The penetration of LiBs into all levels of society is driven by their very high energy densities, meaning that LiBs are a fraction of the size and weight of other batteries: however, a device containing such high energy densities comes at a price – we must understand the risks and hazards associated with it in order to manage them, but it appears that the penetration of LiBs has not been matched by our understanding of the risks and hazards.
When heat is generated faster than it can be dissipated, the cell goes into irreversible thermal runaway
If a lithium ion cell is abused, by overheating, overcharging or crushing, chemical reactions can be triggered that generate heat, hydrogen, carbon monoxide, hydrogen cyanide, hydrogen fluoride, a mixture of light hydrocarbon gases, oxygen and small droplets of the solvent- and more heat. The heat speeds up the chemical reactions generating more heat and more gases.
When the heat is generated faster than it can be dissipated, the cell goes into irreversible thermal runaway. Whilst inside the cell, there is insufficient oxygen to sustain fire. When the cell bursts or vents via a valve or blast cap, the gas may ignite which produces jet-like flames. If there is insufficient air (as in a LiBESS) or at low states-of-charge, vapour cloud may not ignite immediately.
If delayed ignition occurs, there could be a possibility of a flash fire, fire balls developing, or in extreme cases, even a vapour cloud explosion.
The latter occurred at a 2MW LiBESS in Surprise, Arizona in April 2019 resulting in nine firefighters being contaminated with hydrogen cyanide and four being injured, two very seriously after being blown over 20 m under a chain metal fence. There have been ca. 30 fires and explosions in LiBESS in the last 2 or 3 years, and the first explosion on British soil occurred in September of this year at the 20MW Carnegie Road facility.
Our fire and rescue services are on a major and rapid learning curve
There have also been many electric vehicle (EV) fires (including ca. 30 per annum in China) as well as fires on board hybrid ferries and electric aircraft. Our fire and rescue services are on a major and rapid learning curve: as well as the danger of vapour cloud explosion or fire and toxic gases, there is also risks associated with stranded electrical energy and associated electrocution (EV battery packs can be 600V) and arc flash. In addition, EV packs have re-ignited hours, days and weeks after the initial incident, and have done so many times.
Lithium ion batteries are amazing and essential for the decarbonisation of the planet, but all stakeholders need to understand the associated risks and hazards, from EV owners, LiBESS operators, householders with domestic LiBESS, first responders and the public – including you!
Featured Image: Pikist
