The Study On Synthesis And Modified Of Li₄Ti₅O₁₂ And Its Thin Film Electrode For Lithium-Ion-Battery Anodes

prepared by high-temperature solid-phase method.The?-cyclodextrin carbon coating and chitosan carbon nitrogen quantum dot co-modifying lithium titanate were prepared by sol-gel method.The preparation conditions of Li₄Ti₅O₁₂ thin film electrode were investigated by spin-coating method and the Ag deposited lithium titanate thin film electrode was synthesized.The conclusions are as follows:Spinel Li₄Ti_4.9Ni_0.1O₁₂ as anode material for lithium-ion battery was synthesized successfully by solid-state reaction method.The results showed that the synthesized Li₄Ti_4.9Ni_0.1O₁₂ particles are homogeneous without impure phase.The first discharge specific capacity of the Li₄Ti_4.9Ni_0.1O₁₂ sample is 173.3 m Ah/g and the coulombic efficiency was 97.4%at 0.5 C rate.The specific capacity remained 163.4 m Ah/g after50 cycles with a capacity retention of 94.3%.The as-prepared Li₄Ti_4.9Ni_0.1O₁₂ has smaller charge transfer impedance R_ct and weber impedance R_w compared with the Li₄Ti₅O₁₂.Li₄Ti₅O₁₂/C anode materials were successfully synthesized by two-step calcination and sol-gel method using?-cyclodextrin starting materials.The results show that the prepared Li₄Ti₅O₁₂/C composites are spinel cubic crystal with good crystallinity and without other impurities.The particle size is between 50nm and200nm.The electrochemical properties of Li₄Ti₅O₁₂ were effectively improved by carbon coating.Among these composites,Li₄Ti₅O₁₂ with 5%carbon coating shows the initial discharge specific capacity of 167.1 m Ah/g at 5C and a 93.3%capacity retention after100 cycles.Its reversible capacity is 125.4m Ah/g at a high discharge rate of 20 C after100 cycles.carbon-nitrogen co-modified Li₄Ti₅O₁₂?CNLTO?anode material for lithium-ion battery was synthesized by sol-gel method and two-step calcination process using chitosan as starting materials.The results show that the particle size of CNLTO is between 50 and 200 nm,and the particles adhere with nano-carbon-nitrogen quantum dots.The initial discharge specific capacity of CNLTO is 219.7 m Ah/g at 0.5C and its capacity retention is 80.3%after 100 cycles.The discharge capacity of CNLTO is up to 140.4 m Ah/g even at 40C with the capacity retention of 94.8%after 100 cycles,which can be attribute to the excellent conductivity and super fast ionic transport characteristic.The optimum experimental conditions of Li₄Ti₅O₁₂ thin film materials were investigated by sol-gel-spin coating.The results show that the pure phase Li₄Ti₅O₁₂film with smooth surface and good crystallinity was prepared at 3000 rpm of rotating speed at a heating rate of 5?/min to 350?heat preservation for 15 min and duplicate for 8 times.The effect of doping on the phase composition,film integrity and conductivity of Li₄Ti₅O₁₂ film materials was investigated by introducing different contents of Ag NO₃ as doping source under optimal conditions.The results showed that Ag particles deposited on the surface of the film do not change the crystal structure of the film material.the particles deposited on Ag surface could improve the electronic conductivity of the composite,but the integrity of the film formation is correlated negatively with the silver content.