Sec-butanol as a bifunctional electrolyte additive to effectively improve electrochemical performance of V2O5//Zn battery

Abstract

Aqueous Zn-ion batteries (AZIBs) are considered as a promising energy storage device owing to their inherent safety, cost-effectiveness, and environment friendliness. However, their commercialization is hindered by critical challenges, including severe dendrite growth and poor electrochemical performance stemming from an inefficient cathode-electrolyte interaction, thus leading to inevitable short circuits and significant capacity decay. Herein, sec-butanol (SBT) is applied as a bifunctional electrolyte additive in a 1 M Zn(ClO₄)₂ aqueous electrolyte to achieve high-performance AZIBs. Profiting from the strong coordination and adsorption capabilities, SBT effectively reshapes the solvation structure of Zn²⁺ ions in the electrolyte and inhibits the two-dimensional diffusion of Zn²⁺ ions. Moreover, SBT also enhances the wettability of the electrolyte on the V₂O₅ cathode, facilitating better electrode–electrolyte interactions. Benefiting from those positive effects, the Cu//Zn half cell with SBT demonstrates stable cycling performance over 1000 cycles at 5 mA cm⁻² in the modified electrolyte, markedly outperforming cells with pure aqueous electrolyte. Most notably, the V₂O₅//Zn full battery achieves a remarkable capacity of 247.78 mAh g⁻¹ at 4 A g⁻¹ in the modified electrolyte, significantly surpassing the performance of systems without SBT.