Advances in aluminum-air battery technology might allow electrically powered vehicles to become more realistic and competitive automotive options for many drivers.
At present, most electric vehicles (EVs) are powered by lithium-ion battery packs and have a driving range of about 100 miles (160 km). After that, drivers have to plug into a 240-volt charger for six to eight hours for a full charge, find a quick-charge station and plug into a 480-volt charger for 20 to 30 minutes for 80% of a full charge, or call a tow truck. See also: Electric vehicle
In addition to being slow to charge, the lithium-ion battery packs that power EVs are heavy and expensive, and typically will need to be replaced at least once during the vehicles’ lifetime. In 2013, an aluminum-air battery was demonstrated that could extend the driving range of an electric vehicle up to 1000 mi (1600 km). See also: Battery
The aluminum-air battery consists of an aluminum anode in an electrolyte solution of potassium hydroxide and uses oxygen from air as the cathode. A selectively permeable membrane allows oxygen from the air to enter the cell but excludes gases such as carbon dioxide that would interfere with the battery’s function. When the battery is in use, the oxidation reaction of aluminum plus oxygen plus water produces aluminum hydroxide plus electrical energy (electrons). See also: Aluminum; Electricity; Electrolyte; Oxidation-reduction; Oxide
Because aluminum is a lightweight metal and the cathode material, oxygen, does not have to be stored in the battery, an aluminum-air battery is considerably lighter than a comparable lithium-ion battery. It is estimated that 55 lb (25 kg) of aluminum will provide a driving range of about 1000 mi (1600 km) and the entire battery will weigh about 200 lb (90 kg). By comparison, the Nissan Leaf’s 600-lb (270-kg) lithium-ion battery pack provides a driving range of about 100 mi (160 km).
A major disadvantage of the aluminum-air battery is that it is not rechargeable. Once the aluminum is consumed, the battery must be replaced, which means that some sort of battery-swapping station or service would need to be readily available to drivers. However, the by-product of the battery’s reaction, aluminum hydroxide, is recyclable. See also: Aluminum (metallurgy); Wide-scale infrastructure for electric cars
In March 2013, Phinergy, a developer of aluminum-air battery technology, test-drove a Citroën C1 (city car or mini) that was powered by a small lithium-ion battery and fitted with a 50-plate (55-lb) aluminum-air battery that charged the lithium-ion battery. The vehicle functioned like a hybrid by using the aluminum-air battery to extend its driving range. According to reports, Phinergy expects this technology to be used in a commercial vehicle by 2017. Tesla Motors also has a number of recent patents and patent applications describing the use of an aluminum-air battery to extend the driving range of an electric vehicle by providing backup power to a non-metal-air battery that powers the vehicle. See also: Energy storage; Hybrid automotive power systems
