Interface Chemistry on MXene‐Based Materials for Enhanced Energy Storage and Conversion Performance

Abstract

MXenes have attracted increasing attention due to their unique advantages, excellent electronic conductivity, tunable layer structure, and controllable interfacial chemistry. However, the practical applications of MXenes in energy storage devices are severely limited by the issues of torpid reaction kinetics, limited active sites, and poor material utilization efficiency. Herein, the most-up-to date advances in the rational microstructure design to enhance electrochemical reaction kinetics and energy storage performance of MXene-based materials are comprehensively summarized. This review begins with the preparation and properties of MXenes, classified into fluorine-containing acid etching and fluoride-free etching approaches. Afterwards, the interlayer structure design and interfacial functionalization of MXenes with respect to interlayer spacing and porous structure, terminal groups, and surface defects are summarized. Then the focus turns to the construction of advanced MXene-based heterojunctions based on in situ derivation and surface self-assembly. Based on these microstructure modulating strategies, the state-of-the-art progress of MXene-based applications with respect to supercapacitors, alkali metal-ion batteries, metal-sulfur batteries, and photo/electrocatalysis are highlighted. Finally, the critical challenges and perspectives for the future research of 2D MXene-based nanostructures are highlighted, aiming to present a comprehensive reference for the design of MXene-based electrodes for electrochemical energy storage.

In Situ and Operando Characterizations of 2D Materials in Electrochemical Energy Storage Devices

“…[ 25 ] The high intrinsic electronic/ionic conductivities of MXenes render them particularly promising electrode materials. [ 26,27 ] TMDs follow an MX 2 structure, wherein M is a transition metal element (such as W, Mo, and Ti), and X is a class of chalcogen elements (such as S, Te, or Se). [ 28 ] TMDs can adopt semiconducting, metallic, and even superconducting properties depending upon their chemical composition and layer structures.…”

Opportunities and challenges for aqueous metal-proton batteries

“…Two-dimensional materials Two-dimensional transition-metal dichalcogenides (2D TMDs) such as MoS 2 and TiS 2 have been investigated in electrochemical energy storage, 56,57 and their proton-storage abilities have attracted attention. Metallic 1T-phase MoS 2 nanosheets have been prepared for supercapacitor electrodes.…”

Flexible MXene‐Based Composites for Wearable Devices

“…[ 8 ] So far, a dozen of MXenes, for example, Ti 2 C, V 2 C, Nb 2 C, Ti 4 N 3 as well as TiNbC, Ti 3 CN, Mo 2 TiC 2 have been reported to be successfully synthesized. [ 9 ] Compared to other candidates ( Table 1 ), MXenes possess unique superiorities such as outstanding electrical conductivity, large specific surface area, unique layered‐structure, excellent dispersibility in aqueous solutions and abundant terminal groups, [ 10 ] endowing them with great potentiality in various application fields including electromagnetic interference (EMI) shielding, [ 11 ] energy storage, [ 12 ] optical devices, [ 13 ] biomedical engineering, [ 14 ] and catalysis ( Table 2 ). [ 15 ] However, several drawbacks of MXenes, such as poor mechanical property, easy restacking, relatively small lateral size, and poor stability at oxygen atmosphere, greatly limit the further development of pristine MXenes in achieving highly desirable flexibility and durability for wearable electronics.…”