The South Korean companies are two of the world's biggest producers of the lithium-ion batteries that power humanity's growing pile of phones, laptops, and electric cars. Audi previously used battery cells from Sanyo and Panasonic to power its "e-tron" plug-in hybrid electric cars.

"This will allow us to supply a technological solution that makes electric cars even more attractive for our customers," says Dr. Bernd Martens, a member of the board of management of Audi's procurement division.

The three companies have revealed little beyond the existence of the partnership, and it's unclear exactly how it will work with even basic questions like whether both companies provide batteries, or if one will be ousted down the line, unanswered. All Audi had to say is it's planning to build a whole lot more EVs, so it's time to forge strong relationships with battery suppliers.

The luxury automaker, owned by Volkswagen, plans to expand its lineup from 52 to "about 60″ models in the next five years, including several new EVs. "We as a high-tech brand will raise electric mobility to a new level," Audi boss Rupert Stadler said in May.

One new model will be the yet-to-be-named 300-mile SUV, which Audi teased in April when it revealed renderings of a concept called the Prologue Allroad concept.

Don't get too excited about that range, though. First of all, it's a goal, not a guarantee. And in American terms, the range will be closer to 260 or 270 miles. That's because the New European Driving Cycle, the test used to rate fuel economy across the pond, is a bit generous (and has been criticized as such). The Tesla Model S 85D, for example, has an EPA-rated range of 270 miles. In Europe, it's rated for 328 miles, an 11 percent improvement for the exact same car.