[Insight & Opinion] Reasonable Regulations for Carrying Portable Batteries Onboard

Vulnerable to Heat and Pressure
Utilize the '30% or Less State of Charge' Rule
Clear Guidelines Must Be Provided to Passengers

Airlines are strengthening their management of lithium-ion batteries carried onboard. The key measures include recommending that passengers carry batteries themselves and prohibiting storage in overhead bins. However, the specific measures taken by airlines are inconsistent. Some even absurdly require the use of ‘zippered plastic bags.’ The Ministry of Land, Infrastructure and Transport is also preparing an ‘Aviation Safety Innovation Plan’ that regulates limits on the number of batteries carried, designated storage locations, and verification of product information labeling.

Most lithium-ion battery fires are caused by external ‘pressure’ or ‘heat.’ In particular, physical deformation of the battery due to external pressure is problematic. If the separator inside the lithium-ion battery is damaged, a severe internal short circuit occurs, leading to uncontrollable thermal runaway. The situation worsens if the external pressure persists for a long time. This is why the International Air Transport Association (IATA) prohibits batteries in checked baggage.

It is the airline’s responsibility to clearly inform passengers that portable batteries are vulnerable to external pressure. Passengers must be reliably informed not to apply excessive force to bags containing batteries. Plastic bags, which are ineffective against forces applied to batteries, cannot be a practical alternative. In fact, fires caused by external short circuits in lithium-ion batteries are rarely found. The Ministry of Land, Infrastructure and Transport should fully reflect this fact in its innovation plan.

It is also important to note that the risk of lithium-ion battery fires increases according to the ‘state of charge.’ This is a unique characteristic of lithium-ion batteries, which have a completely different structure from traditional batteries that use chemical oxidation-reduction reactions. As the state of charge increases, the amount of lithium ions accumulated at the anode (- pole) increases, raising the possibility of internal discharge that triggers thermal runaway.

The ‘30% or less state of charge’ regulation, which the International Civil Aviation Organization (ICAO) has applied to cargo on cargo-only aircraft since 2016, should be actively utilized. This means passengers should be advised to sufficiently reduce the state of charge of portable batteries before boarding the aircraft. Transferring the electricity from the portable battery to a high-quality battery-powered phone can be a practical alternative. Of course, this is inconvenient for consumers who want to use portable batteries conveniently. However, considering the possibility of a terrible aircraft fire, such inconvenience must be willingly endured.

Accurate information on extinguishing lithium-ion battery fires is also important. If a fire extinguisher cannot be used, the most reliable alternative is to submerge the portable battery in a water tank filled with a sufficient amount of water. Due to the nature of battery fires that spread uncontrollably in an instant, there is no time to hesitate. It is necessary to prepare water tanks in several locations inside the cabin. The information that water should not be used on battery fires is baseless fake news.

Consumer awareness regarding portable batteries must also be improved. Consumers purchasing portable batteries should always remember the proverb ‘You get what you pay for.’ Cheap portable batteries cannot be trusted for the stability of their separators.

The government must also drastically strengthen quality control of portable batteries. The confusing issue of distinguishing them from single-use button-shaped lithium (metal) batteries must also be resolved.

Deokhwan Lee, Professor Emeritus at Sogang University, Chemistry and Science Communication