Electroactive Ionic Polymer of Intrinsic Microporosity for High-Performance Capacitive Energy Storage.

Here, we report an ionic polymer of intrinsic microporosity (PIM) as a high-functioning supercapacitor electrode without the need for conductive additives or binders. The performance of this material is directly related to its large accessible surface area. By comparing electrochemical performance between a porous viologen PIM and a non-porous viologen polymer, we reveal that the high energy and power density are both due to the ability of ions to rapidly access the ionic PIM. In 0.1 M H 2 SO 4 electrolyte, a pseudocapacitve energy of 315 F g -1 is observed, whereas in 0.1 M Na 2 SO4, a capacitive energy density of 250 F g -1 is obtained. In both cases, this capacity is retained over 10,000 charge-discharge cycles, without the need for stabilizing binders or conductive additives even at moderate loadings (5 mg cm -2 ). This desirable performance is maintained in a prototype symmetric two-electrode capacitor device, which had >99% Coloumbic efficiency and a <10 mF capacity drop over 2000 cycles. These results demonstrate that ionic PIMs function well as standalone supercapacitor electrodes and suggest ionic PIMs may perform well in other electrochemical devices such as sensors, ion-separation membranes, or displays. This article is protected by copyright. All rights reserved.