Method of evaluating relative safety of porous electrode/electrolyte combinations to spot heating

Thermal abuse situations involving batteries can conveniently be classified into two broad categories, one involving relatively uniform heating of the battery contents and the other involving highly localized heating inside a battery. Reliable prediction of battery behaviour during abuse is difficult to do by modelling and often quite expensive to do empirically. The relative safety of systems exposed to uniform heating can be quantified using hot box or accelerating rate calorimeter techniques. Here, a simple, inexpensive method of quantifying the relative safety of systems exposed to local heating is discussed. Laboratory size batteries of coin-cell format are reproducibly exposed to localized heating at a container/porous electrode interface using conventional spot welding equipment. Some electrode/electrolyte combinations used in lithium-ion-type batteries were evaluated in this manner. In particular, the effects of state of lithiation on and differences between LiCoO2 and LiNiO2 electrodes were studied.