Its an electrochemical battery like any other. In fact silver-zinc chemistry (like a hearing aid) is not all that unusual for this type of dry cell. However t

Its an electrochemical battery like any other. In fact silver-zinc chemistry (like a hearing aid) is not all that unusual for this type of dry cell. However the internal resistance from using paper as an "electrolyte" is incredibly high. So the weight or volume per power output ratio is extremely bad compared to anything. Even direct radio isotope batteries are worse. Radio isotope RTGs are worse. The "electrostatic" comes from the engineering model where you can pretty much treat it like a magic leyden jar that charges itself. A self charging high voltage capacitor of sorts.