Thermal kinetics on exothermic reactions of a commercial LiCoO2 18650 lithium-ion battery and its components used in electric vehicles: A review

Abstract

A review gathering available results on the chemical kinetics in literature for the commercial 18650 lithium-ion batteries containing cathode material of LiCoO2 and related components is summarized and discussed. Most of these kinetic parameters derived from adiabatic and heat-flow calorimeter, some few of them with the fitting of electrochemical-thermal model associated with data of accelerating rate calorimeter. However, due to the complexity of solid-state reaction involving both anode and cathode as well as the difficulty to determine the reaction mechanism function by thermal analysis on the solid electrode, most of the interpretation of calorimetric data set the order to be unity for simplicity. Kinetics-based heat rates under thermal abuses encompass the decomposition of solid electrolyte interface (stage III from 85 to 120 °C), reaction of LixC6 with electrolyte (stage IV from 120 to 170 °C), reaction of LixCoO2 with electrolyte (stage V from 170 to 200 °C), decomposition of LixCoO2 (stage VI > 200 °C), decomposition of solvent (stage VI > 200 °C) induced by internal short, and auto-ignition of solvent (stage VI > 200 °C). To clearly capture the distinctive features of these kinetic behaviors, the standard deviations adopted by the American Society for Testing and Materials E2781 and International Confederation for Thermal Analysis and Calorimetry are applied to enhance the accuracy and precision of the kinetic parameters. A diagram integrating all the Ea and log A values of LiCoO2 battery and its components is depicted, in which a newly phenomenon of compensation effect has been discovered. The linear equation of log A versus Ea tells the truth that some large errors existed in the data acquisition of kinetic parameters. Taking and comparing individually the average kinetic parameters from the decomposition of SEI, reaction of LixC6 with electrolyte, reaction of LixCoO2 with electrolyte to the whole battery, it is noteworthy that the chemical kinetics of the LiCoO2 battery is next door to that of LixCoO2 with electrolyte in n-th order reactions. The autocatalytic model II in Ea versus log A diagram seems to have the biggest deviations. The paradoxical model between the n-th order and autocatalytic type regarding the reaction of LixCoO2 with electrolyte exists and has not been exactly solved. Practically, some unimaginable disagreement among parameters of Ea and logA (sec−1 M1-n) are as yet unsettled, which reveals that the more extensive studies are needed to resolve the existing disputes. For the near future, a breakthrough of exceedingly better technology for acquiring the accurate chemical kinetics of a LiCoO2 battery and its ingredients will be expected earnestly.