Thermal hazard evaluation of 18650 lithium-ion batteries at various discharge rates

Abstract

Lithium-ion batteries (LIB) provide high energy density, low self-discharge rate, long cycle life, and superior suitability for a wide range of applications, such as portable electronic devices, electric vehicles, and renewable energy systems. In this investigation, we prepared 18650 LIB cells with various discharging rates (1C, 2C, 3C, and 4C) using specified conditions for static discharging experiment, and recorded the battery discharge current (Idis), discharge time (tdis), central surface maximum temperature (Tmax), temperature fluctuation, discharge capacity (Cdis), discharge energy (Wdis), and voltage at different time intervals. We studied the association between the discharge rate and the thermal stability of LIB specimens. In the discharge process, it was observed that operating at an increased discharge rate exhibited a direct correlation with a higher temperature rise. The findings indicate that batteries prepared with a higher discharge rate exhibit greater instability in terms of inherent property. During the 4C discharge rate, the Tmax, Cdis, and Wdis values were 96.6 °C, 3.117 Ah, and 9.021 Wh, respectively. These results indicate that a discharging rate of 4C is inappropriate for batteries, while the discharging rates of 1C, 2C, and 3C are suitable in terms of thermal stability.