Current collector, battery cell and battery

Abstract

The embodiment of the present invention provides a current collector, a battery cell and a battery, wherein the current collector comprises a main structure, a strength weakening band is provided on the main structure, and the strength weakening band separates the main structure into at least two parts, and any two parts of the at least two parts are connected by a conductive material. When the current collector provided by the embodiment of the present invention is used in a battery, it helps to avoid the situation where the positive electrode plate and the negative electrode plate are in contact and short-circuited due to non-breakage or partial breakage through the damaged diaphragm, thereby improving the safety of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a current collector, a battery cell and a battery. Background Art

[0002] Lithium batteries have been widely used due to their advantages such as high energy density. The battery cell of a lithium battery is mainly composed of a positive electrode sheet, a negative electrode sheet and a diaphragm. Since the diaphragm is relatively weaker than the positive electrode sheet and the negative electrode sheet, in the event of an accident, the diaphragm may be damaged in some parts of the battery cell, and the positive electrode sheet and the negative electrode sheet may be in contact and short-circuited due to not being broken or partially breaking through the broken diaphragm. It can be seen that the existing lithium batteries have the defect of low safety. Summary of the invention

[0003] The embodiments of the present invention provide a current collector, a battery cell and a battery to solve the problem of low safety of existing lithium batteries.

[0004] In order to solve the above-mentioned technical problems, the present invention is achieved as follows:

[0005] An embodiment of the present invention provides a current collector, including a main structure, on which a strength weakening band is provided, the strength weakening band separates the main structure into at least two parts, and any two of the at least two parts are connected by a conductive material.

[0006] An embodiment of the present invention further provides a battery cell, including a pole piece, wherein the pole piece includes the above-mentioned current collector.

[0007] An embodiment of the present invention further provides a battery, comprising the above-mentioned battery cell.

[0008] In an embodiment of the present invention, a strength weakening band is provided on the main structure of the current collector, and the strength weakening band separates the main structure into at least two parts; when subjected to a destructive force, the main structure of the current collector can be broken as a whole at the strength weakening band; the current collector provided in this embodiment, when used in a battery, helps to avoid the situation where the positive electrode plate and the negative electrode plate are in contact and short-circuited due to non-breakage or partial breakage through a damaged diaphragm, thereby improving the safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A schematic diagram of the structure of a current collector provided in an embodiment of the present invention;

[0010] Figure 2 Schematic diagram of the structure of the positive electrode current collector and the negative electrode current collector in an embodiment of the present invention;

[0011] Figure 3 A schematic diagram of the structure of the positive electrode sheet and the negative electrode sheet in an embodiment of the present invention;

[0012] Figure 4 Schematic diagram of the assembly structure of the positive electrode sheet, the negative electrode sheet and the diaphragm in an embodiment of the present invention;

[0013] Figure 5 Schematic diagram of the structure of the winding core in an embodiment of the present invention. DETAILED DESCRIPTION

[0014] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail in conjunction with the accompanying drawings and specific embodiments. In the following description, specific details such as specific configurations and components are provided only to help fully understand the embodiments of the present invention. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. In addition, for clarity and brevity, the description of known functions and structures is omitted.

[0015] like Figure 1 As shown, the current collector 100 provided in an embodiment of the present invention includes a main structure 110, on which a strength weakening band 120 is provided, and the strength weakening band 120 separates the main structure 110 into at least two parts, and any two of the at least two parts are connected by conductive material.

[0016] It is easy to understand that the current collector is a component used to collect current, and the main structure it includes can be a metal foil, such as copper foil or aluminum foil. The strength of the main structure of the existing current collector is usually equal at all places. When subjected to destructive force, it usually breaks at the main force position, and remains connected at the position where the force is lighter or not. In combination with practical applications, taking a lithium battery with a current collector as an example, since the strength of the diaphragm in the lithium battery is usually lower than that of the current collector, under the action of destructive force, the length of the damaged position of the diaphragm is usually greater than the length of the broken position of the current collector, and the strength of the positive and negative pole pieces of the lithium battery is mainly provided by the current collector. Therefore, it is easy for the unbroken part of the positive pole piece of the lithium battery and the unbroken part of the negative pole piece to contact each other through the broken diaphragm and short-circuit. In this short-circuit situation, mild phenomena such as heating and swelling will occur, and severe cases will cause the battery to smoke and catch fire, bringing greater safety problems.

[0017] In this embodiment, a weakened zone 120 is provided on the main structure 110 included in the current collector 100 , and the strength of a portion of the main structure 110 corresponding to the weakened zone 120 is lower than the strength of other portions of the main structure 110 .

[0018] The strength weakening band 120 separates the main structure 110 into at least two parts, and any two parts of the at least two parts are connected by a conductive material; for the convenience of explanation, each part of the at least two parts is defined as a first part. It is easy to understand that for a current collector, multiple first parts are only separated by the strength weakening band 120, and they can still be conductive to each other. For example, the first part and the strength weakening band 120 are both components of the main structure 110, and the first part and the solid part of the strength weakening band 120, that is, the first part and the conductive material can be connected as one body, but the strength weakening band 120 is set so that the corresponding areas of different first parts on the main structure 110 are not continuous; for another example, the first part can be a conductive structure such as a metal foil, and the strength weakening band 120 can be a non-conductive structure such as plastic. By coating the conductive material on the strength weakening band 120, two adjacent first parts can be conductive. When the current collector 100 is hit by a relatively severe external force, the main structure 110 can be completely broken at the strength weakening band 120. When the current collector 100 provided in this embodiment is used in a lithium battery, it can effectively avoid short circuits caused by the unbroken parts of the positive electrode sheet and the unbroken parts of the negative electrode sheet contacting each other.

[0019] In an embodiment of the present invention, a strength weakening band is provided on the main structure of the current collector, and the strength weakening band separates the main structure into at least two parts; when subjected to a destructive force, the main structure of the current collector can be broken as a whole at the strength weakening band; the current collector provided in this embodiment, when used in a battery, helps to avoid the situation where the positive electrode plate and the negative electrode plate are in contact and short-circuited due to non-breakage or partial breakage through a damaged diaphragm, thereby improving the safety of the battery.

[0020] In some feasible embodiments, the number of the strength weakening bands 120 provided on the main structure 110 may be one or more; and the extension direction of the strength weakening bands 120 provided on the main structure 110 may be along the length direction or width direction of the main structure 110, or along the oblique direction or the curved direction, etc., so as to separate the main structure 110 into at least two parts, so that the main structure 110 can be broken as a whole when subjected to destructive force.

[0021] In one application example, the strength weakening tape 120 extends along the length direction of the main structure 110 of the current collector 100, that is, the extension direction of the strength weakening tape 120 is parallel to the length direction of the main structure 110, and the main structure 110 is divided into two parts arranged oppositely in the width direction. When the current collector 100 is used in a battery with a wound battery cell, the current collector 100 in a strip shape in the initial state can be wound, so that the strength weakening tape 120 on the main structure 110 of the wound current collector 100 can be distributed on the same cross section, so that when subjected to a destructive force, the above-mentioned main structure 110 can be broken as a whole.

[0022] Also taking the above application example, the number of the strength weakening tape 120 can be one, so as to ensure that the main structure 110 can be broken as a whole; the number of the strength weakening tape 120 can also be multiple, and multiple strength weakening tapes 120 can be arranged in parallel. In this way, when the wound current collector 100 is subjected to destructive force at different positions, it can be broken at the corresponding cross-section, thereby further improving the safety of the battery.

[0023] Further optionally, the length of the weakened band 120 is equal to the length of the main structure 110. That is, the weakened band 120 extends from one end surface of the main structure 110 along the length direction to the other end surface of the main structure 110 along the length direction; this can avoid to a certain extent the situation that when the current collector 100 is subjected to a destructive force, both ends or one end of the main structure 110 along the length direction are still connected, further ensuring that the main structure 110 can be broken as a whole.

[0024] In another application example, the current collector 100 can also be used in a battery with a laminated cell. In this case, the arrangement of the strength weakening tape 120 on the main structure 110 can be more flexible. For example, the strength weakening tape 120 can be extended in any direction to separate the main structure 110. In addition, when there are multiple strength weakening tapes 120, the multiple strength weakening tapes 120 can be parallel or non-parallel and staggered; relatively speaking, arranging multiple strength weakening tapes 120 in parallel can reduce the difficulty of processing the strength weakening tapes 120.

[0025] Optionally, the weakened zone 120 includes at least one of a thinned structure, a hollow structure, and a concave-convex structure.

[0026] For the thinning structure, it may refer to the grooves processed on the surface of the main structure 110, which are used to reduce the thickness of the main structure 110 at the corresponding position, so as to weaken the strength; the above-mentioned grooves may be continuous or discontinuous; for example, a groove may be provided with both ends reaching the edges of both sides of the main structure 110 along the length direction, or a plurality of grooves may be arranged discontinuously in the length direction of the main structure 110, or a continuous zigzag groove may be provided on the main structure 110. For the hollow structure, it may refer to the openings processed on the main structure 110, and the openings may be at least one of the various shapes such as circular, triangular, quadrilateral, pentagonal and pentagram; the number of openings may be multiple, and they may be arranged discontinuously along a certain direction. For the concave-convex structure, it may refer to the structure in which the convexities and concavities are arranged alternately on the surface of the main structure 110.

[0027] By providing at least one of the above thinning structure, hollow structure and concave-convex structure, the strength weakening effect of the strength weakening belt 120 on a specific area of ​​the main structure 110 can be achieved.

[0028] In some feasible implementations, the weakened band 120 may be obtained by laser engraving, chemical etching, mold stamping, metal engraving, or other process means.

[0029] Optionally, the main structure 110 is also provided with a pole ear.

[0030] When the current collector 100 is used in a battery having a wound cell, a tab is provided on the main structure 110 of the current collector 100 , which helps to directly fix the tab at the center of the winding when the main structure 110 is wound.

[0031] See also Figures 2 to 4 The embodiment of the present invention further provides a battery cell, including a pole piece, wherein the pole piece 210 includes the above-mentioned current collector 100 .

[0032] It is easy to understand that the strength of the pole piece 210 is mainly provided by the current collector 100 . Usually, the fracture of the pole piece 210 can be regarded as the fracture of the current collector 100 .

[0033] Typically, the battery cell includes two types of pole pieces 210, namely, a positive pole piece 211 and a negative pole piece 212. Both the positive pole piece 211 and the negative pole piece 212 may include the current collector 100 described in the above embodiment, so as to facilitate the positive pole piece 211 and the negative pole piece 212 to be broken as a whole at the same time when subjected to a destructive force. Of course, in some feasible embodiments, the current collector 100 having the strength weakening band 120 may be provided only for the positive pole piece 211 or only for the negative pole piece 212, which can also prevent the positive pole piece 211 and the negative pole piece 212 from contacting each other to a certain extent.

[0034] It should be noted that this battery cell is a battery cell using the above-mentioned current collector 100, and all implementation methods in the above-mentioned current collector 100 embodiment are applicable to the embodiment of this battery cell and can also achieve the same technical effect.

[0035] The following mainly takes the example that all the pole pieces 210 in the battery cell have corresponding weakened strips 120 , that is, the example that the main structure 110 of the current collector 100 included in each pole piece 210 is provided with a weakened strip 120 .

[0036] Optionally, the distance between the center line of the first weakened strength zone and the center line of the second weakened strength zone is less than or equal to 2 mm;

[0037] The pole piece 210 includes a first pole piece and a second pole piece that are arranged opposite to each other, the first strength weakening band is a strength weakening band 120 corresponding to the first pole piece, and the second strength weakening band is a strength weakening band 120 corresponding to the second pole piece and matching the first strength weakening band.

[0038] It is easy to understand that the corresponding relationship between the above-mentioned strength weakening band 120 and the pole piece 210 mainly refers to the current collector 100 included in which pole piece 210 the strength weakening band 120 is specifically located. For example, the first strength weakening band may refer to the main structure 110 included in the current collector 100 included in the first pole piece, and the second strength weakening band may refer to the main structure 110 included in the current collector 100 included in the second pole piece. The matching relationship between the first strength weakening band and the second strength weakening band may refer to the presence of a strength weakening band 120 with the same or similar setting position and extension direction between two adjacent pole pieces 210.

[0039] In this embodiment, the distance between the center line of the first strength weakening band and the center line of the second strength weakening band is limited to within a threshold value, for example, within the above-mentioned 2 mm. This can effectively avoid the situation where the battery cell is difficult to completely break when subjected to a destructive force due to excessive misalignment of the positions of the above-mentioned strength weakening bands. At the same time, a certain fault tolerance is provided, reducing the difficulty of assembling the battery cell.

[0040] Of course, in some preferred implementations, the center line of the first strength weakening band and the center line of the second strength weakening band may completely overlap, which can effectively ensure that the battery cell can be completely broken when subjected to destructive force, thereby improving the safety of the battery cell.

[0041] Optionally, the pole piece further includes a diaphragm 220;

[0042] The first pole piece and the second pole piece are respectively a positive pole piece and a negative pole piece, and the separator 220 is disposed between the positive pole piece and the negative pole piece.

[0043] The battery cell usually includes two types of pole pieces 210, namely, the positive pole piece 211 and the negative pole piece 212, and the separator 220 can be arranged between the positive pole piece 211 and the negative pole piece 212. For example, the battery cell can be a wound battery cell or a laminated battery cell; for the wound battery cell, the positive pole piece 211, the separator 220 and the negative pole piece 212 can be arranged in sequence and then wound to obtain the wound battery cell. Of course, in order to avoid contact between the two pole pieces during winding, the separator 220 can be separately covered on the outside of the positive pole piece 211 and / or the negative pole piece 212; for the laminated battery cell, the positive pole piece 211 and the negative pole piece 212 can be arranged alternately, and the separator 220 can be arranged between any two adjacent pole pieces 210. By setting the separator 220, the situation of direct contact between the positive pole piece 211 and the negative pole piece 212 and short circuit can be avoided.

[0044] Optionally, when the battery cell is a wound battery cell, the strength weakening band 120 corresponding to the pole piece 210 is parallel to the width direction of the wound battery cell.

[0045] Generally speaking, for a wound battery cell, its width direction corresponds to a direction perpendicular to the pole ear 130, and the strength weakening tape 120 extends in the length direction of the main structure 110. After winding, it is parallel to the width direction of the battery cell, that is, the strength weakening tape 120 is located on a specific cross-section of the wound battery cell.

[0046] By setting the strength weakening band 120 corresponding to the pole piece 210 to be parallel to the width direction of the wound battery cell, the wound battery cell can be broken as a whole when subjected to a destructive force, thereby preventing the positive pole piece 211 and the negative pole piece 212 from contacting each other and causing a short circuit.

[0047] Optionally, in the case that the battery cell is a laminated battery cell, there are multiple pole pieces 210 , and the strength weakening zones 120 corresponding to the multiple pole pieces 210 overlap or approximately overlap with each other in vertical projection.

[0048] For laminated cells, the arrangement of the strength weakening bands 120 on the main structure 110 of the current collector 100 included in the pole piece 210 is relatively flexible. In this embodiment, the positions of the strength weakening bands 120 corresponding to each pole piece 210 on the main structure 110 are unified, so that the strength weakening bands 120 corresponding to each pole piece 210 overlap or overlap approximately in vertical projection. It is easy to understand that the approximate overlap can correspond to the situation where the distance between the center line of the first strength weakening band and the center line of the second strength weakening band is less than a certain threshold. This is conducive to the laminated cell being able to break as a whole when subjected to destructive force.

[0049] Of course, it is easy to understand that the laminated battery cell may include multiple battery cell units, each of which is mainly composed of a positive electrode sheet 211, a negative electrode sheet 212, and a separator 220. In some feasible embodiments, the positions of the two electrode sheets 210 in each battery cell unit corresponding to the strength weakening band 120 can be matched, and the positional relationship between the electrode sheets 210 in different battery cell units and the strength weakening band 120 is not limited, which can also prevent the positive electrode sheet 211 and the negative electrode sheet 212 from contacting each other to a certain extent.

[0050] Optionally, the pole piece 210 further includes an active material coating layer; the active material coating layer is at least coated on the strength weakening zone 120 included in the current collector 100 .

[0051] The above-mentioned active material coating layer may refer to a positive electrode coating layer or a negative electrode coating layer and other structures. In the present embodiment, the active material coating layer is at least coated on the strength weakening band 120 included in the current collector 100 to ensure that the battery cell can realize conventional charging and discharging functions; of course, in some preferred embodiments, the active material coating layer may also be coated on the above-mentioned strength weakening band 120 and the main structure 110 at the same time.

[0052] In one example, there are multiple pole sheets 210, including a positive pole sheet 211 and a negative pole sheet 212. The collector 100 included in the positive pole sheet 211 is provided with a positive electrode coating layer 231, and the collector 100 included in the negative pole sheet 212 is provided with a negative electrode coating layer 232.

[0053] For the convenience of description, the current collector 100 included in the positive electrode sheet 211 is referred to as a positive electrode current collector, and the current collector 100 included in the negative electrode sheet 212 is referred to as a negative electrode current collector.

[0054] Taking the above-mentioned battery cell as a wound battery cell as an example, the wound battery cell can be manufactured by the following steps:

[0055] (1) See Figure 2, the two foils are used as the main structure 110 of the positive electrode collector and the main structure 110 of the negative electrode collector respectively; for the convenience of description, the main structure 110 of the positive electrode collector is called the positive electrode main structure 111, and the main structure 110 of the negative electrode collector is called the negative electrode main structure 112;

[0056] A strength weakening band 120 is provided on the positive electrode main structure 111 and the negative electrode main structure 112, respectively. The strength weakening bands 120 on the two main structures 110 may correspond to each other in position, extension direction and number. Only one strength weakening band 120 is shown on each main structure 110 in the figure. In actual application, the number of the strength weakening bands 120 on each main structure 110 may be one or more.

[0057] (2) See Figure 3 , coating the positive electrode active material (corresponding to the above-mentioned positive electrode coating layer 231) on the positive electrode collector to prepare the positive electrode plate 211; coating the negative electrode active material (corresponding to the above-mentioned negative electrode coating layer 232) on the negative electrode collector to prepare the negative electrode plate 212;

[0058] In addition, corresponding tabs 130 may be fixed to the positive electrode main structure 111 and the negative electrode main structure 112 respectively;

[0059] (3) See Figure 4 , a separator 220 is disposed between the positive electrode sheet 211 and the negative electrode sheet 212. To prevent the positive electrode sheet 211 and the negative electrode sheet 212 from contacting each other during the winding process, the separator 220 may be disposed on the other side of the positive electrode sheet 211 relative to the side where the negative electrode sheet 212 is located, and / or, on the other side of the negative electrode sheet 212 relative to the side where the positive electrode sheet 211 is located;

[0060] (4) See Figure 5 , the structure obtained in step (3) is wound to obtain a winding core 300; at this time, Figure 5 As shown, the strength weakening tape 120 is wound together and overlapped, and is parallel to the width direction of the winding core 300;

[0061] Of course, in practical applications, the number of the weakened tapes 120 in the wound battery cell may be one or more. When there are multiple weakened tapes 120 , the multiple weakened tapes 120 may be parallel to each other.

[0062] (5) The core 300 undergoes packaging-liquid injection-chemical treatment to produce a wound battery cell.

[0063] In addition, for the laminated battery cell, the manufacturing steps are similar to the manufacturing steps of the above-mentioned wound battery cell. In the case of removing the pole ear 130 in step (2), the structure obtained in step (3) can be laminated, which will not be repeated here.

[0064] An embodiment of the present invention further provides a battery, comprising the above-mentioned battery cell.

[0065] The battery in this embodiment may be a lithium battery.

[0066] It should be noted that the battery is a battery that uses the above-mentioned battery cell, and all implementation methods in the above-mentioned battery cell embodiments are applicable to the embodiments of the battery and can achieve the same technical effects.

[0067] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary personnel in this technical field, several improvements and modifications can be made without departing from the principles described in the present invention. These improvements and modifications are also within the scope of protection of the present invention.

Claims

1. A battery cell, characterized in that: The invention comprises a pole piece, wherein the pole piece comprises a current collector, wherein the current collector comprises a main structure, wherein a strength weakening band is arranged on the main structure, and wherein the strength weakening band separates the main structure into at least two parts; Wherein, the pole piece comprises a first pole piece and a second pole piece which are arranged opposite to each other, the first strength weakening band is a strength weakening band corresponding to the first pole piece, and the second strength weakening band is a strength weakening band corresponding to the second pole piece and matching the first strength weakening band; The distance between the center line of the first weakened zone and the center line of the second weakened zone is less than or equal to 2 mm; The pole piece further comprises an active material coating layer; the active material coating layer is at least coated on the strength weakening zone included in the current collector.

2. The battery cell according to claim 1, characterized in that: In the case where the battery cell is a wound battery cell, the strength weakening band corresponding to the pole piece is parallel to the width direction of the wound battery cell.

3. The battery cell according to claim 1, characterized in that: When there are plural weakened bands, the plurality of weakened bands are arranged in parallel.

4. The battery cell according to claim 1, characterized in that: The weakened strip extends along the length direction of the main structure.

5. The battery cell according to claim 4, characterized in that: The length of the weakened strip is equal to the length of the main structure.

6. The battery cell according to claim 1, characterized in that: The strength weakening belt includes at least one of a thinning structure, a hollow structure and a concave-convex structure.

7. A battery, characterized in that: The invention comprises the battery cell as claimed in any one of claims 1 to 6.

Images