Electrolysis stack, bipolar plate and vanadium electrolyte valence state adjusting device

Abstract

The utility model provides a kind of electrolytic cell, bipolar plate and vanadium electrolyte valence adjustment device.The utility model electrolytic cell includes: two end plates and electrolytic cell group, two end plates are located in the two sides of electrolytic cell group in the first direction, electrolytic cell group includes cathode plate, cathode plate is made of carbon material;Anode plate, anode plate is made of metal material;Ion exchange membrane, cathode plate, ion exchange membrane and anode plate are sequentially arranged along the first direction, cathode plate and ion exchange membrane define cathode electrolyte chamber, anode plate and ion exchange membrane define anode electrolyte chamber, wherein electrolytic cell group has positive liquid inlet channel, positive liquid outlet channel, negative liquid inlet channel and negative liquid outlet channel, positive liquid inlet channel and positive liquid outlet channel are communicated with anode electrolyte chamber, negative liquid inlet channel and negative liquid outlet channel are communicated with cathode electrolyte chamber.The utility model electrolytic cell service life is long, electric conductivity is good, cost is low and corrosion resistant.

Description

Technical Field

[0001] This utility model relates to the field of vanadium redox flow battery technology, specifically to an electrolytic stack, bipolar plates, and a vanadium electrolyte valence state adjustment device. Background Technology

[0002] In a vanadium redox flow battery, both the positive and negative electrodes use a circulating vanadium solution as the energy storage medium. Vanadium electrolyte is one of the key materials in the vanadium redox flow battery system. During initial assembly, to ensure charge balance during operation, equal amounts of 3.5-valent (i.e., trivalent and tetravalent vanadium each make up 1 / 2) vanadium electrolyte are typically filled into the anode and cathode tanks. Electrolysis is suitable for producing 3.5-valent electrolyte. The bipolar plate of the electrolytic cell is usually a single, continuous electrode plate. The anode solution and cathode solution are located on opposite sides of the bipolar plate. Using a metal anode plate is prone to acidic chemical corrosion; using coated metal electrodes is expensive; and using non-metallic carbon materials, due to their oxidation under high voltage, limits the voltage of the electrolytic cell, thus affecting operation and resulting in a high failure rate. On the cathode side, the medium is also acidic, but the voltage is lower, leading to hydrogen absorption side reactions. If a metal bipolar plate is used, hydrogen embrittlement is likely to occur, and sulfuric acid will slowly dissolve the metal, causing corrosion. This not only reduces the lifespan of the electrode plate but also contaminates the electrolyte. Adding an oxide coating to the electrode surface will exacerbate the hydrogen absorption side reactions and reduce current efficiency. In summary, if a metallic material is used for the bipolar plate, corrosion is difficult to solve; if a non-metallic material is used, the mechanical strength is low, and the anode is prone to oxidation. Furthermore, the vanadium redox flow battery electrochemical valence state adjustment system in related technologies typically uses an electrolyte with a specified valence state as the electrolysis endpoint, and endpoint detection often relies on manual sampling and testing, increasing maintenance costs. Utility Model Content

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention provide an electrolytic stack, bipolar plates, and a vanadium electrolyte valence state adjustment device.

[0004] The electrolytic cell stack of this utility model embodiment includes:

[0005] Two end plates; and

[0006] An electrolytic cell assembly, wherein two end plates are located on both sides of the electrolytic cell assembly in a first direction, the electrolytic cell assembly includes a cathode plate made of carbon material;

[0007] An anode plate, said anode plate being made of a metallic material;

[0008] An ion exchange membrane is provided, wherein the cathode plate, the ion exchange membrane, and the anode plate are arranged sequentially along the first direction. The cathode plate and the ion exchange membrane define a cathode electrolyte chamber, and the anode plate and the ion exchange membrane define an anode electrolyte chamber. The electrolytic cell assembly has a positive electrode liquid inlet channel, a positive electrode liquid outlet channel, a negative electrode liquid inlet channel, and a negative electrode liquid outlet channel. The positive electrode liquid inlet channel and the positive electrode liquid outlet channel are connected to the anode electrolyte chamber, and the negative electrode liquid inlet channel and the negative electrode liquid outlet channel are connected to the cathode electrolyte chamber.

[0009] In some embodiments, there are multiple electrolytic cell groups, and the multiple electrolytic cell groups are stacked sequentially along the first direction;

[0010] The electrolytic stack includes bipolar plates, the anode side of which is made of a metallic material and the cathode side of which is made of a carbon material. The anode side and the cathode side of the bipolar plates are respectively arranged adjacent to the anode plate and the cathode plate in the first direction.

[0011] In some embodiments, carbon material is hot-pressed onto the anode plate to form the bipolar plate;

[0012] Alternatively, the cathode plate and the anode plate can be attached and fixed together in the first direction to form the bipolar plate.

[0013] In some embodiments, the electrolytic stack further includes a cathode insulating plate, a cathode current collector, an anode current collector, and an anode insulating plate, wherein one of the two end plates, the cathode insulating plate, the cathode current collector, the plurality of electrolytic cell groups, the anode current collector, the anode insulating plate, and the other of the two end plates are arranged sequentially in the first direction;

[0014] Each of the electrolytic cells further includes a flow frame, which is provided between the ion exchange membrane and each of the anode plate and the cathode plate.

[0015] In some embodiments, the end plate is made of aluminum alloy, titanium alloy or stainless steel.

[0016] Both the anode current collector and the cathode current collector are copper plates;

[0017] The anode plate is made of stainless steel, titanium, or titanium alloy.

[0018] The cathode plate is made of flexible graphite material.

[0019] This utility model also proposes a bipolar plate, which includes an anode plate and a cathode plate fixed together in a first direction. The thickness directions of the anode plate and the cathode plate are both in the first direction. The anode plate is made of a metallic material, and the cathode plate is made of a carbon material. The anode plate constitutes the anode side of the bipolar plate, and the cathode plate constitutes the cathode side of the bipolar plate.

[0020] This utility model also proposes a vanadium electrolyte valence state adjustment device, including...

[0021] An electrolysis unit is provided, comprising an electrolysis power source and an electrolysis stack. The electrolysis stack is as described above, and has a positive electrode liquid inlet channel, a positive electrode liquid outlet channel, a negative electrode liquid inlet channel, and a negative electrode liquid outlet channel. The positive electrode of the electrolysis power source is connected to the anode current collector of the electrolysis stack, and the negative electrode of the electrolysis power source is connected to the cathode current collector of the electrolysis stack.

[0022] The liquid storage section includes a positive electrode liquid storage tank and a negative electrode liquid storage tank. The positive electrode liquid storage tank is used to store positive electrode electrolyte, and the negative electrode liquid storage tank is used to store negative electrode electrolyte. The outlet of the positive electrode liquid storage tank is connected to the inlet of the positive electrode liquid inlet channel through a first pipeline, the outlet of the positive electrode liquid outlet channel is connected to the inlet of the positive electrode liquid storage tank through a second pipeline, the outlet of the negative electrode liquid storage tank is connected to the inlet of the negative electrode liquid inlet channel through a third pipeline, and the outlet of the negative electrode liquid outlet channel is connected to the inlet of the negative electrode liquid storage tank through a fourth pipeline.

[0023] The valence state detection unit is used to detect the valence state of the negative electrode electrolyte discharged from the negative electrode liquid storage tank.

[0024] In some embodiments, the valence state detection unit includes a sampling pipeline and a detection device. The two ends of the sampling pipeline are respectively connected to the third pipeline and the detection device. The sampling pipeline is equipped with a sampling pump, which samples the negative electrode electrolyte discharged from the negative electrode liquid storage tank at first preset time intervals.

[0025] In some embodiments, the negative electrode electrolyte is a vanadium electrolyte, the negative electrode liquid storage tank is equipped with a stirring device, and filters are provided at the end of the first pipeline adjacent to the positive electrode liquid inlet channel and at the end of the third pipeline adjacent to the negative electrode liquid inlet channel;

[0026] The first preset time is greater than or equal to 0.1 seconds and less than or equal to 300 seconds;

[0027] The detection device includes a flow cell and an ultraviolet spectrophotometer;

[0028] The optical path length of the flow cell is greater than or equal to 0.1 mm and less than or equal to 0.2 mm. After the vanadium electrolyte obtained by the injection pump is introduced into the flow cell, the flow cell is placed in the ultraviolet spectrophotometer, and then the valence state of the vanadium electrolyte is obtained by measuring the absorbance of the vanadium electrolyte.

[0029] Alternatively, the optical path length of the flow cell is greater than or equal to 10 mm and less than or equal to 20 mm. After mixing the second preset volume of vanadium electrolyte obtained by the injection pump with the third preset volume of pure water in the mixing chamber, the mixture is introduced into the flow cell. Then, the flow cell is placed in the ultraviolet spectrophotometer, and the valence state of the vanadium electrolyte is obtained by measuring the absorbance of the vanadium electrolyte. The ratio of the second preset volume to the third preset volume is 1:(10-100).

[0030] In some embodiments, the electrolysis unit further includes a voltage monitor connected to a plurality of tabs on the electrolytic stack to detect the voltage of each electrolytic cell group in the electrolytic stack;

[0031] Both the positive electrode liquid storage tank and the negative electrode liquid storage tank are equipped with temperature regulation devices;

[0032] The positive electrode liquid storage tank is equipped with a positive electrode liquid storage tank level gauge, and the negative electrode liquid storage tank is equipped with a negative electrode liquid storage tank level gauge;

[0033] At least one of the first pipeline and the second pipeline is equipped with a positive circulation pump;

[0034] Both the first pipeline and the second pipeline are equipped with a positive temperature sensor and a positive pressure sensor;

[0035] At least one of the third pipeline and the fourth pipeline is equipped with a negative circulation pump;

[0036] Both the third and fourth pipelines are equipped with negative temperature sensors and negative pressure sensors.

[0037] The beneficial effects of this utility model are as follows: The cathode plate of the electrolytic stack according to the embodiment of this utility model is made of carbon material, which makes the cathode plate corrosion resistant. After the vanadium electrolyte enters the cathode electrolyte chamber, the corrosion impact on the cathode plate is small, thereby improving the service life of the electrolytic stack. The anode plate is made of metal material, which has good conductivity and low cost. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of an electrolytic cell stack according to an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of a vanadium electrolyte valence state adjustment device according to an embodiment of the present invention.

[0040] Figure label:

[0041] 1. Electrolytic stack; 11. End plate; 12. Cathode plate; 13. Anode plate; 14. Ion exchange membrane; 15. Bipolar plate; 16. Cathode insulating plate; 17. Cathode current collector; 18. Anode current collector; 19. Anode insulating plate; 101. Liquid flow frame.

[0042] 2. Electrolysis power source;

[0043] 3. Positive electrode liquid storage tank; 31. First pipeline; 32. Second pipeline; 33. Positive electrode liquid storage tank level gauge; 34. Positive electrode circulation pump; 35. Positive electrode temperature sensor; 36. Positive electrode pressure sensor; 37. Positive electrode liquid drain port.

[0044] 4. Negative electrode liquid storage tank; 41. Third pipeline; 42. Fourth pipeline; 43. Negative electrode liquid storage tank level gauge; 44. Negative electrode circulation pump; 45. Negative electrode temperature sensor; 46. Negative electrode pressure sensor; 47. Negative electrode vent; 48. Stirring device.

[0045] 5. Sampling pipeline, 51. Detection device, 52. Sampling pump. Detailed Implementation

[0046] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0047] The electrolytic cell stack 1 of this utility model is described below with reference to the accompanying drawings. For example... Figure 1 As shown, the electrolytic stack 1 according to an embodiment of the present invention includes two end plates 11 and an electrolytic cell group, with the two end plates 11 located on both sides of the electrolytic cell group in a first direction.

[0048] The electrolytic cell assembly includes a cathode plate 12, an anode plate 13, and an ion exchange membrane 14. The cathode plate 12 is made of carbon material, and the anode plate 13 is made of metal material. The cathode plate 12, ion exchange membrane 14, and anode plate 13 are arranged sequentially along a first direction. The cathode plate 12 and the ion exchange membrane 14 define a cathode electrolyte chamber, and the anode plate 13 and the ion exchange membrane 14 define an anode electrolyte chamber.

[0049] The electrolytic cell assembly includes a positive electrode inlet channel, a positive electrode outlet channel, a negative electrode inlet channel, and a negative electrode outlet channel. The positive electrode inlet channel and the positive electrode outlet channel are connected to the anolyte chamber, and the negative electrode inlet channel and the negative electrode outlet channel are connected to the cathode electrolyte chamber. Specifically, the positive electrode electrolyte can be introduced into the anolyte chamber through the protective positive electrode inlet channel for electrolysis to undergo an oxidation reaction, and then discharged from the protective positive electrode outlet channel. The negative electrode electrolyte can be introduced into the cathode electrolyte chamber through the protective negative electrode inlet channel for electrolysis to undergo a reduction reaction, and then discharged from the protective negative electrode outlet channel.

[0050] Anode plate 13 provides a reaction surface, promoting the oxidation reaction of active substances in the positive electrode electrolyte. Anode plate 13 also promotes the reduction reaction in the negative electrode electrolyte. Ion exchange membrane 14 selectively allows ions (such as H+) to pass through. + This prevents the direct mixing of positive and negative electrode electrolytes.

[0051] According to an embodiment of the present invention, the cathode plate 12 of the electrolytic stack 1 is made of carbon material, which makes the cathode plate 12 corrosion resistant. After the vanadium electrolyte enters the cathode electrolyte chamber, the corrosion impact on the cathode plate 12 is small, thereby improving the service life of the electrolytic stack 1. The anode plate 13 is made of metal material, which has good conductivity and low cost.

[0052] In some embodiments, there are multiple electrolytic cell groups, which are stacked sequentially along a first direction, with a positive electrode liquid inlet channel, a positive electrode liquid outlet channel, a negative electrode liquid inlet channel, and a negative electrode liquid outlet channel penetrating through the multiple electrolytic cell groups.

[0053] This utility model also proposes a bipolar plate 15. According to an embodiment of this utility model, the bipolar plate 15 includes an anode plate 13 and a cathode plate 12 fixed together in a first direction. The thickness directions of both the anode plate 13 and the cathode plate 12 are in the first direction. The anode plate 13 is made of a metallic material, and the cathode plate 12 is made of a carbon material. The anode plate 13 constitutes the anode side of the bipolar plate 15, and the cathode plate 12 constitutes the cathode side of the bipolar plate 15.

[0054] In some embodiments, the electrolytic stack 1 includes bipolar plates 15. The anode side of the bipolar plates 15 is made of a metallic material, and the cathode side is made of a carbon material. The anode and cathode sides of the bipolar plates 15 respectively form adjacent anode plates 13 and cathode plates 12 in a first direction. Specifically, the bipolar plates 15 are each composed of two layers of material in the first direction, including a metal layer made of a metallic material and a carbon layer made of a carbon material. The metal layer is the anode side of the bipolar plates 15, and the carbon layer is the cathode side of the bipolar plates 15. Adjacent anode plates 13 and cathode plates 12 in the first direction are formed by bipolar plates 15. The anode side of the bipolar plates 15 forms the anode plate 13 and defines an anolyte chamber with an ion exchange membrane 14. The cathode side of the bipolar plates 15 forms the cathode plate 12 and defines a cathode electrolyte chamber with an ion exchange membrane 14.

[0055] In some embodiments, the anode plate 13 is made of stainless steel, titanium, or titanium alloy. The cathode plate 12 is made of flexible graphite. That is, the anode side of the bipolar plate 15 is made of stainless steel, titanium, or titanium alloy, and the cathode side of the bipolar plate 15 is made of flexible graphite. By controlling the processing precision, sealing and composite can be achieved, resulting in high strength and high corrosion resistance. The flexible graphite plate has self-sealing properties, and the electrolytic stack 1 has good sealing performance.

[0056] In some embodiments, carbon material is hot-pressed onto the anode plate 13 to form a bipolar plate 15. Alternatively, the cathode plate 12 and the anode plate 13 are bonded and fixed together in a first direction to form the bipolar plate 15. Specifically, the bipolar plate 15 may be integrally formed by hot-pressing carbon material onto the anode plate 13, or the bipolar plate 15 may be formed by mechanically joining the anode plate 13 and the cathode plate 12.

[0057] In some embodiments, the electrolytic stack 1 further includes a cathode insulating plate 16, a cathode current collector 17, an anode current collector 18, and an anode insulating plate 19. One of the two end plates 11, the cathode insulating plate 16, the cathode current collector 17, the plurality of electrolytic cell groups, the anode current collector 18, the anode insulating plate 19, and the other of the two end plates 11 are arranged sequentially in a first direction.

[0058] Each electrolytic cell assembly also includes a flow frame 101, which is provided between the ion exchange membrane 14 and each of the anode plate 13 and cathode plate 12. A seal is provided between adjacent flow frames 101, ion exchange membranes 14, and anode plates 13 and 12. The seal prevents electrolyte leakage and ensures sealing between layers. The flow frame 101 serves as a frame for fixing the ion exchange membrane 14. For example, the inner wall of the flow frame 101, the ion exchange membrane 14, and the anode plate 13 define the anolyte chamber, and the inner wall of the flow frame 101, the ion exchange membrane 14, and the cathode plate 12 define the cathode electrolyte chamber. The flow frame 101 contains titanium mesh and titanium fiber felt arranged sequentially in the anolyte chamber, serving to conduct electrons and facilitate gas diffusion and fluid flow; the flow frame 101 also contains graphite felt located in the cathode electrolyte chamber, serving to increase reaction sites and facilitate fluid flow.

[0059] Specifically, end plates 11 are rigid plates at both ends of the battery stack, applying pressure to maintain the stack's seal. End plates 11 are made of aluminum alloy, titanium alloy, or stainless steel. Cathode insulating plate 16 and anode insulating plate 19 are located inside end plates 11, insulating and guiding electrolyte flow to prevent current leakage to external structures. For example, cathode insulating plate 16 guides the flow of negative electrolyte, and anode insulating plate 19 guides the flow of positive electrolyte.

[0060] Both the anode current collector 18 and the cathode current collector 17 are copper plates. The anode current collector 18 is used to connect to the positive terminal of the power supply, and the cathode current collector 17 is used to connect to the negative terminal of the power supply.

[0061] like Figure 1 and Figure 2 As shown, this utility model also proposes a vanadium electrolyte valence state adjustment device. The vanadium electrolyte valence state adjustment device according to the embodiment of this utility model includes an electrolysis unit, a storage unit, and a valence state detection unit.

[0062] The electrolysis unit includes an electrolytic power supply 2 and an electrolytic stack 1. The electrolytic stack 1 has a positive electrode liquid inlet channel, a positive electrode liquid outlet channel, a negative electrode liquid inlet channel, and a negative electrode liquid outlet channel. The positive terminal of the electrolytic power supply 2 is connected to the anode current collector 18 of the electrolytic stack 1, and the negative terminal of the electrolytic power supply 2 is connected to the cathode current collector 17 of the electrolytic stack 1. For example, the electrolytic power supply 2 is a DC power supply, with an output current of 0-500A and an output voltage of 0-300V.

[0063] The electrolyte storage section includes a positive electrode electrolyte tank 3 and a negative electrode electrolyte tank 4. Positive electrode electrolyte tank 3 stores the positive electrode electrolyte, and negative electrode electrolyte tank 4 stores the negative electrode electrolyte. The outlet of positive electrode electrolyte tank 3 is connected to the inlet of the positive electrode electrolyte inlet channel via a first pipe 31, and the outlet of the positive electrode electrolyte outlet channel is connected to the inlet of positive electrode electrolyte tank 3 via a second pipe 32. The outlet of negative electrode electrolyte tank 4 is connected to the inlet of the negative electrode electrolyte inlet channel via a third pipe 41, and the outlet of the negative electrode electrolyte outlet channel is connected to the inlet of negative electrode electrolyte tank 4 via a fourth pipe 42.

[0064] Specifically, the negative electrode electrolyte is a vanadium electrolyte, and the negative electrode liquid storage tank 4 is equipped with a stirring device 48 to ensure the uniformity of the liquid (vanadium electrolyte) in the negative electrode liquid storage tank 4. For example, the stirring device 48 includes a stirring motor and a stirring paddle. The power of the stirring motor is selected according to the actual size of the storage tank, and the stirring paddle is made of plastic-lined metal.

[0065] The bottom of the positive electrode liquid storage tank 3 is provided with a positive electrode liquid drain port 37, and the negative electrode liquid storage tank 4 is provided with a negative electrode drain port 47, so as to drain the electrolyte.

[0066] The positive electrode liquid storage tank 3 can be made of metal or non-metal, while the negative electrode liquid storage tank 4 can be made of plastic. For example, the negative electrode liquid storage tank 4 can be made of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE) or other plastics, or it can be a plastic-lined metal tank.

[0067] The valence state detection unit is used to detect the valence state of the negative electrode electrolyte discharged from negative electrode liquid storage tank 4. Specifically, it detects the valence state of the vanadium electrolyte discharged from negative electrode liquid storage tank 4. The valence state of the vanadium electrolyte can be adjusted chemically, using a chemical reducing agent, or electrochemically, using electrons as a reducing agent. Electrochemical reduction requires no external reagents, resulting in higher electrolyte purity. It can reduce tetravalent and pentavalent vanadium electrolytes to 3.5 valence to meet the requirements of all-vanadium redox flow batteries.

[0068] like Figure 2 As shown, in some embodiments, the valence state detection unit includes a sampling pipeline 5 and a detection device 51. The two ends of the sampling pipeline 5 are connected to a third pipeline 41 and the detection device 51, respectively. A sampling pump 5252 is provided on the sampling pipeline 5 to sample the negative electrode electrolyte discharged from the negative electrode liquid storage tank 4 at first preset time intervals. Specifically, the detection device 51 includes a flow cell and an ultraviolet spectrophotometer. The flow cell and the ultraviolet spectrophotometer are used together to detect the absorbance of the vanadium electrolyte.

[0069] In some embodiments, the optical path length of the flow cell is greater than or equal to 0.1 mm and less than or equal to 0.2 mm. After the vanadium electrolyte obtained by the injection pump 52 is introduced into the flow cell, the flow cell is placed in an ultraviolet spectrophotometer, and then the valence state of the vanadium electrolyte is obtained by measuring the absorbance of the vanadium electrolyte.

[0070] Alternatively, in some embodiments, the optical path length of the flow cell is greater than or equal to 10 mm and less than or equal to 20 mm. A second preset volume of vanadium electrolyte obtained by the sample pump 52 is mixed with a third preset volume of pure water in a mixing chamber and then introduced into the flow cell. The flow cell is then placed in an ultraviolet spectrophotometer, and the valence state of the vanadium electrolyte is obtained by measuring its absorbance. The ratio of the second preset volume to the third preset volume is 1:(10-100). That is, the volume of the mixed pure water is 10 times (100 times) the volume of the sampled vanadium electrolyte.

[0071] In some embodiments, the first preset time is greater than or equal to 0.1 seconds and less than or equal to 300 seconds. For example, the negative electrode electrolyte discharged from the negative electrode liquid storage tank 4 is sampled every 60 seconds.

[0072] In some embodiments, filters are provided at one end of the first pipeline 31 near the positive electrode liquid inlet channel and at one end of the third pipeline 41 near the negative electrode liquid inlet channel. Specifically, precision filters are provided on the first pipeline 31 and the third pipeline 41 near the inlet of the electrolytic cell stack to filter insoluble substances and impurities in the system.

[0073] In some embodiments, the electrolysis unit further includes a voltage monitor connected to a plurality of tabs on the electrolytic stack 1 to detect the voltage of each electrolytic cell group in the electrolytic stack 1. Specifically, tabs are provided on the cathode plate 12, anode plate 13, and bipolar plate 15. The voltage monitor is connected to the plurality of tabs to detect the voltage of each electrolytic cell group in the electrolytic stack 1 and transmit it to the control system.

[0074] In some embodiments, both the positive electrode liquid storage tank 3 and the negative electrode liquid storage tank 4 are equipped with temperature regulating devices. Specifically, the temperature regulating device is a circulating water device, which can exchange heat with the electrolyte in the positive electrode liquid storage tank 3 and the negative electrode liquid storage tank 4 in order to control the temperature of the electrolyte in the positive electrode liquid storage tank 3 and the negative electrode liquid storage tank 4.

[0075] In some embodiments, the positive electrode liquid storage tank 3 is equipped with a positive electrode liquid storage tank level gauge 33, and the negative electrode liquid storage tank 4 is equipped with a negative electrode liquid storage tank level gauge 43. Specifically, both the positive electrode liquid storage tank level gauge 33 and the negative electrode liquid storage tank 4 are used to measure the liquid level and feed it back to the control system. Specifically, when the positive electrode liquid storage tank level gauge 33 detects that the liquid level in the positive electrode liquid storage tank 3 is lower than the low liquid level, the automatic control system controls the liquid tank inlet valve to open, injecting pure water into the positive electrode liquid storage tank 3. When the high liquid level is reached, the inlet valve closes. Similarly, tetravalent vanadium solution, pentavalent vanadium solution, or other high-valence electrolytes that require adjustment are injected into the negative electrode liquid storage tank 4. When the high liquid level is reached, the inlet valve closes.

[0076] like Figure 2 As shown, at least one of the first pipeline 31 and the second pipeline 32 is equipped with a positive electrode circulation pump 34, and at least one of the third pipeline 41 and the fourth pipeline 42 is equipped with a negative electrode circulation pump 4, in order to transport electrolyte. For example, the first pipeline 31 is equipped with a positive electrode circulation pump 34, and the third pipeline 41 is equipped with a negative electrode circulation pump 4. The positive electrode circulation pump 34 and the negative electrode circulation pump 4 are acid and alkali resistant electromagnetic pumps, diaphragm pumps, or centrifugal pumps, etc.

[0077] Positive temperature sensor 35 and positive pressure sensor 36 are installed on the first pipeline 31 and the second pipeline 32, and negative temperature sensor 45 and negative pressure sensor 46 are installed on the third pipeline 41 and the fourth pipeline 42. Specifically, temperature sensors and pressure sensors are installed in the delivery pipelines to detect the inlet and outlet temperatures and pressures of the electrolytic cell stack 1, so as to provide feedback to the control system.

[0078] The vanadium electrolyte valence state adjustment device according to this utility model includes the following steps during use:

[0079] S1. Water is introduced into the positive electrode liquid storage tank 3 as the positive electrode electrolyte, and vanadium electrolyte with a valence state greater than or equal to tetravalent is introduced into the negative electrode liquid storage tank 4 as the negative electrode electrolyte.

[0080] S2. Continuously circulate the positive and negative electrolytes into the electrolytic cell stack 1 for a fourth preset time. Specifically, the fourth preset time is greater than or equal to 5 minutes and less than or equal to 30 minutes. The positive electrode circulation pump 34 and the negative electrode circulation pump 44 are turned on, pumping the positive electrolyte from the positive electrode storage tank 3 and the negative electrolyte from the negative electrode storage tank 4 into the electrolytic cell stack 1, respectively, circulating for 5-30 minutes to fill the electrolytic cell assembly with electrolyte and ensure full contact between the electrodes and the electrolyte.

[0081] S3. The temperature and pressure of the positive electrolyte in the first pipeline 31 and the second pipeline 32 are detected, as are the temperature and pressure of the negative electrolyte in the third pipeline 41 and the third pipeline 42. The valence state of the negative electrolyte in the third pipeline 41 is also detected. Specifically, the temperature and pressure of the electrolyte are detected using a positive electrode temperature sensor 35, a positive electrode pressure sensor 36, a negative electrode temperature sensor 45, and a negative electrode pressure sensor 46. The valence state detection unit is used to detect the valence state of the negative electrolyte discharged from the negative electrode liquid storage tank 4. After the cycle is completed, the control device automatically records the electrolyte valence state detection results.

[0082] S4. Control the temperature of the positive electrolyte in the positive electrode liquid storage tank 3 and the negative electrolyte in the negative electrode liquid storage tank 4 between 10°C and 50°C. Specifically, control the temperature of the positive electrolyte in the positive electrode liquid storage tank 3 and the negative electrolyte in the negative electrode liquid storage tank 4 between 25°C and 35°C. This is to reduce the failure of components in the electrolytic cell stack 1, improve reaction efficiency, and reduce the tendency of electrolyte to crystallize. For example, control the temperature of the positive electrolyte in the positive electrode liquid storage tank 3 and the negative electrolyte in the negative electrode liquid storage tank 4 at 30°C.

[0083] S5. Turn on the electrolysis power supply 2 and gradually increase the electrolysis current value until the current density reaches the fifth preset value. Specifically, the fifth preset value is greater than or equal to 50 mA / cm². 2 And less than or equal to 300 mA / cm 2 The current is determined based on the electrode area of ​​the electrolytic cell; current = current density * effective electrode plate area.

[0084] In some embodiments, the fifth preset value is greater than or equal to 100 mA / cm 2 And less than or equal to 200 mA / cm 2 When the current density is greater than or equal to 100 mA / cm 2 And less than or equal to 200 mA / cm 2 This can improve the stability of current operation and increase current efficiency.

[0085] S6. When the valence state of the negative electrode electrolyte discharged from the negative electrode liquid storage tank 4 reaches 3.5, electrolysis is stopped. Specifically, in step S6, when the valence state of the negative electrode electrolyte discharged from the negative electrode liquid storage tank 4 reaches 3.6, the current density is reduced to a sixth preset value. The sixth preset value is greater than or equal to 20 mA / cm². 2 And less than or equal to 50 mA / cm 2 This reduces energy consumption.

[0086] In one specific embodiment, the vanadium electrolyte valence state adjustment device according to this invention is used to reduce a tetravalent vanadium oxysulfate solution to a 3.5-valent vanadium electrolyte, wherein the vanadium oxysulfate concentration is 1.7 mol / L. The production capacity is 2m³ / L.3 / d.

[0087] The system uses an electrolytic stack 1 with an effective electrolytic area of ​​50cm x 50cm. Electrolytic stack 1 consists of 10 electrolytic cells connected in series, with a current density of 100mA / cm². 2 The end plate 11 is made of aluminum alloy with a thickness of 2cm. The current collectors (cathode current collector 17 and anode current collector 18) are made of pure copper plates. The bipolar plates 15 are made of pure titanium plates (TA1 material) and flexible graphite composite plates. The electrolysis power supply 2 is a 0-300A DC power supply with a power of 10kW.

[0088] The valence state detection unit consists of an ultraviolet spectrophotometer and a 0.2mm flow cell, with a detection frequency of once every 60 seconds. The positive electrode liquid storage tank has a volume of 1m³. 3 Add pure water to 1m 3 No additional sulfuric acid is required; negative electrode liquid storage tank 4, volume 2m³ 3 Add 2m of electrolyte 3 .

[0089] Turn on the circulating water to adjust the temperature of the positive and negative electrode solutions to 30℃, and simultaneously turn on the circulating pumps (positive electrode circulating pump 34 and negative electrode circulating pump 44) for 30 minutes.

[0090] Gradually increase the current to 250A to start electrolysis. During the electrolysis process, continuously sample and monitor the concentration of the electrolyte discharged from the negative electrode liquid storage tank 4. When the concentration of tetravalent vanadium discharged from the negative electrode liquid storage tank 4 is 55% of the initial concentration, adjust the current to 100A and continue electrolysis until the concentration of tetravalent vanadium is 50% of the initial concentration, then stop electrolysis.

[0091] The electrolysis device was used for a total test of 500 hours. The voltage was stable. The current efficiency fluctuated between 90% and 95% during the electrolysis process. The valence state of the generated electrolyte was stable at 3.5 ± 0.1. The quality of the electrolyte product was stable, and no additional impurities were introduced as tested.

[0092] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0093] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0094] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0095] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0096] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0097] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An electrolytic cell stack, characterized in that, include: Two end plates; and An electrolytic cell assembly, wherein two end plates are located on both sides of the electrolytic cell assembly in a first direction, the electrolytic cell assembly includes a cathode plate made of carbon material; An anode plate, said anode plate being made of a metallic material; An ion exchange membrane is provided, wherein the cathode plate, the ion exchange membrane, and the anode plate are arranged sequentially along the first direction. The cathode plate and the ion exchange membrane define a cathode electrolyte chamber, and the anode plate and the ion exchange membrane define an anode electrolyte chamber. The electrolytic cell assembly has a positive electrode liquid inlet channel, a positive electrode liquid outlet channel, a negative electrode liquid inlet channel, and a negative electrode liquid outlet channel. The positive electrode liquid inlet channel and the positive electrode liquid outlet channel are connected to the anode electrolyte chamber, and the negative electrode liquid inlet channel and the negative electrode liquid outlet channel are connected to the cathode electrolyte chamber.

2. The electrolytic cell stack according to claim 1, characterized in that, There are multiple electrolytic cell groups, and the multiple electrolytic cell groups are stacked sequentially along the first direction; The electrolytic stack includes bipolar plates, the anode side of which is made of a metallic material and the cathode side of which is made of a carbon material. The anode side and the cathode side of the bipolar plates are respectively arranged adjacent to the anode plate and the cathode plate in the first direction.

3. The electrolytic cell stack according to claim 2, characterized in that, Carbon material is hot-pressed onto the anode plate to form the bipolar plate; Alternatively, the cathode plate and the anode plate can be attached and fixed together in the first direction to form the bipolar plate.

4. The electrolytic cell stack according to claim 2, characterized in that, The electrolytic stack further includes a cathode insulating plate, a cathode current collector, an anode current collector, and an anode insulating plate. One of the two end plates, the cathode insulating plate, the cathode current collector, the plurality of electrolytic cell groups, the anode current collector, the anode insulating plate, and the other of the two end plates are arranged sequentially in the first direction. Each of the electrolytic cells further includes a flow frame, which is provided between the ion exchange membrane and each of the anode plate and the cathode plate.

5. The electrolytic cell stack according to claim 4, characterized in that, The end plate is made of aluminum alloy, titanium alloy or stainless steel. Both the anode current collector and the cathode current collector are copper plates; The anode plate is made of stainless steel, titanium, or titanium alloy. The cathode plate is made of flexible graphite material.

6. A bipolar plate, characterized in that, The bipolar plate includes an anode plate and a cathode plate fixed together in a first direction, the thickness direction of the anode plate and the cathode plate being the first direction, the anode plate being made of a metallic material, the cathode plate being made of a carbon material, the anode plate constituting the anode side of the bipolar plate, and the cathode plate constituting the cathode side of the bipolar plate.

7. A vanadium electrolyte valence state adjustment device, characterized in that, include An electrolysis unit, comprising an electrolysis power supply and an electrolysis stack, wherein the electrolysis stack is the electrolysis stack according to claim 4, the electrolysis stack having a positive electrode liquid inlet channel, a positive electrode liquid outlet channel, a negative electrode liquid inlet channel and a negative electrode liquid outlet channel, the positive electrode of the electrolysis power supply being connected to the anode current collector of the electrolysis stack, and the negative electrode of the electrolysis power supply being connected to the cathode current collector of the electrolysis stack; The liquid storage section includes a positive electrode liquid storage tank and a negative electrode liquid storage tank. The positive electrode liquid storage tank is used to store positive electrode electrolyte, and the negative electrode liquid storage tank is used to store negative electrode electrolyte. The outlet of the positive electrode liquid storage tank is connected to the inlet of the positive electrode liquid inlet channel through a first pipeline, the outlet of the positive electrode liquid outlet channel is connected to the inlet of the positive electrode liquid storage tank through a second pipeline, the outlet of the negative electrode liquid storage tank is connected to the inlet of the negative electrode liquid inlet channel through a third pipeline, and the outlet of the negative electrode liquid outlet channel is connected to the inlet of the negative electrode liquid storage tank through a fourth pipeline. The valence state detection unit is used to detect the valence state of the negative electrode electrolyte discharged from the negative electrode liquid storage tank.

8. The vanadium electrolyte valence state adjustment device according to claim 7, characterized in that, The valence state detection unit includes a sampling pipeline and a detection device. The two ends of the sampling pipeline are connected to the third pipeline and the detection device, respectively. The sampling pipeline is equipped with a sampling pump, which samples the negative electrode electrolyte discharged from the negative electrode liquid storage tank at first preset time intervals.

9. The vanadium electrolyte valence state adjustment device according to claim 8, characterized in that, The negative electrode electrolyte is a vanadium electrolyte. The negative electrode liquid storage tank is equipped with a stirring device. The first pipeline near the positive electrode liquid inlet channel and the third pipeline near the negative electrode liquid inlet channel are both equipped with filters. The first preset time is greater than or equal to 0.1 seconds and less than or equal to 300 seconds; The detection device includes a flow cell and an ultraviolet spectrophotometer; The optical path length of the flow cell is greater than or equal to 0.1 mm and less than or equal to 0.2 mm. After the vanadium electrolyte obtained by the injection pump is introduced into the flow cell, the flow cell is placed in the ultraviolet spectrophotometer, and then the valence state of the vanadium electrolyte is obtained by measuring the absorbance of the vanadium electrolyte. Alternatively, the optical path length of the flow cell is greater than or equal to 10 mm and less than or equal to 20 mm. After mixing the second preset volume of vanadium electrolyte obtained by the injection pump with the third preset volume of pure water in the mixing chamber, the mixture is introduced into the flow cell. Then, the flow cell is placed in the ultraviolet spectrophotometer, and the valence state of the vanadium electrolyte is obtained by measuring the absorbance of the vanadium electrolyte. The ratio of the second preset volume to the third preset volume is 1:(10-100).

10. The vanadium electrolyte valence state adjustment device according to claim 7, characterized in that, The electrolysis unit also includes a voltage monitor, which is connected to multiple tabs on the electrolytic stack to detect the voltage of each electrolytic cell group in the electrolytic stack; Both the positive electrode liquid storage tank and the negative electrode liquid storage tank are equipped with temperature regulation devices; The positive electrode liquid storage tank is equipped with a positive electrode liquid storage tank level gauge, and the negative electrode liquid storage tank is equipped with a negative electrode liquid storage tank level gauge; At least one of the first pipeline and the second pipeline is equipped with a positive circulation pump; Both the first pipeline and the second pipeline are equipped with a positive temperature sensor and a positive pressure sensor; At least one of the third pipeline and the fourth pipeline is equipped with a negative circulation pump; Both the third and fourth pipelines are equipped with negative temperature sensors and negative pressure sensors.

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