On methods to measure the energetics of a lithium ion battery in thermal runaway

Methods are described for measuring the energy released by a Li-ion battery in thermal runaway. A calorimetry technique is described to measure the exothermic energy released during thermal runaway. The technique uses the battery as a calorimeter with temperature and mass loss measurements to analyze the energetics. Runaway is induced by heating of the battery. Only one battery is investigated over a range of heating power and state of charge (SOC). The dynamics of the battery are investigated including time events, temperature, mass lost and energies. The total energy in runaway is manifested by the internal energy stored in the battery and the enthalpy of the ejected mass. Combustion of the ejected gases is described by a technique using the Cone Calorimeter. Results are reported. Both of these techniques are considered less desireable because of the rapid release of energy therefore two new techniques are proposed. The technique of Lyon&Walters using a standard Bomb Calorimeter with nitrogen instead of oxygen to measure the runaway exothermic energy, and measurement of the resulting ejected gas composition to measure the combustion energy.