Lithium-ion battery systems are complex electrochemical and mechanical systems, and the safety of battery packs is of Paramount importance in electric vehicles. The Safety Requirements of Electric vehicles, which clearly point out that the battery system does not fire or explode in 5 minutes after thermal loss of battery cell, reserve time for the crew to escape safely.

1. Thermal safety of power battery

Cold temperatures can cause poor battery performance and possible damage, but are generally not a safety hazard. However, overcharging (too high a voltage) can cause the cathode to decompose and oxygenate the electrolyte. Overdischarge (too low voltage) can cause the solid electrolyte interface (SEI) on the anode to break down and may cause oxidation of the copper foil, further damaging the battery.

2.IEC 62133 standard

IEC 62133 (Safety Test Standard for Lithium-ion Batteries and Batteries) is a safety requirement for testing secondary batteries and batteries containing alkaline or non-acidic electrolytes. It is used to test batteries used in portable electronics and other applications, addressing chemical and electrical hazards and mechanical issues such as vibration and shock that can threaten consumers and the environment.

3.UN/DOT 38.3

UN/DOT 38.3 (T1-T8 test and UN ST/SG/AC.10/11/ Rev.5), covers transport safety testing of all battery packs, lithium metal batteries and batteries. The test criteria consist of eight tests (T1 -- T8), focusing on specific transportation hazards.

4.IEC 62619

IEC 62619 (Safety Standard for Secondary Lithium Batteries and Battery Packs), which sets out the safety requirements for batteries in electronic and other industrial applications. Test requirements are suitable for stationary and dynamic applications. Fixed applications include telecommunications, uninterruptible power supplies (UPS), electrical energy storage systems, utility switches, emergency power supplies, and similar applications. Power applications include forklifts, golf carts, autonomous guided vehicles (AGVs), railways and ships (excluding road vehicles).

5.UL 2580x

UL 2580x (UL Battery Safety Standard for Electric Vehicles), consists of a number of tests:

High current battery short circuit: This test is run on a fully charged sample. Short circuit the sample using a total circuit resistance of ≤ 20 mΩ. Spark ignition detected the presence of combustible concentrations of gas in the samples and no signs of explosion or fire.

Battery squeeze: Run on a fully charged sample and simulate the impact of a vehicle crash on EESA integrity. Like the short-circuit test, spark ignition detects the presence of flammable concentrations of gas in the sample and there is no sign of an explosion or fire. No toxic gases are released.

Cell squeeze (vertical) : Run on a fully charged sample. The force applied in the squeeze test must be limited to 1000 times the weight of the battery. The spark ignition test is the same as the test in the squeeze test.

6. Safety Requirements for Electric Vehicles (GB 18384-2020)

The Safety Requirements for Electric Vehicles is a national standard of the People‘s Republic of China that came into effect on January 1, 2021, which sets out safety requirements and test methods for electric vehicles.