Redox Flow Development at VoltStorage

How VoltStorage sets new standards in the development of the Redox Flow technology.

Munich, February 4th, 2020 – Since 2018, VoltStorage offers the world’s first cost efficient residential storage system based on the ecological Redox Flow technology. Thanks to patent pending production automation and technological developments, VoltStorage succeeded in making a storage technology available to the mass market, that was successfully deployed in large storage systems, for the first time.

To continuously further develop the VoltStorage residential storage solutions and to set new standards, VoltStorage has an own research and development department at its disposal. This department is comprised by international Flow Battery experts from Germany, Brazil, England and the US. One major goal of the R&D activity at VoltStorage is the further development of the Redox Flow battery cells and the materials and components required for that.

Material science as a major focus activity of Redox Flow development

The focus of the material and component research is on the three central elements of Redox Flow battery cells: (1) the graphite felt, that is required for the equal distribution of electric charge in the half cells, (2) the bipolar plate that acts as electrode material and thus ensures the electrical conductivity between the cells and (3) the ion exchange membrane, that enables the electricity storage/discharge through the counter ion exchange between the two half cells.

For testing various materials, so called small cells are deployed, that have the same fundamental construction of a full-scale Redox Flow battery cell. The VoltStorage research team relies on self-developed small cells, that exhibit a larger active area and thus return more valid results than available laboratory cells. “With our continuous material tests, we pursue the goal to identify new components that exhibit a higher conductivity and therefore increase the efficiency of the overall system” explains the VoltStorage CTO and Co-Founder Michael Peither, who already worked on the first Redox Flow cells back in 2016.

Zusammenbau einer Redox-Flow Kleinzelle
Zwei Forscher arbeiten an einer Redox-Flow Kleinzelle
Zwei Forscher werden einen Redox-Flow Kleinzellen-Test aus

More than 300 material tests conducted in 2019

In the last year alone, the research and development team at VoltStorage has tested and analyzed more than 120 different materials and components in an excess of 300 small cells. For example, various activation methods and graphite-felt sized were tested to enhance the conductivity of the battery cells and therefore the overall system. “Due to the sheer amount of different materials and suppliers, the possibilities are enormous. To date we concentrated exclusively on the major manufacturers and suppliers. In the coming months however, we will lay our eyes on those suppliers, that do not have a large market share yet. With that we want to exploit new efficiency and savings potentials”, explains Redox Flow expert Dr. Antonio dos Santos.

Cooperation with major cell material suppliers

Most of the materials and components commercially available on the market are not optimized for the use in Redox Flow battery cells, but rather different applications – such as the development of fuel cells. That is why research and development cooperation with leading material manufacturers are necessary to set new technological standards in the Redox Flow area. ”Regarding all three core components (felts, membranes and bipolar plates) we are in direct conversations with developers of their respective manufacturers. Thereby we iteratively develop new materials that are optimized for the use in our storage systems”, explains VoltStorage CTO Michael Peither.

Redox Flow cell structure

A redox flow battery cell has two half cells that consist of a frame with liquid channels. In the center of these frames is a large-area graphite felt. The two half cells are separated by an ion exchange membrane. Each battery cell is enclosed by two bipolar plates.

Redox-Flow Batteriezelle von VoltStorage

Bipolar plate

The bipolar plate is used as the electrode of a Redox Flow battery cell. It is thus responsible for the electrical conductivity, which is increased on the material side by using particularly conductive and corrosion-resistant materials, such as graphite.

Ion exchange membrane

The transparent and thin layered ion exchange membrane separates the positve and negative charged half cell and ensures the separation of the two differently charged electrolyte circuits. It only allows an ion exchange between the half-cells, which is necessary for power storage or discharge.

Graphite felt

Via the liquid channels in the cell frame, the positve or negative charged electrolyte, which serves as a storage medium, is directed into the respective half cell.

There the electrolyte is taken up by the large-area graphite felt and distributed evenly in the two half-cells. This results in a charge exchange between the differently charged half-cells via the ion exchange membrane.

Concluding prototype tests

Materials and components that exhibited positive results during small cell tests, are tested in prototype systems in the next step. These are systems that are identical to (full-scale) series products except the material or component in question. These storage systems are therefore operated in the VoltStorage laboratories under real operation conditions and analyzed thoroughly. Only if these test procedures present positive results, the respective materials are in line for the series production. “On the basis of our numerous tests in the past twelve months, we identified and developed new materials especially in the areas of graphite felts and ion exchange membranes, of which we already have transferred a few into the series production or about to do so in the near future” reports VoltStorage CTO Michael Peither regarding the achievements of the VoltStorage material research department.

More about VoltStorage

VoltStorage develops and produces solar energy storage systems based on the ecological Redox Flow technology. With its sustainable storage solutions, VoltStorage follows the vision of making 100% renewable energies available around 24/7 – and thus making the world cleaner and fairer.

VoltStorage is the first company worldwide to make the Redox Flow Technology, which has been successful in the large storage segment for years, available as a home storage solution for private households. This was made possible by VoltStorage’s production process, for which a patent is pending. For the first time this allows automated and thus cost-effective production of Redox Flow batteries.

With the Redox Flow technology, the company can establish a storage technology in the mass market that is free from rare materials and conflicting raw materials, is completely recyclable and also has a high level of operational reliability and longevity.

Any questions?

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