Smartphones, portable chargers, wireless earphones: mobile electronic devices have become an indispensable part of our daily lives, and all of them contain lithium-ion batteries. But the number of accidents involving these batteries is on the rise. As batteries age and degrade over time, flammable gas can build up inside, creating a risk that they will suddenly ignite. We look at what to buy, how to use devices safely, and how to dispose of lithium-ion batteries correctly. Guest: Ikeya Tomohiko (Associate Vice President, Central Research Institute of Electric Power Industry)