A steadily increasing demand of high-energy density batteries for mobile devices, electronic vehicles, the storage of renewable energy, as well as the shortage of lithium resources, spur the research on suitable elements as active species in battery-systems. Multivalent-ions, such as Mg2+, Ca2+ and Al3+ have become popular candidates as they can transfer more electrons per atom. In fact Al3+-conducting batteries can reach higher energy densities and specific capacities than conventional lithium-ion batteries.
Besides high energy densities, a long cycle lifetime is a main aspect for future energy storage materials. One way to satisfy both demands and simultaneously ensure a highest level of safety is to focus on thin film batteries (TFBs). Next to utilizing a non-flammable solid electrolyte, TFBs do not suffer from possible passivation of the electrodes surface during cycling what in turn expands their lifetime. However, only a few reports on rechargeable aluminum batteries have been published.