For any proper evaluation of next generation energy storage systems technological, economic, and environmental performance metrics should be considered. Here conceptual cells and systems are designed for different aluminium battery (AlB) concepts, including both active and passive materials. Despite the fact that all AlBs use high-capacity metal anodes and materials with low cost and environmental impact, their energy densities differ vastly and only a few concepts become competitive taking all aspects into account. Notably, AlBs with high-performance inorganic cathodes have the potential to exhibit superior technological and environmental performance, should they be more reversible and energy efficient, while at the system level costs become comparable or slightly higher than for both AlBs with organic cathodes and lithium-ion batteries (LIBs). Overall, with continued development, AlBs should be able to complement LIBs, especially in light of their significantly lower demand for scarce materials. 

Abstract Aluminum 3D thin film anodes fully integrated with a separator are fabricated by sputtering and enable rechargeable aluminum metal batteries with high power performance. The 3D thin film anodes have an approximately four to eight times larger active surface area than a metal foil, which significantly both reduces the electrochemical overpotential, and improves materials utilization. In full cells with organic cathodes, that is, aluminum metal?organic batteries, the 3D thin film anodes provide 165 mAh g?1 at 0.5 C rate, with a capacity retention of 81% at 20 C, and 86% after 500 cycles. Post-mortem analysis reveals structural degradation to limit the long-term stability at high rates. As the multivalent charge carrier active here is AlCl2+, the realistic maximal specific energy, and power densities at cell level are ≈100 Wh kg?1 and ≈3100 W kg?1, respectively, which is significantly higher than the state-of-the-art for Al batteries.

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.

Rechargeable battery technologies based on the use of metal anodes coupled to multivalent charge carrier ions (such as Mg2+, Ca2+ or Al3+) have the potential to deliver breakthroughs in energy density radically leap-frogging the current state-of-the-art Li-ion battery technology. However, both the use of metal anodes and the migration of multivalent ions, within the electrolyte and the electrodes, are technological bottlenecks which make these technologies, all at different degrees of maturity, not yet ready for practical applications. Moreover, the know-how gained during the many years of development of the Li-ion battery is not always transferable. This perspective paper reviews the current status of these multivalent battery technologies, describing issues and discussing possible routes to overcome them. Finally, a brief section about future perspectives is given.