A battery cell and a battery

Abstract

The utility model discloses a battery cell and a battery, wherein the battery cell comprises a body, wherein the body is formed by stacking a first pole piece, an isolation film and a second pole piece and then winding; the first pole piece comprises a first section, a second section and a third section, and the two ends of the second section are respectively connected to the first section and the third section, wherein the end of the first section away from the second section is the first winding starting point of the first pole piece; the first section comprises a first bending section, a second bending section, a first straight section and a second straight section, and the two ends of the first bending section are respectively connected to the second section and the first straight section, and the two ends of the second bending section are respectively connected to the first straight section and the second straight section, and the end of the second straight section away from the second bending section is the first winding starting point. The first pole piece is bent twice by the first bending section and the second bending section, so that the position of the first winding starting point is more stable, and it is not easy to have problems such as poor position of the pole ear margin caused by position offset and wrinkling of the head, thereby improving the quality of the battery cell.

Description

Technical Field

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

[0002] A lithium-ion battery is a secondary battery, which consists of an internal bare cell and an outer shell. The internal bare cell is mainly composed of a positive electrode sheet, a negative electrode sheet and a separator which are wound together. The separator is arranged between the positive electrode sheet and the negative electrode sheet. Active substances are coated on the surfaces of the positive and negative electrodes to participate in charging and discharging. In the prior art, a blank area is generally left at the head of the electrode sheet for welding the pole ear. The blank area will be laid flat inside the cell and then wound from the inside to the outside. However, the flat head is prone to problems such as displacement and wrinkling during the winding process, which affects the quality of the cell. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides a battery core that can have higher quality.

[0004] The utility model also provides a battery having the battery core.

[0005] The battery cell according to the first aspect of the present invention comprises: a main body, which is formed by stacking and winding a first pole piece, an isolation membrane and a second pole piece; the first pole piece comprises a first section, a second section and a third section, two ends of the second section are respectively connected to the first section and the third section, both sides of the third section along the thickness direction have a first active material layer, the second section has the first active material layer only on the side away from the first section, and the first section does not have the first active material layer, wherein an end of the first section away from the second section is a first winding starting point of the first pole piece, and an end of the third section away from the second section is a first winding end point of the first pole piece; the first section comprises a first bending section, a second bending section, a first straight section and a second straight section, two ends of the first bending section are respectively connected to the second section and the first straight section, two ends of the second bending section are respectively connected to the first straight section and the second straight section, and an end of the second straight section away from the second bending section is a first winding starting point.

[0006] The battery cell according to the first embodiment of the utility model has at least the following beneficial effects:

[0007] The first pole piece has a first bending section and a second bending section, that is, after the first pole piece is bent twice, when the first pole piece is wound, the setting of the second bending section can effectively avoid the problem of the first pole piece being offset or wrinkled during winding, so that the battery cell can have higher quality.

[0008] According to some embodiments of the utility model, the isolation membrane includes a first end and a second end, the first end is the second winding starting point of the isolation membrane, and along the width direction of the battery cell, the first end protrudes relative to the second straight line segment away from one end of the second bending segment, and the distance between the second winding starting point and the first winding starting point is L1, 5mm≤L1≤10mm.

[0009] According to some embodiments of the present invention, along the width direction of the battery core, the length of the second straight line segment is L2, 1mm≤L2≤10mm.

[0010] According to some embodiments of the present invention, two isolation membranes are provided, and the two isolation membranes are respectively located on both sides of the first pole piece.

[0011] According to some embodiments of the present invention, the isolation membrane includes a polyolefin layer, a PVDF adhesive layer and a ceramic layer, the PVDF adhesive layer has two layers, the two PVDF adhesive layers are respectively bonded to the opposite sides of the polyolefin layer, and the ceramic layer has one layer, the ceramic layer is bonded to the side of one of the PVDF adhesive layers away from the polyolefin layer.

[0012] According to some embodiments of the present invention, the battery cell further includes a first pole tab, and the first pole tab is connected to the first straight line segment.

[0013] According to some embodiments of the present invention, the battery core further includes a first adhesive layer, and the first adhesive layer is bonded to the first pole ear and the first straight line segment.

[0014] According to some embodiments of the utility model, the second pole piece includes a second active material layer, the second active material layer covers a portion of the second pole piece, the second pole piece includes a fourth segment, one end of the fourth segment is a third winding starting point of the second pole piece, the fourth segment does not have a second active material layer, and the battery cell also includes a second pole ear, which is connected to the fourth segment.

[0015] According to some embodiments of the present invention, the battery core further includes a second adhesive layer, and the second adhesive layer is bonded to the second electrode tab and the fourth segment.

[0016] The battery according to the second aspect of the present invention comprises the battery cell described in any one of the first aspect of the present invention.

[0017] The battery according to the embodiment of the second aspect of the utility model has at least the following beneficial effects: the first pole piece has a first bending section and a second bending section, that is, after the first pole piece is bent twice, when the first pole piece is wound, the setting of the second bending section can effectively avoid the problem of displacement or wrinkling of the first pole piece during winding, so that the battery cell can have higher quality, and further, the quality of the battery cell formed by the battery cell is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0019] Figure 1 A structural diagram of a battery cell according to an embodiment of the utility model;

[0020] Figure 2 This is a structural diagram of the isolation membrane in the battery cell of some embodiments of the utility model.

[0021] Reference numerals:

[0022] First pole piece 101, second pole piece 102, isolation film 103, first section 104, second section 105, third section 106, first active material layer 107, second active material layer 108, first pole tab 110, second pole tab 109, first adhesive layer 113, second adhesive layer 111, third adhesive layer 112, fourth section 114, polyolefin layer 201, PVDF adhesive layer 202, ceramic layer 203;

[0023] A first winding starting point 15 , a second winding starting point 16 , a third winding starting point 17 , a first winding end point 18 , a first bending segment 14 , a second bending segment 11 , a first straight segment 13 , and a second straight segment 12 . DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0025] In the description of the present invention, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0026] In the description of the present utility model, "several" means more than one, "many" means more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used to distinguish the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0027] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0028] In the description of the present invention, reference terms such as "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention.

[0029] refer to Figure 1 According to the first embodiment of the utility model, the battery cell includes: a body, which is formed by stacking a first pole piece 101, a separator 103 and a second pole piece 102 and then winding them; the first pole piece 101 includes a first section 104, a second section 105 and a third section 106, the two ends of the second section 105 are respectively connected to the first section 104 and the third section 106, and the third section 106 has a first active material layer 107 on both sides along the thickness direction, and the second section 105 has the first active material layer 107 only on the side away from the first section 104, and the first section 104 does not have the first active material layer 107, wherein the first section 104 has the first active material layer 107, and the second section 104 has the first active material layer 107. One end of the first section 104 away from the second section 105 is the first winding starting point 15 of the first pole piece 101, and one end of the third section 106 away from the second section 105 is the first winding end point 18 of the first pole piece 101; the first section 104 includes a first bending section 14, a second bending section 11, a first straight section 13 and a second straight section 12, the two ends of the first bending section 14 are respectively connected to the second section 105 and the first straight section 13, the two ends of the second bending section 11 are respectively connected to the first straight section 13 and the second straight section 12, and the end of the second straight section 12 away from the second bending section 11 is the first winding starting point 15. The first pole piece 101 has a first bending section 14 and a second bending section 11, that is, after the first pole piece 101 is bent twice, when the first pole piece 101 is wound, the provision of the second bending section 11 can effectively avoid the problem of the first pole piece 101 being offset or wrinkled during winding, so that the battery cell can have a higher quality.

[0030] The first active material layer 107 has a high lithium ion reserve and can accommodate more lithium ions, which helps to increase the capacity of the battery cell. Secondly, the first active material layer 107 has excellent lithium ion deintercalation-intercalation performance. During the charge and discharge process, lithium ions can be smoothly embedded and deintercalated in the active material layer without damaging the material structure. In addition, the first active material layer 107 also has a good lithium ion diffusion rate and electronic conductivity, which helps to reduce polarization and increase the charge and discharge current, thereby ensuring that the battery cell has good performance. The use of the first active material layer 107 can make the battery cell stable and have a long life.

[0031] It should be noted that when the first pole piece 101 and the second pole piece 102 of the battery cell are unfolded, the unfolding direction of the first pole piece 101 and the second pole piece 102 is the length direction of the first pole piece 101 and the second pole piece 102, which is also the width direction of the battery cell; the direction perpendicular to the unfolding direction of the first pole piece 101 and the second pole piece 102 is the width direction of the first pole piece 101 and the second pole piece 102, which is also the length direction of the battery cell, and the extending direction is parallel to the length direction of the battery cell.

[0032] It should be noted that in some embodiments of the utility model, the first pole piece 101 is a negative pole piece. The negative electrode plays the role of storing and releasing lithium ions during the charging and discharging process. In the process of winding the battery cell, winding the negative electrode first can ensure that the active material of the negative electrode is in full contact with the electrolyte, so that the lithium ions are more effectively embedded and de-embedded, which helps to improve the energy density and cycle performance of the battery cell. Secondly, from the perspective of structural stability, the negative electrode material may expand and shrink in volume during the charging and discharging process. If the positive electrode is rolled first and then the negative electrode, the negative electrode material may be compressed by the positive electrode during expansion, resulting in structural damage and decreased battery cell performance. However, if the negative electrode is rolled first, a certain amount of space can be reserved to accommodate the volume change of the negative electrode material during the charging and discharging process, thereby maintaining the stability of the battery cell structure. Therefore, setting the first pole piece 107 as a negative pole piece helps to improve the electrochemical performance and structural stability of the battery cell, and ensure that the battery cell has better performance and service life.

[0033] refer to Figure 1In some embodiments of the present invention, the isolation film 103 includes a first end and a second end, the first end is the second winding starting point 16 of the isolation film 103, along the width direction of the battery cell, the first end protrudes relative to the second straight line segment 12 away from one end of the second bending segment 11, and the distance between the second winding starting point 16 and the first winding starting point 15 is L1, 5mm≤L1≤10mm. For example, L1 can be 5mm, 6mm, 8mm or 10mm. Due to factors such as heating, charging and discharging, the second winding starting point 16 will be in a retracted state. In order to prevent the first pole piece 101 from contacting the second pole piece 102 and causing a short circuit, the second winding starting point 16 is designed to extend 5mm-10mm compared to the first winding starting point 15, which can effectively prevent the impact of the retraction of the second winding starting point 16. When L1 is less than 5mm, the retraction of the second winding starting point 16 may cause the first winding starting point 15 to contact the second pole piece 102, thereby causing a short circuit; if L1 is designed to be greater than 10mm, unnecessary material consumption will increase, increasing production costs.

[0034] It should be noted that in conventional battery cells, the isolation membrane 103 will first be wound half a circle, bent once, and then drive the head of the first pole piece 101 to be wound. The size of the half circle in the conventional battery cell is much larger than 10 mm. The battery cell of the embodiment of the utility model cancels the half circle pre-winding of the isolation membrane 103, thereby reducing material loss and reducing costs.

[0035] refer to Figure 1 In some embodiments of the present invention, along the width direction of the battery cell, the length of the second straight segment 12 is L2, 1mm≤L2≤10mm. The length of the second straight segment 12 is set between 1-10mm to improve the stability of the position of the first winding starting point 15. When L2 is less than 1mm, it may cause the first winding starting point 15 to retract into the second bending segment 11 or retract into the first straight segment 13, reducing the stability of the position of the first winding starting point 15; when L2 is greater than 10mm, it will increase unnecessary material consumption and increase production costs.

[0036] refer to Figure 1 In some embodiments of the present invention, two isolation films 103 are provided, and the two isolation films 103 are respectively located on both sides of the first pole piece 101. The isolation films 103 are provided on both sides of the first pole piece 101 to ensure that the first pole piece 101 and the second pole piece 102 at any position of the wound battery cell can be effectively isolated to prevent the occurrence of a short circuit.

[0037] refer to Figure 2In some embodiments of the present invention, the isolation film 103 includes a polyolefin layer 201, a PVDF adhesive layer 202 and a ceramic layer 203. The PVDF adhesive layer 202 has two layers, and the two PVDF adhesive layers 202 are respectively bonded to the opposite sides of the polyolefin layer 201. The ceramic layer 203 has one layer, and the ceramic layer 203 is bonded to the side of one of the PVDF adhesive layers 202 away from the polyolefin layer 201. The polyolefin material has good toughness and can effectively prevent short circuits inside the battery cell. Secondly, the polyolefin material has excellent chemical stability and can resist corrosion from a variety of chemical substances, ensuring that the battery cell can work stably under various environmental conditions. In addition, the polyolefin separator has a high porosity, which is conducive to the free movement of ions, thereby improving the charge and discharge efficiency of the battery cell. The PVDF adhesive layer 202 has excellent chemical resistance, can work stably in the battery core, is not easily corroded by electrolyte or other chemicals, has high strength and toughness, can effectively prevent short circuit and electrolyte leakage inside the battery core, ensure the safe operation of the battery core, and also has many excellent properties such as high porosity and ion conductivity, easy processing, environmental protection, etc. The ceramic layer 203 has high strength and toughness, and can effectively prevent sharp objects from piercing the isolation membrane 103 to cause a short circuit.

[0038] It should be noted that in some embodiments of the present invention, polypropylene or polyethylene is preferably used for the polyolefin layer 201. Polypropylene and polyethylene have better heat resistance, processing performance and chemical stability than other polyolefin materials, and can still maintain their good performance in the battery core.

[0039] refer to Figure 1 In some embodiments of the utility model, the battery cell further includes a first pole ear 110, and the first pole ear 110 is connected to the first straight line segment 13. The first pole ear 110 is the contact point when the battery cell is charged and discharged, and is responsible for drawing the current from the positive electrode, flowing through the inside of the battery cell, and finally reaching the negative electrode to form a complete circuit. This ensures the electrical connection between the inside and outside of the battery cell, so that the battery cell can work normally. At the same time, the excellent conductivity of the first pole ear 110 can ensure the smooth flow of current in the battery cell, thereby ensuring the stability and performance of the battery cell. The design of the first pole ear 110 can reduce the internal resistance of the battery cell and reduce the energy loss of the battery cell during operation, thereby improving the energy utilization and efficiency of the battery cell.

[0040] It should be noted that in some embodiments of the present invention, the first pole ear 110 is made of nickel, which has good conductivity and excellent corrosion resistance, and good welding performance, can improve the stability of the battery cell structure, has relatively low cost, and is conducive to reducing production costs.

[0041] refer to Figure 1In some embodiments of the present invention, the battery cell further comprises a first adhesive layer 113, which is bonded to the first pole tab 110 and the first straight segment 13. The first adhesive layer 113 can effectively prevent the first pole tab 110 from piercing the isolation film 103 and contacting the second pole piece 102 to cause a short circuit.

[0042] refer to Figure 1 In some embodiments of the utility model, the second pole piece 102 includes a second active material layer 108, the second active material layer 108 covers part of the second pole piece 102, the second pole piece 102 includes a fourth section 114, one end of the fourth section 114 is the third winding starting point 17 of the second pole piece 102, the fourth section 114 does not have the second active material layer 108, and the battery cell also includes a second pole ear 109, and the second pole ear 109 is connected to the fourth section 114. The second active material layer 108 and the first active material layer 107 are responsible for storing and releasing energy, the second pole piece 102 and the first pole piece 101 ensure that energy is efficiently transmitted to the external circuit, and improve the conductivity of the battery cell. The second pole ear 109 is the contact point when the battery cell is charged and discharged, and is responsible for drawing the current from the positive electrode, flowing through the inside of the battery cell, and finally reaching the negative electrode to form a complete circuit. This ensures the electrical connection between the inside and outside of the battery cell, so that the battery cell can work normally. At the same time, the excellent conductivity of the second pole ear 109 can ensure the smooth flow of current in the battery cell, thereby ensuring the stability and performance of the battery cell. The design of the second pole ear 109 can reduce the internal resistance of the battery cell and reduce the energy loss of the battery cell during operation, thereby improving the energy utilization and efficiency of the battery cell.

[0043] It should be noted that in some embodiments of the utility model, the material used for the second pole ear 109 is aluminum. Aluminum has good electrical conductivity, can effectively transmit electrons, and ensure the stable flow of current inside the battery. Secondly, the mechanical strength of aluminum material is relatively high. The second pole ear 109 needs to withstand the vibration of the battery cell, and the strength of aluminum can ensure that it can remain stable under various working conditions and is not prone to deformation or breakage. Another important advantage is that a layer of oxide protective film can be formed on the surface of aluminum. This protective film can effectively prevent aluminum from being further oxidized and maintain its stability and conductivity. Aluminum is a relatively common and inexpensive metal, which makes it possible to reduce production costs while ensuring performance using aluminum as the second pole ear 109.

[0044] It should be noted that, in some embodiments of the present invention, the extension direction of the first pole tab 110 and the second pole tab 109 is parallel to the length direction of the battery cell.

[0045] refer to Figure 1In some embodiments of the present invention, the battery cell further comprises a second adhesive layer 111, which is bonded to the second pole tab 109 and the fourth section 114. The second adhesive layer 111 can effectively prevent the second pole tab 109 from piercing the isolation film 103 and contacting the first pole piece 101 to cause a short circuit.

[0046] refer to Figure 1 In some embodiments of the present invention, the battery cell also includes a third adhesive layer 112, which is bonded to the first pole piece 101 of the adjacent outer circle opposite to the second pole ear 109, also to prevent the second pole ear 109 from piercing the isolation membrane 103 and contacting the first pole piece 101 to cause a short circuit.

[0047] The battery according to the second embodiment of the utility model includes any one of the battery cells in the first embodiment. In this way, the first pole piece 101 is bent twice by the first bending section 14 and the second bending section 11, so that the position of the first winding starting point 15 is more stable, and it is not easy to have problems such as poor position of the pole ear margin caused by position offset and wrinkling of the head, thereby improving the quality of the battery cell. Furthermore, the battery formed by the battery cell has better quality.

[0048] The embodiments of the utility model are described in detail above in conjunction with the accompanying drawings, but the utility model is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

Claims

1. A battery cell, characterized in that: The battery cell comprises: A body, wherein the body is formed by stacking a first pole piece, a separator and a second pole piece and then winding them; The first pole piece includes a first section, a second section and a third section, two ends of the second section are connected to the first section and the third section respectively, both sides of the third section along the thickness direction have a first active material layer, only one side of the second section away from the first section has the first active material layer, and the first section does not have the first active material layer, wherein an end of the first section away from the second section is a first winding starting point of the first pole piece, and an end of the third section away from the second section is a first winding end point of the first pole piece; The first section includes a first bending section, a second bending section, a first straight section and a second straight section, two ends of the first bending section are respectively connected to the second section and the first straight section, two ends of the second bending section are respectively connected to the first straight section and the second straight section, and the end of the second straight section away from the second bending section is the first winding starting point.

2. The battery cell according to claim 1, characterized in that: The isolation film includes a first end, which is the second winding starting point of the isolation film. Along the width direction of the battery cell, the first end protrudes relative to the second straight line segment and away from one end of the second bending segment. The distance between the second winding starting point and the first winding starting point is L1, 5mm≤L1≤10mm.

3. The battery cell according to claim 2, characterized in that: Along the width direction of the battery core, the length of the second straight line segment is L2, 1mm≤L2≤10mm.

4. The battery cell according to claim 1, characterized in that: Two isolation membranes are provided, and the two isolation membranes are respectively located on both sides of the first pole piece.

5. The battery cell according to claim 1, characterized in that: The isolation membrane includes a polyolefin layer, a PVDF adhesive layer and a ceramic layer. The PVDF adhesive layer has two layers, and the two PVDF adhesive layers are respectively bonded to the opposite sides of the polyolefin layer. The ceramic layer has one layer, and the ceramic layer is bonded to the side of one of the PVDF adhesive layers away from the polyolefin layer.

6. The battery cell according to claim 1, characterized in that: The battery cell further includes a first pole tab, which is connected to the first straight line segment.

7. The battery cell according to claim 6, characterized in that: The battery core further includes a first adhesive layer, and the first adhesive layer is bonded to the first electrode tab and the first straight line segment.

8. The battery cell according to claim 1, characterized in that: The second pole piece includes a fourth section, one end of the fourth section is a third winding starting point of the second pole piece, the fourth section does not have a second active material layer, and the battery cell also includes a second pole ear connected to the fourth section.

9. The battery cell according to claim 8, characterized in that: The battery core further includes a second adhesive layer, and the second adhesive layer is bonded to the second electrode tab and the fourth segment.

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

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