Why do Lithium-Ion Batteries Catch Fire
We have all seen the news reports of fires caused by batteries in e-bikes, e-scooters and other devices which contain these batteries. Why does this happen and are there ways in which the risks can be minimised?
Firstly, we should point out that fires caused by L-Ion batteries are rare. Many of the electric goods we use every day contain lithium batteries including phones, lap tops, cars, power banks, e-cigs and others. Even though fires are rare the consequences of a fire can be terrible with damage to property and loss of life.
Anyone who travels by air should now be aware that airlines do not allow lithium batteries in checked luggage, they must be taken onto the aircraft with carry on baggage. This is because a fire in the cabin will be seen by crew/passengers and can be dealt with. Do you remember the Samsung phone fires a few years ago – as a result of that airlines now carry fire containment bags into which a device containing a lithium battery which is smoking or about to catch fire can be placed. In 2022 the FAA recorded 62 incidents involving lithium-ion batteries, more than 1 per week. The majority are power banks and vape devices.
So why do they catch fire? A battery of any type is a device which is used to store electricity. Lithium based batteries are so popular because the amount of energy which can be stored per size/weight is higher than most other types. The down side is also that they contain lithium, which is highly reactive. If the battery is damaged, if there is a manufacturing defect or an electrical problem the combination of the stored energy and the lithium can result in a specular fire. 
Lithium batteries operate most efficiently between 20 degrees and 40 degrees centigrade. The device they are powering will contain a battery management system which manages the heat output and will usually stop the battery from operating at a certain threshold temperature (normally around 60 degrees C). If for some reason this does not happen a “thermal runaway” can occur possibly resulting in a fire due to evaporation of the electrolyte.
Over charging, physical damage, a short circuit, manufacturing defects or exposure to high temperatures can all be the cause of a thermal runaway or fire.
How can we minimise the risk –
Only use batteries which are from a reputable manufacturer. Buying the cheapest possible e-bike or e-scooter might seem a great deal at the time but the unbranded batteries with poor quality control during manufacture can be a time bomb. Look at who makes the batteries and the battery management system. Opt for Sony, Panasonic, LG or similar if you can.
Only charge batteries with the charger supplied or approved by the manufacturer. A high output charger might reduce the charging time but it could also damage the batteries.
Do not leave batteries charging in unoccupied places or overnight.
Do not store anything containing L-ion batteries in places where they may be exposed to high temperatures.
Do not used damaged batteries. Protect those you are using against mechanical damage. Dispose of any which show signs of damage safely.
Swelling or bulging of the battery can be an indication that they are damaged or that the electrolyte is / has evaporated.
Consider using fire proof battery cases or bags for storage.
How to minimise risks from L-Ion batteries-
Incidents of battery fires on planes-
Chemical exposure risks from L-Ion batteries-
https://www.prevor.com/en/li-ion-batteries-chemical-hazard-inside-our-cars/
