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Funded project ZIB2


Aqueous zinc-ion batteries 2

Zinc-ion batteries have long been the focus of attention for these and other applications – but so far without commercial success. The BMBF-funded research project “Aqueous zinc-ion batteries ZIB2” is now investigating how industrial implementation can succeed. The central development goals are the use of non-critical, cost-effective materials, an increase in efficiency and an extension of the service life as well as the application of industrial cell designs.

Aqueous zinc-ion batteries (ZIB) are often referred to as green energy storage technology, as their cell chemistry is based on sufficiently available zinc. The batteries are considered to be reliable, environmentally friendly, economical and there is no risk of explosion or fire as water is an essential component of the cell. Although ZIB systems have already reached a high level of technological maturity, the technology has not yet been able to establish itself across a wide range of applications compared to the lithium-ion battery (LIB). However, as demand for sustainable storage technologies continues to grow, alternative systems such as ZIB are increasingly coming into focus. The market-ready development of zinc-ion technology is being further accelerated by the constantly rising demand for energy storage systems, the increasing scarcity of raw materials in established systems and the desire for greater environmental friendliness and sustainability. ZIB is therefore developing into a genuine alternative to the dominant LIB technology, particularly in the field of stationary storage systems.

State of the art and technical challenges of zinc-ion batteries
Modern zinc-ion concepts consist, on the one hand, of a positive electrode with a variety of possible materials such as manganese oxides, vanadium oxides or Prussian blue analogs (PBA) such as copper ferricyanide and, on the other hand, a negative electrode made of metallic zinc. In addition, water is used as the electrolyte, which increases the intrinsic safety of the ZIB system immensely.

Cost efficiency, cost-effectiveness, safety and sustainability are the driving forces behind the choice of a suitable battery storage system for stationary applications, such as storing surplus solar or wind energy. In contrast to established technologies such as LIB, aqueous zinc-ion systems fully meet the above-mentioned critical market requirements. Thanks to their high environmental friendliness, the aqueous, non-toxic electrolytes and materials used, the high specific power, which is essential for power grid applications, and the low cost due to the good availability of zinc, ZIBs represent an attractive approach to solving the current and future energy storage problem.

The PBA cathode materials addressed in ZIB2 are characterized by their low energy losses and their ability to charge and discharge quickly. This makes them particularly relevant for applications in the stationary energy storage sector, where it is necessary to react quickly to possible load peaks in the power grid in order to avoid widespread power outages. Another advantage of PBA cathode materials is their simple, scalable and cost-effective synthesis. In the course of rapid commercialization, large quantities of electrodes can be produced and processed into numerous cells. A major disadvantage of PBA systems to date has been their short service life of only 300 cycles (charging and discharging process). However, project partners in the ZIB2 consortium have already been able to increase the service life of PBA-based ZIBs to 800 cycles by cleverly modifying the respective PBA structure. Further strategies are being pursued in the current project in order to increase the performance of the PBA technology and thus enable rapid use of the developed cells in real application scenarios.

Improved cycle life and efficiency through new materials and cell concepts

In order to further increase the service life and efficiency of zinc-ion batteries, the project partners are synthesizing, characterizing and optimizing new materials for both the anode and the cathode. New electrolyte compositions are also being produced and studied in detail. In addition, the aging mechanisms occurring at the electrodes, which can impair the long service life of the battery cells, are to be identified and analyzed. In this way, indications can be found for further optimization of the interaction between the electrodes and the electrolyte. After identifying promising materials and material combinations, various industry-oriented cell designs will be developed, produced and tested in order to determine the optimum design for a final, production-ready product. Different manufacturing processes will also be considered, including the printing of ZIBs, for example. Finally, the project participants will subject all source materials, cell components and manufacturing processes to a detailed economic and ecological assessment in order to fully determine the market potential of this new battery technology and to be able to demonstrate the economic efficiency and environmental friendliness of the ZIB system.

Background information

The ZIB2 project is coordinated by Varta Microbattery GmbH, which aims to scale up the cell design and drive forward the industry-oriented demonstrator. The electrochemistry of the active materials is being analyzed and investigated at the University of Bremen. GRILLO-Werke AG is contributing its expertise in zinc materials and their use as anodes. Fraunhofer IFAM produces the Prussian blue analog cathode materials on a large scale and develops the electrode formulations and coatings. The adaptation of the Zn-based electrolytes is being developed by E-Lyte Innovations GmbH. Battronics GmbH addresses aging models, cost considerations and value creation.