Research On The Metal Silicate And Metal Selenide As Anode Materials For Lithium Ion Batteries

With the development of today's society and the rapid increase in people's demand for energy,countries around the world have begun to face a serious energy crisis.Lithium ion batteries?LIBs?with the virtue of pollution-free,recycle and high energy density have become a hotspot of many researchers concentrated on.However,the use of commercial carbon materials as anode material of LIBs has limited the development and employment for the low theoretical capacity of carbon.Therefore,in order to meet the needs of social development and alleviate the energy crisis,it is a general trend to explore anode materials with high performance and capacity.In this paper,several metal silicates and metal selenides were synthesized as anode materials of LIBs by simple methods,and their lithium storage properties and applications were studied.Related researches are as follows:1.Study on the core-shell structured carbon nanotube@manganese silicate?CNT@MnSiO₃?as high capacity anode of lithium-ion batteriesMetal silicates are one of the ideal materials for the anode of LIBs,but their performance in battery are limited by the poor conductivity and volume change during the charge/discharge process.To make up the defects of metal silicates,one-dimensional core-shell structured CNT@MnSiO₃ with enhanced conductivity and battery performance(920 mA h g^-1 at 500 mA g^-1 over 650 cycles)has been prepared by a facile solvothermal method.The CNT@MnSiO₃ material is different from the conventional CNT-based composites,which is a MnSiO₃ layer coated on the exterior of CNT.The one-dimensional tubular structure can offer an effective path for Li⁺diffusion,thus increasing the Li⁺diffusion rate in circulation process of battery.The CNT in the central of composite can substantial increase the conductivity and reduce the volume change of material.So the CNT@MnSiO₃ composite exhibit excellent cyclic capacity and rate performance.This method for preparing coaxial CNT@MnSiO₃ composite provides a promising way and method to synthesize other high performance metal silicates electrode.2.Study on the hollow Co₂SiO₄ Microcube?a-Co₂SiO₄ HC?with amorphous structure as anode material of lithium ion batteryIn order to alleviate the deficiency of weak conductivity and large volume change for Co₂SiO₄ electrode in LIB,the amorphous Co₂SiO₄ microcube with hollow and pore structure is firstly prepared by facile hydrothermal method and calcining process.For comparison,crystalline Co₂SiO₄ with similar structure is synthesized.On account of the amorphous nature,pore and hollow structure,the as-prepared amorphous Co₂SiO₄hollow microcubes can accelerated Li⁺diffusion rate and relieve volume expansion,which display superior electrochemical performance of 610 mA g^-1 after 380 cycles at500 mAh g^-1 than their crystalline counterpart when used as anode material of LIB.This work is a good attempt to employ amorphous metal silicate in LIB and at the same time facilitates the research of other amorphous materials as high performance LIB electrode.3.Study on the hexagonal prism structured manganese selenide/nitrogen-doped?MnSe/CN?carbon for high performance lithium ion batteriesMnSe has been widely studied in photodetectors,electrochemical sensor,ect.due to its unique bonding characteristics and special structures,but there are few reports about its application in LIB for the defect of low conductivity and huge volume expansion during charge/discharge process when served as anode material of LIB.To improve the electrochemical performance of MnSe,a novel hexagonal prism structured manganese selenide stabilized by nitrogen-doped carbon is successfully synthesized by a simple solvothermal and carbonization processes.Compared with conventional method of synthesizing metal selenide,this strategy without producing toxic H₂Se gases and using template is more eco-friendly and simple.The MnSe/CN composites exhibited higher rate performance and superior cycling performance compared with pristine MnSe when applied as anode material of LIB.This strategy can be further extended as a general approach to synthesize other metal selenides and the prepared nitrogen-doped carbon stabilized CoSe,NiSe and ZnSe also exhibit a superior LIB performance.This work can provide a new strategy for preparing metal selenides as advanced materials in area of SIBs,LIBs,catalysts,etc.