Got it - the actual paper cites it as 285 mAh g^-1 ie 285 mAh/g, so it does indeed look like ~410Wh/kg. The nature article has a nice chart that doesn't need a

Got it - the actual paper cites it as 285 mAh g^-1 ie 285 mAh/g, so it does indeed look like ~410Wh/kg. The nature article has a nice chart that doesn't need access: http://www.nature.com/article-assets/npg/nenergy/2016/nenergy201639/images_hires/w450/nenergy201639-f3.jpg http://www.nature.com/article-assets/npg/nenergy/2016/nenerg... Looks like at 5C discharge rate they can maintain 92% of their capacity ~375 Wh/kg even after 5000 cycles - this is the most promising stuff I've seen since Li-S (lithium sulphur), which have a higher specific energy, but lower cycle life and much lower discharge rating.