Northvolt transformed in a matter of months from Europe's best shot at a homegrown electric-vehicle battery champion to a struggling company.

Swedish battery maker Northvolt filed for Chapter 11 bankruptcy protection in the U.S., delivering a blow to Europe's electrification ambitions.

Northvolt's financial collapse deals a blow to Europe's plan to set up its own battery industry to power electric cars, stirring a debate about whether it needs to do more to attract investment as startups struggle to catch up with Chinese rivals.