Comparison analysis on the thermal runaway of lithium-ion battery under two heating modes

The thermal stability evaluation of materials in a soft-pack commercial cell is tested using C80 calorimeter, including anode, cathode, separator and full cell (mixing of the three materials including additional electrolyte). Thermal runaway characteristic of the commercial cell is tested on the accelerating rate calorimeter (ARC) with two heating modes, including internal heating mode and external heating mode. The results show that the thermal stability of internal material for tested cell follows the below order: anode < separator < cathode. The voltage drop is influenced by the consumption of cathode and separator, while the effect of anode consumption on the voltage can be negligible. Both onset temperature and critical temperature in external heating mode are larger than that in internal heating mode. Thermal runaway induced by high temperature of the tested cell can be divided into three stages: 1) the cell can work under normal mode and all the internal exothermal reaction can be ignorable, 2) the exothermal of anode which can be detected and the thermal runaway can be stopped by effective heat dissipation, and 3) the cathode reaction and separator melting which cause the cell voltage drop and thermal runaway of the cell is inevitable in this stage

Failure mechanism of the lithium ion battery during nail penetration

Nail penetration is one of the most important methods to study the internal short circuit safety of lithium ion batteries (LIBs). A series of penetration tests on LIBs under different conditions are conducted. The effects of the states of charge (SOC), penetration positions, depths and speeds are analyzed. As for different penetration positions, thermal runaway reaction is more severe when the battery is penetrated at center due to the faster propagation of thermal runaway. The battery surface temperature is not positively correlated with penetration depth, and the temperature distribution becomes more nonuniform with the increasing of penetration speed. All batteries get into thermal runaway if their temperatures exceed 233 °C due to the shrinkage of separator and trigger of reaction between cathode and electrolyte. The fire behavior of penetrated batteries is exhibited in this work. “Micro short-circuit cell” structure is proposed to interpret the mechanism of internal short circuit induced by penetration

Effects of Current and Ambient Temperature on Thermal Response of Lithium Ion Battery

Both operating current and ambient temperature have a great impact on heat generation and the available residual capacity of the lithium ion battery. The thermal response of the lithium ion battery is investigated under isothermal conditions. Six currents from 1 A to 6 A, with a 1 A interval, are investigated in order to discuss the effect of current under 25 °C; four temperatures from 10 °C to 55 °C, with a 15 °C interval, are investigated to study the effect of temperature under the current of 2 A. The heat generation rate increases with the current increasing during both the charge and discharge stage, but the charge capacity remains independent of current, while the discharge capacity decreases with increasing current. Heat generation decreases with increasing temperature in both the charge and discharge stage, while charge capacity and discharge capacity increase. with the temperature increasing from 10 °C to 55 °C. Heat generation of per charge/discharge capacity is also discussed, and in most cases, the heat generation of per charge capacity during the constant voltage charge stage is larger than that during the constant current charge stage. Heat generation increases at the expense of available capacity, during the discharge stage