护套线过电流诱发短路故障起火过程及痕迹特征

为深入研究RVVB护套线发生过电流诱发短路故障的火灾危险性,搭建RVVB护套线过电流诱发短路故障电路实验平台,探究短路故障起火过程及痕迹特征,对过电流诱发短路故障初次短路发生时间、起火特征及痕迹特征进行研究。结果表明:当I≥45 A时,护套线会出现短路击穿现象,并引发明火燃烧;当I=66 A时,过电流诱发短路故障平均时间由I=45 A的1803.4 s缩短至52.8 s,明火燃烧时间呈现波动上升趋势,由16.4 s升高至28.96 s,火灾危险性增大;护套线发生过电流诱发短路故障会产生圆珠状、半圆状、尖状、连接珠状、凹坑状、断口状、叠加珠状等短路熔痕以及直径大小不一的短路熔珠。研究结果可对过电流诱发短路故障起火机理及熔痕识别提供理论基础。

In situ observation of cracking and self-healing of solid electrolyte interphases during lithium deposition

The growth of lithium(Li)whiskers is detrimental to Li batteries.However,it remains a challenge to directly track Li whisker growth.Here we report in situ observations of electrochemically induced Li deposition under a CO_(2) atmosphere inside an environmental transmission electron microscope.We find that the morphology of individual Li deposits is strongly influenced by the competing processes of cracking and self-healing of the solid electrolyte interphase(SEI).When cracking overwhelms self-healing,the directional growth of Li whiskers predominates.In contrast,when self-healing dominates over cracking,the isotropic growth of round Li particles prevails.The Li deposition rate and SEI constituent can be tuned to control the Li morphologies.We reveal a new“weak-spot”mode of Li dendrite growth,which is attributed to the operation of the Bardeen-Herring growth mechanism in the whisker’s cross section.This work has implications for the control of Li dendrite growth in Li batteries.