Bill Gates is putting more of his money behind a developer of battery technology, whose technology is based on research out of MIT. Liquid Metal Battery said Thursday that it has raised $15M in a Series B round, which was led by Khosla Ventures, and also included Gates, who was a Series A funding backer. Energy company Total also participated in the round. Liquid Medal Battery is developing new battery technology aimed at grid-scale, electricity storage. The firm's technology was spun out of the lab of Dr. Donald Sadoway, a professor at the Massachusetts Institute of Technology.