Binder-Free Co₄N Nanoarray on Carbon Cloth as Flexible High-Performance Anode for Lithium-Ion Batteries

The development of flexible energy storage devices is highly dependent on the exploration of flexible anode materials with high electrochemical performances. Therefore, growing active materials with large capacity on flexible substrate has been intensively investigated. We herein report a simple route for the fabrication of binder-free Co4N nanoarrays on carbon cloth (Co4N/CC) as flexible and highly efficient anode of lithium-ion battery. High initial Coulombic efficiency can be achieved. The Co4N/CC exhibited a high capacity over 1100 mAh g–1 at 0.1 A g–1 and 855 mAh g–1 at 0.5 A g–1, which both could be effectively retained at ∼90% after 150 and 300 cycles, respectively. At a high current density of 2.0 A g–1, a high reversible capacity of 650 mAh g–1 was obtained. The excellent electrochemical performances can be primarily attributed to the high conductivity of Co4N and the unique architecture of Co4N/CC, in which needle-like Co4N nanoarrays fully cover the carbon fiber and serve as the antenna in the electrolyte, while CC works as electronic conductor. In addition, carbon fiber has been partially hybridized by nitrogen, which contributes to the extra lithium storage capability. Due to the relatively low voltage plateau of Co4N/CC, the full cell assembled with typical LiCoO2 cathode showed a very favorable high-voltage (∼3.7 V) and high energy density and power density. Due to the simple and effective procedure, the current strategy can be readily extended for the fabrication of other transition-metal nitrides, holding a great promise for electrochemical applications.