WO2024147963A1 - Dry methods for modification of single-crystal battery cathode materials - Google Patents

Abstract

Disclosed herein is a dry post-treatment method for modifying a single-crystal cathode material for battery applications and the product thereof. The method disclosed herein may involve a single-crystal cathode material dry mixed with one or more treatment materials. The one or more treatment materials may be metal compounds having metals selected from the group consisting of Magnesium (Mg), Aluminum (Al), Titanium (Ti), Manganese (Mn), Cobalt (Co), Zinc (Zn), Zirconium (Zr), Niobium (Nb), and Molybdenum (Mo). In a subsequent step, the mixed materials are heated at elevated temperatures which allow the one or more treatment materials to melt and react with lithium residuals on the surface of the single-crystal cathode material.

Description

NOVBS.003WO PATENT DRY METHODS FOR MODIFICATION OF SINGLE-CRYSTAL BATTERY CATHODE MATERIALS INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS [0001] Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. This application claims priority to U.S. Provisional Patent Application No. 63/478,885, filed January 6, 2023, which is hereby incorporated by reference in its entirety. BACKGROUND Field [0002] The disclosure relates to battery materials, including battery cathodes and battery active materials. Related Art [0003] The development of rechargeable high energy density batteries, such as Li- ion batteries, is of great technological importance. Typically, commercial rechargeable Li-ion batteries use a lithium transition metal oxide or a lithium iron phosphate cathode and a graphite anode. While batteries based on such materials are approaching their theoretical energy density limit, significant research and development continues in order to improve other important characteristics such as cycle life, efficiency, and cost. Further, significant research and development continues in order to simplify the methods of production and to reduce the complexity, material amounts, and losses involved. [0004] A typical secondary Li-ion battery cell includes a graphite negative electrode, a lithium metal oxide positive electrode, a polymer separator, an organic electrolyte, and casings. Among them, the lithium metal oxide positive electrode material is a key component in deciding energy storage capability and battery cost. Among several types of lithium metal oxide materials, lithium nickel manganese cobalt oxide, known as “NMC”, is one of the most preferred cathode materials to be used in commercial battery cells. [0005] A battery cathode material production process typically consists of two main steps including precursor sintering/calcination and post-treatment. After calcination, the as-prepared cathode materials usually have many lithium residuals on the surface, which cause electrode slurry gelation and large gas formation during battery operations. The formation of gas is highly undesirable as battery casings and other structures are inelastic, thus subject to rupture. To solve these problems, as-prepared cathode materials can undergo a post-treatment process to remove lithium residuals and possibly form surface coatings. Usually, as-prepared cathode materials are washed using water or organic solvents followed by subsequent wet coating. As for the wet-coating process, coating chemicals are dissolved in water, organic solvents, or mixtures of the two. After mixing the coating solution with as-prepared cathode materials, the mixtures are filtered or evaporated before carrying out the second refiring to obtain good and uniform surface coatings. Overall, washing and wet-coating are energy extensive processes and produce a large amount of wastewater. More importantly, Ni-rich cathode materials are sensitive to moisture exposure, making the washing and wet-coating process less favorable as a universal post-treatment process. SUMMARY [0006] The disclosure herein relates to a dry post-treatment method for modifying a single crystal cathode material for battery applications. The method consists of two general steps. In the first step, the single-crystal cathode material is dry mixed with one or more treatment materials in compound form having metals selected from Magnesium (Mg), Aluminum (Al), Titanium (Ti), Manganese (Mn), Cobalt (Co), Zinc (Zn), Zirconium (Zr), Niobium (Nb), and Molybdenum (Mo). In the second step, the mixture of the single-crystal cathode material and the one or more treatment materials are heated at elevated temperatures which allow chemicals to melt, decompose, and react with lithium residuals on the surface of single-crystal cathode materials. [0007] The post-treatment processes herein produce improvements in charge and discharge properties of the post-treated cathode materials. Further the dry post-treatment processes herein show unexpected results, as examples disclosed herein show an improvement or reduction in lithium residuals in single crystal materials but do not lead to a reduction in lithium residuals in the polycrystalline materials. Counterintuitively, the polycrystalline cathode materials showed an increase, not a reduction, in lithium residuals, where the single crystalline cathode materials showed a large decrease in lithium residuals. For example, the post-treatment processes herein lead to an increase in lithium residuals in treated and/or refired polycrystalline cathode materials compared to pristine polycrystalline cathode materials. On the other hand, treated and/or refired single crystalline cathode materials lead to a decrease in lithium residuals compared to pristine single crystalline cathode materials. This is true even though the polycrystalline cathode materials and the single crystalline cathode materials have the same stoichiometric composition. For example, polycrystalline NMC622 showed an increase in lithium residuals and a general increase in surface area when subjected to post- treatment processes disclosed herein. However, single crystalline NMC622 showed a large decrease in lithium residuals and a large reduction in surface area as a result of post-treatment processes disclosed herein. [0008] In some aspects, the techniques described herein relate to a solvent-free method for post-synthesis modification of a single-crystal battery cathode material for lithium- ion batteries, including: providing a single crystal cathode material having a single crystal structure; dry mixing the cathode material with one or more low-melting-point treatment materials in the forms of metal compounds containing one or more metals selected from the group consisting of Magnesium (Mg), Aluminum (Al), Titanium (Ti), Manganese (Mn), Cobalt (Co), Zinc (Zn), Zirconium (Zr), Niobium (Nb), and Molybdenum (Mo); and mixtures thereof; and sintering the single-crystal cathode material mixed with the one or more low- melting-point treatment materials at elevated temperatures to produce a treated single-crystal cathode material. [0009] In some aspects, the techniques described herein relate to a method, wherein the single crystal cathode material has a layered structure with single crystalline morphologies, a D50 particle size in a range of 1^m to 20 ^m, and have a general chemical formula of Li1+x[(NinMnmCoc)1-aAa]1-xO2 where: A is selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and combinations thereof; -0.05 ^ x ^ 0.10; n + m + c = 1; and 0 ^ a ^ 0.05. [0010] In some aspects, the techniques described herein relate to a method, wherein the single crystal cathode material has a spinel structure with single crystalline morphologies, a D50 particle size in a range of 1^m - 30 ^m, and have a general formula of LixMn2-y-zNiyMzO4 where: M is selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Co, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and combinations thereof; 0.25 ^ x ^ 1.1; 0.3 ^ y ^ 0.5; and 0 ^ z ^ 0.15. [0011] In some aspects, the techniques described herein relate to a method, wherein the single crystal cathode material has a layered structure with single crystalline morphologies, a D50 particle size in a range of 1^m to 20 ^m, and have a general chemical formula of Li_1+x[(Ni_nCo_cAl_m)_1-aA_a]_1-xO₂ where: A is selected from the group consisting of Mg, Si, Ca, Ti, V, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and combinations thereof; -0.05 ^ x ^ 0.10; n + m + c = 1; and 0 ^ a ^ 0.05. [0012] In some aspects, the techniques described herein relate to a method, wherein the melting points of the one or more treatment materials are below 500 °C. [0013] In some aspects, the techniques described herein relate to a method, wherein the one or more treatment materials include the forms of metal hydroxides, metal formates, metal acetates, metal oxalates, metal carboxylates, metal phosphates, metal nitrates, metal hydrides, metal benzoates, or combinations thereof. [0014] In some aspects, the techniques described herein relate to a method, wherein an average particle size of the one or more treatment materials is greater than 10 nm and less than 10 ^m. [0015] In some aspects, the techniques described herein relate to a method, wherein the sintering temperatures are above 700 °C and below 950 °C. [0016] In some aspects, the techniques described herein relate to a method, wherein a dwell time for the sintering is greater than 1 min and less than 24 h. [0017] In some aspects, the techniques described herein relate to a method, wherein the sintering is conducted with one or multiple intermediate hold temperatures and the heating and cooling rates range from 0.5 °C/min to 10 °C/min. [0018] In some aspects, the techniques described herein relate to a method, wherein an amount of the one or more treatment materials ranges from about 0.01 wt% to about 1 wt% of the single crystal cathode material. [0019] In some aspects, the techniques described herein relate to a method, wherein an amount of the one or more treatment materials ranges from about 0.01 mole% to about 1 mole% of the single crystal cathode material. [0020] In some aspects, the techniques described herein relate to a method, wherein the dry mixing is performed with a blade grinder, planetary mixer, high-speed conical mixer, mechanofusion, trituration, or acoustic mixer. [0021] In some aspects, the techniques described herein relate to a method, wherein the dry mixing is a heated dry mixing at approximately the melting point of the one or more treatment materials. [0022] In some aspects, the techniques described herein relate to a method, wherein sintering is performed in oxygen, air, or inert gas. [0023] In some aspects, the techniques described herein relate to a method, wherein lithium residuals on the cathode surface in the forms of LiOH and Li2CO3 are reduced by 20% to 75% after the sintering. [0024] In some aspects, the techniques described herein relate to a method, further including detecting the reduction in lithium residuals before and after the post-synthesis modification through an acid-base titration. [0025] In some aspects, the techniques described herein relate to a method, wherein the surface area of the modified cathode is reduced by 10% to 50% after the sintering. [0026] In some aspects, the techniques described herein relate to a method, wherein single crystal cathode material was previously sintered at a temperature exceeding 500°C prior to the dry mixing. [0027] In some aspects, the techniques described herein relate to a method, additionally including applying the treated single-crystal cathode material to a current collector for use as an electrode in a battery. [0028] In some aspects, the techniques described herein relate to a battery including the treated single-crystal cathode material. [0029] In some aspects, the techniques described herein relate to a battery cathode material including: a single crystal having a layered O3 structure; a D50 particle size in a range of 1 ^m to 20 ^m; a treated particle surface treated with residues from one or more metal compounds having a melting point below about 900 degrees Celsius, wherein the metals in the metal compounds are selected from the group consisting of Magnesium (Mg), Aluminum (Al), Titanium (Ti), Manganese (Mn), Cobalt (Co), Zinc (Zn), Zirconium (Zr), Niobium (Nb), and Molybdenum (Mo); and mixtures thereof; a core structure represented by the general formula LxTyMzO2 where: x ^ 0.2; y ^ 0.5; 0.2 ^ z ^ 0; L consists of one or more insertable alkali metals; T consists of two or more first row transition metal elements; and M consists of one or more metal elements other than an alkali metal or a first-row transition metal element; wherein the battery material is free of solvents or solvent residues. [0030] In some aspects, the techniques described herein relate to a battery cathode material, wherein the battery cathode material is free of solvents and solvent residues. [0031] In some aspects, the techniques described herein relate to a battery cathode material, wherein the core structure is represented by the chemical formula Li1+x[(NinMnmCoc)1-aAa]1-xO2 where: A is selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and a combination thereof; where: -0.05 ^ x ^ 0.10; n + m + c = 1; 0 ^ a ^ 0.05; n > 0; m > 0; and c > 0. BRIEF DESCRIPTION OF THE DRAWINGS [0032] Figure 1A shows an SEM image of pristine LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622). [0033] Figure 1B shows an SEM image of refired LiNi0.6Mn0.2Co0.2O2 (NMC622). [0034] Figure 1C shows an SEM image of Zr(OH)4 treated LiNi0.6Mn0.2Co0.2O2 (NMC622). [0035] Figure 2A shows an XRD of pristine LiNi0.6Mn0.2Co0.2O2 (NMC622). [0036] Figure 2B shows an XRD image of refired LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622). [0037] Figure 2C shows an XRD image of Zr(OH)₄ treated LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622). [0038] Figure 3A shows BET surface area of Example 1. [0039] Figure 3B shows lithium residuals in the form of Li2O of Example 1. [0040] Figure 4A shows the discharge capacity of coin-cells made with powders from Example 1. [0041] Figure 4B shows capacity the retention of coin-cells made with powders from Example 1. [0042] Figure 5A shows an SEM image of pristine LiNi_0.80Mn_0.1Co_0.1O₂ (Pristine NMC811). [0043] Figure 5B shows an SEM image of refired LiNi0.8Mn0.1Co0.1O2 (Refired NMC811). [0044] Figure 5C shows an SEM image of Al acetate treated LiNi0.8Mn0.1Co0.1O2 (Al treated NMC811). [0045] Figure 6A shows the XRD pattern of pristine LiNi_0.80Mn_0.1Co_0.1O₂ (Pristine NMC811). [0046] Figure 6B shows an XRD image of refired LiNi_0.8Mn_0.1Co_0.1O₂ (Refired NMC811). [0047] Figure 6C shows an XRD image of Al acetate treated LiNi0.8Mn0.1Co0.1O2 (Al treated NMC811). [0048] Figure 7 shows the lithium residual quantity of powders from Example 2. [0049] Figure 8A shows the specific discharge capacity of coin-cells made with powders from Example 2. [0050] Figure 8B shows the capacity retention of coin-cells made with powders from Example 2. [0051] Figure 9A shows an SEM image of pristine polycrystalline LiNi0.6Mn0.2Co0.2O2 (PC_pristine). [0052] Figure 9B shows an SEM image of pristine single crystal LiNi0.6Mn0.2Co0.2O2 (SC_pristine). [0053] Figure 10A shows an SEM image of refired polycrystalline LiNi_0.6Mn_0.2Co_0.2O₂ (PC_Refired@900). [0054] Figure 10B shows an SEM image of Co(OH)₂ treated polycrystalline LiNi_0.6Mn_0.2Co_0.2O₂ (PC_Co(OH)2 treated Refired@900). [0055] Figure 11A shows an SEM image of refired single crystal LiNi0.6Mn0.2Co0.2O2 (SC_Refired@900). [0056] Figure 11B shows an SEM image of Co(OH)2 treated single crystal LiNi0.6Mn0.2Co0.2O2 (SC_Co(OH)2 treated Refired@900). [0057] Figure 12A shows the BET surface area of polycrystal material from Example 3. [0058] Figure 12B shows the BET surface area of single crystal material from Example 3. [0059] Figure 13A shows lithium residuals in the form of Li2O for polycrystal samples of Example 3. [0060] Figure 13B shows lithium residuals in the form of Li2O for single crystal samples of Example 3. [0061] Figure 14A shows the discharge capacity of coin-cells made with polycrystal powders from Example 3. [0062] Figure 14B shows the discharge capacity of coin-cells made with single crystal powders from Example 3 [0063] Figure 15A shows the capacity retention of coin-cells made with polycrystal powders from Example 3. [0064] Figure 15B shows the capacity retention of coin-cells made with single crystal powders from Example 3. [0065] Figure 16A shows an SEM image of pristine LiNi_0.83Mn_0.06Co_0.11O₂ (NMC83). [0066] Figure 16B shows an SEM image of WO₃ treated LiNi_0.83Mn_0.06Co_0.11O₂ (NMC83). [0067] Figure 17 shows an XRD pattern of Example 4. [0068] Figure 18A shows specific discharge capacity of coin-cells made with powders from Example 4. [0069] Figure 18B shows capacity retention of coin-cells made with powders from Example 4. [0070] Figure 19 is a flow chart illustrating a general process for producing cathode materials according to some embodiments herein. DETAILED DESCRIPTION [0071] The foregoing and other aspects of the present disclosure will now be described in more detail with respect to the description and methodologies provided herein. This description is not intended to be a detailed catalogue of all the ways in which the embodiments of the present disclosure may be implemented. For example, features illustrated with respect to one embodiment may be incorporated into other embodiments, and features illustrated with respect to a particular embodiment may be deleted from that embodiment. Hence, the following specification is intended to illustrate some particular embodiments, and not to exhaustively specify all permutations, combinations and variations thereof. The citation of any document herein is not to be construed as an admission that it is prior art with respect to the present disclosure. [0072] The battery cathode material production process may involve two steps including precursor sintering/calcination and post-treatment. After calcination, the as-prepared cathode materials (pristine cathode materials) usually have many lithium residuals on the surface, which cause electrode slurry gelation and large gas formation during battery operations. To solve these problems, as prepared cathode materials should undergo a post- treatment process to remove lithium residuals and possibly form surface coatings. Usually, as- prepared cathode materials are washed using water or organic solvents followed by subsequent wet coating. As for the wet-coating process, coating chemicals are dissolved in water, organic solvents, or mixtures of two. After mixing the coating solution with as-prepared cathode materials, the mixtures are filtered or evaporated before carrying out the second refiring to obtain good and uniform surface coatings. Overall, washing and wet-coating are energy extensive processes and produce a large amount of wastewater. More importantly, Ni-rich cathode materials are sensitive to moisture exposure, making the washing and wet-coating process less favorable as a universal post-treatment process. [0073] Embodiments of this disclosure present a dry post-treatment process for single-crystal cathode materials, in which single-crystal cathode materials are dry mixed with low-melting point treatment materials in the form of metal compounds followed by a heat treatment. This post-treatment process alters the surface of single crystal cathode materials resulting in finished single-crystal cathode materials with low surface area, smooth surface, low surface lithium residuals, lower gas formation, stable structure, and improved electrochemical performance. Advantageously, this process avoids the use of water or other solvents as a dry process. The dry processes disclosed herein simplify the steps associated with post-treatment processes and reduce the number of byproducts such as aqueous byproducts with harmful chemicals or compounds. [0074] Fig. 19 is a flowchart of an example method for a solvent-free method for post-synthesis modification of single-crystal battery cathode materials for batteries. At step 1910, the method includes providing a single crystal cathode material with a single crystal structure. At step 1920, the method includes dry mixing the single crystal cathode material with one or more low-melting-point treatment materials. At step 1930, the method includes sintering the single-crystal cathode material mixed with the one or more low-melting-point treatment materials at elevated temperatures to produce treated single-crystal cathode materials. [0075] In various embodiments, the provided single crystal cathode materials in step 1910 are pristine single crystal cathode materials. Thus, the single crystal cathode materials have been previously sintered or calcined at temperatures exceeding about 500 degrees Celsius. As such, the sintering in step 1930 may be referred to as a refiring of the single crystal cathode materials. Therefore, the processes disclosed herein relate to post-treatment of single crystal cathode materials, as the single crystal cathode materials have been previously synthesized via sintering. Since the single crystal cathode materials have not been treated or refired at elevated temperatures they may be referred to as pristine single crystal cathode materials prior to treatment and refiring/sintering. [0076] In some embodiments the stoichiometry of the pristine or treated single crystal cathode materials may be represented by the general formula LxTyMzO2 where x ^ 0.2, y ^ 0.5, and 0.2 ^ z ^ 0; L consists of one or more insertable alkali metals (in the case of Li- ion batteries is lithium); T consists of one or more first row transition metal elements; and M consists of one or more metal elements other than an alkali metal or a first-row transition metal element. In some embodiments T consists of two or more first row transition metal elements and Aluminum. In some embodiments, x is about 1, y + z is about 1, and z is less than about 0.1. In some embodiments, x is 1, y + z is 1, and z is less than 0.01. In some embodiments M consists of one or more metal elements other than iron, alkali metals, and first-row transition metal elements. In some embodiments T is three or more first row transition elements. In some embodiments T is Ni, Mn, and Co. Advantageously, the pristine or treated single crystal cathode materials represented by the general formula LxTyMzO2 are free of solvents or solvent residues. [0077] In some embodiments the pristine or treated single crystal cathode materials have the general chemical formula of Li1+x[(NinMnmCoc)1-aAa]1-xO2 wherein A is selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and a combination thereof; -0.05 ^ x ^ 0.10; n + m + c = 1; and 0 ^ a ^ 0.05. The cathode materials represented by the general chemical formula of Li1+x[(NinMnmCoc)1-aAa]1-xO2 may be lithium nickel manganese cobalt oxide battery cathode materials (NMC). In the NMC materials n is greater than zero, m is greater than zero, and c is greater than zero. In some embodiments 0.0001 ^ a ^ 0.05. In some embodiments the battery cathode material may be represented by the general formula Li_1+x[(Ni_nMn_mCo_c)_1-aA_a]_1-xO₂, where -0.03 ^ x ^ 0.06; n + m + c = 1; n ^ 0.05; m ^ 0.05; c ^ 0; A is a metal dopant; and 0 ^ a ^ 0.05. The battery cathode materials may be high energy density LiNMC used in commercial applications with high Ni contents, such that n ^ 0.6. Especially desirable in some applications are single crystal LiNMC lithium transition metal oxide particulate materials, abbreviated as SC-LiNMC and also known as monolithic “NMC”, in which the average LiNMC grain size exceeds 1 ^m. If the grain size is too large, then increased impedance during Li-ion cell operation can result. Therefore, SC-LiNMC, grain sizes (D50) may be present between 1 ^m and 20 ^m. SC-LiNMC particles can consist of multiple LiNMC grains. However, superior capacity retention can be obtained if SC-LiNMC particles each consist of a single LiNMC grain. The D50 particle size of the NMC materials may be in the range of about 500 nm to about 20 ^m, about 800 nm to about 20 ^m, about 900 nm to about 20 ^m, about 1 ^m to about 20 ^m, about 1 ^m to about 15 ^m, about 1 ^m to about 10 ^m, or any range of values in between. [0078] In some embodiments the provided cathode materials have the general formula of Li_xMn_2-y-zNi_yM_zO₄ wherein M is selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Co, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and a combination thereof; 0.25 ^ x ^ 1.1; 0.3 ^ y ^ 0.5; and 0 ^ z ^ 0.15. In some embodiments 0 < z ^ 0.15. The cathode materials represented by the general chemical formula of LixMn2-y-zNiyMzO4 may be lithium manganese oxide battery cathode materials (LMO). The particle size of the LMO battery materials may have a D50 particle size in the range of about 1 ^m to about 30 ^m, about 10 ^m to about 30 ^m, about 1 ^m to about 20 ^m, about 1 ^m to about 10 ^m, about 0.5 ^m to about 30 ^m or any range of values in between. [0079] In some embodiments the provided cathode materials have the general chemical formula of Li1+x[(NinCocAlm)1-aAa]1-xO2 where: A is selected from the group consisting of Mg, Si, Ca, Ti, V, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and a combination thereof; - 0.05 ^ x ^ 0.10; n + m + c = 1; and 0 ^ a ^ 0.05. In some embodiments n is greater than zero, c is greater than zero, and m is greater than zero. The cathode materials represented by the general chemical formula of Li_1+x[(Ni_nCo_cAl_m)_1-aA_a]_1-xO₂ may be lithium nickel cobalt aluminum battery cathode materials (NCA). The particle size of the NCA battery materials may have a D50 particle size in the range of about 500 nm to about 20 ^m, about 500 nm to about 10 ^m, about 10 ^m to about 20 ^m, about 1 ^m to about 10 ^m, or any value in between (i.e. about 10 um). [0080] The low melting point treatment materials that are dry mixed with the single crystal cathode materials may be selected from metal compounds where the metal in the metal compounds is selected from the group consisting of Magnesium (Mg), Aluminum (Al), Titanium (Ti), Manganese (Mn), Cobalt (Co), Zinc (Zn), Zirconium (Zr), Niobium (Nb), and Molybdenum (Mo); and mixtures thereof. [0081] The treatment material compounds having metals selected from the group consisting of Magnesium (Mg), Aluminum (Al), Titanium (Ti), Manganese (Mn), Cobalt (Co), Zinc (Zn), Zirconium (Zr), Niobium (Nb), and Molybdenum (Mo) may be provided in various forms. For example, these low melting point treatment materials may be provided in the form of metal hydroxides, metal formates, metal acetates, metal oxalates, metal carboxylates, metal phosphates, metal nitrates, metal hydrides, metal benzoates, or combinations thereof. For example, the Aluminum may be provided as Aluminum acetate (such as C₆H₉AlO₆), Zinc may be provided as Zinc hydroxide (Zn(OH)₂), or Cobalt may be provided as Co(OH)₂. [0082] The hydroxide, acetate, oxalate, carboxylate, phosphate, nitrate, hydride, or benzoate may be selected such that it melts, disintegrates, or vaporizes into a gas phase at a temperature lower than the melting point of the elemental metal or lower than the boiling point of the lithium residuals such that the treatment metal reacts with the lithium residuals of the single crystal cathode material. In some embodiments the metal compound in the form of a hydroxide, acetate, oxalate, carboxylate, phosphate, nitrate, hydride, or benzoate are selected such that the metal reacts with the lithium residuals on the surface of the single crystal cathode material and forms lithium metal oxide compounds or metal oxide compounds. The lithium metal oxide compounds are advantageous as they remove lithium residuals from the surface of the single crystal cathode material in the formation of the lithium metal oxide compounds. In some embodiments the selected treatment material compounds coat the outer surface of the single crystal cathode materials prior to firing and then partially decompose and/or react with the lithium residuals on the surface of the single crystal cathode material, forming lithium metal oxide compounds. Advantageously, the treated surface and/or metal oxide coating or layer provided by the treatment materials are highly stable at elevated temperatures and in the presence of a battery electrolyte. [0083] In some embodiments the melting point of the treatment material may be based upon the melting point of one or more metal compounds in the form of metal hydroxides, metal formates, metal acetates, metal oxalates, metal carboxylates, metal phosphates, metal nitrates, metal hydrides, metal benzoates, or combinations thereof. As an example, the melting point of the treatment material may be based upon the melting point of Zirconium hydroxide (550°C), Magnesium acetate (80°C), Cobalt hydroxide (168°C), or Zinc Hydroxide (125- 160°C). [0084] In some embodiments the melting point of the treatment material may be based upon the melting point of Magnesium nitrate, Magnesium Phosphate, Magnesium Hydroxide, Magnesium hydride, Aluminum Phosphate, Aluminum acetate, Aluminum nitrate, Aluminum Hydroxide, Titanium acetate, Titanium Phosphate, Titanium nitrate, Manganese acetate, Manganese Phosphate, Manganese nitrate, Cobalt Phosphate, Cobalt acetate, Cobalt nitrate, Zinc Phosphate, Zinc acetate, Zinc nitrate, Zirconium acetate, Zirconium nitrate, Niobium acetate, Niobium nitrate, Molybdenum acetate, or Molybdenum nitrate. [0085] The treatment materials in the form of metal compounds may be selected such that they are below the boiling temperature of LiOH (924°C). Therefore, various metal compounds or salts may be used to react with LiOH on the surface of the single crystal cathode material without LiOH boiling off. In some embodiments the residues of the metal compounds react with the lithium residuals on the surface of the single crystal cathode materials and form lithium compounds. In some embodiments the treatment material compounds react with the lithium residuals on the surface of the single crystal cathode material and form a partial coating or layer on the single crystal cathode material. However, the layer of the treatment materials may be incomplete as the weight percent of the treatment materials ranges from about 0.01 wt% to about 1 wt% of that of the single crystal cathode material or from about 0.01 mole% to about 1 mole% of that of the single crystal cathode material. In some embodiments the amount of the treatment materials may be less than about 1 wt%, less than about 0.5 wt%, less than about 0.25 wt%, or less than about 0.05 wt% of the weight of the single crystal cathode material. In some embodiments the amount of the treatment materials may be less than about 1 mole%, less than about 0.5 mole %, less than about 0.25 mole %, or less than about 0.05 mole % of the weight of the single crystal cathode material or any range of values in between. [0086] In some embodiments the elevated temperatures for sintering may be temperatures exceeding about 400°C, about 500 °C, about 600 °C, about 700 °C, about 800 °C, about 900 °C, about 1000 °C, about 1100 °C, or about 1200 °C. In some embodiments, the elevated temperature is above about 700 °C and below about 950 °C. The sintering time may be in a range of 1 min to 24 hours, 1 minute to 4 hours, at least 30 minutes, at least 1 hour, at least 2 hours, at least 3 hours, at least four hours, or any range of values in between. [0087] In embodiments herein the single crystal cathode precursors have been previously fired at temperatures exceeding 500 °C in order to produce the single crystal cathode materials from feedstock materials such as one or more transition metals or post- transition metals, one or more dopants, and one or more lithium sources. The one or more transition metals or post-transition metals may be one or more aluminum sources, cobalt sources, one or more nickel sources, and/or one or more manganese sources. The nickel, manganese and cobalt may be provided in various ratios to provide different compositions for the single crystal cathode material. In some embodiments the single crystal cathode material is NMC111, NMC532, NMC622, or NMC811. [0088] In various embodiments herein the single crystal cathode material is comprised of particles having a single crystal structure. The single crystal structure should be differentiated from a polycrystalline structure. The single crystal particles are particles that may be generally comprised of a crystal grain. In some embodiments the average grain size of the single crystal cathode material exceeds about 1 ^m, or more than 70% of the particle is comprised of a single crystal grain. In some embodiments the average grain size is at least 30% of the particle size of the single crystal particle, at least about 40% of the particle size, at least about 50% of the particle size, at least about 60% of the particle size, or any range of values in between. In some embodiments the single crystal cathode material is composed of particles having a single, continuous grain or crystal structure. The crystal structure may have a well- defined orientation with no grain boundaries. Single crystal structures may be visually differentiated from polycrystalline structures, such as shown in Figure 9(a) depicting polycrystalline particles and Figure 9(b) showing single crystal particles, both of which are discussed further herein. [0089] Single crystal cathode materials are advantageous as they often exhibit improved electrochemical performance compared to their polycrystalline counterparts. They may offer higher energy density, better rate capability, and longer cycle life. Further, absence of grain boundaries and defects in a single crystal structure can reduce the likelihood of mechanical failures, such as cracking or pulverization, during charge-discharge cycles. Moreover, the absence of grain boundaries can promote faster and more uniform ion diffusion within the cathode material, leading to improved charge and discharge rates. [0090] The cathode post-processing procedures disclosed herein show improved chemical performance due, in part, to reduced cation mixing or cation disorder, where larger cations such as Ni are located where Lithium ions are intended to be or within Lithium layers, or visa versa where lithium ions are where Ni ions are intended to be. Cation mixing can cause reduced electrochemical performance for several reasons. For example, it can disrupt the ordered structure of cathode materials and affect the ability of the cathode material to store and release lithium ions, which reduces the overall efficiency of the cathode material. [0091] Cation disorder can also increase the internal impedance of the cathode material, making it less conductive. This increases the resistance to ion diffusion and electron transport, which can lead to reduced battery performance. Further, since the ordered structure of the cathode material is disrupted, such as the order of a crystalline material, the structural stability of the material decreases to an extent. This can bring about structural distortions, for example in a crystalline material, where disproportionately sized cations weaken the lattice. Materials with low cation mixing can be less prone to phase transformation and cracking during cycling. Thus, the disclosed process is desirable at least because prevents disorder in cation arrangements in single crystal cathode materials. In some embodiments the percent of cation mixing is less than about 7% or the amount of Ni in Li layers, or visa versa, is less than about 7%. [0092] The processes in embodiments herein are also advantageous at least in part because they reduce lithium residuals. Lithium residuals generally comprise unreacted byproducts of lithium precursor materials, such as LiOH and Li2CO3. These residuals are generally undesirable because they can lead to side reactions that reduce battery capacity. The oxidation of these compounds may result in the formation of Li2O and CO2 gas at higher voltages, which lowers the coulombic efficiency between the charge and discharge capacities during cycling. The creation of gasses can also cause fracture or failure of the battery or battery active materials. Finally, lithium impurities can also have a detrimental effect on slurry preparation and the creation of the cathode itself. [0093] The embodiments disclosed herein advantageously reduce lithium residuals on single crystal cathode materials. In some embodiments the post-treatment processes enable a reduction in lithium residuals such that the lithium residuals are less than about 50% of the lithium residuals prior to the post-treatment processes. In further embodiments the lithium residuals in the treated single crystal cathode materials are less than about 40%, less than about 30%, less than about 20%, or less than about 10% of the lithium residuals prior to the post- treatment. Thus, the processes disclosed herein enable at least a 50% reduction in lithium residuals compared to the pristine particles. [0094] In some aspects the disclosure relates to a battery containing the single crystal cathode material produced according to embodiments disclosed herein. The battery materials disclosed herein may be incorporated into various consumer or commercial devices. Examples include but are not limited to personal electronic devices, electric cars or mobility devices, battery storage devices, electric tools, electric bicycles, electric toys, or any other electrically powered device. Definitions [0095] Unless the context requires otherwise, throughout this specification and claims, the words "comprise", “comprising” and the like are to be construed in an open, inclusive sense. The words “a”, “an”, and the like are to be considered as meaning at least one and are not limited to just one. [0096] As used herein, the term “and/or” refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative (“or”). [0097] The term "cathode" should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the disclosure but often refers to the electrode at which reduction occurs when a metal-ion is discharged. In a lithium ion cell, the cathode is the electrode that is lithiated during discharge and delithiated during charge. [0098] With regards to a given item, the transitional phrase “consisting essentially of” is to be construed as limiting to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the given item. [0099] Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. In a quantitative context, the term “about” may be construed as being in the range up to plus 5% and down to minus 5% of the stated value. [0100] The term “stochiometric amount” should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the disclosure but also refers to an amount of reactants in a chemical reaction that allows the reactants to react completely, based on the mole ratios indicated by the balanced chemical equation. [0101] The term “dry” or “liquid-free environment” should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the disclosure but generally refers to an environment that is free or substantially free of solvents including water, organic, or inorganic solvents. [0102] The term “lithium residues” should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art but generally refers to the unreacted byproducts of lithium precursor materials, such as LiOH and Li2CO3. Lithium residues are generally undesirable because they can lead to undesirable side reactions that reduce battery capacity. The oxidation of these compounds may result in the formation of Li2O and CO₂ gas at higher voltages, which lowers the coulombic efficiency between the charge and discharge capacities during cycling. [0103] The term "half-cell" should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the invention but often refers to a cell that has a working electrode and a metal counter/reference electrode. A lithium half-cell has a working electrode and a lithium metal counter/reference electrode. [0104] The term “substantially free” should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the invention but often refers to a minimal amount of something in a material. For example, in some embodiments substantially free means a material may contain less than 1% of something that it is “substantially free” of. [0105] The term “free of” should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the invention but often refers to an insignificant or de minimis amount of something. In certain embodiments herein, the material may only contain trace amounts of the substance (such as water or a solvent) that it is “free of.” [0106] “Elevated temperatures” as described herein generally refers to temperatures exceeding about 400°C. [0107] “Smooth surface” as described herein may be a specific surface area measurement below about 0.7 m²/g as measured by BET surface area measurements. [0108] “Surface area” measurements referred to herein in terms of m²/g are BET surface area measurements. [0109] The term “lithium residues” should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art but generally refers to the unreacted byproducts of lithium precursor materials, such as LiOH and Li₂CO₃. Lithium residues are generally undesirable because they can lead to undesirable side reactions that reduce battery capacity. The oxidation of these compounds may result in the formation of Li₂O and CO2 gas at higher voltages, which lowers the coulombic efficiency between the charge and discharge capacities during cycling. Lithium residues can also be called lithium residuals. [0110] A “high-speed blade grinder” is intended to refer to a blade grinder with RPM in excess of about 100 RPM. A high-speed blade grinder may have a speed in the range of about 200 to about 2000 RPM. The blades of high speed blade grinders are generally flat. In some instances where the length is the longest dimension of the blade, the ratio of the width to the thickness of the blade is at least 5:1. In some instances the blade grinder may produce mechanical forces similar to a coffee grinder, but a high speed blade grinder may be appropriately scaled for commercial use. [0111] “O2 atmosphere” as used herein should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art but generally refers to atmospheric gasses that include oxygen. [0112] “Cation mixing” as described herein should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the invention but often refers to a cation disorder where divalent nickel cations (Ni²⁺) occupy locations in a layered cathode material structure where lithium cations (Li⁺) are intended to reside, and vice versa. [0113] “Pristine single crystal” as described herein generally refers to single- crystal cathode materials that have been synthesized from cathode precursors or feedstock materials that were fired at temperatures exceeding 500 degrees Celsius. Pristine materials have not been subjected to post-treatment processes. The single-crystal cathode material is composed of cathode in a stoichiometric ratio, one example being LiNi_0.6Mn_0.2Co_0.2O₂ for single-crystalline NMC622. The crystal structure of cathode materials may be determined via X-ray diffraction. [0114] The term “stoichiometric” herein should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the invention but often refers to the ratio of reactants in a chemical equation or formula. For example, H2O refers to a ratio of two hydrogen atoms for every one oxygen atom in the water molecule and may be produced according to the stoichiometric equation 2H + O ĺ H₂O. Stoichiometric values may be whole numbers or integers, or they may be fractions that could be multiplied by a number such that they are whole numbers or integers. [0115] The term “molar ratio” herein should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the invention but often refers to the ratio between the amounts in moles of any two compounds. A mole of a substance is equivalent to 6.02214076 x10²³ elementary entities (e.g., atoms, molecules) of that substance. [0116] The term "O3" is intended to refer to phases having a Į-NaFeO₂ type structure, as described in C. Delmas, C. Fouassier, and P. Hagenmuller, Physica, 99B (1980) 81-85. [0117] The term “phase” generally should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art but generally refers a distinct and homogeneous form of matter separated at its surface from other forms of matter. [0118] The term “single crystal” is intended to refer to a lithium transition metal oxide particulate material in which its constituent particles are comprised of about one grain, the average grain size being at least 1 ^m in size. The acronym “SC” refers to single crystalline herein. [0119] The term “polycrystalline” is intended to refer to a lithium transition metal oxide material having particles that are comprised of a plurality of grains or secondary agglomerated particles comprised of primary particles with individual grains. The acronym “PC” refers to polycrystalline herein. [0120] The term “low melting point” is intended to refer to a melting point below about 920°C. [0121] The term “spinel structure” is intended to refer to a crystal lattice where the oxide anions are arranged in a cubic close-packed lattice and the cations are occupying some or all of the octahedral and tetrahedral sites in the lattice. Spinel material may be a single disordered or ordered phase, or a mix of both. [0122] The term “metal compounds” as used herein should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the invention but often refers to compounds containing one or more metal ions and one or more counterions. For example, a metal salt such as Zr(OH)₄ is a metal compound having a metallic ion (Zr⁴⁺) and one or more counterions (OH-). The term “metal compounds” is intended to exclude metals only provided in elemental form. [0123] The term “average grain size” should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the invention but often refers to the grain size as determined by applying the Scherrer equation to the largest x-ray diffraction peak of the particulate for grain sizes less than 100 nm. For grain sizes of 100 nm or more, the average grain size refers to the average length of the greatest dimension of at least 20 random particles as directly observed by SEM. [0124] The term “average particle size” should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the invention but often refers to the average of the greatest dimension of at least 20 random particles as directly observed by a laser particle size analyzer. [0125] The term "grain" should be given its ordinary meaning as it would be understood by a person having ordinary skill in the art at the time of the invention but often refers to a crystallite, the terms being used interchangeably herein. [0126] “Dry mixing” or “solvent free” or “dry” as used herein refers to a process or composition that is free of materials that are in a liquid state at room temperature of about 21 degrees Celsius and atmospheric pressure of about 1 atm. [0127] “Solvent residues” should be interpreted as would be understood by a person having ordinary skill in the art but also refers to elements, particles, or molecules that remain in a material after the liquid phase of a solvent has been removed. These residues include trace minerals or solutes that exist in purified solvents, such as purified water or organic solvents. [0128] Unless sated otherwise all experiments and processes herein were performed under atmospheric pressure. Examples [0129] The following are exemplary in nature to better illustrate the present invention and are non-limiting in scope, application or uses. [0130] Material characterization [0131] Scanning electron microscope (SEM) images were taken using a Phenom XL G2 Desktop SEM with an accelerating voltage of 15 kV under a back scattering electron mode. Powder samples were prepared by adhering onto a sample stub using conductive carbon tape. [0132] X-ray diffraction (XRD) patterns of powders were measured by a Bruker D8 Advance diffractometer with a Cu KĮ X-ray source and a diffracted beam monochromator. Rietveld refinement was done on the measured XRD patterns to quantify the amount of cation mixing, Ni in the Li layers, using Rietica software. [0133] Particle size diffraction (PSD) of powders were measured by a Horiba LA- 950V2 particle size analyzer. Samples were prepared by flocculating in 0.2 wt% sodium hexametaphosphate (NaHMP) in DI water. [0134] Brunauer–Emmett–Teller (BET) surface area of powders was measured by a Quantachrome NOVAtouch LX2 gas sorption system. Samples were prepared by degassing at 760 torr before measurements. [0135] Lithium residuals of powders were measured by a Mettler Toledo Titrator Excellence T5. Samples were prepared by flocculating in water and titrated with 0.1M of HCl to determine LiOH and Li2CO3 content. [0136] Cell preparation and electrochemical evaluation [0137] Electrode slurries were prepared by mixing active material, carbon black (Imerys/Timcal SuperP), and polyvinylidene fluoride (PVDF, Solvay Solef 5130) in a weight ratio of 0.94: 0.04: 0.02 in N-Methyl-2-Pyrrolidone (NMP, Fisher Scientific, 99.9%) with a solid content of 50% using a planetary mixer. The slurry was coated onto 15 μm aluminum foil sheet using the doctor blade method and dried on a 90°C drying table in air before final drying in a vacuum oven at 100-120 °C overnight. The dried electrodes were compressed by calendar rolling and punched with a 13.00 mm diameter. The areal active mass loading was ~18-22 mg/cm². Coin-cells were fabricated in an Argon filled glovebox with one sheet of active electrode, Li foil counter electrode, 2 layers of separator (Celgard 2500), and 100 μL of 1.2M LiPF₆ in a solution of ethylene carbonate:ethylmethyl carbonate:dimethyl carbonate (EC:EMC:DMC (25:5:70 wt%), CapChem) electrolyte using CR2032 coin-type casings. Galvanostatic cycling measurements were made using a NOVONIX ultra high-precision coulometry system at a controlled temperature of 25 °C. [0138] Example 1. [0139] Pristine single-crystalline LiNi0.6Mn0.2Co0.2O2 (NMC622) was made by an all-dry or solid-state method as follows. A mixture of NiO, Co₃O₄, Mn₃O₄, and 5% excess Li₂CO₃ in a stoichiometric ratio of LiNi_0.6Mn_0.2Co_0.2O₂ was mixed in a high-speed blade grinder for 2 minutes. The mixed powder was transferred into an alumina crucible and sequentially heated in a tube furnace under O2 atmosphere at 600°C for 3h, 950°C for 20h, and then cooled down to room temperature. The heating rate and cooling rates were at 10°C/min and 1°C/min, respectively. The calcined product was jet milled to obtain pristine NMC622 material. Zr(OH)4-treated NMC622 was made by mixing the pristine NMC622 with 0.5mol% of Zr(OH)₄ in a blade grinder for 2 minutes, followed by heating to 900°C for 3 hours. The heating and cooling rates were at 10°C/min. The refired NMC622 sample was made by heating the pristine SC NMC622 to 900°C for 3 hours. [0140] Figure 1 demonstrates that the surface of Zr(OH)₄-treated NMC622 (Figure 1(c)) was smoother than that of pristine NMC622 (Figure 1(a)) and refired NMC622 (Figure 1(b)) as demonstrated by the decrease in BET surface area (Figure 3(a)). Figure 2 shows that the crystallinity, which relates to the degree of peak separation between 63.5° and 66° 2^, increased when pristine NMC622 was refired or treated with Zr(OH)4. As shown in Table 1, Zr(OH)₄-treated NMC622 showed lower cation mixing than pristine and refired NMC622. High crystallinity and low cation mixing are two indicators suggesting that Zr(OH)₄-treated NMC622 shows better electrochemical performance than pristine and refired NMC622, as discussed further with regard to Figure 4. [0141] Table 1. Cation mixing through Rietveld refinement of pristine NMC622, refired NMC622, and Zr(OH)4-treated NMC622. Samples Cation Mixing (%) Derived Bragg R-factor (%) Pristine NMC622 2.02 0.74 Refired NMC622 1.89 1.00 Zr(OH)₄-Treated NMC622 1.47 0.93 [0142] Figure 3(A) shows that the surface area of Zr(OH)4-treated NMC622 was three times smaller than that of pristine NMC622. Zr(OH)₄-treated NMC622 has a low surface area at about 0.5 m²/g. Figure 3(B) shows the amount of lithium residuals in the form of Li₂O reduced significantly from ~6000 ppm for pristine NMC622 to below 2000 ppm for both refired NMC622 and Zr(OH)₄-treated NMC622. It is worth noting that reheating step at a high temperature, which was applied to make refired NMC622 and Zr(OH)4-treated NMC622, brought many advantages including lithium residual reduction, surface area reduction, and crystallinity improvement. However, refired NMC622 was not as good as Zr(OH)₄-treated NMC622 in terms of electrochemical performances. Figure 4 shows that Zr(OH)4-treated NMC622 has greater discharge capacity (4(A)) and discharge capacity retention (4(B)) than pristine and refired NMC622. The above results confirm the effectiveness of using Zr(OH)4 to treat NMC622 material. [0143] Example 2. [0144] Pristine single-crystalline LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) was made by the solid-state method as follows. A mixture of Ni, Co, Mn, and 1% excess Li₂CO₃ in a stoichiometric ratio of LiNi_0.8Mn_0.1Co_0.1O₂ was mixed in a high-speed blade grinder for 2 minutes. The mixed powder was transferred into an alumina crucible and sequentially heated in a tube furnace under O2 atmosphere at 600°C for 3 hours, 920°C for an additional 20 hours, 870°C for an additional 5 hours, and then cooled down to room temperature. The heating rate and cooling rates were at 10°C/min and 1°C/min, respectively. The calcined product was jet milled to obtain pristine NMC811 material. Aluminum Acetate-treated NMC811 was made by mixing the pristine NMC811 with 0.25mol% of aluminum acetate basic hydrate in a blade grinder for 2 minutes, followed by heating to 900°C for 3 hours. The heating and cooling rates were at 10°C/min. The refired NMC811 sample was made by heating the pristine NMC811 to 900°C for 3 hours. [0145] Figure 5 shows that the surface of refired and Al acetate-treated NMC811 samples were much smoother than that of pristine NMC811. Figure 6 indicates that the crystallinity of refired and Al acetate-treated NMC811 samples were better than that of pristine NMC811. Figure 7 shows that refired NMC811 contained the lowest amount of surface lithium residuals. Even though Al acetate-treated NMC811 showed lower discharge capacity than the refired and pristine NMC811 as shown in Figure 8(a), their capacity retention was much better than the pristine and refired NMC811 samples, as shown in Figure 8(b). Thus, the Al acetate- treated NMC811 will retain a larger percentage of its capacity (compared to pristine and refired NMC811) as charge and discharge cycles continue. [0146] Example 3. [0147] Pristine single-crystalline (SC) and polycrystalline (PC) LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622) were made by the solid-state method using a co-precipitated hydroxide precursor. Commercially available Ni_0.6Mn_0.2Co_0.2(OH)₂ precursor was mixed with 10% excess Li₂CO₃ in a stoichiometric ratio of LiNi_0.6Mn_0.2Co_0.2O₂ in a high-speed blade grinder for 20 minutes. Then the mixed powder was transferred into an alumina crucible and sequentially heated in a tube furnace under an oxygen atmosphere. The furnace was then cooled down to room temperature. The heating rate and cooling rates were at 5°C/min and 1°C/min, respectively. Sintering temperature and time were kept at 950°C and 20 hours, respectively for single-crystalline NMC622 or 870°C and 20 hours, respectively for polycrystalline NMC622. The calcined single-crystallite NMC622 product was jet milling to break all agglomerates. In contrast, the calcined polycrystalline NMC622 product was used as prepared without any milling to preserve its polycrystalline morphology. [0148] Pristine SC and PC NMC622 samples were refired at 900°C for 3 hours with and without adding Co(OH)2. Table 2 describes the sample information. SEM images of these pristine samples, Pristine SC NMC622 and PC NMC622, are shown in Figure 9. [0149] Table 2. Treatment conditions for each sample Sample name Treatment Material Refiring Temperature (°C) PC_Pristine - - PC_Refired@900C - 900 PC_Co(OH)₂ treated_Refired@900C Co(OH)₂ 900 SC_Pristine - - SC_Refired@900C - 900 SC_Co(OH)₂ treated_Refired@900C Co(OH)₂ 900 [0150] As shown in Figure 10, there was no significant difference in material morphologies of PC NMC622 samples despite refiring with (Figure 10(B)) and without (Figure 10(A)) treatment materials. After refiring, refired SC NMC622 samples (Figure 11(A)) were smoother than pristine SC NMC622 samples that were not refired (Figure 11(B)), as shown in SEM images. This is also demonstrated by the drop in surface area between pristine SC NMC622 and refired SC NMC622 in Figure 12(b). Furthermore, Figure 12 also shows that polycrystalline samples (Figure 12(a)) do not undergo a similar decrease in surface area after refiring or treatments at 900°C as occurs with single crystal samples (Figure 12(b)). Therefore, this method is optimal for single crystal cathode samples and is generally not applicable for polycrystal samples. In addition, the lithium residuals in Figure 13 on the surface of single crystal cathode materials were reduced by ~50%, as shown in Figure 13(b), whereas the lithium residuals on the polycrystal cathode material doubled after refiring or treating with Co(OH)₂ and refiring, as shown in Figure 13(a). The lithium residual on the surface is an indirect indicator of lithiation, the lower the lithium residuals the higher the lithiation. In addition, high lithium residuals in the excess of 2000ppm will impact electrode fabrication due to gelation of the slurry. Therefore, implementing this disclosure on polycrystal cathode materials will generally hinder electrode formation from the high lithium residuals whereas improvements may be seen with refired or treated single crystal cathode materials due to the decrease in lithium residuals. [0151] Figure 14 show galvanostatic cycling of pristine polycrystal cathode material, refired polycrystal cathode material, and polycrystal cathode material that was treated with cobalt hydroxide using the method in this disclosure. From these results, the normalized discharge capacity does not show significant difference between the samples. [0152] Figure 15 shows the galvanostatic cycling of pristine single crystal cathode, refired single crystal cathode, and Co(OH)₂ treated single crystal cathode. As shown in the figure, there is an improvement in the electrochemistry of the material after implementing the methods in this disclosure. Both the discharge capacity and the discharge capacity retention percentage are improved in the coated refired sample compared to pristine SC and pristine SC refired after 25 charge/discharge cycles. Therefore, comparing Figure 14 and Figure 15, the coating treatment outlined in this disclosure does not improve the electrochemistry of polycrystal materials but does show improvement in single crystal cathode materials. [0153] Example 4. [0154] This example, a pristine LiNi_0.83Mn_0.06Co_0.11O₂ (NMC83), was made by mixing Ni powder, Mn powder, Co powder, and 1% excess Li₂CO₃ in a stochiometric ratio of LiNi_0.83Mn_0.06Co_0.11O₂ in an auto-grinder for 30 mins to form a homogenous mixture. The mixed powder was transferred into an alumina crucible and sequentially heated in a tube furnace at 600°C for 3 hours, at 900°C for an additional 20 hours, and at 870°C for an additional 5 hours then cooled down to room temperature under O2 atmosphere. WO3 (Tungsten (IV) oxide) treated NMC83 samples were made by mixing NMC83 with 0.5 mole% WO3 in an auto-grinder for 30 mins. The mixed powder was then transferred into an alumina crucible and heated in a tube furnace at 720 °C for 3 hrs. A heating rate of 10 °C/min and cooling rate of 1°C/min were used. SEM images in Figure 16 demonstrates that the samples have a single crystal morphology with a smooth surface. Figure 16A shows an SEM image of pristine LiNi0.83Mn0.06Co0.11O2 (NMC83) and Figure 16B shows an SEM image of treated LiNi0.83Mn0.06Co0.11O2 (NMC83). Figure 17 shows the XRD patterns of NMC83 and WO3 treated NMC83 having a pure single phase layered O3 phase without Li impurities. The peak separation between (108)/(110) at 65° increases after WO3 treatment indicating an increase in crystallinity. Thus, the WO₃ treated samples have increased single crystal order compared to pristine samples. [0155] Figure 18A shows galvanostatic cycling of half cells made with pristine NMC83 and WO₃ treated NMC83. There is a decrease in discharge capacity after treatment with WO3, which has a melting point of 1473 °C. However, the capacity retention in Figure 18B for pristine NMC83 and WO3 treated NMC83 demonstrates that the WO3 treatment did not change capacity retention. Additional Embodiments [0156] In the foregoing specification, the disclosure references specific embodiments. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the disclosure. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. [0157] Indeed, although this invention has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while several variations of the embodiments of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosed invention. Any methods disclosed herein need not be performed in the order recited. Thus, it is intended that the scope of the invention herein disclosed should not be limited by the particular embodiments described above. [0158] It will be appreciated that the systems and methods of the disclosure each have several innovative aspects, no single one of which is solely responsible or required for the desirable attributes disclosed herein. The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and sub combinations are intended to fall within the scope of this disclosure. [0159] It will also be appreciated that conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open- ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. In addition, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. In addition, the articles “a,” “an,” and “the” as used in this application and the appended claims are to be construed to mean “one or more” or “at least one” unless specified otherwise. Similarly, while operations may be depicted in the drawings in a particular order, it is to be recognized that such operations need not be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flowchart. However, other operations that are not depicted may be incorporated in the example methods and processes that are schematically illustrated. For example, one or more additional operations may be performed before, after, simultaneously, or between any of the illustrated operations. Additionally, the operations may be rearranged or reordered in other embodiments. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems may generally be integrated together in a single software product or packaged into multiple software products. Additionally, other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve desirable results. [0160] Accordingly, the claims are not intended to be limited to the embodiments shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein. [0161] Terms and phrases used in this application, and variations thereof, especially in the appended claims, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing, the term ‘including’ should be read to mean ‘including, without limitation,’ ‘including but not limited to,’ or the like; the term ‘comprising’ as used herein is synonymous with ‘including,’ ‘containing,’ or ‘characterized by,’ and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps; the term ‘having’ should be interpreted as ‘having at least;’ the term ‘includes’ should be interpreted as ‘includes but is not limited to;’ the term ‘example’ is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; and use of terms like ‘preferably,’ ‘preferred,’ ‘desired,’ or ‘desirable,’ and words of similar meaning should not be understood as implying that certain features are critical, essential, or even important to the structure or function of the disclosure, but instead as merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the disclosure. In addition, the term “comprising” is to be interpreted synonymously with the phrases “having at least” or “including at least”. When used in the context of a process, the term “comprising” means that the process includes at least the recited steps but may include additional steps. When used in the context of a compound, composition or device, the term “comprising” means that the compound, composition or device includes at least the recited features or components, but may also include additional features or components. Likewise, a group of items linked with the conjunction ‘and’ should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as ‘and/or’ unless expressly stated otherwise. Similarly, a group of items linked with the conjunction ‘or’ should not be read as requiring mutual exclusivity among that group, but rather should be read as ‘and/or’ unless expressly stated otherwise. [0162] Additionally, the phrase “consisting essentially of” will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase “consisting of” excludes any element not specified. The transitional phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. [0163] Ranges can be expressed herein as from “about” or “approximately” one particular value, and/or to “about” or “approximately” another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. For example, “about” or “approximately” can mean within 1 or more than 1 standard deviations, per the practice in the art. Alternatively, “about” or “approximately” can mean a range of up to 20%, up to 10%, up to 5%, and up to 1% of a given value.

Claims

WHAT IS CLAIMED IS: 1. A solvent-free method for post-synthesis modification of a single-crystal battery cathode material for lithium-ion batteries, comprising: providing a single crystal cathode material having a single crystal structure; dry mixing the cathode material with one or more low-melting-point treatment materials in the forms of metal compounds containing one or more metals selected from the group consisting of Magnesium (Mg), Aluminum (Al), Titanium (Ti), Manganese (Mn), Cobalt (Co), Zinc (Zn), Zirconium (Zr), Niobium (Nb), and Molybdenum (Mo); and mixtures thereof; and sintering the single-crystal cathode material mixed with the one or more low- melting-point treatment materials at elevated temperatures to produce a treated single- crystal cathode material.

2. The method of claim 1, wherein the single crystal cathode material has a layered structure with single crystalline morphologies, a D50 particle size in a range of 1^m to 20 ^m, and have a general chemical formula of Li_1+x[(Ni_nMn_mCo_c)_1-aA_a]_1-xO₂ where: A is selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and combinations thereof; -0.05 ^ x ^ 0.10;

0 ^ a ^ 0.05. 3. The method of claim 1, wherein the single crystal cathode material has a spinel structure with single crystalline morphologies, a D50 particle size in a range of 1^m - 30 ^m, and have a general formula of Li_xMn_2-y-zNi_yM_zO₄ where: M is selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Co, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and combinations thereof; 0.25 ^ x ^ 1.1; 0.

3 ^ y ^ 0.5; and 0 ^ z ^ 0.15.

4. The method of claim 1, wherein the single crystal cathode material has a layered structure with single crystalline morphologies, a D50 particle size in a range of 1^m to 20 ^m, and have a general chemical formula of Li1+x[(NinCocAlm)1-aAa]1-xO2 where: A is selected from the group consisting of Mg, Si, Ca, Ti, V, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and combinations thereof; -0.05 ^ x ^ 0.10; n + m + c = 1; and 0 ^ a ^ 0.05.

5. The method of any of claims 1-4, wherein the melting points of the one or more treatment materials are below 500 °C.

6. The method of any of claims 1-5, wherein the one or more treatment materials comprise the forms of metal hydroxides, metal formates, metal acetates, metal oxalates, metal carboxylates, metal phosphates, metal nitrates, metal hydrides, metal benzoates, or combinations thereof.

7. The method of any of claims 1 or 5-7, wherein an average particle size of the one or more treatment materials is greater than 10 nm and less than 10 ^m.

8. The method of any of claims 1-7, wherein the sintering temperatures are above 700 °C and below 950 °C.

9. The method of claim 8, wherein a dwell time for the sintering is greater than 1 min and less than 24 h.

10. The method of claim 8, wherein the sintering is conducted with one or multiple intermediate hold temperatures and the heating and cooling rates range from 0.5 °C/min to 10 °C/min.

11. The method of any of claims 1-10, wherein an amount of the one or more treatment materials ranges from about 0.01 wt% to about 1 wt% of the single crystal cathode material.

12. The method of any of claims 1-10, wherein an amount of the one or more treatment materials ranges from about 0.01 mole% to about 1 mole% of the single crystal cathode material.

13. The method of any of claims 1-12, wherein the dry mixing is performed with a blade grinder, planetary mixer, high-speed conical mixer, mechanofusion, trituration, or acoustic mixer.

14. The method of claim 13, wherein the dry mixing is a heated dry mixing at approximately the melting point of the one or more treatment materials.

15. The method of any of claims 1-14, wherein sintering is performed in oxygen, air, or inert gas.

16. The method of any of claims 1-15, wherein lithium residuals on the cathode surface in the forms of LiOH and Li2CO3 are reduced by 20% to 75% after the sintering.

17. The method of claim 16, further comprising detecting the reduction in lithium residuals before and after the post-synthesis modification through an acid-base titration.

18. The method of any of claims 1-17, wherein the surface area of the modified cathode is reduced by 10% to 50% after the sintering.

19. The method of claim 18, wherein single crystal cathode material was previously sintered at a temperature exceeding 500°C prior to the dry mixing.

20. The method of claim 18, additionally comprising applying the treated single-crystal cathode material to a current collector for use as an electrode in a battery.

21. A battery comprising the treated single-crystal cathode material of Claim 1.

22. A battery cathode material comprising: a single crystal having a layered O3 structure; a D50 particle size in a range of 1 ^m to 20 ^m; a treated particle surface treated with residues from one or more metal compounds having a melting point below about 900 degrees Celsius, wherein the metals in the metal compounds are selected from the group consisting of Magnesium (Mg), Aluminum (Al), Titanium (Ti), Manganese (Mn), Cobalt (Co), Zinc (Zn), Zirconium (Zr), Niobium (Nb), and Molybdenum (Mo); and mixtures thereof; a core structure represented by the general formula L_xT_yM_zO₂ where: x ^ 0.2; y ^ 0.5; 0.2 ^ z ^ 0; L consists of one or more insertable alkali metals; T consists of two or more first row transition metal elements; and M consists of one or more metal elements other than an alkali metal or a first- row transition metal element; wherein the battery material is free of solvents or solvent residues.

23. The battery cathode material of Claim 22, wherein the battery cathode material is free of solvents and solvent residues.

24. The battery cathode material of Claim 22, wherein the core structure is represented by the chemical formula Li1+x[(NinMnmCoc)1-aAa]1-xO2 where: A is selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Zn, Sr, Zr, Nb, Mo, Sn, Sb, Ba, and a combination thereof; -0.05 ^ x ^ 0.10; n + m + c = 1; 0 ^ a ^ 0.05; n > 0; m > 0; and c > 0.