Lithium battery

Abstract

The utility model provides a lithium battery. The lithium battery comprises: a battery cell comprising at least one lamination unit, the lamination unit comprising a first diaphragm and pole pieces located at two sides of the first diaphragm; at least two reference electrodes; the at least two reference electrodes and the at least two second diaphragms are arranged in a one-to-one correspondence mode, and the reference electrodes are located between the second diaphragms and the first diaphragms corresponding to the reference electrodes; when the number of the laminated unit is one, the at least two reference electrodes are connected with the laminated unit; when the number of the laminated units is at least two, the at least two laminated units are sequentially laminated, the at least two reference electrodes are connected with any one of the at least two laminated units and are located at different positions of the laminated unit, or the at least two reference electrodes are respectively connected with different laminated units. According to the technical scheme provided by the utility model, the problem of resource waste caused by the fact that a battery cell needs to be disassembled and cannot be reused after being disassembled in a test method in the prior art can be solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to lithium battery technical field, specifically, relate to a lithium battery. BACKGROUND

[0002] Lithium battery, as indispensable energy storage unit in modern electronic equipment and electric vehicle, is a kind of secondary battery that relies on lithium ion migration between positive and negative electrode. With the rapid progress of science and technology and the increasing digitalization of people's lifestyle, the performance requirements of lithium ion battery are also constantly improved, users not only expect more portable and more durable batteries, but also hope that the battery can realize fast charging, which directly promotes the demand for double improvement of battery energy density and fast charging compatibility. However, the maximum rate of lithium battery fast charging time and charging is affected by many factors such as the material used by the cell, the cell process, the cell shape, etc. For the same cell, the maximum rate that can be tolerated by different positions inside is also different, which means that the maximum charging rate that can be tolerated by each region inside the cell is not consistent. By studying the maximum rate that can be tolerated by different positions of the same cell, and then improving the area with lower rate charging, the fast charging capacity of the whole cell can be improved.

[0003] At present, in order to determine the maximum rate that can be tolerated by different positions of the cell, the cell usually needs to be cycled charged and discharged for a certain number of times at a certain temperature, and then the cell is disassembled and the lithium precipitation situation of different positions is determined through the overall interface of the cell. The above method is intuitive, but the cell cannot be reused after disassembly, resulting in resource waste. UTILITY MODEL CONTENT

[0004] The main purpose of the utility model is to provide a kind of lithium battery, can solve the problem of resource waste caused by the test method of prior art needing to disassemble cell, cell cannot be reused after disassembly.

[0005] In order to achieve the above purpose, the utility model provides a kind of lithium battery, comprising: cell, including at least one layering unit, layering unit includes first diaphragm and the pole piece located on the two sides of first diaphragm, one of two pole pieces is positive pole piece, another of two pole pieces is negative pole piece;At least two reference electrodes;At least two second diaphragms, second diaphragm is located between pole piece and first diaphragm, at least two reference electrodes are set one by one with at least two second diaphragms, reference electrode is located between second diaphragm and first diaphragm corresponding thereto;When layering unit is one, at least two reference electrodes are connected with layering unit, and at least two reference electrodes are located at different positions of layering unit;When layering unit is at least two, at least two layering units are stacked in turn, at least two reference electrodes are connected with any one of at least two layering units and located at different positions of layering unit, or, at least two reference electrodes are connected with different layering units respectively.

[0006] Further, the number of the stacked units is N, each reference electrode is connected with any one of the stacked units between the second stacked unit and the N-2th stacked unit, wherein N is a positive integer greater than 2.

[0007] Further, the number of the stacked units is at least two, the at least two stacked units are arranged one by one with the at least two reference electrodes, and the positions of the at least two reference electrodes on the corresponding stacked units are the same.

[0008] Further, the reference electrode comprises an inserted section and an exposed section, one end of the inserted section is located between the second diaphragm and the first diaphragm corresponding to the inserted section, and the exposed section extends out of the battery cell.

[0009] Further, the inserted section is located between the second diaphragm and the first diaphragm corresponding to the inserted section.

[0010] Further, the length of the second diaphragm is L1, the width of the second diaphragm is W1, the length of the inserted section is L2, the value range of L1 / L2 is 2-3, and the value range of W1 is 3cm-5cm.

[0011] Further, the lithium battery further comprises a shell, the shell has a mounting cavity, the battery cell and all the second diaphragms are mounted in the mounting cavity, and the exposed section of each reference electrode is located outside the mounting cavity.

[0012] Further, the lithium battery further comprises at least two connecting tabs, the at least two connecting tabs are arranged one by one with the at least two reference electrodes, and the connecting tab is connected with the corresponding reference electrode.

[0013] Further, the surface of the reference electrode is provided with a lithium plating layer.

[0014] Further, the first diaphragm and the second diaphragm are made of the same material.

[0015] The technical scheme of the present application can monitor the change of the reference electrode potential of the battery cell under different temperatures and SOC conditions during the charging process of the battery cell at a specified rate, and then evaluate the maximum rate charging capacity limit that can be borne by different positions of the battery cell through the voltage of the reference electrode, without the need to actually disassemble the battery cell to observe the interface, thereby avoiding damage to the battery cell caused by disassembly, allowing the battery cell to remain intact after testing, and thereby being reusable, thereby avoiding resource waste caused by disassembly. BRIEF DESCRIPTION OF DRAWINGS

[0016] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the exemplary embodiments of the present application and their description serve to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0017] In the drawings:

[0018] Figure 1 Part structure schematic diagram of a lithium battery of an embodiment of the utility model is shown;

[0019] Figure 2 Part structure schematic diagram of a lithium battery of an embodiment of the utility model is shown;

[0020] Figure 3 Part structure schematic diagram of a lithium battery of an embodiment of the utility model is shown.

[0021] Among them, the above-mentioned drawings include the following reference signs:

[0022] 10, cell; 11, laminated unit; 111, first diaphragm; 112, pole piece; 20, reference electrode; 30, second diaphragm. DETAILED DESCRIPTION

[0023] It should be noted that the embodiments in the utility model and the features in the embodiments can be combined with each other without conflict. The utility model will be described in detail below with reference to the drawings and in combination with embodiments.

[0024] At present, the maximum rate that can be borne by different positions of the cell needs to be determined by disassembling and cycling for a certain number of times, and then determining the lithium precipitation condition of different positions according to the overall interface of the cell. The cell cannot be reused, the cycle number is generally 20-50 cycles, a large amount of time is needed, and the maximum rate that can be borne by the cell at one temperature can only be verified at a time, which requires a large amount of resources and time.

[0025] In order to solve the above problems, combined with reference to Figures 1 to 3As shown, the utility model provides a kind of lithium battery, and the lithium battery includes: electric core 10, including at least one laminated unit 11, laminated unit 11 includes first diaphragm 111 and the pole piece 112 located in the two sides of first diaphragm 111, one of two pole pieces 112 is positive pole piece 112, another of two pole pieces 112 is negative pole piece 112;At least two reference electrodes 20;At least two second diaphragms 30, second diaphragm 30 is located between pole piece 112 and first diaphragm 111, at least two reference electrodes 20 are set one by one with at least two second diaphragms 30, reference electrode 20 is located between the second diaphragm 30 and first diaphragm 111 corresponding therewith;When laminated unit 11 is one, at least two reference electrodes 20 are connected with laminated unit 11, and at least two reference electrodes 20 are located at different positions of laminated unit 11;When laminated unit 11 is at least two, at least two laminated units 11 are sequentially stacked, at least two reference electrodes 20 are connected with any one of at least two laminated units 11 and are located at different positions of laminated unit 11, or, at least two reference electrodes 20 are connected with different laminated units 11 respectively.

[0026] In this embodiment, by arranging at least two reference electrodes 20 inside the battery cell 10, the potential changes of the reference electrodes 20 at different temperatures and SOC conditions during the charging process of the battery cell 10 at a specified rate can be monitored in real time. Then, the maximum rate charging capacity limit that can be tolerated by different positions of the battery cell 10 can be evaluated by the voltage of the reference electrode 20, without the need to actually disassemble the battery cell 10 to observe the interface. This can avoid damage to the battery cell 10 caused by disassembly, so that the battery cell 10 can remain intact after testing, thereby allowing repeated use and reducing the difficulty of battery cell 10 verification. The second separator 30 is introduced between the tab 112 and the first separator 111, and the reference electrode 20 is placed between the first separator 111 and the second separator 30. This not only ensures the correct isolation of the reference electrode 20 from the inside of the battery cell 10, avoiding short circuits or affecting the performance of the battery cell 10 caused by direct contact, but also ensures that the reference electrode 20 can play a stable monitoring role in the charging cycle. By corresponding arrangement of at least two reference electrodes 20 and at least two second separators 30, the lithium precipitation boundary at multiple positions inside the battery cell 10 can be monitored. This arrangement allows simultaneous acquisition of lithium precipitation information in different regions without damaging the battery cell 10, thereby improving the efficiency and comprehensiveness of the test. As can be seen from the above, by arranging at least two reference electrodes 20 and at least two second separators 30 inside the battery cell 10, non-destructive monitoring of the lithium precipitation boundary of the battery cell 10 during charging is achieved. This not only reduces the cost and time of battery cell 10 testing, avoids resource waste caused by disassembly, but also improves the efficiency and sustainability of battery cell 10 testing. Moreover, by obtaining the difference in rate charging capacity performance of certain specified positions of the battery cell 10, targeted improvements can be made to improve the performance of the battery cell 10.

[0027] It should be noted that when the laminated unit 11 is at least two, a third separator is arranged between the adjacent two laminated units 11, and the polarities of the two tabs located on both sides of the third separator are opposite. Figure 1 and Figure 3 The area where the black dots in the above-mentioned figures are located is the setting position of the reference electrode.

[0028] SOC is the abbreviation of "State of Charge", which is usually translated as "State of Charge" or "Remaining Capacity" in Chinese. In the field of battery management and monitoring, SOC refers to the ratio of the remaining capacity of the battery to the total capacity of the battery, often expressed in percentage form. It is a key parameter in the battery management system (BMS), which reflects the battery capacity level, helps users understand the remaining use time of the battery, and assists in achieving optimized charging and discharging control of the battery to avoid overcharging or overdischarging, thereby protecting the battery and prolonging its service life.

[0029] In one embodiment, the reference electrode 20 is a lacquered copper wire, the diameter of the reference electrode 20 ranges from 20 μm to 80 μm, and the length ranges from 50 cm to 100 cm.

[0030] It should be noted that the reference electrode 20 needs to be pretreated as follows: 10 mm to 20 mm of both ends of the copper wire are sequentially immersed in an acid solution, an alcohol solvent, and water, and then dried and polished using fine sandpaper with a mesh size of 200 mesh or more, and finally one end of the pretreated copper wire is fixed on a second diaphragm 30. After the reference electrode 20 is installed, the sealing work related to the battery cell 10 is performed, and then the battery cell 10 is subjected to liquid injection, formation, aging, and capacity distribution.

[0031] Referring to Figures 1 to 3 In one embodiment of the utility model, the number of the laminated units 11 is N, each reference electrode 20 is connected to any one of the laminated units 11 between the second laminated unit 11 and the N-2 laminated unit 11, wherein N is a positive integer greater than 2.

[0032] In this embodiment, the reference electrode 20 is arranged between the second laminated unit 11 and the N-2 laminated unit 11, that is, the laminated unit 11 where the reference electrode 20 is located has laminated units 11 on the upper and lower sides, which can clamp the reference electrode 20 in the stacking direction, so that the reference electrode 20 can be stably clamped between the second diaphragm 30 and the first diaphragm 111, thereby improving the connection stability of the reference electrode 20 and the battery cell 10.

[0033] Referring to Figures 1 to 3 In one embodiment of the utility model, the number of the laminated units 11 is N, each reference electrode 20 is connected to any one of the laminated units 11 between the second laminated unit 11 and the N-2 laminated unit 11, wherein N is a positive integer greater than 2.

[0034] In this embodiment, by arranging the reference electrode 20 at the same position of different laminated units 11, the charging capacity difference of the same position region of different layers of the battery cell 10 can be obtained.

[0035] Referring to Figures 1 to 3 In one embodiment of the utility model, the reference electrode 20 includes an insertion section and an exposed section, one end of the insertion section is located between the corresponding second diaphragm 30 and the first diaphragm 111, and the exposed section extends out of the battery cell 10.

[0036] In the embodiment, the insertion section of the reference electrode 20 is located between the second diaphragm 30 and the first diaphragm 111, and the insertion section is in direct contact with the electrolyte and the active material inside the battery cell 10, while the exposed section extends out of the battery cell 10 and can be connected with the external testing device, so that the testing process does not need to damage the structure of the battery cell 10, and since the exposed section of the reference electrode 20 can be directly connected with the external device, repeated tests can be performed on the same battery cell 10 at different time points or in different charge cycles, and long-term monitoring of the performance of the battery cell 10 over time can be realized.

[0037] Referring to Figures 1 to 3 In an embodiment of the utility model, the insertion section is located between the second diaphragm 30 and the first diaphragm 111 corresponding to the insertion section.

[0038] In the embodiment, the insertion section is located between the second diaphragm 30 and the first diaphragm 111, which can form physical isolation for the insertion section, reduce the probability of side reactions between the active material and the reference electrode 20, and thus improve the service life of the reference electrode 20.

[0039] Referring to Figures 1 to 3 In an embodiment of the utility model, the length of the second diaphragm 30 is L1, the width of the second diaphragm 30 is W1, the length of the insertion section is L2, and the value range of L1 / L2 is 2-3, and the value range of W1 is 3cm-5cm.

[0040] In the embodiment, the value range of L1 / L2 is 2-3, that is, the length of the second diaphragm 30 is at least twice the length of the insertion section, which can avoid direct contact between the reference electrode 20 and the active material, provide a stable environment for the reference electrode 20, and prolong the service life of the reference electrode 20.

[0041] In an embodiment of the utility model, the lithium battery further comprises a housing, the housing has a mounting cavity, the battery cell 10 and all the second diaphragms 30 are mounted in the mounting cavity, and the exposed sections of the reference electrodes 20 are located outside the mounting cavity.

[0042] In the embodiment, the exposed section is located outside the mounting cavity, which facilitates connection with the external testing device, simplifies the testing operation process, and improves the testing efficiency.

[0043] In an embodiment of the utility model, the lithium battery further comprises at least two connecting tabs, the at least two connecting tabs are arranged in one-to-one correspondence with the at least two reference electrodes 20, and the connecting tab is connected with the reference electrode 20 corresponding to the connecting tab.

[0044] In the embodiment, the direct corresponding connection of the connecting tab and the reference electrode 20 is connected with the external circuit through the connecting tab, the circuit connection in the test process is simplified, the tester does not need to find a specific reference electrode 20 connection point in the battery cell 10, and only needs to establish an external circuit connection with the corresponding connecting tab, so that the test efficiency can be significantly improved.

[0045] In one embodiment, the connecting tab is made of copper wire, and the connecting tab is welded with the reference electrode 20.

[0046] In one embodiment of the utility model, the surface of the reference electrode 20 is provided with a lithium plating layer.

[0047] In the embodiment, the surface of the reference electrode 20 is provided with a lithium plating layer, so that the reference electrode 20 can serve as a reference for potential measurement. The lithium-plated reference electrode 20 can be used to monitor the lithium precipitation under different temperatures and different SOC conditions. When the battery is rapidly charged, if the potential on the negative electrode surface drops below the lithium precipitation potential, lithium precipitation starts. At the same time, by plating lithium on the reference electrode 20, multiple charging and discharging tests can be performed without damaging the battery itself, avoiding the waste of resources caused by disassembly and reassembly of the battery after each test.

[0048] It should be noted that the lithium plating layer of the reference electrode 20 can be formed by positive plating lithium, using the positive electrode as the plating lithium anode and the reference electrode 20 as the plating lithium cathode for plating lithium, or can also be formed by negative plating lithium, using the negative electrode as the plating lithium anode and the reference electrode 20 as the plating lithium cathode for plating lithium, or simultaneously using positive plating lithium and negative plating lithium multiple times alternately, the plating lithium uses a current of 10-50 mu A, and the plating time is 3-10 hours.

[0049] In one embodiment of the utility model, the first diaphragm 111 and the second diaphragm 30 are made of the same material.

[0050] In the embodiment, the use of diaphragms made of the same material can ensure a uniform electrochemical environment inside the battery cell 10, reduce local electrochemical performance changes caused by material differences, and in addition, the same diaphragm material helps to maintain the consistency of the structure of the battery cell 10, avoiding unevenness of the internal structure of the battery cell 10 caused by differences in physical properties (such as thickness, porosity, elasticity, etc.) of different diaphragm materials.

[0051] In one embodiment, two pole pieces in the laminated unit 11, one is a positive pole piece, and the other is a negative pole piece. The positive pole piece has a positive tab, and the negative pole piece has a negative tab.

[0052] Cell test: three cells from each of the experimental comparison 1 group and the experimental comparison 2 group are tested. The test temperature range is 20-55°C, and the test rate range is 0.1C-5C (1C represents the rate at which a lithium battery is charged from empty to the rated capacity within one hour at room temperature).

[0053] The positive and negative tabs of the cells are connected to the ends of the charging cabinet, and different rate charges under different temperature conditions are carried out, while monitoring the voltage changes of the reference electrodes and the negative electrodes at different positions. When the voltage difference between the negative electrode and the reference electrode of one of the cells is lower than a set value, which is generally in the range of (0mv-15mv), the test is stopped at this time, and the charging ambient temperature, the charging rate, and the corresponding SOC interval are recorded. According to the above test scheme, the required temperature and rate are tested. Taking the cell that meets the 3C-4C rate charging capability as an example, the test results are as follows:

[0054] Example 1: The 3C charging data of the target cell under the conditions of 10°C, 25°C, and 45°C are as follows. The five reference electrodes 20 in the experimental comparison 1 group are located at different positions in the same laminated unit 11 of the cell. The number of laminated units in the experimental comparison 2 group is 60. The four reference electrodes 20 in the experimental comparison 2 group are located in the first laminated unit, the 15th laminated unit, the 20th laminated unit, and the 30th laminated unit, respectively. The above four reference electrodes are located at the same position in different layers of the cell:

[0055]

[0056]

[0057] Example 2: The 4C charging data of the cell under the conditions of 10°C, 25°C, and 45°C are as follows. The five reference electrodes 20 in the experimental comparison 1 group are located at different positions in the same laminated unit 11 of the cell. The number of laminated units in the experimental comparison 2 group is 60. The four reference electrodes 20 in the experimental comparison 2 group are located in the first laminated unit, the 15th laminated unit, the 20th laminated unit, and the 30th laminated unit, respectively. The above four reference electrodes are located at the same position in different layers of the cell:

[0058]

[0059]

[0060] In summary, the data show that by setting multiple reference electrodes, the lithium precipitation boundaries of the battery at different temperatures and different rates at different positions can be stably monitored, and the voltage difference between the negative electrode at the 5th reference electrode of the experimental comparison group 1 and the reference electrode decreases rapidly, which indicates that the rate charging performance at this position is poorer than that at other positions, and the rate charging performance of this position can be improved from the design and process technology, thereby improving the overall rate charging performance of the battery.

[0061] From the above description, it can be seen that the above-mentioned embodiments of the utility model realize the following technical effects: by setting at least two reference electrodes inside the battery, the change of the reference electrode potential of the battery at different temperatures and SOC conditions during charging at a specified rate can be monitored in real time, and then the maximum rate charging capacity upper limit that can be tolerated by different positions of the battery is evaluated through the voltage of the reference electrode without actually disassembling the battery to observe the interface, which can avoid damage to the battery caused by disassembly, so that the battery can remain intact after testing, and can be reused, thereby avoiding resource waste caused by disassembly.

[0062] Obviously, the above-described embodiments are only a part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the utility model.

[0063] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, work, device, component and / or their combinations.

[0064] The above only describes the preferred embodiments of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model.

Claims

1. A lithium battery, characterized by, The lithium battery comprises: an electric core (10) comprising at least one laminated unit (11), the laminated unit (11) comprising a first diaphragm (111) and pole pieces (112) located on both sides of the first diaphragm (111), one of the two pole pieces (112) being a positive pole piece and the other being a negative pole piece; at least two reference electrodes (20); at least two second diaphragms (30) located between the pole pieces (112) and the first diaphragm (111), the at least two reference electrodes (20) being arranged one-to-one with the at least two second diaphragms (30), the reference electrode (20) being located between the second diaphragm (30) corresponding thereto and the first diaphragm (111); when the laminated unit (11) is one, the at least two reference electrodes (20) are all connected with the laminated unit (11), and the at least two reference electrodes (20) are located at different positions of the laminated unit (11); when the laminated unit (11) is at least two, the at least two laminated units (11) are sequentially stacked, the at least two reference electrodes (20) are all connected with any one of the at least two laminated units (11) and located at different positions of the laminated unit (11), or the at least two reference electrodes (20) are respectively connected with different laminated units (11).

2. The lithium battery of claim 1, wherein, The number of the laminated units (11) is N, and each reference electrode (20) is connected with any one of the laminated units (11) between the second laminated unit (11) and the N-2th laminated unit (11), wherein N is a positive integer greater than 2.

3. The lithium battery of claim 1, wherein, The laminated unit (11) is at least two, the at least two laminated units (11) are arranged one-to-one with the at least two reference electrodes (20), and the positions of the at least two reference electrodes (20) on the laminated units (11) corresponding thereto are the same.

4. The lithium battery according to any one of claims 1 to 3, characterized in that, The reference electrode (20) comprises an inserted section and an exposed section, one end of the inserted section is located between the second diaphragm (30) corresponding thereto and the first diaphragm (111), and the exposed section extends out of the electric core (10).

5. The lithium battery of claim 4, wherein, The inserted section is entirely located between the second diaphragm (30) corresponding thereto and the first diaphragm (111).

6. The lithium battery of claim 4, wherein, The length of the second diaphragm (30) is L1, the width of the second diaphragm (30) is W1, the length of the inserted section is L2, the value range of L1 / L2 is 2-3, and the value range of W1 is 3-5 cm.

7. The lithium battery of claim 4, wherein, The lithium battery further comprises a shell having a mounting cavity, the electric core (10) and all the second diaphragms (30) are mounted in the mounting cavity, and the exposed section of each reference electrode (20) is located outside the mounting cavity.

8. The lithium battery according to any one of claims 1 to 3, characterized in that, The lithium battery further comprises at least two connecting tabs, the at least two connecting tabs are arranged one-to-one with the at least two reference electrodes (20), and the connecting tab is connected with the reference electrode (20) corresponding thereto.

9. The lithium battery according to any one of claims 1 to 3, characterized in that, The surface of the reference electrode (20) is provided with a lithium plating layer.

10. The lithium battery according to any one of claims 1 to 3, characterized in that, The first diaphragm (111) and the second diaphragm (30) are made of the same material.

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