(Invited) Recycling and Upcycling Electrode Materials from Spent Lithium-Ion and Alkaline Batteries
Authors: Wang Xiaolei 
Published: July 2022

Lithium-ion batteries (LIBs) and alkaline batteries have been widely used in electric vehicles and portable electronics, dominating the energy storage market for decades,[1] but their recycling/upcycling has lagged far behind. Re/up-cycling batteries is urgently needed because it can not only preserve raw materials such as Li, Co, Ni, Mn, Al, and Cu for LIBs as well as Zn, Mn, Fe for alkaline batteries but also reduce hazardous wastes towards the environment.[2] Despite previous efforts made on re/up-cycling LIBs and alkaline batteries, there remains an urgent demand for simple, economic, environmentally benign, and energy-saving approaches.

For LIB recycling, the dominated recycling methods including pyrometallurgy and hydrometallurgy are destructive and criticized of high energy consumption, undesirable economic outputs, and water contamination. By contrast, non-destructive methods such as solid-state sintering[3] and hydrothermal treatment coupled with short annealing (HT-SA) [4-5]are more promising. However, these emerged direct recycling approaches are deficient at regenerating outdated cathode materials to meet current market need. As such, upcycling (i.e., upgraded regeneration of cathodes) through surface engineering (coating[6] and doping[7-9]) or bulk reconstruction[10] has been developed. In our work, we demonstrate one upcycling approach to regenerate LiCoO2 cathode through an improved HT-SA approach in which a coating layer is prepared accompanied with the regeneration process. The upcycled cathode material shows improved electrochemical performance surpassing the pristine electrode materials.

For alkaline battery recycling, the major recycling still focuses on hydrometallurgy and pyrometallurgy. Hydrometallurgical processes generally follow different steps of pre-treatment and subsequent leaching and separation of different metals by electrolysis, extraction or precipitation.[11] Another approach for treating spent alkaline battery materials is upcycling towards other applications such as supercapacitors,[12] catalysis[13], micronutrient fertilizer,[14] Mn alloy fabrication.[14] In our work, for the first time, we directly upcycle both zinc anode and Mn-based cathode for their use in rechargeable Zn-MnO2 batteries by a simple yet efficient annealing procedure. Zn was regenerated in a reductive atmosphere and the regenerated Zn shows high Coulombic efficiency and long life in symmetric cells while the regenerated Mn-based cathode shows superior performance than fresh MnO2 with regards to capacity, rate, and life. Under optimized N/P ratio, the regenerated Zn and MnO2 was paired to make rechargeable Zn-MnO2 batteries delivering excellent performance, comparable or even superior to state-of-the-art Zn-MnO2 batteries.

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