石墨/LiFePO4电池高温储存后的性能

摘要

研究了石墨/磷酸铁锂(LiFePO4)电池高温(55±2℃)储存后的性能.以25％～ 75％荷电态(SOC)储存时,电池和LiFePO4电极的容量均为先略有增加、后衰减,容量达到最高点时,LiFePO4电极的阻抗减小,动力学性能提高,对性能变化起决定性作用,原因是脱锂态储存时LiFePO4和FePO4体积差引起的内应力,使两相的晶粒发生分裂,产生新鲜界面.%The performance of graphite/lithium iron phosphate( LiFePO4) battery after stored at high temperature (55 ± 2℃) was studied. During stored in 25% ~ 75% state of charge (SOC), the capacity of both the battery and the LiFePO4 electrodes slightly increased firstly and then decreased. When the capacity went up to the maximum, the impedance of the LiFePO4 electrode decreased with its kinetic characteristics improved, mainly contribute to the overall changing of performance. The reason was the difference in the cell volume of LiFePO4 and FePO4 caused the internal stress in the structure when stored in delithiated, which led to the partical splitting of the two phases,some fresh surface emerged.