Electrode assembly, battery cell, battery and electrical device

Abstract

The present application relates to an electrode assembly, a battery cell, a battery and an electrical device. The electrode assembly comprises at least one positive electrode sheet; at least one negative electrode sheet which is alternately stacked with the positive electrode sheet; and a separator sandwiched between every two adjacent positive electrode sheet and negative electrode sheet, wherein a first accommodating cavity is formed between the positive electrode sheet and the separator adjacent thereto, a second accommodating cavity is formed between the negative electrode sheet and the separator adjacent thereto, and the first accommodating cavity and the second accommodating cavity are independently arranged and are not communicated with each other. According to the present application, the first accommodating cavity and the second accommodating cavity are independently arranged, the first accommodating cavity is filled with a first electrolyte, and the second accommodating cavity is filled with a second electrolyte, so that the first electrolyte and the second electrolyte are arranged in separate partitions, and do not affect each other, thereby effectively reducing the effect of the first electrolyte on a negative electrode and the effect of the second electrolyte on a positive electrode, and improving the battery performance.

Description

Electrode assembly, battery cell, battery and power-consuming device

[0001] Related applications

[0002] This application claims priority to Chinese patent application number 2024201930810, filed on January 25, 2024, entitled “An electrode assembly, a battery cell, 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, 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, a battery, and an electrical device.

[0007] In a first aspect, the present application provides an electrode assembly, comprising:

[0008] At least one positive electrode;

[0009] At least one negative electrode sheet is stacked alternately with each positive electrode sheet; and

[0010] A diaphragm is sandwiched between each two adjacent positive and negative electrode sheets;

[0011] A first accommodating cavity is provided between the positive electrode sheet and the adjacent diaphragm, and a second accommodating cavity is provided between the negative electrode sheet and the adjacent diaphragm. The first accommodating cavity and the second accommodating cavity are independently provided and not connected to each other.

[0012] Through the above structure, the first electrolyte is accommodated in the first accommodating cavity, and the second electrolyte is accommodated in the second accommodating cavity, so that other components except active ions do not mix and diffuse between the first electrolyte and the second electrolyte, which can reduce the probability of some components in the first electrolyte having an adverse effect on the negative electrode sheet, and reduce the probability of some components in the second electrolyte having an adverse effect on the positive electrode sheet, thereby improving the overall performance of the battery.

[0013] In some embodiments, the first accommodating cavity has a first opening, the second accommodating cavity has a second opening, and an opening direction of the first opening is opposite to an opening direction of the second opening.

[0014] By setting the opening direction of the first opening of the first accommodating chamber and the opening direction of the second opening of the second accommodating chamber in opposite directions, the first electrolyte and the second electrolyte can be filled into the first accommodating chamber and the second accommodating chamber respectively from different directions, thereby reducing the probability of mixing between the first electrolyte and the second electrolyte.

[0015] In some embodiments, the diaphragm is a continuous diaphragm and has a Z-shaped structure. The positive electrode sheet is located between each two adjacent layers of the diaphragm, and the negative electrode sheet is located between each two adjacent layers of the diaphragm. A first bonding area is provided on the diaphragm, and the first bonding area is used to bond each two adjacent layers of the diaphragm.

[0016] Through the above structure, the diaphragm is folded and wound between each two adjacent positive and negative electrode sheets, and after the diaphragm is folded, each two adjacent layers of the diaphragm are bonded through their own first bonding area, so that a first accommodating cavity is smoothly formed between the positive electrode sheet and the adjacent diaphragm, and a second accommodating cavity is smoothly formed between the negative electrode sheet and the adjacent diaphragm, thereby realizing 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 positive electrode or negative electrode.

[0017] In some embodiments, the first bonding area is located on two opposite sides of the membrane in the thickness direction, and the first bonding area on each side surface includes a first adhesive strip respectively arranged at both ends of the membrane along the width direction of the membrane, and the first adhesive strip extends along the length direction of the membrane.

[0018] By setting a first rubber strip extending along the length direction of the diaphragm, when the diaphragm is folded and set between the positive electrode sheet and the negative electrode sheet, the first rubber strip can bond the two ends in the width direction between each adjacent layer of diaphragm, so that the diaphragm forms a pocket-like structure with one end open, so as to smoothly form the first accommodating cavity and the second accommodating cavity.

[0019] In some embodiments, the separator has a larger width than the adjacent positive or negative electrode sheet, and the area where the separator extends beyond the positive or negative electrode sheet is set as the first bonding area.

[0020] By forming the first bonding area in the area where the separator extends beyond the positive electrode sheet or the negative electrode sheet, smooth bonding between each two adjacent separator layers can be achieved, and the contact area between the positive electrode sheet and the negative electrode sheet and the first electrolyte and the second electrolyte respectively can be increased.

[0021] In some embodiments, the positive electrode sheet and the negative electrode sheet each include a body and a tab protruding from at least one side of the body, the body being located between two adjacent layers of separators, and the tab extending outside the separators;

[0022] The first adhesive strip at at least one end in the width direction of the diaphragm is used to bond two adjacent diaphragm layers and the tabs between the two adjacent diaphragm layers.

[0023] Thus, by simultaneously bonding each two adjacent layers of diaphragms and the tabs located between the two adjacent layers of diaphragms through the first adhesive strip in the first bonding area, the sealing of the first and second accommodating cavities can be improved, and the probability of electrolyte flowing out through the gap between the tabs and the diaphragms can be reduced.

[0024] In some embodiments, the separator includes a plurality of stacked sub-separators, the positive electrode sheet is located between every two adjacent sub-separators, and the negative electrode sheet is located between every two adjacent sub-separators.

[0025] Compared to a folded continuous membrane, the spacing between adjacent sub-membranes in a stacked arrangement is fixed. When a continuous membrane is folded, the spacing at the corners of the Z-fold is smaller, resulting in higher electrolyte osmotic pressure there. However, the spacing between adjacent sub-membranes is constant, and the electrolyte osmotic pressure at each location is the same, resulting in more uniform electrolyte penetration.

[0026] In some embodiments, the positive electrode sheet and the negative electrode sheet are respectively provided with a second bonding area in a first direction, and are respectively provided with a third bonding area in a second direction intersecting the first direction;

[0027] The second bonding area and the third bonding area are respectively bonded to adjacent sub-diaphragms to form a first accommodation cavity and a second accommodation cavity respectively.

[0028] By setting the second bonding area and the third bonding area, each positive electrode sheet and the adjacent sub-diaphragm can be bonded to each other and enclosed to form a first accommodating cavity to accommodate the first electrolyte; and each negative electrode sheet and the adjacent sub-diaphragm can be bonded to each other and enclosed to form a second accommodating cavity to accommodate the second electrolyte.

[0029] In some embodiments, the second adhesive region includes a second adhesive strip extending along the first direction.

[0030] In some embodiments, the third bonding area includes a third adhesive strip extending along the second direction.

[0031] In some embodiments, the positive electrode sheet and the negative electrode sheet are respectively provided with a second bonding area in a first direction, and each sub-separator is provided with a fourth bonding area in a second direction intersecting with the first direction;

[0032] The second bonding area and the fourth bonding area are respectively bonded to adjacent sub-diaphragms to form a first accommodating cavity and a second accommodating cavity respectively.

[0033] The second bonding area is set on the positive electrode sheet and the negative electrode sheet, and the fourth bonding area is set on each sub-membrane. On the premise that the positive electrode sheet and the adjacent sub-membrane are bonded and enclosed to form a first accommodating cavity, and the negative electrode sheet and the adjacent sub-membrane are bonded and enclosed to form a second accommodating cavity, the bonding area on the positive electrode sheet and the negative electrode sheet is smaller, which can expand the contact area between the positive electrode sheet and the first electrolyte, and expand the contact area between the negative electrode sheet and the second electrolyte.

[0034] In some embodiments, the second adhesive region includes a second adhesive strip extending along the first direction.

[0035] In some embodiments, the fourth bonding area includes a fourth adhesive strip extending along the second direction.

[0036] By providing the second rubber strip, the third rubber strip and the fourth rubber strip to stably bond the adjacent sub-diaphragms or the sub-diaphragms to the positive and negative electrode sheets, the sealing performance of the first accommodating cavity and the second accommodating cavity can be improved.

[0037] In some embodiments, the positive electrode sheet and the negative electrode sheet each include a body and a tab protruding from at least one side of the body. The body is located between two adjacent sub-diaphragms, and the tab extends outside each sub-diaphragm.

[0038] Therefore, during the bonding process of two adjacent layers of sub-diaphragms, the overlapping positions of the tabs and the sub-diaphragms can be bonded, thereby improving the sealing of the first and second accommodating cavities and reducing the probability of electrolyte flowing out through the gap between the tabs and the diaphragms.

[0039] In some embodiments, the air permeability of the membrane is ≥ 20000 s / 100 cc, and the ionic conductivity of the membrane is ≥ 0.1 mS / cm 2 .

[0040] In a second aspect, the present application also provides a battery cell comprising the electrode assembly as described above.

[0041] In some embodiments, the battery cells are pouch cells.

[0042] In some embodiments, the battery cell further includes an outer packaging body, and the electrode assembly is disposed within the outer packaging body.

[0043] In some embodiments, the battery cell further includes a fifth bonding area disposed between an inner wall of the outer packaging body and an outermost separator in the electrode assembly, the fifth bonding area being used to separate the interior space of the outer packaging body into a first portion and a second portion that are independent of each other;

[0044] The first part is communicated with the first accommodating cavity, and the second part is communicated with the second accommodating cavity.

[0045] By providing the fifth bonding area, the internal space of the outer package can be divided into a first part and a second part which are independent of each other, thereby expanding the space for accommodating the electrolyte and playing a role in temporarily storing the electrolyte during the electrolyte penetration process.

[0046] In some embodiments, the electrode assembly comprises an ear portion and a body portion, a first heat-sealed area is provided on one side edge of the ear portion and an edge opposite to the ear portion of the electrode assembly, a second heat-sealed area is provided on an opening side edge of the first accommodating cavity, and a third heat-sealed area is provided on an opening side edge of the second accommodating cavity;

[0047] The first heat-sealing area, the second heat-sealing area and the third heat-sealing area are all used for heat-sealing with the outer packaging body.

[0048] By providing the first heat-sealing area, the second heat-sealing area and the third heat-sealing area, the first electrolyte can be more stably accommodated in the first accommodation cavity, and the second electrolyte can be more stably accommodated in the second accommodation cavity.

[0049] In a third aspect, the present application also provides a battery comprising the battery cell described above.

[0050] In a fourth aspect, the present application also provides an electrical device comprising the battery as described above.

[0051] The above-mentioned electrode assembly, battery cell, battery and electrical device have a first accommodating cavity formed between the positive electrode sheet and the adjacent diaphragm, and a second accommodating cavity formed between the negative electrode sheet and the adjacent diaphragm. The first accommodating cavity and the second accommodating cavity are arranged independently of each other. Therefore, the first electrolyte is filled into the first accommodating cavity, and the first electrolyte acts independently on the positive electrode, and the second electrolyte is filled into the second accommodating cavity, and the second electrolyte acts independently on the negative electrode, so that the first electrolyte and the second electrolyte are arranged separately and do not affect each other, thereby effectively reducing the influence of the first electrolyte on the negative electrode and the influence of the second electrolyte on the positive electrode, thereby improving battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] 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.

[0053] FIG. 1 is a schematic structural diagram of a battery cell according to one or more embodiments.

[0054] FIG2 is a schematic structural diagram of an electrode assembly according to one or more embodiments.

[0055] FIG3 is a schematic diagram illustrating the structure of a separator in an electrode assembly according to one or more embodiments.

[0056] FIG. 4 is a schematic structural diagram of a separator in an electrode assembly according to one or more embodiments.

[0057] FIG5 is a schematic structural diagram of an electrode assembly according to one or more embodiments.

[0058] FIG6 is a schematic structural diagram of an electrode assembly according to one or more embodiments.

[0059] FIG. 7 is a schematic structural diagram of an electrode assembly according to one or more embodiments.

[0060] FIG8 is a schematic structural diagram of an electrode assembly according to one or more embodiments.

[0061] FIG9 is a schematic structural diagram of an electrode assembly according to one or more embodiments.

[0062] FIG. 10 is a schematic structural diagram of a soft-pack battery cell according to one or more embodiments.

[0063] Explanation of the accompanying drawings: 100, battery cell; 10, electrode assembly; 20, outer packaging body; 30, fifth bonding area; 40, heat sealing area; 11, positive electrode sheet; 12, negative electrode sheet; 13, diaphragm; 14, first accommodating cavity; 15, second accommodating cavity; 21, first part; 22, second part; 111, main body; 112, tab; 113, second bonding area; 114, third bonding area; 131, first bonding area; 132, sub-diaphragm; 141, first opening; 151, second opening; 1311, first adhesive strip; 1321, fourth bonding area; a, width direction; b, length direction; c, first direction; d, second direction. DETAILED DESCRIPTION

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] Furthermore, a battery cell includes a housing and an electrode assembly housed within the housing. Battery cells come in different types, such as hard-shell battery cells and soft-pack battery cells. For hard-shell battery cells, the housing is a hard shell structure, while for soft-pack battery cells, the housing can be an encapsulating film, such as aluminum-plastic film or PP film. It should be noted that the housing forms a space for the electrode assembly, thereby protecting the electrode assembly.

[0073] The electrode assembly is the component within a battery cell where the electrochemical reaction occurs. It's primarily composed of a wound or stacked arrangement of positive and negative electrode sheets, typically with a separator between them. The portions of the positive and negative sheets containing active material constitute the main body of the electrode assembly, while the portions of the positive and negative sheets without active material each form a tab. The positive and negative tabs can be located together at one end of the main body or separately at either end.

[0074] In the current structure of battery cells, the electrolyte is filled in the packaging membrane 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 deteriorating for 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.

[0075] 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, wherein a first accommodating cavity is formed between the positive electrode sheet and the adjacent diaphragm, and a second accommodating cavity is formed between the negative electrode sheet and the adjacent diaphragm. The first accommodating cavity and the second accommodating cavity are arranged independently of each other. Therefore, the first accommodating cavity is filled with the first electrolyte, and the first electrolyte acts independently on the positive electrode, and the second electrolyte is filled into the second accommodating cavity, and the second electrolyte acts independently on the negative electrode, so that the first electrolyte and the second electrolyte are separately partitioned and arranged without affecting each other, thereby effectively reducing the influence of the first electrolyte on the negative electrode and the influence of the second electrolyte on the positive electrode, thereby improving battery performance.

[0076] Referring to Figures 1 and 2, an embodiment of the present application provides an electrode assembly 10, comprising at least one positive electrode sheet 11, at least one negative electrode sheet 12, and a separator 13. Each negative electrode sheet 12 is alternately stacked with each positive electrode sheet 11, and the separator 13 is sandwiched between each two adjacent positive electrode sheets 11 and negative electrode sheets 12. A first accommodating cavity 14 is provided between the positive electrode sheet 11 and the adjacent separator 13, and a second accommodating cavity 15 is provided between the negative electrode sheet 12 and the adjacent separator 13. The first accommodating cavity 14 and the second accommodating cavity 15 are independently provided and not interconnected.

[0077] It should be noted that the positive electrode sheets 11 and the negative electrode sheets 12 are stacked along their thickness direction, and the separator 13 is sandwiched between every two adjacent positive electrode sheets 11 and negative electrode sheets 12 to perform insulation and isolation.

[0078] The first accommodating chamber 14 and the second accommodating chamber 15 are independently arranged and not connected to each other, specifically referring to that the first accommodating chamber 14 and the second accommodating chamber 15 respectively form independent accommodating spaces, so that the first accommodating chamber 14 and the second accommodating chamber 15 can seal other components other than active ions in their respective accommodating spaces on the basis of smoothly achieving active ion conduction, thereby reducing the mutual influence between other components other than active ions in the first accommodating chamber 14 and the second accommodating chamber 15. In the present application, the first accommodating chamber 14 and the second accommodating chamber 15 are not connected to each other, which means that only active ions can pass through the diaphragm 13 between the first accommodating chamber 14 and the second accommodating chamber 15, thereby forming a closed circuit between the positive electrode sheet 11 and the negative electrode sheet 12, while other components other than active ions in the first accommodating chamber 14 and the second accommodating chamber 15 cannot diffuse with each other due to the obstruction of the diaphragm 13, that is, they cannot be connected.

[0079] The positive electrode sheet 11 and the adjacent separator 13 can be connected at their edges, but are not limited to forming a first accommodating cavity 14. The first accommodating cavity 14 is located between each positive electrode sheet 11 and the adjacent separator 13. Therefore, when the first electrolyte is accommodated in the first accommodating cavity 14, the first electrolyte can only act on the positive electrode sheet 11, while the additives in the first electrolyte can react with the active ions to form a passivation film on the surface of the positive electrode sheet 11, thereby playing a protective role.

[0080] Similarly, the negative electrode sheet 12 and the adjacent separator 13 can be connected at their edges, but are not limited to forming a second accommodating cavity 15. The second accommodating cavity 15 is located between each negative electrode sheet 12 and the adjacent separator 13. Therefore, when the second electrolyte is accommodated in the second accommodating cavity 15, the second electrolyte can only act on the negative electrode sheet 12, while the additives in the second electrolyte can react with the active ions to form a passivation film on the surface of the negative electrode sheet 12, thereby playing a protective role.

[0081] Through the above structure, the first electrolyte is accommodated in the first accommodating cavity 14, and the second electrolyte is accommodated in the second accommodating cavity 15, so that the first electrolyte and the second electrolyte do not mix or diffuse with each other, which can reduce the probability that some components in the first electrolyte have an adverse effect on the negative electrode sheet 12, and reduce the probability that some components in the second electrolyte have an adverse effect on the positive electrode sheet 11, thereby improving the overall performance of the battery.

[0082] In some embodiments, the first receiving cavity 14 has a first opening 141 for filling the first electrolyte, and the second receiving cavity 15 has a second opening 151 for filling the second electrolyte. The opening direction of the first opening 141 is opposite to that of the second opening 151 .

[0083] Specifically, the opening direction of the first opening 141 is opposite to the opening direction of the second opening 151, so that the first electrolyte and the second electrolyte are filled into the first accommodating cavity 14 and the second accommodating cavity 15 from opposite directions, respectively, which can reduce the probability of mixing between the first electrolyte and the second electrolyte.

[0084] By setting the opening direction of the first opening 141 of the first accommodating chamber 14 and the opening direction of the second opening 151 of the second accommodating chamber 15 to different directions, the first electrolyte and the second electrolyte can be filled into the first accommodating chamber 14 and the second accommodating chamber 15 from different directions, respectively, thereby reducing the probability of mixing between the first electrolyte and the second electrolyte.

[0085] Referring to Figures 1, 3, and 4, in some embodiments, the separator 13 is a continuous separator 13 having a Z-shaped structure. The positive electrode sheet 11 is located between each two adjacent layers of separator 13, and the negative electrode sheet 12 is located between each two adjacent layers of separator 13. A first bonding area 131 is provided on the separator 13 for bonding each two adjacent layers of separator 13.

[0086] It should be noted that the diaphragm 13 is a continuous diaphragm 13, which means that the diaphragm 13 is a single-piece diaphragm and is relatively long. It can be folded and wound between each two adjacent positive electrode sheets 11 and negative electrode sheets 12, so that each positive electrode sheet 11 is located between two adjacent layers of diaphragm 13, and each negative electrode sheet 12 is located between two adjacent layers of diaphragm 13, thereby insulating and isolating the two adjacent positive electrode sheets 11 and negative electrode sheets 12.

[0087] The first bonding area 131 refers to a structure that can provide bonding force between two adjacent layers of separators 13 so that the two adjacent layers of separators 13 can be bonded and fixed to each other.

[0088] When the diaphragm 13 is arranged in a Z-shaped folding manner, viewed from the side, the diaphragm 13 is folded to form multiple V-shaped structures connected end to end, wherein the opening directions of each two adjacent V-shaped structures are opposite, and each two adjacent V-shaped structures respectively place the positive electrode sheet 11 and the negative electrode sheet 12.

[0089] For each V-shaped structure, one side of the tip is naturally connected due to folding, and the two sides adjacent to the opening are bonded through the first bonding area 131. As a result, each V-shaped structure forms a pocket-like structure with an opening, and the opening directions of the two adjacent V-shaped structures are opposite.

[0090] At this time, a positive electrode sheet 11 and a negative electrode sheet 12 are respectively provided in each adjacent two V-shaped structures, so that a first accommodating cavity 14 is formed between the positive electrode sheet 11 and the diaphragm 13 on both sides, and a second accommodating cavity 15 is formed between the negative electrode sheet 12 and the diaphragm 13 on both sides. The opening directions of the first accommodating cavity 14 and the second accommodating cavity 15 are opposite and independent of each other, so that the first electrolyte in the first accommodating cavity 14 and the second electrolyte in the second accommodating cavity 15 can not affect each other.

[0091] In some specific embodiments, the positive electrode sheet 11 and the negative electrode sheet 12 may both adopt a multi-sheet stacked structure, that is, each positive electrode sheet 11 and each negative electrode sheet 12 is an independent single-sheet structure. Alternatively, the positive electrode sheet 11 may adopt a multi-sheet stacked structure, while the negative electrode sheet 12 may adopt a continuous folded structure similar to the continuous separator 13, or both the positive electrode sheet 11 and the negative electrode sheet 12 may adopt a continuous folded structure similar to the continuous separator 13.

[0092] Through the above structure, the diaphragm 13 is folded and wound between each two adjacent positive electrode sheets 11 and negative electrode sheets 12, and after the diaphragm 13 is folded, each two adjacent layers of the diaphragm 13 are bonded through their own first bonding area 131, so that the first accommodating cavity 14 is smoothly formed between the positive electrode sheet 11 and the adjacent diaphragm 13, and the second accommodating cavity 15 is smoothly formed between the negative electrode sheet 12 and the adjacent diaphragm 13, thereby realizing the 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 positive electrode or the negative electrode.

[0093] In some embodiments, the first adhesive region 131 is located on two opposite surfaces of the diaphragm 13 in the thickness direction. The first adhesive region 131 on each side surface includes a first adhesive strip 1311 disposed at both ends of the diaphragm 13 along the width direction a of the diaphragm 13, and the first adhesive strip 1311 extends along the length direction b of the diaphragm 13. The diaphragm 13 is folded along its own length direction b, and the first adhesive strip 1311 is bonded between each two adjacent layers of the folded diaphragm 13.

[0094] Specifically, the thickness direction of the diaphragm 13 is perpendicular to the plane formed by the width direction a and the length direction b of the diaphragm 13. That is, the first bonding area 131 is provided on both the front and back surfaces of the diaphragm 13. When the diaphragm 13 is a continuous diaphragm 13, the diaphragm 13 extends along its own length direction b, and the width direction a of the diaphragm 13 is perpendicular to the length direction b.

[0095] Two first adhesive strips 1311 are provided at opposite ends of the separator 13 along the width direction a of the separator 13, and each first adhesive strip 1311 extends along the length direction b of the separator 13. When the separator 13 is folded and wound along its length direction b between two adjacent positive and negative electrode sheets 11 and 12, the two adjacent separators 13 can be bonded together by the first adhesive strips 1311, thereby forming a pocket-like structure with one end open between the two adjacent separators 13.

[0096] It can be understood that the first bonding area 131 can be bonded by setting the first adhesive strip 1311, or by other methods, such as setting the first bonding area 131 to a sticky material with adhesive force, or coating the first bonding area 131 with glue, both of which can achieve bonding, which will not be elaborated here.

[0097] By providing a first adhesive strip 1311 extending along the length direction b of the diaphragm 13, when the diaphragm 13 is folded and arranged between the positive electrode sheet 11 and the negative electrode sheet 12, the first adhesive strip 1311 can bond the two ends in the width direction a between each two adjacent layers of diaphragms 13, so that the diaphragm 13 forms a pocket-like structure with one end open, so as to smoothly form the first accommodating cavity 14 and the second accommodating cavity 15.

[0098] In some embodiments, the size of the separator 13 along its own width direction a is larger than the size of the adjacent positive electrode sheet 11 or negative electrode sheet 12 along the width direction a, and the area where the separator 13 extends beyond the positive electrode sheet 11 or negative electrode sheet 12 is set as the first bonding area 131.

[0099] Specifically, the width direction a of the positive electrode sheet 11 and the negative electrode sheet 12 is in the same direction as the width direction a of the separator 13. In the width direction a of the separator 13, opposite ends of the separator 13 extend beyond the positive electrode sheet 11 and the negative electrode sheet 12 and form a first bonding area 131. The first bonding area 131 bonds each two adjacent layers of separator 13. That is, there is no overlap between the positive electrode sheet 11 or the negative electrode sheet 12 and the first bonding area 131 between two adjacent layers of separator 13.

[0100] When the first electrolyte is contained in the first accommodating cavity 14, the contact area between the positive electrode sheet 11 and the first electrolyte is larger. Similarly, when the second electrolyte is contained in the second accommodating cavity 15, the contact area between the negative electrode sheet 12 and the second electrolyte is larger.

[0101] Therefore, by forming the first bonding area 131 in the area where the separator 13 extends beyond the positive electrode sheet 11 or the negative electrode sheet 12, smooth bonding between each two adjacent layers of the separator 13 can be achieved, and the contact area between the positive electrode sheet 11 and the negative electrode sheet 12 and the first electrolyte and the second electrolyte respectively can be increased.

[0102] As shown in Figures 2 and 3, in some embodiments, the positive electrode sheet 11 and the negative electrode sheet 12 each include a body 111 and a tab 112 protruding from at least one side of the body 111. The body 111 is located between two adjacent layers of separators 13, and the tab 112 extends outside the separators 13. A first adhesive strip 1311 at at least one end of the separator 13 in the width direction a is used to bond each adjacent two layers of separators 13 and the tab 112 located between the two adjacent layers of separators 13.

[0103] Specifically, the main body 111 of the positive electrode sheet 11 and the main body 111 of the negative electrode sheet 12 together form the main body of the electrode assembly 10, i.e., the portion containing the active material. The tabs 112 of the positive electrode sheet 11 and the tabs 112 of the negative electrode sheet 12 are the portions without active material. The tabs 112 extend from between two adjacent layers of separator 13 to form the positive and negative connection terminals of the battery cell.

[0104] When the diaphragm 13 is folded and wound between the positive electrode sheet 11 and the negative electrode sheet 12, the tabs 112 between each two adjacent layers of diaphragms 13 will pass through the first bonding area 131 and extend out of the diaphragm 13. Therefore, when the first bonding area 131 bonds each two adjacent layers of diaphragms 13, the tabs 112 located between the two adjacent layers of diaphragms 13 will be bonded together, thereby reducing the probability of the electrolyte in the first accommodating cavity 14 or the second accommodating cavity 15 flowing out through the gap between the tabs 112 and the diaphragm 13.

[0105] Thus, by simultaneously bonding each two adjacent layers of diaphragms 13 and the tabs 112 located between the two adjacent layers of diaphragms 13 through the first adhesive strip 1311 of the first bonding area 131, the sealing performance of the first accommodating cavity 14 and the second accommodating cavity 15 can be improved, and the probability of electrolyte flowing out through the gap between the tabs 112 and the diaphragms 13 can be reduced.

[0106] Please refer to FIG. 2 and FIG. 5 . In some embodiments, the separator 13 includes a plurality of stacked sub-separators 132 . The positive electrode sheet 11 is located between each two adjacent sub-separators 132 , and the negative electrode sheet 12 is located between each two adjacent sub-separators 132 .

[0107] Specifically, each sub-separator 132 is a separate piece and is sandwiched between two adjacent positive electrode sheets 11 and negative electrode sheets 12 .

[0108] Compared to a folded continuous separator 13, the spacing between adjacent sub-separators 132 in a stacked arrangement is fixed. When the continuous separator 13 is folded, the spacing at the corners of the Z-fold is smaller, resulting in higher electrolyte osmotic pressure at these locations. However, the spacing between adjacent sub-separators 132 is constant, and the electrolyte osmotic pressure at each location is the same, resulting in more uniform electrolyte penetration.

[0109] As shown in Figures 6 and 7, in some embodiments, the positive electrode sheet 11 and the negative electrode sheet 12 are each provided with a second bonding area 113 in a first direction c, and are each provided with a third bonding area 114 in a second direction d intersecting the first direction c. The second bonding area 113 and the third bonding area 114 are respectively bonded to adjacent sub-separators 132 to form a first accommodation cavity 14 and a second accommodation cavity 15, respectively.

[0110] Specifically, the positive electrode sheet 11 and the negative electrode sheet 12 are typically arranged in a rectangular structure, with the first direction c and the second direction d being arranged along the length and width of the rectangular structure, respectively. That is, the first direction c is perpendicular to the second direction d. In this case, the second bonding area 113 extends along the first direction c, and the third bonding area 114 extends along the second direction d. Thus, the second bonding area 113 and the third bonding area 114 are arranged perpendicular to each other.

[0111] Furthermore, after the positive electrode sheet 11 , the negative electrode sheet 12 and the separator 13 are assembled to form the electrode assembly 10 , the first direction c is parallel to the height direction of the electrode assembly 10 , and the second direction d is parallel to the width direction a of the electrode assembly 10 .

[0112] The second bonding area 113 and the third bonding area 114 can also be bonded by setting a first adhesive strip 1311. The second bonding area 113 is set at one end of each positive electrode sheet 11 or each negative electrode sheet 12 along the first direction c, and the third bonding area 114 is set at the opposite ends of each positive electrode sheet 11 or each negative electrode sheet 12 along the second direction d.

[0113] Therefore, when each positive electrode sheet 11 is stacked with each negative electrode sheet 12 and the adjacent sub-membrane 132, the second bonding area 113 and the third bonding area 114 can achieve bonding between each positive electrode sheet 11 and each negative electrode sheet 12 and the adjacent sub-membrane 132, so that each positive electrode sheet 11 and the adjacent sub-membrane 132 are jointly enclosed to form a first accommodating cavity 14 with an opening on one side through the second bonding area 113 and the third bonding area 114, and each negative electrode sheet 12 and the adjacent sub-membrane 132 are jointly enclosed to form a second accommodating cavity 15 with an opening on one side through the second bonding area 113 and the third bonding area 114.

[0114] By providing the second bonding area 113 and the third bonding area 114, each positive electrode sheet 11 and the adjacent sub-membrane 132 can be bonded to each other and enclosed to form a first accommodating cavity 14 to accommodate the first electrolyte; and each negative electrode sheet 12 and the adjacent sub-membrane 132 can be bonded to each other and enclosed to form a second accommodating cavity 15 to accommodate the second electrolyte.

[0115] As shown in Figures 8 and 9, in some embodiments, the positive electrode sheet 11 and the negative electrode sheet 12 are each provided with a second bonding area 113 in a first direction c, and each sub-separator layer 132 is provided with a fourth bonding area 1321 in a second direction d intersecting the first direction c. The second bonding area 113 and the fourth bonding area 1321 are respectively bonded to adjacent sub-separators 132 to form a first accommodating cavity 14 and a second accommodating cavity 15, respectively.

[0116] When the second bonding area 113 is provided on each positive electrode sheet 11 and each negative electrode sheet 12 along the first direction c, a fourth bonding area 1321 extending along the second direction d can be provided on each sub-separator layer 132. In this case, the positive electrode sheet 11 or negative electrode sheet 12 is bonded to the adjacent sub-separator layer 132 via the second bonding area 113 thereon, while the two adjacent sub-separators 132 are bonded in the second direction d via the fourth bonding area 1321. When the positive electrode sheet 11, negative electrode sheet 12, and sub-separators 132 are stacked, the second bonding area 113 and the fourth bonding area 1321 can similarly enclose a first accommodating cavity 14 between the positive electrode sheet 11 and the adjacent sub-separator layer 132, and the second bonding area 113 and the fourth bonding area 1321 can enclose a second accommodating cavity 15 between the negative electrode sheet 12 and the adjacent sub-separator layer 132.

[0117] The second bonding area 113 is set on the positive electrode sheet 11 and the negative electrode sheet 12, and the fourth bonding area 1321 is set on each layer of the sub-membrane 132. On the premise that the positive electrode sheet 11 and the adjacent sub-membrane 132 are bonded and enclosed to form the first accommodating cavity 14, and the negative electrode sheet 12 and the adjacent sub-membrane 132 are bonded and enclosed to form the second accommodating cavity 15, the bonding area on the positive electrode sheet 11 and the negative electrode sheet 12 is smaller, which can expand the contact area between the positive electrode sheet 11 and the first electrolyte, and expand the contact area between the negative electrode sheet 12 and the second electrolyte.

[0118] In some embodiments, the second adhesive region 113 includes a second adhesive strip (not shown) extending along the first direction c. And / or, the third adhesive region 114 includes a third adhesive strip (not shown) extending along the second direction d. And / or, the fourth adhesive region 1321 includes a fourth adhesive strip (not shown) extending along the second direction d.

[0119] Specifically, the second bonding area 113, the third bonding area 114 and the fourth bonding area 1321 can be bonded by setting adhesive strips, so that each positive electrode sheet 11 and each negative electrode sheet and the adjacent sub-diaphragm 132 are bonded to each other, and the first accommodating cavity 14 and the second accommodating cavity 15 are smoothly enclosed.

[0120] In some embodiments, the positive electrode sheet 11 and the negative electrode sheet 12 each include a body 111 and a tab 112 protruding from at least one side of the body 111 . The body 111 is located between two adjacent sub-diaphragms 132 , and the tab 112 extends outside each sub-diaphragm 132 .

[0121] It is understood that when the separator 13 includes multiple stacked sub-separators 132, the positive electrode sheet 11 and the negative electrode sheet 12 also include a body 111 and a tab 112 protruding from at least one side of the body 111. The body 111 is located between two adjacent layers of sub-separators 132, and the tab 112 extends outside the stacked sub-separators 132. The adhesive strip 1311 at at least one end of the sub-separator 132 in the width direction a is used to bond two adjacent layers of sub-separators 132 and the tab 112 located between the two adjacent layers of sub-separators 132.

[0122] In some embodiments, the air permeability of the membrane 13 is ≥ 20000 s / 100 cc, and the ionic conductivity of the membrane 13 is ≥ 0.1 mS / cm 2 .

[0123] Specifically, the air permeability of the diaphragm 13 is well known in the art. The air permeability of the diaphragm 13 is comprehensively affected by the internal pore structure of the diaphragm 13, such as the porosity, pore size, pore shape, and pore tortuosity. It indirectly reflects the degree to which the diaphragm 13 blocks other components of the electrolyte on both sides except for active ions. It can be tested using methods known in the art. For example, the diaphragm 13 is punched into a small disc with a diameter of 50 mm. The small disc is tested for air permeability using a Wang Yan type air permeability meter (Asahi Seiko model EG01-55-1MR). The test pressure is controlled at 1.21 kPa. The time (seconds, s) required for 100 cc of gas (air) to pass through the test is used to obtain the air permeability of the diaphragm, which is expressed in s / 100 cc.

[0124] The ionic conductivity of the diaphragm 13 refers to the ability of the diaphragm 13 to conduct active ions (such as lithium ions), and can be tested specifically by the following method:

[0125] The separator 13 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 1470ECellTest multi-channel electrochemical workstation. The test voltage was 10 mV and the test frequency 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 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.

[0126] Therefore, the permeability of the diaphragm 13 will affect the permeability of the electrolyte in the diaphragm 13. If the permeability of the electrolyte in the diaphragm 13 is too high, it means that the electrolyte is more likely to penetrate through the diaphragm 13 from the first accommodating cavity 14 or the second accommodating cavity 15, thereby reducing the sealing of the first accommodating cavity 14 for the first electrolyte, and reducing the sealing of the second accommodating cavity 15 for the second electrolyte.

[0127] The ionic conductivity of the diaphragm 13 affects the conduction of lithium ions between the positive and negative electrodes. By limiting the range of the ionic conductivity of the diaphragm 13, active ions can be smoothly conducted between the first accommodating cavity 14 and the second accommodating cavity 15, thereby smoothly forming a circuit between the positive and negative electrodes.

[0128] As a preferred range, the ionic conductivity of the diaphragm 13 can be set to ≥0.3 mS / cm 2 .

[0129] Therefore, by setting the air permeability and ionic conductivity of the separator 13 within the above ranges, the sealing performance of the first accommodating chamber 14 for the first electrolyte and the sealing performance of the second accommodating chamber 15 for the second electrolyte can be further improved. This allows the first electrolyte to more stably act on the positive electrode in the first accommodating chamber 14, while the second electrolyte can more stably act on the negative electrode in the second accommodating chamber 15.

[0130] In addition, the diaphragm 13 can be obtained by using conventional porous PP, PE, or PI-based membranes and performing a densification 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 and performing a lithiation treatment. All of these can achieve the above-mentioned effects and will not be elaborated here.

[0131] As shown in FIG. 1 and FIG. 10 , based on the same concept as the electrode assembly 10 described above, the present application further provides a battery cell 100 , including the electrode assembly 10 described above.

[0132] In some embodiments, the battery cell 100 further includes a first electrolyte (not shown) and a second electrolyte (not shown). The first electrolyte is an electrolyte that acts on the positive electrode and is filled in the first receiving cavity 14, and the second electrolyte is an electrolyte that acts on the negative electrode and is filled in the second receiving cavity 15.

[0133] The composition and content of the first electrolyte and the second electrolyte may be the same or different, and may be specifically set according to the actual materials of the positive and negative electrodes 12, so that the composition of the first electrolyte can better promote the positive electrode 11, thereby increasing the efficiency of the reaction between the positive electrode 11 and the first electrolyte. The composition of the second electrolyte can better promote the negative electrode 12, thereby increasing the efficiency of the reaction between the negative electrode 12 and the second electrolyte.

[0134] Furthermore, the first and second accommodating chambers 14 and 15 are used to separately accommodate the first electrolyte and the second electrolyte, so that the first electrolyte and the second electrolyte can react with the positive electrode sheet 11 and the negative electrode sheet 12 independently of each other, thereby reducing the influence of the first electrolyte on the negative electrode sheet 12 and the influence of the second electrolyte on the positive electrode sheet 11.

[0135] Through the above structure, the first electrolyte can be better accommodated in the first accommodating cavity 14, the second electrolyte can be better accommodated in the second accommodating cavity 15, and the influence of the first electrolyte on the negative electrode sheet 12 and the influence of the second electrolyte on the positive electrode sheet 11 can be reduced.

[0136] In some embodiments, at least one of the first electrolyte and the second electrolyte is a gel electrolyte.

[0137] Specifically, a gel electrolyte refers to an electrolyte in a gel-like state. This effectively reduces the fluidity of the electrolyte, further reducing the probability of mixing between the first electrolyte and the second electrolyte, allowing the first electrolyte to be more stably accommodated in the first accommodating cavity 14 and the second electrolyte to be more stably accommodated in the second accommodating cavity 15.

[0138] Furthermore, the first electrolyte may be configured as a gel electrolyte, the second electrolyte may be configured as a gel electrolyte, or both the first electrolyte and the second electrolyte may be configured as gel electrolytes.

[0139] 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 negative electrode sheet 12 and the probability of the second electrolyte affecting the positive electrode sheet 11.

[0140] In some embodiments, the battery cell 100 further includes an outer packaging body 20 , and the electrode assembly 10 is disposed within the outer packaging body 20 .

[0141] Specifically, the outer packaging body 20 can be, but is not limited to, an aluminum-plastic film, a PP film, or a PC film. The outer packaging body 20 is wrapped around the periphery of the electrode assembly 10 and can protect the electrode assembly 10 .

[0142] In some embodiments, the battery cell 100 further includes a fifth bonding area 30 disposed between the inner wall of the outer packaging body 20 and the outermost separator 13 in the electrode assembly 10. The fifth bonding area 30 is used to separate the interior space of the outer packaging body 20 into a first portion 21 and a second portion 22 that are independent of each other. The first portion 21 communicates with the first accommodating cavity 14, and the second portion 22 communicates with the second accommodating cavity 15.

[0143] Specifically, after the positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 are stacked to form the electrode assembly 10, the electrode assembly 10 is placed inside the outer package 20. At this point, a fifth bonding area 30 is provided between the outermost separator 13 of the electrode assembly 10 and the inner wall of the outer package 20, allowing the outermost separator 13 to bond to the inner wall of the outer package 20. In this way, the interior of the outer package 20 is divided into a first portion 21 and a second portion 22 that are independent of each other.

[0144] When the separator 13 is folded and wound between the positive electrode sheet 11 and the negative electrode sheet 12, the opening directions of the first accommodating cavity 14 and the second accommodating cavity 15 are opposite. As a result, the first portion 21 can communicate with the first accommodating cavity 14, and the second portion 22 can communicate with the second accommodating cavity 15. After the first portion 21 is connected to the first accommodating cavity 14, the space after the second portion 22 is connected to the second accommodating cavity 15 is disconnected. The electrolytes in the two spaces are arranged independently and do not affect each other.

[0145] By providing the fifth bonding area 30 , the internal space of the outer package 20 can be divided into a first portion 21 and a second portion 22 which are independent of each other, thereby expanding the space for accommodating electrolyte and temporarily storing electrolyte during the electrolyte penetration process.

[0146] In some embodiments, the electrode assembly 10 comprises an ear portion and a body portion. A first heat-sealing region 40 is provided on one side edge of the ear portion and on an edge opposite the ear portion of the electrode assembly 10. A second heat-sealing region 50 is provided on the opening side edge of the first accommodating cavity 14. A third heat-sealing region 60 is provided on the opening side edge of the second accommodating cavity 15. The first heat-sealing region 40, the second heat-sealing region 50, and the third heat-sealing region 60 are all used for heat-sealing with the outer packaging body.

[0147] Specifically, the tab portion is a structure composed of the tabs of all the positive electrode sheets 11 and the tabs of all the negative electrode sheets 12 , and the body portion is a structure composed of the bodies of all the positive electrode sheets 11 and the bodies of all the negative electrode sheets 12 .

[0148] After the positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 are stacked to form the electrode assembly 10, the electrode assembly 10 is placed inside the outer packaging body 20. At this time, since the first heat-sealing area 40 is provided on the edge of the electrode assembly 10 where the electrode ear portion is located and the edge of the side opposite to the electrode ear portion, the first heat-sealing area 40 can be used to heat-seal the edge of the electrode assembly 10 where the electrode ear portion is located and the edge of the side opposite to the electrode ear portion to the outer packaging body 20.

[0149] After the first heat-sealing area 40 is heat-sealed, the remaining two side edges become the openings of the first accommodating cavity 14 and the second accommodating cavity 15, respectively. The first electrolyte is then filled into the first accommodating cavity 14 through the opening, and the first accommodating cavity 14 is heat-sealed by the second heat-sealing area 50. The second electrolyte is then filled into the second accommodating cavity 15 through the opening, and the second accommodating cavity 15 is heat-sealed by the third heat-sealing area 60.

[0150] Thus, by providing the first heat-sealing area 40 , the second heat-sealing area 50 and the third heat-sealing area 60 , the first electrolyte can be more stably accommodated in the first accommodation cavity 14 , and the second electrolyte can be more stably accommodated in the second accommodation cavity 15 .

[0151] Based on the same concept as the above-mentioned soft-pack battery cell 100 , the present application also provides a battery, including the above-mentioned soft-pack battery cell 100 .

[0152] Based on the same concept as the above-mentioned battery, the present application also provides an electrical device, including the above-mentioned battery.

[0153] Based on the same concept as the above-mentioned battery cell 100, the present application also provides a method for preparing the battery cell 100, comprising the following steps:

[0154] The positive electrode sheet 11 and the negative electrode sheet 12 are stacked in sequence;

[0155] A bonding area is provided on the separator 13, and the separator 13 is folded and wound in a Z-shaped structure between the adjacent positive electrode sheet 11 and the adjacent negative electrode sheet 12 to form the electrode assembly 10. A first accommodating cavity 14 is formed between the positive electrode sheet 11 and the adjacent separator 13 through the bonding area, and a second accommodating cavity 15 is formed between the negative electrode sheet 12 and the adjacent separator 13 through the bonding area. The first accommodating cavity 14 and the second accommodating cavity 15 are independently provided and not connected to each other.

[0156] Alternatively, the separator 13 is cut into multiple sub-separators 132, and bonding areas are provided on the positive electrode sheet 11 and the negative electrode sheet 12. Alternatively, bonding areas are provided on the positive electrode sheet 11, the negative electrode sheet 12, and the sub-separator 132, and a sub-separator 132 is provided between each adjacent positive electrode sheet 11 and the negative electrode sheet 12 to form the electrode assembly 10. A first accommodating cavity 14 is formed between the positive electrode sheet 11 and the adjacent separator 13 through the bonding area, and a second accommodating cavity 15 is formed between the negative electrode sheet 12 and the adjacent separator 13 through the bonding area. The first accommodating cavity 14 and the second accommodating cavity 15 are provided independently of each other and are not connected to each other.

[0157] The electrode assembly 10 is housed in the outer packaging body 20 .

[0158] In some embodiments, the above preparation method further comprises the following steps:

[0159] The outermost separator 13 in the electrode assembly 10 is bonded and fixed to the inner wall of the outer package 20 .

[0160] Heat-seal the outer packaging body 20 with respect to the side edge where the pole ear portion of the electrode assembly 10 is located and the side edge opposite to the pole ear portion.

[0161] The first containing cavity 14 is filled with the first electrolyte, and then the opening side edge of the first containing cavity 14 is heat-sealed.

[0162] The second containing cavity 15 is filled with the second electrolyte, and then the edge of the opening of the second containing cavity 15 is heat-sealed.

[0163] Specifically, when the diaphragm 13 is set as a continuous diaphragm and is folded and wound between each two adjacent positive electrode sheets 11 and negative electrode sheets 12, first, before the diaphragm 13 is folded, rubber strips 1311 are respectively set on the two side surfaces in the thickness direction of the diaphragm 13, and the rubber strips 1311 on each side surface are respectively located at both ends along the width direction a of the diaphragm 13, and the rubber strips 1311 extend along the length direction b of the diaphragm 13.

[0164] When the separator 13 is folded and wound between each pair of adjacent positive electrode sheets 11 and negative electrode sheets 12, the adhesive strip 1311 acts as a bond between each pair of adjacent separators 13, so that both sides of the separator 13 along its width direction a are bonded and sealed by the adhesive strip 1311. At this point, a first accommodating cavity 14 with one side open is formed between each positive electrode sheet 11 and the adjacent separator 13, and a second accommodating cavity 15 with one side open is formed between each negative electrode sheet 12 and the adjacent separator 13. The opening directions of the first accommodating cavity 14 and the second accommodating cavity 15 are opposite.

[0165] When the separator 13 is a stacked sub-separator 132, a second bonding area 113 is first provided on each layer of the positive electrode sheet 11 and the negative electrode sheet 12, and then a third bonding area 114 is provided on each layer of the positive electrode sheet 11 and the negative electrode sheet 12, or a fourth bonding area 1321 is provided on each layer of the sub-separator 132. The second bonding area 113 and the third bonding area 114, or the second bonding area 113 and the fourth bonding area 1321, enclose a first accommodating cavity 14 having a first opening 141 between the positive electrode sheet 11 and the adjacent sub-separator 132, and a second accommodating cavity 15 having a second opening 151 is formed between the negative electrode sheet 12 and the adjacent sub-separator 132.

[0166] After assembling the electrode assembly 10, the electrode assembly 10 is placed inside the outer packaging body 20, and the outermost side of the diaphragm 13 is bonded to the inner wall of the outer packaging body 20 through the fifth bonding area 30 to separate the internal space of the outer packaging body 20 into a first part 21 and a second part 22, so that the electrode assembly 10 can be stably set inside the outer packaging body 20.

[0167] Furthermore, the first heat-sealing area 40 heat-seals the edge of the electrode assembly 10 where the electrode ear is located and the edge of the electrode assembly 10 opposite the electrode ear to the outer package 20. After the first heat-sealing area 40 heat-seals, the remaining two edges respectively become the openings of the first accommodating cavity 14 and the second accommodating cavity 15.

[0168] Then, the first electrolyte is filled into the first accommodating chamber 14 through the opening of the first accommodating chamber 14, and the side edges of the opening of the first accommodating chamber 14 are heat-sealed by the second heat-sealing area 50. Then, the second electrolyte is filled into the second accommodating chamber 15 through the opening of the second accommodating chamber 15, and the side edges of the opening of the second accommodating chamber 15 are heat-sealed by the third heat-sealing area 60.

[0169] In order to test and verify the battery cells provided in this application, the positive and negative electrode sheets, separators, and electrolytes were prepared according to the following methods to form comparative examples and examples:

[0170] As shown in FIG1 , when the separator is set as a continuous separator, the positive electrode sheet, the negative electrode sheet and the separator are assembled together to form a battery. The specific preparation process is as follows:

[0171] (1) Preparation of positive electrode

[0172] The positive electrode active material lithium manganate (LiMn2O4) was mixed with the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) in a weight ratio of 95:3:2 in N-methylpyrrolidone solvent and then coated on both sides of the aluminum foil. After drying and cold pressing, the positive electrode sheet was obtained. The coating amount per unit area on both sides was 0.27g / 1540.25mm 2 , punch out the electrode into a positive electrode sheet with a main active area of ​​49*87mm.

[0173] (2) Preparation of negative electrode sheet

[0174] Graphite, conductive carbon, and styrene-butadiene rubber (SBR) were dissolved in deionized water at a weight ratio of 95:3:2 and mixed to obtain a negative electrode slurry under the action of a vacuum mixer. The negative electrode slurry was evenly coated on both sides of a copper foil. The copper foil was dried at room temperature and then transferred to a 120°C oven for drying for 1 hour. The negative electrode sheet was then cold pressed and cut into pieces, wherein the coating amount per unit area on both sides was 0.17 g / 1540.25 mm. 2 , punch out the electrode into a negative electrode sheet with a main active area of ​​51*93mm.

[0175] (3) Preparation of diaphragm

[0176] Comparative Example 1 uses a traditional PE membrane, wherein the thickness of the PE membrane is 12 μm, the air permeability is 146 s / 100 cc, and the ionic conductivity is 0.62 mS / cm 2 The present invention provides a diaphragm 13 prepared by dipping a common PE diaphragm in a treatment solution and then curing it with UV light. The diaphragm 13 is used as the diaphragm of Comparative Example 2 and Examples 1, 2, 3, and 4. After the treatment, the air permeability of the diaphragm is 26469s / 100cc and the conductivity is 0.56mS / cm 2 ; Cut the two diaphragms into 108mm width for later use.

[0177] Among them, the components of the above-mentioned dip coating treatment liquid include EC, EMC, LiPF6, ethoxylated trimethylolpropane triacrylate, vinyl acetate, and benzoyl peroxide (BPO), and the mass ratio of EC:EMC:LiPF6:ethoxylated trimethylolpropane triacrylate: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 365nm, a power of 800mW / cm2, and a treatment time of 2s.

[0178] (4) Preparation of electrolyte

[0179] Positive electrolyte: LiFSI was dissolved in dimethyl sulfoxide to prepare 1M / L electrolyte A;

[0180] Positive electrode gel electrolyte (first electrolyte): Electrolyte A: 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 A-GEL;

[0181] Anode electrolyte: EC:EMC:DMC were mixed in a volume ratio of 1:1:1, and LiFSI was added to prepare electrolyte B with a lithium salt concentration of 1M / L.

[0182] The negative electrode side gel electrolyte (second electrolyte) was mixed according to the mass ratio of electrolyte A: polyethylene glycol dimethacrylate: VC = 80%: 10%: 10%, and then AIBN was added with a mass fraction of 0.4% of the total mixed solution mass, which was recorded as electrolyte B-GEL.

[0183] (5) Assembling to form a battery

[0184] The battery assembly steps in Example 1, Example 2, Example 3 and Example 4 are as follows:

[0185] The prepared positive and negative electrode sheets are stacked in sequence, and a separator is folded and wound in a Z-shaped structure between each pair of adjacent positive and negative electrode sheets to provide isolation. The two adjacent separator layers on either side of each positive electrode sheet are bonded together via a first bonding area 131, forming a first accommodating cavity 14. The two adjacent separator layers on either side of each negative electrode sheet are bonded together via a first bonding area 131, forming a second accommodating cavity 15. The opening of the second accommodating cavity 15 is opposite to that of the first accommodating cavity 14.

[0186] The stacked negative electrode sheet, separator, and positive electrode sheet are placed together in the aluminum-plastic film, and the outermost side of the separator 13 is bonded to the inner wall of the aluminum-plastic film through the fifth bonding area 30 to separate the inner space of the aluminum-plastic film into a first portion 21 and a second portion 22 .

[0187] The aluminum-plastic film is heat-sealed to the side edge of the electrode lug and the side edge opposite the electrode lug on the electrode assembly 10 through the first heat-sealing area 40. The first electrolyte is then filled into the first accommodating cavity 14 through the opening of the first accommodating cavity 14, and the side edge of the opening of the first accommodating cavity 14 is heat-sealed through the second heat-sealing area 50. The second electrolyte is then filled into the second accommodating cavity 15 through the opening of the second accommodating cavity 15, and the side edge of the opening of the second accommodating cavity 15 is heat-sealed through the third heat-sealing area 60. Finally, the battery is assembled.

[0188] As shown in Figure 2, when the diaphragm is set as a multi-layer sub-diaphragm, the positive electrode sheet, the negative electrode sheet and the sub-diaphragm are assembled together to form a battery, wherein the preparation process of the positive electrode sheet, the negative electrode sheet, the sub-diaphragm and the electrolyte is the same as the preparation process of the positive electrode sheet, the negative electrode sheet, the diaphragm and the electrolyte of the above-mentioned Z-type structure diaphragm.

[0189] During the battery assembly process, the separator is first cut to form multiple sub-separators 132. The prepared positive and negative electrode sheets are stacked in sequence, with each sub-separator 132 sandwiched between two adjacent positive and negative electrode sheets.

[0190] A second bonding area 113 is provided on each layer of the positive electrode sheet 11 and the negative electrode sheet 12, and a third bonding area 114 is provided on each layer of the positive electrode sheet 11 and the negative electrode sheet 12. Through the second bonding area 113 and the third bonding area 114, a first accommodating cavity 14 having a first opening 141 is enclosed and formed between the positive electrode sheet 11 and the adjacent sub-diaphragm 132, and a second accommodating cavity 15 having a second opening 151 is enclosed and formed between the negative electrode sheet 12 and the adjacent sub-diaphragm 132.

[0191] The stacked negative electrode sheet, sub-separator, and positive electrode sheet are placed together in the aluminum-plastic film, and the outermost sub-separator is bonded to the inner wall of the aluminum-plastic film via the fifth bonding area 30. At this time, the first opening 141 is set to the left, and the second opening 151 is set to the right.

[0192] The aluminum-plastic film is heat-sealed to the side edge of the electrode lug and the side edge opposite the electrode lug on the electrode assembly 10 through the first heat-sealing area 40. The first electrolyte is then filled into the first accommodating cavity 14 through the opening of the first accommodating cavity 14, and the side edge of the opening of the first accommodating cavity 14 is heat-sealed through the second heat-sealing area 50. The second electrolyte is then filled into the second accommodating cavity 15 through the opening of the second accommodating cavity 15, and the side edge of the opening of the second accommodating cavity 15 is heat-sealed through the third heat-sealing area 60, ultimately assembling the battery.

[0193] The battery assembly steps in Comparative Example 1 and Comparative Example 2 are as follows:

[0194] The prepared positive electrode sheets and negative electrode sheets are stacked in sequence, and the separator is folded and wound in a Z-shaped structure between each two adjacent positive electrode sheets and negative electrode sheets to play an isolating role.

[0195] Then, the stacked negative electrode sheet, separator and positive electrode sheet are placed into the aluminum-plastic film, the positive electrode electrolyte and the negative electrode electrolyte are filled into the aluminum-plastic film, and the aluminum-plastic film is packaged and finally assembled into a battery.

[0196] It can be understood that the batteries in Comparative Examples 1 and 2 are assembled in a traditional manner.

[0197] Furthermore, a life test was carried out under a constant temperature environment of 25°C. The specific process is: first stand for 5 minutes, and discharge to 3V at 0.5C (1500mA). After standing for 5 minutes, charge to 4.3V at 1 / 3C, and then charge at a constant voltage at 4.3V until the current is less than or equal to 100mA. Stand for 5 minutes, and then discharge to 3V at 1 / 3C. The discharge capacity at this time is the initial discharge capacity, recorded as D0. Then, according to the above process, a cycle test was carried out in the range of 3V-4.3V. Record the capacity value Dn (n=1,2,3...) every week. When the capacity Dn≤80%D0, record the cycle number n as the cycle life. The data obtained during the test are as shown in the following table:

[0198] Comparative Examples 1 and 2, as well as Examples 1 and 2, all employed a continuous separator, i.e., a separator folded in a Z-shape and disposed between the positive and negative electrode sheets. Examples 3 and 4 employed sub-separators, i.e., separators comprising multiple stacked sub-separators. Test data clearly demonstrates that the cycle life of the soft-pack battery cells provided herein is significantly improved.

[0199] 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.

[0200] 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 comprising: At least one positive electrode; At least one negative electrode sheet is alternately stacked with each of the positive electrode sheets; as well as A separator is sandwiched between each two adjacent positive and negative electrode sheets; A first accommodating cavity is provided between the positive electrode sheet and the adjacent diaphragm, and a second accommodating cavity is provided between the negative electrode sheet and the adjacent diaphragm. The first accommodating cavity and the second accommodating cavity are independently provided and not connected to each other.

2. The electrode assembly according to claim 1, wherein The first accommodating cavity has a first opening, the second accommodating cavity has a second opening, and an opening direction of the first opening is opposite to an opening direction of the second opening.

3. The electrode assembly according to claim 2, wherein: The diaphragm is a continuous diaphragm and has a Z-shaped structure. The positive electrode sheet is located between each two adjacent layers of the diaphragm, and the negative electrode sheet is located between each two adjacent layers of the diaphragm. A first bonding area is provided on the diaphragm, and the first bonding area is used to bond each two adjacent layers of the diaphragm.

4. The electrode assembly according to claim 3, wherein: The first bonding area is located on two opposite sides of the diaphragm in the thickness direction, and the first bonding area on each side surface includes a first adhesive strip respectively arranged at both ends of the diaphragm along the width direction of the diaphragm, and the first adhesive strip extends along the length direction of the diaphragm.

5. The electrode assembly according to claim 4, wherein The separator has a larger dimension along its width direction than the adjacent positive electrode sheet or the negative electrode sheet along its width direction, and a region where the separator extends beyond the positive electrode sheet or the negative electrode sheet is set as the first bonding region.

6. The electrode assembly according to claim 5, wherein: The positive electrode sheet and the negative electrode sheet each include a body and a tab protruding from at least one side of the body, the body being located between two adjacent layers of the diaphragm, and the tab extending out of the diaphragm; The first adhesive strip at at least one end in the width direction of the diaphragm is used to bond two adjacent layers of the diaphragm and the tab between the two adjacent layers of the diaphragm.

7. The electrode assembly according to claim 2, wherein: The separator includes a plurality of stacked sub-separators, the positive electrode sheet is located between each two adjacent sub-separators, and the negative electrode sheet is located between each two adjacent sub-separators.

8. The electrode assembly according to claim 7, wherein: The positive electrode sheet and the negative electrode sheet are respectively provided with a second bonding area in a first direction, and are respectively provided with a third bonding area in a second direction intersecting with the first direction; The second bonding area and the third bonding area are respectively bonded to the adjacent sub-diaphragms to form The first accommodating cavity and the second accommodating cavity.

9. The electrode assembly according to claim 8, wherein The second bonding area includes a second adhesive strip extending along the first direction.

10. The electrode assembly according to claim 8 or 9, wherein: The third bonding area includes a third adhesive strip extending along the second direction.

11. The electrode assembly according to claim 7, wherein The positive electrode sheet and the negative electrode sheet are respectively provided with a second bonding area in a first direction, and each of the sub-separators is provided with a fourth bonding area in a second direction intersecting with the first direction; The second bonding area and the fourth bonding area are respectively bonded to the adjacent sub-diaphragms to form the first accommodation cavity and the second accommodation cavity respectively.

12. The electrode assembly according to claim 11, wherein The second bonding area includes a second adhesive strip extending along the first direction.

13. The electrode assembly according to claim 11 or 12, wherein: The fourth bonding area includes a fourth adhesive strip extending along the second direction.

14. The electrode assembly according to any one of claims 7 to 13, wherein: The positive electrode sheet and the negative electrode sheet each include a body and a tab protruding from at least one side of the body. The body is located between two adjacent layers of the sub-diaphragms, and the tab extends out of each sub-diaphragm.

15. The electrode assembly according to any one of claims 1 to 14, wherein: The air permeability of the diaphragm is ≥20000s / 100cc, and the ionic conductivity of the diaphragm is ≥0.1mS / cm 2 .

16. A battery cell comprising the electrode assembly according to any one of claims 1 to 15.

17. The battery cell according to claim 16, wherein: The battery cell is a soft-pack battery.

18. The battery cell according to claim 16 or 17, wherein: The battery cell further includes an outer packaging body, and the electrode assembly is disposed within the outer packaging body.

19. The battery cell according to claim 18, wherein: The battery cell further includes a fifth bonding area provided between an inner wall of the outer packaging body and the outermost separator in the electrode assembly, the fifth bonding area being used to separate the inner space of the outer packaging body into a first part and a second part which are independent of each other; The first portion is communicated with the first accommodating cavity, and the second portion is communicated with the second accommodating cavity.

20. The battery cell according to claim 19, wherein The electrode assembly comprises an ear portion and a body portion, wherein a first heat-sealing area is provided on one side edge of the ear portion and an edge opposite to the ear portion of the electrode assembly, a second heat-sealing area is provided on an opening side edge of the first accommodating cavity, and a third heat-sealing area is provided on an opening side edge of the second accommodating cavity; The first heat-sealing area, the second heat-sealing area and the third heat-sealing area are all used for heat-sealing with the outer packaging body.

21. A battery comprising the battery cell according to any one of claims 16 to 20.

22. An electrical device comprising the battery according to claim 21.

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