An electrochemical battery that exchanges energy with an external device. The battery includes a container containing a positive electrode, a negative electrode and an intervening electrolyte, the electrodes and electrolyte existing as liquid material layers in the container at the operating temperature of the battery so that adjacent layers form respective electrode-electrolyte interfaces. Positive and negative current collectors are in electrical contact with the positive and negative electrodes, respectively, both collectors being adapted for connection to the external device to create a circuit through which current flows. A circulation producer in the battery causes circulation within at least one of the layers to increase the flux of material in one layer to an interface with an adjacent layer, thereby giving the battery a greater current/power capability.