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-sate lithium batteries (SLBs). Herein, Li6.5La3Zr1.5Ta0.5O12 (LLZTO) pellets before sintering are compacted under various pressure to study the impact of compaction pressure on the overall properties of LLZTO SSEs and their SLBs. Among them, the sample pressed at 600 MPa (LLZTO-600) has the largest compactness and the highest ionic conductivity due to the 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 1500 h without short circuits. Meanwhile, the LFP|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.