Lithium-ion batteries (LIBs) are complex electrochemical and mechanical systems, the subject of dozens of international safety standards. In this FAQ, we will discuss key environmental aspects of LIB safety, review common safety standards for lithium-ion batteries, and consider using custom battery testing labs to ensure the safety of testing personnel.
Many safety issues with lithium-ion batteries (LIBs) arise because these devices are sensitive to voltage and temperature. Figure 1 illustrates the behavior of a Li(Ni0.5Co0.2Mn0.3)O2 (NCM) battery. In this example, the battery is specified to operate over a temperature range of -30 to 55°C.
At temperatures above 55°C (to approximately 80°C), batteries exhibit better rate capability due to faster electrochemical reactions and rapid ion migration in the electrolyte and electrodes. Under these conditions, side reactions become severe, leading to rapid capacity decay. Above 80°C, batteries begin to deteriorate, and any temperature above 130°C can cause battery components to melt and potentially ignite a fire.
Low temperatures can lead to poor battery performance and potentially damage, but generally do not pose a safety hazard. However, overcharging (excessively high voltage) can cause cathode decomposition and electrolyte oxidation, which is a safety concern. Over-discharging (excessively low voltage) can cause the solid electrolyte interface (SEI) on the anode to decompose and may lead to copper foil oxidation, further damaging the battery.
In addition to operational and environmental issues related to voltage and temperature, mechanical damage can also lead to safety problems with the LIB. Given these concerns, safety standards for LIBs are also extensive.
The five common safety standards for lithium-ion batteries are:
1. IEC62133
2. UN/DOT38.3
3. IEC62619
4. UL1642
5. UL2580
IEC 62133 is a safety testing standard for lithium-ion batteries and tertiary batteries, outlining the safety requirements for testing secondary batteries and tertiary 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 that can threaten consumers and the environment, as well as mechanical issues such as vibration and shock.
UN/DOT 38.3 (also known as the T1-T8 tests and UN ST/SG/AC.10/11/Rev. 5) covers transport safety testing for all LIBs, lithium metal batteries, and batteries. The testing standard comprises eight tests (T1 – T8), each focusing on specific transport hazards. UN/DOT 38.3 is a self-certification standard and does not require independent third-party testing; however, the use of third-party testing laboratories is common to reduce the risk of litigation in the event of an incident.
Several common packaging and safe transportation standards for lithium batteries (Table 1), such as:
1. UN3090 lithium metal battery, transported as a component.
2. UN3480, LIB, transported as a component.
3. UN3091, Lithium metal batteries transported in or packaged with equipment.
4. UN3481, LIB is transported in the equipment or packaged with the equipment.
IEC 62619 covers safety standards for secondary lithium-ion batteries and battery packs, specifying safety application requirements for LIBs in electronic and other industrial applications. The IEC 62619 standard testing requirements apply to both static and dynamic applications.
Fixed applications include telecommunications, uninterruptible power supplies (UPS), energy storage systems, utility switches, emergency power supplies, and similar applications. Powered applications include forklifts, golf carts, automated guided vehicles (AGVs), rail and marine vehicles—excluding road vehicles.
UL1642 is the UL standard for lithium battery safety, which specifies the standard requirements for primary and secondary lithium batteries used as power sources in electronic products.
UL1642 covers:
1. Replaceable lithium batteries by technicians, containing 5.0 grams (0.18 ounces) or less of metallic lithium. Batteries with a lithium content exceeding 5.0 grams will be judged on their compliance with requirements (if applicable) and will undergo additional testing and inspection to determine whether the battery is suitable for its intended use.
2. User-replaceable lithium batteries, each electrochemical cell containing no more than 4.0 grams (0.13 ounces) of lithium metal and no more than 1.0 gram (0.04 ounces) of lithium metal. Batteries containing more than 4.0 grams or more than 1.0 gram of lithium require further inspection and testing to determine whether the battery or its intended use is feasible.
UL1642 does not cover the risk of toxicity from ingesting lithium batteries, or the risk of exposure to metallic lithium due to battery damage or cutting.
UL2580x is UL's electric vehicle battery safety standard, which consists of multiple tests, including:
High-current battery short circuit: Run on a fully charged sample. Short-circuit the sample using a total circuit resistance of ≤ 20mΩ. Spark ignition detects the presence of flammable gas in the sample, with no signs of explosion or fire. Furthermore, vapors are not vented to the outside through designated vents or systems. There are no signs of casing rupture or observable electrolyte leakage. If the LIB remains operational after the short-circuit test, it will undergo charge and discharge cycles according to the manufacturer's specifications. Short-circuit testing can be performed on sub-assemblies rather than the entire Energy Storage Assembly (EESA).
Battery Crush: This test runs on a fully charged sample and simulates the impact of a vehicle collision on EESA integrity. Similar to the short-circuit test, spark ignition detects the presence of flammable gases within the sample, ensuring there are no signs of explosion or fire. No toxic gases are released.
Battery cell crushing (vertical): This test is performed on a fully charged sample. The force applied during the crushing test must be limited to 1000 times the weight of the battery. Similar to the crushing test, spark ignition detects the presence of flammable gases within the sample, ensuring there are no signs of explosion or fire. No toxic gases are released.
LIB Testing Lab
Full-testing LIBs are inherently a hazardous activity. Degassing, fire, or explosion is possible due to deep discharge, short circuits, high temperatures, and various types of mechanical abuse.
Specially designed LIB testing and storage rooms have been developed to mitigate the potential for injury to personnel. One example is a walk-in 90-minute fireproof room with internal and external fire protection, which can be used as a testing room or for storing LIBs (Figure 2).
Functions designed to protect people and the environment include:
a. The roof has pressure-reducing surfaces to balance internal and external pressure in the event of an accident.
b. High-performance ventilation systems for the rapid extraction of harmful or explosive gases.
c. The ability to inject inert gas to help control hazardous reactions or fires.
d. Fire sensors for warning of developing fires and integrated fire suppression systems.
e. Additional gas sensors are used to identify degassing, and more sensors and signal relays are placed as needed.
In summary, the lithium metal content in lithium-ion batteries means they pose a potential hazard to users of battery-powered systems. LIB safety hazards include deep discharge, short circuits, high temperatures, and mechanical abuse. There are dozens of international safety standards and design requirements for lithium-ion batteries. This article introduces five common safety standards for lithium-ion batteries, as well as some basic considerations when designating a LIB testing laboratory.
