Electrode assembly and battery cell

Abstract

The utility model relates to an electrode assembly and a battery monomer. The electrode assembly comprises a main body and a heating sheet arranged in the main body; wherein the heating piece comprises a conductive piece, the conductive piece and the main body are arranged in an insulated mode, and the conductive piece is configured to be capable of heating in an alternating magnetic field; the built-in heating sheet is additionally arranged, and the temperature of the main body is raised by utilizing the electromagnetic induction principle; especially for the main body and the battery monomer with large thickness, the built-in heating sheet can improve the heat transfer efficiency, and enables the temperature distribution at each thickness position in the main body to be more uniform. The heating time is shortened in the working conditions needing heating, such as hot pressing, vacuum baking water removal and low-temperature loading, the manufacturing efficiency is improved, and the service life of the battery monomer is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to an electrode assembly and a battery monomer. Background Art

[0002] With the development of lithium-ion battery technology and changes in user needs, battery cell design is gradually moving towards larger sizes and higher capacities. Highly integrated thick cores face uneven heating during hot pressing during manufacturing. While improved core forming can be achieved by extending preheating or heating times, adding preheating equipment, and adding hot pressing channels, this impacts production efficiency and comes at a high cost. Furthermore, battery cells require vacuum baking to remove water before injection, and heating is also required to improve performance in low-temperature environments. In both the manufacturing and usage scenarios described above, heating thick cores presents challenges such as low heat conduction efficiency and uneven heating. Utility Model Content

[0003] To this end, the technical problem to be solved by the present invention is to overcome the technical difficulties in the existing technology of slow heat conduction and uneven heating of battery cells during hot pressing, baking and dehydration, and heating in low-temperature environments, and to provide an electrode assembly and battery cell that can use electromagnetic induction to quickly heat up and shorten the heating time.

[0004] In the first aspect, in order to solve the above technical problems, the present invention provides an electrode assembly, which includes:

[0005] main body,

[0006] A heating plate, wherein the heating plate is built into the main body;

[0007] The heating plate includes a conductive member, the conductive member is insulated from the main body, and the conductive member is configured to generate heat in an alternating magnetic field.

[0008] In one embodiment of the present invention, the heating plate further includes a heat-conducting insulating member, the heat-conducting insulating member forms a closed cavity, and the conductive member is built into the closed cavity.

[0009] In one embodiment of the present invention, a first hollow area is provided at the middle position of the conductive member.

[0010] In one embodiment of the present invention, the conductive member is provided with a second hollow area, and the second hollow area surrounds the outer side of the first hollow area.

[0011] In one embodiment of the present invention, the thermally conductive insulating member includes a first side plate and a second side plate respectively located on both sides of the closed cavity, and the first side plate and the second side plate are arranged opposite to each other along a first direction; in the first direction, the thickness of the first side plate is a, the thickness of the second side plate is b, and the thickness of the thermally conductive insulating member is c, wherein the value range of c is 0 to 1 mm, and the value range of a and / or b is 0 to 0.5 mm.

[0012] In one embodiment of the present invention, the main body has a first side surface and a second side surface arranged opposite to each other along a first direction, and the heating plate has a third side surface and a fourth side surface arranged opposite to each other along the first direction; in the first direction, the third side surface is closer to the first side surface than the fourth side surface; the distance between the third side surface and the first side surface is d, and the distance between the fourth side surface and the second side surface is e, wherein the value range of d and / or e is 10 mm to 50 mm.

[0013] In one embodiment of the present invention, the heat-conducting insulating member of the heating plate is made of heat-conducting silica gel, and / or the conductive member is an iron sheet.

[0014] In one embodiment of the present invention, the main body is a winding structure having a winding starting circle, and the heating plate is accommodated in the circle of the winding starting circle.

[0015] In one embodiment of the present invention, the main body is provided in plurality, and a heating plate is also provided between two of the main bodies.

[0016] In a second aspect, the present invention further provides a battery cell comprising the electrode assembly described in any one of the above embodiments.

[0017] The above technical solution of the utility model has the following beneficial effects compared with the prior art:

[0018] The electrode assembly and battery cell described in the present invention are additionally provided with a built-in heating plate, which utilizes the principle of electromagnetic induction to heat the main body to increase the temperature; especially for the main body and battery cell with larger thickness, the built-in heating plate can improve the heat transfer efficiency and make the temperature distribution at each thickness point in the main body more uniform; in working conditions requiring heating such as hot pressing, vacuum baking for dehydration, and low-temperature loading, the heating time is shortened, thereby improving manufacturing efficiency and the service life of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the content of the utility model easier to understand, the utility model is further described in detail below based on the specific embodiments of the utility model in conjunction with the accompanying drawings, wherein:

[0020] Figure 1This is a schematic diagram of the cross-sectional structure of an electrode assembly in Example 1 of the present utility model;

[0021] Figure 2 This is a schematic cross-sectional view of the heat-conducting insulating member in the first embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the internal structure of the heating plate in Example 1 of the present utility model;

[0023] Figure 4 This is a schematic diagram of the structure of another electrode assembly in Example 1 of the present utility model.

[0024] Figure 5 This is a schematic diagram of the internal structure of the heating plate in the second embodiment of the present utility model;

[0025] Figure 6 This is a schematic diagram of the internal structure of the heating plate in Example 3 of the present utility model.

[0026] Explanation of the reference numerals in the specification: 1. Main body; 11. First side; 12. Second side; 13. Winding starting circle; 2. Heating plate; 21. Conductive member; 211. First hollow area; 212. Second hollow area; 22. Thermally conductive insulating member; 221. Enclosed cavity; 222. First side panel; 223. Second side panel; 23. Third side; 24. Fourth side. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0028] Example 1

[0029] Reference Figures 1 to 4 As shown, the first embodiment of the present invention provides an electrode assembly, which includes a main body 1 and a heating plate 2 built into the main body 1; the heating plate 2 includes a conductive member 21, which can generate heat in an alternating magnetic field, thereby rapidly heating the main body 1, shortening the heating or preheating time in the hot pressing process, and making the main body 1 in a better molded state; in the baking and dehydration process, the heating plate 2 can reduce the baking time and reduce production costs; in low-temperature working conditions, the heating plate 2 can also maintain the working temperature to prevent low temperatures from affecting the working performance of the electrode assembly. The electrode assembly in the first embodiment of the present invention has a built-in heating plate 2, which has a more uniform heating effect and a higher heat conduction rate than external contact heating structures and water bath heating methods, and can extend the service life of the electrode assembly.

[0030] Specifically, the conductive member 21 cuts the alternating magnetic lines of force of the alternating magnetic field and generates eddy currents. The eddy currents cause the carriers in the conductive member 21 to move irregularly at high speed. The carriers and atoms collide and rub against each other to generate heat energy. The heating plate 2 generates heat and conducts the heat to the main body 1 to heat or maintain the temperature of the electrode assembly.

[0031] Furthermore, the conductive member 21 is insulated from the main body 1 to prevent the main body 1 from directly contacting the conductive member 21 to form an electrical connection, thereby preventing metal corrosion or leakage from causing a safety accident. Figure 2 and Figure 3 As shown, the heating plate 2 further includes a heat-conducting insulating member 22 , wherein the heat-conducting insulating member 22 forms a closed cavity 221 , and the conductive member 21 is built into the closed cavity 221 .

[0032] The thermally conductive insulating member 22 is used to form electrical insulation between the conductive member 21 and the main body 1, and also serves as a heat-conducting medium between the conductive member 21 and the main body 1; preferably, the material of the thermally conductive insulating member 22 is set to thermally conductive silicone, and / or the conductive member 21 is set to an iron sheet; in other embodiments, the conductive member 21 can also be set to a nickel sheet or other thin sheet of a material that can generate heat through electromagnetic induction; the material of the thermally conductive insulating member 22 can also be set to other materials that are resistant to high temperatures, chemical corrosion, and do not react with the main body 1 and the electrolyte according to actual needs.

[0033] It should be noted that the heat-conducting insulating member 22 is coated on the outer periphery of the conductive member 21 to form the closed cavity 221, and the conductive member 21 is tightly fitted to the cavity wall of the closed cavity 221 to avoid the generation of intervals or gaps that affect heat conduction; furthermore, when the thickness of the heat-conducting insulating member 22 at the outer edge of the conductive member 21 is the same, the shape of the heating plate 2 is associated with the shape of the conductive member 21, and in the first direction, the orthographic projection of the heating plate 2 is located inside the main body 1, preferably, with reference to Figure 3 As shown, the heating plate 2 and the conductive member 21 are both configured to be rectangular.

[0034] Further, refer to Figure 2As shown, the thermally conductive insulating member 22 includes a first side plate 222 and a second side plate 223, respectively located on both sides of the enclosed cavity 221. The first side plate 222 and the second side plate 223 are arranged opposite each other along a first direction. In the first direction, the thickness of the first side plate 222 is a, the thickness of the second side plate 223 is b, and the thickness of the thermally conductive insulating member 22 is c, wherein the value range of c is 0-1mm, and the value range of a and / or b is 0-0.5mm. If the thickness of the first side plate 222 and the second side plate 223 in the first direction is too small, the insulation structure is easily damaged, exposing the conductive member 21 and causing leakage. If the thickness in the first direction is too large, the thermal conductivity will be affected. The heat generated by electromagnetic induction of the conductive member 21 will be dissipated excessively during conduction in the thermally conductive insulating member 22, affecting the heating effect of the main body 1. At the same time, excessive thickness will affect space utilization, thereby affecting the energy density of the battery cell where the electrode assembly is located. The value of c may be 0.3 mm, 0.5 mm, 0.8 mm, or 0.9 mm; the value of a and / or b may be 0.2 mm, 0.3 mm, or 0.4 mm.

[0035] It should be noted that the thermally conductive insulating member 22 also includes a third side plate and a fourth side plate respectively located on both sides of the second direction of the closed cavity 221. The thickness of the third side plate and / or the thickness of the fourth side plate is greater than or equal to 1 mm. Specifically, the thickness of the third side plate and / or the thickness of the fourth side plate can be 1.2 mm or 1.5 mm or 1.7 mm or 2 mm or 2.3 mm or 2.6 mm or 2.8 mm or 3 mm.

[0036] Furthermore, in order to ensure that the conductive member is located within the alternating magnetic field, refer to Figure 1As shown, the main body 1 has a first side surface 11 and a second side surface 12 disposed opposite each other along a first direction, and the heating plate 2 has a third side surface 23 and a fourth side surface 24 disposed opposite each other along the first direction. In the first direction, the third side surface 23 is closer to the first side surface 11 than the fourth side surface 24. The distance between the third side surface 23 and the first side surface 11 is d, and the distance between the fourth side surface 24 and the second side surface 12 is e, wherein the value range of d and / or e is 10mm to 50mm. The heating control plate for generating an alternating magnetic field is located on the first side surface 11 and the second side surface 12, and the electromagnetic heating power is set to 100W to 5000W. If the values ​​of distance d and distance e are too small, the distance between the heating plate 2 and the heating control plate is small, the heat conduction time is shortened, and the heating temperature is higher. When the temperature is too high, it is easy to cause the diaphragm to shrink, accelerate the aging of the electrode assembly material, and accelerate the decomposition of the electrolyte and the corrosion of the electrode material, which is not conducive to the service life of the electrode assembly. When the distance d and the distance e are too large, the heat conduction path is too long, and the heating effect of the main body 1 on both sides of the first direction is poor, which can easily lead to uneven overall temperature.

[0037] Among them, parameters such as the values ​​of distance d and distance e, the heating power of the heating control plate, the heating time and the heating interval time can be calculated based on the thermal conductivity and specific heat capacity of the battery cell where the electrode assembly is located. Specifically, the values ​​of d and / or e can be 15mm or 20mm or 25mm or 30mm or 35mm or 40mm or 45mm.

[0038] Preferably, a=b and a+b<c, d=e are set; the first side plate 222 and the second side plate 223 are symmetrically arranged on both sides of the first direction of the conductive member 21, and the heating plate 2 is built into the middle part of the main body 1 along the first direction, so that the heat of the conductive member 21 can be evenly conducted to the main body 1 through the thermally conductive insulating member 22, thereby reducing the temperature difference among various parts of the main body 1.

[0039] In some embodiments, the main body 1 has a group, and the heating plate 2 is built into the main body 1. The main body 1 can be set as a laminated structure or a winding structure. When the main body 1 is set as a laminated structure, it is stacked along the first direction, and the heating plate 2 is located in the middle of the stacked structure. When the main body 1 is a winding structure, refer to Figure 1 As shown, the winding structure has a winding starting circle 13 , and the heating sheet 2 is accommodated in the circle of the winding starting circle 13 .

[0040] In some embodiments, reference Figure 4As shown, the main body 1 is provided with a plurality of heating plates 2 , and the interval between two adjacent main bodies 1 is provided with the heating plate 2 , or the heating plate 2 is provided between two adjacent main bodies 1 and in each main body 1 .

[0041] Example 2

[0042] Reference Figure 5 As shown, the second embodiment of the present invention provides an electrode assembly. The difference between the electrode assembly in the second embodiment and the first embodiment is that a first hollow area 211 is provided at the middle position of the conductive member 21 .

[0043] Preferably, the first hollow area 211 is located at the center of the conductive member 21 to prevent the middle area of ​​the main body 1 from being too hot during heating.

[0044] In some embodiments, the conductive member 21 is configured to be rectangular, the first hollow area 211 is configured to be rectangular, and the length of the first hollow area 211 is 10% of the length of the conductive member 21, and the width of the first hollow area 211 is 9% to 10% of the width of the conductive member 21; when the area of ​​the first hollow area 211 is too small or too large, it cannot achieve the effect of balancing the temperature of various parts of the main body 1.

[0045] In some embodiments, the first hollow area 211 can be scaled down in proportion to the shape of the conductive element 21 , or can be set to other shapes different from the conductive element 21 , including but not limited to rectangular, circular, or irregular shapes.

[0046] Example 3

[0047] Reference Figure 6 As shown, embodiment three of the present invention provides an electrode assembly. The only difference between the electrode assembly described in embodiment three and embodiment two is that the conductive member 21 is further provided with a second hollow area 212, and the second hollow area 212 surrounds the outside of the first hollow area 211; the second hollow area 212 can be provided with one or more groups, and the second hollow area 212 can proportionally enlarge the outer edge of the first hollow area 211 with the center of the conductive member 21 as the base point, or the second hollow area 212 can also be set to other shapes.

[0048] Comparative Example 1

[0049] This comparative example provides an electrode assembly, which includes a main body 1. The electrode assembly is not provided with a heating plate 2.

[0050] Application and performance characterization

[0051] Hot press tests were conducted on Examples 1-3 and Comparative Example 1 to characterize their heating performance. The heating plate 2 described in Examples 1-3 was embedded within the starting coil of the wound structure of the main body 1. The first direction was defined as the thickness direction of the main body 1; the main body 1 had a thickness of 20 mm, a width of 150 mm, and a height of 110 mm. The main body 1 had a wound structure with 50 cathode layers and 52 anode layers. The separator was a 14 μm thick PP film. A coating layer with a thickness of 3 μm and made of PVDF adhesive was provided on both sides of the separator in the thickness direction.

[0052] The heating plate 2 in Example 1 has a length of 115 mm, a width of 110 mm, and a thickness in the first direction of 0.5 mm; the conductive member 21 has a length of 110 mm, a width of 105 mm, and a thickness of 0.3 mm; the heating plate 2 in Example 2 differs from the heating plate 2 in Example 1 only in the first hollow area 211, which is located in the center and has a length of 11 mm and a width of 10 mm; the heating plate 2 in Example 3 differs from the heating plate 2 in Example 2 only in the second hollow area 212, which includes two groups of second hollow areas 212, and the conductive member 21 and the second hollow area 212 are arranged at equal widths in the diagonal direction of the heating plate 2.

[0053] Positions 1#, 2#, and 3# are set in the main body 1 for characterizing the heating effect; wherein, the orthographic projection of position 1# along the first direction is located at the center of the first side surface 11, the orthographic projection of position 3# along the first direction is located at one of the four vertices of the first side surface 11, and the orthographic projection of position 2# along the first direction on the first side surface 11 is located at the midpoint of the line connecting the projections of positions 1# and 3#. The following heating procedure is performed on Examples 1 to 3 and Comparative Example 1, and the heating effect is characterized by the temperatures inside the main body at positions 1#, 2#, and 3#;

[0054] Wherein, the heating schedule of comparative example 1 is:

[0055] After preheating at 90°C for 20 minutes, hot press at 90°C with a surface pressure of 3 MPa for 240 seconds;

[0056] The heating procedures for the electrode assembly in Examples 1 to 3 are as follows:

[0057] The heating power is 1000W and the heating is continued for 5s, and the heating is allowed to stand for 5s. Then the heating power is 500W and the heating is continued for 5s and the heating is allowed to stand for 5s until the hot pressing is completed. The surface pressure is 3MPa at 90℃ and the hot pressing is performed for 140s. When the hot pressing plate is pressed down, the electromagnetic heating program is started to make the heating plate 2 work synchronously.

[0058] In the characterization of the heating effect, the hot pressing effect includes the adhesion effect between the diaphragm and the electrode. When the adhesion effect of the diaphragm between the layers is good, the temperature detection of the 1# position, 2# position and 3# position is performed; among them, the 1# position, 2# position and 3# position of the comparative example 1 are detected at the thickness of the middle layer of the main body, and the 1# position, 2# position and 3# position of the examples 1 to 3 are detected at the thickness of 1 / 4 layer of the main body; the above test results are shown in the following table:

[0059] Table 1 Performance test results

[0060]

[0061]

[0062] As can be seen from the above table, after the conductive member 21 is hollowed out, the temperature inside the main body 1 is more uniform when heated. When the 3# position is heated to 70°C, the temperature at other temperature detection positions is closer to 70°C. Preferably, the conductive member 21 is provided with the first hollow area 211 and the second hollow area 212 for balancing the temperature.

[0063] Example 4

[0064] A fourth embodiment of the present invention provides a battery cell, which includes any one of the electrode assemblies in the first to third embodiments.

[0065] During the manufacturing process of battery cells, in order to reduce the offset of the pole pieces and the changes in the shape and size of the main body in the assembly process, they will be hot-pressed in advance. A preheating process will also be set according to the thickness and area differences. The inventors of this case have found that when the preheating temperature is constant, the thicker the main body is, the longer it takes for its center temperature to reach the target temperature; especially for the main body 1 with a larger thickness, the upper and lower pressure plates transfer heat to the inside from the first side 11 and the second side 12 of the main body 1 during hot pressing, so the time is long and the internal temperature is uneven; the embodiment of the utility model adds a heating plate 2 inside the main body 1 or at the interval between adjacent main bodies 1, which can not only eliminate the preheating process and save a lot of preheating equipment, but also greatly shorten the hot pressing time, reduce the number of hot pressing channels, reduce power consumption, and control production costs.

[0066] In addition, the battery requires vacuum baking to remove water before filling. The baking process uses external heating, which also results in slow heat conduction and a long baking time. The heating plate 2 can cooperate with the baking equipment to improve heat conduction and shorten the baking time. If the electrode assembly encounters low temperature conditions during loading and transportation, the heating plate 2 can also improve the working state, avoid uneven heating during water bath heating, and shorten the heating time.

[0067] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. An electrode assembly, characterized in that: include, Subject (1); A heating plate (2), the heating plate (2) being built into the main body (1); The heating plate (2) comprises a conductive member (21), the conductive member (21) and the main body (1) are insulated, and the conductive member (21) is configured to generate heat in an alternating magnetic field.

2. The electrode assembly according to claim 1, wherein: The heating plate (2) further comprises a heat-conducting insulating member (22), wherein the heat-conducting insulating member (22) forms a closed cavity (221), and the conductive member (21) is built into the closed cavity (221).

3. The electrode assembly according to claim 1, wherein: A first hollow area (211) is provided at the middle position of the conductive member (21).

4. The electrode assembly according to claim 3, wherein: The conductive member (21) is provided with a second hollow area (212), and the second hollow area (212) surrounds the outside of the first hollow area (211).

5. The electrode assembly according to claim 2, wherein: The heat-conducting insulating member (22) comprises a first side plate (222) and a second side plate (223) respectively located on both sides of the closed cavity (221), wherein the first side plate (222) and the second side plate (223) are arranged relative to each other along a first direction; in the first direction, the thickness of the first side plate (222) is a, the thickness of the second side plate (223) is b, and the thickness of the heat-conducting insulating member (22) is c, wherein the value range of c is 0 to 1 mm, and the value range of a and / or b is 0 to 0.5 mm.

6. The electrode assembly according to any one of claims 1 to 5, characterized in that: The main body (1) has a first side surface (11) and a second side surface (12) arranged opposite to each other along a first direction, and the heating plate (2) has a third side surface (23) and a fourth side surface (24) arranged opposite to each other along the first direction; in the first direction, the third side surface (23) is closer to the first side surface (11) than the fourth side surface (24); the distance between the third side surface (23) and the first side surface (11) is d, and the distance between the fourth side surface (24) and the second side surface (12) is e, wherein the value range of d and / or e is 10 mm to 50 mm.

7. The electrode assembly according to claim 6, wherein: The heat-conducting insulating member (22) of the heating plate (2) is made of heat-conducting silica gel, and / or the conductive member (21) is an iron sheet.

8. The electrode assembly according to any one of claims 1 to 5, characterized in that: The main body (1) is a winding structure having a winding starting circle (13), and the heating plate (2) is accommodated in the circle of the winding starting circle (13).

9. The electrode assembly according to any one of claims 1 to 5, characterized in that: It also includes a plurality of main bodies (1), and a heating plate (2) is also provided between two main bodies (1).

10. A battery cell, characterized in that: The electrode assembly comprises the electrode assembly according to any one of claims 1 to 9.

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