Measuring device and measuring method for contact resistance

Abstract

The invention provides a measuring device and a measuring method for contact resistance, which are used for measuring the contact resistance of a flow battery electrode, the measuring device comprises a first type of battery and a second type of battery, the first electrode and the second electrode have the same first thickness, and the third electrode has the second thickness; the first electrode respectively has the same first contact area with the first bipolar plate and the second bipolar plate, the second electrode respectively has the same second contact area with the second bipolar plate and the third bipolar plate, and the third electrode respectively has the same third contact area with the fourth bipolar plate and the fifth bipolar plate; and electrolyte is arranged in the first electrode, the second electrode and the third electrode. Measurement errors caused by neglecting certain resistance values in the measurement process are not needed; the method belongs to in-situ measurement, and the influence of a liquid phase circuit and electrolyte on contact resistance is considered. The measurement difficulty and the operation complexity of the contact resistance are reduced, and the measurement precision of the contact resistance is improved.

Description

Technical Field

[0001] The present application mainly relates to the field of liquid flow batteries, and in particular to a contact resistance measuring device and a contact resistance measuring method. Background Art

[0002] Contact resistance refers to the resistance between two conductors at the contact point or contact surface. The existence of contact resistance will affect the efficiency of electron flow between the two conductors, thereby affecting the performance of the circuit. In liquid flow batteries, there is a contact surface between the bipolar plate and the electrode, and there is contact resistance on the contact surface. my country's energy industry standard (NB / T 42007-2013) discloses "A Test Method for Bipolar Plates for All-vanadium Liquid Flow Batteries", but this method ignores the contact resistance between carbon felts, and the carbon felts are not tested in an electrolyte environment, and no electrode system is formed. It is an off-site measurement, which makes the measurement results inaccurate and small.

[0003] Therefore, there is an urgent need for a contact resistance measuring device and a contact resistance measuring method with accurate measurement results, quick operation and in-situ measurement. Summary of the invention

[0004] The present application aims to solve the technical problems of inaccurate contact resistance measurement results and ectopic measurement, and provides a contact resistance measurement device and a contact resistance measurement method.

[0005] In order to solve the above technical problems, the present application provides a contact resistance measuring device for measuring the contact resistance of a liquid flow battery electrode, including a first type of battery and a second type of battery, wherein the first type of battery includes a first bipolar plate, a second bipolar plate, a third bipolar plate, a first electrode and a second electrode, the first electrode is arranged between the first bipolar plate and the second bipolar plate, and the second electrode is arranged between the second bipolar plate and the third bipolar plate; the second type of battery includes a fourth bipolar plate, a fifth bipolar plate and a third electrode, and the third electrode is arranged between the fourth bipolar plate and the fifth bipolar plate; wherein the first electrode and the second electrode have the same first thickness, the third electrode has a second thickness, and the first thickness is different from the second thickness; the first electrode has the same first contact area with the first bipolar plate and the second bipolar plate, respectively, the second electrode has the same second contact area with the second bipolar plate and the third bipolar plate, respectively, the third electrode has the same third contact area with the fourth bipolar plate and the fifth bipolar plate, and the first contact area, the second contact area and the third contact area are the same; and electrolyte is arranged inside the first electrode, the second electrode and the third electrode.

[0006] In some embodiments, the first type of battery and the second type of battery are arranged independently of each other, and the third bipolar plate and the fourth bipolar plate are two independent bipolar plates; or, the first type of battery and the second type of battery are arranged integrally, wherein the third bipolar plate and the fourth bipolar plate are the same bipolar plate.

[0007] In some embodiments, the measuring device further comprises a seal and a pole frame, wherein the seal and the pole frame are used to seal the first type of battery and the second type of battery.

[0008] In some embodiments, the measuring device further comprises an electrochemical workstation for measuring the resistance of the first type of battery and the second type of battery.

[0009] In some embodiments, the first bipolar plate, the second bipolar plate, the third bipolar plate, the fourth bipolar plate and the fifth bipolar plate are respectively provided with connectors for connecting to a plurality of wires, and the wires are used to connect to the electrochemical workstation.

[0010] In order to solve the above technical problems, the present application also provides a contact resistance measurement method, which is applied to the above measurement device, and the measurement method includes:

[0011] The first resistance R1 of the circuit formed by the first bipolar plate and the second bipolar plate and the first electrode therebetween is measured; in the resistance test, the electrode broadly refers to an electrode system including a solid electrode and a liquid electrolyte, and the electrode resistance is the electrode system resistance.

[0012] Measuring a second resistance R2 of a circuit formed by the fourth bipolar plate and the fifth bipolar plate and the second electrode therebetween;

[0013] The third resistor R3 is measured. The third resistor R3 is an equivalent resistance of a circuit formed by connecting the first bipolar plate and the first electrode in series, connecting the third bipolar plate and the second electrode in series in parallel, and then connecting the second bipolar plate in series.

[0014] In some embodiments, the first resistor R1 , the second resistor R2 , and the third resistor R3 are measured using an electrochemical workstation according to an AC impedance method.

[0015] In some embodiments, the step of measuring the first resistance R1 of the circuit formed by the first bipolar plate and the second bipolar plate and the first electrode therebetween comprises: connecting one of the positive electrode or the negative electrode of the electrochemical workstation to the first bipolar plate, and connecting the other of the positive electrode or the negative electrode to the second bipolar plate.

[0016] In some embodiments, the first resistor R1 is calculated using the following formula: 2R b +R e +2R c ; Among them, R b represents the resistance value of any one of the first bipolar plate, the second bipolar plate, the third bipolar plate, the fourth bipolar plate and the fifth bipolar plate; R e Represents the resistance of the first electrode or the second electrode, R c Represents the contact resistance between any electrode and the corresponding bipolar plate.

[0017] In some embodiments, the step of measuring the second resistance R2 of the circuit formed by the fourth bipolar plate and the fifth bipolar plate and the second electrode therebetween comprises: connecting one of the positive electrode or the negative electrode of the electrochemical workstation to the fourth bipolar plate, and connecting the other of the positive electrode or the negative electrode to the fifth bipolar plate.

[0018] In some embodiments, the second resistor R2 is calculated using the following formula: 2R b +KR e +2R c Among them, KR e is the resistance of the third electrode, and K represents the ratio of the second thickness to the first thickness.

[0019] In some embodiments, the third resistor R3 is measured, and the third resistor R3 is the equivalent resistance of a circuit formed by connecting the first bipolar plate and the first electrode in series, and a circuit formed by connecting the third bipolar plate and the second electrode in series in parallel, and then connecting the second bipolar plate in series. The step of measuring the third resistor R3 includes: connecting one of the positive electrode or the negative electrode of the electrochemical workstation to the first bipolar plate and the third bipolar plate, and connecting the other of the positive electrode or the negative electrode to the second bipolar plate.

[0020] In some embodiments, the third resistor R3 is calculated using the following formula: b +(R b +R e +2R c ) / 2.

[0021] In some embodiments, the contact resistance is calculated by combining R1, R2, and R3.

[0022] Compared with the prior art, the present application has the following advantages: there is no need to separate the bipolar plate and the electrode during the measurement process, and there is no need to ignore certain resistance values ​​to cause large measurement errors; the measuring device contains electrolyte, forming a complete electrode system, and is an in-situ measurement, taking into account the influence of the liquid phase circuit and the electrolyte on the contact resistance. This is conducive to reducing the measurement difficulty and operation complexity of the contact resistance and improving the measurement accuracy of the contact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the present application. They are included and constitute a part of the present application. The accompanying drawings illustrate embodiments of the present application and together with the present specification serve to explain the principles of the present application. In the accompanying drawings:

[0024] Figure 1 is a schematic diagram of a measuring device provided in an embodiment of the present application.

[0025] Figure 2 is another schematic diagram of a measuring device provided by an embodiment of the present application.

[0026] Figure 3 It is a flow chart of a measurement method provided in one embodiment of the present application.

[0027] Reference numerals

[0028] Class I batteries, 100;

[0029] a first bipolar plate, 101;

[0030] a second bipolar plate, 102;

[0031] third bipolar plate, 103;

[0032] a first electrode, 104;

[0033] a second electrode, 105;

[0034] first contact surface, 106;

[0035] second contact surface, 107;

[0036] Class II batteries, 200;

[0037] fourth bipolar plate, 201;

[0038] fifth bipolar plate, 202;

[0039] third electrode, 203;

[0040] third contact surface, 204;

[0041] Seals, 300. DETAILED DESCRIPTION

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0043] As shown in this application, unless the context clearly indicates an exception, the words "a", "an", "a kind" and / or "the" do not refer to the singular, but also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0044] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0045] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0046] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0047] Flowcharts are used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed accurately in order. On the contrary, various steps may be processed in reverse order or simultaneously. At the same time, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0048] The present application provides a contact resistance measuring device for measuring the contact resistance of a flow battery electrode. The present application does not limit the type of flow battery and can be applied to all-vanadium flow batteries, iron-chromium flow batteries, zinc-bromine flow batteries, etc. The example recorded in the present application is to measure the contact resistance between a bipolar plate and an electrode. In fact, the measuring device of the present application can also be used to measure the contact resistance between electrodes and other flow battery components, which is not limited here.

[0049] like Figure 1 As shown, a contact resistance measuring device provided by the present application includes a first type battery 100 and a second type battery 200, wherein the first type battery 100 includes a first bipolar plate 101, a second bipolar plate 102, a third bipolar plate 103, a first electrode 104 and a second electrode 105, the first electrode 104 is arranged between the first bipolar plate 101 and the second bipolar plate 102, and the second electrode 105 is arranged between the second bipolar plate 102 and the third bipolar plate 103; the second type battery 200 includes a fourth bipolar plate 201, a fifth bipolar plate 202 and a third electrode 203, and the third electrode 203 is arranged between the fourth bipolar plate 201 and the fifth bipolar plate 202; wherein the first bipolar plate 101 includes a first bipolar plate 101, a second bipolar plate 102, a third bipolar plate 103, a first electrode 104 and a second electrode 105, the first electrode 104 is arranged between the first bipolar plate 101 and the second bipolar plate 102, and the second electrode 105 is arranged between the second bipolar plate 102 and the third bipolar plate 103; The first electrode 104 and the second electrode 105 have the same first thickness, the third electrode 203 has a second thickness, and the first thickness is different from the second thickness; the first electrode 104 has the same two first contact surfaces 106 as the first bipolar plate 101 and the second bipolar plate 102, respectively, and the first contact surface 106 has a first contact area; the second electrode 105 has the same two second contact surfaces 107 as the second bipolar plate 102 and the third bipolar plate 103, respectively, and the second contact surface 107 has a second contact area; the third electrode 203 has the same two third contact surfaces 204 as the fourth bipolar plate 201 and the fifth bipolar plate 202, respectively, and the third contact surface 204 has a third contact area. The first contact area, the second contact area and the third contact area are all the same; the first electrode 104, the second electrode 105 and the third electrode 203 are all provided with electrolyte.

[0050] In some embodiments, the first type of battery 100 and the second type of battery 200 refer to any electrode structure of the negative electrode structure or the positive electrode structure in the liquid flow battery. For example, the first type of battery 100 and the second type of battery 200 can be the positive electrode structure or the negative electrode structure of the all-vanadium liquid flow battery, and the positive electrode structure or the negative electrode structure of the iron-chromium liquid flow battery. The present application does not limit the type of electrolyte, and the electrolyte can be a substance that can conduct electricity in a solution in a broad sense. The electrolyte can also be a liquid containing +5-valent or +4-valent vanadium ions of the positive electrode of the all-vanadium liquid flow battery, or a liquid containing +3-valent or +2-valent vanadium ions of the negative electrode of the all-vanadium liquid flow battery, and examples are not given one by one here. Setting the electrolyte can obtain the actual contact resistance of the bipolar plate and the electrode under the influence of the electrolyte. The present application does not limit the material and shape of the bipolar plate. The first type of battery 100 and the second type of battery 200 can use bipolar plates of the same specifications, such as bipolar plates of the same material and shape, to ensure that the resistance of each bipolar plate is the same. This application does not limit the materials of the first electrode 104, the second electrode 105 and the third electrode 203. The electrodes can be metal electrode materials, carbon electrode materials and composite material electrodes. The electrodes of the same specifications (such as the same material) are used to ensure that their conductivity is the same, which is convenient for subsequent measurement. The first electrode 104 and the second electrode 105 have the same first thickness, and the third electrode 203 has a second thickness. The first thickness is different from the second thickness and is in a certain proportional relationship. The first thickness and the second thickness in a proportional relationship make the resistance of the first electrode 104 and the resistance of the third electrode 203 also have a certain proportional relationship, which is convenient for the subsequent simultaneous equations to solve the contact resistance. The proportional relationship will be explained in the subsequent content. The contact resistance is related to the contact area and pressure between the bipolar plate and the electrode. In order to facilitate measurement, the first contact area, the second contact area and the third contact area are the same. When the first contact area, the second contact area and the third contact area are the same and the pressure is the same, the first electrode 104, the second electrode 105 and the third electrode 203 are respectively formed with the corresponding bipolar plate. The contact resistance is the same. In this embodiment, the first type battery 100 and the second type battery 200 are independently arranged, and without the action of a wire, the two cannot be electrically connected. Among them, the third bipolar plate 103 and the fourth bipolar plate 201 are two independent bipolar plates.

[0051] like Figure 2 As shown, in some embodiments, the first type of battery 100 and the second type of battery 200 are integrally arranged. Since the bipolar plate is conductive, the first type of battery 100 and the second type of battery 200 can be electrically connected without the action of a wire. The third bipolar plate 103 and the fourth bipolar plate 201 are the same bipolar plate. The two settings of the first type of battery 100 and the second type of battery 200 do not affect the measurement results. Providing multiple settings can flexibly apply the device to different usage scenarios, thereby improving the applicability of the device.

[0052] In some embodiments, Figure 1 As shown, the measuring device further includes a seal 300 and a pole frame (not shown), the seal 300 and the pole frame are used to seal the first type battery 100 and the second type battery 200 to prevent leakage of electrolyte, and the pole frame can also provide structural support for the second type battery. The seal 300 and the pole frame are usually not conductive, so they will not affect the measurement results of the present device.

[0053] In some embodiments, the measuring device further includes an electrochemical workstation (not shown) for measuring the resistance of the first type battery 100 and the second type battery 200. How to measure the resistance of the first type battery 100 and the second type battery 200 will be described in the following content.

[0054] In some embodiments, the first bipolar plate 101, the second bipolar plate 102, the third bipolar plate 103, the fourth bipolar plate 201 and the fifth bipolar plate 202 are respectively provided with connectors (not shown) for connecting to a plurality of wires, and the wires are used to connect to the electrochemical workstation. Providing a connector on the bipolar plate facilitates electrical connection and helps to improve the simplicity of measurement. The connector can be fan-shaped or circular, and the specific shape of the connector is not limited in the embodiments.

[0055] The present application also provides a contact resistance measurement method, which is applied to Figure 1-Figure 2 Measuring device. Figure 3 As shown, the measurement methods include:

[0056] S100, measuring a first resistance R1 of a circuit formed by the first bipolar plate 101, the second bipolar plate 102 and the first electrode 104 therebetween;

[0057] S200, measuring a second resistance R2 of a circuit formed by the fourth bipolar plate 201 and the fifth bipolar plate 202 and the second electrode 105 therebetween;

[0058] S300, measuring the third resistor R3, which is an equivalent resistance of a circuit formed by connecting the first bipolar plate 101 and the first electrode 104 in series, a circuit formed by connecting the third bipolar plate 103 and the second electrode 105 in series in parallel, and then a circuit formed by connecting the second bipolar plate 102 in series.

[0059] In some embodiments, an electrochemical workstation is used to measure the first resistor R1, the second resistor R2 and the third resistor R3 according to the AC impedance method. The AC impedance method is a non-destructive test method that can provide information on the dynamic process of the electrode interface, and is therefore suitable for the measurement method of contact resistance of the present application. The testing principle of the AC impedance method is that the corresponding impedance value (divided into real and imaginary parts) can be obtained by changing the frequency of the electrical signal, and the ohmic resistance can be split by the image of the real and imaginary parts of the impedance (the battery test image can generally be approximated as a combination of a semicircle and a slash, and the ohmic resistance is the real value corresponding to the imaginary part when the imaginary part is zero, i.e., the left end point of the semicircle). In practical applications, the ohmic resistance can be directly obtained by the corresponding application software. In some embodiments, the voltage range of the electrochemical workstation output can be 1-10mv, and the voltage frequency can be 0.1-100kHz.

[0060] In some embodiments, the step of S100 further includes: S101, connecting one of the positive or negative electrodes of the electrochemical workstation to the first bipolar plate 101, and connecting the other of the positive or negative electrodes to the second bipolar plate 102. In the measurement method of the present application, the polarity of the first type of battery 100 and the second type of battery 200 is not distinguished, so the bipolar plate of the first type of battery 100 can be connected to any level of the electrochemical workstation. When the first bipolar plate 101 and the second bipolar plate 102 are connected to the electrochemical workstation and the measurement is started, the resistance between the first bipolar plate 101 and the second bipolar plate 102 includes: the resistance of the first bipolar plate 101, the contact resistance between the first bipolar plate 101 and the first electrode 104, the resistance of the first electrode 104, the contact resistance between the first electrode 104 and the second bipolar plate 102, and the resistance of the second bipolar plate 102. From the perspective of the equivalent circuit, the current sequentially passes through the first bipolar plate 101, the contact resistance between the first bipolar plate 101 and the first electrode 104, the first electrode 104, the contact resistance between the first electrode 104 and the second bipolar plate 102, and each part is in a series relationship. According to the series rule of resistance, the resistance values ​​of each part of R1 are summed to obtain R1.

[0061] In some embodiments, the resistance of the first bipolar plate 101 is R b , the resistance of the first electrode 104 is R e , the contact resistance between the first bipolar plate 101 and the first electrode 104 is R c , then the resistance value of R1 can be expressed as: R1 = 2R b +R e +2R c .

[0062] As mentioned above, the specifications of the bipolar plates used in the first type of battery 100 and the second type of battery 200 are the same, so it can be considered that the resistance values ​​of the first bipolar plate 101, the second bipolar plate 102, the third bipolar plate 103, the fourth bipolar plate 201 and the fifth bipolar plate 202 are the same. b represents the resistance of any one of the first bipolar plate 101, the second bipolar plate 102, the third bipolar plate 103, the fourth bipolar plate 201 and the fifth bipolar plate 202. Since the contact areas formed by the first bipolar plate 101, the second bipolar plate 102, the third bipolar plate 103, the fourth bipolar plate 201 and the fifth bipolar plate 202 and the corresponding electrodes are the same, the contact resistance values ​​are the same. Here, R is used c Represents the contact resistance between any electrode and the corresponding bipolar plate. Since the first electrode 104 and the second electrode 105 have the same material, thickness and area, R is used here. e represents the resistance of the first electrode 104 and the second electrode 105. The difference between the third electrode 203 and the first electrode 104 and the second electrode 105 is that the second thickness of the third electrode 203 is proportional to the first thickness of the first electrode 104 and the second electrode 105. The resistance of the third electrode 203 can be expressed as KR e , K is the ratio of the second thickness to the first thickness. The value of K can be any value, such as 2, 3, 4 and 0.5, etc., but the value of K cannot be equal to 1.

[0063] It should be noted that the first type of battery and the second type of battery have an electrolyte, so the electrode in the present application broadly refers to an electrode system including a solid-phase electrode and a liquid-phase electrolyte, and the electrode resistance is the electrode system resistance.

[0064] In some embodiments, step S200 further includes: step S201 , connecting one of the positive electrode or the negative electrode of the electrochemical workstation to the fourth bipolar plate 201 , and connecting the other of the positive electrode or the negative electrode to the fifth bipolar plate 202 .

[0065] In some embodiments, the third bipolar plate 103 and the fourth bipolar plate 201 may be the same bipolar plate, so step S200 also includes S202, connecting one of the positive or negative electrodes of the electrochemical workstation to the third bipolar plate 103, and connecting the other of the positive or negative electrodes to the fifth bipolar plate 202.

[0066] In some embodiments, the second resistor R2 is calculated using the following formula: R2 = 2R b +KR e +2R cFrom the perspective of the equivalent circuit, the current sequentially passes through the fourth bipolar plate 201, the contact resistance between the fourth bipolar plate 201 and the third electrode 203, the third electrode 203, the contact resistance between the third electrode 203 and the fifth bipolar plate 202, and the fifth bipolar plate 202, and each part is in a series relationship. According to the series rule of resistance, R2 can be obtained by summing the resistance values ​​of each part of R2.

[0067] In some embodiments, step S300 also includes S301, connecting one of the positive or negative electrodes of the electrochemical workstation to the first bipolar plate 101 and the third bipolar plate 103, and connecting the other of the positive or negative electrodes to the second bipolar plate 102. From the perspective of the equivalent circuit, the current flows through two parts at the same time. The first part includes: the first bipolar plate 101, the contact resistance between the first bipolar plate 101 and the first electrode 104, the first electrode 104 and the contact resistance between the first electrode 104 and the second bipolar plate 102. The second part includes: the third bipolar plate 103, the contact resistance between the third bipolar plate 103 and the second electrode 105, the second electrode 105, the second electrode 105 and the second bipolar plate 102. The first part and the second part are parallel structures. According to the parallel law of resistance, the resistance generated by the first part and the second part in parallel is half of the first part. After the current flows through the first part and the second part at the same time, it flows through the second bipolar plate 102, and after the first part and the second part are connected in parallel, they are connected in series with the second bipolar plate 102. That is, the third resistor R3 is the equivalent resistance of the circuit formed by the first bipolar plate 101 and the first electrode 104 in series, and the circuit formed by the third bipolar plate 103 and the second electrode 105 in series, and then connected in parallel with the circuit formed by the second bipolar plate 102 in series. Therefore, in some embodiments, R3 can be expressed as: R3 = R b +(R b +R e +2R c ) / 2.

[0068] In some embodiments, since only R b , R e and R c The values ​​of the three unknowns, R1, R2 and R3, can be measured by the electrochemical workstation. By combining the three equations, R can be obtained by solving the three-variable linear equation. b , R e and R c The result obtained by combining the above equations is: R e =(R2-R1) / (K-1), R b =2R3-R1, R c =(R1-2R b -R e ) / 2.

[0069] The measuring device provided by the present application does not need to separate the bipolar plate and the electrode during the measurement process, and does not need to ignore certain resistance values ​​to cause large measurement errors; the measuring device contains an electrolyte, constitutes a complete electrode system, belongs to in-situ measurement, and takes into account the influence of the liquid phase circuit and the electrolyte on the contact resistance. It is conducive to reducing the measurement difficulty and operation complexity of the contact resistance and improving the measurement accuracy of the contact resistance.

[0070] The following provides a test example and a comparative example in an experimental process to illustrate the actual effect of the present application.

[0071] During the experiment, the test case selected a 2cm*2cm electrode, a compression rate of 35%, a pressure of 0.1Mpa, a porosity of 0.92 after compression, a thickness of 1.7mm for the first electrode 104 and a thickness of 3.4mm for the third electrode 203 after compression, and a K value of 2. The electrolyte used in the test was a vanadium sulfate electrolyte, with an average vanadium valence of 3.5 and a concentration of 1.7mol / L.

[0072] The electrochemical workstation test results show that: R1 = 17.4mΩ; R2 = 21.6mΩ; R3 = 10.3mΩ. By calculation, Rb = 2R3-R1 = 2*10.3-17.4 = 3.2mΩ; Re = (R2-R1) / (K-1) = (21.6-17.4) / (2-1) = 4.2mΩ; Rc = (R1-2R b -R e ) / 2=(17.4-2*3.2-4.2) / 2=3.4mΩ. Contact resistance R related to contact area c *A=3.4*4=13.6mΩ*cm 2 .

[0073] The comparative example adopts the measurement method described in NB / T 42007-2013 mentioned in the background technology and is tested under the test conditions of the test example of this application. The contact resistance R is measured at a pressure of 0.1 MPa. c 10.2 mΩ·cm 2 .

[0074] It can be seen from the results of the test examples and the comparative examples that, under the same measurement conditions, the measurement results achieved by the present application are more accurate.

[0075] The basic concepts have been described above. Obviously, for those skilled in the art, the above application disclosure is only an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0076] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0077] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more embodiments of the invention, in the above description of the embodiments of the present application, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the subject of the present application requires more features than the features mentioned. In fact, the features of the embodiment are less than all the features of the single embodiment disclosed above.

[0078] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in this application are approximate values, which may change according to the required characteristics of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining the digits. Although the numerical domains and parameters used to confirm the breadth of the range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

Claims

1. A contact resistance measuring device for measuring the contact resistance of a flow battery electrode, characterized in that: It includes first type batteries and second type batteries, wherein: The first type of battery includes a first bipolar plate, a second bipolar plate, a third bipolar plate, a first electrode and a second electrode, the first electrode is arranged between the first bipolar plate and the second bipolar plate, and the second electrode is arranged between the second bipolar plate and the third bipolar plate; The second type of battery includes a fourth bipolar plate, a fifth bipolar plate and a third electrode, wherein the third electrode is disposed between the fourth bipolar plate and the fifth bipolar plate; The first electrode and the second electrode have the same first thickness, the third electrode has a second thickness, and the first thickness is different from the second thickness; The first electrode has the same first contact area with the first bipolar plate and the second bipolar plate, the second electrode has the same second contact area with the second bipolar plate and the third bipolar plate, the third electrode has the same third contact area with the fourth bipolar plate and the fifth bipolar plate, and the first contact area, the second contact area and the third contact area are all the same; Electrolyte is disposed inside the first electrode, the second electrode and the third electrode.

2. The measuring device according to claim 1, characterized in that The first type of battery and the second type of battery are arranged independently of each other, and the third bipolar plate and the fourth bipolar plate are two independent bipolar plates; or, the first type of battery and the second type of battery are arranged integrally, wherein the third bipolar plate and the fourth bipolar plate are the same bipolar plate.

3. The measuring device according to claim 1 or 2, characterized in that It also includes a seal and a pole frame, and the seal and the pole frame are used to seal the first type of battery and the second type of battery.

4. The measuring device according to claim 1, characterized in that Also included is an electrochemical workstation for measuring the resistance of the first type of battery and the second type of battery.

5. The measuring device according to claim 4, characterized in that The first bipolar plate, the second bipolar plate, the third bipolar plate, the fourth bipolar plate and the fifth bipolar plate are respectively provided with connectors for connecting to a plurality of wires, and the wires are used to connect to the electrochemical workstation.

6. A method for measuring contact resistance, applied to the measuring device according to any one of claims 1 to 5, characterized in that: The measuring method comprises: measuring a first resistance R1 of a circuit formed by the first bipolar plate, the second bipolar plate and the first electrode therebetween; measuring a second resistance R2 of a circuit formed by the second electrode between the fourth bipolar plate and the fifth bipolar plate; The third resistor R3 is measured. The third resistor R3 is an equivalent resistance of a circuit formed by connecting the first bipolar plate and the first electrode in series, a circuit formed by connecting the third bipolar plate and the second electrode in series in parallel, and then a circuit formed by connecting the second bipolar plate in series.

7. The measuring method according to claim 6, characterized in that: The first resistor R1, the second resistor R2 and the third resistor R3 are measured by an electrochemical workstation according to an AC impedance method.

8. The measuring method according to claim 7, characterized in that: The step of measuring a first resistance R1 of a circuit formed by the first bipolar plate, the second bipolar plate and the first electrode therebetween comprises: One of the positive electrode or the negative electrode of the electrochemical workstation is connected to the first bipolar plate, and the other of the positive electrode or the negative electrode is connected to the second bipolar plate.

9. The measuring method according to claim 8, characterized in that: The first resistor R1 is calculated using the following formula: 2R b +R e +2R c ; Among them, R b represents the resistance value of any one of the first bipolar plate, the second bipolar plate, the third bipolar plate, the fourth bipolar plate and the fifth bipolar plate; R e represents the resistance of the first electrode or the second electrode, R c Represents the contact resistance between any electrode and the corresponding bipolar plate.

10. The measuring method according to claim 9, characterized in that: The step of measuring a second resistance R2 of a circuit formed by the second electrode between the fourth bipolar plate and the fifth bipolar plate comprises: One of the positive electrode or the negative electrode of the electrochemical workstation is connected to the fourth bipolar plate, and the other of the positive electrode or the negative electrode is connected to the fifth bipolar plate.

11. The measuring method according to claim 10, characterized in that: The second resistor R2 is calculated using the following formula: 2R b +KR e +2R c ; Among them, KR e is the resistance of the third electrode, and K represents the ratio of the second thickness to the first thickness.

12. The measuring method according to claim 11, characterized in that: The step of measuring the third resistor R3 comprises: One of the positive electrode or the negative electrode of the electrochemical workstation is connected to the first bipolar plate and the third bipolar plate, and the other of the positive electrode or the negative electrode is connected to the second bipolar plate.

13. The measuring method according to claim 12, characterized in that: The third resistor R3 is calculated using the following formula: b +(R b +R e +2R c ) / 2.

14. The measuring method according to any one of claims 13, characterized in that: The contact resistance is calculated by combining R1, R2 and R3.

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