Method and device for evaluating ion barrier or adsorption performance of diaphragm

Abstract

The invention provides a method and a device for evaluating the ion blocking or adsorption performance of a diaphragm. The evaluation method comprises the following steps: providing a first chamber and a second chamber which form an ion migration channel through a diaphragm to be tested; injecting an electrolyte into the first chamber and the second chamber respectively, wherein the electrolyte in the first chamber or the electrolyte in the second chamber contains target ions; setting a potential difference between the first chamber and the second chamber so as to drive the target ions to directionally migrate to pass through the diaphragm to be detected; parameters are measured, evaluation indexes are calculated based on the parameters, and the evaluation indexes are used for quantifying the barrier or adsorption performance of the to-be-tested diaphragm to the target ions. According to the evaluation method and device provided by the invention, the blocking effect of the diaphragm on the ions can be efficiently and quickly detected, so that the diaphragm can be conveniently screened.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a method and apparatus for evaluating the ion blocking or adsorption performance of a separator. Background Technology

[0002] In lithium-ion batteries, the separator, as a crucial barrier between the positive and negative electrodes, needs to block foreign ions other than lithium ions to ensure battery reliability and lifespan. Specifically, during battery manufacturing and use, foreign substances such as transition metals, non-metallic particles, and metal ions generated from the dissolution of the positive electrode can penetrate the separator, causing internal short circuits, accelerating localized thermal runaway during charging and discharging, and even leading to battery fire and explosion. Therefore, during separator development, it is necessary to conduct efficient and rapid testing on the effectiveness of each separator in blocking or adsorbing foreign ions to screen suitable separators and accelerate the development process. Summary of the Invention

[0003] This invention provides a method and apparatus for evaluating the ion blocking or adsorption performance of a membrane, which can efficiently and rapidly detect the ion blocking or adsorption effect of the membrane, so as to facilitate membrane screening.

[0004] This invention provides a method for evaluating the ion blocking or adsorption performance of a membrane, comprising at least the following steps: A first chamber and a second chamber are provided to form ion migration channels through the membrane to be tested; Electrolyte is injected into the first chamber and the second chamber respectively, wherein the electrolyte in the first chamber or the electrolyte in the second chamber contains target ions; A potential difference is established between the first chamber and the second chamber to drive the target ions to migrate directionally through the membrane under test; and The parameters are measured, and based on the parameters, an evaluation index is calculated. The evaluation index is used to quantify the blocking or adsorption performance of the membrane under test for the target ion.

[0005] In one embodiment of the present invention, the parameters include at least one of the concentrations of the target ions in the electrolyte in the first chamber and the electrolyte in the second chamber, or the total amount of the target ions attached to the membrane to be tested.

[0006] In one embodiment of the present invention, the evaluation index is the ion blocking rate, which is calculated by the following formula: Ion blocking rate = [1-(C2*V2) / (C 10 *V1)]*100%; Among them, C 10V1 is the initial concentration of the target ion in the electrolyte in the first chamber before the potential difference is set; C2 is the concentration of the target ion in the electrolyte in the second chamber after the potential difference is set; and V2 is the volume of the electrolyte in the second chamber.

[0007] In one embodiment of the present invention, the evaluation index is the ion adsorption capacity, which is calculated by the following formula: Ion adsorption capacity = C 10 *V1-C1*V1-C2*V2; Among them, C 10 The initial concentration of the target ion in the electrolyte in the first chamber before setting the potential difference is defined as follows: V1 is the volume of the electrolyte in the first chamber; C1 is the concentration of the target ion in the electrolyte in the first chamber after setting the potential difference; C2 is the concentration of the target ion in the electrolyte in the second chamber after setting the potential difference; and V2 is the volume of the electrolyte in the second chamber.

[0008] In one embodiment of the present invention, the evaluation index is the net ion reduction rate, which is calculated by the following formula: Net reduction rate of ions = [(C 10 -C1) / C 10 *100%; Among them, C 10 C1 represents the initial concentration of the target ion in the electrolyte in the first chamber before the potential difference is set, and C1 represents the concentration of the target ion in the electrolyte in the first chamber after the potential difference is set.

[0009] In one embodiment of the present invention, the concentration of the target ion in the electrolyte is analyzed by inductively coupled plasma atomic emission spectrometry or inductively coupled plasma mass spectrometry.

[0010] In one embodiment of the present invention, the electrolyte level in the first chamber is equal to the electrolyte level in the second chamber.

[0011] In one embodiment of the present invention, when the potential difference is set between the first chamber and the second chamber, electrodes are respectively set in the first chamber and the second chamber, and a DC electric field is applied between the two electrodes, wherein the voltage of the DC electric field is 0.1V-6V.

[0012] In one embodiment of the present invention, when the target ion is a cation, the electrode in the first chamber is connected to the positive electrode and the electrode in the second chamber is connected to the negative electrode; when the target ion is an anion, the electrode in the first chamber is connected to the negative electrode and the electrode in the second chamber is connected to the positive electrode.

[0013] In one embodiment of the present invention, the setting time of the potential difference is 0.1h-168h.

[0014] The present invention also provides an apparatus for evaluating the ion blocking or adsorption performance of a membrane, applied to the above-described method, comprising at least: The first chamber is used to contain the first electrolyte; The second chamber, arranged side-by-side with the first chamber, is used to contain the second electrolyte; Connecting pipes to link the first chamber and the second chamber; The diaphragm to be tested is placed in the connecting pipeline; A first electrode extends from outside the first chamber into the electrolyte within the first chamber; and The second electrode extends from outside the second chamber into the electrolyte within the second chamber.

[0015] This invention provides a method and apparatus for evaluating the ion blocking or adsorption performance of a membrane. By improving the evaluation method, the membrane's ion blocking or adsorption effect can be tested efficiently and quickly, thereby rapidly evaluating and screening various membrane products and accelerating R&D and commercial application. Furthermore, the evaluation method provided by this invention can eliminate influencing factors during the testing process and accurately test the membrane's ion blocking effect. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0017] In the attached diagram: Figure 1 This is a schematic diagram of an evaluation device in one embodiment of the present invention.

[0018] Label Explanation: 11. First chamber; 111. First cavity body; 112. First sealing cover; 12. Second chamber; 121. Second cavity body; 122. Second sealing cover; 13. Connecting pipeline; 14. Diaphragm to be tested; 15. Fixing device; 16. First electrode; 17. Second electrode. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0020] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0021] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0022] Please see Figure 1 As shown, the present invention provides an apparatus for evaluating the ion blocking or adsorption performance of a diaphragm, comprising at least a first chamber 11, a second chamber 12, a connecting pipe 13, a diaphragm to be tested 14, a fixing device 15, a first electrode 16, and a second electrode 17. The first chamber 11 and the second chamber 12 are placed side-by-side and are identical. Taking the first chamber 11 as an example, the two chambers will be described below. Specifically, the first chamber 11 includes a first cavity 111 and a first sealing cap 112. The shape of the first cavity 111 is various, such as a cuboid or cylinder, and the surface of the first cavity 111 has an opening (not shown in the figure) to facilitate the injection of electrolyte into the first cavity 111. Furthermore, the opening is fitted with the first sealing cap 112 to seal the first cavity 111 and prevent contamination of the electrolyte inside the first cavity 111. Similarly, the second chamber 12 includes a second cavity 121 and a second sealing cover 122, etc. The arrangement of the second cavity 121 and the second sealing cover 122 is the same as that of the first cavity 111 and the first sealing cover 112, and will not be described in detail here.

[0023] Please see Figure 1As shown, in one embodiment of the present invention, the connecting pipe 13 connects the first chamber 11 and the second chamber 12. Specifically, the connecting pipe 13 connects, for example, the first chamber 111 and the second chamber 121, and the connecting pipe 13, the second chamber 12 and the first chamber 12 are combined to form two chambers with a connected structure.

[0024] Please see Figure 1 As shown, in one embodiment of the present invention, the test diaphragm 14 is placed between the first chamber 11 and the second chamber 12 to isolate the first chamber 11 and the second chamber 12. Specifically, in this embodiment, the test diaphragm 14 is placed, for example, through the connecting pipe 13, to physically isolate the electrolyte from the communication between the first chamber 11 and the second chamber 12.

[0025] Please see Figure 1 As shown, in one embodiment of the present invention, the fixing device 15 clamps the diaphragm 14 to be tested and the connecting pipe 13 to fix the diaphragm 14 to be tested, the first chamber 11 and the second chamber 12, so as to prevent the diaphragm 14 to be tested, the first chamber 11 and the second chamber 12 from moving during the test, which would affect the test process and the accuracy of the test results.

[0026] Please see Figure 1 As shown, in one embodiment of the present invention, the first electrode 16 penetrates the first sealing cover 112 and extends from the outside of the first chamber 11 into the first electrolyte inside the first cavity 111, and the second electrode 17 penetrates the second sealing cover 122 and extends from the outside of the second chamber 12 into the second electrolyte inside the second cavity 121. The first electrode 16 and the second electrode 17 are each independently selected from platinum electrodes, graphite electrodes, or silicon-based negative electrodes, etc.

[0027] Please see Figure 1 As shown, based on the above-described apparatus for evaluating the ion blocking or adsorption performance of a separator, this invention provides a method for evaluating the ion blocking or adsorption performance of a separator. This evaluation method can be used to test various separators, such as those for lithium-ion batteries, sodium-ion batteries, or lithium-sulfur batteries. In this embodiment, the evaluation method is described using the testing of a lithium-ion battery separator as an example. The evaluation method includes at least steps S11-S14.

[0028] Step S11: Provide a first chamber and a second chamber that form an ion migration channel through the membrane to be tested.

[0029] Step S12: Inject electrolyte into the first chamber and the second chamber respectively. The electrolyte in the first chamber or the electrolyte in the second chamber contains the target ions.

[0030] Step S13: Set a potential difference between the first chamber and the second chamber to drive the target ions to migrate directionally through the membrane to be tested.

[0031] Step S14: Measure the parameters and calculate the evaluation index based on the parameters. The evaluation index is used to quantify the blocking or adsorption performance of the membrane under test for the target ions.

[0032] Please see Figure 1 As shown, in one embodiment of the present invention, in step S11, the structure, position and communication relationship of the first chamber 11, the second chamber 12 and the diaphragm to be tested 14 are as described in the above evaluation device, and will not be elaborated further here.

[0033] Please see Figure 1 As shown, in one embodiment of the present invention, after the diaphragm 14 to be tested is placed, in step S11, the diaphragm 14 to be tested, the first chamber 11, and the second chamber 12 are also fixed to prevent the diaphragm 14 to be tested, the first chamber 11, and the second chamber 12 from moving during the test, which would affect the test process and the accuracy of the test results. In this embodiment, for example, the diaphragm 14 to be tested, the first chamber 11, and the second chamber 12 are fixed by clamping the diaphragm 14 to be tested and the connecting pipe 13 using a fixing device 15.

[0034] Please see Figure 1As shown, in one embodiment of the present invention, after the test diaphragm 14, the first chamber 11, and the second chamber 12 are fixed, in step S12, a first electrolyte is injected into the first cavity 111 of the first chamber 11, and a second electrolyte is injected into the second cavity 121 of the second chamber 12. The first electrolyte, for example, contains at least a solvent, a compound containing the target ion, and a lithium salt. The difference between the second electrolyte and the first electrolyte is that the second electrolyte does not contain the target ion solution, and the other components and their concentrations in the electrolyte are the same; that is, the second concentration of the target ion in the second electrolyte is 0. Specifically, the solvent includes at least one of diethyl carbonate, fluoroethylene carbonate, difluoroethyl acetate, dimethyl carbonate, ethylene carbonate, propylene carbonate, or methyl ethyl carbonate. In the compound containing the target ion, the target ion may include anion or cation. When the target ion is a cation, the compound containing the target ion includes at least one of a chloride or sulfate salt containing a cation. The cation may include at least one of sodium ion, magnesium ion, aluminum ion, ferric ion, ferrous ion, copper ion, zinc ion, nickel ion, or manganese ion. When the target ion is an anion, the compound containing the target ion... The compound includes, for example, anionic lithium compounds, and the anion includes, for example, at least one of bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, tetrafluoroborate, or perchlorate. The lithium salt includes, for example, at least one of lithium fluorosulfonylimide or lithium hexafluorophosphate (LiPF6). The content of the lithium salt in the first electrolyte is, for example, 10wt%-18wt%. The first concentration of the target ion in the first electrolyte is, for example, 5ppm-1000ppm. The volumes of the first electrolyte and the second electrolyte are the same, and the liquid level of the first electrolyte in the first cavity 111 is equal to the liquid level of the second electrolyte in the second cavity 121. If the liquid levels of the first electrolyte and the second electrolyte are not the same, the gravity difference between the first electrolyte and the second electrolyte will generate convective mass transfer, thereby accelerating the passage of target ions through the test membrane 14. As a result, it is impossible to distinguish whether the target ions pass through due to the failure of the test membrane or due to passive carrying by gravity convection based on the concentration of target ions in the second electrolyte. Therefore, it is impossible to accurately test the blocking efficiency of the test membrane 14 for target ions.

[0035] Please see Figure 1 As shown, in one embodiment of the present invention, after injecting electrolyte into the two chambers, in step S13, a first electrode 16 is inserted into the first electrolyte, and a second electrode 17 is inserted into the second electrolyte. Specifically, the first electrode 16 penetrates the first sealing cap 112 and extends from the outside of the first chamber 11 into the first electrolyte inside the first cavity 111, and the second electrode 17 penetrates the second sealing cap 122 and extends from the outside of the second chamber 12 into the second electrolyte inside the second cavity 121. The first electrode 16 and the second electrode 17 are each independently selected from platinum electrodes, graphite electrodes, or silicon-based negative electrodes, etc.

[0036] Please see Figure 1 As shown, in one embodiment of the present invention, after inserting electrodes into the electrolyte, in step S13, the first electrode 16 and the second electrode 17 are each electrically connected to the electrochemical workstation. A DC electric field is applied between the first electrode 16 and the second electrode 17, and a preset time for applying the electric field is set to establish a potential difference between the first chamber 11 and the second chamber 12, thereby driving the target ion to migrate directionally from the first electrolyte through the test membrane 14 into the second electrolyte. Specifically, when the target ion is a cation, the first electrode 16 is connected to the positive electrode of the electrochemical workstation, and the second electrode 17 is connected to the negative electrode of the electrochemical workstation; when the target ion is an anion, the first electrode 16 is connected to the negative electrode, and the second electrode 17 is connected to the positive electrode. The preset voltage is a DC voltage, and the value of the preset voltage, for example, does not exceed the decomposition voltage of the first electrolyte and the second electrolyte, specifically, for example, 0.1V-6V. The preset time is, for example, 0.1h-168h. By applying a preset voltage between the first electrode 16 and the second electrode 17, the electrochemical working environment of the separator 14 under test in a lithium-ion battery can be simulated, ensuring the practicality of the test results and making the test results more valuable as a basis for judging whether the separator 14 under test can be applied to lithium-ion batteries. Moreover, if the target ions migrate across the separator 14 under test solely based on the concentration difference between the first electrolyte and the second electrolyte, the migration rate of the target ions is extremely slow. Therefore, by applying a preset voltage, the electric field force will accelerate the migration of the target ions, increasing the driving force for ion migration and thus improving the test efficiency.

[0037] Please see Figure 1 As shown, in one embodiment of the present invention, during the application of the preset voltage in step S13, lithium ions are transferred between the first chamber 11 and the second chamber 12 through the test membrane 14 to achieve energy storage and release. Simultaneously, the test membrane 14 needs to prevent the target ions in the first electrolyte from diffusing into the second electrolyte to avoid a short circuit between the first electrode 16 and the second electrode 17.

[0038] Please see Figure 1As shown, in one embodiment of the present invention, after the DC electric field is applied, in step S14, parameters related to the migration of target ions are measured. Based on the parameters, an evaluation index for quantifying the blocking or adsorption performance of the membrane under test for target ions is calculated and obtained. The parameters include, for example, at least one of the following: the concentration of target ions in the first electrolyte and the second electrolyte, or the total amount of target ions attached to the membrane under test 14. The concentration of target ions in the first electrolyte is measured, for example, by elemental analysis methods such as inductively coupled plasma optical emission spectrometry (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS). The total amount of target ions attached to the membrane under test 14 is measured, for example, by the following process: first, the membrane under test 14 is cleaned with a cleaning solution to dissolve the target ions attached to the membrane under test 14 in the cleaning solution; then, the concentration of target ions in the cleaning solution is measured; finally, the total amount of target ions is calculated based on the concentration and the volume of the cleaning solution. The concentration of the target ions in the cleaning solution is measured, for example, by elemental analysis methods such as ICP-OES or ICP-MS, and the cleaning solution includes, for example, at least one of nitric acid and hydrofluoric acid.

[0039] Please see Figure 1 As shown, in one embodiment of the present invention, in step S14, taking the concentration of the target ion in the first electrolyte and the second electrolyte as an example, the calculation of the evaluation index is explained. Specifically, the evaluation index includes at least one of ion blocking rate, ion adsorption capacity, and net ion reduction rate. The ion blocking rate is calculated using the following formula: Ion blocking rate = [1 - (C² * V²) / (C...] 10 *V1)]*100%; where C 10 To determine the initial concentration of the target ions in the first electrolyte before setting the potential difference, V1 represents the volume of the first electrolyte in the first chamber; C2 represents the concentration of the target ions in the second electrolyte after setting the potential difference, and V2 represents the volume of the second electrolyte in the second chamber. V2 is equal to V1 to avoid the gravitational difference between the first and second electrolytes affecting the accuracy of testing the blocking performance of the membrane 14 for the target ions. Specifically, a higher ion blocking rate indicates a better blocking effect of the membrane 14 for the target ions.

[0040] Please see Figure 1 As shown, in one embodiment of the present invention, in step S14, the ion adsorption amount is calculated using the following formula: Ion adsorption amount = C 10 *V1-C1*V1-C2*V2; where C 10To determine the initial concentration of the target ion in the first electrolyte before setting the potential difference, V1 is the volume of the first electrolyte in the first chamber, C1 is the concentration of the target ion in the first electrolyte after setting the potential difference, C2 is the concentration of the target ion in the second electrolyte after setting the potential difference, and V2 is the volume of the second electrolyte in the second chamber. V2 is equal to V1 to avoid the gravitational difference between the first and second electrolytes affecting the accuracy of testing the adsorption performance of the membrane 14 for the target ion. Specifically, a larger ion adsorption capacity indicates a stronger adsorption capacity of the membrane 14 for the target ion.

[0041] Please see Figure 1 As shown, in one embodiment of the present invention, in step S14, the net ion reduction rate is calculated, for example, by the following formula: Net ion reduction rate = [(C 10 -C1) / C 10 *100%; where C 10 C1 represents the initial concentration of the target ions in the first electrolyte before setting the potential difference, and C1 represents the concentration of the target ions in the first electrolyte after setting the potential difference. Specifically, the net ion reduction rate is a comprehensive reflection of the blocking and adsorption performance of the membrane 14 under test for the target ions. It represents the overall purification capacity of the membrane 14 under test for the target ions in the first electrolyte. The larger the net ion reduction rate, the better the overall removal effect of the membrane 14 under test on the target ions in the first electrolyte.

[0042] Please see Figure 1 As shown, the method and apparatus for testing the blocking or adsorption performance of the membrane 14 against target ions provided by this invention can efficiently and quickly test the blocking or adsorption effect of the membrane against ions, thereby rapidly evaluating and screening various membrane products and accelerating the research and development and commercial application progress. Moreover, the evaluation method and apparatus provided by this invention can accurately test the blocking or adsorption effect of the membrane against ions by eliminating influencing factors such as the height difference between the first and second electrolytes and concentration measurement errors during the testing process.

[0043] The present invention will be explained in more detail below by referring to embodiments and comparative examples, which should not be construed as limiting. Appropriate modifications can be made within the scope of the present invention, all of which fall within the technical scope of the present invention.

[0044] Example 1 according to Figure 1The system provides a first chamber and a second chamber placed side-by-side, connected to each other. A 6cm diameter diaphragm A is placed between the first and second chambers to isolate them. Then, 50mL of a first electrolyte is injected into the first chamber, and 50mL of a second electrolyte is injected into the second chamber. The liquid level of the first electrolyte in the first chamber is equal to the liquid level of the second electrolyte in the second chamber. The first electrolyte contains copper chloride, diethyl carbonate, and LiPF6. The initial concentration of copper ions in the first electrolyte is 20ppm, and the content of LiPF6 in the first electrolyte is 10wt%. The second electrolyte does not contain copper ions, i.e., the initial concentration of copper ions in the second electrolyte is 0. The concentrations of the remaining components are the same as those in the first electrolyte. Two platinum electrodes were inserted into the first and second electrolytes respectively through the sealed caps of the two chambers. The platinum electrode in the first electrolyte was connected to the positive electrode, and the platinum electrode in the second electrolyte was connected to the negative electrode. A DC voltage of +4.5V was applied between the two platinum electrodes and maintained for 4 hours. Samples of the first and second electrolytes were then taken, and the copper ion concentrations in the first and second electrolytes were analyzed by ICP-OES. The results are shown in Table 1, and three evaluation indexes were calculated. When calculating the evaluation indexes, the density of the first and second electrolytes was taken as 1 g / cm³. 3 To calculate.

[0045] Example 2 The difference between this embodiment and Embodiment 1 is that the DC voltage is maintained for 24 hours.

[0046] Example 3 The difference between this embodiment and Embodiment 1 is that the DC voltage is maintained for 72 hours.

[0047] Example 4 The difference between this embodiment and Embodiment 1 is that the initial concentration is 100 ppm.

[0048] Example 5 The difference between this embodiment and Embodiment 1 is that the initial concentration is 500 ppm.

[0049] Example 6 The difference between this embodiment and embodiment 5 is that the DC voltage is +1V.

[0050] Example 7 The difference between this embodiment and Embodiment 1 is that manganese chloride is used instead of copper chloride, and the initial concentration of manganese ions in the electrolyte is 100 ppm.

[0051] Example 8 The difference between this embodiment and Embodiment 2 is that cobalt chloride is used instead of copper chloride, and the initial concentration of cobalt ions in the electrolyte is 100 ppm.

[0052] Comparative Example 1 The difference between this comparative example and Example 4 is that the diaphragm A to be tested is replaced with a commercially available polyethylene diaphragm.

[0053] Comparative Example 2 The difference between this comparative example and Example 5 is that no DC voltage is applied.

[0054] Table 1. Electrolyte concentrations and evaluation indicators in Examples 1-8 and Comparative Examples 1-2

[0055] Please refer to Table 1. Comparing Example 4 and Comparative Example 1, it can be seen that when membrane A is used as the membrane to be tested, the ion blocking rate is 100%, and when polyethylene membrane is used as the membrane to be tested, the ion blocking rate is 76%. This shows that membrane A is more effective than polyethylene membrane in preventing copper ions from diffusing into the second electrolyte.

[0056] Please refer to Table 1. Comparing Examples 1-3, it can be seen that as the test time increases, the amount of ion adsorption and the net ion reduction rate gradually increase, indicating that as the test time increases, more and more copper ions in the first electrolyte are adsorbed by membrane A.

[0057] Please refer to Table 1. Comparing Examples 1 and 4-5, it can be seen that as the difference between the initial concentrations of the first and second electrolytes increases from 20 ppm to 100 ppm, the ion blocking rate does not decrease, but the ion adsorption capacity and net ion reduction rate increase. However, as the difference between the initial concentrations of the first and second electrolytes continues to increase from 100 ppm to 500 ppm, the ion blocking rate and net ion reduction rate decrease, but the ion adsorption capacity still increases. This indicates that the greater the concentration difference between the first and second electrolytes, the stronger the driving force for ion migration. More and more copper ions are adsorbed by membrane A and will not permeate through membrane A, thereby increasing the testing rate. However, when the concentration difference between the first and second electrolytes is too large, copper ions will permeate through membrane A. Therefore, the limit value of the concentration difference between the first and second electrolytes when membrane A can block copper ions can be obtained.

[0058] Please refer to Table 1. Comparing Example 5 and Comparative Example 2, it can be seen that after applying DC voltage, the amount of ion adsorption and the net ion reduction rate increase significantly. This indicates that by applying DC voltage, the driving force for ion migration is enhanced, which can accelerate the diffusion of copper ions onto the membrane. This helps to evaluate the membrane's adsorption performance for copper ions in a shorter time, thereby saving test time.

[0059] Please refer to Table 1. Comparing Examples 5-6, it can be seen that when the voltage increases, the amount of ion adsorption and the net ion reduction rate increase significantly. This indicates that as the voltage increases, the driving force for ion migration becomes stronger, which can accelerate the diffusion of copper ions onto the membrane, thereby improving the testing rate and saving testing time.

[0060] In summary, this invention provides a method and apparatus for evaluating the ion blocking or adsorption performance of a membrane. By applying a DC voltage to the electrodes on both sides of the membrane, the ion blocking or adsorption effect of the membrane can be tested efficiently and quickly, thereby rapidly evaluating and screening various membrane products and accelerating the research and development and commercial application process. Moreover, the evaluation method and apparatus provided by this invention can accurately test the ion blocking or adsorption effect of the membrane by eliminating the influence of factors such as the height difference between the first and second electrolytes and concentration measurement errors during the testing process.

[0061] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method of evaluating ion barrier or sorption properties of a separator, characterized by, At least comprising the following steps: providing a first chamber and a second chamber forming an ion migration channel through a membrane to be tested; injecting electrolyte into each of the first chamber and the second chamber, the electrolyte in the first chamber or the electrolyte in the second chamber containing target ions; setting a potential difference between the first chamber and the second chamber to drive directional migration of the target ions through the membrane to be tested; and measuring a parameter and calculating an evaluation index based on the parameter, the evaluation index being used to quantify the barrier or adsorption performance of the membrane to be tested on the target ions. The parameter comprises at least one of the concentration of the target ions in the electrolyte in the first chamber and the electrolyte in the second chamber, or the content of the target ions attached to the membrane to be tested.

2. The method of claim 1, wherein, The evaluation index is an ion barrier rate, which is calculated by the following formula:

3. The method of claim 1, wherein, The evaluation index is an ion adsorption amount, which is calculated by the following formula: Ion barrier rate = [1 - (C2*V2) / (C 10 *V1)] * 100%; wherein C 10 is the initial concentration of the target ion in the electrolyte in the first chamber before the potential difference is set, V1 is the volume of the electrolyte in the first chamber; C2 is the concentration of the target ion in the electrolyte in the second chamber after the potential difference is set, V2 is the volume of the electrolyte in the second chamber.

4. The method of claim 1, wherein, The evaluation index is an ion net reduction rate, which is calculated by the following formula: Ion adsorption amount = C 10 *V1-C1*V1-C2*V2; wherein C 10 is the initial concentration of the target ion in the electrolyte in the first chamber before the potential difference is set, V1 is the volume of the electrolyte in the first chamber, C1 is the concentration of the target ion in the electrolyte in the first chamber after the potential difference is set, C2 is the concentration of the target ion in the electrolyte in the second chamber after the potential difference is set, and V2 is the volume of the electrolyte in the second chamber.

5. The method of claim 1, wherein, The concentration of the target ions in the electrolyte is analyzed by inductively coupled plasma emission spectrometry or inductively coupled plasma mass spectrometry. Net reduction rate of ions = [(C 10 -C1) / C 10 *100%; wherein C 10 is the initial concentration of the target ion in the electrolyte in the first chamber before the potential difference is set, and C1is the concentration of the target ion in the electrolyte in the first chamber after the potential difference is set.

6. The method according to any one of claims 3-5, characterized in that, The liquid level of the electrolyte in the first chamber and the liquid level of the electrolyte in the second chamber are equal.

7. The method of claim 1, wherein, When the potential difference is set between the first chamber and the second chamber, electrodes are arranged in each of the first chamber and the second chamber, and a direct current electric field is applied between the two electrodes, the voltage of the direct current electric field being 0.1V-6V.

8. The method of claim 1, wherein, When the target ions are cations, the electrode in the first chamber is connected to a positive electrode, and the electrode in the second chamber is connected to a negative electrode; when the target ions are anions, the electrode in the first chamber is connected to a negative electrode, and the electrode in the second chamber is connected to a positive electrode.

9. The method of claim 8, wherein, The setting time of the potential difference is 0.1h-168h.

10. The method of claim 1, wherein, At least comprising:

11. A device for assessing the ion barrier or sorption properties of a separator, for use in the method of any one of claims 1 to 10, characterized in that, a first chamber for containing a first electrolyte; a second chamber arranged in parallel with the first chamber for containing a second electrolyte; a connecting pipeline connecting the first chamber and the second chamber; a membrane to be tested arranged in the connecting pipeline; a first electrode extending from outside the first chamber into the electrolyte in the first chamber; and a second electrode extending from outside the second chamber into the electrolyte in the second chamber. ​

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