Towards High-Performance Zinc-Based Hybrid Supercapacitors via Macropores-Based Charge Storage in Organic Electrolytes.

Abstract

Zn-based aqueous supercapacitors are attracting extensive attention. However, most of the reported long-life and high-power performances are achieved with low Zn-utilization (<0.6 %) and low mass loading in cathode (<2 mg cm-2 ). And, many obtained high energy densities are generally evaluated without considering the mass of Zn-anode. Herein, we propose a Zn-based hybrid supercapacitor, involving a metal organic framework derived porous carbon cathode, a Zn-anode and an N, N-dimethylformamide (DMF)-based electrolyte containing Zn2+ . We demonstrate that the charge storage of cathode mainly occurs in macropores, showing high rate performance at high mass loading (40 mg cm-2 ). Furthermore, the aprotic nature of electrolyte and formation of Zn2+ -DMF complex avoid the Zn-corrosion and dendrite formation. Therefore, the supercapacitor shows a long-life (9,000 cycles) with a high Zn-utilization (2.2 %). When calculated with the total mass of cathode (40 mg cm-2 ) and Zn-anode, the energy density reaches 25.9 Wh kg-1 .