Electronic/Ionic Conductive MoS₆-Based Composites for All-Solid-State Lithium Batteries

The transition metal polysulfide cathodes driven by anion redox show high reversible specific capacity, demonstrating great application potential in all-solid-state lithium batteries (ASSLBs). However, their inferior electron/ion conductivities and large volume expansion are critical challenges. In this work, the MoS₆-10%rGO@15%Li₇P₃S₁₁ cathode material is synthesized and utilized in ASSLBs. The cooperation of reduced graphene oxide (rGO) can significantly mitigate the volume changes of MoS₆ during the cycling and enhance electronic conductivity of the cathode from 2.56 × 10^-8 S cm^-1 for MoS₆ to 0.28 S cm^-1 for MoS₆-10%rGO. Besides, a thin Li₇P₃S₁₁ solid electrolyte layer is <i>in situ</i> coated on the surface of MoS₆-10%rGO, realizing intimate contact. Meanwhile, the ionic conductivity of the MoS₆-10%rGO@15%Li₇P₃S₁₁ composite reaches 8.4 × 10^-4 S cm^-1, 3 orders of magnitude greater than that of MoS₆ with 2.8 × 10^-7 S cm^-1. The ASSLBs utilizing the MoS₆-10%rGO@15%Li₇P₃S₁₁ cathode deliver an initial discharge specific capacity of 1111.97 mAh g^-1 at 0.1 A g^-1. Notably, it achieves a reversible ultrahigh energy density of 1750.94 Wh kg^-1 based on the active material at the second cycle. Furthermore, the batteries possess superior cycling stability, maintaining a discharge specific capacity of 729.53 mAh g^-1 after 500 cycles at 0.5 A g^-1. This work provides a high-energy-density active material for ASSLBs.