I came across a report about "Nonflammable Mobile Batteries" online. I would like to summarize and share some of the interesting points here. Mobile batteries are very useful when a smartphone's battery is running low outside. Most of them are Lithium-ion batteries and they become a current must-have. However, they have some issues. Especially, they are well-known for its having a flammable risk because they use flammable organic solvent. We sometimes saw the news that mobile batteries caught fire on the train and in the garbage truck. A certain company in Osaka developed Sodium-ion mobile batteries as nonflammable ones and started to sell them in mid-March. They said this is the world's first Sodium-ion mobile battery. They have different features from Lithium-ion batteries as follows, 1)High Safety. The battery is hard to overheat and can lower a risk of catching fire even if there is a heat in the battery. 2) Robust Temperature Feature. The battery works at between -35 and 50 degrees when it discharges. In the case of Lithium-ion mobile battery, the temperature is almost between 0 and 40 degrees. 3) Long lifespan. The battery has a lifespan of about 5,000 cycles. That's why it will be available for about 13 years even if it charges one time every day. Lithium-ion's is about 500 cycles. On the other hand, the main downsides are the size and the price. I want to use it as my battery charger in the future when I go outside in such scorching hot.