Recovery of graphite from LI ion batteries

Abstract

The purification process of recycled graphite for use as anode material in Li-ion batteries includes a series of leaching and heat treatment followed by washing with deionized (DI) water, and pickling. The graphite source is produced by a suitable process, such as acid leaching of black species from a battery recycle stream, where a substantial portion of the metal salts used for the cathode material are leached. Trace impurities are typically present in the graphite source, most notably alumina and residual cathode material. A series of heating (sintering) and pH-adjusted washing further purifies the graphite to a modified recycled graphite having a purity of more than 99.5% for use in a recycled battery.

Description

[0001] Statement on federally funded research and development:

[0002] This patent application was developed, in whole or in part, with the support of the United States government under contract number W911NF1920108 granted by the United States Army Research Laboratory. The government owns certain rights to this invention. Background Technology

[0003] Li-ion batteries (LIBs) have been widely used in recent decades, particularly in electric vehicles (EVs) and plug-in electric vehicles (PHEVs) that are already equipped with or directly powered by LIBs. LIBs are widely used as primary power sources in portable electronic devices, electric vehicles, and grid storage. A Li-ion battery comprises charging materials, conductive powders, and binders applied to or deposited onto a current collector, typically a flat copper or aluminum sheet. The charging materials include an anode material (typically graphite or carbon) and a cathode material comprising predetermined ratios of metal salts such as lithium, nickel, manganese, cobalt, aluminum, iron, and phosphorus, defining the so-called "battery chemistry" of the Li-ion battery cell. Preferred battery chemistry varies depending on the supplier and application, and the recyclability of Li-ion batteries typically adheres to the molar ratios of the battery chemistry specified in the recycled charging material product. The purity of the product is highly correlated with the quality and performance of the recycled battery cell and typically depends on so-called "battery-grade" materials, meaning a purity of at least 99.5%. Summary of the Invention

[0004] The purification process for recycled graphite used as an anode material in Li-ion batteries involves a series of leaching and heat treatments, followed by washing with deionized (DI) water and acid washing. The graphite source is produced by suitable processes, such as acid leaching of black material from the battery recycling stream, where a significant portion of the metal salts used for cathode material is removed. Trace impurities are typically present in the graphite source, most notably alumina and residual cathode material. A series of heating (sintering) and pH-adjusted washings further purify the graphite to modified recycled graphite with a purity exceeding 99.5% for use in recycle batteries.

[0005] This configuration is partly based on the observation that the increasing prevalence of electric and hybrid vehicles (EVs / HVs) generates a large volume of spent Li-ion batteries, including charging materials such as NMC (Ni, Mn, Co) cathode materials and anode materials (including graphite and similar carbon forms). The recycling process for NMC charging materials involves leaching spent NMC charging materials, typically using controlled (raw) feedstocks of Ni, Mn, and Co salts to achieve a predetermined ratio of charging material metals according to technical or customer specifications. Graphite from spent Li-ion batteries can also be recycled. Unfortunately, the conventional approach to recycling anode materials from NMC source recycling streams suffers from the following drawbacks: the recovered graphite particles contain impurities, most notably alumina, which remain as residue after the shredding and leaching processes. When significant amounts of impurities remain in the recycled graphite product, meeting customer specifications for performance and physical anode material properties can be problematic. Therefore, this configuration essentially overcomes the drawbacks of conventional battery recycling by producing anode materials containing graphite with improved purity (equivalent to or greater than 99.5% and close to 99.9%).

[0006] More specifically, the disclosed method for recycling graphite from Li-ion batteries receives initial recycled graphite from the recycling stream of a disassembled Li-ion battery, which includes anode material, and washes the anode material in an acidic washing solution to remove residual charging material metals. A heat treatment sintersects the anode material with NaOH to form sintered graphite, which is then combined with a tetrahydrofuran (THF) solution to form reduced graphite. The reduced graphite is combined with a final washing solution to achieve a pH between 6 and 8 (approximately 7) to form modified recycled graphite configured for use as an anode material in a recycled battery. Attached Figure Description

[0007] The above and other objects, features, and advantages of the present invention will become clear from the following description of specific embodiments of the invention as illustrated in the accompanying drawings, in which the same reference numerals refer to the same parts throughout different views. These drawings are not necessarily to scale, but rather focus on illustrating the principles of the invention.

[0008] Figure 1 This is a before-and-after diagram applicable to the recycling environment used with the configuration described in this article;

[0009] Figure 2 Show Figure 1 Graphite recycling components in a Li ion recycling environment;

[0010] Figure 3 Show Figure 2 Iterative graphite treatment in recycled components;

[0011] Figure 4 As shown Figure 1-3 The process flow of graphite recycling and surface treatment in [the context of graphite recycling].

[0012] Figures 5A-5E As shown Figure 4 Results of surface scanning and analysis of recycled graphite in the sample; and

[0013] Figures 6A-6D Shown by Figure 4 The result of the process is the surface modification of graphite. Detailed Implementation

[0014] The configuration described below illustrates an exemplary arrangement for anode material recycling. A Li-ion battery includes a cathode charging material or cathode material, and an anode charging material or anode material. The cathode material comprises a metal salt of a charging material metal (such as Ni, Mn, and Co) in a predetermined ratio. The anode material is typically formed from graphite or related forms of carbon. Traditionally, recycling efforts have focused on the charging material metals of the cathode material due to the relatively high cost of these mined materials; however, anode material recycling has recently become a trend due to the value of recycled graphite.

[0015] Figure 1 This is a before-and-after diagram applicable to the recirculation environment used with the configuration described in this article. (See reference...) Figure 1 The recycling scenario 100 begins with the deployed Li-ion battery 102, typically from an EV. The Li-ion battery 102 has a limited number of charging cycles before the ability of the charging material to accept sufficient charge decreases significantly. Furthermore, premature battery failure occurs due to vehicle malfunctions, collision damage, etc. A mass recycling stream helps supply depleted batteries, including spent battery cells and charging material 104. The batteries are discharged and agitated into granular black material through physical grinding, chopping, and pulverizing. A leaching process receives the black material, including the charging material and any associated casing and copper and aluminum current collectors. The black material, including cathode material metal salts and anode materials of carbon and graphite, is used to form a leaching solution 106 containing dissolved charging material metals. The recycling stream typically originates from Ni, Mn, and Co(NMC)Li-ion batteries and is leached with H2SO4; however, other suitable leaching agents can be used.

[0016] The leachate is then separated from the graphite-rich precipitate to harvest purified graphite, discussed further below, while the leachate follows a separate recycling branch. For integrity, the leachate contains at least Ni, Mn, and Co from the sulfate solution obtained from sulfuric acid leaching; however, other charging material metals and / or leaching acids may be used. Leachate 106 has a molar ratio of charging material metals (Ni, Mn, and Co) based on the composition of the incoming recycling stream. The molar ratio is adjusted with additional metal salts (Ni, Mn, and Co salts), such as sulfates (typically in their original or control form from the fresh material), to produce a target ratio adjustment solution 108.

[0017] A co-precipitation reaction occurs in one or more containers 110 by adjusting the pH of the leaching solution to precipitate a charging material metal (charging material) at a desired ratio produced by the adjustment. Sodium hydroxide or another strong base causes the charging material metal, such as NMC, to precipitate from the solution in a particulate form, typically as a hydroxide, which can be separated by filtration. This particulate form co-precipitated from the pH adjustment of the leaching solution is a cathode material precursor having a desired molar ratio of the target battery chemistry for a new recycleable battery. The active cathode material 114 for a recycleable Li-ion battery is formed by sintering lithium carbonate or other lithium salts in furnace 112. In an exemplary configuration, the cathode active material is LiNi. x Mn y Co z O2 is obtained through sintering Ni x Mn y Co z The cathode is synthesized from (OH)₂ and Li₂CO₃, where x, y, and z represent the molar ratios of Ni, Mn, and Co, respectively. Common chemical compositions include NMC111 (representing an equimolar composition of Ni, Mn, and Co), NMC 811, NMC 622, and NMC 532, but any suitable molar ratio can be achieved by adjusting the ratio in the leaching solution 10⁶–10⁸ and sintering. The recycled cathode material can then be incorporated back into the recycling stream as cathode material, while the following process provides the anode material for the recycled battery. Further details regarding the NMC recycling of the cathode material are disclosed in U.S. Patent No. 10,522,884, filed November 22, 2016, entitled “METHOD AND APPARATUS FORRECYCLING LITHIUM-ION BATTERIES,” which is assigned to the applicant of this application and is incorporated herein by reference in its entirety.

[0018] The remaining leached precipitate replenishes the cathode material recycling by providing a graphite source. It has been found that purifying graphite from spent lithium-ion batteries can provide anode-quality graphite material (>99.5%) for lithium-ion batteries. Purification of the graphite precipitate is achieved through subsequent heating (calcination or sintering) and acid washing processes, which remove residual trace impurities from cathode material recycling for surface recovery and modification of recycled graphite.

[0019] Figure 2 Show Figure 1 Graphite recycling components in a Li ion recycling environment. (Refer to...) Figure 1 and 2 Anode recovery begins with the remaining precipitate solids from the acid leaching of the cathode material at step 106. Typical impurities in graphite include lithium transition metal (nickel, manganese, cobalt) oxides, transition metal sulfates, and alumina. In step 202, an acid leaching method is applied to remove lithium transition metal oxides. This typically involves additional washing / leaching with a leaching agent or an acid used for recovering the cathode material (such as sulfuric acid). Due to the strong covalent bonds in Al₂O₃, neither acid nor alkaline solutions can react completely with it, as shown in step 204. Therefore, the disclosed route employs a high-temperature NaOH sintering method (Al₂O₃ + 2NaOH = 2NaAlO₂ + H₂O), which successfully purified graphite to a purity exceeding 99.9%, as described in step 206.

[0020] However, the resulting high-purity graphite (step 208) may offer suboptimal electrochemical performance, exhibiting an initial coulombic efficiency (ICE) below 80% and poor cycle retention. Analysis of the high-purity graphite (208) revealed that potential performance inhibitors were oxygen-related functional groups generated during the leaching and sintering steps. Based on these contaminants, the disclosed pathway employed ultra-low concentration LiAlH4 tetrahydrofuran solvent reduction and halide (HCl, HBr) acid leaching, as depicted in step 210. The recovered graphite then exhibited an ICE of 91%, as shown in step 212, and also demonstrated similar cycle stability to commercial graphite. Notably, the recovered graphite 212 showed significantly better rate performance than commercial graphite due to the halide anions located on the graphite surface.

[0021] The recycled graphite, which is discussed in further detail below, can then be recycled again with cathode material for battery components, as depicted in step 214, and deployed in the EV as a battery pack, battery module, and / or battery module (216) to eventually re-enter the recycling stream at 218.

[0022] Figure 3 Show Figure 2The iterative graphite treatment 300 in the recycled component. Further investigation of anode material recycling shows that the graphite precipitate 106 from the recycled stream undergoes several stages of impurity and surface treatment. From the recycled stream of the battery pack, battery module, and / or battery assembly 216, the initial graphite mixture 302 is processed as follows... Figure 1 The scalable hydrometallurgical method in the aforementioned patents is produced by black substance 220.

[0023] The mixture contains portions of diaphragm and filter paper because waste graphite is typically discarded in the recycling industry, where it is first filtered through a 120-mesh sieve to obtain recycled graphite (RG), or screened at 304. The main impurities in RG include residual transition metal oxides (NMC particles), Al₂O₃, and any remaining binders. Al₂O₃ tends to constitute a significant proportion of the impurities because it serves as a protective layer for the diaphragm to enhance stability and extend its lifespan; it may fall onto the electrode surface during the shredding process. Due to the solid-ion-covalent bonding within Al₂O₃, it presents further challenges for purification during recycling.

[0024] Considering the chemical properties of existing impurities, a two-step purification method was developed to fundamentally purify recycled graphite. First, an acid leaching method is introduced to remove residual NMC cathode particles. Thus, the charging material metal is leached from the mixed recycling stream of the pulverized Li-ion battery to form acid-leached recycled graphite (ARG), as described in step 306. As mentioned above, this can be achieved using an acid similar to the leaching agent used for cathode recovery.

[0025] Nanoscale Al2O3 particles remain distributed on the surface of the ARG, indicating that Al2O3 cannot be completely dissolved in the leaching process. Therefore, different Al2O3 removal strategies, such as aqua regia and alkaline leaching, can be attempted. However, even under stringent conditions, Al2O3 is still observed in the leaching process. Therefore, the disclosed NaOH sintering method is invoked to completely remove the Al2O3 particles. This involves sintering the ARG with NaOH and washing it with deionized water (DI) and additional NaOH to form sintered acid-leached recycled graphite (SARG), thereby removing residual alumina, as depicted in step 308. During the washing step, a diluted alkaline solution can be used first to remove residual solution from the sintered graphite (SARG) while simultaneously preventing the hydrolysis of the NaAlO2 product. Step 310 describes the synthesis of reduced recycled graphite by combining the SARG with lithium aluminum hydride (LiAlH4) and HCl (hydrochloric acid) solution to produce reduced recycled graphite. The high-purity characterization of the resulting SARG increased from 97% to over 99.9% after step 310.

[0026] This paper presents an innovative recycling process to enable recycled cathode materials to achieve superior performance compared to commercial materials. The disclosed approach is an economically viable recycling and recovery method that allows graphite to meet commercial deployment requirements. Most impurities are removed through the application of scalable acid leaching and alkali sintering methods, and the recycled graphite achieves a purity exceeding 99.9%. To overcome poor ICE (intercalation, ion exchange, and instability) issues, an improved surface reconstruction and modification method is employed. By establishing additional pathways for defect-induced Li-ion diffusion, the recovered graphite (MRG) delivers 4.35 × 10⁻⁶ ppm. -9 cm 2 The average diffusion coefficient per second is greater than 1.59*10. -9 cm 2 The MRG has a capacity more than twice that of commercial graphite (CG) at 0.5 / 1C, thanks to its recycling method. Furthermore, under rigorous commercial evaluation, the MRG exhibits a 91.5% recycled ICE in a half-cell at a current density of 0.5 / 1C, and a higher capacity of 55 / 50 mAh / g than CG. Moreover, both MRG and CG have areal capacities exceeding 3 mAh / cm². 2 The commercial NMC622 cathode was matched for full cell evaluation. Consistently, compared to CG full cells, MRG full cells achieved 7% and 22% higher rate retention at 0.5C and 1C, respectively, and doubled the lifetime with an average energy density exceeding 10%. Economic and environmental feasibility was demonstrated by combining a hydrometallurgical recycling process with a graphite recycling process.

[0027] Figure 4 The following are examples of implementations. Figure 1-3 Example use cases for graphite recycling and surface treatment. (See also...) Figure 1-4 , Figure 4 The process for surface treatment and impurity removal of initial recycled graphite 302 is shown. This includes washing the anolyte material in an acidic washing solution to remove residual charging material metal. The synthesis of acid-leached recycled graphite (ARG) from initial recycled graphite involves mixing initial recycled graphite 302 with 0.5 M H₂SO₄ acid at a solid / liquid ratio of 1:10 for 1 hour, as depicted in step 404. During filtration, the powder is first washed three times with a small amount of 0.05 M H₂SO₄. The powder is then washed with deionized (DI) water until its pH reaches 7. The ARG is dried overnight in a conventional oven at 80°C.

[0028] Following acid leaching / rinsing, sintering of the anode material with NaOH forms sintered graphite. The synthesis of sintered recycled graphite (SARG) occurs in step 406, where 100 g of ARG is thoroughly mixed with 100 g of NaOH; the mixture is transferred to a graphite crucible and placed in a conventional furnace. The temperature is increased from room temperature to 400 °C at a heating rate of 2 °C per minute and maintained at 400 °C for 5 hours to determine if the sintering reaction is complete. The sintered mixture is then cooled to room temperature and stirred or pulverized into powder. The powder is mixed with 1 L of 0.1 M NaOH deionized (DI) water for 1 hour. The solution is then filtered, and the SARG is washed twice with 0.1 M NaOH, and subsequently washed with DI water until the pH is approximately 7. Finally, the SARG is dried overnight in a conventional oven at 80 °C.

[0029] The next step is the synthesis of reduced recycled graphite (RRG), which involves combining a tetrahydrofuran (THF) solution with sintered graphite to form reduced graphite, as described in step 408, and includes mixing 0.5 wt% LiAlH4 tetrahydrofuran (THF) with SARG at a solid / liquid ratio of 1:10 overnight. After filtration, the mixture is washed with a small amount of DI water and 1.5 M HCl solution to form a powder. The powder is transferred to a 1.5 M HCl solution at a solid / liquid ratio of 1:10 and left for 1 hour, followed by washing with DI water. The resulting RRG is dried overnight in a drying oven at room temperature.

[0030] Finally, modified recycled graphite (MRG) was synthesized by mixing 1M HBr and 0.5M H2SO4 solution with RRG at a solid / liquid ratio of 1:10 at 75°C for 1 hour. DI water was used during filtration until the pH reached approximately 7. This was followed by washing the reduced graphite in a final washing solution to achieve a pH between 6 and 8, forming modified recycled graphite configured for use as an anode material in a recycle battery. The MRG product yield was dried overnight in a drying oven at room temperature, as described in step 410.

[0031] Figures 5A-5E As shown Figure 4 Results of surface scanning and analysis of recycled graphite. (Refer to...) Figures 5A-5E , Figure 5A SEM images of the initial recycled graphite (RG)302 are shown, depicting the residual Al2O3. Figure 5B The image shows re-leached graphite (ARG) 404, revealing apparent nano-sized Al2O3 particles distributed on the ARG surface, indicating that Al2O3 cannot be completely dissolved during the leaching process. Figure 5C Sintered graphite (SARG) 406 is shown. Note Figure 5C Surface quality and additional magnification.

[0032] Figure 5D The XRD (x-ray diffraction) patterns of different graphite samples (including initial recycled graphite 502, ARG 504, SARG 506 and commercial graphite 501) are shown. Figure 5D The XRD patterns not only demonstrate the high purity of SARG, but also show minimal impact of the two purification steps on the graphite structure, as the peak positions shift only slightly. Impressively, the purity of graphite was increased from 97% to over 99.9%, comparable to commercial graphite levels, and both purification steps can be scaled up to hundreds of grams without affecting the purity or yield of graphite. Figure 5E Thermogravimetric analysis (TGA) of initial recycled graphite 502, ARG 504, and SARG 506 samples is shown.

[0033] Figures 6A-6D Shown by Figure 4 The result of the process is surface modification of graphite. Figure 6A In the above, the XPS (X-ray photoelectron spectroscopy) spectrum for O and the C( ) for each of CG, SARG, RRG and MRG. Figure 6B The surface and structural characterization of different graphite samples are shown. Figure 6A and 6B In the figure, the original intensity dashed line is approximated by the peak score lines 601, 603, COC 605, C=O 607, CO, C=O 608 and CC 610. Figure 6C The XRD patterns of RRG 702, MRG 708, and CG701 are shown, and Figure 6D Raman spectra of CG 701, SARG 706, RRG 702 and MRG 708 are shown.

[0034] Other use cases include the following.

[0035] Al₂O₃ dissolution experiment: 50 mg of Al₂O₃ powder was mixed with 50 ml of 2 M NaOH solution and stirred overnight at 100 °C. An exact amount of Al₂O₃ powder was mixed with 50 ml of aqua regia (0.5 M HNO₃ and 1.5 M HCl) and operated under the same conditions as another attempt. Both experiments showed that Al₂O₃ cannot be completely dissolved in acidic or alkaline solutions.

[0036] Preparation of acid-leached recycled graphite (ARG): 200 g of initial graphite was sieved using a US standard 120 mesh (125 μm) sieve. 2 L of 0.5 M H₂SO₄ was mixed with the sieved recycled graphite (RG, 197.2 g, yield 98.6%) overnight with stirring. During filtration, the powder was washed with a small amount of 0.05 M H₂SO₄, followed by washing with deionized (DI) water until the pH reached approximately 7. The ARG was dried in a conventional oven at 80 °C. Approximately 178.5 g of graphite was obtained.

[0037] Preparation of sintered acid-leached recycled graphite (SARG): 100 g of ARG (containing approximately 5.5 g of Al2O3) was thoroughly mixed with 100 g of NaOH. The mixture was transferred to a graphite crucible and placed in a conventional furnace. The temperature was raised from room temperature to 400 °C at a heating rate of 2 °C per minute. The mixture was applied at 400 °C for 1 hour. The sintered mixture was then cooled to room temperature at a cooling rate of 2 °C per minute and pulverized into powder. The powder was mixed with 1 L of 0.1 M NaOH deionized (DI) water for 1 hour. The solution was then filtered, and the SARG was washed with a small amount of 0.1 M NaOH, followed by washing with DI water until the pH reached approximately 7. Finally, the SARG was dried in a conventional oven at 80 °C, yielding approximately 90.5 g of SARG, with a yield of 95.8%.

[0038] Recrystallization of sodium salt from the washing solution: 1 L of washing solution was mixed with 2 L of ethanol under stirring for 1 hour. A white powder precipitated at the bottom of a glass beaker. The mixture was then filtered to separate the powder from the solution, washed with ethanol, and dried in a conventional oven at 80 °C. The solution was then heated at 120 °C. The evaporated liquid was collected to obtain NaOH powder.

[0039] Synthesis of Reduced Recycled Graphite (RRG): Due to reactor volume limitations, 200 mL of 0.5 wt% LiAlH4 tetrahydrofuran (THF) solution was mixed with 20 g of SARG in a glass reactor within an argon-filled (99.999%) glove box. The reactor was sealed and transferred outside. The reaction was carried out overnight at room temperature with stirring. After filtration, DI water, 0.1 M HCl solution, and ethanol were applied sequentially to remove excess LiAlH4 and byproducts. Finally, the RRG was dried in a drying oven at room temperature, yielding approximately 20.0 g of RRG.

[0040] Synthesis of modified recycled graphite (MRG): 1 M HBr and 0.5 M H₂SO₄ solutions were mixed with 100 g of RRG at a solid / liquid ratio of 1:10 at 75 °C for 5 hours. DI water was used during filtration until the pH reached approximately 7. After adjusting the concentration, the initially filtered liquid could be reused in the modification. The filtrate was recovered and reused by determining the anion concentration. The MRG was dried overnight in a drying oven at room temperature. Approximately 99.8 g of MRG was obtained.

[0041] While the systems and methods defined herein have been specifically shown and described with reference to their embodiments, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as covered by the appended claims.

Claims

1. A method for recovering graphite from a Li-ion battery, the method comprising: Initial recycled graphite is received from the recycle stream of a disassembled Li-ion battery, which includes anode material. The anode material is washed in an acidic washing solution to remove residual charging material metal; The anode material is sintered with NaOH to form sintered graphite from the anode material; The tetrahydrofuran (THF) solution was combined with the sintered graphite to form reduced graphite; as well as The reduced graphite is washed in a final washing solution to achieve a pH between 6 and 8 to form modified recycle graphite configured to be used as an anode material in a recycle battery.

2. The method as described in claim 1, wherein, The acidic washing solution further comprises a mixture of 1M HBr and 0.5M H2SO4 solution.

3. The method as described in claim 1, wherein, The final washing solution further includes: The reduced graphite was washed with DI water and HCl solution; and Maintain the solid / liquid ratio of the reduced graphite and the HCl solution at 1:10 for a predetermined duration; and The reduced graphite is washed in a mixture containing at least one of HCl, HBr and H2SO4 to produce the modified recycled graphite.

4. The method of claim 1, further comprising leaching charging material metals from a mixed recycling stream of pulverized Li-ion batteries to form acid-leached recycled graphite (ARG).

5. The method of claim 4, wherein, The recycle stream originates from Ni, Mn, and Co(NMC)Li ion batteries leached with H2SO4.

6. The method of claim 1, wherein, The modified recycled graphite has a purity of at least 99.9% and an initial coulombic efficiency of 91.5%.

7. The method of claim 1, wherein, The modified recycled graphite was characterized by a peak intensity ratio of approximately 54.8% for the D band to that for the G band (Ig). d / I g Surface defects.

8. The method of claim 1, wherein, The acidic washing solution further comprises mixing 0.5M H2SO4 with the initial recycled graphite composition containing the anode material at a solid / liquid ratio of 1:10 for about 1 hour.

9. The method of claim 1, wherein, Sintering further includes combining substantially equal masses of NaOH with the anode material after washing, and heating at 375°C-425°C based on an increase of 2°C / min, followed by application at at least 400°C for at least 5 hours.

10. The method of claim 1, wherein, The formation of the reduced graphite further includes combining 0.5 wt% THF with the sintered graphite at a solid / liquid ratio of 1:10 for 7-10 hours.

11. A method for recovering anode material from a Li-ion battery, the method comprising: Leaching of charging material metals from a mixed recycling stream of pulverized Li-ion batteries to form acid-leached recycled graphite (ARG); The ARG is sintered with NaOH and washed with deionized water (DI) and additional NaOH to form sintered acid-leached recycled graphite (SARG), thereby removing residual alumina. Reduced recycled graphite was synthesized by combining the SARG with lithium aluminum hydride (LiAlH4) and HCl solution to produce reduced recycled graphite.

12. The method of claim 11, wherein, These charging materials include metals such as Ni, Mn, and Co.

13. The method of claim 11, further comprising synthesizing the reduced recycled graphite based on the presence of halide anions on the recycled graphite.

14. A system for receiving a recycle stream from an NMC battery and recycled graphite used as a recycle anode charging material, the system comprising: A receiver for receiving initial recycled graphite from the recycle stream of a disassembled Li-ion battery, which includes anode material. The container is washed in an acidic washing solution to remove residual charging material metal; A heat source used to sinter the anode material with NaOH to form sintered graphite from the anode material; A reactor vessel used to combine a tetrahydrofuran (THF) solution with the sintered graphite to form reduced graphite; as well as The reduced graphite is washed in a final washing solution to achieve a pH between 6 and 8, forming a rinsing process for modified recycle graphite configured as an anode material in a recycle battery.

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