edit I am an idiot, who uploaded the image link as the URL. The original source should now be accessible
RMIT engineers say they’ve tripled the energy density of cheap, rechargeable, recyclable proton flow batteries, which can now challenge commercially available lithium-ion batteries for capacity with a specific energy density of 245 Wh/kg.
The advantages are, every part of the device can be easily recycled, and the parts to make the charge-holding portion of the battery are less damaging to acquire than in li-ion