Saturday, December 3, 2011

vanadium redox flow battery history

The vanadium redox flow battery
By Dr. Adam H. Whitehead
History and comparison with other battery types
Already in the 19th Century was known batteries in which the
electrolyte flowed by gravity to prevent the formation of gas bubbles
at the electrodes. Similarly, we already knew redox fuel - a fuel cell
that contained a redox battery element. Modern redox flow batteries
were invented in 1949 by Prof. Walter Kangro and patented [1]. The
development of useful systems, however, took place until 1970, when
NASA began to explore these energy stores.
After examining many different systems developed by NASA functioning
iron-chromium redox flow batteries. These were fairly complex and
suffered from a steady and irreversible loss of capacity, since iron
and chromium diffused through the membrane. In 1986, the Scylla of
Prof. Maria-Kazacos at the University of New South Wales, Australia,
developed for solving the problem of membrane junction has been
patented [2]. She sat in two vanadium electrolyte. Vanadium diffused
equally true, but the steady loss of capacity was now completely
reversible by simply recharging.
Sumitomo Electric Industries Ltd.. [3] adapted the vanadium redox flow
battery of Prof. Scylla-Kazacos, to produce the first generation of
large batteries. Sumitomo vanadium redox batteries were installed
exclusively in Japan. VRB Power Inc. [4] used Sumitomo reactors for
its large battery installations in South Africa, Australia and the
United States.
Christian Pichler
Figure 2 The youngest vanadium redox flow battery FB10/100 - 10 kW,
100 kWh of energy at a voltage of 36 V to 58 V. It fits with tanks and
all units in a 4.1 m × 2.2 m × 2.4 m large box with full tanks and
weighs 10.2 tons
Currently, a handful of companies is active in the development of
redox flow systems. Despite the significant advantages of the vanadium
redox battery technology in certain applications, the university's
research activities were surprisingly limited. A new generation of
small, commercial-vanadium redox flow batteries became independent of
the company Cell Power Ltd. [5] (Fig. 2) and VRB Power Inc. develops.
Both companies have patents that are of importance for their
respective technology. The Scylla-Kazacos original patent has now
Comparison with other battery types
In conventional rechargeable batteries - for example Lead-acid,
nickel-metal hydride, nickel-cadmium and lithium-ion battery -
changing the electrode chemically loaded or unloaded while. This
causes the solid electrodes, a change in volume. After a few cycles by
the beginning of a mechanical breakdown. Through the use of dissolved
electroactive material as it comes in the vanadium redox battery is
used, this decay is avoided completely.
Lead-acid batteries fail by the formation of thick, insulating lead
sulfate crystals (sulfation), if they are held for long periods in the
partially discharged state, as in photovoltaic applications typically
often the case. Especially in winter the sun is often no longer enough
to fully charge the batteries and to dissolve the lead sulfate
crystals. The vanadium redox battery is also not affected by this
failure mechanism, there are no sulfate crystals. In addition,
vanadium-redox batteries are also insensitive to stratification of the
electrolyte (acid density fluctuations along the cell) or grid
corrosion (dissolution of the current collector), which also
contribute to shortening the lifetime of lead acid batteries.
Included with all rechargeable batteries, water, creates a potentially
explosive hydrogen loading. The crowd, which arises in vanadium redox
battery is extremely low and can be directly over the tanks is
collected and discharged. Some other batteries, specially produce wet
cell lead-based, as much hydrogen gas that the operation is permitted
only in rooms with appropriate ventilation and anti-static floor [6,
Compared with high-performance batteries, e.g. the Li-ion batteries,
vanadium redox battery pretty sure. Thus cause a short circuit or
reverse polarity of the cells no harm. And since all cells are
traversed by the same electrolyte, you do not need individual cell
monitoring and control. All cells have the same capacity, not an
equalizing charge is required.
The vanadium redox battery is more complex than other batteries and
inevitably more expensive than lead-acid batteries with a set of
comparable energy. Nevertheless, it is expected, the vanadium redox
battery, since you can expect a very long cycle life. For lead-acid
energy storage systems are from time to time all the battery-swap
rates, whereas in the vanadium redox battery only relatively small
items such as Pumps must be renewed and thus a long service life is
achieved with good efficiency.

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