流变相法合成尖晶石型Li_xMn_2O_4及其电化学性能

Electrochemical properties of spinel Li_xMn_2O_4 compound synthesized by the rheologic phase method

以LiNO3 和电解MnO2 为原料 ,以含羟基有机溶剂和水的混合溶液为分散剂 ,采用流变相法合成尖晶石型LixMn2 O4,用XRD ,TG DTA等技术表征了其结构与性能 .结果表明 ,在煅烧温度为 76 0℃时 ,所得化合物为Mn的平均价态为 3.5左右的尖晶石型锂锰氧化合物 ,该化合物具有良好的电化学性能 ,呈现出 4 .0 5V和 3.95V两个放电平台 ,并很好的电压稳定性 ,首次放电容量达 117mA·h·g-1,充放电效率大于 90 % ,循环 2 0次后 ,放电容量约为 10 2mA·h·g-1.

A spinel type Li x Mn 2O 4 compound was synthesized by rheologic phase reaction using LiNO 3 and electrolytic MnO 2(EMD) as raw materials and mixture solution of water and organic agent with hydroxy as dispersant. The changes in the crystal structure and the reaction mechanism of LiNO 3 and EMD were detected by means of X ray diffraction and thermal analysis (TG DTA). The results show that perfect spinel Li x Mn 2O 4 crystals can be obtained at the calcinating temperature of 760 ℃ for 12 h. It should be noted that there exist two step lithium intercalation/deintercalation processes in Li x Mn 2O 4 at 3.95 and 4.05 V, which were induced by lithium ion ordering on the 8a tetrahedral sites. The material exhibited the charge/discharge characterizatics typical of undoped, non stoichiometric Li x Mn 2O 4 spinel and the discharge capacity decreased by 12% of the initial capacity (117 mA·h·g -1 ) after 20 cycles.