Advanced Calcium-Thionyl Chloride High-Power Battery
Final rept. 15 May 1989-15 May 1990
RAMAT-TEL-AVIV UNIV AUTHORITY FOR RESEARCH AND INDUSTRIAL DEVELOPMENT LTD (ISRAEL)
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In this phase we have demonstrated that CaSrX2 7 or 20 SO2-TC cells A7 and A20 types can deliver at RT up to 5.5Ah at low rates and 4.4Ah at 0.9 A. These cells have 10 to 80 more capacity than have commercial Li-TC and Li-SO2 wound c-size cells. The improved A7 and A20 types cells lost almost no capacity after 4-5 weeks of storage at 70 deg C. The A20 type cell generates less heat at 20 deg C under OCV conditions than equivalent LiTC cells, having the same electrode area, i.e. it has a longer shelf life. The addition of P40 additive to SrX2 TC SO2 solutions decrease further the corrosion rate of calcium. The lowest corrosion rate found for solutions containing 20 SO2 0.3 P40. Formolation of the SrX2-TC electrolyte with 20 SO2 and 0.3 P40 A20S type cell found to have the following advantages it increases shelf life, it increases load voltage and Faradaic efficiency. A preliminary specification of A20S type Ca-TC cell is enclosed. The improved shelf-life of calcium in BaX2TC solutions as compared to CaX2TC solutions results mainly for the difference in the solubility or reactivity of the CaO film in those two solutions. In CaX2TC solutions the oxide dissolves leaving the calcium with a CaCl2 layer which does not provide the metal with good protection. In BaX2TC solutions, on the native CaO layer a BaCl2AlCl3 or Al2O3 layer is formed. This BaCl3AlCl3Al2O3 layer does not form when the oxide is missing from the surface. Therefore cleaned calcium in BaX2TC solution corrodes at the same rate as does calcium in CaX2TC solutions.
- Electrochemical Energy Storage