Rational design of MXene-based films for energy storage: Progress, prospects

Two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides (MXenes) have been synthesized and developed into a wide range of applications including energy storage, optoelectronics, electromagnetic interference shielding, biomedicine, and sensors, etc. Compared to other 2D materials, MXenes possess a unique set of properties such as superior mechanical strength, outstanding hydrophily, and excellent dispersion quality, making them particularly suitable for fabricating films/membranes featuring designed microstructures and tunable nanochannels. 2D MXene-based films (MBFs) have demonstrated excellent ion storage, electron transport and ionic selectivity properties for electrochemical energy storage and have received enormous interest in recent years. Compared with conventional electrode materials and structures, MBFs show great advantages in the aspects of flexibility, tailorability and functionality, which are suitable for flexible, portable, and highly integrated energy storage systems. This review summarizes recent advances and well-developed strategies of the MBFs design and fabrication toward applications of metal-ion batteries (MIBs, including Li, Na, K-ions), lithium-sulfur (Li-S) batteries and supercapacitors (SCs). Special attentions are given to the design principles of MBFs based microstructures, inter-layer nanochannels and in-plane nanochannels for energy storage. Finally, the current challenges and promising perspectives of the MBFs for energy storage devices are presented. Two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides (MXenes) have been synthesized and developed into a wide range of applications including energy storage, optoelectronics, electromagnetic interference shielding, biomedicine, and sensors, etc. Compared to other 2D materials, MXenes possess a unique set of properties such as superior mechanical strength, outstanding hydrophily, and excellent dispersion quality, making them particularly suitable for fabricating films/membranes featuring designed microstructures and tunable nanochannels. 2D MXene-based films (MBFs) have demonstrated excellent ion storage, electron transport and ionic selectivity properties for electrochemical energy storage and have received enormous interest in recent years. Compared with conventional electrode materials and structures, MBFs show great advantages in the aspects of flexibility, tailorability and functionality, which are suitable for flexible, portable, and highly integrated energy storage systems. This review summarizes recent advances and well-developed strategies of the MBFs design and fabrication toward applications of metal-ion batteries (MIBs, including Li, Na, K-ions), lithium-sulfur (Li-S) batteries and supercapacitors (SCs). Special attentions are given to the design principles of MBFs based microstructures, inter-layer nanochannels and in-plane nanochannels for energy storage. Finally, the current challenges and promising perspectives of the