Aqueous Copper-Aluminium (Cu || Al) Primary Battery for Energy Storage

A novel aqueous primary battery consisting of a copper or copper alloy cathode, an aluminium or aluminium alloy anode, an aqueous copper sulfate catholyte, and an aqueous aluminium sulfate anolyte [Al/Al ³⁺ ,SO ₄ ^2- // Cu ^2+, SO ₄ ^2- /Cu] is reported in this work. The battery comprises a ceramic or wood or any other inert separator that allows the transport of ions. If the catholyte and anolyte are supplemented with aqueous potassium nitrate as a supporting electrolyte, cupric ion (Cu ²⁺ ) crossover to the anode compartment can be prevented effectively. The battery delivers specific discharge capacity exceeding 2500 mAh per gm of anode material with stable electrochemical behavior. The battery showed an open circuit voltage greater than 0.6 volts (0.61 to 0.7 volts). The battery operates with a redox reaction between copper and aluminium, which can be represented as 3 Cu ²⁺ (aq.) + 2 Al (s) = 3 Cu (s) + 2 Al ³⁺ (aq.). The battery excels in self-discharging property; it does not lead to hydrogen evolution at the anode, it does not cause consumption of aqueous solvent during discharge, nor does it lead to parasitic corrosion of the anode. It possesses an energy density exceeding 600 W-hr per kg anode, and it indicates an anodic efficiency greater than 86% with the capability of delivering an electric current density exceeding 5 mA per gm of anode material, approximately.