In this paper, the overcharge performance of a commercial pouch lithium-ion battery with Li y (NiCoMn) 1/3 O 2 -Li y Mn 2 O 4 composite cathode and graphite anode is evaluated under various test conditions, considering the effects of charging current, restraining plate and heat dissipation.
What is a battery overcharge?
Overcharge is the normal continued application of charging current to a battery after the battery has reached its maximum state of charge. It impacts the steady-state values of pressure, temperature, and voltage.
In the standards or regulations, the overcharge performance of single lithium-ion battery is evaluated through several overcharge tests, during which a controlled current is applied to the tested battery (e.g. 1/3 C) up to a set of charge limits (e.g. 2.0 SOC, 1.5 times the upper cut-off voltage).
The factors of battery material, charging pattern, and battery structure design on the overcharge effect are also summarized. To some extent, using external protection devices (such as BMS, OSD, CID) can improve overcharging security. But the internal protection of overcharge additives is more effective.
Overcharge test: The overcharge test is conducted in constant current mode at current rates of 0.5 C, 1 C, 2 C, 3 C, 4 C and 5 C, respectively. During this period, voltage, current, surface temperature and gas concentration parameters are collected until the battery ruptures and voltage reaches 6 V, and then, charging is stopped.
Before the overcharge test, charge the battery in 1 C constant current mode to a cut-off voltage of 4.1 V and leave it for 0.5 h. Then discharge to a cut-off voltage of 2.8 V in 1 C constant current mode and leave for 0.5 h. Repeat 3 times.
Key factors for battery overcharge safety, such as cathode materials, electrolyte safety, and charging current are concluded in this review. Compared to external protection devices (such as BMS, OSD, CID), the internal protection of overcharge additives are more effective.