One‐dimensional NiS‐CNT@Li7P3S11 nanocomposites as ionic/electronic additives for LiCoO2 based all‐solid‐state lithium batteries

Abstract

Increasing active material content is critical to realize high energy density for all-solid-state lithium batteries (ASSLBs), which is generally impeded by limited ionic/electronic conductions in cathode layer. Herein, one-dimensional NiS-CNT@Li7P3S11 nanocomposites are synthesized by wet chemistry method and possess high mixed ionic/electronic conductivities. When employed as additives for LiCoO2, the NiS-CNT@Li7P3S11 nanocomposites can efficiently improve the electrochemical performances of LiCoO2 cathode in the ASSLBs. Specifically, the resultant Li/75%Li2S-24%P2S5-1%P2O5/Li10GeP2S12/LiCoO2-5%NiS-CNT@Li7P3S11 ASSLBs with 70 wt% LiCoO2 content deliver a reversible capacity of 114.3 mAh g−1 after 50 cycles under 0.1 C and 99.6 mAh g−1 at 0.5 C after 100 cycles at room temperature. Even if the active material LiCoO2 content increases to 80%, a high reversible discharge capacity of 124 mAh g−1 can be achieved at 0.05 C after 25 cycles. Obviously, the excellent electrochemical performances are attributed to the improved ionic/electronic conductivities with assistance of NiS-CNT@Li7P3S11. This work provides an efficient strategy to design cathode materials with high ionic/electronic conductivities and paves the way for the practical application of ASSLBs.