Coupling effect of vacancy defects and multi-adsorption sites in porous carbon cathode for high-performance aqueous zinc-ion hybrid capacitors

Abstract

Aqueous zinc-ion hybrid capacitors (AZICs) are considered to be an auspicious electrochemical energy storage device due to their superior cycling stability and high power density, but the inadequate electrolyte ions storage active sites and inconsistent pore sizes of porous carbon materials result in poor energy storage performance. Thus, unveiling the interplay between the heteroatom dopant, carbon vacancy defects, and pore sizes in carbon cathode is essential for promoting the Zn2+ and SO42− ions storage capability. In this work, N, S co-doped multi-adsorption sites porous carbon materials with abundant vacancy defects (HC-0.2) are successfully prepared by a facile direct activating/annealing method, which exhibit strong interaction adsorption ability and boost ion and electron transfer. In terms of zinc storage performance, the HC-0.2 cathode exhibits a high capacity of 245.8mAh/g at 0.2A/g and a long cycling stability with 82.3 % capacity retention over 10,000 cycles at 10A/g. Moreover, the HC-0.2//Zn device has a supreme energy density of 164.1Wh/kg and an ultrahigh power density of 30.1 kW/kg. Meanwhile, through theoretical calculations, the N, S multi-adsorption sites, a suitable pore size, and vacancy defects of the HC-0.2 cathode are crucial for improving the Zn2+ and SO42− ions storage capability. This work can provide a comprehensive understanding of the coupling effect of the multi-adsorption sites and vacancy defects of N, S co-doped porous carbon materials on energy storage capability.