Microwave-Assisted Methanol–Sulfosalicylic Acid Leaching System for Efficient and Closed-Loop Lithium-Ion Battery Cathode Recycling

Abstract

Effective recycling of spent lithium-ion batteries (LIBs) is critical to mitigating resource scarcity and environmental degradation amid rising global demand for energy storage. However, LIB recycling faces two persistent challenges: non-recyclable reductants in organic acid systems and inefficiencies in processing mixed cathode powders. Herein, we introduce a closed-loop methanol–sulfosalicylic acid (MeOH–SSA) system for rapid, sustainable metal recovery. Leveraging microwave-assisted leaching, this approach achieves exceptional efficiencies (>99% within 15 min) for extracting Li, Ni, Co, and Mn, governed by an internal diffusion-controlled mechanism with notably low activation energies (15.39, 17.57, and 17.55 kJ mol⁻¹ for Ni, Co, and Mn, respectively). Our integrated recovery process, encompassing oxalate coprecipitation, MeOH regeneration, and Li₃PO₄ isolation, achieves complete recovery of Ni and Co, high recovery of Mn (97%), and effective Li recovery (95.87% with 94% purity), alongside 92.53% MeOH reuse. A techno-economic analysis highlights significant advantages: a net profit of $22.59 per kg of processed cathode material with an energy consumption of 28.09 MJ kg⁻¹, outperforming conventional methods in cost-efficiency and environmental footprint. Notably, this system excels across both single-component and mixed cathode compositions. By simultaneously addressing reductant reusability and mixed-cathode compatibility, this work establishes a versatile, eco-efficient framework for LIB recycling.