The possibility of utilization of the lead-air electrochemical system as a power source is shown. The system consists of a standard lead electrode and H ₂ SO ₄ electrolyte, used in the lead acid battery and a gas diffusion electrode developed in the Institute of Electrochemistry and Energy Systems. Three catalysts have been checked for applicability with the new system-active carbon Norit NK, cobalt tetramethoxyphenylporphyrin and cobalt phthalocyanine. Cyclic voltammetry has been applied to all three catalysts and the results have been presented as galvanostatic charge-discharge curves. Polarization and Tafel dependences have been studied in a three-electrode cell. An original method for formation of the lead electrode has been elaborated. It has been established that the gas diffusion electrode is sufficiently stable in the sulphuric acid electrolyte. The energy values obtained at laboratory conditions provide a good perspective for a practical application of the lead-air system for energy storage and in the automobile industry.

Thermally treated caffeine doped active carbon (Caffeine-Norit) is studied as a catalyst for the oxygen reduction reaction (ORR) with application in metal-air systems with neutral aqueous electrolytes. Catalytic activity is characterized by polarization curves and Tafel plots and the results are compared with 5% Platinum (5% Pt-Norit) and 4% Silver (4% Ag-Norit) catalysts. The Tafel slopes of all three catalysts are equal, the activity of Ag-Norit being somewhat lower then both Caffeine-Norit and Pt-Norit. The polarization curves are also comparable, especially in the low current density region. The increase of overpotential for the Caffeine-Norit at current density higher than 50 mA cm ⁻² is due to accumulation of H ₂ O ₂ in the catalyst layer. This was demonstrated by a simple method for detection of peroxides in neutral electrolytes based on indigo carmine indicator. The discharge curves of Caffeine-Norit in 4 M NaCl electrolyte at 10 mA cm ⁻² display a plateau at potential of −320 mV vs Ag/AgCl (1.23 V vs MA8M magnesium alloy).

The Magnesium-Air battery is a very attractive energy source due to its high specific energy, low cost and the possibility of rapid mechanical recharge. The use of citric acid as an additive to the electrolyte (sea water) prevents the precipitation of Mg(OH)2 and enhances the behaviour of the magnesium electrode. Due to the better access of electrolyte to the electrode surface, ohmic and polarization resistances are reduced, and the rate of electrochemical reaction is increased. The equilibrium potential is displaced towards lower values for both pure magnesium and magnesium alloy AZ63.Citric acid favours also the performance of the GDE by removing the Mg(OH)2 precipice. A functioning battery is tested under polar conditions at the Bulgarian Antarctic station at Livingstone island.

Thermally treated caffeine doped active carbon (Caffeine-Norit) is studied as a catalyst for the oxygen reduction reaction (ORR) with application in metal-air systems and neutral aqueous electrolytes. Catalytic activity is characterized by polarization curves and Tafel plots and the results are compared with 5% Platinum (5% Pt-Norit) and 4% Silver (4% Ag-Norit) catalysts. The Tafel slopes of all three catalysts are the same, the activity of Ag-Norit being somewhat smaller then both Caffeine-Norit and Pt-Norit. The polarization curves are also comparable, especially in the low current density region. The increase of overpotential for the Caffeine-Norit at current density higher than 50 mA cm-2 is due to accumulation of H2O2 in the catalyst layer. This was demonstrated by using a simple method for detection of peroxides in neutral electrolytes based on indigo carmine indicator.