 Lithium ion batteries, LIBs, are commonly used in many applications due to their high energy density and power density. Unfortunately, they can experience thermal runaway, TR, which can cause fires or even explosions if not detected quickly enough. This paper reviews the current state of TR early warning and fire extinguishing technologies for LIBs. Early warning methods include acoustic, heat, force, electricity, and gas sensors, while fire extinguishing agents include halon, CO2, water mist, and foam. These technologies provide a basis for reducing the risk of fire and explosion from TR events. This article was authored by Ku Wang, Dongxiu Ouyang, Xinming Qian, and others.