Single battery and battery pack

Abstract

The utility model discloses a single battery and a battery pack, and relates to the technical field of batteries. The single battery comprises a roll core body. The roll core body comprises a first electrode plate, a diaphragm and a second electrode plate which are stacked and wound, and the diaphragm is arranged between the first electrode plate and the second electrode plate; wherein the first electrode plate comprises a first base material layer, a first active coating and a second active coating, the first active coating is arranged on the side, away from the diaphragm, of the first base material layer, the second active coating is arranged on the side, close to the diaphragm, of the first base material layer, a first groove is formed in the second active coating, and a first buffer layer is arranged in the first groove. According to the single battery provided by the invention, when the electrode plates expand to generate stress in the charging and discharging process, the first buffer layer is compressed after being stressed, so that the stress is absorbed to play a buffer role, the probability of breakage of the electrode plates is effectively reduced, and the service life of the single battery is prolonged.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a single cell battery and a battery pack. Background Technology

[0002] With the continuous development of the electric vehicle and energy storage industry, the requirements for battery energy density and safety of electric vehicles and energy storage equipment are becoming increasingly stringent. Large cylindrical batteries are a major development direction for electric vehicles and energy storage equipment.

[0003] However, while increasing the diameter of large cylindrical batteries brings certain performance risks, as the battery diameter continues to increase, the number of winding layers of the electrode sheets inside the battery core also increases. Therefore, the cumulative stress caused by the expansion of the electrode sheets during charging and discharging also increases. The layered expansion stress may cause the electrode sheets of the core to break, resulting in battery performance failure. Utility Model Content

[0004] In order to achieve the above objectives, this application aims to provide a single cell and a battery pack, which solves the technical problem in the prior art where excessive cumulative expansion stress in the core of a large cylindrical battery leads to electrode breakage and battery performance failure.

[0005] The technical solution adopted is as follows:

[0006] In a first aspect, embodiments of this application provide a single-cell battery, comprising:

[0007] A core body, the core body comprising a first electrode sheet, a diaphragm and a second electrode sheet stacked and wound together, the diaphragm being disposed between the first electrode sheet and the second electrode sheet;

[0008] The first electrode sheet includes a first substrate layer, a first active coating, and a second active coating. The first active coating is disposed on the side of the first substrate layer away from the diaphragm, and the second active coating is disposed on the side of the first substrate layer close to the diaphragm. The second active coating has a first groove, and a first buffer layer is disposed in the first groove.

[0009] In one embodiment of the first aspect, the first electrode sheet has a length direction when it is in a flattened state, the length of the second active coating in the length direction is L1, and the length of the first buffer layer in the length direction is L2, satisfying the relationship: 0.1≤L2 / L1≤0.2.

[0010] In one embodiment of the first aspect, the second electrode sheet includes a second substrate layer, a third active coating and a fourth active coating. The third active coating is disposed on the side of the second substrate layer away from the diaphragm, and the fourth active coating is disposed on the side of the second substrate layer close to the diaphragm. The fourth active coating has a second groove, and a second buffer layer is disposed in the second groove.

[0011] In one embodiment of the first aspect, the second electrode sheet has a length direction when it is in a flattened state, the length of the fourth active coating in the length direction is L3, and the length of the second buffer layer in the length direction is L4, satisfying the relationship: 0.1≤L4 / L3≤0.2.

[0012] In one embodiment of the first aspect, the second electrode sheet includes a second substrate layer, a third active coating and a fourth active coating, the third active coating being disposed on the side of the second substrate layer away from the diaphragm, the fourth active coating being disposed on the side of the second substrate layer close to the diaphragm, the fourth active coating having a second groove, and a second buffer layer being disposed in the second groove;

[0013] When the first electrode sheet is in a flattened state, it has a length direction. The length of the first buffer layer in the length direction is L2, and the length of the second buffer layer in the length direction is L4, satisfying the relationship: 0.7≤L4 / L2≤1.3.

[0014] In one embodiment of the first aspect, the third active coating has a third groove, and a third buffer layer is disposed in the third groove.

[0015] In one embodiment of the first aspect, the first active coating has a fourth groove, and a fourth buffer layer is disposed in the fourth groove.

[0016] In one embodiment of the first aspect, a first adhesive layer is provided between the first buffer layer and the first substrate layer;

[0017] The first groove is a through groove extending through the second active coating along the thickness direction of the first electrode sheet. One side of the first adhesive layer is bonded to the surface of the first substrate layer facing the diaphragm, and the other side of the first adhesive layer is bonded to the first buffer layer. Alternatively, the first groove is a blind groove formed in the second active coating along the thickness direction of the first electrode sheet. One side of the first adhesive layer is bonded to the bottom wall of the first groove facing the diaphragm, and the other side of the first adhesive layer is bonded to the first buffer layer.

[0018] In one embodiment of the first aspect, the first groove extends along the winding direction of the core body, the second active coating has a first end and a second end in the width direction, the first groove extends along the width direction of the second active coating to the edge positions of the first end and the second end, respectively; and the first buffer layer covers the bottom wall of the first groove.

[0019] In one embodiment of the first aspect, along the thickness direction of the first electrode sheet, the surface of the first buffer layer facing the diaphragm does not extend beyond the surface of the second active coating facing the diaphragm.

[0020] In one embodiment of the first aspect, the first buffer layer includes a colloidal layer and a substrate layer, the colloidal layer being disposed in the first groove, the substrate layer being disposed on the side of the colloidal layer away from the first substrate layer, and at least one of the colloidal layer and the substrate layer being capable of absorbing electrolyte.

[0021] Secondly, embodiments of this application also provide a battery pack, including the single battery cells described in any of the above embodiments.

[0022] The beneficial effects of this application are as follows: This application proposes a single-cell battery, which includes a core body. The core body includes a first electrode sheet, a separator, and a second electrode sheet stacked and wound together. The separator is disposed between the first and second electrode sheets. The first electrode sheet includes a first substrate layer, a first active coating, and a second active coating. The first active coating is disposed on the side of the first substrate layer away from the separator, and the second active coating is disposed on the side of the first substrate layer closer to the separator. By creating a first groove in the second active coating and providing a first buffer layer within the first groove, when the electrode sheet expands and generates stress during charging and discharging, the first buffer layer is compressed under stress, thereby absorbing stress and providing a buffering effect. This effectively reduces the probability of electrode sheet breakage, extends the service life of the single-cell battery, and avoids the technical problem in the prior art where excessive accumulated expansion stress of the core leads to electrode sheet breakage and battery performance failure. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The following is a top view of the core body in some embodiments of this application. Figure 1 ;

[0025] Figure 2 This illustration shows a stacked diagram of the first electrode sheet, the diaphragm, and the second electrode sheet in some embodiments of this application. Figure 1 ;

[0026] Figure 3 The following is a top view of the core body in some embodiments of this application. Figure 2 ;

[0027] Figure 4 This illustration shows a stacked diagram of the first electrode sheet, the diaphragm, and the second electrode sheet in some embodiments of this application. Figure 2 ;

[0028] Figure 5 This illustration shows a stacked diagram of the first electrode sheet, the diaphragm, and the second electrode sheet in some embodiments of this application. Figure 3 ;

[0029] Figure 6 A schematic diagram of the stacking of the first buffer layer in some embodiments of this application is shown.

[0030] Explanation of key component symbols:

[0031] 110 - Core body; 111 - First electrode sheet; 1111 - First substrate layer; 1112 - First active coating; 11121 - Fourth groove; 1113 - Second active coating; 11131 - First groove; 1114 - First buffer layer; 11141 - Colloidal layer; 11142 - Matrix layer; 1115 - First adhesive layer; 1116 - Fourth buffer layer; 112 - Separator; 113 - Second electrode sheet; 1131 - Second substrate layer; 1132 - Third active coating; 11321 - Third groove; 1133 - Fourth active coating; 11331 - Second groove; 1134 - Second buffer layer; 1135 - Second adhesive layer; 1136 - Third buffer layer; X - Length direction. Detailed Implementation

[0032] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0033] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element 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.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0035] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0036] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0037] like Figure 1 and Figure 2 As shown, an embodiment of this application provides a single-cell battery, mainly used in battery packs. The single-cell battery includes a core body 110. The core body 110 includes a first electrode sheet 111, a separator 112, and a second electrode sheet 113 stacked and wound together, with the separator 112 disposed between the first electrode sheet 111 and the second electrode sheet 113.

[0038] The first electrode sheet 111 includes a first substrate layer 1111, a first active coating 1112, and a second active coating 1113. The first active coating 1112 is disposed on the side of the first substrate layer 1111 away from the diaphragm 112, and the second active coating 1113 is disposed on the side of the first substrate layer 1111 close to the diaphragm 112. The second active coating 1113 has a first groove 11131, and a first buffer layer 1114 is disposed in the first groove 11131.

[0039] The single-cell battery provided in the embodiments of this application has first electrode sheet 111 and second electrode sheet 113 with opposite polarities to provide the battery charge. A separator 112 is disposed between the first electrode sheet 111 and the second electrode sheet 113 to provide insulation and prevent short circuits between them. For example, the first electrode sheet 111 can be a positive electrode, the second electrode sheet 113 can be a negative electrode, and the separator 112 is disposed between them. Additionally, a separator 112 is also disposed on the side of the first electrode sheet 111 or the second electrode sheet 113 away from the separator 112 to ensure that the first electrode sheet 111 and the second electrode sheet 113 do not contact each other after winding, thereby preventing short circuits between them.

[0040] By creating a first groove 11131 on the second active coating 1113 and setting a first buffer layer 1114 within the first groove 11131, the first buffer layer 1114 is compressed after being subjected to stress when the electrode sheet expands during charging and discharging, thereby absorbing the stress and playing a buffering role. This effectively reduces the probability of electrode sheet breakage, extends the service life of the single cell, and avoids the technical problem in the prior art where excessive accumulated expansion stress of the core leads to electrode sheet breakage and battery performance failure.

[0041] Furthermore, by placing the first buffer layer 1114 within the first groove 11131 of the second active coating 1113, this facilitates contact between the second active coating 1113 and the separator 112, preventing structural interference caused by placing the first buffer layer 1114 between the second active coating 1113 and the separator 112, which would affect the contact performance between the second active coating 1113 and the separator 112 and thus the electrical performance of the individual battery. On the other hand, it also facilitates the winding and forming of the core body 110, preventing structural interference caused by placing the first buffer layer 1114 between the second active coating 1113 and the separator 112, which would affect the winding and forming of the core body 110 and thus the electrical performance of the individual battery.

[0042] Optionally, the single cell is a rechargeable battery, which refers to a battery that can be recharged after discharge to activate the active materials and continue to be used. For example, the single cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, or nickel-cadmium battery, but is not limited to these. The single cell can be cylindrical, but can also be prismatic, pouch, or other shapes of battery.

[0043] In one embodiment of this application, the first groove 11131 extends along the winding direction of the core body 110, the second active coating 1113 has a first end and a second end in the width direction, the first groove 11131 extends along the width direction of the second active coating 1113 to the edge positions of the first end and the second end respectively, and the first buffer layer 1114 covers the bottom wall of the first groove 11131.

[0044] The first groove 11131 extends in the width direction of the second active coating 1113 to the edge of the first end and the second end, and the first buffer layer 1114 covers the entire bottom wall of the first groove 11131, so that the area where the first buffer layer 1114 is provided can be subjected to uniform force in each area when the first electrode sheet 111 undergoes a chemical reaction and expands, so as to play a better buffering role and prevent the electrode sheet from breaking due to the cumulative expansion stress of the core.

[0045] In one embodiment of this application, along the thickness direction of the first electrode sheet 111, the surface of the first buffer layer 1114 facing the diaphragm 112 does not extend beyond the surface of the second active coating 1113 facing the diaphragm 112. This arrangement ensures that the first buffer layer 1114 does not increase the radial dimensions of the first electrode sheet 111 and the entire core body 110, thus preventing any impact on energy density.

[0046] like Figure 2 As shown, in one embodiment of this application, the first electrode sheet 111 has a length direction X when it is in a flattened state, the second active coating 1113 has a length L1 in the length direction X, and the first buffer layer 1114 has a length L2 in the length direction X, satisfying the relationship: 0.1≤L2 / L1≤0.2.

[0047] In this embodiment, by controlling the ratio of the length L2 of the first buffer layer 1114 in its flattened state to the length L1 of the second active coating 1113 in its flattened state to between 0.1 and 0.2, the ratio of the first buffer layer 1114 to the second active coating 1113 is controlled between 10% and 20%. This avoids the first buffer layer 1114 being too long, which would result in the second active coating 1113 being too short, affecting the contact area between the second active coating 1113 and the separator 112, and thus affecting the electrical performance of the single cell. On the other hand, it also avoids the first buffer layer 1114 being too short, which would affect its absorption and buffering effect on expansion stress, thereby affecting the service life of the single cell.

[0048] To better demonstrate the beneficial effects of these parameters and relationships, the following experimental data is provided. Specific implementation examples and test results are shown in the table below:

[0049]

[0050]

[0051] In Examples 1-3, 1000 single-cell batteries were prepared according to the parameters in the table for each example. The electrochemical reaction efficiency and electrode breakage probability of the single-cell batteries were statistically analyzed. The results of the electrochemical reaction efficiency and electrode breakage probability are shown in the table above. The electrochemical reaction efficiency was greater than 95% and the electrode breakage probability was less than 5%. The high electrochemical reaction efficiency and low electrode breakage probability meet the design requirements. Therefore, when L2 / L1 is between 0.1 and 0.2, it can ensure that the electrode breakage probability meets the design requirements and also take into account the design requirements of electrochemical reaction efficiency, which is the optimal implementation method.

[0052] like Figure 3 and Figure 4 As shown, in one embodiment of this application, the second electrode sheet 113 includes a second substrate layer 1131, a third active coating 1132, and a fourth active coating 1133. The third active coating 1132 is disposed on the side of the second substrate layer 1131 away from the diaphragm 112, and the fourth active coating 1133 is disposed on the side of the second substrate layer 1131 close to the diaphragm 112. The fourth active coating 1133 has a second groove 11331, and a second buffer layer 1134 is disposed in the second groove 11331.

[0053] In this embodiment, by creating a second groove 11331 on the fourth active coating 1133 and setting a second buffer layer 1134 within the second groove 11331, the second buffer layer 1134 is compressed after being subjected to stress when the electrode sheet expands during charging and discharging, thereby absorbing the stress and playing a buffering role. This further reduces the probability of electrode sheet breakage and extends the service life of the single cell, avoiding the technical problem in the prior art where excessive accumulated expansion stress of the core leads to electrode sheet breakage and battery performance failure.

[0054] Furthermore, by disposing the second buffer layer 1134 within the second groove 11331 of the fourth active coating 1133, this facilitates contact between the fourth active coating 1133 and the separator 112, preventing structural interference caused by placing the second buffer layer 1134 between the fourth active coating 1133 and the separator 112, which would affect the contact performance between the fourth active coating 1133 and the separator 112 and thus impact the electrical performance of the individual battery. On the other hand, it also facilitates the winding and forming of the core body 110, preventing structural interference caused by placing the second buffer layer 1134 between the fourth active coating 1133 and the separator 112, which would affect the winding and forming of the core body 110 and thus impact the electrical performance of the individual battery.

[0055] like Figure 4 As shown in the above embodiments of this application, when the second electrode sheet 113 is in a flattened state, it has a length direction X. The length of the fourth active coating 1133 in the length direction X is L3, and the length of the second buffer layer 1134 in the length direction X is L4, satisfying the relationship: 0.1≤L4 / L3≤0.2.

[0056] In this embodiment, by controlling the ratio of the length L4 of the second buffer layer 1134 in its flattened state to the length L3 of the fourth active coating 1133 in its flattened state to be between 0.1 and 0.2, the ratio of the second buffer layer 1134 to the fourth active coating 1133 is controlled between 10% and 20%. This avoids the second buffer layer 1134 being too long, which would result in the fourth active coating 1133 being too short, affecting the contact area between the fourth active coating 1133 and the separator 112, and thus affecting the electrical performance of the single cell. On the other hand, it also avoids the second buffer layer 1134 being too short, which would affect its absorption and buffering effect on expansion stress, thereby affecting the service life of the single cell.

[0057] To better demonstrate the beneficial effects of these parameters and relationships, the following experimental data is provided. Specific implementation examples and test results are shown in the table below:

[0058]

[0059] In Examples 4-6, 1000 single-cell batteries were prepared according to the parameters in the table for each example. The electrochemical reaction efficiency and electrode breakage probability of the single-cell batteries were statistically analyzed. The results of the electrochemical reaction efficiency and electrode breakage probability are shown in the table above. The electrochemical reaction efficiency was greater than 95% and the electrode breakage probability was less than 5%. The high electrochemical reaction efficiency and low electrode breakage probability meet the design requirements. Therefore, when L4 / L3 is between 0.1 and 0.2, it can ensure that the electrode breakage probability meets the design requirements and also take into account the design requirements of electrochemical reaction efficiency, which is the optimal implementation method.

[0060] like Figure 3 and Figure 4 As shown, in one embodiment of this application, the second electrode sheet 113 includes a second substrate layer 1131, a third active coating 1132, and a fourth active coating 1133. The third active coating 1132 is disposed on the side of the second substrate layer 1131 away from the diaphragm 112, and the fourth active coating 1133 is disposed on the side of the second substrate layer 1131 close to the diaphragm 112. The fourth active coating 1133 has a second groove 11331, and a second buffer layer 1134 is disposed in the second groove 11331.

[0061] When the first electrode sheet 111 is in a flattened state, it has a length direction X. The length of the first buffer layer 1114 in the length direction X is L2, and the length of the second buffer layer 1134 in the length direction X is L4, satisfying the relationship: 0.7≤L4 / L2≤1.3.

[0062] In this embodiment, by controlling the ratio of the length L4 of the second buffer layer 1134 in its flattened state to the length L2 of the first buffer layer 1114 in its flattened state to between 0.7 and 1.3, the ratio of the second buffer layer 1134 to the first buffer layer 1114 is controlled between 70% and 130%, thereby keeping the length difference between the second buffer layer 1134 and the first buffer layer 1114 within 30%. This avoids an excessive difference in the contact area between the fourth active coating 1133 and the separator 112 compared to the contact area between the second active coating 1113 and the separator 112, which could affect the uniformity of the electrochemical reaction and thus the electrical performance of the single cell. Furthermore, it also avoids a large difference in the absorption effect of expansion stress between the second buffer layer 1134 and the first buffer layer 1114, which could affect the uniformity of expansion stress absorption and thus the lifespan of the single cell.

[0063] To better demonstrate the beneficial effects of these parameters and relationships, the following experimental data is provided. Specific implementation examples and test results are shown in the table below:

[0064]

[0065] In Examples 7 and 8, 1000 single-cell batteries were prepared according to the parameters in the table for each example. The electrochemical reaction efficiency and electrode breakage probability of the single-cell batteries were statistically analyzed. The results of the electrochemical reaction efficiency and electrode breakage probability are shown in the table above. The electrochemical reaction efficiency was greater than 95% and the electrode breakage probability was less than 5%. The high electrochemical reaction efficiency and low electrode breakage probability meet the design requirements. When L4 / L2 is between 0.7 and 1.3, it can ensure that the electrode breakage probability meets the design requirements and also take into account the design requirements of electrochemical reaction efficiency, which is the optimal implementation method.

[0066] like Figure 4 As shown, in the above embodiments of this application, a first adhesive layer 1115 is provided between the first buffer layer 1114 and the first substrate layer 1111. The first groove 11131 has two groove opening methods, as follows:

[0067] The first type: the first groove 11131 is a through groove that passes through the second active coating 1113 along the thickness direction of the first electrode sheet 111. One side of the first adhesive layer 1115 is bonded to the surface of the first substrate layer 1111 facing the diaphragm 112, and the other side of the first adhesive layer 1115 is bonded to the first buffer layer 1114.

[0068] In this embodiment, the opening of the first groove 11131 divides the second active coating 1112 in the winding direction of the first electrode sheet 111 into two segments. At this time, the bottom wall of the first groove 11131 is the surface of the first substrate layer 1111 facing the diaphragm 112, and one side of the first adhesive layer 1115 is directly bonded to the first substrate layer 1111, so that the first buffer layer 1114 can have a larger thickness and achieve a better buffering effect.

[0069] The second type: The first groove 11131 is a blind groove formed in the second active coating 1113 along the thickness direction of the first electrode sheet 111. One side of the first adhesive layer 1115 is bonded to the bottom wall of the first groove 11131 facing the diaphragm 112, and the other side of the first adhesive layer 1115 is bonded to the first buffer layer 1114.

[0070] In this embodiment, the first groove 11131 is a blind groove, and the first adhesive layer 1115 is bonded to the bottom wall of the first groove 11131 to place the first buffer layer 1114 on the first electrode sheet 111.

[0071] In this embodiment, by providing a first adhesive layer 1115 between the first buffer layer 1114 and the first substrate layer 1111, the first buffer layer 1114 is stably disposed in the first groove 11131 under the adhesive action of the first adhesive layer 1115, which effectively improves the installation stability of the first buffer layer 1114 and thus ensures the stability of the first buffer layer 1114 in buffering expansion stress.

[0072] In other embodiments, a second adhesive layer 1135 is further provided between the second buffer layer 1134 and the second substrate layer 1131. By providing the second adhesive layer 1135 between the second buffer layer 1134 and the second substrate layer 1131, the second buffer layer 1134 is stably disposed within the second groove 11331 under the adhesive action of the second adhesive layer 1135, effectively improving the installation stability of the second buffer layer 1134, thereby ensuring the stability of the second buffer layer 1134 in buffering expansion stress.

[0073] like Figure 5 As shown, in the above embodiments of this application, the third active coating 1132 has a third groove 11321, and a third buffer layer 1136 is provided in the third groove 11321.

[0074] In this embodiment, by creating a third groove 11321 on the third active coating 1132 and setting a third buffer layer 1136 within the third groove 11321, the third buffer layer 1136 is compressed after being subjected to stress when the electrode sheet expands during charging and discharging, thereby absorbing the stress and playing a buffering role. This further reduces the probability of electrode sheet breakage and extends the service life of the single cell, avoiding the technical problem in the prior art where excessive accumulated expansion stress of the core leads to electrode sheet breakage and battery performance failure.

[0075] like Figure 5 As shown, in any of the above embodiments of this application, the first active coating 1112 has a fourth groove 11121, and a fourth buffer layer 1116 is disposed in the fourth groove 11121.

[0076] In this embodiment, by creating a fourth groove 11121 on the fourth active coating 1133 and setting a fourth buffer layer 1116 within the fourth groove 11121, the fourth buffer layer 1116 is compressed after being subjected to stress when the electrode sheet expands during charging and discharging, thereby absorbing the stress and playing a buffering role. This further reduces the probability of electrode sheet breakage and extends the service life of the single cell, avoiding the technical problem in the prior art where excessive accumulated expansion stress of the core leads to electrode sheet breakage and battery performance failure.

[0077] like Figure 6 As shown, in any of the above embodiments of this application, the first buffer layer 1114 includes a colloidal layer 11141 and a substrate layer 11142. The colloidal layer 11141 is disposed in the first groove 11131, and the substrate layer 11142 is disposed on the side of the colloidal layer 11141 away from the first substrate layer 1111. At least one of the colloidal layer 11141 and the substrate layer 11142 is capable of absorbing electrolyte.

[0078] In this embodiment, by placing the colloidal layer 11141 in the groove and placing the substrate layer 11142 on the side of the colloidal layer 11141 away from the first substrate layer 1111, and ensuring that at least one of the colloidal layer 11141 and the substrate layer 11142 can absorb the electrolyte, when the colloidal layer 11141 can absorb the electrolyte and the substrate layer 11142 is permeable, the electrolyte can pass through the substrate layer 11142 and be absorbed by the colloidal layer 11141. Therefore, during charging and discharging, when the electrode sheet expands and generates stress, the colloidal layer 11141, under stress and compression, can release the electrolyte and replenish the core body 110 through the substrate layer 11142, effectively improving the cycle performance of the core body 110 and extending its service life, thus maintaining good electrical performance of the individual battery.

[0079] When both the colloidal layer 11141 and the substrate layer 11142 can absorb the electrolyte, a portion of the electrolyte can be absorbed by the colloidal layer 11141 through the substrate layer 11142, while another portion of the electrolyte can be absorbed by the substrate layer 11142. Thus, when the electrode sheet expands and generates stress during charging and discharging, the colloidal layer 11141 and the substrate layer 11142 are compressed under stress, which can release the electrolyte to the core body 110 to replenish the electrolyte. This effectively improves the cycle performance of the core body 110 and extends its service life, allowing the single cell to maintain good electrical performance.

[0080] For example, the liquid absorption capacity of the colloidal layer 11141 is greater than that of the base layer 11142, and the first buffer layer 1114 may be an expanding adhesive paper.

[0081] It should be noted that the second buffer layer 1134, the third buffer layer 1136, and the fourth buffer layer 1116 may each include a colloidal layer and a matrix layer, and at least one of the colloidal layer and the matrix layer can absorb electrolyte. This allows the second buffer layer 1134, the third buffer layer 1136, and the fourth buffer layer 1116 to absorb a certain amount of electrolyte. Therefore, when the electrode sheets expand and generate stress during charging and discharging, the second buffer layer 1134, the third buffer layer 1136, and the fourth buffer layer 1116, after being compressed under stress, can release electrolyte to replenish the core body 110, further improving the cycle performance of the core body 110 and extending its service life, thereby further improving the electrical performance of the individual battery.

[0082] Embodiments of this application also provide a battery pack, including the single battery cells in any of the above embodiments.

[0083] The battery pack has the single cell of any of the above embodiments, and therefore has all the beneficial effects of a single cell, which will not be described in detail here.

[0084] The battery pack has a housing and at least one individual battery cell as described in any of the above embodiments, with the individual battery cell housed within the housing. When there are multiple individual battery cells, they can be connected in series or in parallel, or a combination of series and parallel connections, which will not be elaborated further.

[0085] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0086] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A single-cell battery, characterized in that, include: The core body (110) includes a first electrode sheet (111), a diaphragm (112) and a second electrode sheet (113) stacked and wound together, wherein the diaphragm (112) is disposed between the first electrode sheet (111) and the second electrode sheet (113). The first electrode sheet (111) includes a first substrate layer (1111), a first active coating (1112), and a second active coating (1113). The first active coating (1112) is disposed on the side of the first substrate layer (1111) away from the diaphragm (112), and the second active coating (1113) is disposed on the side of the first substrate layer (1111) close to the diaphragm (112). The second active coating (1113) has a first groove (11131), and a first buffer layer (1114) is disposed in the first groove (11131).

2. The single-cell battery according to claim 1, characterized in that, When the first electrode sheet (111) is in a flattened state, it has a length direction (X). The second active coating (1113) has a length of L1 in the length direction (X), and the first buffer layer (1114) has a length of L2 in the length direction (X), satisfying the relationship: 0.1≤L2 / L1≤0.

2.

3. The single-cell battery according to claim 1, characterized in that, The second electrode sheet (113) includes a second substrate layer (1131), a third active coating (1132) and a fourth active coating (1133). The third active coating (1132) is disposed on the side of the second substrate layer (1131) away from the diaphragm (112), and the fourth active coating (1133) is disposed on the side of the second substrate layer (1131) close to the diaphragm (112). The fourth active coating (1133) has a second groove (11331), and a second buffer layer (1134) is disposed in the second groove (11331).

4. The single-cell battery according to claim 3, characterized in that, When the second electrode sheet (113) is in a flattened state, it has a length direction (X). The length of the fourth active coating (1133) in the length direction (X) is L3, and the length of the second buffer layer (1134) in the length direction (X) is L4, satisfying the relationship: 0.1≤L4 / L3≤0.

2.

5. The single-cell battery according to claim 1, characterized in that, The second electrode sheet (113) includes a second substrate layer (1131), a third active coating (1132) and a fourth active coating (1133). The third active coating (1132) is disposed on the side of the second substrate layer (1131) away from the diaphragm (112), and the fourth active coating (1133) is disposed on the side of the second substrate layer (1131) close to the diaphragm (112). The fourth active coating (1133) has a second groove (11331), and a second buffer layer (1134) is disposed in the second groove (11331). When the first electrode sheet (111) is in a flattened state, it has a length direction (X). The length of the first buffer layer (1114) in the length direction (X) is L2, and the length of the second buffer layer (1134) in the length direction (X) is L4, satisfying the relationship: 0.7≤L4 / L2≤1.

3.

6. The single-cell battery according to claim 3, characterized in that, The third active coating (1132) has a third groove (11321), and a third buffer layer (1136) is disposed in the third groove (11321); and / or The first active coating (1112) has a fourth groove (11121), and a fourth buffer layer (1116) is provided in the fourth groove (11121).

7. The single-cell battery according to any one of claims 1-6, characterized in that, A first adhesive layer (1115) is provided between the first buffer layer (1114) and the first substrate layer (1111); The first groove (11131) is a through groove that extends through the second active coating (1113) along the thickness direction of the first electrode sheet (111). One side of the first adhesive layer (1115) is bonded to the surface of the first substrate layer (1111) facing the diaphragm (112), and the other side of the first adhesive layer (1115) is bonded to the first buffer layer (1114). Alternatively, the first groove (11131) is a blind groove formed in the second active coating (1113) along the thickness direction of the first electrode sheet (111). One side of the first adhesive layer (1115) is bonded to the bottom wall of the first groove (11131) facing the diaphragm (112), and the other side of the first adhesive layer (1115) is bonded to the first buffer layer (1114).

8. The single-cell battery according to any one of claims 1 to 6, characterized in that, The first groove (11131) extends along the winding direction of the core body (110), the second active coating (1113) has a first end and a second end in the width direction, the first groove (11131) extends along the width direction of the second active coating (1113) to the edge positions of the first end and the second end respectively; and the first buffer layer (1114) covers the bottom wall of the first groove (11131).

9. The single-cell battery according to claim 8, characterized in that, Along the thickness direction of the first electrode sheet (111), the surface of the first buffer layer (1114) facing the diaphragm (112) does not extend beyond the surface of the second active coating (1113) facing the diaphragm (112).

10. The single-cell battery according to any one of claims 1 to 6, characterized in that, The first buffer layer (1114) includes a colloidal layer (11141) and a substrate layer (11142). The colloidal layer (11141) is disposed in the first groove (11131), and the substrate layer (11142) is disposed on the side of the colloidal layer (11141) away from the first substrate layer (1111). At least one of the colloidal layer (11141) and the substrate layer (11142) is capable of absorbing electrolyte.

11. A battery pack, characterized in that, Includes the single-cell battery according to any one of claims 1 to 10.

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