Efficient recycling method for cathode active material

Abstract

The present invention, in particular, relates to a method for forming recycled cathode active material from depleted cathode active material from a battery, the method comprising: forming a black mass from the depleted cathode active material (also referred to as depleted cathode active material or depleted cathode active material or depleted CAM); digesting the black mass with a carboxylic acid to form a delithiated cathode active material precursor; adding a pure lithium salt to the delithiated cathode active material precursor to form a cathode active material precursor; Calcining the cathode active material precursor to form recycled cathode active material.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to pending U.S. Provisional Application No. 63 / 407,842, filed September 19, 2022, which is incorporated herein by reference.

[0002] Technical field of the invention The present invention relates to batteries, and more particularly to recycling of battery cathode active material (also known as cathode active material, or CAM). [Background technology]

[0003] Batteries are currently ubiquitous in society as energy storage devices, and devices utilizing batteries as energy storage devices are widely used in the communications industry, such as mobile phones, the tool industry, such as yard or hand tools, the transportation industry, such as vehicles, the medical industry, such as pacemakers, and virtually any area of ​​commerce where energy storage is required.

[0004] The widespread use and adoption of batteries can put supply pressure on the raw materials used, and the inability to meet demand can drive up the costs of the materials. Increased use has also created problems associated with the disposal of used (also called depleted) batteries.

[0005] Currently, there is a global need for methods to recycle batteries, especially battery cathode active materials. The main components used in CAMs are lithium, nickel, manganese, cobalt, and aluminum, and two commercially important primary battery materials are LiMO2 or LiM2O4, where M is primarily a combination of nickel, manganese, cobalt, and aluminum with lesser amounts of other metals.

[0006] Current processes for recycling depleted (also called exhausted or spent) CAM are primarily carried out by hydrothermal digestion temperatures of at least 170°C in sealed vessels, which results in the formation of metal sulfates and lithium hydroxide. In subsequent post-processing to modify the CAM, the metal sulfates ultimately produce sodium sulfate salts, which makes the recycling process unsustainable on a commercial scale. Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide a method for forming recycled CAM from depleted CAM, where the depleted CAM is preferably from a battery.

[0008] The present invention relates to a method for forming recycled CAM from depleted CAM that allows for the recovery of metal salts in a manner that allows the metal salts to be converted into recycled CAM without forming sodium sulfate. [Effects of the Invention]

[0009] A particular feature of the present invention is the particular effectiveness (also called ability) of forming recycled CAM from depleted CAM without forming sulfates and without the need for filtration of the black mass typically formed from depleted CAM or the high temperatures and pressures associated with hydrothermal processes.

[0010] Another feature is the exceptional efficiency (ability) of forming recycled CAM from depleted CAM without loss of cathode metal.

[0011] A particular advantage of the present invention is its particular effectiveness (ability) to form recycled CAM from depleted CAM, where the recycled CAM has a different ratio of metals than the depleted CAM, thereby enabling the conversion of the depleted CAM to recycled CAM that is enriched in at least one metal compared to the depleted CAM. [Means for solving the problem]

[0012] These and other possible embodiments are provided in a process for forming a recycled cathode active material (also referred to as recycled CAM) comprising the steps of: forming a black mass from the depleted cathode active material (also referred to as depleted CAM); digesting the black mass with a carboxylic acid to form a delithiated cathode active material precursor; adding a pure (also called virgin) lithium salt to the delithiated cathode active material precursor to form the cathode active material precursor; and Calcining the cathode active material precursor to form a recycled cathode active material (referred to as recycled CAM).

[0013] Yet another embodiment is provided in a process for recycling cathode active material from a battery, the process including: removing the depleted cathode active material (referred to as depleted CAM) from the battery; forming a black mass from the depleted cathode active material; digesting the black mass with a carboxylic acid to form a cathode active material precursor (also referred to as a CAM precursor); adding virgin lithium salt to a cathode active material precursor; and Calcining the cathode active material precursor to form a recycled cathode active material. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a flow chart of the present invention.

[0015] [Figure 2] FIG. 2 is an XRD graph of the CAM precursor.

[0016] [Figure 3] FIG. 3 is a graphical representation of the particle size of the CAM precursor.

[0017] [Figure 4] Figure 4 shows the XRD pattern of the recycled CAM.

[0018] [Figure 5] Figure 5 is a graphical representation of the particle size of recycled CAM.

[0019] [Figure 6A] 6A-6C graphically illustrate the advantages of the present invention. [Figure 6B] Same as above [Figure 6C] Same as above DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention relates to a method and system for recovering metals from depleted CAM without forming sulfates, such as sodium sulfate, thereby forming recycled CAM. More specifically, the present invention relates to a method and system for recovering metals from depleted CAM suitable for use in forming recycled CAM having essentially the same stoichiometry, without adding substantial amounts of virgin metal salts.

[0021] Depleted CAM is typically recycled from batteries, although not exclusively, such that processes can be utilized for the formation of recycled CAM from CAM recovered from production streams not included in batteries. When recycled from batteries, the depleted CAM is preferably isolated from other components of the battery, such as the anode, separator, electrolyte, current collector, carbon, container, and any other components that are not part of the depleted CAM.

[0022] For purposes of the present invention, virgin CAM is CAM formed from metal salts that were not previously part of CAM. Depleted CAM is CAM that was previously in a crystalline form consistent with LiM2O4 or LiMO2, as further described herein. Black mass is formed from depleted CAM that has been removed from a battery and treated, preferably by heat, to provide a metal-rich material consistent with CAM. The CAM precursor is a metal carboxylate, where the metal is from the depleted CAM. Recycled CAM is CAM formed from metals previously utilized in depleted CAM, preferably where at least 20% by weight of the metal in the recycled CAM, more preferably at least 50% by weight, and even more preferably at least 80% by weight of the metal is formed from metals previously utilized in depleted CAM.

[0023] The present invention will be described with reference to Figure 1, which is represented by a flowchart. In Figure 1, at least one battery (also referred to as a cell) and preferably a plurality of batteries, wherein at least one battery, preferably all batteries, contains depleted CAM, are collected (10). The batteries are separated (12) into non-compliant batteries (16) that contain cathode material that does not contain LiMO2 or LiM2O4 or that contains an amount of depleted CAM that is insufficient for recycling, and compliant batteries (14) that have depleted CAM that contains LiMO2 or LiM2O4. The non-compliant batteries are separated (18) from the process stream for separate treatment, the nature of which is not limited by the present invention. The compliant battery is preferably discharged and then disassembled (20), where the battery cell containing the depleted CAM is physically separated from other components of the battery cell, such as the casing, shell, connection tabs, and electronic components such as battery management elements, foil, and shielding, resulting in a separated battery cell (22) and a waste stream (24). The waste stream, the nature of which is not limited to this invention, is removed from the process stream for separation (26). The battery cell includes at least the depleted CAM, anode, dielectric, and enclosure. The battery cell is preferably cut or diced (28) in a manner sufficient to maintain safety. Without limitation, the battery cell may be shredded or diced in a non-volatile liquid such as water or in an atmosphere that discourages combustion to protect against the unlikely event of energy discharge. The depleted CAM can be partially isolated by ultrasonic flow (30). Graphite from the anode, silicon from the cathode material, and any other components can be removed by flotation or filtration (32). The fluoride, residual carbon and binder can be burned off in (34), resulting in the isolation of a black mass (36), which contains large amounts of the components of CAM, particularly lithium, nickel, manganese, cobalt or aluminum.The depleted CAM is heated to remove volatile components; therefore, some changes in chemical structure may occur during the heating process, and the lattice may be at least partially altered compared to the depleted CAM; the black mass is converted to a CAM precursor (38), as further described herein, and calcined (40), as further described herein, to form recycled CAM.

[0024] In the method of the present invention, the black mass is directly digested with a carboxylic acid, preferably a polycarboxylic acid, more preferably a dicarboxylic acid, and most preferably oxalic acid, to produce a metal carboxylate. In one embodiment of the present invention, the black mass can be pulverized before being digested with the carboxylic acid. A particular feature of the present invention is that recycled CAM can be formed from depleted CAM at atmospheric pressure or at temperatures below 100°C under atmospheric pressure. For purposes of the present invention, ambient or atmospheric pressure is defined as having the pressure of the local environment without any auxiliary pressure increase or decrease. The method of the present invention eliminates the need for hydrothermal processes, which typically require heating to at least about 170°C in a closed vessel where pressure increases dramatically.

[0025] In a preferred embodiment, the depleted CAM is converted to recycled CAM comprising a lithium metal compound in a spinel crystal structure defined by Formula I: LiNi x Mn y X z E w O4 Formula I (where E is an optional dopant; x+y+z+w = 2 and w ≦ 0.2); or In a preferred embodiment, the depleted CAM is converted to recycled CAM comprising a lithium metal compound in a rock salt crystal structure defined by Formula II: LiNi a Mn b X c GdO2 formula II (where G is an optional dopant; X is Co or Al; and a+b+c+d = 1, and d ≤ 0. 1).

[0026] In a preferred embodiment, the spinel crystal structure of Formula I has 0.4≦x≦0.6; 1.4≦y≦1.6, and z≦0.9. More preferably, 0.5≦x≦0.55, 1.45≦y≦1.5, and z≦0.05. In a preferred embodiment, neither x nor y is zero. In Formula I, the Mn / Ni ratio is preferably 4 or less, more preferably at least 2.33 to 3.4, and most preferably at least 2.7 to 3.4.

[0027] In a preferred embodiment, the rock salt crystal structure of Formula II is a high-nickel NMC where 0.5≦a≦0.9, more preferably 0.58≦a≦0.62 as represented by NMC 622 or 0.78≦a≦0.82 as represented by NMC 811. In a preferred embodiment, a=b=c as represented by NMC 111. The term NMCxxx is a shorthand used in the art to represent the nominal relative ratios of nickel, manganese, and cobalt. NMC 811 is, for example, LiNi 0.8 Mn 0.1 X 0.1 Represents O2.

[0028] In one embodiment of the present invention, the black mass is digested with a carboxylic acid, preferably in the presence of an acid, most preferably nitric acid, to form a CAM precursor comprising a mixture of metal salts according to the following formula, using oxalate (OX) as a representative carboxylic acid: Li u Ni x Mn y X z E w O4+ OX → uLi + + xNiOX + yMnOX + zXOX + wEOX Here, the lithium may be less than stoichiometric due to the use of at least some lithium removed during the digestion process to form the depleted CAM or delithiated CAM precursor. Lithium, preferably as lithium hydroxide or lithium carbonate, is added to the delithiated CAM precursor to restore the lithium and metal to the proper stoichiometry, followed by calcination to achieve recycled CAM, represented by the following formula: Li + xNiOX + yMnOX + zXOX + wEOX → LiNixMnyXzEwO4 where Li + At least a portion of this is from virgin lithium salts added to account for the lithium deficiency.

[0029] In another embodiment of the present invention, the black mass is digested with a carboxylic acid, preferably in the presence of an acid, most preferably nitric acid, to form a delithiated CAM precursor comprising a mixture of metal salts according to the following formula, using oxalate (OX) as a representative carboxylic acid: Li v Ni a Mn b X c G d O2+ OX → vLi + + aNiOX + bMnOX + cXOX + dGOX Here, the lithium may be less than stoichiometric due to the use of at least some lithium removed during the digestion process to form the depleted CAM or delithiated CAM precursor. Lithium, preferably as lithium hydroxide or lithium carbonate, is added to form a stoichiometric CAM precursor, followed by calcination to achieve recycled CAM represented by the following formula: Li + + aNiOX + bMnOX + cXOX + dGOX → LiNi a Mn b X c G d O2 where Li + At least a portion of this is from virgin lithium salts added to account for the lithium deficiency.

[0030] In the formulas herein, lithium is defined as stoichiometrically charge-balanced, with the understanding that lithium is mobile between the anode and cathode. Thus, at any given time, the cathode may be relatively lithium-rich or relatively lithium-depleted. In a depleted CAM, lithium is below stoichiometric balance; upon charging, lithium may exceed stoichiometric balance. Similarly, in the formulations listed throughout this specification, the metals are expressed as charge-balanced, with the understanding that the metals may be slightly enriched or slightly depleted, as determined by elemental analysis, since it is not possible to formulate a perfectly balanced stoichiometry in practice. In the present invention, for stoichiometric expressions such as in NMC811, the stoichiometric ratio is ±1 mole % due to variations in manufacturing and elemental analysis. As a non-limiting example, NMC811 or the equivalent expression LiNi 0.8 Mn 0.1 Co 0.1 O2 is LiNi when the total molar amount of Ni, Mn and Co is 1. 0.792-0.808 Mn 0.099-0.101 Co 0.099-0.101 Intended to represent O2.

[0031] Dopants can be added to improve oxide properties such as electronic conductivity and stability. The dopants are preferably substitutional dopants added in conjunction with the primary nickel, manganese, and optionally cobalt or aluminum. The dopants preferably account for 10 mol % or less of the oxide, preferably 5 mol % or less. Preferred dopants include Al, Gd, Ti, Zr, Mg, Ca, Sr, Ba, Mg, Cr, Cr, Cu, Fe, Zn, V, Bi, Nb, and B, with Al and Gd being particularly preferred, with the understanding that Al is utilized as the dopant when Al is not the primary component represented by X in Formula I or Formula II. Dopants and coating materials can be added to the reactor as either carboxylates, carbonates, oxides, or metals, as needed to produce the desired composition.

[0032] A particular feature of the present invention is the ability to maintain metal stoichiometry throughout the recycling process. Additional metals, such as lithium niobate coatings, form metal salts throughout the recycling process, potentially as oxalates. Upon calcination to form the compound of Formula I or Formula II, the niobium forms either a niobium dopant or a lithium niobate coating, as described in U.S. Patent Application Publication No. 20210028448, which is incorporated herein by reference.

[0033] The recycled CAM is preferably formed from metal carboxylates by methods described in detail in U.S. Patents: U.S. Patent Application Publication No. 17 / 743,932, filed May 13, 2022; U.S. Patent Application Publication No. 20220064019; U.S. Patent Application Publication No. 20210359300; U.S. Patent Application Publication No. 20210028448; and U.S. Patent Application Publication No. 20190372129, each of which is incorporated herein by reference.

[0034] For purposes of this invention, a virgin metal salt is a metal salt containing a metal not previously used in CAM, or a metal salt added to a CAM precursor to alter the stoichiometry of the metals. Preferred virgin metal salts are metal hydroxides or metal carboxylates, especially metal oxalates.

[0035] An advantage of the present invention is the ability to recapture substantially all of the metals in the depleted CAM with minimal loss because there is no need to filter the metal salts prepared from the black mass. Thus, there is no need to include virgin metal salts if the recycled CAM is prepared with the same stoichiometry of metals as when forming NMC 111 from NMC 111 as the depleted CAM. If NMC 811 is formed as recycled CAM and NMC 111 as depleted CAM, the stoichiometry should be changed and virgin metals should be added to change the ratio. Metals cannot be easily removed from depleted CAM, black mass or CAM precursors, so it is preferred to add metal, preferably virgin metal, to alter the stoichiometry. As a non-limiting example, NMC 111 has the nominal formula LiNi 0.33 Mn 0.33 X 0.33 O2, and NMC 811 is nominally LiNi 0.8 Mn 0.1 X 0.1 O2. To convert depleted NMC 111 to recycled NMC 811, nickel salts must be added to the extent necessary to achieve a molar ratio of nickel to manganese or cobalt of about 8. Alternatively, if recycled NMC 111 is formed from depleted NMC 811, sufficient amounts of manganese and cobalt must be added to equal the molar ratio of nickel. One skilled in the art can readily determine the amounts of metals necessary to adjust the stoichiometry as needed.

[0036] For purposes of this invention, a virgin lithium salt is a lithium salt that is added to a CAM precursor formed from black mass or to a metal carboxylate slurry before drying to achieve the proper stoichiometric ratio of lithium to metal before calcination to form recycled CAM. Preferred virgin lithium salts are lithium hydroxide or lithium carbonate.

[0037] The stoichiometry of lithium must be determined as understood and is well within the ability of one skilled in the art. The moles of lithium relative to the metal will vary, as the state of charge of CAM utilized as depleted CAM can change dramatically. Additionally, lithium may be lost in the process of separating the depleted CAM from other battery components, such as the carbon, electrolyte, collector, separator, etc. Therefore, the lithium concentration is determined after digestion, and sufficient virgin lithium is added to balance the stoichiometry before drying and calcination.

[0038] After forming the recycled CAM, it is preferable to form a battery that includes the recycled CAM as the cathode active material. Formation of a battery that includes recycled CAM is no different from the process that utilizes virgin CAM. Accordingly, further details regarding the process for forming the battery will be readily understood by those skilled in the art. [Example]

[0039] Fully lithiated niobium-coated NMC811 CAM, representing the black mass formed from depleted CAM independent of the battery (separated), was added to a solution of oxalic acid and water in a 500 mL three-neck round-bottom flask equipped with a condenser. The flask was placed in a heating mantle, and the temperature was maintained at 95°C on a stir plate. The molar ratio of depleted CAM to oxalic acid was 1.00:1.02, corresponding to a 0.5 mol% excess of oxalic acid, and the solids content was approximately 58%. The reaction was allowed to proceed for 25 hours. The slurry was then mixed for 1 hour and spray-dried to yield a CAM precursor with a Li / Ni / Mn / Co ratio consistent with NMC811. The CAM precursor was calcined at 837°C for 15 hours to yield recycled CAM.

[0040] The stoichiometry and concentrations of Li, Ni, Mn, Co, and Nb were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). The crystalline structure of the material was characterized by X-ray diffraction (XRD) using a Cu Kα radiation source. The overall appearance of the sample was characterized by scanning electron microscopy (SEM). High-angle annular dark-field (HAADF) scanning transition electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDX) were used to investigate the localization of niobium in the recycled CAM.

[0041] To fabricate the cathode, recycled CAM was mixed with carbon black and PVDF (90:7:3) in n-methyl-2-pyrrolidone (NMP) to form a slurry. The slurry was coated onto carbon-coated Al foil and dried overnight in a vacuum oven at 80°C to obtain an electrode. The electrode was calendered and punched into small pieces with a diameter of 1.4 cm. A coin-shaped half cell measuring 2023 mm was assembled in a glove box filled with high-purity argon using Li metal as the anode and polypropylene (PP) as the separator. The electrolyte solution was 1M LiPF6 in ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / dimethyl carbonate (DMC), where EC / EMC / DMC were mixed with 1% vinylene carbonate in a 1:1:1 volume ratio. The mass loading of recycled CAM in the electrode was approximately 4-5 mg / cm. 2Electrochemical measurements were carried out at 25°C and between 2.8 and 4.3 V.

[0042] Figure 2 shows the XRD pattern of the CAM precursor. The peaks can be indexed to monoclinic lithium oxalate and monoclinic α-Ni dihydrate oxalate structures. ICP analysis of the CAM precursor showed a molar ratio of Ni, Mn, and Co of 8:1:1, indicating no loss of transition metals and an acceptable proportion of metal ions in the precursor. The lithium:transition metal ratio was shown to be approximately 1.06:1.00, which is slightly higher than the 1.03:1.00 NMC811 CAM starting material; therefore, no lithium salt addition was required to achieve stoichiometric balance. Niobium was shown to be approximately 0.52 wt%.

[0043] The particles were confirmed by SEM to be spherical with a particle size D50 value of 10.6 μm, as shown in the particle size graphical representation in Figure 3. The tap density of the CAM precursor was determined to be 0.52 g / ml. The CAM precursor was calcined at 837°C for 15 hours, after which the resulting recycled CAM was analyzed.

[0044] After calcination, the composition of the recycled CAM was determined to have a nominal lithium content of 1.05 moles per mole of Ni / Mn / Co combination, with a Ni / Mn / Co ratio of 0.80 / 0.10 / 0.10. The XRD pattern of the recycled CAM is shown in Figure 4. [ka] The space group was indexed to a hexagonal structure. Single-phase crystals with no unidentified / impurity peaks from the process were detected, confirming the successful recycling of depleted NMC811 CAM to NMC811 CAM.

[0045] Table 1 shows the R values ​​and lattice parameters of the recycled CAM. The R values, often used as an indicator of cation mixing in NMC cathode materials, are higher than 1.2, indicating the minimum and desired amount of cation mixing. The a and c lattice parameters are 2.87 Å and 14.20 Å, respectively. (Table 1) XRD parameters of recycled NMC811 [Table 1] material: material recycled: ideal: ideal

[0046] The particle size distribution of the recycled NMC811 CAM is shown in Figure 5. SEM showed that the spherical particle morphology was restored.

[0047] To verify the presence of niobium as a coating layer on the surface of each primary particle of recycled NMC811, samples were cross-sectioned and analyzed by scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDX). The results showed a thin niobium coating layer on the surface and edges of the particles, as well as niobium doping within the particles.

[0048] To characterize the electrochemical performance of the recycled NMC811 material, half-molded 2032-size coin cells were fabricated. Figures 6A-6C graphically show the electrochemical performance, specific discharge capacity, and capacity retention versus cycle number and rate capability of the input and recycled NMC811 materials. As can be seen from Figures 6A-6C, the recycled NMC811 exhibits higher discharge capacity compared to the input NMC811, but the capacity retention is lacking. The recycled sample also exhibits good rate capability with good rebalance after undergoing harsh conditions (5C and 10C). Table 2 summarizes the electrochemical performance of the recycled NMC compared to the input NMC811 conditioned at C / 20 mAh / g, C / 20 Columbia efficiency (CE), C / 10 (mAh / g), and 1C / 10 Columbia efficiency (CE). Table 2: Summary of electrochemical performance of pristine (input) and recycled NMC811. [Table 2] Material: Material Capacity Retention: Capacity retention Input: Recycled:

[0049] The results demonstrate the effective formation of recycled CAM at temperatures below 100°C under atmospheric pressure. The recycling process of the present invention offers the possibility of recycling depleted CAM without the need for complex separation processes, particularly high temperatures, high pressures, and filtration of the black mass. The black mass formed as isolated depleted CAM can be converted to a carboxylate, preferably an oxalate, which serves as a CAM precursor for the formation of recycled CAM. X-ray diffraction and inductively coupled plasma optical emission spectroscopy confirm the excellent purity of the recycled CAM. The recycled CAM exhibits industrially desirable spherical particle shape. Furthermore, the electrochemical performance of a coin half-battery containing recycled CAM showed a specific discharge capacity of 217.7 mAh / g at the first C / 10 cycle. The method of the present invention can provide a scalable alternative to existing recycling processes.

[0050] While the present invention has been described with reference to preferred embodiments, it is not limited thereto, and those skilled in the art will recognize additional embodiments that are set forth and described in the claims appended hereto.

Claims

1. A method of forming a recycled cathode active material comprising: forming a black mass from the depleted cathode active material (also referred to as depleted cathode active material or depleted cathode active material or depleted CAM); digesting the black mass with a carboxylic acid to form a delithiated cathode active material precursor (also referred to as a delithiated cathode active material precursor or a delithiated CAM precursor); adding virgin lithium salt to the delithiated cathode active material precursor to form a cathode active material precursor (also referred to as a CAM precursor); Calcining the cathode active material precursor to form a recycled cathode active material (also referred to as recycled cathode active material or recycled CAM).

2. 2. The method of forming a recycled cathode active material of claim 1, wherein the depleted cathode active material is defined by Formula I or Formula II: Li u Ni x Mn y Co z E w O 4 (Formula 1) wherein in Formula I: E is an optional dopant; x+y+z+w = 2; w ≦ 0.2; and u ≦ 1); Or, Li v Ni a Mn b X c G d O 2 (Formula II) (wherein in Formula II: G is an optional dopant; X is Co or Al; a+b+c+d = 1; v ≦ 1; and d ≦ 0.1).

3. 3. The method of forming a recycled cathode active material of claim 2, wherein in Formula I, 0.4 ≦ x ≦ 0.6； 1.4 ≦ y ≦ 1.6; and z ≦ 0.9。

4. 4. The method of forming a recycled cathode active material of claim 3, wherein in Formula I, 0.5 ≦ x ≦ 0.55； 1.45 ≦ y ≦ 1.5; and z ≦ 0.05。

5. 3. The method of forming a recycled cathode active material of claim 2, wherein in Formula I, neither x nor y is zero.

6. 3. The method for forming a recycled cathode active material of claim 2, wherein said formula I has a Mn / Ni ratio of 4 or less.

7. 7. The method for forming a recycled cathode active material according to claim 6, wherein the Mn / Ni ratio is at least 2.33 and not more than 3.

4.

8. 8. The method for forming a recycled cathode active material according to claim 7, wherein the Mn / Ni ratio is at least 2.7 to 3.

4.

9. 3. The method for forming a recycled cathode active material according to claim 2, wherein in Formula II, 0.5≦a≦0.

9.

10. 10. The method for forming a recycled cathode active material of claim 9, wherein in Formula II, 0.58≦a≦0.

62.

11. 10. The method for forming a recycled cathode active material of claim 9, wherein in Formula II, 0.78≦a≦0.

82.

12. 3. The method of forming a recycled cathode active material of claim 2, wherein E or G is selected from the group consisting of Al, Gd, Ti, Zr, Mg, Ca, Sr, Ba, Mg, Cr, Cu, Fe, Zn, V, Bi, Nb, and B.

13. 13. The method of forming a recycled cathode active material of claim 12, wherein E or G is selected from the group consisting of Al and Gd.

14. 2. The method of forming a recycled cathode active material of claim 1, wherein the recycled cathode active material is defined by Formula I or Formula II: LiNi x Mn y Co z E w O 4 (Formula I) wherein in Formula I: E is an optional dopant; x+y+z+w = 2; and w ≦ 0.2); Or, LiNi a Mn b X c G d O 2 (Formula II) wherein in Formula II: G is an optional dopant; X is Co or Al; and where: a+b+c+d = 1; and d ≦ 0. 1).

15. 15. The method of forming a recycled cathode active material of claim 14, wherein in Formula I: 0.4 ≦ x ≦ 0.6； 1.4 ≦ y ≦ 1.6; and z ≦ 0.9。

16. 16. The method of forming a recycled cathode active material of claim 15, wherein in Formula I: 0.5 ≦ x ≦ 0.55； 1.45 ≦ y ≦ 1.5; and z ≦ 0.05。

17. 15. The method of forming a recycled cathode active material of claim 14, wherein in Formula I, neither x nor y is zero.

18. 15. The method for forming a recycled cathode active material according to claim 14, wherein in formula I, the Mn / Ni ratio is 4 or less.

19. 19. The method of forming a recycled cathode active material according to claim 18, wherein the Mn / Ni ratio is at least 2.33 and not more than 3.

4.

20. 20. The method of claim 19, wherein the Mn / Ni ratio is at least 2.7 to less than 3.

4.

21. 15. The method for forming a recycled cathode active material of claim 14, wherein in Formula II, 0.5≦a≦0.

9.

22. 22. The method for forming a recycled cathode active material of claim 21, wherein in Formula II, 0.58≦a≦0.

62.

23. 22. The method for forming a recycled cathode active material of claim 21, wherein in Formula II, 0.78≦a≦0.

82.

24. 15. The method of forming a recycled cathode active material of claim 14, wherein E or G is selected from the group consisting of Al, Gd, Ti, Zr, Mg, Ca, Sr, Ba, Mg, Cr, Cu, Fe, Zn, V, Bi, Nb, and B.

25. 25. The method of forming a recycled cathode active material of claim 24, wherein E or G is selected from the group consisting of Al and Gd.

26. 10. The method of forming a recycled cathode active material of claim 1, wherein the depleted cathode active material and the recycled cathode active material have the same molar ratio of Ni, Mn, Co, and Al.

27. 10. The method of forming a recycled cathode active material of claim 1, wherein the depleted cathode active material and the recycled cathode active material do not have the same molar ratios of Ni, Mn, Co, and Al.

28. 30. The method of forming a recycled cathode active material of claim 27, further comprising adding a virgin metal salt prior to said drying.

29. 30. The method of forming a recycled cathode active material of claim 28, wherein the virgin metal salt is a metal hydroxide or a metal carboxylate.

30. 30. The method of forming a recycled cathode active material of claim 29, wherein the virgin metal salt is a metal oxalate.

31. 10. The method of forming a recycled cathode active material of claim 1, wherein the carboxylic acid is a multicarboxylic acid.

32. 32. The method of forming a recycled cathode active material of claim 31 , wherein the carboxylic acid is a dicarboxylic acid.

33. 10. The method of forming a recycled cathode active material of claim 1, wherein the carboxylic acid is selected from the group consisting of oxalic acid, acetic acid, and malic acid.

34. 34. The method of forming a recycled cathode active material of claim 33, wherein the carboxylic acid is oxalic acid.

35. 10. The method of forming a recycled cathode active material of claim 1, wherein the virgin lithium salt is selected from the group consisting of lithium hydroxide and lithium carbonate.

36. 10. The method of claim 1, wherein the digestion is carried out at a temperature of 100°C or less.

37. 10. The method of forming a recycled cathode active material of claim 1, wherein the digestion is carried out at ambient pressure.

38. 10. A method for forming a battery, comprising forming the recycled cathode active material of claim 1, followed by forming an anode, a separator, an electrolyte, and connectivity (also referred to as connecting elements).

39. 1. A method for recycling cathode active material from a battery, comprising: removing depleted cathode active material from the battery; forming a black mass from the depleted cathode active material; digesting the black mass with a carboxylic acid to form a cathode active material precursor; adding a virgin lithium salt to the cathode active material precursor; and calcining the cathode active material precursor to form a recycled cathode active material.

40. 40. The method for recycling cathode active material from a battery of claim 39, wherein the cathode active material is defined by Formula I or Formula II: LiNi x Mn y Co z E w O 4 Formula I where E is an optional dopant; and x+y+z+w = 2, w ≤ 0. 2); or LiNi a Mn b X c G d O 2 Formula II where G is an optional dopant; X is Co or Al; and a+b+c+d = 1 and d ≦ 0.

1.

41. 41. The method for recycling cathode active material from a battery of claim 40, wherein in Formula I: 0.5 ≦ x ≦ 0.6； 1.4 ≦ y ≦ 1.5； and z≦0.

9.

42. 42. The method for recycling cathode active material from a battery of claim 41, wherein in Formula I: 0.5 ≦ x ≦ 0.55； 1.45 ≦ y ≦ 1.5; and z ≦ 0.

05.

43. 41. The method for recycling cathode active material from a battery of claim 40, wherein in formula I, neither x nor y is zero.

44. 41. The method for recycling cathode active material from a battery according to claim 40, wherein in formula I, the Mn / Ni ratio is 3 or less.

45. 45. The method for recycling cathode active material from a battery according to claim 44, wherein the Mn / Ni ratio is at least 2.33 and less than 3.

46. 46. ​​The method for recycling cathode active material from a battery according to claim 45, wherein the Mn / Ni ratio is at least 2.6 to less than 3.

47. 41. The method for recycling cathode active material from a battery according to claim 40, wherein in Formula II, 0.5≦a≦0.

9.

48. 48. The method for recycling cathode active material from a battery according to claim 47, wherein in Formula II, 0.58≦a≦0.

62.

49. 48. The method for recycling cathode active material from a battery according to claim 47, wherein in Formula II, 0.78≦a≦0.

82.

50. 41. The method for recycling cathode active material from a battery of claim 40, wherein E or G is selected from the group consisting of Al, Gd, Ti, Zr, Mg, Ca, Sr, Ba, Mg, Cr, Cu, Fe, Zn, V, Bi, Nb, and B.

51. 51. The method for recycling cathode active material from a battery of claim 50, wherein E or G is selected from the group consisting of Al and Gd.

52. 40. The method for recycling cathode active material from a battery of claim 39, wherein the recycled cathode active material is defined by Formula I or Formula II: LiNi x Mn y Co z E w O 4 Formula I (wherein E is an optional dopant; x+y+z+w=2, with w≦0.2); or LiNi a Mn b X c G d O 2 Formula II where G is an optional dopant; X is Co or Al; and where a+b+c+d = 1 and d ≤ 0.1).

53. 53. The method for recycling cathode active material from a battery of claim 52, wherein in Formula I: 0.5 ≦ x ≦ 0.6； 1.4 ≦ y ≦ 1.5; and z≦0.9。

54. 54. The method for recycling cathode active material from a battery of claim 53, wherein in Formula I: 0.5 ≦ x ≦ 0.55； 1.45 ≦ y ≦ 1.5; and z≦0.05。

55. 53. The method for recycling cathode active material from a battery according to claim 52, wherein in formula I, neither x nor y is zero.

56. 53. The method for recycling cathode active material from a battery according to claim 52, wherein in formula I, the Mn / Ni ratio is 3 or less.

57. 57. The method for recycling cathode active material from a battery according to claim 56, wherein the Mn / Ni ratio is at least 2.33 and less than 3.

58. 58. The method for recycling cathode active material from a battery according to claim 57, wherein the Mn / Ni ratio is at least 2.6 to less than 3.

59. 53. The method for recycling cathode active material from a battery according to claim 52, wherein in Formula II, 0.5≦a≦0.

9.

60. 60. The method for recycling cathode active material from a battery according to claim 59, wherein in Formula II, 0.58≦a≦0.

62.

61. 60. The method for recycling cathode active material from a battery according to claim 59, wherein in Formula II, 0.78≦a≦0.

82.

62. 53. The method for recycling cathode active material from a battery according to claim 52, wherein E or G is selected from the group consisting of Al, Gd, Ti, Zr, Mg, Ca, Sr, Ba, Mg, Cr, Cu, Fe, Zn, V, Bi, Nb, and B.

63. 63. The method for recycling cathode active material from a battery of claim 62, wherein E or G is selected from the group consisting of Al and Gd.

64. 40. The method for recycling cathode active material from a battery of claim 39, wherein the cathode active material and the recycled cathode active material have the same stoichiometry.

65. 40. The method for recycling cathode active material from a battery of claim 39, wherein the cathode active material and the recycled cathode active material do not have the same stoichiometry.

66. 66. The method for recycling cathode active material from a battery according to claim 65, further comprising adding a virgin metal salt prior to said drying.

67. 67. The method for recycling cathode active material from a battery according to claim 66, wherein the virgin metal salt is a metal hydroxide or a metal carboxylate.

68. 67. The method for recycling cathode active material from a battery according to claim 66, wherein the virgin metal salt is a metal oxalate.

69. 40. The method for recycling cathode active material from a battery according to claim 39, wherein the carboxylic acid is a polycarboxylic acid.

70. 70. The method for recycling cathode active material from a battery according to claim 69, wherein the carboxylic acid is a dicarboxylic acid.

71. 40. The method for recycling cathode active material from a battery according to claim 39, wherein the carboxylic acid is selected from the group consisting of oxalic acid, acetic acid, and malic acid.

72. 72. The method for recycling cathode active material from a battery according to claim 71, wherein the carboxylic acid is oxalic acid.

73. 40. The method for recycling cathode active material from a battery according to claim 39, wherein the virgin lithium salt is selected from the group consisting of lithium hydroxide and lithium carboxylate.

74. 40. The method for recycling cathode active material from a battery of claim 39, wherein the digestion is carried out at a temperature of 100°C or less.

75. 40. The method for recycling cathode active material from a battery of claim 39, wherein the digestion is conducted at ambient pressure.

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