What is the difference
between ESMA's asymmetric supercapacitor technology and conventional
supercapacitor technology?
Conventional supercapacitor design
technology uses two identical polarizable electrodes (carbon electrodes), which
potentials change depending on their charge. This design is referred to as a
symmetric capacitor. Devices of this design (with aqueous electrolyte) first
appeared in the late 1970s. Second generation symmetric devices appeared in the
1980s, which used a non-aqueous electrolyte to increase the cell operating
voltage.
ESMA capacitors use a third generation
supercapacitor design. They have one polarizable (carbon) electrode and one
non-polarizable electrode (made of nickel oxyhydroxide) (see Design). This design is referred to as
asymmetric technology. In summary, first generation supercapacitors use a symmetric
design with an aqueous electrolyte, second generation supercapacitors use a
symmetric design with an organic electrolyte, and third generation
supercapacitors, like ESMA products, use an asymmetric design with KOH aqueous
solution electrolyte.
What happens during overvoltage of ESMA capacitors?
ESMA capacitors do not fail during
overvoltage conditions. When the applied voltage exceeds the maximum specified
value for a long time, the capacitor cell begins to generate gas. The gas is
released through a resealable safety valve located at the top of each cell when
a designated pressure is reached. Water, which is the major part of the
electrolyte in an ESMA capacitor, is consumed during gassing, therefore,
additional distilled water may be needed to top up the electrolyte if
overvoltage conditions persist for long periods of time. Nevertheless,
overvoltage conditions do not harm an ESMA capacitor. This is unique among all
supercapacitor products.
What is the service life and cycle life of ESMA
supercapacitor modules?
Cycle tests of ESMA capacitor modules using
a hybrid vehicle power profile have been preformed uninterruptedly for over two
years. At the beginning of 2002, more than 500,000 charge/discharge cycles had
been completed with no noticeable decrease in performance. This testing
continues.
Delco Remy (North American manufacturer of
starters and alternators for heavy-duty trucks) tested ESMA capacitors for
their engine starting performance. They successfully completed 157,000
consecutive starts of a heavy-duty truck engine. At the December 2000 SAE
conference, Delco Remy and Freightliner (major North American manufacturer of
heavy-duty trucks) presented a joint paper containing ESMA capacitor test
results. This paper "Paper 2000-01-3495: Electrochemical Capacitors for
Truck Applications" can be obtained from www.sae.org.
ESMA capacitors have been installed in
several types of trucks for more than four years in Russia and over two years
in the US (with major truck fleets) and used to insure successful engine
starting under all weather conditions.
Does ESMA sell individual electrochemical capacitor cells?
ESMA's main commercial products are
capacitor modules.
ESMA can supply individual capacitor cells for testing. In such cases the
customer is responsible for mechanical fixturing to provide compression on the
cells, and voltage equalization of the cells before series connection.
What is the risk of voltage unbalance of ESMA cells within
the modules?
Risk of unbalance is significantly lower
than when using electrochemical capacitors of other manufacturers. It relates
to the fact that there is an effect of voltage self-balancing happening due to
harsh increase of leakage currents in capacitor cells with increase of their
voltage.
Which modules are suitable for engine starting of
different vehicle types?
10EC104 S, 10EC501 S and 10EC402 S modules are sized for most truck starting
applications. 20EC402
S and 20EC501 S
modules, which contain more energy and deliver higher power, are suitable for
the starting of heavy-duty equipment engines. 20EC402 S modules are generally used
in portable engine starting devices.
Are ESMA capacitors safe and environmentally friendly?
ESMA products are safe and contain no toxic
substances. Their flame and explosion safety is due to the fact that no
explosive or flammable materials are used in their construction. Each cell has
a special resealable safety valve to release gas that may be generated should
an overvoltage be applied. Capacitor cells contain nickel, which can be
recycled with Ni-MH batteries.
Is it possible to build high-voltage systems using ESMA
electrochemical capacitor modules?
Yes, high-voltage systems can be assembled
connecting the modules in series. Several such strings may then be parallel
connected to meet the energy requirements of an application. For example, the RTS100 system operates at
400 V.
What is ESMA's attitude towards collaborative activities?
How can I become an ESMA distributor?
ESMA is most interested in developing the
market for its electrochemical capacitors. Please be assured we will review
your proposal and reply with our comments.
ESMA would like to increase its
distribution network and welcomes new distributors all around the world. If
your company is interested in becoming a distributor of ESMA products, then
please contact us specifying your desired distribution region, your company
profile, and the market segment you would like to serve.
Can ESMA design and produce special capacitor products?
ESMA will develop and manufacture
non-standard capacitor products to meet technical performance requirements of a
customer to the maximum extent. This type of activity is usually performed
under a development contract.
Can an ESMA electrochemical capacitor module operate in
any orientation?
Standard ESMA modules must be oriented with
their terminal connections at the top. This insures proper operation of the
safety gas-release valve. However, ESMA can provide special supercapacitor
products for applications that require operation in any orientation.
Reports of ESMA are presented to the various international
conferences and seminars
Application of
ultracapacitors as traction energy sources
New ultracapacitors
developed by JSC ESMA for various applications
Power characteristics of
'ESMA' capacitors
Electric drive bus and
electric drive truck, with electrochemical capacitors as the only on-board
power source
Electrochemical capacitors
for hybrid electric vehicles
Electrochemical capacitor
Module for hybrid transport application
Internal losses and features
of asymmetric capacitor operation
Operation of nickel
hydroxide/carbon capacitor at temperature of approx 65°C
All reports are given in PDF
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