球磨条件对由电解MnO_2制备的LiMn_2O_4的结构、形貌和性能的影响

Effect of ball-milling conditions on the structure,morphology and performance of LiMn_2O_4 prepared from electrolytic MnO_2

使用工业电解MnO2为原料和高温固相法合成了LiMn2O4正极材料,通过SEM,XRD,循环伏安以及电化学测试对合成的LiMn2O4材料进行了表征,详细考察了电解二氧化锰(EMD)预球磨过程中球的大小和质量配比对EMD粒径和形貌的影响以及对合成的LiMn2O4电化学性能的影响。实验结果表明,当全部使用小球(直径6mm)预磨MnO2时,所制备的LiMn2O4尖晶石样品的晶粒尺寸适中,分布均匀,形貌较好,并与理论拟合结果完全一致。用0.5C倍率,在3.4～4.35V电压和常温下,LiMn2O4的首次放电比容量达到120mAh/g,20次循环后的容量保持率仍为97%。

The LiMn2O4 cathode materials were synthesized by using industrial electrolytic MnO2 （EMD）as raw material and high temperature solid-phase method. The prepared LiMn2O4 was characterized by XRD, SEM, cyclic voltammetry and electrochemical tests, the effects of different ball size and mass ratio on the grain size and morphology of EMD in pre-milling process were investigated in detail,and the effects on electrochemical performance of prepared LiMn2O4 were also studied. The results demonstrated that the prepared LiMn2O4 samples had moderate grain size, uniform distribution and good spinel morphology which are in accordance with theoretical calculation when MnO2 was premilled with small-sized （D-=6 mm） balls. Under the conditions of 3.40±4. 35 V range and ambient temperatures, the initial specific discharge capacity was as high as 120 mAh/g at 0. 5C, and the capacity retention rate was 97% after 20 cycles.