➀ Researchers from the University of Tokyo have developed a cost-effective method to test lithium-ion batteries for overheating, aiding in the design of safer batteries.

➁ The new method involves creating a miniature battery that is more prone to thermal runaway, allowing easier study in laboratory settings.

➂ By using a thermal runaway factor (TRF), the method evaluates the likelihood of a battery overheating based on its energy storage, volume-to-surface ratio, and material properties.