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(2 D)nickel-based coordination polymers were successfully prepared according to aqueous phase copolymerization approach.And then uniform carbondoped 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.