Study On Synthesis And Modification Of Microspherical TiNb₂O₇ Anode Materials

Titanium niobate(TiNb2O7,TNO),as a new type of lithium ion battery anode material,has similar electrochemical properties to lithium titanate material.The lithium ion insertion potential of TiNb2O7 is about 1.64 V,which can effectively avoid the formation of SEI film and the formation of lithium dendrites.In terms of theoretical capacity,it far exceeds lithium titanate,which is about 387.5 mAh/g.With excellent cycle stability and safety,it has been widely concerned by researchers.This subject focuses on the preparation of TiNb2O7 single-phase lithium ion battery anode material and its doping modification.In the experiment,solvothermal method was used to prepare pure TiNb2O7 material.The effects of raw material ratio,solvothermal temperature and calcination temperature on its electrochemical performance were studied.As aresult,when the atomic molar ratio Ti:Nb=1:2,the solvent temperature is 180? for 24 hours and the calcination temperature is 900 ? for 6 hours,using tetrabutyl titanate(C16H36O4Ti)and niobium pentachloride(NbCl5)as raw materials,ethanol as the solvent,the prepared TiNb2O7 pure phase material has the best lithium storage capacity.When the discharge rate is 0.5 C,the first discharge specific capacity of the electrode reaches 367.1 mAh/g,and after 50 cycles,its discharge specific capacity was maintained at 156.9 mAh/g.At 10 C,the first discharge specific capacity of the electrode reaches 251.4 mAh/g,and after 300 cycles,its discharge specific capacity was maintained at 87.4 mAh/g.In this paper,the metal doping modification of TiNb2O7 materials is studied,and vanadium pentoxide(V2O5)is used as the vanadium,source to test the electrochemical performance of samples with different vanadium ion doping amounts.The analysis results show that when the atomic molar ratio Ti:V=1:0.03,TNO-V0.03 electrode can show good electrochemical performance.At 0.5 C,the first discharge specific capacity of the TNO-V0.03 electrode is 338.2 mAh/g,and it has a discharge specific capacity of 264 mAh/g after 100 cycles;when the discharge rate of the electrode is 10 C,the first discharge specific capacity can reach 294.3 mAh/g,after 500 cycles,the discharge specific capacity is 195.8 mAh/g.In order to improve the electrical conductivity of TiNb2O7 electrode,this paper selects cetyltrimethylammonium bromide(CTAB)as the carbon source and synthesizes TNO/C composite by solvothermal method.When the carbon content is 15%,the TNO/C composite material can exhibit excellent electrochemical performance.At a discharge rate of 1 C,the initial discharge specific capacity of the TNO/C composite is 372.1 mAh/g.After 100 cycles,the discharge specific capacity is maintained at 264.8 mAh/g.When the discharge rate is 10 C,the initial discharge specific capacity of the electrode is 228.2 mAh/g,and it can still reach 176.2 mAh/g after 1000 cycles.