Unveiling the critical role of interfacial ionic conductivity in all-solid-state lithium batteries

Advancement of all-solid-state lithium-ion (Li+) batteries (ASSLIBs) has been hindered by the large interfacial resistance mainly originating from interfacial reactions between oxide cathodes and solid-state sulfide electrolytes (SEs). To suppress the interfacial reactions, an interfacial coating layer between cathodes and SEs is indispensable. However, the kinetics of interfacial Li+ transport across the coating layer has not been well understood yet. Herein, we tune the interfacial ionic conductivity of the coating layer LiNb0.5Ta0.5O3 (LNTO) by manipulating post-annealing temperature. It is found that the interfacial ionic conductivity determines interfacial Li+ transport kinetics and enhancing the interfacial ionic conductivity can significantly boost the electrochemical performance of SE-based ASSLIBs. A representative cathode LiNi0.5Mn0.3Co0.2O2 coated by LNTO with the highest interfacial ionic conductivity exhibits a high initial capacity of 152 mAh.g−1 at 0.1 C and 107.5 mAh.g−1 at 1 C. This work highlights the importance of increasing interfacial ionic conductivity for high-performance SE-based ASSLIBs. This work reveals the significance of interfacial ionic conductivity and its effect on the electrochemical performance of all-solid-state lithium-ion batteries (ASSLIBs), suggesting that enhancing the interfacial ionic conductivity of the interfacial coating layer is crucial for achieving high-performance SE-based ASSLIBs. [Display omitted] •The interfacial layers (LiNb0.5Ta0.5O3) with various Li+-conductivities were engineered on the LiNi0.5Mn0.3Co0.2O2 surface.•The interfacial ionic conductivity determines interfacial Li+ transport kinetics.•Enhancing the interfacial ionic conductivity can significantly boost the electrochemical performance of ASSLIBs.•LiNi0.5Mn0.3Co0.2O2 coated by the highest Li+-conductive LNTO demonstrates the best electrochemical performance.