LG Chem halted production in September after saying a chemical used to make batteries may not have been registered with the U.S. Environmental Protection Agency.
The EPA said it didn't order the shutdown but had issued a subpoena on LG Chem, seeking to learn what chemicals are used at the factory. Production had begun in July in Holland in western Michigan.
LG Chem said the first shipments from the factory are expected in November.
The company drew attention during its 2010 groundbreaking when President Barack Obama traveled to Michigan for the event.