Verticality Bridging Multilayered MXenes by NCNTs for Rapid Electron/Ion Bi-Continuous Transport.

Enlarging the interlayer structure of MXenes has been proven to be an effective strategy for enhancing the speed and efficiency of ion transport in assembled MXene-based battery electrodes. However, the expanded interlayer space will inevitably lead to decreased interlayer conductivity because of the insufficient internal contact between isolated monolayered MXenes. Herein, the "rapid electron/ion bi-continuous-transport channels" are achieved by vertically growing N-doped carbon nanotubes (NCNTs) into the interlamination to bridge multilayered MXenes. Importantly, both experimental and theoretical analyses demonstrate the co-catalytic effect of Ni and MXenes on the growth of NCNTs, a phenomenon that has not been reported previously. The vertically grown NCNTs, serving as bridging pillars in the interlamination, not only significantly augment the interlayer structure but also forge a robust interconnection among the monolayered MXenes. Therefore, this design simultaneously realizes the enlargement of the interlayer space to facilitate electrolyte infiltration for fast ion transport and enhances the interlayer conductivity for rapid electron transport through the NCNTs bridging pillars. As a result, the as-derived TiC@NCNTs hybrids show a high reversible capacity of 610 mAh g for Li storage and 158 mAh g Na storage. This work provides a universal approach to regulating the properties of MXenes.