PVD amorphous carbon coated 3D NiCo₂O₄ on carbon cloth as flexible electrode for both sodium and lithium storage

With the advent of flexible electronics, flexible secondary rechargeable batteries have attracted considerable attentions as a promising power source in the new generation of flexible electronics such as roll-up displays, smart electronics, and implantable medical devices. In this work, we report the fabrication of 3D NiCo₂O₄ arrays on carbon cloth as a binder-free anode for sodium/lithium ion storage. Amorphous carbon layer is used to modify the surface of NiCo₂O₄ arrays by physical vapor deposition (PVD). The electrochemical performance measurements demonstrate that the amorphous carbon layer can improve the electrochemical stability of NiCo₂O₄. The NiCo₂O₄@ C/carbon cloth electrode exhibits a high reversible capacity of 749.9 mAh g⁻¹, stable cycling with more than 535.47 mAh g⁻¹ at 500 mA g⁻¹ over 100 cycles and impressive rate capability (318 mAh g⁻¹ at 5 A g⁻¹ over 700 cycles) for SIBs and excellent electrochemical performance for LIBs (reversible capacity of 807.63 mAh g⁻¹ were observed for 100 cycles).