Tolerance for Li dendrite penetration in Ta-doped Li7La3Zr2O12 solid electrolytes sintered with Li2.3C0.7B0.3O3 additive

Abstract

We fabricated garnet-type Ta-doped Li7La3Zr2O12 (LLZTO)/Li2.3C0.7B0.3O3 (LCBO) composite ceramic solid electrolytes. By adding the appropriate amount of LCBO to LLZTO, composite solid electrolytes were densified by sintering at 1000 °C without covering the pellet with LLZTO mother powder. LLZTO/LCBO Composites with LCBO volume contents of 20 and 50% showed the ionic conductivity well above 1 × 10−4 S cm−1 at room temperature. Li plating and stripping property for LLZTO/LCBO composites was evaluated using symmetric cells with Li metal electrodes at room temperature. As results, a symmetric cell composed of composite solid electrolyte with low LCBO volume content was stably cycled at the current density up to 0.3 mA cm−2, but increasing the amount of LCBO significantly lowered the current density where the Li dendrite penetration in solid electrolyte occurs. This indicates that LCBO addition is effective for lowering the sintering temperature of LLZTO but the smaller LCBO content is prefer to maintain the tolerance for Li dendrite penetration at high current density.