NOVELTY - An electrochemical cell (20) for a secondary battery, comprises positive electrode having an active intercalation cathode material of bentonite; negative electrode having an active anode material (22) containing one of magnesium and sodium; electrolyte positioned in contact with at least one of the positive and the negative electrode; and when the melting point of the electrolyte is higher than the melting point of sodium, then the electrochemical cell further comprises a separator between the negative electrode and the electrolyte, where the separator is beta-alumina solid electrolyte.    USE - As electrochemical cell for secondary battery (claimed).    ADVANTAGE - The electrochemical cell for battery assembles easily and recharges repeatedly.    DETAILED DESCRIPTION - An electrochemical cell (20) for a secondary battery, comprises positive electrode having an active intercalation cathode material of bentonite, where the bentonite has modified molecular structure as a result of have been treated to enhance its conductivity, the modified molecular structure is at least one of a broken molecular framework resultant from exposing the bentonite to sulfuric acid or a framework in which a polyaniline compound has been intercalated; negative electrode having an active anode material (22) containing one of magnesium and sodium; electrolyte positioned in contact with at least one of the positive electrode and the negative electrode; when the negative electrode contains magnesium, the electrolyte is a solid gel polymeric electrolyte; and when the negative electrode is sodium, the electrolyte is a molten salt electrolyte at the operating temperature of the battery, and when the melting point of the electrolyte is higher than the melting point of sodium, then the electrochemical cell further comprises a separator between the negative electrode and the electrolyte, where the separator is beta-alumina solid electrolyte.    DESCRIPTION OF DRAWING(S) - The figure shows schematic view of a second battery.    Electrochemical cell (20)    Active anode material (22)    Separator (24)    Electrolyte layer (26)    Active cathode layer (28)