MIT and A123 Systems Reveal Process to Manufacture Batteries Using Electrophoresis

Massachusetts Institute of Technology (Cambridge, MA) and A123 Systems, Inc. (Watertown, MA) share U.S. Patent 7,662,265 which covers methods for making bipolar electrochemical devices, such as batteries, using electrophoresis. A bipolar device is assembled by applying a field that creates a physical separation between two active electrode materials, without requiring insertion of a discrete separator film or electrolyte layer, according to inventorsYet-Ming Chiang, Benjamin Hellweg, Richard K Holman, Steven M. Tobias, Kim Dong-Wan and  Ryan Craig Wartena.  The process may be used to manufacture rechargeable lithium batteries. 

Potentials (e.g., electrical potentials) and fields (e.g., electrical fields) are used to assemble a variety of electrochemical device architectures, including two-dimensional and three-dimensional constructions for batteries, capacitors, fuel cells, electrochromic displays, and sensors. The disclosed electrophoretic assembly methods do not require insertion of a discrete separator film or electrolyte layer, and are useful for producing devices with reduced manufacturing cost and improved energy density, power density, and cycle life.

FIG. 1 is a schematic illustration of depositing an electrochemically active material using electrophoresis

FIG. 3 is a schematic illustration of a system for spatially concentrating a cathode material in the pore space of a porous foam anode using electrophoresis

FIG. 4A is a schematic illustration of spatially concentrating a cathode material in the pore space of a porous foam anode using electrophoresis according to certain embodiments. FIG. 4B is an expanded view of the foam.

According to the inventors it was surprisingly observed that the bridging phenomenon leading to electrical shorting between deposition electrodes can be avoided when the applied voltage is sufficiently large, greater than about 5 volts and preferably about 10 volts. In this case, even closely spaced electrodes or deposits do not electrically short, and a densely packed electrode system is facilitated. 

Electrical shorting between electrodes is prevented by providing in liquid suspension or solution other constituents that are electronically insulating and deposit more quickly than the electronically conductive active materials. Such constituents include, for example, a polymer or other organic material, components of a dissolved lithium salt, or a reaction product formed at the electrode surface upon the electrodeposition of such a constituent. The reaction product results from a reaction between the deposited constituent and another constituent of the suspension, or between the deposited constituent and the electrode material itself, such as a lithium carbonate forming on the surface of a carbon electrode.  


A123Systems is one of the world's leading suppliers of high-power lithium ion batteries using its patented Nanophosphate™ technology designed to deliver a new combination of power, safety and life.  On January 14th,  A123 Systems (Nasdaq:AONE) announced a battery supply agreement with Fisker Automotive, a new American automaker building premium green vehicles. The supply agreement is for battery systems for the Fisker Karma Plug-in Hybrid Electric Vehicle (PHEV). The Karma is scheduled to be launched in late 2010 and expected to be one of the cleanest, most fuel-efficient cars in the world while still offering industry-leading style and performance. 


A123 Systems announced in December, 2009 that it had entered into a joint venture with SAIC Motor Co. Ltd, a leading automaker in China. The focus of the joint venture is to develop, manufacture and sell complete vehicle traction battery systems for use in hybrid electric and pure electric passenger vehicles and heavy duty truck and bus applications in the People's Republic of China, the largest and fastest growing automotive market in the world.