Modeling analysis of the effect of battery design on internal short circuit hazard in LiNi0.8Co0.1Mn0.1O2/SiOx-graphite lithium ion batteries

The internal short circuit is one of the most severe safety hazards to large format lithium ion batteries. This study aims to reproduce the internal short circuit hazard through experimental and numerical methods to give a better understanding of the effect of laminated battery design on thermal abuse tolerance. A thermal abuse reaction model based on LiNi0.8Co0.1Mn0.1O2/SiOx-graphite system is constructed with the assist of differential scanning calorimetry, and accelerating rate calorimetry experiments. The thermal runaway of the sample battery shows a five-stage process, and 11 chemical reactions and other heat sources are sorted out through modeling. Then the model is further simplified and coupled with the electrochemical-thermal model. The whole process of initiation of thermal runaway and heat progression afterward are reproduced. The model is extended to compare batteries with different laminated numbers and electrode sizes on the internal short circuit issue. Results show that different laminate design schemes will result in different hazard patterns. Larger layer number will delay the thermal runaway of the battery, but increase the seriousness of thermal hazard. Thermal tolerance ability can be adjusted without changing battery capacity. This work provides an applicable methodology for tuning layer number and electrode size for battery manufacture for safety concerns.