Experimental investigation on the essential cause of the degrading performances for an overcharging ternary battery

Ternary power batteries, as the mainstream power sources of electric vehicles, are liable to inducing thermal runaway (TR) with respect to their sensitivity to abusive conditions. Among various abuse conditions, the overcharge of a battery has been considered as the most common and severe case giving rise to thermal safety accidents. In this study, an overcharged battery and a normal battery, both using ternary/graphite electrodes, were investigated and analyzed synergistically through thermal behaviors and electrochemical characteristics. Initially, a series of electrochemical parameters including charge and discharge voltage plateaus, discharged capacity and time at different discharge rates, and internal resistances were carried out. Then, the heat generation behaviors between normal and overcharged batteries were evaluated. Furtherly, the interconnectedness with the electrochemical capacity degradation and heat generation aggravation of the ternary battery after overcharge was analyzed. Besides, the essential causes of the deterioration of electrochemical properties and severe heat behaviors resulting from overcharge were intensively analyzed via microscopic perspectives. In addition, the electrochemical characteristics fading of abused ternary battery triggered by overcharge were investigated, especially under higher temperature (55 degrees C) and ultralow temperature (-20 degrees C) conditions. Therefore, for an overcharged battery, this research not only elaborates the essential causa of the degraded electrochemical and anabatic thermal performance from a materials and thermal science perspective but also provides a foundation for further promoting the safety properties of commercialized power batteries with ternary chemical systems.