Sion Power: Lithium Sulfur Batteries for Electric Vehicles

Sion Power of Tucson, Arizona just received $50 million in funding for rechargeable lithium sulfur battery technology, according to this SEC filing. (That’s Sion, not Stion, the CIGS thin-film solar manufacturer that received $130 million in funding last week.)

Unlike the recently funded and young battery companies such as:

Aquion (sodium ion)
Liquid Metal Battery (molten antimony and molten magnesium separated by an electrolyte )
Amprius (silicon nanostructure to replace a carbon anode system)
Eos Energy (zinc air)
Pellion (magnesium ion)

— Sion has been working on electrochemical energy storage for almost 20 years — since the firm was spun out of Brookhaven National Laboratories and incorporated as Moltech in 1994.

The source of the funding was undisclosed, but board members include investors from Topspin Partners and Renaissance Technologies. Sion has also received grants from DOE and ARPA-E, and has collaborated on battery materials with BASF. The company has worked with QinetiQ on powering unmanned aerial vehicles.

Sion claims that its lithium-sulfur (Li-S) materials system has the highest theoretical gravimetric and volumetric energy densities of any battery system, as well as superior low-temperature operation — an important consideration in powering an electric car in Alaska. Sion will initially go after automotive applications. Jeff St. John looked at the company’s technology a while ago in this article.

Electric car drive trains such as those in the Tesla or Fisker are currently dominated by lithium-ion technology, although Fisker’s battery supplier, A123, has had some performance issues lately, and the battery in the Chevy Volt has had some fire safety issues. Investor Vinod Khosla has expressed little optimism for lithium-ion technology, as he sees the necessity for thermal controls and management as an unsustainable cost if EV prices are to become truly affordable.

Eric Wesoff,