高活性Mn2O3制备尖晶石LiMn2O4及其性能研究

Study on Performance of Spinel LiMn2O4 Derived from a High Reactive Mn2O3

尖晶石LiMn2O4是当前最具研究价值的锂离子电池正极材料之一。采用碳酸锰热解法制备高活性Mn2O3粉末作为尖晶石LiMn2O4的前驱体,探究锰锂比对高温固相法合成尖晶石LiMn2O4的影响。利用热重分析(TG-DSC)及热力学分析确定碳酸锰热解制备前驱体高活性Mn2O3的最佳热解条件:热解温度为600℃时,制备出结晶性能良好、无杂质、分散均匀的Mn2O3粉末。通过X射线衍射(XRD)、扫描电镜(SEM)和电化学测试对尖晶石LiMn2O4的结构、形貌和电化学性能进行表征。结果表明,随着锂锰比增加,产物的结构、形貌和电化学性能均有所改善和提高。锂源的添加量决定了尖晶石LiMn2O4结构、形貌,当Mn∶Li=2. 0∶1. 2时,尖晶石LiMn2O4样品的结晶形态完善,表面光滑,颗粒均匀,且无杂质;在0. 5C下,其首次充电比容量达到117. 6 mAh·g^-1,放电比容量为114. 8 mAh·g^-1。循环100周后容量保持率达到91. 8%。在高倍率放电下,仍保持较高的放电比容量和较好的循环性能。

Spinel LiMn2O4 is one of the most researched lithium ion battery cathode materials. The highly reactive Mn2O3 was prepared as the precursor of spinel LiMn2O4 by manganese carbonate pyrolysis method,and the effect of Mn-Li ratio on the synthesis of spinel LiMn2O4 by high temperature solid phase method were investigated. Thermogravimetric analysis(TG-DSC)and thermodynamic analysis were used to determine the optimal pyrolysis conditions for the preparation of high-activity Mn2O3 by manganese carbonate pyrolysis method. When the pyrolysis temperature was 600 °C,Mn2O3 with good crystallinity,no impurities and uniform dispersion was prepared. The structure,morphology and electrochemical properties of the spinel LiMn2O4 were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)and electrochemical tests. The results showed that the morphology and electrochemical properties of the product were improved as the Li-Mn ratio increased,the addition of lithium determined the structure and morphology of spinel LiMn2O4. When Mn∶Li=2.0∶1.2,the spinel LiMn2O4 sample had perfect crystal morphology,smooth surface,uniform particles and no impurities;its first charge capacity reached 117.6 mAh·g^-1,discharge capacity reached 114.8 mAh·g^-1. And the capacity retention rate reached 91.8% after 100 cycles. Under high discharge rate,the discharge capacity and cycle performance were still perfect.