Recent advances in the industrialization of direct recycling for retired lithium-ion batteries

Abstract

The exponential growth of lithium-ion batteries (LIBs) in electric vehicles and grid storage has escalated concerns over critical resource scarcity and environmental risks from end-of-life waste. Compared to pyrometallurgical and hydrometallurgical recycling methods, which are often associated with high energy consumption, secondary pollution, and poor economic benefits, direct recycling, which focuses on the regeneration of cathode materials, offers a sustainable closed-loop recycling pathway. This review systematically examines the technical framework of direct recycling, encompassing safety-critical pretreatment (discharging and disassembly) and advanced separation strategies to recover cathode active materials intact from current collectors. It further analyzes six cathode regeneration methodologies: solid-state sintering, which is simple but limited by inhomogeneity; solvothermal method, which can restore uniformity but lacks safety and is constrained in scalability; molten-salt method, which requires high temperatures to achieve uniform regeneration; electrochemical relithiation methods, which require complex equipment, are limited in terms of scalability for industrial applications; chemical relithiation methods, which involve the use of organic solvents and lithium compounds, may potentially lead to secondary pollution. Functional organic lithium salts can create conditions for uniform regeneration at ambient temperature and pressure. Despite promising lab-scale results, industrial adoption faces hurdles including inconsistent separation purity, a lack of universal protocols for mixed/degraded cathodes, high operational costs, and uncertain market acceptance. Future progress hinges on the development of low-cost, high-efficiency, and high-purity smart screening techniques for battery materials; uniform regeneration of different types of degraded materials; upgraded recycling approaches that enhance performance through doping/coating; and comprehensive lifecycle assessments to validate environmental and economic benefits. This work consolidates critical insights to accelerate the transition of direct recycling from innovation to scalable industrial practice.