Li10GeP2S12-based solid electrolyte induced by high pressure for all-solid-state batteries: A facile strategy of low-grain-boundary-resistance

Solid electrolytes (SEs) with high ionic conductivity are crucial for the collaborative design of high-performance all-solid-state lithium batteries (ASSLBs). Besides the common element substitution and doping, it is anticipated that there is still room for pressure to improve ionic conductivity in SEs by modifying their crystal structure and microstructure. Herein, we applied in-situ high pressure to monitor the effect of compression on the structure–property relation in Li10GeP2S12 (LGPS). The lattice contraction (<2%) of LG was monitored within 2 GPa, which does not affect the optimal size of the ionic channel. In contrast to the fact that the grain resistance can be markedly decreased by low pressing, grain boundary resistance is found to be minimized by virtue of 1.5 GPa, and accordingly, interfacial Li± ionic diffusion between flexible grain bodies and electrode surface is primarily facilitated by enhancing the charge carrier mobility. In addition, we report for the first time that powder LGPS could be pressed as a ceramic-sulfide pellet without breakage under 1.5 GPa and assembled as a solid electrolyte within the LiFePO4/Li10GeP2S12/Li configuration of ASSLBs. This cell exhibits improved capacity and cycling stability compared to the cell using no-pressure-treated electrolyte. The present study advances our understanding of solid electrolytes and provides an important framework for developing high-performance ASSLBs with low fabrication costs in the future.