High-pseudocapacitance of porous and square NiO@NC nanosheets for high-performance lithium-ion batteries

Layered nickel oxides have been focused with intense research interests as high-performance lithium-ion batterie (LIB) anode. However, it is hard to obtain few layered nickel oxides material directly as it easily forms bulk material with the strong interaction between the interlayer. In this work, two-dimensional (2D) nickel-based coordination polymers were successfully prepared according to aqueous phase copolymerization approach. And then uniform carbon-doped NiO nanosheets were successfully obtained from facile solution assembly and post-thermal treatment. The detailed electrochemical testing shows that the uniform NiO nanocrystals encapsulated into porous N-doped carbon (NiO@NC) nanosheets present much higher rate capability with the discharge specific capacity of 782.7 mAh·g⁻¹ at high current density of 2.0 A·g⁻¹ than pure NiO (690 mAh·g⁻¹). It also shows long-term cycling performance with 91% retention after 50 cycles at 1.0 A·g⁻¹. The high rate capability, cycling stability and the easy synthesis make NiO@NC nanosheets as a promising candidate for LIB anode and build up new way for the fabrication of metal oxides anode materials.