球形Li_4Ti_5O_(12)/NC复合材料的制备及性能

以CH_3COOLi为锂源、Ti(OC_4H_9)_4为钛源、聚乙二醇(PEG)1000为碳源、CO(NH_2)_2为氮源,采用溶胶-凝胶法制备球形氮修饰碳(NC)包覆钛酸锂(Li_4Ti_5O_(12))复合材料。用XRD、X射线光电子能谱(XPS)和热重测试分析材料的晶型及元素组成,用SEM和透射电子显微镜测试分析结构。制备的材料呈球形,NC包覆未改变Li_4Ti_5O_(12)的晶型,但会导致烧结过程中部分Ti~(4+)还原成Ti~(3+)。恒流充放电、循环伏安和交流阻抗等测试表明:NC包覆,可提高Li_4Ti_5O_(12)的电化学性能,当NC包覆量为4.11%时,复合材料的循环性能最好,以1 C在0.8~2.5 V循环100次,仍保持103.5 mAh/g的比容量。

Preparation and performance of spherical Li4Ti5O12/NC composite

CH3COOLi,Ti(OC4H9)4,PEG1000 and CO (NH2)2 were used as lithium source,titanium source,carbon source and nitrogen source,respectively,the composite of lithium titanate(Li4Ti5 O12) coated by nitrogen doping carbon (NC) were prepared by sol-gel method.XRD,X-ray photoelectron spectroscopy and thermal gravimetric analyzer were used to test the morphology and element component of the material.The SEM and transmission electron microscope tests were utilized to characterize the microcosmic structure.The prepared materials were like of sphere,NC covering could not affect the morphology of Li4Ti5O12,but led to the transformation from Ti4+ to Ti3 + during the sintering process.The galvanostatic charge-discharge,cyclic voltammetry and AC impedance spectroscopy tests showed that the electrochemical performance of spherical Li4Ti5O12 by NC covering was increased.When the coating amount of NC was 4.11％,the cycle performance of composite was the best.Its specific capacity was kept at 103.5 mAh/g when cycled 100 times at 1 C in 0.8-2.5 V.