Lithium-ion battery fires in Tokyo reached 179 cases by the end of May this year, marking a record-breaking pace [1].

This surge highlights a growing public safety risk as portable electronics become more ubiquitous. The increase in incidents suggests that current charging habits and device handling may be insufficient to prevent hazardous chemical reactions.

According to data from the Tokyo Fire Department, the number of fires through May is approximately 1.5 times higher than during the same period in 2025 [1]. In 2025, the count for the same period was 382 cases [1].

The department said the most frequent scenario for ignition occurs while devices are charging [1]. Officials said that physical impacts, such as dropping a device, can trigger fires.

Portable power banks are a significant contributor to the problem. Fires involving mobile batteries account for more than 30% of all lithium-ion battery-related blazes [3].

Seasonal trends also play a role in the frequency of these incidents. The Tokyo Fire Department said that fires tend to increase during the summer months [1]. This trend is often linked to overheating during charging, or exposure to high ambient temperatures.

Authorities continue to urge residents to use certified charging equipment and avoid leaving devices to charge unattended for long periods. The department said the risk of ignition increases when batteries are damaged or subjected to extreme heat.

“Lithium-ion battery fires in Tokyo reached 179 cases by the end of May this year.”

The rapid increase in battery fires in Tokyo reflects the broader challenge of managing high-energy-density lithium batteries in consumer electronics. As the volume of mobile power banks and high-capacity devices grows, the margin for error regarding heat management and physical damage narrows. The correlation with summer heat suggests that environmental factors can either trigger or accelerate battery failure, necessitating stricter safety standards for both manufacturers and end-users.