Battery cell and manufacturing method therefor, battery apparatus and electrical apparatus

Abstract

A battery cell and a manufacturing method therefor, a battery apparatus, and an electrical apparatus. The battery cell comprises an electrode assembly; separators each comprise a separator base layer and an adhesive layer, and each separator base layer comprises a first main body region and a first edge region; each adhesive layer is located on the surface of the side of a first edge region facing a negative electrode sheet, and the adhesive layers of two adjacent separators located on two sides of the negative electrode sheet are bonded to each other and wrap the negative electrode sheet therein; the negative electrode sheet comprises a negative electrode base layer, the negative electrode base layer comprising a second main body region and a second edge region; the negative electrode sheet further comprises a lithium-philic layer and / or an insulating layer, the lithium-philic layer being located on at least part of the surface of the second main body region, and the insulating layer being located on at least part of the surface of the second edge region. The battery apparatus can reduce the escape of pulverized substances from the edge of the negative electrode, and can enable the battery cell to have good cycle performance.

Description

Battery cells and their preparation methods, battery devices and electrical devices

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411545289.5, filed on October 31, 2024, entitled “Battery Cell and Method for Preparation Thereof, Battery Device and Power Consumption Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a battery cell and its preparation method, a battery device, and an electrical device. Background Technology

[0004] Battery cells using lithium metal as the negative electrode material have a much higher energy density than lithium-ion battery cells, which is crucial for applications such as long-range electric vehicles, drones, and electric aircraft. However, the poor cycle capacity of these battery cells has hindered their commercialization. Summary of the Invention

[0005] This disclosure provides a battery cell and its preparation method, battery device and power supply device, which can reduce the release of pulverized material from the edge of the negative electrode and enable the battery cell to have good cycle performance.

[0006] In a first aspect, this disclosure provides a battery cell, the battery cell including an electrode assembly, the electrode assembly including at least one positive electrode, at least two separators and at least one negative electrode, and adjacent positive and negative electrodes are separated by the separators.

[0007] The separator includes a separator substrate layer and an adhesive layer. The separator substrate layer includes a first main region and a first edge region. The first main region is the region of the separator substrate layer that faces the negative electrode sheet. The first edge region is the region of the separator substrate layer that does not face the negative electrode sheet. The adhesive layer is located on the surface of the first edge region facing the negative electrode sheet. The adhesive layers of two adjacent separator layers on both sides of the negative electrode sheet are bonded to each other and encapsulate the negative electrode sheet therein.

[0008] The negative electrode sheet includes a negative electrode substrate layer, which includes a second main region and a second edge region. The second main region is the region of the negative electrode substrate layer that is directly opposite the positive electrode sheet, and the second edge region is the region of the negative electrode substrate layer that is not directly opposite the positive electrode sheet.

[0009] The negative electrode further includes a lithiophilic layer located on at least a portion of the surface of the second main body region; or, the negative electrode further includes an insulating layer located on at least a portion of the surface of the second edge region; or, the negative electrode further includes a lithiophilic layer and an insulating layer, the lithiophilic layer located on at least a portion of the surface of the second main body region, and the insulating layer located on at least a portion of the surface of the second edge region.

[0010] The negative electrode sheet disclosed herein may have a lithiophilic layer disposed on at least a portion of the surface of the second main region of the negative electrode substrate, while the second edge region of the negative electrode substrate does not have a lithiophilic layer. During lithium deposition, the lithiophilic layer preferentially reacts with the deposited lithium metal to form an alloy, thereby reducing the lithium metal nucleation energy barrier and decreasing dendrite formation. During lithium deposition, the deposited lithium metal preferentially nucleates at the lithiophilic layer, thus reducing the likelihood of lithium dendrite formation and lithium pulverization at the second edge region of the negative electrode substrate. Furthermore, the alloy formed by the reaction of the lithiophilic layer and lithium itself has a high lithium conductivity, which also facilitates rapid lithium ion diffusion.

[0011] The negative electrode sheet disclosed herein may also have an insulating layer disposed on at least a portion of the surface of the second edge region of the negative electrode substrate layer, thereby reducing the possibility that lithium ions will gain electrons in the second edge region of the negative electrode substrate layer and be deposited as lithium metal, thereby reducing the possibility that lithium metal will form lithium dendrites and pulverized lithium in the second edge region of the negative electrode substrate layer.

[0012] The negative electrode sheet disclosed herein may also have a lithiophilic layer disposed on at least a portion of the surface of the second main body region of the negative electrode substrate layer, and an insulating layer disposed on at least a portion of the surface of the second edge region of the negative electrode substrate layer.

[0013] In the electrode assembly disclosed herein, two adjacent separator layers located on both sides of the negative electrode sheet are bonded together by an adhesive layer and the negative electrode sheet is completely wrapped within it to form a bag-like microstructure. This can reduce the amount of powdery substances formed during repeated charging and discharging of the battery cell, such as powdered lithium and broken solid electrolyte interface film powder, which are released from the edge of the negative electrode. This can reduce the risk of short circuit within the battery cell and also reduce the phenomenon of overcharging of the battery cell.

[0014] Therefore, the battery cells provided in this disclosure have good cycle performance.

[0015] In some embodiments, the adhesive layer is also located on at least a portion of the surface of the first body region facing the negative electrode sheet, and the adhesive layer is bonded to the negative electrode sheet.

[0016] At this point, the adhesive layer can tightly connect the separator to the negative electrode sheet, thereby further reducing dendrite growth, reducing the generation of lithium pulverization, and fixing the pulverized material to the surface of the negative electrode sheet, reducing the pulverized material from the edge of the negative electrode.

[0017] In some embodiments, the thickness of the adhesive layer is 0.5 μm-10 μm.

[0018] With the thickness of the adhesive layer within the above range, it is possible to bond two adjacent separator layers together and encapsulate the negative electrode sheet to form a bag-like microstructure without introducing significant kinetic polarization problems into the battery cell, thereby enabling the battery cell to have high capacity performance characteristics.

[0019] In some embodiments, the adhesive layer comprises one or more of a first polymer and a polymeric solid electrolyte material.

[0020] In some embodiments, the first polymer includes one or more of acrylate polymers, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyethylene glycol, styrene-butadiene rubber, and their respective derivatives.

[0021] In some embodiments, the polymer solid electrolyte material is formed by complexing a polymer matrix material with a lithium salt, wherein the polymer matrix material includes one or more of polyethylene oxide, polypropylene oxide, polycarbonate, polyacrylonitrile, polysiloxane, polyvinylidene fluoride, acrylate polymers, and their respective derivatives.

[0022] In some embodiments, the lithiophilic layer comprises one or more of a lithiophilic metal, a lithiophilic alloy, and a lithiophilic oxide.

[0023] In some embodiments, the thickness of the lithiophilic layer is 20 nm to 1000 nm.

[0024] In some embodiments, the lithiophilic layer comprises one or more of the following: elemental gold, silver, indium, bismuth, zinc, tin, gallium, and germanium, alloys, and oxides.

[0025] In some embodiments, the thickness of the insulating layer is 0.2 μm-20 μm.

[0026] In some embodiments, the insulating layer includes an insulating filler.

[0027] In some embodiments, the insulating filler includes one or more of ceramic materials, silicate materials, minerals, and glass.

[0028] In some embodiments, the isolation membrane substrate layer comprises a porous base membrane.

[0029] In some embodiments, the isolation membrane substrate layer includes a porous base membrane and a heat-resistant coating located on at least one side of the porous base membrane, wherein the heat-resistant coating includes one or more of organic particles, inorganic particles, and organic-inorganic composite particles.

[0030] In some embodiments, the negative electrode substrate layer includes a negative electrode current collector, which is a metal foil or a composite current collector. The composite current collector includes a polymer material base layer and a metal material layer formed on at least one side of the polymer material base layer.

[0031] In some embodiments, the negative electrode substrate layer includes a negative electrode current collector and a lithium-based metal layer located on at least one side of the negative electrode current collector. The negative electrode current collector is a metal foil or a composite current collector. The composite current collector includes a polymer material base layer and a metal material layer formed on at least one side of the polymer material base layer.

[0032] In some embodiments, the electrode assembly is a stacked electrode assembly.

[0033] In some embodiments, the electrode assembly is a wound electrode assembly, which is formed by sequentially stacking and winding a positive electrode sheet, a separator, a negative electrode sheet, and a separator.

[0034] Secondly, this disclosure provides a method for preparing a battery cell, comprising the following steps: assembling at least one positive electrode sheet, at least two separator films, and at least one negative electrode sheet to obtain an electrode assembly, wherein adjacent positive and negative electrode sheets are separated by the separator film; the separator film includes a separator film substrate layer and an adhesive layer, the separator film substrate layer includes a first main region and a first edge region, the first main region being the region of the separator film substrate layer directly opposite the negative electrode sheet, the first edge region being the region of the separator film substrate layer not directly opposite the negative electrode sheet, and the adhesive layer being located on the surface of the first edge region facing the negative electrode sheet; the negative electrode sheet includes a negative electrode substrate layer, the negative electrode substrate layer including a second main region and a second edge region, the second main region being the... The negative electrode substrate layer is located in the region directly opposite the positive electrode sheet, and the second edge region is located in the region where the negative electrode substrate layer is not directly opposite the positive electrode sheet; the negative electrode sheet further includes a lithiophilic layer located on at least a portion of the surface of the second main body region; or, the negative electrode sheet further includes an insulating layer located on at least a portion of the surface of the second edge region; or, the negative electrode sheet further includes a lithiophilic layer and an insulating layer, the lithiophilic layer located on at least a portion of the surface of the second main body region, and the insulating layer located on at least a portion of the surface of the second edge region; the obtained electrode assembly is placed in an outer packaging, and the adhesive layers of two adjacent separators located on both sides of the negative electrode sheet are bonded together by hot pressing and the negative electrode sheet is wrapped therein, and electrolyte is injected to obtain a battery cell.

[0035] Thirdly, this disclosure provides a battery device comprising a plurality of battery cells as described in the first aspect.

[0036] Fourthly, this disclosure provides an electrical device that includes a battery cell as described in the first aspect or a battery device as described in the third aspect. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0038] Figure 1 shows a schematic diagram of a battery cell provided in some embodiments of this disclosure.

[0039] Figure 2 shows a schematic diagram of an electrical device provided in some embodiments of this disclosure.

[0040] Figure 3 shows an exploded schematic diagram of the isolation membrane provided in some embodiments of this disclosure.

[0041] Figure 4 shows an exploded schematic diagram of the isolation membrane provided in some other embodiments of this disclosure.

[0042] Figure 5 shows an exploded schematic diagram of the isolation membrane provided in some embodiments of the present disclosure.

[0043] Figure 6 shows an exploded schematic diagram of the negative electrode sheet provided in some embodiments of this disclosure.

[0044] Figure 7 shows an exploded schematic diagram of the negative electrode sheet provided in some other embodiments of this disclosure.

[0045] Figure 8 shows an exploded schematic diagram of the negative electrode sheet provided in some embodiments of this disclosure.

[0046] Figure 9 shows an exploded schematic diagram of an electrode assembly provided in some embodiments of this disclosure.

[0047] Figure 10 shows an exploded schematic diagram of an electrode assembly provided in some other embodiments of this disclosure.

[0048] Figure 11 shows an exploded schematic diagram of an electrode assembly provided in some other embodiments of the present disclosure.

[0049] Figure 12 shows an exploded schematic diagram of an electrode assembly provided in some other embodiments of the present disclosure.

[0050] Figure 13 shows an exploded schematic diagram of an electrode assembly provided in some other embodiments of the present disclosure.

[0051] The accompanying drawings are not necessarily drawn to scale.

[0052] The reference numerals in the attached figures are explained as follows: 10, separator; 11, separator substrate layer; 111, first main body region; 112, first edge region; 12, adhesive layer; 20, negative electrode sheet; 21, negative electrode substrate layer; 211, second main body region; 212, second edge region; 22, lithiophilic layer; 23, insulating layer; 30, positive electrode sheet. Detailed Implementation

[0053] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the battery cell, its preparation method, battery device, and power-consuming device of this disclosure. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter of the claims.

[0054] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0055] Unless otherwise specified, all embodiments and optional embodiments of this disclosure may be combined with each other to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0056] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0057] Unless otherwise specified, all steps in this disclosure may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0058] Unless otherwise specified, in this disclosure, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0059] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0060] In the description of the embodiments of this disclosure, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0061] Unless otherwise stated, the test temperature for all parameters mentioned in this disclosure is 25°C.

[0062] The battery cells mentioned in the embodiments of this disclosure are capable of charging and discharging independently. The battery cells may be cylindrical, cuboid, or other shapes, and this disclosure does not limit this. Figure 1 shows an example of a cuboid battery cell.

[0063] The battery apparatus mentioned in the embodiments of this disclosure may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0064] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0065] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0066] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0067] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0068] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0069] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0070] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0071] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0072] The technical solutions described in this disclosure are applicable to various electrical devices that use battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. Battery cells and battery devices are used to store or provide electrical energy.

[0073] Figure 2 is a schematic diagram of an example electrical device. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0074] The battery cells provided in the embodiments of this disclosure can be lithium metal battery cells, negative electrode-free lithium metal battery cells, etc.

[0075] A negative electrode-free lithium metal battery cell typically refers to a battery cell in which no negative electrode active material layer is actively formed on the negative electrode side during the manufacturing process. For example, during the manufacturing process, a negative electrode active material layer formed of carbonaceous materials is not applied or deposited at the negative electrode, and a lithium-based metal layer is not actively formed on the negative electrode side. During the first charge, lithium ions gain electrons on the negative electrode side and deposit on the surface of the negative electrode current collector to form lithium metal. During discharge, the lithium metal can be converted back into lithium ions and return to the positive electrode, achieving cyclic charging and discharging.

[0076] Lithium metal possesses a high theoretical specific capacity (3860 mAh / g) and a low reduction potential (-3.04 V vs. SHE), making it a highly promising anode material. Currently, the dendrite growth problem in battery cells using lithium metal as the anode material and the resulting short circuit issues are the main challenges to its commercialization. Dendrite growth can puncture the separator, leading to internal short circuits between the positive and negative electrodes, affecting the cycle performance of the battery cell. After the dendrites break, they gradually evolve into lithium powder. Additionally, the anode also contains fragmented solid electrolyte interphase (SEI) film powder. These powdered materials, such as lithium powder and fragmented SEI film powder, can drift away from the anode edge with the electrolyte, potentially causing internal short circuits between the positive and negative electrodes and overcharging of the battery cell, resulting in a significant increase in charging capacity compared to discharging capacity during charging. This is mainly because the pulverized lithium from the negative electrode drifts to the positive electrode and attaches with the positive electrode active material. This causes the lithium-poor positive electrode active material formed during the charging process of the battery cell to be directly lithiated into a lithium-rich positive electrode active material. This will cause the battery cell to take longer to charge, thus affecting the cycle performance of the battery cell.

[0077] Based on this, the present disclosure provides a battery cell that can reduce the amount of pulverized material released from the edge of the negative electrode and enable the battery cell to have good cycle performance.

[0078] The battery cell disclosed herein includes an electrode assembly.

[0079] As shown in Figures 3 to 13, the electrode assembly includes at least one positive electrode 30, at least two separators 10, and at least one negative electrode 20, and adjacent positive electrode 30 and negative electrode 20 are separated by separators 10.

[0080] The separator 10 includes a separator substrate layer 11 and an adhesive layer 12. The separator substrate layer 11 includes a first main region 111 and a first edge region 112. The first main region 111 is the region where the separator substrate layer 11 faces the negative electrode 20. The first edge region 112 is the region where the separator substrate layer 11 does not face the negative electrode 20. The adhesive layer 12 is located on the surface of the first edge region 112 facing the negative electrode 20. The adhesive layers 12 of two adjacent separator layers 10 located on both sides of the negative electrode 20 are bonded to each other and wrap the negative electrode 20 therein.

[0081] The negative electrode 20 includes a negative electrode substrate layer 21, which includes a second main region 211 and a second edge region 212. The second main region 211 is the region of the negative electrode substrate layer 21 that faces the positive electrode 30, and the second edge region 212 is the region of the negative electrode substrate layer 21 that does not face the positive electrode 30. The negative electrode 20 also includes a lithiophilic layer 22, which is located on at least a portion of the surface of the second main region 211; or, the negative electrode 20 also includes an insulating layer 23, which is located on at least a portion of the surface of the second edge region 212; or, the negative electrode 20 also includes a lithiophilic layer 22 and an insulating layer 23, with the lithiophilic layer 22 located on at least a portion of the surface of the second main region 211 and the insulating layer 23 located on at least a portion of the surface of the second edge region 212.

[0082] The negative electrode sheet disclosed herein may have a lithiophilic layer disposed on at least a portion of the surface of the second main region of the negative electrode substrate, while the second edge region of the negative electrode substrate does not have a lithiophilic layer. During lithium deposition, the lithiophilic layer preferentially reacts with the deposited lithium metal to form an alloy, thereby reducing the lithium metal nucleation energy barrier and decreasing dendrite formation. During lithium deposition, the deposited lithium metal preferentially nucleates at the lithiophilic layer, thus reducing the likelihood of lithium dendrite formation and lithium pulverization at the second edge region of the negative electrode substrate. Furthermore, the alloy formed by the reaction of the lithiophilic layer and lithium itself has a high lithium conductivity, which also facilitates rapid lithium ion diffusion.

[0083] The negative electrode sheet disclosed herein may also have an insulating layer disposed on at least a portion of the surface of the second edge region of the negative electrode substrate layer, thereby reducing the possibility that lithium ions will gain electrons in the second edge region of the negative electrode substrate layer and be deposited as lithium metal, thereby reducing the possibility that lithium metal will form lithium dendrites and pulverized lithium in the second edge region of the negative electrode substrate layer.

[0084] The negative electrode sheet disclosed herein may also have a lithiophilic layer disposed on at least a portion of the surface of the second main body region of the negative electrode substrate layer, and an insulating layer disposed on at least a portion of the surface of the second edge region of the negative electrode substrate layer.

[0085] In the electrode assembly disclosed herein, two adjacent separator layers located on both sides of the negative electrode sheet are bonded together by an adhesive layer and the negative electrode sheet is completely wrapped within it to form a bag-like microstructure. This can reduce the amount of powdery substances formed during repeated charging and discharging of the battery cell, such as powdered lithium and broken solid electrolyte interface film powder, which are released from the edge of the negative electrode. This can reduce the risk of short circuit within the battery cell and also reduce the phenomenon of overcharging of the battery cell.

[0086] Therefore, the battery cells provided in this disclosure have good cycle performance.

[0087] In Figures 3 to 13, directions X, Y, and Z are all perpendicular to each other. Direction Z represents the thickness direction.

[0088] Figures 9 to 13 show exploded schematic diagrams of the electrode assembly. The adhesive layers 12 of the two adjacent separators 10 on both sides of the negative electrode 20 are not bonded to each other. It should be noted that in the final battery cell, the adhesive layers 12 of the two adjacent separators 10 on both sides of the negative electrode 20 are bonded to each other and wrap the negative electrode 20 therein.

[0089] In some embodiments, the electrode assembly may be a stacked electrode assembly.

[0090] In the stacked electrode assembly, the number of positive electrode plates can be the same as the number of negative electrode plates, or the number of positive electrode plates can be one more than the number of negative electrode plates, or the number of negative electrode plates can be one more than the number of positive electrode plates. This disclosure does not limit the specific number of positive electrode plates. As shown in Figures 9 to 13, the number of positive electrode plates 30 is one more than the number of negative electrode plates 20.

[0091] In some embodiments, the electrode assembly can be a wound electrode assembly, which can be formed by sequentially stacking a positive electrode, a separator, a negative electrode, and a separator and then winding them together.

[0092] In some embodiments, the battery cell includes an outer packaging and an electrolyte, the outer packaging being used to house the electrode assembly and the electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0093] The lithiophilic layer 22 can be located on at least a portion of the surface of the second main body region 211. This means that the second main body region 211 of the negative electrode substrate layer 21 has two surfaces opposite each other in its thickness direction. The lithiophilic layer 22 can be disposed on a portion or all of the two opposite surfaces of the second main body region 211, or it can be disposed on a portion or all of each of the two opposite surfaces of the second main body region 211. In some embodiments, as shown in Figures 6 and 8, the lithiophilic layer 22 is located on all of the two surfaces of the second main body region 211 of the negative electrode substrate layer 21.

[0094] The insulating layer 23 may be located on at least a portion of the surface of the second edge region 212, meaning that the second edge region 212 of the negative electrode substrate layer 21 has two surfaces opposite to each other in its thickness direction. The insulating layer 23 may be disposed on a portion or all of the two opposite surfaces of the second edge region 212, or the insulating layer 23 may be disposed on a portion or all of the respective positions of the two opposite surfaces of the second edge region 212.

[0095] In some embodiments, as shown in Figures 7 and 8, the insulating layer 23 is located on all positions of both surfaces of the second edge region 212 of the negative electrode substrate layer 21.

[0096] In some embodiments, the adhesive layer 12 may also be located on at least a portion of the surface of the first body region 111 facing the negative electrode 20, and the adhesive layer 12 is bonded to the negative electrode 20.

[0097] At this point, the adhesive layer can tightly connect the separator to the negative electrode sheet, thereby further reducing dendrite growth, reducing the generation of lithium pulverization, and fixing the pulverized material to the surface of the negative electrode sheet, reducing the pulverized material from the edge of the negative electrode.

[0098] As shown in Figure 4, the adhesive layer 12 can be located on the entire surface of the separator substrate layer 11 facing the negative electrode 20.

[0099] As shown in Figure 5, the adhesive layer 12 can be located on the surface of the first edge region 112 facing the negative electrode 20 and on a portion of the surface of the separator substrate layer 11 facing the negative electrode 20.

[0100] In some embodiments, the thickness of the adhesive layer can be 0.5μm-10μm, for example, it can be 0.5μm, 0.8μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any range of the above values.

[0101] With the thickness of the adhesive layer within the above range, it is possible to bond two adjacent separator layers together and encapsulate the negative electrode sheet to form a bag-like microstructure without introducing significant kinetic polarization problems into the battery cell, thereby enabling the battery cell to have high capacity performance characteristics.

[0102] Optionally, the thickness of the adhesive layer can be 0.5μm-10μm, 0.5μm-8μm, 0.5μm-6μm, 0.5μm-5μm, 0.5μm-4μm, 0.8μm-10μm, 0.8μm-8μm, 0.8μm-6μm, 0.8μm-5μm, 0.8μm-4μm, 1μm-10μm, 1μm-8μm, 1μm-6μm, 1μm-5μm, or 1μm-4μm.

[0103] In some embodiments, the adhesive layer may include one or more of a first polymer and a polymer solid electrolyte material.

[0104] Optionally, the adhesive layer may include a first polymer.

[0105] In some embodiments, the first polymer may include one or more of acrylate polymers, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyethylene glycol, styrene-butadiene rubber, and their respective derivatives. A derivative is a product derived from the substitution of hydrogen atoms or groups of atoms in the polymer by other atoms or groups of atoms.

[0106] Optionally, the first polymer may include one or more of acrylate polymers, polyurethanes, and their respective derivatives. Both polymers are rich in hydrogen bonds and also have good adhesive properties.

[0107] In this disclosure, acrylate polymers refer to polymers comprising acrylate monomer units and / or methacrylate monomer units. They can be homopolymers formed from one acrylate monomer or one methacrylate monomer, or copolymers formed from two or more acrylate monomers, two or more methacrylate monomers, or at least one acrylate monomer and at least one methacrylate monomer.

[0108] Optionally, the acrylate monomer may include one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, and lauryl acrylate.

[0109] Optionally, the methacrylate monomer may include one or more of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, and lauryl methacrylate.

[0110] In some embodiments, the weight-average molecular weight of the first polymer can be 6,000-2,000,000, and optionally 50,000-1,000,000.

[0111] The weight-average molecular weight of the first polymer can be tested by gel permeation chromatography.

[0112] In some embodiments, polymer solid electrolyte materials can be formed by complexing a polymer matrix material with a lithium salt.

[0113] Optionally, the polymer matrix material may include one or more of polyethylene oxide, polypropylene oxide, polycarbonate, polyacrylonitrile, polysiloxane, polyvinylidene fluoride, polyurethane, acrylate polymers, and their respective derivatives. Derivatives refer to products derived from the substitution of hydrogen atoms or groups of atoms in the polymer by other atoms or groups of atoms.

[0114] Optionally, the lithium salt may include one or more of lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(fluorosulfonyl)imide (LiFSI).

[0115] In some embodiments, the separator substrate layer may include a porous base membrane.

[0116] The porous base membrane can be made of one or more of the following materials, including but not limited to glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and polyimide. The porous base membrane can be a single-layer film or a multi-layer composite film. When the porous base membrane is a multi-layer composite film, the materials of each layer may be the same or different.

[0117] In some embodiments, the isolation membrane substrate layer may include a porous base membrane and a heat-resistant coating located on at least one side of the porous base membrane.

[0118] Optionally, the heat-resistant coating may include one or more of organic particles, inorganic particles, and organic-inorganic composite particles.

[0119] In some embodiments, the lithiophilic layer may include one or more of a lithiophilic metal, a lithiophilic alloy, and a lithiophilic oxide.

[0120] Optionally, the lithiophilic layer may include one or more of the following: gold (Au), silver (Ag), indium (In), bismuth (Bi), zinc (Zn), tin (Sn), gallium (Ga), and germanium (Ge), in its elemental form, alloy, or oxide.

[0121] Alternatively, the lithiophilic layer may include one or more of the following: gold (Au), silver (Ag), indium (In), bismuth (Bi), zinc (Zn), tin (Sn), gallium (Ga), and germanium (Ge).

[0122] Further optionally, the lithiophilic layer may include one or more of bismuth (Bi) or bismuth alloys.

[0123] In some embodiments, the thickness of the lithiophilic layer can be 20nm-1000nm, for example, it can be 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, or any range of the above values.

[0124] Optionally, the thickness of the lithiophilic layer can be 20nm-500nm, 20nm-400nm, 20nm-300nm, 20nm-200nm, 20nm-150nm, 20nm-120nm, 30nm-500nm, 30nm-400nm, 30nm-300nm, 30nm-200nm, 30nm-150nm, 30nm-120nm, 50nm-500nm, 50nm-400nm, 50nm-300nm, 50nm-200nm, 50nm-150nm, or 50nm-120nm.

[0125] Alternatively, the lithiophilic layer can be formed by an evaporation process or a sputtering process.

[0126] In some embodiments, the thickness of the insulating layer can be 0.2μm-20μm, for example, it can be 0.2μm, 0.5μm, 0.8μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, or any range of the above values.

[0127] Optionally, the thickness of the insulating layer can be 0.2μm-16μm, 0.2μm-14μm, 0.2μm-12μm, 0.2μm-10μm, 0.2μm-8μm, 0.2μm-6μm, 0.2μm-5μm, 0.5μm-16μm, 0.5μm-14μm, 0.5μm-12μm, 0.5μm-10μm, 0.5μm-8μm, 0.5μm- 6μm, 0.5μm-5μm, 0.8μm-16μm, 0.8μm-14μm, 0.8μm-12μm, 0.8μm-10μm, 0.8μm-8μm, 0.8μm- 6μm, 0.8μm-5μm, 1μm-16μm, 1μm-14μm, 1μm-12μm, 1μm-10μm, 1μm-8μm, 1μm-6μm, 1μm-5μm.

[0128] In some embodiments, the insulating layer may include insulating filler.

[0129] Optionally, the insulating filler may include one or more of ceramic materials, silicate materials, minerals, and glass. More preferably, the insulating filler may include one or more of the following: alumina (Al2O3), zinc oxide (ZnO), silicon oxide (SiO2), titanium oxide (TiO2), zirconium oxide (ZrO2), barium oxide (BaO), calcium oxide (CaO), magnesium oxide (MgO), sodium oxide (Na2O), nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, boehmite, mica, bentonite, hydropyrite, kaolin, and talc.

[0130] In some embodiments, the insulating layer may include an adhesive.

[0131] Optionally, the adhesive may include, but is not limited to, one or more of the following: styrene-butadiene copolymer, acrylate-styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylic rubber, butyl rubber, styrene-butadiene rubber, fluororubber, polyethylene, polypropylene, ethylene propylene diene monomer (EPDM) rubber, ethylene propylene diene monomer (EPDM) rubber, polyethylene oxide, polyepoxychloropropane, polyvinylpyrrolidone, polyphosphazene, polyacrylonitrile, polystyrene, polyvinylpyridine, chlorosulfonated polyethylene, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, hydroxypropyl methylcellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylic acid, polyimide, polyamide-imide, and polyimide-polyamide-imide copolymer.

[0132] In some embodiments, the negative electrode may include both a lithiophilic layer and an insulating layer, the thickness of which may be the same or different.

[0133] In some embodiments, the negative electrode substrate layer may include a negative electrode current collector, which may be a metal foil or a composite current collector.

[0134] Alternatively, as an example, the metal foil may be copper foil, copper alloy foil, nickel foil, nickel alloy foil, aluminum foil, or aluminum alloy foil.

[0135] The composite current collector may include a polymeric material substrate and a metallic material layer formed on at least one side of the polymeric material substrate. Optionally, as an example, the metallic material layer may include, but is not limited to, one or more of copper, copper alloys, aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Optionally, as an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0136] In some embodiments, the negative electrode substrate layer may include a negative electrode current collector and a lithium-based metal layer located on at least one side of the negative electrode current collector.

[0137] Alternatively, the lithium-based metal layer may include lithium or a lithium alloy.

[0138] In some embodiments, the positive electrode may include a positive current collector and a positive electrode film layer located on at least one side of the positive current collector, the positive electrode film layer including a positive active material. The positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0139] In some embodiments, the positive electrode active material may include one or more of lithium transition metal oxides and their modified forms, lithium phosphates and their modified forms.

[0140] Optionally, examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and lithium-rich manganese-based materials.

[0141] Optionally, examples of lithium phosphates may include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0142] In some embodiments, to further improve the energy density of a single battery cell, the positive electrode active material may include materials of the general formula Li. aNi b Co c M d O e A f One or more of lithium transition metal oxides and their modified materials. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M may include one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A may include one or more of N, F, S and Cl.

[0143] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811), LiNi 0.83 Mn 0.08 Co 0.07 O2 (abbreviated as Ni83), LiNi 0.90 Mn 0.05 Co 0.05 O2 (abbreviated as Ni90), LiNi 0.94 Mn 0.03 Co 0.03 O2 (abbreviated as Ni94), LiNi 0.96 Co 0.02 Mn 0.02 O2 (abbreviated as Ni96), LiNi 0.80 Co 0.15 Al 0.05 One or more of O2, LiFePO4, LiMnPO4 and their respective modified materials.

[0144] During the charging and discharging process, lithium (Li) undergoes insertion / extraction and consumption within a single battery cell, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar Li content represents the initial state of the material, i.e., the state before material addition. As the positive electrode active material is applied to the battery cell, the molar Li content changes after charge-discharge cycles. Similarly, the molar O content in the examples of positive electrode active materials in this disclosure is only a theoretical value. Oxygen release from the crystal lattice causes changes in the molar O content, leading to fluctuations in the actual molar O content.

[0145] The modified materials for the above-mentioned positive electrode active materials can be doped and / or surface coated.

[0146] In some embodiments, the positive electrode film layer may further include a positive electrode binder, which may include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene-propylene terpolymer, ethylene-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0147] In some embodiments, the positive electrode film may further include a positive electrode conductive agent, which may include, but is not limited to, one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor-grown carbon fibers (VGCF).

[0148] In some embodiments, the positive current collector may be a metal foil or a composite current collector. Examples of metal foils include carbon-coated aluminum foil, aluminum foil, nickel foil, and titanium foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. Examples of metal materials include, but are not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymer substrates include, but are not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene.

[0149] In some embodiments, the electrolyte may be a liquid electrolyte, i.e., an electrolyte solution. An electrolyte solution includes an electrolyte salt and a solvent.

[0150] In some embodiments, the electrolyte salt may be one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0151] In some embodiments, the solvent may include, but is not limited to, one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0152] In some embodiments, the electrolyte may also include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve overcharge performance, additives that improve high-temperature performance, additives that improve low-temperature performance, etc.

[0153] This disclosure also provides a method for preparing the battery cell of this disclosure.

[0154] The preparation method of a single battery cell includes the following steps:

[0155] An electrode assembly is formed by assembling at least one positive electrode 30, at least two separator films 10, and at least one negative electrode 20. Adjacent positive electrode 30s and negative electrode 20s are separated by separator films 10. The separator film 10 includes a separator film substrate layer 11 and an adhesive layer 12. The separator film substrate layer 11 includes a first main region 111 and a first edge region 112. The first main region 111 is the region of the separator film substrate layer 11 that is directly opposite to the negative electrode 20. The first edge region 112 is the region of the separator film substrate layer 11 that is not directly opposite to the negative electrode 20. The adhesive layer 12 is located on the surface of the first edge region 112 facing the negative electrode 20. The negative electrode 20 includes a negative electrode substrate layer 21, which includes a second main region 211 and a second edge region 212. The second main region 211 is the region of the negative electrode substrate layer 21 that faces the positive electrode 30, and the second edge region 212 is the region of the negative electrode substrate layer 21 that does not face the positive electrode 30. The negative electrode 20 also includes a lithiophilic layer 22, which is located on at least a portion of the surface of the second main region 211; or, the negative electrode 20 also includes an insulating layer 23, which is located on at least a portion of the surface of the second edge region 212; or, the negative electrode 20 also includes a lithiophilic layer 22 and an insulating layer 23, with the lithiophilic layer 22 located on at least a portion of the surface of the second main region 211 and the insulating layer 23 located on at least a portion of the surface of the second edge region 212. The obtained electrode assembly is placed in an outer package, and the adhesive layers 12 of the two adjacent separators 10 on both sides of the negative electrode 20 are bonded together by hot pressing and the negative electrode 20 is wrapped in it. Electrolyte is injected to obtain a battery cell.

[0156] After hot pressing, the edges of the separators on both sides of the negative electrode sheet are bonded together, and the entire negative electrode sheet is wrapped in it to form a bag-like microstructure, which can reduce the amount of pulverized material that escapes from the edge of the negative electrode.

[0157] In some embodiments, the temperature of the hot pressing treatment can be 35°C-90°C, for example, it can be 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or any range of the above values.

[0158] In some embodiments, the hot pressing time can be 1 min to 10 min, for example, it can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, or any range of the above values.

[0159] In some embodiments, the pressure for hot pressing can be 1 MPa to 5 MPa, for example, 1 MPa, 1.2 MPa, 1.4 MPa, 1.6 MPa, 1.8 MPa, 2 MPa, 2.2 MPa, 2.4 MPa, 2.6 MPa, 2.8 MPa, 3 MPa, 3.2 MPa, 3.4 MPa, 3.6 MPa, 3.8 MPa, 4 MPa, 4.2 MPa, 4.4 MPa, 4.6 MPa, 4.8 MPa, 5 MPa, or any range of the above values.

[0160] In some embodiments, the adhesive layer 12 may also be located on at least a portion of the surface of the first body region 111 facing the negative electrode 20, and the adhesive layer 12 is bonded to the negative electrode 20.

[0161] After hot pressing, the negative electrode sheet and the separator are bonded together. The edges of the separator on both sides of the negative electrode sheet are bonded together, and the negative electrode sheet is completely wrapped in it to form a bag-like microstructure, which can reduce the amount of powdery material that escapes from the edge of the negative electrode.

[0162] Example

[0163] The following embodiments describe the disclosure of this disclosure in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0164] Example 1

[0165] Preparation of positive electrode sheet

[0166] LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2, polyvinylidene fluoride (PVDF) as the positive electrode binder, and acetylene black as the positive electrode conductive agent are mixed in a mass ratio of 98:1:1, and N-methylpyrrolidone (NMP) is added and stirred to form a uniform positive electrode slurry. The positive electrode slurry is then uniformly coated onto one surface of the positive electrode current collector aluminum foil, with a positive electrode active material loading of 25 mg / cm³. 2 After drying and cold pressing, the material is cut into rectangular plates of 40mm×50mm to serve as positive electrode plates.

[0167] Preparation of negative electrode sheet

[0168] Two 50μm thick lithium foils were laminated with copper foil using a roll forming method, and then cut into rectangular electrode sheets of 42mm × 52mm. The rectangular electrode sheets were placed in a magnetron sputtering system, and the edge areas of the electrode sheets were covered with a mask; a vacuum of 6 × 10⁻⁶ was then applied. -4 After Pa, argon gas was introduced, followed by radio frequency sputtering; the sputtering power was 60W, the sputtering pressure was 0.4Pa, and the target material was a Bi target; the sputtering time was adjusted to control the Bi layer thickness to 80nm; then the chamber was opened, the mask was removed, and a lithium metal anode sheet modified with a lithophile Bi layer with a central area of ​​40mm×50mm was obtained.

[0169] Preparation of the separating membrane

[0170] Methyl methacrylate monomer (MMA) and n-butyl methacrylate monomer (BA) were mixed in a mass ratio of 4:6 and dissolved in dimethylacetamide solvent (DMAc). The mixture was stirred and mixed evenly under a N2 atmosphere. Then, azobisisobutyronitrile (AIBN) was added, wherein the mass ratio of AIBN to the total mass of monomers (MMA+BA) was 1:99. The mixture was stirred at 85°C for 12 hours, followed by washing with water, purification and drying to obtain polymethyl methacrylate co-butyl methacrylate (P(MMA-co-BA)) powder.

[0171] P(MMA-co-BA) powder and dimethylformamide (DMF) were mixed at a mass ratio of 1:39 and stirred for 24 hours to obtain an adhesive layer solution. The adhesive layer solution was coated onto one surface of a porous polypropylene membrane, dried to remove moisture, and then cut into 44mm × 54mm sheets as a release liner. The thickness of the adhesive layer was 2μm, and the area of ​​the adhesive layer was 44mm × 54mm.

[0172] Preparation of electrolyte

[0173] The electrolyte solvent is a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7, and the lithium salt is lithium hexafluorophosphate (LiPF6) with a concentration of 1 mol / L.

[0174] Preparation of battery cells

[0175] One positive electrode, one separator, one negative electrode, one separator, and one positive electrode are stacked in sequence, with the adhesive layers of two separators facing each other. Then, the positive and negative electrodes are welded together, and then wrapped in an outer packaging aluminum-plastic film bag for sealing. The aluminum-plastic film is then hot-pressed at a temperature of 45°C for 300 seconds (5 minutes) and a pressure of 1.5 MPa. After that, 0.3 g of electrolyte is injected and sealed. Then, it is left to stand at 25°C for more than 6 hours to obtain a single battery cell.

[0176] Example 2

[0177] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0178] Preparation of negative electrode sheet

[0179] Two 50μm thick lithium foils were laminated with copper foil using a roll forming method, and then cut into rectangular electrode sheets of 42mm × 52mm. The rectangular electrode sheets were placed in a magnetron sputtering system, and the edge areas of the electrode sheets were covered with a mask; a vacuum of 6 × 10⁻⁶ was then applied. -4 After Pa, argon gas was introduced, followed by radio frequency sputtering; the sputtering power was 60W, the sputtering pressure was 0.4Pa, and the target material was a Bi target; the sputtering time was adjusted to control the Bi layer thickness to 60nm; then the chamber was opened, the mask was removed, and a lithium metal anode sheet modified with a lithophile Bi layer with a central area of ​​40mm×50mm was obtained.

[0180] Example 3

[0181] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0182] Preparation of negative electrode sheet

[0183] Two 50μm thick lithium foils were laminated with copper foil using a roll forming method, and then cut into rectangular electrode sheets of 42mm × 52mm. The rectangular electrode sheets were placed in a magnetron sputtering system, and the edge areas of the electrode sheets were covered with a mask; a vacuum of 6 × 10⁻⁶ was then applied. -4 After Pa, argon gas was introduced, followed by radio frequency sputtering; the sputtering power was 60W, the sputtering pressure was 0.4Pa, and the target material was a Bi target; the sputtering time was adjusted to control the Bi layer thickness to 30nm; then the chamber was opened, the mask was removed, and a lithium metal anode sheet modified with a lithophile Bi layer with a central area of ​​40mm×50mm was obtained.

[0184] Example 4

[0185] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0186] Preparation of the separating membrane

[0187] P(MMA-co-BA) powder and dimethylformamide (DMF) were mixed at a mass ratio of 1:39 and stirred for 24 hours to obtain an adhesive layer solution. The adhesive layer solution was coated onto one surface of a porous polypropylene membrane, dried to remove moisture, and then cut into 44mm × 54mm sheets as a release liner. The thickness of the adhesive layer was 4μm, and the area of ​​the adhesive layer was 44mm × 54mm.

[0188] Example 5

[0189] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0190] Preparation of the separating membrane

[0191] P(MMA-co-BA) powder and dimethylformamide (DMF) were mixed at a mass ratio of 1:39 and stirred for 24 hours to obtain an adhesive layer solution. The adhesive layer solution was coated onto one surface of a porous polypropylene membrane, dried to remove moisture, and then cut into 44mm × 54mm sheets as a release liner. The thickness of the adhesive layer was 6μm, and the area of ​​the adhesive layer was 44mm × 54mm.

[0192] Example 6

[0193] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0194] Preparation of the separating membrane

[0195] P(MMA-co-BA) powder and dimethylformamide (DMF) were mixed at a mass ratio of 1:39 and stirred for 24 hours to obtain an adhesive layer solution. The adhesive layer solution was coated onto one surface of a porous polypropylene membrane, dried to remove moisture, and then cut into 44mm × 54mm sheets as a release liner. The thickness of the adhesive layer was 1μm, and the area of ​​the adhesive layer was 44mm × 54mm.

[0196] Example 7

[0197] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0198] Preparation of the separating membrane

[0199] P(MMA-co-BA) powder and dimethylformamide (DMF) were mixed at a mass ratio of 1:39 and stirred for 24 hours to obtain an adhesive layer solution. The adhesive layer solution was coated onto one surface of a porous polypropylene membrane, dried to remove moisture, and then cut into 44mm × 54mm sheets as a release liner. The thickness of the adhesive layer was 0.5μm, and the area of ​​the adhesive layer was 44mm × 54mm.

[0200] Example 8

[0201] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0202] Preparation of the separating membrane

[0203] Polyurethane and dimethylformamide (DMF) were mixed at a mass ratio of 1:39 and stirred for 24 hours to obtain an adhesive layer solution. The adhesive layer solution was coated onto one surface of a porous polypropylene membrane, dried to remove moisture, and then cut into 44mm × 54mm sheets as release films. The thickness of the adhesive layer was 2μm, and the area of ​​the adhesive layer was 44mm × 54mm.

[0204] Example 9

[0205] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0206] Preparation of the separating membrane

[0207] P(MMA-co-BA) powder and dimethylformamide (DMF) were mixed at a mass ratio of 1:39 and stirred for 24 hours to obtain an adhesive layer solution. A porous polypropylene membrane was cut into 44mm × 54mm sheets. The adhesive layer solution was then coated onto the edge of one surface of the porous polypropylene membrane and dried to remove moisture, resulting in a separator membrane. The adhesive layer had a thickness of 2μm, was annular in shape, and had a width of 2mm. The area of ​​the porous polypropylene membrane without the adhesive layer was 42mm × 52mm, and this area was directly opposite the negative electrode.

[0208] Example 10

[0209] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0210] Preparation of negative electrode sheet

[0211] Two 50μm thick lithium foils are laminated with copper foil using a roll forming method, and then cut into rectangular electrode sheets of 42mm × 52mm. SiO2 and polyvinylidene fluoride (PVDF) are dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 49:1 and mixed evenly to obtain an insulating slurry. This slurry is then coated onto the edge area of ​​the electrode sheet and dried to remove moisture, resulting in the negative electrode sheet. The insulating layer is 4μm thick, annular in shape, and 2mm wide. The area of ​​the negative electrode sheet without the insulating layer is 40mm × 50mm, and this area is directly opposite the positive electrode sheet.

[0212] Comparative Example 1

[0213] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0214] Preparation of the separating membrane

[0215] The porous polypropylene membrane was cut into 44mm×54mm sheets to serve as a release liner.

[0216] Comparative Example 2

[0217] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0218] Preparation of the separating membrane

[0219] P(MMA-co-BA) powder and dimethylformamide (DMF) were mixed at a mass ratio of 1:39 and stirred for 24 hours to obtain an adhesive layer solution. The adhesive layer solution was coated onto one surface of a porous polypropylene membrane, dried to remove moisture, and then cut into 44mm × 54mm sheets as separators. The thickness of the adhesive layer was 2μm, the area of ​​the adhesive layer was 40mm × 50mm, and the adhesive layer was directly opposite the positive electrode.

[0220] Comparative Example 3

[0221] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0222] Preparation of the separating membrane

[0223] Two 50μm thick lithium foils are combined with copper foil by rolling, and then cut into rectangular electrodes of 42mm×52mm as negative electrodes.

[0224] Comparative Example 4

[0225] Except for the following differences, the preparation method of the battery cell is the same as that in Example 1.

[0226] Preparation of negative electrode sheet

[0227] Two 50μm thick lithium foils were laminated with copper foil using a roll forming method, and then cut into rectangular electrode sheets of 42mm × 52mm. The rectangular electrode sheets were placed in a magnetron sputtering system and evacuated to a vacuum of 6 × 10⁻⁶. -4 After Pa, argon gas was introduced, followed by radio frequency sputtering; the sputtering power was 60W, the sputtering pressure was 0.4Pa, and the target material was a Bi target; the sputtering time was adjusted to control the Bi layer thickness to 80nm; then the chamber was opened, the mask was removed, and a lithium metal anode sheet with a 42mm×52mm area modified with a lithiophilic Bi layer was obtained.

[0228] Performance testing

[0229] Cyclic performance tests were conducted on individual battery cells at 25°C using a 0.2C (28mA) charge and a 1C (140mA) discharge rate. Specifically, the battery cells were charged at a constant current rate of 0.2C to 4.3V, followed by constant voltage charging until the current decayed to 0.15C; then discharged at a constant current rate of 1C to a voltage of 2.8V to obtain the first discharge capacity; subsequent charge-discharge cycles were performed following the same steps.

[0230] Table 1

[0231] The test results from Examples 1 to 10 and Comparative Examples 1 to 2 show that bonding the two adjacent separator layers on both sides of the negative electrode sheet together and encapsulating the negative electrode sheet within them can better reduce the possibility of pulverized material detaching from the edge of the negative electrode and drifting to the positive electrode, thereby improving the cycle performance of the battery cell. In Comparative Example 2, the adhesive layer of the separator is directly opposite the positive electrode sheet, and no adhesive layer is provided at the edge of the separator. Therefore, the negative electrode sheet cannot be encapsulated, and pulverized material may still detach from the edge of the negative electrode and drift to the positive electrode, resulting in poor long-cycle performance of the battery cell.

[0232] The test results from Examples 1 to 10 and Comparative Examples 3 to 4 also show that placing a lithiophilic layer at the position where the negative electrode and positive electrode face each other, and not placing a lithiophilic layer in the area where the negative electrode and positive electrode do not face each other, or placing an insulating layer in the area where the negative electrode and positive electrode do not face each other, can better reduce the possibility of lithium pulverization leaching from the edge of the negative electrode and drifting to the positive electrode, thereby improving the cycle performance of the battery cell. Comparative Example 3 has neither a lithiophilic layer nor an insulating layer on its negative electrode, and Comparative Example 4 also has a lithiophilic layer in the area where the negative electrode and positive electrode do not face each other. Therefore, neither of these methods can effectively reduce the possibility of lithium pulverization leaching from the edge of the negative electrode and drifting to the positive electrode, thus leading to a higher likelihood of overcharging in the battery cell.

[0233] As can be seen from the test results of Examples 1 to 3, further adjusting the thickness of the lithium-affinity layer in the negative electrode sheet can further improve the cycle performance of the battery cell.

[0234] The test results of Examples 1, 4 to 7 show that further adjusting the thickness of the adhesive layer in the separator can further improve the cycle performance of the battery cell.

[0235] It should be noted that this disclosure is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this disclosure are included within the technical scope of this disclosure. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, are also included within the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. A battery cell, wherein, The battery cell includes an electrode assembly, which includes at least one positive electrode sheet, at least two separators and at least one negative electrode sheet, and adjacent positive and negative electrode sheets are separated by the separators. The separator includes a separator substrate layer and an adhesive layer. The separator substrate layer includes a first main region and a first edge region. The first main region is the region of the separator substrate layer that faces the negative electrode sheet. The first edge region is the region of the separator substrate layer that does not face the negative electrode sheet. The adhesive layer is located on the surface of the first edge region facing the negative electrode sheet. The adhesive layers of two adjacent separator layers on both sides of the negative electrode sheet are bonded to each other and encapsulate the negative electrode sheet therein. The negative electrode sheet includes a negative electrode substrate layer, which includes a second main region and a second edge region. The second main region is the region of the negative electrode substrate layer that is directly opposite to the positive electrode sheet, and the second edge region is the region of the negative electrode substrate layer that is not directly opposite to the positive electrode sheet. The negative electrode further includes a lithiophilic layer located on at least a portion of the surface of the second main body region; or, the negative electrode further includes an insulating layer located on at least a portion of the surface of the second edge region; or, the negative electrode further includes a lithiophilic layer and an insulating layer, the lithiophilic layer located on at least a portion of the surface of the second main body region, and the insulating layer located on at least a portion of the surface of the second edge region.

2. The battery cell according to claim 1, wherein, The adhesive layer is also located on at least a portion of the surface of the first main body region facing the negative electrode sheet, and the adhesive layer is bonded to the negative electrode sheet.

3. The battery cell according to any one of claims 1-2, wherein, The thickness of the adhesive layer is 0.5μm-10μm.

4. The battery cell according to any one of claims 1-3, wherein, The adhesive layer comprises one or more of a first polymer and a polymer solid electrolyte material.

5. The battery cell according to claim 4, wherein, The first polymer includes one or more of acrylate polymers, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyethylene glycol, styrene-butadiene rubber, and their respective derivatives; and / or, The polymer solid electrolyte material is formed by complexing a polymer matrix material with a lithium salt. The polymer matrix material includes one or more of polyethylene oxide, polypropylene oxide, polycarbonate, polyacrylonitrile, polysiloxane, polyvinylidene fluoride, acrylate polymers, and their respective derivatives.

6. The battery cell according to any one of claims 1-5, wherein, The lithiophilic layer comprises one or more of a lithiophilic metal, a lithiophilic alloy, and a lithiophilic oxide; and / or, The thickness of the lithiophilic layer is 20nm-1000nm.

7. The battery cell according to any one of claims 1-6, wherein, The lithiophilic layer comprises one or more of the following: elemental gold, silver, indium, bismuth, zinc, tin, gallium, and germanium, alloys, and oxides.

8. The battery cell according to any one of claims 1-7, wherein, The thickness of the insulating layer is 0.2 μm-20 μm; and / or, The insulating layer includes insulating filler.

9. The battery cell according to claim 8, wherein, The insulating filler includes one or more of ceramic materials, silicate materials, minerals, and glass.

10. The battery cell according to any one of claims 1-9, wherein, The base layer of the isolation membrane includes a porous base membrane.

11. The battery cell according to any one of claims 1-9, wherein, The isolation membrane substrate layer includes a porous base membrane and a heat-resistant coating located on at least one side of the porous base membrane. The heat-resistant coating includes one or more of organic particles, inorganic particles, and organic-inorganic composite particles.

12. The battery cell according to any one of claims 1-11, wherein, The negative electrode substrate layer includes a negative electrode current collector, which is a metal foil or a composite current collector. The composite current collector includes a polymer material base layer and a metal material layer formed on at least one side of the polymer material base layer.

13. The battery cell according to any one of claims 1-11, wherein, The negative electrode substrate layer includes a negative electrode current collector and a lithium-based metal layer located on at least one side of the negative electrode current collector. The negative electrode current collector is a metal foil or a composite current collector. The composite current collector includes a polymer material base layer and a metal material layer formed on at least one side of the polymer material base layer.

14. The battery cell according to any one of claims 1-13, wherein, The electrode assembly is a stacked electrode assembly.

15. The battery cell according to any one of claims 1-13, wherein, The electrode assembly is a wound electrode assembly, which is formed by sequentially stacking and winding a positive electrode sheet, a separator, a negative electrode sheet, and a separator.

16. A method for preparing a single battery cell, comprising the following steps: An electrode assembly is formed by assembling at least one positive electrode, at least two separator layers, and at least one negative electrode, with adjacent positive and negative electrodes separated by the separator layers. The separator layer includes a separator substrate layer and an adhesive layer. The separator substrate layer includes a first main region and a first edge region. The first main region is the area of ​​the separator substrate layer directly opposite the negative electrode, and the first edge region is the area of ​​the separator substrate layer not directly opposite the negative electrode. The adhesive layer is located on the surface of the first edge region facing the negative electrode. The negative electrode includes a negative electrode substrate layer, which includes… The second main region and the second edge region are defined as follows: the second main region is the area where the negative electrode substrate layer is directly opposite the positive electrode sheet; the second edge region is the area where the negative electrode substrate layer is not directly opposite the positive electrode sheet. The negative electrode sheet further includes a lithiophilic layer located on at least a portion of the surface of the second main region; or, the negative electrode sheet further includes an insulating layer located on at least a portion of the surface of the second edge region; or, the negative electrode sheet further includes a lithiophilic layer and an insulating layer, with the lithiophilic layer located on at least a portion of the surface of the second main region and the insulating layer located on at least a portion of the surface of the second edge region. The obtained electrode assembly is placed in an outer package, and the adhesive layers of the two adjacent separators on both sides of the negative electrode sheet are bonded together by hot pressing, thus encapsulating the negative electrode sheet therein. Electrolyte is injected to obtain a single battery cell.

17. A battery device comprising a plurality of battery cells as described in any one of claims 1-15.

18. An electrical device comprising a battery cell as described in any one of claims 1-15 or a battery device as described in claim 17.

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