Abstract

Solid-state batteries (SSBs) can essentially improve battery safety. Garnet-type Li7La3Zr2O12 (LLZO) is considered one of the most promising solid electrolytes for SSBs. However, the performance of LLZO-based SSBs is limited by the large cathode/electrolyte interfacial resistance. High-rate and long-cycling SSBs were achieved only after adding flammable polymer or liquid electrolyte in the cathode at the sacrifice of safety. Here, we show that an all-ceramic cathode/electrolyte with an extremely low interfacial resistance can be realized by thermally soldering LiCoO2 (LCO) and LLZO together with the Li2.3−xC0.7+xB0.3−xO3 solid electrolyte interphase through the reaction between the Li2.3C0.7B0.3O3 solder and the Li2CO3 layers that can be conformally coated on both LLZO and LCO. The all-solid-state Li/LLZO/LCO battery with such an all-ceramic cathode/electrolyte exhibits high cycling stability and high rate performance, constituting a significant step toward the practical applications of SSBs.