Risk evaluation of internal short circuit for lithium-ion battery based on an active protection method

Internal short circuit (ISC) can lead to thermal runaway and even cause fire. But the traditional passive methods cannot prevent the ISC before it occurs. The active protection method is proposed based on the evaluation of the ISC risk. An evaluation model is built based on the electrochemical model and solved with the Monte-Carlo method. Then, the model is verified with experimental data. The simulation result agrees with the experimental data of accelerated cycle life. Next, the effect of different factors on the probability of ISC risk is studied. It is found that (a) the variation trend of the probability of ISC risk with cycle number is nonlinear. The critical cycle number exists in the long-time use of the battery. (b) The probability increment of ISC risk becomes apparent when the charge rate reaches a critical value. (c) Battery temperature plays a great role in the critical cycle number. A lower temperature reduces the critical cycle number. (d) Effect of factors on the probability of ISC risk is listed as follows: charge rate > cycle number > battery temperature. With the help of the active protection method, ISC risk can be predicted before ISC occurs