Lithium ion battery
By designing multiple reference electrode groups in a lithium-ion battery and using lithium iron phosphate and copper wire structures, the accuracy and cost issues of monitoring lithium plating inside the battery are solved, enabling comprehensive monitoring of lithium plating inside the battery. This method is suitable for long-cycle performance analysis of new energy vehicles and electronic products.
Patent Information
- Application Number
- CN202520095644.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-15
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2035-01-15
AI Technical Summary
Existing lithium-ion batteries make it difficult to comprehensively and accurately monitor lithium plating inside the battery during electrochemical research and testing. Furthermore, traditional reference electrode materials suffer from signal disturbances, operational complexity, and high costs.
Design a lithium-ion battery comprising multiple reference electrode groups, using lithium iron phosphate as the fixing part and copper wire as the lead part, and achieve potential calibration and precise monitoring through current density distribution theory design, and adopt a multi-component structure for comprehensive lithium plating monitoring.
It enables comprehensive and accurate monitoring of lithium plating inside batteries, improves testing accuracy and ease of operation, reduces costs, and is suitable for long-cycle performance analysis of new energy vehicles and electronic products.
Smart Images
Figure CN223884431U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of batteries, in particular to a lithium ion battery provided with multiple reference electrodes. BACKGROUND
[0002] With the development of the lithium ion battery industry, the research on batteries is also more and more in-depth. Generally, when the lithium ion battery is detected, only the overall electrochemical performance of the battery can be studied, and the positive and negative electrodes of the battery cannot be studied separately. Therefore, a reference electrode needs to be introduced into the battery.
[0003] In the process of electrochemical research and testing, the reference electrode can provide a known and stable potential reference point. Therefore, by taking the reference electrode as the reference point, the actual potential of the positive and negative electrodes (working electrodes) of the battery can be accurately measured, and the performance of the positive and negative electrodes can be studied separately. However, it is difficult to achieve all-around accurate monitoring of the lithium precipitation in the battery. CONTENT OF THE UTILITY MODEL
[0004] Therefore, the purpose of the present application is to provide a lithium ion battery provided with multiple reference electrodes, which can achieve all-around accurate monitoring of the lithium precipitation in the battery.
[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:
[0006] A lithium ion battery includes a battery cell, a positive electrode tab and a negative electrode tab, and a first main reference electrode, a second main reference electrode, an auxiliary reference electrode and a third main reference electrode arranged and spaced in sequence along the direction in which the current density inside the battery gradually decreases. The auxiliary reference electrode can be used to calibrate the potential of the first main reference electrode, the second main reference electrode and the third main reference electrode.
[0007] Optionally, in the above-mentioned lithium ion battery, the positive electrode tab and the negative electrode tab are respectively located at both ends of the battery cell in the X direction.
[0008] The first main reference electrode, the second main reference electrode, the auxiliary reference electrode and the third main reference electrode are all located between the positive electrode tab and the negative electrode tab, and are arranged and spaced in sequence along the direction gradually away from the positive electrode tab in the X direction.
[0009] Optionally, in the above-mentioned lithium ion battery, the first main reference electrode includes a first fixed part located inside the battery cell, and a first lead part connected in reference to the first fixed part and extending out of the battery cell. The surface material of the first fixed part includes lithium iron phosphate, and the first lead part includes a first copper wire.
[0010] And / or, the second main reference electrode comprises a second fixed part located in the battery cell, and a second lead part connected with the second fixed part and extending out of the battery cell, the surface material of the second fixed part comprises lithium iron phosphate, and the second lead part comprises a second copper wire;
[0011] And / or, the third main reference electrode comprises a third fixed part located in the battery cell, and a third lead part connected with the third fixed part and extending out of the battery cell, the surface material of the third fixed part comprises lithium iron phosphate, and the third lead part comprises a third copper wire.
[0012] Optionally, in the above lithium ion battery, the first fixed part, the second fixed part and the third fixed part are all in a sheet structure, and the plane of the sheet structure is parallel to the pole sheet in the battery cell.
[0013] Optionally, in the above lithium ion battery, the first fixed part and the first lead part are rivet-welded, and the connection part is located in the battery cell.
[0014] And / or, the second fixed part and the second lead part are rivet-welded, and the connection part is located in the battery cell.
[0015] And / or, the third fixed part and the third lead part are rivet-welded, and the connection part is located in the battery cell.
[0016] Optionally, in the above lithium ion battery, the auxiliary reference electrode comprises:
[0017] A fourth fixed part located in the battery cell, the fourth fixed part comprises a copper wire body without an oxidation layer, and a metal lithium coating layer located on the outer surface of the copper wire body without an oxidation layer.
[0018] A fourth lead part connected with the fourth fixed part and located outside the battery cell, the fourth lead part comprises an enameled wire copper wire.
[0019] Optionally, in the above lithium ion battery, the diameter of the auxiliary reference electrode is any value in the range of 20 microns to 40 microns.
[0020] And / or, the length of the metal lithium coating layer is any value in the range of 1 centimeter to 2 centimeters.
[0021] Optionally, in the above lithium ion battery, the second main reference electrode is located at the intermediate position of the positive electrode tab and the negative electrode tab.
[0022] And / or, the second main reference electrode is located at the intermediate position between the first main reference electrode and the third main reference electrode.
[0023] And / or, the auxiliary reference electrode is located at an intermediate position between the second main reference electrode and the third main reference electrode.
[0024] Optionally, in the above lithium ion battery, in the X direction:
[0025] The width dimension k of the first fixed part, the second fixed part and the third fixed part is any value in the range of 0.7mm to 1.3mm, for example 1mm.
[0026] And / or, the ratio between the interval distance a between the positive electrode tab and the first main reference electrode and the X direction size h of the lithium ion battery satisfies 1 / 20≤a / h≤3 / 20, for example a=1 / 10h.
[0027] And / or, the ratio between the interval distance b between the first main reference electrode and the second main reference electrode and the X direction size h of the lithium ion battery satisfies 2 / 10≤b / h≤4 / 10, for example b=3 / 10h.
[0028] And / or, the ratio between the interval distance c between the second main reference electrode and the third main reference electrode and the X direction size h of the lithium ion battery satisfies 2 / 10≤c / h≤4 / 10, for example c=3 / 10h.
[0029] And / or, the ratio between the interval distance g between the third main reference electrode and the negative electrode tab and the X direction size h of the lithium ion battery satisfies 1 / 6≤g / h≤3 / 6, for example g=1 / 3h.
[0030] Optionally, in the above lithium ion battery, in the Y direction perpendicular to the X direction:
[0031] The interval distance between the connection of the first fixed part and the first lead part and the side edge of the battery where the first lead part is located, the interval distance between the connection of the second fixed part and the second lead part and the side edge of the battery where the second lead part is located, and the interval distance between the connection of the third fixed part and the third lead part and the side edge of the battery where the third lead part is located are all i, i is greater than zero; the length dimension of the first fixed part, the second fixed part and the third fixed part are all e, e is greater than zero; i and e satisfy 2 / 4f≤i+e≤f, f is the Y direction size of the lithium ion battery.
[0032] As can be seen from the above technical solution, the lithium-ion battery provided in this application is designed based on the theory of internal current density distribution of the battery. The first main reference electrode, the second main reference electrode, the third main reference electrode, and the auxiliary reference electrode constitute a reference electrode group composed of multiple reference electrodes. Through the multi-component structure of this reference electrode group, the potentials of the first, second, and third main reference electrodes can be calibrated in real time, thereby improving the sample preparation quality and testing accuracy of the reference electrode group. Furthermore, since the multiple reference electrodes in this reference electrode group are located in multiple regions with different current densities inside the battery, precise potential monitoring of different regions where each reference electrode is located is possible. The potential distribution at different locations inside the battery can be obtained in real time, enabling comprehensive and precise monitoring of the actual situation inside the battery. This allows for the determination of lithium deposition in different regions during battery operation, ultimately achieving comprehensive and precise monitoring of lithium deposition within the battery. Attached Figure Description
[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0034] Figures 1 to 3 The diagram shows three types of lithium-ion batteries with tabs located at different positions and the arrangement of their internal reference electrodes, which are provided for embodiments of this application.
[0035] Figure 4 This is a flowchart illustrating the method for preparing an LFP reference electrode assembly according to an embodiment of this application.
[0036] in:
[0037] 1-First main reference electrode, 2-Second main reference electrode, 3-Third main reference electrode
[0038] 4-Auxiliary reference electrode, 5-Positive tab, 6-Negative tab, 7-Battery cell, 10-Side,
[0039] 11-First lead portion, 12-First fixing portion,
[0040] 21-Second lead portion, 22-Second fixing portion,
[0041] 31-Third lead section, 32-Third fixing section,
[0042] 41-Fourth lead wire part, 42-Fourth fixing part. Detailed Implementation
[0043] Term explanation:
[0044] Reference electrode: electrode used as a reference for measuring electrode potential. The electrode to be measured and the reference electrode with a precisely known electrode potential value form a battery, and the battery electromotive force value is measured to calculate the electrode potential of the measured electrode.
[0045] Current density: a physical quantity describing the strength and direction of current at a certain point in the circuit. Its size is equal to the amount of electricity passing through a unit area per unit time, and the direction vector is the normal vector of the corresponding cross section of the unit area, pointing to the direction determined by the passage of positive charges through this cross section.
[0046] Lithium iron phosphate: an inorganic compound widely used as a positive material in lithium-ion batteries.
[0047] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0048] Please refer to Figure 1 The lithium-ion battery provided in the embodiments of the present application is not only composed of the battery cell 7, the positive tab 5 and the negative tab 6, but also sequentially arranged and spaced apart in the direction of gradually decreasing internal current density of the battery, the first main reference electrode 1, the second main reference electrode 2, the auxiliary reference electrode 4 and the third main reference electrode 3. The auxiliary reference electrode 4 can be used to calibrate the potential of the first main reference electrode 1, the second main reference electrode 2 and the third main reference electrode 3.
[0049] It can be seen that the lithium ion battery provided by the embodiment of the application is designed based on the theory of internal current density distribution of the battery, the current distribution in the battery can be simulated by COMSOL (a multi-physical field simulation software), and then the lithium precipitation in different current density regions can be monitored accurately. The first main reference electrode 1, the second main reference electrode 2, the third main reference electrode 3 and the auxiliary reference electrode 4 form a reference electrode group composed of multiple reference electrodes. Through the multi-component structure of the reference electrode group, the potentials of the first main reference electrode 1, the second main reference electrode 2 and the third main reference electrode 3 can be calibrated in real time, and the sample preparation quality and test accuracy of the reference electrode group can be improved. In addition, the multiple reference electrodes in the reference electrode group are located in multiple regions with different internal current densities of the battery, so that the different regions where the reference electrodes are located can be monitored accurately, the potential distribution at different positions in the battery can be obtained in real time, and the actual situation in the battery can be monitored accurately in all directions to determine the lithium precipitation in different regions during the operation of the battery, and finally the lithium precipitation in the battery can be monitored accurately in all directions.
[0050] The positive and negative tabs as working electrodes are key components for connecting the internal electrodes and external circuits in the lithium ion battery, and can be arranged at both ends of the cell. For example, please refer to Figures 1 to 3 In some embodiments, the positive tab 5 and the negative tab 6 are respectively located at both ends of the cell 7 in the X direction. It should be noted that the positive tab 5 and the negative tab 6 are respectively located at both ends of the cell 7 in the X direction, which can be located at the opposite two sides (see Figure 1 and Figure 2 ), or can be located at both ends of the same side 10 (see Figure 3 ). Moreover, when the lithium ion battery is in a rectangular block structure, the X direction can be the length direction (see Figure 1 ) or the width direction (see Figure 2 ) or the thickness direction; when the lithium ion battery is in other shapes, the X direction can be any side of the lithium ion battery.
[0051] Moreover, when the positive tab 5 and the negative tab 6 are respectively located at both ends of the cell 7 in the X direction, the first main reference electrode 1, the second main reference electrode 2, the auxiliary reference electrode 4 and the third main reference electrode 3 are located between the positive tab 5 and the negative tab 6, and are arranged and spaced along the X direction, so as to achieve the purpose of monitoring different regions with different internal current densities in the battery.
[0052] In the prior art, the materials of the reference electrode of the lithium ion battery are basically copper, lithium, stainless steel or platinum, but copper and stainless steel will disturb the electrical signal and affect the test accuracy, lithium is easy to oxidize, the operation steps are complex, and platinum is high in cost. Moreover, with the rapid development of new energy vehicles and various electronic products, the industry has higher requirements for the long cycle performance of lithium ion batteries. Therefore, it is important to build a multi-electrode battery containing a reference electrode with stable testing, high accuracy, simple operation and low cost for analyzing the capacity decay of the positive and negative electrodes during the long cycle of the lithium ion battery and predicting the service life of the lithium ion battery.
[0053] Therefore, in some embodiments, the first main reference electrode 1, the second main reference electrode 2 and the third main reference electrode 3 can all be provided in the form of an assembly structure composed of a fixed part and a lead part. For example, the first main reference electrode 1 includes a first fixed part 12 located in the battery cell 7, and a first lead part 11 connected in reference to the first fixed part 12 and extending out of the battery cell 7, the surface material of the first fixed part 12 includes lithium iron phosphate, and the first lead part 11 can be made of copper wire; and / or, the second main reference electrode 2 includes a second fixed part 22 located in the battery cell 7, and a second lead part 21 connected in reference to the second fixed part 22 and extending out of the battery cell 7, the surface material of the second fixed part 22 includes lithium iron phosphate, and the second lead part 21 can be made of copper wire; and / or, the third main reference electrode 3 includes a third fixed part 32 located in the battery cell 7, and a third lead part 31 connected in reference to the third fixed part 32 and extending out of the battery cell 7, the surface material of the third fixed part 32 includes lithium iron phosphate, and the third lead part 31 can be made of copper wire.
[0054] Among them, lithium iron phosphate has high stability and long service life, as the fixed part of each main reference electrode (i.e. the first fixed part 12, the second fixed part 22, the third fixed part 32) is built in the battery cell 7, and has the characteristics of stable testing, high accuracy, long service life, simple operation, low cost and great application value compared with the copper wire lithium reference electrode. Moreover, copper wire is used as the lead tab (i.e. the first lead part 11, the second lead part 21, the third lead part 31) in each main reference electrode, on the one hand, the specific surface area of copper wire is small, which can play a role in conducting without affecting the performance of the battery cell; on the other hand, the copper wire can be flexibly adjusted in position, which can be drawn out from any position of the lithium ion battery as needed, can improve the flexibility of the position of the reference electrode group, and solve the problem of position limitation of the traditional reference electrode tab. Therefore, the LFP reference electrode group provided by the embodiments of the present application not only has accurate monitoring but also has flexible and adjustable tab position.
[0055] In some embodiments, the first fixed part 12, the second fixed part 22, and the third fixed part 32 are all in a sheet structure, and the plane of the sheet structure is parallel to the pole piece in the battery cell 7, so as to ensure that the internal and external structures of the battery are flat and avoid affecting the performance of the battery itself. Specifically, the region provided with lithium iron phosphate in the first fixed part 12 is in a sheet structure, and is substantially parallel to the pole piece adjacent thereto in the battery cell 7; and / or, the region provided with lithium iron phosphate in the second fixed part 22 is in a sheet structure, and is substantially parallel to the pole piece adjacent thereto in the battery cell 7; and / or, the region provided with lithium iron phosphate in the third fixed part 32 is in a sheet structure, and is substantially parallel to the pole piece adjacent thereto in the battery cell 7. For example, in some embodiments, the first fixed part 12, the second fixed part 22, and the third fixed part 32 can each adopt a lithium iron phosphate pole piece, which refers to a battery positive pole piece made of lithium iron phosphate as the main active material. However, it is not limited thereto, and in other embodiments, other similar structures can also be used as the fixed part of the main reference electrode.
[0056] In some embodiments, the first fixed part 12 and the first lead part 11 are riveted and welded, and the connection part is located in the battery cell 7; and / or, the second fixed part 22 and the second lead part 21 are riveted and welded, and the connection part is located in the battery cell 7; and / or, the third fixed part 32 and the third lead part 31 are riveted and welded, and the connection part is located in the battery cell 7. In short, the fixed part provided with lithium iron phosphate in each main reference electrode is respectively riveted and welded with a copper wire, so as to obtain a fixed position with stable performance and accurate monitoring through lithium iron phosphate, and at the same time, the tab lead part can have high operation flexibility through the copper wire.
[0057] In some embodiments, the auxiliary reference electrode 4 includes a fourth fixed part 42 and a fourth lead part 41. The fourth lead part 41 is located outside the battery cell 7, specifically a copper wire enameled wire; the fourth fixed part 42 is located inside the battery cell 7, and includes a conductive structure formed by a copper wire body without an oxide layer and a metal lithium coating layer on the outer surface thereof. In this embodiment, the auxiliary reference electrode 4 as a whole can be made of a copper wire enameled wire with a diameter of any value in the range of 20 microns to 40 microns, one end of which is treated by acidification to obtain a bare copper wire (i.e., a copper wire body without an oxide layer), and the length of the bare copper wire can be any value in the range of 1 centimeter to 2 centimeters (for example, 1.5 centimeters), and the bare copper wire extends into the inside of the battery cell 7 as the fourth fixed part 42 of the auxiliary reference electrode 4; before testing, the copper wire of the auxiliary reference electrode 4 is plated with lithium, and the fourth lead part 41 of the auxiliary reference electrode 4 is connected with the positive tab 5 and the negative tab 6 in sequence, respectively, and is plated with lithium once, so as to ensure that the copper wire is completely coated with lithium metal, thereby forming the metal lithium coating layer. In specific implementation, the auxiliary reference electrode 4 can be made of a copper wire enameled wire with a diameter of 20-40 microns, and the surface oxide layer of the bare part of the copper wire enameled wire is acidified by 1.5 cm to obtain a copper wire.
[0058] In some embodiments, the second main reference electrode 2 can be arranged at a position between the positive tab 5 and the negative tab 6; and / or, the second main reference electrode 2 can be arranged at a position between the first main reference electrode 1 and the third main reference electrode 3; and / or, the auxiliary reference electrode 4 can be arranged at a position between the second main reference electrode 2 and the third main reference electrode 3. In specific implementations, the arrangement of the reference electrodes can be determined according to the following requirements, please refer to Figure 1 or Figure 2 or Figure 3 :
[0059] In the X direction: the width dimension k of the first fixed part 12, the second fixed part 22 and the third fixed part 32 can be any value within the range of 0.7mm to 1.3mm, for example, k = 1mm; and / or, the ratio between the interval distance a between the positive tab 5 and the first main reference electrode 1 and the X direction dimension h of the lithium ion battery satisfies 1 / 20≤a / h≤3 / 20, for example, a = 1 / 10h; and / or, the ratio between the interval distance b between the first main reference electrode 1 and the second main reference electrode 2 and the X direction dimension h of the lithium ion battery satisfies 2 / 10≤b / h≤4 / 10, for example, b = 3 / 10h; and / or, the ratio between the interval distance c between the second main reference electrode 2 and the third main reference electrode 3 and the X direction dimension h of the lithium ion battery satisfies 2 / 10≤c / h≤4 / 10, for example, c = 3 / 10h; and / or, the ratio between the interval distance g between the third main reference electrode 3 and the negative tab 6 and the X direction dimension h of the lithium ion battery satisfies 1 / 6≤g / h≤3 / 6, for example, g = 1 / 3h.
[0060] In the Y direction perpendicular to the X direction: the interval distance between the connection of the first fixed part 12 and the first lead part 11 and the battery side edge 10 where the first lead part 11 is located, the interval distance between the connection of the second fixed part 22 and the second lead part 21 and the battery side edge 10 where the second lead part 21 is located, and the interval distance between the connection of the third fixed part 32 and the third lead part 31 and the battery side edge 10 where the third lead part 31 is located are all i, i is greater than zero; the length dimension of the first fixed part 12, the second fixed part 22 and the third fixed part 32 are all e, e is greater than zero; the relationship between the above interval distance i, the fixed part length dimension e and the battery Y direction dimension f satisfies 2 / 4f≤i+e≤f, for example, i+e = 3 / 4f or 2 / 3f.
[0061] In addition, the application also provides a preparation method of the LFP (lithium iron phosphate) reference electrode group for precise lithium precipitation monitoring. The LFP reference electrode group in the method is designed based on the actual current distribution in the battery, can monitor the potential of different current density distribution areas, realizes all-around precise lithium precipitation potential monitoring of the lithium ion battery, and can make precise judgment on the lithium precipitation in the actual battery operation.
[0062] Please refer to Figure 4 The preparation method of the LFP reference electrode group provided by the application also includes the following steps:
[0063] Step S1: preparing a first main reference electrode 1, a second main reference electrode 2, a third main reference electrode 3 and an auxiliary reference electrode 4. For example, the first main reference electrode 1, the second main reference electrode 2 and the third main reference electrode 3 are all lithium iron phosphate electrode sheets, the length of which is 2 / 3 of the length of the positive electrode sheet of the battery cell, and the width is 1 mm; the auxiliary reference electrode is a copper wire of a varnished wire with a diameter of 20 microns to 40 microns, and one end of the copper wire is acid treated to expose a part of the surface oxidation layer with a length of 1.5 cm, thereby obtaining the copper wire body in the fourth fixed part 42 described above.
[0064] Step S2: arranging and implanting the first main reference electrode 1, the second main reference electrode 2, the auxiliary reference electrode 4 and the third main reference electrode 3 between the working electrode and the counter electrode of the battery cell to be measured 7, and leading the lead wires of the first main reference electrode 1, the second main reference electrode 2, the auxiliary reference electrode 4 and the third main reference electrode 3 from the side edge 10 of the battery to be measured. The first main reference electrode 1 is placed at the positive tab side area, because the current density is the largest at this position, and the lithium precipitation phenomenon is more likely to occur; the second main reference electrode 2 is placed at the middle position or near the middle position of the battery cell 7, according to the current density simulation distribution, the current density at the middle position is smaller than that at the positive tab, and placing the second main reference electrode 2 at this position can monitor the lithium precipitation in the middle area with slightly weaker current density; the third main reference electrode 3 is placed at a position far away from the positive tab 5 with small current density, and can monitor the lithium precipitation in the area with small current density, and the specific position can be any position between the middle position of the battery cell and the negative tab 6.
[0065] Step S3: assembling, baking, liquid injection, aging, formation and capacity grading of the battery cell.
[0066] Step S4: before testing, the copper wire of the auxiliary reference electrode 4 is plated with lithium, and the copper wire is connected to the positive electrode and the negative electrode in sequence, and is plated with lithium once respectively, so as to ensure that the copper wire is completely covered with metallic lithium.
[0067] Step S5: connecting the first main reference electrode 1, the second main reference electrode 2, the third main reference electrode 3 and the auxiliary reference electrode 4 in turn for potential calibration, and recording the calibration potential, which is used as a reference to monitor the conditions of the main reference electrodes in real time during the subsequent test.
[0068] Finally, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude any other embodiments of the present application that do not fall within the limits of the claims. It will be understood by those skilled in the art that, although the present application has been described in relation to the preceding examples, various modifications can be made thereto without departing from the scope of the application as defined by the following claims. Therefore, the present application should not be limited by the preceding examples.
[0069] The various embodiments in the specification are described in progressive manner, each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.
[0070] The above description of disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A lithium-ion battery comprising a cell (7), and a positive tab (5) and a negative tab (6), characterized in that, The first main reference electrode (1), the second main reference electrode (2), the auxiliary reference electrode (4), and the third main reference electrode (3) are sequentially arranged and spaced apart in the direction in which the current density inside the battery gradually decreases.
2. The lithium-ion battery of claim 1, wherein, The positive tab (5) and the negative tab (6) are respectively located at two ends of the battery cell (7) in the X direction. The first main reference electrode (1), the second main reference electrode (2), the auxiliary reference electrode (4), and the third main reference electrode (3) are sequentially arranged and spaced apart in the direction gradually away from the positive tab (5) in the X direction.
3. The lithium-ion battery of claim 1, wherein, The first main reference electrode (1) includes a first fixed part (12) located inside the battery cell (7), and a first lead part (11) connected in reference to the first fixed part (12) and extending out of the battery cell (7), the surface material of the first fixed part (12) includes lithium iron phosphate, and the first lead part (11) includes a first copper wire; And / or, the second main reference electrode (2) includes a second fixed part (22) located inside the battery cell (7), and a second lead part (21) connected in reference to the second fixed part (22) and extending out of the battery cell (7), the surface material of the second fixed part (22) includes lithium iron phosphate, and the second lead part (21) includes a second copper wire; And / or, the third main reference electrode (3) includes a third fixed part (32) located inside the battery cell (7), and a third lead part (31) connected in reference to the third fixed part (32) and extending out of the battery cell (7), the surface material of the third fixed part (32) includes lithium iron phosphate, and the third lead part (31) includes a third copper wire.
4. The lithium-ion battery of claim 3, wherein, The first fixed part (12), the second fixed part (22), and the third fixed part (32) are all in a sheet structure, and the plane of the sheet structure is parallel to the pole piece in the battery cell (7).
5. The lithium-ion battery of claim 3, wherein, The first fixed part (12) and the first lead part (11) are rivet-welded, and the connection part is located inside the battery cell (7); And / or, the second fixed part (22) and the second lead part (21) are rivet-welded, and the connection part is located inside the battery cell (7); And / or, the third fixed part (32) and the third lead part (31) are rivet-welded, and the connection part is located inside the battery cell (7).
6. The lithium-ion battery of claim 1, wherein, The auxiliary reference electrode (4) includes: A fourth fixed part (42) located inside the battery cell (7), the fourth fixed part (42) includes a copper wire body without an oxidation layer, and a metal lithium coating layer located on the outer surface of the copper wire body without an oxidation layer; A fourth lead part (41) connected with the fourth fixed part (42) and located outside the battery cell (7), the fourth lead part (41) includes an enameled copper wire.
7. The lithium-ion battery of claim 6, wherein, The diameter of the auxiliary reference electrode (4) is any value in the range of 20-40 microns; And / or, the length of the lithium metal coating layer is any value in the range of 1-2 cm.
8. The lithium-ion battery of claim 2, wherein, The second main reference electrode (2) is located at the middle position between the positive tab (5) and the negative tab (6); And / or, the second main reference electrode (2) is located at the middle position between the first main reference electrode (1) and the third main reference electrode (3); And / or, the auxiliary reference electrode (4) is located at the middle position between the second main reference electrode (2) and the third main reference electrode (3).
9. The lithium-ion battery of claim 3, wherein, In the X direction: The width dimension k of the first fixed part (12), the second fixed part (22), and the third fixed part (32) is any value in the range of 0.7-1.3 mm; And / or, the ratio between the interval distance a between the positive tab (5) and the first main reference electrode (1) and the X direction size h of the battery satisfies 1 / 20≤a / h≤3 / 20; And / or, the ratio between the interval distance b between the first main reference electrode (1) and the second main reference electrode (2) and the X direction size h of the battery satisfies 2 / 10≤b / h≤4 / 10; And / or, the ratio between the interval distance c between the second main reference electrode (2) and the third main reference electrode (3) and the X direction size h of the battery satisfies 2 / 10≤c / h≤4 / 10; And / or, the ratio between the interval distance g between the third main reference electrode (3) and the negative tab (6) and the X direction size h of the battery satisfies 1 / 6≤g / h≤3 / 6.
10. The lithium-ion battery of claim 3, wherein, In the Y direction: The interval distance between the connection of the first fixed part (12) and the first lead part (11) and the battery side (10) where the first lead part (11) is located, the interval distance between the connection of the second fixed part (22) and the second lead part (21) and the battery side (10) where the second lead part (21) is located, and the interval distance between the connection of the third fixed part (32) and the third lead part (31) and the battery side (10) where the third lead part (31) is located are all i, i is greater than zero; The length dimension of the first fixed part (12), the second fixed part (22), and the third fixed part (32) are all e, e is greater than zero; i and e satisfy 2 / 4f≤i+e≤f, f is the Y direction size of the battery.