Three-electrode button cell

Abstract

The utility model belongs to the technical field of lithium ion batteries, and particularly relates to a three-electrode button cell which comprises a positive shell, a positive pole piece, a second diaphragm, a reference electrode, a first diaphragm, a negative pole piece, a gasket, an elastic piece and a negative shell which are sequentially arranged in the positive shell, and all the parts are arranged in the middle of the positive shell. The reference electrode comprises a pole plate, a metal net and an overhanging pole lug, the pole plate surrounds the periphery of the metal net and is connected with the metal net, the first diaphragm and the second diaphragm respectively cover the upper side and the lower side of the metal net, and the overhanging pole lug is integrally connected with one side of the pole plate and extends out from the position between the positive pole shell and the negative pole shell.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium ion batteries, and specifically relates to a three-electrode button battery. Background Art

[0002] With the rapid development of the lithium-ion battery industry, lithium batteries have been widely used in various industries. In order to meet the special needs of different industries for lithium batteries, researchers have continuously debugged and optimized battery formulas, such as the ratio of positive and negative electrode materials, electrolyte formulas, etc. In order to deeply study the impact of various parameters on battery performance, it is necessary to introduce reference electrodes to obtain the changes in positive and negative electrode potentials and study their evolution laws. At the same time, button batteries are simple to make, low-cost, and easy to test. Therefore, combining the two will maximize R&D efficiency, shorten R&D cycles, and reduce R&D costs.

[0003] Three-electrode button cells have been used in the development of lithium battery systems. However, due to the small size of the button cell itself, setting up a reference electrode in a narrow space requires high operating skills of the experimenter. The presence of the reference electrode will interfere with the original battery structure, affect the air tightness and structural stability of the button cell, and thus affect the cycle performance. At the same time, the unstable reference electrode structure and uneven operating techniques will greatly increase the test error, seriously affect the accuracy of the results, reduce the success rate of the experiment, and increase time, material and labor costs. To this end, a Chinese patent discloses a three-electrode button battery device for precise measurement and its application, application number: CN202110303242.8, the device includes a negative electrode assembly and a positive electrode assembly, the negative electrode assembly has a negative electrode cover and a negative electrode sheet located on the side of the negative electrode cover facing the positive electrode assembly, the positive electrode assembly has a positive electrode shell and a positive electrode sheet located on the side of the positive electrode shell facing the negative electrode assembly, and also includes a reference electrode assembly, the reference electrode assembly is arranged between the negative electrode sheet and the positive electrode sheet, and has a plurality of reference electrodes distributed in a rotationally symmetrical manner with the center of the overlapping part of the negative electrode sheet and the positive electrode sheet as the center of the circle. In this patent, double wires are used as the reference electrode structure, and at the same time, they are led out of the shell in a filament shape. Although the filamentary reference electrode is small in size, the overall structure lacks stability. During the arrangement process, it is not easy to control the insertion area of ​​the reference electrode, and it requires high operating skills and low efficiency. At the same time, the sealing of the filamentary lead-out area is difficult to ensure, which is easy to cause subsequent leakage and gas leakage, affecting the battery performance. Utility Model Content

[0004] The purpose of the utility model is to provide a three-electrode button battery to solve the problems existing in the prior art.

[0005] To achieve the above object, the present utility model provides the following technical solution: A three-electrode button cell, comprising a positive electrode case, in which a positive electrode plate, a second separator, a reference electrode, a first separator, a negative electrode plate, a gasket, a spring piece and a negative electrode case are sequentially placed, and each component is arranged in the middle of the positive electrode case. The reference electrode includes a plate electrode, a metal mesh and an extended ear. The plate electrode surrounds the circumferential of the metal mesh and is connected thereto. The first separator and the second separator respectively cover the upper and lower sides of the metal mesh. The extended ear is integrally connected to one side of the plate electrode and extends out between the positive electrode case and the negative electrode case. This reference electrode is small in volume, thin, light and stable in structure, easy to operate, and can ensure the accuracy and repeatability of experimental data.

[0006] Preferably, the metal mesh is a single wire, parallel multi-wires, cross multi-wires or a mesh.

[0007] Preferably, insulating layers are coated on both sides of the extended ear.

[0008] Preferably, first and second sealing rubber rings matching the shape of the plate electrode are provided on both sides of the plate electrode. The first sealing rubber ring is stuck on the outside of the negative electrode case, and the second sealing rubber ring is stuck on the inside of the positive electrode case. The plate electrode adopts a double-sided sealing rubber ring design, eliminating local gaps, ensuring good sealing performance, and further guaranteeing the battery cycle performance.

[0009] Preferably, the plate electrode is a full plate electrode, which is closely attached between the first and second sealing rubber rings. The full plate electrode is in close contact with the first and second sealing rings without gaps. Using the full plate electrode can increase the overall stiffness of the three electrodes, ensure its structural stiffness while keeping the overall volume small, thin and light, facilitate assembly, easy to operate, and improve the production success rate of the three-electrode battery.

[0010] Preferably, the plate electrode and the metal mesh are of an integral structure.

[0011] Preferably, the extended ear is 3-8 mm.

[0012] Preferably, the material of the reference electrode is one of gold, platinum and copper; one of gold, platinum and lithium is plated on the surface of the metal mesh.

[0013] Preferably, the first separator, the second separator and the gasket have the same area.

[0014] Preferably, the extended ear is wrapped with insulating tape.

[0015] The beneficial effects of the present utility model are: 1) The device makes the reference electrode by foil stamping, greatly reducing the volume of the reference electrode, without modifying the structural parts of the button cell, reducing the operation difficulty, simplifying the production process, and improving the production efficiency of the three-electrode button cell;

[0016] 2) The reference electrode is small in volume, but its structure is thin, light, and stable, easy to operate, reducing manufacturing errors and ensuring the accuracy and repeatability of experimental data;

[0017] 3) The reference electrode adopts a full-plate and double-sided sealing rubber ring design, eliminating local gaps, ensuring good sealing performance, and thus guaranteeing the battery cycle performance. Description of the Drawings

[0018] Figure 1 is a perspective view of this embodiment;

[0019] Figure 2 is an exploded view of this embodiment;

[0020] Figure 3 is a cross-sectional view of this embodiment;

[0021] Figure 4 is a perspective sectional view of this embodiment;

[0022] Figure 5 is a perspective view of the reference electrode in this embodiment;

[0023] Description of the Reference Numerals: 1, negative electrode case; 2, positive electrode case; 3, shrapnel; 4, gasket; 5, reference electrode, 501, plate; 502, lithium-plated copper mesh; 503, tab; 504, insulating layer; 6, first sealing rubber ring; 7, second sealing rubber ring; 8, negative electrode plate; 9, positive electrode plate; 10, first separator; 11, second separator. Detailed Embodiment

[0024] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0025] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0026] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", "connection", "fixed connection", and "fixed joint" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0027] The following specifically describes the embodiments of the present utility model in detail with reference to the accompanying drawings and preferred embodiments.

[0028] As Figure 1 shown, a three-electrode button battery includes a positive electrode case 2. Inside the positive electrode case, a positive electrode plate 9, a second separator 11, a reference electrode 5, a first separator 10, a negative electrode plate 8, a gasket 4, a spring piece 3, and a negative electrode case 1 are sequentially placed. Each component is arranged in the middle inside the positive electrode case. Specifically, the reference electrode includes a plate electrode 501, a metal mesh 502, and an extended ear 503. The material of the reference electrode is one of gold, platinum, and copper. In this embodiment, copper is used. Specifically, a copper foil is stamped into a "disk" shape, and a fixed shape such as a single line, parallel multiple lines, cross multiple lines, a mesh, etc. is cut out at the bottom of the "disk" according to requirements. The cut edges are processed to be smooth and clean. Lithium (or gold or platinum) is plated on the cut area at the bottom of the disk through an electroplating process to obtain a lithium-plated copper mesh. An insulating layer is coated at the extended ear, and a 5-mm extended ear 503 is reserved for subsequent testing to form the entire reference electrode. Among them, the first separator, the second separator, and the gasket have the same area, and the first separator and the second separator respectively cover the upper and lower sides of the metal mesh.

[0029] Furthermore, first sealing rubber rings 6 and second sealing rubber rings 7 that match the shape of the plate electrode are provided on both sides of the plate electrode. The first sealing rubber ring is stuck on the outside of the negative electrode case, and the second sealing rubber ring is stuck on the inside of the positive electrode case. This reference electrode adopts a full-plate and double-sided sealing rubber ring design, eliminating local gaps, ensuring good sealing performance, and thus guaranteeing the battery cycle performance.

[0030] As the best embodiment, the manufacturing method of this battery is as follows: First, an 8-μm copper foil is stamped into a "disk" shape, and holes are cut out at the bottom of the "disk" through a mold to form a copper mesh, and the cut edges are processed to be smooth and clean. The copper mesh area is placed in an electrolyte, and lithium is plated on the surface of the copper mesh through an electroplating process to obtain a lithium-plated copper mesh. An insulating layer 504 is coated on the extended ear 503, and a 5-mm exposed ear is reserved, and the exposed area of the extended ear 503 is wrapped with insulating tape for later use.

[0031] A three-electrode button cell is fabricated in an argon environment. First, the second sealing rubber ring 7 is snapped into the positive electrode case 2. The positive electrode plate 9 is placed in the center of the positive electrode case, and about 15 μL of electrolyte is dropped in to soak the positive electrode plate 9 and adhere to the positive electrode case 2. The second separator 11 is placed into the positive electrode case 2 with tweezers to completely cover the positive electrode plate 9, and about 15 μL of electrolyte is dropped in to soak the second separator 11. The reference electrode 5 is placed directly above the second separator 11 and gently inserted so that the lithium-plated copper mesh contacts the second separator 11. Then, the first separator 10 is placed with tweezers to completely cover the lithium-plated copper mesh, and about 15 μL of electrolyte is dropped in to soak the first separator 10. The negative electrode plate 8 is placed in the center above the first separator 10, and sufficient electrolyte is dropped in to soak the negative electrode plate 8. The spacer 4 is picked up with tweezers and placed on top of the negative electrode plate 8, and then the shrapnel 3 is picked up and placed above the spacer 4. The first sealing rubber ring 6 is fixed to the outer edge of the negative electrode case 1, and finally the negative electrode case 1 is picked up and placed on top of the shrapnel 3 and gently pressed in. During the pressing process, pay attention to observing the electrode plate 501 of the reference electrode 5 to prevent abnormal phenomena such as bending and wrinkling. The assembled button cell is picked up with tweezers and transferred to a button cell sealer (with the negative electrode facing up), a pressure of 3 MPa is applied, and after 5 s, the pressure is released. The button cell is taken out and the surface of the cell is cleaned to obtain the three-electrode button cell.

[0032] It should be noted that this device can be used to transport semi-finished lithium batteries, provide vacuum or inert gas according to requirements, and select different accessories for combination to make full use of space and improve work efficiency. For ordinary technical personnel in this technical field, without departing from the principle of the present invention, several improvements and refinements can also be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A three-electrode button cell, comprising a positive electrode shell, in which a positive electrode sheet, a second diaphragm, a reference electrode, a first diaphragm, a negative electrode sheet, a gasket, a spring and a negative electrode shell are sequentially placed, and each component is centrally arranged in the positive electrode shell, characterized in that: The reference electrode includes a pole plate, a metal mesh and an extended pole ear, the pole plate surrounds the circumference of the metal mesh and is connected thereto, the first diaphragm and the second diaphragm respectively cover the upper and lower sides of the metal mesh, and the extended pole ear is integrally connected to one side of the pole plate and extends from between the positive electrode shell and the negative electrode shell.

2. The three-electrode button cell according to claim 1, characterized in that: The metal mesh is in the form of a single wire, multiple parallel wires, multiple crossed wires or a mesh.

3. The three-electrode button cell according to claim 1, characterized in that: Both sides of the protruding pole ear are coated with an insulating layer.

4. The three-electrode button cell according to claim 1, characterized in that: A first sealing rubber ring and a second sealing rubber ring matching the shape of the electrode plate are disposed on both sides of the electrode plate, wherein the first sealing rubber ring is clamped on the outer side of the negative electrode shell, and the second sealing rubber ring is clamped on the inner side of the positive electrode shell.

5. The three-electrode button cell according to claim 4, characterized in that: The electrode plate is a full electrode plate, which is tightly fitted between the first sealing rubber ring and the second sealing rubber ring.

6. The three-electrode button cell according to claim 1, characterized in that: The electrode plate and the metal mesh are an integrated structure.

7. The three-electrode button cell according to claim 1, characterized in that: The extended pole ear is 3-8 mm.

8. The three-electrode button cell according to claim 1, characterized in that: The reference electrode is made of one of gold, platinum and copper; the surface of the metal mesh is plated with one of gold, platinum and lithium.

9. The three-electrode button cell according to claim 1, characterized in that: The first diaphragm, the second diaphragm and the spacer have the same area.

10. The three-electrode button cell according to claim 1, characterized in that: The outer side of the protruding pole ear is wrapped with insulating tape.

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