System for preparing vanadium electrolyte through cathode flow channel diversion type electrolysis

Abstract

The system for preparing the vanadium electrolyte through the cathode flow channel diversion type electrolysis comprises an electrolysis device, the electrolysis device comprises a cathode part and an anode part, and the cathode part and the anode part are separated through a proton exchange membrane; the cathode part comprises an end plate, an insulating plate, a collector plate, a bipolar plate, a cathode electrode and an insulating pad which are sequentially mounted in a stacked manner, a snakelike, linear or interdigital cathode flow channel is formed in the side surface of one side, attached to the cathode electrode, of the bipolar plate, the cathode flow channel is in an open slot form, one end of the cathode flow channel is a cathode electrolyte inlet, and the other end of the cathode flow channel is a cathode electrolyte outlet. And the other end is a cathode electrode liquid outlet. By adopting the cathode flow channel diversion type electrolytic preparation system for the vanadium electrolyte, the preparation energy consumption is reduced, and the preparation efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of batteries, and in particular relates to a system for preparing vanadium electrolyte by cathode flow channel diversion electrolysis. Background Art

[0002] All-vanadium liquid flow batteries have the advantages of independent design of capacity and power, high safety level, long service life, good design flexibility, and environmental friendliness. These advantages make all-vanadium liquid flow battery energy storage technology stand out among various energy storage technologies and are generally considered to be the energy storage technology with the greatest potential for large-scale application.

[0003] High cost is one of the main factors limiting the large-scale application of all-vanadium flow batteries. It is reported that the manufacturing and operation and maintenance costs of all-vanadium flow battery electrolytes (vanadium electrolytes) account for 40% to 60% of the cost of all-vanadium flow battery energy storage systems. The preparation methods of electrolytes are mainly pure electrolysis and a combination of chemical reduction and electrolysis. The pure electrolysis method is widely favored by researchers because it does not introduce impurities and can be scaled up.

[0004] The electrolyte of all-vanadium flow battery generally uses sulfuric acid as the supporting system and vanadyl sulfate or vanadium pentoxide as raw materials. Vanadyl sulfate is expensive and difficult to prepare. Therefore, using vanadium pentoxide, which is inexpensive and has a relatively simple preparation process, as the raw material to prepare the electrolyte of all-vanadium flow battery is the most effective way to reduce the preparation cost of all-vanadium flow battery electrolyte. However, compared with vanadyl sulfate, vanadium pentoxide has extremely low solubility in sulfuric acid and a slow dissolution rate. The national standard GB / T 37204-2018 stipulates that the vanadium ion concentration in the electrolyte of all-vanadium liquid flow batteries should not be less than 1.5 mol / L. If vanadium pentoxide is used as a raw material to prepare an electrolyte with a concentration of more than 1.5 mol / L, only a trace amount of vanadium pentoxide can be naturally dissolved in sulfuric acid when pure electrolysis is used. Therefore, when using pure electrolysis to prepare all-vanadium liquid flow battery electrolytes, how to make the vanadium pentoxide suspension electrolyzed at low energy consumption and high rate in the electrolysis device under the action of a pump is the main problem hindering the large-scale preparation of vanadium pentoxide electrolytes by pure electrolysis.

[0005] When using an H-type electrolytic cell to prepare an electrolyte for an all-vanadium flow battery using vanadium pentoxide as a raw material, the suspension does not flow, which is bound to result in a poor mass transfer method and insufficient material mixing. This leads to the disadvantages of high energy consumption, low rate, and easy corrosion of graphite felt when using an H-type electrolytic cell to prepare an electrolyte. To overcome the above disadvantages, patent CN200810012119.5 discloses a method and device for preparing a vanadium electrolyte, but it does not consider the problems of vanadium pentoxide suspension blockage and precipitation during the production of the electrolyte. Liu Ran et al. built a method and device for preparing a vanadium electrolyte for the first time in China. A device for flow electrolysis of vanadium pentoxide suspension was built to produce an all-vanadium liquid flow battery electrolyte with good performance, solving the problem of uneven material mixing during the electrolysis process. However, the device has the disadvantages of slow electrolysis rate and high energy consumption, and the prospect of using the device for large-scale preparation of electrolyte is unknown. Patent CN201520407125.3 reports a device for large-scale production of liquid flow battery electrolyte. However, when the device is used to prepare electrolyte in large quantities, there is no clear improvement in the two key issues of electrolyte preparation energy consumption and rate that affect the cost of the electrolyte.

[0006] One of the key factors affecting electrolysis efficiency and energy consumption is that since the cathode electrolyte is a vanadium pentoxide suspension formed by dissolving vanadium pentoxide powder in dilute sulfuric acid, when it flows through the cathode electrode without restraint (i.e., it flows freely in all directions and lacks guidance), the suspension flows slowly, affecting the reaction efficiency and energy consumption. Utility Model Content

[0007] In view of this, the purpose of the present application is to solve at least one of the above problems and provide a system for preparing vanadium electrolyte by cathode flow channel diversion electrolysis, so as to reduce preparation energy consumption and improve preparation efficiency.

[0008] The utility model solves the above problems through the following technical means:

[0009] A system for preparing vanadium electrolyte by cathode flow channel diversion electrolysis comprises an electrolysis device, wherein the electrolysis device comprises a cathode part and an anode part, wherein the cathode part and the anode part are separated by a proton exchange membrane; the cathode part comprises an end plate, an insulating plate, a current collecting plate, a bipolar plate, a cathode electrode and an insulating pad which are stacked and installed in sequence, a serpentine, straight or interdigitated cathode flow channel is provided on the side surface of the bipolar plate which is in contact with the cathode electrode, the cathode flow channel is in the form of an open slot, one end of the cathode flow channel is a cathode electrolyte inlet, and the other end is a cathode electrode liquid outlet.

[0010] Furthermore, the anode part includes an end plate, an insulating plate, a current collecting plate, an anode plate, a fluid frame and a sealing gasket which are stacked in sequence. An anode flow channel is provided on the side of the fluid frame which is in contact with the anode plate. The anode flow channel is an open slot type, and a plurality of diverter columns are arranged in parallel and at intervals on the anode flow channel. One end of the anode flow channel is an anode electrolyte inlet, and the other end is an anode electrode liquid outlet.

[0011] Furthermore, the anode plate is a titanium plate or titanium felt plated with iridium oxide coating or ruthenium-iridium-titanium coating.

[0012] Furthermore, the cathode part and the anode part are stacked and fastened with fasteners.

[0013] Furthermore, it also includes a cathode electrolyte circulation device, which includes a cathode liquid storage tank, an electrolyte delivery pipeline and a delivery pump. The cathode electrolyte inlet and the cathode electrolyte outlet are both connected to the cathode liquid storage tank through the electrolyte delivery pipeline, and a delivery pump is installed on the electrolyte delivery pipeline between the cathode electrolyte inlet and the cathode liquid storage tank.

[0014] Furthermore, it also includes an anode electrolyte circulation device, which includes an anode electrolyte storage tank, an electrolyte delivery pipeline and a delivery pump. The anode electrolyte inlet and the anode electrolyte outlet are both connected to the anode electrolyte storage tank through the electrolyte delivery pipeline, and a delivery pump is installed on the electrolyte delivery pipeline between the anode electrolyte inlet and the anode electrolyte storage tank.

[0015] Furthermore, it also includes a charge and discharge control system, which is electrically connected to the cathode electrode and the anode plate.

[0016] Beneficial effects of the utility model:

[0017] (1) Using a titanium plate or titanium felt coated with iridium oxide or ruthenium iridium titanium as the anode accelerates the rate of oxygen evolution reaction at the anode while reducing the overpotential of the oxygen evolution reaction, so that the energy consumption of preparing the same volume and concentration of electrolyte is lower.

[0018] (2) According to the different characteristics and requirements of the anode and cathode reactions, a method that can satisfy the flow of the cathode and anode fluids is adopted, wherein the cathode flow channel is arranged based on the bipolar plate, and the anode flow channel is arranged based on the fluid frame. On the one hand, the cathode flow channel has a guiding effect on the suspension to prevent its free flow, thereby ensuring the flow speed, optimizing the flow pattern, and reducing the contact resistance. On the other hand, the diversion supply of the anode electrode liquid is realized, further reducing the energy consumption of preparing the same mass of electrolyte.

[0019] (3) Due to the presence of the cathode flow channel, the contact between the vanadium ions and the proton exchange membrane is limited, which does not affect the proton transfer and can hinder the transmembrane transport of vanadium ions, thereby reducing the loss of raw materials during the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0021] Figure 1 It is a schematic diagram of a preferred embodiment of the utility model;

[0022] Figure 2 This is a schematic diagram of an explosion of an electrolysis device;

[0023] Figure 3 is a schematic diagram of a bipolar plate;

[0024] Figure 4 Schematic diagram of the fluid box. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0026] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0027] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0028] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0029] like Figures 1 to 4As shown, this embodiment provides a system for preparing vanadium electrolyte by cathode flow channel diversion electrolysis, comprising an electrolysis device 4, a cathode electrolyte circulation device, an anode electrolyte circulation device and a charge and discharge control system 5, wherein the electrolysis device comprises a cathode part and an anode part, wherein the cathode part and the anode part are separated by a proton exchange membrane; the cathode part comprises an end plate 401, an insulating plate 408, a current collecting plate 402, a bipolar plate 403, a cathode electrode 404 and an insulating pad 405 which are stacked and installed in sequence, and a serpentine, straight or interdigitated cathode flow channel 4032 is provided on the side surface of the bipolar plate where the cathode electrode is bonded, and the cathode flow channel is in the form of an open slot, and one end of the cathode flow channel is a cathode electrolyte inlet 4031, and the other end is a cathode electrode liquid outlet 4033.

[0030] The anode part includes an end plate 401, an insulating plate 408, a current collecting plate 402, an anode plate 407, a fluid frame 406 and a sealing gasket 405 which are stacked in sequence. An anode flow channel 4062 is provided on the side of the fluid frame which is in contact with the anode plate. The anode flow channel is an open slot type. A plurality of diverter columns 4064 are arranged in parallel and at intervals on the anode flow channel. One end of the anode flow channel is an anode electrolyte inlet 4061, and the other end is an anode electrode liquid outlet 4065. During specific assembly, the anode plate is in contact with the anode flow channel, and a diverter gap is formed between adjacent diverter columns, so that the anode electrode liquid (dilute sulfuric acid) can be diverted, so that the anode electrolyte can be evenly dispersed to contact and react with the anode plate.

[0031] The anode plate is a titanium plate or titanium felt coated with iridium oxide or ruthenium iridium titanium; in this embodiment, the anode plate is a titanium plate coated with iridium oxide. In addition, since the proton exchange membrane is a necessary component consistent with the prior art, it is not shown in the drawings, and the proton exchange membrane is clamped and fixed by an insulating pad.

[0032] The cathode electrolyte circulation device includes a cathode storage tank 3, an electrolyte delivery pipeline and a delivery pump. The cathode electrolyte inlet and the cathode electrolyte outlet are both connected to the cathode storage tank through the electrolyte delivery pipeline. A delivery pump is installed on the electrolyte delivery pipeline between the cathode electrolyte inlet and the cathode storage tank.

[0033] The anode electrolyte circulation device comprises an anode liquid storage tank 1, an electrolyte delivery pipeline 6 and a delivery pump 2. The anode electrolyte inlet and the anode electrolyte outlet are both connected to the anode liquid storage tank through the electrolyte delivery pipeline. A delivery pump is installed on the electrolyte delivery pipeline between the anode electrolyte inlet and the anode liquid storage tank.

[0034] The charge and discharge control system is electrically connected to the cathode electrode and the anode plate.

[0035] It can be understood that the cathode part and the anode part are stacked and fastened with fasteners. Preferably, positioning holes for assembling with fasteners can be opened on each assembly component, such as bipolar plate positioning holes 4034 are opened at the four corners of the bipolar plate, and fluid frame positioning holes 4063 are opened at the four corners of the fluid frame.

[0036] The end plate is made of stainless steel and serves as a fastening device to withstand stress; the insulating plate is made of insulating PVC material processed by CNC machine tools and serves to separate the end plate and the current collecting plate; the current collecting plate is made of copper material and serves to collect current and conduct electricity; the anode plate serves as an anode electrode and serves to electrolyze water and conduct electricity; the fluid frame is made of corrosion-resistant insulating PVC sheet processed by CNC machine tools and serves to distribute the anode electrolyte and provide the flow of the anode electrolyte; the sealing gasket is made of a compressible, impermeable, insulating fluororubber flat gasket, It plays the role of closing the fluid frame and the surface of the bipolar plate and fixing the proton exchange membrane; the proton exchange membrane adopts DuPont Nafion117 proton exchange membrane, which separates the cathode and anode electrolytes, and only allows hydrogen ions to pass through to form a loop; the bipolar plate is processed from a 10 mm thick graphite plate that has been treated with anti-permeability, and a serpentine, flat or interdigitated cathode flow channel with a depth of 1 mm is engraved on the surface of the bipolar plate; the cathode electrode adopts 4.6 mm thick graphite felt, and the compression rate after compression is 35%, which provides a reaction point for the reduction reaction of the pentavalent vanadium ions in the vanadium pentoxide suspension. In this example, a graphite felt with a size of 3cm*3cm is used as the cathode electrode.

[0037] In addition to the electrolysis device, the entire system is also equipped with a cathode electrolyte circulation device, an anode electrolyte circulation device and a charge and discharge control system. During the process of electrolysis to prepare the electrolyte, by controlling the amount of electricity charged into the electrolysis device, a 3.5-valent electrolyte can be accurately prepared.

[0038] In this device, the bipolar plate with cathode flow channels and the fluid frame with anode flow channels are the core components. The bipolar plate is where the cathode electrolyte (suspension) flows and penetrates into the cathode electrode and anode area for proton exchange, and plays a conductive role. The fluid frame is responsible for the distribution of dilute sulfuric acid (anolyte).

[0039] The bipolar plate is in close contact with the current collector on the cathode side, and the cathode electrolyte inlet and outlet are protected by corrosion-resistant sealing gaskets to prevent the cathode electrolyte from contacting the cathode current collector. The fluid frame and the anode plate are sealed by corrosion-resistant, high-strength silicone glue.

[0040] On the bipolar plate, the cathode flow channel is designed according to the mass transfer and flow characteristics of the electrolyte. For example, when a serpentine flow channel is used, the mass transfer of the vanadium pentoxide suspension in the cathode electrode is enhanced, the reactant distribution is more uniform, and the reaction rate is improved. When a straight flow channel is used, the flow distance of the suspension is shorter, the pressure drop is lower, the pump work consumed in the electrolysis process is reduced, and the system energy consumption is reduced.

[0041] The working process is as follows:

[0042] The vanadium pentoxide powder is dissolved in dilute sulfuric acid to form a vanadium pentoxide suspension. The suspension enters the cathode flow channel from the cathode storage tank under the action of the delivery pump and penetrates into the cathode electrode to undergo a reduction reaction. The dilute sulfuric acid is stored in the anode storage tank. The dilute sulfuric acid enters the anode flow channel under the action of the delivery pump and undergoes an oxygen evolution reaction on the iridium oxide-coated titanium plate (anode plate).

[0043] The cathode part and the anode part of the electrolysis device are separated by a proton exchange membrane, which only allows hydrogen ions to pass through. There is a directional transmission of electrons in the external circuit. The two together with the conductive structure in the electrolysis device form the circuit path of the electrolysis device.

[0044] The dilute sulfuric acid entering the electrolysis device undergoes an oxygen evolution reaction on the iridium oxide-plated titanium plate (reaction equation 1.1);

[0045] The pentavalent vanadium in the vanadium pentoxide suspension entering the electrolysis device for reaction will first be reduced to a tetravalent vanadium (reaction equation 1.2), and then returned to the cathode liquid storage tank under the action of the delivery pump to mix with the unreacted vanadium pentoxide suspension. The mixture of tetravalent vanadium and pentavalent vanadium will continue to be pumped into the electrolysis device, and the reactions of pentavalent vanadium being reduced to tetravalent vanadium (reaction equation 1.2) and tetravalent vanadium being reduced to trivalent vanadium (reaction equation 1.3) will continue to occur. The generated trivalent vanadium will promote the dissolution of pentavalent vanadium (reaction equation 1.4).

[0046] By controlling the electrolysis time, a 3.5-valent vanadium electrolyte can be obtained.

[0047] The reaction equation of dilute sulfuric acid in the anode storage tank is:

[0048] 2H 2 O-4e - →4H + +O 2 (1.1)

[0049] The reaction equation of the suspension in the cathode storage tank is:

[0050]

[0051] VO 2+ +e - +2H +→V 3+ +H 2 O (1.3)

[0052]

[0053] In summary, the cathode flow channel flow-guiding electrolysis system for preparing vanadium electrolyte of the present application has the following characteristics:

[0054] 1. Self-designed fluid frame and bipolar plate are used to realize asymmetric flow mode of cathode and anode electrolytes; 2. Self-designed electrolysis device is low-cost, simple to assemble and easy to maintain; 3. The cathode part adopts serpentine, straight or interdigitated flow channels to enhance the mass transfer of vanadium pentoxide suspension in the electrolysis device and reduce the energy consumption of preparing electrolyte by electrolysis; 4. Iridium oxide-plated titanium plate is used as the anode reaction material to reduce the overpotential of oxygen evolution reaction and the energy consumption of preparing electrolyte by electrolysis.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A system for preparing vanadium electrolyte by cathode flow channel diversion electrolysis, comprising an electrolysis device, wherein the electrolysis device comprises a cathode part and an anode part, wherein the cathode part and the anode part are separated by a proton exchange membrane; characterized in that: The cathode part includes an end plate, an insulating plate, a current collecting plate, a bipolar plate, a cathode electrode and an insulating pad which are stacked in sequence. A serpentine, straight or interdigitated cathode flow channel is provided on the side of the bipolar plate where the cathode electrode is in contact. The cathode flow channel is in the form of an open groove, one end of the cathode flow channel is a cathode electrolyte inlet, and the other end is a cathode electrode liquid outlet.

2. The system for preparing vanadium electrolyte by cathode flow channel conduction electrolysis according to claim 1, characterized in that: The anode part includes an end plate, an insulating plate, a current collecting plate, an anode plate, a fluid frame and a sealing gasket which are stacked in sequence. An anode flow channel is provided on the side of the fluid frame which is in contact with the anode plate. The anode flow channel is an open slot type. A plurality of diverter columns are arranged in parallel and at intervals on the anode flow channel. One end of the anode flow channel is an anode electrolyte inlet, and the other end is an anode electrode liquid outlet.

3. The system for preparing vanadium electrolyte by cathode flow channel conduction electrolysis according to claim 2, characterized in that: The anode plate is a titanium plate or titanium felt plated with iridium oxide coating or ruthenium iridium titanium.

4. The system for preparing vanadium electrolyte by cathode flow channel conduction electrolysis according to claim 3, characterized in that: The cathode portion and the anode portion are stacked and fastened with fasteners.

5. The system for preparing vanadium electrolyte by cathode flow channel conduction electrolysis according to claim 4, characterized in that: It also includes a cathode electrolyte circulation device, which includes a cathode liquid storage tank, an electrolyte delivery pipeline and a delivery pump. The cathode electrolyte inlet and the cathode electrolyte outlet are both connected to the cathode liquid storage tank through the electrolyte delivery pipeline, and a delivery pump is installed on the electrolyte delivery pipeline between the cathode electrolyte inlet and the cathode liquid storage tank.

6. The system for preparing vanadium electrolyte by cathode flow channel conduction electrolysis according to claim 5, characterized in that: It also includes an anode electrolyte circulation device, which includes an anode electrolyte storage tank, an electrolyte delivery pipeline and a delivery pump. The anode electrolyte inlet and the anode electrolyte outlet are both connected to the anode electrolyte storage tank through the electrolyte delivery pipeline, and a delivery pump is installed on the electrolyte delivery pipeline between the anode electrolyte inlet and the anode electrolyte storage tank.

7. The system for preparing vanadium electrolyte by cathode flow channel conduction electrolysis according to claim 6, characterized in that: Also included is a charge and discharge control system, which is electrically connected to the cathode electrode and the anode plate.

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