Nanoporous Conducting Polymer Nanowire Network-Encapsulated MnO 2 -Based Flexible Supercapacitor with Enhanced Rate Capability and Cycling Stability.

Transition-metal-oxide-based electrochemical electrodes usually suffer from poor electron and ion transport, leading to deteriorated rate performance and cycling stability. Herein, we address these issues by developing a facile "conducting encapsulation" strategy toward a nanoporous PEDOT nanowire/MnO 2 nanoparticle/PEDOT nanowire composite electrode. Through encapsulation of the PEDOT nanowire network, the overall electrochemical performance of the resultant composite electrode is substantially enhanced. Specifically, the rate capability and capacitance retention are improved by ∼48.2 and ∼33%, respectively, which are 89.8% at 0.8-40 mA/cm 2 and 93% after 3000 charge/discharge cycles at 2.0 mA/cm 2 , respectively. Moreover, the specific capacitance is increased by ∼6 times of that of the MnO 2 @PEDOT NW electrode at ∼200 mA/cm 2 . We find that a nanoporous conducting nanowire network that encapsulates a MnO 2 nanoparticle layer can provide efficient electron and ion transport paths and stabilize the structure of MnO 2 from collapse during charge/discharge cycling and mechanical deformation. This strategy can be applied to other pseudocapacitive material-based electrochemical electrodes, such as transition-metal oxides and conducting polymers.