以镍钴锰(LiNiCoMnO2， NCM)为正极的26650型三元锂离子电池因具有优异的电化学性能和低成本的优势，在电动汽车发展中得到了广泛应用。为研究环境温度、放电深度（depth of discharge， DOD）对该类型电池过放电行为的影响，分别在常温、低温、高温下进行100%、110%、120%和130% DOD的放电诱导，并在测试前后进行阻抗分析。过放电实验结果表明在低温下，内短路发生时刻有所延迟；在110% ～ 130% DOD放电阶段，电压可能会发生剧烈振荡；过放电期间电池达到最高温度所需时间延长，整体温升速率增大。在高温下，电池发生内短路时刻有所延迟，电池达到最高温度所需时间变长。阻抗测试结果表明，在低温下过放电后，内阻变化幅度显著减小。在高温下经过110%、120%、130% DOD过放电后，电池内阻变化率均大于常温下的内阻变化率。本研究结果揭示26650型NCM锂离子电池在不同温度、不同DOD下过放电的失效机制，为过放电故障预警参数的设定及预防因过放电而引发电池热失控的防控方法提供重要支撑。

The 26650 ternary LiNiCoMnO2 (NCM) lithium-ion battery has been widely applied in the development of electric vehicles due to its advantages of premium electrochemical performance and low cost. To investigate the impacts of ambient temperature and depth of discharge (DOD) on overdischarge behaviors of 26650 NCM lithium-ion battery, this paper has performed 100%, 110%, 120% and 130% DOD discharge at normal, low and high ambient temperature, and has carried out impedance analysis before and after the test. The overdischarge results indicate that at low ambient temperature, there is a delay in the occurrence of internal short circuit; during 110% ~ 130% DOD discharge, there may be severe voltage oscillations, while the interval for the battery to reach its maximum temperature and the overall temperature rise rate during overdischarge increase. At high ambient temperature, the occurrence of internal short circuit is delayed while the time required for the battery to reach its maximum temperature is longer. The impedance test results show that the variation in internal resistance significantly decreases after overdischarge at low ambient temperature. After 110%，120% and 130% DOD overdischarge at high ambient temperature, the variation rate of battery internal resistance is greater than that at normal temperature. This study reveals the failure mechanism of 26650 NCM lithium-ion battery overdischarged at different ambient temperatures and DODs, which will provide vital support for the setting of early warning parameters for overdischarge fault and the preventive methods for battery thermal runaway caused by overdischarge.