Investigation on the fire hazards of Li-Ion cells

Li-ion batteries had a great development in recent years, and their use has grown massively because of their higher energy and power density with respect to traditional ones. However, their high energy density implies great danger in the event of malfunctions or failures, due to the emission of toxic and highly flammable substances. In the worst case, thermal runaway can occur. It is a chain reaction where unwanted reactions take place that leads to an uncontrolled and unstoppable increase in temperature. It can cause uncontrolled combustion and then explosion with great danger. In order to identify the conditions that lead to the thermal runaway and to limit its occurrence, thermal stability of Li-ion batteries is here investigated. Thermal abuse tests are performed on lithium nickel manganese cobalt oxide cells from Panasonic in an ISO 5660 cone calorimeter. Heat release rate is measured by changing the state of charge (SoC) of the cells and the radiant power of the cone calorimeter. The relationship between the SoC and the onset of the heat release is clearly revealed.