Advances and Challenges on Recycling the Electrode and Electrolyte Materials in Spent Lithium-Ion Batteries

Abstract

Lithium-ion batteries (LIBs), as the advanced power batteries with comprehensive performance, have widely used in electric vehicles (EVs), military equipment, aerospace, consumer electronics, and other fields. With the surge in demand for LIBs, the number of spent LIBs has increased rapidly. However, if the spent LIBs just are simply landfilled, the hazardous components contained in them such as heavy metals and organic electrolytes will pollute the environment, and ultimately threaten human health. In addition, some valuable components will be wasted by landfill, especially high-value metal elements contained in cathode. Thus, the recycling of spent LIBs is a “two birds with one stone” strategy which is not only beneficial to environmental protection but also has high economic value. Accordingly, great efforts have been made to develop efficient and cost-effective recycling processes for spent LIBs recovery. In line with the recycling process, this review first presents a series of pretreatment progresses (disassembling, inactivation, dismantling, and separation) and discusses the problems and challenges involved (automation, environmental protection, and cost, etc.). Second, we summarize and discuss the current recovery and regeneration technologies for cathode materials, including pyrometallurgy, hydrometallurgy and electrochemistry. In addition, advances in the recovery of anode and electrolyte are also introduced. Finally, based on the current state of recycling, we cautiously make some suggestions and prospects for the future recycling of spent LIBs, with a view to providing more ideas for the recycling of used LIBs.

Recycling Hazardous and Valuable Electrolyte in Spent Lithium-Ion Batteries: Urgency, Progress, Challenge, and Viable Approach

“…The traditional treatment process of Li-based salts in the electrolyte is usually accoupled with the recovery of electrodes, which were decomposed to LiF etc. during the pretreatment of spent LIBs such as dismantling, crushing, or heat treatment. ,,, However, the emission of toxic fluorine- and phosphorus-containing compounds has not received much attention. Meanwhile, the economic value of LiPF 6 is the driving force for recycling.…”

“…during the pretreatment of spent LIBs such as dismantling, crushing, or heat treatment. 21,22,27,28 However, the emission of toxic fluorine-and phosphorus-containing compounds has not received much attention. Meanwhile, the economic value of LiPF 6 is the driving force for recycling.…”

“…24−26 Meanwhile, the volatile carbonate solvents including methyl ethyl carbonate (EMC), ethylene carbonate (EC), and dimethyl carbonate (DMC), etc., will be produced small volatile organic compounds (VOCs). 21,22,27,28 Besides, the small number of additives such as flame retardants will transform into carcinogenic furans and dioxins during the burning process. 29,30 As a result, these hazardous materials derived from the electrolyte easily diffuse into the water, soil, and air, causing serious environmental pollution and threatening human life.…”

“…The sensitive Li-based salts such as LiPF 6 can easily react with trace water to produce toxic fluorine- and phosphorus-containing compounds (POF 3 , PF 5 , HF, and H 3 PO 4 , etc. ). − Meanwhile, the volatile carbonate solvents including methyl ethyl carbonate (EMC), ethylene carbonate (EC), and dimethyl carbonate (DMC), etc., will be produced small volatile organic compounds (VOCs). ,,, Besides, the small number of additives such as flame retardants will transform into carcinogenic furans and dioxins during the burning process. , As a result, these hazardous materials derived from the electrolyte easily diffuse into the water, soil, and air, causing serious environmental pollution and threatening human life. However, the hazardous electrolyte treatment is always neglected during spent LIBs recycling.…”

“…However, due to the relatively few studies ( ∼10 ) about electrolyte treatment included in the Web of Science, there are few reviews fully focused on electrolyte recovery, while illustrating and discussing it as only a small part of spent LIBs recycling. , On the other hand, as one of the world’s largest producers of LIBs and disposal of spent LIBs in China, more and growing reports (about 80 ) about electrolyte treatment are found in Chinese patents and journals, which were included in the China National Knowledge Infrastructure (CNKI), as shown in Figure . ,− Some of the results are interesting and can provide significant technical and theoretical references for electrolyte treatment. Unfortunately, these results have not been reviewed and well exhibited worldwide due to the limitations of the language.…”