Spray-coated few-layer graphene as an aluminium battery cathode

We report herein wet-jet milling produced graphene (GWJM) as a high performing aluminium battery (AB) cathode material. The electrodes of GWJM were fabricated in an ecofriendly and highly scalable manner by a spray-coating approach using inexpensive solvents (ethanol–water) and sodium carboxymethyl cellulose binder. GWJM as a cathode of AB delivered a reversible capacity of 57 mA h g⁻¹ at a current density of 1 A g⁻¹ during the first cycle that increased to 72 mA h g⁻¹ after 10 000 cycles under continuous operation. This capacity corresponds to a volumetric capacity of 245 mA h L⁻¹ and an energy density of 105 W h kg⁻¹. The combined structural and theoretical analysis reveals that such an increase in the capacity is accomplished by the stage-4 insertion of AlCl₄⁻ anions into GWJM. The electrodes exhibited a very good rate performance of 72, 35, 22, 74, and 135 mA h g⁻¹ while discharging at current densities of 1, 2, 3, 1, and 0.1 A g⁻¹, respectively, even after 10 000 cycles. The capacity was further increased to 90−175 mA h g⁻¹ when the ambient temperature was raised to 70 °C. The spray-coated graphene electrodes could be easily adapted for industrial applications owing to their simple and highly scalable fabrication, superior cycling stability as well as high rate capability.