Mechanistic insights into NaOH-driven crystal destruction and selective lithium extraction from spent LiFePO4 via
Yanbo Pei1, Qing Zhao2, Liwei Liu3
1Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Abstract:
The rapid increase in spent lithium iron phosphate (LiFePO4) batteries brings significant challenges related to environmental pollution, human health risks, and resource sustainability. Conventional recycling technologies are often hampered by high energy consumption, secondary pollution, and operational hazards. This study proposes a sustainable mechanochemical approach for recycling spent LiFePO4 black mass, based on the targeted destruction of the stable LiFePO4 crystal structure. Using sodium hydroxide as an efficient co-grinding agent in a solvent-free system, a superior lithium leaching efficiency of 98.83 % was achieved under optimized conditions, while iron co-leaching was effectively suppressed to 0.27 %. Comprehensive characterizations, including X-ray diffraction, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy confirmed the destruction of the LiFePO4 crystal structure, the formation of Li3PO4, and the oxidation of Fe2+. An economic assessment demonstrates the viability of this procedure, yielding a net profit of $0.9659 per kilogram of LiFePO4 black mass. This work presents an efficient, economically viable, and environmentally benign mechanochemical strategy for LiFePO4 battery recycling, offering fundamental insights into crystal structure destruction for sustainable resource recovery.
