Renewable energy might soon have storage batteries that are more environmentally friendly in their own right. Researchers have developed a new form of aluminum battery with twice the energy density of previous designs, making the technology more practical for large-scale projects like solar and wind farms while using more sustainable materials. The trick was to replace the usual graphite cathode (the positive electrode) with anthraquinone, an organic carbon-based molecule that ups the density by storing positive charge carriers coming from the electrolyte.
Aluminum batteries still aren't available outside of labs, and you shouldn't expect this breakthrough to be available any time soon. They're still half as energy-dense as lithium-ion cells, and the scientists are busy working on more effective electrolytes and charging systems. If aluminum does reach parity with lithium, however, it could lead to a sea change where renewable energy and electric cars run on more readily available and recyclable materials.