Metal-air batteries

Functioning of a lithium-oxygen cell.
© Fraunhofer IFAM

Functioning of a lithium-oxygen cell.

Glass test cells for metal/oxygen systems.
© Fraunhofer IFAM

Glass test cells for metal/oxygen systems.

Metal-air batteries are already commercially available as primary batteries. They are distinguishable from conventional lithium-ion technology by their high theoretical energy densities (>1000 Wh/kg). However, recharge ability represents a significant challenge and is currently being researched. For us the focus is on the development of gas diffusion electrodes (GDE) using new substrate materials (C, Ti) and catalysts as well as novel designs. The understanding of the interactions between the electrolyte and the GDE remains a further important focus of our work.

In addition to zinc-air batteries (theoretically ~1100 Wh/kg), we are working intensively with the high energy system of lithium-air (theoretically ~3500 Wh/kg). The greatest challenge hereby is to avoid of the undesirable side reactions. These currently lead to significantly low (factor 10) practical energy densities as well as extremely low cycle stabilities. The optimal wetting of the GDE, the change in the pore microstructure due to the deposition of solid discharge products, and the stability of the lithium-metal anode against the electrolyte are important influencing factors, in addition to the stability of the electrolyte itself.

We develop new material and electrode designs and maintain a special metal-air test unit in order to conduct tests under a variety of conditions. Also, in situ analytics can be used in this context when necessary. In addition, we work with the conceptual design of metal-air cell stacks.