This is the second time in recent months that an Apple executive has left for an automaker. Apple lost its automotive project manager, Doug Field, to Ford Motor in September.

Ahn this month became chief technology officer for the battery division of Volkswagen Group Components, according to his Linkedin profile.

In 2018, Apple hired Ahn, a former executive in Samsung SDI’s next-generation battery division. Apple uses batteries not only in its cell phones and laptops, but also in its developing electric vehicles.

Industry sources told Reuters last year that Apple aims to launch an electric car with advanced battery technology by 2024.

Apple declined to comment while Ahn and Volkswagen did not immediately comment.

When asked if Apple plans to develop batteries and displays in-house like it does with chips, Apple CEO Tim Cook said in October: “I wouldn’t want to rule anything out.”

“It’s more about whether or not we see our way to do something significantly better,” he said on a conference call.

Apple Inc’s talks with Chinese companies CATL and BYD over battery supply for its planned electric vehicle have mostly been stalled after suppliers refused to build US factories solely for the tech giant three people familiar with the talks told Reuters in September.

Volkswagen laid out an ambitious plan to build six battery factories across Europe with partners by the end of the decade, key to its vision to overtake Tesla Inc as the world leader in electric vehicles.