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Sustainable Recycling and Regeneration of Cathode Scraps from Industrial Production of Lithium-Ion Batteries Xiaoxiao Zhang, Qing Xue, Li Li, Ersha Fan, Feng Wu, and Renjie Chen ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.6b01948 • Publication Date (Web): 10 Oct 2016 Downloaded from http://pubs.acs.org on October 16, 2016

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ACS Sustainable Chemistry & Engineering

Sustainable Recycling and Regeneration of Cathode Scraps from Industrial Production of Lithium-Ion Batteries Xiaoxiao Zhanga, Qing Xuea, Li Lia,b*, Ersha Fana, Feng Wua,b and Renjie Chena,b* a. Beijing Key Laboratory of Environmental Science and Engineering, School of Materials Science and Engineering, Beijing Institute of Technology, No.5 South Zhongguancun Street, Beijing 100081, China. b. Collaborative Innovation Center of Electric Vehicles in Beijing, No.5 South Zhongguancun Street, Beijing 100081, China. * E-mail address: [email protected]; [email protected]

ACS Paragon Plus Environment

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KEYWORDS: lithium-ion batteries, recycling, scraps, calcination, regeneration

ABSTRACT: The burst demand of lithium-ion batteries (LIBs) for energy storage leads to an increasing production of LIBs. The huge amount of electrode scraps produced during the industrial production cannot be overlooked. A sustainable and simple method was developed to regenerate Li(Ni1/3Co1/3Mn1/3)O2 electrode scraps as new cathodes for LIBs. Three different separation processes, including direct calcination, solvent dissolution and basic solution dissolution, were applied to obtain the active materials. Then, a heat treatment was used to regenerate the scraps. The effects of separation methods and heat treatment temperatures were systematically investigated. The results show that the scraps regenerated with solvent dissolution and heat treatment at 800 °C deliver the highest reversible discharge capacities of 150.2 mA h g-1 at 0.2C after 100 cycles with capacity retention of 95.1%, which is comparable with commercial Li(Ni1/3Co1/3Mn1/3)O2 cathodes. When cycled at 1C, a high reversible discharge capacity of 128.1 mA h g-1 can be obtained after 200 cycles. By contrast, scraps regenerated through direct calcination method at 600 °C exhibit the best cycling performances, with the highest capacity retention of 96.7% after 100 cycles at 0.2C and 90.5% after 200 cycles at 1C. By characterizations of XRD, SEM, XPS and particle size distribution analysis, the improved electrochemical performances of regenerated cathodes can be attributed to the uniform particle morphology and newly formed protective LiF composite. The simple and green regeneration process provides a novel perspective of recycling scraps from industrial production of LIBs.

INTRODUCTION Currently, the fast-growing market of consumer electronics, electric vehicles and stationary energy storage, has spurred a surge demand for lithium-ion battery (LIB), which is the most


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popular energy storage technology and occupies the largest market share of batteries.1-3 According to the statistics, between 2000 and 2010, the annual production of LIBs increased by 800% in the world.4 It is predicted that there will be a huge growth for LIB industry with an estimated global market close to $32 billion by 2020, particularly stimulated by the burst of electric vehicles for green transportation.3, 5 Accordingly, the quantity and weight of spent LIBs in 2020 will surpass 25 billion units and 500 thousand tonnes, respectively.4 In view of the significant quantity, environmental preservation and valuable resources conservation, simple and green recycling processes of spent LIBs is highly desirable and has become a research hotspot around the world.6-11 Different strategies, mainly including pyrometallurgical 12-15 and hydrometallurgical processes,16-20 have been investigated and developed rapidly to recycle cathode materials with higher economic values. Our previous research focused on the green hydrometallurgical recycling of spent cathode materials with organic acids, and satisfied leaching efficiencies of valuable metals were obtained.21-24 Apart from spent end-of-life LIBs, the large amount of electrode scraps generated during the production process of LIBs cannot be neglected as well. However, few related reports are focused on this subject.25-26 Compared with spent LIBs, electrode scraps have their own characteristics. For example, the scraps have not been assembled into cells, thus they are not in contact with electrolyte and not subject to charge/discharge tests. Consequently, the active materials in electrode scraps remain in complete structure. These features make us think of simple and green methods to regenerate scraps as new electrode materials for LIBs, saving the complex acid leaching and purification steps of traditional recycling processes, and realizing a closed loop recycling of scraps. The emphasis of regenerating electrode scraps is on the separation of active materials from current collectors and the following regeneration treatment.


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In this study, commercial Li(Ni1/3Co1/3Mn1/3)O2 (NCM) cathode scraps from industrial production of LIBs were regenerated as an example. The electrochemical performances of commercial NCM powders were tested for comparison. Three different separation methods, including direct calcination, solvent dissolution and basic solution dissolution have been investigated to obtain the active materials. Then a simple and green heat treatment was applied to regenerate NCM scraps as new electrode materials for LIBs. The effects of separation method and heat treatment temperature on the electrochemical performances of NCM cathode were systematically studied. Under the optimal treatment conditions, the regenerated materials show satisfied electrochemical performances comparable with commercial NCM cathode for LIBs. The whole regeneration process is sustainable, simple and commercially viable. EXPERIMENTAL SECTION Recycling and regeneration. Li(Ni1/3Co1/3Mn1/3)O2 cathode scraps (obtained from CITIC GUOAN MGL Co., Ltd.) were cut into 2 cm2 size pieces, then three different treatment methods were conducted to regenerate the cathode scraps. (1) Direct calcination: 50 g cathode scraps were directly calcined at 300 °C, 400 °C, 500 °C, 600 °C and 700 °C for 5 h in a muffle furnace, respectively. Then at certain temperatures the electrode scraps can be peeled off easily from Al foils, and regenerated as new cathode materials for LIBs. The scraps calcined at different temperatures were labelled as DC-300, DC-400, DC-500, DC-600 and DC-700. (2) NMP solvent dissolution: 50 g cathode scraps were first immersed in N-methyl-2pyrrolidone (NMP) solvent to dissolve PVDF binder. After 1 h immersion under ultrasound, the scraps peeled off from Al foils, and were separated from NMP solvent by centrifugation. The separated NMP solvent can be recycled and reused for several times.


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After drying at 80 °C for 24 h, the scraps were heat treated at 200~900 °C for 5 h to regenerate as new cathode materials for LIBs and labelled as SD-200, SD-300, SD-400, SD-500, SD-600, SD-700, SD-800 and SD-900. The pristine sample without heat treatment was labelled as SD-UH. (3) Basic solution dissolution: 50 g cathode scraps were first immersed in 2 M NaOH basic solution to dissolve Al foils. The solution was stirred for 1 h until all the Al foils were dissolved. Then the scraps were collected after filtration and washed for several times to remove residual Al3+. After drying at 80 °C for 24 h, the scraps were heat treated at 200~900 °C for 5 h to regenerate as new cathode materials for LIBs and labelled as BD200, BD-300, BD-400, BD-500, BD-600, BD-700, BD-800 and BD-900. The pristine sample without heat treatment was labelled as BD-UH. For comparison, commercial NCM sample (labelled as CS) were purchased from the same manufacturer and tested as cathodes for LIBs. The waste gas from heat treatment process can be collected and purified to reduce environmental pollution. Material Characterizations. The structure analysis was carried out using X-ray diffraction (XRD; Rigaku Ultima IV-185) with a Cu Kα radiation source. The source tension and current are 40 kV and 40 mA, respectively. Data were acquired with a speed of 8° min−1 over a 2θ range of 10°−80°. Morphologies of the samples were characterized by a field emission scanning electron microscope (FESEM, FEI, Quanta 200f). X-ray photoelectron spectroscopy (XPS, PHI Quantera) was used to detect the surface elements of the materials. The data of thermal gravimetric analysis (TGA) were collected with a TG-DTA 6200 LAB SYS instrument at a scan rate of 5 °C minute-1, and the temperature range is from room temperature to 900 °C under air atmosphere. Particle size distributions were measured with a laser particle size analyzer (OMEC, LS-POP(9)).


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Electrochemical Tests. For fabrication of the cathodes, the regenerated electrodes were mixed with acetylene black (AB) and polyvinylidene fluoride (PVDF) (8:1:1 by weight) in NMP. The obtained slurry was coated onto Al foil and roll-pressed. The electrodes were dried overnight at 80 °C in a vacuum oven, and assembled into 2025 coin-cells in a glove box filled with highpurity argon using Li metal as anode and Celgard 2400 membrane as separator. The electrolyte solution was 1 M LiPF6 in ethyl carbonate (EC) and dimethyl carbonate (DMC) (1:1 by volume). The loading mass of active material in the samples is ~3.5−4 mg cm-2. The electrochemical measurements were performed using a Land battery test system (Land CT2001A, Wuhan, China) in the voltage range of 2.8−4.3 V at different rates from 0.2C to 5C (1C=150 mA g-1). The potentials throughout the paper are referenced to the Li/Li+ couple. RESULTS AND DISCUSSION Direct calcination. The direct calcination method is based on the decomposition of PVDF binder. Then the active materials can be easily peeled off. In order to determine the accurate decomposition temperature of PVDF binder and AB conductive additives, the thermal analysis was conducted as shown in Figure S1. It can be seen that PVDF begins to decompose at ~350 °C and the decomposition completes at 600 °C, while AB starts to break down at ~650 °C. Figure 1a shows the images of pristine scraps and scraps calcined at 300 °C and 700 °C. It can be seen that the DC-300 sample shows no change compared with pristine scraps, due to the undecomposed PVDF binder. Meanwhile, the scraps calcined at 700 °C are fragile and the active materials were mixed with Al foils, which makes the separation process impossible. This phenomenon is ascribed to the melting of Al foil at high temperatures. So the practical direct calcination temperatures are set at 400, 500 and 600 °C. XRD patterns of the regenerated DC-400, DC-500 and DC-600 samples, and the photos of Al foils after separation are showed in Figure 1b. All the


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samples exhibit patterns indexed to a hexagonal layered α-NaFeO2 type structure (space group, R

3 m). The clear split of (006)/(012) and (018)/(110) peaks indicate that the layered structure is well reserved after calcination. In DC-400 and DC-500, there are some residue conductive carbons, which only decompose at higher temperature above 600 °C. From the images of Al foils after separation, it can be seen that the active materials can be peeled off almost completely, indicating a high recycling rate.

Figure 1. (a) Photos of pristine scraps and scraps after calcination at 300 °C and 700 °C; (b) XRD patterns of DC-400, DC-500, DC-600, and photos of Al foils after peeling off.


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SEM images of the DC-400, DC-500 and DC-600 samples are depicted in Figure 2. At a lower calcination temperature of 400 °C, residue carbon additives still exist in the scraps, as clearly shown in Figure 2a. By comparison, the DC-500 and DC-600 samples have a relatively regular spherical morphology and uniform particle size distribution, which can also be confirmed by the particle size distribution results in Figure 2d. The D50 values of DC-500 and DC-600 samples are nearly the same. While the DC-400 sample shows a smaller value due to the existence of small residue carbon.

Figure 2. SEM images of DC-400 (a), DC-500 (b), DC-600 (c); Particle size distribution curves of DC samples (d). In order to investigate the composition at the surface of samples, XPS analysis was conducted and the results are shown in Figure 3. In the C1s photoelectron spectra of all the samples, the peaks at 285 eV are assigned to C-H bonds from hydrocarbon contamination, and the other peak located at 284 eV is attributed to graphitic-like compounds, which correspond to conductive carbon in the electrodes.27-29 Meanwhile, as the calcination temperature increases, the relative content of conductive carbon decreases because of the decomposition of carbon at higher


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temperature. The XPS F1s core peaks of all the samples at 685 eV are assigned to LiF component, which is the product of PVDF thermal decomposition.29-31

Figure 3. XPS patterns of C1s (a) and F1s (b) elements in DC-400, DC-500 and DC-600. Electrochemical tests were conducted to investigate the performances of regenerated electrodes, and the results are shown in Figure 4. Overall, as the calcination temperature increases, better electrochemical performances can be obtained. When cycled at a low rate of 0.2C, the DC-600 sample exhibits the best discharge capacity of 145.4 mA h g-1 at 1st cycle, and maintains at 140.6 mA h g-1 after 100 cycles with the highest capacity retention of 96.7%. As the rate increases to 1C, it also delivers a high reversible discharge capacity of 121 mA h g-1 after 200 cycles with capacity retention of 90.5%. The rate performances of all the samples are shown in Figure 4c. After cycling at high rate of 5C, the discharge capacity of DC-600 sample can be recovered to 138 mA h g-1, indicating that the structure is not destroyed during high rate cycling. In order to further investigate the electrochemical reaction in the samples, the differential capacity curves of DC-600 sample and the charge/discharge profiles of all the samples at different cycles are shown in Figure 4d and 4e, respectively. The best overlap of charge/discharge curves of DC-600 means the best reversibility, and the discharge voltage peak locates at as high as 3.77 V. The excellent


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cycling performance can be attributed to the protection of LiF formed during PVDF decomposition. In contrast, DC-400 exhibits the worst electrochemical performances, mainly due to its agglomerated morphology and incomplete decomposition of PVDF.

Figure 4. Electrochemical performances of regenerated DC samples: (a,b) Cycling performances at 0.2C and 1C; (c) Rate performances at different currents; (d) dQ dV-1 plots of DC-600 at different cycles; (e) Charge/discharge profiles of DC samples at 0.2C. NMP solvent dissolution. Another separation method is to dissolve PVDF binder into NMP solvent. Then the active materials are subject to heat treatment from 200-900 °C. Based on the electrochemical performances of all the samples in the following discussion part, XRD patterns of the SD-UH, SD-300 and SD-800 samples are shown in Figure 5a, and those of other samples are shown in Figure S2. It can be seen that the residue carbons disappear when the temperature rises above 600 °C. Like DC samples, no other impurities are found in XRD analysis. From the TG result of SD-UH in Figure 5b, it can be inferred that the total contents of PVDF, carbon and other components are about 12.2%. SEM images of SD-UH, SD-200, SD-400, SD-600 and SD-800 are shown in Figure 6. Due to


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the undecomposed PVDF binder, some agglomerates are observed in the SD-UH and SD200 samples. As the temperature increases to 400 °C, PVDF begins to decompose and the morphology of the particles become more uniform, and some small particles appear because of high temperature calcination. The particle size distribution results also reveal the same trend, with similar small D50 values of SD-400, SD-600 and SD-800 samples.

Figure 5. (a) XRD patterns of SD-UH, SD-300 and SD-800; (b) TG-DSC curves of SD-UH. XPS analysis of SD-UH, SD-200 and SD-800 are shown in Figure 7. When the scraps are regenerated at 200 °C, below the decomposition temperature of PVDF (−(CF2−CH2)n−), the presence of PVDF is revealed by two equal peaks in the C1s spectra, one at 286.2 eV from the −CH2− groups and another at 290.9 eV from the −CF2− groups.28, 30, 32 Meanwhile, the main peak at 687.7 eV in the F1s spectrum corresponds to −CF2− groups from PVDF.28, 30, 32 When the temperature rises to 800 °C, the peaks corresponding to PVDF disappear and a new peak located at 685 eV in the F1s spectrum is formed, which is attributed to LiF component.30-31


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Figure 6. SEM images of SD-UH (a), SD-200 (b), SD-400 (c), SD-600 (d), SD-800 (e); Particle size distribution curves of SD samples (f).

Figure 7. XPS patterns of C1s (a) and F1s (b) elements in SD-UH, SD-200 and SD-800. Galvanostatic charge/discharge tests of the SD samples were performed between 2.8 and 4.3 V at 0.2C and 1C rates, as shown in Figure 8a and 8b. The best performance is obtained with SD800 sample, delivering the highest reversible discharge capacities of 150.2 mA h g-1 at 0.2C after


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100 cycles with capacity retention of 95.1%, which is comparable with commercial NCM cathode. Even cycled at a high rate of 1C, a reversible discharge capacity of 128.1 mA h g-1 can be obtained after 200 cycles. It can be seen that the samples calcined at higher temperatures of 600, 700, 800 and 900 °C all exhibit better performances than the pristine sample. By comparison, SD-300 only attains 99 mA h g-1 after 100 cycles at 0.2C. The charge/discharge curves and corresponding dQ dV-1 plots of SD-800 reveals its best reversibility. The improved performances after regeneration at higher calcination temperature can be attributed to the newly formed LiF protective composite, which is inactive and can protect active materials from side reaction with electrolytes. The advantages of LiF in cathode materials are also confirmed in other reports.33-35 Compared with DC-600, SD-800 contains less LiF content because more PVDF dissolves in NMP solvent. Thus, SD-800 delivers a higher discharge capacity due to the more reserved active Li ions. On the other hand, DC-600 exhibits better cycling performance with the highest capacity retention. This is also associated with LiF content. The more LiF in DC-600, the less side reaction occurs with electrolytes. Basic solution dissolution. The last way to obtain active materials is to dissolve Al foils with NaOH basic solution. So the content of PVDF in pristine BD-UH sample before calcination is higher than that in the SD sample, which can be concluded from TG analysis (Figure 9a) of BDUH sample with a mass loss of 15.6%. XRD patterns of all the samples are shown in Figure 9b and Figure S3. The residue carbon burns off when temperature rises above 600 °C, just the same as DC and SD samples. However, minor peaks of LiF and transition metal oxides (mainly NiCo2O4 or Co3O4) are observed above 600 °C, as shown in the enlarged XRD patterns at certain ranges in Figure S3.36 Meanwhile, the split of (018)/(110) peaks at high temperatures are less obvious. This can be ascribed to the more HF released from PVDF decomposition, which attacks


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NCM to form LiF and the corresponding transition metal oxides. Thus it can be speculated that the lower calcination temperature, the less destruction of layered structure and the better electrochemical performances.

Figure 8. Electrochemical performances of regenerated SD samples: (a,b) Cycling performances at 0.2C and 1C; (c) Rate performances at different currents; (d) dQ dV-1 plots of SD-800 at different cycles; (e) Charge/discharge profiles of SD samples at 0.2C.

Figure 9. (a) TG-DSC curves of BD-UH; (b) XRD patterns of BD-UH, BD-200 and BD-500.


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Morphological results of the BD samples are shown in Figure 10. It is clear to see that large agglomerates are formed in BD-UH and BD-200, owning to the existence of PVDF binders. Accordingly, the D50 values obtained from particle size distribution results are as high as ~16 µm. After PVDF decomposition at higher temperatures, single particles are released from large agglomerates, and the D50 values decrease as well. Similar to the XPS results of SD samples, the C1s spectra of BD-UH and BD-200 samples have a binding energy of 286.2 eV and 290.9 eV, in relation to the −CH2− and −CF2− groups of PVDF component, respectively, as shown in Figure 11a. Correspondingly, the peaks located at 687.7 eV in the F1s spectrum are related to −CF2− groups of PVDF.27, 30, 32 While the existence of LiF in BD-800 sample is consistent with the binding energy of 685 eV in F1s spectra.30-31

Figure 10. SEM images of BD-UH (a), BD-200 (b), BD-400 (c), BD-600 (d), BD-800 (e); Particle size distribution curves of BD samples (f).


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Figure 11. XPS patterns of C1s (a) and F1s (b) elements in BD-UH, BD-200 and BD-800. Electrochemical performances of all the BD samples are shown in Figure 12. Electrodes regenerated at lower temperatures of 200 °C and 300 °C exhibit better performances. The reversible discharge capacity of BD-200 are 122.7 mA h g−1 at 0.2C after 100 cycles and 111.3 mA h g−1 at 1C after 200 cycles. The rate capability test in Figure 12c shows that, BD-200 exhibits higher discharge capacities than the other samples at all rates. At 5C rate, the average discharge capacity is 105 mA h g−1 for the BD-200 sample. From the charge/discharge profiles at different cycles and the corresponding differential capacity curves of BD-200 at 0.2C, the discharge voltage peak locates at 3.73 V, lower than those of DC-600 and SD-800 samples. It is speculated that at lower calcination temperature of 200 °C, PVDF begins to melt, and the long tangled chains of PVDF can move around and recrystallize in the final cooling process, providing the opportunity to redistribute and form a more continuous PVDF binder on the surface of active materials.37-38 On the contrary, higher calcination temperatures cause severe decomposition of PVDF and HF release, which can destroy the layered structure of materials and result in worse electrochemical performances.


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Figure 12. Electrochemical performances of regenerated BD samples: (a, b) Cycling performances at 0.2C and 1C; (c) Rate performances at different currents; (d) dQ dV-1 plots of BD-200 at different cycles; (e) Charge/discharge profiles of BD samples at 0.2C. Table 1. Discharge capacities (mA h g-1) and capacity retentions (%) of regenerated electrodes with different methods. Sample 400 DC

SD

BD

CS

1st discharge 106.1

0.2C 100th discharge 102.3

Capacity retention 96.4

1st discharge 89.8

1C 200th discharge 81.1

Capacity retention 90.3

500

123.6

116.3

94.1

108.1

100

92.5

600

145.4

140.6

96.7

133.7

121

90.5

UH

136

127.1

93.4

126.2

103.7

82.2

300

116.9

99.1

84.8

103.8

84.4

81.3

800

157.8

150.2

95.1

149.5

128.1

85.7

UH

127.8

110.4

86.3

121.7

92.6

76

200

132.3

122.7

92.7

123

111.3

90.5

500

106

87.5

82.5

89.3

75.2

84.2

155.3

145.2

93.5

146.8

129.2

88


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Figure 13. Schematic illustration of different regeneration processes of Li(Ni1/3Co1/3Mn1/3)O2 cathode scraps. For comparison, the characterization and electrochemical performances of commercial Li(Ni1/3Co1/3Mn1/3)O2 sample were conducted, and the results are shown in Figure S4 and S5. The CS sample reveals layered structure with no impurity and regular spherical particles with diameter of 7~12 µm. When tested as cathode materials, the CS sample shows satisfied electrochemical performances. The summary data of CS and typical regenerated samples are listed in Table 1, and the different reaction mechanism of three regeneration processes are illustrated in Figure 13. The separation methods and the following heat treatment temperatures mainly affect the morphology and composite of the regenerated electrodes. We can clearly see that the DC-600 sample exhibits the best cycling performances compared with SD and BD samples. The direct calcination at 600 °C can decompose PVDF completely, thus introduce more LiF composite, which can provide better protection of active materials from side reactions with


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electrolytes. On the other hand, the SD-800 sample delivers the highest discharge capacity during cycling. The solvent dissolution method can remove most PVDF binder, then less LiF is formed during the following calcination. Meanwhile, more active Li ions are reserved, contributing higher reversible discharge capacity. Due to a more serious agglomeration than DC and SD samples, the BD-200 sample performs less well in the electrochemical tests. To summarize, separation methods and calcination process have great impacts on the electrochemical performances of regenerated cathodes for LIBs. CONCLUSION In summary, Li(Ni1/3Co1/3Mn1/3)O2 electrode scraps from industrial production of LIBs were regenerated as new cathodes by a simple and sustainable method, which includes separation and heat treatment processes. A comprehensive and detailed investigation was conducted to find the optimal regeneration conditions and understand the underlying reasons. After regeneration, the cathodes exhibit satisfied electrochemical performances comparable with commercial Li(Ni1/3Co1/3Mn1/3)O2 cathodes. Specifically, scraps separated by solvent dissolution and calcination at 800 °C deliver the highest discharge capacities. Meanwhile, scraps regenerated through direct calcination at 600 °C show the best cycling performances. Both the separation methods and calcination temperatures play an important role in the electrochemical performances. The profound reason lies in the content of LiF from PVDF decomposition and the morphology change of particles during the separation and calcination processes. This work provides a novel perspective of recycling and regeneration of electrode scraps from industrial production for LIBs, and offers multiple options of practical and green regeneration processes for the industry in different situations and requirements.


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ASSOCIATED CONTENT Supporting Information. TG-DTG curves of PVDF binder and AB conductive additive; XRD patterns of regenerated SD samples; XRD patterns of regenerated BD samples and enlarged XRD patterns of regenerated BD-600, BD-700 and BD-800 at 17-20°, 29-33° and 43.5-46°; XRD patterns and SEM images of commercial sample; electrochemical performances of commercial sample. AUTHOR INFORMATION Corresponding Author * Li Li, E-mail address: [email protected] * Renjie Chen, E-mail address: [email protected] Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Notes The authors declare no competing financial interest. ACKNOWLEDGMENT The experimental work of this study was supported by the Joint Funds of the National Natural Science Foundation of China (U1564206) and the National Natural Science Foundation of China (51302014), the Chinese National 973 Program (2015CB251106), Major achievements

Transformation Project for Central University in Beijing and Beijing Science and Technology Project (D151100003015001).


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Table of Contents

Li(Ni1/3Co1/3Mn1/3)O2 electrode scraps from industrial production of LIBs were regenerated as new cathodes by a simple and sustainable method, which includes separation and heat treatment processes.


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Sustainable Recycling and Regeneration of ... - ACS Publications

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