Performance promotion of NVO cathodes by regulating interfacial hydrophilicity and ion bonding energy

Abstract

The impact of different binders, polyvinylidene fluoride, polyvinyl alcohol (PVA), and polyethylene oxide, on the electrochemical performance of NH₄V₄O₁₀ (NVO) cathodes in aqueous zinc-ion batteries (AZIBs) is systematically examined in this work. Through a combination of experimental and computational analyses, it is demonstrated that the hydrophilicity of the binders, along with the ionic interactions with Zn²⁺ ions, are critical factors influencing the electrochemical performances of the NVO cathodes. The electrochemical characterization indicates that the NVO cathode with PVA binder (PVA-NVO) achieves a remarkable reversible capacity of 477.9 mAh g⁻¹ at 0.5 A g⁻¹, which is retained as 321.0 mAh g⁻¹ even at a high current density of 10 A g⁻¹. Notably, PVA-NVO reserves 79.7 % of the initial capacity after 3000 charge-discharge cycles at 10 A g⁻¹. These findings highlight the significant role of binders in facilitating ion transport at the interface between NVO and the aqueous electrolyte, providing valuable insights and practical examples for advancing the development of AZIBs with high energy density.