In the context of a ~1.5 V AA battery (the grandparent comment's lament), current over time is energy. Regarding internal resistance, the resistance of all mat

In the context of a ~1.5 V AA battery (the grandparent comment's lament), current over time is energy. Regarding internal resistance, the resistance of all materials drops when they get sufficiently hot, and even a volt or two is enough to get an arc going. Once that happens it will spread until the entire battery is converted to plasma. Given the energy densities the other commenter hoped for, the propagation rate is likely to be at the speed of sound, in other words a high-order explosion. Which is not surprising given that such a battery would amount to a stick of dynamite with electrode layers spaced every few molecules.