Recycling garnet-type electrolyte toward superior cycling performance for solid-state lithium batteries

Green-sustainable approaches prompt urgent attention for recycling end-of-life spent solid-state lithium batteries (SSLBs), which are candidates for next-generation energy storage systems. Here, we propose a green method of deformation-driven re-sintering (DDR) to recycle spent SSLBs with emphasis on garnet-type solid-state electrolyte (SSE) recovery. The recycled fine SSE particles via DDR provide sufficient sintering activity for grain fusion and promote Li absorption with the Li2O atmosphere. The severe deformation accelerates the phase transformation process from the tetragonal phase to cubic phase and inhibits the proton/lithium exchange process. The homogeneous distribution of Li-ions eliminates discontinuous connection areas, facilitating the establishment of fast ionic pathways. The critical current density of DDR-SSE reaches 1.24 mA·cm−2, indicating a stable process of the stripping and plating lithium. SSLBs assembled by the DDR-SSE and LiFePO4 cathode show a superior cycling performance with a discharge capacity of 126.7 mAh·g−1 and capacity retention of 89.7% after 400 cycles (0.5 C) at room temperature. The work firstly provides a feasible green-sustainable method for spent SSEs with high performances, promoting the environmental benignity and economic viability for the sustainable solution of resources.