Compound electrodes for electrochemical processes

Compound electrodes are used instead of an anode and solution electrode and cathode and solution electrode in an electrochemical system that does not rely on a diaphragm or membrane directly between the anode electrode and the cathode electrode. The compound electrode consists of a solution electrode inside the anode or cathode electrode with a liquid or gel or electrolytic membrane located between the solution electrode and the anode or cathode electrode. The compound electrode may be used in a electrolytic cell, a fuel cell or a unipolar activation cell.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows the construction of a compound electrode according to one embodiment of the invention. The outer electrode 2 is may be an anode or a cathode as required in an electrochemical cell and is made of an electrically conductive material. The inner electrode 4 is also made of an electrically conductive material. An electrically conducting liquid or gel or electrolytic membrane 6 is in contact with and between the outer electrode and the inner electrode so that it allows electrons to pass between the outer electrode and the inner electrode. Non-conductor spacers 8 are provided when liquid or gel is used between the inner and outer electrodes. The liquid or gel must remain stable under the operating voltage and current and temperature of the compound electrode. The electrolytic membrane must be in contact with the inner and outer electrode under all operating conditions of the compound electrode. To ensure good contact, the inner part of the outer electrode and the outer part of the inner electrode may be tapered to fit in planar or cubical electrodes, or conical to fit in circular electrodes. The external surface of the outer electrode 10 may have surfaces that have high specific surface area or coated with protective or catalytic surfaces. Electrical connection 12 is made with the outer electrode and electrical connection 14 is made with the inner electrode. FIG. 2 shows the installation of one embodiment of a compound electrode of the present invention in an electrolytic process. The electrochemical cell has a cathode cell 20 and an anode cell 22 each having a compound electrode within it. The cathode cell 20 has compound electrode 24 in it. The anode cell 22 each has compound electrode 26 in it. The positive terminal 30 of a DC power source 28 is connected to the outer electrode 32 of the compound electrode 24 in the anode cell 22 that is in contact with the anolyte 34 . Anode reaction occurs because electrons are removed from the anolyte. The anolyte containing the ions is transferred mechanically through line 38 to the cathode cell 20 . The electrons are delivered to the outer surface of the cathode compound electrode 24 in contact with the catholyte 36 causing the cathode reaction to occur. The spent catholyte is recycled to the anode cell through line 40 and new anolyte may also be added. The electronic circuit consists of the DC power source 28 to the cathode outer electrode 42 through the liquid or gel or electrolytic membrane between the cathode outer electrode and the inner electrode to the inner cathode electrode and then to the conductor 44 between the inner cathode electrode and the inner anode electrode to the inner anode electrode and then through the liquid or gel or electrolytic membrane between the inner anode electrode and the anode outer electrode to the anode outer electrode and then back to the DC power source. The anode and cathode cells may be cubical or cylindrical. There may be several anode cells and cathode cells and the electrolyte flow between these cells may be connected in series or in parallel. There may be several anode or cathode electrodes in the anode cell and cathode cell and these electrodes may be electrically connected in series or in parallel or groups connected in series or parallel and these groups connected in series or parallel connections. FIG. 3 shows the similar installation of the compound electrodes in a fuel cell process where fuel and an oxidant are consumed to produce electric power. In the example in FIG. 3 , hydrogen 48 is fed into the anode cell 50 where it is catalyzed to the hydrogen ion at the anode electrode 51 and electrons produced travel to the external electrical load 52 . The hydrogen ion contained in the electrolyte is transferred to the cathode cell 54 where oxygen 56 is being fed and water is produced at the cathode electrode 53 . The cathode reaction consists of the reaction of the hydrogen ion plus the oxygen plus the electron from the anode to form water: 2 H (&plus;) &plus;2 e (−) &plus;½O 2 →H 2 O The electronic circuit consists of the electrical load 52 to the cathode outer electrode 60 through the liquid or gel or electrolytic membrane between the cathode outer electrode and the inner electrode to the inner cathode electrode and then to the conductor 62 between the inner cathode electrode and the inner anode electrode to the inner anode electrode and then through the liquid or gel or electrolytic membrane between the inner anode electrode and the anode outer electrode to the anode outer electrode and then back to the electrical load 52 . An alternative electrical connection for fuel cells is to connect the inner electrode of the anode to the outer electrode of the cathode and the inner electrode of the cathode to the electrical load. Compound electrodes may also be used by two methods to carry out unipolar reactions. Unipolar reactions are a new branch of chemistry where electrons are continuously removed or added to a fluid. The fluid may be a liquid or a gas. FIG. 4 shows one method of applying the compound electrodes of the present invention to unipolar processes. The anode compound electrode 70 in the anode cell 72 and the cathode compound electrode 74 in the anode cell 76 are electrically connected by means of the inner electrodes but the anolyte 78 is separate from the catholyte 80 . In general, a neutral anolyte is fed to the anode cell 72 where electrons are removed from the fluid. The positively charged anolyte fluid is discharged from the anode cell 72 through line 82 as a final product or to participate in an external reaction before being returned as neutral anolyte to the anode cell. Similarly, the neutral catholyte 80 is fed into the cathode cell 76 and electrons are added to the fluid. The negatively charged catholyte is discharged from the cathode cell 76 through line 84 as final product or to participate in another process. Power is supplied from DC power source 86 . FIG. 5 shows another method of applying a compound electrode of the present invention to unipolar activation. The compound electrode 90 is turned into a cylindrical electrode. The inner electrode 92 surrounds a cylindrical cell 91 and may be the anode or cathode electrode and the outer electrode 94 is the opposite cathode or anode electrode. The liquid or gel or electrolytic membrane 96 is installed between the two electrodes. An annular outer cell 98 surrounds the outer electrode 94 . In FIG. 5 , the inner cylindrical cell 91 is the anode electrode and is fitted with nonconductive end caps 100 to receive a neutral anolyte fluid in tangential feed 101 and discharge the activated anolyte tangentially at the exit end 102 . The fluid feed of neutral catholyte 103 to the annular outer cell 98 is also tangentially fed and also discharged tangentially from the annular outer or cell 98 through line 104 . The liquid or gel or electrolytic membrane 96 is held between the inner and outer electrode. The contact surfaces of the electrodes when an electrolytic membrane is used are preferably slightly conical in shape and forced together to maintain a pod contact between the inner and outer electrodes. The outer cylinder of the cell may be made of the same material as the outer electrode but preferably, it should be a nonconductor material such as a plastics material. A positive terminal of a DC power source 106 is connected to the inner cylinder electrode and a negative terminal of the DC power source is connected to the outer electrode cylinder.