Whichever company is helping VW run its plant will likely play a key role. That’s because building batteries for cars requires exquisite control of materials and manufacturing. Many smartphones use one battery cell, so if minor differences between two cells result in slightly different capacities, it just means somebody gets a few more minutes of Twitter time than somebody else. But even minor differences in the capacity or quality of the 500 or so cells that make up a pack can undermine the performance or safety of the entire vehicle. (Tesla uses smaller cells than most; its batteries contain 5,000 or more cells.) “Cells have to be identical from a quality perspective,” says Jay Whitacre, who runs the Scott Institute for Energy Innovation at Carnegie Mellon University. “Only the very best producers can make lithium-ion batteries for automotive use.”
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