Spherical Vanadium Pentoxide Cathode for Zinc-Ion Hybrid Supercapacitors

Abstract

Zinc-ion hybrid supercapacitors (ZIHS), as a promising energy storage device, often face challenges such as structural distortion and capacity fading due to sluggish Zn2+ diffusion and unstable interfacial reactions. In order to solve this problem, a spherical micro–nano structure (spherical V2O5)/gel electrolyte (PAM-ZnSO4) was designed. The integration of mesoporous spherical V2O5 with a flexible PAM-ZnSO4 hydrogel electrolyte establishes efficient Zn2+ transport channels while enhancing the mechanical robustness of the device. The mesoporous channel of spherical V2O5 can accelerate the transport of Zn2+, and its highly crystalline surface stabilizes the interfacial reaction. Electrochemical analysis confirms that the structure can reduce the diffusion barrier and homogenize the ion flow, thereby inhibiting structural distortion and capacity attenuation. The results show that the constructed spherical V2O5 cathode achieves a surface capacitance of 221.9 mF cm–2 and a high energy density of 123.3 μWh cm–2 at 1 mA cm–2, and the capacity retention rate exceeds 80% after 10,000 cycles. The flexible device also exhibits excellent performance of 197 mF cm–2, showing good potential for wearable applications. This work explores a feasible way for the application of V2O5 cathodes in ZIHS.