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 RuO2 anode 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 mu W/cm(2)), whether charged for seconds or hours; a one hour charge leads to 1.9 C/cm(2) 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. (C) 2015 The Electrochemical Society.