Solid-state batteries promise to improve range, charging and safety aspects of electric vehicles compared to liquid-type batteries in use today, which is why most major automakers are working on the technology, both independently and in partnerships.

The latest to announce its involvement in the space is Hyundai Motor Group which last week said it is working with Factorial Energy to test the Woburn, Massachusetts-based company's solid-state battery and its integration in Hyundai EVs. The two will also develop specifications for manufacturing Factorial’s battery with a view for automotive applications.

Hyundai Motor Group, which covers the Genesis, Hyundai and Kia brands, will also make an investment in Factorial as part of the agreement.

Factorial has been developing solid-state battery technology for the past six years and includes former Chairman and CEO of Panasonic Corporation of North America Joe Taylor as executive chairman. Panasonic is a major battery supplier, and includes Tesla and Toyota among its customers.

Former Mercedes-Benz CEO Dieter Zetsche and former Ford CEO Mark Fields are also on Factorial's advisory board.

Factorial claims to have developed a solid-state battery that enables safe and reliable performance in high-capacity, high-voltage applications. The company claims the battery could deliver 20-50% more range than current liquid-type batteries, and could be used by current EVs.

Solid-state batteries aren't a new technology but hurdles remain when it comes to automotive applications, the key ones being manufacturing the batteries at the scale and durability required for cars.

Hyundai Motor Group hasn't said when it expects to start selling EVs with solid-state batteries, though other automakers such as BMW, Honda, Stellantis, Toyota and Volkswagen Group predict the technology will be ready for prime time in the second half of the decade.