锂离子电池高倍率纳米晶钛酸锂负极材料的制备及性能研究

Preparation and Properties of High-Rate Nanocrystalline Lithium Titanate Anode Materials for Lithium Ion Batteries

摘要: 为了解决尖晶石型钛酸锂(Li₄Ti₅O₁₂)导电性差、倍率容量低等缺点，本文以TiO₂为钛源、Li₂CO₃为锂源以及葡萄糖为碳源，采用两步球磨和两段固相烧结(简称两步法)制备了钛酸锂纳米晶负极材料。所制备的样品通过XRD、TEM、激光粒度仪、EIS以及充放电测试仪表征。结果表明所制备的样品颗粒尺寸低至50 nm，平均粒径 < 150 nm，具有优异的电化学性能。其中，0.1 C倍率下放电可逆比容量达到168 mAh/g，在1 C、3 C、5 C、7 C、10 C倍率下放电比容量分别为154 mAh/g、149 mAh/g、145 mAh/g、140 mAh/g和134 mAh/g。对比0.1 C，容量保持率分别为90.5%、88.6%、86.3%、83.3%和79.8%。通过两步法制备的样品可以有效抑制钛酸锂在合成过程中晶粒生长、团聚并改善钛酸锂的电化学性能。

Abstract: In order to solve the shortcomings of spinel lithium titanate (Li₄Ti₅O₁₂), such as poor conductivity and low rate capacity, lithium titanate nanocrystals anode materials are prepared using two-step ball milling combined with two-stage solid-phase sintering (referred to as two-step method) with TiO₂ as the titanium source, Li₂CO₃ as the lithium source, and glucose as a carbon source . The prepared samples are characterized by means of XRD, TEM, Laser particle analysis, EIS and charge/discharge measurement. The results show that the lithium titanate prepared has a size of less than 50 nm and the average particle size is less than 150 nm, which possess excellent electrochemical performance. The discharge specific capacity reaches to 168 mAh/g at 0.1 C, and the reversible specific capacity are 154 mAh/g, 149 mAh/g, 145 mAh/g, 140 mAh/g and 134 mAh/g at 1 C, 3 C, 5 C, 7 C, and 10 C, with the specific capacity retention rates of 90.5%, 88.6%, 86.3%, 83.3%, and 79.8%. The sample prepared by the two-step method can effectively suppress the grain growth and agglomeration during the synthesis process, improving the electrochemical performance of lithium titanate.