Potentiometric sensor

Abstract

The potential sensor comprises a shell and a tab on the outer side of the shell, a battery cell, a reference electrode assembly and electrolyte are arranged in the shell, and the battery cell comprises a positive pole piece, a negative pole piece and a first isolating membrane; the reference electrode assembly comprises a reference electrode and a separator wrapping the reference electrode, the separator is arranged between the positive pole piece and the first isolating membrane, or the separator is arranged between the negative pole piece and the first isolating membrane, or the separator is arranged between the negative pole piece and the first isolating membrane. The positive pole piece, the negative pole piece, the first isolating membrane and the isolating piece are all in contact with the electrolyte. According to the application, the reference electrode in the battery is rubberized on the two sides, so that the fluctuation during potential measurement in the long-period charging and discharging process of the battery is small, the potential is closer to the real potential of the whole electrode, the test accuracy is high, and the reference electrode can be prevented from being repeatedly plated with lithium.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a potential sensor. Background Art

[0002] At present, the three-electrode system potential monitoring method of the potential sensor mainly adopts the built-in three-electrode structure and the external three-electrode structure. Among them, the built-in three-electrode structure easily causes the reference electrode to dissolve, resulting in continuous changes in the lithium ion concentration around the reference electrode, which in turn causes the relative potential of the battery to continue to change during the charging and discharging process, and it is impossible to obtain a stable measurement potential. Moreover, the dissolution of the reference electrode during the cycle process makes it only possible to measure the potential changes during short-cycle charging and discharging without repeated lithium plating. If a long-cycle potential test is performed, the reference electrode needs to be repeatedly plated with lithium, which makes the process cumbersome and complicated, increases the time required for the test and consumes lithium resources. The test value of the external three-electrode structure test has poor consistency with the true value, and is not suitable for tests that require accurate and accurate potential values. Summary of the invention

[0003] In view of this, the present application provides a potential sensor, which glues the reference electrode inside it on both sides to reduce the fluctuation of the potential measurement during the long-cycle charging and discharging process of the battery, and is closer to the actual potential of the entire electrode. The test accuracy is high, and it can also ensure that the reference electrode will not dissolve when measuring the potential during the long-cycle charging and discharging process of the battery, so as to avoid repeated lithium plating of the reference electrode.

[0004] In the first aspect, the present application provides a potential sensor, the potential sensor comprises a shell and a tab on the outside of the shell, the shell is provided with a battery cell, a reference electrode assembly and an electrolyte, the battery cell comprises a positive electrode sheet, a negative electrode sheet and a first separator, the first separator is arranged between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet is connected to the positive electrode tab, and the negative electrode sheet is connected to the negative electrode tab. The reference electrode assembly comprises a reference electrode and a separator wrapping the reference electrode, the separator is arranged between the positive electrode sheet and the first separator; or the separator is arranged between the negative electrode sheet and the first separator. The positive electrode sheet, the negative electrode sheet, the first separator and the separator are all in contact with the electrolyte. The present application arranges a separator wrapping the reference electrode in the potential sensor, on the one hand, the separator is conducive to reducing the potential fluctuation difference of the potential sensor and enhancing the accuracy of the test, and on the other hand, the separator prolongs the measurement period of the potential sensor.

[0005] In some embodiments, the separator includes a first polymer tape and a second polymer tape. The side of the first polymer tape with the adhesive layer is adhesively bonded to the positive electrode tab. The side of the second polymer tape with the adhesive layer is adhesively bonded to the first separator film. Alternatively, the side of the first polymer tape with the adhesive layer is adhesively bonded to the first separator film, and the side of the second polymer tape with the adhesive layer is adhesively bonded to the negative electrode tab. The side of the first polymer tape with the non - adhesive layer and the side of the second polymer tape with the non - adhesive layer are arranged opposite to each other, so that after the positive electrode tab, the first separator film, and the negative electrode tab are pressed and laminated, the separator is formed. The relative arrangement of the side of the first polymer tape with the non - adhesive layer and the side of the second polymer tape with the non - adhesive layer can protect the reference electrode while not affecting the contact between the reference electrode and the electrolyte, improving the reliability and stability of the test results while further increasing the service life of the potential sensor. The lithium - plated end of the reference electrode is inserted into the interior of the separator along the first direction, and the non - lithium - plated end of the reference electrode extends outside the housing. Herein, the length direction of the separator is consistent with the first direction. Generally, gluing will cause partial capacity loss in the gluing area. However, the applicant unexpectedly found that during the installation of the built - in three - electrode structure, when gluing on both sides of the reference electrode, the current path in the normal direction (the third direction) of the gluing area is blocked by the separator, and the radial (the second direction) path leads to the anode and cathode. The change in lithium concentration in the radial direction is less than that in the normal direction. Gluing on both sides can reduce the change in lithium concentration around the built - in reference electrode, and the measured potential is more stable and closer to the average potential of the electrode. Although gluing will cause partial capacity loss in the gluing area, and the partial capacity loss is less than 0.1%, the potential stability and accuracy are significantly improved.

[0006] In some embodiments, along the first direction, the width of the battery cell is denoted as A, and the length of the lithium - plated end of the reference electrode is denoted as B, satisfying: 0.3 ≤ B / A ≤ 0.5, where the width direction of the battery cell is consistent with the first direction. Exemplarily, B / A is 0.3, 0.35, 0.4, 0.45, 0.5, or a range composed of any two of the above values.

[0007] In some embodiments, along the first direction, the length of the lithium - plated end of the reference electrode is denoted as B, and the length of the separator is denoted as C, satisfying: 1 < C / B < 1.2. The length of the lithium - plated end of the reference electrode and the length of the separator are both within a suitable range, which is conducive to reducing the potential fluctuation difference during potential measurement. The smaller the potential fluctuation difference, the more stable the test and the higher the accuracy. And if the C / B ratio is too large, it will cause capacity loss, making the electrochemical reaction uneven and having potential safety hazards. Exemplarily, C / B is 1.02, 1.04, 1.06, 1.08, 1.1, 1.15, 1.18, 1.19, 1.195, or a range composed of any two of the above values.

[0008] In some embodiments, along the second direction, the radial length of the lithium-plated end of the reference electrode is recorded as B', and the width of the separator is recorded as C', satisfying: 1% ≤ B' / C' ≤ 3%, wherein the width direction of the separator is consistent with the second direction. When the B' / C' satisfies the above range, it can further improve the stability and test stability of the potential sensor while reducing the battery capacity loss caused by the provision of the separator. Exemplarily, B' / C' is 1%, 1.5%, 2.0%, 2.5%, 3% or a range consisting of any two of the above values.

[0009] In some embodiments, the radial length B' of the lithium-plated end of the reference electrode satisfies: 40 μm ≤ B' ≤ 120 μm. Exemplarily, B' is 40 μm, 50 μm, 60 μm, 70 μm, 90 μm, 110 μm, 120 μm, or a range consisting of any two of the above values.

[0010] In some embodiments, along the third direction, the thickness of the first polymer tape and / or the second polymer tape is recorded as D, satisfying: 1≤D / B′≤2, wherein the thickness direction of the polymer tape is consistent with the third direction. The appropriate thickness of the isolation member can better block the path of the current along the third direction (normal direction), which is more conducive to improving the test stability. Exemplarily, D / B′ is 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.5, 1.6, 1.7, 1.8, 1.9, 2 or a range consisting of any two of the above values.

[0011] In some embodiments, along the second direction, the height of the battery cell is recorded as A', and the distance from the midpoint between the two vertices of the outer side wall of the separator and the end adjacent to the lithium-plated end of the reference electrode to the top of the battery cell is recorded as H, satisfying: 30% ≤ H / A' ≤ 70%, and the pole ear is arranged at the top of the battery cell. Within the above range, it is more conducive to reducing the difference in potential fluctuations and the test accuracy is higher. Exemplarily, H / A' is 30%, 40%, 50%, 60%, 70% or a range consisting of any two of the above values.

[0012] In some embodiments, the polymer tape includes a polymer substrate and an adhesive layer, wherein the adhesive layer is disposed on one side surface of the polymer substrate, the temperature grade range of the polymer tape is 75 to 85° C., and the voltage grade of the polymer tape is below 600V. The temperature grade range of the polymer tape may be the maximum operating temperature range of the polymer tape. The voltage grade of the polymer tape may be the maximum operating voltage that the polymer tape can withstand. When the polymer tape satisfies at least one of the above conditions, the difference in potential fluctuation measured by the potential sensor is small, and the life of the potential sensor is improved.

[0013] In some embodiments, the polymer substrate is selected from a polyolefin polymer substrate, and the polyolefin polymer substrate includes but is not limited to PE (polyethylene) tape and PVC (polyvinyl chloride) insulating tape.

[0014] In some embodiments, the insulation resistance of the polymer tape is recorded as R ohms, which satisfies: R ≥ 10. Preferably, it satisfies: 10 ≤ R ≤ 18. Exemplarily, the insulation resistance R of the polymer tape is 10 ohms, 12 ohms, 14 ohms, 16 ohms, 18 ohms, or a range consisting of any two of the above values.

[0015] In some embodiments, the potential sensor satisfies: 0.05≤1μm×R / B′≤0.25. The present application further regulates the range of the insulation resistance of the polymer tape to facilitate adaptation with the lithium-plated end of the reference electrode, better blocking the current in the normal direction of the adhesive area, and at the same time, by further limiting the radial length of the lithium-plated end of the reference electrode within a suitable range, it is conducive to a significant improvement in potential stability and accuracy. Exemplarily, the value of 1μm×R / B′ is 0.05, 0.10, 0.15, 0.20, 0.25 or a range consisting of any two of the above values.

[0016] In some embodiments, the reference electrode assembly further includes a second separator, and when the separator is disposed between the positive electrode plate and the first separator, the first polymer tape adhesive layer side is bonded to the second separator, and when the separator is disposed between the negative electrode plate and the first separator, the second polymer tape adhesive layer side is bonded to the second separator, so as to avoid direct contact between the separator and the plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 Schematic diagram of the structure of the potential sensor described in this application.

[0019] In the figure: 1. negative electrode plate; 2. second isolation membrane; 3. isolation member; 4. reference electrode; 5. first isolation membrane; 6. positive electrode plate; 7. negative electrode tab; 8. positive electrode tab; 101. battery cell. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] Potentiometric Sensors

[0022] First Implementation Method

[0023] See also Figure 1 The potential sensor includes a shell and a pole ear on the outside of the shell, and a battery cell 101, a reference electrode assembly and an electrolyte are arranged inside the shell. The battery cell 101 includes a negative electrode sheet 1, a positive electrode sheet 6 and a first isolation membrane 5, and the first isolation membrane 5 is arranged between the negative electrode sheet 1 and the positive electrode sheet 6. The negative electrode sheet 1 is connected to the negative electrode ear 7, and the positive electrode sheet 6 is connected to the positive electrode ear 8. The reference electrode assembly includes a reference electrode 4 and an isolation member 3 wrapping the reference electrode, and the isolation member 3 is arranged between the negative electrode sheet 1 and the first isolation membrane 5. The positive electrode sheet 6, the negative electrode sheet 1, the first isolation membrane 5 and the isolation member 3 are all in contact with the electrolyte.

[0024] The separator 3 includes a first polymer tape 31 and a second polymer tape 32, wherein the adhesive layer side of the first polymer tape 31 (toward the first separator 5) is bonded to the first separator 5, and the adhesive layer side of the second polymer tape 32 (toward the negative electrode sheet 1) is bonded to the negative electrode sheet 1, and the adhesive layer side of the first polymer tape 31 (toward the separator 3) and the adhesive layer side of the second polymer tape (toward the separator 3) are arranged opposite to each other, so that the positive electrode sheet 6, the first separator 5 and the negative electrode sheet 1 are pressed and stacked to form the separator 3. One end of the reference electrode 4 is a lithium-plated end, and the other end is a non-lithium-plated end. The lithium-plated end of the reference electrode 4 is inserted into the interior of the separator 3 along a first direction, and the non-lithium-plated end of the reference electrode 4 extends out of the shell, wherein the first direction is the x-axis direction, the second direction is the y-axis direction, and the third direction is the z-axis direction.

[0025] In some embodiments, the reference electrode assembly further includes a second isolation film 2 , the adhesive layer side of the second polymer tape 32 is bonded to the second isolation film 2 , and the second isolation film 2 is bonded to the negative electrode plate 1 .

[0026] Second implementation method

[0027] Different from the first embodiment, the isolation member 3 is arranged between the positive electrode plate 6 and the first isolation film 5, the adhesive layer side of the first polymer tape 31 is bonded to the second isolation film 2, the second isolation film 2 is laminated on the positive electrode plate 6, and the adhesive layer side of the second polymer tape 32 is bonded to the first isolation film 5.

[0028] Embodiment design:

[0029] Example 1

[0030] Preparation of positive electrode

[0031] Aluminum foil is used as the positive electrode current collector, and a layer of lithium cobalt oxide slurry is evenly coated on the surface of the aluminum foil. The lithium cobalt oxide slurry includes 97.8wt% LiCoO2 (LCO), 0.8wt% polyvinylidene fluoride (PVDF) and 1.4wt% conductive carbon black, and then cold pressed to prepare a positive electrode sheet.

[0032] Preparation of negative electrode

[0033] Copper foil is used as the negative electrode current collector, and a layer of graphite slurry is evenly coated on the surface of the copper foil, wherein the graphite slurry includes 97.7wt% artificial graphite, 1.3wt% carboxymethyl cellulose (CMC) and 1.0wt% styrene-butadiene rubber (SBR), and then cold pressed to prepare a negative electrode sheet.

[0034] Preparation of isolation membrane

[0035] A 9 μm thick polyethylene (PE) porous membrane was selected as the isolation membrane.

[0036] Preparation of electrolyte

[0037] Ethyl methyl carbonate (EMC), ethylene carbonate (EC), lithium hexafluorophosphate LiPF6, fluoroethylene carbonate (FEC), 1,3-propane sultone (PS), and vinyl ethylene carbonate (VC) were uniformly mixed in a mass ratio of 40:35:15:3:3:4 to obtain an electrolyte.

[0038] Preparation of potentiometric sensors

[0039] (1) Material preparation: a. Punching isolation film: separate each layer of isolation film with paper, place it on the film die and punch it into small pieces of 53.2*45.7mm, then use tweezers to take out the isolation film for use. b. Punching pole pieces: put the corresponding pole pieces on the die of the punching machine for punching, and use tweezers to take out the pole pieces. The size of the positive pole piece is 49.5*42mm, and the size of the negative pole piece is 51*43.5mm. c. Cleaning the pole ears: lay the pole pieces flat on dust-free paper, and wipe the pole ears with a cotton swab with a small amount of solvent. The positive pole piece is wiped with GSN, and the negative pole piece is wiped with water. d. Chemical treatment of lithium-plated copper wire (reference electrode 4): The lithium-plated copper wire is treated with dilute acid (0.1mol / L dilute hydrochloric acid) for 1min before use to remove the surface oxide layer.

[0040] (2) Gluing: PE tape is pasted on the negative electrode plate 1 and the first isolation film 5. The position parameters during the gluing are shown in Table 1. In order to avoid the change of lithium ion concentration caused by the deviation of the reference electrode position and lead to inaccurate point detection, the lithium-plated copper wire is placed on the PE tape. PE tape performance parameters: temperature level: 80°C (176°F); thickness: 6 mils; voltage level: 500V; insulation strength: 40 kV / mm (1000 V / mil); insulation resistance: 14 ohms.

[0041] The difference between Comparative Example 1 and Example 1 is that no glue is applied in Comparative Example 1.

[0042] The difference between Examples 2 to 7 and Example 1 is that the corresponding parameters A, B and C are adjusted during the adhesive application, as shown in Table 1.

[0043] The difference between Examples 8 to 12 and Example 5 is that when applying glue in Examples 8 to 12, parameter A′, parameter B′ and parameter C′ are further adjusted on the basis of Example 5, as shown in Table 2 for details.

[0044] The difference between Examples 13 to 15 and Example 11 is that when the adhesive is applied in Examples 13 to 15, the parameter B′ and the parameter D are further adjusted on the basis of Example 11, as shown in Table 3 for details.

[0045] The difference between Examples 16 to 18 and Example 13 is that when Examples 16 to 18 are glued, the ratio of H / A′ is further adjusted on the basis of Example 13, as shown in Table 4 for details.

[0046] The difference between Examples 19 to 22 and Example 17 is that when applying glue in Examples 19 to 22, the parameter R, the parameter B′ and the ratio of R / B′ are further adjusted on the basis of Example 17, as shown in Table 5 for details.

[0047] (3) Welding: Align the welding points of the battery cell and place it on the welding seat. Use tweezers to pick up the external tab and align the welding points and place it on the tab for welding. Use 11mm wide and thick green glue, cut into small glue pieces with a length of 7mm, and use tweezers to pick up the Tab welding position. Apply four small glue pieces on both sides. If the disassembled pole piece is welded, the Tab should be insulated with wrinkled glue to prevent short circuit.

[0048] (4) Top and side sealing: Use a special three-electrode top sealing head for head assembly and fixture debugging. Fold the packaging bag in half, put the battery cell and reference electrode into the packaging bag, and use the fixture to seal the top and side. Wrap the reference electrode with a layer of isolation film with the opening facing outward.

[0049] (5) Liquid injection: Adjust the injection volume within the required range, expand the battery cell with a special buckle tool, and use a liquid injection pump or dropper to insert the battery cell with the opening facing upward to inject the electrolyte.

[0050] (6) Packaging: After liquid injection, the battery cell is placed in a vacuum still box and left to stand for 15 minutes. After standing, the battery cell is placed in a packaging machine for vacuum packaging.

[0051] Table 1

[0052]

[0053]

[0054] Compared with Example 1 and Example 4, it can be seen that when the B / A value and C / B are not in the appropriate range, the difference in potential fluctuation is large, both around 0.04. The two groups of ratios of Example 4 and Example 5 are both within the range described in this application. It can be seen from Table 1 that the ratio is around 0.03. Compared with Examples 1 to 3, the difference in potential fluctuation of Examples 4 to 5 is reduced by about 0.01. Compared with Example 5, at least one of the B / A value and C / B in Examples 6 to 7 is within the range described in this application. Combined with the data in Table 1, it can be seen that the difference in potential fluctuation of Examples 6 to 7 is significantly higher than the difference in potential fluctuation of Example 5, which is about 0.005 higher. Comparative Example 1 was not glued, and its difference in potential fluctuation increased significantly to 0.088.

[0055] Table 2

[0056] A′(mm) B′(μm) C′(μm) B′ / C′ Difference in potential fluctuation Example 8 61 80 2000 0.040 0.030 Example 9 61 64 2800 0.023 0.027 Example 10 61 80 4000 0.020 0.025 Embodiment 11 61 64 6400 0.010 0.024 Example 12 61 64 9600 0.008 0.029

[0057] Compared with Example 9, it can be seen that the range of B' / C' value is appropriate in Example 8 and Example 12, which is conducive to further reducing the difference of potential fluctuation. Compared with Example 9, it can be seen that when the B' value is in the appropriate range, the smaller the value of B' / C' value in the appropriate range is, the more conducive it is to reducing the difference of potential fluctuation.

[0058] Table 3

[0059]

[0060]

[0061] Compared with Example 11, Examples 13 to 15 further adjust the D / B′ value on the basis of Example 11. It can be clearly seen that the difference in potential fluctuations of Examples 13 to 15 is further reduced.

[0062] Table 4

[0063] H / A′ Difference in potential fluctuation Example 16 0.3 0.019 Embodiment 17 0.5 0.017 Embodiment 18 0.7 0.019

[0064] Compared with Example 14, Examples 16 to 18 further adjust the H / A′ value on the basis of Example 14. It can be clearly seen that the difference in potential fluctuations of Examples 16 to 18 is further reduced.

[0065] Table 5

[0066] R B′(μm) R / B′ Difference in potential fluctuation Embodiment 19 16 64 0.25 0.015 Embodiment 20 10 80 0.125 0.015 Embodiment 21 10 120 0.083 0.014 Embodiment 22 2 80 0.025 0.017

[0067] Compared with Example 17, Examples 19 to 22 further adjust the R value, B' value and R / B' value on the basis of Example 17. The three parameters in Examples 19 to 21 are all within the appropriate range, and the corresponding potential fluctuation differences are significantly reduced compared with Example 17. The R value and R / B' value of Example 22 are not within the appropriate range, and the effect is not much different from that of Example 17.

[0068] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A potential sensor, characterized in that: including a shell and a tab outside the shell; A battery cell, a reference electrode assembly and an electrolyte are arranged inside the shell; The battery cell comprises a positive electrode sheet, a negative electrode sheet and a first isolation film, wherein the first isolation film is arranged between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet is connected to the positive electrode tab, and the negative electrode sheet is connected to the negative electrode tab; The reference electrode assembly includes a reference electrode and a separator wrapping the reference electrode; The separator is disposed between the positive electrode sheet and the first separator; or The separator is disposed between the negative electrode plate and the first separator; The positive electrode sheet, the negative electrode sheet, the first separator and the separator are all in contact with the electrolyte.

2. The potential sensor according to claim 1, characterized in that The spacer includes a first polymer tape and a second polymer tape; The first polymer tape adhesive layer side is bonded to the positive electrode plate, and the second polymer tape adhesive layer side is bonded to the first isolation film; or, The first polymer tape adhesive layer side is bonded to the first isolation film, and the second polymer tape adhesive layer side is bonded to the negative electrode plate; and, The first polymer tape adhesive layer side and the second polymer tape adhesive layer side are arranged opposite to each other, so that the positive electrode sheet, the first separator and the negative electrode sheet are pressed and stacked to form the separator; The lithium-plated end of the reference electrode is disposed inside the isolation member along a first direction; The non-lithium-plated end of the reference electrode extends out of the shell; Wherein, the length direction of the isolation element is consistent with the first direction; The width direction of the battery cell is consistent with the first direction.

3. The potential sensor according to claim 2, characterized in that: Along the first direction, the width of the battery cell is recorded as A, and the length of the lithium-plated end of the reference electrode is recorded as B, satisfying: 0.3≤B / A≤0.

5.

4. The potential sensor according to claim 2, characterized in that: Along the first direction, the length of the lithium-plated end of the reference electrode is recorded as B, and the length of the separator is recorded as C, satisfying: 1 <C / B<1.2。 5. The potential sensor according to claim 2, characterized in that: Along the second direction, the radial length of the lithium-plated end of the reference electrode is recorded as B', and the width of the separator is recorded as C', satisfying at least one of the following conditions: (1) 1% ≤ B′ / C′ ≤ 3%; (2) 40 μm ≤ B′ ≤ 120 μm; Wherein, the width direction of the isolation member is consistent with the second direction.

6. The potential sensor according to claim 5, characterized in that Along the third direction, the thickness of the first polymer tape and / or the second polymer tape is recorded as D, satisfying: 1≤D / B′≤2; Wherein, the thickness direction of the polymer tape is consistent with the third direction.

7. The potential sensor according to claim 5, characterized in that: Along the second direction, the height of the battery cell is recorded as A′, and the distance from the middle point between the two vertices of the outer side wall of the separator and the end adjacent to the lithium-plated end of the reference electrode to the top of the battery cell is recorded as H, satisfying: 30%≤H / A′≤70%; The pole ear is arranged on the top of the battery cell.

8. The potential sensor according to claim 2, characterized in that: The polymer tape comprises a polymer substrate and an adhesive layer, wherein the adhesive layer is disposed on one side surface of the polymer substrate, and the polymer tape satisfies at least one of the following conditions: (1) The temperature grade range is 75~85℃; (2) Voltage level is below 600V; (3) The polymer substrate is selected from polyolefin polymer substrates.

9. The potential sensor according to claim 5, characterized in that: The insulation resistance of the polymer tape is denoted as R ohms, satisfying at least one of the following conditions: (1)0.05≤1μm×R / B′≤0.25; (2)R≥10。 10. The potential sensor according to claim 2, characterized in that: The reference electrode assembly also includes a second isolation membrane; When the separator is disposed between the positive electrode plate and the first separator, the adhesive layer side of the first polymer tape is bonded to the second separator; When the separator is disposed between the negative electrode plate and the first separator, the adhesive layer side of the second polymer tape is bonded to the second separator.

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