以电解MnO_2超细粉为锰源制备高倍率LiMn_2O_4材料

Synthesis of high-rate LiMn_2O_4 with electrolytic MnO_2 ultra-fine particles

采用高温固相反应将电解MnO_2超细粉制备成粒度较大、结晶度较高的Mn_3O_4,再以其为锰源成功合成了LiMn_2O_4锂离子电池正极材料。采用X射线粉末衍射仪、扫描电镜、激光粒度分析仪、振实密度测试仪、比表面积测试仪及电化学充放电测试仪分别对合成材料的结构、形貌、粒度分布、振实密度、比表面积及电化学性能进行了表征测试。结果表明,合成的LiMn_2O_4材料晶体结构完整,为立方尖晶石结构,中粒度D(50)为8.88μm,振实密度为1.75 g/cm^3;在3.0~4.2 V(vs.Li/Li^+)充放电电压范围内,0.2 C(1 C=120 mA/g)首次放电比容量为121.5 mAh/g,100周循环容量保持率为90.8%,5 C放电比容量为0.2 C的76.8%,表现出优良的循环稳定性和倍率性能。

Mn_3O_4 with big particle size and good crystallinity was first synthesized by high-temperature solid-state reaction method from electrolytic MnO_2(EMD) ultra-fine particles. Then the LiMn_2O_4 cathode material was successfully synthesized with the above Mn_3O_4 as Mn source. The crystal structure, surface morphology, particle size distribution, tap density and specific surface area of the synthesized materials were characterized by X-ray diffraction spectroscopy(XRD), scanning electron microscopy(SEM), laser particle size analyzer, tap density instrument and BET analyzer, respectively. The electrochemical performance of LiMn_2O_4 materials was measured by chargedischarge tests. The results show that the synthesized LiMn_2O_4 has good crystallinity with cubic spinel structure,narrow particle size distribution with D(50) of 8.88 μm and high tap density of 1.75 g/cm^3. Moreover, the material delivers the initial discharge capacity of 121.5 mAh/g at 0.2 C(1 C=120 mA/g) in the voltage range of 3.0-4.2 V(vs. Li/Li^+),the capacity retention after 100 cycles is 90.8%,and the capacity ratio of 5 C/0.2 C is 76.8%,which demonstrate that the LiMn_2O_4 material has good cycle performance and high-rate property.