Canada’s Lithium Americas said General Motors will boost investment in the miner’s Thacker Pass project, which produces the critical ingredient for electric-vehicle batteries.

General Motors Inc will commit $625 million toward what’s likely to be one of the biggest US lithium mines, reinforcing the automaker’s efforts to secure domestic supply of the battery metal critical for electric vehicles.

Previously, GM invested $320 million into Lithium Americas in exchange for 15 million shares back in February of last year. In total, GM has now invested $750 million into Lithium Americas and the joint venture, not including the $195 million line of credit.