Electrolysis galvanic pile, bipolar plate and vanadium electrolyte valence state adjusting device

Abstract

The invention provides an electrolysis galvanic pile, a bipolar plate and a vanadium electrolyte valence state adjusting device. The electrolysis galvanic pile comprises two end plates and an electrolytic cell set, the two end plates are located on the two sides of the electrolytic cell set in the first direction, the electrolytic cell set comprises a cathode plate, and the cathode plate is made of a carbon material; the anode plate is made of a metal material; the ion exchange membrane, the cathode plate, the ion exchange membrane and the anode plate are sequentially arranged in the first direction, a cathode electrolyte chamber is defined by the cathode plate and the ion exchange membrane, an anode electrolyte chamber is defined by the anode plate and the ion exchange membrane, and the electrolytic cell set is provided 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. The positive electrode liquid inlet channel and the positive electrode liquid outlet channel are communicated with the anolyte chamber, and the negative electrode liquid inlet channel and the negative electrode liquid outlet channel are communicated with the catholyte chamber. The electrolytic galvanic pile is long in service life, good in conductivity, low in cost and resistant to corrosion.

Description

Technical Field

[0001] The present invention relates to the technical field of all-vanadium liquid flow batteries, and in particular to an electrolytic cell stack, a bipolar plate and a vanadium electrolyte valence state adjustment device. Background Art

[0002] All-vanadium flow batteries utilize a circulating vanadium solution as the energy storage medium for both the positive and negative electrodes. Vanadium electrolyte is a key material in all-vanadium flow battery systems. During initial installation, to ensure charge balance during operation, the anode and cathode storage tanks are typically filled with equal amounts of 3.5-valent vanadium electrolyte (i.e., 1 / 2 each of trivalent and tetravalent vanadium). The electrolysis method is suitable for producing 3.5-valent electrolytes. The bipolar plates of an electrolytic cell are typically a single, single electrode plate. The two sides of the bipolar plate are the anode solution and the cathode solution, respectively. Using a metal anode plate is prone to acidic chemical corrosion; using a coated metal electrode is expensive; and using non-metallic carbon materials, due to their oxidation at high voltages, limits the voltage of the electrolytic cell, thus affecting operation and increasing the failure rate. On the cathode side, it is also an acidic medium, but the voltage is lower, and there is a hydrogen absorption side reaction. If a metal bipolar plate is used, hydrogen embrittlement is likely to occur, and sulfuric acid will slowly dissolve the metal and cause corrosion, which not only reduces the service life of the electrode plate, but also pollutes the electrolyte. If an oxide coating is added to the surface of the electrode, the hydrogen absorption side reaction will be aggravated, reducing the current efficiency. In summary, if the bipolar plate is made of metal material, the corrosion problem is difficult to solve. If non-metallic materials are used, the mechanical strength is low and the anode is prone to oxidation. In addition, the electrochemical valence adjustment system of the vanadium liquid flow battery in the related art usually uses the electrolyte of the specified valence state as the electrolysis end point, and the detection of the end point often relies on manual sampling and detection, which increases the operation and maintenance costs. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, embodiments of the present invention provide an electrolytic cell stack, a bipolar plate, and a vanadium electrolyte valence adjustment device.

[0004] The electrolytic stack according to an embodiment of the present invention includes:

[0005] two end plates; and

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

[0007] an anode plate made of a metal material;

[0008] An ion exchange membrane, the cathode plate, the ion exchange membrane and the anode plate are arranged in sequence 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, wherein the electrolytic cell group 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 in communication with the anode electrolyte chamber, and the negative electrode liquid inlet channel and the negative electrode liquid outlet channel are in communication with the cathode electrolyte chamber.

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

[0010] The electrolysis stack includes a bipolar plate, the anode side of the bipolar plate is made of a metal material, the cathode side of the bipolar plate is made of a carbon material, and the anode side and the cathode side of the bipolar plate respectively constitute the anode plate and the cathode plate adjacent to each other in the first direction.

[0011] In some embodiments, hot pressing a carbon material onto the anode plate to form the bipolar plate;

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

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

[0014] Each of the electrolytic cell groups further includes a liquid flow frame, and the liquid flow frame 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] The anode current collecting plate and the cathode current collecting plate are both 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] The present invention 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 metal material, and the cathode plate is made of 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] The present invention also proposes a vanadium electrolyte valence adjustment device, comprising

[0021] An electrolysis unit, the electrolysis unit comprising an electrolysis power supply and an electrolysis stack, the electrolysis stack being the electrolysis stack described above, the electrolysis stack having a cathode liquid inlet channel, a cathode liquid outlet channel, a cathode liquid inlet channel, and a cathode liquid outlet channel, the positive electrode of the electrolysis power supply being connected to the anode current collecting plate of the electrolysis stack, and the negative electrode of the electrolysis power supply being connected to the cathode current collecting plate of the electrolysis stack;

[0022] A liquid storage portion, the liquid storage portion comprising a cathode liquid storage tank and a cathode liquid storage tank, the cathode liquid storage tank being used to store a cathode electrolyte, the cathode liquid storage tank being used to store a cathode electrolyte, the cathode liquid storage tank having an outlet connected to the inlet of the cathode liquid inlet channel via a first pipeline, the cathode liquid discharge channel having an outlet connected to the inlet of the cathode liquid storage tank via a second pipeline, the cathode liquid storage tank having an outlet connected to the inlet of the cathode liquid inlet channel via a third pipeline, and the cathode liquid discharge channel having an outlet connected to the inlet of the cathode liquid storage tank via 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, and a sampling pump is provided on the sampling pipeline to sample the negative electrode electrolyte discharged from the negative electrode liquid storage tank at every first preset time interval.

[0025] In some embodiments, the negative electrode electrolyte is a vanadium electrolyte, a stirring device is provided in the negative electrode liquid storage tank, and a filter is provided at one end of the first pipeline adjacent to the positive electrode liquid inlet channel and at one 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 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 passed into the flow cell, the flow cell is placed in the ultraviolet spectrophotometer, and then the valence state of the vanadium electrolyte is obtained according to the absorbance of the vanadium electrolyte;

[0029] Alternatively, the optical path of the circulation cell is greater than or equal to 10 mm and less than or equal to 20 mm, the second preset volume of vanadium electrolyte obtained by the sampling pump and the third preset volume of pure water are mixed in the mixing chamber and then passed into the circulation cell, and then the circulation cell is placed in the ultraviolet spectrophotometer, and then the valence state of the vanadium electrolyte is obtained based on the absorbance of the vanadium electrolyte, wherein 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 electrolysis stack so as to detect the voltage of each electrolysis cell group of the electrolysis stack;

[0031] The cathode liquid storage tank and the cathode liquid storage tank are both provided with a temperature regulating device;

[0032] The cathode liquid storage tank is provided with a cathode liquid storage tank level gauge, and the cathode liquid storage tank is provided with a cathode liquid storage tank level gauge;

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

[0034] The first pipeline and the second pipeline are both provided with a cathode temperature sensor and a cathode pressure sensor;

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

[0036] The third pipeline and the fourth pipeline are both provided with a cathode temperature sensor and a cathode pressure sensor.

[0037] In some embodiments, the vanadium electrolyte valence adjustment device comprises the following steps when used:

[0038] S1, passing water into the cathode liquid storage tank as the cathode electrolyte, and passing a vanadium electrolyte with a valence greater than or equal to four into the cathode liquid storage tank as the cathode electrolyte;

[0039] S2, continuously passing the positive electrode electrolyte and the negative electrode electrolyte into the electrolytic stack for a fourth preset time;

[0040] S3, detecting the temperature and pressure of the positive electrode electrolyte in the first pipeline and the second pipeline, detecting the temperature and pressure of the negative electrode electrolyte in the third pipeline and the third pipeline, and detecting the valence state of the negative electrode electrolyte in the third pipeline;

[0041] S4, controlling the temperature of the cathode electrolyte in the cathode liquid storage tank and the anode electrolyte in the anode liquid storage tank to between 10° C. and 50° C.;

[0042] S5, turning on the electrolysis power supply and gradually increasing the electrolysis current value so that the current density reaches a fifth preset value;

[0043] S6. When the valence of the negative electrode electrolyte discharged from the negative electrode liquid storage tank reaches 3.5, stop electrolysis.

[0044] In some embodiments, the temperature of the cathode electrolyte in the cathode liquid storage tank and the anode electrolyte in the anode liquid storage tank is controlled between 25° C. and 35° C.;

[0045] The fourth preset time is greater than or equal to 5 minutes and less than or equal to 30 minutes;

[0046] The fifth preset value is greater than or equal to 50 mA / cm 2 And less than or equal to 300mA / cm 2 ;

[0047] In step S6, when the valence of the negative electrode electrolyte discharged from the negative electrode solution storage tank reaches 3.6, the current density is reduced so that the current density reaches a sixth preset value.

[0048] In some embodiments, the fifth preset value is greater than or equal to 100 mA / cm 2 And less than or equal to 200mA / cm 2 ;

[0049] The sixth preset value is greater than or equal to 20 mA / cm 2 And less than or equal to 50mA / cm 2 .

[0050] The present invention has the following beneficial effects: the cathode plate of the electrolytic stack according to the embodiment of the present invention is made of carbon material, which makes the cathode plate corrosion-resistant. After the vanadium electrolyte enters the cathode electrolyte chamber, the corrosion effect on the cathode plate is minimal, thereby extending the service life of the electrolytic stack. The anode plate is made of metal material, which has good conductivity and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a schematic diagram of an electrolytic cell stack according to an embodiment of the present invention.

[0052] Figure 2Schematic diagram of a vanadium electrolyte valence adjustment device according to an embodiment of the present invention.

[0053] Reference numerals:

[0054] 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 collecting plate, 18. Anode current collecting plate, 19. Anode insulating plate, 101. Liquid flow frame;

[0055] 2. Electrolysis power supply;

[0056] 3. Cathode liquid storage tank, 31. First pipeline, 32. Second pipeline, 33. Cathode liquid storage tank level gauge, 34. Cathode circulation pump, 35. Cathode temperature sensor, 36. Cathode pressure sensor, 37. Cathode liquid drain port;

[0057] 4. Anode liquid storage tank, 41. Third pipeline, 42. Fourth pipeline, 43. Anode liquid storage tank level gauge, 44. Anode circulation pump, 45. Anode temperature sensor, 46. Anode pressure sensor, 47. Anode drain port, 48. Stirring device;

[0058] 5. Sampling pipeline, 51. Detection device, 52. Sampling pump. DETAILED DESCRIPTION

[0059] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0060] The following describes an electrolytic cell stack 1 according to an embodiment of the present invention with reference to the accompanying drawings. 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, and the two end plates 11 are located on both sides of the electrolytic cell group in a first direction.

[0061] 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 a carbon material, and the anode plate 13 is made of a metal material. The cathode plate 12, the ion exchange membrane 14, and the anode plate 13 are arranged in sequence 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 anolyte chamber.

[0062] The electrolytic cell assembly comprises a cathode liquid inlet channel, a cathode liquid outlet channel, a cathode liquid inlet channel, and a cathode liquid outlet channel. The cathode liquid inlet channel and the cathode liquid outlet channel are connected to the anolyte chamber, while the cathode liquid inlet channel and the cathode liquid outlet channel are connected to the cathode liquid chamber. Specifically, the cathode electrolyte can be introduced into the anolyte chamber through the protective cathode liquid inlet channel, where it undergoes electrolysis and oxidation reaction, and then be discharged from the protective cathode liquid outlet channel. The cathode electrolyte can be introduced into the cathode liquid chamber through the protective cathode liquid inlet channel, where it undergoes electrolysis and reduction reaction, and then be discharged from the protective cathode liquid outlet channel.

[0063] The anode plate 13 provides a reaction surface to promote the oxidation reaction of the active material in the positive electrolyte. The anode plate 13 promotes the reduction reaction of the negative electrolyte. The ion exchange membrane 14 selectively transmits ions (such as H + ), preventing the positive and negative electrolytes from mixing directly.

[0064] The cathode plate 12 of the electrolytic stack 1 according to an embodiment of the present invention is made of a carbon material, which makes the cathode plate 12 corrosion-resistant. After the vanadium electrolyte enters the cathode electrolyte chamber, the corrosion effect on the cathode plate 12 is minimal, thereby increasing the service life of the electrolytic stack 1. The anode plate 13 is made of a metal material with good conductivity and low cost.

[0065] In some embodiments, there are multiple electrolytic cell groups, which are stacked in sequence along a first direction, and the cathode liquid inlet channel, cathode liquid outlet channel, cathode liquid inlet channel, and cathode liquid outlet channel run through the multiple electrolytic cell groups.

[0066] The present invention also provides a bipolar plate 15. According to an embodiment of the present invention, the bipolar plate 15 includes an anode plate 13 and a cathode plate 12 fixed together in a first direction. The thickness directions of the anode plate 13 and the cathode plate 12 are both in the first direction. The anode plate 13 is made of a metal 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.

[0067] In some embodiments, the electrolytic stack 1 includes a bipolar plate 15, wherein the anode side of the bipolar plate 15 is made of a metal material, and the cathode side of the bipolar plate 15 is made of a carbon material. The anode side and cathode side of the bipolar plate 15 respectively constitute adjacent anode plates 13 and cathode plates 12 in a first direction. Specifically, the bipolar plate 15 is respectively composed of two layers of material in the first direction, including a metal layer made of a metal material and a carbon layer made of a carbon material. The metal layer constitutes the anode side of the bipolar plate 15, and the carbon layer constitutes the cathode side of the bipolar plate 15. The anode side of the bipolar plate 15 constitutes the anode plate 13 and defines an anolyte chamber with the ion exchange membrane 14. The cathode side of the bipolar plate 15 constitutes the cathode plate 12 and defines a catholyte chamber with the ion exchange membrane 14.

[0068] In some embodiments, the anode plate 13 is made of stainless steel, titanium, or a titanium alloy. The cathode plate 12 is made of flexible graphite. Specifically, the anode side of the bipolar plate 15 is made of stainless steel, titanium, or a titanium alloy, while the cathode side of the bipolar plate 15 is made of flexible graphite. Controlling machining precision allows for sealing and lamination, resulting in high strength and corrosion resistance. The flexible graphite plate is self-sealing, providing excellent sealing performance for the electrolytic stack 1.

[0069] In some embodiments, a carbon material is hot-pressed onto the anode plate 13 to form the bipolar plate 15. Alternatively, the cathode plate 12 and the anode plate 13 are attached and fixed together in a first direction to form the bipolar plate 15. Specifically, the bipolar plate 15 can be formed by hot-pressing the carbon material onto the anode plate 13 so that the anode plate 13 is integrally formed. Alternatively, the bipolar plate 15 can be formed by mechanically joining the anode plate 13 and the cathode plate 12.

[0070] In some embodiments, the electrolytic stack 1 further includes a cathode insulating plate 16, a cathode current collecting plate 17, an anode current collecting plate 18, and an anode insulating plate 19. One of the two end plates 11, the cathode insulating plate 16, the cathode current collecting plate 17, a plurality of electrolytic cell groups, the anode collecting plate 18, the anode insulating plate 19, and the other of the two end plates 11 are sequentially arranged in the first direction.

[0071] Each electrolytic cell assembly also includes a liquid flow frame 101, which is positioned between the ion exchange membrane 14 and each of the anode plate 13 and cathode plate 12. Seals are provided between the liquid flow frame 101, the ion exchange membrane 14, and adjacent pairs of the anode plate 13 and cathode plate 12. These seals prevent electrolyte leakage and ensure a tight seal between the layers. The liquid flow frame 101 is a framework for securing the ion exchange membrane 14. For example, the inner wall of the liquid flow frame 101, the ion exchange membrane 14, and the anode plate 13 define an anolyte chamber, while the inner wall of the liquid flow frame 101, the ion exchange membrane 14, and the cathode plate 12 define a catholyte chamber. The liquid flow frame 101 includes titanium mesh and titanium fiber felt arranged sequentially within the anolyte chamber to conduct electrons, facilitate gas diffusion, and facilitate fluid flow. A graphite felt is also positioned within the catholyte chamber to increase reaction sites and facilitate fluid flow.

[0072] Specifically, the end plates 11 are rigid plates at both ends of the battery stack, applying pressure to maintain the stack's seal. They are made of aluminum alloy, titanium alloy, or stainless steel. The cathode insulator 16 and anode insulator 19 are located inside the end plates 11. These insulators insulate and guide the flow of electrolyte, preventing current leakage to external structures. For example, the cathode insulator 16 guides the flow of negative electrolyte, while the anode insulator 19 guides the flow of positive electrolyte.

[0073] The anode current collecting plate 18 and the cathode current collecting plate 17 are both copper plates. The anode current collecting plate 18 is used to connect to the positive electrode of the power supply, and the cathode current collecting plate 17 is used to connect to the negative electrode of the power supply.

[0074] like Figure 1 and Figure 2 As shown, the present invention further proposes a vanadium electrolyte valence adjustment device. The vanadium electrolyte valence adjustment device according to an embodiment of the present invention includes an electrolysis part, a liquid storage part, and a valence detection part.

[0075] The electrolysis section includes an electrolysis power supply 2 and an electrolysis stack 1. The electrolysis stack 1 has a cathode liquid inlet channel, a cathode liquid outlet channel, a cathode liquid inlet channel, and a cathode liquid outlet channel. The positive electrode of the electrolysis power supply 2 is connected to the anode current collecting plate 18 of the electrolysis stack 1, and the negative electrode of the electrolysis power supply 2 is connected to the cathode current collecting plate 17 of the electrolysis stack 1. For example, the electrolysis power supply 2 is a DC power supply, and the output current of the electrolysis power supply 2 is 0-500A and the output voltage of the electrolysis power supply 2 is 0-300V.

[0076] The liquid storage section includes a cathode liquid storage tank 3 and a cathode liquid storage tank 4. The cathode liquid storage tank 3 is used to store the cathode electrolyte, and the cathode liquid storage tank 4 is used to store the cathode electrolyte. The outlet of the cathode liquid storage tank 3 is connected to the inlet of the cathode liquid inlet channel via a first pipeline 31, and the outlet of the cathode liquid discharge channel is connected to the inlet of the cathode liquid storage tank 3 via a second pipeline 32. The outlet of the cathode liquid storage tank 4 is connected to the inlet of the cathode liquid inlet channel via a third pipeline 41, and the outlet of the cathode liquid discharge channel is connected to the inlet of the cathode liquid storage tank 4 via a fourth pipeline 42.

[0077] Specifically, the negative electrode electrolyte is a vanadium electrolyte, and a stirring device 48 is provided in the negative electrode liquid storage tank 4. The stirring device 48 ensures 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.

[0078] The bottom of the cathode liquid storage tank 3 is provided with a cathode liquid drain port 37 , and the cathode liquid storage tank 4 is provided with a cathode drain port 47 for draining the electrolyte.

[0079] The cathode liquid storage tank 3 can be made of metal or non-metal, and the cathode liquid storage tank 4 can be made of a plastic tank. For example, the cathode liquid storage tank 4 can be made of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), or other plastics, or a metal tank lined with plastic.

[0080] The valence detection unit is used to detect the valence of the cathode electrolyte discharged from the cathode liquid storage tank 4. Specifically, the valence detection unit detects the valence of the vanadium electrolyte discharged from the cathode liquid storage tank 4. The valence 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 and results in a higher purity electrolyte. It can reduce vanadium electrolytes with a valence of 4 or 5 to a valence of 3.5, sufficient for use in all-vanadium redox flow batteries.

[0081] like Figure 2 As shown, in some embodiments, the valence state detection unit includes a sampling line 5 and a detection device 51. The two ends of the sampling line 5 are respectively connected to the third line 41 and the detection device 51. The sampling line 5 is provided with a sampling pump 5252, which samples the negative electrode electrolyte discharged from the negative electrode liquid storage tank 4 at a first preset interval. Specifically, the detection device 51 includes a flow cell and an ultraviolet spectrophotometer, which are used in combination to detect the absorbance of the vanadium electrolyte.

[0082] In some embodiments, the optical path of the circulation 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 sampling pump 52 is passed into the circulation cell, the circulation cell is placed in an ultraviolet spectrophotometer, and then the valence state of the vanadium electrolyte is obtained based on the absorbance of the vanadium electrolyte.

[0083] Alternatively, in some embodiments, the optical path of the flow cell is greater than or equal to 10 mm and less than or equal to 20 mm. After the second preset volume of vanadium electrolyte obtained by the injection pump 52 and the third preset volume of pure water are mixed in the mixing chamber and passed into the flow cell, the flow cell is then placed in an ultraviolet spectrophotometer, and the valence state of the vanadium electrolyte is obtained based on the absorbance of the vanadium electrolyte. 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 to 100 times the volume of the sampled vanadium electrolyte.

[0084] 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 electrolyte discharged from the negative electrolyte storage tank 4 is sampled every 60 seconds.

[0085] In some embodiments, a filter is provided at one end of the first conduit 31 adjacent to the cathode liquid inlet channel and at one end of the third conduit 41 adjacent to the cathode liquid inlet channel. Specifically, precision filters are provided on the first conduit 31 and the third conduit 41 adjacent to the inlet of the electrolytic stack to filter insoluble matter and impurities in the system.

[0086] In some embodiments, the electrolysis section further includes a voltage monitor connected to multiple tabs on the electrolysis stack 1 to detect the voltage of each electrolysis cell group in the electrolysis stack 1. Specifically, tabs are provided on the cathode plate 12, the anode plate 13, and the bipolar plate 15. The voltage monitor is connected to the multiple tabs to detect the voltage of each electrolysis cell group in the electrolysis stack 1 and transmit the voltage to the control system.

[0087] In some embodiments, a temperature regulating device is provided in each of the cathode liquid storage tank 3 and the cathode liquid storage tank 4. Specifically, the temperature regulating device is a circulating water device that can exchange heat with the electrolyte in the cathode liquid storage tank 3 and the cathode liquid storage tank 4 to control the temperature of the electrolyte in the cathode liquid storage tank 3 and the cathode liquid storage tank 4.

[0088] In some embodiments, a positive electrode liquid tank level gauge 33 is provided on the positive electrode liquid tank 3, and a negative electrode liquid tank 4 level gauge 43 is provided on the negative electrode liquid tank 4. Specifically, the positive electrode liquid tank level gauge 33 and the negative electrode liquid tank 4 are both used to measure the liquid level and feed back to the control system. Specifically, when the positive electrode liquid tank level gauge 33 detects that the liquid level in the positive electrode liquid tank 3 is lower than the low liquid level, the automatic control system controls the liquid tank water inlet valve to open, and injects pure water into the positive electrode liquid tank 3. When the high liquid level is reached, the water inlet valve is closed. A tetravalent vanadium solution or a pentavalent vanadium solution or other high-valent electrolyte that needs to be adjusted is injected into the negative electrode liquid tank 4. When the high liquid level is reached, the liquid inlet valve is closed.

[0089] like Figure 2 As shown, at least one of the first and second pipelines 31 and 32 is provided with a positive electrode circulation pump 34, and at least one of the third and fourth pipelines 41 and 42 is provided with a negative electrode circulation pump 4 for transporting electrolyte. For example, the positive electrode circulation pump 34 is provided on the first pipeline 31, and the negative electrode circulation pump 4 is provided on the third pipeline 41. The positive electrode circulation pump 34 and the negative electrode circulation pump 4 are acid- and alkali-resistant electromagnetic pumps, diaphragm pumps, centrifugal pumps, etc.

[0090] A positive electrode temperature sensor 35 and a positive electrode pressure sensor 36 are provided on the first and second pipelines 31 and 32, respectively. A negative electrode temperature sensor 45 and a negative electrode pressure sensor 46 are provided on the third and fourth pipelines 41 and 42. Specifically, temperature sensors and pressure sensors are provided in the transport pipelines to detect the inlet and outlet temperatures and pressures of the electrolytic stack 1 for feedback to the control system.

[0091] The vanadium electrolyte valence adjustment device according to the present invention comprises the following steps when in use:

[0092] S1. Water is introduced into the cathode liquid storage tank 3 as the cathode electrolyte, and vanadium electrolyte with a valence greater than or equal to tetravalent is introduced into the cathode liquid storage tank 4 as the cathode electrolyte.

[0093] S2. Continue to flow 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 to pump the positive electrolyte in the positive electrode liquid storage tank 3 and the negative electrode electrolyte in the negative electrode liquid storage tank 4 into the electrolytic cell stack 1, respectively, and circulate for 5-30 minutes until the electrolytes fill the electrolytic cell stack and the electrodes and the electrolytes are in full contact.

[0094] S3. Detect the temperature and pressure of the positive electrode electrolyte in the first and second pipelines 31 and 32, detect the temperature and pressure of the negative electrode electrolyte in the third pipeline 41 and the negative electrode electrolyte in the third pipeline 41, and detect the valence state of the negative electrode electrolyte in the third pipeline 41. Specifically, the positive electrode temperature sensor 35, the positive electrode pressure sensor 36, the negative electrode temperature sensor 45, and the negative electrode pressure sensor 46 are used to detect the temperature and pressure of the electrolyte. 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 4. After the cycle is completed, the control device automatically records the electrolyte valence state detection results.

[0095] S4. Control the temperature of the positive electrolyte in the positive liquid storage tank 3 and the negative electrolyte in the negative liquid storage tank 4 to between 10°C and 50°C. Specifically, control the temperature of the positive electrolyte in the positive liquid storage tank 3 and the negative electrolyte in the negative liquid storage tank 4 to between 25°C and 35°C. This can reduce component failure of the electrolytic stack 1, improve reaction efficiency, and reduce the easy crystallization of the electrolyte. For example, control the temperature of the positive electrolyte in the positive liquid storage tank 3 and the negative electrolyte in the negative liquid storage tank 4 to 30°C.

[0096] S5, turn on the electrolysis power supply 2 and gradually increase the electrolysis current value so that the current density is the fifth preset value. Specifically, the fifth preset value is greater than or equal to 50mA / cm 2 And less than or equal to 300mA / cm 2 The current is determined by the electrode area of ​​the electrolytic cell, current = current density * electrode plate (effective) area.

[0097] In some embodiments, the fifth preset value is greater than or equal to 100 mA / cm 2 And less than or equal to 200mA / cm 2 , when the current density is greater than or equal to 100mA / cm 2 And less than or equal to 200mA / cm 2 , which can improve the current operation stability and improve the current efficiency.

[0098] S6. When the valence of the negative electrolyte discharged from the negative electrolyte storage tank 4 reaches 3.5, stop electrolysis. Specifically, in step S6, when the valence of the negative electrolyte discharged from the negative electrolyte storage tank 4 reaches 3.6, reduce the current density so that the current density is a sixth preset value. The sixth preset value is greater than or equal to 20 mA / cm 2 And less than or equal to 50mA / cm 2 Thus, energy loss can be reduced. When the valence of the negative electrode electrolyte discharged from the negative electrode liquid storage tank 4 reaches 3.5, the electrolysis is stopped and the electrolysis work is completed.

[0099] In a specific embodiment, the vanadium electrolyte valence state adjustment device according to the present invention is used to reduce the tetravalent vanadium oxysulfate solution to a 3.5-valent vanadium electrolyte, wherein the concentration of the vanadium oxysulfate is 1.7 mol / L. The production capacity is 2m 3 / d.

[0100] The effective electrolysis area of ​​the electrolytic stack 1 in the system used is 50cm*50cm. The electrolytic stack 1 is composed of 10 electrolytic cell groups connected in series, and the current density is 100mA / cm 2 The end plate 11 is made of aluminum alloy with a thickness of 2 cm, and the current collecting plates (cathode current collecting plate 17 and anode current collecting plate 18) are pure copper plates; the bipolar plate 15 is a pure titanium plate (TA1 material) and a flexible graphite composite plate, and the electrolytic power supply 2 is a 0-300A DC power supply with a power supply of 10kW.

[0101] The valence state detection unit consists of a UV spectrophotometer and a 0.2mm flow cell, with a detection frequency of 60s. 3 , add pure water to 1m 3 No additional sulfuric acid is required; the negative electrode liquid storage tank 4 has a volume of 2m 3 , add 2m electrolyte 3 .

[0102] The circulating water was turned on to adjust the temperature of the positive and negative electrode solutions to 30° C., and the circulating pumps (positive electrode circulating pump 34 and negative electrode circulating pump 44) were turned on at the same time, and circulated for 30 minutes.

[0103] The current was gradually increased to 250 A, and electrolysis was started. During the electrolysis process, the concentration of the electrolyte discharged from the cathode liquid storage tank 4 was continuously sampled and detected. When the concentration of tetravalent vanadium discharged from the cathode liquid storage tank 4 was 55% of the initial concentration, the current was adjusted to 100 A, and electrolysis was continued until the concentration of tetravalent vanadium was 50% of the initial concentration, and then the electrolysis was stopped.

[0104] The electrolysis device was used to conduct a test for a total of 500 hours, and the voltage was stable. The current efficiency during the electrolysis process fluctuated between 90% and 95%. The valence of the generated electrolyte could be stabilized at 3.5±0.1. The quality of the electrolyte product was stable, and no additional impurities were introduced after testing.

[0105] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention.

[0106] 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0107] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0108] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0109] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0110] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify 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 group, wherein the two end plates are located on both sides of the electrolytic cell group in a first direction, and the electrolytic cell group includes a cathode plate made of a carbon material; an anode plate made of a metal material; An ion exchange membrane, the cathode plate, the ion exchange membrane and the anode plate are arranged in sequence 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, wherein the electrolytic cell group 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 in communication with the anode electrolyte chamber, and the negative electrode liquid inlet channel and the negative electrode liquid outlet channel are in communication with 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 in sequence along the first direction; The electrolysis stack includes a bipolar plate, the anode side of the bipolar plate is made of a metal material, the cathode side of the bipolar plate is made of a carbon material, and the anode side and the cathode side of the bipolar plate respectively constitute the anode plate and the cathode plate adjacent to each other in the first direction.

3. The electrolytic cell stack according to claim 2, characterized in that: hot pressing a carbon material onto the anode plate to form the bipolar plate; Alternatively, the cathode plate and the anode plate are 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 collecting plate, an anode current collecting plate, and an anode insulating plate, wherein one of the two end plates, the cathode insulating plate, the cathode current collecting plate, a plurality of electrolytic cell groups, the anode collecting plate, the anode insulating plate, and the other of the two end plates are sequentially arranged in the first direction; Each of the electrolytic cell groups further includes a liquid flow frame, and the liquid flow frame 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; The anode current collecting plate and the cathode current collecting plate are both 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 directions of the anode plate and the cathode plate are both in the first direction, the anode plate is made of a metal 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.

7. A vanadium electrolyte valence adjustment device, characterized in that: include An electrolysis unit, wherein the electrolysis unit includes an electrolysis power supply and an electrolysis stack, wherein the electrolysis stack is the electrolysis stack according to claim 4, wherein the electrolysis stack has a cathode liquid inlet channel, a cathode liquid outlet channel, a cathode liquid inlet channel, and a cathode liquid outlet channel, wherein the positive electrode of the electrolysis power supply is connected to the anode current collecting plate of the electrolysis stack, and the negative electrode of the electrolysis power supply is connected to the cathode current collecting plate of the electrolysis stack; A liquid storage portion, the liquid storage portion comprising a cathode liquid storage tank and a cathode liquid storage tank, the cathode liquid storage tank being used to store a cathode electrolyte, the cathode liquid storage tank being used to store a cathode electrolyte, the cathode liquid storage tank having an outlet connected to the inlet of the cathode liquid inlet channel via a first pipeline, the cathode liquid discharge channel having an outlet connected to the inlet of the cathode liquid storage tank via a second pipeline, the cathode liquid storage tank having an outlet connected to the inlet of the cathode liquid inlet channel via a third pipeline, and the cathode liquid discharge channel having an outlet connected to the inlet of the cathode liquid storage tank via 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 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 respectively connected to the third pipeline and the detection device. A sampling pump is provided on the sampling pipeline to sample the negative electrode electrolyte discharged from the negative electrode liquid storage tank at every first preset time interval.

9. The vanadium electrolyte valence adjustment device according to claim 8, characterized in that: The negative electrode electrolyte is a vanadium electrolyte, a stirring device is provided in the negative electrode liquid storage tank, and a filter is provided at one end of the first pipeline adjacent to the positive electrode liquid inlet channel and at one end of the third pipeline adjacent to the negative electrode liquid inlet channel; 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 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 passed into the flow cell, the flow cell is placed in the ultraviolet spectrophotometer, and then the valence state of the vanadium electrolyte is obtained according to the absorbance of the vanadium electrolyte; Alternatively, the optical path of the circulation cell is greater than or equal to 10 mm and less than or equal to 20 mm, the second preset volume of vanadium electrolyte obtained by the sampling pump and the third preset volume of pure water are mixed in the mixing chamber and then passed into the circulation cell, and then the circulation cell is placed in the ultraviolet spectrophotometer, and then the valence state of the vanadium electrolyte is obtained based on the absorbance of the vanadium electrolyte, wherein the ratio of the second preset volume to the third preset volume is 1:(10-100).

10. The vanadium electrolyte valence adjustment device according to claim 7, characterized in that: The electrolysis unit further includes a voltage monitor connected to a plurality of tabs on the electrolysis stack so as to detect the voltage of each electrolysis cell group of the electrolysis stack; The cathode liquid storage tank and the cathode liquid storage tank are both provided with a temperature regulating device; The cathode liquid storage tank is provided with a cathode liquid storage tank level gauge, and the cathode liquid storage tank is provided with a cathode liquid storage tank level gauge; At least one of the first pipeline and the second pipeline is provided with a cathode circulation pump; The first pipeline and the second pipeline are both provided with a cathode temperature sensor and a cathode pressure sensor; At least one of the third pipeline and the fourth pipeline is provided with a negative electrode circulation pump; The third pipeline and the fourth pipeline are both provided with a cathode temperature sensor and a cathode pressure sensor.

11. The vanadium electrolyte valence adjustment device according to claim 10, characterized in that: The following steps are included when using it: S1, passing water into the cathode liquid storage tank as the cathode electrolyte, and passing a vanadium electrolyte with a valence greater than or equal to four into the cathode liquid storage tank as the cathode electrolyte; S2, continuously passing the positive electrode electrolyte and the negative electrode electrolyte into the electrolytic stack for a fourth preset time; S3, detecting the temperature and pressure of the positive electrode electrolyte in the first pipeline and the second pipeline, detecting the temperature and pressure of the negative electrode electrolyte in the third pipeline and the third pipeline, and detecting the valence state of the negative electrode electrolyte in the third pipeline; S4, controlling the temperature of the cathode electrolyte in the cathode liquid storage tank and the anode electrolyte in the anode liquid storage tank to between 10° C. and 50° C.; S5, turning on the electrolysis power supply and gradually increasing the electrolysis current value so that the current density reaches a fifth preset value; S6. When the valence of the negative electrode electrolyte discharged from the negative electrode liquid storage tank reaches 3.5, stop electrolysis.

12. The vanadium electrolyte valence adjustment device according to claim 11, characterized in that: Controlling the temperature of the cathode electrolyte in the cathode liquid storage tank and the anode electrolyte in the anode liquid storage tank to be between 25° C. and 35° C.; The fourth preset time is greater than or equal to 5 minutes and less than or equal to 30 minutes; The fifth preset value is greater than or equal to 50 mA / cm 2 And less than or equal to 300mA / cm 2 ; In step S6, when the valence of the negative electrode electrolyte discharged from the negative electrode solution storage tank reaches 3.6, the current density is reduced so that the current density reaches a sixth preset value.

13. The vanadium electrolyte valence adjustment device according to claim 12, characterized in that: The fifth preset value is greater than or equal to 100mA / cm 2 And less than or equal to 200mA / cm 2 ; The sixth preset value is greater than or equal to 20 mA / cm 2 And less than or equal to 50mA / cm 2 .

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