Apple has lost its Global Battery Chief, Soonho Ahn, to German automaker Volkswagen, as first reported by Manager Magazin (via Tesla North).

Back in early 2019, it was reported Ahn was scooped up by Apple, poaching the battery executive from Samsung. Ahn became Apple’s new Global Head of Battery Developments.

Volkswagen plans to build six battery plants to supply the company’s electric vehicle ambitions, and Ahn appears to be a central part of the initiative, as he has relocated to Wolfsburg, Lower Saxony, Germany, according to his updated LinkedIn profile. Previously he was working at Apple’s headquarters in Cupertino, California.

Ahn earned his Ph.D. in Chemical Engineering from Auburn University in Alabama, which is also Apple CEO Tim Cook’s alma mater. Prior to working at Samsung, he was a longtime executive at LG Chem, as the South Korean company’s VP of Energy Solutions.

The loss of Ahn could be seen as a blow to Apple’s “Project Titan” self-driving electric vehicle project. Batteries are the integral heart of an electric car and Ahn’s departure also joins the recent loss of “Project Titan” chief Doug Ford, who departed for Ford back in September.

Apple’s car project is now being led by executive Kevin Lynch, who previously headed up Apple Watch software. A recent Bloomberg report said Apple was fast-tracking its car project, with an internal timeline now noting four years, which could mean a car debuting as soon as 2025 (no word if the Apple car will charge with Lightning or USB-C, however).