The research
team and its new battery (from left to right): Prof. Dr. Ulrich S. Schubert,
Tobias Janoschka
und Dr. Martin Hager. Foto: Anne Günther/FSU
(October 21, 2015) Chemists of Jena University present an
innovative redox-flow battery based on organic polymers and water
Sun and wind are important sources of renewable energy, but
they suffer from natural fluctuations: In stormy weather or bright sunshine
electricity produced exceeds demand, whereas clouds or a lull in the wind
inevitably cause a power shortage. For continuity in electricity supply and
stable power grids, energy storage devices will become essential. So-called
redox-flow batteries are the most promising technology to solve this problem.
However, they still have one crucial disadvantage: They require expensive
materials and aggressive acids.
A team of researchers at the Friedrich Schiller University
Jena (FSU Jena), in the Center for Energy and Environmental Chemistry (CEEC
Jena) and the JenaBatteries GmbH (a spin-off of the University Jena), made a
decisive step towards a redox-flow battery which is simple to handle, safe and
economical at the same time: They developed a system on the basis of organic
polymers and a harmless saline solution. "What's new and innovative about
our battery is that it can be produced at much less cost, while nearly reaching
the capacity of traditional metal and acid containing systems," Dr. Martin
Hager says. The scientists present their battery technology in the current
edition of the renowned scientific journal 'Nature' (DOI:10.1038/nature15746).
In contrast to conventional batteries, the electrodes of a
redox-flow battery are not made of solid materials (e.g., metals or metal
salts) but they come in a dissolved form: The electrolyte solutions are stored
in two tanks, which form the positive and negative terminal of the battery.
With the help of pumps the polymer solutions are transferred to an
electrochemical cell, in which the polymers are electrochemically reduced or
oxidized, thereby charging or discharging the battery. To prevent the
electrolytes from intermixing, the cell is divided into two compartments by a
membrane. "In these systems the amount of energy stored as well as the
power rating can be individually adjusted. Moreover, hardly any self-discharge
occurs," Martin Hager explains.