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Fraunhofer ISC Showing Li-Ion Polymer Battery with ORMOCER Electrolyte at Hannover Messe
11 April 2008
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| ORMOCER is a family of inorganic-organic hybrid polymers. Click to enlarge. |
Researchers from the Fraunhofer-Institut für Silicatforschung (ISC) will present their most recent work on developing a lithium-ion polymer battery at the upcoming Hannover Messe, 21-25 April. The cells use a polymer electrolyte derived from ORMOCER (ORganically MOdified CERamics) materials—inorganic-organic hybrid polymers also developed at Fraunhofer.
A polymer electrolyte in lithium-ion batteries can offer a number of advantages such as design flexibility and stability under abusive conditions, but it can also be a less efficient conductor of the lithium ions. Fraunhofer has been working with ORMOCER materials over the last 10 years to optimize its properties for use in Li-ion cells (among other applications).
The polymer is a compound with silicon-oxygen chains that forms an inorganic structure to which organic side chains become attached.
We have succeeded in replacing the inflammable organic electrolytes with a non-flammable polymer that retains its shape. This considerably enhances the safety of lithium-ion batteries. What’s more, because it is a solid substance, the electrolyte cannot leak out of the battery.
Normally, the more solid a polymer is, the less conductive it becomes. But we had numerous parameters that we could adjust—for example, we can use coupling elements with two, three or four arms. As a result, we have more possibilities with ORMOCERs than with a single type of plastic.
—Dr. Kai-Christian Möller, head of the ISC Electrochemical Energy Storage and Conversion group
ORMOCERs are inorganic-organic copolymers which are synthesized as a matrix for Li-ion conduction. The properties of the materials are controlled by the choice of base materials, by how the inorganic polycondensation reaction is conducted, and by controlling the thermal and uv-initiated crosslinking reactions. This enables the polymer to be adapted to the needs of battery and ultracapacitor manufacturing.
Dr. Möller, who began leading the new Electrochemical Energy Storage and Conversion group at ISC in April 2007, said that the properties of the current polymer electrolyte are similar in principle to those reported by earlier ISC researchers (Popall et. al.)
Charge/discharge cycles of complete batteries like (Cu/active carbon/ORMOCER/LiCoO2/Al) with an ORMOCER as separator electrolyte were measured. The voltage drop of these batteries is very similar to cells with standard liquid electrolytes and the efficiency is close to 100%. Cycling the batteries with a current density of 0.25 mA cm-2 between the voltage limits of 3.1 and 4.1 V results in a charge/discharge capacity (referring to the cathode mass) of 100 mAh g-1 at the beginning and after a slight decrease in a stabilised capacity of 75 mAh g-1 after 15 cycles. These promising results could be optimised by using highly purified components.
—Popall (2001)
Fraunhofer will continue to work on improving the conductivity of the polymer to optimize power delivery, in conjunction with the exploration of different electrode materials. The ISC group is also researching ultracaps for application in vehicles, but is not combining the ultracapacitors with the Li-ion polymer batteries, according to Dr. Möller.
Resources
M. Popall, R. Buestrich, G. Semrau, G. Eichinger, M. Andrei, W. O. Parker, S. Skaarup and K. West. New polymer lithium secondary batteries based on ORMOCER electrolytes–inorganic–organic polymers. Electrochimica Acta Volume 46, Issues 10-11, 15 March 2001, Pages 1499-1508 DOI: 10.1016/S0013-4686(00)00745-3
M. Popall, M. Andrei, J. Kappel, J. Kron, K. Olma and B. Olsowski. ORMOCERs as inorganic-organic electrolytes for new solid state lithium batteries and supercapacitors. Electrochimica Acta Volume 43, Issues 10-11, 1998, Pages 1155-1161 DOI: 10.1016/S0013-4686(97)10014-7
April 11, 2008 in Batteries | Permalink | Comments (3) | TrackBack (0)
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Comments
I noticed a website on ultracapacitors (www.ultracapacitors.org) that talks about the new and upcoming super battery.
Is that something that can be used with a Li-Ion Polymer Battery? Do the technologies work together?
Thanks
JJ
Posted by: James Jackson | Apr 11, 2008 6:22:22 PM
Yes, of course a supercapacitor pack can work in parallel with any battery, but you have to pay two times. In the above paper the bad new is the 75mAh/gram of LiCoO2. It's 60% the normal value and LiCoO2 is a very expensive component with Cobalt inside. Li+ conductivity is a key point to get uniform discharge and avoid thermal effects. ORMOCER looks like a very interesting research Lab's component.
Posted by: raymond bonnaterre | Apr 12, 2008 1:59:44 AM
Dear Dr. Moller
Questions:
1- Is the ionic conductivity of your finding solid electrolyte, at its best, can match the organic based electrolytes?
2- Does the application of your finding solid electrolyte electrolyre changes the volumetric energy density of Li-ion cell (if so, by what %?)
Posted by: Hossein Maleki | Apr 14, 2008 10:34:47 AM
