Improvements of The Iron Electrode of Iron-Air Battery for Grid Scale Energy Storage Systems

摘要

The iron-air rechargeable battery is a very promising candidate for large-scale energy storage because of the environmentally friendliness and low cost of raw materials. However, there are two major technical challenges associated with the iron electrode that prevent it from large-scale utilization: low charging efficiency and low utilization of active material. The reversible potential of the iron electrode is more negative than the reversible potential of the hydrogen evolution reaction. Consequently, the conversion of iron hydroxide to iron during charging is accompanied by hydrogen evolution reaction, which results in a charging efficiency of the iron electrode as low as 50%. In addition, the formation of non-conductive iron (Ⅱ) hydroxide during discharging prevents complete utilization of active material of iron electrode and also results in a poor high rate capability of discharge. In this poster we report on the performance of carbonyl iron based electrodes with bismuth sulfide additives. The purity and morphology of iron play a critical role in determining the charging efficiency. Carbonyl iron is particularly suitable for iron electrode manufacturing because of its high purity and small particle size. The charging efficiency can be further improved to 96% by bismuth additives that selectively inhibit the hydrogen evolution reaction. It has been reported in the literature that sulfide additives can prevent iron electrode from complete passivation. We report remarkable improvements to the utilization of the iron electrode during high rates of discharge in the presence of sulfide additives.