High-performance binder-free novel ZnCo2O4–TiN/Ni electrode for supercapacitor application

Abstract

Heterostructures comprised of metal nitrides and mixed metal oxides on 3D porous substrates are novel for the fabrication of high-performance binder-free electrodes. Herein, for the first time, we utilize the Ni 3D framework to grow hierarchical flakes-like nanosheets of ZnCo₂O₄ and thin film deposition of TiN for the fabrication of ZnCo₂O₄–TiN/Ni (ZCO-TiN/Ni) binder-free electrodes. Using the vacuum arc deposition technique to deposit TiN on Ni foam and further hydrothermal technique to grow flakes-like ZnCo₂O₄ nanosheets, the binder-free ZCO-TiN/Ni electrode exhibits a high specific capacitance of 233 mF cm⁻² at a current density of 1 mA cm⁻², enhanced rate capability of 80 % and long cycling stability of 77.6 % after 3000 cycles. Additionally, a symmetric supercapacitor assembled using ZCO-TiN/Ni electrodes shows a remarkable energy density of 19 mWh cm⁻² at a current density of 0.25 mA cm⁻² and a high power density of 493.5 mW cm⁻². Above all, the device exhibits good cyclic stability after 2000 cycles. Benefiting from the stable hierarchical microstructure of ZnCo₂O₄, the ultrahigh electric conductivity of TiN, the 3D framework of current collector, and the binder-free approach, the ZCO-TiN/Ni electrode material prepared by this approach may open new opportunities for the development of promising electrodes for supercapacitors.