Learning lessons from accidents has always been very instructive for developing inherently safer technologies and processes. This paper aims to show that lithium-ion rechargeable battery (LIB) technology is no exception, as the penetration of these devices into society has been accompanied by a number of significant fires and explosions. The relatively small incidents involving LIBs arose from their application in an ever wider and more varied range of portable electronic products in the mid 2000's, leading to, for example, repeated recalls of laptop computers. Later it became apparent that failures could and would occur in the full value chain of LIBs, starting from the manufacturing of cells up to end-of life issues and recycling. The true nature of the risks and hazards of LIBs has only started to become apparent with larger batteries, for example those associated with e-mobility (electric vehicles) and grid-scale battery energy storage systems, and hence this paper focusses on the lessons to be learnt from incidents involving these systems.