Zinc Chloride

These reduce the amount of NH₄Cl (Ammonium Chloride) and replace it with Zinc Chloride (ZnCl₂)

Zn(s) + 2 MnO₂(s) + ZnCl₂(aq) + 2 H₂O(l) -> 2 MnO(OH)(s) + 2 Zn(OH)Cl(aq)

These were originally marketed as HP or High Power Cells, but today even ordinary Zinc Carbon are marketed as Heavy Duty and High power. It’s claimed a x2 increase in capacity, but actually this is purely due to lower internal resistance partially due to less “polarization” from hydrogen on the electrode and thus is only true at higher currents when an Alkaline cell is better value. This is why in on a torch when it dims turning it off at once and leaving it a while it “bounces back” hence the “9 lives” and “bounces back” text with the Eveready cat in the 1930s and today. On very low current drain (like 10mA Radio HT) there is little advantage to Zinc Chloride. The UK Ever Ready promoted these as “HP” cells and batteries instead of producing Alkaline as existing Zinc Carbon factory production could be used. The Alkaline cells already existed.