Lithium-ion batteries have become part of everyday life, powering everything from smartphones to solar backup systems. Thermal runaway refers to a rapid, uncontrollable rise in temperature caused by chain reactions inside the battery. Lithium-ion batteries have a limited lifespan and once they are fully depleted, you can’t put them on again. He explained that piercing, such as from an impact or object falling on a battery, can lead to thermal runaway. The takeaway from specialists across the board is clear: lithium-ion batteries must be treated with care.