There are issues with the solid-state battery buses Daimler delivered to the city of Wiesbaden in February. The 21 Mercedes-Benz eCitaros have been out of service for a good two weeks as their batteries are undergoing checks due to an insulation fault that could lead to short circuits.

They are the only manufacturer of solid-state batteries for electric vehicles on an industrial scale – and yet they are hardly in the spotlight: French Bolloré subsidiary Blue Solutions developed and commercialised batteries with solid-state electrolyte years ago. Their most prominent customer is Daimler.