Molecular reconfigurations enabling active liquid–solid interfaces for ultrafast Li diffusion kinetics in the 3D framework of a garnet solid-state electrolyte

Developing all solid-state lithium ion batteries (ASSBs) is a promising way to solve safety issues surrounding liquid-based batteries, yet the interfacial issues make ASSBs insufficient in providing long-term cycling performance or acceptable rate capabilities. Herein, we propose a new kind of electrolyte configuration, comprising a 3D ceramic framework filled with plastic crystals on the surface, to effectively enhance the interfacial Li diffusion kinetics. The soft plastic crystals enable not only excellent contact with the rigid framework and cathodes, but also rapid molecular reorganization to accommodate the interfacial Li, achieving ultrafast Li diffusion globally via the 3D framework. As a result, the ASSBs with the proposed electrolyte (i.e. garnet-succinonitrile composites) show an extremely low interfacial resistance, providing an initial discharge capacity of 165.3 mA h g−1 and a 95% capacity retention after 100 cycles when using a LiNi0.5Co0.2Mn0.3O2 (NCM) cathode. Furthermore, these NCM-ASSBs using the designed electrolyte even exhibit better cycling performance within a higher voltage range (2.8–4.5 V) than conventional lithium ion batteries (LIBs) using conventional liquid electrolytes (LEs). A capacity retention rate of 92% for 3DLLZO-PCE is demonstrated, against the 85% for LE-LIBs after 50 cycles. We believe that this strategy provides useful guidance for constructing high-performance ASSBs, which is important in their further commercialization.