Transport Processes in a Li-ion Cell during an Internal Short-Circuit

作者：Jinyong Kim, Anudeep Mallarapu, S. Santhanagopalan · 年份：2020 · DOI：10.1149/1945-7111/ab995d · 被引用次数：28 · 研究领域：Materials Science

Internal short-circuit in lithium-ion battery causes abrupt increase of cell temperature and triggers thermal runaway of battery packs. In this work, we developed a detailed electrochemical-thermal model to investigate the physical behavior during the internal short-circuit. Simulations at wide range of heat transfer coefficients and short-circuit resistances are conducted to illustrate electrochemical and thermal behavior at wide range of conditions. Strong interactions between electrochemical behavior and thermal behavior are found, since parameters such as rate constants, diffusivities and conductivities are affected by temperature. Poorer thermal management tends to cause faster discharging rate and hence more susceptible to thermal runaway. Also, the Joule heating at the shorted region promotes electrochemical reactions nearby, causing in-plane non-uniformity of electrolyte and active material transport. Furthermore, it is found that diffusion in solid active materials plays a significant role at very high shorting conditions (~20C), as electrochemical reactions rates are being progressively more limited by active material diffusion with increasing discharging rate. This diffusion limitation causes decrease of cell equilibrium potential and heat generation rate at the shorted spot. Hence, the heating regime shifts from "local heating" to "global heating". Based on the findings, important design parameters for battery safety are discussed.