Electrode assembly, battery monomer, preparation method of battery monomer, battery and power utilization device

Abstract

The invention relates to an electrode assembly, a battery monomer, a battery and a power utilization device. The electrode assembly comprises at least one positive plate; the at least one negative plate and the positive plates are alternately stacked; the diaphragms are clamped between every two adjacent positive plates and negative plates; wherein a first accommodating cavity is arranged between the positive plate and the diaphragm adjacent to the positive plate, a second accommodating cavity is arranged between the negative plate and the diaphragm adjacent to the negative plate, and the first accommodating cavity and the second accommodating cavity are arranged independently and are not communicated with each other. The first accommodating cavity and the second accommodating cavity are mutually independently arranged, so that the first accommodating cavity is filled with the first electrolyte, and the second accommodating cavity is filled with the second electrolyte, so that the first electrolyte and the second electrolyte are independently arranged in a partitioned manner and do not influence each other; therefore, the influence of the first electrolyte on the cathode and the influence of the second electrolyte on the anode are effectively reduced, and the battery performance is improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and in particular, to an electrode assembly, a battery cell, a preparation method thereof, a battery, and an electric device. Background Art

[0002] In a lithium-ion battery, the materials of the positive electrode and the negative electrode are different, which leads to different requirements for the components of the electrolyte for the positive electrode and the negative electrode. When different components in the electrolyte have a promoting effect on one of the positive electrode or the negative electrode, there may be a reverse negative impact on the other, ultimately affecting the performance of the battery. Summary of the Invention

[0003] Based on this, in view of the problem that the electrolyte in the current battery structure has a negative impact on the positive electrode or the negative electrode, thereby affecting the battery performance, it is necessary to provide an electrode assembly, a battery cell, a preparation method thereof, a battery, and an electric device.

[0004] In a first aspect, the present application provides an electrode assembly, comprising:

[0005] At least one positive electrode sheet;

[0006] At least one negative electrode sheet, which is stacked alternately with each positive electrode sheet; and

[0007] A separator, which is clamped between every two adjacent positive electrode sheets and negative electrode sheets;

[0008] Wherein, a first accommodation cavity is provided between the positive electrode sheet and the adjacent separator, and a second accommodation cavity is provided between the negative electrode sheet and the adjacent separator. The first accommodation cavity and the second accommodation cavity are independently arranged and not communicated with each other.

[0009] With the above structure, the first electrolyte is placed in the first accommodation cavity, and the second electrolyte is placed in the second accommodation cavity, so that other components except the active ions between the first electrolyte and the second electrolyte do not mix and diffuse, which can reduce the probability that some components in the first electrolyte have an adverse effect on the negative electrode sheet, and reduce the probability that some components in the second electrolyte have an adverse effect on the positive electrode sheet, thereby improving the overall performance of the battery.

[0010] In some embodiments, the first accommodation cavity has a first opening, the second accommodation cavity has a second opening, and the opening direction of the first opening is opposite to the opening direction of the second opening.

[0011] Setting the opening direction of the first opening of the first accommodation cavity to be opposite to the opening direction of the second opening of the second accommodation cavity can respectively fill the first electrolyte and the second electrolyte into the first accommodation cavity and the second accommodation cavity from different directions, reducing the probability of mixing between the first electrolyte and the second electrolyte.

[0012] In some embodiments, the separator is a continuous separator and has a Z-shaped structure. The positive electrode sheet is located between every two adjacent layers of the separator, and the negative electrode sheet is located between every two adjacent layers of the separator. The separator is provided with a first bonding area for bonding every two adjacent layers of the separator.

[0013] With the above structure, the separator is folded and wound around every two adjacent positive electrode sheets and negative electrode sheets. After the separator is folded, every two adjacent layers of the separator are bonded through their own first bonding areas, so that a first accommodation cavity is smoothly formed between the positive electrode sheet and the adjacent separator, and a second accommodation cavity is smoothly formed between the negative electrode sheet and the adjacent separator, thereby realizing the separate and independent accommodation of the first electrolyte and the second electrolyte, and reducing the probability that the first electrolyte and the second electrolyte are mixed with each other and thus affect the positive electrode or the negative electrode.

[0014] In some embodiments, the first bonding areas are located on the opposite two side surfaces in the thickness direction of the separator, and the first bonding area on each side surface includes adhesive strips respectively arranged at both ends of the separator along the width direction of the separator, and the adhesive strips extend along the length direction of the separator.

[0015] By providing the adhesive strips extending along the length direction of the separator, when the separator is folded and arranged between the positive electrode sheet and the negative electrode sheet, the adhesive strips can bond both ends in the width direction between every two adjacent layers of the separator, so that the separator forms a pocket-shaped structure with one end open, facilitating the smooth formation of the first accommodation cavity and the second accommodation cavity.

[0016] In some embodiments, the dimension of the separator in the width direction is greater than the dimensions of the adjacent positive electrode sheet and negative electrode sheet in the width direction, and the area where the separator extends beyond the positive electrode sheet or the negative electrode sheet is set as the first bonding area.

[0017] By forming the first bonding area in the area where the separator extends beyond the positive electrode sheet or the negative electrode sheet, the smooth bonding between every two adjacent layers of the separator can be realized, and the contact areas between the positive electrode sheet and the negative electrode sheet and the first electrolyte and the second electrolyte can be increased.

[0018] In some embodiments, both the positive electrode sheet and the negative electrode sheet include a main body and a tab protruding from at least one side of the main body. The main body is located between every two adjacent layers of the separator, and the tab extends outside the separator;

[0019] Among them, the adhesive strips at at least one end in the width direction of the separator are used to bond every two adjacent layers of the separator and the tabs located between every two adjacent layers of the separator.

[0020] Thus, by simultaneously bonding every two adjacent layers of the separator and the tabs located between every two adjacent layers of the separator through the adhesive strips of the first bonding area, the sealing performance of the first accommodation cavity and the second accommodation cavity can be improved, and the probability that the electrolyte flows out through the gap between the tab and the separator can be reduced.

[0021] In some embodiments, the separator includes multiple sub-separators stacked on top of each other. 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.

[0022] Compared with a continuously folded separator, in the stacked sub-separators, the distance between every two adjacent sub-separators is fixed. When the continuous separator is folded, the distance at the corner position of the Z-shaped fold is smaller, resulting in a greater osmotic pressure of the electrolyte here. The distance between every two adjacent sub-separators is the same, and the osmotic pressure of the electrolyte at each position is the same, enabling a more uniform osmotic effect of the electrolyte.

[0023] In some embodiments, the positive electrode sheet and the negative electrode sheet are respectively provided with second bonding regions in a first direction, and are respectively provided with third bonding regions in a second direction intersecting the first direction;

[0024] Wherein, the second bonding region and the third bonding region are respectively bonded to the adjacent sub-separators to correspondingly form a first accommodation cavity and a second accommodation cavity.

[0025] By providing the second bonding region and the third bonding region, each positive electrode sheet can be bonded to the adjacent sub-separator and enclose to form a first accommodation cavity for accommodating the first electrolyte; and each negative electrode sheet can be bonded to the adjacent sub-separator and enclose to form a second accommodation cavity for accommodating the second electrolyte.

[0026] In some embodiments, the positive electrode sheet and the negative electrode sheet are respectively provided with second bonding regions in a first direction, and each sub-separator is provided with a fourth bonding region in a second direction intersecting the first direction;

[0027] Wherein, the second bonding region and the fourth bonding region are respectively bonded to the adjacent sub-separators to correspondingly form a first accommodation cavity and a second accommodation cavity.

[0028] By providing the second bonding region on the positive electrode sheet and the negative electrode sheet, and providing the fourth bonding region on each layer of sub-separator, on the premise of realizing the bonding between the positive electrode sheet and the adjacent sub-separator to enclose and form a first accommodation cavity, and the bonding between the negative electrode sheet and the adjacent sub-separator to enclose and form a second accommodation cavity, the bonding areas on the positive electrode sheet and the negative electrode sheet are 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.

[0029] In some embodiments, both the positive electrode sheet and the negative electrode sheet include a main body and a tab protruding from at least one side of the main body. The main body is located between two adjacent layers of sub-separators, and the tab extends outside each sub-separator.

[0030] Thus, during the process of bonding adjacent layers of the sub-separator, the overlapping position of the tab and the sub-separator can be bonded, improving the sealing performance of the first accommodation cavity and the second accommodation cavity, and reducing the probability of the electrolyte flowing out through the gap between the tab and the separator.

[0031] In some embodiments, the air permeability of the separator is ≥20000 s / 100 cc, and the ionic conductivity of the separator is ≥0.1 mS / cm 2 。

[0032] In a second aspect, the present application further provides a battery cell including the electrode assembly described above.

[0033] In some embodiments, the battery cell is a soft-pack battery.

[0034] In some embodiments, the battery cell further includes a first electrolyte and a second electrolyte. The first electrolyte is filled in the first accommodation cavity, and the second electrolyte is filled in the second accommodation cavity. Among them, the composition and / or content of the first electrolyte and the second electrolyte are different.

[0035] With the above structure, the first electrolyte can react better with the positive electrode sheet, and the second electrolyte can react better with the negative electrode sheet. Moreover, it can reduce the influence of the first electrolyte on the negative electrode sheet and the influence of the second electrolyte on the positive electrode sheet.

[0036] In some embodiments, at least one of the first electrolyte and the second electrolyte is a gel electrolyte.

[0037] With the above structure, starting from the inherent characteristics of the electrolyte, the probability of mixing between the first electrolyte and the second electrolyte can be further reduced, thereby reducing the probability of the first electrolyte affecting the negative electrode sheet and the probability of the second electrolyte affecting the positive electrode sheet.

[0038] In some embodiments, the first electrolyte and / or 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 an acrylic acid monomer unit and / or an acrylate monomer unit.

[0039] Thereby, the first electrolyte and / or the second electrolyte can smoothly form a gel electrolyte, thus reducing the probability of mixing between the first electrolyte and the second electrolyte.

[0040] In some embodiments, 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.

[0041] In some embodiments, the battery cell further includes an outer encapsulation body, and the electrode assembly is disposed inside the outer encapsulation body.

[0042] In some embodiments, the battery cell further includes a fifth bonding region disposed between the inner wall of the outer encapsulation body and the outermost diaphragm in the electrode assembly, and the fifth bonding region is used to divide the internal space of the outer encapsulation body into two independent parts, a first part and a second part;

[0043] Wherein, the first part communicates with the first accommodation cavity, and the second part communicates with the second accommodation cavity.

[0044] By providing the fifth bonding region, the internal space of the encapsulation film can be divided into two independent parts, a first part and a second part, to expand the accommodation space for the electrolyte, and can play a role in temporarily storing the electrolyte during the electrolyte penetration process.

[0045] In some embodiments, the electrode assembly has a tab portion and a body portion, a first heat-sealing region is provided on one side edge of the tab portion and the side edge opposite to the tab portion of the electrode assembly, a second heat-sealing region is provided on the opening side edge of the first accommodation cavity, and a third heat-sealing region is provided on the opening side edge of the second accommodation cavity;

[0046] Wherein, the first heat-sealing region, the second heat-sealing region, and the third heat-sealing region are all used for heat-sealing with the outer encapsulation body.

[0047] By providing the first heat-sealing region, the second heat-sealing region, and the third heat-sealing region, 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.

[0048] In a third aspect, the present application further provides a battery, including the battery cell as described above.

[0049] In a fourth aspect, the present application further provides an electrical device, including the battery as described above.

[0050] In a fifth aspect, the present application further provides a method for manufacturing a battery cell, including the following steps:

[0051] Stack the positive electrode sheet and the negative electrode sheet in sequence;

[0052] A bonding area is provided on the separator, and the separator is folded in a Z-shaped structure and wound around the adjacent positive electrode plate and negative electrode plate to form an electrode assembly. A first accommodation cavity is formed between the positive electrode plate and the adjacent separator through the bonding area, and a second accommodation cavity is formed between the negative electrode plate and the adjacent separator through the bonding area. The first accommodation cavity and the second accommodation cavity are independently arranged and do not communicate with each other;

[0053] Alternatively, the separator is slit into multiple sub-separators, and bonding areas are provided on the positive electrode plate and the negative electrode plate, or bonding areas are provided on the positive electrode plate, the negative electrode plate, and the sub-separators. One sub-separator is arranged between each adjacent positive electrode plate and negative electrode plate to form an electrode assembly. A first accommodation cavity is formed between the positive electrode plate and the adjacent separator through the bonding area, and a second accommodation cavity is formed between the negative electrode plate and the adjacent separator through the bonding area. The first accommodation cavity and the second accommodation cavity are independently arranged and do not communicate with each other;

[0054] The electrode assembly is placed inside the outer package.

[0055] In some embodiments, after the step of placing the electrode assembly inside the outer package, the following steps are further included:

[0056] The outermost separator of the electrode assembly is bonded and fixed to the inner wall of the outer package;

[0057] Thermal sealing is performed between the side edges of the electrode assembly where the pole lugs are located and the side edge opposite to the pole lugs and the outer package;

[0058] The first electrolyte is filled into the first accommodation cavity, and then the opening side edge of the first accommodation cavity is thermally sealed;

[0059] The second electrolyte is filled into the second accommodation cavity, and then the opening side edge of the second accommodation cavity is thermally sealed.

[0060] In the above-mentioned electrode assembly, battery cell, its preparation method, battery, and electrical device, a first accommodation cavity is formed between the positive electrode plate and the adjacent separator, and a second accommodation cavity is formed between the negative electrode plate and the adjacent separator. The first accommodation cavity and the second accommodation cavity are independently arranged. Therefore, the first electrolyte is filled into the first accommodation cavity, and the first electrolyte acts independently on the positive electrode, and the second electrolyte is filled into the second accommodation cavity, and the second electrolyte acts independently on the negative electrode, so that the first electrolyte and the second electrolyte are separately partitioned 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, and improving the battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a schematic structural diagram of a battery cell according to one or more embodiments.

[0062] Figure 2 Schematic structural diagram of an electrode assembly according to one or more embodiments.

[0063] Figure 3 Schematic structural diagram of a separator in an electrode assembly according to one or more embodiments.

[0064] Figure 4 Schematic structural diagram of a separator in an electrode assembly according to one or more embodiments.

[0065] Figure 5 Schematic structural diagram of an electrode assembly according to one or more embodiments.

[0066] Figure 6 Schematic structural diagram of an electrode assembly according to one or more embodiments.

[0067] Figure 7 Schematic structural diagram of an electrode assembly according to one or more embodiments.

[0068] Figure 8 Schematic structural diagram of an electrode assembly according to one or more embodiments.

[0069] Figure 9 Schematic structural diagram of an electrode assembly according to one or more embodiments.

[0070] Figure 10 Schematic structural diagram of a pouch cell according to one or more embodiments.

[0071] Description of reference numerals: 100, cell; 10, electrode assembly; 20, encapsulation film; 30, fifth bonding region; 40, first heat-sealing region; 50, second heat-sealing region; 60, third heat-sealing region; 11, positive electrode tab; 12, negative electrode tab; 13, separator; 14, first accommodation cavity; 15, second accommodation cavity; 21, first part; 22, second part; 111, body; 112, tab; 113, second bonding region; 114, third bonding region; 131, first bonding region; 132, sub-separator; 141, first opening; 151, second opening; 1311, adhesive strip; 1321, fourth bonding region; a, width direction; b, length direction; c, first direction; d, second direction. Detailed Description of the Embodiments

[0072] To make the above objects, features, and advantages of the present application more apparent and understandable, the following provides a detailed description of the specific embodiments of the present application with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0073] In the description of the present application, it should be understood that if terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present application.

[0074] In addition, if terms such as "first" and "second" appear, these terms are only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0075] In the present application, unless otherwise clearly specified and limited, if terms such as "mounted", "connected", "connected to", "fixed", etc. appear, these terms should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0076] In the present application, unless otherwise clearly specified and limited, if a description such as a first feature being "on" or "under" a second feature appears, its meaning may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0077] It should be noted that if an element is referred to as "fixed to" or "disposed on" another element, it can 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 can be directly connected to the other element or there may be an intermediate element at the same time. If present, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are only for illustrative purposes and do not represent the only implementation.

[0078] At present, from the perspective of the development of the market situation, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars and other fields. With the continuous expansion of the application fields of power batteries, the market demand is also continuously increasing.

[0079] 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, parallel or in a mixed connection. A mixed connection means that there are both series and parallel connections among multiple battery cells.

[0080] Furthermore, the battery cell includes a housing and an electrode assembly disposed inside the housing. Among them, the battery cell includes different types such as hard-shell battery cells and soft-pack battery cells. When the battery cell is a hard-shell battery cell, the housing is a hard-shell structure, and when the battery cell is a soft-pack battery cell, the housing can be a packaging film such as an aluminum-plastic film or a PP film. It should be noted that the housing is used to form a housing space for accommodating the electrode assembly, so as to protect the electrode assembly.

[0081] The electrode assembly is the component in the battery cell where an electrochemical reaction occurs. The electrode assembly is mainly formed by winding or laminating a positive electrode sheet and a negative electrode sheet, and a separator is usually disposed between the positive electrode sheet and the negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet having active substances constitute the main body part of the electrode assembly, and the parts of the positive electrode sheet and the negative electrode sheet without active substances respectively constitute the electrode tabs. The positive electrode tab and the negative electrode tab can be located at one end of the main body part together or at both ends of the main body part respectively.

[0082] In the current battery cell structure, an electrolyte is filled within a packaging film to conduct active ions between the positive electrode and the negative electrode. However, other components in the electrolyte besides the active ions can also diffuse through the separator between the positive and negative electrodes. The diffusion of other components besides the active ions often deteriorates the performance of the battery cell. For example, anions can permeate through the separator, causing polarization inside the battery cell and thus affecting the rate performance of the battery cell. In addition, the positive and negative electrodes also have different requirements for the composition of the electrolyte and some of its additives. For instance, some additives in the electrolyte may only be effective for one of the positive or negative electrodes, ineffective or even deteriorating for the other. In this way, the additives in the electrolyte can instead affect the electrochemical reactions of the positive or negative electrodes, resulting in an impact on the performance of the battery.

[0083] Based on the above considerations, to solve the problem that the electrolyte in the current battery cell can have a negative impact on the positive or negative electrode, thereby affecting the battery performance, one or more embodiments of the present application provide an electrode assembly. A first accommodation cavity is formed between the positive electrode sheet and the adjacent separator, and a second accommodation cavity is formed between the negative electrode sheet and the adjacent separator. The first accommodation cavity and the second accommodation cavity are independently arranged. Therefore, a first electrolyte is filled into the first accommodation cavity, and the first electrolyte acts independently on the positive electrode. A second electrolyte is filled into the second accommodation cavity, and the second electrolyte acts independently on the negative electrode, such that the first electrolyte and the second electrolyte are separately partitioned 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, and improving the battery performance.

[0084] Referring to Figure 1 and Figure 2 , an embodiment of the present application provides an electrode assembly 10, including at least one positive electrode sheet 11, at least one negative electrode sheet 12, and a separator 13. The negative electrode sheets 12 and the positive electrode sheets 11 are alternately stacked, and the separator 13 is sandwiched between every two adjacent positive electrode sheets 11 and negative electrode sheets 12. Among them, a first accommodation cavity 14 is provided between the positive electrode sheet 11 and the adjacent separator 13, and a second accommodation cavity 15 is provided between the negative electrode sheet 12 and the adjacent separator 13. The first accommodation cavity 14 and the second accommodation cavity 15 are independently arranged and not connected to each other.

[0085] It should be noted that the positive electrode sheet 11 and the negative electrode sheet 12 are stacked along their own thickness directions, and the separator 13 is sandwiched between every two adjacent positive electrode sheets 11 and negative electrode sheets 12 to play an insulating and isolating role.

[0086] The first accommodating cavity 14 and the second accommodating cavity 15 are independently arranged and not communicated with each other. Specifically, it means that the first accommodating cavity 14 and the second accommodating cavity 15 respectively form independent accommodating spaces, so that on the basis of smoothly realizing the conduction of active ions, the first accommodating cavity 14 and the second accommodating cavity 15 can seal other components except active ions in their respective accommodating spaces, reducing the mutual influence between other components except active ions in the first accommodating cavity 14 and the second accommodating cavity 15. In the present application, the non-communication between the first accommodating cavity 14 and the second accommodating cavity 15 means that only active ions can pass through the separator 13 between the first accommodating cavity 14 and the second accommodating cavity 15 to form a closed loop between the positive electrode sheet 11 and the negative electrode sheet 12, while other components except active ions in the first accommodating cavity 14 and the second accommodating cavity 15 cannot diffuse into each other under the blocking of the separator 13, that is, they cannot be communicated.

[0087] The positive electrode sheet 11 and the adjacent separator 13 can, but are not limited to, form the first accommodating cavity 14 by connecting their edges. The first accommodating cavity 14 is located between each positive electrode sheet 11 and the adjacent separator 13. Therefore, when the first electrolyte is placed in the first accommodating cavity 14, the first electrolyte can only act on the positive electrode sheet 11, and the additive in the first electrolyte can act on the active ions to form a passivation film on the surface of the positive electrode sheet 11 to play a protective role.

[0088] Similarly, the negative electrode sheet 12 and the adjacent separator 13 can, but are not limited to, form the second accommodating cavity 15 by connecting their edges. The second accommodating cavity 15 is located between each negative electrode sheet 12 and the adjacent separator 13. Therefore, when the second electrolyte is placed in the second accommodating cavity 15, the second electrolyte can only act on the negative electrode sheet 12, and the additive in the second electrolyte can act on the active ions to form a passivation film on the surface of the negative electrode sheet 12 to play a protective role.

[0089] Through the above structure, the first electrolyte is placed in the first accommodating cavity 14, and the second electrolyte is placed in the second accommodating cavity 15, so that the first electrolyte and the second electrolyte do not mix and 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.

[0090] In some embodiments, the first accommodating cavity 14 has a first opening 141, and the second accommodating cavity 15 has a second opening 151. The opening direction of the first opening 141 is opposite to the opening direction of the second opening 151.

[0091] Among them, the first opening 141 is used to fill the first electrolyte into the first accommodating cavity 14, and the second opening 151 is used to fill the second electrolyte into the second accommodating cavity 15.

[0092] Specifically, the opening directions of the first opening 141 and the second opening 151 are opposite to each other, such 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.

[0093] By setting the opening directions of the first opening 141 of the first accommodating cavity 14 and the second opening 151 of the second accommodating cavity 15 to be different directions, the first electrolyte and the second electrolyte can be filled into the first accommodating cavity 14 and the second accommodating cavity 15 from different directions respectively, reducing the probability of mixing between the first electrolyte and the second electrolyte.

[0094] Please refer to Figure 1 、 Figure 3 and Figure 4 In some embodiments, the separator 13 is a continuous separator and has a Z-shaped structure. The positive electrode sheet 11 is located between every two adjacent layers of the separator 13, and the negative electrode sheet 12 is located between every two adjacent layers of the separator 13. A first bonding area 131 is provided on the separator 13, and the first bonding area 131 is used for bonding every two adjacent layers of the separator 13.

[0095] It should be noted that the separator 13 being a continuous separator means that the separator 13 is a single-piece separator with a relatively long length, and can be wound around every two adjacent positive electrode sheets 11 and negative electrode sheets 12 in a folded manner, such that each positive electrode sheet 11 is located between two adjacent layers of the separator 13, and each negative electrode sheet 12 is located between two adjacent layers of the separator 13, thereby insulating and isolating every two adjacent positive electrode sheets 11 and negative electrode sheets 12.

[0096] The first bonding area 131 refers to a structure that can provide a bonding force between two adjacent layers of the separator 13, so that the two adjacent layers of the separator 13 can be bonded and fixed to each other.

[0097] When the separator 13 is arranged in a Z-shaped folding manner, when viewed from the side, the separator 13 forms a plurality of V-shaped structures connected end to end after folding. Among them, the opening directions of every two adjacent V-shaped structures are opposite, and every two adjacent V-shaped structures are respectively provided with the positive electrode sheet 11 and the negative electrode sheet 12.

[0098] 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. Thus, each V-shaped structure forms a pocket-shaped structure with an opening, and the opening directions of two adjacent V-shaped structures are opposite.

[0099] At this time, a positive electrode sheet 11 and a negative electrode sheet 12 are respectively arranged 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.

[0100] In some specific embodiments, the positive electrode sheet 11 and the negative electrode sheet 12 may both adopt a multi-sheet stacking structure, that is, each positive electrode sheet 11 and each negative electrode sheet 12 are independent single-sheet structures. Alternatively, the positive electrode sheet 11 may adopt a multi-sheet stacking structure, while the negative electrode sheet 12 may adopt a continuous folding structure that is the same as the continuous separator, or both the positive electrode sheet 11 and the negative electrode sheet 12 may adopt a continuous folding structure that is the same as the continuous separator 13.

[0101] 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 thus affecting the positive electrode or the negative electrode.

[0102] See also Figure 3 In some embodiments, the first bonding area 131 is located on two opposite sides of the diaphragm 13 in the thickness direction, and the first bonding area 131 on each side surface includes adhesive strips 1311 respectively arranged at both ends of the diaphragm 13 along the width direction a of the diaphragm 13, and the adhesive strips 1311 extend along the length direction b of the diaphragm 13. The diaphragm 13 is folded along its own length direction b, and the adhesive strips 1311 are bonded between each two adjacent layers of the folded diaphragm 13.

[0103] 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, the diaphragm 13 is extended along its own length direction b, and the width direction a of the diaphragm 13 is perpendicular to the length direction b.

[0104] The adhesive strips 1311 include two strips, which are respectively arranged at opposite ends of the separator 13 along the width direction a of the separator 13, and each adhesive strip 1311 extends along the length direction b of the separator 13. When the separator 13 is folded and wound around each adjacent pair of the positive electrode plates 11 and the negative electrode plates 12 along its own length direction b, the adjacent two layers of the separator 13 can be bonded through the adhesive strips 1311, so that a pocket-like structure with one end open is formed between the adjacent two layers of the separator 13.

[0105] It can be understood that the first bonding area 131 can be bonded by setting the adhesive strips 1311, or can be bonded by other means. For example, the first bonding area 131 can be set as a viscous material with adhesiveness, or glue can be coated on the first bonding area 131, and the bonding effect can be achieved, which will not be elaborated here.

[0106] By providing the adhesive strips 1311 extending along the length direction b of the separator 13, when the separator 13 is folded and arranged between the positive electrode plate 11 and the negative electrode plate 12, the adhesive strips 1311 can bond the two ends in the width direction a between each adjacent two layers of the separator 13, so that the separator 13 forms a pocket-like structure with one end open, facilitating the smooth formation of the first accommodation cavity 14 and the second accommodation cavity 15.

[0107] In some embodiments, the dimension of the separator 13 along the width direction a is greater than the dimensions of the adjacent positive electrode plate 11 and negative electrode plate 12 along the width direction a, and the area where the separator 13 exceeds the positive electrode plate 11 and the negative electrode plate 12 is set as the first bonding area 131.

[0108] Specifically, the width direction a of the positive electrode plate 11 and the negative electrode plate 12 is the same as the width direction a of the separator 13. Along the width direction a of the separator 13, both opposite ends of the separator 13 exceed the positive electrode plate 11 and the negative electrode plate 12 and form the first bonding area 131. Through the first bonding area 131, each adjacent two layers of the separator 13 are bonded, that is, there is no overlapping part between the positive electrode plate 11 or the negative electrode plate 12 and the first bonding area 131 between the adjacent two layers of the separator 13.

[0109] When the first electrolyte is placed in the first accommodation cavity 14, the contact area between the positive electrode plate 11 and the first electrolyte is larger. Similarly, when the second electrolyte is placed in the second accommodation cavity 15, the contact area between the negative electrode plate 12 and the second electrolyte is larger.

[0110] Therefore, by forming the first bonding area 131 in the area where the separator 13 exceeds the positive electrode plate 11 or the negative electrode plate 12, the smooth bonding between each adjacent two layers of the separator 13 can be achieved, and the contact areas between the positive electrode plate 11 and the negative electrode plate 12 and the first electrolyte and the second electrolyte can be increased respectively, thereby improving the reaction efficiency.

[0111] As Figure 2 and Figure 3 shown, in some embodiments, the positive electrode sheet 11 and the negative electrode sheet 12 both include a main body 111 and a tab 112 protruding from at least one side of the main body 111. The main body 111 is located between two adjacent layers of the separator 13, and the tab 112 extends outside the separator 13. Among them, the adhesive strip 1311 at at least one end in the width direction a of the separator 13 is used to bond every two adjacent layers of the separator 13 and the tab 112 located between the two adjacent layers of the separator 13.

[0112] 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 part of the electrode assembly 10, that is, the part with the active material. The tabs 112 of the positive electrode sheet 11 and the tabs 112 of the negative electrode sheet 12 are the parts without the active material. The tabs 112 extend out from between two adjacent layers of the separator 13 so as to form the positive connection terminal and the negative connection terminal of the battery cell.

[0113] When the separator 13 is folded and wound around the positive electrode sheet 11 and the negative electrode sheet 12, the tabs 112 between every two adjacent layers of the separator 13 will pass through the first bonding area 131 and extend out of the separator 13. Therefore, when the first bonding area 131 bonds every two adjacent layers of the separator 13, it will bond the tabs 112 located between the two adjacent layers of the separator 13 together, thereby reducing the probability that the electrolyte in the first accommodation cavity 14 or the second accommodation cavity 15 flows out through the gap between the tab 112 and the separator 13.

[0114] Thus, by simultaneously bonding every two adjacent layers of the separator 13 and the tabs 112 located between the two adjacent layers of the separator 13 with the adhesive strip 1311 of the first bonding area 131, the sealing performance of the first accommodation cavity 14 and the second accommodation cavity 15 can be improved, and the probability that the electrolyte flows out through the gap between the tab 112 and the separator 13 can be reduced.

[0115] Please also refer to Figure 2 and Figure 5 , in some embodiments, the separator 13 includes multiple sub-separators 132 stacked together. The positive electrode sheet 11 is located between every two adjacent sub-separators 132, and the negative electrode sheet 12 is located between every two adjacent sub-separators 132.

[0116] Specifically, each sub-separator 132 is a single piece and is sandwiched between every two adjacent positive electrode sheets 11 and negative electrode sheets 12.

[0117] Compared with the continuous diaphragm in the folded state, in the multi-piece sub-diaphragms 132 arranged in a stacked manner, the distance between every two adjacent sub-diaphragms 132 is fixed. When the continuous diaphragm 13 is folded, the distance at the corner position of the Z-shaped fold is smaller, resulting in a greater osmotic pressure of the electrolyte here. The distance between every two adjacent sub-diaphragms 132 is the same, and the osmotic pressure of the electrolyte at each position is the same, which can make the osmotic effect of the electrolyte more uniform.

[0118] In some embodiments, the positive electrode sheet 11 and the negative electrode sheet 12 both include a main body 111 and a tab 112 protruding from at least one side of the main body 111. The main body 111 is located between two adjacent layers of sub-diaphragms 132, and the tab 112 extends outside each sub-diaphragm 132.

[0119] It can be understood that when the diaphragm 13 includes multiple sub-diaphragms 132 arranged in a stacked manner, the positive electrode sheet 11 and the negative electrode sheet 12 also include a main body 111 and a tab 112 protruding from at least one side of the main body 111. The main body 111 is located between two adjacent layers of sub-diaphragms 132, and the tab 112 extends outside the sub-diaphragms 132 arranged in a stacked manner. Among them, at least one end of the adhesive strip 1311 in the width direction a of the sub-diaphragm 132 is used to bond every two adjacent layers of sub-diaphragms 132 and the tab 112 located between the two adjacent layers of sub-diaphragms 132.

[0120] As Figure 6 and Figure 7 shown, in some embodiments, the positive electrode sheet 11 and the negative electrode sheet 12 are respectively provided with a second bonding area 113 in the first direction c, and are respectively provided with a third bonding area 114 in the second direction d intersecting with the first direction c. Among them, the second bonding area 113 and the third bonding area 114 are respectively bonded to the adjacent sub-diaphragms 132 to correspondingly form a first accommodation cavity 14 and a second accommodation cavity 15.

[0121] Specifically, the positive electrode sheet 11 and the negative electrode sheet 12 are usually set as a rectangular structure. The first direction c and the second direction d are respectively arranged along the length direction b and the width direction a of the rectangular structure, that is, the first direction c is perpendicular to the second direction d. At this time, the second bonding area 113 extends along the first direction c, and the third bonding area 114 extends along the second direction d, so the second bonding area 113 and the third bonding area 114 are arranged perpendicular to each other.

[0122] Furthermore, after the positive electrode sheet 11, the negative electrode sheet 12, and the diaphragm 13 are assembled to form the electrode assembly 10, the first direction c is arranged parallel to the height direction of the electrode assembly 10, and the second direction d is arranged parallel to the width direction a of the electrode assembly 10.

[0123] The second bonding region 113 and the third bonding region 114 can also be bonded by arranging a rubber strip 1311. The second bonding region 113 is arranged at one end of each positive electrode plate 11 or each negative electrode plate 12 along the first direction c, and the third bonding region 114 is respectively arranged at opposite ends of each positive electrode plate 11 or each negative electrode plate 12 along the second direction d.

[0124] Thus, when each positive electrode plate 11, each negative electrode plate 12 and the adjacent sub-separator 132 are stacked, the second bonding region 113 and the third bonding region 114 can bond each positive electrode plate 11, each negative electrode plate 12 and the adjacent sub-separator 132. Thus, the second bonding region 113 and the third bonding region 114 cause each positive electrode plate 11 and the adjacent sub-separator 132 to jointly enclose a first accommodating cavity 14 with one side open, and cause each negative electrode plate 12 and the adjacent sub-separator 132 to jointly enclose a second accommodating cavity 15 with one side open.

[0125] By arranging the second bonding region 113 and the third bonding region 114, each positive electrode plate 11 and the adjacent sub-separator 132 can be bonded to each other and enclose the first accommodating cavity 14 to facilitate the accommodation of the first electrolyte; and each negative electrode plate 12 and the adjacent sub-separator 132 can be bonded to each other and enclose the second accommodating cavity 15 to facilitate the accommodation of the second electrolyte.

[0126] As Figure 8 and Figure 9 shown, in some embodiments, the second bonding regions 113 are respectively arranged on the positive electrode plates 11 and the negative electrode plates 12 along the first direction c, and the fourth bonding regions 1321 are arranged on each sub-separator 132 along the second direction d intersecting the first direction c. Among them, the second bonding region 113 and the fourth bonding region 1321 are respectively bonded to the adjacent sub-separator 132 to correspondingly form the first accommodating cavity 14 and the second accommodating cavity 15.

[0127] When the second bonding region 113 extends along the first direction c on each positive electrode plate 11 and each negative electrode plate 12, the fourth bonding region 1321 extending along the second direction d can be arranged on each layer of sub-separator 132. At this time, the positive electrode plate 11 or the negative electrode plate 12 is bonded to the adjacent sub-separator 132 through the second bonding region 113 thereon, and the adjacent two layers of sub-separators 132 are bonded in the second direction d through the fourth bonding region 1321. When the positive electrode plate 11, the negative electrode plate 12 and the sub-separator 132 are stacked, the first accommodating cavity 14 can also be enclosed between the positive electrode plate 11 and the adjacent sub-separator 132 through the second bonding region 113 and the fourth bonding region 1321, and the second accommodating cavity 15 can also be enclosed between the negative electrode plate 12 and the adjacent sub-separator 132 through the second bonding region 113 and the fourth bonding region 1321.

[0128] The second bonding area 113 is disposed on the positive electrode sheet 11 and the negative electrode sheet 12, and the fourth bonding area 1321 is disposed on each layer of the sub-separator 132. On the premise of realizing the bonding between the positive electrode sheet 11 and the adjacent sub-separator 132 to enclose and form the first accommodating cavity 14, and the bonding between the negative electrode sheet 12 and the adjacent sub-separator 132 to enclose and form the second accommodating cavity 15, the bonding areas on the positive electrode sheet 11 and the negative electrode sheet 12 are 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, thereby improving the reaction efficiency.

[0129] Specifically, the second bonding area 113, the third bonding area 114, and the fourth bonding area 1321 can all be bonded by setting rubber strips. Among them, the rubber strip of the second bonding area 113 extends along the first direction c, and the rubber strips of the third bonding area 114 and the fourth bonding area 1321 both extend along the second direction d.

[0130] Thereby, each positive electrode sheet 11 and each negative electrode sheet are bonded to the adjacent sub-separator 132, and the first accommodating cavity 14 and the second accommodating cavity 15 are successfully enclosed and formed.

[0131] In some embodiments, the air permeability of the separator 13 ≥ 20000 s / 100 cc, and the ionic conductivity of the separator 13 ≥ 0.1 mS / cm 2 。

[0132] Specifically, the air permeability of the separator 13 has the meaning well-known in the art. The air permeability of the separator 13 is comprehensively affected by the internal pore structure such as the porosity, pore diameter, pore shape, and pore tortuosity of the separator 13, which reflects the degree of blocking of other components except active ions in the electrolytes on both sides of the separator 13, and can be tested by methods known in the art. For example, the separator 13 is punched into small round pieces with a diameter of 50 mm, and the air permeability of the small round pieces is tested by using a Wangyan air permeability meter (Asahi Seiko model EG01-55-1MR). The test pressure is controlled at 1.21 kPa, and the time (seconds, s) taken for 100 cc of gas (air) to pass through is measured, and the air permeability of the separator is obtained, with the unit of s / 100 cc.

[0133] The ionic conductivity of the separator 13 refers to the ability of the separator 13 to conduct active ions (such as lithium ions), and the following method can be specifically used for testing:

[0134] The separator 13 is blanked into small round pieces with a diameter of 16 mm, the thickness d is measured and recorded. The cut small round pieces are assembled in the order of stainless steel sheet, separator film, and stainless steel sheet, and at the same time, a small amount (10 μL) of electrolyte (the solvent is EC:EMC with a volume ratio of 3:7, and the lithium salt is 1 mol / L LiPF6) is dropped and encapsulated in a coin cell. The electrochemical impedance spectroscopy of the Solartron 1470E CellTest multi-channel electrochemical workstation is used for testing. The test voltage can be 10 mV, and the test frequency can be 0.1 Hz to 100 KHz. A Nyquist plot is drawn. The Zview software is used to analyze the obtained Nyquist plot by using the equivalent circuit curve fitting method. The intersection point of the straight line and the horizontal axis is denoted as R. The ionic conductivity is calculated using the formula λ = d / RS; where λ represents the ionic conductivity, d represents the thickness of the separator film, R represents the ionic resistance, and S represents the cross-sectional area of the small round piece.

[0135] Therefore, the air permeability of the separator 13 will affect the penetration rate of the electrolyte in the separator 13. If the penetration rate of the electrolyte in the separator 13 is too high, it means that the electrolyte is more likely to penetrate out from the first accommodation cavity 14 or the second accommodation cavity 15 through the separator 13, thereby reducing the sealing performance of the first accommodation cavity 14 for the first electrolyte and the sealing performance of the second accommodation cavity 15 for the second electrolyte.

[0136] The ionic conductivity of the separator 13, on the other hand, will affect the conduction of lithium ions between the positive and negative electrodes. By limiting the range of the ionic conductivity of the separator 13, active ions can be smoothly conducted between the first accommodation cavity 14 and the second accommodation cavity 15, thereby smoothly forming a circuit between the positive and negative electrodes.

[0137] As a preferred range, the ionic conductivity of the separator 13 can be set to ≥0.3 mS / cm 2 。

[0138] Therefore, setting the air permeability and ionic conductivity of the separator 13 within the above ranges can further improve the sealing performance of the first accommodation cavity 14 for the first electrolyte and the sealing performance of the second accommodation cavity 15 for the second electrolyte. In this way, the first electrolyte can act more stably on the positive electrode in the first accommodation cavity 14, while the second electrolyte can act more stably on the negative electrode in the second accommodation cavity 15.

[0139] In addition, the separator 13 can be obtained by subjecting conventional porous PP, PE, PI-based membranes to densification filling treatment of their porous structures, or by coating and densifying membranes with PEO or PVDF-based materials, or by subjecting ion-selective permeable membranes to lithiation treatment, all of which can achieve the above effects and will not be elaborated here.

[0140] Such asFigure 1 and Figure 10 As shown in Figure 10 , based on the same concept as the above-mentioned electrode assembly 10, the present application also provides a battery cell 100, including the electrode assembly as described above.

[0141] Specifically, the battery cell 100 is a soft-pack battery.

[0142] In some embodiments, the battery cell 100 further includes a first electrolyte (not shown in the figure) and a second electrolyte (not shown in the figure). Among them, the first electrolyte is an electrolyte acting on the positive electrode and is filled in the first accommodation cavity 14, and the second electrolyte is an electrolyte acting on the negative electrode and is filled in the second accommodation cavity 15.

[0143] The compositions and contents 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 electrode plates 12, so that the components of the first electrolyte can better promote the positive electrode plate 11. And the components of the second electrolyte can better promote the negative electrode plate 12.

[0144] Furthermore, by using the first accommodation cavity 14 and the second accommodation cavity 15 to separately accommodate the first electrolyte and the second electrolyte, the first electrolyte and the second electrolyte can react with the positive electrode plate 11 and the negative electrode plate 12 independently of each other, reducing the influence of the first electrolyte on the negative electrode plate 12 and the influence of the second electrolyte on the positive electrode plate 11.

[0145] Through the above structure, the first electrolyte can be better accommodated in the first accommodation cavity 14, the second electrolyte can be better accommodated in the second accommodation cavity 15, and the influence of the first electrolyte on the negative electrode plate 12 and the influence of the second electrolyte on the positive electrode plate 11 can be reduced.

[0146] In some embodiments, at least one of the first electrolyte and the second electrolyte is a gel electrolyte.

[0147] Specifically, a gel electrolyte means that the state of the electrolyte is gel-like. In this way, the fluidity of the electrolyte can be effectively reduced, and further the probability of mixing between the first electrolyte and the second electrolyte can be reduced, so that 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.

[0148] Furthermore, the first electrolyte can be set as a gel electrolyte, or the second electrolyte can be set as a gel electrolyte, or both the first electrolyte and the second electrolyte can be set as gel electrolytes.

[0149] Through the above structure, starting from the inherent characteristics of the electrolyte, the probability of mixing between the first electrolyte and the second electrolyte can be further reduced, 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.

[0150] In some embodiments, the first electrolyte and / or 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 an acrylic monomer unit and / or an acrylate monomer unit.

[0151] Specifically, the first monomer unit can undergo a polymerization reaction under the action of an initiator to form gelation, so that the first electrolyte and / or the second electrolyte can smoothly form a gel electrolyte.

[0152] The first monomer unit includes acrylic monomer units and / or acrylate monomer units. The acrylic monomer units may specifically include, but are not limited to, one or more of acrylic acid and methacrylic acid; the acrylate monomer units may specifically include, but are not limited to, one or more of methyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, butyl acrylate, isodecyl acrylate, isooctyl acrylate, lauryl acrylate, isobornyl acrylate, isobornyl methacrylate, ethoxyethoxyethyl acrylate, cyanoacrylate, caprolactone acrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, ethoxylated tetrahydrofurfuryl acrylate, trimethylolpropane triacrylate, 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(propoxylated) neopentyl glycol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polycyclohexyl acrylate, methoxypolyethylene glycol acrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, methoxypolyethylene glycol methacrylate, pentaerythritol triacrylate, propoxylated glycerol triacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, bis(trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, 4(ethoxy) pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate.

[0153] The initiator may include, but is not limited to, peroxide initiators and / or azo initiators, for example, one or more of acyl peroxides (benzoyl peroxide, lauroyl peroxide), persulfates (ammonium persulfate), and azo initiators (azobisisobutyronitrile, azobisisoheptonitrile).

[0154] Thus, the first electrolyte and / or 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 the reaction efficiency.

[0155] In some embodiments, the polymer matrix further comprises a homopolymer or copolymer of a second monomer unit, and the second monomer unit comprises 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.

[0156] In some embodiments, the ethylenically unsaturated carbonate monomer unit comprises one or more of vinylene carbonate (VC), ethylene ethylene carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluorinated ethylene carbonate, and chlorinated ethylene carbonate.

[0157] In some embodiments, the ethylenically unsaturated sulfate monomer unit comprises one or more of ethylene vinyl sulfite, vinyl sulfite, 4-methyl vinyl sulfate, and 4-ethyl vinyl sulfate.

[0158] In some embodiments, the ethylenically unsaturated sulfonate monomer unit comprises one or more of 1,3-propane sultone, allyl p-toluenesulfonate, 2,2-difluoroethyl 4-methylbenzenesulfonate, and methylene methanesulfonate cyclic ester.

[0159] In some embodiments, the ethylenically unsaturated phosphate monomer unit comprises one or more of dimethyl vinyl phosphate, diethyl vinyl phosphate, diethyl allyl 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-trifluoropropenyl ethyl phosphate.

[0160] In some embodiments, the ethylenically unsaturated carboxylate monomer unit comprises vinyl acetate.

[0161] In some embodiments, the ethylenically unsaturated sulfone monomer unit comprises one or more of methyl vinyl sulfone, ethyl vinyl sulfone, cyclobutene sulfone, sulfolane, and cycloethyl sulfoxide.

[0162] In some embodiments, the ethylenically unsaturated nitrile monomer unit comprises one or more of acrylonitrile, succinonitrile, glutaronitrile, and adiponitrile.

[0163] In some embodiments, the ethylenically unsaturated ether monomer unit comprises one or more of 1,3-dioxolane, ethylene oxide, 1,2-epoxypropane, 4-methyl-1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, ethylene glycol diglycidyl ether, and triethylene glycol divinyl ether.

[0164] Specifically, during the preparation of the first electrolyte and the second electrolyte, the mass ratio among the base electrolyte, the first monomer unit, the second monomer unit, and the initiator can be set as base electrolyte∶first monomer unit∶second monomer unit∶initiator = (60% - 98%)∶(1% - 20%)∶(0% - 20%)∶(0.1% - 1%).

[0165] Among them, the base electrolyte is composed of an electrolyte salt and a solvent. The electrolyte salt is a lithium salt or a sodium salt. The lithium salts include but are 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 difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorophosphate, lithium difluoro(dioxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate. The sodium salts include but are not limited to one or several of NaPF6, NaClO4, NaBCl4, NaSO3CF3, and Na(CH3)C6H4SO3. The concentration is 0.3 - 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.

[0166] The above mass ratio range can make the first electrolyte and / or the second electrolyte gel better and make its structure more stable.

[0167] In some embodiments, the battery cell 100 further includes an outer encapsulation body 20, and the electrode assembly 10 is disposed inside the outer encapsulation body 20.

[0168] Specifically, the outer encapsulation body 20 can be but is not limited to being set as an aluminum - plastic film, a PP film, or a PC film. The outer encapsulation body 20 covers the outer periphery of the electrode assembly 10 and can play a protective role for the electrode assembly 10.

[0169] In some embodiments, the battery cell 100 further includes a fifth bonding area 30 disposed between the inner wall of the outer encapsulation body 20 and the outermost diaphragm 13 in the electrode assembly 10. The fifth bonding area 30 is used to divide the inner space of the outer encapsulation body 20 into two mutually independent first part 21 and second part 22. Among them, the first part 21 communicates with the first accommodation cavity 14, and the second part 22 communicates with the second accommodation cavity 15.

[0170] 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 time, a fifth bonding area 30 is provided between the separator 13 on the outermost side of the electrode assembly 10 and the inner wall of the outer package 20, so that the outermost separator 13 can be bonded to the inner wall of the outer package 20. In this way, the interior of the outer package 20 is divided into an independent first part 21 and a second part 22.

[0171] When the separator 13 is folded around the positive electrode sheet 11 and the negative electrode sheet 12, the opening directions of the first accommodation cavity 14 and the second accommodation cavity 15 are opposite. Thus, the first part 21 can communicate with the first accommodation cavity 14, the second part 22 can communicate with the second accommodation cavity 15, and after the first part 21 and the first accommodation cavity 14 communicate, the space after the second part 22 and the second accommodation cavity 15 communicate is not connected to each other, and the electrolytes in the two spaces are independently arranged and do not affect each other.

[0172] By providing the fifth bonding area 30, the internal space of the outer package 20 can be divided into an independent first part 21 and a second part 22, expanding the accommodation space for the electrolyte and being able to temporarily store the electrolyte during the electrolyte penetration process.

[0173] In some embodiments, the electrode assembly 10 has a tab portion and a body portion. A first heat-sealing area 40 is provided on one side edge of the tab portion of the electrode assembly 10 and on the side edge opposite to the tab portion, a second heat-sealing area 50 is provided on the opening side edge of the first accommodation cavity 14, and a third heat-sealing area 60 is provided on the opening side edge of the second accommodation cavity 15. Among them, the first heat-sealing area 40, the second heat-sealing area 50, and the third heat-sealing area 60 are all used for heat-sealing with the outer package.

[0174] Specifically, the tab portion is a structure jointly 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 jointly composed of the bodies of all the positive electrode sheets 11 and the bodies of all the negative electrode sheets 12.

[0175] 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 time, since the first heat-sealing area 40 is provided on one side edge where the tab portion of the electrode assembly 10 is located and on the side edge opposite to the tab portion, the side edge where the tab portion of the electrode assembly 10 is located and the side edge opposite to the tab portion can be heat-sealed to the outer package 20 through the first heat-sealing area 40.

[0176] After heat-sealing the first heat-sealing area 40, the remaining two side edges are respectively the opening of the first accommodating cavity 14 and the opening of the second accommodating cavity 15. Then, the first electrolyte is filled into the first accommodating cavity 14 through the opening of the first accommodating cavity 14, and the first accommodating cavity 14 is heat-sealed through the second heat-sealing area 50. Then, the second electrolyte is filled into the second accommodating cavity 15 through the opening of the second accommodating cavity 15, and the second accommodating cavity 15 is heat-sealed through the third heat-sealing area 60.

[0177] 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 accommodating cavity 14, and the second electrolyte can be more stably accommodated in the second accommodating cavity 15.

[0178] Based on the same concept as the above battery cell 100, the present application also provides a battery including the battery cell 100 as described above.

[0179] Based on the same concept as the above battery, the present application also provides an electrical device including the battery as described above.

[0180] Based on the same concept as the above battery cell 100, the present application also provides a method for manufacturing a battery cell 100, including the following steps:

[0181] Stack the positive electrode sheet 11 and the negative electrode sheet 12 in sequence;

[0182] Provide a bonding area on the separator 13, and fold the separator 13 in a Z-shaped structure around the adjacent positive electrode sheet 11 and negative electrode sheet 12 to form an 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 arranged and do not communicate with each other;

[0183] Alternatively, the separator 13 is slit into multiple sub-separators 132, a bonding area is provided on the positive electrode sheet 11 and the negative electrode sheet 12, or a bonding area is provided on the positive electrode sheet 11, the negative electrode sheet 12, and the sub-separator 132. One sub-separator 132 is provided between each adjacent positive electrode sheet 11 and negative electrode sheet 12 to form an 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 arranged and do not communicate with each other;

[0184] Place the electrode assembly 10 inside the outer package 20.

[0185] In some embodiments, the above manufacturing method further includes the following steps:

[0186] Bond and fix the outermost separator 13 in the electrode assembly 10 to the inner wall of the outer package 20.

[0187] Thermally seal the side edges of the electrode assembly 10 where the tab ears are located and the side edges opposite to the tab ears to the outer package 20.

[0188] Fill the first accommodation cavity 14 with the first electrolyte, and then thermally seal the opening side edge of the first accommodation cavity 14.

[0189] Fill the second accommodation cavity 15 with the second electrolyte, and then thermally seal the opening side edge of the second accommodation cavity 15.

[0190] Specifically, when the separator 13 is set as a continuous separator and is folded around each adjacent pair of positive electrode plates 11 and negative electrode plates 12, first, before the separator 13 is folded, adhesive strips 1311 are respectively arranged on both surfaces in the thickness direction of the separator 13, and the adhesive strips 1311 on each surface are respectively located at both ends along the width direction a of the separator 13, and the adhesive strips 1311 extend along the length direction b of the separator 13.

[0191] When the separator 13 is folded around each adjacent pair of positive electrode plates 11 and negative electrode plates 12, the adhesive strips 1311 play a bonding role between each adjacent two layers of the separator 13, so that both sides of the separator 13 along its width direction a are bonded and sealed through the adhesive strips 1311. At this time, a first accommodation cavity 14 with one side open is formed between each positive electrode plate 11 and the adjacent separator 13, and a second accommodation cavity 15 with one side open is formed between each negative electrode plate 12 and the adjacent separator 13, and the opening directions of the first accommodation cavity 14 and the second accommodation cavity 15 are opposite.

[0192] When the separator 13 is a stacked sub-separator 132, first, a second bonding area 113 is arranged on each layer of the positive electrode plate 11 and the negative electrode plate 12, and then a third bonding area 114 is arranged on each layer of the positive electrode plate 11 and the negative electrode plate 12, or a fourth bonding area 1321 is arranged on each layer of the sub-separator 132. Through the second bonding area 113 and the third bonding area 114, or through the second bonding area 113 and the fourth bonding area 1321, a first accommodation cavity 14 with a first opening 141 is enclosed between the positive electrode plate 11 and the adjacent sub-separator 132, and a second accommodation cavity 15 with a second opening 151 is enclosed between the negative electrode plate 12 and the adjacent sub-separator 132.

[0193] After the electrode assembly 10 is assembled, the electrode assembly 10 is placed inside the outer package 20, and the outermost side of the separator 13 is bonded to the inner wall of the outer package 20 through the fifth bonding area 30, so as to divide the inner space of the outer package 20 into a first part 21 and a second part 22, enabling the electrode assembly 10 to be stably arranged inside the outer package 20.

[0194] Further, one side edge where the tab of the electrode assembly 10 is located and the side edge opposite to the tab are respectively heat-sealed to the outer package 20 through the first heat-sealing area 40. After the first heat-sealing area 40 is heat-sealed, the remaining two side edges are respectively the openings of the first accommodation cavity 14 and the second accommodation cavity 15.

[0195] Then, the first electrolyte is filled into the first accommodation cavity 14 through the opening of the first accommodation cavity 14, and the side edge of the opening of the first accommodation cavity 14 is heat-sealed through the second heat-sealing area 50. Then, the second electrolyte is filled into the second accommodation cavity 15 through the opening of the second accommodation cavity 15, and the side edge of the opening of the second accommodation cavity 15 is heat-sealed through the third heat-sealing area 60.

[0196] In order to test and verify the battery cell provided by the present application, the positive and negative electrode plates, the separator, and the electrolyte are respectively prepared according to the following method to form a comparative example and an example.

[0197] As Figure 1 shown, when the separator is set as a continuous separator, the positive electrode plate, the negative electrode plate, and the separator are assembled together to form a battery. The specific preparation process of the battery is as follows:

[0198] (1) Preparation of the positive electrode plate

[0199] The positive electrode active material lithium manganate (LiMn2O4), the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) are fully stirred and mixed evenly in an N-methylpyrrolidone solvent according to a weight ratio of 95:3:2, and then coated on both sides of an aluminum foil. After drying and cold pressing, a positive electrode plate is obtained, where the coating amount per unit area on both sides is 0.27 g / 1540.25 mm 2 , and the electrode plate is punched into a positive electrode plate with a main active area of 49 * 87 mm.

[0200] (2) Preparation of the negative electrode plate

[0201] Graphite, conductive carbon, and styrene-butadiene rubber (SBR) are dissolved in deionized water and mixed according to a weight ratio of 95:3:2, and a negative electrode slurry is obtained under the action of a vacuum mixer; the negative electrode slurry is evenly coated on both sides of a copper foil; the copper foil is air-dried at room temperature and then transferred to an oven at 120 °C for drying for 1 h, and then obtained a negative electrode plate through cold pressing and slitting, where the coating amount per unit area on both sides is 0.17 g / 1540.25 mm2 , the anode plate is punched into an anode plate with a main active area of 51*93 mm.

[0202] (3) Preparation of the separator

[0203] In Comparative Example 1, a traditional PE separator is used. Among them, the thickness of the PE separator is 12 μm, the air permeability is 146 s / 100 cc, and the ionic conductivity is 0.62 mS / cm 2 . In the examples of the present application, the separator 13 provided by the present application is prepared by dipping a common PE separator in a treatment solution and then performing UV curing. The separator 13 is used as the separator in Comparative Example 2, Examples 1, 2, 3, and 4. After the treatment, the air permeability of the separator is 26469 s / 100 cc, and the conductivity is 0.56 mS / cm 2 ; The two separators are cut into a width of 108 mm for standby.

[0204] Among them, the components of the above dipping treatment solution include EC, EMC, LiPF6, ethoxylated trimethylolpropane triacrylate, vinyl acetate, benzoyl peroxide (BPO), and the mass ratio of EC:EMC:LiPF6: ethoxylated trimethylolpropane triacrylate: vinyl acetate: benzoyl peroxide (BPO) = 20:30:19.5:10:20:0.5. The curing process is to irradiate with ultraviolet light with a wavelength of 365 nm, and the power is 800 mW / cm 2 , and the treatment time is 2 s.

[0205] (4) Preparation of the electrolyte

[0206] Positive electrode electrolyte: Dissolve LiFSI in dimethyl sulfoxide to prepare electrolyte A with a concentration of 1 M / L;

[0207] Positive electrode side gel electrolyte (first electrolyte): Mix according to the mass ratio of electrolyte A: polyethylene glycol dimethacrylate: VC = 80%:10%:10%, and add azobisisobutyronitrile (AIBN) with a mass fraction of 0.4% of the total mass of the mixed solution, denoted as electrolyte A-GEL;

[0208] Negative electrode electrolyte: Mix EC:EMC:DMC according to a volume ratio of 1:1:1, and add LiFSI to prepare electrolyte B with a lithium salt concentration of 1 M / L;

[0209] Negative electrode side gel electrolyte (second electrolyte): Mix according to the mass ratio of electrolyte A: polyethylene glycol dimethacrylate: VC = 80%:10%:10%, and then add AIBN with a mass fraction of 0.4% of the total mass of the mixed solution, denoted as electrolyte B-GEL.

[0210] (5) Assemble to form a battery

[0211] Among them, the battery assembly steps in Embodiment 1, Embodiment 2, Embodiment 3, and Embodiment 4 are as follows:

[0212] The prepared positive electrode sheet and negative electrode sheet are stacked in sequence, and the separator is folded and wound in a Z-shaped structure between every two adjacent positive electrode sheets and negative electrode sheets in sequence to play an isolation role. Among them, the adjacent two layers of separators on both sides of each positive electrode sheet are bonded through the first bonding area 131, so that the adjacent two layers of separators are bonded to form the first accommodation cavity 14. The adjacent two layers of separators on both sides of each negative electrode sheet are bonded through the first bonding area 131, so that the adjacent two layers of separators are bonded to form the second accommodation cavity 15, and the opening direction of the second accommodation cavity 15 is opposite to that of the first accommodation cavity 14.

[0213] The stacked negative electrode sheet, separator, and positive electrode sheet are together loaded into the aluminum-plastic film, and the outermost side of the separator 13 and the inner wall of the aluminum-plastic film are bonded through the fifth bonding area 30, and the internal space of the aluminum-plastic film is divided into a first part 21 and a second part 22.

[0214] The aluminum-plastic film is heat-sealed with the side edges where the pole lugs are located on the electrode assembly 10 and the side edge opposite to the pole lugs through the first heat-sealing area 40. Then, the first electrolyte is filled into the first accommodation cavity 14 through the opening of the first accommodation cavity 14, and the opening side edge of the first accommodation cavity 14 is heat-sealed through the second heat-sealing area 50. Then, the second electrolyte is filled into the second accommodation cavity 15 through the opening of the second accommodation cavity 15, and the opening side edge of the second accommodation cavity 15 is heat-sealed through the third heat-sealing area 60, and finally the battery is assembled.

[0215] As Figure 2 shown, when the separator is set as multiple sub-separators, the positive electrode sheet, negative electrode sheet, and sub-separators are assembled together to form a battery. Among them, the preparation processes of the positive electrode sheet, negative electrode sheet, sub-separators, and electrolyte are the same as those of the positive electrode sheet, negative electrode sheet, separator, and electrolyte of the above Z-shaped structure separator.

[0216] During the assembly process of the battery, first, the separator is cut to form multiple sub-separators 132. The prepared positive electrode sheet and negative electrode sheet are stacked in sequence, and each sub-separator 132 is clamped between every two adjacent positive electrode sheets and negative electrode sheets.

[0217] A second bonding region 113 is provided on each layer of the positive electrode sheet 11 and the negative electrode sheet 12, and a third bonding region 114 is provided on each layer of the positive electrode sheet 11 and the negative electrode sheet 12. Through the second bonding region 113 and the third bonding region 114, a first accommodation cavity 14 having a first opening 141 is enclosed between the positive electrode sheet 11 and the adjacent sub-separator 132, and a second accommodation cavity 15 having a second opening 151 is enclosed between the negative electrode sheet 12 and the adjacent sub-separator 132.

[0218] The stacked negative electrode sheet, sub-separator, and positive electrode sheet are all loaded into the aluminum-plastic film, and the outermost sub-separator is bonded to the inner wall of the aluminum-plastic film through the fifth bonding region 30. At this time, the first opening 141 is arranged to face left, and the second opening 151 is arranged to face right.

[0219] The aluminum-plastic film is heat-sealed with the side edges where the pole lugs are located on the electrode assembly 10 and the side edge opposite to the pole lugs through the first heat-sealing region 40. Then, the first electrolyte is filled into the first accommodation cavity 14 through the opening of the first accommodation cavity 14, and the opening side edge of the first accommodation cavity 14 is heat-sealed through the second heat-sealing region 50. The second electrolyte is filled into the second accommodation cavity 15 through the opening of the second accommodation cavity 15, and the opening side edge of the second accommodation cavity 15 is heat-sealed through the third heat-sealing region 60, and finally a battery is assembled.

[0220] The battery assembly steps in Comparative Example 1 and Comparative Example 2 are as follows:

[0221] The prepared positive electrode sheet and negative electrode sheet are stacked in sequence, and the separator is folded in a Z-shaped structure and wound around each adjacent pair of positive electrode sheets and negative electrode sheets to play an isolation role.

[0222] Then, the stacked negative electrode sheet, separator, and positive electrode sheet are all loaded into the aluminum-plastic film, positive electrode electrolyte and negative electrode electrolyte are filled into the aluminum-plastic film, and the aluminum-plastic film is encapsulated, and finally a battery is assembled.

[0223] It can be understood that the batteries in Comparative Example 1 and Comparative Example 2 are assembled in a traditional manner.

[0224] Furthermore, a life test is carried out in a constant temperature environment of 25°C. The specific process is as follows: First, it is left standing for 5 min, and discharged to 3 V at 0.5C (1500 mA). After standing for 5 min, it is charged to 4.3 V at 1 / 3C, and then constantly charged at 4.3 V until the current is less than or equal to 100 mA. After standing for 5 min, it is discharged to 3 V at 1 / 3C. At this time, the discharge capacity is the initial discharge capacity, denoted as D0. Subsequently, according to the above process, a cycle test is carried out in the 3V - 4.3V range. 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. The data obtained during the test are as follows in the table:

[0225]

[0226] Among them, continuous diaphragms are used in Comparative Example 1, Comparative Example 2, Example 1, and Example 2, that is, the diaphragm is folded in a Z-shaped structure and arranged between the positive electrode plate and the negative electrode plate. Sub-diaphragms are used in Example 3 and Example 4, that is, the diaphragm includes multiple sub-diaphragms stacked layer by layer. It can be clearly seen from the test data that the cycle life of the soft-pack battery cell provided by the present application is significantly improved.

[0227] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0228] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. An electrode assembly, characterized in that, Comprising: At least one positive electrode sheet; At least one negative electrode sheet, which is stacked alternately with each of the positive electrode sheets; And A separator, which is sandwiched between every two adjacent positive electrode sheets and the negative electrode sheet; Wherein, a first accommodation cavity is provided between the positive electrode sheet and the adjacent separator, and a second accommodation cavity is provided between the negative electrode sheet and the adjacent separator, and the first accommodation cavity and the second accommodation cavity are independently arranged and not communicated with each other.

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

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

4. The electrode assembly according to claim 3, characterized in that, The first bonding area is located on the opposite two side surfaces in the thickness direction of the separator, and the first bonding area on each side surface includes rubber strips respectively arranged at both ends of the separator along the width direction of the separator, and the rubber strips extend along the length direction of the separator.

5. The electrode assembly according to claim 4, wherein The size of the separator in the width direction is larger than the sizes of the adjacent positive electrode sheet and the negative electrode sheet in the width direction, and the area where the separator exceeds the positive electrode sheet and the negative electrode sheet is set as the first bonding area.

6. The electrode assembly according to claim 5, characterized in that Both the positive electrode sheet and the negative electrode sheet include a body and a tab protruding from at least one side of the body. The body is located between every two adjacent layers of the separator, and the tab extends outside the separator; Wherein, the rubber strips at at least one end in the width direction of the separator are used for bonding every two adjacent layers of the separator and the tab located between the two adjacent layers of the separator.

7. The electrode assembly according to claim 2, characterized in that, The separator includes multiple sub-separators stacked, 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.

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; Wherein, the second bonding area and the third bonding area are respectively bonded to the adjacent sub-separators to correspondingly form the first accommodation cavity and the second accommodation cavity.

9. The electrode assembly according to claim 7, characterized in that, 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; Wherein, the second bonding area and the fourth bonding area are respectively bonded to the adjacent sub-separators to correspondingly form the first accommodation cavity and the second accommodation cavity.

10. The electrode assembly according to claim 7, wherein, Both the positive electrode sheet and the negative electrode sheet include a body and a tab protruding from at least one side of the body. The body is located between every two adjacent layers of the sub-separators, and the tab extends outside each sub-separator.

11. The electrode assembly according to any one of claims 1-10, characterized in that, The air permeability of the separator is ≥ 20000 s / 100 cc, and the ionic conductivity of the separator is ≥ 0.1 mS / cm 2 .

12. A battery cell, characterized in that, Comprising the electrode assembly according to any one of claims 1-11.

13. According to the battery cell of claim 12, the battery cell is a soft-pack battery.

14. The battery cell according to claim 12 or 13, characterized in that, It further includes a first electrolyte and a second electrolyte. The first electrolyte is filled in the first accommodation cavity, and the second electrolyte is filled in the second accommodation cavity. Wherein, the composition components and / or contents of the first electrolyte and the second electrolyte are different.

15. The battery cell according to any one of claims 12-14, characterized in that, At least one of the first electrolyte and the second electrolyte is a gel electrolyte.

16. The battery cell according to any one of claims 12-15, characterized in that, The first electrolyte and / or the second electrolyte includes a basic electrolyte and a polymer matrix; the polymer matrix includes a homopolymer or copolymer of a first monomer unit, and the first monomer unit includes an acrylic monomer unit and / or an acrylate monomer unit.

17. The battery cell according to claim 16, characterized in that, 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.

18. The battery cell according to any one of claims 12-17, characterized in that, The battery cell further includes an outer encapsulation body, and the electrode assembly is disposed inside the outer encapsulation body.

19. The battery cell according to claim 18, wherein, The battery cell further includes a fifth bonding area disposed between the inner wall of the outer encapsulation body and the outermost diaphragm of the electrode assembly. The fifth bonding area is used to divide the internal space of the outer encapsulation body into two independent parts, a first part and a second part; Wherein, the first part communicates with the first accommodation cavity, and the second part communicates with the second accommodation cavity.

20. The battery cell according to claim 19, wherein The electrode assembly has a tab portion and a body portion. A first heat-sealing area is provided on one side edge of the tab portion of the electrode assembly and on the side edge opposite to the tab portion. A second heat-sealing area is provided on the opening side edge of the first accommodation cavity, and a third heat-sealing area is provided on the opening side edge of the second accommodation cavity; Wherein, 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 encapsulation body.

21. A battery, characterized in that, It includes the battery cell according to any one of claims 12-20.

22. An electric device, characterized in that, It includes the battery according to claim 21.

23. A preparation method of a battery cell, characterized in that, It includes the following steps: Stack the positive electrode sheet and the negative electrode sheet in sequence; Set a bonding area on the diaphragm, and fold the diaphragm in a Z-shaped structure around the adjacent positive electrode sheet and negative electrode sheet to form an electrode assembly. A first accommodation cavity is formed between the positive electrode sheet and the adjacent diaphragm through the bonding area, and a second accommodation cavity is formed between the negative electrode sheet and the adjacent diaphragm through the bonding area. The first accommodation cavity and the second accommodation cavity are independently arranged and do not communicate with each other; Alternatively, the separator is slit into multiple sub-separators, and bonding areas are provided on the positive electrode sheet and the negative electrode sheet, or bonding areas are provided on the positive electrode sheet, the negative electrode sheet, and the sub-separators. One sub-separator is disposed between each adjacent positive electrode sheet and negative electrode sheet to form an electrode assembly. A first accommodation cavity is formed between the positive electrode sheet and the adjacent separator through the bonding area, and a second accommodation cavity is formed between the negative electrode sheet and the adjacent separator through the bonding area. The first accommodation cavity and the second accommodation cavity are independently arranged and do not communicate with each other; The electrode assembly is placed inside the outer package.

24. The preparation method according to claim 23, wherein, After the step of placing the electrode assembly inside the outer package, the following steps are further included: Bond and fix the outermost separator in the electrode assembly to the inner wall of the outer package; Thermally seal the side edges where the tab ears of the electrode assembly are located and the side edges opposite to the tab ears to the outer package; Fill the first accommodation cavity with a first electrolyte, and then thermally seal the opening side edge of the first accommodation cavity; Fill the second accommodation cavity with a second electrolyte, and then thermally seal the opening side edge of the second accommodation cavity.

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