What are the common safety standards for lithium-ion batteries?

Many LIB safety issues arise because these devices are sensitive to voltage and temperature. Figure 1 illustrates the behavior of an Li(Ni₀.₅Co₀.₂Mn₀.₃)O₂ (NCM) battery. In this example, the battery is specified to operate within a temperature range of -30°C to 55°C.

At temperatures above 55°C (up to about 80°C), the battery exhibits better rate capability due to faster electrochemical reactions and rapid ion transport in the electrolyte and electrodes. Under these conditions, side reactions become severe, leading to rapid capacity degradation. At temperatures above 80°C, the battery begins to suffer damage, and any temperature exceeding 130°C can cause the battery components to melt and potentially ignite a fire.

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Operating voltage and temperature are two factors that influence lithium battery safety.

Figure 1: Operating voltage and temperature are two factors that influence lithium battery safety. This example applies to NCM cells.

Low temperatures can cause poor battery performance and potential damage, but generally do not pose safety hazards. However, overcharging (excessively high voltage) can lead to cathode decomposition and electrolyte oxidation, which is a safety concern. Over-discharging (excessively low voltage) can cause the solid electrolyte interphase (SEI) on the anode to decompose and may lead to oxidation of the copper foil, further damaging the battery.

In addition to operational and environmental issues related to voltage and temperature, mechanical damage can also cause safety problems in LIBs. Given these concerns, LIB safety standards are equally extensive.

Five common safety standards for lithium-ion batteries are:

1. IEC 62133

2. UN/DOT 38.3

3. IEC 62619

4. UL 1642

5. UL 2580

IEC 62133 is a safety testing standard for lithium-ion cells and batteries, outlining safety requirements for secondary cells and batteries containing alkaline or non-acidic electrolytes. It is used to test LIBs used in portable electronic products and other applications. IEC 62133 addresses chemical and electrical hazards as well as mechanical issues such as vibration and shock that may threaten consumers and the environment.

UN/DOT 38.3 (also known as T1–T8 testing and UN ST/SG/AC.10/11/Rev. 5) covers transportation safety testing for all LIBs, lithium metal batteries, and cells. The test standard includes eight tests (T1 – T8), each focusing on specific transportation hazards. UN/DOT 38.3 is a self-certification standard and does not require independent third-party testing. However, using a third-party testing laboratory is common to reduce litigation risks in the event of an accident.

Several common packaging and safety transportation standards for lithium batteries (Table 1) include:

1. UN 3090 – Lithium metal batteries shipped as components.

2. UN 3480 – LIBs shipped as components.

3. UN 3091 – Lithium metal batteries shipped in or packed with equipment.

4. UN 3481 – LIBs shipped in or packed with equipment.
   

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Image: Several common packaging and safety transportation standards for lithium batteries.

Table 1: Many types of lithium batteries are considered hazardous materials and require special handling during transportation.

IEC 62619 covers safety standards for secondary lithium cells and batteries, specifying safety application requirements for LIBs in electronic and other industrial applications. The IEC 62619 standard test requirements apply to stationary and motive applications.

Stationary applications include telecommunications, uninterruptible power supplies (UPS), electrical energy storage systems, utility switching, emergency power, and similar applications. Motive applications include forklifts, golf carts, automated guided vehicles (AGVs), railways, and marine vessels—excluding road vehicles.

UL 1642 is a UL standard for lithium battery safety, specifying standard requirements for primary and secondary lithium batteries used as power sources in electronic products.

UL 1642 covers:

1. Technician-replaceable lithium batteries containing 5.0 grams (0.18 ounces) or less of metallic lithium. Batteries containing more than 5.0 grams of lithium are evaluated based on compliance with requirements (where applicable) and undergo additional testing and inspection to determine suitability for intended use.

2. User-replaceable lithium batteries containing no more than 4.0 grams (0.13 ounces) of metallic lithium per electrochemical cell and no more than 1.0 gram (0.04 ounces) of metallic lithium in total. Batteries exceeding 4.0 grams per cell or 1.0 gram total lithium require further inspection and testing to determine suitability for intended use.

UL 1642 does not cover toxicity risks from ingesting lithium batteries or risks of exposure to metallic lithium due to battery damage or cutting.

UL 2580 is the UL safety standard for electric vehicle batteries, consisting of multiple tests, including:

• High-Current Battery Short Circuit: Conducted on a fully charged sample. The sample is short-circuited with a total circuit resistance ≤ 20 mΩ. Spark ignition detects the presence of a flammable concentration of gas inside the sample, with no signs of explosion or fire. Additionally, no vapor is emitted to the outside through specified vents or the system. There must be no casing rupture or observable electrolyte leakage. If the LIB remains operational after the short circuit test, it undergoes charge and discharge cycles according to the manufacturer’s specifications. Short circuit tests may be performed on subassemblies rather than the entire electrical energy storage assembly (EESA).

• Battery Crush: Conducted on a fully charged sample to simulate the impact of a vehicle collision on the integrity of the EESA. As with the short circuit test, spark ignition detects the presence of a flammable concentration of gas inside the sample, with no signs of explosion or fire. No toxic gases are released.

• Battery Cell Crush (Vertical): Conducted on a fully charged sample. The force applied during the crush test must be limited to 1000 times the weight of the battery. As with the crush test, spark ignition detects the presence of a flammable concentration of gas inside the sample, with no signs of explosion or fire. No toxic gases are released.

LIB Test Chambers
Testing LIBs is inherently hazardous. Due to deep discharge, short circuits, high temperatures, and various types of mechanical abuse, off-gassing, fire, or explosion is likely to occur.

Specially designed LIB test and storage chambers have been developed to mitigate the risk of injury to personnel. One example is a walk-in, 90-minute fire-rated chamber with internal and external fire protection, usable as a test chamber or for storing LIBs (Figure 2).

Features designed to protect personnel and the environment include:
a. A pressure relief surface on the roof to balance internal and external pressure in case of an accident.
b. High-performance ventilation for rapid extraction of harmful or explosive gases.
c. The ability to inject inert gases to help control hazardous reactions or fires.
d. Fire sensors to warn of developing fires and integrated fire suppression systems.
e. Additional gas sensors to identify off-gassing, with provisions for placing more sensors and signal relays as needed.