By coupling high-speed X-ray tomography and thermal imaging methods, researchers have demonstrated that events occurring inside a lithium-ion battery as it heats up and explodes can be imaged in high resolution and real time (Nat. Commun. 2015, DOI: 10.1038/ncomms7924). The three-dimensional imaging method provides a novel way to investigate heat-induced damage to internal structures of Li-ion batteries, which could lead to improved battery safety. Standard analytical methods are limited to scrutinizing the internal components of failed batteries only after the events that caused the failure have run their course. So a team led by Paul R. Shearing of University College London devised the tomography method and used it to study two standard types of commercial Li-ion batteries as they heated the battery shells to roughly 250 °C. One battery, strengthened with an internal support, remained largely intact until chemical reactions triggered thermal runaway. The internal temperature then spiked above 1,000 °C, melting copper structures inside the battery. The other battery simply exploded, blowing off the battery cap and ejecting molten material.