An aluminium battery operating with an aqueous electrolyte

Aluminium is an attractive active material for battery systems due to its abundance, low cost, a gravimetric energy density of 2.98 Ah g-1 (c.f. lithium 3.86 Ah g-1) and a volumetric energy density of 8.04 Ah cm-3 (c.f. lithium 2.06 Ah cm-3). An aqueous electrolyte-based aluminium-ion cell is described using TiO2 nanopowder as the negative electrode, CuHCF (copper-hexacyanoferrate) as the positive electrode and an electrolyte consisting of 1 mol dm-3 AlCl3 and 1 mol dm-3 KCl. Voltammetric and galvanostatic analysis have shown that the discharge voltage is circa 1.5 V. Both a single cell and 2-cell battery are demonstrated using 10 cm2 electrodes and 126 mg and 256 mg total active material for the 1-cell and 2-cell batteries respectively. The single cell exhibits an energy density of circa 15 mW h g-1 (combined positive and negative electrode masses) at a power density of 300 mW g-1 with energy efficiency remaining above 70 % for over 1750 cycles. Initial characterisation shows charge storage is due to the presence of Al3+. Cell capacity is circa 10 mA h g-1 and operates with a discharge voltage of circa 1.5 V (efficiency >80 % at 20C charge/discharge rate).