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A clad metal breakthrough is helping jumpstart widespread adoption of this fuel-saving technology.

Faced with rising fuel economy and emissions standards around the globe, auto makers are turning to new approaches to improve their fuel efficiency. At the top of the list is the innovative “start-stop” technology. 

This technology uses a dedicated battery that is charged when the vehicle decelerates, storing energy which then restarts the engine from an idle position such as at a stop light or in traffic congestion. The start-stop battery runs the electrical systems while the engine is temporarily turned off. According to the American Automobile Association, startstop systems can improve fuel economy by as much as 12% while also reducing emissions.

Auto makers are pushing hard to advance the technology and make it standard equipment. The research firm Trefis estimates that worldwide production of start-stop vehicles will triple to 35 million in 2015. A key to making this happen is replacing the lead-acid batteries currently being used with smaller, lighter and more energy-dense lithium-ion battery packs. 

That is where Materion comes in. “Lithium-ion battery chemistries force cell designers to use copper anode terminals and aluminum cathode terminals,” explains Joe Kaiser, Vice President, Product and Market Development at Materion Technical Materials. “One battery pack may have hundreds of cells that must be connected to one another via a busbar between anode and cathode terminals.” The standard assembly process is tedious, relying on nuts and bolts to attach busbars between cells.

As auto makers scale to high-volume production, pack assemblers want to replace this costly process with highly efficient laser welders. This presents pack designers with a serious challenge: laser welding copper to aluminum creates unreliable metallurgical joints. To solve the problem, Materion Technical Materials has created an innovative Dovetail Clad® material which joins copper and aluminum in a side-by-side bonded strip. This copper-aluminum composite facilitates repeatable high-volume laser welding of copper to copper and aluminum to aluminum in large pack assemblies. Not only does Materion Technical Materials Dovetail Clad metal solve a huge technical hurdle, it also helps reduce the overall weight of the battery pack by replacing much of the copper with lower-density aluminum.

“We believe this is a huge opportunity for Materion,” says Kaiser. “We are already spec’d into a number of future model year vehicles, and are talking with most major OEMs around the globe.”