Electrode assembly, battery cell and preparation method therefor, battery, and electric device

Abstract

The present application relates to an electrode assembly, a battery cell and a preparation method therefor, a battery, and an electric device. The electrode assembly comprises: a first electrode sheet; a second electrode sheet, which is stacked with the first electrode sheet; a first separator, which is sandwiched between the first electrode sheet and the second electrode sheet; and a second separator, which is stacked on the side of the first electrode sheet facing away from the first separator; wherein a closed cavity for accommodating the first electrode sheet is formed between the first separator and the second separator. In the present application, the first separator and the second separator define a closed cavity, the first electrode sheet and a first electrolyte are both accommodated in the closed cavity, and a second electrolyte fills between the second electrode sheet and the first separator, so that the first electrolyte independently acts on the first electrode sheet, the second electrolyte independently acts on the second electrode sheet, and the first electrolyte and the second electrolyte do not affect each other, thereby effectively reducing the impact of a positive electrode electrolyte on a negative electrode and the impact of a negative electrode electrolyte on a positive electrode, and improving battery performance.

Description

Electrode assembly, battery cell, preparation method thereof, battery, and electrical device

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. 2024101087580, filed on January 25, 2024, entitled “An electrode assembly, a battery cell, a method for preparing the same, a battery, and an electrical device,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to an electrode assembly, a battery cell and a preparation method thereof, a battery, and an electrical device. Background Art

[0004] In lithium-ion batteries, the positive and negative electrodes are made of different materials, resulting in different requirements for the electrolyte composition. While different electrolyte components may promote one of the positive or negative electrodes, they may negatively impact the other, ultimately affecting battery performance.

[0005] Summary of the Invention

[0006] Based on this, the present application provides an electrode assembly, a battery cell and a preparation method thereof, a battery, and an electrical device.

[0007] In a first aspect, the present application provides an electrode assembly, which is a wound electrode assembly and includes:

[0008] First pole piece;

[0009] A second pole piece, stacked with the first pole piece;

[0010] A first diaphragm is sandwiched between the first pole piece and the second pole piece; and

[0011] a second diaphragm, laminated on a side of the first electrode facing away from the first diaphragm;

[0012] A closed cavity for accommodating the first pole piece is formed between the first diaphragm and the second diaphragm.

[0013] Through the above structure, the first electrode and the first electrolyte are placed together in the closed cavity, and the second electrode and the second electrolyte are located outside the closed cavity. As a result, the first electrolyte acts independently on the first electrode, and the second electrolyte acts independently on the second electrode, and the two do not affect each other, thereby effectively reducing the impact of the first electrolyte on the second electrode and the impact of the second electrolyte on the first electrode, thereby improving battery performance.

[0014] In some embodiments, a bonding area is provided on the first diaphragm and / or the second diaphragm, and the bonding area is arranged around the edge of the first diaphragm and / or the second diaphragm to form a closed ring structure;

[0015] The first diaphragm and the second diaphragm are bonded together through the bonding area and enclosed to form a closed cavity.

[0016] By setting the bonding area, the first diaphragm and the second diaphragm can be bonded and fixed along the edge, and smoothly enclosed to form a closed cavity, so that the first electrode and the first electrolyte are accommodated in the closed cavity, and the second electrode and the second electrolyte are isolated outside the closed cavity, thereby realizing the separate and independent accommodation of the first electrolyte and the second electrolyte, and reducing the probability of the first electrolyte and the second electrolyte mixing with each other and affecting the first electrode or the second electrode.

[0017] In some embodiments, opposite ends of the first diaphragm and / or the second diaphragm along their width direction respectively extend beyond the first pole piece, and the extended portions respectively form first extension portions;

[0018] The bonding area includes two first sub-bonding areas, which are located at both ends of the first diaphragm and / or the second diaphragm in the width direction, and each first sub-bonding area is at least partially correspondingly arranged on the first protruding portion.

[0019] Through the above structure, the first diaphragm and the second diaphragm can be bonded in the width direction through the first sub-bonding area on the first extension portion, so that the first electrode can be better accommodated in the closed cavity formed between the first diaphragm and the second diaphragm, so as to facilitate a more complete reaction between the first electrode and the first electrolyte in the closed cavity.

[0020] In some embodiments, a coating region and an uncoated region are provided on the first electrode piece, the coating region is provided with an active material layer, and the uncoated region is provided on opposite sides of the coating region along the width direction of the first electrode piece;

[0021] In the width direction of the first diaphragm or the second diaphragm, the width of each first sub-bonding area is not greater than the sum of the widths of the corresponding first protruding portion and the uncoated area.

[0022] With the above structure, the probability of the first sub-adhesive region covering the coating region can be reduced, so that the contact area between the active material layer on the coating region and the first electrolyte is larger, thereby improving the reaction efficiency.

[0023] In some embodiments, the first pole piece includes a main body and a pole ear portion, the coated area and the uncoated area are both located on the main body, the pole ear portion is connected to the uncoated area, and the pole ear portion extends out of the closed cavity along the width direction of the first pole piece.

[0024] Through the above structure, during the bonding process of the first diaphragm and the second diaphragm, the overlapping portion of the pole ear portion of the first electrode piece and the first sub-bonding area is bonded simultaneously. On the one hand, it can improve the sealing of the closed cavity and reduce the probability of the first electrolyte flowing out of the closed cavity through the gap between the pole ear portion and the first diaphragm or the second diaphragm. On the other hand, it can improve the stability of the first electrode piece in the closed cavity.

[0025] In some embodiments, opposite ends of the first diaphragm and / or the second diaphragm along their own length direction respectively extend beyond the first pole piece, and the extending portions respectively form second extension portions;

[0026] The bonding area includes two second sub-bonding areas, which are located at both ends of the first diaphragm and / or the second diaphragm in the length direction, and each second sub-bonding area is correspondingly arranged on the second protruding portion.

[0027] Through the above structure, the first diaphragm and the second diaphragm can be bonded in the length direction through the second sub-bonding area on the second extension portion, so that the first electrode can be better accommodated in the closed cavity formed between the first diaphragm and the second diaphragm, so as to facilitate a more complete reaction between the first electrode and the first electrolyte in the closed cavity.

[0028] In some embodiments, the air permeability of the first membrane is ≥ 20000 s / 100 cc, and the ionic conductivity of the first membrane is ≥ 0.1 mS / cm 2 .

[0029] In some embodiments, the air permeability of the second membrane is ≥ 20000 s / 100 cc, and the ionic conductivity of the second membrane is ≥ 0.1 mS / cm 2 .

[0030] Therefore, setting the air permeability and ionic conductivity of the first and second diaphragms within the above ranges can further improve the sealing performance of the closed cavity with respect to the first electrolyte, thereby allowing the first electrolyte to act more stably on the first electrode in the closed cavity.

[0031] In a second aspect, the present application further provides a battery cell comprising a first electrolyte, a second electrolyte and the above electrode assembly, wherein the first electrolyte is filled in the closed cavity, and the second electrolyte is filled between the second electrode plate and the first diaphragm.

[0032] In some embodiments, the first electrolyte and the second electrolyte have different compositions.

[0033] In some embodiments, the first electrolyte and the second electrolyte have different contents.

[0034] In some embodiments, the first electrolyte is a gel electrolyte.

[0035] In some embodiments, the second electrolyte is a gel electrolyte.

[0036] Through the above structure, the probability of mixing between the first electrolyte and the second electrolyte can be further reduced based on the inherent characteristics of the electrolyte, thereby reducing the probability of the first electrolyte affecting the second electrode and the probability of the second electrolyte affecting the first electrode.

[0037] In some embodiments, the first electrolyte includes a base electrolyte and a polymer matrix; the polymer matrix includes a homopolymer or a copolymer of a first monomer unit, and the first monomer unit includes at least one of an acrylic monomer unit and an acrylate monomer unit.

[0038] In some embodiments, the second electrolyte includes a base electrolyte and a polymer matrix; the polymer matrix includes a homopolymer or a copolymer of a first monomer unit, and the first monomer unit includes at least one of an acrylic monomer unit and an acrylate monomer unit.

[0039] In some embodiments, the polymer matrix also includes a homopolymer or copolymer of a second monomer unit, and the second monomer unit includes one or more of an ethylenically unsaturated carbonate monomer unit, an ethylenically unsaturated sulfate monomer unit, an ethylenically unsaturated sulfonate monomer unit, an ethylenically unsaturated sulfone monomer unit, an ethylenically unsaturated carboxylate monomer unit, an ethylenically unsaturated phosphate monomer unit, an ethylenically unsaturated nitrile monomer unit, and an ethylenically unsaturated ether monomer unit.

[0040] In some embodiments, the battery cell further includes a shell, and the electrode assembly is accommodated inside the shell.

[0041] In a third aspect, the present application also provides a battery comprising the battery cell described above.

[0042] In a fourth aspect, the present application also provides an electrical device comprising the battery as described above.

[0043] In a fifth aspect, the present application also provides a method for preparing a battery cell, comprising the following steps:

[0044] Applying a first electrolyte on the first surface of the first electrode;

[0045] laminating a second separator on one side of the first surface coated with the first electrolyte;

[0046] The first diaphragm is laminated on a side of the second surface of the first electrode piece opposite to the first surface, and is bonded to the second diaphragm to form a closed cavity, so that the first electrode piece is accommodated in the closed cavity;

[0047] The second electrode piece is stacked on a side of the first diaphragm away from the first electrode piece;

[0048] Winding the stacked second diaphragm, the first electrode sheet, the first diaphragm, and the second electrode sheet to form an electrode assembly;

[0049] The electrode assembly is placed in the housing, and the second electrolyte is filled between the second electrode plate and the first separator.

[0050] In some embodiments, after the step of coating the first electrolyte on the first surface of the first electrode sheet, the method further includes the following steps:

[0051] The first electrolyte is gelled to obtain a gel electrolyte.

[0052] In some embodiments, after placing the electrode assembly into the housing and filling the second electrolyte between the second electrode plate and the first separator, the method further includes the following steps:

[0053] The second electrolyte is gelled to obtain a gel electrolyte.

[0054] The above-mentioned electrode assembly, battery cell and preparation method thereof, battery, and electrical device are enclosed by the first diaphragm and the second diaphragm to form a closed cavity, and the first electrode plate and the first electrolyte are jointly accommodated in the closed cavity, and the second electrolyte is filled between the second electrode plate and the first diaphragm; wherein, the first electrolyte and the first electrode plate can be correspondingly set as the positive electrode electrolyte and the positive electrode plate, and the second electrolyte and the second electrode plate can be set as the negative electrode electrolyte and the negative electrode plate. Of course, the first electrolyte and the first electrode plate can also be correspondingly set as the negative electrode electrolyte and the negative electrode plate, and the second electrolyte and the second electrode plate can be set as the positive electrode electrolyte and the positive electrode plate; in this way, the first electrolyte acts independently on the first electrode plate, and the second electrolyte acts independently on the second electrode plate, and the two do not affect each other, thereby effectively reducing the influence of the positive electrode electrolyte on the negative electrode and the influence of the negative electrode electrolyte on the positive electrode, thereby improving battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] 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 embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0056] FIG1 is a schematic structural diagram of an electrode assembly according to one or more embodiments.

[0057] FIG. 2 is a schematic structural diagram of a first separator or a second separator in an electrode assembly according to one or more embodiments.

[0058] FIG3 is a schematic structural diagram of a first diaphragm or a second diaphragm and a first electrode piece in an electrode assembly according to one or more embodiments.

[0059] FIG. 4 is a schematic diagram of a process for preparing a battery cell according to one or more embodiments.

[0060] FIG. 5 is a flowchart of a method for preparing a battery cell according to one or more embodiments.

[0061] Explanation of the accompanying drawings: 100, electrode assembly; 10, first pole piece; 20, second pole piece; 30, first diaphragm; 40, second diaphragm; 50, closed cavity; 60, bonding area; 11, main body; 12, pole ear; 13, first surface; 14, second surface; 31, first extension; 32, second extension; 61, first sub-bonding area; 62, second sub-bonding area; a, width direction; b, length direction. DETAILED DESCRIPTION

[0062] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0063] In the description of this application, it should be understood that if 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", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0064] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, if the term "plurality" appears, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0065] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connected," "fixed," etc., should be interpreted broadly. For example, these terms may refer to fixed connections, removable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; and internal communication between two components or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0066] In this application, unless otherwise expressly specified or limited, if a first feature is described as being "above" or "below" a second feature, or similar descriptions, this may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is described as being "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is described as being "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0067] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only embodiment.

[0068] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric vehicles, as well as in other fields. As the application of power batteries continues to expand, market demand is also growing.

[0069] A battery cell is the smallest unit that makes up a battery. In a battery, there can be multiple battery cells, and multiple battery cells can be connected in series, in parallel, or in mixed connection. Mixed connection means that multiple battery cells are connected in both series and in parallel.

[0070] Furthermore, a battery cell includes a housing and an electrode assembly housed within the housing. Battery cells can be divided into wound-type battery cells and laminated-type battery cells based on their molding methods and structures. In a wound-type battery cell, the positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, then wound to form an integral structure. The wound structure is then pressed and shaped to form an electrode assembly, which is then housed within the housing to form a battery cell.

[0071] Specifically, the electrode assembly is the component within a battery cell where the electrochemical reaction occurs. For wound-type battery cells, the electrode assembly is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet. The portions of the positive and negative electrodes containing active material constitute the main body of the electrode assembly, while the portions of the positive and negative electrodes without active material each constitute the tabs. The positive and negative tabs can be located together at one end of the main body or separately at opposite ends.

[0072] In the current structure of wound battery cells, the electrolyte is filled in the shell to conduct active ions between the positive and negative electrodes. However, other components in the electrolyte besides the active ions will also diffuse between the positive and negative electrodes through the diaphragm. The diffusion of other components besides the active ions often deteriorates the performance of the battery cell. For example, anions will penetrate the diaphragm to cause internal polarization of the battery cell, thereby affecting the rate performance of the battery cell. In addition, the positive and negative electrodes have different requirements for the composition of the electrolyte and some of the additives. For example, some additives in the electrolyte may only be effective for one of the positive or negative electrodes, but ineffective or even have a deteriorating effect on the other. In this way, the additives in the electrolyte will affect the electrochemical reaction of the positive or negative electrode, resulting in the performance of the battery being affected.

[0073] Based on the above considerations, in order to solve the problem that the electrolyte in the current battery cell will have a negative impact on the positive electrode or negative electrode, thereby affecting the battery performance, an electrode assembly is provided in one or more embodiments of the present application, in which a closed cavity is formed by enclosing a first diaphragm and a second diaphragm, and the first electrode plate and the first electrolyte are jointly accommodated in the closed cavity, and the second electrolyte is filled between the second electrode plate and the first diaphragm; wherein the first electrolyte and the first electrode plate can be correspondingly set as a positive electrode electrolyte and a positive electrode plate, and the second electrolyte and the second electrode plate are set as a negative electrode electrolyte and a negative electrode plate. Of course, the first electrolyte and the first electrode plate can also be correspondingly set as a negative electrode electrolyte and a negative electrode plate, and the second electrolyte and the second electrode plate are set as a positive electrode electrolyte and a positive electrode plate; in this way, the first electrolyte acts independently on the first electrode plate, and the second electrolyte acts independently on the second electrode plate, and the two do not affect each other, thereby effectively reducing the influence of the positive electrode electrolyte on the negative electrode and the influence of the negative electrode electrolyte on the positive electrode, thereby improving battery performance.

[0074] Referring to FIG1 , an embodiment of the present application provides an electrode assembly 100. The electrode assembly 100 is a wound electrode assembly 100 and includes a first electrode sheet 10, a second electrode sheet 20, a first separator 30, and a second separator 40. The second electrode sheet 20 is stacked with the first electrode sheet 10, the first separator 30 is sandwiched between the first electrode sheet 10 and the second electrode sheet 20, and the second separator 40 is stacked on the side of the first electrode sheet 10 facing away from the first separator 30. A closed cavity 50 is formed between the first separator 30 and the second separator 40 to accommodate the first electrode sheet 10.

[0075] It should be noted that the first electrode 10 and the second electrode 20 are respectively a positive electrode and a negative electrode, wherein the first electrode 10 can be a positive electrode or a negative electrode. When the first electrode 10 is a positive electrode, the second electrode 20 is a negative electrode; when the first electrode 10 is a negative electrode, the second electrode 20 is a positive electrode.

[0076] The first electrode sheet 10 and the second electrode sheet 20 are stacked along the thickness direction. The first diaphragm 30 is the diaphragm disposed between the first electrode sheet 10 and the second electrode sheet 20 along the thickness direction. The second diaphragm 40 is the diaphragm disposed along the thickness direction on the side of the first electrode sheet 10 facing away from the first diaphragm 30 and the second electrode sheet 20. In other words, the second diaphragm 40, the first electrode sheet 10, the first diaphragm 30, and the second electrode sheet 20 are stacked in this order. After winding, the first diaphragm 30 and the second diaphragm 40 are sandwiched between the adjacent first electrode sheet 10 and the second electrode sheet 20 to provide insulation and isolation.

[0077] The closed cavity 50 is formed by the first diaphragm 30 and the second diaphragm 40, and the interior of the closed cavity 50 can be independent of the outside, so that the active ions can be smoothly conducted between the inside and outside of the closed cavity 50, and other components except the active ions can be isolated inside and outside the closed cavity 50 respectively, thereby reducing the mutual influence between the inside and outside of the closed cavity 50 and other components except the active ions.

[0078] The first separator 30 and the second separator 40 can be connected at their edges to form a closed cavity 50, but are not limited to these. The first electrode sheet 10 located between the first separator 30 and the second separator 40 is accommodated within the closed cavity 50. The second separator 40, the first electrode sheet 10, the first separator 30, and the second electrode sheet 20 are sequentially stacked and then wound to form the wound electrode assembly 100. As a result, the first electrode sheet 10 and the first electrolyte are located together within the closed cavity 50, while the second electrode sheet 20 and the second electrolyte are located outside the closed cavity 50, thereby isolating the first electrolyte from the second electrolyte through the closed cavity 50.

[0079] Through the above structure, the first electrode 10 and the first electrolyte are accommodated together in the closed cavity 50, and the second electrode 20 and the second electrolyte are located outside the closed cavity 50. As a result, the first electrolyte acts independently on the first electrode 10, and the second electrolyte acts independently on the second electrode 20, without affecting each other, thereby effectively reducing the influence of the first electrolyte on the second electrode 20 and the influence of the second electrolyte on the first electrode 10, thereby improving battery performance.

[0080] Referring to Figures 1 and 2 , in some embodiments, a bonding area 60 is provided on the first diaphragm 30 and / or the second diaphragm 40. The bonding area 60 surrounds the edge of the first diaphragm 30 and / or the second diaphragm 40 to form a closed annular structure. The first diaphragm 30 and the second diaphragm 40 are bonded together by the bonding area 60 to form a closed cavity 50.

[0081] Specifically, the bonding area 60 can be set on the surface of the first diaphragm 30 facing the second diaphragm 40, or on the surface of the second diaphragm 40 facing the first diaphragm 30, or on the surfaces of the first diaphragm 30 and the second diaphragm 40 facing each other.

[0082] The bonding area 60 is a structure that can provide bonding force between the first diaphragm 30 and the second diaphragm 40 so that the first diaphragm 30 and the second diaphragm 40 can be bonded and fixed to each other.

[0083] The adhesive region 60 is disposed around the edges of the first diaphragm 30 and / or the second diaphragm 40, extending along the edges of the first diaphragm 30 and / or the second diaphragm 40 to form a closed annular structure. Thus, when the first diaphragm 30 and the second diaphragm 40 are attached to each other, the adhesive region 60 ensures a tight fit between the edges of the first diaphragm 30 and the second diaphragm 40. The absence of the adhesive region 60 prevents the first diaphragm 30 and the second diaphragm 40 from attaching to each other. In other words, the first diaphragm 30 and the second diaphragm 40 are bonded together by the adhesive region 60, forming a closed, bag-like cavity 50.

[0084] At this time, the first electrode 10 and the first electrolyte are contained in the closed cavity 50, and the second electrode 20 and the second electrolyte are located outside the closed cavity 50, so that isolation between the first electrolyte and the second electrolyte can be achieved, so that the first electrolyte acts independently on the first electrode 10, and the second electrolyte acts independently on the second electrode 20.

[0085] In addition, the bonding area 60 can be a rubber strip adhered to the first diaphragm 30 and / or the second diaphragm 40, and the bonding between the first diaphragm 30 and the second diaphragm 40 is achieved through the rubber strip, so that the first diaphragm 30 and the second diaphragm 40 are enclosed to form a closed cavity 50.

[0086] By providing the bonding area 60, the first diaphragm 30 and the second diaphragm 40 can be bonded and fixed along the edges, and smoothly enclosed to form a closed cavity 50, so that the first electrode 10 and the first electrolyte are accommodated in the closed cavity 50, and the second electrode 20 and the second electrolyte are isolated outside the closed cavity 50, thereby realizing the separate and independent accommodation of the first electrolyte and the second electrolyte, and reducing the probability of the first electrolyte and the second electrolyte mixing with each other and affecting the first electrode 10 or the second electrode 20.

[0087] Referring to Figures 1, 2, and 3, in some embodiments, opposite ends of the first diaphragm 30 and / or the second diaphragm 40 along their width direction a extend beyond the first electrode sheet 10, with the extended portions forming first extensions 31. The bonding region 60 includes two first sub-bonding regions 61, which are located at opposite ends of the first diaphragm 30 and / or the second diaphragm 40 along the width direction a. Each first sub-bonding region 61 is at least partially disposed on the corresponding first extension 31.

[0088] Specifically, the width direction a of the first electrode piece 10 and the second electrode piece 20 is in the same direction as the width direction a of the first diaphragm 30 and the second diaphragm 40. The opposite ends of the first diaphragm 30 and the second diaphragm 40 in the width direction a extend beyond the width of the first electrode piece 10, thereby forming a first extension portion 31 on the first diaphragm 30 and the second diaphragm 40, respectively.

[0089] The two first sub-bonding areas 61 are respectively arranged at opposite ends of the first diaphragm 30 and the second diaphragm 40 in the width direction a. When the first electrode 10 is located between the first diaphragm 30 and the second diaphragm 40, the first extension portion 31 of the first diaphragm 30 and the first extension portion 31 of the second diaphragm 40 are fitted together, so that the first diaphragm 30 and the second diaphragm 40 can be tightly bonded through the first sub-bonding areas 61 on their respective first extension portions 31.

[0090] Through the above structure, the first diaphragm 30 and the second diaphragm 40 can be bonded in the width direction a through the first sub-bonding area 61 on the first protruding portion 31, so that the first pole piece 10 can be better accommodated in the closed cavity 50 enclosed by the first diaphragm 30 and the second diaphragm 40.

[0091] In some embodiments, a coated region (not shown) and an uncoated region (not shown) are provided on the first electrode sheet 10. The coated region is provided with an active material layer, and the uncoated regions are provided on opposite sides of the coated region along the width direction a of the first electrode sheet 10. In the width direction a of the first diaphragm 30 or the second diaphragm 40, the width of each first sub-bonding region 61 is no greater than the sum of the widths of the corresponding first extension 31 and the uncoated region.

[0092] Specifically, the width of each first sub-bonding area 61 is not greater than the sum of the widths of the corresponding first protrusion 31 and the uncoated area. When the first diaphragm 30 and the second diaphragm 40 are bonded through the first sub-bonding area 61, while ensuring that the first protrusion 31 of the first diaphragm 30 and the second diaphragm 40 can be smoothly bonded, the probability of the first sub-bonding area 61 overlapping with the coated area on the first electrode 10 can be reduced, so that the first sub-bonding area 61 is only bonded to the first protrusion 31 of the first diaphragm 30 and the second diaphragm 40, or bonded to the first protrusion 31 and the uncoated area of ​​the first electrode 10.

[0093] Thus, through the above structure, the probability of the first sub-adhesive region 61 covering the coating region can be reduced, so that the contact area between the active material layer on the coating region and the first electrolyte is larger.

[0094] In addition, it can be understood that the second electrode 20 also has a coated area and an uncoated area, and the coated area is coated with an active material layer, and the uncoated area is formed on opposite sides of the coated area along the width direction a of the second electrode 20, which will not be elaborated here.

[0095] In some embodiments, the first pole piece 10 includes a main body 11 and a pole ear 12 , the coated area and the uncoated area are both located on the main body 11 , the pole ear 12 is connected to the uncoated area, and the pole ear 12 extends out of the closed cavity 50 along the width direction a of the first pole piece 10 .

[0096] Specifically, when the first pole piece 10 is disposed between the first diaphragm 30 and the second diaphragm 40, the first diaphragm 30 and the second diaphragm 40 are bonded to each other via the first sub-bonding region 61 on each first extension 31. At the same time, because the tab portion 12 of the first pole piece 10 extends out of the closed cavity 50 along the width direction a, the first sub-bonding region 61 overlaps with the tab portion 12 during bonding. The overlapping portion of the tab portion 12 and the first sub-bonding region 61 is bonded between the first diaphragm 30 and the second diaphragm 40, thereby improving the stability of the first pole piece 10 within the closed cavity 50.

[0097] It can be understood that the structure of the second pole piece 20 is the same as that of the first pole piece 10, that is, the second pole piece 20 also has a main body 11 and a tab portion 12, and the coated area and the uncoated area of ​​the second pole piece 20 are both formed on the main body 11, and the tab portion 12 of the second pole piece 20 is connected to the uncoated area of ​​the second pole piece 20. The tab portion 12 of the first pole piece 10 and the tab portion 12 of the second pole piece 20 extend to form the positive and negative connection terminals of the battery cell.

[0098] Through the above structure, during the bonding process of the first diaphragm 30 and the second diaphragm 40, the overlapping portion of the pole ear portion 12 of the first electrode piece 10 and the first sub-bonding area 61 is bonded simultaneously. On the one hand, it can improve the sealing of the closed cavity 50 and reduce the probability of the first electrolyte flowing out of the closed cavity 50 through the gap between the pole ear portion 12 and the first diaphragm 30 or the second diaphragm 40. On the other hand, it can improve the stability of the first electrode piece 10 in the closed cavity 50.

[0099] In some embodiments, opposite ends of the first diaphragm 30 and / or the second diaphragm 40 along their length direction b extend beyond the first pole piece 10, and the extending portions each form a second extension 32. The bonding area 60 includes two second sub-bonding areas 62, which are located at opposite ends of the first diaphragm 30 and / or the second diaphragm 40 along the length direction b, and each second sub-bonding area 62 is correspondingly disposed on the second extension 32.

[0100] Specifically, the length direction b of the first electrode piece 10 and the second electrode piece 20 is the same as the length direction b of the first diaphragm 30 and the second diaphragm 40. The opposite ends of the first diaphragm 30 and the second diaphragm 40 in the length direction b extend beyond the length of the first electrode piece 10, thereby forming a second extension portion 32 on the first diaphragm 30 and the second diaphragm 40, respectively.

[0101] The two second sub-bonding areas 62 are respectively arranged at opposite ends of the first diaphragm 30 and the second diaphragm 40 in the length direction b. When the first electrode 10 is located between the first diaphragm 30 and the second diaphragm 40, the second extension 32 of the first diaphragm 30 and the second extension 32 of the second diaphragm 40 are fitted together, so that the first diaphragm 30 and the second diaphragm 40 can be tightly bonded through the second sub-bonding areas 62 on their respective second extensions 32.

[0102] Further, taking the first diaphragm 30 as an example, the first sub-bonding area 61 is extended along the width direction a of the first diaphragm 30, and the second sub-bonding area 62 is extended along the length direction b of the first diaphragm 30, and the first sub-bonding area 61 and the second sub-bonding area 62 are connected end to end, thereby jointly enclosing a rectangular bonding area 60 that matches the outline of the first diaphragm 30.

[0103] Therefore, when the first diaphragm 30 and the second diaphragm 40 are bonded, the rectangular bonding area 60 tightly bonds the edges of the first diaphragm 30 and the second diaphragm 40, so that a closed cavity 50 is formed between the first diaphragm 30 and the second diaphragm 40, and the first electrode 10 and the first electrolyte are accommodated together in the closed cavity 50.

[0104] Through the above structure, the first diaphragm 30 and the second diaphragm 40 can be bonded in the length direction b through the second sub-bonding area 62 on the second extension portion 32, so that the first pole piece 10 can be better accommodated in the closed cavity 50 enclosed by the first diaphragm 30 and the second diaphragm 40.

[0105] In some embodiments, the air permeability of the first diaphragm 30 is ≥ 20000 s / 100 cc, and the ionic conductivity of the first diaphragm 30 is ≥ 0.1 mS / cm 2 .

[0106] Specifically, the air permeability of the first diaphragm 30 is set to ≥ 20000 s / 100 cc, and the ionic conductivity of the first diaphragm 30 is set to ≥ 0.1 mS / cm 2 .

[0107] Among them, the permeability of the first diaphragm 30 has a well-known meaning in the art. The permeability of the first diaphragm 30 is comprehensively affected by the internal pore structure of the first diaphragm 30, such as the porosity, pore size, pore shape and pore tortuosity. It indirectly reflects the degree of barrier of the first diaphragm 30 to other components in the electrolyte on both sides except active ions. It can be tested by methods known in the art. For example, the first diaphragm 30 is punched into small discs with a diameter of 50 mm, and the small discs are tested for permeability using a Wang Yan-type permeability meter (Asahi Seiko model EG01-55-1MR). The test pressure is controlled to 1.21 kPa, and the time (seconds, s) taken for 100 cc of gas (air) to pass through is used to obtain the permeability of the first diaphragm 30, which is expressed in s / 100 cc.

[0108] The ionic conductivity of the first diaphragm 30 refers to the ability of the first diaphragm 30 to conduct active ions (such as lithium ions), and can be tested specifically by the following method:

[0109] The first separator 30 was punched into small discs with a diameter of 16 mm. The thickness d was measured and recorded. The punched discs were assembled in the order of stainless steel sheet, separator, and stainless steel sheet. A small amount (10 μL) of electrolyte (solvent: EC:EMC, volume ratio: 3:7, lithium salt: 1 mol / L LiPF6) was added and encapsulated in a button cell. Electrochemical impedance spectroscopy (EIS) was used on a Solartron 1470E CellTest multi-channel electrochemical workstation. The test voltage was 10 mV and the test frequency range was 0.1 Hz to 100 kHz. Nyquist plots were plotted. The resulting Nyquist plots were analyzed using Zview software using the equivalent circuit curve fitting method. The intersection of the straight line and the horizontal axis was designated as R. Ionic conductivity was calculated using the formula λ = d / RS, where λ represents ionic conductivity, d represents separator thickness, R represents ionic resistance, and S represents the cross-sectional area of ​​the disc.

[0110] Therefore, the permeability of the first diaphragm 30 will affect the permeability of the electrolyte in the first diaphragm 30. If the permeability of the electrolyte in the first diaphragm 30 is too high, it means that the electrolyte is more likely to penetrate out of the closed cavity 50 through the first diaphragm 30, thereby reducing the sealing of the closed cavity 50 for the first electrolyte.

[0111] The ionic conductivity of the first diaphragm 30 will affect the conduction of lithium ions between the positive and negative electrodes. By limiting the range of the ionic conductivity of the first diaphragm 30, active ions can be smoothly conducted between the inside and outside of the closed cavity 50, thereby smoothly forming a circuit between the positive and negative electrodes.

[0112] As a preferred range, the ionic conductivity of the first diaphragm 30 can be set to ≥0.3 mS / cm 2 .

[0113] Therefore, setting the air permeability and ionic conductivity of the first separator 30 within the above ranges can further improve the sealing performance of the sealed cavity 50 for the first electrolyte, thereby allowing the first electrolyte to act more stably on the first electrode 10 in the sealed cavity 50 .

[0114] In addition, the first diaphragm 30 can be obtained by using a conventional porous PP, PE, or PI based membrane and performing a densification filling treatment on the porous structure. It can also be obtained by coating a dense membrane with PEO or PVDF materials. It can also be obtained by using an ion selective permeable membrane and performing a lithiation treatment. All of these can achieve the above-mentioned effects and will not be elaborated here.

[0115] In some embodiments, the air permeability of the second diaphragm 40 is ≥ 20000 s / 100 cc, and the ionic conductivity of the second diaphragm 40 is ≥ 0.1 mS / cm 2 .

[0116] Specifically, the air permeability of the second diaphragm 40 is set to ≥ 20000 s / 100 cc, and the ionic conductivity of the second diaphragm 40 is set to ≥ 0.1 mS / cm 2 .

[0117] The air permeability and ionic conductivity of the second diaphragm 40 can be tested using the same method as the air permeability and ionic conductivity of the first diaphragm 30 , which will not be described in detail here.

[0118] Since the closed cavity 50 is formed by the first diaphragm 30 and the second diaphragm 40, the permeability of the second diaphragm 40 will affect the permeability of the electrolyte in the second diaphragm 40. If the permeability of the electrolyte in the second diaphragm 40 is too high, it means that the electrolyte is more likely to penetrate out of the closed cavity 50 through the second diaphragm 40, which will also reduce the sealing of the closed cavity 50 for the first electrolyte.

[0119] The ionic conductivity of the second diaphragm 40 will affect the conduction of lithium ions between the positive and negative electrodes. By limiting the range of the ionic conductivity of the second diaphragm 40, active ions can be smoothly conducted between the inside and outside of the closed cavity 50, thereby smoothly forming a circuit between the positive and negative electrodes.

[0120] As a preferred range, the ionic conductivity of the second diaphragm 40 can be set to ≥0.3 mS / cm 2 .

[0121] Therefore, setting the air permeability and ionic conductivity of the second diaphragm 40 within the above ranges can further improve the sealing performance of the sealed cavity 50 for the first electrolyte, thereby allowing the first electrolyte to act more stably on the first electrode 10 in the sealed cavity 50 .

[0122] In addition, the second diaphragm 40 can also be obtained by using conventional porous PP, PE, or PI-based membranes, and performing a densification and filling treatment on the porous structure. It can also be obtained by coating a dense membrane with PEO or PVDF-type materials. It can also be obtained by using an ion-selective permeable membrane after a lithiation treatment. All of these can achieve the above-mentioned effects, which will not be elaborated here.

[0123] In some embodiments, one of the first electrode 10 and the second electrode 20 is a positive electrode, and the other is a negative electrode.

[0124] Specifically, the first electrode 10 can be configured as a positive electrode, and the second electrode 20 can be configured as a negative electrode. In this case, the positive electrode and the positive electrolyte are contained in the closed cavity 50, and the negative electrode and the negative electrolyte are located outside the closed cavity 50.

[0125] Of course, the first electrode 10 can also be set as a negative electrode, and the second electrode 20 can be set as a positive electrode. In this case, the negative electrode and the negative electrolyte are contained in the closed cavity 50, and the positive electrode and the positive electrolyte are located outside the closed cavity 50.

[0126] Therefore, the positions of the positive electrode sheet and the negative electrode sheet relative to the closed cavity 50 can be adjusted more flexibly according to the requirements of actual applications, so that the structure of the battery cell finally formed is more stable.

[0127] Based on the same concept as the above-mentioned electrode assembly 100, the present application also provides a battery cell, including a first electrolyte, a second electrolyte and the above-mentioned electrode assembly 100, the first electrolyte is filled in the closed cavity 50, and the second electrolyte is filled between the second electrode plate 20 and the first diaphragm 30.

[0128] In some embodiments, the first electrolyte and the second electrolyte have different compositions. Further, the first electrolyte and the second electrolyte have different contents.

[0129] Specifically, the first electrolyte and the second electrolyte have the same or different compositions, and the first electrolyte and the second electrolyte have the same or different contents. In some embodiments, the first electrolyte and the second electrolyte have different compositions, and further, the first electrolyte and the second electrolyte have different contents.

[0130] The first electrolyte and the second electrolyte have different compositions, including but not limited to different types of electrolyte salts / solvents / additives. The first electrolyte and the second electrolyte have different contents, including but not limited to different contents of electrolyte salts / solvents / additives.

[0131] The specific composition and content of the first electrolyte and the second electrolyte can be set according to the actual materials of the first electrode 10 and the second electrode 20, so that the components of the first electrolyte can better promote the first electrode 10, and the components of the second electrolyte can better promote the second electrode 20, thereby improving the reaction efficiency.

[0132] Through the above structure, the first electrolyte and the first electrode 10 can be better accommodated in the closed cavity 50, and the second electrolyte and the second electrode 20 can be isolated outside the closed cavity 50, reducing the impact of the first electrolyte on the second electrode 20 and the impact of the second electrolyte on the first electrode 10.

[0133] In some embodiments, the first electrolyte is a gel electrolyte. In some embodiments, the second electrolyte is a gel electrolyte.

[0134] Specifically, a gel electrolyte refers to an electrolyte in a gel-like state. Setting both the first electrolyte and the second electrolyte as gel electrolytes can effectively reduce the fluidity of the electrolytes, further reducing the probability of mixing between the first electrolyte and the second electrolyte, allowing the first electrolyte to be more stably contained within the closed cavity 50.

[0135] Through the above structure, the probability of mixing between the first electrolyte and the second electrolyte can be further reduced based on the inherent characteristics of the electrolyte, thereby reducing the probability of the first electrolyte affecting the second electrode 20 and the probability of the second electrolyte affecting the first electrode 10.

[0136] In some embodiments, the first electrolyte includes a base electrolyte and a polymer matrix; the polymer matrix includes a homopolymer or a copolymer of a first monomer unit, and the first monomer unit includes at least one of an acrylic monomer unit and an acrylate monomer unit.

[0137] In some embodiments, the second electrolyte includes a base electrolyte and a polymer matrix; the polymer matrix includes a homopolymer or a copolymer of a first monomer unit, and the first monomer unit includes at least one of an acrylic monomer unit and an acrylate monomer unit.

[0138] Specifically, the first monomer unit can undergo a polymerization reaction under the action of an initiator to form a gel, so that at least one of the first electrolyte and the second electrolyte can smoothly form a gel electrolyte.

[0139] The first monomer unit includes at least one of an acrylic acid monomer unit and an acrylic acid ester monomer unit. The acrylic acid monomer unit may specifically include, but is not limited to, one or more of acrylic acid and methacrylic acid. The acrylic acid ester monomer unit may specifically include, but is not limited to, methyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, butyl acrylate, isodecyl acrylate, isooctyl acrylate, lauryl acrylate, isobornyl acrylate, isobornyl methacrylate, ethoxylated acrylate. Ethoxyethyl acrylate, cyanoacrylate, caprolactone acrylate, 2-phenoxyethyl acrylate, tetrahydrofuran acrylate, ethoxylated tetrahydrofuran acrylate, cyclotrimethylolpropane acrylate, 2-carboxyethyl acrylate, cyclohexyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, 1, 4-Butanediol diacrylate, 1,4-Butanediol dimethacrylate, 1,3-Butanediol diacrylate, 1,3-Butanediol dimethacrylate, 1,6-Hexanediol diacrylate, 1,6-Hexanediol dimethacrylate, Dipropylene glycol diacrylate, Dipropylene glycol dimethacrylate, Tripropylene glycol diacrylate, Tripropylene glycol dimethacrylate, Neopentyl glycol diacrylate, Neopentyl glycol dimethacrylate, 2-(Propoxy)neopentyl glycol diacrylate, Polyethylene glycol diacrylate, Polyethylene glycol di One or more of methacrylate, polypropylene glycol dimethacrylate, polycyclohexyl acrylate, methoxy polyethylene glycol acrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, methoxy polyethylene glycol methacrylate, pentaerythritol triacrylate, propoxylated glycerol triacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, di(trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, 4(ethoxy)pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

[0140] The initiator may include, but is not limited to, a peroxide initiator and / or an azo initiator, for example, one or more of acyl peroxides (benzoyl peroxide, lauroyl peroxide), persulfates (ammonium persulfate), and azo initiators (azobisisobutyronitrile, azobisisoheptonitrile).

[0141] As a result, at least one of the first electrolyte and the second electrolyte can smoothly form a gel electrolyte, thereby reducing the probability of mixing between the first electrolyte and the second electrolyte and improving reaction efficiency.

[0142] In some embodiments, the polymer matrix also includes a homopolymer or copolymer of a second monomer unit, and the second monomer unit includes one or more of an ethylenically unsaturated carbonate monomer unit, an ethylenically unsaturated sulfate monomer unit, an ethylenically unsaturated sulfonate monomer unit, an ethylenically unsaturated sulfone monomer unit, an ethylenically unsaturated carboxylate monomer unit, an ethylenically unsaturated phosphate monomer unit, an ethylenically unsaturated nitrile monomer unit, and an ethylenically unsaturated ether monomer unit.

[0143] In some embodiments, the ethylenically unsaturated carbonate monomer units include one or more of vinylene carbonate (VC), vinylethylene carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, and chloroethylene carbonate.

[0144] In some embodiments, the ethylenically unsaturated sulfate monomer units include one or more of vinyl sulfite, vinyl sulfite, 4-methyl vinyl sulfate, and 4-ethyl vinyl sulfate.

[0145] In some embodiments, the ethylenically unsaturated sulfonate monomer units include one or more of 1,3-propylene sultone, allyl p-toluenesulfonate, 2,2-difluoroethylene, 4-methylbenzenesulfonate, and methylenedisulfonate.

[0146] In some embodiments, the ethylenically unsaturated phosphate monomer units include one or more of dimethyl vinyl phosphate, diethyl vinyl phosphate, diethyl propenyl phosphate, diethyl butenyl phosphate, diethyl 1-buten-2-yl phosphonate, diethyl ethynyl phosphate, vinyl trifluoromethyl phosphate, vinyl-1-trifluoroethyl phosphate, diethyl fluorovinyl phosphate, and 1-trifluoropropenylethyl phosphate.

[0147] In some embodiments, the ethylenically unsaturated carboxylic acid ester monomer units include vinyl acetate.

[0148] In some embodiments, the ethylenically unsaturated sulfone monomer units include one or more of methyl vinyl sulfone, ethyl vinyl sulfone, sulfolene, sulfolane, and ethylene sulfoxide.

[0149] In some embodiments, the ethylenically unsaturated nitrile monomer units include one or more of acrylonitrile, succinonitrile, glutaronitrile, and adiponitrile.

[0150] In some embodiments, the ethylenically unsaturated ether monomer units include one or more of 1,3-dioxolane, ethylene oxide, 1,2-propylene oxide, 4-methyl-1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, ethylene glycol diglycidyl ether, and triethylene glycol divinyl ether.

[0151] Specifically, during the preparation of the positive electrode electrolyte and the negative electrode electrolyte, the mass ratio between the basic electrolyte, the first monomer unit, the second monomer unit and the initiator can be set to basic electrolyte: first monomer unit: second monomer unit: initiator = (60%-98%): (1%-20%): (0%-20%): (0.1%-1%).

[0152] The basic electrolyte is composed of an electrolyte salt and a solvent. The electrolyte salt is a lithium salt or a sodium salt. The lithium salt includes but is not limited to one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorophosphate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate. The sodium salt includes but is not limited to one or more of NaPF6, NaClO4, NaBCl4, NaSO3CF3, and Na(CH3)C6H4SO3. The concentration is 0.3 to 4 mol / L, and the solvent includes but is not limited to one or more of ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0153] The above mass ratio range can make the first electrolyte and / or the second electrolyte gel better and make their structure more stable.

[0154] Specifically, one of the first electrolyte and the second electrolyte is a positive electrode electrolyte, and the other is a negative electrode electrolyte.

[0155] In some embodiments, the battery cell further includes a shell, and the electrode assembly 100 is accommodated inside the shell.

[0156] The shell can provide a closed protective space for the electrode assembly 100 so that the electrode assembly 100 can perform an electrochemical reaction more stably inside the shell.

[0157] Based on the same concept as the above-mentioned battery cell, the present application also provides a battery, including the above-mentioned battery cell.

[0158] Based on the same concept as the above-mentioned battery, the present application also provides an electrical device, including the above-mentioned battery.

[0159] As shown in FIG4 and FIG5 , based on the same concept as the above-mentioned battery cell, the present application also provides a method for preparing a battery cell, comprising the following steps:

[0160] S10 : coating a first electrolyte on the first surface 13 of the first electrode 10 .

[0161] Specifically, the first electrolyte can be applied to the first surface 13 of the first electrode sheet 10 by roller immersion. Specifically, the first electrolyte is placed in a container, and the first electrode sheet 10 is conveyed via conveyor rollers, with the lower end of one of the conveyor rollers immersed in the container. As the first electrode sheet 10 passes over the conveyor rollers, the first surface 13 of the electrode sheet faces downward and passes through the first electrolyte in the container, thereby smoothly coating the first electrolyte on the first surface 13 of the first electrode sheet 10.

[0162] In the above manner, the first electrolyte can be coated on the first surface 13 simultaneously during the transportation process of the first electrode 10 , thereby improving production efficiency.

[0163] S20 : ​​The second separator 40 is laminated on one side of the first surface 13 coated with the first electrolyte.

[0164] After the first electrolyte coating is completed, the second separator 40 is laminated on the first surface 13 of the first electrode by a conveyor roller so that the first electrolyte is located between the first surface 13 and the second separator 40 .

[0165] S30 : stacking the first diaphragm 30 on the second surface 14 of the first electrode 10 opposite to the first surface 13 , and bonding the first diaphragm 30 to the second diaphragm 40 to form a closed cavity 50 , so that the first electrode 10 is accommodated in the closed cavity 50 .

[0166] The first diaphragm 30 is stacked on one side of the second surface 14 of the first electrode 10. By applying pressure, the first diaphragm 30 and the second diaphragm 40 are bonded through the bonding area 60, thereby enclosing a closed cavity 50 between the first diaphragm 30 and the second diaphragm 40, and the first electrode 10 and the first electrolyte are accommodated in the closed cavity 50.

[0167] S40 : stacking the second pole piece 20 on the side of the first diaphragm 30 away from the first pole piece 10 .

[0168] The second electrode sheet 20 is transported by a transport roller, and during the transport process, the second electrode sheet 20 is stacked on a side of the first diaphragm 30 facing away from the first electrode sheet 10 .

[0169] S50 : Winding the stacked second separator 40 , the first electrode sheet 10 , the first separator 30 , and the second electrode sheet 20 to form the electrode assembly 100 .

[0170] S60 : placing the electrode assembly 100 into the housing, and filling the second electrolyte between the second electrode sheet 20 and the first separator 30 .

[0171] After the electrode assembly 100 is placed in the shell, since the first electrode plate 10 and the first electrolyte are sealed in the closed cavity 50, the second electrolyte is filled into the shell at this time, so that the second electrolyte can be filled between the second electrode plate 20 and the first diaphragm 30, and is isolated from the first electrolyte in the closed cavity 50 without affecting each other.

[0172] In some embodiments, after step S10, the method further includes the following steps:

[0173] S12: The first electrolyte is gelled to obtain a gel electrolyte.

[0174] Specifically, during the gelation process of the first electrolyte, ultraviolet irradiation or heat treatment can be used to gel the first electrolyte. Ultraviolet irradiation can cause the first electrolyte coated on the first surface 13 to gel more quickly, reducing the probability of the first electrolyte dripping from the first surface 13, so that the first electrolyte can be more stably contained in the closed cavity 50.

[0175] In some embodiments, before step S30, the method further includes the following steps:

[0176] S26 : spraying the first electrolyte onto the second surface 14 of the first electrode 10 opposite to the first surface 13 .

[0177] After the first electrolyte is coated on the first surface 13 , the degree of wetting of the first electrolyte on the first electrode piece 10 can be detected and determined, thereby determining the coating amount of the first electrolyte on the first electrode piece 10 .

[0178] When the coating amount of the first electrolyte on the first electrode piece 10 is small, the electrolyte can be replenished by spraying the first electrolyte onto the second surface 14 so that the first electrolyte fully infiltrates the first electrode piece 10 .

[0179] In some embodiments, after step S26, the method further includes the following steps:

[0180] S28: The first electrolyte on the second surface 14 is irradiated with ultraviolet rays to gel the first electrolyte.

[0181] Ultraviolet irradiation can cause the first electrolyte on the second surface 14 to gel more quickly, thereby reducing the probability of the first electrolyte dripping from the second surface 14 , so that the first electrolyte can be more stably accommodated in the closed cavity 50 .

[0182] In some embodiments, after step S60, the method further includes the following steps:

[0183] S70: The second electrolyte is gelled to obtain a gel electrolyte.

[0184] Specifically, during the gelation process of the second electrolyte, the second electrolyte may be gelled by ultraviolet irradiation or heating.

[0185] By irradiating with ultraviolet rays, the second electrolyte between the second electrode 20 and the first diaphragm 30 can be fully gelled. On the one hand, the second electrolyte is more stably filled between the second electrode 20 and the first diaphragm 30. On the other hand, the probability of mixing between the first electrolyte and the second electrolyte is further reduced.

[0186] In order to test and verify the battery cells provided in this application, positive and negative electrode sheets, a first separator, a second separator, and an electrolyte were prepared respectively according to the following methods to form comparative examples and embodiments.

[0187] Specifically, the preparation process of the embodiment is as follows:

[0188] (1) Preparation of positive electrode

[0189] NCM811(LiNi 0.8 Co 0.1 Mn 0.1 O2) is thoroughly stirred and mixed with conductive agent acetylene black and binder polyvinylidene fluoride (PVDF) in an N-methylpyrrolidone solvent system in a weight ratio of 94:3:3, and then coated on aluminum foil, dried, and cold pressed to obtain a positive electrode sheet. The width of the active material is 87 mm and the length of the tab is 16 mm.

[0190] (2) Preparation of negative electrode sheet

[0191] Graphite, SBR, and conductive carbon were thoroughly stirred and mixed in deionized water in a weight ratio of 94:3:3, and then coated on copper foil and cold pressed to obtain a negative electrode sheet. The width of the active material was 93 mm and the length of the tab was 13 mm.

[0192] (3) Preparation of diaphragm

[0193] In the embodiment of the present application, the first and second diaphragms provided in the present application are prepared by dipping a common PE diaphragm in a treatment solution and then UV curing. The first and second diaphragms are used as the diaphragms of Examples 1 and 2. After the treatment, the air permeability of the diaphragm is 26469s / 100cc and the conductivity is 0.56mS / cm 2 The first diaphragm and the second diaphragm are cut into 108mm widths, and hot melt adhesive with a width of 5mm and a thickness of 15um is prepared on both sides of the width of the first diaphragm and the second diaphragm. The hot melt adhesive can be hot-pressed and bonded at 160 degrees Celsius.

[0194] The components of the dip coating solution include EC, EMC, LiPF6, ethoxylated trimethylolpropane triacrylate, vinyl acetate, and AIBN, and the mass ratio of EC:EMC:LIPF6:triethylene glycol dimethacrylate:vinyl acetate:benzoyl peroxide (BPO) is 20:30:19.5:10:20:0.5. The curing process is to use ultraviolet light with a wavelength of 365 nm and a power of 800 mW / cm 2 , processing time is 2s

[0195] (4) Preparation of electrolyte

[0196] Positive electrolyte: LiFSI was dissolved in dimethyl sulfoxide to prepare 1M / L electrolyte M;

[0197] Positive electrode gel electrolyte (first electrolyte): electrolyte M: polyethylene glycol dimethacrylate: VC = 80%: 10%: 10% by mass, and 0.4% by mass of azobisisobutyronitrile (AIBN) was added to the above mixture, which was recorded as electrolyte M-GEL;

[0198] Anode electrolyte: EC:EMC:DMC was mixed in a volume ratio of 1:1:1, and LiFSI was added to prepare electrolyte N with a lithium salt concentration of 1M / L;

[0199] The negative electrode side gel electrolyte (second electrolyte) was mixed in a mass ratio of electrolyte N: polyethylene glycol dimethacrylate: VC = 80%: 10%: 10%, and then AIBN was added at a mass fraction of 0.4% of the total mixed solution mass, which was recorded as electrolyte N-GEL.

[0200] Furthermore, the preparation process of the comparative example is as follows:

[0201] (1) Preparation of positive electrode

[0202] NCM811(LiNi 0.8 Co 0.1 Mn 0.1O2) is thoroughly stirred and mixed with conductive agent acetylene black and binder polyvinylidene fluoride (PVDF) in an N-methylpyrrolidone solvent system in a weight ratio of 94:3:3, and then coated on aluminum foil, dried, and cold pressed to obtain a positive electrode sheet. The width of the active material is 87 mm and the length of the tab is 16 mm.

[0203] (2) Preparation of negative electrode sheet

[0204] Graphite, SBR, and conductive carbon were thoroughly stirred and mixed in deionized water in a weight ratio of 94:3:3, and then coated on copper foil and cold pressed to obtain a negative electrode sheet. The width of the active material was 93 mm and the length of the tab was 13 mm.

[0205] (3) Preparation of diaphragm

[0206] The traditional PE membrane is used as the base membrane, wherein the thickness of the PE membrane is 12 μm, the air permeability is 148 s / 100 cc, and the ionic conductivity is 0.62 mS / cm 2 .

[0207] (4) Preparation of electrolyte

[0208] Positive electrolyte: LiFSI was dissolved in dimethyl sulfoxide to prepare 1M / L electrolyte M;

[0209] Positive electrode gel electrolyte (first electrolyte): electrolyte M: polyethylene glycol dimethacrylate: VC = 80%: 10%: 10% by mass, and 0.4% by mass of azobisisobutyronitrile (AIBN) was added to the above mixture, which was recorded as electrolyte M-GEL;

[0210] Anode electrolyte: EC:EMC:DMC was mixed in a volume ratio of 1:1:1, and LiFSI was added to prepare electrolyte N with a lithium salt concentration of 1M / L;

[0211] The negative electrode side gel electrolyte (second electrolyte) was mixed in a mass ratio of electrolyte N: polyethylene glycol dimethacrylate: VC = 80%: 10%: 10%, and then AIBN was added at a mass fraction of 0.4% of the total mixed solution mass, which was recorded as electrolyte N-GEL.

[0212] Furthermore, a life test is carried out under a constant temperature environment of 25°C. The specific process is: first stand for 5 minutes, discharge to 2.8V at 0.5C (1500mA), stand for 5 minutes, charge to 4.3V at 1 / 3C, and then charge at a constant voltage at 4.3V to a current ≤100mA. Stand for 5 minutes, then discharge to 2.8V at 1 / 3C. The discharge capacity at this time is the initial discharge capacity, recorded as D0. Subsequently, according to the above process, a cycle test is carried out in the range of 2.8~4.3V, and the capacity value Dn (n=1, 2, 3...) is recorded every week. When the capacity Dn<=80%D0, the cycle number n is recorded as the cycle life.

[0213] Among them, comparative example 1:

[0214] The separator used the aforementioned basic separator, a 12μm-thick PE separator. The negative electrode sheet was coated with the electrolyte N-GEL and cured by UV irradiation, but no separator encapsulation was performed. The wound electrode assembly was then placed in a casing and injected with the electrolyte M-GEL. The battery cells were then insulated at 70°C for 5 hours to allow the M-GEL electrolyte to cure before testing.

[0215] Comparative Example 2:

[0216] The diaphragm used is a gel-filled 12um diaphragm (mentioned above). After treatment, the permeability of the diaphragm is 26469s / 100cc and the conductivity is 0.56mS / cm 2 The negative electrode sheet is coated with electrolyte N-GEL and cured by UV irradiation, but no separator is encapsulated. The wound electrode assembly is then placed in a casing and injected with electrolyte M-GEL. The battery cell is then heated at 70°C for 5 hours to cure the electrolyte M-GEL before testing.

[0217] Comparative Example 3:

[0218] The diaphragm uses a gel-filled 12um diaphragm (mentioned above). After treatment, the permeability of the diaphragm is 26469s / 100cc and the conductivity is 0.56mS / cm 2 Electrolyte N was applied to the negative electrode sheet without UV curing and without separator packaging. The electrode assembly was then wound and placed in a housing, where electrolyte M was injected and tested.

[0219] Example 1:

[0220] The diaphragm is a treated diaphragm with a bonding area. That is, the diaphragm uses a gel-filled 12 μm diaphragm (mentioned above) and has a bonding area thereon. After the treatment, the air permeability of the diaphragm is 26469 s / 100 cc and the conductivity is 0.56 mS / cm 2 . As a specific implementation method, low-melting-point PP glue (melting temperature 100°C) can be used in the bonding area. The electrolyte N-GEL is coated on the negative electrode sheet, cured by ultraviolet irradiation, and then wound. During the winding process, the first diaphragm and the second diaphragm are bonded by low-melting-point PP glue and enclosed to form a closed cavity. The wound electrode assembly is placed in the shell and the electrolyte M-GEL is injected. Then, the battery cell is kept at 70°C for 5 hours to achieve the curing of the electrolyte M-GEL, and then tested.

[0221] Example 2:

[0222] The diaphragm uses a gel-filled 12um diaphragm (mentioned above) and sets a bonding area on the diaphragm. After the treatment, the air permeability of the diaphragm is 26469s / 100cc and the conductivity is 0.56mS / cm 2 As a specific embodiment, the bonding area can use low-melting point PP glue (melting temperature 100°C). Electrolyte N is coated on the negative electrode sheet, and it is not cured by ultraviolet irradiation, and then wound. During the winding process, the first diaphragm and the second diaphragm are bonded by PP glue and enclosed to form a closed cavity. The wound electrode assembly is placed in the shell, injected with electrolyte M, and then tested.

[0223] It can be clearly seen from the test data that the cycle life of the battery cell provided in this application is significantly improved.

[0224] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0225] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. An electrode assembly, the electrode assembly being a wound electrode assembly and comprising: First pole piece; a second pole piece, stacked with the first pole piece; a first diaphragm, sandwiched between the first pole piece and the second pole piece; and a second diaphragm, stacked on a side of the first pole piece facing away from the first diaphragm; A closed cavity for accommodating the first pole piece is formed between the first diaphragm and the second diaphragm.

2. The electrode assembly according to claim 1, wherein, The first diaphragm and / or the second diaphragm is provided with a bonding area, the bonding area is arranged around the edge of the first diaphragm and / or the second diaphragm to form a closed ring structure; The first diaphragm and the second diaphragm are bonded to each other through the bonding area and enclosed to form the closed cavity.

3. The electrode assembly according to claim 2, wherein, Two opposite ends of the first diaphragm and / or the second diaphragm along their width direction respectively extend beyond the first pole piece, and the extending portions respectively form first extension portions; The bonding area includes two first sub-bonding areas, which are located at both ends of the first diaphragm and / or the second diaphragm in the width direction, and each of the first sub-bonding areas is at least partially correspondingly arranged on the first protruding portion.

4. The electrode assembly according to claim 3, wherein, The first electrode sheet is provided with a coating area and an uncoating area, the coating area is provided with an active material layer, and the uncoating area is provided on opposite sides of the coating area along the width direction of the first electrode sheet; In the width direction of the first diaphragm or the second diaphragm, the width of each of the first sub-adhesive regions is no greater than the sum of the widths of the corresponding first protruding portion and the uncoated region.

5. The electrode assembly according to claim 4, wherein, The first pole piece includes a main body and a pole ear. The coated area and the uncoated area are both located on the main body. The pole ear is connected to the uncoated area and extends out of the closed cavity along the width direction of the first pole piece.

6. The electrode assembly according to any one of claims 3-5, wherein, Two opposite ends of the first diaphragm and / or the second diaphragm along their own length direction respectively extend beyond the first pole piece, and the extending portions respectively form second extension portions; The bonding area includes two second sub-bonding areas, the two second sub-bonding areas are located at both ends of the first diaphragm and / or the second diaphragm in the length direction, and each second sub-bonding area is correspondingly arranged on the second protruding portion.

7. The electrode assembly according to any one of claims 1-6, wherein, The air permeability of the first separator is ≥20,000 s / 100 cc, and the ionic conductivity of the first separator is ≥0.1 mS / cm 2 .

8. The electrode assembly according to any one of claims 1-7, wherein, The air permeability of the second separator is ≥20,000 s / 100 cc, and the ionic conductivity of the second separator is ≥0.1 mS / cm 2 .

9. A battery cell comprising a first electrolyte, a second electrolyte, and the electrode assembly according to any one of claims 1 to 8, wherein the first electrolyte is filled in the closed cavity, and the second electrolyte is filled between the second electrode sheet and the first separator.

10. The battery cell according to claim 9, wherein, The first electrolyte and the second electrolyte have different compositions.

11. The battery cell according to claim 9 or 10, wherein, The first electrolyte and the second electrolyte have different contents.

12. The battery cell according to any one of claims 9-11, wherein, The first electrolyte is a gel electrolyte.

13. The battery cell according to any one of claims 9-12, wherein, The second electrolyte is a gel electrolyte.

14. The battery cell according to claim 12 or 13, wherein, The first electrolyte includes a basic electrolyte and a polymer matrix; the polymer matrix includes a homopolymer or a copolymer of a first monomer unit, and the first monomer unit includes at least one of an acrylic monomer unit and an acrylic ester monomer unit.

15. The battery cell according to any one of claims 12-14, wherein, The second electrolyte includes a base electrolyte and a polymer matrix; the polymer matrix includes a homopolymer or copolymer of a first monomer unit, and the first monomer unit includes at least one of an acrylic monomer unit and an acrylate monomer unit.

16. The battery cell according to claim 14 or 15, wherein, The polymer matrix further includes a homopolymer or copolymer of a second monomer unit, and the second monomer unit includes one or more of an ethylenically unsaturated carbonate monomer unit, an ethylenically unsaturated sulfate monomer unit, an ethylenically unsaturated sulfonate monomer unit, an ethylenically unsaturated sulfone monomer unit, an ethylenically unsaturated carboxylate unit, an ethylenically unsaturated phosphate monomer unit, an ethylenically unsaturated nitrile monomer unit, and an ethylenically unsaturated ether monomer unit.

17. The battery cell according to any one of claims 9-16, wherein, The battery cell further includes a housing, and the electrode assembly is disposed inside the housing.

18. A battery, comprising the battery cell according to any one of claims 9-17.

19. An electrical device, comprising the battery according to claim 18.

20. A method for preparing a battery cell, comprising the following steps: Coating a first electrolyte on a first surface of a first electrode sheet; Stacking a second separator on one side of the first surface coated with the first electrolyte; Stacking a first separator on one side of a second surface of the first electrode sheet opposite to the first surface, and Bonding with the second separator to form a closed cavity, and accommodating the first electrode sheet in the closed cavity; Stacking a second electrode sheet on one side of the first separator facing away from the first electrode sheet; Winding the stacked second separator, the first electrode sheet, the first separator, and the second electrode sheet to form an electrode assembly; Placing the electrode assembly into a housing, and filling a second electrolyte between the second electrode sheet and the first separator.

21. The method for preparing a battery cell according to claim 20, wherein, After the step of coating the first electrolyte on the first surface of the first electrode sheet, the method further includes the step of: Gelatinizing the first electrolyte to obtain a gel electrolyte.

22. The method for preparing a battery cell according to claim 21, wherein, After the step of placing the electrode assembly into the housing and filling the second electrolyte between the second electrode sheet and the first separator, the method further includes the step of: Gelatinizing the second electrolyte to obtain a gel electrolyte.

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