Tremella-like Vanadium\nTetrasulfide as a High-Performance\nCathode Material for Rechargeable Aluminum Batteries

Abstract

Rechargeable aluminum batteries (RABs) are gaining widespread\nattention\nfor large-scale energy storage applications as a result of their high\nenergy densities, high security, and abundance. The key to sustain\nthe progress of RABs lies in the quest for the proper cathode materials\nwith prominent capacity and reversible cycle life. Herein, we propose\na tremella-like VS₄ as a cathode material aiming to tackle\nthis problem. Obtained from a morphology modification process, VS₄ with a unique nanosheet structure provides sufficient active\nsites for intercalation and conversion reactions, shortens the transport\npaths for charge carrier ions, and facilitates the infiltration process\nfor electrolyte. The RAB with the VS₄ cathode exhibits\nexcellent electrochemical performance, including outstanding specific\ncapacity (407.9 mAh g^–1) and stable cycling performance\n(∼300 cycles at a high current density). The energy storage\nmechanism has been comprehensively investigated and is confirmed to\nbe a combination of the intercalation/deintercalation of Al³⁺ and AlCl₄^– ions and conversion reaction\nby various techniques and DFT calculation. Our study not only provides\na peculiar and simple strategy for the rational design of metal sulfide\ncathode materials with high capacity and long-term stability but also\nproposes a specific energy storage mechanism that guides the development\nof cathode materials of RABs in the future.