Three-electrode lithium battery

Abstract

The utility model discloses a three-electrode lithium battery, which belongs to the technical field of lithium batteries and comprises a shell, a naked battery cell and a reference electrode, the shell comprises an inner cavity, and the naked battery cell and the reference electrode are both sealed in the inner cavity of the shell; the reference electrode is arranged in the middle layer of the bare cell, the reference electrode comprises a lithium-copper composite belt, and the lithium-copper composite belt is wrapped with a diaphragm on the outer side surface in the bare cell; insulating parts are arranged at the positions, corresponding to the lithium-copper composite belts, in the naked battery cell, and the lithium-copper composite belts are isolated from the naked battery cell through the insulating parts. The lithium-copper composite belt rich in more lithium is adopted as the reference electrode, the service time of the reference electrode is prolonged, the insulating part isolates the reference electrode from directly contacting with the naked battery cell to react, the influence of back-and-forth migration of positive and negative lithium ions of the naked battery cell on the monitoring potential of the reference electrode is avoided, and the loss of metal lithium on the reference electrode is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to lithium battery technical field, concretely relates to a three electrode lithium battery. BACKGROUND

[0002] In order to explore the electrochemical performance of the battery, the reference electrode is introduced to monitor the change of lithium potential of positive and negative electrodes in the charging and discharging process of lithium ion battery. The three-electrode lithium battery is formed by introducing the reference electrode. The three electrodes can analyze the cycle, high and low temperature charging and discharging, fast charging and battery failure, and systematically analyze the reaction mechanism.

[0003] At present, the common reference electrode is lithium-plated copper wire structure, such as the Chinese patent document with the announcement number CN218513507U discloses a battery cell and a lithium battery comprising the battery cell, wherein the battery cell comprises: a shell and a top cover, the top cover is connected to the shell, the top cover is provided with a positive pole and a negative pole; at least three reference electrode poles are arranged on the shell or the top cover; at least one reference electrode is arranged in the shell, and the reference electrode is electrically connected to the reference electrode pole. The reference electrode in the lithium battery is plated with lithium on the copper wire through the positive and negative electrode sheets. However, the copper wire needs to be plated with lithium after being introduced into the battery cell, which greatly increases the production time. In addition, the copper wire is thin, and the surface lithium plating amount is limited. Lithium loss will occur during the charging and discharging process, resulting in unpredictable deviation of test data, which is not suitable for long-term continuous work. CONTENT OF THE UTILITY MODEL

[0004] The utility model aims at providing a three electrode lithium battery, solves the problem that the reference electrode in the prior art is plated with lithium on the copper wire through the positive and negative electrode sheets, the copper wire is thin, and the surface lithium plating amount is limited. Lithium loss will occur during the charging and discharging process, resulting in unpredictable deviation of test data.

[0005] In order to achieve the above-mentioned purpose, the utility model provides a three electrode lithium battery, which comprises a shell, a bare battery cell and a reference electrode, the shell comprises an inner cavity, the bare battery cell and the reference electrode are all sealed in the inner cavity of the shell; the reference electrode is arranged in the middle layer of the bare battery cell, the reference electrode comprises a lithium-copper composite tape, the outer side of the lithium-copper composite tape in the bare battery cell is wrapped with a diaphragm; the position corresponding to the lithium-copper composite tape in the bare battery cell is provided with an insulating piece, and the insulating piece insulates the lithium-copper composite tape from the bare battery cell.

[0006] Further, the lithium-copper composite tape is arranged at the middle position of the length direction of the bare battery cell, which can reduce the measurement error of the reference electrode at the position and reduce the influence on the test result.

[0007] Further, the length of the insulating piece is half of the width of the bare battery cell, the width of the insulating piece is 1mm-5mm; the length and width of the lithium-copper composite tape are smaller than the length and width of the insulating piece.

[0008] The length and width of the lithium-copper composite tape are less than the length and width of the insulating piece, so that the high-temperature adhesive tape can completely cover the lithium-copper composite tape, and the insulation effect is ensured. The length of the insulating piece is half of the width of the bare battery cell, and the insulating piece avoids covering the width of the bare battery cell to reduce the migration efficiency of lithium ions in the bare battery cell.

[0009] Further, the bare battery cell includes a positive plate and a negative plate, and the lithium-copper composite tape is clamped between the positive plate and the negative plate; one end of the lithium-copper composite tape located outside the positive plate and the negative plate is connected with a reference tab, the reference tab extends out of the shell, and the reference tab is in insulating and sealed connection with the shell.

[0010] The reference tab is connected with the foil of the lithium-copper composite tape in the form of welding, which facilitates monitoring of potential changes.

[0011] Further, the positive plate is connected with a positive tab, and the negative plate is connected with a negative tab; the positive tab and the negative tab both extend to the outside of the shell, and the positive tab and the negative tab are both in insulating and sealed connection with the shell.

[0012] The positive tab and the negative tab can lead out the current inside the battery, and the sealed connection of the positive tab and the negative tab with the shell can ensure good sealing of the battery and prevent liquid leakage.

[0013] Further, the positive tab and the negative tab are located on the same side of the shell.

[0014] Through the above technical solutions, the packaging design of the battery can be simplified, the use of packaging materials can be reduced, and thus the overall weight and volume of the battery can be reduced. The side-by-side layout of the positive tab and the negative tab can shorten the current path and reduce the internal resistance of the battery, thereby improving the charge and discharge efficiency of the battery.

[0015] Further, the positive tab, the negative tab, and the reference tab are located on different sides of the shell, and the potential changes of the positive tab and the negative tab during the charging and discharging process can be independently monitored, which helps to more accurately analyze the electrochemical reaction process inside the battery.

[0016] Further, the lithium-copper composite tape includes a copper matrix, and lithium layers are arranged on both sides of the copper matrix, and the thickness of the lithium layer is 20-40 microns.

[0017] The double-sided lithium layer structure and the thickness of the lithium layer can prolong the service life of the lithium-copper composite tape and improve the detection accuracy of the reference electrode.

[0018] Further, the shell is filled with electrolyte, and the bare electrode and the reference electrode are immersed in the electrolyte.

[0019] Compared with the prior art, the technical scheme has the following beneficial effects:

[0020] The three-electrode lithium battery has the lithium copper composite belt rich in lithium as the reference electrode, so that the reference electrode can accurately monitor the potential for a long time, the use time of the reference electrode is increased, the detection accuracy of the reference electrode is improved, and the safety of the battery cell is ensured.

[0021] Obviously, the elements or features described in the above single embodiment can be used alone or in combination in other embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0022] In the drawings, the size and proportion do not represent the actual product size and proportion. The drawings are merely illustrative, and some unnecessary elements or features are omitted for clarity.

[0023] Figure 1 is a structural schematic diagram of a lithium battery in the embodiments of the present application.

[0024] REFERENCE NUMERALS

[0025] 1, reference tab; 2, shell; 3, positive plate; 4, negative plate; 5, negative tab; 6, positive tab; 7, lithium copper composite belt; 8, insulating piece. DETAILED DESCRIPTION

[0026] The present application will be described in detail below with reference to the drawings.

[0027] REFERENCE Figure 1The embodiment provides a three-electrode lithium battery, which comprises a shell 2, a bare battery cell and a reference electrode, the shell 2 comprises an inner cavity, and the bare battery cell and the reference electrode are both sealed in the inner cavity of the shell 2. An electrolyte is injected into the shell 2, and the bare battery cell and the reference electrode are immersed in the electrolyte. The bare battery cell is further connected with a positive electrode and a negative electrode, and the positive electrode, the negative electrode and the reference electrode constitute a three-electrode lithium ion battery. The reference electrode is arranged in the middle layer of the bare battery cell, and the reference electrode comprises a lithium-copper composite tape 7, and the outer side of the lithium-copper composite tape 7 in the bare battery cell is wrapped with a diaphragm. The lithium-copper composite tape 7 rich in lithium is used as the reference electrode, so that the reference electrode can accurately monitor the potential for a long time, the use time of the reference electrode is increased, the detection accuracy of the reference electrode is improved, and the safety of the battery cell is ensured. Compared with the prior art, the lithium-copper composite tape 7 omits the process of plating lithium on the copper wire of the positive electrode and the negative electrode, and greatly reduces the assembly time of the three electrodes. The position corresponding to the lithium-copper composite tape 7 in the bare battery cell is provided with an insulating piece 8, and the insulating piece 8 insulates the lithium-copper composite tape 7 from the bare battery cell. The insulating piece 8 insulates the reference electrode from directly contacting and reacting with the bare battery cell, avoids the influence of the back and forth migration of lithium ions of the positive electrode and the negative electrode of the bare battery cell on the monitoring potential of the reference electrode, and reduces the loss of metallic lithium on the reference electrode.

[0028] It should be noted that the insulating piece 8 is a high-temperature adhesive tape. On the one hand, the high-temperature adhesive tape plays an insulating role, and on the other hand, the high-temperature adhesive tape can withstand a high-temperature environment and prevent the insulating piece 8 from being damaged due to high temperature. The high-temperature adhesive tape is also convenient to install and can be attached to the inside of the bare battery cell. Moreover, the thickness of the high-temperature adhesive tape is relatively small, and the high-temperature adhesive tape does not occupy additional space in the bare battery cell. The shell 2 is an aluminum plastic film structure, and the bare battery cell and the reference electrode are packaged in the shell 2 formed by the aluminum plastic film.

[0029] Further, the length and width of the lithium-copper composite tape 7 are smaller than the length and width of the insulating piece 8, that is, the high-temperature adhesive tape, so that the high-temperature adhesive tape can completely cover the lithium-copper composite tape 7 and ensure the insulation effect. The length of the high-temperature adhesive tape is half the width of the bare battery cell, and the high-temperature adhesive tape avoids covering the width range of the bare battery cell to reduce the migration efficiency of lithium ions in the bare battery cell. The width of the high-temperature adhesive tape is 1 mm-5 mm, which reduces the shading of the inside of the bare battery cell. The specific width can be 1 mm, 2 mm, 3 mm, 4 mm or 5 mm, and preferably 1 mm-2 mm. The lithium-copper composite tape 7 is arranged at the middle position in the length direction of the bare battery cell, which can reduce the measurement error of the reference electrode at the position and reduce the influence on the test result.

[0030] It can be understood that, as Figure 1As shown, the bare battery cell includes a positive electrode sheet 3 and a negative electrode sheet 4, and a lithium-copper composite strip 7 is clamped between the positive electrode sheet 3 and the negative electrode sheet 4. One end of the lithium-copper composite strip 7 outside the positive electrode sheet 3 and the negative electrode sheet 4 is connected with a reference tab 1, the reference tab 1 extends out of the shell 2, and the reference tab 1 is in insulating and sealing connection with the shell 2. The reference tab 1 is a copper tab, which is connected with the foil of the lithium-copper composite strip 7 by welding, facilitating the monitoring of the potential. The lithium-copper composite strip 7 includes a copper matrix, and the copper matrix has lithium layers arranged on both sides. The lithium layers are pressed on the surfaces of both sides of the copper matrix. The thickness of the lithium layer is 20-40 μm, which can be 20 μm, 30 μm or 40 μm, and 30 μm is preferred in the embodiment. When the thickness of the lithium layer is 30 μm, the service life of the lithium-copper composite strip 7 can be prolonged, and the detection accuracy of the reference electrode can be improved.

[0031] The current of the bare battery cell is usually transmitted from the inside of the battery to the outside of the battery by the tab component, such as Figure 1 As shown, the positive electrode sheet 3 is welded with a positive tab 6, and the positive tab 6 leads out of the shell 2 formed by the aluminum plastic film. The negative electrode sheet 4 is welded with a negative tab 5, and the negative tab 5 leads out of the shell 2 formed by the aluminum plastic film. It should be noted that the positive tab 6 is an aluminum tab, and the negative tab 5 is a copper tab. In order to ensure the sealing of the battery, the positive tab 6 and the negative tab 5 are in insulating and sealing connection with the shell 2. Specifically, a heat-sealing glue layer is arranged on the inner side of the aluminum plastic film at the positions corresponding to the positive tab 6 and the negative tab 5, and the positive tab 6 and the negative tab 5 are sealed with the aluminum plastic film by heat sealing. Similarly, the reference tab 1 is also sealed with the aluminum plastic film by heat sealing.

[0032] In some embodiments, the positive tab 6 and the negative tab 5 are located on the same side of the shell 2, which can simplify the packaging design of the battery, reduce the use of packaging materials, and thus reduce the overall weight and volume of the battery. The side-by-side layout of the positive tab 6 and the negative tab 5 can shorten the current path and reduce the internal resistance of the battery, thereby improving the charge and discharge efficiency of the battery. In addition, when the positive tab 6 and the negative tab 5 are on the same side, the heat can be more concentratedly dissipated, which is convenient for designing a heat dissipation system outside the battery, thereby improving the heat dissipation performance of the battery.

[0033] Further, the positive tab 6, the negative tab 5 and the reference tab 1 are located on different sides of the shell 2. By arranging the reference tab 1 on different sides of the positive tab 6 and the negative tab 5, the potential changes of the positive tab 6 and the negative tab 5 during the charging and discharging process can be independently monitored, which helps to more accurately analyze the electrochemical reaction process inside the battery. Moreover, under the condition of high-rate charging or low temperature, lithium ion precipitation may occur in the negative electrode, and the positive electrode may also be polarized due to too fast lithium extraction. By arranging the reference electrode respectively, the polarization degree of the positive and negative electrodes can be accurately detected, thereby providing data support for optimizing the performance of the battery.

[0034] The method for manufacturing a three-electrode lithium battery includes the following steps:

[0035] Step one: first, the positive plate 3 and the negative plate 4 of the bare battery core are welded with the external positive lug 6 and the negative lug 5 respectively by ultrasonic welding.

[0036] Step two: a reference electrode is prepared, the lithium-copper composite strip 7 has a width of 1-2mm and a length of half of the positive plate 3, the lithium-copper composite strip 7 foil side is welded with the reference lug 1, the lithium-copper composite strip 7 after welding is wrapped with a separator and fixed with a thin high-temperature tape, the wrapped lithium-copper composite strip 7 is placed in the middle position of the corresponding plate in the middle layer, after the position is determined, the positions of the positive plate 3 and the negative plate 4 corresponding to the lithium-copper composite strip 7 are covered with high-temperature tape, and the size of the high-temperature tape is slightly larger than that of the lithium-copper composite strip 7.

[0037] Step three: after the prepared lithium-copper composite strip 7 is placed in the position of the built-in high-temperature tape, the battery core containing the reference electrode is packaged with an aluminum plastic film, and after packaging, the battery core is injected and sealed, and after 12h of immersion, it is determined whether the positive electrode potential and the negative electrode potential to the reference electrode are normal.

[0038] Step four: after the three-electrode lithium battery is completed, the battery core is formed, degassed, and tested, and in the testing process, a multichannel recorder is used to monitor the potential of the negative electrode to the reference electrode, the positive and negative electrode potentials of the battery core are monitored during the testing process, and the positive electrode potential to the reference electrode is calculated, in addition, the multichannel recorder and the charging and discharging equipment need to be consistent in time collection.

[0039] In the description of the utility model, it needs to be explained that the terms "front", "back", "left", "right", "up", "down", "top", "bottom", "inside", "outside" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and cannot be understood as limiting or implying that the indicated device or element must have a specific orientation, structure and operation, therefore, it cannot be understood as a limitation on the utility model. In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0040] In the description of the utility model, it needs to be explained that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected, it can be mechanical connection, or electrical connection, it can be directly connected, or indirectly connected through an intermediate medium, or the communication between two elements. For ordinary skilled persons in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0041] The protection scope of the utility model is only limited by the claims. Thanks to the teaching of the utility model, the person skilled in the art can easily recognize that the alternative structure of the disclosed structure of the utility model can be used as a feasible alternative implementation mode, and the disclosed implementation mode of the utility model can be combined to generate a new implementation mode, which also falls within the scope of the appended claims.

Claims

1. A three-electrode lithium battery comprising a housing (2) comprising an internal cavity, a bare cell and a reference electrode, both the bare cell and the reference electrode being sealed in the internal cavity of the housing (2); the reference electrode being disposed in an intermediate layer of the bare cell, characterized in that, The reference electrode comprises a lithium-copper composite belt (7) wrapped with a diaphragm on the outer side of a bare battery cell; the bare battery cell is provided with an insulating piece (8) at the position corresponding to the lithium-copper composite belt (7) inside the bare battery cell, which insulates the lithium-copper composite belt (7) from the bare battery cell.

2. The three-electrode lithium battery of claim 1, wherein, The lithium-copper composite belt (7) is arranged at the middle position in the length direction of the bare battery cell.

3. The three-electrode lithium battery of claim 1, wherein, The length of the insulating piece (8) is half of the width of the bare battery cell, and the width of the insulating piece (8) is 1-5 mm; the length and width of the lithium-copper composite belt (7) are smaller than those of the insulating piece (8).

4. The three-electrode lithium battery of claim 1, wherein, The bare battery cell comprises a positive electrode sheet (3) and a negative electrode sheet (4), and the lithium-copper composite belt (7) is clamped between the positive electrode sheet (3) and the negative electrode sheet (4); one end of the lithium-copper composite belt (7) outside the positive electrode sheet (3) and the negative electrode sheet (4) is connected with a reference tab (1), the reference tab (1) extends out of a shell (2), and the reference tab (1) is in insulating and sealed connection with the shell (2).

5. The three-electrode lithium battery of claim 4, wherein, The positive electrode sheet (3) is connected with a positive tab (6), and the negative electrode sheet (4) is connected with a negative tab (5); the positive tab (6) and the negative tab (5) both extend out of the shell (2), and the positive tab (6) and the negative tab (5) are both in insulating and sealed connection with the shell (2).

6. The three-electrode lithium battery of claim 5, wherein, The positive tab (6) and the negative tab (5) are located on the same side of the shell (2).

7. The three-electrode lithium battery of claim 6, wherein, The positive tab (6) and the negative tab (5) are located on the opposite side of the reference tab (1) with respect to the shell (2).

8. The three-electrode lithium battery of claim 1, wherein, The lithium-copper composite belt (7) comprises a copper matrix, and the two surfaces of the copper matrix are provided with lithium layers.

9. The three-electrode lithium battery of claim 8, wherein, The thickness of the lithium layer is 20-40 µm.

10. The three-electrode lithium battery of claim 1, wherein, The shell (2) is filled with an electrolyte, and the bare battery cell and the reference electrode are immersed in the electrolyte.

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