An assembled electrochemical cell is formed comprising an anode containing sub-micrometer and micrometer-size particles of an anode material for cyclically intercalating and de-intercalating lithium ions or sodium ions, a cathode containing like-sized particles of a cathode material for intercalating and de-intercalating the ions utilized in the anode, and a non-aqueous electrolyte composed for transporting ions between the anode and cathode. Nanometer-size particles of a basic metal oxide or a metal nitride are mixed with at least one of (i) the particles of electrode material for at least one of the anode and cathode and (ii) the electrolyte. The composition and the amount of the metal oxide or metal nitride is determined for chemically neutralizing acidic contaminants formed in the operation of the electrochemical cell, adsorbing incidental water, and to generally prevent degradation of the respective electrode materials.