Three-electrode button cell

Abstract

The utility model relates to a three-electrode button cell. The three-electrode button cell comprises: a top cover, the end face of which is provided with a through hole; the electrode assembly comprises a negative plate, a first diaphragm and a positive plate which are stacked in sequence; the lithium plate is arranged between the top cover and the electrode assembly, and the lithium plate and the positive plate or the negative plate of the electrode assembly are arranged at intervals through a second diaphragm; the conductive piece is arranged between the lithium sheet and the top cover, is in ohmic contact with the lithium sheet and is insulated from the top cover; the sealing ring is arranged on the inner edge of the through hole of the top cover and abuts against the conductive piece penetrating through the through hole; and the shell is buckled with the top cover to form a closed cavity. The lithium sheet is arranged between the negative plate and the top cover of the button cell as the reference electrode, the electric potential of the reference electrode is exported in real time by the conductive piece, the electrochemical behavior of an electrode interface can be accurately analyzed in cooperation with potential signals of the positive electrode and the negative electrode, and the button cell is stable in structure, convenient to assemble, particularly good in sealing performance and high in reliability. And in-situ three-electrode testing can be carried out for many times.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to button batteries, and more particularly to a three-electrode button battery. Background Technology

[0002] In the field of lithium-ion batteries, metallic lithium is typically used as the counter electrode to assemble a button half-cell with a positive or negative electrode. The voltage change of the positive or negative electrode is then tested to perform a preliminary test on the electrochemical performance of the lithium-ion battery electrode materials. This testing method is widely used in the research and development and performance evaluation of lithium-ion batteries.

[0003] With the continuous development of lithium-ion battery technology, the requirements for the accuracy of testing the electrochemical performance of electrode materials are increasing. However, conventional button cells are usually two-electrode systems, which can only test the potential difference between the positive or negative electrode and metallic lithium, and cannot test the absolute potential of the positive or negative electrode materials, nor can they simultaneously obtain the potential of the reference electrode during the test, making it difficult to meet the needs of precise electrochemical analysis. Overcoming this inherent limitation has become a key factor in achieving accurate analysis.

[0004] To address the shortcomings of two-electrode systems, three-electrode battery structures have been extensively studied. In a conventional lithium-ion battery, a lithium sheet encased in a separator or a lithium-plated conductive wire is placed between the positive and negative electrodes as a reference electrode, with the electrical signal extracted through the conductive wire. However, this structure still has many drawbacks. For example, the conductive wire used to extract the signal affects the battery's sealing performance, assembly is complex, and the reference electrode has poor stability. This leads to problems such as electrolyte leakage and data drift during testing, affecting the accuracy and reliability of the test results. Furthermore, the corresponding three-electrode battery structure cannot achieve long-term stable use and cannot be used for subsequent related electrochemical tests, resulting in material waste, increased testing costs, and hindering efficient testing.

[0005] CN114784224A discloses a reference electrode, a three-electrode battery cell, and a lithium-ion battery. The reference electrode disclosed in this invention uses a porous material as its substrate, ensuring electrolyte flowability and not affecting the performance of the three-electrode battery cell. It uses a stable lithium iron phosphate layer as a coating layer for the substrate framework, effectively solving the problem in existing technologies where lithium used as a reference electrode or its coating layer reacts with the electrolyte and additives, significantly improving the stability of the reference electrode.

[0006] CN119361600A discloses a lithium metal reference electrode for a three-electrode lithium-ion battery. The lithium metal reference electrode includes a lithium metal component encapsulated by a polymer solid electrolyte membrane as a first protective layer and a Li-IL@MOFs / polymer composite film based on a metal-organic framework material as a second protective layer. This reduces the risk of corrosion of the lithium metal reference electrode during use and improves its stability when the entire reference electrode is placed outside the battery cell.

[0007] CN117276690A discloses a lithium-ion three-electrode battery and its preparation method. The reference electrode includes a metal sheet, a metal wire, and an insulating tape connecting the metal sheet and the metal wire. This reference electrode does not require activation and can realize the detection of the lithium-ion three-electrode battery formation stage. It is simple to operate, has high manufacturing efficiency, and long cycle life.

[0008] Therefore, it is of great significance to provide a three-electrode battery that is structurally stable, reliably sealed, easy to assemble, and capable of long-term stable testing. Utility Model Content

[0009] To address the shortcomings of existing technologies, the purpose of this invention is to provide a three-electrode button cell. By placing a lithium sheet as a reference electrode between the negative electrode and the top cover of the button cell, the potential of the reference electrode is extracted in real time by a conductive component. Combined with the potential signals of the positive and negative electrodes, the electrochemical behavior of the electrode interface can be accurately analyzed. Furthermore, the button cell has a stable structure, is easy to assemble, and has particularly good sealing properties, enabling multiple in-situ three-electrode tests.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, this utility model provides a three-electrode button cell, the three-electrode button cell comprising:

[0012] The top cover has a through hole on its end face; the electrode assembly includes a negative electrode, a first separator, and a positive electrode stacked sequentially; a lithium sheet is disposed between the top cover and the electrode assembly, and is spaced apart from the positive or negative electrode of the electrode assembly by a second separator, the diameter of the lithium sheet being less than 1 / 5 of the diameter of the positive electrode; a conductive element is disposed between the lithium sheet and the top cover, one end of the conductive element being in ohmic contact with the lithium sheet, and the other end penetrating through the through hole of the top cover, exposed on the surface of the top cover, and insulated from the top cover; a sealing ring is disposed at the inner edge of the through hole of the top cover and abuts against the conductive element penetrating through the through hole; and a housing is fastened to the top cover to form a sealed cavity.

[0013] Preferably, the thickness of the lithium sheet is less than 50 μm.

[0014] Preferably, the diameter of the lithium sheet is smaller than the diameter of the second separator, and the diameter of the second separator is smaller than the diameter of the positive electrode sheet.

[0015] Preferably, the conductive component includes an enameled wire with the enamel removed at both ends of the axial direction, exposing bare metal wires. One end of the metal wire is in ohmic contact with the lithium sheet, and the other end of the metal wire passes through a through hole and is exposed on the surface of the top cover. The middle part of the enameled wire has intact enamel, penetrates the through hole, is insulated from the top cover, and abuts against a sealing ring at the inner edge of the through hole.

[0016] Preferably, the conductive component includes a T-shaped terminal, the T-shaped terminal includes an end face and a column body fixedly connected to the end face, an insulating gasket is provided between the end face and the top cover, and the end of the column body away from the end face passes through the insulating gasket and the through hole of the top cover in sequence, is exposed on the surface of the top cover, and abuts against the sealing ring at the inner edge of the through hole.

[0017] Preferably, the end face of the T-type terminal completely covers the lithium sheet, and the second diaphragm completely covers the end face of the T-type terminal.

[0018] Preferably, the end face of the T-type terminal block has a shape including a square, rectangle, triangle, or circle.

[0019] Preferably, the thickness of the insulating pad is less than 0.5 mm.

[0020] Preferably, a support member is provided between the positive electrode sheet and the housing.

[0021] Preferably, the support member includes a steel sheet and a disc spring sheet.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention uses a lithium sheet as a reference electrode placed between the negative electrode and the top cover of a button cell. The potential of the reference electrode is exported in real time by a conductive component. Combined with the potential signals of the positive and negative electrodes, the electrochemical behavior of the electrode interface can be accurately analyzed. Furthermore, the button cell has a stable structure, is easy to assemble, and has good sealing properties, enabling multiple in-situ three-electrode tests. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the three-electrode button cell provided in Example 1.

[0025] Figure 2 This is a schematic diagram of the structure of the three-electrode button cell provided in Example 2.

[0026] Among them, 1-top cover; 2-sealing ring; 31-negative electrode sheet; 32-first diaphragm; 33-positive electrode sheet; 4-lithium sheet; 5-second diaphragm; 61-end face of T-type terminal; 62-post body of T-type terminal; 63-enameled wire; 7-insulating gasket; 81-steel sheet; 82-disc spring sheet; 9-shell. Detailed Implementation

[0027] The technical solution of this utility model will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of this utility model and should not be considered as specific limitations thereof.

[0028] The "range" disclosed in this utility model can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and maximum range values ​​of 3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this utility model, unless otherwise specified, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0029] Unless otherwise specified, all embodiments and optional embodiments of this utility model can be combined with each other to form new technical solutions.

[0030] The term "embodiment" as used in this utility model means that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment or implementation of this utility model. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this utility model can be combined with other embodiments.

[0031] In this utility model, open-ended technical features or solutions described with terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions composed of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0032] In this utility model, the word "first" in "first aspect" is used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should it be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first" only serves a non-exhaustive enumeration purpose and should be understood not to constitute a closed limitation on quantity.

[0033] In this utility model, "optional" means that it is optional, that is, it refers to any one of the two parallel solutions of "having" or "not having". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" option is independent.

[0034] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0035] In one specific embodiment, the present invention provides a three-electrode button cell battery, the three-electrode button cell battery comprising:

[0036] The top cover has a through hole on its end face; the electrode assembly includes a negative electrode, a first separator, and a positive electrode stacked sequentially; a lithium sheet is disposed between the top cover and the electrode assembly, and is spaced apart from the positive or negative electrode of the electrode assembly by a second separator, the diameter of the lithium sheet being less than 1 / 5 of the diameter of the positive electrode; a conductive element is disposed between the lithium sheet and the top cover, one end of the conductive element being in ohmic contact with the lithium sheet, and the other end penetrating through the through hole of the top cover, exposed on the surface of the top cover, and insulated from the top cover; a sealing ring is disposed at the inner edge of the through hole of the top cover and abuts against the conductive element penetrating through the through hole; and a housing is fastened to the top cover to form a sealed cavity.

[0037] In this invention, based on the structure of a button cell, a lithium sheet is placed between the negative electrode and the top cover of the button cell as a reference electrode. The potential of the reference electrode is exported in real time by a conductive component. Combined with the potential signals of the positive and negative electrodes, the electrochemical behavior of the electrode interface can be accurately analyzed. Furthermore, the button cell has a stable structure, is easy to assemble, and has good sealing properties, enabling multiple in-situ three-electrode tests.

[0038] By using an independent lithium sheet as the reference electrode and extracting the signal through a conductive component, the reference potential can be monitored synchronously during battery charging and discharging, significantly improving the accuracy of electrochemical testing.

[0039] The top cover and housing can be made of stainless steel, which can conduct electricity and output negative and positive potential signals.

[0040] In some embodiments, the thickness of the lithium sheet is less than 50 μm, for example, it can be 50 μm, 45 μm, 40 μm, 35 μm, 30 μm, 25 μm, 20 μm, 15 μm or 10 μm.

[0041] In some embodiments, the diameter of the lithium sheet is smaller than the diameter of the second separator, and the diameter of the second separator is smaller than the diameter of the positive electrode sheet.

[0042] In button batteries, the size of the positive electrode is typically slightly smaller than that of the negative electrode to ensure that all lithium ions released from the positive electrode are received by the negative electrode. Therefore, in this invention, it is preferable that the diameter of the lithium electrode is smaller than the diameter of the second separator, and the diameter of the second separator is smaller than the diameter of the positive electrode. This ensures that the lithium electrode does not undergo an electrochemical reaction with the positive and negative electrodes, and also ensures good ohmic contact between the positive or negative electrode and the top cover or casing. This, in turn, ensures the accuracy of the output reference electrode potential signal, positive electrode potential signal, and negative electrode potential signal, enabling precise analysis of the electrochemical behavior of the electrode interface.

[0043] In some embodiments, the conductive element includes an enameled wire with its axial ends stripped of enamel to expose bare metal wire. One end of the metal wire is in ohmic contact with the lithium sheet, and the other end of the metal wire passes through a through-hole and is exposed on the surface of the top cover. The middle portion of the enameled wire has intact enamel, penetrates the through-hole, is insulated from the top cover, and abuts against a sealing ring at the inner edge of the through-hole.

[0044] In some embodiments, the conductive element includes a T-shaped terminal, the T-shaped terminal includes an end face and a column fixedly connected to the end face, an insulating gasket is provided between the end face and the top cover, and one end of the column away from the end face passes through the insulating gasket and the through hole of the top cover in sequence, is exposed on the surface of the top cover, and abuts against the sealing ring at the inner edge of the through hole.

[0045] An insulating gasket is placed between the end face of the T-type terminal and the top cover. This not only ensures insulation between the lithium sheet and the top cover, but also, together with the sealing ring between the inner edges of the through hole, the double sealing structure design effectively prevents electrolyte leakage and improves the battery's sealing performance and testing stability.

[0046] The metal conductor of the enameled wire and the T-type terminal can be made of materials such as copper, which can achieve conductivity and output the reference electrode, i.e., the potential signal of the lithium chip.

[0047] In some embodiments, the end face of the T-type terminal completely covers the lithium sheet, and the second diaphragm completely covers the end face of the T-type terminal.

[0048] In some embodiments, the thickness of the insulating pad is less than 0.5 mm, for example, it can be 0.5 mm, 0.45 mm, 0.4 mm, 0.35 mm, 0.3 mm, 0.25 mm, 0.2 mm, 0.15 mm or 0.1 mm.

[0049] In some embodiments, the end face of the T-terminal may be square, rectangular, triangular, or circular. The end face of the T-terminal can maintain good ohmic contact with the lithium plate.

[0050] In some embodiments, a support member is also provided between the positive electrode and the housing.

[0051] In some embodiments, the support includes a steel sheet and a disc spring sheet.

[0052] By setting steel plates and disc spring plates between the positive electrode and the housing to support the three-electrode assembly, the spring plates are used to provide elastic preload, ensuring the stability of the contact between the three-electrode assembly and reducing the impact of contact resistance fluctuations on the test results.

[0053] The three-electrode button cell also includes an electrolyte. The three-electrode button cell provided by this invention can use commercially available lithium-ion battery electrolyte.

[0054] The numerical range described in this utility model includes not only the point values ​​listed above, but also any point values ​​within the numerical range not listed above. Due to space limitations and for the sake of brevity, this utility model will not exhaustively list the specific point values ​​included in the range.

[0055] Example 1

[0056] This embodiment provides a three-electrode button cell, such as Figure 1 As shown, the three-electrode button cell includes:

[0057] Top cover 1, the end face of the top cover 1 is provided with a through hole, and a sealing ring 2 is provided on the inner edge of the through hole;

[0058] The electrode assembly includes a negative electrode 31, a first diaphragm 32 and a positive electrode 33 stacked sequentially.

[0059] A lithium sheet 4 is disposed between the top cover 1 and the negative electrode 31, and is spaced apart from the negative electrode 31 by a second separator 5. The diameter of the lithium sheet 4 is 1 / 5 of the diameter of the positive electrode 33.

[0060] A T-shaped terminal is disposed between the lithium sheet 4 and the top cover 1. The end face 61 of the T-shaped terminal is fixedly connected to the body 62 of the T-shaped terminal. The end face 61 of the T-shaped terminal is circular, completely covering the lithium sheet 4 and being completely covered by the second diaphragm 5. An insulating gasket 7 is disposed between the end face 61 of the T-shaped terminal and the top cover 1. The end of the body 62 of the T-shaped terminal away from the end face 61 of the T-shaped terminal passes through the insulating gasket 7 and the through hole of the top cover 1 in sequence, is exposed on the surface of the top cover 1, and abuts against the sealing ring 2 at the inner edge of the through hole.

[0061] The housing 9 is fastened to the top cover 1 to form a sealed cavity, into which an electrolyte is injected.

[0062] Both the top cover 1 and the housing 9 are made of stainless steel, and the T-shaped terminal block is made of copper.

[0063] When the three-electrode button battery provided in this embodiment is used, the top cover 1, the shell 9 and the end of the T-shaped terminal 62 exposed on the surface of the top cover 1 are respectively connected to the wires to output the negative electrode potential signal, the positive electrode potential signal and the reference electrode signal, so as to realize the accurate analysis of the electrode interface reaction potential.

[0064] Example 2

[0065] This embodiment provides a three-electrode button cell, such as Figure 2 As shown, the three-electrode button cell includes:

[0066] Top cover 1, the end face of the top cover 1 is provided with a through hole, and a sealing ring 2 is provided on the inner edge of the through hole;

[0067] The electrode assembly includes a positive electrode 33, a first diaphragm 32 and a negative electrode 31 stacked sequentially.

[0068] A lithium sheet 4 is disposed between the top cover 1 and the positive electrode 33, and is spaced apart from the positive electrode 33 by a second separator 5. The diameter of the lithium sheet 4 is 1 / 8 of the diameter of the positive electrode 33.

[0069] Enamelled wire 63, with the enamel removed from both ends of the axial direction to expose the bare metal wire, one end of the metal wire is in ohmic contact with the lithium sheet 4, and the other end of the metal wire passes through the through hole and is exposed on the surface of the top cover 1. The middle part of the enamelled wire has intact enamel, passes through the through hole, is insulated from the top cover 1, and abuts against the sealing ring 2 at the inner edge of the through hole.

[0070] The support, including a steel sheet 81 and a disc spring sheet 82, is attached to the surface of the negative electrode sheet 31 away from the first diaphragm 32.

[0071] The housing 9 is fastened to the top cover 1 to form a sealed cavity, into which an electrolyte is injected.

[0072] Both the top cover 1 and the housing 9 are made of stainless steel, and the metal conductor of the enameled wire is made of copper.

[0073] When the three-electrode button battery provided in this embodiment is used, the top cover 1, the shell 9 and the exposed end of the enameled wire 63 on the surface of the top cover 1 after removing the enamel coating are respectively connected to the wire to output the positive electrode potential signal, the negative electrode potential signal and the reference electrode signal, so as to realize the accurate analysis of the reaction potential of the electrode interface.

[0074] The applicant declares that the above description is only a specific embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model fall within the protection and disclosure scope of the present utility model.

Claims

1. A three-electrode button cell, characterized in that, The three-electrode button cell includes: A top cover, wherein a through hole is provided on the end face of the top cover; An electrode assembly includes a negative electrode, a first separator, and a positive electrode stacked sequentially. A lithium sheet is disposed between the top cover and the electrode assembly, and is spaced apart from the positive or negative electrode of the electrode assembly by a second separator. The diameter of the lithium sheet is less than 1 / 5 of the diameter of the positive electrode. A conductive element is disposed between the lithium sheet and the top cover. One end of the conductive element is in ohmic contact with the lithium sheet, and the other end passes through the through hole of the top cover, is exposed on the surface of the top cover, and is insulated from the top cover. A sealing ring is disposed on the inner edge of the through hole of the top cover and abuts against the conductive component that passes through the through hole; The housing is fastened to the top cover to form a sealed cavity.

2. The three-electrode button cell as described in claim 1, characterized in that, The thickness of the lithium sheet is less than 50 μm.

3. The three-electrode button cell as described in claim 1, characterized in that, The diameter of the lithium sheet is smaller than the diameter of the second separator, and the diameter of the second separator is smaller than the diameter of the positive electrode sheet.

4. The three-electrode button cell as described in claim 1, characterized in that, The conductive component includes an enameled wire with the enamel removed at both ends of the axial direction, exposing the bare metal wire. One end of the metal wire is in ohmic contact with the lithium sheet, and the other end of the metal wire passes through a through hole and is exposed on the surface of the top cover. The middle part of the enameled wire has intact enamel, penetrates through the through hole, is insulated from the top cover, and abuts against the sealing ring at the inner edge of the through hole.

5. The three-electrode button cell as described in claim 1, characterized in that, The conductive component includes a T-shaped terminal, which includes an end face and a column body fixedly connected to the end face. An insulating gasket is provided between the end face and the top cover. The end of the column body away from the end face passes through the insulating gasket and the through hole of the top cover in sequence, is exposed on the surface of the top cover, and abuts against the sealing ring at the inner edge of the through hole.

6. The three-electrode button cell as described in claim 5, characterized in that, The end face of the T-type terminal completely covers the lithium sheet, and the second diaphragm completely covers the end face of the T-type terminal.

7. The three-electrode button cell as described in claim 5, characterized in that, The thickness of the insulating pad is less than 0.5 mm.

8. The three-electrode button cell as described in claim 5, characterized in that, The end face of the T-type terminal block can be square, rectangular, triangular, or circular.

9. The three-electrode button cell as described in claim 1, characterized in that, A support is also provided between the positive electrode and the shell.

10. The three-electrode button cell as described in claim 9, characterized in that, The support component includes steel sheets and disc spring sheets.

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