October 14, 2026
Key Points
- Lithium-ion batteries can create unique fire and electrical hazards when cells enter thermal runaway.
- Battery safety becomes increasingly important as lithium-ion technology is used across a wider range of products and in larger, more complex energy storage systems.
- Managing lithium-ion battery risk requires a multifaceted approach that includes quality design and manufacturing, third-party certification, user education and emergency response.
Lithium-ion batteries power many of the products and systems people rely on every day, from phones and laptops to e-bikes, electric vehicles and large battery energy storage systems. But when something goes wrong, the way these batteries fail can create hazards that behave differently from other types of fires.
In a recent article for In Compliance Magazine, UL Solutions experts Bruce Johnson, regulatory services manager for the Industrial TIC group, and LaTanya Schwalb, principal engineer for the Energy and Industrial Automation group, explain those hazards and why understanding thermal runaway is an important part of managing lithium-ion battery risk.
The article answers several key questions:
What is thermal runaway and why does it matter?
Thermal runaway occurs when a lithium-ion cell generates heat faster than it can dissipate it, creating a self-accelerating process that can push the cell further into failure. Once it begins, thermal runaway can spread to adjacent cells in a process known as propagation, turning an isolated problem into a much larger event.
What can cause a lithium-ion battery to fail?
Battery failures can result from manufacturing or design defects, environmental conditions, physical damage or electrical abuse. Contributing factors can include internal contamination, extreme temperatures, moisture, crushing, overcharging and short circuits. Some conditions can develop internally before there are external signs of a problem.
Why do lithium-ion batteries require a different approach to fire safety?
Lithium-ion battery failures can create several hazards simultaneously and escalate rapidly. Thermal runaway can generate intense heat, release flammable and toxic gases, eject hot material and spread from one cell to another. Lithium-ion batteries can retain energy after visible flames are controlled, creating the potential for reignition.
How does battery safety change as energy storage systems grow larger and more complex?
Battery energy storage systems use the same underlying lithium-ion technology found in smaller applications, but they scale that stored energy into larger and more complex installations. As systems grow, managing risk increasingly depends on how they are designed, installed, used and controlled, including how the system responds if a cell fails.
What can we learn from real-world lithium-ion battery fires?
The Fire Department of the City of New York’s experience shows how quickly lithium-ion battery incidents can develop. FDNY documented 268 lithium-ion battery-related fires in 2023 and 277 in 2024. The In Compliance article notes that micromobility devices such as e-bikes and e-scooters were a particular concern as these incidents increased.
How can lithium-ion battery risk be managed?
Managing lithium-ion battery risk requires a multifaceted approach. The In Compliance article highlights quality design and manufacturing, third-party certification, user education and emergency response.
Where can I learn more?
Read the In Compliance article: “Why the Hazards of Lithium-Ion Batteries Require a Different Approach to Safety.”
Additional information is available in the article “Safety Guidelines for Large Lithium-Ion Battery Systems” published on UL.com.