SiCl4-Assisted Calcination Strategy for Lithium Recovery and Regeneration of Cathodes

Abstract

The rapid growth of lithium-ion battery (LIB) deployment has intensified the need for efficient and sustainable recycling of spent cathodes. This work introduces a silicon tetrachloride (SiCl4)-assisted calcination strategy that repurposes SiCl4, a hazardous byproduct of the photovoltaic industry, as an effective low-temperature chlorinating agent for metal recovery from spent Ni-rich cathodes. Thermodynamic analysis indicates spontaneous chlorination reactions initiated by preferential Li extraction, followed by stepwise gas−solid propagation converting Ni, Co, and Mn into soluble chlorides, while generating phase-pure SiO2 as a benign byproduct. Under optimized conditions (500 °C, SiCl4:cathode = 3:1, 25 and 40 min), leaching efficiencies exceed 95% for Li, Ni, Co, and Mn from NCM622 and LMO, and similarly high recovery is achieved for unsorted mixed cathodes. The recovered metals are resynthesized into phase-pure NCM622 and LMO via coprecipitation and sol−gel routes, delivering 166.7 and 116.9 mAh g−1 at 1 C with 90 and 82% capacity retention after 100 cycles, respectively, comparable to pristine analogues. Techno-economic and life-cycle assessments using the EverBatt model reveal reduced energy consumption, greenhouse gas emissions, and processing costs compared with conventional methods. This SiCl4-assisted calcination offers a sustainable, high-value, and circular approach for LIB cathode resynthesis while bridging photovoltaic and battery material loops.