Research of Air Cathodes for Aluminum Air Batteries

Abstract

Abstract : The dismounted marine currently uses portable power systems mainly for radio communications, however the future will require a wide range of portable power systems for an electronics rich environment. The marine is already burdened with traditional equipment and the addition of new equipment will likely add to this load. This places a premium on reducing the weight of the power sources to maintain the mobility and effectiveness during combat. This need for lightweight power sources is the catalyst for developing higher energy density (Wh/kg) power sources. Current power source requirements are met with the LiSO2 (EA-5590) primary batteries and any possible substitute power sources shall be compared to this baseline. A power source that offers promise in this application is the Aluminum-air system (for the chemistry see the Appendix). This system actually has a higher energy density than the LiSO2 system and could be significantly higher, if a larger portion of its theoretical energy density could be realized. The system displays a significant difference between the practical and theoretical energy densities. Part of the inefficiency is due to the difference in the theoretical Al-air voltage (2.7V) and the practical operating Al-air voltage (1.35V). The goal of this program was to improve the practical energy density of the Al-air system, The focus of this Phase I program was to identify and evaluate alternative cathode materials to reduce this difference between the practical and theoretical energy density of the aluminum anode. Several new air cathodes were developed using different catalysts and carbons. These new cathodes were characterized and then discharged in actual aluminum air cells. One new air cathode formulation performed better than our existing cathode. The new Vulcan cathode performed better than the existing Mn cathode at the current densities of 5 and 10 mA/sq cm with an improvement as high as 21%.