The world is now betting on lithium-ion-powered electric vehicles as a way to meet climate goals. 2020, the year of the outbreak, saw nearly 1.4 million battery-electric and plug-in hybrid vehicles (collectively known as XEVs) registered in Europe, an increase of 137 percent over 2019. Electric XEVs have three times lower emissions than conventional vehicles and vary in their manufacturing and charging processes, depending on the power source. Despite the proven advantages of XEVs, using batteries to power cars around the world requires attention: batteries are guaranteed to last between five and eight years; recycling is notoriously difficult (currently less than 5 percent); batteries are polluting; charging XEVs on a large scale can strain the grid, and the rare earth minerals required for XEVs pose a supply chain risk.
A report on the environmental impact of conventional and alternative fuel vehicles published by the European Commission in 2020 concluded that hybrid electric vehicles have a significantly lower environmental impact across all vehicle types. However, given the wide variation in the energy mix across countries, this impact is highly dependent on the regional and operating environment. In addition, the use of copper and electronic components in XEVs continues to put pressure on the environment. In contrast, aluminum-air battery technology promises to address sustainability, recycling, and procurement issues for low-carbon transportation.
Aluminum-air batteries are a cheap, light, and powerful source of energy. The formula is simple: aluminum + air = power.
About 20 years ago, scientists predicted that the combination of aluminum-air batteries and XEVs would be one of the most promising technologies for future passenger vehicles in terms of driving range, purchase price, fuel costs, and life-cycle costs. Aluminum-air batteries are a cheap, light, and powerful source of energy. Trevor Jackson, a former Rolls-Royce engineer, founded Métallectrique, an aluminum-air battery development company that has garnered significant media attention over the past few years. Jackson said the range of aluminum-air batteries is similar to that of gasoline-powered cars, currently estimated at 1,600 kilometers per full charge. The barriers to the commercialization of aluminum-air batteries have long been inherent in the technology itself: poor performance, high cost, and problems due to anode corrosion or pore blockage that make the technology unsuitable for expansion and commercialization.
However, Jackson believes his company has solved these problems with an aluminum-air battery pack that has an energy density of 1.35 kWh/kg, about nine times the energy of lithium-ion batteries. According to Jackson, the best way to describe this technology is as an "electric engine. It is neither a battery nor an engine, but the electronic equivalent of an engine. In this "engine," the "fuel" is aluminum metal (the anode), which reacts with the surrounding oxygen (the cathode) to produce power. Since the cathode is only oxygen from the surrounding air, it does not need to carry the weight of another metal like a conventional battery, which makes it quite light. Currently, the cost per kilowatt hour to the manufacturer is 29 to 35 euros, and the cost per kilometer driven by the driver is 0.15 cents.
For now, charging infrastructure remains one of the main challenges to replacing internal combustion engine vehicles with XEVs, and a 2018 Harvard University study suggests that a more accessible, easy-to-use and relatively inexpensive charging infrastructure is needed to ensure the commercial success of XEVs. While battery replacement can significantly reduce the wait time for XEV drivers, this technology is difficult to implement. On the one hand, batteries are very heavy and must be precisely installed; on the other hand, a battery replacement system requires a network of evenly distributed stations that have access to a reliable power supply. Moreover, one study found that even unregulated charging of a small number of XEVs could place significant stress on the local grid and could lead to overloads.
For aluminum-air batteries, there are few infrastructure requirements. The current system is designed for manual battery swapping and is based on modules weighing less than 5 kg. In the future, by purchasing an aluminum-air battery adapter, customers will also be able to transform the XEV into a lithium-aluminum-air hybrid. This will not only make the used market more attractive, but will also accelerate sales of new electric vehicles. If the aluminum-air battery adapter reduces the number of charge cycles, the technology may not only extend the use of lithium batteries, but also extend their lifespan. Recycling of lithium-ion batteries has not yet been developed for other environmentally friendly XEV technologies, but recycling of aluminum-air batteries may be much easier, and aluminum recycling infrastructure already exists. In addition to using aluminum as a power source for electric vehicles, this technology could be used to recycle scrap metal from discarded aircraft. The use of aluminum air batteries in passenger cars is just the beginning; possible uses for aluminum air batteries include the marine sector, such as container ships and cruise ships, airport ground support equipment, and powering rural microgrids.
According to the International Energy Agency's 2050 Net Zero Emissions Roadmap, half of the CO2 reductions by 2050 will come from technologies that are currently in the prototype or demonstration stage. This means that promising technologies such as aluminum-air batteries will need to be commercialized on a large scale to accelerate the decarbonization process in transportation.
