A three-electrode cell

Abstract

The utility model belongs to battery technical field discloses a three electrode battery. Three electrode battery includes the positive sheet, diaphragm and negative sheet that set up in turn layer by layer, three electrode battery still includes reference electrode, and reference electrode includes current collector, and current collector includes annular main part and the tab that is connected with main part, and the main part is arranged around the outer edge of positive sheet and is spaced with positive sheet. The annular main part of reference electrode is arranged around the outer edge of positive sheet, and is spaced with positive sheet, so that positive sheet and reference electrode are located in the same layer, and the diaphragm between positive sheet and reference electrode in the prior art is saved, on the one hand, it is favorable for reducing cost, and the overall thickness of battery is reduced, on the other hand, the interference of diaphragm to battery performance detection can be reduced, the potential change of positive reference and negative reference can be accurately detected, and the steric hindrance effect of reference electrode in full battery is reduced.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a three-electrode battery. Background Technology

[0002] To further improve battery safety and performance, a method for in-situ detection of internal electrochemical reactions in batteries is needed to monitor and control the changes in positive and negative electrode potentials in real time during charging and discharging.

[0003] The most common method currently is to introduce a reference electrode to monitor the positive and negative electrode potentials of the battery in situ. The reference electrode is typically placed between the positive and negative electrode plates, and separators are required between both the positive and negative electrode plates. This arrangement not only increases the number of separators and the overall thickness of the battery, thus increasing cost, but the separators also interfere with the battery's electrical performance testing, affecting the accuracy of detecting changes in the positive and negative reference potentials, and reducing the steric hindrance effect of the reference electrode within the entire battery. Utility Model Content

[0004] The purpose of this invention is to provide a three-electrode battery that can solve the problems of increased separator quantity, increased battery thickness and cost, and reduced performance testing accuracy caused by the reference electrode being located between the positive and negative electrodes.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A three-electrode battery includes a positive electrode, a separator, and a negative electrode stacked sequentially, and the three-electrode battery also includes a reference electrode;

[0007] The reference electrode includes a current collector, which includes an annular body and a tab connected to the body. The body is disposed around the outer edge of the positive electrode and spaced apart from the positive electrode.

[0008] As an alternative to the above-mentioned three-electrode battery, both the positive electrode and the negative electrode are circular, and the main body is annular. The inner radius R1 of the main body, the outer radius R2 of the main body, the radius R3 of the positive electrode, and the radius R4 of the negative electrode satisfy: 0.05≤(R2-R1) / R3≤0.36, and R4>R2>R1>R3;

[0009] And / or, the main body is annular, the positive electrode is circular, and the main body and the positive electrode are arranged at the same center.

[0010] As an alternative to the above-mentioned three-electrode battery, the reference electrode further includes an active material layer that covers the main body.

[0011] As an alternative to the above-mentioned three-electrode battery, the sum of the thicknesses h1 of the main body and the active material layer and the thickness h2 of the positive electrode sheet satisfy: 0.667≤h1 / h2≤1;

[0012] And / or, the active material layer at least covers the side of the body facing the diaphragm;

[0013] And / or, the active material layer is a lithium iron phosphate layer, a lithium titanate layer, a lithium manganese iron phosphate layer, a lithium manganese phosphate layer, or a lithium titanium phosphate layer.

[0014] As an alternative to the above-mentioned three-electrode battery, the tab is elongated and extends outward along the radial direction of the main body, and the width w1 of the tab satisfies: 0.5cm≤w1≤5mm;

[0015] And / or, the length L1 of the electrode lug satisfies: 1cm≤L1≤5cm.

[0016] As an alternative to the above-mentioned three-electrode battery, the main body is provided with multiple through holes, and the maximum cross-sectional width w2 of the through holes satisfies: 1μm≤w2≤50μm;

[0017] The sum of the areas of all the through holes is 1.3% to 16.4% of the area of ​​the unopened parts of the body.

[0018] As an alternative to the aforementioned three-electrode battery, the through holes are distributed in an array at equal intervals along the inner diameter to the outer diameter of the main body.

[0019] As an alternative to the above-mentioned three-electrode battery, the connection end of the electrode near the main body is covered with a first insulating layer, and the first insulating layer and the outer edge of the main body are spaced apart along the length direction of the electrode to form an exposed conductive area.

[0020] As an alternative to the above-mentioned three-electrode battery, the dimension L2 of the conductive region along the length direction of the electrode tab satisfies: 0.5cm≤L2≤1cm; the dimension L3 of the first insulating layer along the length direction of the electrode tab satisfies: 0.5cm≤L3≤1cm.

[0021] And / or, the first insulating layer is polyimide, polyethylene terephthalate, polyethylene, or polytetrafluoroethylene.

[0022] As an alternative to the above-mentioned three-electrode battery, the thickness of the first insulating layer is 10-50 μm.

[0023] The beneficial effects of this utility model are:

[0024] In the three-electrode battery provided by this utility model, the annular main body of the reference electrode is arranged around the outer edge of the positive electrode and spaced apart from the positive electrode, so that the positive electrode and the reference electrode are located in the same layer, eliminating the need for the separator between the positive electrode and the reference electrode in the prior art. On the one hand, this helps to reduce costs and the overall thickness of the battery. On the other hand, it can reduce the interference of the separator on battery performance testing, accurately detect the potential changes of the positive and negative reference electrodes, and reduce the spatial steric hindrance effect of the reference electrode in the whole cell.

[0025] Compared with existing technologies that use lithium metal to make reference electrodes or in-situ electrodeposit lithium on the surface of copper wires, the reference electrode provided by this invention also includes an active material layer covering the main body, which can reduce operational risks, have a long service life, and meet the long-term cyclic monitoring requirements.

[0026] The main body is provided with through holes, which allows the electrolyte to fully wet the electrode and separator materials, ensuring uniform distribution and fluidity of lithium ion concentration and reducing test accuracy errors. Attached Figure Description

[0027] Figure 1 This is an exploded view of the three-electrode battery provided by this utility model;

[0028] Figure 2 This is a cross-sectional view of the positive electrode, reference electrode, negative electrode, and separator provided by this utility model;

[0029] Figure 3 This is a cross-sectional view of the positive electrode and the reference electrode provided by this utility model;

[0030] Figure 4 This is a schematic diagram of the structure of the positive electrode, reference electrode, and negative electrode provided by this utility model.

[0031] In the picture:

[0032] 10. Positive electrode plate; 20. Separator; 30. Negative electrode plate; 40. Reference electrode; 41. Current collector; 411. Main body; 4111. Through hole; 412. Tab; 42. First insulating layer; 43. Active material layer; 51. Positive electrode shell; 52. Negative electrode shell; 60. Spring; 70. First gasket; 80. Second gasket; 90. Second insulating layer. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0034] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0037] like Figure 1 As shown, this embodiment provides a three-electrode battery, including a housing and a positive electrode 10, a separator 20, and a negative electrode 30 sequentially stacked within the housing. The separator 20 is located between the positive electrode 10 and the negative electrode 30 to prevent direct contact between them. The housing includes a positive electrode housing 51 and a negative electrode housing 52, which, when connected, form a receiving cavity. The positive electrode 10, the separator 20, and the negative electrode 30 are located within this receiving cavity.

[0038] To monitor the changes in positive and negative electrode potentials in real time during charging and discharging, the three-electrode battery also includes a reference electrode 40. In the prior art, the reference electrode is placed between the positive and negative electrode plates. This not only requires the addition of a separator for insulation, but also, because the reference electrode has a certain size, the battery needs to bypass the reference electrode during charging and discharging to perform lithium insertion and extraction, which prolongs the transport distance of the lithium-ion battery and increases polarization. Furthermore, the negative electrode plate partially blocked by the reference electrode cannot insert lithium, resulting in uneven local lithium-ion concentration, which can cause deviations in the reference monitoring results.

[0039] To address the aforementioned issues, the reference electrode 40 in this embodiment includes a current collector 41. The current collector 41 includes an annular body 411 and a tab 412 connected to the body 411. The body 411 is arranged around the outer edge of the positive electrode 10 and spaced apart from the positive electrode 10, so that the positive electrode 10 and the reference electrode 40 are located in the same layer. There is no need to provide insulating components such as a separator between the positive electrode 10 and the reference electrode 40. On the one hand, this helps to reduce costs and the overall thickness of the battery. On the other hand, it can reduce the interference of insulating components such as separators on battery performance testing, accurately detect the potential changes of the positive and negative references, and reduce the spatial steric hindrance effect of the reference electrode 40 in the whole battery.

[0040] In some embodiments, the current collector 41 can be aluminum foil, which has good conductivity and is inexpensive. In other embodiments, the current collector 41 can also be made of other conductive materials.

[0041] In some embodiments, such as Figure 1 and Figure 2 As shown, both the positive electrode 10 and the negative electrode 30 are circular, and the main body 411 is annular. The inner radius R1 of the main body 411, the outer radius R2 of the main body 411, the radius R3 of the positive electrode 10, and the radius R4 of the negative electrode 30 satisfy: 0.05≤(R2-R1) / R3≤0.36, and R4>R2>R1>R3.

[0042] Understandably, a smaller value of (R2-R1) / R3 (e.g., less than 0.05) indicates a smaller radial width of the main body 411, assuming the size of the positive electrode 10 remains constant. This increases the difficulty of manufacturing the main body 411 and the greater the risk of short circuits. Conversely, a larger value of (R2-R1) / R3 (e.g., greater than 0.36) results in a larger radial width of the main body 411 and a smaller size of the positive electrode 10. While this reduces the manufacturing difficulty of the main body 411, it does not reflect the actual battery conditions and cannot effectively simulate the internal environment of the battery, rendering the reference data meaningless. Therefore, setting 0.05 ≤ (R2-R1) / R3 ≤ 0.36 comprehensively considers factors such as manufacturing difficulty, short-circuit risk, and simulation effectiveness to ensure that the reference data reflects the actual operating conditions of the battery.

[0043] For example, typical non-limiting values ​​for (R2-R1) / R3 can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, or 0.36.

[0044] In some embodiments, in order to ensure that the positive electrode 10 and the main body 411 are spaced apart, the main body 411 and the positive electrode 10 are arranged at the same center, so as to ensure that the inner ring sidewalls of the main body 411 are spaced apart from the positive electrode 10.

[0045] In existing technologies, reference electrodes typically use lithium sheets or foils, or lithium is electrodeposited in situ on the surface of metal wires such as copper wire. Since lithium is a hazardous material, there are certain operational risks during its preparation. Using copper or silver wires as reference electrodes requires lithium plating on their surface under a small current. On the one hand, the lithium layer is thin, with a lifespan of only about 7 days, which cannot meet the requirements for long-term cyclic monitoring. On the other hand, the exposed metal wire in the electrolyte can cause interference to the electrical signal.

[0046] To address the above problems, in some embodiments, such as Figure 3 As shown, the reference electrode 40 also includes an active material layer 43, which covers the main body 411. By setting the active material layer 43, lithium plating is not required, and the main body 411 does not need to use lithium metal sheets or lithium foils, which helps to reduce operational risks and costs, and ensures that the reference electrode 40 can work for a long time to meet the monitoring requirements of long-term cycles.

[0047] Optionally, the active material layer 43 can be a lithium iron phosphate layer, a lithium titanate layer, a lithium manganese iron phosphate layer, a lithium manganese phosphate layer, or a lithium titanium phosphate layer, which can more accurately obtain potential changes.

[0048] In some other embodiments, the active material layer 43 may include at least two of the following: a lithium iron phosphate layer, a lithium titanate layer, a lithium manganese iron phosphate layer, a lithium manganese phosphate layer, and a lithium titanium phosphate layer.

[0049] In some embodiments, the active material layer 43 covers the side of the body 411 facing the diaphragm 20. In other embodiments, the active material layer 43 is provided on both the side of the body 411 facing the diaphragm 20 and the side of the body 411 facing away from the diaphragm 20.

[0050] In some embodiments, the sum of the thicknesses h1 of the main body 411 and the active material layer 43 satisfies the condition h2 of the thickness of the positive electrode 10: 0.667 ≤ h1 / h2 ≤ 1. When the sum of the thicknesses h1 of the main body 411 and the active material layer 43 is greater than the thickness h2 of the positive electrode 10, that is, the active material layer 43 is thicker, it will cause the positive electrode 10 and the negative electrode 30 to not adhere tightly, resulting in a large gap, increasing the ion transport path, and affecting the impedance test results. When the sum of the thicknesses h1 of the main body 411 and the active material layer 43 is too small, the active material layer 43 is too thin, resulting in less active material in the active material layer 43, making it impossible to accurately measure the potential of the positive electrode 10 or the negative electrode 30.

[0051] In some embodiments, the main body 411 is provided with a plurality of through holes 4111, which can reduce the influence of the reference electrode 40 on the electrolyte flow, thereby reducing the test error.

[0052] In some embodiments, the maximum cross-sectional width w2 of the through-hole 4111 satisfies: 1μm ≤ w2 ≤ 50μm. If the maximum cross-sectional width of the through-hole 4111 is too large, it will affect the strength of the main body 411, causing the reference electrode 40 to easily break and become ineffective during assembly; if the maximum cross-sectional width of the through-hole 4111 is too small, it will affect the flow of the electrolyte, thereby increasing the testing error. Therefore, setting the maximum cross-sectional width w2 of the through-hole 4111 within the above range ensures both the strength of the main body 411 and reduces the impact on the fluidity of the electrolyte.

[0053] In some embodiments, the sum of the areas of all through holes 4111 is 1.3% to 16.4% of the area of ​​the unopened area on the main body 411. This is to control the opening area while accelerating the wetting of the electrolyte, so as to avoid the main body 411 from breaking due to the force exerted during assembly and testing due to the excessive opening area, thereby losing its monitoring function.

[0054] For example, a typical non-limiting value for the ratio of the sum of the areas of all through holes 4111 to the area of ​​unopened holes on the body 411 can be 1.3%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, or 16.4%.

[0055] In some embodiments, multiple through holes 4111 are provided, and the multiple through holes 4111 are distributed in an array at equal intervals along the inner radial and outer diameter directions of the main body 411, so that the openings are more uniform, which is conducive to the full flow of electrolyte, so that the electrolyte can fully wet the positive electrode 10, the negative electrode 30 and the separator 20, ensuring uniform distribution of lithium ion concentration and fluidity, and reducing test accuracy error.

[0056] In some embodiments, such as Figure 4 As shown, the through hole 4111 is a circular hole, and multiple circular holes are distributed in a circular array. In some other embodiments, the shape of the through hole 4111 can be a triangle, a square, or other polygons, or it can be an ellipse or other irregular shapes.

[0057] In some embodiments, such as Figure 4 As shown, the tab 412 is elongated and extends outward along the radial direction of the main body 411. The width w1 of the tab 412 satisfies: 0.5cm≤w1≤5mm. The width w1 of the tab 412 being within the above range ensures the stability of current conduction.

[0058] For example, typical non-limiting values ​​for the width w1 of the tab 412 are 0.5cm, 1cm, 1.5cm, 2cm, 2.5cm, 3cm, 3.5cm, 4cm, 4.5cm, and 5cm.

[0059] In some embodiments, the length L1 of the tab 412 satisfies: 1cm≤L1≤5cm.

[0060] For example, typical non-limiting values ​​for the length L1 of the tab 412 are 1cm, 1.5cm, 2cm, 2.5cm, 3cm, 3.5cm, 4cm, 4.5cm, and 5cm.

[0061] In some embodiments, the connection end of the tab 412 near the main body 411 is covered with a first insulating layer 42. The first insulating layer 42 and the outer edge of the main body 411 are spaced apart along the length direction of the tab 412, forming an exposed conductive area 4121. By providing the first insulating layer 42, the pressure between the positive electrode housing 51 and the negative electrode housing 52 during packaging can be prevented from causing the tab 412 to break and the reference electrode 40 to fail. At the same time, it can also prevent the reference electrode 40 from short-circuiting when it comes into contact with the positive electrode housing 51, thereby avoiding affecting the reference potential and ensuring the accuracy of monitoring data such as positive and negative references.

[0062] It is understandable that when the casing is encapsulated, the first insulating layer 42 is located between the positive electrode casing 51 and the negative electrode casing 52. The first insulating layer 42 covers the tab 412 to prevent it from being pinched off by the positive electrode casing 51 and the negative electrode casing 52.

[0063] In some embodiments, the first insulating layer 42 may be an insulating tape, which is an electrolyte-resistant material.

[0064] For example, the first insulating layer 42 may be made of materials such as polyimide (PI), polyethylene terephthalate (PET), polyethylene (PE), or polytetrafluoroethylene (PTFE) to improve electrolyte resistance while ensuring insulation properties.

[0065] In some other embodiments, the first insulating layer 42 may include at least two of the following: a polyimide layer, a polyethylene terephthalate layer, a polyethylene layer, and a polytetrafluoroethylene layer, to improve material properties.

[0066] Understandably, because the first insulating layer 42 has a certain thickness, it can increase the local lithium-ion migration distance within a three-electrode battery, causing deviations in the test data. Therefore, by setting the conductive region 4121, the influence of the first insulating layer 42 on the increased lithium-ion migration distance can be reduced, thereby improving the accuracy of the test data.

[0067] In some embodiments, the dimension L2 of the conductive region 4121 along the length direction of the tab 412 satisfies: 0.5cm ≤ L2 ≤ 1cm. This arrangement ensures that the first insulating layer 42 is spaced apart from the main body 411, preventing the first insulating layer 42 from affecting the main body 411.

[0068] For example, typical non-limiting values ​​for the dimension L2 of the conductive region 4121 along the length direction of the tab 412 are 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, and 1 cm.

[0069] In some embodiments, the dimension L3 of the first insulating layer 42 along the length direction of the tab 412 satisfies: 0.5cm≤L3≤1cm, so as to ensure that the first insulating layer 42 has a certain length and that the first insulating layer 42 can contact the positive electrode shell 51 and the negative electrode shell 52, so as to avoid the tab 412 breaking during shell encapsulation.

[0070] For example, typical non-limiting values ​​for the dimension L3 of the first insulating layer 42 along the length direction of the tab 412 are 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, and 1 cm.

[0071] In some embodiments, the thickness of the first insulating layer 42 is 10–50 μm to better protect the tab 412. Exemplarily, the thickness of the first insulating layer 42 is 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm.

[0072] In some embodiments, reference is made to Figure 1 As shown, a spring sheet 60 and a first gasket 70 are also provided between the positive electrode housing 51 and the positive electrode plate 10. The spring sheet 60 is located between the positive electrode housing 51 and the first gasket 70. The spring sheet 60 and the first gasket 70 can buffer the force between the positive electrode housing 51, the positive electrode plate 10, and the reference electrode 40, so as to avoid deformation and damage to the positive electrode plate 10 and the reference electrode 40, while also ensuring good interface contact of the electrode plates.

[0073] In some embodiments, a second gasket 80 is provided between the negative electrode housing 52 and the negative electrode sheet 30, and the second gasket 80 can protect the negative electrode sheet 30.

[0074] In some embodiments, a second insulating layer 90 is provided around the edge of the negative electrode housing 52. The second insulating layer 90 can cover the edge of the negative electrode housing 52 so as to avoid short circuit when the positive electrode housing 51 and the negative electrode housing 52 are assembled during the three-electrode battery packaging.

[0075] Optionally, the negative electrode housing 52 includes a bottom plate and a side plate. The side plate is disposed around the circumferential edge of the bottom plate. A second insulating layer 90 is sleeved on the side plate. The second insulating layer 90 covers the inner circumferential surface, the outer circumferential surface, and the end face of the side plate facing the positive electrode housing 51, so as to provide insulation protection for the negative electrode housing 52 and the positive electrode housing 51.

[0076] Alternatively, the second insulating layer 90 may be made of resin, epoxy resin, polytetrafluoroethylene or polyethylene.

[0077] The assembly process of the above three-electrode battery is as follows:

[0078] Place the second gasket 80 and the negative electrode 30 into the negative electrode housing 52 in sequence. After adding an appropriate amount of electrolyte into the negative electrode housing 52, lay the separator 20 flat on the negative electrode 30. Then, place the reference electrode 40 and the positive electrode 10 in the housing, and place the positive electrode 10 at the center of the main body 411 of the reference electrode 40. Then, place the first gasket 70 and the spring 60 in the housing, connect the positive electrode housing 51 and the negative electrode housing 52, and seal them to complete the assembly of the three-electrode battery.

[0079] In some embodiments, the reference electrode 40 is calibrated after the three-electrode battery is assembled. Specifically, after the three-electrode battery is assembled, it is left to stand for 60 minutes, and then the reference electrode 40 and the negative electrode 30 are connected on the charge-discharge test cabinet and charged to complete the calibration process of the reference electrode 40, thereby extending the service life of the reference electrode 40.

[0080] Specifically, during the reference charge adjustment process, the reference electrode 40 and the negative electrode 30 are connected for charging. A constant current charging method is used to adjust the charge state of the reference electrode 40, with a charging rate of 0.01C-0.33C and a charging time of 0.1h-10h.

[0081] Preferably, the State of Charge (SOC) of the reference electrode 40 is 50%. Too low or too high SOC will cause the potential of the reference electrode 40 to be unstable, making it impossible to accurately monitor the changes in the positive and negative reference potentials. At the same time, too high a charging rate will cause polarization of the reference electrode 40, affecting the service life of the reference electrode 40.

[0082] To demonstrate the excellent service life of the three-electrode batteries described above, the present invention provides the following embodiments and comparative examples, and compares the service life of the three-electrode batteries.

[0083] Example 1

[0084] In this embodiment, the radius R4 of the negative electrode 30 is 8mm, the radius R3 of the positive electrode 10 is 6mm, the inner radius R1 of the main body 411 is 7mm, and the outer radius R2 of the main body 411 is 7.5mm. Among them, (R2-R1) / R3=0.083, and R4>R2>R1>R3, which can ensure that the three-electrode battery does not short-circuit.

[0085] In this embodiment, the active material layer 43 is a lithium iron phosphate layer, the conductive region 4121 has a dimension L2 of 1 cm along the length direction of the tab 412, the thickness of the first insulating layer 42 is 25 μm, and the dimension L3 of the first insulating layer 42 has a dimension L3 of 1 cm along the length direction of the tab 412.

[0086] In this embodiment, the number of through holes 4111 etched by laser on the main body 411 is 200. The through holes 4111 are circular holes with a diameter of 5μm. The through holes 4111 are arranged in an array along the inner radial and outer diameter directions of the main body 411.

[0087] In this embodiment, when adjusting the charge of the reference electrode 40, the charging rate is selected as 0.1C and the time is 5h, so as to adjust the state of charge of the reference electrode 40 to 50% SOC, thereby ensuring the test accuracy of the reference electrode 40.

[0088] Example 2

[0089] The difference between the three-cell electrode in this embodiment and that in embodiment 1 is that the loading time for the reference electrode 40 is 1 hour, while the rest of the structure and loading process are the same.

[0090] Example 3

[0091] The difference between the three-cell electrode in this embodiment and that in embodiment 1 is that the loading time for the reference electrode 40 is 9 hours, while the rest of the structure and loading process are the same.

[0092] Example 4

[0093] The difference between the three-cell electrode in this embodiment and that in embodiment 1 is that the loading rate is 0.05C during the loading process of the reference electrode 40, while the rest of the structure and loading process are the same.

[0094] Example 4

[0095] The difference between the three-cell electrode in this embodiment and that in embodiment 1 is that the loading rate is 0.2C during the loading process of the reference electrode 40, while the rest of the structure and loading process are the same.

[0096] Comparative Example 1

[0097] The structure of the three-electrode battery in this comparative example is the same as that in Example 1. The difference is that the reference electrode 40 is not subjected to load adjustment, and the change in negative electrode potential is directly detected.

[0098] Comparative Example 2

[0099] The structure of the three-electrode battery in this comparative example differs from that in Example 1 in that the reference electrode 40 is made of copper wire with a diameter of 50 μm. After the copper wire is installed in the battery, the positive electrode 10 and the reference electrode 40 are connected, and the negative electrode 30 and the reference electrode 40 are connected, respectively. The batteries are then charged at 10 μA for 4 hours to complete the fabrication of the copper wire lithium-plated reference electrode 40.

[0100] A lithium battery charge-discharge test cabinet was used to perform a 0.33C charge-discharge cycle on the battery, and the potential between the negative electrode 30 and the reference electrode 40 was monitored. When the negative reference potential deviated abnormally, the reference electrode 40 was considered to have reached the end of its service life.

[0101] The lifespan of the reference electrodes in the above embodiments and comparative examples is summarized in the following table:

[0102]

[0103]

[0104] By comparing the service life of the reference electrode 40 in each embodiment and comparative example in the table above, it can be seen that both the loading ratio and the loading duration will affect the service life of the reference electrode 40.

[0105] As can be seen from Examples 1, 2, and 3, both excessively long and short adjustment times will affect the service life of the reference electrode 40. As can be seen from Examples 1 and 4, increasing the adjustment ratio will shorten the service life of the reference electrode 40. As can be seen from Examples 1 and Comparative Example 1, adjustment of the reference electrode 40 is necessary to ensure a longer service life. As can be seen from Examples 1 and Comparative Example 2, the service life of the reference electrode 40 with the above-described structure provided by this invention is far greater than the service life of the reference electrode 40 directly using copper wire.

[0106] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A three-electrode battery, comprising a positive electrode (10), a separator (20), and a negative electrode (30) stacked sequentially, characterized in that, The three-electrode battery also includes a reference electrode (40); The reference electrode (40) includes a current collector (41), which includes an annular body (411) and a tab (412) connected to the body (411). The body (411) is disposed around the outer edge of the positive electrode (10) and spaced apart from the positive electrode (10).

2. The three-electrode battery according to claim 1, characterized in that, The positive electrode (10) and the negative electrode (30) are both circular, and the main body (411) is annular. The inner radius R1 of the main body (411), the outer radius R2 of the main body (411), the radius R3 of the positive electrode (10) and the radius R4 of the negative electrode (30) satisfy: 0.05≤(R2-R1) / R3≤0.36, and R4>R2>R1>R3; And / or, the main body (411) is annular, the positive electrode (10) is circular, and the main body (411) and the positive electrode (10) are arranged at the same center.

3. The three-electrode battery according to claim 1, characterized in that, The reference electrode (40) further includes an active material layer (43) that covers the body (411).

4. The three-electrode battery according to claim 3, characterized in that, The sum of the thicknesses h1 of the main body (411) and the active material layer (43) and the thickness h2 of the positive electrode (10) satisfy: 0.667≤h1 / h2≤1; And / or, the active material layer (43) at least covers the side of the body (411) facing the diaphragm (20); And / or, the active material layer (43) is a lithium iron phosphate layer, a lithium titanate layer, a lithium manganese iron phosphate layer, a lithium manganese phosphate layer, or a lithium titanium phosphate layer.

5. The three-electrode battery according to claim 1, characterized in that, The tab (412) is elongated and extends outward along the radial direction of the main body (411), and the width w1 of the tab (412) satisfies: 0.5cm≤w1≤5mm; And / or, the length L1 of the tab (412) satisfies: 1cm≤L1≤5cm.

6. The three-electrode battery according to any one of claims 1-5, characterized in that, The main body (411) is provided with a plurality of through holes (4111), and the maximum cross-sectional width w2 of the through holes (4111) satisfies: 1μm≤w2≤50μm; The sum of the areas of all the through holes (4111) is 1.3% to 16.4% of the area of ​​the unopened parts on the body (411).

7. The three-electrode battery according to claim 6, characterized in that, The through holes (4111) are distributed in an array at equal intervals along the inner diameter to the outer diameter of the main body (411).

8. The three-electrode battery according to any one of claims 1-5, characterized in that, The tab (412) near the connection end of the body (411) is covered with a first insulating layer (42). The first insulating layer (42) and the outer edge of the body (411) are spaced apart along the length direction of the tab (412) to form an exposed conductive area (4121).

9. The three-electrode battery according to claim 8, characterized in that, The dimension L2 of the conductive area (4121) along the length direction of the tab (412) satisfies: 0.5cm≤L2≤1cm; the dimension L3 of the first insulating layer (42) along the length direction of the tab (412) satisfies: 0.5cm≤L3≤1cm; And / or, the first insulating layer (42) is polyimide, polyethylene terephthalate, polyethylene or polytetrafluoroethylene.

10. The three-electrode battery according to claim 9, characterized in that, The thickness of the first insulating layer (42) is 10-50 μm.

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