From sodium-sulphur to zinc-air to redox flow batteries, many electrochemical systems are available or are being developed as alternatives to lithium-ion batteries. Scientists at the Technical University of Vienna are now enriching this diversity with a further variant. Jürgen Fleig’s team developed an oxygen-ion battery in which oxygen instead of lithium forms the basis for a new type of electricity storage. Initial tests show great potential for a long-lasting battery that can be regenerated at the same time.
For their oxygen-ion battery, the researchers used heat-resistant, ceramic electrodes made, for example, from metal oxides of lanthanum, strontium and iron. Doubly negatively charged oxygen ions migrate between these electrodes. When discharging, this oxygen is stored in a ceramic electrode and gives off two electrons per atom for a usable current flow. A first prototype showed a volumetric energy density of around 140 watt hours per liter, which is still around a third of the lithium-ion batteries available today.
Benefits of oxygen in battery chemistry
The advantages of this power storage system include very low loss of storage capacity and a potentially extremely long service life. It can also be regenerated by adding oxygen. If oxygen is lost through side reactions, the loss can simply be compensated for with oxygen from the ambient air. In contrast to lithium-ion batteries, there is no risk of fire with ceramic electrodes. Critical materials such as cobalt or nickel, which are only available in limited quantities, can also be dispensed with. The researchers even hope to be able to replace the lanthanum that is currently still used with optimized ceramics.
Due to the lower energy density, however, oxygen-ion batteries would simply be too large for mobile applications in smartphones or electric vehicles. The high operating temperature between 200 and 400 degrees Celsius also limits ease of use. Nevertheless, Jürgen Fleig and colleagues can imagine an application for stationary storage in the future, for example to absorb excess electricity from wind or solar parks.
(jl)