X-ray computed tomography and simultaneous multi-signal detection for evaluation of thermal runaway of lithium-ion battery

Early warning of thermal runaway (TR) scenarios is one of the most effective and important ways to prevent accidents in lithium-ion battery (LIB) safety management. Herein, TR characteristics of 18,650 LIB are carefully investigated using X-ray computed tomography (X-CT) and simultaneously multi-signal method. The results show that after the first gas venting, TR of LIB may not necessarily and spontaneously occur within a certain temperature range. The X-CT reveals that TR originally occurs in the central area along the axial direction of the LIB, and then it expands to the surface layer of the LIB during thermal abuse. Internal electric short circuit occurs at 100°C and structural damage occurs at 110°C. The first gas venting time is almost simultaneously as the first TR temperature rising, which provides a very effective way to anticipate early TR, guaranteeing enough time for handling of LIB accident and supplying chances for people escaping.

热失控（Thermal Runaway, TR）场景预警是锂离子电池（Lithium-ion Battery, LIB）安全管理中预防事故的最有效且关键的手段之一。本文采用X射线计算机断层扫描（X-ray Computed Tomography, X-CT）与同步多信号方法，对18650型锂离子电池的热失控特性展开了细致研究。研究结果表明，在特定温度区间内，首次排气后锂离子电池未必会自发发生热失控。X-CT成像结果显示，热失控最初起源于锂离子电池的轴向中心区域，在热滥用过程中逐步蔓延至电池表层。当温度达到100℃时，电池内部发生电短路；当温度升至110℃时，电池出现结构损坏。首次排气时刻与首次热失控温升时刻几乎同步，这为提前预判热失控提供了极为有效的途径，可为锂离子电池事故处置预留充足时间，也为人员撤离争取了宝贵机会。