In-situ Raman investigation and application of MXene-stabilized polypyrrole composite for flexible aqueous batteries
Lingyun Li, Jing Xu, Minjie Shi, Jing He, Jintian Jiang, Kun Dai, Zhimin Jiang, Chao Yan
Abstract
Although polypyrrole (PPy) has been recognized as a promising organic electrode for rechargeable aqueous batteries (RABs), the practical application is still restricted by its rapid capacity fading after repeated cycles. Herein, a multilayer structural MXene-stabilized PPy (MXene@PPy) composite has been purposefully designed via a facile dip-coating approach, wherein the MXene coating effectively inhibits the structural degradation and irreversible redox reaction of PPy during the electrochemical process, demonstrated by electrochemical measurements combined with in-situ Raman investigation. Density functional theory (DFT) calculation further confirms the obvious electron transfer from MXene to PPy, leading to the formation of electron-rich region on PPy and hole-rich region on MXene, thereby promoting the redox reaction of PPy in the MXene@PPy composite with increased density of states (DOS). As an electrode, the MXene@PPy composite exhibits a large specific capacity of 124.9 mAh g−1 at 1.0 mA cm−2, high coulombic efficiency of ∼100%, superior charge-transfer capability, excellent rate performance and long-term cycling stability with high capacity retention of ∼80.3% over 2500 cycles in acidic aqueous electrolyte. For real application, a high-performance flexible RAB device constructed with such MXene@PPy composite electrode has been substantiated as the efficient power source, revealing its potential applications in high-safety portable/wearable electronics.