Lithium-ion (Li-ion) are a trending battery type in many different buildings and industries and can be found in residential consumer electronics to electric skateboards, bikes and vehicles through to commercial power back-up/UPS, solar panel and grid-scale energy storage and military and aerospace applications.
Li-ion batteries capitalise on their ability to deliver high energy density, longer shelf life, and lower environmental impact than traditional technologies. As a result, Li- ion batteries have become the energy storage technology of choice for most electronic devices and equipment, small and large.
While billions of these batteries operate safely on a daily basis, as we know from media reports and even personal experiences, these batteries present a risk of thermal runaway. This document aims to provide businesses with general information about the various levels of risk associated with Li-ion batteries, as well as mitigation strategies to consider when managing such risks.
For Li-ion batteries, thermal runaway events generally begin with a single cell overheating; this ignites the electrolyte within that cell, which ignites adjacent cells. Causes of thermal runaway can range from inferior quality cells, manufacturing defects, mechanical and physical abuse, and overcharging.
Because lithium reacts exothermically with water, these fires are incredibly challenging to control and extinguish.
Certain lithium-ion battery chemistries can also release heavy metals and toxic smoke, which are costly to clean up and remediate when involved in a fire, especially in sensitive environments.
Below are the four stages of thermal runaway:
Stage 1: Abuse Factor
Stage 2: Off-Gas Generation
Stage 3: Smoke Generation
Stage 4: Fire Generation
Thermal runaway events in Li-ion batteries have resulted in the recall of millions of laptop batteries due to overheating reports and fires involving the batteries and chargers for "hoverboard" scooters and, more recently, e-bikes. While these events might be small in number compared to the billions of units in use with no reported adverse events, they reinforce the need for a robust risk assessment.
The loss examples in commercial and industrial settings are growing. For example, the Morris Lithium Battery Fire on June 29, 2021, was one of the biggest Li-ion battery fires in American history.¹ This event helped highlight how challenging it is to protect against and extinguish a fire involving Li-ion batteries in bulk storage. It also reinforced how critical hazard communication and fire department planning is to battle such a blaze. In 2018, another large fire occurred in Jamaica, New York, after a Li-ion battery was improperly disposed of, sparking a fire that brought the nearby Long Island Railroad to a halt. The fire grew rapidly due to nearby trash, piles of paper, cardboard recycling, and windy conditions. It took close to a full day to extinguish the fire.²
The severity of fire risk associated with the storage of Li-ion batteries is dependent upon the quantity of batteries, battery chemistry, physical form, energy rating (ampere-hours), state of charge (SOC), storage spacing and arrangement, and product packaging. Also, there is evidence of increased fire hazard due to rough handling and breach of battery integrity, such as puncture, with resultant thermal runaway – as lithium chemistries are reactive with oxygen. Inventory handling methods to ensure batteries are not damaged and identifying and isolating stock that may be damaged – is also key.
Keep only incidental storage quantities to protect Li-ion battery storage in high (extra) hazard sprinklered properties.
Incidental storage is accomplished by limiting the battery storage footprint to 20m² and height to 1.8 m while keeping >3 m of open space in between each pile and from other nearby combustibles. The goal is to spread out and lower the risk so that it is limited to one pallet in the event of a fire.
For most other occupancies, studies have shown that even a single pallet of Li-ion batteries can spread uncontrolled fire quickly. Consider relocating the storage offsite or outside and away from the structure, such as within a temperature- controlled storage container or at a secure third-party location.
Li-ion batteries may be stored in limited quantities in specially designed storage cabinets. Market options today include storage cabinets with integrated fire extinguishing systems, off-gas, and pressure relief designs to mitigate the smoke and fumes from a thermal runaway event.
Special sprinkler systems are necessary for bulk battery storage, such as warehousing. Often, this may include segregating storage into dedicated areas and sprinkler upgrades such as in-rack sprinklers and more robust ceiling storage sprinklers.
Material handling equipment (e.g., forklifts, pallet jacks, etc.) is quickly transitioning from traditional lead-acid to Li-ion batteries. Li-ion battery-powered material handling equipment relies on "opportunity charging," meaning the charging stations are decentralised throughout the storage area, allowing quick recharging.
Below are examples of the desired level of certification(s) for such battery systems when used in material handling equipment:
Other common marks include CE, CSA, and IEC. If the batteries, BMS (Battery Management System), and charging system are not UL Listed, they should meet an equivalent level of testing and approval.
It is important to have an emergency response plan to address the fire exposure and to train operators to identify the first signs of thermal runaway for a quick response – and give them formal training on actions to take in the event of a fire or thermal runaway involving the equipment.
Any physical damage to forklift batteries or their enclosure should be reported. It is also generally recommended that to install accessible incident response kits near equipment – such as fire-rated blankets, heat-resistant gloves, noncombustible containment drums, and fire suppression media.
Below are some best practices, which can be initiated within a facility:
Li-ion batteries are helping transition our energy needs today towards a more sustainable future away from carbon- based sources. However, Li-ion batteries present a unique and challenging fire risk, especially from thermal runaway. Battery form, chemistry, energy rating (Ah), listings/approvals, and manufacturing quality will all impact the unique risk profile of the batteries.
As these batteries continue to pervade businesses through bulk storage, integration, assembly, or even into newer material handling equipment, please reach out to Chubb Risk Engineering Services to explore options for safe use, handling, storage, and emergency planning and response best practices.
1. Morris Lithium Battery Fire,
3. UL 2580, "Standard for Safety for Batteries for Use in Electric Vehicles"
4. UL 2271, " Standard for Batteries for Use in Light Electric Vehicle (LEV) Applications"
5. UL 1998, "Standard for Safety for Software in Programmable Components"
6. UL 991, "Standard for tests for Safety- Related Controls Employing Solid- State Devices"
7. UL 583, “Standard for Safety for Electric Battery-Powered Industrial Trucks”
For more information about protecting your business, contact your local Chubb Risk Engineer, email us at Risk.Engineering.email@example.com, or visit www.chubb.com/au-en/business/risk-engineering-services
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