Fast self-transformation of in-situ confined V₂O₃ nanodots by a scalable carbon nanosheet with outstanding rate capability and stability for advanced aqueous zinc batteries

Aqueous zinc-ion batteries (ZIBs) are desirable for safe and large scale energy storage. However, the lack of suitable cathodes that show excellent comprehensive performance is still key reason that hinders the development of ZIBs. Herein, a laminar hydrated vanadium oxide composites (VOH ND@C) with outstanding rate capability and stability are comprehensively designed and regulated by a fast in-situ electrochemical self-transformation process. The precursor materials (V₂O₃ ND@C) are fabricated firstly by freeze-drying method in bulk and subsequent calcination process, after which small V₂O₃ nanodots can be evenly distributed in carbon nanosheets. During electrochemical treatment process, the precursors are fast transformed into laminar hydrated vanadium oxide composites with better structure stability. It is because this strategy of integrating pre-inserted H₂O molecules and constructing carbon encapsulation are proved to be effectively inhibit volume expansion of vanadium oxide and improve electron transfer. Meanwhile, laminar composite structure and highly exposed active surface from vanadium oxide nanodots contribute to the high-rate capability. Consequently, the VOH ND@C cathode delivers high specific capacity of 452.8 mA h g^-1 at 0.2 A g^-1, and excellent rate performance of 176.5 mA h g^-1 even at 50 A g^-1. Moreover, excellent cycling stability is acquired with capacity retention 86% over 10,000 cycles. This work is expected to provide a new scalable practical route to improve V-based cathode materials for advanced ZIBs.