A battery cell and a battery

Abstract

The utility model discloses a battery cell and a battery. The battery cell of the utility model comprises a positive electrode sheet, a negative electrode sheet and a diaphragm. The battery cell has a set length direction, a width direction and a thickness direction. The two ends of the battery cell along the length direction are respectively a first end and a second end. The positive electrode sheet and the negative electrode sheet are both provided with a pole ear, which extends from the first end. The diaphragm is provided between the positive electrode sheet and the negative electrode sheet. The diaphragm comprises a plurality of extension sections stacked along the thickness direction. At least one end of the extension section has a bonding portion. Along the length direction of the battery cell, the bonding portion exceeds the edge of the negative electrode sheet. Along the thickness direction of the battery cell, adjacent bonding portions are bonded to each other, so that the plurality of bonding portions are connected as one body, the connection strength is good and the stability is good. When the battery falls, the plurality of bonding portions bonded as one body can hinder the diaphragm from moving along the length direction of the battery cell to the side away from the bonding portion, so as to prevent the short circuit in the battery cell caused by the contact between the positive and negative electrode sheets.

Description

Technical Field

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

[0002] In the related art, drop resistance is one of the important safety indicators for evaluating secondary batteries. Generally, the battery is tested through a drop test. After the battery falls, the diaphragm may be folded or misaligned with the pole piece, resulting in direct contact between pole pieces of different polarities and internal short circuit, followed by a large amount of heat in the battery and even fire. In order to avoid the above situation, the prior art fixes the diaphragm by pasting a strip of hot melt adhesive on the end of the battery cell to prevent the diaphragm from being misaligned with the pole piece. However, the strip of hot melt adhesive has a weak restraining ability on the diaphragm, and it may still fall off when used for a long time or subjected to a large impact force, and cannot achieve a good protection effect. 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 prevent the pole piece and the diaphragm from being misaligned and has good stability.

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

[0005] According to the battery cell of the first aspect embodiment of the utility model, the battery cell has set length direction, width direction and thickness direction, the two ends of the battery cell along the length direction are respectively a first end and a second end, the battery cell comprises a positive electrode sheet, a negative electrode sheet and a separator, the positive electrode sheet and the negative electrode sheet are both provided with pole ears, the pole ears extend from the first end, the separator is arranged between the positive electrode sheet and the negative electrode sheet, the separator comprises a plurality of extension sections stacked along the thickness direction, at least one end of the extension section has a bonding portion, along the length direction of the battery cell, the bonding portion exceeds the edge of the negative electrode sheet, along the thickness direction of the battery cell, the adjacent bonding portions are bonded to each other.

[0006] The battery cell according to the embodiment of the utility model has at least the following beneficial effects: the diaphragm includes a plurality of stacked extension sections, the extension sections include bonding portions, along the length direction of the battery cell, the bonding portions extend beyond the edge of the negative electrode sheet, along the thickness direction of the battery cell, adjacent bonding portions are bonded to each other, so that the plurality of bonding portions are connected as one, the connection strength is good and the stability is good, when the battery falls, the plurality of bonding portions bonded as one can hinder the movement of the diaphragm along the length direction of the battery cell away from the side where the bonding portions are located, thereby preventing a short circuit in the battery cell caused by contact between the positive and negative electrode sheets.

[0007] According to some embodiments of the present invention, the bonding portion includes a bonding area, and along the thickness direction of the battery core, at least one side of the bonding area is coated with an adhesive layer, and the adhesive layer is bonded to the adjacent bonding portion.

[0008] According to some embodiments of the present invention, the bonding portion includes multiple bonding areas and multiple avoidance areas. The bonding areas and the avoidance areas are arranged in sequence along the width direction of the battery cell, and gaps are defined between adjacent avoidance areas along the thickness direction of the battery cell.

[0009] According to some embodiments of the present invention, along the thickness direction of the battery core, the size of the glue layer is 10 μm to 30 μm.

[0010] According to some embodiments of the utility model, the extension section also includes an extension portion, and the extension portion and the bonding portion are arranged in sequence along the length direction of the battery cell. The extension portion exceeds the edge of the negative electrode sheet, and the ratio of the extension portion to the bonding area size is 1:9 to 4:1.

[0011] According to some embodiments of the present invention, along the length direction of the battery core, both ends of the extension section have bonding portions.

[0012] According to some embodiments of the present invention, the separator, the positive electrode sheet and the negative electrode sheet are wound to form the battery cell, and the separator further includes a plurality of bending segments, and the bending segment connects two adjacent extending segments along the thickness direction of the battery cell.

[0013] According to some embodiments of the present invention, adjacent bent sections are bonded to each other along the thickness direction of the battery core.

[0014] According to some embodiments of the present invention, the number of the positive electrode sheet and the number of the negative electrode sheet are both plural, and the positive electrode sheet and the negative electrode sheet are stacked in sequence along the thickness direction of the battery cell.

[0015] A battery according to a second embodiment of the present invention includes:

[0016] case;

[0017] The battery cell provided in the first aspect of the embodiment is accommodated in the shell.

[0018] The battery according to the embodiment of the utility model has at least the following beneficial effects: the battery includes the battery cell provided by the above-mentioned first aspect embodiment, and at least has all the advantages of the battery cell, and while the drop resistance of the battery cell is improved, the drop resistance of the battery is also improved.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0021] Figure 1 A schematic diagram of a battery cell according to an embodiment of the utility model;

[0022] Figure 2 This is a front view of a battery cell according to an embodiment of the utility model;

[0023] Figure 3 It is a schematic diagram of the diaphragm according to an embodiment of the utility model.

[0024] Reference numerals:

[0025] Diaphragm 100, extension section 110, bonding portion 111, bonding area 1111, avoidance area 1112, adhesive layer 1113, extension section 112, bending section 120;

[0026] Tab 200. DETAILED DESCRIPTION

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] In the description of the utility model, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example 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.

[0032] Reference Figure 1 and Figure 2 The first aspect of the utility model provides a battery cell, which has a set length direction, width direction and thickness direction. The two ends of the battery cell along the length direction are respectively a first end and a second end. The battery cell includes a positive electrode sheet, a negative electrode sheet, a diaphragm 100 and a suture line. The positive electrode sheet and the negative electrode sheet are both provided with a pole ear 200, and the pole ear 200 extends from the first end. The diaphragm 100 is arranged between the positive electrode sheet and the negative electrode sheet. The diaphragm 100 includes a plurality of extension sections 110 stacked along the thickness direction. At least one end of the extension section 110 has a bonding portion 111. Along the length direction of the battery cell, the bonding portion 111 exceeds the edge of the negative electrode sheet. Along the thickness direction of the battery cell, adjacent bonding portions 111 are bonded to each other.

[0033] The diaphragm 100 includes a plurality of stacked extension sections 110, and the extension sections 110 include bonding portions 111. Along the length direction of the battery cell, the bonding portions 111 extend beyond the edge of the negative electrode sheet, and along the thickness direction of the battery cell, adjacent bonding portions 111 are bonded to each other, so that the plurality of bonding portions 111 are connected as a whole, and the connection strength is good and the connection has good stability. When the battery falls, the plurality of bonding portions 111 bonded as a whole can hinder the movement of the diaphragm 100 along the length direction of the battery cell away from the side where the bonding portions 111 are located, thereby preventing a short circuit in the battery cell caused by contact between the positive and negative electrode sheets.

[0034] Reference Figure 3In some embodiments, the bonding portion 111 includes a bonding area 1111, and along the thickness direction of the battery cell, at least one side of the bonding area 1111 is coated with a glue layer 1113, and the glue layer 1113 is bonded to the adjacent bonding portion 111. The glue layer 1113 can be pre-coated on the bonding area 1111, and after a plurality of extension segments 110 are stacked, the glue layer 1113 is bonded to the adjacent bonding portions 111, thereby achieving bonding and fixing of the adjacent extension segments 110. Specifically, the glue layer 1113 can be selected as a hot melt adhesive. After the glue layer 1113 is applied to the diaphragm 100, the diaphragm 100 is combined with the positive electrode sheet and the negative electrode sheet to form a battery cell, and then the battery cell is hot pressed so that the glue layer 1113 can be bonded to the adjacent bonding portions 111.

[0035] Reference Figure 3 In some embodiments, the bonding portion 111 includes a plurality of bonding areas 1111 and a plurality of avoidance areas 1112. The bonding areas 1111 and the avoidance areas 1112 are sequentially arranged along the width direction of the battery cell. A gap is defined between adjacent avoidance areas 1112 along the thickness direction of the battery cell, thereby forming a channel for the flow of electrolyte. When the battery cell is applied to a battery, the electrolyte can flow in through the gap between adjacent avoidance areas 1112 to infiltrate the positive electrode sheet and the negative electrode sheet. While ensuring that the adjacent bonding portions 111 are bonded and fixed by the adhesive layer 1113, the problem of lithium deposition caused by insufficient electrolyte infiltration of the electrode sheet can be avoided. Specifically, the sum of the areas of all mutually bonded bonding portions 111 accounts for 40%-60% of the total area of ​​the end of the battery cell along the length direction, so that the electrode sheet can be fully infiltrated while ensuring the bonding effect.

[0036] Among them, when the dimensions of the battery cell along the width direction are different, the distance between two adjacent bonding areas 1111 may also change accordingly. Therefore, the thickness and spacing of the two bonding areas 1111 must ensure good bonding effect while ensuring the electrode is infiltrated by the electrolyte, which can be determined based on actual conditions.

[0037] In addition, the portion of the diaphragm 100 that extends beyond the electrode sheets along the length direction of the battery cell can store electrolyte. When the electrolyte decreases in the later stage of the battery cycle, the portion of the diaphragm 100 that extends beyond the electrode sheets can still provide a certain amount of electrolyte for the positive and negative electrode sheets, thereby extending the time for lithium deposition to occur in the battery cell and extending the service life of the battery.

[0038] In some embodiments, along the thickness direction of the battery cell, the size of the glue layer 1113 is 10 μm to 30 μm. The size of the glue layer 1113 can be selected to be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm or any other value between 10 μm and 30 μm. The size of the glue layer 1113 should not be too large or too small. When the size of the glue layer 1113 is too small, for example, less than 10 μm, the adhesive force provided by the glue layer 1113 is insufficient, and the adjacent adhesive portions 111 are easily separated when impacted or stressed, and the effect of preventing the diaphragm 100 from moving is not achieved; and when the size of the glue layer 1113 is too large, it may cause the size of multiple adhesive portions 111 along the thickness direction of the battery cell to increase, resulting in an uneven outer surface of the battery cell, which may affect the shelling process of the battery cell when the battery cell is used in a battery. Therefore, the size of the glue layer 1113 along the thickness direction of the battery core is selected to be 10 μm to 30 μm, which can ensure the bonding strength of the glue layer 1113 while not significantly increasing the thickness of the multi-layer bonding part 111, thereby achieving a better bonding effect.

[0039] Reference Figure 2 ,in, Figure 2 The dotted line in is only for the convenience of distinguishing the bonding portion 111 and the extension portion 112, and cannot be considered as the outline of the battery cell. In some embodiments, the extension section 110 also includes an extension portion 112. Along the length direction of the battery cell, the extension portion 112 and the bonding portion 111 are arranged in sequence, and the extension portion 112 exceeds the edge of the negative electrode sheet. The ratio of the size of the extension portion 112 to the bonding area 1111 is 1:9 to 4:1. Along the length direction of the battery cell, the proportion of the bonding portion 111 to the portion of the extension section 110 that exceeds the edge of the negative electrode sheet is 20% to 90%. Specifically, the proportion of the bonding portion 111 to the portion of the extension section 110 that exceeds the edge of the negative electrode sheet can be selected as 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or any other value between 20% and 90%. For example, when the dimension exceeding the edge of the negative electrode sheet is 10 mm, the dimension of the bonding portion 111 can be selected to be 2 mm to 9 mm, so as to reserve sufficient coating space for the glue layer 1113 and ensure that the glue layer 1113 has sufficient bonding area, while avoiding contact between the glue layer 1113 and the positive electrode sheet and the negative electrode sheet, which would affect the electrical performance of the battery cell.

[0040] In some embodiments, along the length direction of the battery cell, both ends of the extension section 110 have a bonding portion 111, and both ends of the multiple extension sections 110 extend beyond the negative electrode sheet and are bonded together through an adhesive layer 1113, thereby ensuring that when the battery cell falls, both ends of the diaphragm 100 along the length direction of the battery cell will not be misaligned relative to the electrode sheet, so that the positive electrode sheet and the negative electrode sheet are always separated by the diaphragm 100, thereby ensuring the safety performance of the battery cell.

[0041] In some embodiments, the battery cell may be a wound structure battery cell, wherein the separator 100, the positive electrode sheet and the negative electrode sheet are wound to form the battery cell, and the separator 100 further comprises a plurality of bent sections 120, wherein the bent sections 120 connect two adjacent extension sections 110 along the thickness direction of the battery cell. When the battery cell is a wound structure battery cell, the adhesive layer 1113 may be continuously coated in the length direction of the separator 100, and the adhesive layer 1113 is selected as a hot melt adhesive. After the separator 100, the positive electrode sheet and the negative electrode sheet are wound to form the battery cell, a part of the battery cell is hot pressed, and then the adhesive layer 1113 is coated on the separator 100 and the hot pressed area forms a bonding area 1111, while the hot melt adhesive coated on the area not hot pressed has no bonding effect and forms an avoidance area 1112, so that the electrolyte can flow between adjacent avoidance areas 1112, thereby simplifying the step of coating the adhesive layer 1113 on the separator 100, and no intermittent coating is required in the length direction of the separator 100.

[0042] In some embodiments, adjacent bending sections 120 are bonded to each other along the thickness direction of the battery cell. The bending area may also be provided with a portion extending beyond the negative electrode sheet, and the size extending beyond the negative electrode sheet may be the same as the size extending beyond the negative electrode sheet of the bonding portion 111. When applying the colloid, it may be applied continuously along the length direction of the separator 100, so that the adjacent bending areas along the thickness direction of the battery cell can also be bonded to form a whole, thereby further increasing the fixing effect of the end of the separator 100.

[0043] In other embodiments, the battery cell may be a stacked structure battery cell, wherein the number of positive and negative electrode sheets are both multiple, and the positive and negative electrode sheets are stacked in sequence along the thickness direction of the battery cell. In this case, the number of diaphragms 100 may be multiple, and each diaphragm 100 includes a bonding portion 111, and a diaphragm 100 is arranged between adjacent positive and negative electrode sheets. The multiple diaphragms 100 are bonded together by a glue layer 1113, or, the number of diaphragms 100 is one, and the diaphragm 100 is folded in a "Z" shape, and the diaphragm 100 includes multiple stacked extension portions 112, and the extension portion 112 is arranged between the positive electrode sheet and the negative electrode sheet.

[0044] The second aspect of the present invention provides a battery (not shown in the figure), including a shell and the battery cell provided by the first aspect of the embodiment, and the battery cell is accommodated in the shell. The battery includes the battery cell provided by the first aspect of the embodiment, and at least has all the advantages of the battery cell. While the anti-drop performance of the battery cell is improved, the anti-drop performance of the battery is also improved. The above is a detailed description of the embodiment of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiment. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A battery cell, characterized in that: The battery cell has set length, width and thickness directions, and the two ends of the battery cell along the length direction are respectively a first end and a second end. The battery cell includes a positive electrode sheet, a negative electrode sheet and a separator. Both the positive electrode sheet and the negative electrode sheet are provided with pole ears, and the pole ears extend from the first end. The separator is arranged between the positive electrode sheet and the negative electrode sheet. The separator includes a plurality of extension sections stacked along the thickness direction. Along the length direction of the battery cell, at least one end of the extension section has a bonding portion, and the bonding portion extends beyond the edge of the negative electrode sheet. Along the thickness direction of the battery cell, adjacent bonding portions are bonded to each other.

2. The battery cell according to claim 1, characterized in that: The bonding portion comprises a bonding area, and along the thickness direction of the battery core, at least one side of the bonding area is coated with an adhesive layer, and the adhesive layer is bonded to the adjacent bonding portion.

3. The battery cell according to claim 2, characterized in that: The bonding portion includes a plurality of bonding areas and a plurality of avoidance areas. The bonding areas and the avoidance areas are arranged in sequence along the width direction of the battery core. A gap is defined between adjacent avoidance areas along the thickness direction of the battery core.

4. The battery cell according to claim 2, characterized in that: Along the thickness direction of the battery core, the size of the glue layer is 10 μm to 30 μm.

5. The battery cell according to claim 2, characterized in that: The extension section also includes an extension portion, and along the length direction of the battery cell, the extension portion and the bonding portion are arranged in sequence, the extension portion exceeds the edge of the negative electrode sheet, and the ratio of the extension portion to the bonding area is 1:9 to 4:

1.

6. The battery cell according to any one of claims 1 to 5, characterized in that: Along the length direction of the battery core, both ends of the extension section have bonding parts.

7. The battery cell according to any one of claims 1 to 5, characterized in that: The separator, the positive electrode sheet and the negative electrode sheet are wound to form the battery cell. The separator further comprises a plurality of bending sections, and the bending section connects two adjacent extending sections along the thickness direction of the battery cell.

8. The battery cell according to claim 7, characterized in that: Along the thickness direction of the battery core, adjacent bent sections are bonded to each other.

9. The battery cell according to any one of claims 1 to 5, characterized in that: There are multiple positive electrode sheets and multiple negative electrode sheets, and the positive electrode sheets and the negative electrode sheets are stacked in sequence along the thickness direction of the battery cell.

10. A battery, characterized in that include: case; The battery cell according to any one of claims 1 to 9 is accommodated in the shell.

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