Co/N dual hybrid strategy for superior capacity and long cyclic stability Li+/K+ storage of ZnO/N-doped carbon nanosheet framework

Abstract

ZnO is considered to be a promising negative material for lithium ion batteries (LIBs) because of its high theoretical capacity, low cost and natural abundance. However, it is faced with the challenges of poor electronic conductivity and huge volume expansion, which will cause serious capacity degradation in the process of charge and discharge. Hence, the Co nanoparticles are introduced into the composite of ZnO and 3D N-doped carbon nanosheet framework (ZnO-NCNF) to further improve the lithium storage capacity and cyclic stability based on our previous work. The ZnxCoy composites were obtained after coprecipitation and subsequent thermal treatment. The Zn7Co3 composite presents the highest specific capacity of 667 mAh g−1 at 500 mA g−1 after 900 cycles. Moreover, it could possess a capacity of 597 mAh g−1 at 1 A g−1 for 1800 cycles. In contrast, the capacity of Zn10Co0 drops rapidly after 800 cycles. The introduction of Co nanoparticles could improve the electrochemical performances. Meanwhile, the Zn7Co3 composite also presents excellent potassium ion storage performance, which is seldom reported before. EIS results show that the introduction of Co could accelerate the electrons transporting, leading to better performances of electrochemical Li+ storage. This may be a promising strategy to design ZnO-based anodes with superior performances.