Disordered rocksalt material and method of forming it

Abstract

A composite particle comprised of interspersed spinel and disordered rocksalt domains therein may be made by removing lithium from a disordered rocksalt to form a lithium deficient disordered rocksalt and heating the lithium deficient disordered rocksalt for a time and temperature to form the composite particle.

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 LiMii2O4 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, which may be incombination with other transition metals. As such, the disordered rocksalt (DR) materials can achieve relatively high energy density with relatively low material cost. In order to achieve comparable energy density, known cathode materials require higher-cost raw materials, such as cobalt or nickel.

[0005] Unfortunately, these DR materials require the particle size to be in the submicrometer range due to the low Li diffusivity of these materials. This has caused these DR materials to suffer poor capacity and voltage retention issues, largely originating from the poorly controlled, heavily- pulverized nanoparticle morphology introduced upon preparing the DR materials. The pulverized particle morphology of DRs tends to accelerate the electrolyte decomposition and dissolution of Mn, when present, to the electrolyte, leading to shorter cycle life. Also, the pulverized particle morphology may lead to low electrode density decreasing the volumetric energy density of the DR material on a current collector that forms the typical cathode in a battery.

[0006] Accordingly, it would be desirable to provide a particle having a DR structure that avoids one or more of the problems of the prior art DRs as described above and batteries comprised of disordered rocksalt cathodes having improved characteristics such as longer cycle life, high volumetric density, improved processing and power delivery.BRIEF SUMMARY

[0007] Particles of interspersed spinel or monoclinic and disordered rock domains (composite particle “CP”) may be formed by heating a disordered rock salt particle with lithium deficiency (DDR). The DDR typically has a surface deficiency of lithium. It is understood that nanodomains may be comprised of spinel, monoclinic and rocksalt phases, but bulk X-ray diffraction techniques may be inadequate to detect both phases due to the overlapping diffraction peaks of the spinel and monoclinic phase. The DDR may be made by solid state thermal synthesis followed by removal of Li from the DR structure by thermal treatment in oxygen at a lower temperature, which then may be washed to remove surface lithium species that are formed such as lithium carbonate and lithium hydroxide. The DDR may be made by synthesizing the DR in a molten salt followed by washing to form the DDR (“salt method”). That is, the salt method unexpectedly may form the DDR directly (i.e., without thermally treating in the presence of oxygen at a lower temperaturethan the synthesis temperature even though such further treatment may be performed if desired). The DDR is then thermally treated to form the CPs in an atmosphere with or without oxygen.

[0008] An illustrative CP is one comprising interspersed spinel or monoclinic and disordered rocksalt domains, the domains being less than 100 nanometers (“nanodomains”). The presence of spinel or monoclinic and DR structures in powders of the particles may be determined by X-ray diffraction. The nanodomains size and distribution within the particle may be determined by Focused-Ion-Beam (FIB) cross-section analysis by high resolution transmission electron microscopy (HRTEM) employing flat-field filtering for the inverse fast fourier transform (FFT) of the HRTEM image.

[0009] The illustrative CP may be made by heating a lithium deficient disordered rocksalt (DDR) particle for a transformation time and transformation temperature sufficient to form the CP having nanodomains of spinel or monoclinic and disordered rocksalt interspersed within the composite. The DDR particle has a chemical gradient of Li that is sufficient to initiate the formation of the interspersed nanodomains within the DDR to form the CP at the transformation time and temperature that are substantially below the temperature used to synthesize the disordered rock salt particle. The monoclinic domains, without being limiting, may more readily form when the DDR has less of or no gradient and the heat treatment is in air at a temperature exceeding 400°C to about 600 °C. The CPs may be used in primary and secondary lithium ion batteries. The DR powder may be used with any suitable battery component to form a lithium ion battery in electrolyte including, for example, a current collector, separator and anode such as those known in the art.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 shows the X-ray diffraction patterns of disordered rock salt particles not of this invention and composite particles of this invention.

[0011] Figure 2 is a scanning electron micrograph of a disordered rock salt particles not of this invention.

[0012] Figure 3 shows scanning electron micrographs of composite particles of this invention.

[0013] Figure 4 shows scanning electron micrographs of composite particles of this invention.

[0014] Figure 5 shows the X-ray diffraction patterns of disordered rock salt particles not of this invention and composite particles of this invention.

[0015] Figure 6 is a scanning electron micrograph of a disordered rock salt particles not of this invention.

[0016] Figure 7 is a scanning electron micrograph of a disordered rock salt particles not of this invention.

[0017] Figure 8 is a scanning electron micrograph of a disordered rock salt particles not of this invention.

[0018] Figure 9 is a scanning electron micrograph of composite particles of this invention.

[0019] Figure 10 is a scanning electron micrograph of composite particles of this invention.

[0020] Figure 11 is a transmission electron micrograph (TEM) of composite particles of this invention.

[0021] Figure 12 shows a high resolution transmission electron micrograph (HRTEM) of a cross-sectioned composite particle of this invention.

[0022] Figure 13 shows flat-field filtering for the inverse fast fourier transform (FFT) of the HRTEM image of Figure 12.

[0023] Figure 14 shows the electron diffraction pattern of the composite particle of Figure 12 with spinel denoted with blue color and DR crystalline structures with yellow color.

[0024] Figure 15 shows the spatial relationship of the ^-spacing of the DR and spinel domains in the composite particle of Figure 12 in the 200 plain.

[0025] Figure 16 shows voltage profiles and capacity retention of a battery having a cathode comprised of disordered rock salt particles not of this invention.

[0026] Figures 17 A, B and C show voltage profiles and capacity retention of batteries having a cathode comprised of composite particles of this invention.

[0027] Figure 18 shows the capacity retention of batteries having a cathode comprised of composite particles of this invention.

[0028] Figure 19 shows the X-ray diffraction patterns of disordered rock salt particles not of this invention and composite particles of this invention.

[0029] Figure 20 shows scanning electron micrographs of disordered rocksalt particles not of this invention and composite particles of this invention.

[0030] Figure 21 shows voltage profiles and capacity retention of batteries having a cathode comprised of disordered rocksalt particles not of this invention and of composite particles of this invention.

[0031] Figure 22 shows voltage profiles and capacity retention of batteries having a cathode comprised of disordered rocksalt particles not of this invention and of composite particles of this invention.

[0032] Figure 23 shows shows the X-ray diffraction patterns of composite particles of this invention.

[0033] Figure 24 is a scanning electron micrograph of composite particles of this invention.

[0034] Figure 25 shows voltage profiles and capacity retention of batteries having a cathode comprised of composite particles of this invention.

[0035] Figure 26 shows voltage profiles and capacity retention of batteries having a cathode comprised of composite particles of this invention.

[0036] Figure 27 shows voltage profiles and capacity retention of batteries having a cathode comprised of composite particles of this invention.

[0037] Figure 28 shows voltage profiles and capacity retention of batteries having a cathode comprised of composite particles of this invention.

[0038] Figure 29 shows voltage profiles and capacity retention of batteries having a cathode comprised of composite particles of this invention.DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] A rate “C” refers to cither (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.

[0042] To the extent certain battery characteristics can vary with temperature, such characteristics are specified at ambient ~20 °C to 30 °C, unless the context clearly dictates otherwise.

[0043] 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. 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 unless otherwise specified.

[0044] The CP is comprised of interspersed spinel or monoclinic and disordered rocksalt domains that are less than 100 nanometers (“nanodomains”). These domains are preferably less than 50 or 25 nanometers. Both spinel and monoclinic domains may be present with the disordered rocksalt domains. The characteristics of the domains and particles may be determined by micrographical techniques as described herein. The CPs generally exhibit a disordered rock salt <7-spacing of about 0.2 nm and a spinel or monoclinic d-spacing of about 0.4 nm along the 200 planes.

[0045] The CP may be formed from any useful disordered rock salt, but is particularly useful for DRs comprised of one or more of Ti, Mn, Fe, Co,V, Cr, Ni and Cu. Illustratively, the CP may have a chemistry represented byLixM yMzO2-(a+b)FaZb where 1.0<x<1.75; 0<y<0.55; 0. 1 <z< 1 ; 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, Fc, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh and Sb; and Z is one or more of P, N and S. Desirably, M is comprised of one or more of Ti, Mn, Fe, Co,V, Cr, Ni and Cu and more desirably M is comprised of Mn. M’ desirably is comprised of at least one of Ti, Ta and Nb.

[0046] The CPs in contrast to the typically milled DR powders may lack sharp asperities and be more circular when made by the salt method. Illustratively, the CPs may have a circularity as follows. An individual particle circularity is defined as the 4TIA / P2. where A is the area of the particle and P is the perimeter length of the particle, both as viewed from a random perspective. Sphericity, a related parameter, is derived as the square root of circularity. Circularity is a numerical value greater than zero and less than or equal to one. A perfectly circular particle is referred to as having a circularity of 1.00. Tables of population circularity data are represented in such a way that various levels of circularity (e.g., 0.65, 0.75, 0.85, 0.90, and 0.95) are accompanied by percentages of the particle sample population with a circularity greater than the tabulated value. Desirably, at least about 70%, 75% or 80% of the CPs (by number) have a circularity that is at least about 0.65, 0.75, 0.8 or 0.85 (i.e., spherical as used herein).

[0047] The CPs may be any particle size and size distribution use in a battery, however, the interspersed nanodomains of the CPs surprisingly allows the primary particle size to besubstantially larger than typical pulverized DR particles necessary to make a useful battery. Typical DRs generality have a particle size that is substantially less than 100 nm (average less than or D90 of less than 100 nanometers equivalent spherical diameter by volume or number). Generally, the average particle size is at most 20 micrometers, but typically the average primary particle size is at most about 2 micrometers to 01 micrometers. It has been discovered that CPs having particles from 100 nm to 2 micrometers in contrast to typical DRs may have useful battery characteristics with a particle distribution by number or volume of a D90 of at most about 1.5 micrometers, D50 that is submicrometer (e.g., less than 1 micrometer to about 0.1 micrometer), and a D10 of at least 0.1 micrometer being particularly useful. The primary particles may be agglomerated to form aggregates (secondary particles such as those arising from spray drying, which may further sintered if desired). Primary particles are discrete unagglomerated particles preferably having the aforementioned particle size distribution. Unagglomerated particles are those that may easily be disrupted by shear (illustratively those bonded at most be van der Waals and hydrogen bonding).

[0048] Particle size and shape can be measured by any suitable methods known in the ail to measure particle size by diameter (equivalent spherical diameter). In some embodiments, the particle size and shape are determined by laser diffraction as is known in the art. For example, particle size can be determined using a laser diffractometer such as the Microtrac S3500 with static image analysis accessory using PartAnSI software to analyze the captured images of the particles or image analysis of scanning electron micrographs of the particles (e.g., counting of at least 100 particles by image analysis software such as described above).

[0049] When the salt method described herein is used the CP may be further comprised of a trace amount of one or more of Na, K, Cs, Br and CL Trace herein is an amount that is detectable by known bulk analysis techniques such as inductively coupled plasma mass spectrometry. A trace, herein,, is any amount from 100 pails per million by weight to the analytical detectable limits (e.g., parts per billion by weight).

[0050] A composite particle (CP) may be formed by heating a lithium deficient disordered rocksalt (DDR) for a transformation time and transformation temperature sufficient to form the composite particle having nanodomains of spinel or monoclinic or both and disordered rocksalt interspersed within the composite particle. The transformation temperature is substantially belowthe temperature necessary to form a disordered rock salt (e.g., 800 °C or 900 °C to 1200 °C or 1100 °C). Particularly useful transformation temperatures generally are from 300 °C to 600 °C. The transformation time may be any useful, with those times that do not result in any deleterious particle growth while still realizing the nanodomains being desirable. Illustratively the transformation time may be from 5 minutes, 15 minutes, 30 minutes 60 minutes, 2 hours or 3 hours to 24 hours, 12 hours or 20 hours. The atmosphere may be static or flowing. The transformation atmosphere may be any suitable such as an inert (noble gas or nitrogen) or contain oxygen (air, oxygen or inert gas / nitrogen with a partial pressure of oxygen). When an oxygen containing atmosphere is employed, the DDR may be formed in-situ and subsequently be transformed into the CP. CP’s having a monoclinic phase, without being limiting, appear to be formed when the DDR from the salt method synthesis method is used and the washing after annealing is with a lithium hydroxide solution having a pH of at least 11 and the transformation temperature is at least 400 °C or 500 °C to 600 °C, which may be due to further development of a monoclinic super structure as displayed by an X-ray diffraction peak centered at 21020 (Cu). The formation of this phase may also be more prevalent depending on the transition metals of the disordered rocksalt. Illustratively, without being limiting in any way, the presence of Ti appears to favor the formation of the monoclinic domains when heated above 400 °C, whereas the presence of Nb appears to disfavor the formation of the monoclinic phase all other things being essentially the same.[00511 The DDR particle has a lithium deficiency. The lithium deficiency, for example, may be shown by a Li chemical gradient as given by the difference in Li concentration of the DDR in the outer 20% by volume (outer) than in the core 80% volume encapsulated by the outer volume and is sufficient to cause the DDR to convert to the CP, with the outer a lower amount of Li being particular useful. The difference necessary to cause the conversion in practicable times may be any useful for the particular CP. Exemplary useful differences may be 1%, 5%, 10% or 25% to 50%. The concentration of Li may be determined by electron micrographical techniques.

[0052] The DDR may be made by first forming a disordered rocksalt (DR) particle and removing lithium, for example, from the surface of the disordered rock salt particle. Illustratively, the lithium may be removed at the surface of the disordered rock salt particle by washing in neutral or basic water (e.g., having a base dissolved therein such as an alkali hydroxide and ammonia) andseparating the washed particles from the water, for example, by filtration or settling / centrifugation. Another illustration is a thermal treatment of a DR particle, where the DR is heated in an oxygen containing atmosphere at a temperature substantially (e.g., 300 °C to 500 °C) below the DR synthesis temperature, which is typically from 800 °C to 1200 °C. The heating may be by any suitable heating method such as those known in the art including resistance heating, RF / microwave heating, inductively coupled heating and radiative heating. The oxygen containing atmosphere may be any having sufficient oxygen to remove the lithium from the DR. Generally, the amount of oxygen present is at least about 0.1 mole fraction or about 0.2 mole fraction, with air being a particular example.

[0053] A particularly useful method (“salt method”) to form the DR particle comprises heating disordered rocksalt precursors (DRP) and a salt to a reaction temperature above the salt’s melting point and at a DRP / salt volume ratio sufficient to form the desired DR powder, with the ratio being at least 0.75, 1, 1.2., 1.4, 1.5 to any practicable amount such as 5). The ratio is believed, without being limiting, to be desirable in limiting the solid state reactions that may occur prior to salt’s melting as well as having a sufficient amount of salt to dissolve one or more of the DRPs sufficiently to realize the desired DR powder. The salt may preferentially dissolve one or more of the DRPs under the heating conditions, such as those that are comprised of Li or Mn. The salt method described herein surprisingly make cathode DR containing particles with much larger sizes than typical for DR pure particles. The salt method, illustratively, may form composite particles having an average particle size of 0.1 micrometers to 2 micrometers and the method allows for the formation of composite particles that may have an average size that is the same or within 50% of the size as the DR or DDR from which it is made.

[0054] In the salt method herein, the salt and each DRP are a powder. To facilitate the formation of desired DR powder, each of these precursor powders are of a similar particle size and size distribution that are uniformly distributed in a precursor mixture (illustratively, a random 10 samples desirably have a ratio of salt / DRP within 20%, 10%, 5%, 2% or 1% of each other). Similar particle size meaning that the average particle size of each of these powders are within an order of magnitude of each other, but preferably the average size 5X or 2X from each other. Generally, the salt and DRPs powders have an average size (volume) of at most about 20 micrometers, 15, micrometers, 10 micrometers, 5 micrometers or 2 micrometers to at least about 0.1 micrometers.It may be desirable for the DRPs lacking Mn and Li to have a particle size (volume) that is less than the particle size of the DRPs having Li or Mn (e.g., average size 5%, 10%, 20% or 50% smaller).

[0055] When employing the salt method, the heating rate, to realize the desired particle size, size distribution and morphology, is desirably as rapid as possible and the time at the DR synthesis temperature is generally from 1, 2, 3 or 5 minutes to 30, 15 or 10 minutes.

[0056] 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.

[0057] The desired DR composition for the DDR may be any useful DR and in particular those comprised of Mn or Mn and Ti. Illustratively, the DR and subsequent CP made from the DR may be one represented by 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)<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, 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 or CP.

[0058] 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) is 0.05 to 1.5, 1, 0.95, 0.8, 0.65, 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. The ratio between P, N and S when two or more arc present may be any useful ratio depending on the attributes sought. For example, it may be desirable to have S present when a reduced redoxpotential is desired. It may also be desirable for S to be the majority of the P, S and N present in the composition.

[0059] The composition 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.

[0060] The cation of the composition 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.

[0061] One or more of the DRPs may be compounds (e.g., metal compound) comprised of oxygen, fluorine and one or more P, S and N, such as oxides, hydroxides, oxynitrides, nitrides, nitrates, sulfides, sulfates, sulfites, phosphates, phosphites, fluorides and combinations thereof. Examples of precursors may include MinO-,. MnO, LiOH, NbiOs, LiF, NbFs, and / or the like. For doping the oxygen site with one or more of P, S and N at least one precursor includes one of these elements. Possible P, S and N precursors may include elemental P, S or N, metal nitrides (e.g. lithium nitride), metal nitrates, metal nitrites, metal phosphates, metal phosphides, metal phosphites, metal sulfites, metal sulfates, metal sulfides (e.g., lithium sulfide), wherein the metal is one that is desired in the DR to form the DDR used to make the CP.

[0062] The DRPs may be mixed dry, at the desired amounts to realize the desired DR stoichiometry, or in a liquid such as water or organic solvent to make a suspension. The mixing may be performed by any method useful to realize the desired particle size with examples being a micromedia mill, ball mill, planetary mill or attrition mill. The primary particles may have any useful average particle size as previously described with particles of at most 2 micrometer, 1 micrometer, 400 nanometers (nm), 200 nm, or 100 nm being useful. An Example of a suitable micro bead mill is a Buhler PML2 mill (Buhler Group).

[0063] The suspension of DRP particles may then be dried, if wet mixed, by any suitable method such as spray drying to form secondary particles. The spray drying may be performed using any known commercially available spray dryer such as a mini spray dryer, such as the Buchi B-290 model. When using the salt method, the amount of salt must be sufficient to enable the formation of the desired particle size and morphology as described above without having to pulverize the DDR or CP powder. Generally, the amount of salt as given by the DRP / salt by weight is at least about 0.5, 0.75 or 1 to 2, 1.75 or 1.5.

[0064] The salt may be any that melts at a temperature below the DR synthesis temperature with the salt desirably melting 10%, 20% or 30% to about 50% below the DR synthesis temperature. Illustratively, the salt desirably has a melting temperature from 400 °C or 500 °C to 700 °C, allowing for the further practicable crystallization of the DR below the salt’ s melting point without any substantial growth of the particles (e.g., average size is within 20%, 10% or 5% by number or volume) of the same material not held at crystallization temperature within the solid salt. The crystallization temperature generally is at least 400 °C, 450 °C, or 500 °C to the melting point of the salt.

[0065] In an illustration the salt method to form Mn containing DRs to be transformed to composite particles may desirably employ disordered rocksalt precursors (DRPs) comprised of a disordered rocksalt precursor having a lower solubility (lower solubility DRP) in the salt in its molten state and disordered rocksalt precursors having a higher solubility (higher solubility DRP) in the salt in its molten state and the disordered rocksalt precursors having higher solubility are comprised of Mn or Li and the disordered rocksalt precursors having lower solubility are in the absence of Mn and Li. In a preferred salt method, the lower solubility DRP are not fully dissolved in the molten salt and act as nucleation sites for the formation of the DR to form the DDR. Desirably, the lower solubility DRPs have an average particle size that is less than the higher solubility disordered rocksalt precursors’ particle size.

[0066] The salt may be any useful salt having the aforementioned characteristics including those having an atomic radius (van der Waals atomic radii) sufficiently larger than the corresponding ion in the DR used to form the DDR that at most a trace amount of salt ion is present in the DR and subsequent DDRs and CPs produced therefrom. Trace is any amount of at most about 10 ppm to the detectability limits by known analytical techniques (e.g., 1 part per billion byweight). Generally, the salt elements are at least 10%, 20% or 30% larger than the corresponding Li and O in the DR. Exemplary salts include KBr, KC1, KI, CsBr, CsCl and any combination thereof.

[0067] The dry DRP particles may then be heated to a DR synthesis temperature. The DR synthesis temperature causes the DRPs to react and form a DR single phase. The DR synthesis temperature generally is from 800 °C to 900 °C, 1100 °C or 1200 °C for a time period from 10 min, 1, 2, 3, or 5 hours to 12 or 24 hours when using the solid state synthesis method. When employing the salt method, the heating rate, to realize the desired particle size, size distribution and morphology, is desirably as rapid as possible and the time at the DR synthesis temperature is generally from 1, 2, 3 or 5 minutes to 30, 15 or 10 minutes.

[0068] The heating rate may be any sufficient to realize the desired particle characteristics of the DR, and illustratively for the salt method the heating and cooling rate is advantageously sufficiently rapid to realize the desired particle characteristics without having to further pulverize or mill the resultant DR. Exemplary salt method heating / cooling rates include those that are at least 10 °C / minute, 25 °C / minute, 50 °C / minute or 100 °C / minute to any practicable heating and cooling rate. The rapid heating rate and cooling rate is the average rate from the salts melting temperature to the DR synthesis temperature. The rate below the melting temperature may be any rate and it may be advantageous to cool below the salt melting point at slower rates or have a hold temperature to improve a DR characteristic such as increasing the crystallinity, without causing undesired characteristics (e.g., particle growth). Illustratively, the temperature may be held at a temperature from about 300 °C to the melting point of the salt and typically from about 400 °C to 600 °C.

[0069] The DR synthesis may be performed under any suitable atmosphere, which may be static or flowing. The annealing environment may be under a noble gas, nitrogen, atmospheric air or dry air and combination thereof to realize a desired partial pressure of one or more gases. In other embodiments, the synthesis conditions may be selected based on the compositions of the disordered rocksalt precursors, such as which metals are present. For example, a manganese-based composition may utilize the conditions above (e.g., 750-900 °C for between 6 and 24 hours), whereas a composition based on another metal may have a broader temperature range, a higherrange, or a lower range and / or a broader, longer, or shorter range of time periods, or multiple thermal steps.

[0070] After the DR is formed the DDR may be formed as described above. Illustratively, the salt may be removed from the DR formed by the salt method herein, by dissolving the salt in water and may include slightly acidic water (pH 1 to below 7) or basic water (pH above 7 to 14) and separated by filtration, settling or centrifugation. The separated powder may then be washed in neutral or basic water to create the DDR. Alternatively, the DDR may be produced by heating to 300 °C to 500 °C in an atmosphere comprised of oxygen with air being suitable. The DDR produced by heating in an oxygen atmosphere may be further washed with neutral or basic water (pH >7 to 14) with a lithium hydroxide solution having a pH of at least 10, 10.5 or 11 being preferred. The CP is then formed from the DDR as described above.

[0071] The CP may be used to form a cathode by any suitable method such as those known in the art. For example, the CP may be mixed with a binder such a polymer useful to make cathodes (e.g., polyfluoropolymer such as polyvinylidene fluoride) and 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.

[0072] Desirably the CP of the cathode has an average secondary particle size of 1 to 20 micrometers. Each of the secondary particles is an agglomeration of primary particles. The CP primary particles desirably have an average particle size as described herein and may contain other particles that may be useful such as increasing the electrical conductivity (e.g., carbon or other inorganic high ionic conductive particles).

[0073] The CP cathode 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.

[0074] The CP cathode desirably is further comprised of carbon. The CP that is formed may be mixed by any method with milling as described herein being a suitable method with other components useful to make an electrode. For example, carbon may be added. The carbon may be added via a suspension and spray dried to form spray dried particles. The carbon may include acetylene black, carbon black, carbon fiber, graphite, carbon nano-tube, KJ600, and / or the like. The carbon may be mixed at a ratio in which the CP represents a majority and the carbon precursors represent a minority. For example, the CP and carbon may each be present in an amount such that the amount of CP / amount of carbon by weight may be a ratio of 100 / 1, 50 / 1 30 / 1, 20 / 1 or 10 / 1 to 5 / 1, 1.5 / or 1 / 1.Illustrations

[0075] Illustration 1. A method to form a composite particle comprising, removing lithium from a disordered rocksalt to form a lithium deficient disordered rocksalt and heating the lithium deficient disordered rocksalt for a transformation time and transformation temperature to form the composite particle having nanodomains of disordered rocksalt and at least one of spinel and monoclinic interspersed therein

[0076] Illustration 2. The method of illustration 1, wherein the removing of the lithium comprises one or more of aqueous washing the disordered rocksalt and heating to 200 °C to 600 °C in an atmosphere comprised of oxygen.

[0077] Illustration 3. The method of illustration 2, wherein the removing is comprised of aqueous washing in basic water.

[0078] Illustration 4. The method of illustration 3, wherein the basic water is comprised of ammonia, an alkali hydroxide or combination thereof dissolved therein.

[0079] Illustration 5. The method of illustration 4, wherein the basic water is comprised one or more of lithium hydroxide and ammonia dissolved therein.

[0080] Illustration 6. The method of illustration 2, wherein the removing is comprised of heating to 300 °C to 500 °C.

[0081] Illustration 7. The method of illustration 6, wherein the atmosphere has a mole fraction of oxygen of at least 0.1.

[0082] Illustration 8. The method of illustration 6, wherein mole fraction of oxygen is at least 0.2.

[0083] Illustration 9. The method of any one of preceding illustrations, wherein the composite particle has an average primary particle size of at most 20 micrometers.

[0084] Illustration 10. The method of illustration 8, wherein the composite particles have an average primary particle size of 0.1 micrometers to 2 micrometers.

[0085] Illustration 11. The method of either illustration 9 or 10, wherein the disordered rocksalt is a disordered rocksalt powder having an average size that is within 50% of the average size of the composite powder.

[0086] Illustration 12. The method of any one of the preceding illustrations, wherein the disordered rocksalt is prepared by reacting, in a salt that is molten, disordered rocksalt precursors comprised of a disordered rocksalt precursor having a lower solubility in the salt in its molten state and a disordered rocksalt precursor having a higher solubility in the salt in its molten state and the disordered rocksalt precursor having higher solubility are comprised of Mn or Li and the disordered rocksalt precursors having lower solubility lack Mn and Li.

[0087] Illustration 13. The method of illustration 12, wherein the lower solubility disordered rocksalt precursors have an average particle size that is less than the higher solubility disordered rocksalt precursors’ particle size.

[0088] Illustration 14. The method of any one of the preceding illustrations, wherein the nanodomains have an average size of at most about 20 nm.

[0089] Illustration 15. The method of any one of the preceding illustrations wherein the heating to the transformation temperature and transformation time is in a transformation atmosphere with or without oxygen.

[0090] Illustration 16. The method of illustration 15, wherein the transformation atmosphere is a noble gas.

[0091] Illustration 17. The method of illustration 15, wherein the transformation temperature is from 300 °C to 600 °C and the transformation time is at least 30 minutes to 10 hours.

[0092] Illustration 18. A powder comprising a composite particle having interspersed disordered rocksalt domains and domains of spinel, monoclinic or both therein.

[0093] Illustration 19. The powder of illustration 18, wherein the domains have an average size of at most about 25 nm.

[0094] Illustration 20. The powder of illustration 18 wherein the composite particle has primary particles having a D90 of at most about 1.5 micrometers, D50 that is submicrometer, and a D10 of at least 0.1 micrometer.

[0095] Illustration 21. The powder of any one of illustrations 18 to 20, wherein at least 60% of the primary particles by number have a circularity of at least 0.65.

[0096] Illustration 22. The powder of any one of illustrations 17 to 21, wherein the composite particle has spinel and disordered rocksalt ( / -spacings that arc distinct in the 200 plane.

[0097] Illustration 23. The powder of illustration 22, wherein the spinel ^-spacing is about0.41 nm and the disordered rocksalt ( / -spacing is about 0.2 nm.

[0098] Illustration 24. The powder of any one of illustrations 18 to 23, wherein the composite particle has a chemistry represented byLixM yMzO2-(a+b)FaZb 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.

[0099] Illustration 25. The powder of illustration 24, wherein M is comprised of one or more of Ti, Mn, Fe, Co,V, Cr, Ni and Cu.

[0100] Illustration 26. The powder of illustration 25, wherein M is comprised of Ti andMn.

[0101] Illustration 27. The powder of illustrations 24 or 25, wherein M’ is comprised ofNb and M is comprised of Mn.

[0102] Illustration 28. The powder of illustration 26, wherein the domains are comprised of monoclinic domains.

[0103] Illustration 29. The powder of claim 27, wherein the domains are comprised of spinel domains.

[0104] Illustration 30. A cathode comprised of the powder of any one of illustrations 18 to29 and carbon.

[0105] Illustration 31. A battery comprised of the cathode of illustration 30.

[0106] Illustration 32. The method of any one of illustrations 1 to 14, wherein the lithium deficient disordered rocksalt has a lithium gradient of at least 5% difference from its shell to core.Examples

[0107] Initial Mn-DR synthesis by a molten-salt method or a solid-state method

[0108] Solid State method: we first prepare the powder mixture of a proper amount of I 2CO3, Mn20a, TiCh / bfeOs / etc., precursors to synthesize Mn-DR compounds using ball milling (e.g., 500 rpm for 6 hours, using acetone as the ball mill medium or dry milling). Then, the mixed Mn-DR precursors are placed in a crucible and heated under Ar at a high temperature (e.g., 1000 °C for 2 hours). After the high-temperature solid-state synthesis, the particles are milled by hand grinding or ball milling.

[0109] If using a molten- salt method to produce Mn-DR, in addition to LiiCOs M112O3 TiO2 / Nb2Os / etc., we mix additional salts, such as CsBr / KBr / NaCl, to prepare the Mn-DR precursors: Here, the molten-salt flux (e.g., CsBr) helps to create single-crystal at a low temperature. We mix all chemicals in a planetary ball mill using certain ball mill conditions (e.g., 500 rpm for 6 hours). The powder was then gathered and left to dry in the vacuum oven overnight (e.g., at 80°C).

[0110] The dried powder is then placed in a crucible and heated under Ar at a temperature higher than the employed salt's melting point (e.g., 800 °C, 830 °C, 850 °C and 900 °C) for a brief length of time (e.g., 3, 5, 7,10, 15 minutes) in a furnace (e.g., rapid-heating furnace). The sample may further undergo additional annealing at a temperature (e.g., 600 °C) below the melting point of the molten-salt flux for a crystallization time (e.g., 1 to 10 hours), which helps remove possible compositional inhomogeneity in the Mn-DR particles and increase the crystallinity.

[0111] Then, the solidified sample is removed from the furnace once it has cooled to room temperature, cleaned with room temperature water or basic water (e.g., LiOH solution), and dried overnight in a vacuum oven (e.g., at 80°C).

[0112] A second heating under air, 02(g), or Ar to induce the formation of the composite particle is employed. For Mn-DR particles without Li-vacancies (lack of a chemical gradient) after the synthesis during Step 1, air or 02(g) reannealing at an elevated temperature (e.g., 300- 500°C) is used to pull out Li from the Mn-DR structure upon air or 02(g) reacting with Li from Mn-DR to form Li2CO or LiOH at the particle surface. Then, the Mn-DR with Li-vacanciesundergoes nanophase separation into DR and spinel nanocomposite at an elevated temperature. For Mn-DR particles with Li-vacancies after the synthesis during Step 1, air, 02(g), and Ar can all be used to directly transform the DDR to the nanocomposite particle heating to an elevated temperature (e.g., 300-600 °C).

[0113] After the heating to induce the formation of the composite particles having the nanodomains, the CPs go through a washing step (e.g., with a LiOH solution) to remove surface U2CO3 or LiOH on the final compound. After the washing, the sample is dried in a vacuum oven (e.g., at 80°C).

[0114] Figure 1 shows the XRD patterns of Li1 2Mno4Tio4O2 (LMTO) synthesized using the molten salt method before and after heating to the transformation time and temperature in air and Ar gases for 5 hours at different temperatures (300°C, 400°C, and 500°C) for LMTO synthesized at 800 °C for 5 minutes, annealing at 600 °C for 20 hours and water washed with deionized water. The XRD results show that the DR before the heating to the transformation temperature has a pure DR phase with high crystallinity. Additionally, the XRD results demonstrate how the phase transformation to spinel evolved (denoted with a star in the XRD pattern) when heated to different transformation temperatures in Ar and air. They also show that at the same temperature, the phase transformation in the air is higher than in argon. Upon heating in air (or O2(g) annealing), it is believed that Li-vacancies are introduced in Mn-DR upon Li-extraction from Mn-DR by air (or O2) to form surface Li2COa or LiOH, which in turn allows additional cation rearrangements resulting in the formation of more spinel nanodomains. In principle, Ar-reannealing of the Mn-DR without any Li-vacancies (Li chemical gradient) should not show such spinel formation, but the ones made by the salt method already have some Li-vacancies in Mn-DR, which is believed to be due to Li+-H+exchange upon washing in neutral or basic water (this Li+-H+exchange level correlates with the pH). The SEM images for the pristine DR material and the materials prior to and after heating to the transformation temperature in argon and air and are shown in Figures 2-4. These Figures show that the CP retained its size and morphology after heating to the transformation temperature comparing Figure 2 to Figures 3 and 4.

[0115] The XRD patterns of the solid-state Mn-DR (LMTO) before and after Ar and air annealing are shown in Figure 5. As opposed to the molten salt synthesized Mn-DR, the Ar- annealed sample shows no spinel transformation. This is believed to be due the lack of a sufficientLi gradient (insufficient Li-vacancies at the surface for example) are created during the solid-state synthesis of Mn-DR, leaving no driving force for spinel formation upon Ar annealing where there is no driving force for creating surface Li-species (LiiCOk LiOH) by reacting with Ar. This, in turn, results in simple annealing of Mn-DR with improved DR crystal structure. In contrast when the solid-state LMTO is exposed to air annealing, Li-extraction by air (to form surface Li^COa, LiOH) creates Li-vacancies to trigger the formation of spinel nanodomains. SEM data on the air- anncalcd DR (formed by solid-state synthesis) shows signs of surface species formation Figures 9 and 10 and in particular Figure 10 compared to the solid state prepared Mn-DR. In contrast, the Ar heat treated DR (Figures 5, 7 and 8) displays no spinel formation and slight growth but with retention of the morphology of the as solid state synthesized Mn-DR (Figure 6 of the as synthesized v. Figures 7 and 8).

[0116] Figure 11 shows the cross-section of the composite particle from a DDR (LMTO) formed by the molten salt method. Figure 12 shows the HRTEM of the cross-section of the composite particle. Figure 13 shows the focused ion beam (FIB) cross-section of the flat field filtering for the inverse fast Fourier transformation (FFT) of the HRTEM image of the composite particles showing disordered rock salt domains (darker regions) and spinel domains (lighter regions) in the composite particles. Figures 14 and 15 show the electron diffraction pattern of the composite particle where composite particle displays distinct d-spacing of the DR domains of 0.201 nm and spinel domains of 0.4121 nm along the 200 plane.

[0117] Figures 16-18 show the voltage profiles of batteries made with disordered rock salt particles made by the molten salt method and the composite particles made therefrom. In Figure 16, the DR made from the molten salt method (shown in Figure 2) and the composite particles of Figure 4 are made into battery cells using the same materials and methods.

[0118] The particle size of molten salt DR is 500-800 nm (Fig. 1), which is much larger than the reported diameter of LMTO DR formed when using a solid state synthesis as described herein. The composite particles made from this DR have similar particles size of about 500 nm to 1 micrometer (Figure 4). The first discharge capacity of the DR is only 53 mAh / g, whereas it is 215 mAh / g for the composite particles formed at 300°C (LMTO air-annealed at 300°C) and -200 mAh / g for both LMTO-400°C and LMTO-500°C (Figures 16, 17A-C and 18). A greater discharge capacity and cycling stability is seen for a higher spinel ratio (induced with higher air annealingtemperature) in a nanocomposite structure. For instance, the discharge capacity of LMTO-300°C composite particle containing battery reduces from 215 mAh / g to 170 mAh / g after 30 cycles (Figure 18). In contrast, LMTO-400°C composite particle containing battery increases its capacity to 230 mAh / g during the initial cycles, then gradually decreases to 202 mAh / g after almost 28 cycles. Likewise, the LMTO-500°C composite particle containing battery also showed an increase in initial capacity during charge and discharge, followed by a reduction in discharge capacity (Figure 18). The use of composite particles in a battery clearly improves the performance compared to particles only with a disordered rocksalt crystalline structure. To our knowledge, a reversible capacity of over 200 mAh / g has never been achieved for single-crystal Mn-DR cathode particles particularly at the particle size range as achieved by the composite particles having DR and spinel domains.

[0119] Li1.2Mno.6Nbo.2O2 (LMNO) DR is made by the salt method described above to form a DDR, which is then subject to heating in air (200 °C, 300 °C, and 400 °C) for 5 hours. The LMNO is synthesized using NaCl with the salt to precursor ratio (1:0.5) at 950 °C for 5 minutes. After Air annealing Figure 19 shows that 200 °C air heating is insufficient to form any detectable spinel by X-ray diffraction (XRD), where the XRD patterns revealed spinel formation at 300 °C and 400 °C (depicted as a star in the XRD). Figure 20 shows the SEM images of the air-annealed LMNO, showing a primary particle size of about 800 nm to about 1000 nm for the 300 and 400 °C annealed LMNO (composite particles), with the 200 °C, being a smaller size of about 500 nm having only DR crystalline structure (Figure 19). The voltage profiles of batteries with cathodes of these materials are shown in Figure 21 and 22 (cycled between 1.5-4.8 V at 20 mA / g and 40 mA / g respectively). The reversible capacity of >200 mAh / g of the composite particles (300 and 400 °C) even at high current charge and discharge has not been achieved in a single-crystal Mn- DR particles, making our capacity close to 250 mAh / g in 800-1000 nm single-crystal composite particles remarkable. Overall, our demonstration of high capacity composite particles formed from both LMTO and LMNO shows the universality of this invention to make high-capacity Mn-DR cathode materials without the need to reduce particle size by particle pulverization to enable high capacity.

[0120] Figure 23 shows LMTO made by the salt method subject to heating in air. The top pattern shows an LMTO that has been synthesized at 800 °C for 5 minutes and annealed for 20hours at 600 °C and washed with a LiOH solution to remove the LMTO from the salt that has been subject to heating in air at 300 °C for 5 hours. The spinel peaks are readily apparent as previously observed in Figure 1. Figure 23 shows the formation of spinel domains initially at 300 °C and then evolution of the spinel domains to a monoclinic phase at a temperature of above 400 °C that becomes further defined by the peak centered about 21 ° 20 as shown in bottom X-ray pattern which is subjected to heating to 500 °C for 5 hours. The middle pattern is of an LMTO synthesized at 900 °C for 20 minutes and annealed at 600 °C for 20 hours and then subject to heating in air for 5 hours at 400 °C. It appears that a monoclinic peak is beginning to form, which may be due to the greater crystallinity of the higher synthesis temperature and time. Heat treatments of the 900 °C synthesized LMTO as just described display more distinct monoclinic peaks about 21 ° 20 when heat treated at 500 °C and 600 °C for 5 hours.

[0121] Figure 24 shows LMTO particles synthesized at 900 °C for 20 minutes and annealed at 600 °C for 20 hours and then subject to heating in air for 5 hours at 300 °C. This Figures shows the particles are substantially larger than those synthesized at lower temperatures for shorter times such as shown in Figures 2-4. Figure 25 shows the cycling behavior of a battery made as previously described using LMTO synthesized at 900 °C as described above and heating in air for 5 hours at 500 °C. From this cycling behavior it is apparent that the LMTO with the larger size and monoclinic domains results in good initial capacity that increases with cycles. Likewise similar behavior is shown for the same material after heating in air at 600 °C for 5 hours as shown in Figure 26, where the initial capacity rises from about 190 mAh / g at the 1stcycle rising to about 210 to 217 mAh / g at the 10 cycle.

[0122] Figures 27-29 show the voltage profiles of LMTO that has been synthesized at 800 °C for 5 minutes and annealed for 20 hours at 600 °C and washed with a LiOH solution to remove the LMTO from the salt and then heated in air at 300 °C, 400 °C, and 500 °C for 5 hours as noted on each of these Figures. Figures 28 and 29 composite particles display a monoclinic peak at 21 ° 20 in the X-ray diffraction pattern and have similar voltage profiles compared to Figure 27 displaying a differing profile particular the 1stand 5thcycles (capacity increases for from 1stto 5thcycle for the batteries containing composite particles displaying a monoclinic peak.

Claims

WHAT IS CLAIMED IS:

1. A method to form a composite particle comprising, removing lithium from a disordered rocksalt to form a lithium deficient disordered rocksalt and heating the lithium deficient disordered rocksalt for a transformation time and transformation temperature to form the composite particle having nanodomains of disordered rocksalt and at least one of spinel and monoclinic interspersed therein.

2. The method of claim 1, wherein the removing of the lithium comprises one or more of aqueous washing the disordered rocksalt and heating to 200 °C to 600 °C in an atmosphere comprised of oxygen.

3. The method of claim 2, wherein the removing is comprised of aqueous washing in basic water.

4. The method of claim 3, wherein the basic water is comprised of ammonia, an alkali hydroxide or combination thereof dissolved therein.

5. The method of claim 4, wherein the basic water is comprised one or more of lithium hydroxide and ammonia dissolved therein.

6. The method of claim 2, wherein the removing is comprised of heating to 300 °C to 500 °C.

7. The method of claim 6, wherein the atmosphere has a mole fraction of oxygen of at least 0.1.

8. The method of claim 6, wherein mole fraction of oxygen is at least 0.2.

9. The method of claim 1, wherein the composite particle has an average primary particle size of at most 20 micrometers.

10. The method of claim 9, wherein the composite particles have an average primary particle size of 0.1 micrometers to 2 micrometers.

11. The method of 10, wherein the disordered rocksalt is a disordered rocksalt powder having an average size that is within 50% of the average size of the composite particles.

12. The method of claim 1, wherein the disordered rocksalt is prepared by reacting, in a salt that is molten, disordered rocksalt precursors comprised of a disordered rocksalt precursor having a lower solubility in the salt in its molten state and a disordered rocksalt precursor having a higher solubility in the salt in its molten state and the disordered rocksalt precursor having higher solubility are comprised of Mn or Li and the disordered rocksalt precursors having lower solubility lack Mn and Li.

13. The method of claim 12, wherein the lower solubility disordered rocksalt precursors have an average particle size that is less than the higher solubility disordered rocksalt precursors’ particle size.

14. The method claim 1, wherein the nanodomains have an average size of at most about 20 nm.

15. The method of claim 1 wherein the heating to the transformation temperature and transformation time is in a transformation atmosphere with or without oxygen.

16. The method of claim 15, wherein the transformation atmosphere is a noble gas.

17. The method of claim 15, wherein the transformation temperature is from 300 °C to 600 °C and the transformation time is at least 30 minutes to 10 hours.

18. A powder comprising a composite particle having interspersed disordered rocksalt domains and domains of spinel, monoclinic or both therein.

19. The powder of claim 18, wherein the domains have an average size of at most about 25 nm.

20. The powder of claim 18 wherein the composite particle has primary particles having a D90 of at most about 1.5 micrometers, D50 that is submicrometer, and a D10 of at least 0.1 micrometer.

21. The powder of claim 18, wherein at least 60% of the primary particles by number have a circularity of at least 0.65.

22. The powder of claim 18, wherein the composite particle has spinel and disordered rocksalt ( / -spacings that are distinct in the composite particle’s 200 plane.

23. The powder of claim 22, wherein the spinel ( -spacing is about 0.41 nm and the disordered rocksalt ( / -spacing is about 0.2 nm.

24. The powder of claim 18, wherein the composite particle has a chemistry 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 .

25. The powder of claim 24, wherein M is comprised of one or more of Ti, Mn, Fe, Co,V, Cr, Ni and Cu.

26. The powder of claim 25, wherein M is comprised of Ti and Mn.

27. The powder of claim 25, wherein M’ is comprised of Nb and M is comprised of Mn.

28. The powder of claim 26, wherein the domains are comprised of monoclinic domains.

29. The powder of claim 27, wherein the domains are comprised of spinel domains.

30. A cathode comprised of the powder of claim 18 and carbon.

31. A battery comprised of the cathode of claim 30.

32. The method of claim 1, wherein the lithium deficient disordered rocksalt has a lithium gradient of at least 5% difference from its shell to core.

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