Reviewed by Mila PereraOct 28 2022
Two-dimensional transition-metal carbides (MXenes) are extremely competitive in electrochemical energy storage due to their highly hydrophilic surfaces and outstanding metal conductivity. However, the easy stacking-up inclination of interlayers would result in decreased ion accessibility and available transport paths within MXenes, limiting their electrochemical performance.
Based on the design of nanoscale ion channels, MXene electrodes with maximized ion accessibility and high mechanical strength are constructed and used for high-capacity Zinc-ion energy storage. The design of in-plane ion channels provides a simple, efficient, and scalable approach to improve the electrochemical energy storage capacity of MXenes and other 2D materials. Image Credit: Science China Press
Numerous techniques have been developed to fully utilize MXenes’ advantages in electrochemical energy storage and prevent self-stacking behavior. Hole etching is one of the strategies employed to improve transport efficiency and ion accessibility, which can be applied to construct high-performance energy storage devices.
Particularly, chemical etching’s ability to produce nanoscale ion-channel electrodes offers promising application potential. Controlling the level of chemical etching for effective manipulation of electrochemical energy storage still poses significant difficulties.
In this study published by Science Bulletin, MXene nanosheets with in-plane ion channels are created by chemical oxidation and used as electrodes to create self-healing Zinc-ion micro-capacitors (ZIMC) with exceptional anti-self-discharge performances.
This work is based on the design concept of nanoscale in-plane ion channels. While maintaining the superior mechanical strength and electrical conductivity of large-sized MXene nanosheets, the in-plane ion-channel equipped MXene nanosheets can reduce the ions’ transit distance and improve the electrochemical performance of ZIMC.
The self-healing MXene-based Zinc-ion micro-capacitor that was created has high areal specific capacitance (532.8 mF cm–2) at current densities of 2 mA cm–2, a low self-discharge rate of 4.4 mV h–1, and a high energy density of 145.1 μWh cm–2 at power densities of 2800 μW cm–2.
The developed ZIMC has significant promise for use in flexible electronics due to its superior anti-self-discharge and self-healing characteristics, which could support microelectronic devices for an extended period.
MXene electrodes with optimum ion accessibility and excellent mechanical strength are created and employed for high-capacity zinc-ion energy storage based on the construction of nanoscale ion channels.
An in-plane ion channel design provides a simplified, practical, and scalable method to significantly increase the electrochemical energy storage capability of MXenes and other 2D materials.
Journal Reference
Cheng, Y. et al. (2022) Maximizing the ion accessibility and high mechanical strength in nanoscale ion channel MXene electrodes for high-capacity zinc-ion energy storage. Science Bulletin. doi:10.1016/j.scib.2022.10.003