In situ synthesis of a V2O3/biomass cotton-derived carbon composite for aqueous magnesium-ion batteries

Abstract

Vanadium trioxide (V₂O₃) shows potential as a cathode material for aqueous magnesium-ion batteries due to its high theoretical specific capacity. However, its low specific surface area, low electrical conductivity, and poor cycling stability limit its practical application. In this work, the V₂O₃ was successfully grown on the surface of carbonized cotton fibers (V₂O₃-C) via a hydrothermal carbonization method. The introduction of cotton-derived carbon can enhance the conductivity of V₂O₃-C and serve as a supporting scaffold, providing anchoring sites for V₂O₃. Furthermore, the nanorod/nanofiber structure provides high porosity and large surface area, which increases the electrode-electrolyte interface and facilitating rapid ion transport. The abundant -OH in cotton fibers anchor V via coordinate bonds, preventing vanadium dissolution and dramatically improving cycling stability as an AMIBs cathode. Thus, the composite shows 215 mAh g^-1 at 0.05 A g^-1 and maintains a 98.8 % retention rate after 500 cycles at 2 A g^-1. Notably, ex situ analysis confirms the charge storage mechanism is primarily Mg²⁺ intercalation/deintercalation. Furthermore, The V₂O₃-C//PTCDA full battery exhibits exceptional cycling performance with the 89.5 % capacity retention after 1400 cycles at 0.5 A g^-1. This study demonstrates the promise of combining biomass-derived materials with V₂O₃-C for high-efficiency AMIBs.