Stepwise MXene and MOF conversion assisted ultrathin dual-carbon-protected V2O3 nanosheets for ultrafast and durable Zn-ion storage

Abstract

Vanadium oxides with high theoretical capacity are attractive cathodes for aqueous zinc-ion batteries (AZIBs), while their practical usage is still obstructed by the vanadium dissolution, structure deterioration, and sluggish reaction kinetics during cycles. Herein, ultrathin dual-carbon-protected V₂O₃ nanosheets are developed to tackle these issues through stepwise MXene and MOF conversion. As-designed C@V₂O₃@C nanosheets exhibit structural merits of large surface area, porous structure, small size, high V₂O₃ content, and ultrathin inner/outer dual-carbon matrix. For Zn-ion storage, these structural advantages endow a C@V₂O₃@C cathode with good capacity retention of ∼100% at 1 A g⁻¹ and excellent cycling performance over 3000 cycles. Remarkably, it manifests an exceptional rate capability of 402 mA h g⁻¹ at 50 A g⁻¹, outperforming most reported cathode materials for AZIBs. Combined in/ex situ experiments and theoretical calculation further illuminate the reaction mechanism of V₂O₃ with initial activation process and subsequent reversible H⁺/Zn²⁺ co-insertion/extraction reactions, along with the effect of carbon matrix on the superior performance by suppressing V dissolution, enhancing the structural stability, improving the pseudocapacitive behavior, and boosting the electron/ion transportation ability of the vanadium oxide cathode. As a proof of concept, as-assembled flexible ZIBs with excellent battery performance can be integrated into a self-powered sensor system for human motion monitoring, highlighting the potential application of the C@V₂O₃@C cathode for wearable electronics.