What is the liquid coming out of these Duracell batteries?
Well, it depends on which type of battery you have. Alkaline batteries such as Duracell Coppertop usually leaks KOH (potassium hydroxide) under conditions of misuse as a white foam. However, KOH is hygroscopic and will easily form a oily like liquid which is what you might be seeing in your batteries. Handle it with proper care since KOH is caustic and can cause tissue damage.