Three-electrode cell and battery

Abstract

The three-electrode battery cell comprises a basic battery cell, the basic battery cell comprises a plurality of positive plates, negative plates and first diaphragms, the positive plates, the negative plates and the first diaphragms are stacked, the positive plates and the negative plates are sequentially and alternately arranged, the first diaphragms are arranged between the adjacent positive plates and the adjacent negative plates, and the first diaphragms are arranged between the positive plates and the negative plates. The first diaphragms are arranged on the two outermost sides of the basic battery cell; the reference electrode is positioned on one side of the basic battery cell; the independent positive plate is positioned on one side, deviating from the basic battery cell, of the reference electrode; one second diaphragm is arranged between the reference electrode and the independent positive plate, and one second diaphragm is arranged on one side, deviating from the reference electrode, of the independent positive plate. Therefore, the reference electrode and the independent positive plate are arranged outside the basic battery cell, so that the three-electrode battery cell does not increase the number of layers of diaphragms in the basic battery cell, and the transmission of lithium ions between the positive plate and the negative plate is not influenced.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field especially relates to a three electrode electric core and battery. BACKGROUND

[0002] The electrochemical performance test and evaluation of battery system is the key step of improving the performance of lithium battery and carrying out technical transformation. In order to accurately monitor the positive and negative electrode potential, a three electrode system is usually used to provide more accurate charge and discharge curves, positive and negative electrode potential and electrochemical impedance spectrum test results.

[0003] In the related art, the reference electrode of the three electrode battery is usually arranged in the bare electric core, that is, the reference electrode is located between the positive plate and the negative plate of the bare electric core. Since the reference electrode needs to be wrapped with a separator to form a sandwich structure of "separator-reference electrode-separator", the number of separator layers in the bare electric core will also increase by two when the reference electrode is inserted into the bare electric core, thereby increasing the resistance of lithium ion transmission between the positive plate and the negative plate during charging and discharging of the battery, affecting the electrochemical performance analysis of the battery. SUMMARY

[0004] The utility model discloses in view of above-mentioned present situation, a kind of three electrode electric core and battery are provided to improve the problem of big transmission resistance of lithium ion between positive plate and negative plate.

[0005] In the first aspect, the utility model provides a kind of three electrode electric core, it includes: basic electric core, the basic electric core includes multiple layering positive plate, negative plate and first separator, the positive plate and the negative plate are sequentially arranged alternately, and first separator is arranged between adjacent positive plate and negative plate, the outermost two sides of the basic electric core are the first separator;Reference electrode, located in the one side of the basic electric core;Independent positive plate, located in the one side of reference electrode away from the basic electric core;Multiple second separators, one of the second separators is arranged between the reference electrode and the independent positive plate, one of the second separators is arranged on the side of the independent positive plate away from the reference electrode.

[0006] Optionally, the three electrode electric core further includes positive tab connected with the positive plate, negative tab connected with the negative plate, reference tab connected with the reference electrode, and independent positive tab connected with the independent positive plate;The positive tab and the negative tab are located on the same side of the three electrode electric core;The reference tab and the independent positive tab are located on the same side of the three electrode electric core, and are on the opposite side of the positive tab.

[0007] Optionally, the three electrode electric core further includes positionally opposite top side and bottom side;The positive tab and the negative tab are located on the top side;The reference tab and the independent positive tab are located on the bottom side.

[0008] Optionally, the reference electrode comprises a lithium-plated section and a lithium-free section connected with each other, the lithium-plated section is located between the first diaphragm and the second diaphragm, the lithium-free section extends out of the first diaphragm and the second diaphragm, and the lithium-free section is connected with the reference tab.

[0009] Optionally, the lithium-plated section is provided with a lithium-plated layer on a side facing the independent positive electrode sheet.

[0010] Optionally, the lithium-plated section is at least partially in a zigzag structure.

[0011] Optionally, the lithium-plated section is at least partially in a wave structure, or the lithium-plated section is at least partially in a rake structure, or the lithium-plated section is at least partially in a coiled structure.

[0012] Optionally, the base battery cell comprises opposite first and second sides, and the first and second sides are both provided with the first diaphragm; on the first side, the negative electrode sheet is adjacent to the outermost first diaphragm; on the second side, the negative electrode sheet is adjacent to the outermost first diaphragm.

[0013] Optionally, the material of the reference electrode is copper.

[0014] Optionally, the reference electrode comprises a copper wire, and the diameter of the copper wire is 20-60 microns, or the diameter of the copper wire is 45-55 microns.

[0015] In a second aspect, the utility model provides a kind of battery, which comprises the three-electrode battery cell described above.

[0016] The three-electrode battery cell described in the utility model comprises a base battery cell, a reference electrode, an independent positive electrode sheet and a second diaphragm. The reference electrode is located on one side of the base battery cell, and the independent positive electrode sheet is located on the side of the reference electrode away from the base battery cell. As the reference electrode and the independent positive electrode sheet are both arranged outside the base battery cell, the three-electrode battery cell described in the utility model does not increase the number of diaphragms in the base battery cell, so as not to affect the transmission of lithium ions between the positive electrode sheet and the negative electrode sheet. In addition, the arrangement of the independent positive electrode sheet also facilitates subsequent connection with an external charge and discharge test cabinet to perform lithium plating operation on the reference electrode. BRIEF DESCRIPTION OF DRAWINGS

[0017] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0018] For a more complete understanding of the present application, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which like numbers designate like parts, where:

[0019] Figure 1 is a schematic diagram showing the overall structure of a three-electrode battery cell related to the present application.

[0020] Figure 2 is a schematic diagram showing Figure 1 the partial structure of the three-electrode battery cell.

[0021] Figure 3 is a schematic diagram showing Figure 1 the lithium-plated segment of the three-electrode battery cell in a wavy structure.

[0022] Figure 4 is a schematic diagram showing Figure 1 the lithium-plated segment of the three-electrode battery cell in a rake structure.

[0023] Figure 5 is a schematic diagram showing Figure 1 the lithium-plated segment of the three-electrode battery cell in a coiled structure.

[0024] Reference signs: 1, base battery cell; 11, positive electrode sheet; 12, negative electrode sheet; 13, first separator; 2, reference electrode; 21, lithium-plated segment; 22, lithium-free segment; 3, independent positive electrode sheet; 4, second separator; 5, positive electrode tab; 6, negative electrode tab; 7, reference electrode tab; 8, independent positive electrode tab. DETAILED DESCRIPTION

[0025] Hereinafter, preferred embodiments of the present application will be described in detail with reference to the accompanying drawings. In the following description, for the purpose of explanation, identical components are assigned with the same reference numerals, and repetitive explanations are omitted. In addition, the drawings are merely schematic diagrams, and the ratio of the size between components or the shape of the components, etc. can be different from the actual ones. It should be noted that all directional references, such as up, down, left, right, front, back, etc., used herein are in connection with the orientation of the apparatuses as shown in the drawings, and are merely used for convenience and clarity in understanding the application.

[0026] It should also be noted that when an element is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element, or intervening elements can also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element, or intervening elements can also be present.

[0027] Referring to Figure 1 and Figure 2This application provides a three-electrode battery cell, which includes a base cell 1, a reference cell, an independent positive electrode 3, and multiple second separators 4. The base cell 1 includes multiple stacked positive electrode 11s, negative electrode 12s, and first separators 13. The positive electrode 11s and negative electrode 12s are alternately arranged in sequence, and a first separator 13 is provided between adjacent positive electrode 11s and negative electrode 12s. The outermost two sides of the base cell 1 are both first separators 13. The reference electrode 2 is located on one side of the base cell 1. The independent positive electrode 3 is located on the side of the reference electrode 2 facing away from the base cell 1. A second separator 4 is provided between the reference electrode and the independent positive electrode 3, and a second separator 4 is provided on the side of the independent positive electrode 3 facing away from the reference electrode.

[0028] Based on the above structure, since both the reference electrode 2 and the independent positive electrode 3 are located outside the base cell 1, the three-electrode cell involved in this application does not increase the number of separator layers in the base cell 1, thus not affecting the transport of lithium ions between the positive electrode 11 and the negative electrode 12. Furthermore, the independent positive electrode 3 facilitates subsequent connection to an external charge / discharge test cabinet for lithium plating of the reference electrode 2. The base cell 1 can also be considered a bare cell in related technologies.

[0029] In some embodiments, the base cell 1 includes a first side and a second side opposite to each other, and both the first side and the second side are provided with a first separator 13; on the first side, a negative electrode 12 is adjacent to the outermost first separator 13; on the second side, a negative electrode 12 is adjacent to the outermost first separator 13. Thus, the electrodes on both outermost sides of the base cell 1 are negative electrode sheets 12. Specifically, the negative electrode material coated on the negative electrode sheet 12 is usually graphite. Graphite is a relatively stable material that does not easily undergo structural changes during charging and discharging, which helps to improve the cycle stability and lifespan of the battery. In addition, graphite reacts relatively mildly in the battery, has good thermal stability, and is not prone to thermal runaway, thereby improving the safety of the battery. Therefore, having both outermost sides of the base cell 1 as negative electrode sheets 12 can improve the battery's lifespan and safety performance.

[0030] It is understandable that, based on the alternating arrangement of positive electrode 11 and negative electrode 12 in related technologies, and also based on the fact that the outermost two electrodes of the basic cell 1 in this application are both negative electrode 12, the three-electrode cell of this application is provided with an independent positive electrode 3, referring to... Figure 2 The three-electrode cell forms a structure of "second separator 4 - independent positive electrode 3 - second separator 4 - reference electrode 2 - first separator 13 - negative electrode 12 - first separator 13 - positive electrode 11... first separator 13 - negative electrode 12 - first separator 13". However, if the base cell 1 is considered as a whole, the structure of this three-electrode cell can also be viewed as "second separator 4 - independent positive electrode 3 - second separator 4 - reference electrode 2 - base cell 1".

[0031] Referring to Figure 1 In some embodiments, the three-electrode battery cell further comprises a positive electrode tab 5 connected with the positive electrode sheet 11, a negative electrode tab 6 connected with the negative electrode sheet 12, a reference electrode tab 7 connected with the reference electrode 2, and an independent positive electrode tab 8 connected with the independent positive electrode sheet 3. The positive electrode tab 5 and the negative electrode tab 6 are located on the same side of the three-electrode battery cell. The reference electrode tab 7 and the independent positive electrode tab 8 are located on the same side of the three-electrode battery cell and are on the opposite side of the positive electrode tab 5. In this way, the reference electrode tab 7 and the independent positive electrode tab 8 are located on the same side of the three-electrode battery cell, which facilitates the connection of the reference electrode tab 7 and the independent positive electrode tab 8 during testing. Specifically, when the reference electrode sheet is plated with lithium, the independent positive electrode tab 8 is connected to the positive terminal of the charge-discharge test cabinet, the reference electrode tab 7 is connected to the negative terminal of the charge-discharge test cabinet, and the positive electrode tab 5 and the negative electrode tab 6 of the base battery cell 1 are not connected during testing. Among them, the reference electrode tab 7 and the independent positive electrode tab 8 are arranged on the opposite side of the positive electrode tab 5, that is, the reference electrode tab 7 and the independent positive electrode tab 8 are also arranged on the opposite side of the negative electrode tab 6. In this way, by separating the positive electrode tab 5 and the negative electrode tab 6 from the independent positive electrode tab 8 and the reference electrode tab 7, the connection of the independent positive electrode tab 8 and the reference electrode tab 7 during the connection operation can be effectively avoided, thereby improving the convenience and accuracy of the connection.

[0032] Referring to Figure 1 In some embodiments, the three-electrode battery cell further comprises a top side and a bottom side opposite to each other. The positive electrode tab 5 and the negative electrode tab 6 are located on the top side. The reference electrode tab 7 and the independent positive electrode tab 8 are located on the bottom side. In this way, the reference electrode tab 7 and the independent positive electrode tab 8 are led out on the bottom side, which makes it easy for the workers to distinguish and facilitates the subsequent connection operation. In addition, the positive electrode tab 5 and the negative electrode tab 6 are located on the top side, and the reference electrode tab 7 and the independent positive electrode tab 8 are located on the bottom side, which can also prevent the reference electrode tab 7 and the independent positive electrode tab 8 from being easily contacted with the positive electrode tab 5 and the negative electrode tab 6 during testing, thereby reducing the risk of short circuit.

[0033] In some embodiments, the reference electrode 2 comprises a lithium-plated section 21 and a lithium-free section 22 connected with each other. The lithium-plated section 21 is located between the first separator 13 and the second separator 4, and the lithium-free section 22 extends out of the first separator 13 and the second separator 4, and the lithium-free section 22 is connected with the reference electrode tab 7. In this way, the lithium-free section 22 extends out of the first separator 13 and the second separator 4, which facilitates the connection with the reference electrode tab 7. In some examples, the lithium-free section 22 is welded with the reference electrode tab 7.

[0034] In some embodiments, the lithium-plated section 21 is provided with a lithium-plated layer on the side facing the independent positive electrode sheet 3. Specifically, the independent positive electrode tab 8 is connected to the positive terminal of the charge-discharge test cabinet, the reference electrode tab 7 is connected to the negative terminal of the charge-discharge test cabinet, and the lithium-plated layer is formed on the lithium-plated section 21 by plating lithium.

[0035] In some embodiments, the material of the reference electrode 2 is copper, and the reference electrode 2 can include a copper wire. Specifically, copper does not have obvious chemical reactions in most electrolyte and environments, which enables the reference electrode 2 using copper material to provide a stable potential reference, and copper has good conductivity and can quickly respond to electrochemical changes, thereby providing accurate potential readings.

[0036] Specifically, the three-electrode battery cell includes the following steps in the preparation process:

[0037] (1) Stack the positive electrode sheet 11, the negative electrode sheet 12, and the first separator 13 to form a stacked basic battery cell 1, and stack two second separators 4 on the outermost side of the basic battery cell 1;

[0038] (2) Soak one end of the copper wire in sulfuric acid to a certain depth, the concentration of the sulfuric acid is 95%-100%, the soaking time is 0.5h-2h, then rinse with industrial alcohol with a concentration of 99%, and then dry in a fume hood;

[0039] (3) Put the end of the copper wire soaked in sulfuric acid in step (2) between the adjacent first separator 13 and the second separator 4, and the end not soaked in sulfuric acid is led out of the separator from the side or bottom edge of the basic battery cell 1, and the independent positive electrode tab 3 is placed between the two adjacent second separators 4 in step (1), forming a structure of “second separator 4-independent positive electrode tab 3-second separator 4-reference electrode 2-first separator 13-basic battery cell 1”, and then packaging, baking, liquid injection, formation, aging, and capacity test;

[0040] (4) After the capacity test in step (3) is completed, the independent positive electrode tab 3 is used to perform single-sided lithium plating on the copper wire, the current for lithium plating of the copper wire is 10μA-25μA, and the single-sided lithium plating time is 2h-6h, thereby forming a reference electrode 2 structure with a lithium plating section 21 and a lithium-free section 22, and finally obtaining a lithium ion three-electrode.

[0041] It should be noted that the single-sided lithium plating method for the copper wire includes connecting the independent positive electrode tab 8 to the positive terminal of the charge and discharge test cabinet, connecting the reference electrode tab 7 to the negative terminal of the charge and discharge test cabinet, and then performing lithium plating. After single-sided lithium plating is completed, the lithium plating layer on the side of the lithium plating section 21 facing the independent positive electrode tab 3 in the above embodiment is obtained. At this time, it should be noted that before the copper wire is subjected to single-sided lithium plating using the independent positive electrode tab 3, the welding work of the lithium-free section 22 and the reference electrode tab 7 needs to be completed first.

[0042] In some examples, the length of the copper wire immersed in the sulfuric acid is between 20%-40% of the total length of the copper wire. In this way, the copper wire immersed in the sulfuric acid is the lithium plating section 21, and the length of the lithium plating section 21, which is 20%-40% of the total length of the copper wire, can ensure that there is a sufficient length of the lithium plating section 21 between the first diaphragm 13 and the second diaphragm 4, so as to avoid the three-electrode battery being taken out during the preparation process.

[0043] Specifically, in some examples, the total length of the copper wire can be 10-15 cm. When the length of the copper wire is 10 cm, the length of the copper wire immersed in the sulfuric acid can be 2-4 cm; when the length of the copper wire is 15 cm, the length of the copper wire immersed in the sulfuric acid can be 3-6 cm.

[0044] In some embodiments, the lithium plating section 21 is at least partially in a zigzag structure. In this way, the lithium plating section 21 can have a longer length, which can be accommodated between the first diaphragm 13 and the second diaphragm 4 by bending or coiling, so as to increase the part of the reference electrode 2 between the first diaphragm 13 and the second diaphragm 4, and form a larger contact surface between the first diaphragm 13 and the second diaphragm 4, so as to better collect the potential.

[0045] Referring to Figure 3 In some examples, the lithium plating section 21 is at least partially in a wavy structure. Referring to Figure 4 In other examples, the lithium plating section 21 is at least partially in a rake structure. Referring to Figure 5 In other examples, the lithium plating section 21 is at least partially in a coiled structure. In the above examples, the lithium plating section 21 can have a longer length, so as to increase the part of the reference electrode 2 between the first diaphragm 13 and the second diaphragm 4, and form a larger contact surface between the first diaphragm 13 and the second diaphragm 4, so as to better collect the potential.

[0046] It should be noted that the zigzag structure of the lithium plating section 21 can be shaped before being immersed in the sulfuric acid, or the lithium plating section 21 can be shaped into a zigzag structure after being immersed in the sulfuric acid.

[0047] In some embodiments, the reference electrode 2 comprises a copper wire, and the diameter of the copper wire is 20-60 microns. In this way, the diameter of the copper wire, which is 20-60 microns, can have good potential reference performance while having a certain mechanical strength. In addition, if the diameter of the copper wire is greater than 6 microns, the time required for the lithium plating process is longer; when the diameter of the copper wire is less than 20 microns, the copper wire is too thin and is not convenient to operate.

[0048] In some embodiments, the diameter of the copper wire can also be 45-55 microns.

[0049] The present application also provides a battery comprising the three-electrode battery as above.

[0050] In summary, since the reference electrode 2 and the independent positive electrode sheet 3 are both arranged outside the base battery cell 1, the three-electrode battery cell involved in the present application does not increase the number of separators in the base battery cell 1, thereby not affecting the transport of lithium ions between the positive electrode sheet 11 and the negative electrode sheet 12. In addition, the arrangement of the independent positive electrode sheet 3 can also facilitate subsequent connection with an external charge-discharge test cabinet to perform lithium plating operation on the reference electrode 2.

[0051] In the description of the present application, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0052] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0053] The embodiments, implementation manners and related technical features of the present application can be combined and replaced with each other without conflict.

[0054] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present application without departing from the technical solution content of the present application, all still fall within the scope of the technical solution of the present application.

[0055] Although the present application has been specifically described above in combination with the drawings and embodiments, it can be understood that the above description does not limit the present application in any form. Those skilled in the art can deform and change the present application according to needs without deviating from the essential spirit and scope of the present application, and these deformations and changes all fall within the scope of the present application.

Claims

1. A three-electrode cell, characterized in that, The three-electrode battery cell comprises: a basic battery cell comprising a plurality of positive electrode sheets, negative electrode sheets and first separators arranged in a stack, the positive electrode sheets and the negative electrode sheets are alternately arranged in sequence, and a first separator is arranged between adjacent positive electrode sheets and negative electrode sheets, and the outermost two sides of the basic battery cell are the first separators; a reference electrode located on one side of the basic battery cell; an independent positive electrode sheet located on the side of the reference electrode away from the basic battery cell; a plurality of second separators, one of which is arranged between the reference electrode and the independent positive electrode sheet, and one of which is arranged on the side of the independent positive electrode sheet away from the reference electrode.

2. The three-electrode cell of claim 1, wherein, The three-electrode battery cell further comprises a positive electrode tab connected to the positive electrode sheet, a negative electrode tab connected to the negative electrode sheet, a reference electrode tab connected to the reference electrode, and an independent positive electrode tab connected to the independent positive electrode sheet; The positive electrode tab and the negative electrode tab are located on the same side of the three-electrode battery cell; The reference electrode tab and the independent positive electrode tab are located on the same side of the three-electrode battery cell and are on the opposite side of the positive electrode tab.

3. The three-electrode cell of claim 2, wherein, The three-electrode battery cell further comprises a top side and a bottom side opposite to each other; The positive electrode tab and the negative electrode tab are located on the top side; The reference electrode tab and the independent positive electrode tab are located on the bottom side.

4. The three-electrode cell of claim 3, wherein, The reference electrode comprises a lithium-plated section and a lithium-free section connected to each other; The lithium-plated section is located between the first separator and the second separator, the lithium-free section extends out of the first separator and the second separator, and the lithium-free section is connected to the reference electrode tab.

5. The three-electrode cell of claim 4, wherein, The lithium-plated section is provided with a lithium-plated layer on the side facing the independent positive electrode sheet.

6. The three-electrode cell of claim 4, wherein, The lithium-plated section is at least partially in a meandering structure.

7. The three-electrode cell of claim 6, wherein, The lithium-plated section is at least partially in a wavy structure; or The lithium-plated section is at least partially in a rake structure; or The lithium-plated section is at least partially in a coiled structure.

8. The three-electrode cell of claim 1, wherein, The basic battery cell comprises a first side and a second side opposite to each other, and the first side and the second side are both provided with the first separator; On the first side, the negative electrode sheet is adjacent to the outermost first separator; On the second side, the negative electrode sheet is adjacent to the outermost first separator.

9. The three-electrode cell of any one of claims 1-8, wherein, The material of the reference electrode is copper.

10. The three-electrode cell of claim 9, wherein, The reference electrode comprises a copper wire, and the diameter of the copper wire is 20-60 microns; or The diameter of the copper wire is 45-55 microns.

11. A battery, characterized by The three-electrode battery cell according to any one of claims 1-10 is provided.

Images