MXenes, a new family of two-dimensional transition metal carbides, nitrides and carbonitrides, have emerged as promising materials for electrical energy storage (EES) systems due to their superior properties, such as high electronic conductivity, excellent mechanical capability, and hydrophily. These properties of MXenes are closely related to their structure and surface functional groups, and directly decided and readily tailored by means of synthesis methods applied. The properties of MXenes have a determining effect on the electrochemical performance of EES systems. This review begins with the intrinsic connections between properties and crystal structure, chemical composition and surface chemistry of MXenes as background. Then, the effects of latest synthesis on MXenes’ properties are systematically scrutinized, including the effects of precursors, processing parameters, the etching, delaminating, and compositing strategies of MXenes. Further focus is turned to the state-of-the-art progress of MXenes and their composites acting as cathodes, anodes, current collectors, electrolyte additives, and conductive binder in supercapacitors, monovalent (Li⁺, Na⁺, K⁺, and halogen anion) ion batteries, and multivalent (Zn²⁺, Mg²⁺, Ca²⁺, and Al³⁺) ion batteries. The synthesis-property-application relationships in MXenes for desired EES devices are highlighted. Finally, the critical challenges and perspectives are discussed for the future development of MXenes in advanced supercapacitors and rechargeable batteries.

MXenes 是一种新的二维过渡金属碳化物、氮化物和碳氮化物家族，由于其优异的性能，如高电子电导率、优异的机械性能和亲水性，已成为电能存储(EES) 系统的有前途的材料。MXene 的这些性质与其结构和表面官能团密切相关，并且可以通过所应用的合成方法直接决定和轻松定制。MXene 的特性对 EES 系统的电化学性能具有决定性影响。本综述首先以 MXene 的性质与晶体结构、化学成分和表面化学之间的内在联系为背景。然后，系统地研究了最新合成对 MXene 性能的影响，包括 MXene 前驱体、加工参数、蚀刻、分层和复合策略的影响。进一步的重点转向 MXene 及其复合材料的最先进进展，这些复合材料在超级电容器、一价（Li ⁺、Na ⁺、K ⁺和卤素）阴离子）离子电池和多价（Zn ²⁺、Mg ²⁺、Ca ²⁺和Al ³⁺）离子电池。重点介绍了所需 EES 器件的 MXene 中的合成-性能-应用关系。最后，讨论了 MXene 在先进超级电容器和可充电电池中未来发展的关键挑战和前景。