Aluminum-air: status of technology and applications [secondary cells]

Over the years, the use of aluminum as an anode has attracted many potential applications due to its very high theoretical ampere-hour capacity, voltage and specific energy. In reality, although these values are reduced due to system inefficiencies, this electrochemistry still yields energy densities that exceed many other couples. Since the early 1980s, aluminum-air technology has rapidly advanced to a safe, reliable system that possesses practical energy densities of 300-500 Wh/kg and specific power to 22.6 W/kg. These advances include development of a very pure, alloyed aluminum anode, and the lowest cost air-cathode available today. Presently, this technology is used in a wide variety of applications. One significant application is the reserve power unit. AT&T, Bell Canada, cellular phone and cable network operators in the UK and France Telecoms, are using this system to increase the reserve back-up power available from lead-acid battery to over 60 hours. For underwater vehicles or UUV Applications, the US and Canadian Navy have on-going UUV programs which could extend the vehicle range from 180 miles with silver-zinc batteries to over 540 miles with an aluminum-oxygen system. Other applications include a small, highly energized man-pack portable aluminum-air battery for the Special Operation Forces. The air electrode is also utilized in production of low-cost highly efficient ultracapacitors as well as in certain electrosynthesis operations. This paper summarizes the present state of the technology and the current applications of the aluminum-air technology.