One place to start might be the companies mentioned on the Lithium Ion Battery page on Wikipedia. A lot of the same major players show up again and again in these sorts of factory deals and discussions, such as: LG Chem (mentioned here; also a major partner with some of the German automakers on the European continent), Panasonic (partner in Tesla's Gigafactory), Sony (a traditional player in battery chem and essentially the originator of commercialized Lithium Ion tech in the first place), Toshiba (another traditional player).