Dry post-treatment processes for lithium transition metal oxide cathode materials

Abstract

Embodiments of the disclosure relate to post-treatment processes for single-crystalline lithium transition metal oxide cathode materials. The post-treatment processes may be dry post-treatment processes and include a dry mixing or coating step and one or more refirings. The dry coating may include mixing the single-crystalline cathode materials with one or more metal compounds in an environment free of solvents. A first refiring prior to the dry mixing may be at temperatures exceeding 700 degrees Celsius and a second refiring after the dry mixing may be at temperatures below 700 degrees Celsius. The coated and reheated cathode materials disclosed herein have superior cycle life compared to the pristine materials.

Description

Dry Post-treatment Processes for Lithium Transition Metal Oxide Cathode MaterialsINCORPORATION BY REFERENCE TO RELATED APPLICATION

[0001] This PCT application claims priority to U.S. Provisional Application 63 / 544937, filed October 19, 2023, and U.S. Provisional Application 63 / 694666, filed September 13, 2024, the entirety' of which are incorporated herein for any and all purposes.BACKGROUNDField of Disclosure

[0002] This disclosure relates to battery' materials, including battery cathodes and battery active materials.Description of the 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 continue in order to improve other important characteristics such as cycle life, efficiency, and cost. Further, significant research and development continue 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 ty pes 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] Single-crystalline cathode materials are usually made by high-temperature calcination followed by deagglomeration. Un-treated (pristine) single-cry stalline cathode materials usually have many lithium residuals and cracks on the surface from the high energy impact of deagglomeration. Further, high lithium residuals result in electrode slurry gelation and cause significant gas formation upon cell formation. Cracking and rough cathode surface usually correlate with high cathode surface area, which accelerates parasitic reactions between cathode materials and electrolytes resulting in poor cycle life.

[0006] Traditional post-treatment processes involve washing cathode materials with water or organic solvents followed by refiring at elevated temperatures. In some cases, after washing, the washed cathode materials are coated with chemicals dissolved in aqueous / non-aqueous solvents prior to refiring. Overall, w ashing 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

[0007] This disclosure herein relates to dry coating processes for single-crystalline lithium transition metal oxide cathode materials. In some embodiments pristine single crystal cathode materials may be coated either before a refiring or between tw o refiring steps. Refiring with coating improves the electrochemical characteristics of the cathode material but an additional (second) refiring can improve the electrochemical performance of the cathode material more than a single refiring alone.

[0008] The cathode materials may be subjected to a coating process either before, after, or betw een one or more refirings. The coating process may be a dry coating process that is free of solvents. The dry' coating process may apply a layer of a metal onto the surface of the cathode material. Subsequent refiring of the cathode materials and one or more coating materials may solidify a layer of the one or more coating materials on the surface of the cathode material. As an example, a single cry stal cathode material may be coated with one or more metals other than nickel, manganese, or cobalt. In some embodiments the one or more coating materials may be comprised of transition metals or post-transition metals. In some embodiments the metals for the coating material may be 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. In embodiments herein the coating and refiring processes can be particularly beneficial for single crystal cathode materials. In some embodiments the one or more coating materials or treatment materials include metals selected from the group consisting of Al, Zr. Ti. Mg, and Nb.

[0009] One process for dry coating single-crystalline lithium transition metal oxide cathode materials may include three or more steps. In step 1, pristine cathode materials are refired at elevated temperatures (TI). The refiring can heal cracks, smoothen surfaces, reduce surface area, reduce lithium residuals, or increase crystallinity. In step 2, the refired cathode materials may be coated with one or more coating materials. In step 3, coated cathode materialsmay be reheated at mild temperatures (T2) to affix the one or more coating materials to a surface of the cathode materials. The final cathode materials prepared using techniques in this disclosure have superior cycle life compared to the pristine materials.

[0010] In some embodiments Tl is a temperature exceeding 700 degrees Celsius. In some embodiments, T2 is a temperature below 700 degrees Celsius. In some embodiments T1 exceeds 800 degrees Celsius and T2 is below 800 degrees Celsius.

[0011] In some aspects, the techniques described herein relate to a method, wherein Tl is greater than 700 °C and lower than 1000 °C.

[0012] In some aspects, the techniques described herein relate to a method, wherein T2 is greater than 300 °C and lower than 700 °C.

[0013] In some aspects, the techniques described herein relate to a dry coating method for preparing single-crystal Li-ion battery cathode materials, the method including: a) refiring pristine single-crystal cathode materials at a temperature (Tl) exceeding 700° Celsius to heal cracks, smoothen surfaces, reduce surface area, reduce lithium residuals, or increase crystallinity; b) coating the refired single-crystal cathode materials from (a) with one or more coating materials, wherein the coating is a dry coating free of solvents; and c) reheating the coated single-crystal cathode materials from (b) at temperatures below 700° Celsius (T2) to affix the one or more coating materials to the surfaces of the single-cry stal cathode material.

[0014] In some aspects, the techniques described herein relate to a method, wherein single-crystal cathode materials have a layered structure with single crystal morphologies, a D50 average particle size in the range of 500 nm - 10 pm, the general chemical formula of Linx[(NinMnmCoc)i-aAa]i-xO2 where: n + m + c = l; A is one or more dopants; -0.05<x<0.1; and 0 < a < 0.05. In some aspects the single-crystal cathode materials have a D50 particle size in a range of 1 pm to 20 pm.

[0015] In some aspects, the techniques described herein relate to a method, wherein A is one or a combination of elements selected from the following list of elements: Al, Mg, Zr, Nb, Si, P, Mo, Ba, Sr, Ca, Zn, Cr, V, and Ti.

[0016] In some aspects, the techniques described herein relate to a method, wherein Tl is lower than 1000 °C.

[0017] In some aspects, the techniques described herein relate to a method, wherein the refiring is conducted under an atmosphere selected from the group consisting of air, oxygen, and reduced oxygen.

[0018] In some aspects, the techniques described herein relate to a method, wherein T2 is greater than 300 °C and lower than 700 °C.

[0019] In some aspects, the techniques described herein relate to a method, wherein the reheating is conducted under an atmosphere selected from the group consisting of air, oxygen, and reduced oxygen.

[0020] In some aspects, the techniques described herein relate to a method, where lithium compounds are added to the pristine cathode materials prior to refiring.

[0021] In some aspects, the techniques described herein relate to a method, where lithium compounds are in the forms of. but not limited to, lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxide, and combination thereof

[0022] In some aspects, the techniques described herein relate to a method, where the amount of lithium compounds added are ranging from 0 mol% to 10 mol% of pristine cathode materials.

[0023] In some aspects, the techniques described herein relate to a method, wherein the one or more coating materials are nano powders with an average primary particle size smaller than 100 nm and surface area higher than 50 m2 / g.

[0024] In some aspects, the techniques described herein relate to a method, wherein the one or more coating materials are compounds of Al, Zr, Ti, Mg, Nb in the forms of oxides, hydroxides, or combination thereof.

[0025] In some aspects, the techniques described herein relate to a dry7coating method for preparing single-crystal Li-ion battery cathode materials, the method including: firing a mixture of single-crystal cathode precursor materials at a temperature (TO) exceeding 700 Celsius to produce lithiated single-crystal cathode materials; cooling the single-crystal cathode materials to a temperature below 100 degrees Celsius; refiring the single-crystal cathode materials at a temperature (Tl) exceeding 700 degrees Celsius to produce refired single-crystal cathode materials; coating the refired single-crystal cathode materials with one or more coating materials in an all-dry process free of solvents; and reheating the coated singlecrystal cathode materials at mild temperatures (T2) to affix the one or more coating materials to the surfaces of the single-crystal cathode material.

[0026] In some aspects, the techniques described herein relate to a method, additional including milling the single-crystal cathode materials after the firing at (TO) and before the refiring (Tl).

[0027] In some aspects, the techniques described herein relate to a method, additional including milling the single-crystal cathode materials after the refiring at (Tl) and before the coating step.

[0028] In some aspects, the techniques described herein relate to a method, wherein the mild temperatures (T2) is greater than 300 °C and lower than 700 °C.

[0029] In some aspects, the techniques described herein relate to a method, wherein the single-crystal cathode precursor materials include NiO, CO3O4, MnsCh, and LieCOs.

[0030] In some aspects, the techniques described herein relate to a method, wherein the NiO, CO3O4, M CL. and LieCOs are mixed in a stoichiometric ratio of LiNio.6Mno.2Coo.2O2 with Li2CO3 in excess of at least 5%.

[0031] In some aspects, the techniques described herein relate to a single-crystal Li-ion batten' cathode material product synthesized 1.

[0032] In some aspects, the techniques described herein relate to a single-crystal Li-ion battery cathode material product, wherein: the single-crystal Li-ion battery’ cathode materials have a layered structure with single crystal morphologies, a D50 average particle size in the range of 500 nm - 10 pm, the general chemical formula of Lii+x[(NinMnmCoc)i-aAa]i-xO2 where: n + m + c = l; A is one or more dopants; -0.05<x<0.1; and 0 < a < 0.05.

[0033] In some aspects, the techniques described herein relate to a single-crystal Li-ion battery cathode material product, wherein the single-crystal Li-ion battery- cathode material product coating is selected from a group consisting of Al, Zr, Ti, Mg, and Nb.

[0034] In some aspects, the techniques described herein relate to a dry or solvent- free method for post-synthesis modification of a single-crystal battery cathode material for lithium-ion batteries, including: providing a pristine single crystal cathode material having a single crystal structure; dry mixing the cathode material with one or more treatment materials having a melting point beloyv about 920°C 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. In some aspects the treated single-crystal cathode material is comprised of particles. In some aspects the treated single-crystal cathode material is free of solvent residues.

[0035] 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.

[0036] In some aspects the techniques described herein relate to a method, yvherein 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.

[0037] 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 pm.

[0038] In some aspects, the techniques described herein relate to a method, wherein the sintering temperatures are above 700 °C and below 1100 °C.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] In some aspects, the techniques described herein relate to a method, wherein sintering is performed in oxygen, air, or inert gas.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] In some aspects, the techniques described herein relate to a method, additionally including applying the treated single-cry stal cathode material to a current collector for use as an electrode in a battery.

[0051] In some aspects, the techniques described herein relate to a battery including the treated single-crystal cathode material.

[0052] In some aspects, the techniques described herein relate to a battery cathode material including: a single crystal having a layered 03 structure; a D50 particle size in a range of 1 pm to 20 pm; 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 LxTyMzCh 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 solvent residues.

[0053] 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.

[0054] In some aspects, the techniques described herein relate to a post-processing method for single-cry stal Li-ion battery cathode materials, the method comprising: providing singe-crystalline cathode materials; dry’ mixing the singe-crystalline cathode materials with one or more coating materials in the absence of solvents; and subjecting the single-crystalline cathode materials to one or more refirings at temperatures exceeding 300 degrees Celsius before or after the dry’ mixing.

[0055] In some aspects, the techniques described herein relate to a post-processing wherein a first refiring is performed before the dry mixing and a second refiring is performed after the dry mixing.BRIEF DESCRIPTION OF DRAWINGS:

[0056] Figure 1 illustrates a process diagram of the procedure for post-treatment of single-crystalline cathode materials.

[0057] Figure 2 illustrates a schematic illustration of the morphology of disclosure single-crystalline cathode materials.

[0058] Figure 3 shows SEM image demonstrating the morphology of fumed alumina.

[0059] Figure 4 shows SEM images of (a) fumed alumina-coated on pristine polycrystalline, (b) fumed alumina-coated on pristine single-crystalline, (c) fumed alumina- coated on refired polycrystalline, (d) fumed alumina-coated on refired single-crystalline NMC622.

[0060] Figure 5 shows Galvanostatic cycling performance of lwt% fumed alumina coated on pristine / refired poly crystalline and pristine / refired single-crystalline NMC622 samples where (a) shows discharge capacity and (b) shows normalized discharge capacity retention

[0061] Figure 6 shows SEM images of (a) cathode powder refired at 900 °C (refired900C); (b) cathode powder refired at 900 °C and coated with fumed alumina (refired900C_coated); (c) cathode powder refired at 900 °C, coated with fumed alumina, then refired at 500 °C (refired900C_coated_refired500C): (d) cathode powder refired at 900 °C. coated with fumed alumina, then refired at 600 °C (refired900C_coated_refired600C); (e) cathode powder refired at 900 °C, coated with fumed alumina, then refired at 650 °C (refired900C_coated_refired650C); and (f) cathode powder refired at 900 °C. coated with fumed alumina, then refired at 700 °C (refired900C coated refired700C).

[0062] Figure 7 shows SEM images of cathode powder (a) pristine; (b) refired at 900 °C (refired900C); (c) coated with fumed alumina (coated); (d) coated with alumina and refired at 900 °C (coated_refired900C); (e) refired at 900 °C and coated with fumed alumina (refired900C_coated); (f) refired at 900 °C, coated with fumed alumina, and refired at 600 °C (refired900C_coated_refired600C).

[0063] Figure 8 shows XRD of cathode powder (a) pristine; (b) refired at 900 °C (refired900C); (c) coated with fumed alumina (coated); (d) coated with alumina and refired at 900 °C (coated_refired900C); (e) refired at 900 °C and coated with fumed alumina (refired900C_coated); (f) refired at 900 °C, coated with fumed alumina, and refired at 600 °C (refired900C_coated_refired600C).

[0064] Figure 9 shows Galvanostatic cycling performance of example 3 samples where (a) illustrates discharge capacities; and (b) illustrates normalized discharge capacity retention of NMC622 samples.

[0065] Figure 10 illustrates SEM images of (a) PC Pristine, (b) PC 500, and (c) PC_800 NMC622 samples.

[0066] Figure 11 shows XRD patterns of (a) PC Pristine, (b) PC 500, and (c) PC_800 NMC622 samples.

[0067] Figure 12 shows SEM images of (a) SC_Pristine, (b) SC_500, (c) SC_800 NMC622 samples.

[0068] Figure 13 shows XRD patterns of (a) SC Pristine. (b) SC_500, (c) SC_800 NMC622 samples.

[0069] Figure 14 shows lithium residuals amount on (a) PC NMC622 samples; (b) SC NMC622 samples.

[0070] Figure 15 shows BET surface area of cathode materials refired at different refire T1 temperatures.

[0071] Figure 16 shows galvanostatic cycling performance of (a) PC NMC622 samples and (b) SC NMC622 samples.

[0072] Figure 17 demonstrates SEM images of powders from example 5 where (a) is an image of 1FA-500 and (b) is an image of 1FA-900.

[0073] Figure 18 illustrates line scan images of powders from example 5 where (a) is a TEM image of 1FA-900 and (b) is a TEM image of 1FA-500 where the arrow indicates the direction of the line scan. Figure 18(c) depicts the detected elements across the direction of the arrow in 18(a) and Figure 18(d) depicts the detected elements across the direction of the arrow in 18(b).

[0074] Figure 19 shows electrochemical performance of samples from example 5.

[0075] Figure 20 shows SEM images of (A) Pristine_NMC702901, (B)Refired_NMC702901, (C) 0.25NMC702901, (D) 0.5NMC702901.

[0076] Figure 21 shows XRD patterns of (A) Pristine_NMC702901, (B)Refired_NMC702901, (C) 0.25NMC702901, (D) 0.5NMC702901.

[0077] Figure 22 shows galvanostatic cycling performance ofRefired_NMC702901, 0.25NMC702901, 0.5NMC702901 where (A) shows discharge capacity, and (B) shows normalized discharge capacity retention.

[0078] Figure 23 shows SEM images of (a), (d) pristine_NMC640, (b), (e) Refired_NMC640, (c), (f) 0.40NMC640.

[0079] Figure 24 shows XRD patterns of materials prepared in example 7.

[0080] Figure 25 shows XRD patterns of materials prepared in example 7 of the (018) / (l 10) peak region (63.5-66° 20).

[0081] Figure 26 shows galvanostatic cycling performance of materials prepared in example 7 where (a) shows discharge capacity’, and (b) shows normalized discharge capacity.

[0082] Figure 27 shows SEM images of (a) pristine NMC631, (b) refired NMC631, (c) finished NMC631.

[0083] Figure 28 shows XRD patterns of pristine NMC631, refired NMC631, and finished NMC631: a) full view (10-90° 20) and (b) expanded views of impurity region (20- 30° 20) and (018) / (l 10) peak region (64-66° 20).

[0084] Figure 29 shows half coin cell galvanostatic cycling performance of pristine NMC631, refired NMC631, and finished NMC631 : (a) discharge capacity’ and (b) normalized discharge capacity.

[0085] Figure 30 illustrates a process diagram of the procedure for post-treatment of single-crystalline cathode materials according to some embodiments herein.DETAILED DESCRIPTION

[0086] The disclosure relates to dry processes for single crystalline cathode materials. In some embodiments pristine single crystal cathode materials are coated either before a refiring or between two refirings. Thus, the post-processing of the single-cry stalline cathode materials may comprise a coating and one or more refilings. Refiring after coating improves the electrochemical characteristics of the cathode material but a first refiring (additional refiring) and subsequent refiring after coating can improve the electrochemical performance of the cathode material more than a single refiring alone. In some embodiments the additional refiring reduces lithium residuals, increases cry stallinity, and smoothens the surface of the single crystalline cathode material and the refiring after coating reduces lithium residuals and at least partially applies the coating.

[0087] Coating the surface is a highly beneficial step to make long-lived cathode materials for Li-ion batteries. Single-cry stalline cathode materials can be made by high- temperature calcination followed by jet milling. Un-treated (pristine) single-crystalline cathode materials usually have many lithium residuals and cracks on the surface from the high energy impact of jet milling. High lithium residuals result in electrode slurry gelation and cause significant gas formation upon cell formation. Cracking and rough cathode surface usually correlate with high cathode surface area, which accelerates parasitic reactions between cathode materials and electrolytes resulting in poor cycle life.

[0088] The disclosure herein proposes the use of a refiring step before depositing a coating on single-crystalline cathode materials and a second refiring step after depositing acoating on single-cry stalline cathode materials to achieve high-performance single-crystalline lithium transition metal oxide cathode materials, as demonstrated in Figure 1. Thus, the singlecrystal cathode materials may be fired in three different heating steps. The first firing may be to synthesize the pristine cathode materials, after which the cathode materials may be cooled to room temperatures. The first refiring may occur at elevated temperatures after synthesis of the pristine material to improve the surface imperfections of single-crystalline cathode materials as demonstrated in Figure 2. The second refiring may occur at mild temperatures, such as temperatures below 700 Celsius, after coating to form chemical bonds between coating materials and single-crystalline cathode materials as demonstrated in Figure 2.

[0089] One of skill in the art may assume that coating should be performed on cathode materials that have roughened surfaces. For example, a roughened surface may be perceived as desirable to decrease the surface area (to smooth out the roughened surface with a single coating) or to increase the amount of coating that may be loaded onto the cathode material. However, this disclosure uniquely provides a coating on a smoothened surface with a lower surface area, which is counterintuitive. For example, a coating step could be performed after milling the single-crystalline cathode material, where the cathode surface is not as smooth. However, the inventors of the disclosure have discovered that refiring the pristine single-crystal cathode materials has the ability to heal cracks and fix surface defects resulting in a smooth surface with fewer small fractures and that coating the material after this refiring step produces superior electrochemical properties. Conversely, without the refiring step, pristine singlecrystal cathode samples had poor capacity retention. Thus, the first refiring counterintuitively improves the coating of the cathode materials and does not negatively affect the coating adherence or electrochemical properties.

[0090] Advantageously, this disclosure relates to an all-dry process for the production of cathode materials. The all-dry process is desirable as it eliminates excess wastewater or pollutants that are produced during ty pical coating or washing process. Further, an all-dry' coating process may streamline the process such that the evaporation of liquids on the surface of the cathode materials is not necessary and eliminating the use of water potentially reduces reactions, oxidizations, or contaminants that may be introduced via the washing steps.

[0091] The all-dry process may be considered an “all-dry” process as it does not incorporate the use of solvents. In some embodiments the all-dry' process is substantially free of solvent residues. In some embodiments the all-dry' process eliminates the use of water in the process. In some embodiments the all-dry process may be performed in a reduced humidity environment. For example, the coating may be performed in an atmosphere with reducedhumidity or with inert gasses, such as nitrogen or noble gasses. In some embodiments an “all dry” process may be referred to as a solid-state process where the process is free of any solvents or solvent residues.

[0092] Advantageously, the dry coating and refiring methods disclosed herein may be applied to pristine single crystal cathode materials synthesized according to a dry process, thus eliminating the production of byproducts (particularly aqueous byproducts) and the use of excess water in the synthesis and post-treatment of the pristine single crystal cathode materials. Therefore, the entire process, including synthesis and post-treatment of single crystal cathode materials, can be performed according to dry processes. In some embodiments the single crystal cathode material is NMC, LMN, or NCA synthesized according to dry processes and further coated and refired according to the dry’ processes disclosed herein.

[0093] Any of the embodiments disclosed herein may be performed as an all-dry process. In any embodiment disclosed herein the al I -dry or dry process may be a solid-state process, a method performed in a water-free environment, a solvent-free process, a process performed in the absence of liquid water and / or gaseous water, a process performed in the absence of liquid solvents, a solvent-free method, etc. Advantageously, the cathode materials produced according to the all-dry process are free of solvent residues. For example, the singlecrystal battery’ cathode materials produced according to embodiments herein may be free of solvent residues. In some embodiments the all-dry methods are free of liquid water, aqueous solvents, or liquids. For example, the entire processing, including mixing, coating, or refiring, may be performed in the absence of liquid solvents or water.

[0094] Solvent residues include trace minerals or solutes that exist in solvents. These residues include but are not limited to solid salts, acids, bases, trace metals, and trace impurities. For example, acid residues may come from inorganic acids such as HC1, HNO3, H2SO4, H3PO4, and organic acids such as citric, dl-malic, ascorbic, succinic, oxalic, 1-tartaric, lactic acid, and formic acids. Other solvent residues may' be trace metals, such as sodium, magnesium, calcium, iron, etc. Trace impurities may comprise residues incompletely removed from solvent reagents. These trace impurities may be acceptable according to industry standards for the purity of certain reagents. These trace impurities may be in the amount of parts per million (ppm) or parts per billion (ppb). In some embodiments, free of solvent residues includes less than 1 ppm solvent residues.

[0095] In some embodiments the pristine cathode materials for post-treatment were produced according to dry processes such that they are free of solvent residues. For example, the pristine cathode materials were not produced via a co-precipitation process or othersolvothermal processes. Therefore, some embodiments herein exclude the use of pristine cathode materials produced with to a conventional co-precipitation process.

[0096] Figure 1 illustrates a general process diagram of the procedure for post treatment of single-crystalline cathode materials. NMC precursor materials may be provided in 100. NMC refers to Lithium-Nickel-Manganese-Cobalt-Oxide, but the methods herein may be applied to other battery cathode materials, such as single-crystal cathode materials of varying compositions. In 110, the NMC precursor materials are sintered to obtain pristine NMC materials 120. In 130 the pristine NMC materials are subjected to a first refiring, resulting in a refired NMC 140. The refired NMC 140 is then subjected to a dry coating 150, producing a coated NMC 160. The coated NMC is then subjected to a second refiring 170. producing a finished NMC 180 that can be incorporated into a battery cell.

[0097] Between the pristine NMC 120 and the 1strefiring 130 a deagglomeration process may be performed in order to deagglomerate and / or size control the pristine NMC materials 120. The deagglomeration process may comprise jet milling, blade grinding, pin milling, centrifugal impact milling, ball milling, vibrator)’ milling, planetary milling, or other milling processes.

[0098] In some embodiments the dry coating 150 is performed via blade grinding, so as to incorporate a dry coating material onto the surface of the refired NMC materials 140. The dry coating material may be an inorganic dry coating material and may comprise Al, Zr, Ti, Mg, Nb in the forms of oxides, hydroxides, or combination thereof. The inorganic dry coating material may be selected from a group consisting of Al, Zr, Ti, Mg, and Nb. In some embodiments the inorganic materials may be provided in the forms of oxides, hydroxides, or both. In some embodiments the coating material is alumina oxide power. In some embodiments the system for deagglomerating the pristine NMC material is the same system for coating the refired NMC 140. In at least one embodiment a blade grinder is used for deagglomeration and coating of NMC materials.

[0099] In some embodiments the treatment or coating materials that are dry mixed with the single crystalline cathode materials have an average particle size of the one or more treatment materials is greater than 10 nm and less than 10 pm. In some embodiments the average particle size of the coating materials is greater than about 0. 1 pm, about 0.5 pm, about 1 pm, about 5 pm or any range of values in betw een. In some embodiments the coating or treatment materials are greater than about 0.1 pm and have a melting point below- 900 degrees Celsius. Further, in the dry coating processes disclosed herein the treatment or coating material is not a solvent or in liquid form at about 21 Celsius and 1 atm.

[0100] In some embodiments the single-cry stalline cathode material used in the post-treatment processes herein is a cathode material having the general chemical formula of Li i+x[(NinMnmCoc)i-aAa]i-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 Lii+x[(NinMnmCoc)i-aAa] i-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 Lii+x[(NinMnmCoc)i-aAa]i-xO2, where -0.03 < x < 0.06; n + m + c = l; n > 0.05; m > 0.05; c > 0; A is a metal dopant; and 0 < a < 0.05. The batery 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 pm. If the grain size is too large, then increased impedance during Li-ion cell operation can result. Therefore, SC-LiNMC, gram sizes (D50) may be present between 1 pm and 20 pm. SC-LiNMC particles can consist of more than one LiNMC grain. However, superior capacity’ retention can be obtained if SC-LiNMC particles each consist of a single LiNMC grain.

[0101] The D50 particle size of the single crystalline cathode materials or treated / coated cathode materials may be in the range of about 500 nm to about 20 pm, about 800 nm to about 20 pm, about 900 nm to about 20 pm, about 1 pm to about 20 pm, about 1 pm to about 15 pm, about 1 pm to about 10 pm, about 5 pm to about 15 pm, or any value or range of values in between (i.e. about 10 pm to about 20 pm). As discussed herein, particles produced according to the methods herein are generally spherical and not nanosheets. As discussed above, the grain sizes (D50) of the single cry stalline materials may be between about 1 pm and 20 pm. In embodiments herein single cry stalline cathode materials or coated single crystalline cathode materials are particles having D50 particle sizes discussed herein.

[0102] In some embodiments the provided or pristine cathode materials have the general formula of LixMn2-y-zNiyMzO4 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 batery cathode materials (LMO). The particle size of the LMO batery materials mayhave a D50 particle size in the range of about 1 pm to about 30 pm, about 10 pm to about 30 pm, about 1 pm to about 20 pm, about 1 pm to about 10 pm, about 5 pm to about 15 pm, about 0.5 pm to about 30 pm or any value or range of values in between.

[0103] In some embodiments the pristine or provided cathode materials have the general chemical formula of Lii+x[(NinCocAlm)i-aAa]i-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 = I; 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 Lii+x[(NinCocAlm)i-aAa]i-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 pm, about 500 nm to about 10 pm, about 10 pm to about 20 pm, about 1 pm to about 10 pm, or any value or range of values in between (i.e. about 10 um).

[0104] In some embodiments the coating or 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 CeFfcAlOe), Zinc may be provided as Zinc hydroxide (Zn(OH)2), or Cobalt may be provided as Co(OH)2.

[0105] In some embodiments a 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 organic portion of the treatment or coating material decomposes in a refiring, but the metal (such as Al, Zr, Ti, Mg, and Nb) remains and coats the surface of the single crystalline 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 can be 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 cathodematerials prior to firing and then partially decompose and / or react with the lithium residuals on the surface of the single crystal cathode material during refiring.

[0106] In some embodiments the treatment or coating materials in the form of metal compounds may be selected such that they are below the boiling temperature of LiOH (924°C). Therefore, in some embodiments 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 complete or 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 may range 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.

[0107] In embodiments herein the pristine single crystal cathode materials have been previously fired at temperatures exceeding 500 °C (for example in the range of 700°C to 1100°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 cry stal cathode material. In some embodiments the single crystal cathode material is NMC111, NMC532, NMC622, or NMC811. In some embodiments after the firing of feedstock materials (or NMC precursor materials) the pristine single crystal cathode materials are cooled down to a temperature below about 100°C. In some embodiments the pristine cathode materials are cooled to a temperature below about 70°C or below about 50°C or any range or value in between. The cooling process generally separates the sintering from the first refiring.

[0108] Figure 30 depicts another method of post-treating cathode materials. In step 3000 NMC precursor materials or feedstock materials are provided. Although step 3000 lists NMC feedstock materials, these feedstock materials can contain lithium and one or more transition metals, such as nickel, manganese, cobalt, or aluminum. Feedstock or NMC precursor materials may be dry and free of solvent residue. Thereafter at step 3010 the NMC precursor materials are sintered. The sintering in 3010 may be at temperatures in a range of 900°C to 1200°C. The pristine cathode materials in step 3020 may be single crystalline NMC cathode materials, such as those disclosed herein.

[0109] In step 3030 the pristine single crystal cathode materials are dry coated with one or more treatment materials. In some embodiments the treatment materials (in 3030) have a melting point below about 500°C. The dry coating may be substantially free of solvents or substantially free of water and aqueous residues. After coating the coated NMC (3040) is subjected to a first refiring (3050). The first refiring may be at a temperature range of at least 500°C or in a range of about 700 °C to about 950 °C. After the first refiring (3050) a finished NMC (3060) is produced with superior cycling and capacity’ characteristics.

[0110] Therefore, this disclosure presents the all-dry post-treatment process that results in single-crystalline cathode materials having low surface area, low lithium residuals, high crystallinity, and excellent electrochemical performances.[OHl] In some aspects the disclosure relates to a battery containing the single crystal cathode material produced according to embodiments disclosed herein. The battery- may be a secondary (reusable) battery. 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

[0112] Although the folloyving terms are believed to be well understood by one of skill in the art, the following definitions are set forth to facilitate understanding of the presently disclosed subject matter.

[0113] All technical and scientific terms used herein, unless otherwise defined beloyv, are intended to have a meaning that yvould be understood by one of ordinary skill in the art. References to techniques employed herein are intended to refer to the techniques as commonly understood in the art, including variations on those techniques or substitutions of equivalent techniques that would be apparent to one of skill in the art.

[0114] “Pristine single-cry stal cathode materials” as described herein generally refers to single-crystal cathode materials that have been synthesized from cathode precursors previously fired at elevated temperatures. The single-crystal cathode material is composed of cathode in a stoichiometric ratio, one example being LiNio.6Mno.2Coo.2O2 for single-crystalline NMC622.

[0115] “Elevated temperatures” as described herein may be temperatures exceeding 700 °C, 800 °C. 900 °C. or 1000 °C. In some embodiments, the elevated temperature is above about 700 °C and below about 1000°C.

[0116] “Mild temperatures” as described herein may be temperatures exceeding about 300 °C, 400 °C. 500 °C, 600 °C, or 700 °C but not exceeding about 700 °C. In some embodiments, the elevated temperature is above about 300 °C and lower than about 700 °C.

[0117] “Low lithium residuals” as described herein may be Li2O surface content detected below 2000 ppm, 1500 ppm, 1000 ppm, 500 ppm, or 0 ppm. In some embodiments, low lithium residuals is above 0 ppm and lower than 2000 ppm.

[0118] “High lithium residuals” as described herein may be Li2O surface content detected above 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, or 5000 ppm. In some embodiments, high lithium residuals is a value above 2000 ppm.

[0119] “Smooth surface” as described herein may be specific surface area measured below 0.8 m2 / g, 0.7 m2 / g, 0.6 m2 / g, or 0.5 m2 / g. In some embodiments, smooth surface is above 0 m2 / g and below 0.8 m2 / g.

[0120] “Rough surface” as described herein may be specific surface area measured above 0.8 m2 / g, 0.9 m2 / g, 1.0 m2 / g, 1.1 m2 / g, 1.2 m2 / g, 1.3 m2 / g, 1.4 m2 / g, or 1.5 m2 / g. In some embodiments, rough surfaces is above 0.8 m2 / g.

[0121] “Surface area” measurements referred to herein in terms of m2 / g are BET surface area measurements.

[0122] 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.

[0123] The term “low melting point” is intended to refer to a melting point below about 920°C.

[0124] The term "03" is intended to refer to phases having a a-NaFeO2 type structure, as described in C. Delmas, C. Fouassier, and P. Hagenmuller, Physica, 99B (1980)

[0125] 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 or components 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 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.

[0126] 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 Li2CC>3. Lithium residues are generally undesirable because they can lead to undesirable side reactions that reduce battery capacity7. 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.

[0127] 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 boundary from other forms of matter.

[0128] “Single crystal morphologies” or “single crystal” 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 refers to a crystalline solid where the particle consists essentially of one or more grains, where the average grain facet size is greater than 20% of the average particle size. In some embodiments of single cry stal particles, each particle consists of a single crystal essentially free from interparticle boundaries. A single cry stal may also be referred to as a “monocrystal” or have the acronym “SC.” A single crystal morphology is where the average grain facet size is greater than 20% of the average particle size.

[0129] The term “poly crystalline” should be given its ordinary meaning as it would be understood by a person having ordinary’ skill in the art and 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 grains may be less than 20% of the average particle size. The acronym “PC” refers to polycry stalline herein.

[0130] 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 disclosure but often refers to a minimal amount of something in a material. For example, in someembodiments substantially free means a material may contain less than 1% of something that it is ■substantially free” of.

[0131] 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 often refers to an environment that is free or substantially free of solvents including organic or aqueous solvents. A “liquid-free environment” generally excludes solvents in liquid form but does not exclude solid hydrates, such as the solid hydrate LiOH- H2O. The “liquid” state of a material is intended to refer to its state at about 21 degrees Celsius and about 1 atm.

[0132] The term “coating” generally refers to a layer of material(s) applied to an object. The coating may be cured or hardened onto the object such that it is generally inseparable from the object. The coating may range from a monolayer of atoms up to several hundred microns or more, depending upon the particle size. The coating may be a partial coating on the surface of a material.

[0133] The term “cathode” should be given its ordinary meaning as it would be understood by a person having skill in the art at the time of the disclosure and refers to the electrode at which reduction occurs when a metal-ion battery is discharged. In a lithium-ion cell, the cathode is the electrode that is lithiated during discharge and delithiated during charge. The cathode may also be called the “positive electrode.”

[0134] 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.

[0135] The term “D50” 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 median particle size of a group of particles, as measured by a random group of particles.

[0136] “Refiring” as used herein should be given its ordinary meaning as it would be understood by a person having skill in the art at the time of the disclosure but also refers to sintering, heating, or firing cathode materials that have been previously synthesized through heating. For example, single crystal cathode materials are synthesized through calcination, which is generally considered a first firing. Therefore, post-processes involving heating or firing previously synthesized cathode materials may be termed a “refiring.” Multiple refiringsmay be performed, such as disclosed herein, and other post-processing steps may be performed before or between refirings.

[0137] 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.

[0138] 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.

[0139] “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 O2.

[0140] 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.

[0141] “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 solvents. These residues include but are not limited to salts, acids, bases, trace metals, and trace impurities. For example, acid residues may come from inorganic acids such as HC1, HNO3, H2SO4, H3PO4, and organic acids such as citric, dl-malic, ascorbic, succinic, oxalic, 1-tartaric, lactic acid, and formic acids. Other solvent residues may be trace metals, such as sodium, magnesium, calcium, iron. etc. Trace impurities may comprise residues incompletely removed from solvent reagents. These trace impurities may be acceptable according to industry standards for the purity of certain reagents. These trace impurities may in the amount of parts per million (ppm) or parts per billion (ppb).

[0142] A “particulate” as used herein is intended to refer to a material with particles. The term “particle” should be given its ordinary meaning as would be understood bya person having ordinary' skill in the art but is intended to refer to a generally spherical or oblong material.

[0143] 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 provided in the alternative (“or”).

[0144] As used herein, the terms “a” or “an” or “the” may refer to one or more than one. For example, “a” dopant can mean one dopant or a plurality of dopants.Examples

[0145] Some aspects of the embodiments discussed above are disclosed in further detail in the following examples, which are not in any way intended to limit the scope of the present disclosure. Those in the art will appreciate that many other embodiments also fall within the scope of the disclosure, as it is described herein above and in the claims. The following are exemplary in nature to better illustrate the present disclosure and are non-limiting in scope, application or uses.Material characterization

[0146] Scanning electron microscope (SEM) images were taken using a Phenom XL G2 Desktop SEM with an accelerating voltage of 15 kV under secondary' electrons (SE) and backscattered electrons (BSE) modes. Powder samples were prepared by adhering onto a sample stub using conductive carbon tape.

[0147] X-ray diffraction (XRD) patterns of powders were measured by a Bruker D8 Advance diffractometer with a Cu Ka X-ray source and a diffracted beam monochromator. Rietveld refinement w as done on the measured XRD patterns to quantify the amount of cation mixing: Ni in the Li layers using Rietica software. Cation mixing 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

[0148] Particle size diffraction (PSD) of powders w ere measured by a Horiba LA- 950V2 particle size analyzer. Samples were prepared by flocculating in 0.2 wt% sodium hexametaphosphate (NaHMP) in DI water.

[0149] Brunauer-Emmett-Teller (BET) surface area of powders were measured by a Quantachrome NOVAtouch LX2 gas sorption system. Samples were prepared by degassing at 760 torr before measurements. Each sample was measured twice using a 5-point BETmeasurement with P / Poratio ranging from 0.05 to 0.3. Nitrogen was used as absorbate gas. Void volume was measured by Helium.

[0150] Lithium residuals of powders were measured by a Mettler Toledo Titrator Excellence T5. Samples were prepared by flocculating in DI water and titrated with 0.1 M of HC1 solution to determine LiOH and Li2COs contents on the surface of materials. Li2O equivalent was used as a universal metric to compare the total amount of surface lithium residuals, which include both LiOH and Li2CO3. Li2O equivalent was calculated using the following formula:( (LiOH (ppm)\ / Li2CO3 (ppm)\\L12O (p1p 1 m) 3 = - * 2 + - „„ * 29.88 H 23.95 ) k 73.89 ) JCell preparation and electrochemical evaluation

[0151] Electrode slurries were prepared by mixing of active material, carbon black, and polyvinylidene fluoride in a weight ratio of 0.94: 0.04: 0.02 in N-Methyl-2-Pyrrolidone with a solid content of 50 % using a planetary mixer. The slurry was coated onto 15 pm 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 140 °C overnight. The dried electrodes were compressed using by calendar rolling and punched with a 13.00 mm diameter. The areal active mass loading was -18-22 mg / cm2. Coin-cells were assembled in an Ar filled glovebox with one sheet of active electrode, Li foil counter electrode, 2 layers of separator (Celgard 2500), and 100 pL of 1.2M LiPFe in a solution of ethylene carbonate: ethylmethyl carbonate: dimethyl carbonate (EC:EMC:DMC (25:5:70 wt%)) electrolyte using CR2032 coin-type casings. Galvanostatic cycling measurements were made using a NOVONIX ultra high-precision coulometry system at a controlled temperature of 25.0 °C.Example 1.

[0152] Pristine poly crystalline and single-crystalline LiNio.6Mno.2Coo.2O2 (NMC622) were made by an all-dry or solid-state method as follows. Nio.6Mno.2Coo.2(OH)2 precursor was mixed with 10 % excess Li2COs in a high-speed blade grinder for 20 minutes. The mixed pow der w as transferred into an alumina crucible and sequentially heated in a tube furnace under an oxygen atmosphere at 870 °C for 20 hours to make polycrystalline (PC) NMC622 or 940 °C for 20 hours to make single crystalline (SC) NMC622. 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. The calcined single-crystalline NMC622 product was jet milled tode-agglomerate secondary particles resulting in pristine single-crystalline NMC622 material (120) (Pristine SC). The calcined polycrystalline NMC622 product (120) (Pristine PC) was used as prepared without any milling to preserve its poly crystalline morphology.

[0153] Refired polycrystalline (Refired PC) and refired single-crystalline (Retired SC) NMC622 were made by reheating pristine poly crystalline (Pristine PC) and pristine singlecrystalline (Pristine SC) NMC622. respectively, at 900 °C for 3 hours with the heating / cooling rates at 5 °C / min. Refired PC and Refired SC samples were deagglomerated using a blade grinder in for 1 min and sieved using a 325-mesh sieve before dry coating in the next step. Fumed alumina (alumina oxide power) was dry-coated on pristine polycrystalline (Pristine PC_Coated), refired polycrystalline (Refired PC_Coated), pristine single-crystalline (Pristine SC Coated), and refired single-crystalline NMC622 (Refired SC Coated) by using a blade grinder for 1 min at 1 wt% fumed alumina.

[0154] Table 1. Particle size analyses and lithium residual quantifications of 1 wt% fumed alumina-coated NMC622 samples.

[0155] Figure 3 shows the morphology of fumed alumina that was used in this disclosure, and Figure 4 shows SEM images of (a) fumed alumina-coated on pristine poly cr stalline, (b) fumed alumina-coated on pristine single-crystalline, (c) fumed alumina- coated on refired polycrystalline. (d) fumed alumina-coated on refired single-crystalline NMC622. Due to their small particle size, fumed alumina particles were deposited on the surface of NMC622 as a thin layer as shown in Figure 4. Therefore, the morphologies(relatively smooth or rough surfaces) of fumed alumina-coated NMC622 samples retain the morphologies ofNMC622 samples prior to coating.

[0156] The refiring step (130) did not affect the morphology of poly crystalline NMC622 samples (Figure 4 (a) and (c)). Table 1 indicates that the particle size of Pristine PC_Coated sample with a D50 of 6. 10 pm and Refired PC_Coated sample with a D50 of 6.33 pm were similar. However, there were significant differences in morphology and particle size of Pristine SC_Coated sample with a D50 of 2.87 pm and Refired SC_Coated sample with a D50 of 3.88 pm. It could be explained that there were cracks and defects on the surface of single-crystalline NMC622 after jet-milling. The refiring step (130) therefore can heal cracks and fix surface defects resulting in a smooth surface with fewer small fractures.

[0157] As shown in Table 1, there were high lithium residuals on the surface of Pristine SC Coated sample with 4344 ppm of Li2O. In contrast, a low amount of lithium residuals was found on Refired SC_Coated sample with 857 ppm Li2O, indicating the importance of refiring single-crystalline NMC622 prior to performing dry' coating to obtain NMC cathode materials with low lithium residuals. Interestingly, there was no significant difference in the amount of lithium residuals on the surface of Pristine PC Coated sample and Refired PC_Coated sample which is 2525 ppm and 2400 ppm of Li2O respectively. The discrepancy in the impact of the refiring step prior to dry coating between poly crystalline and single-cry stalline NMC622 samples suggests that the refiring step (130) is a highly advantageous step for making single-crystalline NMC materials.

[0158] Figure 5(a) shows that fumed alumina-coated NMC622 samples that were refired at high temperatures prior to dry coating have loyver discharge capacities than the ones without the refiring step. Discharge capacity loss could be attributed to lithium loss during the refiring step (130). Extra lithium could be added during the refiring step (130) to compensate for lithium loss during high-temperature heat treatment, which is expected to improve discharge capacities. There was no difference in the capacity retention of fumed alumina- coated poly crystalline NMC622 samples, indicating that the refiring step (130) prior to dry coating step (150) yvas not necessary’ for making poly crystalline NMC cathode materials. However, it is clear that single-crystalline NMC622 should be refired (130) prior to dry coating (150) based off electrochemical data as shown in Figure 5(b). Without the refiring step (130), Pristine SC_coated NMC622 sample had poor capacity retention over a period of 25 cycles.

[0159] Therefore, a refiring step should be used to modify single-crystalline NMC cathode materials before attempting dry coating.Example 2,

[0160] Pristine single-cry stalline LiNio.6Mno.2Coo.2O2 (NMC622) was made by the solid-state method as follows. A mixture of NiO, CO3O4, Mn.-O . and 10% excess Li2COs in a stoichiometric ratio of LiNio.6Mno.2Coo.2O2 was mixed in a high-speed blade grinder for 20 minutes. The mixed powder was transferred into an alumina crucible and sequentially heated in a tube furnace under an O2 atmosphere at 600 °C for 3 hours, 950 °C for 20 hours, and then cooled down to room temperature. The heating rate and cooling rates were at 5 °C / min and 1 °C / min, respectively. The calcined product was jet milled to obtain pristine single-crystalline NMC622 material. The pristine single-crystalline NMC622 was then refired at 900 °C for 1 hour and then jet milled to obtain refired single-crystalline NMC622 (Refired900C). 1 wt% commercial fumed alumina was dry-coated on refired single-crystalline NMC622 by using a blade grinder for 1 min (refired900C_Coated). The coated single-cry stalline NMC622 was then refired the second time at different temperatures including 500 °C (Refired900C_Coated_refired500C), 600 °C (Refired900C_Coated_refired600C), 650 °C (Refired900C_Coated_refired650C), 700 °C (Refired900C_Coated_refired700C) for 3 hours. The samples that went through the second refinng step were deagglomerated using a blade grinder for 1 min and sieved using a 325 -mesh sieve before testing.

[0161] Table 2. Surface area of single-crystalline NMC622 samples.

[0162] Due to the small particle size, fumed alumina particles would adhere to the surface of single-crystalline NMC622 via physical interaction after dry coating (150). This physical interaction might not be strong enough to withstand vigorous mixing during cathode slurry' preparation, resulting in the detachment of fumed alumina from NMC622 surfaces. One way to improve the adhesion of fumed alumina particles towards single-crystalline NMC622particles is to perform heat treatment to form chemical bonds between them. It seems to be difficult to quantify the interaction between fumed alumina particles and NMC622 particles at different T2 refiring temperatures by looking at SEM images (Figure 6). However, the BET surface area decreased with increasing second refiring temperature indicating some reaction is happening. It is worth noting that the melting point of aluminum oxide is above 2000 °C. Therefore, the reduction in surface area with temperature is a result of fumed alumina reacting with single-crystalline NMC622 particles rather than alumina melting and recrystallizing. The higher the second refiring temperature, the more the fumed alumina particles react with singlecrystalline NMC622 particles. The surface area of refired900C_coated_refired700C singlecrystalline NMC622 sample was smaller than that of refired_900C single-crystalline NMC622, which indicates the diffusion of aluminum into the bulk of NMC622 when the 2ndrefiring temperature reached 700 °C.

[0163] Therefore, the 2ndrefiring (step 170) after the dry coating step is highly advantageous to keep fumed alumina on the surface of NMC622 particles. The 2ndrefiring temperature should be limited to prevent diffusion of all aluminum into the bulk of singlecrystalline NMC622.Example 3,

[0164] Pristine single-crystalline LiNio.6Mno.2Coo.2O2 (NMC622) was made by the solid-state method as follows. A mixture of NiO, CO3O4, M113O4. and 10 % excess Li2CO3 in a stoichiometric ratio of LiNio.6Mno.2Coo.2O2 was mixed in a high-speed blade grinder for 20 minutes. The mixed powder was transferred into an alumina crucible and sequentially heated in a tube furnace under an O2 atmosphere at 600 °C for 3 hours, 950 °C for 20 hours, and then cooled down to room temperature. The heating rate and cooling rates were at 5 °C / min and 1 °C / min, respectively. The calcined product was jet milled to obtain pristine single-crystalline NMC622 (Pristine). The pristine sample was refired at 900 °C for 3 hours under an O2 atmosphere to obtain a refired single-crystalline NMC622 (Refired900C). 1 wt% fumed alumina was dry-coated on pristine single-crystalline NMC622 by using a blade grinder for 1 min to obtain a coated single-crystalline NMC622 (Coated). The coated sample was refired at 900 °C for 3 hours under an O2 atmosphere to obtain a coated and refired sample (Coated_Refired900C). 1 wt% fumed alumina was coated on Refired900C to obtain a refired and coated sample (Refired900C_Coated). Refired900C_coated sample was refired at 600 °C for 3 hours under an O2 atmosphere to obtain a refired at 900 °C, coated, and refired at 600 °C sample (Refired900C coated Refired600C). All samples that were refired weredeagglomerated using a blade grinder for 1 min and sieved using a 325-mesh sieve before testing or conducting other experiments.

[0165] Table 3. Lithium residual and surface area measurement of NMC622 samples

[0166] From SEM images (Figure 7), the rough edges present on Pristine sample (Figure 7(a)) smoothens after refiring at 900 °C as demonstrated in Refired900C (Figure 7(b)) and Coated_refire900C (Figure 7(d)). In addition, the coated samples (Figure 7(c) & (e)) demonstrate even distribution of fumed alumina. Furthermore, from XRD data (Figure 8), there is an improvement in crystallinity when refiring is done.

[0167] Table 3 shows that the first refiring step (130) at 900 °C reduced the amount of lithium residuals significantly from more than 2000 ppm in the pristine sample to less than 1000 ppm in the Refired900C sample. The surface area of the Refired900C sample was 0.54 m2 / g compared to around 1 m2 / g for the Pristine sample. A smaller surface area results in less reaction between electrolyte and cathode materials, thus improving cycle life. As shown in Figure 9. (b), the refired900C sample shows higher capacity retention than the pristine sample.

[0168] It is important to compare the coated sample and the refired900C_coated sample to evaluate the importance of the refiring step (130) prior to dry coating (150). The coated sample has a higher amount of lithium residuals and a higher surface area than therefired900C_coated sample. Moreover, the discharge capacity retention of the refired900C_coated sample is also much higher than that of the coated sample (Figure 9(b)). The above results indicate the importance of the first refiring step (130) prior to the dry coating step (150).

[0169] The importance of the second refiring step (170) after the dry coating step (150) was also investigated. Even though the amount of lithium residuals on the surface of the refired900C_coated_refired600C sample is slightly higher than that of the refired900C_coated sample, the refired900C_coated_refired600C sample has a smaller surface area than the refired900C_coated sample. This could be attributed to reactions between fumed alumina particles and single-crystalline NMC622 particles, which strengthen the adhesion of fumed alumina coating layers to the surface of single-crystalline NMC622 particles. As a result, the capacity retention of refired900C_coated_refired600C sample is much better than that of refired900C_coated sample.

[0170] Coated_Refired900C sample was made by coating fumed alumina directly on Pristine sample (120) without going through 1strefiring step (130) and then refired at 900 °C. As shown in Figure 9(a), Coated_Refired900C sample has very low discharge capacities. This result indicates the importance of the 1strefiring step (130) and also the detrimental impact of refiring at very high temperatures on NMC materials that were previously coated with fumed alumina particles.

[0171] In conclusion, it is highly advantageous to implement two refiring steps before and after the coating step with nanomaterials to achieve long-lived single-crystalline NMC materials.Example 4,

[0172] Pristine single-crystalline (SC) LiNio.6Mno.2Coo.2O2 (NMC622) was made by the solid-state method as follows. A mixture ofNiO, CO3O4, MnsO4, and 10% excess Li2CO3 in a stoichiometric ratio of LiNio.6Mno.2Coo.2O2 was mixed in ahigh-speed mixer for 20 minutes to produce the NMC precursor 100. The mixed powder was loaded into a mullite saggar and then slowly passed through a roller hearth kiln (RHK). RHK settings allowed the saggar to stay at 930 °C for 16.25 hours and at 880°C for 3 hours under an oxygen atmosphere. The calcined product was jet milled to obtain pristine SC NMC622 (step 120).

[0173] Pristine polycrystalline (PC) LiNio.6Mno2Coo.2O2 (NMC622) was made as follows. Commercially available Nio.6Mno.2Coo.2(OH)2 precursor was mixed with 10% excess Li2CO3 in a stoichiometric ratio of LiNio.6Mno.2Coo.2O2 in a high-speed blade grinder for 20 minutes. Then the mixed powder was transferred into an alumina crucible and sequentiallyheated in a tube furnace under an oxygen atmosphere at 850 °C for 20 hours. 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. The calcined PC NMC622 was used without any milling to preserve its poly crystalline morphology.

[0174] Pristine SC and PC NMC622 samples were refired at 500 °C or 800°C for 3 hours, and then were coated with 0.5 wt% fumed alumina by using a high-speed blade mixer before refiring for a second time at 500 °C for 3 hours. Table 4 describes sample information.Table 4. Sample information

[0175] As shown in Figure 10, there were rough layers of alumina on the surface of PC_500 and PC_800 samples. Besides that, there was no significant change in the overall morphology of PC NMC622 samples before and after performing the dry coating process with two refiring steps. Furthermore, Figure 11 indicates the similarity in XRD patterns of PC NMC622 samples. These morphological and structural data suggest that the first refiring step prior to fumed alumina coating could be less important for polycrystalline NMC materials.

[0176] In contrast, the first refiring step (130) prior to fumed alumina coating (150) is highly advantageous or crucial for the dry coating process of single-crystalline NMC materials. As shown in Figure 13, SC-800 sample showed better crystallinity than SC_Pristine and SC_500 samples. Table 5 provides the lithium residual deposits on various NMC622 samples.Table 5. Lithium residuals amount on NMC622 samples.

[0177] Figure 14(a) shows that there was no significant change in the amount of lithium residuals on PC NMC622 samples, which indicated no benefit of refiring at 800 °C instead of 500 °C in the first refiring step prior to dry coating for polycrystalline NMC materials. However, as shown in Figure 14(b), there was a clear trend for lithium residuals on SC NMC622 samples. SC 800 sample contained much less lithium residual than SC 500C even though the two samples were coated with the same amount of fumed alumina and refired at the same temperature for the 2ndrefiring (170) temperature. This result indicates the importance of the first refiring (130) temperature. The 1strefiring (130) at 800 °C not only fixed surface defects, and increased crystall inity but also reduced surface lithium residuals. Low temperatures for the first refiring step (130) can be less favorable.

[0178] Figure 15 further demonstrates the impact of the temperature of the first refiring step (130) on cathode materials. As shown in figure 15, when poly crystal materials are refired at 500 °C or 800 °C their BET surface area does not change significantly. However, when the same conditions are applied to single crystal materials, there is an inverse correlation with the temperature of refiring step (130) and the BET surface area. As the refiring step (130) increases in temperature, the BET surface area decreases. This further highlights that polycry stal and single crystal materials require different treatments. In addition, this indicates that the first refiring step (130) requires high temperatures for single crystal cathode materials.

[0179] Figure 16 further emphasizes the benefit of high temperatures in the first refiring step (130) for SC NMC materials. SC_800 sample showed better discharge capacity retention than SC_Pristine and SC_500. These electrochemical results together with the physical characterization data demonstrate that SC NMC materials require a high-temperature refiring step (130) to fix surface defects, improve crystallinity, and reduce lithium residuals before performing coating and subsequent refiring steps.

[0180] It is commonly believed that a rough surface is beneficial for good coating adhesion between coating chemicals and NMC materials. In this case, single-crystalline NMC materials that were made using the solid-state method have surface defects after jet milling. The surface roughness would be beneficial for direct fumed alumina coating. However, thisstudy shows that NMC materials should be subjected to a high-temperature refiring step (130) prior to dry coating (150) and subsequent heat treatment.Example 5

[0181] Pristine single-crystalline (SC) LiNio.6Mno.2Coo.2O2 (NMC622) was made by the dry solid-state method as follows. A mixture of NiO, CO3O4, Mn3O4. and 10% excess Li2CO3 in a stoichiometric ratio of LiNio.6Mno.2Coo.2O2 was mixed in a high-speed mixer for 20 minutes to produce the NMC precursor (100). The mixed powder was loaded into a saggar and then slowly passed through a roller hearth kiln (RHK). RHK settings allowed the saggar to stay at 930 °C for 16.25 hours and at 880 °C for 3 hours under an oxygen atmosphere. The calcined product was jet milled to obtain pristine SC NMC622 (120).

[0182] The pristine SC NMC622 sample (120) was refired at 800 °C for 3 hours and then jet milled to obtain refired SC NMC622 (140). The refired SC NMC622 (140) was coated with 1 wt% fumed alumina by a high-speed blade mixer before refiring for 3 hours at either 500 °C (1FA-500) or 900 °C (1FA-900).

[0183] Table 4. Sample Conditions

[0184] SEM images of 1FA-500 and 1FA-900 in Figure 17 demonstrate that the morphology of samples with the two different 2ndrefining (170) temperatures are very similar. This demonstrates that the second refiring temperature does not affect the morphology of the single crystal. In Figure 18, EDX line scan images depict the elemental composition of nickel, manganese, cobalt, and aluminum across a single cry stal cathode with second refiring temperature at 500 °C and 900 °C. This figure demonstrates that the elemental composition of nickel, manganese, and cobalt across the single crystal maintain the NMC622 stoichiometry regardless of the second refiring temperature. However, in figure 18 (D) when observing the elemental composition of aluminum, the results indicate that aluminum remains on the surface with 1FA-500 where the second refiring temperature is at 500 °C. For 1FA-900 where the second refiring temperature is at 900 °C. figure 18 (C) demonstrates that the elemental distribution of aluminum across the particle is the same. In other words, the aluminum contentdoes not van' from the edge to the center of the particle. However, with 1 FA-500, figure 18 (D) demonstrates that there is a variation in aluminum content from the edge to the center of a single crystal cathode, indicating that the Al remains as a surface coating. For this sample, the majority of the aluminum measured is concentrated on the edge of the particle, indicating that a coating has been formed on the surface. This reinforces that a lower second refiring temperature is required after coating to preserve the surface coating. Having a well-protected surface enables longer cycle life since the material is protected from electrolyte which can allow cracking of the surface. Therefore, second refiring temperatures in embodiments herein are maintained below about 700 Celsius in order to preserve a concentrated surface coating.

[0185] Furthermore, the discharge capacity' of cells made from 1FA-900 and 1FA- 500 shown in figure 19 demonstrates that a lower second refiring temperature provides better results. The discharge capacity values are higher with 1FA-500 than 1FA-900. Therefore, these results further demonstrate that lower second refiring (170) temperatures are required to ensure better electrochemistry and coatings on the surface.Example 6

[0186] The pristine single crystal LiNi0.70Mn0.29Co0.01O2 (Pristine_NMC702901) sample was refired at 750 °C for 3 hours under a flow of oxygen to obtain refired single crystal NMC702901 (Refired_NMC702901). The refired_NMC702901 was then mixed with 0.25 wt% (0.25NMC702901) AI2O3 or 0.5 wt% AI2O3 (0.5NMC702901) in a blender for 1 minute. This mixture was then transferred to an alumina crucible and fired at 500 °C for 3 hours.

[0187] The SEM images in figure 20 demonstrates that there no morphological changes after coating with alumina using methods outlined in this disclosure. Therefore, the morphology' of the final product retains the morphology of the pristine material. The XRD images in figure 21 demonstrates that implementing the methods in this disclosure did not change the crystal structure. The crystallinity of the material was retained after coating with alumina. As previously indicated, the BET specific surface area increases w ith alumina coating as shown in table 5. As the alumina percentage increases, the BET specific surface area increases. Furthermore, the lithium residuals on the surface remain low.

[0188] Lastly, these materials were integrated into coin cells to test its electrochemical performance and cycled between 2.8 to 4.4 V at C / 20 for the first 2 cycles and C / 5 for the remaining cycles. Figure 22 (A) demonstrates that the specific discharge capacity has increased after implementing the methods described in this disclosure. In addition, the capacity retention demonstrated in figure 22 (B) has improved and thus by implementing this method, the longevity of the material is increased.Example 7

[0189] The pristine single crystal LiNi0.60Mn0.34Co0.06O2 (Pristine_NMC640) sample was refired at 750 °C for 5 hours under a flow of oxygen to obtain refired single crystal NMC640 (Refired_NMC640). The refired_NMC640 was then mixed with 0.40 wt% AI2O3 in a blender for 1 minute. This mixture was then transferred to an alumina crucible and fired at 500 °C for 3 hours under a flow of oxygen to obtain a coated single crystal NMC640 (0.40NMC640).

[0190] Table 6. specific surface area of samples in Example 7.

[0191] The SEM images in figure 23 displays the surface morphology of the material as it is processed through the steps in this disclosure. In figure 23 (a) and (d), the particles of pristine_NMC640 are angular with defined edges. However, after refirmg, figure 23 (b) and (e) demonstrate that the edges of the refired_NMC640 particle are smoothened and present rounded edges. This demonstrates that the surface has been changed after refiring. Furthermore, in table 6, the BET surface area of refired_NMC640 is lower than pristine_NMC640. which demonstrates that the first refiring step 130 described in this disclosure causes the surface area to decrease. This further indicates that refiring material aftersynthesis will smoothen the surface, preparing it for coating. Thereafter, coating refired_NMC640 with alumina to make 0.40NMC640, table 6 demonstrates that there is an increase in surface area of the particle likely due to alumina’s high surface area. The XRD image in figure 24 demonstrates that a layered 03 phase was formed and retained for all 3 samples. Furthermore, in figure 25 (c) which shows the peaks becoming more defined after refiring and further improved after coating with 0.40 wt% alumina. Therefore, the implementation of methods in this disclosure did not introduce new crystal structures into the material.

[0192] Lastly, these materials were integrated into half coin cells to test its electrochemical performance and cycled between 2.8 to 4.5 V at C / 20 for the first 2 cycles and C / 5 for the remaining cycles. The discharge specific capacity versus cycle number shown in figure 26 (a) demonstrates that there is an increase in the first cycle capacity upon refiring with a slight decrease after coating. While there is a decrease in capacity after coating, this is still higher than pristine material. Furthermore, the normalized capacity7in figure 26 (b) demonstrates that implementing the methods in this disclosure improves capacity retention. Example 8

[0193] Pristine SC NMC631 (Pristine NMC631) was refired at 800 °C for 5 hours in RHK and then jet milled to obtain refired SC NMC631 (refired NMC631). The refired NMC631 was coated with 0.4 wt% fumed alumina by using a high-speed blade mixer before refiring at 500 °C for 3 hours to form finished NMC631 (finished NMC631).

[0194] Figure 27 show s SEM images of pristine NMC631 , refired NMC631, and finished NMC631. All three samples exhibit similar morphology w ith the exception of pristine NMC631 which presents more cracks and smaller particles than refired NMC631 or finished NMC631. This further demonstrates that the techniques described in this disclosure smoothen and decrease the surface area of the particles. Figure 28 (a) and (b) shows XRD images of the 3 samples and demonstrates that all 3 samples have a pure 03 phase structure. Improved crystallinity7was observed after refiring compared to the pristine sample as evidence by greater (108) / (l 10) peak separation in figure 28 (b). Figure 29 shows improved electrochemical performance in terms of specific discharge capacity and capacity retention after treating pristine materials with three steps described in this disclosure including 1strefiring 130, dry coating 150, and 2ndrefiring 170.

[0195] These results further confirm the importance of post-treat pristine NMC materials with several steps including 1strefiring 130 to fix surface defects, dry coating 150 tocover the surface with protective coating materials, and 2ndrefiring 170 to enhance chemical bonding between NMC with protective materials coating layers.Example 9

[0196] Pristine single-crystalline LiNio.6Mno.2Coo.2O2 (NMC622) was made by an all-dry or solid-state method as follows. A mixture of NiO, CO3O4, MnsO4, and 5% excess Li2CO3 in a stoichiometric ratio of LiNio.6Mno.2Coo.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 l°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.

[0197] The surface of Zr(OH)4-treated NMC622 was smoother than that of pristine NMC622 and refired NMC622 as demonstrated by a decrease in BET surface area of the Zr(OH)4-treated NMC622. In fact, surface area of Zr(OH)4-treated NMC622 was three times smaller (0.5 m2 / g) than that of pristine NMC622. Further, crystallinity increased when pristine NMC 622 was refired or treated with Zr(OH)4, as demonstrated by a the degree of peak separation between 63.5° and 66° 20. Further, 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.

[0198] As shown in Table 7, 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.

[0199] Table 7. Cation mixing through Rietveld refinement of pristine NMC622, refired NMC622, and Zr(OH)4-treated NMC622.Example 10

[0200] Pristine single-cry stalline LiNio.8Mno.1Coo.1O2 (NMC811) was made by the solid-state method as follows. A mixture of Ni, Co, Mn, and 1% excess Li2CO? in a stoichiometric ratio of LiNio.8Mno.1Coo.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 l°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.

[0201] Similar to example 9, the surface of refired and Al acetate-treated NMC811 samples were much smoother than that of pristine NMC811 and the crystallinity of refired and Al acetate-treated NMC811 samples were better than that of pristine NMC811. Finally. Al acetate-treated NMC811 had a capacity retention much better than the pristine and refired NMC811 samples.Alternatives

[0202] Some embodiments herein may be described according to the following numbered alternatives:

[0203] Alternative 1. A dry coating method for preparing single-crystal Li-ion battery cathode materials, the method comprising: a) refiring pristine single-crystal cathode materials at a temperature (T1 ) exceeding 700 Celsius; b) dry coating the refired single-crystal cathode materials with one or more coating materials, wherein the dry coating is a dry coating free of solvents; and c) reheating the coated single-crystal cathode materials at temperatures below 700 Celsius (T2) to affix the one or more coating materials to particle surfaces of the single-crystal cathode material.

[0204] Alternative 2. The method of alternative 1, wherein the surface area of the pristine single-cry stal cathode materials decreases by at least 45% after the refiring.

[0205] Alternative 3. The method of alternatives 1 or 2, wherein the pristine singlecrystal cathode materials were previously fired at a temperature (TO) exceeding 800 Celsius prior to the refiring.

[0206] Alternative 4. The method of any one of alternatives 1-3, wherein after the firing at TO the single-cry stal cathode materials were cooled to a temperature below 100 Celsius.

[0207] Alternative 5. The method of any one of alternatives 1-4. wherein the lithium residuals of the pristine single-crystal cathode materials are reduced by at least 30% after the refiring.

[0208] Alternative 6. The method of any one of alternatives 1-5, wherein T1 is about 800 Celsius.

[0209] Alternative 7. The method of any one of alternatives 1-6, wherein the surface area of the pristine single-crystal cathode materials decreases by at least 15% after the refiring

[0210] Alternative 8. The method of any one of alternatives 1-7, wherein the surface area is BET specific surface area.

[0211] Alternative 9. The method of any one of alternatives 1-8, wherein the lithium residuals of the pristine single-cry stal cathode materials are reduced by at least 100% after the refiring.

[0212] Alternative 10. The method of any one of alternatives 1-9, wherein the one or more coating materials are isolated to the particle surfaces of the coated single-crystal cathode materials after the reheating.

[0213] Alternative 11. The method of any one of alternatives 1-10, wherein the one or more coating materials remain within 300 nm of the particle surfaces of the coated singlecrystal cathode materials after the reheating.

[0214] Alternative 12. The method of any one of alternatives 1-11, wherein at least 80% of the one or more coating materials remain within 200 nm of the particle surfaces of the coated single-crystal cathode materials after the reheating.

[0215] Alternative 13. The method of any one of alternatives 1-12, wherein lithium compounds are added to the pristine single-crystal cathode materials prior to the reheating and the lithium compounds comprise lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxide, and combination thereof.

[0216] Alternative 14. The method of any one of alternatives 1-13, wherein the one or more coating materials do not penetrate further than 200 nm from a particle surface of the coated single-crystal cathode material particle.

[0217] Alternative 15. The method of any one of alternatives 1-14, wherein the coated single-crystal cathode material is comprised of a plurality7of coated single-crystal cathode particles.

[0218] Alternative 16. The method of any one of alternatives 1-15. wherein the coated single-crystal cathode particles have a D50 between 0.1 pm and 20 pm.

[0219] Alternative 17. The method of any one of alternatives 1-16, wherein the one or more coating materials are concentrated on the particle surfaces of the coated single-crystal cathode material.

[0220] Alternative 18. The method of any one of alternatives 1-17, wherein the coated single-cry stal cathode material has a specific capacity of at least 150 mAh / g after 20 cycles.

[0221] Alternative 19. The method of any one of alternatives 1-18. wherein the coated single-cry stal cathode material maintains at least 80% of its discharge capacity after 1,000 cycles.

[0222] Alternative 20. A coated single-cry stal cathode material produced according to any of alternatives 1-19.

[0223] Alternative 21. The coated single-crystal cathode material of Alternative 20, wherein the coated single-crystal cathode material is free of solvents and solvent residues.

[0224] Alternative 22. The coated single-cry stal cathode material of Alternative 20, wherein the coated single-cry stal cathode material is free of solvent residues or impurities such as aqueous residues, organic residues, acidic residues, or basic residues.

[0225] Alternative 23. The coated single-crystal cathode material of Alternative 20, wherein the coated single-crystal cathode material has less than 1 ppm of solvent residues.

[0226] Alternative 24. The coated single-cry stal cathode material according to any one of alternatives 19-23, wherein the coated single-crystal cathode material is coated NMC.Additional Embodiments

[0227] It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein.In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein.

[0228] Reference throughout the specification to "‘one example”, “another example”, “an example”, and so forth, means that a particular element (e.g., feature, structure, and / or characteristic) described in connection with the example is included in at least one example described herein, and may or may not be present in other examples. In addition, it is to be understood that the described elements for any example may be combined in any suitable manner in the various examples unless the context clearly dictates otherwise.

[0229] It is to be understood that the ranges provided herein include the stated range and any value or sub-range within the stated range, as if such value or sub-range were explicitly recited. For example, a range from about 2 nm to about 20 nm should be interpreted to include not only the explicitly recited limits of from about 2 nm to about 20 nm, but also to include individual values, such as about 3.5 nm. about 8 nm, about 18.2 nm, etc., and sub-ranges, such as from about 5 nm to about 10 nm, etc. Furthermore, when “about” and / or “substantially” are / is utilized to describe a value, this is meant to encompass minor variations (up to + / - 10%) from the stated value.

[0230] While several examples have been described in detail, it is to be understood that the disclosed examples may be modified. Therefore, the foregoing description is to be considered non-limiting.

[0231] While certain examples have been described, these examples have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the systems and methods described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.

[0232] Features, materials, characteristics, or groups described in conjunction with a particular aspect, or example are to be understood to be applicable to any other aspect or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed,may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The protection is not restricted to the details of any foregoing examples. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0233] Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a sub-combination or variation of a sub-combination.

[0234] Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results, unless provided otherwise herein. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some examples, the actual steps taken in the processes illustrated and / or disclosed may differ from those shown in the figures. Depending on the example, certain of the steps described above may be removed or others may be added. Furthermore, the features and attributes of the specific examples disclosed above may be combined in different ways to form additional examples, all of which fall within the scope of the present disclosure.

[0235] For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular example. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

[0236] Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain examples include, while other examples 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 examples.

[0237] Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain examples require the presence of at least one of X, at least one of Y, and at least one of Z.

[0238] Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” 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.

[0239] The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred examples in this section or elsewhere in this specification and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.

[0240] Although the foregoing invention has been described in terms of certain preferred embodiments, other embodiments will be apparent to those of ordinary skill in the art. Additionally, other combinations, omissions, substitutions, and modifications will be apparent to the skilled artisan, in view of the disclosure herein. Accordingly, the present invention is not intended to be limited by the recitation of the preferred embodiments but is instead to be defined by reference to the appended claims.

[0241] The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive manner and unless otherwise indicated refers to the ordinary meaning as would be understood by one of ordinary skill in the art in view of the specification. Furthermore, embodiments may comprise, consist of, consist essentially of, several novel features, no single one of which is solely responsible for its desirable attributes or is believed to be essential to practicing the embodiments herein described. As used herein, the section headings are for organizational purposes only and are not to be construed as limitingthe described subject matter in any way. When definitions of terms in incorporated references appear to differ from the definitions provided in the present teachings, the definition provided in the present teachings shall control. It will be appreciated that there is an implied ‘'about” prior to the temperatures, concentrations, times, etc. discussed in the present teachings, such that slight and insubstantial deviations are within the scope of the present teachings herein unless provided otherwise herein.

[0242] Although this disclosure is in the context of certain embodiments and examples, those of ordinary skill in the art will understand that the present disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses of the embodiments and obvious modifications and equivalents thereof. In addition, while several variations of the embodiments have been shown and described in detail, other modifications, which are within the scope of this disclosure, will be readily apparent to those of ordinary’ 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 maybe made and still fall within the scope of the disclosure. 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 or embodiments of the disclosure. Thus, it is intended that the scope of the present disclosure herein disclosed should not be limited by the particular disclosed embodiments described above.

Claims

Claims:

1. A dry coating method for preparing single-crystal Li-ion battery cathode materials, the method comprising: a) refiring pristine single-crystal cathode materials at atemperature (Tl) exceeding 700Celsius to heal cracks, smoothen surfaces, reduce surface area, reduce lithium residuals, or increase crystallinity’; b) coating the refired single-crystal cathode materials from a) with one or more coating materials, wherein the coating is a dry coating free of solvents; and c) reheating the coated single-crystal cathode materials from b) at temperatures below700 Celsius (T2) to affix the one or more coating materials to the surfaces of the single-crystal cathode material.

2. The method of claim 1, wherein single-crystal cathode materials have a layered structure with single crystal morphologies, a D50 average particle size in the range of 500 nm - 10 pm, the general chemical formula of Lii+x[(NinMnmCoc)i-aAa]i-xO2 where: n + m + c = 1;A is one or more dopants;-0.05<x<0. 1; and0 < a < 0.05.

3. The method of claim 2, wherein A is one or a combination of elements selected from the following list of elements: Al, Mg. Zr, Nb. Si, P. Mo, Ba, Sr, Ca, Zn, Cr, V, and Ti.

4. The method of any one of claims 1 -3, wherein Tl is lower than 1000 °C.

5. The method of any one of claims 1-4, wherein the surface area of the pristine singlecrystal cathode materials decreases by at least 25% after the refiring.

6. The method of any one of claims 1 -5, wherein T2 is greater than 300 °C and lower than 700 °C.

7. The method of any one of claims 1-6, wherein the lithium residuals on the pristine single-crystal cathode materials decrease by at least 50% after the refiring.

8. The method of any one of claims 1-7, where lithium compounds are added to the pristine cathode materials prior to the refiring.

9. The method of claim 8, where lithium compounds are in the forms of, but not limited to, lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxide, and combination thereof.

10. The method of claim 8, where the amount of lithium compounds added are ranging from 0 mol% to 10 mol% of the pristine cathode materials.

11. The method of any one of claims 1-10, wherein the one or more coating materials are nano powders with an average primary particle size smaller than 100 nm and surface area higher than 50 m2 / g.

12. The method of claim 11, wherein the one or more coating materials are compounds of Al, Zr, Ti, Mg, Nb in the forms of oxides, hydroxides, or combination thereof.

13. A dry coating method for preparing a single-crystal Li-ion battery cathode materials, the method comprising: firing a mixture of single-crystal cathode precursor materials at a temperature (TO) exceeding 700 Celsius to produce lithiated single-crystal cathode materials; cooling the single-crystal cathode materials to a temperature below 100 degrees Celsius; refiring the single-crystal cathode materials at a temperature (Tl) exceeding 700 degrees Celsius to produce refired single-cry stal cathode materials; coating the refired single-cry stal cathode materials with one or more coating materials in an all-dry- process free of solvents: and reheating the coated single-crystal cathode materials at mild temperatures (T2) to affix the one or more coating materials to the surfaces of the single-crystal cathode material.

14. The method of Claim 13, additional comprising milling the single-crystal cathode materials after the firing at (TO) and before the refiring (Tl).

15. The method of Claims 13 or 14, additional comprising milling the single-crystal cathode materials after the refiring at (Tl) and before the coating step.

16. The method of any one of Claim 13-15, wherein the mild temperatures (T2) are greater than 300 °C and lower than 700 °C.

17. The method of any one of Claim 13-16, wherein the single-crystal cathode precursor materials comprise NiO, CO3O4, M113O4, and Li2COs.

18. The method of Claim 17, wherein the NiO, CO3O4, MnsO4. and Li2COs are mixed in a stoichiometric ratio of LiNio.6Mno.2Coo.2O2 with Li2COs in excess of at least 5%.

19. A single-crystal Li-ion battery cathode material product synthesized according to the process of Claim 1 .

20. The single-cry stal Li-ion battery- cathode material product of Claim 19, wherein: the single-crystal Li-ion battery cathode materials have a layered structure with single crystal morphologies, a D50 average particle size in the range of 500 nm - 10 pm, the general chemical formula of Lii+x[(NinMnmCoc)i-aAa]i-xO2 where:n + m + c = 1;A is one or more dopants;-0.05<x<0.1; and0 < a < 0.05.

21. The single-crystal Li-ion battery cathode material product of Claims 19 or 20, wherein the single-crystal Li-ion battery cathode material product coating is selected from a group consisting of AL Zr. Ti, Mg. and Nb.

22. A post-processing method for single-crystal Li-ion batten cathode materials, the method comprising: providing singe-crystalline cathode materials; dry mixing the singe-crystalline cathode materials with one or more coating materials in the absence of solvents; subjecting the single-crystalline cathode materials to one or more refirings at temperatures exceeding 700 degrees Celsius before or after the dry mixing.

23. The method of claim 22, wherein a first refiring is performed before the dry mixing and a second refiring is performed after the dry mixing.

Images