Zn-Al共掺和形貌调控制备LiMn2O4正极材料及电化学性能

Preparation and Electrochemical properties of spinel LiMn2O4 cathode by Zn-Al co-doping and Morphology control

摘要:

采用固相燃烧法和不同的焙烧温度制备了600、650、700和750 ℃的LiZn_0.05Al_0.03Mn_1.92O₄材料。实验结果表明,Zn-Al复合掺杂和焙烧未改变LiMn₂O₄的晶体结构,样品结晶性随焙烧温度的升高而增加,650 ℃及以上时形成了较多包含高暴露{111}、小面积{110}和{100}晶面的截断八面体形貌晶粒,但750 ℃时部分样品发生分解。优化焙烧温度650 ℃的样品具有优良的倍率容量和容量保持率,在5 C和10 C下,初始放电比容量和1000次循环后容量保持率分别为101.3 mAh/g、81.5%和99.9 mAh/g、74.3%。CV和EIS表明,其具有较好的循环可逆性和较大的Li₊^{扩散系数。}Zn-Al共掺和形貌调控改性LiMn₂O₄正极材料有效抑制了LiMn₂O₄材料的Jahn-Teller效应,形成的截断八面体颗粒形貌降低了Mn的溶解,同时提供了更多的Li₊^{迁移三维通道},改善了材料的倍率容量及循环寿命。

Abstract:

LiZn_0.05Al_0.03Mn_1.92O₄ cathode material was synthesized by a solid-state combustion method and calcination temperature at 600、650、700 and 750 ℃. The experimental results show that Zn-Al co-doping and the calcination do not change the spinel structure of LiMn₂O₄. The crystallinity of the samples aggrandizes along with the increase of the calcination temperature. More truncated octahedral grains containing high exposure {111}, small area {110} and {100} crystal face are formed at 650 ℃ and higher temperature. However, some samples decompose at 750 ℃. At 5 C and 10 C, the initial specific discharge capacities and the capacity retention ratio after 1000 cycles are 101.3 mAh/g、81.5% and 99.9 mAh/g、74.3%, respectively. CV and EIS show that it has great cyclic reversibility and large Li₊ ^{diffusion coefficient. The Zn-Al} co-doping and morphology control modified LiMn₂O₄ cathode material can effectively inhibit the Jahn-Teller effect of spinel LiMn₂O₄ material. The truncated octahedral morphology reduces the dissolution of Mn and provides more Li^₊ diffusion channels. It improves the rate capacity and cycle life of the material.