Deutsche Version  ACT
Electrical Storage
BMWi
Redox flow batteries 8.10.2015

Teststation for vanadium redox-flow batteries
© Eisenhuth GmbH

Increase efficiency with new materials

Scientists investigate new bipolar plates and sealing materials for components of the redox flow cell. The integration of various functions in one component will reduce costs and improve the reliability of the batteries.

Project status Project completed
Typical system size Energy 0.1 MWh
Typical system size Output 0.01 MW
Columetric energy density 25-30 Wh/l
Efficiency AC/AC 75 %
Cycle durability (80% discharge level) 10,000
Service life of the system 10 years
Typical discharge time several hours
Response time when preparing the energy Milliseconds to seconds
Typical period between storage and withdrawal several hours to several days
Example application areas stationary energy storage stations for single houses or blocks to store wind energy or solar energy
Project duration July 2012 until June 2015

The redox-flow battery is a system of special interest which can reach high cycle numbers. Energy is stored in the form of charged ions in solution, not as solids as in other batteries. Degradation and/or dendrite formation or memory effects in the electrodes can not happen in this battery concept.

  • Concept of a vanadium redox-flow battery © Eisenhuth GmbH / O. Spelters
  • Bipolar plate with integrated frame and gaskets © Eisenhuth GmbH
  • Sample of a laboratory redox-flow battery © Eisenhuth GmbH
  • Teststation for vanadium redox-flow batteries © Eisenhuth GmbH

First redox-flow batteries are on the market, but they are produced from a high number of single components by time consuming manual work. Components with several integrated functionalities are missing. Examples are gaskets, frames for fixing the bipolar plate and fluid distribution structures. All this should be integrated into one single component, leading to less failure sensitive components for redox-flow batteries.

Bipolar plates and sealing materials

uring the run time of this project new bipolar plates and materials for gaskets shall be developed. As materials thermoplastic polymers and elastomers are chosen. Materials with improved electron conductivity for the bipolar plates and integrated gaskets are in the focus of this project. Integration of the gaskets shall be done by Form-In-Place methods or by shape fitted and or force fitted connection. Simultaneously the frame made of isolator polymer should be connected with the bipolar plate resulting in one single component. By this the assembly to cells can be simplified.

This project concerns production of battery components. First redox-flow batteries are commercialized, but they are produced with manual work from many single components. To reduce production costs and to increase reliability tailor-made material combinations will be developed. This will lead to less time during cell production and will increase component reliability. This will lead to more efficient redox-flow batteries.

Competition-ready, improved components

Starting point of the development is the bipolar plate as the main element of a redox-flow battery. This plate should be connected with the isolating frame by polymer processing methods. In adition gaskets should be integrated into this new component. To reach these goals suitabel material combinations have to be identified as well as the processing methods. Evaluation in test cells are necessary. The industrial partner Einenhuth develops molds for samples and roduces samples of the new components. The research partner EFZN assembles test cells and performs electrochemical evaluation. By integration of several functionalities into one component and by development of the production technology for these components the industrial partner Eisenhuth becomes a competitive producer for improved components for redox-flow batteries.

By integration of several functinalities into one single component costs for assembly are saved and reliability of the battery can be improved.

A single component

Material evaluation and evaluation of samples concerning conductivity and processability nearly finished. Running tests in electrolyt for materials for gaskets. Materials for integrated frame identified. First samples of bipolar plates with integrated frame are under development. Tool design for injection molding is finished. Mile stone after one year "Determination of a stable and suitable  material combination for gasket/bipolar plate" should be reached. After two years the milestone "demonstration of suitability of material combination for efficient redox-flow batteries" should be reached. Aim of the project is an improved redox-flow battery by integration of the bipolar plate into the frame with polymer processing methods. Result is one component with several functionalities. By this assembly of the cells can be faster and costs can be reduced.

Sub-projects

In this project the company Eisenhuth cooperates with the Energie-Forschungszentrum Niedersachsen (EFZN)to prepare improved materials and components for redox-flow batteries. The industrial partner delivers materials and component samples. They are analyzed and evaluated by material characterization methods and by electrochemical methods at EFZN. Investigations to rise electron conductivity and quality control for large scale plates as well as tests for gasket stability in electrolyte will be done. The batteries prepared during this project have the typical size of laborators cells with power in the range of several Watts. Their purpose is the evaluation of materials and material combinations and their production methods. The production of commercial redox-flow batteries is not the task of this project. This is the task of assozziated partners like Cellstrom/Gildemeister, who are suppliers of commercial redox-flow-batteries.

Supported by: The Federal Government on the basis of a decision by the German Bundestag

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Research funding

The information system EnArgus provides information on research funding, including on this project (German only).