A lithium battery cell and a method for wrapping a lithium battery cell with an insulating film

Abstract

The present invention discloses a lithium battery cell and a method for wrapping an insulating film for a lithium battery cell, wherein the lithium battery cell comprises a cover plate, a pole, a connecting piece and at least one winding core, wherein the pole is arranged on the upper surface of the cover plate, and the connecting piece is located between the cover plate and the winding core; one end of the connecting piece is connected to the pole ear of the winding core, and the other end is connected to the pole; the lithium battery cell also comprises an insulating film, and the insulating film is wrapped around the outside of the winding core; the insulating film comprises a fixing portion and a wrapping portion, wherein the fixing portion is located in the middle of the insulating film, and the wrapping portion is the other part of the insulating film except the fixing portion; the fixing portion is fixed to the bottom end of the cover plate, and the wrapping portion wraps the winding core from the bottom end of the cover plate downward, and the cover plate is fixed above the winding core. The lithium battery cell and the method for wrapping an insulating film for a lithium battery cell of the present invention have high production efficiency and can also avoid the problem of the pole ear running out and scalding the internal diaphragm of the winding core.

Description

Technical Field

[0001] The invention relates to a battery manufacturing technology, and in particular to a lithium battery cell and a method for wrapping a lithium battery cell with an insulating film. Background Art

[0002] With the advancement of technology and the awakening of users' environmental awareness, the share of new energy vehicles has gradually increased. As the power source of new energy vehicles, lithium batteries have also risen in value and their output has increased; however, compared with traditional power batteries such as lead-acid batteries, the performance of lithium batteries is not stable and safe enough. Therefore, improving the stability and safety of lithium batteries in use has become the preferred research direction of the lithium battery industry.

[0003] At present, the square cell is the most common cell structure in lithium batteries. The square cell is generally made up of two roll cores. To ensure the safety of the cell, a layer of insulating film needs to be wrapped on the side and bottom of the cell during the production process to prevent the cell from directly contacting the metal aluminum shell and causing a short circuit. Therefore, the wrapping quality of the insulating film is very important for the safety performance of the cell.

[0004] Manual wrapping and automatic wrapping are the two most commonly used wrapping methods. Although both wrapping methods can complete the wrapping work, manual wrapping has low efficiency and low wrapping accuracy. The existing automatic wrapping process is to heat the insulating film on the cell cover from the bottom of the cell upwards to complete the wrapping process. There are problems such as the outer ear contacting the aluminum shell and the insulating film burning the internal diaphragm of the winding core, causing the winding core to short-circuit. Summary of the invention

[0005] In view of this, the present invention hopes to provide a lithium battery cell and a method for wrapping a lithium battery cell with an insulating film, which has high production efficiency and can also avoid the problem of tabs leaking out and scalding the diaphragm inside the winding core.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] The present invention provides a lithium battery cell, the lithium battery cell comprising a cover plate, a pole, a connecting piece and at least one winding core, the pole being arranged on the upper surface of the cover plate, the connecting piece being located between the cover plate and the winding core; one end of the connecting piece is connected to a pole ear of the winding core, and the other end is connected to the pole;

[0008] The lithium battery cell also includes an insulating film, which is wrapped around the outside of the winding core; the insulating film includes a fixing portion and a wrapping portion, the fixing portion is located in the middle of the insulating film, and the wrapping portion is the other portion of the insulating film except the fixing portion; the fixing portion is fixed to the bottom end of the cover plate, and the wrapping portion wraps the winding core from the bottom end of the cover plate downward, and the cover plate is fixed above the winding core.

[0009] In the above solution, a stop frame is provided at the bottom end of the cover plate, and the stop frame is provided with at least two positioning posts for positioning the insulating film, and the insulating film is provided with positioning holes that cooperate with the positioning posts.

[0010] In the above scheme, the lithium battery cell includes two winding cores, which are placed in parallel, and the pole ear ends of the two winding cores are facing the bottom end of the cover plate; an isolation sheet is also arranged between the connecting sheet and the winding core, and the isolation sheet is a plastic sheet of preset thickness; the two ends of the isolation sheet are respectively at preset distances from the pole ears of the two winding cores.

[0011] In the above solution, the fixing portion is fixed to the bottom end of the cover plate by a hot stamping process.

[0012] The present invention also provides another lithium battery cell, which includes a cover plate, a pole, a connecting sheet and two winding cores, wherein the pole is arranged on the upper surface of the cover plate, and the connecting sheet is located between the cover plate and the winding core; one end of the connecting sheet is connected to the pole ear of the winding core, and the other end is connected to the pole; the two winding cores are placed in parallel, and the pole ear ends of the two winding cores are both facing the bottom end of the cover plate; an isolation sheet is also arranged between the connecting sheet and the winding core, and the isolation sheet is a plastic sheet of a preset thickness; the two ends of the isolation sheet are respectively at a preset distance from the pole ears of the two winding cores.

[0013] The present invention also provides a method for preparing an insulating film for a lithium battery core, the method comprising:

[0014] Fixing the fixing portion of the insulating film to the bottom end of the cover plate;

[0015] Connect the connecting pieces to the pole ears and poles of the winding core respectively;

[0016] Turning the winding core inwardly so that the tab end of the winding core faces the bottom end of the cover plate;

[0017] The wrapping portion of the insulating film is wrapped around the winding core from top to bottom.

[0018] In the above scheme, after the connecting sheet is connected to the pole lug and pole of the winding core respectively, and before the winding core is turned inwardly so that the pole lug end of the winding core faces the bottom end of the cover plate, the method further includes:

[0019] A spacer is inserted between the winding core and the connecting sheet.

[0020] In the above solution, the fixing portion of the insulating film is fixed to the bottom end of the cover plate, comprising:

[0021] The fixing part of the insulating film is placed on the stop frame at the bottom end of the cover plate, and the positioning hole of the insulating film is inserted into the positioning column of the stop frame;

[0022] The insulating film is fixed on the stop frame.

[0023] In the above solution, the step of fixing the insulating film on the stop frame comprises:

[0024] The positioned insulating film is fixed by hot stamping in a preset hot stamping area of ​​the stop frame.

[0025] In the above solution, the connecting sheet is connected to the pole ear and pole of the winding core respectively, including:

[0026] The connecting piece and the pole lug of the winding core are connected by ultrasonic welding, and the connecting piece and the pole are connected by laser welding.

[0027] The lithium battery cell and the method for wrapping the lithium battery cell with an insulating film of the present invention design the insulating film into a fixing portion and a wrapping portion, wherein the fixing portion is located in the middle of the insulating film, and the wrapping portion is the other portion of the insulating film except the fixing portion; the fixing portion is fixed to the bottom end of the cover plate, and the wrapping portion wraps the roll core downward from the bottom end of the cover plate; it can be seen that the insulating film of the lithium battery cell of the present invention can first fix the middle fixing portion to the bottom end of the cover plate, and then the wrapping portions on all sides wrap the cell from top to bottom, so that the opening of the insulating film is at the bottom, and the insulating film is complete at the upper end of the cell, compared with the method of wrapping from bottom to top with the opening at the top in the prior art, the problem of the upper end of the pole ear running out can be avoided; moreover, the change in the insulating film wrapping method in the present invention can first fix the insulating film on the cover plate by hot stamping before the roll core is connected to the cover plate, and there is no problem of scalding the internal diaphragm of the roll core; therefore, the present invention has both high production efficiency and can avoid the problems of the pole ear running out and scalding the internal diaphragm of the roll core.

[0028] Other beneficial effects of the present invention will be further described in the specific implementation manner in conjunction with the specific technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the appearance of a lithium battery cell according to a first embodiment of the present invention;

[0030] Figure 2 for Figure 1 Schematic diagram of the middle AA direction;

[0031] Figure 3 This is a schematic diagram of a separator in a lithium battery cell according to an embodiment of the present invention;

[0032] Figure 4 for Figure 3 A top view of

[0033] Figure 5 It is a schematic diagram of blanching the insulating film in the method for packing the insulating film of a lithium battery cell according to the second embodiment of the present invention;

[0034] Figure 6 for Figure 5 Left view of

[0035] Figure 7 for Figure 6 Left view of

[0036] Figure 8 This is a schematic diagram of the method for wrapping an insulating film around a lithium battery cell in accordance with the second embodiment of the present invention after the cover plate is connected to the winding core and before the winding is completed. DETAILED DESCRIPTION

[0037] It should be noted that, in the description of the embodiments of the present invention, unless otherwise specified and limited, the term "connection" should be understood in a broad sense. For example, it can be an electrical connection or a connection between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0038] It should be noted that the terms "first, second, and third" in the embodiments of the present invention are only used to distinguish similar objects, and do not represent a specific order for the objects. It is understandable that the specific order or sequence of "first, second, and third" can be interchanged where permitted. It should be understood that the objects distinguished by "first, second, and third" can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0039] An embodiment of the present invention provides a lithium battery cell, which includes a cover plate, a pole, a connecting sheet and at least one winding core, wherein the pole is arranged on the upper surface of the cover plate, and the connecting sheet is located between the cover plate and the winding core; one end of the connecting sheet is connected to the pole ear of the winding core, and the other end is connected to the pole; the lithium battery cell also includes an insulating film, which is wrapped around the outside of the winding core; the insulating film includes a fixing portion and a wrapping portion, the fixing portion is located in the middle of the insulating film, and the wrapping portion is the other portion of the insulating film except the fixing portion; the fixing portion is fixed to the bottom end of the cover plate, and the wrapping portion wraps the winding core from the bottom end of the cover plate downward, and the cover plate is fixed above the winding core.

[0040] Here, the cover plate is mainly used to set the pole, and it is also convenient to fix the insulating film outside the battery cell; the pole is used to obtain external charging or discharge to the outside, and the pole ear is the part of the core that is electrically connected to the outside. Generally, a core includes a positive pole ear and a negative pole ear, and a positive pole column and a negative pole column are set on a cover plate. If there are multiple cores, the positive pole ears of multiple cores are connected in parallel to the positive pole column of the cover plate, and the negative pole ears of multiple cores are connected in parallel to the negative pole column of the cover plate.

[0041] The principle of the embodiment of the present invention: the insulating film can first fix the middle fixing part to the bottom end of the cover plate, and then the surrounding wrapping parts wrap the battery cell from top to bottom, so that the opening of the insulating film is at the bottom, and the insulating film is complete at the upper end of the battery cell. Compared with the method of wrapping from bottom to top with the opening at the top in the prior art, the problem of the upper end of the pole ear running out can be avoided; moreover, the change in the insulating film wrapping method in the embodiment of the present invention can fix the insulating film on the cover plate by hot stamping before the core is connected to the cover plate, and there is no problem of burning the internal diaphragm of the core; therefore, the embodiment of the present invention has both high production efficiency and can avoid the problems of the pole ear running out and burning the internal diaphragm of the core.

[0042] In one embodiment, a stop frame is provided at the bottom end of the cover plate, and the stop frame is provided with at least two positioning posts for positioning the insulating film, and the insulating film is provided with positioning holes that cooperate with the positioning posts. The stop frame is generally made of plastic material, which is convenient for fixing with the insulating film and can also insulate the winding core from the cover plate; the provision of the positioning posts makes it easier for the insulating film to be positioned at a preset position.

[0043] In one embodiment, the lithium battery cell includes two winding cores, the two winding cores are placed in parallel, and the pole lug ends of the two winding cores are facing the bottom end of the cover plate; a spacer is also provided between the connecting sheet and the winding core, and the spacer is a plastic sheet of preset thickness; the two ends of the spacer are respectively at a preset distance from the pole lugs of the two winding cores. Two winding cores can have a larger capacity and avoid the problem that a single winding core is too thin and has poor strength. The preset thickness is to ensure that the isolation sheet has a certain strength, and the preset distance is very small, generally less than 1mm, which is basically equal to the two ends of the isolation sheet respectively against the pole lugs of the two winding cores, so that the pole lugs of the winding core can be prevented from bending inward, which is easy to damage the pole lugs, and may also be inserted into the winding core diaphragm, damaging the winding core diaphragm, and causing the winding core to short-circuit; because the pole lug is soft, its normal state is curved, but the length of the pole lug after extension is much greater than the distance between the winding core and the connecting sheet, so that the pole lug is easy to bend inward when the winding core is turned over, causing the pole lug damage or inverted insertion to damage the winding core diaphragm.

[0044] In one embodiment, the fixing portion is fixed to the bottom end of the cover plate by a hot stamping process. Hot stamping is simple to implement, does not require additional connecting parts, and does not increase the risk of electrical leakage.

[0045] In one embodiment, the connecting piece is connected to the pole lug of the winding core by ultrasonic welding, and the connecting piece is connected to the pole by laser welding. Ultrasonic welding is a solid-state welding achieved without melting the parent material, so it effectively overcomes the spatter and oxidation phenomena produced by resistance welding. The ultrasonic metal welder can perform single-point welding, multi-point welding and short-strip welding on filaments or thin sheet materials of non-ferrous metals such as copper, silver, aluminum, and nickel, and can be widely used in the welding of thyristor leads, fuse sheets, electrical leads, lithium battery pole pieces, and pole lugs. Laser welding has the characteristics of fast welding speed and large depth-to-width ratio, making the connection between the connecting piece and the pole firm and reliable.

[0046] The embodiment of the present invention also provides a method for insulating a lithium battery core pack, the method comprising:

[0047] Fixing the fixing portion of the insulating film to the bottom end of the cover plate;

[0048] Connect the connecting pieces to the pole ears and poles of the winding core respectively;

[0049] Turning the winding core inwardly so that the tab end of the winding core faces the bottom end of the cover plate;

[0050] The wrapping portion of the insulating film is wrapped around the winding core from top to bottom.

[0051] In this way, the insulating film of the lithium battery cell of the embodiment of the present invention can first fix the middle fixing part to the bottom end of the cover plate, and then the surrounding wrapping parts wrap the cell from top to bottom, so that the opening of the insulating film is at the bottom, and the insulating film is complete at the upper end of the cell. Compared with the method of wrapping from bottom to top with the opening at the top in the prior art, the problem of the upper end of the pole ear leaking out can be avoided; moreover, the change in the insulating film wrapping method in the embodiment of the present invention can fix the insulating film on the cover plate by hot stamping before the winding core is connected to the cover plate, and there is no problem of burning the internal diaphragm of the winding core; therefore, the embodiment of the present invention has both high production efficiency and can avoid the problems of the pole ear leaking out and the internal diaphragm of the winding core.

[0052] Here, connecting the connecting piece to the pole ear and pole of the winding core respectively refers to establishing electrical connection between the connecting piece and the pole ear and pole of the winding core respectively, that is, establishing a circuit channel for charging or discharging.

[0053] Flipping the core inward generally refers to flipping the core 90 degrees so that the ear end of the core faces the bottom end of the cover plate, that is, faces the bottom plane perpendicular to the cover plate. In this way, the cover plate can cover the ear end of the core, making the battery safer to use. When connecting the connecting piece to the ear of the core, the direction of the core is generally parallel to the bottom plane of the cover plate.

[0054] In one embodiment, after the connecting sheet is connected to the pole lug and pole of the winding core respectively, and before the winding core is turned inwardly so that the pole lug end of the winding core faces the bottom end of the cover plate, the method further includes:

[0055] A spacer is inserted between the core and the connecting sheet. The distance between the two ends of the spacer and the lugs of the core is very small, which can prevent the lugs of the core from bending inwards, which is easy to damage the lugs, and may also be inserted into the core diaphragm, damaging the core diaphragm and causing a short circuit in the core; because the distance between the core and the connecting sheet is much smaller than the elongated length of the lug, the lug is easy to bend inwards when the core is turned over, causing damage to the lugs or damaging the core diaphragm by inserting backwards.

[0056] In one embodiment, the fixing portion of the insulating film to the bottom end of the cover plate includes:

[0057] The fixing part of the insulating film is placed on the stop frame at the bottom end of the cover plate, and the positioning hole of the insulating film is inserted into the positioning column of the stop frame;

[0058] The insulating film is fixed on the stop frame.

[0059] The stop frame is generally made of plastic material, which is convenient for fixing with the insulating film and can also insulate the winding core from the cover plate; the provision of the positioning column makes it easier for the insulating film to be positioned at a preset position.

[0060] In one embodiment, fixing the insulating film on the stop frame comprises:

[0061] The positioned insulating film is fixed by hot stamping in a preset hot stamping area of ​​the stop frame.

[0062] Hot stamping is easy to implement and does not require additional connecting parts, which will not increase the risk of leakage. The hot stamping area is preset so that it is fixed evenly.

[0063] In one embodiment, before placing the fixing portion of the insulating film on the stop frame at the bottom end of the cover plate and inserting the positioning hole of the insulating film into the positioning column of the stop frame, the method further includes:

[0064] The bottom end of the cover plate is placed upward, and the outer end of the positioning column of the stop frame is placed upward, so as to facilitate the placement, positioning and hot stamping of the insulating film.

[0065] In one embodiment, the connecting sheet is connected to the pole lug and pole of the winding core respectively, comprising:

[0066] The connecting piece and the pole lug of the winding core are connected by ultrasonic welding, and the connecting piece and the pole are connected by laser welding.

[0067] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0068] Embodiment 1

[0069] Figure 1 FIG. 1 is a schematic diagram of the appearance of a lithium battery cell according to an embodiment of the present invention. Figure 2 for Figure 1 The schematic diagram of the AA direction is as follows: Figure 1 , 2 As shown, the lithium battery cell includes a cover plate 11, a connecting sheet 12, a pole 111, an insulating film 13 and two winding cores 14; the cover plate 11 is fixed on the winding core 14, and the insulating film 13 is wrapped around the outside of the winding core 14; the insulating film 13 includes a fixing portion 131 and a wrapping portion 132, the fixing portion 131 is located in the middle of the insulating film 13, and the wrapping portion 132 is the other part of the insulating film 13 except the fixing portion 131 (see Figure 4-6 ); the fixing portion 131 is fixed to the bottom end of the cover plate 11, and the wrapping portion 132 wraps the core 14 from the bottom end of the cover plate 11 downward; the connecting piece 12 is located between the cover plate 11 and the core 14; one end of the connecting piece 12 is connected to the pole ear 141 of the core 14, and the other end is connected to the pole 111. The two cores 14 are placed in parallel, and the pole ears 141 of the two cores 14 are both facing the bottom end of the cover plate 11. Two cores 14 can have a larger capacitance and avoid the problem that a single core 14 is too thin and has poor strength.

[0070] In this way, the insulating film 13 can first fix the middle fixing part 131 to the bottom end of the cover plate 11, and then the surrounding wrapping parts 132 wrap the battery cell from top to bottom, so that the opening of the insulating film 13 is at the bottom, and the insulating film 13 is complete at the upper end of the battery cell. Compared with the method of wrapping from bottom to top with the opening at the top in the prior art, the problem of the upper end of the pole ear 141 leaking out can be avoided; moreover, the change in the wrapping method of the insulating film 13 in the embodiment of the present invention can fix the insulating film 13 on the cover plate 11 before the winding core 14 is connected to the cover plate 11, and there is no problem of burning the internal diaphragm of the winding core 14; therefore, the embodiment of the present invention has both high production efficiency and can avoid the problem of the pole ear 141 leaking out and burning the internal diaphragm of the winding core 14.

[0071] In this embodiment, a stop frame 16 is provided at the bottom end of the cover plate 11, and the stop frame 16 is provided with at least two positioning posts 161 for positioning the insulating film 13, and the insulating film 13 is provided with positioning holes 133 that cooperate with the positioning posts 161. The stop frame 16 is generally made of plastic material, which is convenient for fixing with the insulating film 13 and can also insulate the winding core 14 from the cover plate 11; the provision of the positioning posts 161 makes it easier for the insulating film 13 to be positioned at a preset position.

[0072] In this embodiment, a spacer 15 is further provided between the connecting sheet 12 and the winding core 14. The spacer 15 is a plastic sheet of a preset thickness; both ends of the spacer 15 are respectively at a preset distance from the tabs 141 of the two winding cores 14. The preset thickness is to ensure that the spacer has a certain strength. The preset thickness in this embodiment is 2 mm; the preset distance is 0.5 mm in this embodiment, so that both ends of the spacer 15 almost abut against the tabs 141 of the two winding cores 14, which can prevent the tabs 141 of the winding core 14 from bending inwards, which is easy to damage the tabs 141, and may also be inserted into the diaphragm of the winding core 14, damaging the diaphragm of the winding core 14, resulting in a short circuit of the winding core 14. In this embodiment, the extended length of the pole ear 141 is 17 mm, and the distance between the winding core 14 and the connecting sheet 12 is 5 mm, that is, the distance between the winding core 14 and the connecting sheet 12 is much smaller than the extended length of the pole ear 141, so that the pole ear 141 is easy to bend inward, which is easy to damage the pole ear 141, and may also be inserted into the diaphragm of the winding core 14; and the isolation sheet 15 can avoid the above problems. The isolation sheet 15 is as follows Figure 3 , 4 shown.

[0073] It should be noted that the separator 15 can be implemented alone without the improvement of the insulating film, and can also prevent the tab 141 from being easily bent inward, which can easily damage the tab 141 and the separator inserted into the winding core 14. Of course, it can also be implemented together with the improved insulating film, so that the quality and performance of the lithium battery cell are better.

[0074] In this embodiment, the pole ear 141 is also covered with an insulating tape 17, but the insulating tape 17 is easy to fall off when the pole ear 141 is bent, so it cannot play an insulating role. Therefore, an isolation sheet 15 is still needed to prevent the pole ear 141 from being bent significantly, and the insulating film outside the winding core is used to prevent the pole ear 141 from running out.

[0075] In this embodiment, the fixing portion 131 is fixed to the bottom end of the cover plate 11 by a hot stamping process. Hot stamping is simple to implement, does not require additional connecting parts, and does not increase the risk of leakage.

[0076] In this embodiment, the connecting piece 12 is connected to the pole lug 141 of the winding core 14 by ultrasonic welding, and the connecting piece 12 is connected to the pole 111 by laser welding. In this way, the welding process is safe, and the connection is firm and reliable.

[0077] Embodiment 2

[0078] The embodiment of the present invention further provides a method for wrapping an insulating film around a lithium battery cell. The lithium battery cell may be the lithium battery cell described in Embodiment 1. The method comprises:

[0079] Step 201: Place the bottom end of the cover plate 11 upwards, and the outer end of the positioning column 161 of the stop frame 16 upwards. This facilitates the placement, positioning and hot stamping of the insulating film 13;

[0080] Step 202: Place the fixing portion 131 of the insulating film 13 on the stop frame 16 at the bottom end of the cover plate 11, and insert the positioning hole 133 of the insulating film 13 into the positioning column 161 of the stop frame 16. In this way, the insulating film 13 is more easily positioned to a preset position, such as Figure 5-7 As shown;

[0081] Step 203: Hot-scald the positioned insulating film 13 to the preset hot-scald area 21 of the stop frame 16. Hot-scalding is simple to implement and does not require additional connecting parts, which will not increase the risk of leakage. Considering the welding firmness and welding efficiency, the hot-scalding area 21 is preset to 8, such as Figure 5-7 As shown;

[0082] Step 204: Connect the connecting piece 12 to the pole lug 141 and pole 111 of the winding core 14 respectively. Figure 8 As shown; specifically, the connecting piece 12 and the pole ear 141 of the winding core 14 are connected by ultrasonic welding, and the connecting piece 12 and the pole 111 are connected by laser welding;

[0083] Step 205: inserting the isolation sheet 15 between the winding core 14 and the connecting sheet 12. In this embodiment, after the isolation sheet 15 is inserted, the distance between the two ends of the isolation sheet 15 and the pole ear 141 of the winding core 14 is 0.5 mm respectively, which can prevent the pole ear 141 of the winding core 14 from bending inwards, which is easy to damage the pole ear 141, and may also be inserted into the winding core 14 diaphragm upside down, damaging the winding core 14 diaphragm, causing the winding core 14 to short-circuit; in this embodiment, the extended length of the pole ear 141 is 17 mm, and the distance between the winding core 14 and the connecting sheet 12 is 5 mm, that is, the distance between the winding core 14 and the connecting sheet 12 is much smaller than the extended length of the pole ear 141, so that the pole ear 141 is easy to bend inwards, which is easy to damage the pole ear 141, and may also be inserted into the winding core 14 diaphragm upside down; and the provision of the isolation sheet 15 can avoid the above problems;

[0084] Step 206: Flip the winding core 14 inwardly so that the end of the pole ear 141 of the winding core 14 faces the bottom end of the cover plate 11; specifically, flip the winding core 14 inwardly by 90 degrees so that the end of the pole ear 141 of the winding core 14 faces the bottom end of the cover plate 11, that is, faces the bottom plane perpendicular to the cover plate 11, so that the cover plate 11 can cover the end of the pole ear 141 of the winding core 14, making the battery safer to use. The flipping process is generally also called winding; when connecting the connecting piece 12 to the pole ear 141 of the winding core 14, the direction of the winding core 14 is generally parallel to the bottom plane of the cover plate 11. The state before flipping is referred to as Figure 8 To show it more clearly, Figure 8 The insulating film is not shown;

[0085] Step 207: Wrap the wrapping portion 132 of the insulating film 13 with the winding core 14 from top to bottom. Figure 1 , 2 .

[0086] In this way, the insulating film 13 of the lithium battery cell of the embodiment of the present invention can first fix the middle fixing part 131 to the bottom end of the cover plate 11, and then the surrounding wrapping parts 132 wrap the cell from top to bottom, so that the opening of the insulating film 13 is at the bottom, and the insulating film 13 is complete at the upper end of the cell. Compared with the method of wrapping from bottom to top with the opening at the top in the prior art, the problem of the upper end of the pole ear 141 leaking out can be avoided; moreover, the change in the wrapping method of the insulating film 13 in the embodiment of the present invention can fix the insulating film 13 on the cover plate 11 by hot stamping before the winding core 14 is connected to the cover plate 11, and there is no problem of burning the internal diaphragm of the winding core 14; therefore, the embodiment of the present invention has both high production efficiency and can avoid the problem of the pole ear 141 leaking out and the internal diaphragm of the winding core 14.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A lithium battery cell, characterized in that: The lithium battery cell comprises a cover plate, a pole, a connecting piece and at least one winding core, wherein the pole is arranged on the upper surface of the cover plate, and the connecting piece is located between the cover plate and the winding core; one end of the connecting piece is connected to the pole ear of the winding core, and the other end is connected to the pole; The lithium battery cell further includes an insulating film, which is wrapped around the outside of the winding core; the insulating film includes a fixing portion and a wrapping portion, the fixing portion is located in the middle of the insulating film, and the wrapping portion is the other portion of the insulating film except the fixing portion; the fixing portion is fixed to the bottom end of the cover plate, the wrapping portion wraps the winding core downward from the bottom end of the cover plate, and the cover plate is fixed above the winding core; A stop frame is provided at the bottom end of the cover plate, the stop frame is provided with at least two positioning posts for positioning the insulating film, and the insulating film is provided with positioning holes that cooperate with the positioning posts; A spacer is also provided between the connecting sheet and the winding core, and the spacer is a plastic sheet of a preset thickness; both ends of the spacer are respectively at preset distances from the pole ears of the two winding cores; the connecting sheet and the pole ears of the winding core are connected by ultrasonic welding, and the connecting sheet and the pole are connected by laser welding; The lithium battery core insulation film method comprises the following steps: Fixing the fixing portion of the insulating film to the bottom end of the cover plate; Connect the connecting pieces to the pole ears and poles of the winding core respectively; Turning the winding core inwardly so that the tab end of the winding core faces the bottom end of the cover plate; The wrapping portion of the insulating film is wrapped around the winding core from top to bottom.

2. The lithium battery cell according to claim 1, characterized in that: The lithium battery cell includes two winding cores, which are placed in parallel, and the pole ear ends of the two winding cores are facing the bottom end of the cover plate; an isolation sheet is also arranged between the connecting sheet and the winding core, and the isolation sheet is a plastic sheet of preset thickness; the two ends of the isolation sheet are respectively at preset distances from the pole ears of the two winding cores.

3. The lithium battery cell according to claim 1 or 2, characterized in that: The fixing portion is fixed to the bottom end of the cover plate by a hot stamping process.

4. The lithium battery cell according to claim 3, characterized in that: After the connecting sheet is connected to the pole lug and pole of the winding core respectively, before the winding core is turned inwardly so that the pole lug end of the winding core faces the bottom end of the cover plate, an isolation sheet is inserted between the winding core and the connecting sheet.

5. The lithium battery cell according to claim 4, characterized in that: The method of fixing the fixing portion of the insulating film to the bottom end of the cover plate includes: The fixing part of the insulating film is placed on the stop frame at the bottom end of the cover plate, and the positioning hole of the insulating film is inserted into the positioning column of the stop frame; The insulating film is fixed on the stop frame.

6. The lithium battery cell according to claim 5, characterized in that: The step of fixing the insulating film on the stop frame comprises: The positioned insulating film is fixed by hot stamping in a preset hot stamping area of ​​the stop frame.

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