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

Lithium-ion batteries (LIBs) are complex electrochemical and mechanical systems, the subject of dozens of international safety standards. In this FAQ, we'll discuss key environmental aspects of LIB safety, review common safety standards for lithium-ion batteries, and consider using a custom battery testing lab to ensure the safety of testing personnel.

Many LIB safety issues stem from the devices' sensitivity to voltage and temperature. Batteries are specified for operation within a temperature range of -30 to 55°C.

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.

Operating voltage and temperature are two factors affecting lithium battery safety.

Operating voltage and temperature are two factors affecting lithium battery safety. This example applies to NCM cells.

Low temperatures can cause poor battery performance and may damage the battery, but generally do not pose a safety hazard. However, overcharging (excessive voltage) can lead to cathode decomposition and electrolyte oxidation, a safety concern. Over-discharging (excessive 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 cause safety problems with lithium-ion batteries (LIBs). Given these concerns, safety standards for LIBs are also 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 batteries and batteries, outlining the safety requirements for testing secondary batteries 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 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 litigation risks in the event of an incident.

Several common packaging and safe transport standards for lithium batteries (Table 1) are as follows:

1. UN3090 Lithium metal batteries, transported as components

2. UN3480, LIBs, transported as components

3. UN3091 Lithium metal batteries transported in or packaged with equipment

4. UN3481, LIBs transported in or packaged with equipment.

Many types of lithium batteries are considered hazardous materials and require special handling during transport. 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 stationary and powered applications.

Stationary 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-excluding road vehicles.

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

UL 1642 covers:

1. Technician-replaceable lithium-ion batteries 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 subject to additional testing and inspection to determine their suitability for their intended use.

2. User-replaceable lithium batteries, with 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 if the battery or cell is suitable for its intended use.

UL1642 does not cover the risk of toxicity from ingestion of lithium batteries or the risk of exposure to lithium metal due to battery damage or cutting.

UL2580x is the UL safety standard for electric vehicle batteries, consisting of several tests, including:

High-current battery short circuit: Run on a fully charged sample. Short-circuit the sample using a total circuit resistance of ≤ 20 mΩ. Spark ignition detects the presence of flammable gas in the sample, with no signs of explosion or fire. Furthermore, vapors do not escape 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 a short-circuit test, it will undergo charge and discharge cycles according to the manufacturer's specifications. Short-circuit testing can be performed on sub-components, not the entire Energy Storage Assembly (EESA).

Battery Crushing: Runs on a fully charged sample and simulates the impact of a vehicle collision on the EESA integrity. Similar to the short-circuit test, spark ignition detects the presence of flammable gas concentrations within the sample, and there is no indication of explosion or fire. No toxic gases are released.

Battery Cell Crushing (Vertical): Runs on a fully charged sample. The force applied during the crushing test must be limited to 1000 times the battery weight. Similar to the crushing test, spark ignition detects the presence of flammable gas concentrations within the sample, and there is no indication of explosion or fire. No toxic gases are released.

LIB Test Chamber

Full testing of the LIB is 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 test and storage chambers 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 test chamber or storage LIB (Figure 2).

Features designed to protect people and the environment include:

a) A depressurizing surface on the roof to balance internal and external pressure in the event of an accident.

b) High-performance ventilation for rapid extraction of hazardous 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 for identifying degassing and the location of additional sensors and signal relays 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 over-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 test chamber.