Battery equipment

Abstract

This utility model relates to the field of battery technology, specifically to a battery device. The device includes a housing with an internal cavity; and a battery cell disposed within the cavity. The battery cell has a wound structure, formed by stacking two electrode sheets with a separator between them and then winding them together. This embodiment, through a layered design of the wound structure and the provision of recessed holes in the electrode coating of the inner layer region, can specifically improve the electrolyte wetting efficiency of the innermost electrode layers. During the wetting process, the recessed holes can briefly collect electrolyte and guide its penetration, solving the problem of difficult wetting of the inner electrode layers caused by the tightness of the curved section of the wound cell. Simultaneously, by controlling the ratio between the number of winding layers and the area ratio of recessed holes per unit area of ​​each electrode within a certain range, insufficient wetting due to excessive winding thickness or insufficient area of ​​the recessed holes can be avoided, thereby ensuring the utilization rate of the battery's active materials.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a battery device. Background Technology

[0002] Currently, mainstream batteries still use liquid electrolyte systems. In liquid electrolyte batteries, the electrolyte needs to fully wet the separator and the active material layers of the positive and negative electrodes inside the cell in order to ensure the battery's charge and discharge performance, safety, and consistency.

[0003] Wound battery cells are typically manufactured by winding consecutive positive and negative electrode plates and a separator. The separator is located between adjacent positive and negative electrode plates. For wound battery cells, the cross-section is usually circular or a racetrack-shaped rectangle. Taking a rectangular wound cell as an example, because the electrode plates have taut arc sections during winding, the pressure and stretching during cell manufacturing make these arc sections more taut than straight sections. When filling with electrolyte, these arc sections are difficult to fully wet, and the inner electrode plates are even more difficult to wet completely, leading to insufficient wetting.

[0004] Areas where the electrode is not fully wetted will lead to a decrease in the utilization rate of active materials on the coating, and may even cause black spots to appear during use, which will seriously affect the cycle performance and lifespan of the battery. Utility Model Content

[0005] In view of this, the present invention provides a battery device to solve the problem that some electrodes in the current battery are not fully wetted, resulting in a reduced utilization rate of the active material on the coating.

[0006] In a first aspect, this utility model provides a battery device, which includes:

[0007] The shell has an internal cavity for receiving the contents;

[0008] The battery cell is housed in a receiving cavity. The battery cell has a wound structure, which is formed by stacking two electrode sheets with a spacer between them and then winding them together. Each electrode sheet is coated.

[0009] In the wound structure, a total of n layers are wound, and at least one arc segment is provided; the arc segment includes an outer layer region and an inner layer region. In the inner layer region, a recessed hole is provided on the coating of the arc segment of each electrode layer.

[0010] Within each unit area of ​​the electrode, the area of ​​the recessed holes on the coating is m, and 23≤n / m≤400.

[0011] Beneficial Effects: This embodiment, through a layered design limiting the winding structure and setting recessed holes in the electrode coating of the inner layer region—that is, setting recessed holes in the electrode coating of the innermost layers—can specifically improve the electrolyte wetting efficiency of the innermost electrode layers. During the wetting process, the recessed holes can briefly collect electrolyte and guide its penetration, solving the problem of difficult wetting of the inner electrode layers caused by the tightness of the curved section in the wound cell. Simultaneously, controlling the ratio between the number of winding layers and the area ratio of recessed holes per unit area of ​​each electrode within a certain range can avoid insufficient wetting due to excessive winding thickness or insufficient area of ​​recessed holes. This ensures the utilization rate of the battery's active materials, reduces problems such as localized overheating and black spots in the battery device, and ultimately improves the cycle life and safety of the battery device. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of this utility model, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the overall structure of the battery device in this embodiment;

[0014] Figure 2 This is a schematic diagram of the internal winding of the battery cell in this embodiment;

[0015] Figure 3 for Figure 2 A schematic diagram of the unfolded electrode layer in the inner region of the general;

[0016] Figure 4 This embodiment shows a schematic diagram of a substrate with a coating on one side.

[0017] Figure 5 This is a schematic diagram of a substrate with coatings on both sides in this embodiment.

[0018] Explanation of reference numerals in the attached figures:

[0019] 1. Battery cell; 11. Positive electrode plate; 12. Negative electrode plate; 121. Negative electrode tab; 13. Recessed hole; 14. Coating; 15. Tab adhesive; 16. Substrate; 17. Arc segment; 18. Straight segment; 2. Housing. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0021] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model 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 utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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 also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0023] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0024] Currently, mainstream batteries still use liquid electrolyte systems. In liquid electrolyte batteries, the electrolyte needs to fully wet the separator and the active material layers of the positive and negative electrodes inside the cell to ensure the battery's charge and discharge performance, safety, and consistency.

[0025] Specifically, the electrolyte is a liquid electrolyte that transports active ions. It is a liquid material that conducts ions while isolating electrons. The electrolyte is composed of chemical substances such as solvents, electrolyte salts, and additives. Solvents can be carbonates, carboxylic acid esters, or ethers; electrolyte salts can be lithium salts, sodium salts, or zinc salts. Additives can be vinylene carbonate, fluoroethylene carbonate, propylene sulfite, vinyl sulfite, etc.

[0026] Furthermore, cell 1 is the component in the battery where electrochemical reactions occur; it is the smallest unit in the battery capable of electrochemical reactions such as charging / discharging. Cell 1 is the basic unit in the battery and typically includes a positive electrode 11, a negative electrode 12, and a separator. Lithium-ion cells primarily function by the movement of lithium ions between the positive electrode 11 and the negative electrode 12. In a cuboid cell, thin-film structures are wound or stacked into an electrode assembly with a roughly cuboid shape.

[0027] Furthermore, a separator is disposed between the positive electrode 11 and the negative electrode 12 to separate them and prevent short circuits. The separator can be at least one of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride. A coating can also be provided on the surface of the separator. The coating can be an inorganic coating and, or an organic coating, wherein the inorganic coating material includes at least one of alumina, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite. The organic coating includes at least one of aramid coating and PVDF coating.

[0028] Furthermore, the positive electrode active material is the donor of metal ions, such as lithium ions and sodium ions, for the battery. For example, in the positive electrode of a lithium-ion battery, the positive electrode active material can reversibly intercalate and deintercalate lithium ions, making it the core carrier for storing and releasing chemical energy in the battery.

[0029] The positive electrode active material includes, but is not limited to, at least one of the following materials: lithium phosphates, lithium transition metal oxides and their respective modified compounds, or other conventional materials that can be used as positive electrode active materials for batteries. These positive electrode active materials can be used alone or in combination of two or more. Among them, lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0030] Furthermore, the negative electrode active material serves as a carrier for active ions (such as Li) transferred from the positive electrode during the charging and discharging process of the battery. These active ions can be inserted into or extracted, playing a role in energy storage and release. Negative electrode active materials include carbon-based materials (graphite, natural graphite, etc.), silicon-based materials (elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, etc.), tin-based materials (elemental tin, tin oxides, and tin alloys, etc.), lithium titanate materials, and metallic lithium materials.

[0031] As for wound cells, a cell 1 is generally manufactured by winding consecutive positive electrode 11, negative electrode 12, and separator, with the separator located between adjacent positive and negative electrode 11 and 12. For wound cell types, the cross-section of the cell is typically circular or a racetrack-shaped rectangle. Taking a rectangular wound cell as an example, due to the taut arc segment 17 formed during the winding process, the pressure and stretching during cell manufacturing result in a higher degree of tautness in the arc segment 17 compared to the straight segment 18. During electrolyte filling, the arc segment 17 is difficult to fully wet with the electrolyte, and the inner electrode layers are even more difficult to wet completely, leading to insufficient wetting. Areas where the electrode is not fully wetted result in reduced utilization of the active material on the coating 14, and may even lead to black spots during use, severely affecting the battery's cycle performance and lifespan.

[0032] In view of this, the present invention provides a battery device to solve the problem that some electrodes in the current battery are not fully wetted, resulting in a reduced utilization rate of the active material on the coating 14.

[0033] The following is combined Figures 1 to 5 The following describes embodiments of the present invention.

[0034] According to an embodiment of the present invention, a battery device is provided, which includes a casing and a battery cell 1.

[0035] Specifically, in this embodiment, the housing has an internal cavity, and the battery cell 1 is disposed in the cavity. In this embodiment, the battery cell 1 is a wound battery cell 1. The wound structure is formed by stacking and winding two electrode sheets with a spacer between them. Each electrode sheet has a coating 14, which is composed of an active material. The two electrodes have opposite polarities, that is, one is a positive electrode 11 and the other is a negative electrode 12.

[0036] Furthermore, in this embodiment, in the wound structure, a total of n layers are wound to form an arc segment 17 and a straight segment 18, and at least one arc segment 17 is provided. Of course, multiple arc segments 17 can also be provided according to the actual structural shape of the shell; this embodiment is merely an example. The arc segment 17 includes an outer layer region and an inner layer region. In the inner layer region, a recessed hole 13 is provided on the coating 14 of the arc segment 17 of each electrode layer. The recessed hole 13 is a pit that does not penetrate the active material layer, so that when the electrolyte is wetted, it can briefly accumulate in the recessed hole 13 and gradually penetrate into the inner layer region.

[0037] Furthermore, within each unit area of ​​the electrode, the area ratio of the recessed hole 13 on the coating 14 is m, and 23 ≤ n / m ≤ 400. Since the area of ​​the electrode is different for different battery specifications, and the number of winding layers of the cell 1 may be different for different battery specifications, it is necessary to control the value of n / m within a certain range to ensure that the parameter design can be applied to more battery specifications and improve the versatility of the solution design.

[0038] For example, the value of n / m can be 23, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, etc. Of course, this embodiment is only an example of the value of n / m, but it is not a limitation. Those skilled in the art can change it according to the actual situation, as long as the same technical effect is achieved.

[0039] By defining a layered design for the wound structure and providing recessed holes 13 on the inner layer electrode coating 14, this embodiment can specifically improve the electrolyte wetting efficiency of the inner layers of the electrode. During the wetting process, the recessed holes 13 can briefly collect electrolyte and guide its penetration, solving the problem of difficult wetting of the inner electrode caused by the tightness of the arc segment 17 in the wound cell 1. At the same time, by controlling the ratio between the number of winding layers and the area ratio of the recessed holes 13 per unit area of ​​each electrode within a certain range, insufficient wetting caused by excessive winding thickness or insufficient area of ​​the recessed holes 13 can be avoided. This ensures the utilization rate of the battery active material, reduces problems such as local overheating and black spots in the battery device, and thus improves the cycle life and safety of the battery device.

[0040] Furthermore, the greater the number of winding layers, the larger the area of ​​the recessed holes 13 needs to occupy on the coating 14, so that the electrolyte can be fully wetted. The smaller the number of winding layers, the smaller the area of ​​the recessed holes 13 can occupy on the coating 14, resulting in a larger total volume of active material and better battery capacity.

[0041] Furthermore, in an optional embodiment, in the wound structure, the a-th electrode layer from the outside to the inside is the starting layer of the inner layer region, where a is a positive integer.

[0042] For example, when a = 2 and n = 5, the inner region is between layers 2 and 5. When a = 3 and n = 8, the inner region is between layers 3 and 8.

[0043] Of course, this embodiment is merely an example of the specific values ​​of n and a, but it does not limit them. Those skilled in the art can make changes according to the actual situation, as long as the same technical effect can be achieved.

[0044] With this configuration, the inner layer region is set as the a-th layer from the outside in in this embodiment. This allows for precise targeting of the inner layer region most requiring optimized wetting in the wound structure based on the actual number of winding layers of the battery cell 1. This avoids redundant design of the outer layer region, reduces unnecessary processing of recessed holes 13 while ensuring the wetting effect, and lowers production costs. Furthermore, this embodiment can be adapted to the actual number of winding layers of the battery cell 1, enhancing the applicability of the wound battery cell 1.

[0045] Furthermore, in one optional implementation, a ≥ 5. For example, a can be a value of 5, 6, 7, 8, 9, 10, etc. Of course, this embodiment is merely an example of a specific value, but it is not a limitation. Those skilled in the art can make changes according to actual circumstances, as long as the same technical effect is achieved.

[0046] With this setting, this embodiment further refines the number of starting layers in the inner layer region by a≥5, ensuring that the inner layer region covers a sufficient number of deep electrode sheets, avoiding insufficient deep wetting due to the starting layer being too shallow, which is especially suitable for high-turn-count, high-capacity wound cells 1, and improves their long-term cycle stability.

[0047] Furthermore, in an alternative implementation, the value of m is between 30% and 65%.

[0048] For example, the value of m can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, etc. Of course, this embodiment is merely an example of the value of m, but it is not intended to limit the scope. Those skilled in the art can make changes according to the actual situation, as long as the same technical effect is achieved.

[0049] By controlling the value of m within a certain range, this embodiment can improve both the electrolyte's capacity and the effective area of ​​the active material. If m is too small, the recessed hole 13 will not provide enough space to collect the electrolyte, resulting in insufficient wetting. If m is too large, it may occupy too much active material area, reducing battery capacity. Therefore, controlling the value of m within a certain range can maximize the utilization rate of the active material and improve the battery's energy density while ensuring sufficient electrolyte wetting.

[0050] Furthermore, in an alternative embodiment, in the wound structure, m gradually increases from the outside to the inside.

[0051] With this configuration, m gradually increases from the outside to the inside in this embodiment, which means that m is designed in a gradient manner. This makes the wetting ability of the electrolyte gradually enhanced from the outer layer to the center layer, solving the problem that the center of the electrode is difficult to wet because it is farthest from the edge of the electrode. This achieves the step-by-step penetration of the electrolyte from the edge to the center, improving the sufficiency of the electrolyte when wetting the electrode.

[0052] Furthermore, in an optional embodiment, the depth of the recessed hole 13 is no greater than the thickness of the coating 14. For example, the depth of the recessed hole 13 can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, etc., of the coating 14 thickness. Of course, this embodiment is merely an example illustrating the specific ratio of hole depth to coating 14 thickness, but it is not intended to limit the scope. Those skilled in the art can modify it according to actual circumstances, as long as the same technical effect is achieved.

[0053] With this configuration, in this embodiment, the depth of the recessed hole 13 is no greater than the thickness of the coating 14. This avoids the equipment penetrating the coating 14 and damaging the substrate 16 of the electrode during the preparation of the recessed hole 13, thereby ensuring the structural strength of the electrode and preventing the risk of short circuits caused by damage to the substrate 16. At the same time, it also ensures that the recessed hole 13 only affects the active material in the coating 14 and does not affect the conductivity and structural properties of the substrate 16.

[0054] Furthermore, in an optional embodiment, for the positive electrode, the positive electrode current collector serves as the substrate 16, mainly used to attach the positive electrode active material, thereby collecting the current generated by the positive electrode active material and outputting the current to the outside.

[0055] The positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0056] For the negative electrode, the negative electrode current collector serves as the substrate 16, which plays the role of collecting current and is the carrier of the negative electrode slurry. The negative electrode slurry (negative electrode active material, conductive agent, binder, etc.) is coated on the negative electrode current collector. The negative electrode current collector collects electrons from the negative electrode active material and conducts them to the external circuit, realizing the process of converting chemical energy into electrical energy.

[0057] The negative electrode current collector can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium, and can be surface-plated with silver. Composite current collectors may include a polymer substrate and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0058] Furthermore, in an optional embodiment, the depth of the recessed hole 13 is w1, and the depth w1 of the recessed hole 13 is between 10um and 100um.

[0059] For example, the value of the hole depth w1 can be 10um, 20um, 30um, 40um, 50um, 60um, 70um, 80um, 90um, 100um, etc. Of course, this embodiment is only an example of the value of the hole depth w1, but it is not a limitation. Those skilled in the art can change it according to the actual situation, as long as the same technical effect can be achieved.

[0060] With this configuration, the depth w1 of the recessed hole 13 is limited to a certain range in this embodiment, thereby ensuring that the recessed hole 13 has sufficient space to accommodate the electrolyte and improving the wetting guidance capability. At the same time, it does not cause the recessed hole 13 to excessively weaken the structural strength of the coating 14, ensuring that the coating 14 can still be used normally.

[0061] Furthermore, in one optional embodiment, the recessed hole 13 is a hemispherical or semi-ellipsoidal groove. Of course, this embodiment is merely an example illustrating the specific structural type of the recessed hole 13, and is not intended to limit it. Those skilled in the art can modify it according to actual circumstances, as long as the same technical effect is achieved.

[0062] With this configuration, the recessed hole 13 in this embodiment is set as a hemispherical or semi-ellipsoidal shape. This type of curved surface structure is easy to form through the rolling process and can directly adapt to the protrusions of the rollers on existing rolling machines, thereby reducing the production difficulty. At the same time, the use of curved surface transition can reduce stress concentration in the coating 14 and avoid cracking of the active material at the edge of the recessed hole 13.

[0063] Furthermore, in an optional embodiment, within the confinement range of the arc segment 17 for each electrode layer, the distance between two adjacent recessed holes 13 gradually decreases along the direction close to the geometric center of the confinement range. That is, each electrode layer has a rectangular structure within the arc segment 17, which constitutes the confinement range, and the distance between two adjacent recessed holes 13 gradually decreases along the direction close to the geometric center of this rectangular structure.

[0064] With this configuration, the distance between adjacent holes near the geometric center is reduced, thereby increasing the density of the recessed holes 13. During the electrolyte wetting process, the electrolyte can be accelerated to diffuse towards the central region, solving the problem of slow wetting in the central region due to the long distance and path, and thus improving the wetting efficiency of the central region of the electrode.

[0065] Furthermore, in an optional embodiment, the distance w2 between the center points of two adjacent recessed holes 13 is between 30 μm and 150 μm.

[0066] For example, the value of distance w2 can be 30um, 40um, 50um, 60um, 70um, 80um, 90um, 100um, 110um, 120um, 130um, 140um, 150um, etc. Of course, this embodiment is merely an example of the value of distance w2, but it is not intended to limit it. Those skilled in the art can modify it according to the actual situation, as long as the same technical effect is achieved.

[0067] By setting the distance between adjacent holes within a certain range, this embodiment avoids a decrease in the structural strength of the coating 14 due to two adjacent recessed holes 13 being too close, thereby preventing the active material on the coating 14 from falling off. Furthermore, it also avoids interruption of electrolyte conduction due to two adjacent recessed holes 13 being too far apart, thus forming a continuous penetration path and ensuring the continuity of wetting and the structural stability of the coating 14.

[0068] Furthermore, in an optional embodiment, within the confined area of ​​the arc segment 17 for each electrode layer, the area of ​​the recessed hole 13 gradually increases along the direction close to the geometric center of the confined area. That is, each electrode layer has a rectangular structure within the arc segment 17, which constitutes the confined area, and the area of ​​the recessed hole 13 gradually increases along the direction close to the geometric center of this rectangular structure.

[0069] With this configuration, in this embodiment, the area of ​​the recessed hole 13 near the geometric center gradually increases, thereby allowing the recessed hole 13 in the central region to accommodate more electrolyte, thus enhancing the electrolyte wetting effect in the central region. Combined with the increased density of the recessed hole 13, the amount and speed of electrolyte wetting in the central region can be further improved.

[0070] Furthermore, in an alternative embodiment, in the inner layer region, the distance w3 between the recessed hole 13 and the edge of the electrode is between 15 μm and 150 μm.

[0071] For example, the value of distance w3 can be 15um, 20um, 30um, 40um, 50um, 60um, 70um, 80um, 90um, 100um, 110um, 120um, 130um, 140um, 150um, etc. Of course, this embodiment is merely an example of the value of distance w3, and does not limit it. Those skilled in the art can change it according to the actual situation, as long as the same technical effect is achieved.

[0072] With this configuration, the distance between the hole and the edge of the electrode is limited to a certain range, ensuring that the outermost recessed hole 13 is in an area where the electrolyte can reach it quickly. This avoids the recessed hole 13 being too far inward, which would prevent the electrolyte from reaching it. As a result, the electrolyte can be conducted step by step from the outermost hole to the center, achieving rapid and effective wetting.

[0073] Furthermore, in an optional embodiment, the two electrodes of the wound structure include a positive electrode 11 and a negative electrode 12, such that in the wound structure, adjacent layers of electrodes have opposite polarities, and the area of ​​the positive electrode 11 is smaller than the area of ​​the negative electrode 12. For example, the area of ​​the negative electrode 12 can be 8%, 9%, 10%, 11%, 12%, etc., larger than that of the positive electrode 11. Of course, this embodiment is merely an example of the area difference between the two electrodes, but it is not intended to limit the scope. Those skilled in the art can modify it according to actual conditions, as long as the same technical effect is achieved.

[0074] With this configuration, the area of ​​the negative electrode 12 is larger than that of the positive electrode 11, so that the negative electrode 12 can provide sufficient space for the ions extracted from the positive electrode 11 to be inserted, reducing the battery capacity decay caused by insufficient space in the negative electrode 12, and also reducing the rate of battery capacity decay, thus improving the cycle life of the battery.

[0075] Furthermore, in an alternative embodiment, the n / m value in the positive electrode 11 is between 23 and 380. In the negative electrode 12, the n / m value is between 23 and 360.

[0076] For example, in the positive electrode 11, the value of n / m can be 23, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 350, 380, etc. Of course, this embodiment is merely an example of the value of n / m, but it is not intended to limit it. Those skilled in the art can make changes according to the actual situation, as long as the same technical effect is achieved.

[0077] For example, in the negative electrode 12, the value of n / m can be 23, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 350, 360, etc. Of course, this embodiment is merely an example of the value of n / m, but it is not a limitation. Those skilled in the art can make changes according to the actual situation, as long as the same technical effect is achieved.

[0078] With this configuration, since the positive electrode 11 and the negative electrode 12 have different areas, the parameters of the positive electrode 11 and the negative electrode 12 can be optimized separately, thereby improving the wetting effect of the positive electrode 11 and the negative electrode 12 respectively, thus improving the overall wetting effect of the battery.

[0079] Furthermore, in an optional embodiment, a negative electrode tab 121 is provided on the negative electrode sheet 12, and the substrate 16 of the negative electrode sheet 12 is coated with tab adhesive 15 at least on the side near the negative electrode tab 121.

[0080] Furthermore, the negative electrode tab 121 is typically disposed on one side of the negative current collector and is either separately formed or integrally formed with the negative current collector. It is electrically connected to the negative current collector to conduct current through it. Similarly, the positive electrode tab is typically disposed on one side of the positive current collector and is either separately formed or integrally formed with it. It is electrically connected to the positive current collector to conduct current through it. Both the positive and negative electrode tabs 121 are made of a highly conductive metallic material (such as copper, aluminum, or nickel).

[0081] Furthermore, the tab adhesive 15 is typically coated on at least one side of the negative electrode current collector near the negative electrode tab 121, or on at least one side of the surface of the negative electrode tab 121, to prevent short circuit between the negative electrode tab 121 and the positive electrode plate 11. Alternatively, the tab adhesive 15 can also be coated on at least one side of the positive electrode current collector near the positive electrode tab, or on at least one side of the surface of the positive electrode tab, to prevent short circuit between the positive electrode tab and the negative electrode plate 12. This also helps prevent breakage of the tabs when bending them during battery cell assembly. Tab adhesives mainly include insulating materials such as PVDF (polyvinylidene fluoride), boehmite, polypropylene, and polyethylene.

[0082] With this configuration, the tab adhesive 15 is applied to the negative tab 121 in this embodiment, which can fix the position of the tab and prevent the tab from folding during processing or use, thereby avoiding short circuit between the positive tab and the negative electrode 12, enhancing the safety of the battery structure, and reducing the risk of thermal runaway caused by short circuit.

[0083] Furthermore, in an optional embodiment, a coating 14 is provided on at least one side of the substrate 16 of the negative electrode 12, and the coating 14 is coated with tab adhesive 15 on the side near the negative electrode tab 121.

[0084] With this configuration, in this embodiment, tab adhesive 15 is applied to the side of coating 14 near the negative electrode tab 121, which fixes the tab by the adhesive layer and thus prevents short circuits. Since the coating is only applied to the edge, it also avoids covering too much active material with the adhesive layer, thereby improving the utilization rate of the active material.

[0085] Furthermore, in an alternative embodiment, the n / m value in the negative electrode 12 is between 23 and 320.

[0086] For example, in the negative electrode 12, the value of n / m can be 23, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 320, etc. Of course, this embodiment is only an example of the value of n / m, but it is not a limitation. Those skilled in the art can change it according to the actual situation, as long as the same technical effect can be achieved.

[0087] With this configuration, the overall area of ​​the negative electrode 12 with tab adhesive 15 changes in this embodiment, thus requiring adjustment of the n / m value for optimization. Simultaneously, because the tab adhesive 15 hinders electrolyte penetration from that side, allowing electrolyte to enter only from the other three sides, the electrolyte capacity and conductivity of the recessed hole 13 can be simultaneously optimized and improved, compensating for the reduced wetting path caused by the tab adhesive 15 and ensuring sufficient overall wetting of the negative electrode 12.

[0088] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery device, characterized in that, include: The shell has an internal cavity for receiving the contents; A battery cell (1) is disposed in the cavity. The battery cell (1) has a wound structure. The wound structure is formed by stacking two electrode sheets with a spacer membrane and then winding them together. Each electrode sheet is provided with a coating (14). In the wound structure, a total of n layers are wound, and at least one arc segment (17) is provided; the arc segment (17) includes an outer layer region and an inner layer region. In the inner layer region, a recessed hole (13) is provided on the coating (14) of the arc segment (17) of each electrode sheet. Within a unit area of ​​each electrode, the area ratio of the recessed hole (13) on the coating (14) is m, and 23≤n / m≤400.

2. The battery device according to claim 1, characterized in that, In the wound structure, the a-th electrode layer from the outside to the inside is the starting layer of the inner layer region, where a is a positive integer.

3. The battery device according to claim 2, characterized in that, a≥5。 4. The battery device according to claim 3, characterized in that, The value of m is between 30% and 65%.

5. The battery device according to claim 4, characterized in that, In the wound structure, m gradually increases from the outside to the inside.

6. The battery device according to any one of claims 1 to 5, characterized in that, The depth of the recessed hole (13) is not greater than the thickness of the coating (14).

7. The battery device according to claim 6, characterized in that, The depth of the recessed hole (13) is w1, and the depth w1 of the recessed hole (13) is between 10um and 100um.

8. The battery device according to claim 7, characterized in that, The recessed hole (13) is a groove with a hemispherical structure or a groove with a semi-ellipsoidal structure.

9. The battery device according to any one of claims 1 to 5, characterized in that, Within the confinement range of the arc segment (17) of each electrode layer, the distance between two adjacent recessed holes (13) gradually decreases along the direction close to the geometric center of the confinement range.

10. The battery device according to claim 9, characterized in that, The distance w2 between the center points of two adjacent recessed holes (13) is between 30um and 150um.

11. The battery device according to any one of claims 1 to 5, characterized in that, Within the confinement range of the arc segment (17) in each electrode layer, the area of ​​the recessed hole (13) gradually increases along the direction close to the geometric center of the confinement range.

12. The battery device according to any one of claims 1 to 5, characterized in that, In the inner layer region, the distance w3 between the recessed hole (13) and the edge of the electrode is between 15 μm and 150 μm.

13. The battery device according to any one of claims 1 to 5, characterized in that, In the wound structure, the two electrodes include a positive electrode (11) and a negative electrode (12), and the area of ​​the positive electrode (11) is smaller than the area of ​​the negative electrode (12).

14. The battery device according to claim 13, characterized in that, In the positive electrode (11), the value of n / m is between 23 and 380; In the negative electrode (12), the value of n / m is between 23 and 360.

15. The battery device according to claim 14, characterized in that, The negative electrode sheet (12) is provided with a negative electrode tab (121), and the substrate (16) of the negative electrode sheet (12) is coated with tab adhesive (15) at least on the side near the negative electrode tab (121).

16. The battery device according to claim 15, characterized in that, The coating (14) is provided on at least one side of the substrate (16) of the negative electrode sheet (12), and the coating (14) is coated with tab adhesive (15) on the side near the negative electrode tab (121).

17. The battery device according to claim 15 or 16, characterized in that, In the negative electrode (12), the value of n / m is between 23 and 320.

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