COPENHAGEN :Northvolt's CEO and co-founder Peter Carlsson is stepping down, the Swedish maker of battery cells for electric vehicles said on Friday, one day after the group filed for U.S. Chapter 11 bankruptcy protection. Northvolt went in a matter of months this year from being Europe's best shot at a home-grown electric-vehicle battery champion to racing to stay afloat, hobbled by production problems and dwindling funding. It now needs to raise between $1 billion and $1.2 billion in order to