Investigation on effective fighting technology for LIB fire

Lithium-Ion Batteries (LIBs) convert the chemical energy obtained from the intercalation of lithium ions in the cathode material of the cell into electrical energy. They are called secondary batteries because are rechargeable. They are currently applied in portable applications (e.g., smartphone, tablet, personal computer), in mobility (e.g., Electrical Vehicles (EVs) and Plug-in Hybrid Electric Vehicles (PHEVs)) and Energy Storage Systems (ESS) for the higher energy and power densities than traditional batteries. LIBs due to their energy content and chemical composition are considered dangerous products that must be handled and used according to the manufacturer's safety indication, defined by the safety window (voltage and temperature ranges). If LIBs are used in conditions outside that window, they are subject to external and/or internal abuse, classifiable as mechanical, electrical, and thermal abuse. These conditions lead to a change in the chemical composition, due to melting of the separator and subsequent chemical reactions, and in the internal pressure, with consequent opening of the safety valve, when present, or of an area of the cell with less resistance welding. Because of the exothermicity of the reactions, the temperature of the system drastically increases in a short time giving rise to release of gas, vapours, fire and/or explosion with the projection of fragments. Due to the complexity of battery components and the diversity of conditions of use, the LIB fire classification is controversial. In view of the uncertainty, there are currently no unified and specific requirements for LIB fire suppression and effective LIB fire fighting technology is still a challenge. The suppression of the LIB fire involves the extinction of the open flame and the decrease in the temperature of the battery. If the battery temperature is sufficiently high after the flame has gone out, there is still a chance that the battery will reignite. To investigate how LIB fire can be effectively suppressed, Kokam lithium-ion batteries with a capacity of 25 Ah and 40 Ah were exposed to an open flame of propane and then extinguished using different agents (i.e., water mist, F500, and CO2). The cell temperature is monitored by thermocouples and the tested sample is recorded by a camera to obtain complete information on major events, such as venting, and thermal runaway in terms of temperature and time.