大容量电动车VRLA电池早期容量的衰减

电动车用6DZM20型号的阀控铅酸(VRLA)蓄电池比6DZM14型号的使用寿命降低很多,在循环早期就出现容量衰减。通过对两种型号电池的正极活性物质进行扫描电镜(SEM)、X射线衍射(XRD)、循环伏安(CV)、交流阻抗(IMP)等实验测试以及超细玻璃纤维(AGM)隔膜中的酸度分析,发现6DZM20电池在充电时,正极中的PbSO4不能完全转化为PbO2,造成极板下半部分活性物质的利用率非常低。实验发现,极板上下部分的电流密度分布不均匀使得远离极耳的极板下半部分电流密度很小,硫酸分层造成电池下部的硫酸密度过高等现象都会导致电池出现早期容量衰减现象。

Premature capacity loss of high capacity VRLA batteries for electric vehicle

The valve-regulated lead-acid (VRLA) batteries of 6DZM20 have shorter life than 6DZM14, which are used in electric vehicle, and appeare premature capacity loss (PCL) phenomenon. Different positive active materials (PAM) were studied by SEM, XRD, CV and IMP. And the densities of sulfuric acid that respectively in the up and down parts of 6DZM20 batteries' AGM separators were also tested. The results show that PbSO4 cannot convert completely to PbO2, and the utilization of PAM on the down plate is very low. The reasons are followed by current density of 6DZM20 batteries is not well-proportioned, especially the down part of the plate which has the lowest current density, the down part of the plate has higher acid density as a result of acid stratification, so PCL appears.