Porosity meets robustness: design of ultralight MXene/PVA composite foams for high-performance flexible supercapacitors

Abstract

Flexible supercapacitors should not only exhibit superior electrochemical performance, but also possess high mechanical strength to maintain the structural integrity and electrochemical stability under repeated mechanical deformation. However, the conventional electrodes of flexible supercapacitors often suffer from poor mechanical properties or low specific capacitance, which significantly impedes their application in flexible electronics. Herein, MXene/PVA composite foams with porous structure were controllably fabricated to balance the mechanical strength and electrochemical performance in conventional electrodes. On one hand, the hydrogen bonding formed between MXene sheets and PVA molecules effectively improves the mechanical performance of the composite foams. On the other hand, the construction of continuous ion transport channel in MXene/PVA foams efficiently restrains restacking of MXene sheets and promotes rapid ion transport during electrochemical reaction, thus improving the electrochemical performance. Therefore, the MXene/PVA foams deliver a high tensile strength of 48.93 MPa and specific capacitance of 240.40 F g-1. More importantly, the flexible supercapacitor based on the MXene/PVA foams maintains stable electrochemical performance even under various bending conditions.