Electrospun SnO₂/Co₃O₄ Core–Shell Nanofibers Decorated with ZnO for High Performance Asymmetric Supercapacitors

This study presents the design and synthesis of ternary SnO₂/Co₃O₄/ZnO heterostructured nanofibers fabricated through electrospinning and wet-chemical techniques for high-performance asymmetric supercapacitors (ASCs). Structural analyses confirmed the successful formation of coupled oxide phases with uniform elemental dispersion in a porous fibrous network. The unique core–shell configuration and hierarchical architecture enabled efficient charge transport, high surface area, and abundant electroactive sites. Electrochemical evaluation revealed superior performance of the SnO₂/Co₃O₄/ZnO electrode compared to binary counterparts, achieving a specific capacitance of 275 F/g at 1 A/g, an energy density of 36.6 Wh/kg, and excellent cycling stability with 89.6% capacitance retention after 10,000 cycles. The low charge-transfer resistance and improved ion diffusion behavior confirmed the synergistic interaction among the three oxides. A practical device demonstration further validated the electrode’s ability to power small electronics, highlighting its real-world applicability. These results demonstrate that rational ternary heterostructuring effectively integrates the redox activity of Co₃O₄, the stability of SnO₂, and the conductivity of ZnO, offering a promising route for developing next-generation high-energy, durable supercapacitors.