Page | 002 FIRE AND EXPLOSION THEORY OF LITHIUM ION BATTERY Combustion Triangle
Fire is a process involving rapid oxidation at elevated temperatures accompanied by the evolution of heated gaseous products of combustion, and the emission of visible and invisible radiation. The combustion process is usually associated with the oxidation of a fuel in the presence of oxygen with the emission of heat and light. Three components are necessary for combustion to occur: fuel, oxygen and an ignition source. It is the well known as the combustion triangle, which can be shown as Fig. 1. Recognizing these components and controlling their interaction is critical to safety.
Fig. 1. Combustion triangle.
The first component of the combustion triangle is fuel. There must be sufficient fuel present in the air to form an ignitable mixture. The fuel may be in the form of a gas, vapor, mist or dust. The second component of the combustion triangle is oxygen. For combustion to occur oxygen is necessary only at normal concentrations present in the air we breathe. The ignition sources are perhaps the most variable and unpredictable. For electrical equipment this may be from an arcing or sparking device or from a hot surface. There may be sources of ignition other than electrical equipment, such as hot exhaust surfaces from internal combustion engines.
Essentially all three elements must be present for fire to occur. Removal of fuel or oxygen will result in the fire being extinguished, if the fire itself is considered as a source of ignition, then, the removal of ignition source also will result in the fire being extinguished. Further fire research determined that a fourth element, a chemical chain reaction, was a necessary component of fire. The fire triangle was changed to a fire tetrahedron to reflect this fourth element. Here, the combustion triangle theory was used to explain the battery fire and explosion.
Contributions of Three Components in Lithium Ion Battery
The three components are also necessary for combustion or burning in lithium ion battery. The main fuel in lithium ion battery is electrolyte, which is a solution consists of organic solvent and inorganic salt. The most common solvents used in lithium ion batteries are the ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), and diethyl carbonate (DEC), and combinations thereof. Lithium
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