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Electric Vehicles Research
Posted on March 28, 2011 by  & 

PARC Improves Traction Batteries

Palo Alto Research Center PARC, developed laser printing, object-oriented programming, and personal workstations with graphical user interfaces. Now it is building a cleantech portfolio. PARC was founded in 1970 at Xerox; in 2002, it was incorporated as a wholly owned independent research and development subsidiary of Xerox Corporation, providing services to external customers as well as to Xerox.
 
Dr. Scott Elrod, VP and Director of PARC's Hardware Systems Laboratory (HSL) research organization also directs the Cleantech Innovation Program at PARC, which develops solutions for delivering affordable solar energy, increasing solar cell efficiency, purifying water, managing energy utilization, and producing renewable fuels. One of the projects Elrod and PARC were discussing at last week's ARPA-E Energy Innovation Summit in Washington DC was a technology for the co-extrusion printing of novel battery electrodes, enabling higher energy and/or power densities.
 
Hybrid vehicles currently optimise power density and pure electric vehicles optimise energy density but the technologies are converging in hybrids with large, energy dense batteries for pure electric long range and range extenders such as mini turbines for charging them onboard. See Electric Vehicle Traction Batteries 2011-2021 and attend Electric Vehicles - Land Sea Air Europe 2011.
 
 
PARC has developed a technology for co-extrusion printing—i.e., for depositing thick films of pastes of densely interdigitated functional materials. For batteries, these functional material pastes would be the electrode active materials. A post deposition processing step dries and sinters the deposit into the final electrode structure. The stripes can be as narrow as several microns wide and as tall as several hundred microns.
 
The first application of this technique has been for silver gridlines on the front surface of solar cells. Compared to screen-printed gridlines, the narrower and taller front gridlines created by the technique cover less solar cell surface area, resulting in increased absolute cell efficiency. A production prototype machine is under test at a customer site, with an additional gain of 1% absolute cell efficiency and process speeds up to 200 mm/sec having been demonstrated.
 
While the solar cell application has a near-term sales opportunity, commercial application of the technology to battery electrodes is probably 2-3 years out, Elrod noted. There is further opportunity for the method in air cathodes. The current density in an air-breathing electrode is proportional to the amount of electro-catalytic surface area that is exposed to air. The PARC technology provides a directed-assembly printing method for producing a greater proportion of this "three-phase boundary" than conventional electrode manufacturing methods—up to 10x the air-breathing surface area of conventional electrodes.
 

Authored By:

Chairman

Posted on: March 28, 2011

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