Thin laminar inorganic solid electrolyte with high ionic conductance towards high-performance all-solid-state lithium battery

The development of thin solid-state electrolytes with high ionic conductivity and mechanical strength is essential for high-performance all-solid-state lithium batteries. Although Inorganic solid electrolytes (ISEs) possess high ionic conductivity, fabricating thin and mechanically stable ISEs is still challenging. Herein, Li7La3Zr2O12 (LLZO) nanosheets with lateral size of 3-5 mu m and thickness of -4.5 nm were prepared, and then self-assembled into thin, defect-free, and freestanding LLZO laminar ISE (LLISE). Compared to LLZO pellet (>200 mu m) obtained by cold-pressing method, LLISE with a thickness of 12 mu m attains an almost 10-times higher ionic conductivity of 1.30 x 10-4 S cm-1 at 30 degrees C because of the short Li-ion diffusion distance. Importantly, this thin thickness gives high ionic conductance (0.17 S at 30 degrees C) and energy density of 340 Wh kg-1, ranking one of the highest values among reported solid-state electrolytes. Meanwhile, the compressive strength of LLISE with a thickness of 20 mu m (LLISE-20) reaches 3.2 Gpa. The Li symmetrical cell assembled with LLISE-20 can work over 1500 h without obvious polarization under a current density of 0.2 mA cm-2 at 60 degrees C. The LFP/Li cell exhibits superior cycling stability of 143.2 mAh g-1 at 0.5C and 60 degrees C after 200 cycles with low capacity decay of 0.05% per cycle.

Automated summary

In this study, thin and defect-free LLZO laminar solid electrolytes (LLISE) were successfully prepared, exhibiting high ionic conductivity and mechanical strength. LLISE showed high ionic conductance (0.17 S) and energy density (340 Wh kg-1) at 30 degrees C, along with high compressive strength.