Synergizing Electron and Ion Transports of Ti<sub>3</sub>C<sub>2</sub>T<sub>X</sub> MXene Fiber via Dot‐Sheet Heterostructure and Covalent Ti─C─Ti Cross‐Linking for Efficient Charge Storage and Thermal Management
Huifang Wang, Weidong Zhao, Ziting Zhang, Wenteng Hou, Leang Yin, Henghan Dai, Xinnan Zhu, Jingbo Zhou, Shaochun Tang, Wei Huang, Gengzhi Sun
Abstract
Abstract Ti 3 C 2 T X MXene with the merits of metallic conductivity, superhigh volumetric capacitance, and efficient absorption of the electromagnetic wave is considered a promising building block for fiber fabrication; nevertheless, the simultaneous improvement in electrochemical charge storage and electrical conductivity/thermal management is seldom achieved for MXene‐based fibers due to the contradictory in material design. Typically, aligned and densified packing of MXene fibers is highly desired for an enhanced intra‐/inter‐flake electron transport; however, the narrowed inter‐layer spacing restricts the kinetics of ion diffusion (the intercalation/de‐intercalation of electrolyte ions) and diminishes the accessible active sites for charge storage. Herein, the electron and ion transports of Ti 3 C 2 T X MXene fiber are synergized via a unique dot‐sheet heterostructure covalently bonded by Ti─C─Ti which provides the optimal inter‐layer spacing for rapid ion diffusion and enhances the intra‐/inter‐flake cross‐linking for fast electron transport. As a result, the obtained fiber offers an improved conductivity of 2405 S cm −1 , a desirable capacitance of 1597 F cm −3 , an impressive energy density of 19.8 mWh cm −3 for the assembled supercapacitor, superior Joule heating performance, and a photo‐thermal temperature. These remarkable attributes enable their practical applications in energy‐supply scenarios, such as powering LEDs and wearable thermal management.