钠离子电池TiO_2/还原氧化石墨烯负极材料的制备及储钠性能

由于钠离子半径比锂离子半径大70%,使得钠离子在石墨电极材料中脱嵌较困难,需要对石墨负极材料进行改性。以天然石墨为原料,采用Hummers法制备氧化石墨烯;在此基础上以钛酸丁酯为原料,采用溶胶-凝胶法制备了TiO_2前驱体/氧化石墨烯(TiO_2/GO)复合材料,通过热处理获得锐钛矿型TiO_2/还原氧化石墨烯(TiO_2/RGO)复合材料。电化学测试结果表明:TiO_2含量为15wt%的TiO_2/RGO复合材料在电流密度为20mA·g~(-1)下的首次放电比容量为74.08mAh·g~(-1),随着循环次数的增加,放电比容量逐渐增大,循环50次后达109.10mAh·g~(-1);充放电效率也呈现出逐渐增大的趋势,循环50次后达65.59%。而纯还原氧化石墨烯首次放电比容量为41.43mAh·g~(-1),循环50次后仅为20.47mAh·g~(-1)。

Preparation and storage sodium properties of TiO2/reduced graphene oxide anode materials for sodium-ion batteries

Due to the sodium ion radius is 70% larger than lithium ion radius, the embedding for sodium ion in and out of the graphite electrode materials is more difficult, and the graphite material needs to be modified. Using the natural graphite as raw material, graphene oxide was prepared via the Hummers method. Using the tetra-n-butyl titanate as raw material on this basis, the precursor TiO₂/graphene oxide (TiO₂/GO) composite was prepared by sol-gel method, and the anatase type TiO₂/reduced graphene oxide (TiO₂/RGO) composite was obtained by heat treatment. The electrochemical test results show that when TiO₂ content is 15wt%, the TiO₂/RGO composites exhibit an initial discharge specific capacity of 74.08 mAh·g^-1 at current density of 20 mA·g^-1. And with the increase of the number of cycles, the discharge specific capacity gradually increases, and reaches 109.10 mAh·g^-1 after 50 cycles, and the charge-discharge efficiency is 65.59% after 50 cycles, which is also showing a trend of increasing. While the initial discharge specific capacity of pure reduction oxidation graphite is 41.43 mAh·g^-1, and reaches 20.47 mAh·g^-1 after 50 cycles.