T-Nb2O5/rGO@CC anode for ultralong-life zinc-ion hybrid supercapacitors

Abstract

Zinc-ion hybrid supercapacitors (ZIHSCs) have garnered widespread attention due to their integration of the excellent characteristics of both batteries and capacitors. This study employs a synergistic strategy combining hydrothermal and high-temperature calcination methods to construct a nanosphere-structured T-Nb₂O₅ composite anode material coated with reduced graphene oxide (rGO) on a flexible carbon cloth (CC) substrate (T-Nb₂O₅/rGO@CC), in conjunction with a hierarchical super-mesoporous activated carbon cathode (ACcp@CC) derived from discarded citrus peel. The rGO coating structure suppresses the volume expansion of the internal nanostructure caused by charging and discharging, effectively enhancing mechanical stability. At the same time, the three-dimensional conductive network of rGO effectively compensates for the poor intrinsic conductivity of Nb₂O₅. The constructed ZIHSC delivers a capacitance of 718.56 mF cm^-2 at 1 mA cm^-2, and achieves a maximum energy density of 399.20 μWh cm^-2 at 1 mW cm^-2. Furthermore, after 50,000 ultralong-cycle, the capacity retention rate is 104.17%. The assembled flexible device not only possesses excellent mechanical properties but also delivers a specific capacitance of 389.89 mF cm^-2 at 1 mA cm^-2, providing long-term power for various electronic devices. This study provides a solid theoretical reference for the design of stable composite structures and the investigation of ultra-long cycling performance in niobium-based electrode materials.