Green recycling of short-circuited garnet-type electrolyte for high-performance solid-state lithium batteries

Abstract

Solid-state lithium batteries (SSLBs) solve safety issues and are potentially energy-dense alternatives to next-generation energy storage systems. Battery green recycling routes are responsible for the widespread use of SSLBs due to minimizing environmental contamination, reducing production costs, and providing a sustainable solution for resources, e.g., saving rare earth elements (La, Ta, etc.). Herein, a solid-state recycling strategy is proposed to achieve green recycling of the crucial component solid-state electrolytes (SSEs) in spent SSLBs. The short-circuited garnet Li6.5La3Zr1.5Ta0.5O12 (LLZTO) is broken into fine particles and mixed with fresh particles to improve sintering activity and achieve high packing density. The continuous Li absorption process promotes sufficient grain fusion and guarantees the transformation from tetragonal phase to pure cubic phase for high-performance recycled LLZTO. The Li-ion conductivity reaches 5.80 × 10-4 S cm−1 with a relative density of 95.9%. Symmetric Li cell with as-recycled LLZTO shows long-term cycling stability for 700 h at 0.3 mA cm−2 without any voltage hysteresis. Full cell exhibits an excellent cycling performance with a discharge capacity of 141.5 mA h g−1 and a capacity retention of 92.1% after 400 cycles (0.2C). This work develops an environmentally friendly and economically controllable strategy to recycle SSE from spent SSLBs, guiding future directions of SSLBs large-scale industrial application and green recycling study.