( 1. 清华大学 核能与新能源技术研究院, 北京102201;
2. 北京工业大学 环境与能源工程学院, 北京 100022)
摘 要: 采用控制结晶法, 以MnSO4, NH4HCO3和氨水为原料制备了球形MnCO3。 所得产品的振实密度为2.1 g/cm3, 粉末粒度约为20 μm。 研究了MnCO3在不同温度下的热分解性能, 对热分解产物的差热/热重分析和X射线衍射分析发现, MnCO3的热分解反应分两步进行, 在300 ℃时开始分解, 生成中间产物MnO2; 在520 ℃时, MnO2开始转化为Mn2O3, 至560 ℃时完全转化为立方相的球形Mn2O3。 实验所确定的MnCO3完全分解为立方相球形Mn2O3的最佳条件为在560 ℃下加热4 h。 以LiCO3为锂源材料, 在750 ℃下与球形Mn2O3一起焙烧, 制备得到球形LiMn2O4。 其在25 ℃和0.4C倍率下的首次充放电容量分别为131和125 mA·h/g, 90次循环的容量保持率为84%。
关键字: 球形锰酸锂; 锂离子电池; 控制结晶; MnCO3; Mn2O3
( 1. Institute of Nuclear and New Energy, Tsinghua University,
Beijing 102201, China;
2. Colledge of Environmental and Energy Engineering,
Beijing University of Technology, Beijing 100022, China)
Abstract: A novel process was used to synthesize LiMn2O4 with spherical particles from cheap materials of MnSO4, NH4HCO3, NH3·H2O and LiCO3. The preparation started with a carefully controlled crystallization of MnCO3. Thermal decomposition of MnCO3 was investigated by both DTA & TG analysis and X-ray diffractrometry. The spherical Mn2O3 is obtained by heating MnCO3 at 560℃ for 4 h, then is mixed with LiCoO3 and sintered at 750℃ to produce spherical LiMn2O4. Its initial charge/discharge capacities are 131 and 125 mA·h/g, respectively, and its cycling capacity retention is 84% at the 90th cycle.
Key words: spherical LiMn2O4; Li-ion batteries; controlled crystallization; MnCO3; Mn2O3