Volkswagen is increasing its stake in solid-state battery firm QuantumScape. The German automaker said in a press release Tuesday that it will invest an additional $200 million in the U.S.-based battery company.

VW has been collaborating with QuantumScape since 2012, and claims to be the company's largest automotive investor, with a previous investment of $100 million. In 2018, the two companies formed a joint venture to spur production of solid-state batteries for VW, beginning with a pilot factory.

That will be a step toward VW's plan for automotive use of solid-state batteries in some way around 2025. The automaker wants its batteries to last the life of the car, so any development in the solid-state realm will have to measure up to that.

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As the name suggests, solid-state batteries use a solid electrolyte, as opposed to the liquid electrolyte used in lithium-ion battery chemistry. Proponents claim better performance characteristics than current batteries.

Solid-state technology has the potential to shake up the battery and EV field. A 2019 partnership between Toyota and Panasonic, for instance, includes the technology—at least from a development standpoint. In 2017, BMW partnered with SolidPower on the technology. Like VW, BMW anticipates that solid-state batteries could make it into production cars by 2025.

The VW Group is allowing for solid-state batteries to be a possible (albeit low-volume at first) offering for a model built on its PPE electric platform, which will underpin a range of premium models through the end of the decade.

The automaker plans to produce millions of electric cars over the next few years, mostly based on the mass-market MEB platform using conventional lithium-ion batteries.