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• Nhu L. Tran, Aayush R. Singh, and Tanja Cuk
• J. Electrochem. Soc. 2016 volume 163, issue 2, A286-A289. DOI: 10.1149/2.0621602jes. Download

Facile and reversible deposition of metal layers would enhance power and energy densities of hybrid batteries. Here, we investigate Cu²⁺/Cu⁽⁰⁾ deposition on a RuO₂anode and soluble Fe²⁺/Fe³⁺ oxidation on a symmetric RuO₂ cathode in aqueous electrolyte. The process of Cu plating, in the same cell configuration, leads to significant and reversible discharge capacities on RuO₂ electrodes, while traditional pure transition metal electrodes have negligible capacities and carbon electrodes have a fraction of it. The areal power delivery during discharge is nearly constant (70 μW/cm²), whether charged for seconds or hours; a one hour charge leads to 1.9 C/cm² areal capacity and 85 Wh/kg. Despite exhibiting self-discharge, the cell has 40% energy efficiency if discharged right after charging. The same electrochemical process can be used in flow-cell architectures where flowing the electrolyte mitigates self-discharge and also higher areal power deliveries can be achieved.