The storage of electricity produced by intermittent renewable sources is the bottleneck of the transition towards a fully green energy landscape. Besides technical suitability, the stationary storage with battery technologies applied to buffer the temporal mismatch between electricity production and demand have to comply with very tight economic constraints to be competitive with fossil fuel combustion technologies.
In order to address sensitive aspects concerning the secured supply of critical raw materials, we aim at demonstrating that a rechargeable alkaline zinc-air battery, made of :
Abundant
Environmentally friendly
Intrinisically safe and robust materials
Entirely recyclable
can be more advantageous that state-of-the-art Li-ion batteries for stationary electricity storage.
The main challenges to overcome are avoiding the formation of Zn dendrites which promote detrimental short circuits, increasing the efficiency of the oxygen evolution reaction (OER) and avoiding the formation of solid carbonate deposit in the positive electrode.
“Because air is everywhere. Because zinc is abundant.”
Sunergy participates actively to the development of rechargeable zinc-air batteries through several research projects.
2012-2015: AZTEQUE project with EDF
We have started to work on this project in partnership with EDF, providing a highly capacitive and cyclable zinc electrode in a 3 electrode setup.
By studying various thicknesses of electrodes (3.4-5.4 mm) we have obtained 400-630 mAh/cm².
In order to protect the air cathode, we have added a third electrode only used on charge, discharge is done as a fuel cell. This way, the energy density is correlated to the Zn anode.
Promising results were obtained with 1400 cycles considering a 50% state of charge of the limiting Zinc electrode.
This project, based on our innovative Zinc electrodes, led to the creation of Zinium by EDF.
2022-2025: ZABSES project with French and German partners
We have partnered with important actors from both sides of the Rhine to setup the basis for an innovative European-based zinc-air technology. Namely the research institutions ZSW, and DLR on the German side, and the LPPI (CY Cergy Paris University) and Sunergy in France will improve the different battery components. The German battery manufacturer Varta Microbattery will provide its industrial expertise for battery development.
This project focuses on using a bifunctional air electrode in order to have two electrodes cells. This can greatly improve the specific energy and facilitate the electrical output.