Porous carbon as template for synthesis of Li₄Ti₅O₁₂ and its lithiation performance

Using hydrated titanium oxide sol as raw material, porous carbon as template, a novel spinel Li₄Ti₅O₁₂ was synthesized. SEM, XRD, galvanostatic charge-discharge test, and alternating current impedance test were used to characterize the appearance, structure, and electrochemical performance of the oxide. The results showed that the dimension of the crystal particle of the oxide was about 200 nm. At a 0.5C (1C=0.2 mA· cm^-2) current condition, the first charge-discharge efficiency of the Li₄Ti₅O₁₂ electrode was 99.8%, the lithium intercalation potential or the lithium extraction potential was quite flat, and it's reversible capacity was 117 mAh· g^-1. When the current increased from 0.5C to 5C, the reversible capacity of the oxide was still above 100 mAh· g^-1, which was more than 86% of the initial capacity. The Li₄Ti₅O₁₂ exhibited an excellent rate capability. A.C. impedance test proved that using porous carbon as template in synthesis process could make the spinel Li₄Ti₅O₁₂ have good conductivity and obvious porous characteristic.