A 3D Hydroxylated MXene/Carbon Nanotubes Composite as a Scaffold for Dendrite‐Free Sodium‐Metal Electrodes

Abstract Sodium metal is a promising anode, but uneven Na deposition with a dendrite growth seriously impedes its application. Herein, a fibrous hydroxylated MXene/carbon nanotubes (h‐Ti 3 C 2 /CNTs) composite is designed as a scaffold for dendrite‐free Na metal electrodes. This composite displays fast Na + /electron transport kinetics and good thermal conductivity and mechanical properties. The h‐Ti 3 C 2 contains abundant sodiophilic functional groups, which play a significant role in inducing homogeneous nucleation of Na. Meanwhile, CNTs provide high tensile strength and ease of film‐forming. As a result, h‐Ti 3 C 2 /CNTs exhibit a high average Coulombic efficiency of 99.2 % and no dendrite after 1000 cycles. The h‐Ti 3 C 2 /CNTs/Na based symmetric cells show a long lifespan over 4000 h at 1.0 mA cm −2 with a capacity of 1.0 mAh cm −2 . Furthermore, Na‐O 2 batteries with a h‐Ti 3 C 2 /CNTs/Na anode exhibit a low potential gap of 0.11 V after an initial 70 cycles.