The Investigation Of NiSnO₃/graphene Composites As Lithium-ion Battery Anode Material

Lithium ion batteries are widely used in portable electronic devices and electric vehicles because of their high capacity,long storage life and safety.At present,graphite materials are now the most commonly commercial lithium-ion battery anode materials,but their theoretical capacity of 372 mAh g-1 has been unable to meet the requirements of modern high-performance electronic equipment.It is urgent to develop the high specific capacity,long cycle life,low cost of the next generation of lithium-ion battery anode materials.Tin-based oxides are expected to become alternatives to graphite anode materials due to their high theoretical capacity(Sn:990 mAh g-1),safety and reliability.However,the severe volume change may lead to the pulverization of the electrode during the electrochemical reaction,and finally affects the cycling performance.At present,the main ways have been devoted to improve the electrochemical performance of the anode material by preparing nanomaterials,or synthesizing carbon composites.In this work,we prepare the NiSnO3/graphene composites,and they exhibit excellent electrochemical performance as the anode material in lithium ion battery.The work is as follows:(1)We prepare the NiSnO3/RGO composites by hydrothermal reaction.The pure NiSnO3 nanoparticles are dispersed on the surface of reduced graphene oxide(RGO)nanosheets.The introduction of graphene can effectively ease the agglomeration and volume change of NiSnO3 nanoparticles during the electrochemical reaction.NiSnO3/RGO electrode shows better electrochemical performance compared to NiSnO3 and RGO electrodes.In addition,NiSnO3/RGO exhibits better cycling performance by use of polyvinylpyrrolidone(PVP)surfactant.(2)We prepare NiSnO3/3D-pG by using polystyrene(PS)as sacrificial template.As the anode material in lithium ion battery,the NiSnO3/3D-pG composites show excellent lithium storage performance than NiSnO3/RGO composites.The main reason maybe be attributed to the good porous structure of NiSnO3/3D-pG,which provides the buffer space for the volume change of NiSnO3 nanoparticles during the charge-discharge process.(3)We prepare NiSnO3/RGO/C composites by coating carbon on NiSnO3/RGO composites.Because of the carbon coating on the surface,the NiSnO3 nanoparticles can be avoided to contact with electrolyte directly.The carbon layer can not only inhibit the volume change of nanoparticles in the electrochemical process,but also increase the conductivity of the composites.The NiSnO3/RGO/C composites show better cycling performance and rate performance.