Last night I heard a loud pop and was hit in the chest by the outer casing of a AA Duracell battery. No bruise. This a a first for me, but a quick Google search reveals it is reasonably common, at least for batteries installed in devices. Mine was not, it was in a Ziploc bag sitting on the granite ledge that separates our dining area from the kitchen. This picture sets the scene: the bag was sitting just to the left of the basket with fruit and avocados.
The battery was sitting in a Ziploc bag just to the left of the basket of fruit.
The remains: The top of the bag is detached and covered with battery innards. The outer casing hit me, just where the picture was taken from. The base piece with the short wire and the inner packing were found in the hallway just under the pictures in the distance. The plastic bag was still on the granite ledge.
The strength of the Ziploc seal compared to the bag itself is impressive
The debris field covers about a 4 ft x 4 ft area on the wall, with splatter on three of the picture frames and the wall itself.
Typical of the debris field. The largest spot is about 3/8 inch across.
I’m not sure what lesson this is suppose to teach me. Hadn’t seen such in my 60 years, so probably won’t again. I guess I am simply thankful that the battery was pointed such that I wasn’t the target of the debris.
Stance and Balance 
The Internet and I are begging for a chemist’s explanation, Russ.