Punching holes on paper-like electrodes: An effective strategy to enhance rate performance of supercapacitors

Abstract

Paper-like materials composed of stacked nanosheets are emerging as promising new electrodes for supercapacitors because of reduced weight (without the need of binder or additive) as well as flexibility. However, such dense layered structure greatly affects their rate performance. Here, an effective and simple method of punching holes on paper-like electrodes, inspired by microneedle roller cosmetic therapy, is put forward to improve the ions transfer feature at high rates. Taking 230 μm-thick graphite paper (GP) as an example, with 200 holes/cm2 punched, the capacitance retention is 2.9 times higher than that of unpunched GP when the scan rate increases from 10 to 1000 mV/s, indicating the remarkably improved rate capability. To demonstrate the feasibility of this strategy, a symmetrical supercapacitor is assembled, and it shows the obvious advantage in lighting LED, especially when charging at a high scan rate. The enhancement of rate performance is attributed to the increase of ion diffusion at the lateral boundary during the fast charge-discharge process. Punching holes on electrodes is a universal, low cost, and environmentally friendly approach, and such strategy has great potential for preparing other paper-like electrodes with good rate capability for various energy storage devices.