BMW have started road testing solid-state battery technology in an i7 saloon.

The technology is believed to have the potential to hugely increase range, without a weight penalty.

Solid-state batteries achieve a higher energy density by using solid components instead of the liquids and polymer gels used in today’s batteries.

BMW have been working with battery developer Solid Power since 2016, and this test marks the first time a Solid Power solid-state battery has been tested on the road.

Martin Schuster, vice president of the battery and cell module at the BMW Group, said: “Our BMW i7 ASSB test vehicle on the road is a perfect example of the BMW Group’s technology-open mindset.

“We are continuously advancing the development of new battery cell technologies and are constantly expanding our know-how with valuable partners such as Solid Power. ”

Solid Power and the BMW Group intend to share the development and production process, with a solid-state cell prototype production line planned to open in the group’s Cell Manufacturing Competence Centre (CMCC), using Solid Power expertise.

Mercedes-Benz began testing similar technology in their rival car, the EQS, earlier this year, where range was increased by 25%, to 620 miles.

Toyota and Stellantis are also developing solid-state battery technology.

The i7 is BMW’s flagship electric saloon, currently offering a range of up to 387 miles.