Software Technology for “Method to prepare a particulate cathode materials”

Chemical Products – Guoxian Liang, Patrick Charest, Michel Gauthier, Abdelbast Guerfi, Christophe Michot, Karim Zaghib, Johnson Matthey Battery Materials Ltd, Johnson Matthey PLC

Abstract for “Method to prepare a particulate cathode materials”

“A method of preparing an electrode material. The material comprises complex oxide particles with a non-powdery, conductive carbon deposit at least partially their surface. The method includes: grinding the particles into nanometer-sized complex oxide particles or particles from complex oxide precursors. The grinding is done in a beadmill on particles dispersed on a carrier solvent. After adding the organic carbon precursor to the oxide particles, or the oxide particles, and then pyrolyzing the mixture. Selecting the size of particles to grind and the beads used

Background for “Method to prepare a particulate cathode materials”

“Lithium-ion battery have enjoyed a remarkable technical success and rapid commercial growth since their inception. Sony was founded on lithium insertion electrodes, which were essentially the high voltage cobalt dioxide cathode created by J. B. Goodenough, the carbon anode made of coke or graphitized carbonaceous material.

Because of their superior performance in portable electronic applications, lithium-ion battery have gradually replaced Ni?Cd or Ni-MH batteries. Because of their intrinsic instability and cost, particularly in fully charged states, and their low price, small cells have not been commercialized.

“In the middle 90’s Goodenough (See U.S. Patent. Nos. Nos. LiFePO4 for example, was found to be able to insert-deinsert a lithium ion at 3.45 V. This voltage is higher than that of a lithium anode which corresponds to a two-phase reaction. The covalently bound oxygen atom of the phosphate polyanion removes the cathode stability observed in fully charged layers oxides. This makes it an intrinsically safe lithium-ion batteries.

“As Goodenough (U.S. Patent. No. No. One solution was to reduce LiFePO4 particles down to the nanoscale, as well as partial supplementation with iron or phosphate polyanions.

“One significant improvement was made to the problem low electronic conductivity complex metal oxide cathode dust and, more specifically, metal phosphate. This was done by using an organic carbon precursor. It is pyrolysed onto cathode material to increase the electrical field at the level the cathode particles. [Ravet (U.S. Patent. Nos. Nos.

It is also known that it can increase conductivity of a powder phosphate when used as a cathode. This is done by intermingling conductive carbon black with the phosphate or phosphate precursors prior to synthesis. Although this does not produce good connectivity, the addition of carbon blake to graphite powder results in an insufficient attachment of the C to the metal-phosphate crystal stucture. This attachment is essential for maintaining contact despite fluctuations in volume during long term cycling.

“These recent advances have led many battery users and manufacturers to develop safe, mid-sized to large-sized lithium-ion batteries based upon transition metal phosphates. These batteries can be used in portable power tools and Hybrid Electric Vehicles (HEV), Plug-in HEV, and large stationary batteries for energy storage and backup power from intermittent sources.

“Problems still remain, however, to optimize the processability and cost performance especially when power, cyclability or energy are required simultaneously.”

For example, composite electrode optimization requires that Li+ is diffused in a short distance and that there be an electronic conductive phase at each level of the nanoparticles of LiFePO4. Because of their small surfaces and low compaction, manipulation and processing (coating or compacting) elementary nanoparticles is more difficult than processing micron-sized particles. Nanoparticie is a particle with dimensions between 5 nm and submicrons (defined as less that 1.0 m), preferable between 20 and 600nm. These particles can be primary or secondary. A complex oxide is a primary particle. Secondary particles are made of a complex oxide. They may contain other constituents such as C-deposit, carbon bridging, carbon bridging, or particulate or inert phases, or sintering heads. Secondary particles may also be porous.

“The inventors discovered that the use of agglomerates composed of primary and secondary nanoparticles, which are created at a micron scale or greater (by spray drying), facilitates ions, electron diffusion, and the electrochemical reaction. This is due to using nanodimensions at the level the active material nano particles, while still allowing for the ease of manipulating micron size agglomerates.

As a rule, the material that is used to optimize electrochemical performance of such agglomerates nanoparticles and nanocomposite materials must have a high percentage of active metalphosphate, a low amount of electrochemically inert carbon, and a controlled level of open porosity. The pore channel dimensions should be large enough to allow the solvated lithium’s electrolyte to penetrate and reach elementary particles of nano size to support high charge/discharge rate currents.

It is difficult to design such agglomerates from nanoparticles and nanocomposite materials. Also, attaching nanolayers of conductor carbon to single or agglomerated particles internal or exterior surfaces becomes a problem in order not to use too much carbon. This problem is addressed at both the presynthetised metal phosphate phosphates and at the level the metal phosphate precursors.

“It is well known that metal-phosphate agglomerated precursors have a significant impact on the structure of the final lithium metal phosphate product (WO/0227824 & WO/0227823). The majority of commercially available FePO4, 2H2O, which is a precursor to LiFePO4, can be found in a wet chemical process. It contains large dense aggregates with a mean particle diameter of 40-200 mm and fine elementary particles with a mean particle sizes of 0.1-1 millimeter. Large agglomerated precursor particles are required for the synthesis of lithium metalphosphate. This can lead to impurities, large particle sizes and sintered material due to incomplete reactions between reactants.

Pre-synthesis grinding FePO4.2H2O can reduce secondary particles size to microns by jet milling, such as D50 at 2 m and DIOO 10 m. Air jet milled FePO4.2H2O precursor can significantly improve the electrochemical performance and stability of carbonated Li?Fe?phosphate (designated LiFePO4/C). Sintering can still occur within large agglomerates, which limits the power capabilities of an electrode made from said LiFePO4/C.

“It is well known that organic carbon precursors used in the preparation of Li metal phosphate materials do not agglomerate the nanosize FePO4.2H2O FePO4.2H2O particles. This is despite the optimal synthesis temperatures necessary to produce lithium metal phosphate. However, dense or very porosity large particles of agglomerates and aggregates can sinter to a great extent even when an organic precursor has been used (WO/0227824 & WO/0227823). Because of low Li+ diffusion and/or conductive carbon in the particles, dense and large particles made from agglomerates and aggregates reduce the rate performance of final products.

It is crucial to prepare the metal-phosphate precursor in order to obtain well-dispersed fine particles in the sub-micron and nanometer ranges before sintering. Another aspect of the invention is that it is possible to make precursor agglomerates with the correct structure, porosity, and carbon precursor localization using said well-dispersed nano particles. This allows for the creation of optimized agglomerates or nanocomposites. There are many technologies and methods that can be used to create non-agglomerated tine particle depending on the physical properties. If the metalphosphate isn’t made of hard aggregates or agglomerates, then ultrasounds can be used for breaking secondary particles, dispersing the elementary particles, or smaller agglomerates, and stabilizing the liquid suspension with an organic stabilizer or dispersant. Comminuting, also known as grinding or comminuting, is one of the most common processes that allows the production of fine particles and/or de-agglomerate. Recently, commercially available industrial ultra-fine wet grinders have been developed that can reduce the particle size to between 10 and 20 nm. The nano particles can re-agglomerate over time due to strong vander Waals interaction or electric double layer interaction.

There are many processes that can be used to produce lithium metalphosphate or carbon-coated, lithium metalphosphate materials. One is the solid state reaction of different precursors under reducing and inert atmospheres. High purity lithium metalphosphate is dependent on the nature of the reactants and the size of their particles. There are many reaction temperatures and times that can be used depending on these factors. Most cases, the reaction temperature is too high to complete the reaction. Sintered aggregates and sintering necks are also required.

“Wet chemistry methods such as co-precipitation or sol-get synthesizer have been extensively studied to produce homogeneous precursors at atomic level. In principle, a low temperature is required to obtain fine particles of final products. In practice however, segregation of reacting substances occurs. Therefore, longer reaction times or higher temperatures are needed to obtain high crystallinity as well as high purity. This makes it difficult to control the particle size and morphology.

The hydrothermal reaction is one of most efficient methods to synthesize lithium phosphate. Under moderate hydrothermal conditions, it is possible to make lithium metal phosphate particles of various sizes and morphologies. Different shapes and sizes of particles can be made depending on hydrothermal conditions and the precursors used. For example, nano-rods, hexagonal plates, nano-rods, and micron-sized ellipsoids with submicron dimensions. Controlling stoichiometry and crystallinity, phase purity, particle size, and particle size is often a problem.

The bottleneck in scaling up many of the reported processes is the difficulty of controlling particle size, phase purity, and carbon coating. A low sintering temperature will prevent abnormal growth of particles. A higher sintering temperature, however, is required to ensure high phase purity and high carbon conductivity. It is not possible to reach all optimal parameters in one synthesis step.

“In an earlier work, the applicants also created a low-cost synthesis process to prepare one phosphate cathode product. (See WO 2005/062404). However, said process produces solid crystalline ingots and micron-sized powders similar to conventional grinding.

“Grinding, or comminuting, is one of the most common processes that allows the production of fine particles and/or de-agglomerate for ceramic and paint industries. Recently, commercially available industrial wet nanogrinding equipment has been made. This can be used to reduce particle sizes down to 10 to 20% (see WO 2007/100918).

“During wet nanogrinding with isopropyl alcohol solvent and preliminary experiments on pure LiFePO4 obtained from a melting process, inventors came to the conclusion that such mechanical treatment present deleterious effects that impact the use of that pure LiFePO4 cathode material. In fact, nanogrinding LiFePO4 at 20-30 nm produced a 4% reversible capability in a laboratory-cell, instead of the >80% expected. This is discussed in the following example. It was then concluded that wet-nanogrinding a lithium phosphate was altering product. The inventors discovered that 94% of the reversible potential of this nanoground LiFePO4 could be restored after heating a batch. This surprising effect of wet nanogrinding of pure LiFePO4 followed by restoration of electrochemical properties by thermal treatment and carbon deposit by pyrolysis is the main object of this invention.

“The invention provides a method of preparing carbon-deposited cathode materials. This includes a process from molten Lithium Metal phosphates and ingots. It results in a high-performance cathode material.”

“In one aspect, this invention provides a method of preparing complex oxide particle compositions, where the complex oxide particles have non-powdery conductive carbon deposits on at least a portion of their surface. This method involves nanogrinding complex or complex precursor particles, and includes:

Optimizing can be done with a D90 SP to (B), ratio of 1/10 and a D90(FP), ratio of 1000. The preferred beads size ranges between 100-500?m.

“In another aspect, this invention provides a particle mixture. The particle composition consists of particles with a complex oxide core and a deposit of conductive carbon on at least a portion of the core.

“Another aspect of the invention is the use the particle composition in an active electrode material. A nanocomposite material constituting said active electrode material and an electrochemical cell in which at least one electrode contains said nanocomposite material is also involved.”

“The present invention is especially useful in the preparation of a particle mixture wherein the complex oxygen is at least one compound with an olivine structure and formula AmxO4, wherein:

“In a particular embodiment, the aliovalent/isovalent metal other than Fe, Mn or Ni in the complex oxide, is at least one metal from the group consisting Mg, Mo. Nb. Ti, Al. Ta, Ge. Yb. Sm. Ce. Hf. Cr. Zr. Bi. Zn. Ca et. W.”

“Complex oxides LiFe1JVInxPO4, 0,

These lithium transition metal phosphates have all the olivine structure. They tend to behave similarly mechanically upon being ground, especially when they are made through a melting process.

“Furthermore the present invention is useful for preparing a particle composition in which the complex oxide is composed of a titanate with a spinel structure. The formula AaMmOoNnFf is used wherein A is an alkali metallic; M is Ti alone or partially replaced by another metal. The coefficients a, O, m>O and o>0 are chosen to provide electroneutrality to the complex oxide.

“A” is Li, optionally partially replaced by another alkali metallic.

“In a preferred embodiment, the titanate of formala Li4+xTi5O12/Li4+XMgxTi5O12 is used.

“The conductive carbon pre-cursor is preferably a low viscosity compound that is optionally crosslinkable or polymerizable and is capable of wetting, penetration, and adsorbing on reconstituted agglomerates containing nanoparticles of the precursors, complex oxide, or both. Any liquid, solid, or gaseous organic compound which leaves carbon after pyrolysis can be used as a carbon precursor. It can be combined with different functionalities, such as self-adsorbing, lubricant or catalyst and result in one or more products. In order to impregnate the nanoparticle surfaces and the agglomerates, it is best to mix the conductive carbon precursor with complex oxide particles or complex oxide precursor particles. This will allow for the complex oxygen to be in close contact with the carbon deposit after pyrolysis.

The invention’s method preferably includes a further step after grinding and before the pyrolysis. This further step may include conditioning the reaction mixture to adsorb carbon precursor on complex oxide precursors or the complex oxide or to cross-link or polymerize monomer carbon precursors. A further step may be included in the method, which involves aggregating the reaction mixture containing the complex oxide precursor and carbon precursor. You can either flocculate, spray dry, or use the charge effect to agglomerate.

“In a preferred embodiment of the invention, the following steps are included:

“Alternatively, similar pyrolysis can be performed after synthesis and grinding in order to obtain an electrochemically active material. This is i.e. nanosized metalphosphate with a conductive carbon deposit attached to the crystal structure.

“In one embodiment, the method creates a particle composition by starting with compounds that are precursors to the complex oxide LiMPO4. An organic stabilizer agent should be added to the initial particles prior to grinding in this embodiment. To counter the Van der Waals force, the organic stabilizing agent modifies surface charge and increases repulsive force among particles. The dispersion is stabilized and the level of agglomeration is controlled.

“Inventors showed that complex oxide precursors can be nanoground with the carbon precursor to obtain a particle composition according the invention with high-level size and shape properties. These dimensions and shapes are substantially the same as those of nanoground precursor particles. These examples show that nanogrinding is much easier on precursor particles than it is on complex oxide particles. This could be due to the presence of the carbon pre-cursor, which may have a tensioactive effect and can affect other precursors.

“The organic stabilizer agent can be chosen from surfactants, electrostatic or electrosteric stabilirs, dispersant agents, and encapsulant, with many available commercially.”

“The organic stabilizer agent should be selected from compounds that, upon grinding orpyrolyzing do not produce side effects such as toxic gas or compounds that would be harmful to the performance or cyclability an electrochemical cell comprising a particle composition of the invention.”

“Depending on the carbon content, the organic stabilizing agent could also act as a precursor to the conductive carbon.”

“The Li precursor can be chosen from lithium salts like Li2CO3, LiOH and LiH2PO4, Li3PO4, etc.”

“Fe (or equivalent Mn analogs), the precursor can be chosen from FePO4nH2O or Fe3(PO4)2nH2O iron sulphate, different Iron oxides, hydroxides, and iron salts of organic and inorganic compounds.”

“The P precursor can be chosen from derivatives of P2O5 or phosphoric acid, mono or di ammonium phosphate salts, or salts that combine phosphates and polyphosphates with either the Li or Fe precursor.”

“Some of these compounds can be used to make a precursor for more than one element.”

“When the composition of the present invention is made from complex oxide precursor particles,” pyrolysis can be used to convert the adsorbed carbon precursor to conductive carb either before or during the synthesis.

“In one embodiment, the method creates a particle composition starting with complex oxide LiMPO4 particles. This embodiment uses a reactive liquid as the carrier liquid. It is preferably water or alcohol.

The complex oxide can be prepared using well-known prior art methods, such as a solid state reaction with precursors in a reducing or inert environment if M or Fe is present, or in an oxydizing atmosphere (for example ambient air) if Mn is present. This can be done by co-precipitation, sol-gel synthesis or a hydrothermal process. Preferably, the particle size before grinding is between 1 and 50 m. You can also prepare complex oxide by reacting the precursors at low temperatures in an inert atmosphere or reducing environment. The complex oxide is then pre-ground following synthesis and solidification.

The present invention describes particles with a complex oxide core and non-powdery carbon deposits. These particles include elementary nanoparticles as well as micron-sized agglomerates and aggregates of elementary Nanoparticles.

“Elementary particles have dimensions between 5 nm and 1.0?m, preferable between 10 and 600nm. They include primary and secondary nanoparticles.”

“A primary nanoparticle is a compound oxide with or without C.”

A secondary particle is an aggregate or agglomerate of primary particles. It may also contain other constituents such as C-deposit, carbon bridging, particulate carbon or other inert phases or conductive phases. Porosity may also be a characteristic of secondary particles.

“A?aggregate? of elementary nanoparticles” This refers to a micron-sized assembly of elementary nanoparticles held together by chemical or physical interaction by carbon bridges or locally sintered complex oxygen bridges containing a minimum of (0-30%) internal open porosity. An ?agglomerate? An?agglomerate? is a loosely held assembly of particles by low forces. During the grinding process, agglomerates are created continuously. The invention permits the adjustment of this balance through the use of surfactants. This can be done by changing the milling conditions, or by adsorbing the carbon precursor onto the elementary nanoparticles. The carbon precursor is used to encapsulate the elementary nanoparticles. Aggregates are formed by using the precursor to bond elementary nuparticles. These bonds are then converted to carbon upon pyrolysis or sintering neck, to create larger elementary particles. If the surfactant or precursor is not able to penetrate the agglomerate faster, or if the agglomeration is created before the surfactant is able to penetrate the agglomerate, it is possible for one observe a significant sintering of the elementary particles agglomerates into larger particles.

“The conductive carbon deposit is attached in the complex oxide crystal structure as nanosize layers carbon, preferentially graphitized or?graphene? carbon. What is the carbon deposit that is attached to the complex oxygen? This means that the complex oxide crystal and carbon deposit have an intimate contact via chemical or physical bonding. Although it is not a given, it is believed that the pyrolysis mechanism involves radical production. Gaseous species can cause chemical and physical bonding between the sp3C and the PO4 entities. This attached carbon deposit can be used to induce conductivity and homogeneity within the particle’s electrical field, as well as to partially or completely avoid nano particle sintering. Interparticle binding by carbon bridges may be possible if the carbon deposit is large enough to cover the entire surface of complex oxide particles. If only a small portion of the complex dioxide’s surface is covered by carbon deposits, it can allow local sintering of complex oxide nanoparticles. This creates bonded agglomerates with nanoparticles with an open pore structure that allows for solvated lithium penetration in the micron-sized agglomerates.

“It was found that organic carbon precursor pyrolysis mechanism in touch with the transition metal of the complicated oxide allows for the growth at least partially graphitized layers of the complex dioxide crystal in a mechanism which might, though not limitatively involve a gas phase mechanism. You can control the nature, amount, and location of the carbon deposit by choosing the appropriate organic precursor. This is done by the mechanism of adsorption on the surface or precursor particles of complex oxide and by pyrolysing either on the external or internal surfaces of the agglomerates. Depending on the application, the thickness of the carbon deposit can vary from a few nanometers to a few tenths of nm (for example, 0.5 nm-50nm). This is to ensure efficient electronic conduction through the carbon film (in the case of a continuous deposit) or by short distance tunnelling (in the case of a particulate or discontinuous deposit).

The present invention’s particle composition can be used to make an active material for an electrode. The present invention provides an electrode that is composed of a nanocomposite, which can be applied to a current collector. This composite material comprises said particle composition, pores and a binder, and optionally, an agent providing electronic conductivity.

The complex oxide in a particle composition according to the invention is preferably a LiMXO4 or other oxide. The complex oxide in a particle composition that will be used as an anode active material is preferably a titanate.

“In one embodiment, the nanocomposite materials comprises a particle composition according to the invention. At least 50% of the elementary particles have sizes between 5 nm – 900 nm in diameter, and preferably between 10 and 300 nm in size, provided that the nanoparticles are not agglomerated, or sintered. The invention produces particles that are substantially identical in size and shape to the precursor particles of complex oxide if the composition is made from the precursors.

“Another embodiment of the nanocomposite materials comprises a particle composition according to the invention. In this case, the elementary nanoparticles are agglomerated into aggregates with sizes ranging from 0.2 m to 10 m, and preferably from 0.75 m to 5.25 m.”

“In another embodiment, the conductive coal deposit attached to complex oxide crystal structure on the nanoparticle’s surface has a nanoscale thickness.”

“In another embodiment, the carbon conductive is present on a portion of the complex-oxide nanoparticles’ surface, and the nanoparticles of this complex oxide surface are sintered.”

“In another embodiment, where the majority of the surface of complex oxide nanoparticles has been covered with conductive carbon deposits, the nanoparticles can be aggregated via carbon bridges.

“Another embodiment of the nanocomposite materials contains at least one binder or an electronic conduction additive. Preferably, the binder is a fluorinated, partially fluorinated, elastomer, water, or an organic, soluble, or dispersable binder, including latex. The electron conduction additon, is selected from the group consisting carbons, carbon blacks and graphite. Other cathode materials may also contain nanoparticles.

“A further embodiment of the nanocomposite materials contains secondary particles or agglomerates elementary nanoparticles. It has an open porosity and a volumetric fraction of pores that ranges from 0.30 to0.05, preferentially from 0.0.2 to 0.1.”

“In another embodiment, the deposit of conductive carbon is at least partially graphitized carbon that has been obtained by pyrolysis from an organic carbon precursor that contains elements like N, P and Si that can be covalently bonded to carbon.”

“The invention of nano-sized particles and agglomerates coated with conductive carbon at a nanoscale makes such molten process feasible for high power cathode material.”

“The invention addresses the preparation of complex oxide-carbon cathode material in which a conductive Carbon is chemically linked to the complex crystal structure of the complex dioxide. This is done by pyrolysing an organ carbon precursor in close contact with nanoparticles, nanocomposite aggregates of either the complex or precursor. Preferably by an adsoption or chemical linkage process.”

To control the characteristics of the invention’s particle composition, it is possible to make a suitable selection about the quantity, nature, thickness, and distribution of said carbonaceous deposits. Nanoparticle sintering, for example, can be avoided by leaving open porosity among nanoparticles within the aggregates. On the other hand, partial bridging can be achieved by allowing interparticle sintering to occur or by creating inter-nano particle carbon bridges.

“In one preferred method of realization, nanoparticle suspensions can be obtained by micromedia beads mill grinding or deagglomeration a suspension solid particles of complex oxide or complex oxide precursor in liquid media.”

“The organic carbon precursor should be preferably chosen from organic compounds that are capable of forming conductive carbon deposits upon pyrolysis in presence of complex oxides or precursors thereof. It must also be able to wet, impregnate and preferably encapsulate the complex oxide’s surface or its precursor in order to:

“The organic carbon precursor can be selected from high-carbon surfactants and crosslinkable monomers, oligomers, polymers, or copolymers (especially block copolymers), as well as oligomers or crosslinkable monomers. It is also possible to make liquid organic compounds in solutions or solid organic compounds. The organic precursor can be used to combine more than one function of the C-source function. It can also be used as a surfactant or stabilizer.

There are many products that can be used to stabilize organic molecules. These include surface active agents, also known as surfactants. It is important to use registered stabilizers that are low-cost. These organic compounds include an amphiphilic component that is either ionic or not ionic. They also contain a hydrophilic portion which allows modification of particle/solvent surface tension, wetabiity, and more efficient dispersion. These products and their mixtures are often identified by their HLB number, which indicates the balance between hydrophilic and hydrophobic moieties. Stepan Global Product Catalog contains a large number of surfactants, which is incorporated by reference. You can also find many more from specialty chemical manufacturers around the world.

“The surfactant can be chosen from various fatty acids (for example, oleic acid, or lithium oleate), or fatty acids esters, alkoxylated alcohols or amines.

Esterification can be used to make fatty acid esters surfactants. Numerous cost-effective combinations exist, allowing for fine-tuning of surfactants properties in terms of solubility/insolubility in various solvents, dispersibility of submicron or nanosize complex oxide cathode material. The main advantage of fatty acids esters is their ability to be used as carbon precursors. This allows for the formation of high-quality carbon deposits after pyrolysis of the fat acid chains. The esterification of fatty acids with glycol products (glycerol and glymes) is the main method to obtain non-ionic fatty oils. . . ()? The carbonization ratio is dependent on the fatty acids content, surfactant and fatty acid weight. Low carbonization ratios and the generation of large amounts of ashes during carbonization are avoided by using fatty acids with molecular weights greater than 250. You can mention caprylate, undecylenate and palmitate as well as laurate. Myristate, oleate. ricinoleate. linoleate. linolenate. and stearate. If safety and handling are considered, oleate or stearate, as well as linoleate, pilenate, linolenate and ricinoleate, are preferred. Glycerol monooleate and monostearate may be of interest if there is high carbonization. The solubility properties of fatty acids with the same amount carbon can be affected by the presence of insaturation. Glycerol monooleate, for example, is soluble in isopropyl ethanol (IPA), whereas glycerol monstearate is not. Glycerol monostearate has a lower solubility when it is processed using high-shear, particularly in bead mills following the invention. This high-energy mixing allows for homogeneous dispersion of low-solubility glycerol Monostearate in IPA. It is further stabilized through adsorption onto complex oxide particles. Optimization of surfactant formulation is also easily obtained by esterification of fatty acid with glyines to produce surfactants such as the following oleate derivatives Ci7H33-COO(CH2CH2O)2OH or C17H33-COO(CH2CH2O)9OOC?C17H33.”

“Length of the glyme part and choice of the fatty acid allow preparation of surfactant with suitable HLB value and desirable inciting point, boiling point, solubility/insolubility, wettability in carrier solvent in view to obtain high quality carbon coating after pyrolysis. From an industrial perspective, it is important to remember that optimization of formulation can be done at almost constant cost for a cost-effective solution.

“Tall oil, which is often a byproduct of wood pulp manufacturing, is an interesting source for fatty acid derivatives. Particularly grades obtained by fractional distillation tall oleic acid rosin and further distillation tall oleic acid fatty acid are a low-cost source of fatty acids. Many suppliers offer tall oil and tall oil fat acids, such as Arizona Chemical. They also come in ester with glycerol (or glymes).

“In one embodiment, a fatty acids salt of a transitional metal cation is used to act as the surfactant, and an organic carbon precursor is used. The carbon deposit generated by pyrolysis takes the form of carbon nanotubes. The catalyst for nanotube formation is the transition metal cation. Preferably, the transition metal is Ni, Co, or Fe. Preferably, the fatty acid has at least 6 carbon atoms. More preferably, it should have at least 10, and most importantly, 14. Preferably, the fatty acid is selected from stearate or oleate. J. describes the use of nickel-stearate to make precursors for carbon in nanotubes precursors. Mater. Chem., 2005, 15, 844-849, which. The solubility of a salt can easily be adjusted by selecting the right fatty acid in the fatty salt of a transitional metal.

Stepan Company stocks fatty alcohol sulfate and phosphate esters. The preferred phosphate esters in the invention are the phosphate esters. Particular attention should be paid to Degussa’s styreneoxide-based, phosphorylated polyether and the following formula.

“”

Degussa sells “Imidazolium based surfactants and quaternary ammonium-based surfactants” under the tradename Tego Dispersant.

“”

“Polyanhydride resins are produced by the alternate copolymerization maleic anhydride and an alkylene. They are an important class of compounds that can be used as surfactant or carbon precursor. Of particular interest is poly(maleic anhydride-alt-1-octadecene) produce by Chevron Phillips Chemical Company. Due to isopropanol esterification of anyhydride by isopropanol, this high molecular weight polymer can be dissolved in IPA.

“Reactive surfactants, also known as?Surfmer?”, are non-ionic cationic and anionic compounds. (See Acta Polym 95. 49. 671). ?Reactive surfactant? A surfactant that contains a reactive surfactant. The following formulae are examples of typical compounds:

“”

“Noigen can be purchased from DKS Japan and Hitenol from DKS Japan. Uniquama also offers Maxemul, which is a trade name for other suitable compounds. Reactive surfactants can be used in whole or part to induc nano-encapsulation. These additives can be used at the end to encapsulate nanopowder in a particular embodiment of the invention.

The above industrial compounds combined with a grinding to reduce particle sizes allow optimization of the production process of battery grade nanosize or submicron carbon-coated complex oxide, especially LiFePO4, in terms of cost-effectiveness and safety (low hazard and low VOC), . . ). Preferably, the organic precursors will form a thin carbon deposit on a nanoscale scale that is in close contact with the complex oxide crystal structure. This will then be graphitized during pyrolysis. After pyrolysis, the organic precursor could contain elements like N, P and Si.

These organic precursors can be found in the gas phase at least in equilibrium with the surface distributed organic precursor. This allows for the growth of graphite or graphene on the surface. To promote graphene deposit or graphitic nature, iron, cobalt, or nickel catalysts can be added to the pyrolysis step. You can also introduce and distribute the metal catalyst as a metal containing surfactant like Fe, Co, Ni stearate/oleate.”

“Preferably, the nature, distribution and quantity of organic precursor or carbon deposit after pyrolysis is adjusted to prevent nanoparticle sintering (by Carbon Coating or partial sintering using limited carbon quantities), on complex oxide particles or to form interparticle carbon Bridges at the nanoscale.

“Thermal treatment encourages the sintering primary nanoparticles within an aggregate of nanoparticles, thereby generating secondary particles. The nature of the solvent, concentrations, organic precursor property (adsorbed, not) and thermal or pyrolysis process all influence the size of these secondary particles. Sometimes, aggregates are porosity- or spherical depending on the extent of sintering. These aggregates may retain the primary nanoparticle form or only a portion of it, such as the C-deposit and some open or close pores. The invention shows that both the final synthesized product and the metal precursor can be processed if the particles have been properly coated with carbonaceous deposits.

“The following examples illustrate the present invention more practically, but they do not limit it in any way.”

“All examples were performed with a wet grinder machine from NETZSCH, Inc. (Z model LABSTAR LS 1)”

Summary for “Method to prepare a particulate cathode materials”

“Lithium-ion battery have enjoyed a remarkable technical success and rapid commercial growth since their inception. Sony was founded on lithium insertion electrodes, which were essentially the high voltage cobalt dioxide cathode created by J. B. Goodenough, the carbon anode made of coke or graphitized carbonaceous material.

Because of their superior performance in portable electronic applications, lithium-ion battery have gradually replaced Ni?Cd or Ni-MH batteries. Because of their intrinsic instability and cost, particularly in fully charged states, and their low price, small cells have not been commercialized.

“In the middle 90’s Goodenough (See U.S. Patent. Nos. Nos. LiFePO4 for example, was found to be able to insert-deinsert a lithium ion at 3.45 V. This voltage is higher than that of a lithium anode which corresponds to a two-phase reaction. The covalently bound oxygen atom of the phosphate polyanion removes the cathode stability observed in fully charged layers oxides. This makes it an intrinsically safe lithium-ion batteries.

“As Goodenough (U.S. Patent. No. No. One solution was to reduce LiFePO4 particles down to the nanoscale, as well as partial supplementation with iron or phosphate polyanions.

“One significant improvement was made to the problem low electronic conductivity complex metal oxide cathode dust and, more specifically, metal phosphate. This was done by using an organic carbon precursor. It is pyrolysed onto cathode material to increase the electrical field at the level the cathode particles. [Ravet (U.S. Patent. Nos. Nos.

It is also known that it can increase conductivity of a powder phosphate when used as a cathode. This is done by intermingling conductive carbon black with the phosphate or phosphate precursors prior to synthesis. Although this does not produce good connectivity, the addition of carbon blake to graphite powder results in an insufficient attachment of the C to the metal-phosphate crystal stucture. This attachment is essential for maintaining contact despite fluctuations in volume during long term cycling.

“These recent advances have led many battery users and manufacturers to develop safe, mid-sized to large-sized lithium-ion batteries based upon transition metal phosphates. These batteries can be used in portable power tools and Hybrid Electric Vehicles (HEV), Plug-in HEV, and large stationary batteries for energy storage and backup power from intermittent sources.

“Problems still remain, however, to optimize the processability and cost performance especially when power, cyclability or energy are required simultaneously.”

For example, composite electrode optimization requires that Li+ is diffused in a short distance and that there be an electronic conductive phase at each level of the nanoparticles of LiFePO4. Because of their small surfaces and low compaction, manipulation and processing (coating or compacting) elementary nanoparticles is more difficult than processing micron-sized particles. Nanoparticie is a particle with dimensions between 5 nm and submicrons (defined as less that 1.0 m), preferable between 20 and 600nm. These particles can be primary or secondary. A complex oxide is a primary particle. Secondary particles are made of a complex oxide. They may contain other constituents such as C-deposit, carbon bridging, carbon bridging, or particulate or inert phases, or sintering heads. Secondary particles may also be porous.

“The inventors discovered that the use of agglomerates composed of primary and secondary nanoparticles, which are created at a micron scale or greater (by spray drying), facilitates ions, electron diffusion, and the electrochemical reaction. This is due to using nanodimensions at the level the active material nano particles, while still allowing for the ease of manipulating micron size agglomerates.

As a rule, the material that is used to optimize electrochemical performance of such agglomerates nanoparticles and nanocomposite materials must have a high percentage of active metalphosphate, a low amount of electrochemically inert carbon, and a controlled level of open porosity. The pore channel dimensions should be large enough to allow the solvated lithium’s electrolyte to penetrate and reach elementary particles of nano size to support high charge/discharge rate currents.

It is difficult to design such agglomerates from nanoparticles and nanocomposite materials. Also, attaching nanolayers of conductor carbon to single or agglomerated particles internal or exterior surfaces becomes a problem in order not to use too much carbon. This problem is addressed at both the presynthetised metal phosphate phosphates and at the level the metal phosphate precursors.

“It is well known that metal-phosphate agglomerated precursors have a significant impact on the structure of the final lithium metal phosphate product (WO/0227824 & WO/0227823). The majority of commercially available FePO4, 2H2O, which is a precursor to LiFePO4, can be found in a wet chemical process. It contains large dense aggregates with a mean particle diameter of 40-200 mm and fine elementary particles with a mean particle sizes of 0.1-1 millimeter. Large agglomerated precursor particles are required for the synthesis of lithium metalphosphate. This can lead to impurities, large particle sizes and sintered material due to incomplete reactions between reactants.

Pre-synthesis grinding FePO4.2H2O can reduce secondary particles size to microns by jet milling, such as D50 at 2 m and DIOO 10 m. Air jet milled FePO4.2H2O precursor can significantly improve the electrochemical performance and stability of carbonated Li?Fe?phosphate (designated LiFePO4/C). Sintering can still occur within large agglomerates, which limits the power capabilities of an electrode made from said LiFePO4/C.

“It is well known that organic carbon precursors used in the preparation of Li metal phosphate materials do not agglomerate the nanosize FePO4.2H2O FePO4.2H2O particles. This is despite the optimal synthesis temperatures necessary to produce lithium metal phosphate. However, dense or very porosity large particles of agglomerates and aggregates can sinter to a great extent even when an organic precursor has been used (WO/0227824 & WO/0227823). Because of low Li+ diffusion and/or conductive carbon in the particles, dense and large particles made from agglomerates and aggregates reduce the rate performance of final products.

It is crucial to prepare the metal-phosphate precursor in order to obtain well-dispersed fine particles in the sub-micron and nanometer ranges before sintering. Another aspect of the invention is that it is possible to make precursor agglomerates with the correct structure, porosity, and carbon precursor localization using said well-dispersed nano particles. This allows for the creation of optimized agglomerates or nanocomposites. There are many technologies and methods that can be used to create non-agglomerated tine particle depending on the physical properties. If the metalphosphate isn’t made of hard aggregates or agglomerates, then ultrasounds can be used for breaking secondary particles, dispersing the elementary particles, or smaller agglomerates, and stabilizing the liquid suspension with an organic stabilizer or dispersant. Comminuting, also known as grinding or comminuting, is one of the most common processes that allows the production of fine particles and/or de-agglomerate. Recently, commercially available industrial ultra-fine wet grinders have been developed that can reduce the particle size to between 10 and 20 nm. The nano particles can re-agglomerate over time due to strong vander Waals interaction or electric double layer interaction.

There are many processes that can be used to produce lithium metalphosphate or carbon-coated, lithium metalphosphate materials. One is the solid state reaction of different precursors under reducing and inert atmospheres. High purity lithium metalphosphate is dependent on the nature of the reactants and the size of their particles. There are many reaction temperatures and times that can be used depending on these factors. Most cases, the reaction temperature is too high to complete the reaction. Sintered aggregates and sintering necks are also required.

“Wet chemistry methods such as co-precipitation or sol-get synthesizer have been extensively studied to produce homogeneous precursors at atomic level. In principle, a low temperature is required to obtain fine particles of final products. In practice however, segregation of reacting substances occurs. Therefore, longer reaction times or higher temperatures are needed to obtain high crystallinity as well as high purity. This makes it difficult to control the particle size and morphology.

The hydrothermal reaction is one of most efficient methods to synthesize lithium phosphate. Under moderate hydrothermal conditions, it is possible to make lithium metal phosphate particles of various sizes and morphologies. Different shapes and sizes of particles can be made depending on hydrothermal conditions and the precursors used. For example, nano-rods, hexagonal plates, nano-rods, and micron-sized ellipsoids with submicron dimensions. Controlling stoichiometry and crystallinity, phase purity, particle size, and particle size is often a problem.

The bottleneck in scaling up many of the reported processes is the difficulty of controlling particle size, phase purity, and carbon coating. A low sintering temperature will prevent abnormal growth of particles. A higher sintering temperature, however, is required to ensure high phase purity and high carbon conductivity. It is not possible to reach all optimal parameters in one synthesis step.

“In an earlier work, the applicants also created a low-cost synthesis process to prepare one phosphate cathode product. (See WO 2005/062404). However, said process produces solid crystalline ingots and micron-sized powders similar to conventional grinding.

“Grinding, or comminuting, is one of the most common processes that allows the production of fine particles and/or de-agglomerate for ceramic and paint industries. Recently, commercially available industrial wet nanogrinding equipment has been made. This can be used to reduce particle sizes down to 10 to 20% (see WO 2007/100918).

“During wet nanogrinding with isopropyl alcohol solvent and preliminary experiments on pure LiFePO4 obtained from a melting process, inventors came to the conclusion that such mechanical treatment present deleterious effects that impact the use of that pure LiFePO4 cathode material. In fact, nanogrinding LiFePO4 at 20-30 nm produced a 4% reversible capability in a laboratory-cell, instead of the >80% expected. This is discussed in the following example. It was then concluded that wet-nanogrinding a lithium phosphate was altering product. The inventors discovered that 94% of the reversible potential of this nanoground LiFePO4 could be restored after heating a batch. This surprising effect of wet nanogrinding of pure LiFePO4 followed by restoration of electrochemical properties by thermal treatment and carbon deposit by pyrolysis is the main object of this invention.

“The invention provides a method of preparing carbon-deposited cathode materials. This includes a process from molten Lithium Metal phosphates and ingots. It results in a high-performance cathode material.”

“In one aspect, this invention provides a method of preparing complex oxide particle compositions, where the complex oxide particles have non-powdery conductive carbon deposits on at least a portion of their surface. This method involves nanogrinding complex or complex precursor particles, and includes:

Optimizing can be done with a D90 SP to (B), ratio of 1/10 and a D90(FP), ratio of 1000. The preferred beads size ranges between 100-500?m.

“In another aspect, this invention provides a particle mixture. The particle composition consists of particles with a complex oxide core and a deposit of conductive carbon on at least a portion of the core.

“Another aspect of the invention is the use the particle composition in an active electrode material. A nanocomposite material constituting said active electrode material and an electrochemical cell in which at least one electrode contains said nanocomposite material is also involved.”

“The present invention is especially useful in the preparation of a particle mixture wherein the complex oxygen is at least one compound with an olivine structure and formula AmxO4, wherein:

“In a particular embodiment, the aliovalent/isovalent metal other than Fe, Mn or Ni in the complex oxide, is at least one metal from the group consisting Mg, Mo. Nb. Ti, Al. Ta, Ge. Yb. Sm. Ce. Hf. Cr. Zr. Bi. Zn. Ca et. W.”

“Complex oxides LiFe1JVInxPO4, 0,

These lithium transition metal phosphates have all the olivine structure. They tend to behave similarly mechanically upon being ground, especially when they are made through a melting process.

“Furthermore the present invention is useful for preparing a particle composition in which the complex oxide is composed of a titanate with a spinel structure. The formula AaMmOoNnFf is used wherein A is an alkali metallic; M is Ti alone or partially replaced by another metal. The coefficients a, O, m>O and o>0 are chosen to provide electroneutrality to the complex oxide.

“A” is Li, optionally partially replaced by another alkali metallic.

“In a preferred embodiment, the titanate of formala Li4+xTi5O12/Li4+XMgxTi5O12 is used.

“The conductive carbon pre-cursor is preferably a low viscosity compound that is optionally crosslinkable or polymerizable and is capable of wetting, penetration, and adsorbing on reconstituted agglomerates containing nanoparticles of the precursors, complex oxide, or both. Any liquid, solid, or gaseous organic compound which leaves carbon after pyrolysis can be used as a carbon precursor. It can be combined with different functionalities, such as self-adsorbing, lubricant or catalyst and result in one or more products. In order to impregnate the nanoparticle surfaces and the agglomerates, it is best to mix the conductive carbon precursor with complex oxide particles or complex oxide precursor particles. This will allow for the complex oxygen to be in close contact with the carbon deposit after pyrolysis.

The invention’s method preferably includes a further step after grinding and before the pyrolysis. This further step may include conditioning the reaction mixture to adsorb carbon precursor on complex oxide precursors or the complex oxide or to cross-link or polymerize monomer carbon precursors. A further step may be included in the method, which involves aggregating the reaction mixture containing the complex oxide precursor and carbon precursor. You can either flocculate, spray dry, or use the charge effect to agglomerate.

“In a preferred embodiment of the invention, the following steps are included:

“Alternatively, similar pyrolysis can be performed after synthesis and grinding in order to obtain an electrochemically active material. This is i.e. nanosized metalphosphate with a conductive carbon deposit attached to the crystal structure.

“In one embodiment, the method creates a particle composition by starting with compounds that are precursors to the complex oxide LiMPO4. An organic stabilizer agent should be added to the initial particles prior to grinding in this embodiment. To counter the Van der Waals force, the organic stabilizing agent modifies surface charge and increases repulsive force among particles. The dispersion is stabilized and the level of agglomeration is controlled.

“Inventors showed that complex oxide precursors can be nanoground with the carbon precursor to obtain a particle composition according the invention with high-level size and shape properties. These dimensions and shapes are substantially the same as those of nanoground precursor particles. These examples show that nanogrinding is much easier on precursor particles than it is on complex oxide particles. This could be due to the presence of the carbon pre-cursor, which may have a tensioactive effect and can affect other precursors.

“The organic stabilizer agent can be chosen from surfactants, electrostatic or electrosteric stabilirs, dispersant agents, and encapsulant, with many available commercially.”

“The organic stabilizer agent should be selected from compounds that, upon grinding orpyrolyzing do not produce side effects such as toxic gas or compounds that would be harmful to the performance or cyclability an electrochemical cell comprising a particle composition of the invention.”

“Depending on the carbon content, the organic stabilizing agent could also act as a precursor to the conductive carbon.”

“The Li precursor can be chosen from lithium salts like Li2CO3, LiOH and LiH2PO4, Li3PO4, etc.”

“Fe (or equivalent Mn analogs), the precursor can be chosen from FePO4nH2O or Fe3(PO4)2nH2O iron sulphate, different Iron oxides, hydroxides, and iron salts of organic and inorganic compounds.”

“The P precursor can be chosen from derivatives of P2O5 or phosphoric acid, mono or di ammonium phosphate salts, or salts that combine phosphates and polyphosphates with either the Li or Fe precursor.”

“Some of these compounds can be used to make a precursor for more than one element.”

“When the composition of the present invention is made from complex oxide precursor particles,” pyrolysis can be used to convert the adsorbed carbon precursor to conductive carb either before or during the synthesis.

“In one embodiment, the method creates a particle composition starting with complex oxide LiMPO4 particles. This embodiment uses a reactive liquid as the carrier liquid. It is preferably water or alcohol.

The complex oxide can be prepared using well-known prior art methods, such as a solid state reaction with precursors in a reducing or inert environment if M or Fe is present, or in an oxydizing atmosphere (for example ambient air) if Mn is present. This can be done by co-precipitation, sol-gel synthesis or a hydrothermal process. Preferably, the particle size before grinding is between 1 and 50 m. You can also prepare complex oxide by reacting the precursors at low temperatures in an inert atmosphere or reducing environment. The complex oxide is then pre-ground following synthesis and solidification.

The present invention describes particles with a complex oxide core and non-powdery carbon deposits. These particles include elementary nanoparticles as well as micron-sized agglomerates and aggregates of elementary Nanoparticles.

“Elementary particles have dimensions between 5 nm and 1.0?m, preferable between 10 and 600nm. They include primary and secondary nanoparticles.”

“A primary nanoparticle is a compound oxide with or without C.”

A secondary particle is an aggregate or agglomerate of primary particles. It may also contain other constituents such as C-deposit, carbon bridging, particulate carbon or other inert phases or conductive phases. Porosity may also be a characteristic of secondary particles.

“A?aggregate? of elementary nanoparticles” This refers to a micron-sized assembly of elementary nanoparticles held together by chemical or physical interaction by carbon bridges or locally sintered complex oxygen bridges containing a minimum of (0-30%) internal open porosity. An ?agglomerate? An?agglomerate? is a loosely held assembly of particles by low forces. During the grinding process, agglomerates are created continuously. The invention permits the adjustment of this balance through the use of surfactants. This can be done by changing the milling conditions, or by adsorbing the carbon precursor onto the elementary nanoparticles. The carbon precursor is used to encapsulate the elementary nanoparticles. Aggregates are formed by using the precursor to bond elementary nuparticles. These bonds are then converted to carbon upon pyrolysis or sintering neck, to create larger elementary particles. If the surfactant or precursor is not able to penetrate the agglomerate faster, or if the agglomeration is created before the surfactant is able to penetrate the agglomerate, it is possible for one observe a significant sintering of the elementary particles agglomerates into larger particles.

“The conductive carbon deposit is attached in the complex oxide crystal structure as nanosize layers carbon, preferentially graphitized or?graphene? carbon. What is the carbon deposit that is attached to the complex oxygen? This means that the complex oxide crystal and carbon deposit have an intimate contact via chemical or physical bonding. Although it is not a given, it is believed that the pyrolysis mechanism involves radical production. Gaseous species can cause chemical and physical bonding between the sp3C and the PO4 entities. This attached carbon deposit can be used to induce conductivity and homogeneity within the particle’s electrical field, as well as to partially or completely avoid nano particle sintering. Interparticle binding by carbon bridges may be possible if the carbon deposit is large enough to cover the entire surface of complex oxide particles. If only a small portion of the complex dioxide’s surface is covered by carbon deposits, it can allow local sintering of complex oxide nanoparticles. This creates bonded agglomerates with nanoparticles with an open pore structure that allows for solvated lithium penetration in the micron-sized agglomerates.

“It was found that organic carbon precursor pyrolysis mechanism in touch with the transition metal of the complicated oxide allows for the growth at least partially graphitized layers of the complex dioxide crystal in a mechanism which might, though not limitatively involve a gas phase mechanism. You can control the nature, amount, and location of the carbon deposit by choosing the appropriate organic precursor. This is done by the mechanism of adsorption on the surface or precursor particles of complex oxide and by pyrolysing either on the external or internal surfaces of the agglomerates. Depending on the application, the thickness of the carbon deposit can vary from a few nanometers to a few tenths of nm (for example, 0.5 nm-50nm). This is to ensure efficient electronic conduction through the carbon film (in the case of a continuous deposit) or by short distance tunnelling (in the case of a particulate or discontinuous deposit).

The present invention’s particle composition can be used to make an active material for an electrode. The present invention provides an electrode that is composed of a nanocomposite, which can be applied to a current collector. This composite material comprises said particle composition, pores and a binder, and optionally, an agent providing electronic conductivity.

The complex oxide in a particle composition according to the invention is preferably a LiMXO4 or other oxide. The complex oxide in a particle composition that will be used as an anode active material is preferably a titanate.

“In one embodiment, the nanocomposite materials comprises a particle composition according to the invention. At least 50% of the elementary particles have sizes between 5 nm – 900 nm in diameter, and preferably between 10 and 300 nm in size, provided that the nanoparticles are not agglomerated, or sintered. The invention produces particles that are substantially identical in size and shape to the precursor particles of complex oxide if the composition is made from the precursors.

“Another embodiment of the nanocomposite materials comprises a particle composition according to the invention. In this case, the elementary nanoparticles are agglomerated into aggregates with sizes ranging from 0.2 m to 10 m, and preferably from 0.75 m to 5.25 m.”

“In another embodiment, the conductive coal deposit attached to complex oxide crystal structure on the nanoparticle’s surface has a nanoscale thickness.”

“In another embodiment, the carbon conductive is present on a portion of the complex-oxide nanoparticles’ surface, and the nanoparticles of this complex oxide surface are sintered.”

“In another embodiment, where the majority of the surface of complex oxide nanoparticles has been covered with conductive carbon deposits, the nanoparticles can be aggregated via carbon bridges.

“Another embodiment of the nanocomposite materials contains at least one binder or an electronic conduction additive. Preferably, the binder is a fluorinated, partially fluorinated, elastomer, water, or an organic, soluble, or dispersable binder, including latex. The electron conduction additon, is selected from the group consisting carbons, carbon blacks and graphite. Other cathode materials may also contain nanoparticles.

“A further embodiment of the nanocomposite materials contains secondary particles or agglomerates elementary nanoparticles. It has an open porosity and a volumetric fraction of pores that ranges from 0.30 to0.05, preferentially from 0.0.2 to 0.1.”

“In another embodiment, the deposit of conductive carbon is at least partially graphitized carbon that has been obtained by pyrolysis from an organic carbon precursor that contains elements like N, P and Si that can be covalently bonded to carbon.”

“The invention of nano-sized particles and agglomerates coated with conductive carbon at a nanoscale makes such molten process feasible for high power cathode material.”

“The invention addresses the preparation of complex oxide-carbon cathode material in which a conductive Carbon is chemically linked to the complex crystal structure of the complex dioxide. This is done by pyrolysing an organ carbon precursor in close contact with nanoparticles, nanocomposite aggregates of either the complex or precursor. Preferably by an adsoption or chemical linkage process.”

To control the characteristics of the invention’s particle composition, it is possible to make a suitable selection about the quantity, nature, thickness, and distribution of said carbonaceous deposits. Nanoparticle sintering, for example, can be avoided by leaving open porosity among nanoparticles within the aggregates. On the other hand, partial bridging can be achieved by allowing interparticle sintering to occur or by creating inter-nano particle carbon bridges.

“In one preferred method of realization, nanoparticle suspensions can be obtained by micromedia beads mill grinding or deagglomeration a suspension solid particles of complex oxide or complex oxide precursor in liquid media.”

“The organic carbon precursor should be preferably chosen from organic compounds that are capable of forming conductive carbon deposits upon pyrolysis in presence of complex oxides or precursors thereof. It must also be able to wet, impregnate and preferably encapsulate the complex oxide’s surface or its precursor in order to:

“The organic carbon precursor can be selected from high-carbon surfactants and crosslinkable monomers, oligomers, polymers, or copolymers (especially block copolymers), as well as oligomers or crosslinkable monomers. It is also possible to make liquid organic compounds in solutions or solid organic compounds. The organic precursor can be used to combine more than one function of the C-source function. It can also be used as a surfactant or stabilizer.

There are many products that can be used to stabilize organic molecules. These include surface active agents, also known as surfactants. It is important to use registered stabilizers that are low-cost. These organic compounds include an amphiphilic component that is either ionic or not ionic. They also contain a hydrophilic portion which allows modification of particle/solvent surface tension, wetabiity, and more efficient dispersion. These products and their mixtures are often identified by their HLB number, which indicates the balance between hydrophilic and hydrophobic moieties. Stepan Global Product Catalog contains a large number of surfactants, which is incorporated by reference. You can also find many more from specialty chemical manufacturers around the world.

“The surfactant can be chosen from various fatty acids (for example, oleic acid, or lithium oleate), or fatty acids esters, alkoxylated alcohols or amines.

Esterification can be used to make fatty acid esters surfactants. Numerous cost-effective combinations exist, allowing for fine-tuning of surfactants properties in terms of solubility/insolubility in various solvents, dispersibility of submicron or nanosize complex oxide cathode material. The main advantage of fatty acids esters is their ability to be used as carbon precursors. This allows for the formation of high-quality carbon deposits after pyrolysis of the fat acid chains. The esterification of fatty acids with glycol products (glycerol and glymes) is the main method to obtain non-ionic fatty oils. . . ()? The carbonization ratio is dependent on the fatty acids content, surfactant and fatty acid weight. Low carbonization ratios and the generation of large amounts of ashes during carbonization are avoided by using fatty acids with molecular weights greater than 250. You can mention caprylate, undecylenate and palmitate as well as laurate. Myristate, oleate. ricinoleate. linoleate. linolenate. and stearate. If safety and handling are considered, oleate or stearate, as well as linoleate, pilenate, linolenate and ricinoleate, are preferred. Glycerol monooleate and monostearate may be of interest if there is high carbonization. The solubility properties of fatty acids with the same amount carbon can be affected by the presence of insaturation. Glycerol monooleate, for example, is soluble in isopropyl ethanol (IPA), whereas glycerol monstearate is not. Glycerol monostearate has a lower solubility when it is processed using high-shear, particularly in bead mills following the invention. This high-energy mixing allows for homogeneous dispersion of low-solubility glycerol Monostearate in IPA. It is further stabilized through adsorption onto complex oxide particles. Optimization of surfactant formulation is also easily obtained by esterification of fatty acid with glyines to produce surfactants such as the following oleate derivatives Ci7H33-COO(CH2CH2O)2OH or C17H33-COO(CH2CH2O)9OOC?C17H33.”

“Length of the glyme part and choice of the fatty acid allow preparation of surfactant with suitable HLB value and desirable inciting point, boiling point, solubility/insolubility, wettability in carrier solvent in view to obtain high quality carbon coating after pyrolysis. From an industrial perspective, it is important to remember that optimization of formulation can be done at almost constant cost for a cost-effective solution.

“Tall oil, which is often a byproduct of wood pulp manufacturing, is an interesting source for fatty acid derivatives. Particularly grades obtained by fractional distillation tall oleic acid rosin and further distillation tall oleic acid fatty acid are a low-cost source of fatty acids. Many suppliers offer tall oil and tall oil fat acids, such as Arizona Chemical. They also come in ester with glycerol (or glymes).

“In one embodiment, a fatty acids salt of a transitional metal cation is used to act as the surfactant, and an organic carbon precursor is used. The carbon deposit generated by pyrolysis takes the form of carbon nanotubes. The catalyst for nanotube formation is the transition metal cation. Preferably, the transition metal is Ni, Co, or Fe. Preferably, the fatty acid has at least 6 carbon atoms. More preferably, it should have at least 10, and most importantly, 14. Preferably, the fatty acid is selected from stearate or oleate. J. describes the use of nickel-stearate to make precursors for carbon in nanotubes precursors. Mater. Chem., 2005, 15, 844-849, which. The solubility of a salt can easily be adjusted by selecting the right fatty acid in the fatty salt of a transitional metal.

Stepan Company stocks fatty alcohol sulfate and phosphate esters. The preferred phosphate esters in the invention are the phosphate esters. Particular attention should be paid to Degussa’s styreneoxide-based, phosphorylated polyether and the following formula.

“”

Degussa sells “Imidazolium based surfactants and quaternary ammonium-based surfactants” under the tradename Tego Dispersant.

“”

“Polyanhydride resins are produced by the alternate copolymerization maleic anhydride and an alkylene. They are an important class of compounds that can be used as surfactant or carbon precursor. Of particular interest is poly(maleic anhydride-alt-1-octadecene) produce by Chevron Phillips Chemical Company. Due to isopropanol esterification of anyhydride by isopropanol, this high molecular weight polymer can be dissolved in IPA.

“Reactive surfactants, also known as?Surfmer?”, are non-ionic cationic and anionic compounds. (See Acta Polym 95. 49. 671). ?Reactive surfactant? A surfactant that contains a reactive surfactant. The following formulae are examples of typical compounds:

“”

“Noigen can be purchased from DKS Japan and Hitenol from DKS Japan. Uniquama also offers Maxemul, which is a trade name for other suitable compounds. Reactive surfactants can be used in whole or part to induc nano-encapsulation. These additives can be used at the end to encapsulate nanopowder in a particular embodiment of the invention.

The above industrial compounds combined with a grinding to reduce particle sizes allow optimization of the production process of battery grade nanosize or submicron carbon-coated complex oxide, especially LiFePO4, in terms of cost-effectiveness and safety (low hazard and low VOC), . . ). Preferably, the organic precursors will form a thin carbon deposit on a nanoscale scale that is in close contact with the complex oxide crystal structure. This will then be graphitized during pyrolysis. After pyrolysis, the organic precursor could contain elements like N, P and Si.

These organic precursors can be found in the gas phase at least in equilibrium with the surface distributed organic precursor. This allows for the growth of graphite or graphene on the surface. To promote graphene deposit or graphitic nature, iron, cobalt, or nickel catalysts can be added to the pyrolysis step. You can also introduce and distribute the metal catalyst as a metal containing surfactant like Fe, Co, Ni stearate/oleate.”

“Preferably, the nature, distribution and quantity of organic precursor or carbon deposit after pyrolysis is adjusted to prevent nanoparticle sintering (by Carbon Coating or partial sintering using limited carbon quantities), on complex oxide particles or to form interparticle carbon Bridges at the nanoscale.

“Thermal treatment encourages the sintering primary nanoparticles within an aggregate of nanoparticles, thereby generating secondary particles. The nature of the solvent, concentrations, organic precursor property (adsorbed, not) and thermal or pyrolysis process all influence the size of these secondary particles. Sometimes, aggregates are porosity- or spherical depending on the extent of sintering. These aggregates may retain the primary nanoparticle form or only a portion of it, such as the C-deposit and some open or close pores. The invention shows that both the final synthesized product and the metal precursor can be processed if the particles have been properly coated with carbonaceous deposits.

“The following examples illustrate the present invention more practically, but they do not limit it in any way.”

“All examples were performed with a wet grinder machine from NETZSCH, Inc. (Z model LABSTAR LS 1)”

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