A hollow coating battery current collecting structure, current density measurement system and method

Abstract

The present invention discloses a hollow coating battery current collecting structure, current density measuring system and method, and belongs to the technical field of liquid flow battery. The structure includes a flow channel frame and a hollow coating printed circuit board; a liquid inlet is provided on one side of the flow channel frame, a liquid outlet is provided on the opposite side of the liquid inlet, and the first surface of the flow channel frame is engraved with alternately arranged flow channel grooves; a hollow coating printed circuit board is engraved with a hollow flow channel with a hollow flow channel rib, and a conductive copper strip is etched on the first surface of the hollow coating printed circuit board, a wiring hole is provided at one end of the conductive copper strip, and the other end is provided on the hollow flow channel rib, and the conductive copper strip on the hollow flow channel rib is partially covered with a coating, and the flow channel groove and the hollow flow channel, and the flow channel rib and the hollow flow channel rib are arranged overlappingly. The flow channel frame and the coating are corrosion-resistant, and the structure can accurately measure the current density distribution inside the flow battery with a flow channel according to the current density of each coated conductive copper strip current collector being equal to the ratio of the measured current to the surface area of ​​the area covered with the coating on the conductive copper strip.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid flow batteries, and in particular relates to a hollow coating battery current collecting structure, a current density measurement system and a method. Background Art

[0002] The uniformity of current density distribution inside the electrode is the key to determining battery performance. The uneven distribution of current density inside the electrode is mainly affected by the comprehensive factors of battery structure, materials, and operating parameters. The uneven distribution of current density inside the electrode will cause serious local overpotential, voltage loss and side reactions in the battery, causing corrosion of the current collector, shortening the battery life, and increasing electrolyte leakage and battery safety risks.

[0003] According to whether the battery has a flow channel structure, the internal current density measurement method of the battery where the reactants flow is divided into: the internal current density measurement of the battery with a flow channel and the internal current density measurement of the battery without a flow channel. At present, the two main methods for measuring the internal current density distribution of the flow battery with a flow channel are the partitioned graphite collector block measurement method and the printed circuit board (PCB). Regarding the partitioned graphite collector block measurement method, one is to process the graphite plate into a mutually insulated block-type graphite collector structure that is bonded together through a complex processing process such as engraving partition grooves on one side, filling with adhesive insulating materials, milling off the non-grooved part on the back, and milling the flow channel. When measuring, it is also necessary to use it in conjunction with a copper foil printed circuit board (PCB) with the same partition structure, and the current on each graphite collector is led out through the copper foil in contact with it for measurement. This measurement method has two main disadvantages: First, it cannot guarantee that the contact between each graphite current collector plate and the conductive copper sheet is completely consistent during the measurement process, and the accuracy of the measurement results cannot be guaranteed; second, due to the limitations of its own manufacturing technology, the ribs of the current collector structure will have insulating adhesives, which changes the battery flow channel structure and the electron conduction path. This current collector structure changes the original rib structure of the battery flow channel and will affect the battery charging and discharging performance. The second is to use a slot-type current collector structure, which is mainly composed of an insulating current collector frame and a plurality of knife-shaped graphite current collector sheets. The current collector frame is engraved with electrolyte flow channel grooves, and the flow channel ribs that play a conductive role are composed of a number of knife-shaped graphite current collector sheets inserted on the current collector frame. However, the slot-type current collecting structure still has obvious disadvantages: since the measurement structure is limited by the "rib-groove" structure of the battery flow channel and the structure of the knife-shaped graphite sheet, it is only applicable to a single-channel with a simple structure or a flow channel structure in which the original flow channel ribs are not connected to each other, such as a serpentine single flow channel and a parallel flow channel. For the widely used interdigitated flow channel and the meandering flow channel, since the ribs of the flow channel are connected, the knife-shaped graphite sheet must also be connected without changing the electron conduction path, which limits the function of the knife-shaped graphite sheet partition measurement and cannot achieve the measurement of the current density distribution on the electrode surface; in addition, the current collecting structure is complex to process and has high cost, and is not suitable for promotion. For the printed circuit board (PCB) measurement method, a hollow gold-plated copper printed circuit board (PCB, thickness of about 0.5mm) with the same size as the ribs of the flow channel structure is placed between the graphite current collecting plate of the battery and the porous electrode to achieve the internal current density measurement of the battery. However, the measurement method using gold-plated copper as the medium is not suitable for liquid flow batteries with acidic electrolytes, mainly because the electrolyte of the liquid flow battery is a strong acid solution, H + The ion concentration is generally 4 to 6 mol / L 1 (pH value <1), the conductive copper on the PCB will react with the acidic electrolyte and contaminate the electrolyte, making it impossible to measure the current density distribution on the electrode surface.

[0004] In summary, existing methods for measuring the internal current density of batteries have the problems of narrow applicability, high cost, and inability to accurately and reliably measure the current density distribution inside a flow battery with a flow channel. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a hollow coated battery current collecting structure, a current density measurement system and method, so as to solve the problems that the existing methods have a narrow application range, high cost, and cannot accurately and reliably measure the current density distribution inside the flow battery with a flow channel.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The invention discloses a hollow coating battery current collecting structure, comprising a flow channel frame and a hollow coating printed circuit board;

[0008] A flow channel frame, the flow channel frame is made of corrosion-resistant insulating material, a liquid inlet is provided on one side of the flow channel frame, a liquid outlet is provided on the opposite side of the liquid inlet, and a flow channel groove and a flow channel rib arranged alternately are engraved on the first surface of the flow channel frame, one end of the flow channel groove is connected to the liquid inlet, and the other end is connected to the liquid outlet;

[0009] A hollow coated printed circuit board, wherein a hollow flow channel with a hollow flow channel rib is engraved on the hollow coated printed circuit board, and a conductive copper tape is etched on the first surface of the hollow coated printed circuit board; a wiring hole is arranged at one end of the conductive copper tape, and the other end is arranged on the hollow flow channel rib, and the conductive copper tape on the hollow flow channel rib is partially covered with a coating;

[0010] The hollow flow channels on the second surface of the hollow coated printed circuit board overlap with the flow channel grooves on the first surface of the flow channel frame, and the hollow flow channel ribs on the second surface of the hollow coated printed circuit board overlap with the flow channel ribs on the first surface of the flow channel frame.

[0011] Preferably, the hollow coated printed circuit board is made of an insulating epoxy resin or polytetrafluoroethylene sheet with a thickness of 0.1 to 0.2 mm.

[0012] Preferably, the conductive copper tape on the hollow coated printed circuit board is made of copper foil with a thickness of 5 to 25 μm through an etching process.

[0013] Preferably, the geometric shape and size of the hollow flow channels and hollow flow channel ribs on the hollow coated printed circuit board are the same as the geometric shape and size of the flow channel grooves and flow channel ribs on the first surface of the flow channel frame.

[0014] Preferably, the width of the conductive copper tape on the hollow coated printed circuit board is the same as the width of the hollow flow channel rib, and the number of the conductive copper tapes is the same as the number of the hollow flow channel ribs; the hollow coated printed circuit board is manufactured by PCB equipment.

[0015] Preferably, the coating is a graphite coating, a gold coating, a titanium coating or a platinum coating.

[0016] Preferably, the coating and the hollow flow channel area on the first surface of the hollow coated printed circuit board are in close contact with the positive electrode material of the liquid flow battery.

[0017] Preferably, the flow channel grooves on the first surface of the flow channel frame and the hollow flow channels on the hollow coated printed circuit board are serpentine flow channel grooves, return flow channel grooves, parallel flow channel grooves, interdigitated flow channel grooves or curved wave flow channel grooves.

[0018] The present invention also discloses a current density distribution measurement system with a hollow coated battery current collecting structure, comprising a liquid flow battery with a flow channel and an external charge and discharge unit, wherein the liquid flow battery with a flow channel comprises the above-mentioned hollow coated battery current collecting structure, a positive electrode gasket, a positive electrode material, a diaphragm, a negative electrode material, a negative electrode gasket, a negative current collecting plate and a negative conductive plate; the diaphragm is arranged between the positive electrode material and the negative electrode material; the coating and the hollow flow channel area of ​​the hollow coated battery current collecting structure are in close contact with the positive electrode material of the battery; the conductive copper tape wiring holes and the negative conductive plate of the hollow coated battery current collecting structure are connected to the external charge and discharge unit.

[0019] The present invention also discloses a measurement method using the hollow coating battery current collecting structure, the steps are as follows:

[0020] S1, assembling a hollow coated battery current collecting structure, a positive electrode gasket, a positive electrode material, a separator, a negative electrode material, a negative current collecting plate and a negative conductive plate, and closely contacting the coating and the hollow flow channel area on the first surface of the hollow coated printed circuit board of the hollow coated battery current collecting structure with the positive electrode material to complete the assembly of the liquid flow battery with a flow channel;

[0021] S2, introducing a corrosive electrolyte from the liquid inlet of the hollow coating battery current collecting structure, and the corrosive electrolyte is discharged from the liquid outlet after passing through the flow channel groove;

[0022] S3, the external charge and discharge unit charges and discharges the flow battery with flow channel into which the corrosive electrolyte is introduced, and each conductive copper strip wiring hole and the negative electrode conductive plate are connected to the external charge and discharge unit to form an external detection circuit;

[0023] S4. Calculate the current density using the following formula:

[0024]

[0025] The current is the current value drawn from each conductive copper strip when the external charge and discharge unit is charged and discharged; the surface area of ​​the coating covered by the conductive copper strip is the product of the length and width of the coating.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention provides a hollow coating battery current collecting structure, which directly replaces the original graphite current collecting plate and copper conductive plate in the battery, saves materials, reduces the detection cost of the liquid flow battery, has high measurement accuracy and strong scalability; the flow channel frame made of corrosion-resistant insulating material can be used for batteries using acidic and alkaline corrosive electrolytes on the one hand, extending the battery life, and on the other hand can solve the problems of high processing difficulty and high cost of the existing battery graphite current collecting plate and conductive plate; the coating is made of anti-corrosion material, which is suitable for measuring the current density inside the liquid flow battery with a flow channel having a corrosive electrolyte, and the hollow coating printed circuit board is connected with the The flow channel frame is used in conjunction to construct a partitioned current collecting structure with a flow channel structure. When implemented, the area covered with the coating on the conductive copper belt is directly in contact with the positive electrode material of the flow battery. The wiring holes of each independent conductive copper belt are respectively connected to the external charge and discharge unit, forming a partitioned current collecting structure with a flow channel structure. The current density of each coated conductive copper belt current collector is equal to the ratio of the measured current to the surface area of ​​the area covered with the coating on the conductive copper belt; the coating is used as a protective medium for the conductive copper belt to measure the internal current density distribution of the battery with corrosive electrolyte, reduce the measurement difficulty, and realize the accurate measurement of the internal current density partition of the flow battery with a flow channel structure. The hollow coated battery current collecting structure can measure the internal current density distribution of the flow battery with a flow channel with a corrosive electrolyte in real time, conduct all-round real-time monitoring of the electrochemical reaction inside the battery, accurately measure the internal current density distribution of the flow battery, deepen the understanding and recognition of the battery-related process mechanism, and master the law of uneven distribution and change of the internal characteristic parameters of the flow battery, which is of great significance and application value for optimizing the design, manufacture and operation of the flow battery.

[0028] Furthermore, the hollow coated printed circuit board is manufactured by automated high-precision machinery, and the coating can be manufactured by screen printing technology or electroplating technology depending on the material. The two processing methods can ensure the consistency of each coated conductive copper strip, reduce measurement errors, and improve measurement accuracy.

[0029] The present invention provides a method for measuring a hollow coated battery current collecting structure for a corrosive electrolyte. The method utilizes the hollow coated battery current collecting structure and calculates the current density by taking the current density of each coated conductive copper strip current collector as equal to the ratio of the measured current to the surface area of ​​the region covered with the coating on the conductive copper strip. The method can accurately measure the internal current density distribution of a flow battery with a flow channel having a corrosive electrolyte, has low cost, strong feasibility, simple operation, high stability and strong scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1It is an exploded schematic diagram of the hollow coating battery current collecting structure for corrosive electrolyte of the present invention;

[0031] Figure 2 is a cross-sectional schematic diagram of a hollow coated printed circuit board of the present invention;

[0032] Figure 3 is a cross-sectional schematic diagram of the flow channel frame of the present invention;

[0033] Figure 4 It is a schematic diagram of the assembly of the hollow coating battery current collecting structure for corrosive electrolyte of the present invention;

[0034] Figure 5 It is a schematic structural diagram of the hollow coating battery current collecting structure for corrosive electrolyte of the present invention assembled inside a liquid flow battery;

[0035] Figure 6 This is the current density distribution diagram measured in Example 1 of the present invention.

[0036] Wherein: 1. flow channel frame; 2. hollow coated printed circuit board; 3. liquid inlet; 4. liquid outlet; 5. first surface of flow channel frame; 6. flow channel groove; 7. flow channel rib; 8. first surface of printed circuit board; 9. second surface of printed circuit board; 10. conductive copper tape; 11. coating; 12. conductive copper tape wiring hole; 13. hollow flow channel; 14. hollow flow channel rib; 15. positive electrode material; 16. diaphragm; 17. negative current collector; 18. negative conductive plate; 19. negative electrode material; 20. positive electrode gasket; 21. negative electrode gasket. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0040] like Figure 1-4 As shown, a hollow coating battery current collecting structure provided by the present invention is used for corrosive electrolyte, comprising: a flow channel frame 1 and a hollow coating printed circuit board 2 having the same flow channel structure as the flow channel frame 1;

[0041] The flow channel frame 1 is made of a corrosion-resistant insulating material with a Darlow hardness value greater than 8 degrees, preferably acrylic glass, resin, plastic or ceramic that meets the hardness requirements; the size of the flow channel frame 1 matches and accommodates the size of the flow channel groove 6; a liquid inlet 3 for introducing electrolyte is provided on one side of the flow channel frame 1, and a liquid outlet 4 for discharging electrolyte is provided on the opposite side of the liquid inlet 3; a flow channel groove 6 and a flow channel rib 7 are engraved on the first surface 5 of the flow channel frame, and one end of the flow channel groove 6 is connected to the liquid inlet 3, and the other end is connected to the liquid outlet 4.

[0042] A hollow coated printed circuit board 2, the hollow coated printed circuit board 2 is made of an insulating epoxy resin or polytetrafluoroethylene sheet with a thickness of 0.1 to 0.2 mm through automated high-precision PCB equipment, a hollow flow channel 13 with a hollow flow channel rib 14 is engraved on the hollow coated printed circuit board 2, a conductive copper tape 10 is etched on the first surface 8 of the printed circuit board, the conductive copper tape 10 is made of a copper foil with a thickness of 5 to 25 μm through an etching process, a wiring hole 12 for connecting an external charging and discharging unit is provided at one end of the conductive copper tape 10, and the other end is provided on the hollow flow channel rib 14 of the hollow flow channel 13, a coating 11 made of a corrosion-resistant conductive material is coated on the conductive copper tape 10 part on the hollow flow channel rib 14 by screen printing or electroplating technology, and the coating 11 Including but not limited to graphite coating, gold coating, titanium coating and platinum coating, the graphite coating is prepared by screen printing technology, the gold coating, titanium coating and platinum coating are prepared by electroplating process, the coating 11 can prevent the electrolyte from corroding the conductive copper strip 10, and realize the internal measurement of the flow battery with corrosive electrolyte; the width of the conductive copper strip 10 is the same as the width of the hollow flow channel rib 14, the number of the conductive copper strip 10 is the same as the number of the hollow flow channel rib 14, the coating 11 is consistent with the length and width of the hollow flow channel rib 14, and can completely restore the rib structure and area of ​​the internal flow channel structure of the battery, and the geometric shape and size of the hollow flow channel 13 and the hollow flow channel rib 14 are the same as the geometric shape and size of the flow channel groove 6 and the flow channel rib 7 on the first surface 5 of the flow channel frame. The hollow flow channel 13 on the second surface 9 of the hollow coated printed circuit board overlaps with the flow channel groove 6 on the first surface 5 of the flow channel frame, and the hollow flow channel rib 14 on the second surface 9 of the hollow coated printed circuit board overlaps with the flow channel rib 7 on the first surface 5 of the flow channel frame.

[0043] The coating 11 and the hollow flow channel 13 areas on the first surface 8 of the hollow coated printed circuit board are in close contact with the positive electrode material 15 of the liquid flow battery; the flow channel grooves 6 and the hollow flow channels 13 can both be serpentine flow channel grooves, return flow channel grooves, parallel flow channel grooves, interdigitated flow channel grooves or curved wavy flow channel grooves.

[0044] like Figure 5 The present invention provides a current density distribution measurement system with a hollow coating battery current collecting structure, comprising a liquid flow battery with a flow channel and an external charge and discharge unit, wherein the liquid flow battery with a flow channel comprises the above-mentioned hollow coating battery current collecting structure, a positive electrode gasket 20, a positive electrode material 15, a diaphragm 16, a negative electrode material 19, a negative electrode gasket 21, a negative current collecting plate 17 and a negative conductive plate 18; the diaphragm 16 is arranged between the positive electrode material 15 and the negative electrode material 19, and is used to separate the electrode materials; the coating 11 area and the hollow flow channel 13 area with the hollow coating battery current collecting structure are in close contact with the positive electrode material 15 of the battery; the conductive copper tape wiring hole 12 and the negative conductive plate 18 with the hollow coating battery current collecting structure are connected to the external charge and discharge unit for detection.

[0045] The measurement method using a battery current collecting structure with a hollow coating provided by the present invention comprises the following steps:

[0046] 1) Assembling a hollow coated battery current collecting structure, a positive electrode material 15, a positive electrode gasket 20, a separator 16, a negative electrode material 19, a negative electrode gasket 21, a negative current collecting plate 17 and a negative conductive plate 18, and closely contacting the coating 11 area on the conductive copper tape 10 on the first surface 8 of the printed circuit board of the hollow coated battery current collecting structure and the hollow flow channel 13 area with the positive electrode material 15 to complete the assembly of the liquid flow battery with the flow channel;

[0047] 2) Introducing a corrosive electrolyte from the liquid inlet 3 of the hollow coated battery current collecting structure, and the corrosive electrolyte is discharged from the liquid outlet 4 after passing through the flow channel 6;

[0048] 3) The external charge and discharge unit charges and discharges the flow battery with a flow channel into which the corrosive electrolyte is introduced, and each conductive copper strip wiring hole 12 and the negative conductive plate 18 are connected to the external charge and discharge unit to form an external detection circuit;

[0049] 4) Calculate the current density using the following formula:

[0050]

[0051] Among them, the current is the current value drawn by each conductive copper strip when the external charge and discharge unit is charged and discharged, mA; the surface area of ​​the coating covered by the conductive copper strip is the product of the length and width of the coating, cm 2 .

[0052] Example 1

[0053] The present invention provides a hollow coating battery current collecting structure for corrosive electrolyte, comprising: a flow channel frame 1 and a hollow coating printed circuit board 2 having the same flow channel structure as the flow channel frame 1;

[0054] The flow channel frame 1 is made of acrylic glass with a Darlow hardness value of 9 degrees and a thickness of 8mm; a liquid inlet 3 for introducing electrolyte is provided on one side of the flow channel frame 1, and a liquid outlet 4 for discharging electrolyte is provided on the opposite side of the liquid inlet 3, and a flow channel groove 6 and a flow channel rib 7 are engraved on the first surface 5 of the flow channel frame, one end of the flow channel groove 6 is connected to the liquid inlet 3, and the other end is connected to the liquid outlet 4; the flow channel groove 6 is a serpentine flow channel groove, and the serpentine flow channel groove is composed of 7 U-shaped grooves in the horizontal direction, with a length of 36mm, a width of 2mm, and a groove depth of 2mm; there are 8 flow channel ribs 7, and the flow channel ribs 7 are 34mm long and 2mm wide.

[0055] A hollow coated printed circuit board 2, the hollow coated printed circuit board 2 is made of an insulating epoxy resin sheet with a thickness of 0.1 mm and processed by a PCB device, a hollow flow channel 13 with a hollow flow channel rib 14 is engraved on the hollow coated printed circuit board 2, the hollow flow channel 13 has the same size as the serpentine flow channel shape and length and width dimensions of the first surface 5 of the flow channel frame, the length is 36 mm, the width is 2 mm, and 8 hollow flow channel ribs 14 are provided, the hollow flow channel ribs 14 have the same size as the flow channel ribs 7 on the first surface 5 of the flow channel frame, the length of the hollow flow channel rib 14 is 34 mm, and the width is 2 mm; Printing Eight 20 μm thick conductive copper strips 10 made of copper foil are etched on the first surface 8 of the circuit board. Each conductive copper strip 10 is 68 mm long and 2 mm wide. A wiring hole 12 is provided at one end of the conductive copper strip 10, and the other end is provided on the hollow flow channel rib 14. The conductive copper strip 10 on the hollow flow channel rib 14 is partially coated with a coating 11 made of a corrosion-resistant conductive material by screen printing technology. The coating 11 is a graphite coating composed of graphite and a phenol resin adhesive. The coating 11 has a thickness of 20 μm, a width of 2 mm, and a length of 34 mm, that is, the surface area of ​​the coating is 0.68 cm 2 The hollow channel 13 of the second surface 9 of the hollow coated printed circuit board overlaps with the channel groove 6 of the first surface 5 of the channel frame, and the hollow channel ribs 14 of the second surface 9 of the hollow coated printed circuit board overlap with the channel ribs 7 of the first surface 5 of the channel frame.

[0056] The geometric shapes and sizes of the hollow flow channels 13 and the hollow flow channel ribs 14 on the hollow coated printed circuit board 2 are respectively the same as the geometric shapes and sizes of the flow channel grooves 6 and the flow channel ribs 7 on the first surface 5 of the flow channel frame; the conductive copper tape 10 of the coating 11 covering the first surface 8 of the hollow coated printed circuit board and the hollow flow channel 13 area are in close contact with the positive electrode material 15 of the liquid flow battery.

[0057] The current density distribution measurement system with the hollow coating battery current collecting structure provided by the present invention comprises an all-vanadium liquid flow battery and an external charge and discharge unit, wherein the all-vanadium liquid flow battery comprises the hollow coating battery current collecting structure, a positive electrode gasket 20, a positive graphite felt electrode, a diaphragm 16, a negative graphite felt electrode, a negative electrode gasket 21, a negative current collecting plate 17 and a negative conductive plate 18; the diaphragm 16 is used to separate the positive graphite felt electrode from the negative graphite felt electrode; the coating 11 area and the hollow flow channel 13 area with the hollow coating battery current collecting structure are in close contact with the positive graphite felt electrode of the battery; each component is fastened with an aluminum end plate by bolts and nuts; the conductive copper belt wiring hole 12 and the negative conductive copper plate 18 with the hollow coating battery current collecting structure are connected to the external charge and discharge unit for detection;

[0058] The positive graphite felt electrode is made of 4cm×3cm GFA5 graphite felt; the separator 16 is made of Nafion117; the negative current collector 17 is a graphite current collector engraved with a serpentine flow channel, and the negative current is collected by the copper negative conductive plate 18 and connected to the external circuit.

[0059] The present invention provides a measurement method using the above-mentioned battery current collecting structure with a hollow coating, and the steps are as follows:

[0060] 1) Assembling a hollow coated battery current collecting structure, a positive electrode gasket 20, a positive graphite felt electrode, a separator 16, a negative electrode gasket 21, a negative graphite felt electrode, a negative current collecting plate 17 and a negative conductive plate 18, and closely contacting the coating 11 area and the hollow flow channel 13 area on the first surface 8 of the printed circuit board of the hollow coated battery current collecting structure with the positive graphite felt electrode to ensure good conductivity between the graphite coating and the positive electrode material 15, and completing the assembly of the liquid flow battery with a flow channel;

[0061] 2) A corrosive electrolyte is introduced from the liquid inlet 3 of the hollow coating battery collector structure, and the corrosive electrolyte is discharged from the liquid outlet 4 after passing through the flow channel 6; wherein the corrosive electrolyte is a mixed solution of 1.5 mol / L VOSO4 and 2 mol / L H2SO4, and the electrolyte flow rate is 20 mL / min;

[0062] 3) The external charge and discharge unit discharges the flow battery with a flow channel into which the corrosive electrolyte is introduced, and the conductive copper strip wiring hole 12 and the negative electrode conductive plate 18 are connected to the external charge and discharge unit to form an external detection circuit;

[0063] 4) Under the condition of measuring ambient temperature of 20℃, calculate the current density by combining the following formula:

[0064]

[0065] Among them, the current is the current value drawn by each conductive copper strip when the external charge and discharge unit is charged and discharged, mA; the surface area of ​​the coating covered by the conductive copper strip is the product of the length and width of the coating, cm 2 .

[0066] The measurement results are as follows Figure 6 As shown, the horizontal axis is the charging time, and the vertical axis is the current density during the charging process measured at each position (referring to the position of the conductive copper tape 10 covering the coating 11, that is, the position of the 8 conductive copper tape wiring holes 12 connected to the external charging and discharging unit, and the conductive copper tape wiring holes 12 are numbered 1 to 8 from bottom to top).

[0067] The results show that during the battery charging process, the electrochemical reaction degree inside the electrode is unevenly distributed, the current density is relatively small at the inlet and outlet of the flow channel, and the current density is relatively high in the middle area of ​​the flow channel, and decreases with the position of the flow channel. In addition, during the charging process, the uniformity of the current density distribution improves with the change of time, but the uniformity of the current density distribution decreases with the further increase of time. This is mainly because the electrolyte will continue to flow along the flow channel with lower pressure near the inlet of the flow channel, rather than flowing into the porous electrode with greater resistance for reaction. Similarly, at the outlet of the electrolyte, the electrolyte will flow to the outside of the battery with lower pressure, so the current density is relatively small at the inlet and outlet of the flow channel. As the electrolyte is transported in the middle flow channel, the reactants inside gradually participate in the reaction in the adjacent graphite felt electrode and are consumed. Therefore, the reactants in the graphite felt electrode downstream of the flow channel are less, showing a trend of gradually decreasing current density. At the beginning and end of charging, the activation polarization and concentration polarization inside the battery are relatively large, so the uniformity of the current density distribution is poor.

[0068] Example 2

[0069] The present invention provides a hollow coating battery current collecting structure for corrosive electrolyte, comprising: a flow channel frame 1 and a hollow coating printed circuit board 2 having the same flow channel structure as the flow channel frame 1;

[0070] The flow channel frame 1 is made of a resin with a Darlow hardness value of 9 degrees and a thickness of 10 mm; a liquid inlet 3 for introducing electrolyte is provided on one side of the flow channel frame 1, and a liquid outlet 4 for discharging electrolyte is provided on the opposite side of the liquid inlet 3; a flow channel groove 6 and a flow channel rib 7 are engraved on the first surface 5 of the flow channel frame, one end of the flow channel groove 6 is connected to the liquid inlet 3, and the other end is connected to the liquid outlet 4; the flow channel groove 6 is a serpentine flow channel groove, which is composed of 7 U-shaped grooves in the horizontal direction, with a length of 36 mm, a width of 2 mm, and a groove depth of 2 mm; 8 flow channel ribs 7 are provided, and the flow channel rib 7 is 34 mm long and 2 mm wide.

[0071] A hollow coated printed circuit board 2 is made of a polytetrafluoroethylene sheet with a thickness of 0.2 mm and processed by a PCB device. A hollow flow channel 13 with a hollow flow channel rib 14 is engraved on the hollow coated printed circuit board 2. The size of the hollow flow channel 13 is the same as the serpentine flow channel shape and length and width of the first surface 5 of the flow channel frame, with a length of 36 mm and a width of 2 mm. Eight 20 μm thick conductive copper strips 10 made of copper foil are etched on the first surface 8 of the printed circuit board. Each conductive copper strip 10 is 68 mm long and 2 mm wide. A wiring hole 12 is provided at one end of the conductive copper strip 10, and the other end is provided on the hollow flow channel rib 14. The conductive copper strip 10 on the hollow flow channel rib 14 is partially coated with a coating 11 by electroplating technology. The coating 11 is a gold coating. The coating 11 has a thickness of 20 μm, a width of 2 mm, and a length of 34 mm, that is, the surface area of ​​the gold coating is 0.68 cm 2 ; One end of the conductive copper tape 10 covered with the coating 11 forms a hollow flow channel rib 14, and 8 hollow flow channel ribs 14 are provided. The size of the hollow flow channel rib 14 is the same as the shape and length and width of the flow channel rib 7 on the first surface 5 of the flow channel frame. The hollow flow channel rib 14 is 34 mm long and 2 mm wide; the hollow flow channel 13 on the second surface 9 of the hollow coated printed circuit board is overlapped with the flow channel groove 6 on the first surface 5 of the flow channel frame, and the hollow flow channel rib 14 on the second surface 9 of the hollow coated printed circuit board is overlapped with the flow channel rib 7 on the first surface 5 of the flow channel frame.

[0072] The geometric shape and size of the hollow channel 13 and the hollow channel ribs 14 on the hollow coated printed circuit board 2 are the same as the geometric shape and size of the channel grooves 6 and the channel ribs 7 on the first surface 5 of the channel frame; the conductive copper tape 10 and the hollow channel 13 area of ​​the coating 11 covered on the first surface 8 of the hollow coated printed circuit board are in close contact with the positive electrode material 15 of the liquid flow battery.

[0073] The structure of the current density distribution measurement system with the hollow coating battery current collecting structure is the same as that of Example 1, and the batteries used include but are not limited to all-vanadium liquid flow batteries.

[0074] The measurement method of the above-mentioned battery current collecting structure with hollow coating is the same as that of Example 1.

[0075] Example 3

[0076] The present invention provides a hollow coating battery current collecting structure for corrosive electrolyte, comprising: a flow channel frame 1 and a hollow coating printed circuit board 2 having the same flow channel structure as the flow channel frame 1;

[0077] The flow channel frame 1 is made of plastic with a Darlow hardness value of 12 degrees and a thickness of 8mm; a liquid inlet 3 for introducing electrolyte is provided on one side of the flow channel frame 1, and a liquid outlet 4 for discharging electrolyte is provided on the opposite side of the liquid inlet 3, and a flow channel groove 6 and a flow channel rib 7 are engraved on the first surface 5 of the flow channel frame, one end of the flow channel groove 6 is connected to the liquid inlet 3, and the other end is connected to the liquid outlet 4; the flow channel groove 6 is a serpentine flow channel groove, and the serpentine flow channel groove is composed of 7 U-shaped grooves in the horizontal direction, with a length of 36mm, a width of 2mm, and a groove depth of 2mm; there are 8 flow channel ribs 7, and the flow channel rib 7 is 34mm long and 2mm wide.

[0078] A hollow coated printed circuit board 2 is made of an insulating epoxy resin sheet with a thickness of 0.12 mm and processed by PCB equipment. A hollow flow channel 13 with a hollow flow channel rib 14 is engraved on the hollow coated printed circuit board 2. The size of the hollow flow channel 13 is the same as the serpentine flow channel shape and length and width of the first surface 5 of the flow channel frame, with a length of 36 mm and a width of 2 mm. Eight 20 μm thick conductive copper strips 10 made of copper foil are etched on the first surface 8 of the printed circuit board. Each conductive copper strip 10 is 68 mm long and 2 mm wide. A wiring hole 12 is provided at one end of the conductive copper strip 10, and the other end is provided on the hollow flow channel rib 14. The conductive copper strip 10 on the hollow flow channel rib 14 is partially coated with a coating 11 made of a corrosion-resistant conductive material by electroplating technology. The coating 11 is a platinum coating. The platinum coating 11 has a thickness of 20 μm, a width of 2 mm, and a length of 34 mm, that is, the surface area of ​​the platinum coating is 0.68 cm 2 ; One end of the conductive copper tape 10 covered with the coating 11 forms a hollow flow channel rib 14, and 8 hollow flow channel ribs 14 are provided. The size of the hollow flow channel rib 14 is the same as the shape and length and width of the flow channel rib 7 on the first surface 5 of the flow channel frame. The hollow flow channel rib 14 is 34 mm long and 2 mm wide; the hollow flow channel 13 on the second surface 9 of the hollow coated printed circuit board is overlapped with the flow channel groove 6 on the first surface 5 of the flow channel frame, and the hollow flow channel rib 14 on the second surface 9 of the hollow coated printed circuit board is overlapped with the flow channel rib 7 on the first surface 5 of the flow channel frame.

[0079] The geometric shapes and sizes of the hollow flow channels 13 and the hollow flow channel ribs 14 on the hollow coated printed circuit board 2 are respectively the same as the geometric shapes and sizes of the flow channel grooves 6 and the flow channel ribs 7 on the first surface 5 of the flow channel frame; the coating 11 and the hollow flow channel 13 areas covered on the first surface 8 of the hollow coated printed circuit board are in close contact with the positive electrode material 15 of the liquid flow battery.

[0080] The structure of the current density distribution measurement system with the hollow coating battery current collecting structure is the same as that of Example 1, and the batteries used include but are not limited to all-vanadium liquid flow batteries.

[0081] The measurement method of the above-mentioned battery current collecting structure with hollow coating is the same as that of Example 1.

[0082] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A hollow coating battery current collecting structure, characterized in that: It comprises a flow channel frame (1) and a hollow coated printed circuit board (2); A flow channel frame (1), the flow channel frame (1) is made of a corrosion-resistant insulating material, a liquid inlet (3) is provided on one side of the flow channel frame (1), a liquid outlet (4) is provided on the opposite side of the liquid inlet (3), a first surface (5) of the flow channel frame is engraved with alternately arranged flow channel grooves (6) and flow channel ribs (7), one end of the flow channel groove (6) is connected to the liquid inlet (3), and the other end is connected to the liquid outlet (4); A hollow coated printed circuit board (2), wherein a hollow flow channel (13) with a hollow flow channel rib (14) is engraved on the hollow coated printed circuit board (2), and a conductive copper strip (10) is etched on the first surface (8) of the hollow coated printed circuit board; a wiring hole (12) is provided at one end of the conductive copper strip (10), and the other end is provided on the hollow flow channel rib (14), and the conductive copper strip (10) on the hollow flow channel rib (14) is partially covered with a coating (11); The hollow flow channels (13) on the second surface (9) of the hollow coated printed circuit board are arranged in an overlapping manner with the flow channel grooves (6) on the first surface (5) of the flow channel frame, and the hollow flow channel ribs (14) on the second surface (9) of the hollow coated printed circuit board are arranged in an overlapping manner with the flow channel ribs (7) on the first surface (5) of the flow channel frame.

2. The hollow coating battery current collecting structure according to claim 1, characterized in that: The hollow coated printed circuit board (2) is made of an insulating epoxy resin or polytetrafluoroethylene sheet with a thickness of 0.1 to 0.2 mm.

3. The hollow coating battery current collecting structure according to claim 1, characterized in that: The conductive copper strip (10) on the hollow coated printed circuit board (2) is made of copper foil with a thickness of 5 to 25 μm through an etching process.

4. The hollow coating battery current collecting structure according to claim 1, characterized in that: The geometric shapes and sizes of the hollow flow channels (13) and hollow flow channel ribs (14) on the hollow coated printed circuit board (2) are the same as the geometric shapes and sizes of the flow channel grooves (6) and flow channel ribs (7) on the first surface (5) of the flow channel frame.

5. The hollow coating battery current collecting structure according to claim 1, characterized in that: The width of the conductive copper strip (10) on the hollow coated printed circuit board (2) is the same as the width of the hollow channel rib (14), and the number of the conductive copper strips (10) is the same as the number of the hollow channel ribs (14); the hollow coated printed circuit board (2) is manufactured by PCB equipment.

6. The hollow coating battery current collecting structure according to claim 1, characterized in that: The coating (11) is a graphite coating, a gold coating, a titanium coating or a platinum coating.

7. The hollow coating battery current collecting structure according to claim 1, characterized in that: The coating (11) and the hollow flow channel (13) area on the first surface (8) of the hollow coating printed circuit board are in close contact with the positive electrode material (15) of the liquid flow battery.

8. The hollow coating battery current collecting structure according to claim 1, characterized in that: The flow channel grooves (6) on the first surface (5) of the flow channel frame and the hollow flow channels (13) on the hollow coated printed circuit board (2) are serpentine flow channel grooves, return flow channel grooves, parallel flow channel grooves, interdigitated flow channel grooves or curved wave flow channel grooves.

9. A current density distribution measurement system with a hollow coating battery current collecting structure, characterized in that: The invention comprises a liquid flow battery with a flow channel and an external charge and discharge unit, wherein the liquid flow battery with a flow channel comprises a hollow coated battery current collecting structure as claimed in any one of claims 1 to 8, a positive electrode gasket (20), a positive electrode material (15), a diaphragm (16), a negative electrode material (19), a negative electrode gasket (21), a negative current collecting plate (17) and a negative conductive plate (18); the diaphragm (16) is arranged between the positive electrode material (15) and the negative electrode material (19); the coating (11) and the hollow flow channel (13) areas of the hollow coated battery current collecting structure are in close contact with the positive electrode material (15) of the battery; the conductive copper tape wiring holes (12) and the negative conductive plate (18) of the hollow coated battery current collecting structure are connected to the external charge and discharge unit.

10. A method for measuring a hollow coating battery current collecting structure using any one of claims 1 to 8, characterized in that: Here are the steps: S1, assembling a hollow coated battery current collecting structure, a positive electrode gasket (20), a positive electrode material (15), a separator (16), a negative electrode material (19), a negative current collecting plate (17) and a negative conductive plate (18), and closely contacting the coating (11) and the hollow flow channel (13) area on the first surface (8) of the hollow coated printed circuit board of the hollow coated battery current collecting structure with the positive electrode material (15), thereby completing the assembly of a liquid flow battery with a flow channel; S2, introducing a corrosive electrolyte from the liquid inlet (3) of the hollow coated battery current collecting structure, and the corrosive electrolyte is discharged from the liquid outlet (4) after passing through the flow channel groove; S3, an external charge and discharge unit charges and discharges the flow battery with a flow channel into which a corrosive electrolyte is introduced, and each conductive copper strip wiring hole (12) and the negative electrode conductive plate (18) are connected to the external charge and discharge unit to form an external detection circuit; S4. Calculate the current density using the following formula: The current is the current value drawn from each conductive copper strip (10) detected when the external charge and discharge unit is charging and discharging; and the surface area of ​​the coating (11) covered by the conductive copper strip (10) is the product of the length and width of the coating (11).

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