A battery electrode composition is provided comprising anode and cathode electrodes and an electrolyte ionically coupling the anode and the cathode. At least one of the electrodes may comprise a plurality of active material particles provided to store and release ions during battery operation. The electrolyte may comprise an aqueous metal-ion electrolyte ionically interconnecting the active material particles. Further, the plurality of active material particles may comprise a conformal, metal-ion permeable coating at the interface between the active material particles and the aqueous metal-ion electrolyte. The conformal, metal-ion permeable coating impedes water decomposition at the aforesaid at least one of the electrodes.