Disordered rocksalt material and method of forming it

Abstract

A composition useful for making cathodes is comprised of a disordered rock salt and acid treated carbon. The composition may be made by milling an acid treated carbon with a disordered rock salt in water to form a mixture wherein the disordered rock salt has a disordered rock salt average primary particle size of at most 400 nm and the acid treated carbon has an acid treated carbon average primary particle size less the disordered rock salt primary particle size, removing the water and agglomerating the mixture to form secondary particles having a secondary particle average particle size of at least 1 micrometer to 20 micrometers. The acid treated carbon is treated with an inorganic acid such as concentrated nitric acid.

Description

DISORDERED ROCKSALT MATERIAL AND METHOD OF FORMING ITFIELD

[0001] The present invention is in the field of battery technology.BACKGROUND

[0002] Lithium metal oxides have been used to formulate cathode materials for lithium ion batteries. The cathodes are derived from a few basic crystallographic structure types, such as spinels, olivines, and layered oxide structures. The layered oxide structures have included lithium- excess type structures, where additional lithium is present in the structure.

[0003] Recently, attention has been focused on disordered rocksalt structures, such as those formed from particular lithium metal oxides. Compounds represented by the formula: xLi3NbO4*(l-x)LiMO2(1) where M is a divalent or trivalent cation, have been shown to be a promising class of transition metal oxides for use as cathodes in lithium ion batteries. The compounds of formula (1) are considered a disordered rocksalt in which a random atomic arrangement of lithium and transition metal ions are packed in a closely-packed cubic structure. These disordered rocksalt compositions offer the ability to contain up to 3 lithium atoms per formula unit, which is more than the conventional lithium-excess layered materials. Formula (1) can be transformed and represented as LixMyNzOw.

[0004] The disordered rocksalt structure is an attractive cathode material for next generation lithium ion batteries due to a greater specific energy density (e.g., a higher theoretical energy density) than state-of-the-art cathode materials, such as layered lithium metal oxide structures. For example, certain disordered rocksalt structure materials have a theoretical gravimetric energy density of about 1120 Wh / kg, while a LiM CU active material has a theoretical gravimetric energy density of about 492 Wh / kg and a LiMn1 5Nio 5O4 has a theoretical gravimetric energy density of about 691 Wh / kg. This energy density is especially appealing when lower cost raw materials are used as components in the disordered rocksalt structure, such as manganese. As such, the disordered rocksalt materials can achieve relatively high energy density with relatively lowmaterial cost. In order to achieve comparable energy density, known cathode materials require higher-cost raw materials, such as cobalt or nickel.

[0005] The challenge of disordered rocksalt materials is relatively poor conductivity. The reduction of the disordered rocksalt particle size by milling and then re- agglomerating the milled particles has been described to improve the conductivity by shortening the electron and ion transport pathways (U.S. Pat. Publ. No. 2022 / 0059816). Further improvements may be desirable for improving the electronic conductivity and performance of batteries with disordered rocksalt.

[0006] Accordingly, it would be desirable to provide a disordered rocksalt having desirable processing with carbon powders and resultant disordered rocksalt compositions intermixed with carbon.BRIEF SUMMARY

[0007] We discovered that improvements to disordered rocksalt (DR) compositions comprised of DR and carbon may be realized by acid treating the carbon and mixing with the DR powder to form a composition comprised of the acid treated powder and the DR primary particles, which may then be agglomerated by any suitable method such as spray drying to form secondary particles of the DR and acid treated carbon. It has been found that the acid treatment results in improved uniformity distribution of the carbon and improved battery performance compared to batteries using DRs mixed with untreated carbon powders.

[0008] An illustration is a composition comprised of DR particles and acid treated carbon particles.

[0009] Another illustration is a method of forming a composition, comprising: milling an acid treated carbon with a disordered rock salt in water to form a mixture wherein the disordered rock salt has a disordered rocksalt (DR) average primary particle size of at most 400 nm and the acid treated carbon has an acid treated carbon average primary particle size less the disordered rock salt primary particle size, and removing the water and agglomerating the mixture to form secondary particles having a secondary particle average particle size of at least 1 micrometer to 20 micrometers. The acid treated carbon is formed by immersing a carbon powder in an inorganic acid (inorganic acid dissolved in water at high concentrations, for example, at least 30% by weightinorganic acid in water), which generally is performed at an elevated temperature (e.g, above 30 °C to the boiling point of the inorganic acid).

[0010] When a majority is specified of a component, it means more than 50% by mole or (readily understood from the context used) to essentially all of that component (99% or less). That is, the majority specified constituent of a component is present in an amount greater than 50% to 99%, 90, 80%, 70% or 60% of that component. When a minority of a component is a specified constituent, it is present in an amount less than 50% to about 1% with the balance being the majority specified constituent.

[0011] The composition comprises a disordered rock salt and an acid treated carbon. The DR generally has a cation comprised of lithium and at least one other metal and an anion comprised of oxygen and optionally fluorine and one or more of phosphorous, sulfur, and nitrogen. Desirably, the oxygen is all of the anion or a majority of the anion with the minority being comprised of F and one or more of P, S and N. The fluorine is the majority of two or more of the F, S, P and N. Illustratively, it is desirable for the F / (P, S and N) ratio to be at least 1 to 100, 50, 25, 10, 5 or 2.

[0012] The composition may be used in primary and secondary batteries lithium ion batteries. The composition may be used with any suitable electrolyte, separator and anode such as those known in the ail.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a secondary electron micrograph (SEM) of secondary particles of the invention.

[0014] Figure 2 is a SEM with energy-dispersive X-ray spectroscopy (EDX) map showing the uniform distribution of carbon in the secondary particles of this invention.

[0015] Figure 3 are X-ray diffraction patterns of secondary particles of this invention exposed to annealing.

[0016] Figure 4. are plots of the weight loss and heat flow upon heating of the secondary particles of the invention.

[0017] Figure 5 is a SEM of secondary particles of the invention.

[0018] Figure 6 is a SEM with energy-dispersive X-ray spectroscopy (EDX) map showing the uniform distribution of carbon in the secondary particles of this invention.

[0019] Figure 7 are X-ray diffraction patterns of secondary particles of this invention unannealed and annealed.

[0020] Figure 8 are plots of the weight loss and heat flow upon heating of the secondary particles of the invention.

[0021] Figure 9 is a SEM of secondary particles not of the invention.

[0022] Figure 10 a SEM with energy-dispersive X-ray spectroscopy (EDX) map showing the non-uniform distribution of carbon in the secondary particles not of this invention.DETAILED DESCRIPTION

[0023] The following definitions apply to some of the aspects described with respect to some embodiments of the invention. These definitions may likewise be expanded upon herein. Each term is further explained and exemplified throughout the description, figures, and examples. Any interpretation of the terms in this description should take into account the full description, figures, and examples presented herein.

[0024] The singular terms “a,” “an,” and “the” include the plural unless the context clearly dictates otherwise. Thus, for example, reference to an object can include multiple objects unless the context clearly dictates otherwise.

[0025] A rate “C” refers to either (depending on context) the discharge current as a fraction or multiple relative to a “1 C” current value under which a battery (in a substantially fully charged state) would substantially fully discharge in one hour, or the charge current as a fraction or multiple relative to a “1 C” current value under which the battery (in a substantially fully discharged state) would substantially fully charge in one hour.

[0026] To the extent certain battery characteristics can vary with temperature, such characteristics are specified at 30 degrees C, unless the context clearly dictates otherwise.

[0027] Ranges presented herein are inclusive of their endpoints. Thus, for example, the range 1 to 3 includes the values 1 and 3 as well as the intermediate values.

[0028] The compositions and morphology (e.g., structure) are useful in formulating electrodes of electrochemical cells comprised of the composition. More specifically, the compositon may be used to form the cathode. The lithium ion battery includes an electrolyte formulation with a lithium salt present at a concentration suitable for conducting the lithium ions through the electrolyte formulation between the cathode and an anode during the discharge and recharge operations.

[0029] In a disordered rocksalt both lithium and a transition metal occupy a cubic close-packed lattice of octahedral sites. In electrochemical reactions, lithium diffusion proceeds by the lithium hopping from one octahedral site to another octahedral site via an intermediate tetrahedral site. Lithium in the intermediate tetrahedral site is the activated state in lithium diffusion. The activated tetrahedral lithium ion shares faces with four octahedral sites as follows: (i) the site previously occupied by the lithium ion itself; (ii) the vacancy the lithium ion will move into; and (iii & iv) two sites that can be occupied by lithium, a transition metal, or a vacancy.

[0030] The composition may be a disordered rocksalt (DR) comprising one having a formula:LixM’yMzO2-(a+b)Fa Zb where 1.0<x<1.75; 0<y<0.55; 0.1 <z<l; 0<(a+b)<1.5; (b>0) M’ is one of Ti, Ta, Zr, W, Nb, or Mo; M is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, Sn, Bi and Sb; Z is one or more of P, N and S. Further dopants may be included such as those substituting for Li such as Na and Mg, which may be at any useful amount, but generally are at most about 10% or 5% to 0.01% by mole of the lithium and such dopants present in the DR.

[0031] The amount of F and Z may be a majority or minority of the anion (i.e., O, F and one or more of P, S and N). Illustratively (a+b) may be 0.05 to 1.5, 1, 0.95, 0.8, 0.7 or 0.5. It may be desirable for a to be 0.05 to 0.25. Z may be any combination of P, N and S, or may be just one of them if present. The ratio between P, N and S when two or more are present may be any useful ratio depending on the attributes sought. For example, it may be desirable to have S present when a reduced redox potential is desired. It may also be desirable for S to be the majority of the P, S and N present in the composition.

[0032] The DR may have any desirable Li of 1 or above, but it may be desirable for Li as represented by x to be at least 1.1, 1.15, 1.2 to 1.65, 1.5 or 1.4.

[0033] The cation of the DR may be the metals described, but desirably, at least one of the metals as represented by M is comprised of one or more of Ti, Mn, Fe, Co,V, Cr, Ni and Cu. It may be desirable for M to be comprised of Ti and Mn. The composition may illustratively be one where M’ is comprised of Nb. When Nb is present, it may desirable for M to be comprised of Mn. Illustratively, M’ may be Nb and M may be Mn. When Nb and Mn are present with or without other metals, they may be present in a ratio of Mn / Nb of 1 or 2 to 200, 150, 100, 75, 50, 25 or 10 by mole.

[0034] The DR may be made by any suitable method such as those known in the art to make disordered rocksalts. Illustrative methods are described in U.S. Pat. Nos. 10,280,092, 10,978,706 and ACS Appl Mater Interfaces. 2019 Oct 2;11(39):35777-35787, each incorporated herein by reference.

[0035] Illustratively, the composition is desirably comprised of micro-sized clusters or agglomerates of sub-micro-sized particles. The micro-sized clusters are also referred to herein as secondary particles. The secondary particles desirably have average particle sizes (e.g., diameters) in the micrometer scale, such as between 1 micrometer and 20 micrometers. The secondary particles are comprised of DR primary particles and acid treated carbon particles. The terms “primary” and “secondary” indicate that the primary particles are formed before the secondary particles, and the secondary particles are agglomerations of the primary particles. The DR primary particles have an average particle size (e.g., equivalent spherical diameter) in the nanometer scale, such as less than 400 or 300 nanometers. The acid treated carbon particles (primary particles) have a similar size, but desirably have a primary size that is less than the DR primary particle size. The sub-micro primary particles of disordered rocksalt material may provide desirable conductivity and the micro-sized secondary particles of the disordered rocksalt material yield high electrode energy density.

[0036] Illustratively, the acid treated carbon may be made by immersing a carbon powder in an inorganic acid for a time to sufficiently acidify the carbon black to realize, for example, improved uniform distribution and coating of the DR primary particles when agglomerating theprimary particles of DR and the carbon particles. Generally, the inorganic acid is present in water in an amount of at least 10%, 20%, 30%, 50%, 60% to any practicable amount such as generally referred to as a fuming inorganic acid. The inorganic acid may be any suitable inorganic acid such as those known in the art (e.g., phosphoric, nitric, HC1, sulfuric) with nitric being particularly useful (e.g., concentrated nitric acid -70% by weight).

[0037] The immersion of the carbon may be for any time suitable to realize the acid treated carbon and typically is at least 5, 15, or 30 minutes to 24, 12, or 6 hours and may be done under agitation. The immersion likewise may be desirably performed at an elevated temperature (e.g., greater than about 30 °C to the boiling point of the inorganic acid in water. After immersion in the inorganic acid, the carbon typically is washed with neutral water (~ 7 pH) until the wash water is a neutral pH. The acid treated carbon may then be stored under an atmosphere that maintains the acidification without adsorption of undesired adsorbates (e.g., noble gas, dry air, nitrogen or combination thereof).

[0038] The carbon used to make the acid treated carbon particles may be any useful carbon powder for making a battery and may include, for example, carbon black, carbon nanotubes, graphene, graphite, carbon fiber, and acetylene black. Illustratively, the carbon particles are carbon black powders that may be standard, conductive or non-conductive. The carbon may be comprised of primary particles that are chemically bound into secondary particles (e.g., carbon black) and referred to as structured inorganic powders or the primary particles may not be chemically bound other than by hydrogen or Van-der Waals forces (e.g., carbon nanotubes). The particle size may be determined as previously described. The carbon black may have any useful oil absorption number (ASTM D-2414-09). For example, the carbon black typically should have an oil absorption number (OAN) of about 40, 50, or 60 to 250, 200 or 175 mis per 100 grams. The specific surface area (ISO 9277:2010) may be any useful, and generally is at least 10 m2 / g, 20 m2 / g or 50 m2 / g to any practical surface area, 1000 m2 / g, 500 m2 / g, 300 m2 / g or 200 m2 / g.

[0039] The carbon black may be a standard carbon black which is not specially treated to render it nonconductive. Standard carbon black is a carbon black which is not specifically surface treated or oxidized. Alternatively, one or more conductive carbon blacks may be used exclusively or in conjunction with the standard carbon black. Conductive carbon blacks are generally recognized as having at a purity of at least 97% carbon, but preferably may be 99% or greater inpurity, OAN of 100 or greater and specific surface area of 120 m2 / g or greater. Examples of standard carbon blacks include RAVEN 790, RAVEN 450, RAVEN 500, RAVEN 430, RAVEN 420 and RAVEN 410 carbon blacks available from Colombian and carbon blacks available from Cabot Corporation under the tradenames VULCAN, PROPEL, REGAL, STERLING, and SPHERON.

[0040] Illustratively, the secondary particles of DR and acid treated carbon may be carbon black, carbon nanotubes, graphene, graphite, carbon fiber, and acetylene black, wherein the acid treated carbon particles are milled such that it has a primary average particle size that the same or smaller than the average DR primary particle size. The DR powder and acid treated carbon particles are milled by any suitable method. Illustratively, they are milled at the desirable amounts of each (e.g., 1%, 2%, 3%, 4%, or 5% to 35%, 30%, 25% or 20% by volume or weight of carbon in the composition “carbon and DR”) in deionized water to make the suspension. The milling may be performed via a micromedia mill. The micromedia mill may include concentric cylinders with a milling media present in an annular gap between the cylinders. The milling media grinds the precursors in the suspension as the cylinders are rotated relative to each other to create small nanosized primary particles. The micromedia mill may also be designed to form homogenously-sized particles such that all of the primary precursor particles have approximately the same size, within a designated range. The primary particles out of the mill may have an average particle size that is no greater than 400 nanometers (nm). The average primary particle size of each of the DR and acid treated carbon may be no greater than 200 nm, 100 nm, or less to any practicable size such as greater than about 25 nm. Desirably, the average primary acid treated carbon size is less than the average DR primary particle size. An example of a suitable micromedia mill is a laboratory bead mill, such as the Buhler PML2 product, which is trademark of the Buhler Group. The size of the particles may be determined by any suitable method such as those known in the art including laser diffraction and micrographic techniques.

[0041] After milling, the water is removed to agglomerate the DR and acid treated carbon particles to form the composition. The secondary particles may be formed by any useful method and illustratively may be formed by spray drying. Desirably, the secondary particles have a secondary particle average size of about 1 or 2 micrometers to 20, 15 or 10 micrometers. Thespray drying may be performed, for example, using a mini spray dryer, such as the Buchi B-290 model, which is a trademark of Buchi.

[0042] The composition may be used to form a cathode by any suitable method such as those known in the art. For example, the secondary particles of DR and acid treated carbon may be mixed with a binder such a polymer useful to make cathodes (e.g., polyfluoropolymer such as poly vinylidene fluoride) one or more solvents to form a slurry. Non-limiting examples of the one or more solvents may be an aprotic polar solvent such as methyl-2-pyrrolidinone (NMP). The slurry may then be deposited on a metal current collector (e.g., stainless steel, copper, or any suitable conductive metal thin) and the solvent removed to form the cathode.

[0043] In an embodiment, the composition of DR particles and acid treated particles may be further annealed to a temperature in an inert atmosphere (e.g., noble gas) or in air, which may improve the performance of a battery made therefrom. Illustratively, the temperature may be from about 150 °C, or 200 °C to 450 °C, 400 °C, or 35O°C. The time of the further annealing may be 5, 10 or 15 minutes to 24, 18, 12 or 6 hours.

[0044] A cathode made of the composition may be used in a rechargeable lithium ion battery cell. The battery cell includes the cathode, an anode, separator and electrolyte. The battery or battery cell may be formed in any suitable atmosphere such as common in the art. For example, a high purity argon atmosphere may be used to limit any undesirable contamination from species present in atmospheric air.Illustrations

[0045] Illustration 1. A composition comprised of a mixture of disordered rocksalt particles and acid treated carbon particles.

[0046] Illustration 2. The composition of illustration 1, wherein the mixture comprises secondary particles of agglomerated disordered rocksalt particles and acid treated carbon particles.

[0047] Illustration 3. The composition of illustration 1 or 2, wherein the disordered rocksalt particles have an average particle size of at most 400 nm.

[0048] Illustration 4. The composition of any one of illustrations 1 to 3, wherein the acid treated carbon particles have an average size of at most 400 nm.

[0049] Illustration 5. The composition of any one of illustrations 1 to 4, wherein the acid treated carbon particles have a size that is less than the disordered rock salt particles.

[0050] Illustration 6. The composition of any one of illustrations 1 to 5, wherein the acid treated carbon particles are comprised of acid treated: carbon black, carbon nanotubes, graphene, graphite, carbon fiber, and acetylene black.

[0051] Illustration 7. The composition of any one of illustration 1 to 6, wherein the acid treated carbon particles are comprised of acid treated conductive carbon black having a surface area of at least 30 m2 / g and oil absorption of at most about 10 ml / g.

[0052] Illustration 8. The composition of claim 7, wherein the conductive carbon black has a surface area of at least 50 nr / g and oil absorption number of at most 500 ml / g.

[0053] Illustration 9. The composition of any one of illustration 1 to 8, wherein the acid treated carbon particles are present in an amount of 1% to 35% by volume of the composition.

[0054] Illustration 10. The composition of any one of the preceding illustrations wherein the disordered rock salt is represented byLixM yMzO2-(a+b)Fa Zb where 1.0<x<1.75; 0<y<0.55; 0.1<z<l; 0<(a+b)<0.7; (b>0) M’ is one of Ti, Ta, Zr, W, Nb, or Mo; M is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh and Sb; and Z is one or more of P, N and S.

[0055] Illustration 11. The composition of illustration 10, wherein M is comprised of one or more of Ti, Mn, Fe, Co,V, Cr, Ni and Cu.

[0056] Illustration 12. A battery electrode comprising the composition of any one of illustration 1 to 10.

[0057] Illustration 13. A method of forming a composition, comprising:

[0058] (i) milling an acid treated carbon with a disordered rock salt in water to form a mixture wherein the disordered rock salt has a disordered rock salt average primary particle size of at most 400 nm and the acid treated carbon has an acid treated carbon average primary particle size less the disordered rock salt primary particle size,

[0059] (ii) removing the water and agglomerating the mixture to form secondary particles having a secondary particle average particle size of at least 1 micrometer to 20 micrometers.

[0060] Illustration 14. The method of illustration 13, wherein the acid treated carbon is formed by an acid treating method comprising, immersing a carbon powder in an inorganic acid at an elevated temperature.

[0061] Illustration 15. The method of illustration 14, wherein the elevated temperature is at least above 30 °C to the boiling point of the inorganic acid.

[0062] Illustration 16. The method of either illustration 14 or 15, wherein the inorganic acid’s concentration in water is at least 30% by weight.

[0063] Illustration 17. The method illustration 16, wherein the inorganic acid’s concentration is at least 50% by weight.

[0064] Illustration 18. The method of any one of claims 14 to 17, wherein the inorganic acid is concentrated nitric acid.

[0065] Illustration 19. The method of any one of claims 13 to 18, wherein the removing and agglomerating is by spray drying.

[0066] Illustration 20. The method of any one of illustrations 14 to 19, wherein the acid treating method is comprised of separating the acid treated carbon from the inorganic acid and washing with neutral water until a neutral pH is reached.

[0067] Illustration 21. The method of any one of illustrations 14 to 20, wherein the carbon powder is comprised of one or more of carbon black, carbon nanotubes, graphene, graphite, carbon fiber, and acetylene black.

[0068] Illustration 22. The method of illustration 21, wherein the carbon powder is comprised of a carbon black that is a conductive carbon black.

[0069] Illustration 23. The method of illustration 22, wherein the conductive carbon black has a surface area of at least 30 nr / g and an oil absorption number of at most 200 ml / 100 g.

[0070] Illustration 24. The method of any one of illustrations 13 to 23, wherein after removing the water and agglomerating, the secondary particles are annealed at a temperature of 150 °C to 350 °C.

[0071] Illustration 25. The method of illustration 24, wherein the annealing is for a time of 1 to 24 hours under an inert atmosphere.Examples

[0072] Disordered rocksalt is synthesized via a conventional solid state reaction such as described in U.S. Pat. Publ. No. 2022 / 0059816. Typically, stoichiometric amounts of precursors (MniOs, TiCh, NboOs, LiiCCL and LiF) were mixed in deionized water to make a suspension (35wt% solids), which is ball milled with a planetary ball mill to decrease the particle size (<300 nm) as well as to obtain a homogeneous mixture of all precursors. The mixture is dried at 100°C for 12h under air before being annealed 12 h at 700C and 20 min at 900C under argon or nitrogen flow (20L / h) to obtain the disordered rocksalt, which is used herein for each of the examples and comparative examples.Examples A: Acid treated Super C65 carbon black available from MSE Supplies

[0073] Preparation of the hydrophilic carbon is done by connecting a Liebig condenser with flowing cold water to the center joint of a 500 mL roundbottom flask to prevent solvent evaporation. The top of the condenser is sealed with parafilm to prevent the escape of NO2. 5 g of carbon, (Super C65, MSE Supplies) is added to the 500 mL three neck round bottom flask with an oval stir bar, followed by the addition of 300 mL of concentrated HNO3 (Nitric Acid ACS Reagent 70%, Sigma Aldrich). The flask is placed into a silicon oil bath at 60 °C, which is then slowly increased in temperature to 90 °C, making sure that the solution does not boil. The solution is then stirred for 16 hours at 90 °C. The stirring is then stopped, which allows the carbon black to settle to the bottom of the flask. The supernatant acid is then decanted by pouring or pipetting. Theremaining carbon black suspension is added to a 1 L beaker with -600 mL of DI water and stirred. The flask is rinsed three times with DI water which is added to the IL beaker. The carbon black to allowed to settle and the water is decanted. This step is repeated until the decanted water reaches a neutral pH. The remaining solution is centrifuged, and the supernatant is removed. The centrifuge tubes containing the treated carbon are placed in a vacuum oven at 80 °C for 24 hours to dry. The final acid treated carbon is stored in an argon glove box.

[0074] The appropriate amount of DR and acid treated carbon (2-10 wt%) is wet milled in water with 10% solid content with various milling energies (250, 500 kWh / T) and bead size of 0.3 mm. The obtained slurry is spray dried (slurry flow rate 3ml / min, temperature 80-90 oC, gas flow rate 740 L / h) to obtain carbon coated DR particles with 50-300 nm primary particle size and 1-5 micrometer secondary particle size. The obtained powder was post annealed at different temperatures such as 150, 250, and 350 °C under argon for 12 hours respectively and underwent electrochemical testing.Examples B: Acid treated carbon nanotubes

[0075] Commercially available carbon nanotubes are acid treated in the same manner as the Super C65 carbon black.Comparative Examples B :The same carbon nanotubes are used without acid treating to make secondary particles and batteries in the same manner as the Examples.

[0076] Battery cells arc assembled in a high purity argon filled glovebox (M-Braun, 02 and humidity content <0.1ppm). The cathode was prepared by mixing the carbon coated disordered rocksalt powder with poly(vinylidene fluoride) (Sigma Aldrich) and l-methyl-2-pyrrolidone (Sigma Aldrich), and the resulting slurry was deposited on a stainless steel current collector and dried to form a composite cathode film. For the anode, a thin Li foil was cut into the required size. Each battery cell included a composite cathode film, a polypropylene separator, and a lithium foil anode. An electrolyte (1.0M LiPFe in EC / EMC (1:2 v / v)) containing lithium hexafluorophosphate in a mixture of ethylene carbonate and ethyl methyl carbonate with an additive was used. The battery cell was sealed and cycled between 1.5-4.6V at 30 °C at C / 20 formation rate and C / 3cycling rate, where 1C = 300 mAh / g. For full cell testing graphite anode has been used and battery has been cycled between 2-4.45 or 2-4.55V at 30 oC at C / 20 formation rate and C / 3 cycling rate.

[0077] Spray dried spherical particles of the Super C65 containing secondary particles have an average diameter of ~2 micometers and composed of 100-300nm primary nanoparticles as shown in scanning electron microscopy (SEM) of Figure 1. The uniform distribution of C65 carbon within secondary particles of DR (red dots) can be observed from the energy dispersive X-ray (EDX) elemental mapping shown in Figure 2.

[0078] The carbon coated DR is post annealed at different temperatures such as 150, 250, and 350 °C for 12h under argon to remove residual impurities and adsorbed water. The phase purity of the synthesized samples was analyzed by X-ray diffraction (XRD). All three samples annealed at different temperatures have diffraction peaks corresponding to disordered rock salt structure with the Fm3m space group. There is small peak in the XRD pattern at around 2 0 =30-35° for 150 °C annealed sample which becomes undetectable with increased annealing temperature. The increase in annealing temperature also results in XRD peaks becoming noticeably sharper indicating improved crystallinity as shown in Figure 3.

[0079] Thermogravimetric analysis (TGA) was performed on the secondary particles to detect weight changes with temperature. There arc two weight losses observed on the TGA curve. The first weight loss (~6 wt%) may correspond to release of adsorbed water and decomposition of impurity phases, while the second weight loss (~7 wt%) corresponds to carbon oxidation with exothermic heat generation as shown in Figure 4.

[0080] The electrochemical performance has been tested within voltage window of 1.5-4.6V. Initial capacity (C / 20), CE, and total resistance for Super 65 containing secondary particle samples annealed at different temperatures are shown below. The optimum post annealing temperature is 250 °C with highest initial capacity and CE.

[0081] Table 1

[0082] Acid functionalized multi walled CNTs are used to produce DR with 4 wt% carbon secondary particles. Compared to the previous experiments, lower milling energy was used (250 kWh / T). The secondary particles are shown in Figure 5. The uniform distribution of carbon is shown in Figure 6. CNT spanning DR acid treated secondary particle spheres are also observed. The as-prepared sample has sharp XRD peaks indicating good crystallinity. After post annealing at 250 °C there are no observable changes in the diffraction pattern as shown in Figure 7. There are two weight losses observed in the TGA curve. The first weight loss (~6 wt%) may correspond to release of adsorbed water and decomposition of impurity phases, while second weight loss (~4 wt%) The electrochemical performance has been tested within voltage window of 2-4.5V. The sample post annealed at 250 °Cshows improved Cyl discharge capacity compared with the as- synthesized sample as shown in Table 2may correspond to carbon oxidation with exothermic heat generation as Figure 8.

[0083] Untreated multiwalled CNTs are used to produces DR with ~7% carbon secondary particles. The secondary particles after 400 °C, 6 hour anneal is shown in Figure 9. From this Figure it is apparent that the particles are not uniformly spherical as in the Examples B (Figures 5 and 6). The non- uniformity of the carbon is shown in Figure 10 compared to Examples B (Figure 6). The battery performance of batteries having cathodes and batteries made in the same manner as Examples B are shown in Table 2, where it is readily apparent that the performance is less than the Examples B, which are less than the performance of Examples A. These Comparative Examples B display an impurity phase not seen in Examples B in the X-ray diffraction pattern (not shown).Table 2

Claims

WHAT IS CLAIMED IS:

1. A composition comprised of a mixture of disordered rocksalt particles and acid treated carbon particles.

2. The composition of claim 1, wherein the mixture comprises secondary particles of agglomerated disordered rocksalt particles and acid treated carbon particles.

3. The composition of claim 2, wherein the disordered rocksalt particles have an average particle size of at most 400 nm.

4. The composition of claim 2, wherein the acid treated carbon particles have an average size of at most 400 nm.

5. The composition of claim 4, wherein the acid treated carbon particles have a size that is less than the disordered rock salt particles.

6. The composition of claim 5, wherein the acid treated carbon particles are comprised of acid treated: carbon black, carbon nanotubes, graphene, graphite, carbon fiber, and acetylene black.

7. The composition of claim 6, wherein the acid treated carbon particles are comprised of acid treated conductive carbon black having a surface area of at least 30 m2 / g and oil absorption of at most about 10 ml / g.

8. The composition of claim 7, wherein the conductive carbon black has a surface area of at least 50 m2 / g and oil absorption number of at most 500 ml / g.

9. The composition of claim 1, wherein the acid treated carbon particles are present in an amount of 1% to 35% by volume of the composition.

10. The composition of any one of the preceding claims wherein the disordered rock salt is represented byLixM yMzO2-(a+b)Fa Zbwhere 1.0<x<1.75; 0<y<0.55; 0.1<z<l; 0<(a+b)<0.7; (b>0) M’ is one of Ti, Ta, Zr, W, Nb, or Mo; M is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh and Sb; and Z is one or more of P, N and S.

11. The composition of claim 10, wherein M is comprised of one or more of Ti, Mn, Fe, Co,V, Cr, Ni and Cu.

12. A battery electrode comprising the composition of claim 10.

13. A method of forming a composition, comprising:(i) milling an acid treated carbon with a disordered rock salt in water to form a mixture wherein the disordered rock salt has a disordered rock salt average primary particle size of at most 400 nm and the acid treated carbon has an acid treated carbon average primary particle size less the disordered rock salt average primary particle size,(ii) removing the water and agglomerating the mixture to form secondary particles having a secondary particle average particle size of at least 1 micrometer to 20 micrometers.

14. The method of claim 13, wherein the acid treated carbon is formed by an acid treating method comprising, immersing a carbon powder in an inorganic acid at an elevated temperature.

15. The method of claim 14, wherein the elevated temperature is at least above 30 °C to the inorganic acid’ s boiling point.

16. The method of claim 15, wherein the inorganic acid’s concentration in water is at least 30% by weight.

17. The method claim 16, wherein the inorganic acid’s concentration is at least 50% by weight.

18. The method of claim 13, wherein the inorganic acid is concentrated nitric acid.

19. The method of claim 13, wherein the removing and agglomerating is by spray drying.

20. The method of claim 14, wherein the acid treating method is comprised of separating the acid treated carbon from the inorganic acid and washing with neutral water until a neutral pH is reached.

21. The method of claim 14, wherein the carbon powder is comprised of one or more of carbon black, carbon nanotubes, graphene, graphite, carbon fiber, and acetylene black.

22. The method of claim 21 , wherein the carbon powder is comprised of a carbon black that is a conductive carbon black.

23. The method of claim 22, wherein the conductive carbon black has a surface area of at least 30 nr / g and an oil absorption number of at most 200 ml / 100 g.

24. The method of any one of claims 13 to 23, wherein after removing the water and agglomerating, the secondary particles are annealed at a temperature of 150 °C to 350 °C.

25. The method of claim 24, wherein the annealing is for a time of 1 to 24 hours under an inert atmosphere.

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