Just came across this article http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem.1802.html http://www.nature.com/nchem/journal/vaop/ncurrent/full/nche

Just came across this article http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem.1802.html http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem... about an advance in silicon microparticle anodes for lithium ion batteries which claims a capacity of 3000 mA h/g, and retaining similar performance (~2000 mA h/g) over 100 discharge cycles. They don't mention the voltage, so it's a bit hard to compare energy density; at the 3.2 volts common to lithium ion batteries, that's 6400 watt hours per kilogram, but taking a look at some of the charts available (I can't look at the article itself due to the paywall) it looks like it may actually be .5 volts, which means 1000 watt hours per kilogram. Compare to Tesla's batteries, probably the best in the business, which give you ~130 watt hours per kilogram, and this could be a pretty big game changer. Obviously, they will have to improve past 100 discharge cycles, but it looks like substantial gains in battery technology may be coming within the next decade.