Limitation in energy density of batteries means in practice reduced driving range for electric cars, which is the largest obstacle to these vehicles entering the market. But, new technology using the reaction of metal and air could have a major impact on battery life. The EU-funded project NECOBAUT (New concept of metal-air battery for automotive application based on advanced nanomaterials) was launched with the aim to incorporate nanomaterials into batteries.
Researchers sought to exploit the reaction of iron and air through a technique that could theoretically enable batteries to store eight times more energy than conventional batteries.
Batteries convert stored chemical energy into electrical energy by means of chemical reactions. Each cell of a battery – electric vehicles typically have hundreds of cells – consists of a positive electrode, an ion conductor that can be liquid or solid, and a negative electrode. The team used metal-based nanomaterials to increase the surface of electrodes available to chemical reactions.
For the anode side, they investigated various iron carbide nanostructured materials supported on high-surface carbon. Additives were included to minimise hydrogen evolution and enhance charging efficiency.
Several catalysts were also tested for the cathode (air side), including innovative perovskite materials, developed by project partners. These were evaluated on commercial and project carbon supports.
Based on the test results, researchers manufactured iron and air electrodes and subsequently assembled a metal-air battery cell in which the electrolyte is circulated to dissipate heat and remove gases. A separator prevents internal short circuits and improves safety. Extensive testing demonstrated its potential to meet energy density goals.
Optimisation of all materials and components under different operating conditions facilitated the design of a final prototype. The low-cost and durable NECOBAUT alternative to lithium-ion batteries promises to take electric cars farther before recharging. This new technology enabling the storage capacity of batteries to reach their theoretical limit could be used on the road soon.