Lithium ion batteries (LIBs) are booming due to their high energy density, low maintenance, low self-discharge, quick charging and longevity advantages. However, the thermal stability of LIBs is relatively poor and their failure may cause fire and, under certain circumstances, explosion. The fire risk hinders the large scale application of LIBs in electric vehicles and energy storage systems. This manuscript provides a comprehensive review of the thermal runaway phenomenon and related fire dynamics in singe LIB cells as well as in multi-cell battery packs. Potential fire prevention measures are also discussed. Mitigating the hazards associated with a growing number of LIB applications represents a significant new challenge for the fire safety engineering community. Some perspectives and outlooks on the future of LIB fire safety research and safety engineering are given. (C) 2019 Elsevier Ltd. All rights reserved.