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Sustainable recycling of metal resources from spent lithium-ion batteries (LIBs) with reduced environmental impacts is attracting increasing attention in the current recycling processes. However, over-reliance on energy and chemical input is one of the leading bottlenecks for the prevailing technologies. In this study, pyrolysis gases generated from renewable biomass waste by microthermal catalysis of the cathode material (LiNixCoyMn1−x−yO2) in spent LIBs were innovatively used as reactants for the regulated reduction and conversion of different metals. Detailed experimental results suggest that different reaction pathways for metals can be controlled by the experimental conditions, especially reaction temperature. Li tends to be converted into Li2CO3, immune to the reaction temperature, while Co(III) and Mn(IV) can be just reduced into CoO and MnO in the lower roasting temperature range of 300 °C–500 °C, with further reduction into their metallic forms Co and Ni in the higher temperature range of 500 °C–700 °C, while MnO cannot be further reduced into metallic Mn, and the different converted products are recovered based on their forms with significantly reduced consumption of chemicals. Finally, tentative exploration of the reaction mechanism suggests that cathode materials are efficient catalysts to reduce the roasting temperature and promote the generation of H2 from biomass wastes, changing the traditional solid–solid reaction of carbothermal metallurgy to the gas–solid reaction of hydrogen metallurgy with reduced input of chemical and energy. [ABSTRACT FROM AUTHOR]

Efficient and sustainable recycling of metal resources from spent lithium-ion batteries (LIBs) has been attracting increasing attention, while the overwhelming dependency on chemicals and energy of the currently prevailing spent LIB recycling technologies makes it vulnerable to secondary contaminations. Herein, a mechanochemistry-based process was proposed to recover metals from waste cathode materials of LiCoO2 (LCO) and LiFePO4 (LFP) in spent LIBs based on their intrinsic redox properties. During the mechanochemical reactions, the crystal structures of LCO and LFP were destroyed and converted into amorphous states, with the synchronous generation and conversion of waste cathode materials into their recyclable states under the optimized experimental conditions of molar ratio (LCO : LFP) – 1 : 1, milling time – 5 h, rotation speed – 650 rpm and ball–powder ratio – 50 : 1. Then, 99.9% of Li and 88.6% of Co can be selectively extracted from FePO4 enriched leaching residues using a stoichiometric acid dosage of 0.15 M H2SO4. The deintercalation of Li from different waste cathode materials and in situ conversion of Co(III)/Fe(II) into CoO/FePO4 were further confirmed by DFT calculation results. Additional reductants/oxidants were avoided by this mechanochemistry-based strategy with significantly reduced consumption of chemicals, engineering a green and efficient recycling process for the simultaneous recycling of different metals from spent LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Waste copper sulphate solution was electrolyzed to provide sulphuric acid. • This study obtained leaching rates of 93 % of Ni, 91 % of Co, 89 % of Mn and 92 % of Li. • Recovery rates of 91 % of Ni, 91 % of Co, 86 % of Mn and 90 % of Li were achieved. • A novel method was developed without using any acid or reductant. • This work demonstrated the application of treating waste with waste. Effective recovery of Li, Co, Ni and Mn from cathode materials of spent lithium-ion batteries (LIBs) has become a global concern. In this study, electrolysis of copper sulfate to produce sulfuric acid and electrons were utilized to recover Li, Co, Ni and Mn from spent LIBs. The obtained results showed that 93 % of Ni, 91 % of Co, 89 % of Mn and 94 % of Li were leached and 99 % of Cu was deposited during leaching process by adopting the 0.225 mol/L of copper sulfate with a solid/liquid ratio of 15 g/L at a current density of 50 mA/m2 and 80 °C for 4.5 h. Then, a current efficiency of 72 % for the cathode and 30 % for the anode was achieved at a current density of 40 mA/m2, 70 °C and pH 2.5 during electrodeposition process. The Ni-Co deposition followed the principle of anomalous codeposition and the complete deposition time of Co, Ni and Mn were 3 h, 9 h and 10 h, respectively. Eventually, the Ni, Co, Mn, Li and Cu can be recovered as Ni-Co alloy, MnO 2 and Li 2 CO 3 and Cu metals with the corresponding recovery rates of 99.40 %, 91.00 %, 90.68 %, 85.59 % and 89.55 %, respectively. This study proposes a promising strategy for recycling cathode materials from spent LIBs without addition of chemical reductants and acids. [ABSTRACT FROM AUTHOR]

It might be of practical significance to recover different metals from the already complicated waste spent lithium-ion battery (LIB) stream by simplified recycling processes. This study is, therefore, focused on the exploration of a simplified process for the simultaneous recovery of different metals from waste cathode materials of mixed types of spent LIBs. It is discovered that the leaching agent phosphoric acid demonstrates natural repulsion for Fe, while valuable metals such as Ni, Co, Mn, and Li can be completely dissolved under optimized leaching conditions, indicating a coupling reaction of selective leaching and precipitating for valuable metals and iron, respectively. Characterization results indicate valuable metal-enriched solution and pure FePO4 in leaching solution and residue, respectively. Kinetics and dynamics studies suggest that the leaching of valuable metals is co-controlled by chemical reaction and internal diffusion, accompanying a spontaneous formation of FePO4. Then, new cathode materials LiFePO4 and LiNi1/3Co1/3Mn1/3O2 with sound electrochemical performances can be re-fabricated from leaching residues and lixivium, respectively, and phosphoric acid can be regenerated during the co-precipitating of valuable metals. This entire recycling process can be a highly selective, closed-loop and simplified alternative for recycling different metals from the current most complicated waste LIB stream. [ABSTRACT FROM AUTHOR]

Pursuing sustainable process for selective recycling of valuable metals from spent lithium-ion batteries through low-temperature thermochemistry. [Display omitted] • A low-temperature thermochemical process was proposed for spent LIBs recycling. • Biomass wastes were used as renewable reductants for the conversion of Co and Li. • Li and Co can be selectively recovered as Li 2 CO 3 and CoO/Co by thermal-treatment. • Formation and conversion of products were controlled by different temperature gradient. • Detailed thermochemical reaction process and reduction mechanism were explored. Efficient recycling of valuable metals from spent lithium-ion batteries (LIBs) with the minimized environmental footprint is prevailing among different recycling processes. However, the extensive energy consumption, associated with secondary contaminations, is one of the leading bottlenecks during thermochemical processing. Herein, low-temperature thermochemistry route was explored by thermal reduction using biomass wastes as reductants for selective recycling of valuable metals from spent LIBs based on their inherent conversion characteristics. It can be concluded from the experimental results that corn stalk exhibits better reducing capacity than saw dust and rice straw, and different metals in cathode materials (LiCoO 2) of spent LIBs demonstrate different conversion pathways with the variation of reaction temperatures. Specifically, Li in waste LiCoO 2 tends to be converted into Li 2 CO 3 under reaction temperature range of 250–500 °C, while Co will mainly exist as CoO (400–600 °C) or Co (600–800 °C). Then, the converted product of Li 2 CO 3 can be selectively extracted by water leaching, and CoO or Co will be subjected for mild acidic leaching or magnetic separation, respectively. Detailed characterizations and thermochemical mechanism suggest that the reduction reactions are mainly controlled by one-dimensional model and different products can be obtained through regulation of reaction temperature. This win–win tactics using biomass wastes with significantly reduced roasting temperature is expected to be high-efficiency, high-selectivity and pollutant-free process for spent LIBs recycling. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simultaneous recycling multiple cathode materials by their own intrinsic properties. • Usage of oxidant/reductant can be avoided in mild vitriolic medium. • High-purity FePO 4 can be directly obtained by selective precipitation. • Synergistic recycling of different metals was achieved by Ferro-chemistry approach. Sustainable recycling of different value-added metals from spent lithium-ion batteries (LIBs) can expect significant environmental and economic benefits for the fulfillment of resources utilization. During the separation and recovery of different metals, excessive chemical consumption caused by prolonged processes may eventually spoil the environmentally soundness recycling of spent LIBs. Here, Ferro-chemistry was innovatively proposed towards the recycling of different metals based on transformation of iron morphology from different types of spent LIBs (LiCoO 2 and LiFePO 4). It can be concluded from the thermodynamic results that redox reaction will take place in dilute sulfuric acid medium without addition of reductant/oxidant, indicating that Fe(II) in LFP can be used as reductant for the direct leaching of LiCoO 2. Leaching results indicate that 99.9% Li, Fe, P and 92.4% Co can be dissolved and existed as Fe3+, Li+, PO 4 3− and Co2+ under the optimized conditions, with a decline of over 80% acid consumption. The leaching kinetics of different metals and reaction mechanism suggest that Fe(II) will be promptly liberated to lixivium and then slowly oxidized into Fe(III) with the existence of Co(III), resulting in a synergetic leaching of Co and Fe. Then, Fe(III) can be precipitated as FePO 4 at pH of 2.5, which can remove PO 4 3− with the direct generation of LiFePO 4 precursors. This above ferro-chemistry strategy can effectively reduce the consumption of chemicals with reduced environmental footprint. [ABSTRACT FROM AUTHOR]

• Stoichiometric ratios of acids are used for Li and transition metals leaching. • Dilute tartaric acid shows high selectivity towards Li. • Transition metals can be completely dissolved in dilute sulfuric acid. • NCM cathode materials can be re-fabricated from the obtained products. • A closed-loop process with high selectivity and efficiency is established. Sustainable recycling value-added metals from spent lithium-ion batteries (LIBs) has been supposed to be a promising alternative to alleviate the current environmental and resource issues. Reduced reagents consumption and closed-loop reutilization are still challenging in current prevailing recycling processes. This study proposed a novel recycling strategy involved with gradient extraction of valuable metals and closed-loop re-fabrication of cathode materials. Lithium was selectively recovered as lithium enriched lixivium in mild tartaric acidic medium with a high yield of 99.7 % and little co-extraction of transition metals (Ni, Co and Mn) under optimized leaching conditions. Then transition metals enriched residues can be completely dissolved in facile sulfuric acidic medium without the contamination of Li. Li 2 CO 3 and ternary precursors were recovered from Li enriched lixivium and transition metal enriched lixivium, respectively. Finally, cathode materials of LiNi 1/3 Co 1/3 Mn 1/3 O 2 are refabricated using obtained products to close the recycling loop. It can be concluded that it is possible for the gradient recycling of Li and transition metals based on their inherent properties with minimized consumption of acids under facile leaching conditions, which can also facilitate metals separation process for closed-looped re-fabrication of new cathode materials. [ABSTRACT FROM AUTHOR]

• Usage of acid and reducatant can be avoided in electro-chemical leaching. • Reduced Ea (s) can greatly facilitate the electro-leaching of valuable metals. • Closed-loop cycle of acid generation and metal recycling can be established. • Valuable metals can be efficiently and directly recovered with high selectivity. The sustainable recycling of valuable metals from spent lithium-ion batteries (LIBs) is impeded by the issues of extensive chemicals consumption, tedious separation process and deficient selectivity. Here, novel electrochemically driven and internal circulation strategy was developed for the direct and selective recycling of valuable metals from waste LiCoO 2 of spent LIBs. Firstly, the waste LiCoO 2 can be efficiently dissolved by generated acid (H 2 SO 4) during electro-deposition of Cu from CuSO 4 electrolyte. Then, Co2+ ions in the lixivium can be electrodeposited and recovered as metallic Co with a coinstantaneous regeneration of H 2 SO 4 and regenerated acid can be reused as leachant without obvious shrinking of leaching capability based on circulating leaching results. Over 92% Co and 97% Li can be leached, and 100% Cu and 93% Co are recovered as their metallic forms under the optimized experimental conditions. Results of leaching kinetics suggest that the leaching of Co and Li is controlled by internal diffusion with significantly reduced apparent activation energies (E a) for Li and Co. Finally, Li 2 CO 3 can be recovered from Li+ enriched lixivium after circulating leaching. This recycling process is a simplified route without any input of leachant and reductant, and valuable metals can be selectively recovered in a closed-loop way with high efficiency. [ABSTRACT FROM AUTHOR]

Efficient and sustainable recycling of metal resources from spent lithium-ion batteries (LIBs) is critical for the metal resources security and environment protection. However, the intact exfoliation of cathode materials (CMs) from current collectors (Al foils) and selective extraction of Li towards the in-situ and sustainable recycling of cathodes from spent LIBs are still pending issues. A self-activated and ultrasonic-induced endogenous advanced oxidation process (EAOP) was proposed in this study for selective removal of PVDF and in-situ extraction of Li from CMs of waste LiFePO 4 (LFP) to address the above issues. Over 99 wt% CMs can be detached from Al foils after EAOP treatment under the optimized operation conditions. High purity of Al foil can be directly recycled as metallic forms and nearly 100 % of Li can be in-situ extracted from the detached CMs and then recovered as Li 2 CO 3 (>99.9 % in purity). With induction and reinforcement of ultrasonic, S 2 O 8 2- was self-activated by LFP to generate an increased amount of SO 4 •− radicals that will attack the PVDF binders to ensure their degradation. The degradation pathway of PVDF and density functional theory (DFT) calculation can also support the analytical and experimental results. Then, the complete and in-situ ionization of Li can be achieved by the further oxidization of SO 4 •− radicals from LFP powders. This work provides a novel strategy towards efficient and in-situ recycling of valuable metals from spent LIBs with minimized environmental footprint. [Display omitted] • An endogenous advanced oxidation process (EAOP) was proposed for spent LIBs recycling. • Effective exfoliation of cathode materials from Al foils and selective recycling of metals. • LFP are self-activator to generate radicals under the induction and reinforcement of ultrasound. • Defluorination and carbon skeleton fracture of PVDF under the action of radicals. • Density function theory (DFT) was used to support the PVDF degradation mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • A phosphate chemistry-based process was established for metal recycling; • Priority extraction of Li without contamination of transition metals in lixivium; • Short-cut and selective conversion of Co into CoHPO 4 in leaching residues; • Closed-loop recycling of Li and P as high purity Li 2 CO 3 and struvite; • Revealing transformation and existence mechanism in phosphate medium. The sustainable recycling of valuable metals from spent lithium-ion batteries (LIBs) has attracted an increasing attention. While the uncontrollable nature of reactants from traditional processes will result in increased process cost and environmental footprint. Herein, phosphate chemistry based was process proposed for the recovery of valuable metals from spent LIBs, in which H 3 PO 4 was used as both leachant and precipitant for the selective leaching of Li and direct precipitating of transition metals (Me, Me = Ni, Co, Mn, Fe). In this work, Li will be converted into soluble phosphate (i.e. LiH 2 PO 4) while transition metals tend to form insoluble phosphates of Me 3 (PO 4) 2 and MeHPO 4 under the optimized conditions, indicating the possibility for priority extraction of Li and direct conversion of transition metals into products under controlled experimental condition. Then, LiH 2 PO 4 can be further recovered as struvite (MgNH 4 PO 4 ·6H 2 O, the upcycling of P, recovery rate > 99.97%) and Li 2 CO 3 (purity > 99.99%). This phosphate-chemistry-based recycling process is a validated and promising candidate towards the closed-loop recycling of valuable metals from spent LIBs with minimized impacts on the environment. [ABSTRACT FROM AUTHOR]