高温热处理对水热离子交换法制备钛酸锂纳米棒的结构和性能影响

采用水热离子交换法制备钛酸锂纳米棒, 用热重法(TG)分析钛酸锂在热处理过程中的重量损失, 用X射线衍射仪(XRD)和透射电子显微镜(TEM)测试水热反应温度(150和180℃)和高温热处理(600、750和900℃)对钛酸锂结构的影响, 用恒流充放电法和循环伏安法对钛酸锂进行电化学性能评价. 结果表明, P25与NaOH在180℃水热反应并经过H⁺与Li⁺交换, 热处理后可以得到纳米棒状钛酸锂, 热处理温度为750℃时, 初始放电比容量为164 mAh/g, 在电压为1.5V左右有明显的充放电电压平台, 50次充放电循环后比容量保持率达98.33%, 表现出良好的电化学性能.

Effect of Heat-treatment Temperature on the Structure and Properties of Li_4Ti_5O_(12) Nanorods Prepared by the Hydrothermal Ion Exchange Method

Li₄Ti₅O₁₂nanorods were prepared by hydrothermal ion exchange method. The weight lossprocess of Li₄Ti₅O₁₂ during the heat treatmentwas studied by thermogravimetric method (TG). The structure and composition ofthe samples obtained at different hydrothermal temperatures (150℃ and180℃) and different heat-treatment temperatures (600℃, 750℃ and900℃) were characterized by X-ray diffraction (XRD) andtransmission electron microscope (TEM). The electrochemical performances wereevaluated by means of various techniques including galvanostaticcharge/discharge tests and cycle voltammetry (CV) in terms of cyclingperformance and rate capability. The results indicate that Li₄Ti₅O₁₂nanorods can be synthesized after hydrothermal reaction at 180℃ by theway of ion exchanges. The first specific discharge capacity of the samples heat-treatedat 750℃ is 164 mAh/g with retention ratio of 98.33% after 50charge-discharge cycling, and the voltage plateau at 1.5V could be seen in thedischarge curves distinctively.