Top sealing tool, battery cell and battery pack

Abstract

The invention relates to the technical field of battery cells, and discloses a top sealing tool, a battery cell and a battery pack, and the top sealing tool comprises a supporting plate and a pressing plate. The distance h between the top surface of the supporting plate and the bottom surface of the pressing plate is larger than or equal to 2a1 (1-Xmax) + 2a2, so that the distance between the top surface of the supporting plate and the bottom surface of the pressing plate can be prevented from being too small during heat sealing, the total thickness of two layers of packaging films after heat sealing can be guaranteed, the packaging films are prevented from being over-melted due to overpressure, the bonding force between a PP layer and a non-PP layer of the packaging films can be guaranteed, and the packaging effect of the packaging films is improved. The PP layer and the non-PP layer are prevented from being stripped in the use process of the battery cell, and the sealing performance of the tab of the battery cell can be ensured; and meanwhile, h is smaller than or equal to 2a1 (1-Xmin) + 2a2, so that the distance between the top surface of the supporting plate and the bottom surface of the pressing plate during heat sealing can be prevented from being too large, the thickness of the two layers of packaging films after heat sealing can be prevented from being too large, sufficient hot pressing of the packaging films can be ensured, insufficient hot pressing strength can be avoided, the packaging strength between the two layers of packaging films after heat sealing can be ensured, and the service life of the packaging films can be prolonged. And the sealing performance of the tab of the battery cell can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of battery cells, and in particular to a top sealing tool, a battery cell and a battery pack. Background Art

[0002] The soft-pack battery cell includes an electrode group and a packaging film. The packaging film is used to package and protect the electrode group. During the assembly process of the packaging film and the electrode group, a receiving groove is first punched at a specified position of the packaging film, the electrode group is placed in the receiving groove, and then the packaging film is folded and heat-sealed to complete the packaging of the electrode group.

[0003] During the top sealing process of the battery cell, a top sealing tool is used. The top sealing tool includes a support plate and a pressure plate. First, the packaging edge of the battery cell is placed on the support plate, and the pressure plate moves downward to press the packaging edge of the battery cell. The pressure plate generates heat to complete the pressing of the packaging edge. During the heat sealing process, the heat pressing process is controlled by controlling the downward stroke of the pressure plate. If the pressure plate descends too far, it is easy to cause overpressure, causing the packaging film to melt, affecting the sealing of the battery cell; if the pressure plate descends insufficiently, the packaging film cannot be fully hot-pressed, the packaging film is not fully hot-melted, the packaging strength is insufficient, and the packaging film is prone to cracking during subsequent use, which also affects the sealing of the battery cell. Summary of the invention

[0004] In view of this, the present invention provides a top sealing tool, a battery cell and a battery pack to solve the problem that the top sealing tool in the prior art is prone to overpressure and overmelting or insufficient hot pressure strength during heat sealing, thereby affecting the sealing of the battery cell.

[0005] In a first aspect, the present invention provides a top sealing tool, comprising:

[0006] Support plate;

[0007] A pressing plate, suitable for being pressed onto the top of the support plate; a limiting boss is provided on at least one side of the length direction of one of the top surface of the support plate and the bottom surface of the pressing plate, and a limiting groove is provided on the other of the top surface of the support plate and the bottom surface of the pressing plate. During heat sealing, the packaging film, the pole ear and the insulating member of the battery cell are suitable to be arranged between the support plate and the pressing plate. When the step surface of the limiting boss abuts against the bottom of the limiting groove, the spacing between the top surface of the support plate and the bottom surface of the pressing plate suitable for being pressed onto the butt joint area of ​​the two layers of packaging film is h. The packaging film includes a PP layer and a non-PP layer. The deformation rate of the PP layer is X, 60%≤X≤80%, the maximum value of X is Xmax, and the minimum value of X is Xmin. The thicknesses of the PP layer and the non-PP layer are a1 and a2, respectively, 2a1(1-Xmax)+2a2≤h≤2a1(1-Xmin)+2a2; the unit of h, a1, and a2 is μm.

[0008] Beneficial effects: When the top-sealing tooling of this structure is in use, first place the encapsulation edge of the battery cell on the support plate, and the pressing plate moves downward and presses above the encapsulation edge. The limiting boss contacts the bottom of the limiting groove, and the limiting boss slides along the groove wall of the limiting groove, which can position the pressing plate and guide the pressing plate to descend, avoiding large misalignment between the pressing plate and the support plate due to the error in alignment along the length direction of the battery cell, facilitating the positioning and pressing of the pressing plate and the support plate, and preventing over-pressing or cracking of the encapsulation film caused by misalignment. After the bottom of the limiting groove contacts the end face of the limiting boss, the pressing plate stops pressing down, and the limiting boss limits the pressing plate, which can accurately control the pressing stroke of the pressing plate; the tab of the battery cell is provided on at least one side of the encapsulation film, and the two layers of encapsulation film on both sides of the tab are butted and heat-pressed to form a seal. After the pressing plate descends in place, the distance between the top surface of the support plate and the bottom surface of the pressing plate determines the thickness of the two layers of encapsulation film on both sides of the tab. 2a1(1 - X) + 2a2 is the total thickness of the two layers of encapsulation film after heat sealing, 2a1(1 - Xmin) + 2a2 is the maximum value of the total thickness of the two layers of encapsulation film after heat sealing, and 2a1(1 - Xmax) + 2a2 is the minimum value of the total thickness of the two layers of encapsulation film after heat sealing. By making the distance h between the top surface of the support plate and the bottom surface of the pressing plate satisfy h ≥ 2a1(1 - Xmax) + 2a2, that is, h is greater than or equal to the minimum value of the total thickness of the two layers of encapsulation film after heat sealing, this can prevent the distance between the top surface of the support plate and the bottom surface of the pressing plate from being too small during heat sealing, ensure the total thickness of the two layers of encapsulation film after heat sealing, avoid over-pressing resulting in over-melting of the encapsulation film, ensure the bonding force between the PP layer and the non-PP layer of the encapsulation film, avoid peeling between the PP layer and the non-PP layer during the use of the battery cell, and ensure the sealing performance at the tab of the battery cell; at the same time, h satisfies h ≤ 2a1(1 - Xmin) + 2a2. Such a setting can prevent the distance between the top surface of the support plate and the bottom surface of the pressing plate from being too large during heat sealing, prevent the thickness of the two layers of encapsulation film after heat sealing from being too large, ensure sufficient heat pressing of the encapsulation film, avoid insufficient heat pressing strength, ensure the encapsulation strength between the two layers of encapsulation film after heat sealing, and ensure the sealing performance at the tab of the battery cell.

[0009] In an optional embodiment, the length of the outer end face of the limiting boss extending along the length direction of the top-sealing tooling is L, and the width of the outer end face of the limiting boss extending along the width direction of the top-sealing tooling is W, 3mm ≤ L ≤ 50mm, 3mm ≤ W ≤ 50mm.

[0010] Beneficial effects: Such a setting can control the size of the limiting boss within a suitable range, ensure the strength of the limiting boss, thereby ensuring its guiding and positioning effects, being beneficial to effectively heat-sealing the encapsulation film, and ensuring the sealing performance.

[0011] In an alternative embodiment, the limiting bosses are provided at both ends of the support plate in the length direction, and the limiting grooves are provided at both ends of the pressing plate in the length direction; the surface of the limiting boss facing the inside of the support plate is a first inclined surface, and the side wall of the limiting groove is a second inclined surface. During heat sealing, the second inclined surface is pressed against the first inclined surface.

[0012] In an alternative embodiment, the angle between the first inclined surface and the top surface of the limiting boss is K, and 100° ≤ K ≤ 160°.

[0013] Beneficial effects: The inclination angle of the first inclined surface is moderate, and the guiding effect is good. It can effectively guide the pressing plate to press down, which is beneficial to ensuring the positioning accuracy and the packaging quality after heat sealing.

[0014] In an alternative embodiment, during heat sealing, the vertical height of the fitting area between the first inclined surface and the second inclined surface is e, and 1 mm ≤ e ≤ 50 mm.

[0015] Beneficial effects: The vertical height of the fitting area between the first inclined surface and the second inclined surface is moderate, which can prevent the inclination angles of the two inclined surfaces from being too large or too small, prevent the two inclined surfaces from approaching the horizontal or vertical state, ensure the guiding and positioning effect of the inclined surfaces, and facilitate the positioning and docking of the pressing plate and the support plate.

[0016] In an alternative embodiment, relief grooves are provided on the support plate and the pressing plate inside the limiting bosses. A first plane extending in the same direction as the top surface of the support plate is provided on the support plate between the relief groove and the first inclined surface, and a second plane extending in the same direction as the bottom surface of the pressing plate is provided on the pressing plate between the relief groove and the second inclined surface. During heat sealing, the distance between the first plane and the second plane is f, and 0.5 mm ≤ f ≤ 50 mm.

[0017] Beneficial effects: During heat sealing, the second plane and the first plane are arranged at a certain distance from each other, preventing the second plane from contacting the first plane before the top surface of the limiting boss contacts the bottom of the limiting groove, avoiding the pressing plate from being padded empty, ensuring that the pressing plate presses down in place, and effectively ensuring the pressing effect on the packaging film.

[0018] In an alternative embodiment, the thickness of the single-layer packaging film is h1, and 0.08 mm ≤ h1 ≤ 1 mm;

[0019] and / or, 50 μm ≤ a1 ≤ 200 μm;

[0020] and / or, 30 μm ≤ a2 ≤ 800 μm.

[0021] In an alternative embodiment, the encapsulation film outside the insulating member bulges outward to form a protruding portion, the width of the protruding portion is b1, and ear avoiding grooves are provided on the support plate and the pressing plate. During heat sealing, the protruding portion is located within the ear avoiding groove, the width of the ear avoiding groove is b2, and 0.97 ≤ b2 / b1 ≤ 1.1.

[0022] Beneficial effects: By setting the width of the ear avoiding groove within a suitable range, it is possible to prevent excessive glue overflow at both ends of the ear after hot pressing, and at the same time ensure the hot pressing effect of the encapsulation film and the insulating member at the transition surface of the protruding portion, thereby ensuring the sealing performance at the ear.

[0023] In a second aspect, the present invention also provides an electric core which is top-sealed and encapsulated using the top-sealing tooling described in any one of the above.

[0024] Beneficial effects: For the electric core with this structure, during encapsulation, first place the encapsulation edge of the electric core on the support plate, and the pressing plate moves downward to press against the upper side of the encapsulation edge. The limiting boss slides along the groove wall of the limiting groove, which can position the pressing plate and guide the pressing plate to descend, facilitating the positioning and pressing of the pressing plate and the support plate, and preventing over-pressing or cracking of the encapsulation film due to misalignment. After the bottom of the limiting groove contacts the end face of the limiting boss, the pressing plate stops pressing down, and the pressing plate is limited by the limiting boss, which can accurately control the pressing stroke of the pressing plate. By making the distance h between the top surface of the support plate and the bottom surface of the pressing plate satisfy h ≥ 2a1(1 - Xmax) + 2a2, this can prevent the distance between the top surface of the support plate and the bottom surface of the pressing plate from being too small during heat sealing, ensure the total thickness of the two encapsulation films after heat sealing, avoid over-melting of the encapsulation film due to over-pressing, ensure the bonding force between the PP layer and the non-PP layer of the encapsulation film, avoid peeling between the PP layer and the non-PP layer during the use of the electric core, and ensure the sealing performance at the ear of the electric core; at the same time, h satisfies h ≤ 2a1(1 - Xmin) + 2a2, such a setting can prevent the distance between the top surface of the support plate and the bottom surface of the pressing plate from being too large during heat sealing, prevent the thickness of the two encapsulation films from being too large after heat sealing, ensure sufficient heat pressing of the encapsulation film, avoid insufficient heat pressing strength, ensure the encapsulation strength between the two encapsulation films after heat sealing, and ensure the sealing performance at the ear of the electric core.

[0025] In a third aspect, the present invention also provides a battery pack including the above-mentioned electric core. The battery pack includes an electric core and has the same technical effects as the electric core, which will not be elaborated here. Description of the Drawings

[0026] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 The front view of a top-sealing tooling for an embodiment of the present invention;

[0028] Figure 2 For Figure 1 The front view of the middle support plate;

[0029] Figure 3 For Figure 1 The front view of the middle pressing plate;

[0030] Figure 4 For Figure 1 The top view of the middle support plate;

[0031] Figure 5 The cross-sectional view of a packaging film in a battery cell for an embodiment of the present invention;

[0032] Figure 6 For Figure 1 The top view of the top-sealing tooling during hot-press packaging in cooperation with the battery cell as shown;

[0033] Figure 7 For Figure 6 The cross-sectional view in the A-A direction;

[0034] Figure 8 For Figure 7 The partial enlarged view of part A;

[0035] Figure 9 For Figure 1 The three-dimensional structural schematic diagram of the top-sealing tooling during hot-press packaging in cooperation with the battery cell as shown;

[0036] Figure 10 For Figure 1 The exploded view of the top-sealing tooling and the battery cell as shown;

[0037] Figure 11 The three-dimensional structural schematic diagram of the battery cell tab.

[0038] Explanation of the reference numerals:

[0039] 1. Top sealing tooling; 11. Support plate; 111. Limiting boss; 1111. First inclined surface; 112. Avoidance groove; 113. First plane; 114. Tab avoidance groove; 12. Pressure plate; 121. Limiting groove; 1211. Second inclined surface; 122. Second plane; 2. Battery cell; 21. Encapsulation film; 211. PP layer; 212. Non-PP layer; 22. Tab; 23. Insulating part. Detailed implementation manners

[0040] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0041] In the related art, a top sealing tooling 1 is used to perform top sealing on a battery cell 2. The top sealing tooling 1 includes a support plate 11 and a pressure plate 12. During the top sealing process, first, the encapsulation edge of the battery cell 2 is placed on the support plate 11, and the pressure plate 12 moves downward to press against the encapsulation edge of the battery cell 2. The pressure plate 12 generates heat to complete the pressing of the encapsulation edge. During the heat sealing process, the heat pressing process is controlled by controlling the downward stroke of the pressure plate 12. If the downward distance of the pressure plate 12 is too large, it is easy to cause overpressure, resulting in overmelting of the encapsulation film 21, affecting the bonding force between the PP layer 211 and the non-PP layer 212 of the encapsulation film, causing sealing failure at the tab 22, and affecting the sealing performance of the battery cell 2; if the downward distance of the pressure plate 12 is insufficient, the encapsulation film 21 cannot be fully heat pressed, the encapsulation film 21 is not sufficiently melted, the encapsulation strength is insufficient, and the encapsulation film 21 is prone to cracking during subsequent use, which will also affect the sealing performance of the battery cell 2.

[0042] The following will be combined with Figures 1 to 11 , to describe the embodiments of the present invention.

[0043] According to an embodiment of the present invention, on the one hand, a top-sealing tooling 1 is provided, which includes a support plate 11 and a pressing plate 12. Among them, the pressing plate 12 is adapted to be pressed above the support plate 11; at least one side in the length direction of one of the top surface of the support plate 11 and the bottom surface of the pressing plate 12 is provided with a limiting boss 111, and the other of the top surface of the support plate 11 and the bottom surface of the pressing plate 12 is provided with a limiting groove 121. During heat sealing, the packaging film 21, the tab 22 and the insulating member 23 of the battery cell 2 are adapted to be arranged between the support plate 11 and the pressing plate 12. When the step surface of the limiting boss 111 abuts against the bottom of the limiting groove 121, the distance between the top surface of the support plate 11 and the bottom surface of the pressing plate 12, which is suitable for pressing between the two layers of packaging film docking areas, is h. The packaging film 21 includes a PP layer 211 and a non-PP layer 212. The deformation rate of the PP layer 211 is X, 60% ≤ X ≤ 80%. The maximum value of X is Xmax, and the minimum value of X is Xmin. The thicknesses of the PP layer 211 and the non-PP layer 212 are a1 and a2 respectively, and 2a1(1 - Xmax) + 2a2 ≤ h ≤ 2a1(1 - Xmin) + 2a2; the units of h, a1, and a2 are μm.

[0044] When the top-sealing tooling 1 of this structure is in use, first place the encapsulation edge of the battery cell 2 on the support plate 11, move the pressing plate 12 downward to press on the upper side of the encapsulation edge, the limiting boss 111 contacts the bottom of the limiting groove 121, and the limiting boss 111 slides along the groove wall of the limiting groove 121, which can position the pressing plate 12 and guide the pressing plate 12 to descend, avoiding a large misalignment between the pressing plate 12 and the support plate 11 due to the error in the alignment along the length direction of the battery cell 2, facilitating the positioning and pressing of the pressing plate 12 and the support plate 11, and preventing overpressure or cracking of the encapsulation film 21 caused by misalignment. After the bottom of the limiting groove 121 contacts the end face of the limiting boss 111, the pressing plate 12 stops pressing down, and the pressing plate 12 is limited by the limiting boss 111, which can accurately control the pressing stroke of the pressing plate 12; the tab 22 of the battery cell 2 is provided on at least one side of the encapsulation film 21, and the two layers of the encapsulation film 21 on both sides of the tab 22 are butted and heat-pressed to form a seal. After the pressing plate 12 descends in place, the distance between the top surface of the support plate 11 that presses on the butting area of the two layers of the encapsulation film 21 and the bottom surface of the pressing plate 12 determines the thickness of the two layers of the encapsulation film 21 on both sides of the tab 22. 2a1(1 - X) + 2a2 is the total thickness of the two layers of the encapsulation film 21 after heat-sealing, 2a1(1 - Xmin) + 2a2 is the maximum value of the total thickness of the two layers of the encapsulation film 21 after heat-sealing, 2a1(1 - Xmax) + 2a2 is the minimum value of the total thickness of the two layers of the encapsulation film 21 after heat-sealing. When the deformation rate X of the PP layer 211 satisfies 60% ≤ X ≤ 80%, it can ensure that the encapsulation film 21 has good sealing performance. By making the distance h between the top surface of the support plate 11 and the bottom surface of the pressing plate 12 satisfy h ≥ 2a1(1 - Xmax) + 2a2, that is, h is greater than or equal to the minimum value of the total thickness of the two layers of the encapsulation film 21 after heat-sealing, this can prevent the distance between the top surface of the support plate 11 and the bottom surface of the pressing plate 12 from being too small during heat-sealing, ensure the total thickness of the two layers of the encapsulation film 21 after heat-sealing, avoid overpressure causing the encapsulation film 21 to over-melt, ensure the bonding force between the PP layer 211 and the non-PP layer 212 of the encapsulation film, avoid the peeling of the PP layer 211 and the non-PP layer 212 during the use of the battery cell 2, and ensure the sealing performance at the tab 22 of the battery cell 2; at the same time, h satisfies h ≤ 2a1(1 - Xmin) + 2a2, such a setting can prevent the distance between the top surface of the support plate 11 and the bottom surface of the pressing plate 12 from being too large during heat-sealing, prevent the thickness of the two layers of the encapsulation film 21 after heat-sealing from being too large, ensure sufficient heat-pressing of the encapsulation film 21, avoid insufficient heat-pressing strength, ensure the encapsulation strength between the two layers of the encapsulation film 21 after heat-sealing, and ensure the sealing performance at the tab 22 of the battery cell 2.

[0045] Design battery cells with different PP layer thicknesses a1 and different non-PP layer 212 thicknesses a2, as well as top-sealing tooling with different h values. Use the top-sealing tooling to encapsulate the battery cells, and then conduct vibration tests on the encapsulated battery cells to observe the state of the battery cells. The test results are shown in Table 1.

[0046] Table 1

[0047]

[0048] As can be seen from Examples 1 to 9, when the distance h between the top surface of the top-sealing tooling support plate 11 and the bottom surface of the pressing plate 12 satisfies (1 - Xmax) + 2a2 ≤ h ≤ 2a1(1 - Xmin) + 2a2, the state of the battery cell is good after encapsulation and vibration testing; as can be seen from Comparative Example 1, Comparative Example 3 and Comparative Example 5, when h > 2a1(1 - Xmin) + 2a2, the distance between the top surface of the support plate 11 pressed at the docking area of the two-layer encapsulation film 21 and the bottom surface of the pressing plate 12 is too large, and it is impossible to effectively thermally press the encapsulation film 21. After heat sealing, the encapsulation strength between the two-layer encapsulation film 21 is insufficient and the sealing is poor. After the battery cell is vibration tested, the battery cell is short-circuited, and liquid leakage occurs due to peeling between the two-layer encapsulation film at the plastic-sealed part of the encapsulation film; as can be seen from Comparative Example 2, Comparative Example 4 and Comparative Example 6, when h < (1 - Xmax) + 2a2, the distance between the top surface of the support plate 11 pressed at the docking area of the two-layer encapsulation film 21 and the bottom surface of the pressing plate 12 is too small, which will result in a smaller total thickness of the two-layer encapsulation film 21 after heat sealing, the encapsulation film is over-melted, the battery cell sealing is poor, and after the battery cell is vibration tested, the PP layer and the non-PP layer at the plastic-sealed part of the encapsulation film are peeled off and liquid leaks.

[0049] During heat sealing, the limit boss 111 is pressed. If the size of the limit boss 111 is too small, it is easily deformed under pressure, which will affect the guiding and positioning accuracy of the limit boss 111 and it is difficult to ensure the thickness of the encapsulation film 21 after heat sealing; if the size of the limit boss 111 is too large, it will cause waste of materials and space. As Figure 4 shown, in some embodiments, the outer end surface of the limit boss 111 is rectangular, and the length of the outer end surface of the limit boss 111 extending along the length direction of the top-sealing tooling 1 ( Figure 9 the width direction in Figure 9 ) is L, and the width of the outer end surface of the limit boss 111 extending along the width direction of the top-sealing tooling 1 ( the length direction in

[0050] ) is W, 3 mm ≤ L ≤ 50 mm, 3 mm ≤ W ≤ 50 mm. Such a setting can control the size of the limit boss 111 within a suitable range, ensure the strength of the limit boss 111, thereby ensuring its guiding and positioning effects, being beneficial to effectively heat-sealing the encapsulation film 21, and ensuring the sealing performance.

[0050] As Figure 1 and Figure 2As shown, in some embodiments, the limiting bosses 111 are provided at both ends of the support plate 11 in the length direction, and the limiting grooves 121 are provided at both ends of the pressing plate 12 in the length direction; the surface of the limiting boss 111 facing the inside of the support plate 11 is a first inclined surface 1111, and the side wall of the limiting groove 121 is a second inclined surface 1211. During heat sealing, the second inclined surface 1211 is pressed against the first inclined surface 1111. When the pressing plate 12 is pressed down, the second inclined surface 1211 slides along the first inclined surface 1111 to play a guiding role, facilitating the docking of the pressing plate 12 and the support plate 11, ensuring that the pressing plate 12 is centered, and thus ensuring the positioning accuracy and the packaging quality after heat sealing.

[0051] As Figure 2 shown, in some embodiments, the included angle between the first inclined surface 1111 and the top surface of the limiting boss 111 is K, where 100° ≤ K ≤ 160°. The inclination angle of the first inclined surface 1111 is appropriate, and the guiding effect is good, which can effectively guide the pressing plate 12 to press down, thus facilitating ensuring the positioning accuracy and the packaging quality after heat sealing.

[0052] As Figure 8 shown, in some embodiments, during heat sealing, the vertical height of the fitting area between the first inclined surface 1111 and the second inclined surface 1211 is e, where 1 mm ≤ e ≤ 50 mm. The vertical height of the fitting area between the first inclined surface 1111 and the second inclined surface 1211 is appropriate, which can prevent the inclination angles of the two inclined surfaces from being too large or too small, prevent the two inclined surfaces from approaching the horizontal or vertical state, ensure the guiding and positioning effect of the inclined surfaces, and facilitate the positioning and docking of the pressing plate 12 and the support plate 11.

[0053] As Figure 8 shown, in some embodiments, the longitudinal sections of the limiting bosses 111 and the limiting grooves 121 are right trapezoids. Avoidance grooves 112 are provided on the support plate 11 and the pressing plate 12 inside the limiting bosses 111. A first plane 113 extending in the same direction as the top surface of the support plate 11 is provided on the support plate 11 between the avoidance groove 112 and the first inclined surface 1111, and a second plane 122 extending in the same direction as the bottom surface of the pressing plate 12 is provided on the pressing plate 12 between the avoidance groove 112 and the second inclined surface 1211. During heat sealing, the distance between the first plane 113 and the second plane 122 is f, where 0.5 mm ≤ f ≤ 50 mm. That is, during heat sealing, the second plane 122 and the first plane 113 are arranged at a certain distance from each other to prevent the second plane 122 from contacting the first plane 113 before the top surface of the limiting boss 111 touches the bottom of the limiting groove 121, avoiding the pressing plate 12 from being lifted, ensuring that the pressing plate 12 is pressed down in place, and thus effectively ensuring the pressing effect on the packaging film 21.

[0054] If the thickness of the single-layer packaging film 21 is too thin, the packaging strength will be affected. If the thickness of the single-layer packaging film 21 is too thick, it will cause waste of materials. In some embodiments, as Figure 5As shown, the thickness of the single-layer encapsulation film 21 is h1, where 0.08 mm ≤ h1 ≤ 1 mm. By setting the thickness of the single-layer encapsulation film 21 within this appropriate range, the encapsulation strength of the encapsulation film 21 can be ensured, and material waste can be avoided simultaneously.

[0055] If the thickness of the PP layer 211 is too small, after heat melting, the bonding force between the PP layer 211 and the non-PP layer 212 is insufficient, and it is easy for the PP layer 211 and the non-PP layer 212 to peel off; if the thickness of the PP layer 211 is too large, the speed of heat transfer to the bonding layer between the PP layer 211 and the non-PP layer 212 during heat sealing is slow, which will lead to a reduction in heat sealing efficiency and affect the production efficiency of the battery cell 2. In some embodiments, the thickness a1 of the PP layer 211 satisfies 50 μm ≤ a1 ≤ 200 μm. This can prevent the thickness of the PP layer 211 from being too small or too large, ensure the bonding force between the PP layer 211 and the non-PP layer 212 after heat sealing, avoid peeling between the two during use, and at the same time avoid affecting the heat sealing efficiency due to the excessive thickness of the PP layer 211.

[0056] The thickness of the non-PP layer 212 affects the strength of the encapsulation film 21. If the thickness of the non-PP layer 212 is too small, the strength of the encapsulation film 21 is insufficient, and the encapsulation film 21 is easily punctured; if the thickness of the non-PP layer 212 is too large, material waste will be caused. In some embodiments, the thickness a2 of the non-PP layer 212 is made to satisfy 30 μm ≤ a2 ≤ 800 μm. This can control the thickness of the non-PP layer 212 within an appropriate range, ensuring the encapsulation strength of the encapsulation film 21 while avoiding material waste.

[0057] As Figure 7 and Figure 11 shown, the insulating member 23 is provided outside the two sides of the tab 22. After this area is coated with the encapsulation film 21, a convex portion is formed by the encapsulation film 21 outside the insulating member 23 bulging outward. The width of the convex portion is b1. The tab avoidance grooves 114 are provided on the support plate 11 and the pressing plate 12. During heat sealing, the convex portion is located within the tab avoidance grooves 114, and the width of the tab avoidance grooves 114 is b2. During hot pressing, the PP layer 211 of the encapsulation film 21 will creep and deform. If the width of the tab avoidance grooves 114 is too small, serious glue overflow will occur at both ends of the tab 22, resulting in the appearance of the battery cell 2 bulging; if the width of the tab avoidance grooves 114 is too large, the heat pressure at the stepped transition surface of the convex portion will be insufficient, and the melting depth of the PP layer 211 of the encapsulation film 21 and the insulating member 23 will be insufficient, resulting in easy detachment between the two. To avoid these problems, in some embodiments, 0.97 ≤ b2 / b1 ≤ 1.1. By setting the width of the tab avoidance grooves 114 within an appropriate range, it is possible to prevent excessive glue overflow at both ends of the tab 22 after hot pressing, and at the same time ensure the hot pressing effect of the encapsulation film 21 and the insulating member 23 at the transition surface of the convex portion, thereby ensuring the sealing performance at the tab 22.

[0058] Design battery cells with different widths b1 of the protruding parts and correspondingly top-sealing tooling with different widths b2 of the tab avoiding grooves 114. Use the top-sealing tooling to heat-seal the battery cells, observe the states of the battery cells, conduct vibration tests on the heat-sealed battery cells, and observe the states of the battery cells. The test results are shown in Table 2.

[0059] Table 2

[0060] Example 10 b1 / mm b2 / mm b2 / b1 Cell state Example 11 50.00 55.00 1.10 ok Example 12 100 103.5 1.035 ok Example 13 80.00 78.40 0.98 ok Example 14 150 145.5 0.97 ok Comparative Example 7 50.00 60.00 1.20 After the cell vibration test, the seal at the plastic-sealed step area on both sides of the tab fails and leaks liquid Comparative Example 8 80.00 76.80 0.96 After hot pressing, there is serious overflow of glue in the plastic-sealed step area on both sides of the tab, seriously contaminating the tooling and causing bulging on the appearance

[0061] As can be seen from Examples 10 to 14, when the b1 and b2 of the top-sealing tooling satisfy 0.97 ≤ b2 / b1 ≤ 1.1, the battery cells are in good state after heat-sealing and vibration tests; as can be seen from Comparative Example 7, when b2 / b1 > 1.1, the width b2 of the tab avoiding groove 114 is too large, and the thermal pressure at the stepped transition surface of the protruding part of the packaging film is insufficient. After the vibration test of the battery cell, the sealing of the plastic-sealed stepped area on both sides of the tab fails and leaks liquid; as can be seen from Comparative Example 8, when b2 / b1 < 0.97, the width of the tab avoiding groove 114 is too small, resulting in serious glue overflow at both ends of the tab 22, causing the appearance of the battery cell 2 to bulge.

[0062] In some alternative embodiments, 5 mm ≤ b1 ≤ 300 mm and 4.5 mm ≤ b2 ≤ 330 mm.

[0063] In some embodiments, the flatness of the bottom surface of the pressing plate 12 is less than 0.5 mm, and the roughness of the bottom surface of the pressing plate 12 is within Rz16, which can avoid uneven heat-pressing and plastic-sealing and avoid local sealing defects.

[0064] As Figure 9 and Figure 10 shown, the support plate 11 and the pressing plate 12 are strip-shaped. The bottom of the support plate 11 is provided with a horizontally arranged bottom plate, and the bottom area of the bottom plate is larger than the bottom area of the support plate 11, which can improve the support stability of the support plate 11 for the battery cell 2. During top-sealing, the edge of the packaging film 21 with the tab 22 is placed on the top surface of the support plate 11, and both ends of the support plate 11 are located outside the width edges of the packaging film 21.

[0065] According to an embodiment of the present invention, on the other hand, a battery cell 2 is also provided, which is top-sealed and packaged by using the top-sealing tooling 1 of the above embodiment.

[0066] When encapsulating the battery cell 2 with this structure, first place the encapsulation edge of the battery cell 2 on the support plate 11. The pressing plate 12 moves downward and presses above the encapsulation edge. The limiting boss 111 slides along the groove wall of the limiting groove 121, which can position the pressing plate 12 and guide the pressing plate 12 to descend, facilitating the positioning and pressing of the pressing plate 12 and the support plate 11, and preventing overpressure or cracking of the encapsulation film 21 caused by misalignment. After the bottom of the limiting groove 121 contacts the end face of the limiting boss 111, the pressing plate 12 stops pressing down. The pressing plate 12 is limited by the limiting boss 111, and the downward pressing stroke of the pressing plate 12 can be accurately controlled. By making the distance h between the top surface of the support plate 11 and the bottom surface of the pressing plate 12 satisfy h≥2a1(1 - Xmax)+2a2, this can prevent the distance between the top surface of the support plate 11 and the bottom surface of the pressing plate 12 from being too small during heat sealing, ensure the total thickness of the two layers of encapsulation film 21 after heat sealing, avoid overmelting of the encapsulation film 21 caused by overpressure, ensure the bonding force between the PP layer 211 and the non-PP layer 212 of the encapsulation film, avoid peeling between the PP layer 211 and the non-PP layer 212 during the use of the battery cell 2, and ensure the sealing performance at the tab 22 of the battery cell 2; at the same time, h satisfies h≤2a1(1 - Xmin)+2a2. Such a setting can prevent the distance between the top surface of the support plate 11 and the bottom surface of the pressing plate 12 from being too large during heat sealing, prevent the thickness of the two layers of encapsulation film 21 after heat sealing from being too large, ensure sufficient heat pressing of the encapsulation film 21, avoid insufficient heat pressing strength, ensure the encapsulation strength between the two layers of encapsulation film 21 after heat sealing, and ensure the sealing performance at the tab 22 of the battery cell 2.

[0067] According to an embodiment of the present invention, on the other hand, a battery pack is also provided, including the battery cell 2 of the above embodiment.

[0068] For the battery pack with this structure, during heat sealing, the distance h between the top surface of the support plate 11 and the bottom surface of the pressing plate 12 satisfies 2a1(1 - Xmax)+2a2≤h≤2a1(1 - Xmin)+2a2. This can ensure the total thickness of the two layers of encapsulation film 21 after heat sealing, avoid overmelting of the encapsulation film 21 caused by overpressure, and ensure the sealing performance at the tab 22 of the battery cell 2; at the same time, it can prevent the thickness of the two layers of encapsulation film 21 after heat sealing from being too large, ensure sufficient heat pressing of the encapsulation film 21, avoid insufficient heat pressing strength, ensure the encapsulation strength between the two layers of encapsulation film 21 after heat sealing, and ensure the sealing performance at the tab 22 of the battery cell 2, which is beneficial to improving the safety performance of the battery pack.

[0069] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A top sealing tool, characterized in that: include: Support plate; A pressing plate, suitable for being pressed onto the top of the support plate; a limiting boss is provided on at least one side of the length direction of one of the top surface of the support plate and the bottom surface of the pressing plate, and a limiting groove is provided on the other of the top surface of the support plate and the bottom surface of the pressing plate. During heat sealing, the packaging film, the pole ear and the insulating member of the battery cell are suitable to be arranged between the support plate and the pressing plate. When the step surface of the limiting boss abuts against the bottom of the limiting groove, the spacing between the top surface of the support plate and the bottom surface of the pressing plate suitable for being pressed onto the butt joint area of ​​the two layers of packaging film is h. The packaging film includes a PP layer and a non-PP layer. The deformation rate of the PP layer is X, 60%≤X≤80%, the maximum value of X is Xmax, and the minimum value of X is Xmin. The thicknesses of the PP layer and the non-PP layer are a1 and a2, respectively, 2a1(1-Xmax)+2a2≤h≤2a1(1-Xmin)+2a2; the unit of h, a1, and a2 is μm.

2. The top sealing tool according to claim 1, characterized in that: The length of the outer end surface of the limiting boss extending along the length direction of the top sealing tool is L, and the width of the outer end surface of the limiting boss extending along the width direction of the top sealing tool is W, 3mm≤L≤50mm, 3mm≤W≤50mm.

3. The top sealing tool according to claim 1 or 2, characterized in that: The limiting bosses are arranged at both ends of the length direction of the support plate, and the limiting grooves are arranged at both ends of the length direction of the pressure plate; the side of the limiting boss facing the inside of the support plate is a first inclined surface, and the side wall of the limiting groove is a second inclined surface. During heat sealing, the second inclined surface is pressed onto the first inclined surface.

4. The top sealing tool according to claim 3, characterized in that: The included angle between the first inclined surface and the top surface of the limiting boss is K, and 100°≤K≤160°.

5. The top sealing tool according to claim 3, characterized in that: During heat sealing, the vertical height of the bonding area between the first inclined surface and the second inclined surface is e, and 1mm≤e≤50mm.

6. The top sealing tool according to claim 3, characterized in that: The support plate and the pressure plate on the inner side of the limiting boss are provided with avoidance grooves, a first plane extending in the same direction as the top surface of the support plate is provided on the support plate between the avoidance groove and the first inclined surface, a second plane extending in the same direction as the bottom surface of the pressure plate is provided on the pressure plate between the avoidance groove and the second inclined surface, and during heat sealing, the distance between the first plane and the second plane is f, 0.5mm≤f≤50mm.

7. The top sealing tool according to claim 1 or 2, characterized in that: The thickness of the single-layer packaging film is h1, 0.08mm≤h1≤1mm; and / or, 50 μm ≤ a1 ≤ 200 μm; And / or, 30μm≤a2≤800μm.

8. The top sealing tool according to claim 1 or 2, characterized in that: The packaging film outside the insulating part protrudes outward to form a protrusion, the width of the protrusion is b1, and the support plate and the pressure plate are provided with a tab avoidance groove. During heat sealing, the protrusion is located in the tab avoidance groove, the width of the tab avoidance groove is b2, 0.97≤b2 / b1≤1.

1.

9. A battery cell, characterized in that: The top sealing package is performed by using the top sealing tool according to any one of claims 1 to 8.

10. A battery pack, characterized in that: Comprising the battery cell as claimed in claim 9.

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