Surface tailoring of zinc electrodes for energy storage devices with high-energy densities and long cycle life

Zinc (Zn) ion based capacitors (ZICs) have been considered to be a new emerging energy storage device due to their high energy density and long cycle life. However, it is still challenging to overcome the limitation of ZICs with the low power densities and poor rate performance because of their low ion diffusion ability at high current densities during the cycling. Hence, we propose a novel surface modification strategy for the development of the rough surface and high surface area of Zn electrodes as the anode material so as to improve the ion diffusion ability at the high current densities. The energy storage performance of the surface-tailored Zn electrodes is significantly improved with the high specific capacitance (353 F g^-1 at the current density of 0.5 A g^-1), excellent high-rate performance (62 F g^-1 at the current density of 10.0 A g^-1), and remarkable cycling stability of 99% after 2000 cycles. This improved electrochemical performance is discussed and explained in terms of surface roughness and surface area. Our fining suggests that the surface engineering is a powerful approach for the potential applications of ZICs.