A charged lead/acid battery will have one plate lead and the other plate lead oxide. They are immersed in sulphuric acid. When the battery is discharged, both plates are lead sulphate and the acid is very weak.
A zinc/carbon battery has a case of zinc, when the battery is exhausted, the case will be very thin and the battery often leaks.
There are many different battery chemistries, I have never found a good one yet. !!