An electrochemical cell for a secondary battery is provided, which includes a positive electrode having an intercalation cathode material of bentonite; a negative electrode material having an anode material containing one of magnesium and sodium; an electrolyte positioned in contact with at least one of the positive electrode and the negative electrode; wherein, when the anode material contains magnesium, the electrolyte is a solid gel polymeric electrolyte; and wherein, when the anode material is sodium, the electrolyte is a salt electrolyte, both the anode material and the electrolyte are molten at the operating temperature of the battery, and the cell further comprises a beta alumina solid electrolyte separator between the negative electrode and the electrolyte. To increase its conductivity, the bentonite material is treated, before cell assembly, with an acid and/or intercalated with an anilinium ion, which is then polymerized to form a polyaniline within the bentonite framework.