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.

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.

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.