Swedish battery start-up Northvolt and Siemens’ and AES’s energy storage joint venture Fluence have reached an agreement to co-develop next generation battery technology for grid-scale applications.

As part of the pact, Fluence also plans to purchase battery systems from Northvolt, but the company didn’t provide details on the volume of the supply deal.

The two companies will work together to develop Northvolt battery hardware and battery management systems for Fluence energy storage solutions.