Preparation And Modification Of H₂Ti₁₂O₂₅ As Anode Materials For Lithium Ion Batteries

H₂Ti₁₂O₂₅,as a new and high-voltage anode material,has gradually attracted people's attention due to its high energy density and good cycle performance.However,its naturally low lithium ion diffusion rate and electronic conductivity limit its pratical application to a certain extent.In this study,H₂Ti₁₂O₂₅ anode materials were prepared by different methods using different precursors and further modified by graphene.The conclusions are as follows:1.H₂Ti₁₂O₂₅ nanorods were successfully prepared by molten-salt synthesis(noted as m-H₂Ti₁₂O₂₅).Then the influences of materials ratio?Na₂CO₃:TiO₂:NaCl?,sintering temperature,ion-exchange temperature on structure and electrochemical performance were investigated.The results show that when the molar ratios?Na₂CO₃:TiO₂:NaCl?are 1:6:20,and further ion-exchanged at 380°C after cacilning at820°C for 5 h,m-H₂Ti₁₂O₂₅ nanorods have the best electrochemical performance.2.H₂Ti₁₂O₂₅ micro-nanoparticles were prepared by milling assisted soft-chemical method(noted as s-H₂Ti₁₂O₂₅).The influences of materials ratio?Na₂CO₃:TiO₂?and sintering temperature on the electrochemical performance were investigated.It was concluded that s-H₂Ti₁₂O₂₅5 exhibited the best electrochemical performance when it was prepared at 800°C with a molar ratio of 1.05:6?Na₂CO₃:TiO₂?.3.Compared with s-H₂Ti₁₂O₂₅ micro-nanoparticles,m-H₂Ti₁₂O₂₅ nanorods delivered higher reversible capacity and better high rate performance.m-H₂Ti₁₂O₂₅nanorods delivered 219.8 mAh g^-11 at 1 C after 100 cycles,172.1 mAh g^-1 at 10 C and144.4 mAh g^-1 at 20 C after 200 cycles,while for s-H₂Ti₁₂O₂₅,its reversible capacities were only 189.9 mAh g^-11 at 1C,146.0 mAh g^-11 at 10C and 121.0 mAh g^-11 at 20C after200 cycles under the same conditions.4.With Na₂Ti₃O₇ as precursors,graphene coated H₂Ti₁₂O₂₅ was successfully synthesized via the simple wet-coating method.With the coating content of 0.75 wt.%,H₂Ti₁₂O₂₅/graphene?HTO/G?exhibited an initial reversible capacity of 181.6 mAh·g^-1at 1C,while uncoated H₂Ti₁₂O₂₅?HTO/G?exhibited an initial reversible capacity of163.2 mAh·g^-1.Moreover,HTO/G exhibited improved reversible capacity of 115.5m Ah·g^-1 at a high rate of 10C after 200 cycles,which was higher than that(99.0m Ah·g^-1)of HTO at the same conditions.