Flashlight treatment for instantaneous structuring of dense MXene film into porous MXene/TiO2 nanocomposite for lithium-ion battery anodes

MXenes, the two-dimensional metal carbides and nitrides, have been considered a new class of electrode materials with their noticeable performance in various energy storage systems. Furthermore, the unique property and morphology allow MXenes to be assembled into freestanding films, which can be applied in energy storage devices with lightweight and high energy density. However, their tendency to restack and aggregate remains a challenge to enhance the electrochemical performance of MXenes. In this study, we propose a facile method to fabricate a porous MXene-TiO2 freestanding anode with the help of a flashlight. Simply heating the MXene films with a flashlight in milliseconds increases the interlayer spacing of the MXenes and simultaneously forms TiO2 on the MXene surface. Along with the widened interlayer and formation of TiO2, improved wettability, easy electrolyte penetration, and reduced electrode resistance were achieved. As a result, this freestanding anode exhibits nearly 50 times higher Li+ storage capacity (148 mAh/g) than pristine MXene film (3 mAh/g) at 0.05 A/g and excellent cycle stability up to 1500 cycles without degradation.