Liquid Metal Battery Corp., an MIT spin-out working on grid scale energy storage, has raised a $15 million Series B led by Khosla Ventures, according to a report by GigaOM’s Katie Fehrenbacher. The company had previously raised seed funding from Bill Gates and oil driller Total Energy. (Gates is also an LP in Khosla Ventures.)

The money will go towards advancing the technology developed at MIT by Professor Donald Sadoway, who is taking a year sabbatical to act as Scientific Adviser for the company. In November of last year the company scored a big win by bringing on Phil Giudice, former commissioner of the Massachusetts Department of Energy Resources, as CEO.

But with the technology still pre-commercial, LMBC has a long road ahead of it. As Fehrenbacher describes the company’s tech:

Liquid Metal Battery is developing a battery for the power grid using molten salt sandwiched between two layers of liquid metal. The battery is still at least two years from commercialization, and the team has built a 16-inch prototype, though they might later scale that up to 36 inches. The company is betting that a battery based on liquid metal electrodes will be stable, scalable, and low cost enough that it could revolutionize grid storage.

In addition to seed funding from Gates and Total, LMBC received a grant from the Department of Energy’s ARPA-E program, as well as support from the Deshpande Center and the Chesonis Family Foundation.

While the Series B underscores the technology’s potential, it also points to the challenges of commercialization in the energy space including, at least in sub-sectors like storage, hefty capital requirements. It will be years before we know if LMBC’s technology can get to the necessary price point. But with this round, and with Giudice on board, the company certainly has momentum.

Image via LMBC