荷电态对锰酸锂电池储存性能的影响

Effect of state of charge on storage performance of manganese spinel battery

采用商品化的LiMn2O4和石墨作为正负极材料制作锰酸锂动力电池,研究锰酸锂电池在不同荷电态下的储存性能,并且利用扫描电镜(SEM)、X线衍射(XRD)、循环伏安(CV)和交流阻抗(AC)等分析检测手段表征LiMn2O4电极储存前后的结构、形貌和表面状态变化,测试锰酸锂电池储存前后的电化学性能。研究结果表明:锰酸锂在放电态下储存的容量恢复率最高,达到99.4%;满电储存后容量恢复率最低,为93.6%;储存后锰酸锂电池的循环性能均有所改善,其中满电储存后循环性能最好,170次循环容量保持率为89.7%,储存前170次循环容量保持率为85.4%;锰酸锂电池储存后容量衰减随着荷电态的增加而增加,这主要是由Mn溶解量以及储存后正极表面极化的增加而引起的。

The power battery was manufactured with the commercial LiMn2O4 and graphite.The storage performances of LiMn2O4 batteries at different charged states were studied.Structure,morphology and surface state change of the LiMn2O4 before and after storage were observed by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,cyclic voltammograms（CV） and electrochemical impedance spectroscopy（EIS）,respectively.The electrochemical performances of LiMn2O4 battery before and after storage were tested.The results show that the capacity recovery of LiMn2O4 at discharge state is the best,and it is 99.4%,while the ratio at full charged state is the smallest,which is 93.6%.The cycling performance is improved because of the low capacity and MnO2 film deposited on the electrode.The cycling performance of LiMn2O4 after storage is improved.The cycling performance of LiMn2O4 stored at full charged state is the best,and the capacity retaining is 89.7% after 170 cycles.The capacity retaining is 85.4% after 170 cycles before storage.The capacity fading of LiMn2O4 battery is increased with the increase of charge state,which is because of the increase of Mn dissolution and polarization of electrode.