FIELD OF THE INVENTION
The present invention proposes an anodized Titanium plate with conductive graphite pasted on it, to be used as an electrode in Redox flow battery applications.
BACKGROUND
An electrode/bipolar plate for a Redox Flow battery should be electrically conductive and shall have an excellent mechanical strength, plasticity, liquid-blocking property, and higher electrical conductivity.
Porous electrically conductive carbon blacks do not always exhibit adequate resistance to corrosion, the corrosion may be caused by electrochemical oxidation in a flow cell. Hence, an alternate material has to be established to improve the resistance towards corrosion.
The fabrication of nanocrystalline Titanium dioxide (TiO2) has recently attracted much attention for their versatile applications in solar cells, fuel cells, electrical and photocatalytic systems because it is highly stable, non-toxic and has a suitable Redox potential for photodegrading pollutants. Several studies have focused on the use of TiO2 nanoparticles for improving the catalytic efficiency with respect to the high surface-to-volume ratio.
DISCUSSION ON PRIOR ART
US 20150364768 A1 titled “Redox flow battery cell stack” discloses a bipolar plate for a Redox flow battery that uses an electrically conductive composite possessing excellent mechanical strength, plasticity, and liquid-blocking property, and higher electrical conductivity is imparted. The bipolar plate consists of an electrically conductive composite prepared by mixing a thermoplastic resin, a carbonaceous material chosen from graphite and carbon black, and a carbon nano-tube, in which a carbonaceous material content is 20 to 150 parts by weight and a

carbon nanotube content is 1 to 10 parts by weight relative to 100 parts by weight of the thermoplastic resin.
US 20100269894 A1 titled “Titanium dioxide nanotubes and their use in photovoltaic devices” discloses a substrate surface having an array of Titanium dioxide nanotubes formed at a rate of about 40 µm/hr by anodizing Titanium substrate. The nanotubes contain hexagonal pore structures, are hexagonal in nature along their length and are tightly packed. The electrolyte solution used in the anodization process comprises the complexing agent Na2[H2EDTA]. A Titanium dioxide nanotube array detaches from the underlying Titanium dioxide substrate by allowing the array to stand at room temperature, or by applying heat to the array. The resulting Titanium dioxide membrane has a barrier layer on the back side of the membrane 4 that can be removed by a chemical etch to create a membrane 4 having nanotubes with open ends, which closes one end of the constituent nanotubes. The Titanium dioxide membrane can be filled with a photosensitive dye and used as part of dye-sensitive photovoltaic devices.
The work of anodized Titanium plate with conductive graphite pasted on it demonstrates excellent current collector properties. Anodization forms Titanium nanotubes. The developed Titanium nanotubes with optimum wall thickness reduces the electrical resistance and increase the surface area which is the actual purpose of adhering the conductive graphite. While comparing the graphite plate and anodized Titanium plate with conductive graphite pasted on it for a current collector, the later showed better conductivity and enhanced electrochemical oxidation reaction.
SUMMARY OF THE INVENTION
An Electrode/bipolar plate for a Redox flow battery has to deliver the following properties, electrically conductive and excellent mechanical strength, plasticity, liquid-blocking property, and higher electrical conductivity.

Conductive graphite paste and some parts of activated charcoal were coated over the TiO2 nanotubes are prepared by anodic oxidation. This material can be used for the replacement of graphite which was treated as a current collector for the Redox flow cell stack.
In this invention, a method of the anodized Titanium plate coated with conductive graphite having improved corrosion resistance in Redox flow battery having, a current collector, conductive graphite paste, an anolyte, a membrane, bipolar electrode, an anolyte tank, a catholyte tank, an electrolyte, a Pt cathode, a Ti metal anode, and a TiO2 nanotube.. Anodizing by applying different voltages for a fixed duration of an hour. Sonicating of sample in Millipore water for 5 minutes and drying overnight, after the anodization. Synthesizing of high density, well-ordered, and uniform TiO2 from a Titanium plate through electrochemical anodic oxidation technique. Opening up of the top surface of TiO2 nanotubes with the diameter ranging from 10 to 40 nm with wall thickness of about 3.7 to 7.4 nm, also, the TiO2 nanotubes are prepared by anodic oxidation of Titanium always have one open end and another closed end. Generating of Titanium dioxide nanotubes on the surface of metal Titanium while mass fraction of ammonium fluoride reaches to 0.5% which is best, as at a mass fraction of up to 2.0% due to the corrosion rate of Titanium dioxide nanotubes caused by the fluorine ion in the electrolyte is faster than growth rate with an increasing concentration. Coating over the TiO2 nanotubes with conductive graphite paste, and some parts of activated charcoal by an anodic oxidation which is used as a replacement of graphite used as current collector for redox flow cell stack. The square Ti plate anode is of dimensions of 4 cm x 4 cm. The Pt mesh cathode dimensions are of 2.0 cm x 2.0 cm. The electrolyte is a mixture of 94.5 wt% ethylene glycol, 5 wt% water and 0.5 wt% ammonium fluoride.

BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows two cells in series in a flow battery arrangement.
Figure 2 shows the setup of a single cell flow battery.
Figure 3 shows the Schematic electrode setup used for the anodization of TiO2.
Figure 4 shows the Scanning Electron Micrograph (SEM) of TNT in Ti plate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 shows that the two cells are in series in the flow battery arrangement. Both end plates act as a current collector 1. Between the endplate 2 and bipolar plate 5, a membrane 4 for the hydronium (H+) ions transfer purpose is established. Anolyte flows in the negative side of the end plate and negative side of the bipolar plate 5. Similarly, catholyte flows in the positive side of an end plate and positive side of the bipolar plate 5.
Figure 2 shows the schematic setup of single cell flow battery. In Redox flow cells, the aqueous electrolyte solutions containing reactive species are stored in external tanks 9 and circulated through each cell in the stack. Each cell contains two electrodes 1 at which reversible electrochemical reactions occur. These cells are always composed of a bipolar 5 or end plate - carbon felt - membrane - carbon felt - bipolar or end plates.
In the Vanadium Redox flow battery (VRB) system, two simultaneous reactions occur on both sides of the membrane 4. During the discharge, the electrons are removed from the anolyte 3 and transferred through the external circuit to the catholyte 7. The flow of electrons is reversed during the charge, the reduction is now taking place in the anolyte 6 and the oxidation in the catholyte 7.
Figure 3 shows the schematic setup of anodization. In this setup, Ti metal plate with 1 mm thickness is used as working electrode (anode 18) and Platinum mesh is used as a counter electrode (cathode 14). pH electrode 19 with a pH meter 17

determine the pH of the electrolyte solution in the reaction bath 15. A thermometer 20 is used to check the electrolyte 9 temperature during the anodization process. A Potentiostat 13 is used for applying required potential for the anodization process.
During the anodization process, metal dissolution occurs in the Titanium plate (anode 18). The oxide film barrier layer is generated on the surface of the metal Titanium with the effect of the external electric field and the electrolyte 9. As the anodization time grows, the hole 21 distributed on the surface becomes uniform and forms an orderly structure. The effect of chemical etching results in TiO2 on the hole 21 surface dissolved. The depth of the hole 21 is deepened with the effect of electrochemical oxidation and electrochemical corrosion. Finally, a highly ordered TiO2 nanotube 22 arrays will be formed in the working electrode.
Figure 4 shows the Scanning Electron Microscope (SEM) images of a highly ordered TiO2 nanotube 22 arrays. After anodization, the working electrode with the nanotubes formed is visualized by the SEM showing gaps or holes 21.
The fabrication of nanocrystalline Titanium dioxide (TiO2) has recently attracted much attention in terms of their versatile applications in solar cells, fuel cells, electrical and photocatalytic systems because it is highly stable, non-toxic and has a suitable Redox potential for photo-degrading pollutants. Several studies have focused on the use of TiO2 nanoparticles for the purposes of improving the catalytic efficiency with respect to the high surface-to-volume ratio.
Ti plate which is cut into square shape pieces with dimensions of 4 cm x 4 cm is used as anode 18 (working electrode). Pt mesh with dimensions of 2.0 cm x 2.0 cm is used as cathode 14 (counter electrode). The electrolyte 9 is a mixture of 94.5 wt% ethylene glycol, 5 wt% water, and 0.5 wt% ammonium fluoride. Anodization is carried out by applying different voltages for a fixed duration of one hour. After the anodization, the sample was again sonicated in Millipore water for 5 minutes and dried overnight.

High density, well-ordered, and uniform TiO2 are synthesized from Titanium plate with the electrochemical anodic oxidation technique. The top surface of the tubes are open, and the diameters of these nanotubes ranging from 10 to 40 nm with a wall thickness of about 3.7 to 7.4 nm. TiO2 nanotubes are prepared by anodic oxidation of Titanium always have one open end and another closed end. When the mass fraction of ammonium fluoride reached to 0.5%, Titanium dioxide nanotubes can generate on the surface of metal Titanium. Morphology was destroyed when the mass fraction of ammonium fluoride up to 2.0%, this is because the corrosion rate of Titanium dioxide nanotubes caused by the fluorine ion in the electrolyte 9 is faster than the growth rate with the concentration increasing, so the best mass fraction of ammonium fluoride for the generation of Titanium dioxide is 0.5%.
Conductive graphite paste 2 and some parts of activated charcoal were coated over the TiO2 nanotubes are prepared by anodic oxidation. This material can be used for the replacement of graphite which was used as current collector 1 for Redox flow cell stack.

WE CLAIM:
1. An anodized Titanium plate coated with conductive graphite having
improved corrosion resistance comprising of, (a) a current collector (1),
(b) a conductive graphite paste (2), (c) an anolyte (3), (d) a membrane (4),
(e) bipolar electrode (5), (f) an anolyte tank (6), (g) a catholyte tank (7),
(h) an electrolyte (9), (i) a Pt cathode (14), (j) a Ti metal anode (18), and
(k) a TiO2 nanotube (22), wherein:
(i) The Ti plate is square shape and used as anode (18) (working electrode), and the Pt mesh is used as cathode (14) (counter electrode);
(ii) The electrolyte (9) is a mixture of ethylene glycol, water, and ammonium fluoride; and
(iii) The current collector (1) uses conductive graphite paste 2 and said TiO2 nanotubes (22) are coated by a portion of activated charcoal through anodic oxidation to replace usual graphite.
2. The anodized Titanium plate coated with conductive graphite having improved corrosion resistance as claimed in Claim 1, is used in Redox flow battery applications.
3. The anodized Titanium plate coated with conductive graphite having improved corrosion resistance as claimed in Claim 1, wherein the square Ti plate anode (18) is of dimensions of 4 cm x 4 cm.
4. The anodized Titanium plate coated with conductive graphite having improved corrosion resistance as claimed in Claim 1, wherein the Pt mesh cathode (14) dimensions are of 2.0 cm x 2.0 cm.
5. The anodized Titanium plate coated with conductive graphite having improved corrosion resistance as claimed in Claim 1, wherein the electrolyte (9) is a mixture of 94.5 wt% ethylene glycol, 5 wt% water and 0.5 wt% ammonium fluoride.

6. A method of the anodized Titanium plate coated with conductive graphite having improved corrosion resistance in Redox flow battery comprising of, (a) a current collector (1), (b) a conductive graphite paste (2), (c) an anolyte (3), (d) a membrane (4), (e) bipolar electrode (5), (f) an anolyte tank (6), (g) a catholyte tank (7), (h) an electrolyte (9), (i) a Pt cathode (14), (j) a Ti metal anode (18), and (k) a TiO2 nanotube (22), comprising the steps of:
(i) Anodizing by applying different voltages for a fixed duration of an hour;
(ii) Sonicating of sample in Millipore water for 5 minutes and drying overnight, after the anodization;
(iii) Synthesizing of high density, well-ordered, and uniform TiO2 from a Titanium plate through electrochemical anodic oxidation technique;
(iv) Opening up of the top surface of TiO2 nanotubes with the diameter ranging from 10 to 40 nm with wall thickness of about 3.7 to 7.4 nm, also, the TiO2 nanotubes are prepared by anodic oxidation of Titanium always have one open end and another closed end;
(v) Generating of Titanium dioxide nanotubes on the surface of metal Titanium while mass fraction of ammonium fluoride reaches to 0.5% which is best, as at a mass fraction of up to 2.0% due to the corrosion rate of Titanium dioxide nanotubes caused by the fluorine ion in the electrolyte (9) is faster than growth rate with an increasing concentration; and
(vi) Coating over the TiO2 nanotubes with conductive graphite paste (2) and some parts of activated charcoal by an anodic oxidation which is used as a replacement of graphite used as current collector (1) for redox flow cell stack.

7. The method of the anodized Titanium plate coated with conductive graphite having improved corrosion resistance in Redox flow battery of as claimed in Claim 6, wherein the square Ti plate anode (18) is of dimensions of 4 cm x 4 cm.
8. The method of the anodized Titanium plate coated with conductive graphite having improved corrosion resistance in Redox flow battery of as claimed in Claim 6, wherein the Pt mesh cathode (14) dimensions are of 2.0 cm x 2.0 cm.
9. The method of the anodized Titanium plate coated with conductive graphite having improved corrosion resistance in Redox flow battery of as claimed in Claim 6, wherein the electrolyte (9) is a mixture of 94.5 wt% ethylene glycol, 5 wt% water and 0.5 wt% ammonium fluoride.