Lee Seung-Mi, Kim Jea-Yeon, Byeon Jai-Won
Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul, 139-743, Korea.
J Nanosci Nanotechnol. 2018 Sep 1;18(9):6427-6430. doi: 10.1166/jnn.2018.15691.
Accidental failures and explosions of lithium-ion batteries have been reported in recent years. To determine the root causes and mechanisms of these failures from the perspective of material degradation, failure analysis was conducted for an intentionally shorted lithium-ion battery. The battery was subjected to electrical overcharging and mechanical pressing to simulate internal short-circuiting. After in situ measurement of the temperature increase during the short-circuiting of the electrodes, the disassembled battery components (i.e., the anode, cathode, and separator) were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Regardless of the simulated short-circuit method (mechanical or electrical), damage was observed in the shorted batteries. Numerous small cracks and chemical reaction products were observed on the electrode surface, along with pore shielding on the separator. The event of short-circuiting increased the surface temperature of the battery to approximately 90 °C, which prompted the deterioration and decomposition of the electrolyte, thus affecting the overall battery performance; this was attributed to the decomposition of the lithium salt at 60 °C. The gas generation due to the breakdown of the electrolyte causes pressure accumulation inside the cell; therefore, the electrolyte leaks.
近年来，已有锂离子电池意外故障和爆炸的报道。为了从材料降解的角度确定这些故障的根本原因和机制，对一个故意短路的锂离子电池进行了失效分析。该电池经历了过充电和机械挤压，以模拟内部短路。在原位测量电极短路过程中的温度升高后，通过扫描电子显微镜和能量色散X射线光谱仪对拆解后的电池组件（即阳极、阴极和隔膜）进行了分析。无论模拟短路方法是机械的还是电气的，短路电池中均观察到损坏。在电极表面观察到许多小裂纹和化学反应产物，隔膜上也有孔隙屏蔽现象。短路事件使电池表面温度升高至约90°C，这促使电解质劣化和分解，并进而影响电池的整体性能；这归因于锂盐在60°C时的分解。电解质分解产生的气体导致电池内部压力积聚，因此电解质会泄漏。
