Bill Gates has become the latest investor to invest in Aquion Energy, a US start-up that is pioneering a new type of battery that uses sodium-ion technology.
The Pittsburgh, Pennsylvania, company yesterday announced it is working on raising a US$35m Series D financing round, with a first close on that round from new investors Microsoft chairman Bill Gates and Gentry Venture Partners.
Bright Capital is leading the round, which also involves returning investors Kleiner Perkins and Advanced Technology Ventures.
Last year, Aquion closed a US$15m loan facility, while it also raised US$20m in funding in 2011.
The company, which was founded in 2008, develops and manufactures Aqueous Hybrid Ion (AHI) batteries and energy storage systems.
It claims its batteries are comprised of non-toxic materials to create an environmentally friendly energy storage technology.
Aquion’s AHI battery uses saltwater as an electrolyte, an anode made of activated carbon, a cathode made from manganese oxide and synthetic cotton for the separator. The battery has been developed for both small and large-scale stationary energy storage applications, including off-grid and micro-grid systems, commercial and industrial energy storage and grid-scale applications.
Aquion is planning to start shipping production units from its manufacturing plant in Pennsylvania at the end of this year.
The company’s proprietary aqueous hybrid ion chemistry is based on the research of Jay Whitacre, a professor at Carnegie Mellon University who received R&D funding from the university in 2007 to research low-cost electrochemical approaches to bulk energy storage.
Aquion is not the first battery start-up that Gates has invested in. He has also invested in Ambri and LightSail Energy. In a 2010 article, Gates called for a "battery miracle" to solve the problem of storing intermittent sources of energy, such as solar and wind.