Achieving superior high-life-stability and stable structure for flexible fiber electrodes inspired by Bamboo rice dumpling

MnO₂ is widely recognized as promising pseudocapacitive materials to address the issue of low energy density in fiber supercapacitors. However, it severely suffers from poor cycling stability caused by structure damages. Inspired by Chinese bamboo rice dumplings, herein we demonstrate the strategy of building conductive polymer Poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires around the MnO₂ nanoparticles to address the issue. Benefiting from the tight winding of PEDOT nanowires, the flexible fiber electrode achieves a stable structure and an extraordinary cycle stability. Density functional theory calculations further reveals that the charge redistribution of MnO₂/PEDOT interface and Fe³⁺ doping during polymerization in PEDOT improve the conductivity, facilitate ion adsorption, inhibit the hydrogen evolution reaction, and expand the voltage window. Accordingly, the fiber-shaped supercapacitor based on this electrode exhibits a high cycle lifespan of 86% after 22,000 cycles with capacitance (23.5 F cm⁻³), energy density (8.32 mWh cm⁻³), power density (8000 mW cm⁻³) and voltage window of 1.6 V. Furthermore, it can withstand various angles of bending without losing capacity. Our study provides a pathway to construct MnO₂ with a stable structure and cycling life, and could be further used for developing other materials with unstable structure in flexible electronic devices.