A recent survey by the Canadian Association of Fire Chiefs found about 1,500 lithium‑battery fires across 600 Canadian communities last year, and the number is climbing as more devices use these cells.

A lithium‑ion battery stores energy by keeping its positive and negative terminals apart with a thin barrier. When that barrier is breached – by a drop, a crash, or a faulty charger – the terminals can touch, creating a short circuit that ignites the cell.

If the heat from that ignition reaches a critical point, the battery enters what experts call "thermal runaway." Paul Boissoneault, president of the association and chief of the Oakville Fire Department, explains that in thermal runaway the heat speeds up internal chemical reactions, which in turn generate even more heat.

During the runaway, a metal‑oxide material in one terminal breaks down into metal and oxygen gas. The released oxygen feeds the fire from inside the battery, meaning that simply smothering the flames with a blanket is ineffective.

The intense heat also forces the battery’s chemicals to decompose, releasing toxic gases such as hydrogen fluoride. These fumes can settle on firefighters’ clothing and equipment, contaminating gear with substances like formaldehyde and heavy metals that must later be removed.

Because the fire creates its own oxygen and produces toxic gases, water alone cannot fully extinguish it. Randy Narine, a professional firefighter in Brampton, Ontario, who studies lithium‑battery safety through his company Clean Core Research, estimates that while a gasoline‑car fire may need under 2,000 litres of water, a lithium‑battery fire can require tens of thousands of litres. Moreover, Boissoneault notes that only about 40 percent of the fire departments surveyed had formal training on handling lithium‑battery incidents.

Understanding these mechanisms shows why lithium‑ion fires burn hotter, spread faster, and are harder to control than ordinary fires, and why specialized equipment and training are becoming essential for modern fire services.