Impact of compaction pressure on formation and performance of garnet-based solid-state lithium batteries

Compaction pressure directly determines the compactness of solid-state electrolytes (SSEs), which is crucial to affect the electrochemical performance of solid-state lithium batteries (SLBs). Herein, Li6.5La3Zr1.5Ta0.5O12 (LLZTO) pellets are compacted under various pressures before sintering to study the impact of compaction pressure on the overall properties of LLZTO SSEs and their SLBs. Notably, the sample pressed at 600 MPa (LLZTO-600) exhibits the highest compactness and the highest ionic conductivity due to improved particle contact and suppressed lithium loss. Consequently, the Li|LLZTO-600|Li symmetric cell exhibits the best performance among the samples, which can stably cycle for 1,500 h without short circuits. Meanwhile, the LiFePO4|LLZTO-600|Li full cell can retain 94.8% of its initial capacity after 150 cycles with the lowest overpotential among the SSEs. This work highlights the importance of tuning compaction pressure in developing high-performance SSEs and related SLBs.