Lithium-sulfur battery company Sion Power recently reported to the US Securities and Exchange Commission (SEC) that it raised $50 million in equity sold to undisclosed investors.
| Lithium-Sulfur Batteries |
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| Lithium-Sulfur batteries (LSBs) use a lithium metal anode and a soluble polysulfide cathode. Lithium ions are stripped from the anode during discharge and form lithium polysulfides in the cathode. Li2S in the cathode is the result of complete discharge. |
| On recharge, the lithium ions are plated back onto the anode as the lithium polysulfides in the cathode move towards S8. High order Li-polysulfides (Li2S3 to Li2S8) are soluble in the electrolyte and migrate to the anode, scrubbing off any dendrite growth. |
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| Lithium-sulfur battery. Click to enlarge. |
| The theoretical specific energy of a lithium-sulfur battery chemistry is in excess of 2,500 Wh/kg with a theoretical energy density of 2,600 Wh/L. |
| LSBs have a number of issues, including cycle life and operation at higher temperatures. Among the limiting mechanisms, according to Sion, are the rough lithium surface on the anode during cycling and Li/electrolyte depletion. |
In 2010, Sion, a Brookhaven National Laboratories spin-off, received a three-year research grant worth up to $5 million from the United States Department of Energy Advanced Research Projects Agency - Energy (ARPA-E) (earlier post) for the development of practical, economical and safe lithium-sulfur (Li-S) batteries for powering electric vehicles. Sion’s award was one of 10 made to advanced battery projects by ARPA-E during this second round of project funding.
Performance targets for this program are to exceed 500 Wh/kg and 500 cycles at commercially viable recharge rates. By 2016, the goal is to produce a cell with 600 Wh/kg and 1,000 cycles. Sion Power believes that by utilizing Li-S technology, a battery pack weighing less than 700 lbs (318 kg) can power a 3,500 lb (1,588 kg) five-passenger vehicle more than 300 miles (483 km).
In 2009, Sion Power Corporation and BASF SE signed a Joint Development Agreement (JDA) to accelerate the commercialization of Sion Power’s proprietary lithium-sulfur (Li-S) battery technology for the electric vehicle (EV) market and other high-energy applications. (Earlier post.)
Privately held Sion Power Corporation was established initially as Moltech Corporation in 1994, and holds more than 100 US and international patents on its technology.
Source: Green Car Congress
