What you should know about lithium-ion batteries after 1 caused a fire on a train in Hong Kong

According to police, the train was arriving at Yau Tong MTR station when the incident occurred at around 8:57 a.m. that day. Firefighters investigated how the lithium battery could have caught fire.

Here’s what you need to know about the potential dangers of devices that use lithium-ion batteries.

1. How widespread are lithium-ion batteries?

A lithium-ion battery is a type of rechargeable battery commonly used in cell phones, laptops, portable power banks, rechargeable fans, e-bikes and certain electric vehicles.

2. What are the signs that you should stop using?

According to the Consumer Council, users should immediately stop using products with lithium-ion batteries and unplug the charger if the batteries are deformed, damaged or overheated.

The US-based Electrical Safety Foundation also recommends users to stop using any device or battery that has an unusual odor, color change or excessive heat. Users should also stop using the device if the battery changes shape, leaks, smokes, or no longer holds a charge. Damaged or overheated batteries could cause a fire, it said.

3. Why do batteries wear out?

According to the Consumer Council, charging and discharging of batteries occurs through a process in which lithium ions diffuse through the electrolyte between the anode and cathode.

However, the lithium ions in the battery slowly react chemically with other substances and are converted into compounds that can neither be charged nor discharged. The resistance of the battery also increases over time, which leads to more heat being generated during charging or discharging. The battery capacity gradually decreases, resulting in a shorter charging time.