Secondary battery and battery pack

Abstract

The application discloses a secondary battery and a battery pack, and belongs to the technical field of batteries. The secondary battery comprises an electrode assembly, has a first direction, and the electrode assembly comprises an electrode sheet and a diaphragm which are stacked and wound; the electrode sheet comprises a current collector, the current collector comprises an insulating layer, a first conductive layer and a second conductive layer, and the polarity of the first conductive layer is opposite to that of the second conductive layer; the first conductive layer comprises a first body part and a first tab part, the first tab part is connected with the first body part in the first direction; the second conductive layer comprises a second body part and a second tab part, the second tab part is connected with the second body part in the first direction; the first tab part and the second tab part are respectively located on opposite sides of the current collector in the first direction; the insulating layer is located between the first body part and the second body part, and the insulating layer connects the first body part and the second body part. Through the arrangement of the insulating layer, the tab structure is simplified, the electrode assembly is compactly wound, and the space utilization rate and the energy density are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a secondary battery and a battery pack. BACKGROUND

[0002] Lithium ion batteries have the advantages of high specific energy, high working voltage and low self-discharge rate. In recent years, composite current collector technology has become a major development trend in the industry. The composite current collector is a composite current collector with a metal layer-insulating layer-metal layer to replace the traditional metal current collector. Due to the blocking effect of the insulating layer, the internal short circuit safety of the battery is significantly improved.

[0003] However, in the preparation process of the wound battery, the insulating layer in the composite current collector occupies the volume of the battery, reducing the energy density of the battery. CONTENT OF THE UTILITY MODEL

[0004] The utility model aims to overcome the technical problem that the insulating layer in the composite current collector occupies space, resulting in a decrease in the density of the battery. Another object of the embodiments of the application is to provide a battery pack.

[0005] TECHNICAL SCHEME: The embodiments of the application disclose a secondary battery, comprising an electrode assembly having a first direction, the electrode assembly comprising an electrode sheet and a separator stacked and wound, the electrode sheet comprising a current collector, the current collector comprising an insulating layer, a first conductive layer and a second conductive layer, the polarity of the first conductive layer being opposite to the polarity of the second conductive layer.

[0006] The first conductive layer comprises a first body portion and a first tab portion, the first tab portion being connected to the first body portion in the first direction; the second conductive layer comprises a second body portion and a second tab portion, the second tab portion being connected to the second body portion in the first direction; the first tab portion and the second tab portion are located on opposite sides of the current collector along the first direction; the insulating layer is located between the first body portion and the second body portion, and the insulating layer connects the first body portion and the second body portion.

[0007] In some embodiments, the electrode assembly further has a winding axis and a winding direction around the winding axis; the first tab portion comprises a first bending section and a first connecting section, the first connecting section connecting the first body portion and the first bending section, the first bending section extending towards the winding axis; the second tab portion comprises a second bending section and a second connecting section, the second connecting section connecting the second body portion and the second bending section, the second bending section extending towards the winding axis;

[0008] The electrode sheet is wound along the winding direction and has a plurality of coil layers, each of the coil layers is provided with the first bending section and the second bending section, and the first bending sections of two adjacent coil layers are electrically connected, and the second bending sections of two adjacent coil layers are electrically connected.

[0009] In some embodiments, the insulating layer is provided with a first supporting portion located on one side of the insulating layer in the first direction, the first supporting portion abuts against the first bending section; and / or,

[0010] The insulating layer is provided with a second supporting portion located on the other side of the insulating layer in the first direction, the second supporting portion abuts against the second bending section.

[0011] In some embodiments, the first bending sections of two adjacent layers of the electrode sheet are flush in a plane perpendicular to the first direction, or the first bending sections of two adjacent layers of the electrode sheet are at least partially overlapped in the first direction;

[0012] Or / and, the second bending sections of two adjacent layers of the electrode sheet are flush in a plane perpendicular to the first direction, or the second bending sections of two adjacent layers of the electrode sheet are at least partially overlapped in the first direction.

[0013] In some embodiments, the electrode sheet further comprises a first active layer and a second active layer, the first active layer is arranged on a side of the first body portion away from the insulating layer, the second active layer is arranged on a side of the second body portion away from the insulating layer, and the second active layer is located on a side of the first active layer facing the winding axis;

[0014] The current collector further comprises a first insulating member, the first insulating member is arranged on the second active layer along the first direction, and the first insulating member is located between the second active layer and the first bending section in the first direction.

[0015] In some embodiments, the current collector further comprises a second insulating member, the second insulating member is arranged on the first active layer along the first direction, and the second insulating member and the first insulating member are respectively located on opposite sides of the current collector along the first direction, and the second insulating member is located between the first active layer and the second bending section in the first direction.

[0016] In some embodiments, a plurality of first tab portions are provided, the plurality of first tab portions are arranged at intervals along the winding direction, and each coil layer is provided with at least two first tab portions;

[0017] The second electrode ear is provided in multiple ways, and the multiple second electrode ear are spaced apart along the winding direction, and each layer is provided with at least two second electrode ear.

[0018] In some embodiments, the first insulating member includes a first coating disposed on the second active layer, and the first coating is disposed on the second active layer along the winding direction, and at least a portion of the first bent section abuts against the first coating.

[0019] The second insulating element includes a second coating disposed on the first active layer, and the second coating is disposed on the first active layer along the winding direction, with at least a portion of the second bent section abutting against the second coating.

[0020] In some embodiments, the secondary battery further includes a casing, a first terminal, and a second terminal. The first terminal and the second terminal are respectively disposed on opposite sides of the casing in the first direction, and at least one of the first terminal and the second terminal is insulated from the casing. The first tab is electrically connected to the first terminal, and the second tab is electrically connected to the second terminal. The separator is disposed on one side of the electrode sheet in the thickness direction.

[0021] This application also discloses a battery pack, including the secondary battery as described in the above embodiments.

[0022] Beneficial Effects: The secondary battery of this application embodiment includes an electrode assembly with a first direction. The electrode assembly includes stacked and wound electrode sheets and a separator. The electrode sheets include a current collector, which includes an insulating layer, a first conductive layer, and a second conductive layer. The polarities of the first conductive layer and the second conductive layer are opposite. The first conductive layer includes a first body portion and a first tab portion, with the first tab portion connected to the first body portion in the first direction. The second conductive layer includes a second body portion and a second tab portion, with the second tab portion connected to the second body portion in the first direction. The first tab portion and the second tab portion are respectively located on opposite sides of the current collector along the first direction. An insulating layer is located between the first body portion and the second body portion, and the insulating layer connects the first body portion and the second body portion. By placing the insulating layer between the first body portion and the second body portion, while neither the first tab portion nor the second tab portion has an insulating layer, the tab structure is simplified, allowing the electrode assembly to be wound more compactly, improving the overall space utilization and energy density of the battery.

[0023] The battery pack of this application embodiment includes the secondary battery as described in the above embodiments. Therefore, it can have all the technical features and effects of the above-described secondary battery, which will not be repeated here. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a top view of the electrode assembly in the secondary battery according to an embodiment of this application;

[0026] Figure 2 for Figure 1 A cross-sectional view along the AA direction, showing the state of the secondary battery before it was flattened.

[0027] Figure 3 for Figure 1 A cross-sectional view along the AA direction, showing the connection of the first bent sections and the second bent sections of adjacent electrode sheets;

[0028] Figure 4 for Figure 1 A cross-sectional view along the AA direction shows that the first bending sections of adjacent electrode layers are flush with each other, and the second bending sections of adjacent electrode layers are flush with each other.

[0029] Figure 5 This is a schematic diagram of the connection relationship between the electrode sheet and the separator in the secondary battery of this application embodiment, and the figure shows the state before the electrode sheet is flattened;

[0030] Figure 6 This is a schematic diagram showing the positional relationship between the single-layer electrode sheet and the separator in a secondary battery according to an embodiment of this application. The diagram also shows that the first insulating member covers the second active layer and the second body portion, and the second insulating member covers the first active layer, the first body portion and the separator.

[0031] Figure 7 This is a schematic cross-sectional view of the secondary battery in an embodiment of this application along the AA direction from a top-down perspective.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Electrode assembly; X, first direction; 10. Electrode sheet; 20. Diaphragm; 11. Current collector; 110. Insulating layer; 111. First conductive layer; 112. Second conductive layer; 1111. First body portion; 1112. First tab portion; 1121. Second body portion; 1122. Second tab portion;

[0034] 1113, First bend section; 1123, Second bend section; L, Winding direction; 100, Layer;

[0035] 1101. First support section; 1102. Second support section;

[0036] 1114, First connecting segment; 1124, Second connecting segment;

[0037] 12. First active layer; 13. Second active layer;

[0038] 114. First insulating component; 1141. First coating; 113. Second insulating component; 1131. Second coating; 2. Housing; 3. First collector plate; 4. Second collector plate. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0040] In the description of this application, it should be understood that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In the description of this application, "multiple" means two or more, and "at least one" can refer to one, two, or more, unless otherwise explicitly specified. The terms "first," "second," and "third," etc., are only for the convenience of description and are used to name parts or embodiments by number, and do not imply any order of importance between the parts or embodiments.

[0041] It should also be noted that in the accompanying drawings of this application, the arrow marked X indicates the first direction X, and the arrow marked Y indicates the second direction. The introduction of the first direction X and the second direction in the description of this application is to more clearly define the structure and relative positional relationships of the components in the secondary battery. In actual implementation, the first direction X is generally a vertical direction or a height direction, and the second direction is generally a horizontal direction. The first direction X intersects with the second direction. Optionally, the first direction X is perpendicular to the second direction to optimize the layout of the secondary battery. In the description of this application, "perpendicular" means completely perpendicular to 90° or almost completely perpendicular; for example, an angle between 80° and 100° is considered perpendicular.

[0042] As a preamble to the embodiments of this application, lithium-ion batteries have advantages such as high specific energy, high operating voltage, and low self-discharge rate. In recent years, composite current collector technology has become a major development trend in the industry. Composite current collectors are formed by stacking metal layers-insulating layers-metal layers to replace traditional metal current collectors. Due to the blocking effect of the insulating layer, the internal short-circuit safety of the battery is significantly improved.

[0043] However, in the fabrication process of wound batteries, an insulating layer exists in the welding area of ​​the tabs in the composite current collector. After welding, the insulating layer cannot conduct current, and it also occupies internal battery volume, reducing the battery's energy density. Furthermore, using a blank area to set up quasi-full tabs, even after flattening, still poses a risk of short circuit due to contact with the positive and negative electrode conductive layers or active materials, resulting in a safety hazard.

[0044] In view of this, embodiments of this application provide a secondary battery, which aims to solve at least one of the above-mentioned technical problems.

[0045] Please see Figure 1 and Figure 2 As shown, the secondary battery in this embodiment includes an electrode assembly 1 with a first direction X. The electrode assembly 1 includes stacked and wound electrode sheets 10 and a separator 20. The electrode sheet 10 includes a current collector 11, which includes an insulating layer 110, a first conductive layer 111, and a second conductive layer 112. The polarity of the first conductive layer 111 and the polarity of the second conductive layer 112 are opposite. The first conductive layer 111 includes a first body portion 1111 and a first tab portion 1112. The first tab portion 1112 is located in the first direction X. The first body portion 1111 is connected to the second conductive layer 112, which includes a second body portion 1121 and a second tab portion 1122. The second tab portion 1122 is connected to the second body portion 1121 in the first direction X. The first tab portion 1112 and the second tab portion 1122 are located on opposite sides of the current collector 11 in the first direction X. The insulating layer 110 is located between the first body portion 1111 and the second body portion 1121, and the insulating layer 110 is connected to the first body portion 1111 and the second body portion 1121.

[0046] It should be understood that in the current collector 11 of this application, the first conductive layer 111 can be a positive conductive layer, which can be made of aluminum or other metals, or lithium cobalt oxide, ternary materials, or lithium iron phosphate. The second conductive layer 112 can be a negative conductive layer, which can be made of copper or other metals, or graphite, silicon-based materials, or lithium titanate. The insulating layer 110 can be a polymer insulating material, such as polystyrene, polypropylene, polyester, polycarbonate, polytetrafluoroethylene, polyimide, etc. The insulating layer 110 can be a synthetic fiber insulating paper, such as aromatic polyamide fiber paper, polyester fiber paper, etc.; the insulating layer 110 can also be various insulating tapes, etc. The insulating layer 110 mainly plays a supporting role between the first conductive layer 111 and the second conductive layer 112, while insulating the first body part 1111 and the second body part 1121 to prevent them from conducting.

[0047] Specifically, the first tab 1112 and the second tab 1122 are located on both sides of the current collector 11 along the first direction X. The first tab 1112 serves as the lead-out portion of the first body portion 1111, and the second tab 1122 serves as the lead-out portion of the second body portion 1121, used to lead out current. By placing the insulating layer 110 between the first body portion 1111 and the second body portion 1121, the structure of the insulating layer 110 is optimized, so that neither the first tab 1112 nor the second tab 1122 has the insulating layer 110, simplifying the tab structure, reducing resistance, and improving charging and discharging efficiency. At the same time, it allows the electrode assembly 1 to be wound more compactly, optimizes the space occupied by the tabs inside the battery, enhances the overall stability of the battery, and improves the overall space utilization and energy density of the battery.

[0048] Optionally, the first electrode ear 1112 can be obtained by cutting, that is, the first electrode ear 1112 is integrally formed with the first body portion 1111, or the first electrode ear 1112 can be welded to the first body portion 1111. Similarly, the second electrode ear 1122 can be obtained by cutting, that is, the second electrode ear 1122 is integrally formed with the second body portion 1121, or the second electrode ear 1122 can be welded to the second body portion 1121, which will not be described in detail here.

[0049] Please see Figure 3 and Figure 4 As shown, in some embodiments, the electrode assembly 1 further has a winding axis and a winding direction L for winding around the winding axis; the first electrode tab 1112 includes a first bending section 1113 and a first connecting section 1114, the first connecting section 1114 connecting the first body portion 1111 and the first bending section 1113, the first bending section 1113 extending toward the winding axis.

[0050] The second pole ear portion 1122 includes a second bent section 1123 and a second connecting section 1124. The second connecting section 1124 connects the second body portion 1121 and the second bent section 1123. The second bent section 1123 extends toward the winding axis.

[0051] It should be noted that: the secondary battery is a cylindrical battery, and the electrode assembly 1 is a circular wound structure formed by winding; the extension directions of the first bending section 1113 and the second bending section 1123 are both towards the winding axis, the winding axis is approximately parallel to the first direction X, and the extension direction can be approximately perpendicular to the first direction X.

[0052] The electrode sheet 10 is wound along the winding direction L and has multiple layers 100. Each layer 100 is provided with a first bending section 1113 and a second bending section 1123. The first bending sections 1113 of two adjacent layers 100 are electrically connected, and the second bending sections 1123 of two adjacent layers 100 are electrically connected.

[0053] It should be understood that by connecting the first bending segment 1113 of two adjacent rings 100 and the second bending segment 1123 of two adjacent rings 100, the first conductive layer 111 between adjacent rings 100 and the second conductive layer 112 between adjacent rings 100 are interconnected, thereby optimizing the electron transport path, reducing the electron transport resistance, and improving the current transport efficiency of the entire electrode assembly 1.

[0054] It is understandable that, since each coil 100 is provided with a first bending segment 1113 and a second bending segment 1123, it is equivalent to having a first pole lug 1112 and a second pole lug 1122 in each coil 100. This arrangement can be integral or separate. Taking the first pole lug 1112 as an example: Integral means that the first pole lug 1112 is a single unit, extending and winding along the winding direction L, with multiple independent first bending segments 1113. These first bending segments 1113 are spaced apart along the winding direction L and are present in each coil 100. Separate means that there can be multiple independent first pole lugs 1112, present in each coil 100, and each first pole lug 1112 has at least one first bending segment 1113. The arrangement of the second pole lug 1122 is similar and will not be elaborated here.

[0055] In the case of a separate configuration, the first tabs 1112 of adjacent layers 100 are interconnected, and the second tabs 1122 of adjacent layers 100 are interconnected. This helps to balance the potential between the electrode plates 10 of each layer 100, making the potential of the electrode plates 10 of each layer 100 more uniform, reducing local overpotential phenomena, and improving the cycle life of the battery. Furthermore, the interconnected first tabs 1112 and the interconnected second tabs 1122 can both serve as heat conduction channels, allowing heat to diffuse more evenly within the electrode assembly 1, improving the thermal stability of the battery, and further ensuring the safety of the battery.

[0056] It should be understood that, in some embodiments, the first bent segment 1113 and the second bent segment 1123 may extend in the same direction, that is, both towards the winding axis of the electrode sheet 10 or both towards a direction away from the winding axis of the electrode sheet 10. In some embodiments, the first bent segment 1113 and the second bent segment 1123 may also extend in opposite directions, that is, one of them extends towards the center of the winding direction L of the electrode sheet 10, and the other extends away from the center of the winding direction L of the electrode sheet 10.

[0057] Please see Figure 3 and Figure 4 As shown, in some embodiments, the insulating layer 110 is provided with a first support portion 1101, which is located on one side of the insulating layer 110 in the first direction X, and the first support portion 1101 abuts against the first bent section 1113.

[0058] In some embodiments, the insulating layer 110 is provided with a second support portion 1102, which is located on the other side of the insulating layer 110 in the first direction X, and the second support portion 1102 abuts against the second bent section 1123.

[0059] During the flattening process of the tabs, the first support 1101 supports the first tab 1112, and the second support 1102 supports the second tab 1122, making the first tab 1112 and the second tab 1122 more stable in the battery structure. When the battery is subjected to external mechanical forces, such as compression, collision, or expansion and contraction of the electrode materials inside the battery, the first support 1101 can maintain the shape and position of the first tab 1112, and similarly, the second support 1102 can maintain the shape and position of the second tab 1122, thereby avoiding problems such as affecting the connection with the external circuit or causing internal short circuits due to deformation of the first tab 1112 and the second tab 1122 under force.

[0060] It is also important to understand that the first support portion 1101 and the second support portion 1102 help maintain the overall structural stability of the electrode assembly 1, preventing short circuits or other electrochemical performance degradation due to contact between the active layer and the tab during battery operation, and ensuring the ion transport path. In some cases, the spacing between the first support portion 1101 and the second support portion 1102 helps to thermally isolate the tab from the active layer, thereby reducing the rapid heat transfer between the tab and the active layer, reducing the occurrence of local overheating, helping to achieve a uniform temperature distribution inside the battery, and improving the thermal safety of the battery.

[0061] In some embodiments, the insulating layer 110 is provided with both a first support portion 1101 and a second support portion 1102.

[0062] Optionally, the first support portion 1101, the second support portion 1102, and the insulating layer 110 can be integrally formed.

[0063] Please see Figure 4 As shown, in some embodiments, the first electrode tab 1112 further includes a first connecting segment 1114, which connects the first body portion 1111 and the first bending segment 1113; the first bending segments 1113 of two adjacent electrode sheets 10 are flush on a plane perpendicular to the first direction X.

[0064] In some embodiments, the second electrode tab 1122 further includes a second connecting segment 1124, which connects the second body portion 1121 and the second bending segment 1123; the second bending segments 1123 of adjacent electrode sheets 10 are flush on a plane perpendicular to the first direction X.

[0065] like Figure 4In the illustrated embodiment, the first bending sections 1113 of two adjacent electrode layers 10 are aligned, meaning that the first bending section 1113 of one electrode layer 10 is connected to the first connecting section 1114 of the other electrode layer 10. Similarly, the second bending sections 1123 of two adjacent electrode layers 10 are aligned, meaning that the second bending section 1123 of one electrode layer 10 is connected to the second connecting section 1124 of the other electrode layer 10. It should be understood that adjacent electrode sheets 10 are connected to each other through the first bending section 1113 of one electrode sheet 10 and the first connecting section 1114 of the other electrode sheet 10, so as to realize the current conduction of the two adjacent electrode sheets 10, reduce the length of the first tab 1112 and the second tab 1122, and reduce the material cost; at the same time, it allows the electrode assembly 1 to be wound more compactly, reduces the size of the electrode assembly 1 along the first direction X, solves the problem of protrusions formed at the tab connection of adjacent electrode sheets 10, optimizes the space occupied by the tabs in the battery, enhances the overall stability of the battery, and improves the overall space utilization and energy density of the battery.

[0066] Please see Figure 3 As shown, in some embodiments, the first electrode tab 1112 further includes a first connecting segment 1114, which connects the first body portion 1111 and the first bending segment 1113; the first bending segments 1113 of two adjacent electrode sheets 10 are at least partially stacked in the first direction X.

[0067] In some embodiments, the second electrode tab 1122 further includes a second connecting segment 1124, which connects the second body portion 1121 and the second bending segment 1123; the second bending segments 1123 of adjacent electrode sheets 10 are at least partially stacked in the first direction X. It should be understood that the first bending segments 1113 of adjacent electrode sheets 10 are partially stacked, that is, the overlapping portions of the first bending segments 1113 of adjacent electrode sheets 10 are connected in the first direction X. The second bending segments 1123 of adjacent electrode sheets 10 are partially stacked, that is, the overlapping portions of the second bending segments 1123 of adjacent electrode sheets 10 are connected in the first direction X.

[0068] like Figure 3In the illustrated embodiment, the design of the first bent section 1113 of the first tab 1112 and the second bent section 1123 of the second tab 1122 allows the two connected electrode layers 10 to be interconnected through the bent sections, improving the structural stability and robustness of the entire electrode assembly 1. When the battery is subjected to external impacts, vibrations, or expansion and contraction of the internal electrode materials, the connection of adjacent layers 100 of the electrode sheets 10 effectively prevents separation or misalignment between the electrode sheets 10 layers, ensuring the integrity of the electrode assembly 1 and maintaining the normal performance of the battery. Simultaneously, the presence of the first bent section 1113 and the second bent section 1123 can provide a buffering effect to some extent. When the battery is subjected to external pressure, the bent sections can absorb some of the pressure through their own deformation, reducing damage to the main body and other critical parts, thereby improving the battery's tolerance to complex mechanical environments.

[0069] Please see Figure 3 and Figure 4 As shown, in some embodiments, the electrode sheet 10 further includes a first active layer 12 and a second active layer 13. The first active layer 12 is disposed on the side of the first body portion 1111 opposite to the insulating layer 110, and the second active layer 13 is disposed on the side of the second body portion 1121 opposite to the insulating layer 110, and the second active layer 13 is located on the side of the first active layer 12 facing the winding axis. The current collector 11 further includes a first insulating member 114, which is disposed on the second active layer 13 along a first direction X, and the first insulating member 114 is located between the second active layer 13 and the first bent section 1113 in the first direction X.

[0070] It should be understood that the first insulating component 114 can effectively prevent direct contact between the first bent section 1113 and the second active layer 13, providing an insulating barrier inside the battery, greatly reducing the probability of internal short circuits and significantly improving battery safety.

[0071] In some embodiments, the current collector 11 further includes a second insulating member 113, which is disposed on the first active layer 12 along the first direction X, and the second insulating member 113 and the first insulating member 114 are respectively located on opposite sides of the current collector 11 along the first direction X. The second insulating member 113 is located between the first active layer 12 and the second bending segment 1123 in the first direction X.

[0072] It is important to understand that the first insulating component 114 and the second insulating component 113 provide double insulation protection in critical areas inside the battery. The second insulating component 113 effectively prevents direct contact between the second bent section 1123 and the first active layer 12, greatly reducing the probability of internal short circuits and significantly improving battery safety. Simultaneously, the first insulating component 114 and the second insulating component 113 reduce heat transfer between the active layer and the tab layer.

[0073] It should be noted that: the second insulating member 113 is disposed on the first active layer 12, and the first active layer 12 is located on the side of the second active layer 13 away from the winding axis, and the second bending segment 1123 extends toward the winding axis. Therefore, the second bending segment 1123 matches the second insulating member 113 on the corresponding first active layer 12 of the adjacent inner ring layer. That is, the second insulating member 113 is located between the first active layer 12 and the second bending segment 1123 in the first direction X. Here, the second insulating member 113 refers to the second insulating member 113 of the inner ring layer adjacent to the ring layer where the second bending segment 1123 is located. In other words, the second bending segment 1123 refers to the second bending segment 1123 of the outer ring layer adjacent to the ring layer where the second insulating member 113 is located. This will not be elaborated further.

[0074] Both the first insulating member 114 and the second insulating member 113 provide mechanical support and cushioning for the electrode sheet 10. When the battery is subjected to external mechanical stress or expansion and contraction of the internal electrode material, the insulating members can share some of the pressure, preventing extrusion deformation or damage between the first tab 1112 and the second active layer 13, and between the second tab 1122 and the first active layer 12, thus maintaining the stability of the battery's internal structure and extending its service life. Furthermore, the insulating members can prevent the electrode material from migrating between the active layer and the tab, preventing abnormal deposition of the electrode material in these areas or localized changes in electrolyte concentration, ensuring a stable ion transport environment, thereby improving the battery's charge and discharge efficiency and rate performance, and ultimately enhancing the stability of battery performance.

[0075] In some embodiments, a plurality of first electrode tabs 1112 are provided, the plurality of first electrode tabs 1112 are spaced apart along the winding direction L, and each layer 100 is provided with at least two first electrode tabs 1112; a plurality of second electrode tabs 1122 are provided, the plurality of second electrode tabs 1122 are spaced apart along the winding direction L, and each layer 100 is provided with at least two second electrode tabs 1122.

[0076] It is important to understand that each coil 100 has at least two first tabs 1112 and two second tabs 1122, with the first tabs 1112 and the second tabs 1122 of the same coil 100 spaced apart. By separately providing multiple tabs, each coil 100 reduces stress concentration during tab bending, lowering the risk of deformation or damage to the overall battery structure. The multiple tabs also increase the contact area between the tabs and the external environment, facilitating better heat dissipation during battery operation and improving the battery's heat dissipation performance.

[0077] Please see Figure 5 and Figure 6As shown, in some embodiments, the first insulating member 114 includes a first coating 1141 disposed on the second active layer 13, and the first coating 1141 is disposed on the second active layer 13 along the winding direction L, and at least a portion of the first bent section 1113 abuts against the first coating 1141; the second insulating member 113 includes a second coating 1131 disposed on the first active layer 12, and the second coating 1131 is disposed on the first active layer 12 along the winding direction L, and at least a portion of the second bent section 1123 abuts against the second coating 1131.

[0078] It should be understood that the coating can be applied to all of each layer 100 of the active layer, or only to the areas corresponding to the tabs, or only to a portion of the tabs in each layer 100 instead of all the tabs. The first coating 1141 and the second coating 1131 can be made of polyvinylidene fluoride.

[0079] It's also important to understand that the insulating component completely covers the potential contact area between the active layer and the tabs, providing localized protection. This allows the electrochemical reactions inside the battery to concentrate more at the interface between the active layer and the electrolyte, reducing battery capacity loss and performance degradation caused by side reactions. Simultaneously, the insulating component prevents external factors from affecting the ion diffusion channels, enabling ions to diffuse in a more stable and pure environment, thereby improving the battery's charge / discharge efficiency and rate performance. Furthermore, the design of the insulating component reduces the battery's weight while providing effective protection.

[0080] Please see Figure 6 As shown, in some embodiments, the first insulating member 114 may also cover the separator 20 and / or the second body portion 1121 adjacent to the second active layer 13. This further expands the isolation range. By covering the separator 20, the insulating member can prevent short circuits between the positive and negative electrodes that may be caused by damage to the separator 20 or penetration of conductive impurities. By covering the second body portion 1121, conductive paths can be avoided between the second body portion 1121 and other parts that should not be in contact, greatly improving battery safety. Covering multiple areas with the first insulating member 114 enhances the synergistic stability between the various parts of the electrode assembly 1. It can play a "connecting and fixing" role, making the connection between these components tighter, better resisting damage to the battery structure from external mechanical forces and internal stress changes, maintaining the integrity of the battery structure, and extending the battery's service life. Similarly, the second insulating member 113 may also cover the separator 20 and / or the first body portion 1111 adjacent to the first active layer 12, which will not be described in detail here.

[0081] Please see Figure 7As shown, in some embodiments, the secondary battery further includes a housing 2, a first terminal and a second terminal, the first terminal and the second terminal are respectively disposed on opposite sides of the housing 2 in the first direction X, and at least one of the first terminal and the second terminal is insulated from the housing 2, the first electrode tab 1112 is electrically connected to the first terminal, and the second electrode tab 1122 is electrically connected to the second terminal; the separator 20 is disposed on one side of the electrode sheet 10 in the thickness direction.

[0082] One of the first and second terminals can be a positive terminal and the other a negative terminal. Both can be insulated from the housing 2, or one can be insulated from the housing 2 while the other is electrically connected to or integrally formed with the housing 2. For example, the housing 2 can include a housing body and an end cap. The housing body has a receiving cavity in which the electrode assembly 1 is disposed. The end cap is connected to the housing body and seals the receiving cavity. The first terminal passes through the end cap and is insulated from the end cap, while the second terminal is connected to or integrally formed with the bottom wall of the housing body. That is, the second terminal can be the bottom wall of the housing body itself.

[0083] Optionally, such as Figure 7 As shown, the secondary battery also includes a first current collector 3 and a second current collector 4. The first current collector 3 is electrically connected to the first electrode lug 1112 and the first terminal, and the second current collector 4 is connected to the second electrode lug 1122 and the second terminal, forming a circuit. In actual settings, the first current collector 3, the second terminal, etc., can be selected as needed, or they can be omitted, which will not be described in detail here.

[0084] In some embodiments, the separator 20 is attached to the side of the first active layer 12 away from the first conductive layer 111. It should be understood that the first conductive layer 111 can be a positive electrode conductive layer, in which case the first active layer 12 is a positive electrode active layer; conversely, the first conductive layer 111 can also be a negative electrode conductive layer, in which case the first active layer 12 is a negative electrode active layer. By attaching the separator 20 to one side of the electrode sheet 10, compared to conventional solutions where the separator 20 is attached to both the positive and negative electrode sides, the battery energy density is higher. This application uses a method of winding the electrode sheet 10 and the separator 20 to fabricate the electrode assembly 1, which simplifies the manufacturing process and significantly reduces manufacturing costs.

[0085] This application also discloses a battery pack, including the secondary battery as described in the above embodiments. Therefore, it can possess all the technical features and effects of the aforementioned secondary battery, which will not be repeated here.

[0086] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0087] The above provides a detailed description of a secondary battery and battery pack provided in the embodiments of this application, and uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A secondary battery, characterized in that, The device includes an electrode assembly (1) having a first orientation (X). The electrode assembly (1) includes a stacked and wound electrode sheet (10) and a diaphragm (20). The electrode sheet (10) includes a current collector (11). The current collector (11) includes an insulating layer (110), a first conductive layer (111), and a second conductive layer (112). The polarity of the first conductive layer (111) and the polarity of the second conductive layer (112) are opposite. The first conductive layer (111) includes a first body portion (1111) and a first tab portion (1112), the first tab portion (1112) being connected to the first body portion (1111) in the first direction (X); the second conductive layer (112) includes a second body portion (1121) and a second tab portion (1122), the second tab portion (1122) being connected to the second body portion (1121) in the first direction (X); the first tab portion (1112) and the second tab portion (1122) are respectively located on opposite sides of the current collector (11) along the first direction (X); the insulating layer (110) is located between the first body portion (1111) and the second body portion (1121), and the insulating layer (110) connects the first body portion (1111) and the second body portion (1121).

2. The secondary battery according to claim 1, characterized in that, The electrode assembly (1) further has a winding axis and a winding direction (L) for winding around the winding axis; the first electrode tab (1112) includes a first bent section (1113) and a first connecting section (1114), the first connecting section (1114) connecting the first body part (1111) and the first bent section (1113), the first bent section (1113) extending toward the winding axis; the second electrode tab (1122) includes a second bent section (1123) and a second connecting section (1124), the second connecting section (1124) connecting the second body part (1121) and the second bent section (1123), the second bent section (1123) extending toward the winding axis; The electrode sheet (10) is wound along the winding direction (L) and has multiple layers (100). Each layer (100) is provided with a first bending section (1113) and a second bending section (1123). The first bending sections (1113) of two adjacent layers (100) are electrically connected, and the second bending sections (1123) of two adjacent layers (100) are electrically connected.

3. The secondary battery according to claim 2, characterized in that, The insulating layer (110) is provided with a first support portion (1101), the first support portion (1101) being located on one side of the insulating layer (110) in the first direction (X), and the first support portion (1101) abutting against the first bent section (1113); and / or, The insulating layer (110) is provided with a second support portion (1102), which is located on the other side of the insulating layer (110) in the first direction (X), and the second support portion (1102) abuts against the second bent section (1123).

4. The secondary battery according to claim 3, characterized in that, The first bent segments (1113) of two adjacent electrode sheets (10) are flush with each other on a plane perpendicular to the first direction (X), or the first bent segments (1113) of two adjacent electrode sheets (10) are at least partially stacked in the first direction (X). Or / and, the second bent segments (1123) of two adjacent electrode sheets (10) are flush with each other on a plane perpendicular to the first direction (X), or, the second bent segments (1123) of two adjacent electrode sheets (10) are at least partially stacked in the first direction (X).

5. The secondary battery according to claim 2, characterized in that, The electrode sheet (10) further includes a first active layer (12) and a second active layer (13). The first active layer (12) is disposed on the side of the first body portion (1111) away from the insulating layer (110), and the second active layer (13) is disposed on the side of the second body portion (1121) away from the insulating layer (110). The second active layer (13) is located on the side of the first active layer (12) facing the winding axis. The current collector (11) further includes a first insulating member (114), which is disposed on the second active layer (13) along the first direction (X) and is located between the second active layer (13) and the first bent section (1113) in the first direction (X).

6. The secondary battery according to claim 5, characterized in that, The current collector (11) further includes a second insulating member (113), which is disposed on the first active layer (12) along the first direction (X). The second insulating member (113) and the first insulating member (114) are respectively located on opposite sides of the current collector (11) along the first direction (X). The second insulating member (113) is located between the first active layer (12) and the second bent section (1123) in the first direction (X).

7. The secondary battery according to claim 6, characterized in that, The first electrode tab (1112) is provided in multiple ways, and the multiple first electrode tabs (1112) are spaced apart along the winding direction (L), and each layer (100) is provided with at least two first electrode tabs (1112); The second pole tab (1122) is provided in multiple ways, and the multiple second pole tabs (1122) are spaced apart along the winding direction (L), and each layer (100) is provided with at least two second pole tabs (1122).

8. The secondary battery according to claim 7, characterized in that, The first insulating member (114) includes a first coating (1141) disposed on the second active layer (13), and the first coating (1141) is disposed on the second active layer (13) along the winding direction (L), and at least a portion of the first bent section (1113) abuts against the first coating (1141); The second insulating element (113) includes a second coating (1131) disposed on the first active layer (12), and the second coating (1131) is disposed on the first active layer (12) along the winding direction (L), and at least a portion of the second bent segment (1123) abuts against the second coating (1131).

9. The secondary battery according to any one of claims 1 to 8, characterized in that, The secondary battery further includes a casing (2), a first terminal and a second terminal, the first terminal and the second terminal being respectively disposed on opposite sides of the casing (2) in the first direction (X), and at least one of the first terminal and the second terminal being insulated from the casing (2), the first tab (1112) being electrically connected to the first terminal, and the second tab (1122) being electrically connected to the second terminal; the diaphragm (20) is disposed on one side of the electrode sheet (10) in the thickness direction.

10. A battery pack, characterized in that, Includes the secondary battery as described in any one of claims 1 to 9.

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