Concept and electrochemical mechanism of an Al metal anode ‒ organic cathode battery

Aluminum (Al) batteries are fundamentally a promising future post-Li battery technology. The recently demonstrated concept of an Al-graphite battery represents some significant progress for the technology, but the cell energy density is still very modest and limited by the quantity of the AlCl3 based electrolyte, as it relies on AlCl4‒ intercalation. For further progress, cathode materials capable of an electrochemical reaction with Al positively charged species are needed. Here such a concept of an Al metal anode ‒ organic cathode battery based on anthraquinone (AQ) electrochemistry with a discharge voltage of 1.1 V is demonstrated. Further improvement of both the cell capacity retention and rate capability is achieved by nano-structured and polymerized cathodes. The intricate electrochemical mechanism is proven to be that the anthraquinone groups undergo reduction of their carbonyl bonds during discharge and become coordinated by AlCl2+ species. Altogether the Al metal anode – AQ cathode cell has almost the double energy density of the state-of-the-art Al-graphite battery.