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 Li_2.3−xC_0.7+xB_0.3−xO₃ solid electrolyte interphase through the reaction between the Li_2.3C_0.7B_0.3O₃ 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.

固态电池（SSB）可以从根本上提高电池安全性。石榴石型Li ₇ La ₃ Zr ₂ O ₁₂（LLZO）被认为是SSB最有希望的固体电解质之一。然而，基于LLZO的SSB的性能受到大的阴极/电解质界面电阻的限制。只有在牺牲安全性的前提下在阴极中添加易燃的聚合物或液体电解质后，才能实现高速率和长循环的SSB。在这里，我们表明，通过将LiCoO ₂（LCO）和LLZO与Li _{2.3− x} C _{0.7+ x} B _0.3−一起热焊接，可以实现具有极低界面电阻的全陶瓷阴极/电解质通过Li _2.3 C _0.7 B _0.3 O ₃焊料与可以共形涂覆在LLZO和LCO上的Li ₂ CO ₃层之间的反应生成_x O ₃固体电解质界面相。具有这种全陶瓷阴极/电解质的全固态Li / LLZO / LCO电池具有较高的循环稳定性和高倍率性能，朝着SSB的实际应用迈出了重要的一步。