锂离子电池负极材料碳氮包覆钛酸锂的制备及表征

doi:10.11944/j.issn.1000-0518.2018.01.170016

摘要/Abstract

摘要：

以钛酸正四丁酯为钛源、甲酸锂为锂源、柠檬酸为碳源、脲作为氮源,采用溶胶-凝胶法制备出了氮修饰碳包覆钛酸锂(Li₄Ti₅O₁₂/NC)的复合电极材料。借助X射线衍射仪(XRD)、X射线光电子能谱分析仪(XPS)、傅里叶变换红外光谱仪(FTIR)、热重分析仪(TGA)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对Li₄Ti₅O₁₂/NC的晶体结构、组成和形貌进行了表征分析,结果表明,所得产物是由尖晶石结构Li₄Ti₅O₁₂外围包覆NC组成。恒电流充放电实验结果显示,碳氮包覆量为9.48% 的Li₄Ti₅O₁₂/NC材料在1C下首次放电比容量为212.9 mA·h/g,充放电循环100周后仍能保持160.1 mA·h/g的较高比容量。碳氮包覆不会改变材料的晶型,但能有效抑制复合材料粒径增大,同时增加复合材料锂脱嵌活性位点,提高其比容量和导电性。

关键词: 钛酸锂, 溶胶-凝胶法, 电化学性能

Abstract:

Nitrogen-doped carbon-coated lithium titanate(Li₄Ti₅O₁₂/NC) composites with high performance were prepared via the sol-gel method by using tetrabutyl titanate as the titanium source, lithium monohydrate as the source of lithium, citric acid as carbon source and carbamide as the source of nitrogen. The composites were characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Focuier transform infrared spectrometer(IR), thermal gravimetric analyzer(TG), scanning electron microscoy(SEM) and transmission electron microscopy(TEM). The results show that the composites are consisted of Li₄Ti₅O₁₂ with a NC coating layer. The Li₄Ti₅O₁₂/NC material with 9.48% of NC exhibits a better electrochemical performance. It delivers a capacity of 212.9 mA·h/g at the first discharge under 1C, after 100 cycles at 1C, it still retains a capacity of 160.1 mA·h/g. The NC coating does not change the material's morphology, but inhibits the growth of composite particles and increases the active site for Li⁺ ion insertion/extraction, and thus improves the rate capacity and electronic conductivity.

Key words: lithium titanate, sol-gel method, electrochemical performance

万露, 付争兵. 锂离子电池负极材料碳氮包覆钛酸锂的制备及表征[J]. 应用化学, 2018, 35(1): 116-122.

WAN Lu, FU Zhengbing. Preparation and Characterization of Nitrogen-doped Carbon-coated Lithium Titanate Anode for Lithium-ion Batteries[J]. Chinese Journal of Applied Chemistry, 2018, 35(1): 116-122.

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