Rational design of multi-channel continuous electronic/ionic conductive networks for room temperature vanadium tetrasulfide-based all-solid-state lithium-sulfur batteries

Abstract

All-solid-state lithium-sulfur batteries can completely overcome safety issues and fast capacity fading by substitution of organic liquid electrolytes and eliminating polysulfide shuttle. However, the insulating nature of sulfur and large volume change still inhibit all-solid-state lithium-sulfur batteries from achieving favorable electrochemical performances. In this work, linear-chain compound vanadium tetrasulfide (VS4) anchored reduced graphene oxide (rGO-VS4) nanocomposites are successfully synthesized via a simple one-pot hydrothermal method. Furthermore, 10%rGO-VS4@Li7P3S11 nanocomposites with multi-channel continuous electronic/ionic conductive network are prepared by a facile liquid-phase deposition reaction and further employed as an alternative material for sulfur cathode in all-solid-state lithium batteries. Typically, Li/75%Li2S-24%P2S5-1%P2O5/Li10GeP2S12/10%rGO-VS4@Li7P3S11 all-solid-state lithium-sulfur batteries deliver high reversible capacity of 611 mAh g−1 at 0.1 A g−1 after 100 cycles, corresponding to 853 mAh g−1 based on the mass of sulfur. Even after being cycled at 0.5 A g−1 between 1.5 and 3.0 V for 500 cycles, it still shows the discharge specific capacity of 333 mAh g−1 based on sulfur content with excellent cycling stability. The excellent rate capability and cycle performances can be ascribed to the multi-channel continuous electronic/ionic conductive networks and the improved structural stability. In addition, the electrochemical reaction kinetics and capacity contributions as well as reaction mechanisms of 10%rGO-VS4@Li7P3S11 in all-solid-state lithium batteries were revealed by ex-situ characterization techniques.