Highly defective Ti₃CNT_x-MXene-based fiber membrane anode for lithium metal batteries

Lithium metal batteries (LMBs) have attracted increasing attention owing to their high theoretical capacity and low reduction potential. However, safety concerns and their low coulombic efficiencies (CE) arising from the nonuniform and irreversible formation of Li dendrites on their anodes hinder their practical application. Here, we demonstrate that a highly defective titanium-carbonitride (Ti₃CNT_x)-MXene-based fiber membrane can function as a dendrite-free anode substrate for LMBs. The Ti₃CNT_x fiber membrane electrodes, prepared via the electrostatic self-assembly of Ti₃CNT_x flakes onto a glass-fiber membrane substrate, had a high surface area (∼276 m² g⁻¹), leading to a high CE of ∼99.1%, excellent cycling stability of more than 1000 cycles in a Li half-cell test, and high energy density (581.78 W h kg⁻¹) and high power density (3008 W kg⁻¹) in a Li-MXene-fiber/NCM622 full-battery test. This excellent cell performance is attributed to the strong lithiophilicity and high density of Ti vacancy defects in the Ti₃CNT_x MXenes, as well as the high surface area of the fiber membrane electrode. The lithiophilicity and defect structure of Ti₃CNT_x MXenes in LMB operation were elucidated by DFT calculations.