Boosting the Capacitance of Aqueous Zinc-Ion Hybrid Capacitors by Engineering Hierarchical Porous Carbon Architecture

Abstract

With the merits of having excellent safety, being low cost and being environmentally friendly, zinc-ion hybrid supercapacitors (ZHSCs) are expected to be widely used in large-scale energy storage and flexible wearable devices. However, limited by their sluggish kinetic process, ZHSCs suffer from low-specific capacity and poor cycling stability at high cathode mass loading. Herein, a novel designed oxygen-rich hierarchical porous carbon (HPOC) is obtained by a one-step strategy of synchronous activation and templated for high-performance ZHSCs. The fabricated ZHSCs with HPOCs show significant improvement in Zn-ion storage capability, with a capacity of 209.4 mAh g−1 at 0.1 A g−1 and 108.3 mAh g−1 at 10 A g−1. Additionally, the cycling stability is excellent, with 92.3% retention after 4000 cycles. Furthermore, an impressive areal capacity of 1.7 mAh cm−2 is achieved, even with a high mass loading of 12.5 mg cm−2. More importantly, the flexible quasi-solid state ZHSCs also show a considerable capability (183.5 mAh g−1 at 0.1 A g−1) and a high energy density of 178.0 Wh kg−1. This promising result suggests a valuable route to produce functional nanocarbon materials for zinc storage applications.