Flexible and free-standing MXene decorated biomass-derived carbon cloth membrane anodes for superior lithium-ion capacitors

Abstract

Two-dimensional transition metal materials, MXenes, have attracted tremendous attention in energy storage applications due to their layered structure, good electrical conductivity, and abundant functional groups. In this work, Ti₃C₂T_x MXene nanosheets and carbon nanotubes (CNTs) were uniformly sprayed and successfully loaded on the cotton nonwoven fabric-derived carbon cloth (CC) substrate by electrostatic self-assembly. The as-prepared flexible MXene-CNTs-CC membrane electrodes with enlarged interlayer spacing and high conductivity fabric support exhibited excellent electrochemical performance. In terms of lithium-ion batteries, the optimized MXene-CNTs-CC anode delivered an ultrahigh initial discharge capacity of 2277.5 mAh g⁻¹ at 0.1 A g⁻¹ along with notable cyclability (1149.8 mAh g⁻¹ after 100 cycles) and rate capability (544.1 mAh g⁻¹ after 200 cycles at 2 A g⁻¹) in half cells. The full cells assembled with LiCoO₂ cathode also displayed good cycling stability with a high reversible discharge capacity of 833.5 mAh g⁻¹ after 100 cycles at 0.1 A g⁻¹. Remarkably, the further constructed lithium-ion capacitors with the designed porous carbon nanofiber cathode could maintain energy densities of 121.5 to 20.8 Wh kg⁻¹ with the corresponding power densities of 125 to 12,500 W kg⁻¹, and achieved capacitance retention of 76.3 % after 10,000 cycles at 1 A g⁻¹, demonstrating excellent long-term cycle durability.