锰酸锂充放电过程中的化学变化

Chemical changes of spinel lithium manganese complex oxide as cathode electrodes during charge-discharge cycling

为了考察LiMn2O4锂离子蓄电池正极材料在充放电过程中的化学变化,采用高温固相法制备了尖晶石型LiMn2O4,并对其电化学性能进行了表征,利用X射线衍射分析的结果,结合Li-Mn-O相图,对LiMn2O4在多次循环充放电所发生的相变进行了研究。实验结果表明,其首次放电比容量为123 mAh/g,循环200次后的放电比容量为107 mAh/g;LiMn2O4发生歧化反应,以及在LiMn2O4微粒表面形成的Li2Mn2O4进一步转化成无电化学活性的Li2MnO3,这两种相变都会导致电池的不可逆容量损失。

Spinel lithium manganese oxide-LiMn2O4 for lithium ion batteries as cathode material was prepared by high temperature solid-state reaction to investigate electrochemical performance and its chemical changes during charge-discharged cycling between 4.3 and 3.5 V at room temperature, and the chemical reactions after continuously electrochemical cycling at the LiMn2O4 cathodes were described in detail with respect to XRD results combined the Li-Mn-O phase diagram. Results show that the initial specific discharge capacity of LiMn2O4 is 123 mAh/g, and after 200 times cycling, the discharge capacity retains 107 mAh/g. The irreversible capacity fade observed during cycling is attributed, at least partly, to disproportionation reactions of LiMn2O4,and Li2Mn2O4 which is formed at the particle surface of discharged LiMn2O4 electrodes turn to electrochemically inactive Li2MnO3.