Artificially transformed ultra-stable Li6.75La3Zr1.75Ta0.25O12 incorporated composite solid electrolyte towards high voltage solid lithium metal batteries

Garnet-type Li6.75La3Zr1.75Ta0.25O12 (LLZTO) is enlightening great future in solid-state lithium metal batteries due to the considerable ionic conductivity and good compatibility with metallic lithium. Unfortunately, LLZTO is always trapped into the Li2CO3 by-product forming on the surface in a moist atmosphere and becomes difficult for practical application. Herein, we propose an in-situ conversion from the Li2CO3 by-product towards electrochemical active LiCoO2 to turn this disadvantage. The modified LLZTO (M−LLZTO) realizes excellent air stability and performs impressively enhanced electrochemical performance in the structure application of both cathode and composite solid electrolyte (CSE). The prepared CSE delivers high ionic conductivity and good electrochemical stability against Li metal with an ultra-long lifespan over 2000 h in the symmetrical cells. Once working in a solid-state lithium battery with a LiCoO2 cathode, the solid battery maintains a low capacity fade of 4.51 % over 150 cycles and a high average columbic efficiency of 99 %. All these results promise a new insight into the air sensitive solid electrolyte for advanced solid-state lithium batteries.