Sensitivities of lithium-ion batteries with different capacities to overcharge/over-discharge

A series of experiments were carried out in this study to investigate the sensitivity of lithium-ion batteries with different capacities to overcharge and over-discharge conditions; whereby, two nominal capacities (2100 and 3000 mAh) were included. It is observed that batteries experience a serious degradation in the process of overcharge cycling; moreover, the degradation behavior exacerbates with the increase of battery nominal capacity. That is, the battery with a higher nominal capacity is more sensitive to overcharge conditions, which may be ascribed to the more severe lithium inventory loss, electrolytes loss and anode materials loss along cycling. The worse polarization and heat generation for the higher capacity battery cause inhomogeneous lithium distribution and heat distribution, therefore battery aging is aggravated. The degradation behavior is further demonstrated through the evolution of battery charge/discharge voltage, battery surface temperature, battery resistance and battery internal morphology. Similar phenomenon is also illustrated under the over-discharge condition. Considering the serious damage of overcharge and over-discharge on batteries, it is critical to avoid overcharge and over-discharge especially for the high-capacity battery.