锰酸锂-石墨电池高温存储容量减少的研究

Study on capacity loss of lithium manganate-graphite cells under high temperature storage

利用X射线衍射仪(XRD)、电感耦合等离子体光谱仪(ICP)、电化学工作站与电池检测系统研究了锰酸锂-石墨电池高温存储容量减少的原因。结果表明,存储后正极片中锰酸锂的质量分数与负极片中石墨的质量分数均减少了,锰酸锂晶格表现为收缩,石墨晶格膨胀,正极片中的Mn元素溶出并沉积在负极,负极SEI(solid electrolyte interface)膜生长,造成电池高温存储后放电容量与功率均减少了,容量减少了6.77%,其中5.43%的容量损失由Mn溶出造成,1.34%的容量损失是由SEI的生长与电极反应对石墨界面的破坏造成。

The reasons for the reduction of high-temperature storage capacity of lithium manganate-graphite battery were investigated using X-ray diffractometer(XRD),inductively coupled plasma spectrometer(ICP),electrochemical workstation and battery testing system.The results show that the mass fraction of lithium manganate in the positive electrode and the mass fraction of graphite in the negative electrode decrease after storage,the lithium manganate lattice exhibits shrinkage,the graphite lattice expands,the Mn elements in the positive electrode dissolve and deposit on the negative electrode,and the negative electrode SEI(solid electrolyte interface)film grow,resulting in the reduction of both discharge capacity and power after high temperature storage of the battery.The capacity is reduced by 6.77%,of which 5.43%of the capacity loss is caused by the dissolution of Mn and 1.34%of the capacity loss is caused by the growth of SEI and the destruction of the graphite interface by the electrode reaction.