Lithium-sulfur batteries are an alternative to lithium-ion batteries with three times the storage. Early prototypes were pretty dodgy, but more research is now going on supported by Department of Energy grant money.
From the link:
Earlier this year we reported on several advances geared toward addressing these problems, and noted that these advances had caught the eye of the chemical giant BASF, which is now working to bring lithium-sulfur batteries to market. But challenges remain, including bringing down costs. Now the Department of Energy has also taken an interest in the technology. This week Sion Power Cooperation (which is working with BASF) announced that it has received a three-year, $800,000 DOE grant to further develop the lithium-sulfur batteries for electric vehicles.