Engineering Hollow Porous Carbon-Sphere-Confined MoS2 with Expanded (002) Planes for Boosting Potassium-Ion Storage.

Abstract

Potassium-ion batteries (PIBs) are emerging as promising next-generation electrochemical storage systems for their abundant and low-cost potassium resource. The key point of applying PIBs is to exploit stable K-host materials to accommodate the large-sized potassium ion. In this work, a yolk-shell structured MoS2@hollow porous carbon-sphere composite (MoS2@HPCS) assembled by engineering HPCS-confined MoS2 with expanded (002) planes is proposed for boosting potassium-ion storage. When used as a PIB anode, the as-synthesized MoS2@HPCS composite shows superior potassium storage performance. It delivers a reversible capacity of 254.9 mAh g-1 at 0.5 A g-1 after 100 discharge/charge cycles and maintains 126.2 mAh g-1 at 1 A g-1 over 500 cycles. The superior potassium-ion storage performance is ascribed to the elaborate yolk-shell nanoarchitecture and the expanded interlayer of the MoS2 nanosheet, which could shorten the transport distance, enhance the electronic conductivity, relieve the volume variation, prevent the self-aggregation of MoS2, facilitate the electrolyte penetration, and boost the intercalation/deintercalation of K+. Moreover, the potential application of the MoS2@HPCS composite is also evaluated by assembled K-ion full cells with a perylenetetracarboxylic dianhydride cathode. Accordingly, the as-developed synthetic strategy can be extended to manufacture other host materials for PIBs and beyond.