Hyperstable low-tortuosity fast ion nanochannels for MXene electrodes

Abstract

The development of flexible MXene-based electrodes with hyperstable ion nanochannels and low tortuosity, remains daunting challenging for long-term wearable electronic devices. This paper presents a hydrogen-bonding enhanced holey MXene (HC-HMXene) electrode with maximum ion accessibility, optimized ion transport pathways, and hyperstable ion nanochannels. Specifically, three roles of introducing in-plane mesopores, reducing the lateral dimensions, and increasing the interlayer spacing in HMXene film notably enhance the electrolyte permeation efficiency and shorten the ion transport paths of the electrode (resulting in a 78.7-fold decrease in tortuosity). Thus, the constructed HC-HMXene electrode exhibits 41.1 times higher diffusion coefficient and 2.3 times higher specific capacitance than those of closely restacked film electrode with the same mass loading of MXene. Furthermore, the aramid nanofibers introduced among the MXene layers as interlocking agents bond the nanosheets via hydrogen interaction and significantly enhance the stability of the ion channel. Consequently, the HC-HMXene film effectively resists swelling behavior and maintains good structural stability in aqueous media. Moreover, the flexible sensing integrated system, powered by a HC-HMXene-based zinc ion microcapacitor, exhibits promising application prospects in real-time monitoring human physiological characteristics.