There have been many reports about older batteries swelling and exploding, but rarely is there a story about a brand new one doing so.  In Maine, a middle schooler sustained second degree burns when her 2 month-old iPhone 5c battery exploded while in her pants, lighting them on fire.  The girl stopped, dropped, and rolled, which extinguished the fire.  She then had to take off her pants, so her female classmates put her in a corner and formed a semi-circle, shielding her from view, while the boys alerted a teacher, who got a blanket.  The girl was treated at the hospital, and released.

Batteries can overheat while being charged, which most frequently occurs on older devices with older batteries.  It is rare for a newer device to overheat, especially while detached from the wall.  The most publicized examples of a battery overheating occurred on two Boeing 787 Dreamliners while on the ground, which further delayed the production of the airliner and required a significant redesign.  There have been reports of other iPhone and Samsung Galaxy batteries overheating, but rarely when detached from the charger.

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