Mercedes-Benz has started producing 108-kilowatt-hour battery packs for its EQS flagship sedan, which the automaker plans to unveil April 15.

The packs are being made at the Stuttgart-Hedelfingen plant, part of Mercedes' Untertürkheim complex in Germany, the automaker said Tuesday in a press release.

"The EQS will be equipped with battery layouts enabling different range and performance variants," Mercedes said, while confirming for the first time that the top offering will be a 108-kwh battery pack. That lines up with range estimates that have been pegged at more than 700 kilometers (just under 435 miles) on the European WLTP testing cycle since this model's concept introduction.

The EQS pack will have "CO2-neutrally produced cells," according to Mercedes, with chemistry including nickel, cobalt, and manganese in a ratio of 8:1:1. That reduces cobalt content by around 10% compared to previous cell chemistries, Mercedes said.

As it ramps up production of electric cars, Mercedes said it plans to be involved in all aspects of the battery business, from basic research, to production, to so-called "second-life" uses after batteries have outlived their usefulness in cars.

Teaser for 2022 Mercedes-Benz EQS debuting on April 15, 2021

Teaser for 2022 Mercedes-Benz EQS debuting on April 15, 2021

To that end, Mercedes plans to open a new factory for small-series production of future lithium-ion cells in 2023. The automaker believes this well help build institutional knowledge of battery research, production, and second-life uses or recycling.

This follows the battery strategy that Mercedes outlined to Green Car Reports in 2019—shopping around for the cells, but maintaining expertise over development and manufacturing.

Last year Mercedes fine-tuned that plan somewhat, with a $1.1 billion expansion to establish a "global network of nine battery factories around the world, managed by its subsidiary Deutsche Accumotive.

The company has previously underscored that it won't be part of the "range race," and will instead seek reliability, quality and longevity for its packs. It revealed in 2020 that it is sourcing the cells for the EQS from China's CATL.

Mercedes is planning to bring at least four electric models to the United States over the next two years—starting with the EQS. It's scheduled to go on sale here this fall, followed by the EQE sedan, which is expected to start deliveries in 2022. Mercedes will also build SUV variants of the EQS and EQE in Alabama, starting later in 2022.