Electrolytic cell and exchange current density testing method

Abstract

The invention relates to the technical field of electrolytic tanks, and provides an electrolytic tank and an exchange current density testing method.The electrolytic tank comprises an electrolytic tank container, a working electrode, a reference electrode and a counter electrode, and the electrolytic tank container is filled with electrolyte; the working electrode, the reference electrode and the counter electrode are all inserted into the electrolytic tank container and are completely immersed into the electrolyte; the area of the reference electrode is equal to that of the counter electrode, and the area of the working electrode is smaller than that of the counter electrode. According to the invention, the test accuracy and the electrochemical reaction stability can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic cells, and in particular to an electrolytic cell and a test method for exchange current density. Background Art

[0002] As lithium-ion batteries become a research hotspot in social development, the booming electric vehicle industry has put forward more stringent requirements for battery performance, such as long cycle life, fast charging capability and safety over a wide temperature range. Electrolytes play a vital role in electrochemical systems and are required to transfer ions and maintain electrode reactions. The exchange current density is a descriptive indicator of the anode and cathode reaction rates at electrochemical equilibrium, and is a constant that describes the electrode-electrolyte interface reaction rate. The exchange current density is defined as the rate of the positive reaction occurring on the electrode surface per unit area in the absence of an applied voltage, representing the intrinsic rate of the electrode reaction in a thermodynamic equilibrium state. The exchange current density is a key parameter for describing the electrochemical reaction rate and is of great significance for understanding and optimizing the performance of electrochemical mechanical systems.

[0003] At present, the exchange current density is mainly tested using a two-electrode buckle symmetrical battery. The buckle symmetrical battery is composed of a steel sheet-diaphragm-steel sheet and is easy to prepare. However, the reference electrode and the counter electrode of the buckle symmetrical battery are the same electrode, and the reaction stability is poor. During the assembly process of the buckle symmetrical battery, the position of the steel sheet cannot be completely aligned, resulting in poor area consistency. At the same time, there is a problem of polarization due to small differences in area ratios, which leads to poor accuracy of the test results. Summary of the invention

[0004] The present invention provides an electrolytic cell and a test method for exchange current density, which are used to solve the defects in the prior art that the reference electrode and the counter electrode of the buckled symmetrical battery are the same electrode, the reaction stability is poor, and during the assembly process of the buckled symmetrical battery, the positions of the steel sheets cannot be completely aligned, resulting in poor area consistency, and there is also a problem of polarization due to small differences in area ratios, which leads to poor accuracy of the test results.

[0005] The present invention provides an electrolytic cell, comprising: an electrolytic cell container, a working electrode, a reference electrode and a counter electrode, wherein: The electrolytic cell container is filled with an electrolyte; the working electrode, the reference electrode and the counter electrode are all inserted into the electrolytic cell container and completely immersed in the electrolyte; The area of ​​the reference electrode is equal to the area of ​​the counter electrode, and the area of ​​the working electrode is smaller than the area of ​​the counter electrode.

[0006] According to the electrolytic cell provided by the present invention, the ratio of the area of ​​the working electrode to the area of ​​the counter electrode is less than 0.009.

[0007] The electrolytic cell provided according to the present invention further includes three connecting rods, and the working electrode, the reference electrode and the counter electrode are all provided with protrusions, and the working electrode, the reference electrode and the counter electrode are all welded to their corresponding connecting rods through the protrusions.

[0008] According to the electrolytic cell provided by the present invention, the electrolytic cell container is provided with connecting holes and inert gas through holes, each of the connecting rods is inserted into the corresponding connecting hole, the connecting rods and the connecting holes, and the inert gas through holes and the electrolytic cell container are sealed by sealing rings, and the inert gas through holes are used to introduce inert gas into the electrolyte in the electrolytic cell container.

[0009] According to the electrolytic cell provided by the present invention, the corresponding center positions of the working electrode, the reference electrode and the counter electrode are on the same horizontal line.

[0010] The electrolytic cell provided according to the present invention further comprises a connecting fixture, wherein the connecting fixture connects the connecting rods corresponding to the working electrode, the reference electrode and the counter electrode, respectively, and an electrochemical workstation.

[0011] The present invention also provides a method for testing exchange current density, which is applied to an electrochemical workstation, and the method comprises: Performing an LSV test on the electrolytic cell as described in any one of the above items to determine a test curve corresponding to the electrolytic cell; the test curve is used to characterize the correlation between the logarithm of the current density and the overpotential of the electrode in the electrolytic cell; Based on the test curve, the exchange current density of the electrolyte in the electrolytic cell is determined.

[0012] According to the test method for exchange current density provided by the present invention, determining the exchange current density of the electrolyte in the electrolytic cell based on the test curve comprises: Determine the inflection point interval in the test curve; Performing a linear fit on the data outside the inflection point interval on the test curve to determine the intercept corresponding to the fitting curve; Based on the intercept, the exchange current density of the electrolyte in the electrolytic cell is determined.

[0013] The present invention also provides an electrochemical workstation, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements any of the above-mentioned exchange current density testing methods when executing the computer program.

[0014] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the test method for the exchange current density as described in any one of the above is implemented.

[0015] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the computer program implements any of the above-mentioned methods for testing exchange current density.

[0016] The present invention provides an electrolytic cell and a test method for exchange current density. A three-electrode system is used in the electrolytic cell, and includes a working electrode, a reference electrode and a counter electrode. The three electrodes are completely immersed in an electrolyte in a container of the electrolytic cell. The reference electrode in the three-electrode system is used to more accurately control and measure the potential of the working electrode. The counter electrode provides a sufficient electron exchange area. The area of ​​the reference electrode is equal to the area of ​​the counter electrode, thereby ensuring the balance and stability of the electrochemical reaction. At the same time, the area of ​​the working electrode is smaller than that of the counter electrode, thereby reducing the polarization phenomenon caused by mismatch of the electrode areas, thereby improving the test accuracy and the stability of the electrochemical reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the structure of the electrolytic cell provided in an embodiment of the present invention.

[0019] Figure 2 Schematic diagram of a bump provided by an embodiment of the present invention.

[0020] Figure 3 It is a flow chart of a method for testing exchange current density provided in an embodiment of the present invention.

[0021] Figure 4 It is a schematic diagram of a test curve provided by an embodiment of the present invention.

[0022] Figure 5 It is a schematic diagram of the structure of the exchange current density testing device provided in an embodiment of the present invention.

[0023] Figure 6 It is a schematic diagram of the structure of an electrochemical workstation provided in an embodiment of the present invention.

[0024] Reference numerals: 110: electrolytic cell container; 120: working electrode; 130: reference electrode; 140: counter electrode; 150: bump; 160: connecting rod; 170: connecting hole; 180: inert gas through hole; 190: sealing ring. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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 are within the scope of protection of the present invention.

[0026] In view of the fact that the reference electrode and the counter electrode of the button-type symmetrical battery in the prior art are the same electrode, the reaction stability is poor, and during the assembly process of the button-type symmetrical battery, the steel sheet positions cannot be completely aligned, resulting in poor area consistency. At the same time, there is a problem of polarization effect caused by small area ratio differences, which in turn leads to poor accuracy of test results. An embodiment of the present invention provides an electrolytic cell, Figure 1 1 is one of the structural schematic diagrams of the electrolytic cell provided in the embodiment of the present invention, such as Figure 1 As shown, the electrolytic cell comprises: an electrolytic cell container 110, a working electrode 120, a reference electrode 130 and a counter electrode 140, wherein: The electrolytic cell container 110 is filled with an electrolyte; the working electrode 120, the reference electrode 130 and the counter electrode 140 are all inserted into the electrolytic cell container 110 and are completely immersed in the electrolyte; The area of ​​the reference electrode 130 is equal to the area of ​​the counter electrode 140 , and the area of ​​the working electrode 120 is smaller than the area of ​​the counter electrode 140 .

[0027] In the embodiment of the present invention, a three-electrode system is used in the electrolytic cell, including a working electrode 120 (Working Electrode, WE), a reference electrode 130 (Reference Electrode, RE) and a counter electrode 140 (Counter Electrode, CE), wherein: (1) The working electrode 120 is the electrode to be studied in the electrochemical reaction. The electrochemical reaction occurs on the working electrode 120, that is, the working electrode 120 can participate in the electrochemical reaction as an anode or a cathode. The electrochemical reaction can be a charge transfer reaction and a redox reaction. The working electrode 120 can be an electrode material to be studied or an inert electrode.

[0028] (2) The reference electrode 130 is used to provide a stable potential reference for the working electrode 120. The reference electrode 130 is generally an electrode having a stable and reversible electrochemical reaction, and the reference electrode 130 can be a lithium electrode, a saturated calomel electrode, a silver electrode, or a silver chloride electrode.

[0029] (3) The counter electrode 140, also known as the auxiliary electrode, is used to complete the electron transfer in the circuit. That is, it provides a corresponding electron source or sink for the electrochemical reaction occurring on the working electrode 120. For example, when an oxidation reaction occurs on the working electrode 120, a reduction reaction occurs on the counter electrode 140, and when a reduction reaction occurs on the working electrode 120, an oxidation reaction occurs on the counter electrode 140. The electron transfer on the counter electrode 140 matches the electron transfer on the working electrode 120, ensuring the charge balance of the entire electrochemical reaction. The counter electrode 140 can be made of platinum wire material or other inert materials.

[0030] The three electrodes are inserted into the electrolytic cell container 110 of the electrolytic cell, and the electrolytic cell container 110 can be made of glass or plastic. The electrolytic cell container 110 is filled with an electrolyte, which can be a high-purity electrolyte. The liquid level of the electrolyte is sufficient to cover the effective area of ​​all electrodes, that is, the three electrodes are completely immersed in the electrolyte. The absolute value of the distance between the highest position of the pair of electrodes 140 and the electrolyte liquid level is greater than a first preset threshold, and the absolute value of the distance between the lowest position of the pair of electrodes 140 and the bottom of the electrolytic cell container 110 is greater than a second preset threshold, that is, the lowest position of the pair of electrodes 140 does not contact the bottom of the electrolytic cell container 110.

[0031] It should be noted that the first preset threshold is the lower limit of the absolute value of the distance between the highest position of the counter electrode 140 and the electrolyte surface, and the second preset threshold is the lower limit of the absolute value of the distance between the lowest position of the counter electrode 140 and the bottom of the electrolytic cell container 110. The first preset threshold and the second preset threshold are both values ​​greater than 0, and the sum of the first preset threshold, the second preset threshold and the height of the counter electrode 140 must be less than or equal to the height of the electrolytic cell container 110. The first preset threshold and the second preset threshold can be set based on experience. For example, the first preset threshold can be 0.1 cm, 0.2 cm or 0.5 cm, etc., and the second preset threshold can be 0.1 cm, 0.15 cm or 0.2 cm, etc., and the embodiment of the present invention does not limit this.

[0032] In the three-electrode system, the area of ​​the working electrode 120 is set to be smaller than the area of ​​the counter electrode 140. The current density on the working electrode 120 can be increased by the smaller area of ​​the working electrode 120, while the area of ​​the counter electrode 140 is larger, that is, the current density on the counter electrode 140 remains low, thereby reducing the polarization effect of the counter electrode 140 and improving the test accuracy of the working electrode 120. In addition, if the area of ​​the reference electrode 130 is too large relative to the area of ​​the counter electrode 140, additional potential changes may be introduced in the electrolytic cell, thereby affecting the accurate measurement of the potential of the working electrode 120. In an embodiment of the present invention, the area of ​​the reference electrode 130 is set to be equal to the area of ​​the counter electrode 140, which can minimize this effect. At the same time, if the area of ​​the counter electrode 140 is too small, the counter electrode 140 may not provide enough electrons to support the charge transfer on the working electrode 120, thereby limiting the speed of the electrochemical reaction. In the embodiment of the present invention, by setting the area of ​​the counter electrode 140 to be equal to the area of ​​the reference electrode 130, a sufficiently large surface of the counter electrode 140 can be provided to receive or provide corresponding electrons, thereby maintaining the symmetry of the electrochemical reaction and reducing the polarization effect caused by uneven current density on the electrode surface.

[0033] It should be noted that the polarization effect refers to the phenomenon that the electrode potential deviates from the equilibrium potential due to charge accumulation on the electrode surface or consumption of reactants. The polarization effect will cause deviations in electrochemical measurements.

[0034] Furthermore, the ratio of the area of ​​the working electrode 120 to the area of ​​the counter electrode 140 is less than 0.009.

[0035] In the embodiment of the present invention, the area of ​​the working electrode 120 is set to be much smaller than the area of ​​the counter electrode 140. By optimizing the electrode area ratio, the current distribution between the working electrode 120 and the counter electrode 140 is optimized, thereby relatively reducing the current density on the working electrode 120, reducing the polarization phenomenon, and thus improving the accuracy and stability of the test. That is, when the total current remains unchanged, since the area of ​​the working electrode 120 is small, even a very small current will produce a relatively high current density. Since the counter electrode 140 has a large area, most of the current flows on the counter electrode 140 during the electrolysis process, and the current distribution on the counter electrode 140 is more uniform, thereby making the current density on the counter electrode 140 relatively small.

[0036] Furthermore, the electrolytic cell also includes three connecting rods 160 , and the working electrode 120 , the reference electrode 130 and the counter electrode 140 are all provided with bumps 150 , and the working electrode 120 , the reference electrode 130 and the counter electrode 140 are all welded to their corresponding connecting rods 160 through the bumps 150 .

[0037] Specifically, Figure 2Schematic diagram of the bump provided by the embodiment of the present invention, such as Figure 2 As shown, the edges of the working electrode 120, the reference electrode 130 and the counter electrode 140 are all provided with protrusions 150, and the connecting rod 160 can be a polytetrafluoroethylene rod. When each connecting rod 160 is welded to each electrode through the protrusion 150, the polytetrafluoroethylene material can be hot-melted and connected to the protrusion 150 corresponding to each electrode to ensure that each electrode is fixedly connected to the connecting rod 160, avoid changes in the electrode area due to improper electrode clamping or position displacement, reduce test errors caused by inaccurate electrode position, ensure the consistency of the electrode area, and make the measurement results more accurate and reliable.

[0038] Optionally, the width and height of bump 150 may be set based on experience, and the width of bump 150 may range from [0.1mm, 1mm], for example, the width of bump 150 may be 0.5mm, and the height of bump 150 may range from [0.1mm, 1mm], for example, the height of bump 150 may be 0.5mm.

[0039] Furthermore, the corresponding center positions of the working electrode 120 , the reference electrode 130 , and the counter electrode 140 are on the same horizontal line.

[0040] Specifically, in an electrochemical reaction, the current needs to form a loop between the working electrode 120 and the counter electrode 140. In the embodiment of the present invention, after the corresponding center positions of the working electrode 120, the reference electrode 130 and the counter electrode 140 are on the same horizontal line, it can be ensured that the current path is clear and relatively short, reducing the loss and interference of the current during the transmission process. In addition, the corresponding center positions of the three electrodes are on the same horizontal line, which can make the electric field distribution relatively uniform, avoid experimental errors caused by uneven electric field distribution, and thus improve the accuracy and reliability of the test.

[0041] Furthermore, the electrolytic cell container 110 is provided with connecting holes 170 and inert gas through holes 180, and each connecting rod 160 is inserted into the corresponding connecting hole 170. The connecting rod 160 and the connecting hole 170, as well as the inert gas through hole 180 and the electrolytic cell container 110 are sealed by a sealing ring 190. The inert gas through hole 180 is used to introduce inert gas into the electrolyte in the electrolytic cell container 110.

[0042] Specifically, long-term placement of the electrolyte in the electrolytic cell container 110 may lead to oxidation of the electrolyte. Therefore, in the embodiment of the present invention, all joints in the electrolytic cell container 110 are provided with sealing rings 190, that is, the joints between the connecting hole 170 on the electrolytic cell container 110 and the connecting rod 160 are sealed by the sealing ring 190, and the joints between the inert gas through hole 180 provided on the electrolytic cell container 110 and the electrolytic cell container 110 are also sealed by the sealing ring 190, and the inert gas through hole 180 is continuously introduced into the electrolyte, and the sealing effect of the electrolytic cell container 110 is improved by the sealing ring 190, so as to achieve deoxidation treatment of the electrolyte.

[0043] Optionally, the inert gas through hole 180 includes an inert gas inlet and an inert gas outlet, and the inert gas can be continuously introduced into the electrolytic cell container 110 through the inert gas inlet, and the rate of the inert gas can be less than 3 mL / min. It should be noted that the rate of the inert gas during the test is less than the rate of the inert gas before the test. In addition, the inert gas in the electrolytic cell container 110 can also be discharged through the inert gas outlet.

[0044] In the embodiment of the present invention, the assembly of the electrolytic cell includes the following steps S1 to S4.

[0045] S1. Prepare electrodes

[0046] S1.1. Clean the working electrode 120: Use a suitable solvent (such as ethanol, deionized water, etc.) to clean the surface of the working electrode 120. Polishing can be performed if necessary. The polishing material can be aluminum oxide or sandpaper. The particle size of the polishing material is less than 100 mesh. The polishing time can be greater than 30 minutes. Polishing can be stopped when the surface is clean and there is no obvious oxide layer. Cleaning the working electrode 120 is conducive to improving the accuracy and consistency of the test.

[0047] S1.2. Prepare a reference electrode 130 , which is clean and has no oxide layer.

[0048] S1.3. Prepare a counter electrode 140, which is clean and has no oxide layer.

[0049] S2. Configure the electrolytic cell

[0050] S2.1. Introduce the electrolyte into the electrolytic cell container 110, and ensure that the electrolyte level is sufficient to cover the effective areas of all electrodes.

[0051] S2.2. Weld the working electrode 120, the reference electrode 130 and the counter electrode 140 to the corresponding connecting rods 160 respectively, and insert each electrode into the connecting hole 170 so that all electrodes are completely immersed in the electrolyte and do not touch the cell wall, and adjust the height of each electrode so that the center positions of the three electrodes are on the same horizontal line.

[0052] S3, deoxygenation treatment

[0053] Inert gas is continuously introduced into the electrolyte for sampling, and the rate of inert gas introduction is less than 3 mL / min.

[0054] S4. Eliminate bubbles

[0055] If there are bubbles in the electrolyte attached to the surface of each electrode, you can gently shake the electrode or extract it with a syringe to eliminate the bubbles.

[0056] Furthermore, it also includes a connecting fixture, which connects the connecting rods 160 corresponding to the working electrode 120, the reference electrode 130 and the counter electrode 140, and the electrochemical workstation.

[0057] Before electrolysis, the three motors and the electrochemical workstation can be connected separately using a connection fixture. After setting the test mode and test parameters, the electrolyte can be tested.

[0058] The electrolytic cell provided by the embodiment of the present invention adopts a three-electrode system, and includes a working electrode, a reference electrode and a counter electrode. The three electrodes are completely immersed in the electrolyte in the electrolytic cell container. The reference electrode in the three-electrode system is used to more accurately control and measure the potential of the working electrode. The counter electrode provides sufficient electron exchange area. The area of ​​the reference electrode is equal to the area of ​​the counter electrode, ensuring the balance and stability of the electrochemical reaction. At the same time, the area of ​​the working electrode is smaller than that of the counter electrode, reducing the polarization effect caused by the mismatch of the electrode areas, thereby improving the test accuracy and stability.

[0059] The embodiment of the present invention also provides a method for testing exchange current density, which is applied to an electrochemical workstation. Figure 3 is a flow chart of a method for testing exchange current density provided by an embodiment of the present invention, such as Figure 3 As shown, the method includes the following steps 310 and 320.

[0060] Step 310: Perform an LSV (Linear Sweep Voltammetry) test on the electrolytic cell as described in any of the above items to determine a test curve corresponding to the electrolytic cell; the test curve is used to characterize the correlation between the logarithm of the current density and the overpotential of the electrode in the electrolytic cell.

[0061] Specifically, after the assembled electrolytic cell is connected by the connection fixture and before the test, preliminary experiments such as open circuit voltage (OCV) measurement can be performed to ensure the system stability of the electrochemical workstation. After that, check whether the electrode connection is normal and whether the electrochemical workstation reading is reasonable. After that, the LSV test mode and related test parameters can be configured to perform LSV test on the electrolytic cell. The electrochemical workstation can record data to obtain the test curve.

[0062] It should be noted that the test curve is determined based on the Butler-Volmer equation, which can reflect the relationship between the reaction rate and potential of the electrode reaction. In the test curve, the horizontal axis represents the overpotential of the electrode, and the vertical axis represents the logarithm of the current density. The test curve is a symmetrical curve with the vertical axis as the symmetry axis. In the electrolytic cell of the three-electrode system, the Butler-Volmer equation corresponding to the electrolysis process is shown in formula (1), which is:

[0063] Where j represents the current density of the electrode, is the current density at the anode, is the cathode current density, is the exchange current density, represents the asymmetry factor, n represents the concentration of the substance, F represents the Faraday constant, R represents the gas constant, and , T represents temperature, represents the overpotential of the electrode.

[0064] Based on the Butler-Volmer equation, for the cathode or anode, , after taking the logarithm with base 10, we get After simplifying the formula, the fitting equation corresponding to the test curve can be determined as ,in, represents the logarithm of the current density, A represents the intercept of the fitting equation, and B represents the slope of the fitting equation.

[0065] Optionally, the test parameters may include a scan voltage and a scan speed, etc. The scan may gradually change from an open circuit voltage to -1 V, and the scan speed may be less than 1 mV / s.

[0066] Step 320: Determine the exchange current density of the electrolyte in the electrolytic cell based on the test curve.

[0067] After the test curve is determined, the second derivative of the test curve is calculated to further calculate the exchange current density of the electrolyte.

[0068] Further, based on the test curve, the exchange current density of the electrolyte in the electrolytic cell is determined, including: Determine the inflection point interval in the test curve; Performing a linear fit on the data outside the inflection point interval on the test curve to determine the intercept corresponding to the fitting curve; Based on the intercept, the exchange current density of the electrolyte in the electrolytic cell is determined.

[0069] Specifically, after determining the test curve, the secondary derivative of the data within the target voltage range in the test curve can be calculated, and the coordinate point with the largest absolute value of the secondary derivative on the test curve is determined as the inflection point. Since the test curve is a symmetrical curve, two inflection points can be calculated, and the absolute values ​​of the horizontal coordinates corresponding to the two inflection points are equal and opposite in sign. After determining the two inflection points, the horizontal coordinates of the two inflection points are used as the upper limit and the lower limit, respectively, to form the inflection point interval. The data on the test curve outside the inflection point interval are linearly fitted to obtain two fitting curves with the vertical axis as the axis of symmetry, and the two fitting curves intersect at one point on the vertical axis. The distance between this point and the coordinate origin is determined as the intercept corresponding to the fitting curve, and the intercept is the logarithm of the exchange current density. The exchange current density can be determined by calculating the antilogarithm of the intercept.

[0070] In addition, after fitting to the fitting curve, the absolute values ​​of the slopes of the two fitting curves are equal and have opposite signs. The absolute value of the slope is the Tafel slope. Through the Tafel slope, we can further understand the kinetic characteristics of the electrochemical reaction and the differences in material properties.

[0071] Optionally, the target voltage range may be set based on experience, for example, may be [-500 mV, 500 mV], which is not limited in the embodiment of the present invention.

[0072] For example, Figure 4 is a schematic diagram of a test curve provided by an embodiment of the present invention, such as Figure 4 As shown, the inflection point 1 and the inflection point 2 within the target voltage range of [-500mV, 500mV] are calculated, and the abscissas of the inflection point 1 and the inflection point 2 constitute the inflection point interval [g1, g2]. The data with abscissas less than g1 on the test curve are linearly fitted to obtain the fitting curve 1. At the same time, the data with abscissas greater than g2 on the test curve are linearly fitted to obtain the fitting curve 2. The fitting curve 1 and the fitting curve 2 intersect at one point on the vertical axis, and the vertical coordinate of the intersection is determined as the intercept, and the intercept is 0.065. By taking the antilogarithm of the intercept, the exchange current density can be determined to be 1.16mA / cm 2 . Calculate the slope of fitting curve 1 or fitting curve 2, which is the Tafel slope, and the Tafel slope is 0.985.

[0073] The test method for exchange current density provided by the embodiment of the present invention combines the electrolytic cell of the three-electrode system and the LSV test, and the test operation is simple and convenient, and the accuracy of the calculated exchange current density is improved by improving the collection accuracy of the test data.

[0074] The test device for exchange current density provided by the present invention is described below. The test device for exchange current density described below and the test method for exchange current density described above can be referred to each other.

[0075] Figure 5 is a schematic diagram of the structure of the exchange current density test device provided by an embodiment of the present invention, such as Figure 5 As shown, the exchange current density testing device 500 includes a testing module 510 and a determining module 520 .

[0076] The test module 510 is used to perform an LSV test on the electrolytic cell as described in any of the above items to determine a test curve corresponding to the electrolytic cell; the test curve is used to characterize the correlation between the logarithm of the current density and the overpotential of the electrode in the electrolytic cell.

[0077] The determination module 520 is used to determine the exchange current density of the electrolyte in the electrolytic cell based on the test curve.

[0078] Optionally, the determining module 520 is specifically configured to: Determine the inflection point interval in the test curve; Performing a linear fit on the data outside the inflection point interval on the test curve to determine the intercept corresponding to the fitting curve; Based on the intercept, the exchange current density of the electrolyte in the electrolytic cell is determined.

[0079] Figure 6 Schematic diagram of the structure of the electrochemical workstation provided by the embodiment of the present invention. Figure 6 As shown, the electrochemical workstation may include: a processor 610, a communications interface 620, a memory 630 and a communication bus 640, wherein the processor 610, the communications interface 620 and the memory 630 communicate with each other through the communication bus 640. The processor 610 may call the logic instructions in the memory 630 to execute the test method of the exchange current density, and the method includes: Performing an LSV test on the electrolytic cell as described in any one of the above items to determine a test curve corresponding to the electrolytic cell; the test curve is used to characterize the correlation between the logarithm of the current density and the overpotential of the electrode in the electrolytic cell; Based on the test curve, the exchange current density of the electrolyte in the electrolytic cell is determined.

[0080] In addition, the logic instructions in the above-mentioned memory 630 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0081] On the other hand, the present invention further provides a computer program product, the computer program product includes a computer program, the computer program can be stored in a non-transitory computer-readable storage medium, when the computer program is executed by a processor, the computer can execute the exchange current density test method provided by the above methods, the method comprising: Performing an LSV test on the electrolytic cell as described in any one of the above items to determine a test curve corresponding to the electrolytic cell; the test curve is used to characterize the correlation between the logarithm of the current density and the overpotential of the electrode in the electrolytic cell; Based on the test curve, the exchange current density of the electrolyte in the electrolytic cell is determined.

[0082] In another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the computer program is executed by a processor to perform the test method for the exchange current density provided by the above methods, the method comprising: Performing an LSV test on the electrolytic cell as described in any one of the above items to determine a test curve corresponding to the electrolytic cell; the test curve is used to characterize the correlation between the logarithm of the current density and the overpotential of the electrode in the electrolytic cell; Based on the test curve, the exchange current density of the electrolyte in the electrolytic cell is determined.

[0083] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, i.e., they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative effort.

[0084] Through the description of the above implementation modes, those skilled in the art can clearly understand that each implementation mode can be implemented by means of software plus a necessary general hardware platform, or of course by hardware. Based on such an understanding, the above technical solution can essentially or in other words be embodied in the form of a software product that contributes to the prior art. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of each embodiment or some parts of the embodiment.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrolytic cell, characterized in that include: Electrolytic cell container, working electrode, reference electrode and counter electrode, where: The electrolytic cell container is filled with an electrolyte; the working electrode, the reference electrode and the counter electrode are all inserted into the electrolytic cell container and completely immersed in the electrolyte; The area of ​​the reference electrode is equal to the area of ​​the counter electrode, and the area of ​​the working electrode is smaller than the area of ​​the counter electrode.

2. The electrolytic cell according to claim 1, characterized in that The ratio of the area of ​​the working electrode to the area of ​​the counter electrode is less than 0.

009.

3. The electrolytic cell according to claim 1, characterized in that It also includes three connecting rods. The working electrode, the reference electrode and the counter electrode are all provided with convex points. The working electrode, the reference electrode and the counter electrode are all welded to the corresponding connecting rods through the convex points.

4. The electrolytic cell according to claim 3, characterized in that The electrolytic cell container is provided with connecting holes and inert gas through holes, each of the connecting rods is inserted into the corresponding connecting hole, the connecting rods and the connecting holes, as well as the inert gas through holes and the electrolytic cell container are sealed by sealing rings, and the inert gas through holes are used to introduce inert gas into the electrolyte in the electrolytic cell container.

5. The electrolytic cell according to any one of claims 1 to 4, characterized in that The corresponding center positions of the working electrode, the reference electrode and the counter electrode are respectively on the same horizontal line.

6. The electrolytic cell according to any one of claims 1 to 4, characterized in that It also includes a connecting fixture, which connects the connecting rods corresponding to the working electrode, the reference electrode and the counter electrode, and an electrochemical workstation.

7. A method for testing exchange current density, characterized in that: Applied to an electrochemical workstation, the method comprises: Performing an LSV test on the electrolytic cell according to any one of claims 1 to 6 to determine a test curve corresponding to the electrolytic cell; the test curve is used to characterize the correlation between the logarithm of the current density and the overpotential of the electrode in the electrolytic cell; Based on the test curve, the exchange current density of the electrolyte in the electrolytic cell is determined.

8. The method for testing exchange current density according to claim 7, characterized in that: Determining the exchange current density of the electrolyte in the electrolytic cell based on the test curve comprises: Determine the inflection point interval in the test curve; Performing a linear fit on the data outside the inflection point interval on the test curve to determine the intercept corresponding to the fitting curve; Based on the intercept, the exchange current density of the electrolyte in the electrolytic cell is determined.

9. An electrochemical workstation, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for testing the exchange current density as claimed in claim 7 or 8 is implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for testing the exchange current density as claimed in claim 7 or 8 is implemented.

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