Electrochemical cell comprising an electrodeposited fuel

Abstract

Provided is a rechargeable electrochemical cell system for generating electrical current using a fuel and an oxidant. The system includes a plurality of electrochemical cells. A controller is configured to apply an electrical current between charging electrode(s) and a fuel electrode with the charging electrode(s) functioning as an anode and the fuel electrode functioning as a cathode, such that reducible metal fuel ions in the ionically conductive medium are reduced and electrodeposited as metal fuel in oxidizable form on the fuel electrode. The controller may selectively apply current to a charging electrode and third electrode between fuel electrodes of separate cells to increase uniformity of the metal fuel being electrodeposited on the fuel electrode. The controller controls a number of switches to apply current to the electrodes and select different modes for the system. Also provided are methods for charging and discharging an electrochemical cell system, and selecting different modes.

What is claimed: 
     
         1 . An electrochemical cell comprising:
 a fuel electrode;   an oxidant electrode;   an oxygen evolving electrode;   an oxygen reduction air electrode exposed to external oxygen;   an aqueous ionically conductive medium common to and contacting each of the electrodes;   the fuel electrode and the oxidant electrode being operable in a discharge mode wherein the fuel electrode functions as an anode and the oxidant electrode functions as a cathode to output electrical current;   the oxygen evolving electrode and the oxidant reduction air electrode being operable to generate convective flow in the aqueous ionically conductive medium by application of current therebetween wherein the oxygen evolving electrode acts as an anode to evolve oxygen to generate convective flow in the cell by oxidizing a species thereof from the aqueous ionically conductive medium and the oxidant reduction air electrode acts as a cathode to reduce oxygen.   
     
     
         2 . The electrochemical cell according to  claim 1 , further comprising a controller configured to deliver electrical current of anodic potential to the oxygen evolving electrode and of a cathodic potential to the oxidant reduction air electrode to generate the convective flow. 
     
     
         3 . The electrochemical cell according to  claim 1 , further comprising a plurality of switches, each switch being associated with one of the electrodes and operatively coupled to a controller, wherein the controller is configured to control discharge and charge operations of the cells by controlling an open state and a closed state for each switch of the plurality of switches, such that at least one of the plurality of switches is in an open state and at least one of the plurality of switches is in a closed state during each of the discharge and charge operations. 
     
     
         4 . The electrochemical cell according to  claim 1 , wherein the fuel electrode comprises a series of permeable electrode bodies arranged in spaced apart relation. 
     
     
         5 . The electrochemical cell system according to  claim 2 , wherein the controller is operatively connected to a sensor that senses a condition of the electrochemical cell and wherein the sensor senses at least one input parameter. 
     
     
         6 . The electrochemical cell system according to  claim 4 , wherein the input parameter comprises input via a user input. 
     
     
         7 . The electrochemical cell system according to  claim 4 , wherein the input parameter comprises a limit parameter and wherein the controller is further configured to compare a cell property to the limit parameter. 
     
     
         8 . The electrochemical cell system according to  claim 6 , wherein the cell property comprises a voltage, a cumulative charge capacity, an impedance between electrodes, a slope of electrode voltages, a current, a resistance to a sensing electrode, or a shorting event. 
     
     
         9 . A method of discharging an electrochemical cell, the cell comprising a fuel electrode, an oxidant electrode, an oxygen evolving electrode, an oxygen reduction air electrode exposed to external oxygen, and an aqueous ionically conductive medium common to and contacting each of the electrodes; the method comprising:
 operating the fuel electrode and the oxidant electrode in a discharge mode wherein the fuel electrode functions as an anode and the oxidant electrode functions as a cathode to output electrical current; and   generating convective flow in the aqueous ionically conductive medium by application of current between the oxygen evolving electrode and the oxidant reduction air electrode, wherein the oxygen evolving electrode acts as an anode to evolve oxygen by oxidizing a species thereof from the aqueous ionically conductive medium and the oxidant reduction air electrode acts as a cathode to reduce oxygen.   
     
     
         10 . The method of  claim 9 , wherein the cell further comprises a controller configured to deliver electrical current from a power supply to the electrodes, and wherein the method further comprises: using the controller to:
 deliver electrical current of anodic potential to the oxygen evolving electrode,   deliver electrical current of a cathodic potential to the oxidant reduction air electrode, to generate the convective flow.   
     
     
         11 . The method according to  claim 10 , further comprising switching a plurality of switches operatively coupled between the controller and the electrodes to charge the electrochemical cell based on the a selected charging mode. 
     
     
         12 . The method according to  claim 10 , wherein the fuel electrode comprises a series of permeable electrode bodies arranged in spaced apart relation. 
     
     
         13 . The method according to  claim 10 , further comprising receiving at least one input parameter at the controller, wherein the controller is configured to select between charge modes based on at least one input parameter. 
     
     
         14 . The method according to  claim 10 , further comprising sensing a condition of the electrochemical cell by a sensor coupled to the controller and wherein the input parameter is input by the sensor. 
     
     
         15 . The method according to  claim 13 , wherein the input parameter is input via a user input. 
     
     
         16 . The method according to  claim 13 , further comprising comparing a cell property to the input parameter, wherein the input parameter comprises a limit parameter. 
     
     
         17 . The method according to  claim 16 , wherein the cell property comprises a voltage, a cumulative charge capacity, an impedance between electrodes, a slope of electrode voltages, a current, a resistance to a sensing electrode, or a shorting event.