Electrode assembly, battery and electric equipment

Abstract

The utility model provides an electrode assembly, a battery and electric equipment, and relates to the technical field of energy storage devices. The electrode assembly comprises a positive pole piece, a diaphragm, a negative pole piece and a flexible liquid storage substance which are arranged in a laminated manner; the diaphragm is arranged between the positive pole piece and the negative pole piece; the negative electrode plate comprises a negative electrode current collector, a first negative electrode active material layer and a second negative electrode active material layer, the second negative electrode active material layer is arranged on one side, far away from the negative electrode current collector, of the first negative electrode active material layer, and the material average particle size of the second negative electrode active material layer is smaller than that of the first negative electrode active material layer; and the liquid storage substance is arranged between the diaphragm and the negative current collector. The arrangement of the first negative electrode active material layer and the second negative electrode active material layer is beneficial for embedding lithium ions into the deep part of the negative electrode plate, and the liquid storage material can release a certain electrolyte in the use process of the battery, so that the consumption speed of the electrolyte is reduced, the battery can keep relatively good charge-discharge performance for a long time, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of energy storage devices, and in particular to an electrode assembly, a battery, and an electrical device. Background Art

[0002] Lithium-ion batteries have become the energy storage devices of mainstream electronic products. As people's requirements for batteries increase, a high-performance lithium-ion battery must have good charge and discharge performance while taking into account long cycle life.

[0003] The current process for manufacturing lithium-ion batteries typically involves winding or stacking the positive and negative electrodes and separators into a core, which is then hot-pressed and placed into a casing before being injected and formed. The electrolyte injected into the casing serves as the medium for lithium ion migration between the positive and negative electrodes. The degree of electrolyte wetting of the core determines whether lithium ions can migrate quickly and efficiently between the positive and negative electrodes during charge and discharge, and thus the battery's charge and discharge performance and lifespan.

[0004] However, the electrolyte is continuously consumed during the battery charging and discharging process. When the consumption of the electrolyte reaches a certain level, the capacity of the battery will rapidly decay, followed by a decline in the battery charging and discharging performance and a shortened lifespan.

[0005] Therefore, how to slow down the consumption of electrolyte is an inevitable proposition to improve the charge and discharge performance of the battery and extend the battery life. Utility Model Content

[0006] In view of the above problems, embodiments of the present application provide an electrode assembly, a battery, and an electrical device, which can replenish the electrolyte to achieve the effect of slowing down the consumption rate of the electrolyte.

[0007] According to a first aspect of an embodiment of the present application, an electrode assembly is provided, comprising a stacked positive electrode sheet, a separator, a negative electrode sheet and a flexible liquid storage material; the separator is arranged between the positive electrode sheet and the negative electrode sheet; the negative electrode sheet comprises a negative electrode collector, a first negative electrode active material layer and a second negative electrode active material layer, the second negative electrode active material layer is arranged on the side of the first negative electrode active material layer away from the negative electrode collector, and the average particle size of the material of the second negative electrode active material layer is smaller than the average particle size of the material of the first negative electrode active material layer; the liquid storage material is arranged between the separator and the negative electrode collector.

[0008] During the battery's charge and discharge process, lithium ions transfer between the positive and negative electrodes through the separator, while electrons transfer in opposite directions to the lithium ions. Therefore, the positive electrode, negative electrode, and separator constitute the basic structure of the battery. Because the average particle size of the material in the second negative electrode active material layer is smaller than that in the first negative electrode active material layer, the gaps between the materials in the second negative electrode active material layer are greater than the gaps between the materials in the first negative electrode active material layer. As a result, the kinetics of the second negative electrode active material layer are higher than those of the first negative electrode active material layer. The second negative electrode active material layer can accommodate a larger amount of electrolyte, making it easier for lithium ions to embed into the negative electrode. In other words, during the charge and discharge process, more lithium ions will participate in the chemical reaction, reducing the precipitation of lithium ions on the surface of the negative electrode, slowing the consumption of lithium ions on the negative electrode, and extending the battery's service life. The liquid storage material is arranged between the diaphragm and the negative electrode current collector. When the battery expands during charging, the diaphragm and the negative electrode current collector squeeze the liquid storage material, causing the liquid storage material to release a certain amount of electrolyte, thereby replenishing the electrolyte in the shell of the battery cell, slowing down the consumption rate of the electrolyte, and allowing the battery using the above-mentioned electrode assembly to maintain good charge and discharge performance for a long time, thereby extending the battery life.

[0009] In some embodiments, the liquid storage material is attached to a surface of the separator close to the negative electrode.

[0010] By adopting this solution, the liquid storage material adheres to the surface of the diaphragm and can be assembled with the diaphragm, the positive electrode sheet, and the negative electrode sheet to form an electrode assembly, eliminating the need for a separate assembly step for the liquid storage material. Furthermore, when the battery expands during charging, the electrolyte released by the liquid storage material can directly infiltrate the surface of the negative electrode sheet, providing a carrier and channel for lithium ions to embed into the negative electrode sheet, reducing the problem of lithium plating on the surface of the negative electrode sheet, improving the battery's charge and discharge performance, and extending the battery's service life.

[0011] In some embodiments, the liquid storage material is disposed in the second negative electrode active material layer and / or in the first negative electrode active material layer.

[0012] By adopting the above scheme, the liquid storage material can be in the second negative electrode active material layer or the first active material layer, so that lithium ions can be directly embedded in the negative electrode plate through the electrolyte in the liquid storage material. The liquid storage material can also release the electrolyte when squeezed and infiltrate the first negative electrode active material or the second negative electrode active material around the liquid storage material, so that the first negative electrode active material layer and the second negative electrode active material layer have sufficient lithium ion channels for lithium ion embedding.

[0013] In some embodiments, the liquid storage material is a rod-shaped particle, and the maximum dimension of the liquid storage material in the thickness direction of the negative electrode sheet is larger than the maximum dimension of the liquid storage material in other directions, where the other directions are directions other than the thickness direction of the negative electrode sheet.

[0014] By adopting the above scheme, the rod-shaped particles of the liquid storage material are conducive to the entry of lithium ions into the first negative electrode active material or the second negative electrode active material along the length direction of the liquid storage material. Since the maximum dimension of the liquid storage material in the thickness direction of the negative electrode sheet is larger than the maximum dimension of the liquid storage material in other directions, the length direction of the liquid storage material is basically consistent with the thickness direction of the negative electrode sheet. Therefore, lithium ions can penetrate deeper into the negative electrode sheet along the length direction of the liquid storage material, which is beneficial to improving the charge and discharge performance of the battery.

[0015] In some embodiments, the liquid storage material is disposed between the second negative electrode active material layer and the first negative electrode active material layer.

[0016] By adopting this solution, the liquid storage material facilitates the passage of lithium ions, thereby facilitating the entry of lithium ions from the second negative electrode active material layer into the first negative electrode active material layer, thereby increasing the embedding depth of lithium ions in the negative electrode sheet. When the liquid storage material is squeezed, the electrolyte in the liquid storage material can directly infiltrate the first and second negative electrode active material layers, maintaining the first and second negative electrode active material layers in a moist state for a long time, further improving the battery's charge and discharge performance and extending the battery's service life.

[0017] In some embodiments, the liquid storage material is disposed between the first negative electrode active material layer and the negative electrode current collector.

[0018] By adopting the above scheme, the area between the first negative electrode active material layer and the negative electrode current collector is the farthest from the surface of the negative electrode plate, which is not easily wetted by the electrolyte. By setting the liquid storage material here, the electrolyte retention amount here can be increased, so that the first negative electrode active material layer can remain wetted by the electrolyte for a long time, which is conducive to the embedding of lithium ions into the first negative electrode active material layer, improving the charge and discharge performance of the battery, and extending the battery life.

[0019] In some embodiments, the liquid storage material is attached to a side of the second negative electrode active material layer away from the first negative electrode active material layer.

[0020] By adopting this solution, the liquid storage material is attached to the surface of the second negative electrode active material layer on the side away from the first negative electrode active material layer. It can be assembled with the negative electrode sheet, the positive electrode sheet, and the separator to form an electrode assembly, eliminating the need for a separate assembly step for the liquid storage material. Furthermore, when the battery expands during charging, the electrolyte released by the liquid storage material can directly infiltrate the surface of the negative electrode sheet, providing a carrier and channel for lithium ions to embed into the negative electrode sheet, reducing the problem of lithium plating on the surface of the negative electrode sheet, improving the battery's charge and discharge performance, and extending the battery's service life.

[0021] In some embodiments, the reservoir material is a porous gel or silica gel.

[0022] By adopting this solution, the porous gel or silicone not only utilizes its pores to store more electrode liquid, increasing the electrolyte holding capacity of the reservoir, but also, since gel or silicone is a flexible material with high elasticity, it can recover after repeated compression and can withstand a certain amount of compression in all directions. Using porous gel or silicone as a reservoir material can adapt to the actual operating conditions of the electrode assembly without damaging the original structure of the electrode assembly.

[0023] According to a second aspect of the embodiments of the present application, a battery is provided, comprising the electrode assembly according to any one of the embodiments of the above subject matter.

[0024] According to a third aspect of the embodiments of the present application, there is provided an electrical device comprising the battery in the above embodiment.

[0025] The batteries and electrical equipment in the embodiments of the second and third aspects mentioned above all include the electrode assembly in the first subject mentioned above. Therefore, the batteries and electrical equipment have the various structures and beneficial effects of the above-mentioned electrode assemblies. Please refer to the structural descriptions and beneficial effects in the various embodiments of the electrode assemblies for details. The embodiments of this application will not repeat the relevant structures of the batteries and electrical equipment.

[0026] In the embodiments of the present application, a first negative electrode active material layer and a second negative electrode active material layer having different particle sizes are arranged on the negative electrode current collector. The second negative electrode active material layer having a smaller average particle size is arranged on the side of the first negative electrode active material layer having a larger average particle size away from the negative electrode current collector. This allows the second negative electrode active material layer to have higher kinetics than the first negative electrode active material layer, allowing the second negative electrode active material layer to accommodate a larger amount of electrolyte, making it easier for lithium ions to intercalate into the negative electrode sheet. By arranging a liquid storage material between the separator and the negative electrode current collector, when the battery expands during charging, the separator and the negative electrode current collector squeeze the liquid storage material, causing the liquid storage material to release a certain amount of electrolyte, thereby replenishing the electrolyte in the battery cell housing and slowing down the rate of electrolyte consumption. This allows the battery using the above electrode assembly to maintain good charge and discharge performance for a long time, extending the battery life.

[0027] The above description is only an overview of the technical solutions of the embodiments of the present application. In order to more clearly understand the technical means of the embodiments of the present application, they can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiments of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1 Schematic diagram of the structure of the electrode assembly in one embodiment of the present application.

[0030] Figure 2 This is a schematic structural diagram of the first negative electrode plate in one embodiment of the present application.

[0031] Figure 3 This is a schematic structural diagram of a diaphragm in one embodiment of the present application.

[0032] Figure 4 Schematic diagram of the structure of the second negative electrode plate in one embodiment of the present application.

[0033] Figure 5 Schematic diagram of the structure of the third negative electrode plate in one embodiment of the present application.

[0034] Figure 6 Schematic diagram of the structure of the fourth negative electrode plate in one embodiment of the present application.

[0035] Explanation of reference numerals: 100, positive electrode sheet; 200, separator; 300, negative electrode sheet; 310, negative electrode current collector; 320, first negative electrode active material layer; 330, second negative electrode active material layer; 400, liquid storage material. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0038] The terms "comprises", "comprising" and "having" and any variations thereof in the specification, claims and drawings of this application are intended to cover but not exclude other contents. The word "a" or "an" does not exclude the presence of a plurality.

[0039] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0040] The term "and / or" in this document simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0041] The directional words appearing in the following description are all directions shown in the drawings, and do not limit the specific structure of the electrode assembly, battery or electrical equipment of the present application. For example, in the description of the present application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application.

[0042] In addition, the terms "first", "second", etc. in the description and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order, and may explicitly or implicitly include one or more such features.

[0043] In the description of this application, unless otherwise specified, "plurality" means more than two (including two), and similarly, "multiple groups" means more than two (including two).

[0044] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, "connected" or "connected" in a mechanical structure can refer to a physical connection. For example, a physical connection can be a fixed connection, such as a fixed connection via a fixing member, such as a screw, bolt, or other fixing member. A physical connection can also be a detachable connection, such as a mutual snap-fit ​​connection. A physical connection can also be an integral connection, such as a connection formed by welding, bonding, or integral molding. In addition to referring to a physical connection, "connected" or "connected" in a circuit structure can also refer to an electrical connection or a signal connection. For example, it can be a direct connection, i.e., a physical connection, or an indirect connection through at least one intermediate element, as long as the circuit is interconnected. It can also refer to internal communication between two elements. A signal connection can refer to a signal connection through a circuit or a signal connection through a media medium, such as radio waves. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0045] The present application discloses an electrode assembly, a battery, or an electrical device, wherein the battery includes the electrode assembly, and the electrical device includes the battery, and can be powered by the battery. The electrical device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, an energy storage device, an amusement ride, an elevator, and a lifting device, etc. The vehicle may be a fuel vehicle, a gas vehicle, or a new energy vehicle, wherein the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, etc.; the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.; the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, or an electric airplane toy, etc.; the electric tool may include a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator, and an electric planer, etc.; the energy storage device may be an energy storage wall, a base station energy storage, a container energy storage, etc.; the amusement ride may be a carousel, a bungee jumping machine, etc. This application does not impose any special restrictions on the above-mentioned electrical equipment.

[0046] For new energy vehicles, the above batteries can be used as a driving power source, thereby replacing fossil fuels to provide driving power.

[0047] The above-mentioned battery can be a battery cell or a battery pack or a battery module. When the above-mentioned battery is a battery pack, the battery pack specifically includes a battery management system (BMS) and a plurality of the above-mentioned battery cells. The plurality of battery cells can be electrically connected in series, in parallel, or in a mixture of series and parallel, and communicated with the battery management system to form a battery pack. The above-mentioned battery management system controls and monitors the working status of each battery cell. In addition, the plurality of battery cells can also be connected in series and / or in parallel first, and form a battery module with the module management system, and then the plurality of battery modules can be electrically connected in series, in parallel, or in a mixture of series and parallel, and together with the battery management system form a battery pack.

[0048] The multiple battery cells in the battery pack or battery module can be mounted on a supporting structure such as a box, frame, or bracket. Electrical connections can be made between the battery cells and between the battery cells and the battery management system via a busbar, such as a tab. The battery cells can be lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, and their outer contours can be cylindrical, flat, rectangular, or other shapes, but are not limited to these.

[0049] Typically, a battery cell consists of a battery housing and an electrode assembly, which is housed within the battery housing. The electrode assembly is the smallest unit in the battery that undergoes electrochemical reactions, enabling the charge and discharge of the battery cell. It typically includes a positive electrode sheet, a negative electrode sheet, and a separator separating the positive and negative electrodes. The battery housing is filled with an electrolyte that penetrates the interior of the electrode assembly, providing an ion migration pathway for the electrochemical reaction and acting as a conductor.

[0050] During the use of existing batteries, as the number of charge and discharge cycles increases, the electrolyte will gradually be consumed, resulting in a decrease in battery capacity, poor charge and discharge performance, and a shortened battery life.

[0051] In view of the above problems, the embodiments of the present application provide an electrode assembly, a battery, and an electrical device. Figure 1 Schematic diagram of the structure of the electrode assembly. Figure 2 Schematic diagram of the structure of the negative electrode.

[0052] Please refer to Figure 1 and Figure 2, an embodiment of the present application provides an electrode assembly, including a stacked positive electrode sheet 100, a separator 200, a negative electrode sheet 300 and a flexible liquid storage material 400; the separator 200 is arranged between the positive electrode sheet 100 and the negative electrode sheet 300; the negative electrode sheet 300 includes a negative electrode collector 310, a first negative electrode active material layer 320 and a second negative electrode active material layer 330, the second negative electrode active material layer 330 is arranged on the side of the first negative electrode active material layer 320 away from the negative electrode collector 310, and the average particle size of the material of the second negative electrode active material layer 330 is smaller than the average particle size of the material of the first negative electrode active material layer 320; the liquid storage material 400 is arranged between the separator 200 and the negative electrode collector 310.

[0053] The electrode assembly can be a wound structure or a laminated structure, which is not limited in the present embodiment. Figure 1 The wound structure is used as an example. Taking the electrode assembly as a wound structure as an example, the negative electrode sheet 300, the separator 200, and the positive electrode sheet 100 can be stacked in sequence, and then the stacked three-layer structure is wound into a roll. Each position of the roll structure is stacked with the positive electrode sheet 100, the separator 200, and the negative electrode sheet 300.

[0054] Among them, the negative electrode current collector 310 is usually a structure or part that collects current. The negative electrode current collector 310 can be various materials in the field that are suitable for use as the negative electrode current collector 310 of lithium-ion batteries. For example, the negative electrode current collector 310 can include but is not limited to metal foil, and more specifically can include but is not limited to copper foil or carbon-coated copper foil.

[0055] The first negative electrode active material layer 320 and the second negative electrode active material layer 330 are collectively referred to as negative electrode active material layers. The materials of the first negative electrode active material layer 320 and the second negative electrode active material layer 330 may include, but are not limited to, one or more of graphite, soft carbon, hard carbon, carbon fiber, mesocarbon microbeads, silicon-based materials, tin-based materials, lithium titanate, or other metals capable of forming an alloy with lithium. Furthermore, the materials of the first negative electrode active material layer 320 and the second negative electrode active material layer 330 may be the same or different.

[0056] In the present application, the maximum particle size of the material of the first negative electrode active material layer 320 and the maximum particle size of the material of the second negative electrode active material layer 330 can be controlled to achieve the purpose of controlling the average particle size of the material of the second negative electrode active material layer 330 to be smaller than the average particle size of the material of the first negative electrode active material layer 320. The embodiments of the present application do not specify the control and measurement method of the average particle size of the material of the first negative electrode active material layer 320 and the average particle size of the material of the second negative electrode active material layer.

[0057] In some embodiments, the positive electrode sheet 100 may also include a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector may be any material in the art suitable for use as a positive electrode current collector for lithium-ion batteries. For example, the positive electrode current collector may include but is not limited to metal foil, and more specifically may be aluminum foil or carbon-coated aluminum foil.

[0058] The material of the positive electrode active material layer includes at least a binder and a conductive agent, wherein the conductive agent can be a lithium-containing transition metal oxide or phosphide, etc. For example, the positive electrode active material layer includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate or a ternary material.

[0059] The separator 200 is a critical component of the electrode assembly. Its primary function is to separate the positive electrode sheet 100 from the negative electrode sheet 300, preventing electrons from freely passing through the electrode sheet. However, ions in the electrolyte can freely pass between the positive electrode sheet 100 and the negative electrode sheet 300, thus preventing battery short circuits and explosions. Materials for the separator 200 include, but are not limited to, PE (polyethylene) and PP (polypropylene).

[0060] When the battery is charging, lithium ions are separated from the positive electrode sheet 100, pass through the separator 200 and the electrolyte to the negative electrode sheet 300, and at the same time, electrons are transferred from the positive electrode sheet 100 to the negative electrode sheet 300 through external wires; the lithium ions are embedded in the negative electrode active material and react with the electrons on the negative electrode sheet 300 to generate lithium atoms.

[0061] When the battery is discharging, the electrical equipment is running or some of its functions are running, causing the battery to discharge externally. During this process, lithium ions are separated from the negative electrode plate 300, pass through the diaphragm 200 and the electrolyte to the positive electrode plate 100, and at the same time, electrons are separated from the negative electrode plate 300 and pass through external wires to the positive electrode plate 100; the lithium ions are embedded in the positive active material and react with the electrons in the positive electrode plate 100 to generate lithium atoms.

[0062] Since the average particle size of the material of the second negative electrode active material layer 330 is smaller than the average particle size of the material of the first negative electrode active material layer 320, the gaps between the materials of the second negative electrode active material layer 330 are greater than the gaps between the materials of the first negative electrode active material layer 320. Therefore, the kinetics of the second negative electrode active material layer 330 is higher than that of the first negative electrode active material layer 320. The second negative electrode active material layer 330 can accommodate more electrolyte, and lithium ions are more easily embedded in the negative electrode plate 300. That is to say, during the charge and discharge process, more lithium ions will participate in the chemical reaction, reducing the precipitation of lithium ions on the surface of the negative electrode plate 300, slowing down the consumption rate of lithium ions on the negative electrode plate 300, and extending the service life of the battery.

[0063] The liquid storage material 400 is a material for storing electrolyte, and may constitute a separate layer structure, or may be dispersed and exist at any position between the separator 200 and the negative electrode current collector 310 .

[0064] In some embodiments, the liquid storage material 400 may have a certain degree of flexibility so that it can change in shape as the electrode assembly expands and contracts.

[0065] The material of the liquid storage material 400 can be varied, as long as it does not affect the normal electrical cycle reaction of the battery.

[0066] In some embodiments, the liquid storage material 400 is a porous skeleton material, the pores of the skeleton material are filled with a substance that can absorb liquid, such as conductive carbon black. The skeleton material and the liquid absorbing substance are combined to store electrolyte.

[0067] In other embodiments, the liquid storage material 400 is a porous gel or silica gel. Porous gel or silica gel not only utilizes its pores to store more electrode liquid, thereby increasing the electrolyte holding capacity of the liquid storage material 400, but also, gel or silica gel is a flexible material with high elasticity, capable of recovering its shape after repeated squeezing, and can withstand a certain amount of squeezing in all directions. Using porous gel or silica gel as the liquid storage material 400 can adapt to the actual operating conditions of the electrode assembly without damaging the original structure of the electrode assembly.

[0068] The liquid storage material 400 is arranged between the diaphragm 200 and the negative electrode current collector 310. When the battery expands during charging, the diaphragm 200 and the negative electrode current collector 310 squeeze the liquid storage material 400, causing the liquid storage material 400 to release a certain amount of electrolyte, thereby replenishing the electrolyte in the shell of the battery cell, slowing down the consumption rate of the electrolyte, and allowing the battery using the above-mentioned electrode assembly to maintain good charge and discharge performance for a long time, thereby extending the battery life.

[0069] Several possible locations for the liquid storage material 400 are listed and described below.

[0070] Figure 3 A schematic diagram of the structure of a diaphragm provided in an embodiment of the present application is shown in FIG. Figure 3 As shown, in some embodiments, the liquid storage material 400 is attached to a surface of the separator 200 close to the negative electrode plate 300 .

[0071] For example, an adhesive may be sprayed on the surface of the diaphragm 200 , and then the liquid storage material 400 may be sprayed on the adhesive, so that the liquid storage material 400 adheres to the surface of the diaphragm 200 .

[0072] By adopting the above solution, the liquid storage material 400 is attached to the surface of the separator 200 and can be assembled with the separator 200, the positive electrode sheet 100, and the negative electrode sheet 300 to form an electrode assembly, eliminating the need for a separate assembly step for the liquid storage material 400. In addition, when the battery expands during charging, the electrolyte released by the liquid storage material 400 can directly infiltrate the surface of the negative electrode sheet 300, providing a carrier and channel for lithium ions to embed into the negative electrode sheet 300, reducing the problem of lithium plating on the surface of the negative electrode sheet 300, improving the battery's charge and discharge performance, and extending the battery's service life.

[0073] like Figure 2 As shown, in some embodiments, the liquid storage material 400 is disposed in the second negative electrode active material layer 330 and / or in the first negative electrode active material layer 320 .

[0074] The liquid storage material 400 may be provided solely in the first negative electrode active material layer 320 , solely in the second negative electrode active material layer 330 , or both in the first negative electrode active material layer 320 and the second negative electrode active material layer 330 .

[0075] The liquid storage material 400 can be within the second negative electrode active material layer 330 or the first negative electrode active material layer 320, so that lithium ions can be directly embedded in the negative electrode plate 300 through the electrolyte in the liquid storage material 400. The liquid storage material 400 can also release the electrolyte when squeezed and infiltrate the first negative electrode active material or the second negative electrode active material around the liquid storage material 400, so that the first negative electrode active material layer 320 and the second negative electrode active material layer 330 have sufficient lithium ion channels for lithium ion embedding.

[0076] There are two methods for disposing the liquid storage material 400 in the second negative electrode active material layer 330 and / or the first negative electrode active material layer 320:

[0077] The first method is to mix the liquid storage material 400 in the first negative electrode active material or the second negative electrode active material, and spray the liquid storage material 400 onto the negative electrode current collector 310 together with the first negative electrode active material or the second negative electrode active material, thereby forming the above structure.

[0078] The second method is that when the liquid storage material 400 is gel or silica gel, after the first negative electrode active material layer 320 and the second negative electrode active material layer 330 are formed on the negative electrode current collector 310, a hole is punched on the negative electrode plate 300, and the hole is formed on the second negative electrode active material layer 330, or the hole passes through the second negative electrode active material layer 330 and is partially located on the first negative electrode active material layer 320. Then the negative electrode tab is soaked in high-temperature liquid gel or silica gel and then taken out. After cooling, gel or silica gel particles, i.e., the liquid storage material 400, are left in the hole.

[0079] The liquid storage material 400 formed by the second method mentioned above is a rod-shaped particle, and since the punching process is to punch along the thickness direction of the negative electrode sheet 300, the maximum size of the liquid storage material 400 in the thickness direction of the negative electrode sheet 300 is greater than the maximum size of the liquid storage material 400 in other directions, and other directions refer to directions other than the thickness direction of the negative electrode sheet 300.

[0080] It can be understood that the shape of the rod-shaped particles is basically similar to that of the holes. Therefore, the specific size and shape of the rod-shaped particles depend to a certain extent on the shape and depth of the holes, and are also affected by the pouring conditions and cooling conditions of the liquid raw materials. Therefore, the rod-shaped particles are only the general shape of the liquid storage material 400 and do not strictly meet the shape requirements.

[0081] The liquid storage material 400 holds a relatively large amount of electrolyte, allowing lithium ions to move quickly through the liquid storage material 400. The rod-shaped particles of the liquid storage material 400 facilitate the entry of lithium ions into the first negative electrode active material or the second negative electrode active material along the length of the liquid storage material 400. Because the maximum dimension of the liquid storage material 400 in the thickness direction of the negative electrode sheet 300 is greater than the maximum dimension of the liquid storage material 400 in other directions, the length direction of the liquid storage material 400 is substantially consistent with the thickness direction of the negative electrode sheet 300. As a result, lithium ions can penetrate deeper into the negative electrode sheet 300 along the length direction of the liquid storage material 400, which is beneficial for improving the charge and discharge performance of the battery.

[0082] Figure 4 This is a schematic diagram of the structure of the second negative electrode sheet provided in the embodiment of the present application, as shown in FIG. Figure 4 As shown, in some embodiments, the liquid storage material 400 is disposed between the second negative electrode active material layer 330 and the first negative electrode active material layer 320 .

[0083] A specific implementation method may be that after the first negative electrode active material is coated, a layer of liquid storage material 400 is coated on the surface of the first negative electrode active material layer 320, and the liquid storage material layer can be formed after the liquid storage material 400 is cooled and dried, or a layer of solid liquid storage material particles is sprayed on the surface of the first negative electrode active material layer 320, and then the second negative electrode active material is coated. After the negative electrode plate 300 is installed in the battery shell and the electrolyte is injected into the shell, the solid liquid storage material particles absorb the electrolyte and expand to form a liquid storage material layer, and retain the electrolyte in the liquid storage material 400.

[0084] The liquid storage material 400 is arranged between the second negative electrode active material layer 330 and the first negative electrode active material layer 320, so that the liquid storage material 400 is conducive to the passage of lithium ions, thereby facilitating the lithium ions to enter the first negative electrode active material layer 320 from the second negative electrode active material layer 330, and facilitating the increase of the embedding depth of lithium ions in the negative electrode sheet 300.

[0085] The liquid storage material 400 is arranged between the second negative electrode active material layer 330 and the first negative electrode active material layer 320, so that when the liquid storage material 400 is squeezed, the electrolyte in the liquid storage material 400 can directly infiltrate the first negative electrode active material layer 320 and the second negative electrode active material layer 330, so that the first negative electrode active material layer 320 and the second negative electrode active material layer 330 remain in a wet state for a long time, which is further beneficial to improving the charge and discharge performance of the battery and extending the service life of the battery.

[0086] Figure 5 This is a schematic diagram of the structure of the third negative electrode sheet provided in the embodiment of the present application, as shown in FIG. Figure 5 As shown, in some embodiments, the liquid storage material 400 is disposed between the first negative electrode active material layer 320 and the negative electrode current collector 310 .

[0087] A specific implementation method may be that before the first negative electrode active material is coated on the negative electrode current collector 310, a layer of liquid storage material 400 is first coated on the surface of the negative electrode current collector 310, and a liquid storage material layer can be formed after the liquid storage material 400 is cooled and dried, or a layer of solid liquid storage material particles is sprayed on the surface of the negative electrode current collector 310, and then the first negative electrode active material and the second negative electrode active material are coated. After the negative electrode plate 300 is installed in the battery casing and the electrolyte is injected into the casing, the solid liquid storage material particles absorb the electrolyte and expand to form a liquid storage material layer, and retain the electrolyte in the liquid storage material 400.

[0088] The area between the first negative electrode active material layer 320 and the negative electrode current collector 310 is the farthest from the surface of the negative electrode plate 300. It is not easily wetted by the electrolyte. By setting the liquid storage material 400 here, the electrolyte retention amount here can be increased, so that the first negative electrode active material layer 320 can remain wetted by the electrolyte for a long time, which is conducive to the embedding of lithium ions into the first negative electrode active material layer 320, thereby improving the charge and discharge performance of the battery and extending the battery life.

[0089] Figure 6 This is a schematic diagram of the structure of the fourth negative electrode sheet provided in the embodiment of the present application, as shown in FIG. Figure 6 As shown, in some embodiments, the liquid storage material 400 is attached to a side of the second negative active material layer 330 away from the first negative active material layer 320 .

[0090] A specific implementation method may be that after the first negative electrode active material and the second negative electrode active material are sequentially coated on the surface of the negative electrode current collector 310, a layer of liquid storage material 400 is coated on the surface of the second negative electrode active material layer 330, and the liquid storage material layer can be formed after the liquid storage material 400 is cooled and dried, or a layer of solid liquid storage material particles is sprayed on the surface of the second negative electrode active material layer 330, and after the negative electrode plate 300 is installed in the battery shell and the electrolyte is injected into the shell, the solid liquid storage material particles absorb the electrolyte and expand to form a liquid storage material layer, and retain the electrolyte in the liquid storage material 400.

[0091] The liquid storage material 400 is attached to the surface of the second negative electrode active material layer 330 on the side away from the first negative electrode active material layer 320. It can be assembled with the negative electrode plate 300, the positive electrode plate 100, and the separator 200 to form an electrode assembly, eliminating the need for a separate assembly step for the liquid storage material 400. In addition, when the battery expands during charging, the electrolyte released by the liquid storage material 400 can directly infiltrate the surface of the negative electrode plate 300, providing a carrier and channel for lithium ions to embed into the negative electrode plate 300, reducing the problem of lithium plating on the surface of the negative electrode plate 300, improving the battery's charge and discharge performance, and extending the battery's service life.

[0092] Although the structures of the above electrode assemblies are different, they all contain a liquid storage material 400. The liquid storage material 400 can release electrolyte during the use of the battery, thereby replenishing the electrolyte in the shell of the battery cell and slowing down the consumption rate of the electrolyte. This allows the battery using the above electrode assembly to maintain good charge and discharge performance for a long time, thereby extending the service life of the battery.

[0093] The battery provided in the embodiments of the present application includes the electrode assembly in any of the above embodiments.

[0094] The electrical equipment provided in the embodiments of the present application includes the battery in the above embodiments.

[0095] The above-mentioned batteries and electrical equipment all include the above-mentioned electrode assemblies. Therefore, the batteries and electrical equipment have the various structures and beneficial effects of the above-mentioned electrode assemblies. Please refer to the structural descriptions and beneficial effects in the various embodiments of the electrode assemblies for details. The embodiments of this application will not repeat the relevant structures of the batteries and electrical equipment.

[0096] In summary, the present embodiment of the present invention provides a first negative electrode active material layer 320 and a second negative electrode active material layer 330 of different particle sizes on the negative electrode current collector 310. The second negative electrode active material layer 330, which has a smaller average particle size, is disposed on the side of the first negative electrode active material layer 320, which has a larger average particle size, away from the negative electrode current collector 310. This results in the second negative electrode active material layer 330 having higher kinetics than the first negative electrode active material layer 320. The second negative electrode active material layer 330 can accommodate a larger amount of electrolyte, making it easier for lithium ions to intercalate into the negative electrode sheet 300. By disposing the liquid storage material 400 between the separator 200 and the negative electrode current collector 310, when the battery expands during charging, the separator 200 and the negative electrode current collector 310 squeeze the liquid storage material 400, causing it to release a certain amount of electrolyte, thereby replenishing the electrolyte within the battery cell housing and slowing down the rate of electrolyte consumption. This allows the battery using this electrode assembly to maintain good charge and discharge performance over a long period of time, extending the battery's service life.

[0097] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of this application and to form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0098] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrode assembly, characterized in that: It includes a positive electrode sheet, a separator, a negative electrode sheet and a flexible liquid storage material that are stacked; The diaphragm is provided between the positive electrode sheet and the negative electrode sheet; The negative electrode sheet includes a negative electrode current collector, a first negative electrode active material layer, and a second negative electrode active material layer, wherein the second negative electrode active material layer is provided on a side of the first negative electrode active material layer away from the negative electrode current collector, and the average particle size of the material of the second negative electrode active material layer is smaller than the average particle size of the material of the first negative electrode active material layer; The liquid storage material is arranged between the separator and the negative electrode current collector.

2. The electrode assembly according to claim 1, wherein The liquid storage material is attached to a surface of the separator close to the negative electrode plate.

3. The electrode assembly according to claim 1, wherein The liquid storage material is provided in the second negative electrode active material layer and / or in the first negative electrode active material layer.

4. The electrode assembly according to claim 3, characterized in that The liquid storage material is a rod-shaped particle, and the maximum size of the liquid storage material in the thickness direction of the negative electrode sheet is greater than the maximum size of the liquid storage material in other directions, and the other directions are directions other than the thickness direction of the negative electrode sheet.

5. The electrode assembly according to claim 1, wherein: The liquid storage material is provided between the second negative electrode active material layer and the first negative electrode active material layer.

6. The electrode assembly according to claim 1, wherein: The liquid storage material is disposed between the first negative electrode active material layer and the negative electrode current collector.

7. The electrode assembly according to claim 1, wherein: The liquid storage material is attached to a side of the second negative electrode active material layer away from the first negative electrode active material layer.

8. The electrode assembly according to any one of claims 1 to 7, characterized in that: The liquid storage material is porous gel or silica gel.

9. A battery, characterized in that: The electrode assembly comprises the electrode assembly according to any one of claims 1 to 8.

10. An electrical device, characterized in that: A battery comprising the battery of claim 9.

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