Why Thermal Runaway is the Real Killer in Battery Fires


by Dawson Johns, CEO Zenaji


We have all heard and seen of fires caused in Lithium-based batteries. The recent Tesla fire in Geelong, the fires in Griffith University, the Tesla car fires, the recall by LG of its Lithium batteries, and the list goes on and on in Australia and worldwide.

In 2019 the Government introduced new rules around safety and the installation of lithium batteries in the home but did nothing to examine what was causing the fires and the risk posed to human health. Instead, it looked to regulate the control systems of batteries and their installation. They simply lumped all lithium batteries together as if they were all dangerous and all suffered from the same problems.

They were wrong.

What is really happening and what should consumers be very wary of is that fires are almost exclusively caused by what is known as thermal runaway. Thermal runaway describes a process that is accelerated by increased temperature in turn releasing energy that further increases temperature. Thermal runaway can be initiated from mechanical or thermal failures.

Electro-chemical abuse from overcharging or over-discharging the cell can also start thermal runaway. Also, there’s the possibility of an internal short circuit within the cell which leads to thermal runaway.

Thermal runaway produces uncontrolled heat which leads to fire and or explosions of cells. Once one cell suffers from thermal runaway it can, and usually does, very quickly spread to other cells around the initiating cell so the whole battery bank is engulfed in fire very quickly.

Certain chemistries such as LFP (Lithium Iron Phosphate) and NMC (Nickel, Manganese, Cobalt) batteries and variants of these chemistries are prone to spontaneous internal shorts that result in thermal runaway. Despite the inherent dangers they are very energy-dense, lightweight, and in high demand so battery manufacturers continue to produce them particularly for cars and mobile devices.

However, there is lithium chemistry that is highly practical for stationary devices and does not suffer from thermal runaway unless massively overcharged. This is commonly known as LTO chemistry or Lithium Titanate batteries. With proper management controlling their charge, these cells never suffer from thermal runaway.

Where safety is a consideration in homes, businesses, commercial and industrial installations, LTO batteries are the only Lithium chemistry that offer the level of safety needed now and into the future.

Interestingly LTO cells provide storage and retrieval of power over their very long life at a much lower cost than other lithium batteries. They can be charged and discharged many times than their counterparts and will outlast all other current lithium chemistries by multiple times.

Market penetration of LTO technology is growing. Home storage systems using these cells are rapidly beginning to replace older less-safe chemistries. It is expected that government regulations will become chemistry-focused, limiting the use of LFP and NMC-based batteries.