N掺杂C包覆Li_4Ti_5O_(12)锂离子电池负极材料的制备与性能

Preparation and Performance of N-doped Carbon Coated Li_4Ti_5O_(12) as Anode Material for Lithium-ion Batteries

以TiO2和Li2CO3分别作为钛源和锂源,聚苯胺(PANI)作为碳源和氮源,通过球磨辅助高温固相法合成N掺杂C包覆Li4Ti5O12.通过X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、元素分析仪(EA)、扫描电子显微镜(SEM)及透射电子显微镜(TEM)等对材料的结构和形貌进行了表征,并将合成材料制成电极片组装成扣式电池,测试其电化学性能.结果显示,钛源的处理对样品的性能有影响,通过对TiO2预包覆合成的N掺杂C包覆Li4Ti5O12具有优异的电化学性能,在碳、氮源的包覆比例(PANI与Li4Ti5O12的质量比)为5%时效果最佳:1C放电时其比容量为157.6mA·h/g,20C放电时其比容量仍可达到119.6mA·h/g;在10C充放电循环100次后,其比容量保持率为97.8%,表明N掺杂C包覆Li4Ti5O12具有优异的倍率性能和循环稳定性.

N-doped carbon coated Li4Ti5O12 samples were synthesized by a conventional high-temperature solid method with ball milled TiO2,Li2CO3 and polyaniline（PANI） as the titanium source,lithium source and carbon / nitrogen source,respectively.The structure and morphology of the samples were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,elemental analysis（EA）,scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.The electrochemical performance of the samples as the anode material for lithium-ion batteries was evaluated.The results indicate that the treatment of titanium source affect the electrochemical properties of samples.N-doped carbon coated Li4Ti5O12 obtained by pre-coating process of TiO2 showed the best electrochemical behaviors when the coating ratio of carbon / nitrogen source was 5%.The specific capacity of the electrode reached 157.6 m A·h / g at 1 C and retained to be 119.6 m A·h / g at a high current density of 20 C.It remained 97.8% of initial capacity after100 cycles at 10C.