Rational cathode design for efficient solid-state diffusion in solid-state batteries

Severe risks of explosion and fire hazards with traditional lithium-ion batteries (LIBs) using liquid organic electrolytes have attracted all-solid-state batteries (ASSBs) due to its nonflammable characteristics. Among the various solid electrolytes (SEs), Li10GeP2S12 (LGPS) and garnet-type oxide such as Li7La3Zr2O12 (LLZO) are evaluated as promising candidates for next-generation solid-state batteries due to high ionic conductivity and possibility for mass production. Recent research is mainly about synthesis, conduction mechanism, and especially ionic conductivity. However, the promising properties of bulk SEs can not be guaranteed to exhibit excellent performance in practical applications to full cells. The contact and interface issues between SEs and active materials must be solved for actual cell driving in ASSBs having a solid-solid ionic conduction system. In this perspective, discussion, approaches, and future research directions in relation to ASSBs’ performance are provided. Through the careful examination of the cathode design, it is expected that enhanced solid-state diffusion between the SE and cathode will contribute toward more sustainable long-term ASSBs operation.