The sulfide-manganese dioxide battery and the electrochemical energy sources in the hypothesis of Wachtershauser concerning the origin of life

Recently we could show that elementary sulfur is an excellent cathode mater ial at room temperature in zinc-sulfur batteries as it is reduced rapidly i n aqueous solutions on the surface of iron sulfide electrodes [1]. In this context, the electrochemical reaction of solid elementary sulfur on iron su lfide surfaces in sea water was discussed which could have been one of the energy sources playing a role in the development of life. In the theory of Wachtershauser, the first energy source of life is the formation of pyrite from iron sulfide and hydrogen sulfide, and the first step is the reduction of carbon dioxide on iron sulfide surfaces. We could show that sulfide ions are oxidized rapidly to disulfide ions on t he surface of iron sulfide. The capacity and the specific energy of a sulfi de-manganese dioxide battery with an open cell voltage of about 0.8 V are c omparable to those of commercially available zinc-manganese dioxide batteri es. An electrochemical cell where sulfur is reduced on the surface of an ir on sulfide cathode and sulfide ions are oxidized on the surface of an iron sulfide anode affords an open-cell voltage of about 0.4 V at 95 degreesC.