Mechanochemistry-induced recycling of spent lithium-ion batteries for synergistic treatment of mixed cathode powders

Abstract

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.