Battery cell and manufacturing method therefor, battery device, and electric device

Abstract

A battery cell and a manufacturing method therefor, a battery device, and an electric device. The battery cell comprises an electrode sheet and a separator; the electrode sheet comprises a current collector and an electrode film layer located on at least one side of the current collector; the separator comprises a base film and a coating layer located on at least one side of the base film; and the electrode film layer and / or the coating layer comprises a gel region and a non-gel region, and the gel region comprises a gel electrolyte. The battery cell has improved cycle performance.

Description

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

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411441128.1, filed on October 15, 2024, entitled “Battery cell and method of preparation thereof, battery device, power device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, specifically to a battery cell and its preparation method, a battery device, and an electrical device. Background Technology

[0004] Batteries are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric car toys, electric toy ships, electric toy airplanes, and power tools.

[0005] In the development of battery cells, improving the cycle performance of battery cells is one of the urgent problems to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a battery cell, its preparation method, a battery device, and an electrical device, which can improve the cycle performance of the battery cell.

[0007] In a first aspect, embodiments of this application provide a battery cell, including an electrode sheet and a separator. The electrode sheet includes a current collector and an electrode film layer located on at least one side of the current collector. The separator layer includes a base film and a coating layer located on at least one side of the base film. The electrode film layer and / or the coating layer include a gel region and a non-gel region, wherein the gel region contains a gel electrolyte.

[0008] A gel region containing a gel electrolyte is formed on the electrode plates and / or separator, thus incorporating the gel electrolyte into the electrode plates and / or separator. Due to its solid-like structural properties, the gel electrolyte can adhere tightly to the electrode plates and / or separator, preventing it from being squeezed out due to reduced porosity during battery cell charge-discharge cycles. This allows the electrode plates and / or separator to maintain high electrolyte wettability. Furthermore, the high thermal stability of the gel electrolyte reduces side reactions of the electrolyte at high temperatures, minimizing electrolyte consumption and thereby improving the battery cell's lifespan and cycle performance.

[0009] In some embodiments, the area of ​​the gel region accounts for 10% to 50% of the total area of ​​the electrode film.

[0010] In some embodiments, the area of ​​the gel region accounts for 20% to 30% of the total area of ​​the electrode film.

[0011] In some embodiments, the gel region is located in the middle region of the electrode sheet.

[0012] In some embodiments, the area of ​​the gel region accounts for 10% to 50% of the total area of ​​the coating.

[0013] In some embodiments, the area of ​​the gel region accounts for 20% to 30% of the total area of ​​the coating.

[0014] In some embodiments, the gel region is located in the middle region of the isolation membrane.

[0015] In some embodiments, a portion of the gel electrolyte forms a gel layer on the surface of the gel region, the thickness of the gel layer being 0.1 μm to 0.5 μm.

[0016] In some embodiments, the mass content of the gel electrolyte in the gel region is 0.03% to 0.06%.

[0017] In some embodiments, the gel electrolyte includes one or more of polyacrylate gel, polyacrylamide gel, polyvinyl alcohol gel, polyacrylonitrile gel, and polyethylene oxide gel.

[0018] In some embodiments, the electrode plates include at least one of a positive electrode plate and a negative electrode plate.

[0019] Secondly, embodiments of this application provide a method for preparing a single battery cell, comprising the following steps:

[0020] An electrode sheet and a separator are provided respectively. The electrode sheet includes a current collector and an electrode film layer located on at least one side of the current collector. The separator includes a base film and a coating layer located on at least one side of the base film. The electrode film layer and / or the coating layer include a gel region and a non-gel region. The gel region contains a gel electrolyte monomer.

[0021] The electrode plates and the separator are assembled to form an electrode assembly, the electrode assembly is placed in a housing, an electrolyte containing an initiator is injected, and the housing is encapsulated to obtain a battery cell;

[0022] The battery cell is left to stand at a first temperature, allowing the initiator to initiate the polymerization of the gel electrolyte monomer to form a gel electrolyte.

[0023] In some embodiments, the provision of electrode plates includes:

[0024] A first electrode slurry containing the gel electrolyte monomer and a second electrode slurry not containing the gel electrolyte monomer are provided respectively;

[0025] The first electrode slurry and the second electrode slurry are respectively coated on at least one side of the current collector to form the gel region and the non-gel region, respectively.

[0026] In some embodiments, the mass content of the gel electrolyte monomer in the first electrode slurry is 0.03% to 0.06%.

[0027] In some embodiments, providing the insulating membrane includes:

[0028] A first separator slurry containing the gel electrolyte monomer and a second separator slurry not containing the gel electrolyte monomer are provided respectively;

[0029] The first separator slurry and the second separator slurry are respectively coated on at least one side of the base film to form the gel region and the non-gel region, respectively.

[0030] In some embodiments, the mass content of the gel electrolyte monomer in the first separator slurry is 0.03% to 0.06%.

[0031] In some embodiments, the gel electrolyte monomer includes one or more of acrylic acid and its derivatives, acrylamide and its derivatives, acrylonitrile, and ethylene oxide.

[0032] In some embodiments, the mass ratio of the gel electrolyte monomer to the initiator is 1:(0.8-1.5).

[0033] In some embodiments, the initiator includes one or more of azobisisobutyronitrile, dimethyl azobisisobutyrate, and azobisisoheptanenitrile.

[0034] In some embodiments, the first temperature is 40°C to 60°C.

[0035] According to the embodiments of this application, the preparation method of the second aspect of this application can be used to prepare the battery cell of the first aspect of this application itself.

[0036] Thirdly, embodiments of this application provide a battery device, including a battery cell from the first aspect of this application or a battery cell obtained according to the preparation method of the second aspect of this application.

[0037] Fourthly, embodiments of this application provide an electrical device including a battery device according to embodiments of the third aspect of this application. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0039] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0040] Figure 2 is a schematic diagram of the explosion of a battery provided in some embodiments of this application.

[0041] Figure 3 is an exploded view of the battery module shown in Figure 2.

[0042] Figure 4 is a schematic diagram of the gel region and non-gel region on the electrode sheet in some embodiments of this application.

[0043] Figure 5 is a schematic diagram of the gel region and non-gel region on the isolation membrane in some embodiments of this application.

[0044] The accompanying drawings are not necessarily drawn to scale.

[0045] The reference numerals in the attached drawings are explained as follows: 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing section; 5b. Second housing section; 5c. Receiving space; 6. Battery module; 7. Battery cell; 8. Electrode plate; 9. Separator; a. Non-gelled area; b. Gelled area. Detailed Implementation

[0046] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the battery cell, its preparation method, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0047] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0048] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0049] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0050] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0051] Unless otherwise specified, in this application, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0052] In this application, the terms "multiple" or "various" refer to two or more kinds of things.

[0053] In the description of the embodiments of this application, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0054] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0055] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0056] The battery device mentioned in the embodiments of this application can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application can include battery cells, battery modules, or battery packs.

[0057] A single battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. When there are multiple battery cells, they are connected in series, parallel, or mixed connections through a busbar.

[0058] In some embodiments, the battery device may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0059] In some embodiments, the battery device may be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0060] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0061] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0062] The technical solutions described in the embodiments of this application are applicable to battery devices and electrical devices that use battery devices.

[0063] Battery devices can be used as the power source for electrical devices or as energy storage units for electrical devices. Electrical devices can be, but are not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0064] Electrical devices can choose the type of battery device according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0065] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0066] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0067] As shown in Figure 1, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0068] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0069] In some embodiments, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0070] Figure 2 is an exploded view of a battery provided in some embodiments of this application. As shown in Figure 2, the battery device 2 includes a housing 5 and a battery cell (not shown), with the battery cell housed within the housing 5.

[0071] The housing 5 is used to house individual battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the individual battery cells. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as cylinders, cuboids, etc.

[0072] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0073] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0074] In battery device 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells are connected in both series and parallel configurations. Multiple battery cells can be directly connected in series, in parallel, or in a mixed configuration, and then the whole assembly of multiple battery cells is housed in housing 5. Alternatively, multiple battery cells can first be connected in series, in parallel, or in a mixed configuration to form battery module 6, and then multiple battery modules 6 can be connected in series, in parallel, or in a mixed configuration to form a whole assembly, which is then housed in housing 5.

[0075] Figure 3 is an exploded view of the battery module shown in Figure 2.

[0076] As shown in Figure 3, in some embodiments, there are multiple battery cells 7, which are first connected in series, parallel, or mixed to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or mixed to form a whole and housed in a casing.

[0077] Multiple battery cells 7 in battery module 6 can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 7 in battery module 6.

[0078] The battery cells mentioned in the embodiments of this application may include lithium-ion battery cells or sodium-ion battery cells.

[0079] The battery cell includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to this.

[0080] An electrode assembly typically includes electrode plates and a separator. The electrode plates can include positive electrode plates and negative electrode plates.

[0081] During the charge-discharge cycle of a battery cell, as active ions are inserted and extracted and the electrochemical reaction inside the cell continues, the pores of the active material layer on the electrode sheet are gradually filled with some reaction products, resulting in an increase in electrode thickness and a decrease in porosity. The electrolyte immersed in the electrode sheet is gradually squeezed out of the electrode sheet, and the free electrolyte is consumed by side reactions, which worsens the electrolyte wettability of the electrode sheet and causes local electrolyte shortage. The ion transport channels originally constructed by the electrolyte are damaged, and active ions are deposited on the electrode surface as dead lithium, which leads to the capacity decay of the battery cell and seriously affects the battery cell's lifespan and cycle performance.

[0082] In view of this, embodiments of this application provide a battery cell that, by adding a gel electrolyte to the electrode sheet and / or separator, can reduce the problem of electrolyte shortage in the electrode sheet, improve the wettability of the electrode sheet, and thus improve the lifespan and cycle performance of the battery cell.

[0083] In some embodiments, the battery cell includes an electrode sheet and a separator. The electrode sheet includes a current collector and an electrode film layer located on at least one side of the current collector. The separator includes a base film and a coating layer located on at least one side of the base film. The electrode film layer and / or coating layer include a gel region and a non-gel region, and the gel region contains a gel electrolyte.

[0084] In this application, the electrode plates include a positive electrode plate and a negative electrode plate, and the separator is located between the positive electrode plate and the negative electrode plate.

[0085] In this application, gel electrolyte refers to an electrolyte existing in a gel state. It possesses both the high ionic conductivity and high interfacial compatibility of liquid electrolytes and the high mechanical properties and high thermal stability of solid electrolytes. In the embodiments of this application, a gel region containing gel electrolyte is formed on the electrode sheet and / or separator, thus incorporating the gel electrolyte into the electrode sheet and / or separator. Due to the solid-like structural characteristics of the gel electrolyte, it can adhere tightly to the electrode sheet and / or separator, and will not be squeezed out due to the decrease in internal porosity of the electrode sheet and / or separator during the charge-discharge cycle of the battery cell, allowing the electrode sheet and / or separator to maintain high electrolyte wettability. Simultaneously, due to the high thermal stability of the gel electrolyte, side reactions of the electrolyte at high temperatures can be reduced, electrolyte consumption can be reduced, thereby improving the battery cell's lifespan and cycle performance.

[0086] Gel electrolytes exhibit high thermal stability, but their slower ion transport rate compared to liquid electrolytes can negatively impact the fast-charging performance of individual battery cells. In this application and embodiments, gel and non-gel regions are formed on the electrode plates and / or separators. By controlling the distribution area of ​​the gel electrolyte within the electrode plates and / or separators, the wettability of the electrolyte can be improved while reducing its impact on the ion transport rate, thereby enabling the individual battery cells to achieve higher fast-charging performance.

[0087] In this embodiment, the gel electrolyte can be disposed separately in the electrode sheet or the separator, or it can be disposed simultaneously in both the electrode sheet and the separator. When the electrode sheet contains the gel electrolyte, the gel electrolyte can be disposed in the positive electrode sheet, the negative electrode sheet, or both the positive and negative electrode sheets.

[0088] In some embodiments, the area percentage of the gel region can be from 10% to 50% based on the total area of ​​the electrode film. Exemplarily, the area percentage of the gel region can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any range of the above values, based on the total area of ​​the electrode film. Optionally, the area percentage of the gel region can be from 20% to 30% based on the total area of ​​the electrode film.

[0089] In some embodiments, the area percentage of the gel region can be from 10% to 50% based on the total area of ​​the coating. Exemplarily, the area percentage of the gel region can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any range of the above values, based on the total area of ​​the coating. Optionally, the area percentage of the gel region can be from 20% to 30% based on the total area of ​​the coating.

[0090] By limiting the area ratio of the gel region in the electrode film layer of the electrode sheet and / or the coating of the separator to the above range, the battery cell can have a high ion transport rate and good fast charging performance while improving electrolyte wettability and reducing electrolyte side reactions.

[0091] In some embodiments, referring to FIG4, the gel region b may be located in the middle region of the electrode plate 8, and the two sides of the gel region b are non-gel regions a; and / or, referring to FIG5, the gel region b may be located in the middle region of the separator 9, and the two sides of the gel region b are non-gel regions a.

[0092] In this application, the gel region can be disposed on any one of the positive electrode, negative electrode, and separator, or on any two or all of them.

[0093] During the charge-discharge cycle of a battery cell, the central region experiences higher temperature rise and poorer heat dissipation, leading to more severe electrolyte side reactions and consumption in this region. In this embodiment, by providing a gel region containing a gel electrolyte in the central area of ​​the electrode plates and / or separator, electrolyte consumption in the central region of the battery cell under high-temperature conditions can be effectively reduced, further improving battery life and cycle performance.

[0094] In some embodiments, a gel layer is formed on the surface of the gel region by a portion of the gel electrolyte, and the thickness of the gel layer can be from 0.1 μm to 0.5 μm. Exemplarily, the thickness of the gel layer can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, or any range of the above values.

[0095] During the formation of the gel region, some of the gel electrolyte will polymerize on the surface and then adhere to the electrode film or coating surface to form a gel layer. By controlling the thickness of the formed gel layer within the above range, the electrode sheet can have extremely high wettability, further reducing electrolyte consumption at high temperatures, improving the life of the battery cell, and enhancing cycle performance.

[0096] In some embodiments, the mass content of the gel electrolyte in the gel region can be from 0.03% to 0.06%. Exemplarily, the mass content of the gel electrolyte in the gel region can be 0.03%, 0.04%, 0.05%, 0.06%, or any range of the above values.

[0097] By controlling the mass content of the gel electrolyte in the gel region within the above range, the gel region can have high wettability, which is conducive to the rapid insertion / extraction of active ions. At the same time, the electrode film layer can have a high content of active materials, and the battery cell can maintain a high capacity.

[0098] In some embodiments, the gel electrolyte may include one or more of polyacrylate gel, polyacrylamide gel, polyvinyl alcohol gel, polyacrylonitrile gel, and polyethylene oxide gel.

[0099] The aforementioned gel electrolyte has good compatibility with the coating materials of the electrode film and the separator, and can form a stable coating of the electrode film and the separator. At the same time, it has good conductivity and structural stability, which is conducive to the rapid insertion / extraction of active ions, so that the battery cell has good cycle performance.

[0100] In this embodiment of the application, the electrode sheet may include a positive electrode sheet and a negative electrode sheet.

[0101] [Positive electrode plate]

[0102] In some embodiments, the positive electrode film layer includes a positive electrode active material.

[0103] In some embodiments, the positive electrode active material includes one or more of lithium phosphate, layered lithium transition metal oxide, Prussian blue compounds, polyanionic compounds, and sodium transition metal oxide.

[0104] If the positive electrode active material is one or more of lithium phosphate and layered lithium transition metal oxide, then the positive electrode active material can be used in lithium-ion battery cells; if the positive electrode active material is one or more of Prussian blue compounds, polyanionic compounds, and sodium transition metal oxide, then the positive electrode material can be used in sodium-ion battery cells.

[0105] Lithium-containing phosphates may include one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and their respective modified compounds.

[0106] Examples of layered lithium-containing transition metal oxides may include one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds.

[0107] In some embodiments, the layered lithium-containing transition metal oxide may include Ni. The molar amount of Ni may account for more than 70% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide; optionally, the molar amount of Ni may account for more than 80% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide; more preferably, the molar amount of Ni may account for more than 90% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

[0108] The higher the Ni content in layered lithium-containing transition metal oxides, the higher the energy density of the battery cell.

[0109] In some embodiments, layered lithium-containing transition metal oxides may include Li a Ni b Co c M d O e A f Wherein, 0 < a ≤ 1.2; 0.8 ≤ b < 1; 0 < c < 1; 0 < d < 1; 1 ≤ e ≤ 2; 0 ≤ f ≤ 1; M includes, but is not limited to, one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B; A includes, but is not limited to, one or more of N, F, S, and Cl. This can further improve the energy density of individual battery cells.

[0110] In some embodiments, as an example, layered lithium-containing transition metal oxides may include, but are not limited to, LiNi.0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.9 Co 0.06 Mn 0.04 O2, LiNi 0.92 Co 0.06 Mn 0.02 O2, LiNi 0.96 Co 0.02 Mn 0.02 One or more of O2.

[0111] During the charging and discharging process of a battery cell, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before material addition. After charge-discharge cycles, the molar Li content may change when the positive electrode active material is applied to the battery cell.

[0112] In some embodiments, as an example, sodium transition metal oxides may include, but are not limited to:

[0113] Na 1-x Cu h Fe k Mn l M 1 m O 2-y M 1 It is one or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0114] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 It is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, 0 <z≤0.1;

[0115] Na a Li b Ni c Mn d Fe eO2, where 0.67 < a ≤ 1, 0 < b < 0.2, 0 < c < 0.3, 0.67 < d + e < 0.8, and b + c + d + e = 1.

[0116] In some embodiments, by way of example, the polyanionic compound may include, but is not limited to:

[0117] A 1 f M 3 g (PO4) i O j X 1 3-j , where A is one or more of H, Li, Na, K, and NH4, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, X 1 is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0118] Na n M 4 PO4X 2 , where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0119] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0120] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0121] In some embodiments, by way of example, the Prussian blue compounds may include, but are not limited to:

[0122] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + 、NH4 + 、alkali metal cations and alkaline earth metal cations, and M6 and M 7 Each independently represents one or more of transition metal cations, where 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A is H + , Li + , Na + , K + , NH4 + , Rb + , Cs + , Fr + , Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ and Ra 2+ One or more of these, and M 6 and M 7 Each independently represents a cation of one or more transition metal elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W. Optionally, A is one or more of Li + , Na + and K + One or more of these, and M 6 is a cation of one or more transition metal elements selected from Mn, Fe, Co, Ni, and Cu, and M 7 is a cation of one or more transition metal elements selected from Mn, Fe, Co, Ni, and Cu.

[0123] In the enumeration of the positive electrode active materials in the embodiments of this application, the molar content of O is only the theoretical value. Oxygen release from the lattice will cause the molar content of O to change, and the actual molar content of O will show fluctuations.

[0124] The modified compounds of the above positive electrode active materials can be doping modification and / or surface coating modification of the positive electrode active materials.

[0125] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0126] In some implementations, the weight percentage of the binder in the positive electrode film layer is greater than or equal to 0.5%, which is beneficial to obtaining good adhesion performance.

[0127] In some embodiments, the positive electrode film layer further includes a conductive agent. As an example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0128] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be made by forming a metal material, such as aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, on the polymer substrate. The polymer substrate may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and other substrates.

[0129] In some embodiments, the thickness of the positive current collector is from 4 μm to 20 μm. It is optionally from 6 μm to 18 μm, and more preferably from 8 μm to 16 μm.

[0130] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0131] [Negative electrode plate]

[0132] In some embodiments, the negative electrode film layer comprises a negative electrode active material.

[0133] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. The negative electrode current collector can be made of materials such as metal foil, carbon-coated metal foil, or porous metal plate, and copper foil is an option.

[0134] As an example, the negative electrode active material may include one or more of the following: artificial graphite, natural graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon, and silicon-carbon composites.

[0135] Silicon-based composite materials can be prepared by methods known in the art. For example, they can be prepared by vapor deposition using graphite and silicon materials as raw materials.

[0136] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0137] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0138] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0139] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one side of the polymeric material substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymeric material substrates include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0140] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may also include a conductive undercoat layer sandwiched between the negative electrode current collector and the negative electrode film layer and located on the surface of the negative electrode current collector, which may be composed of a conductive agent and a binder; in some embodiments, the negative electrode sheet may also include a protective layer covering the surface of the negative electrode film layer.

[0141] The negative electrode sheet can be prepared as follows: The negative electrode active material, negative electrode binder, negative electrode conductive agent, and optional other additives are dispersed in a solvent and stirred evenly to form a negative electrode slurry; the negative electrode slurry is coated onto a negative electrode current collector, and after drying, rolling, and other processes, a negative electrode sheet is formed. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0142] [Electrolytes]

[0143] A single battery cell includes an electrolyte.

[0144] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0145] In some embodiments, the electrolyte includes anion, which may include bis(fluorosulfonyl)imide anion (FSI). - ), bis(trifluoromethanesulfonyl)imide anion (TFSI) - ), dioxaborate anion (BOB) - ), difluorooxalate borate anion (DFOB) - ), difluorodioxanol phosphate anion (DFOP) - ), tetrafluorooxalate phosphate anion (TFOP) - ), difluorophosphate anion (PO2F2) - ), hexafluorophosphate anion (PF6) - ), tetrafluoroborate anion (BF4) - ), hexafluoroarsenate anion (AsF6) - ), trifluoromethanesulfonate anion (CF3SO3) - One or more of the following.

[0146] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0147] In some embodiments, the concentration of the electrolyte salt may be 0.3 mol / L or higher, optionally 0.7 mol / L or higher, and further optionally 4 mol / L or lower, optionally 2.5 mol / L or lower, or 1.7 mol / L or lower. When the concentration of the electrolyte salt is within the above range, the electrolyte can have a suitable ionic conductivity.

[0148] Organic solvents may include, but are not limited to, one or more of esters, ethers, sulfones, and nitriles. Esters may include, but are not limited to, one or more of carbonates, phosphate esters, carboxylic esters, sulfate esters, and sulfonates. Carbonates may include cyclic carbonates and / or chain carbonates; optionally, carbonates may include both cyclic and chain carbonates. Chain carbonates may include low-viscosity polar chain carbonates, aliphatic branched carbonates, etc.

[0149] As an example, organic solvents may include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), butene carbonate, ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), dimethyl ether tetraethylene glycol (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL), trimethyl phosphate, 3-methoxypropionitrile, H(CF2)2OCH3, C4F9O CH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, H(CF2)2CH2O(CF2)2H, CF3CHFCF2OCH3, CF3CHFCF2OCH2CH3, 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyloctafluorobutyl methyl ether, 3-trifluoromethyloctafluorobutyl ethyl ether, 3-trifluoromethyloctafluorobutyl propyl ether, 4-trifluoromethyl One or more of the following: decafluoropentyl methyl ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether, 5-trifluoromethyl dodecylfluorohexyl methyl ether, 5-trifluoromethyl dodecylfluorohexyl ethyl ether, 5-trifluoromethyl dodecylfluorohexyl propyl ether, 6-trifluoromethyl tetradecafluoroheptyl methyl ether, 6-trifluoromethyl tetradecafluoroheptyl ethyl ether, 6-trifluoromethyl tetradecafluoroheptyl propyl ether, 7-trifluoromethyl hexadecylfluorooctyl methyl ether, 7-trifluoromethyl hexadecylfluorooctyl ethyl ether, and 7-trifluoromethyl hexadecylfluorooctyl propyl ether.

[0150] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, additives that improve battery low-temperature power performance, etc.

[0151] [Isolation membrane]

[0152] This application does not impose any particular restrictions on the type of separator membrane; any known porous membrane with good chemical and mechanical stability can be selected.

[0153] In some embodiments, the material of the separator may include at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation. The separator may be a single component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating may also be applied to the surface of the separator.

[0154] [Preparation methods for battery cells]

[0155] Another embodiment of this application provides a method for preparing a battery cell, which can be used to prepare the battery cells of the embodiments of this application.

[0156] The preparation method of a single battery cell includes the following steps:

[0157] S10 provides an electrode sheet and a separator, the electrode sheet includes a current collector and an electrode film layer located on at least one side of the current collector, the separator includes a base film and a coating layer located on at least one side of the base film, the electrode film layer and / or the coating layer includes a gel region and a non-gel region, the gel region contains a gel electrolyte monomer;

[0158] S20: Assemble the electrode plates and separator to form an electrode assembly, place the electrode assembly in the housing, inject an electrolyte containing an initiator, and encapsulate to obtain a battery cell;

[0159] S30, the battery cells are left to stand at the first temperature, so that the initiator initiates the polymerization of the gel electrolyte cells to form a gel electrolyte.

[0160] In this embodiment, the gel electrolyte monomers used to form the gel electrolyte are introduced simultaneously with the coating material of the electrode film or separator. After assembling the battery cell, the gel electrolyte monomers are polymerized during the settling process to achieve electrolyte gelation, thereby forming the gel electrolyte in the electrode sheet and / or separator. This allows for the achievement of electrolyte gelation without incurring additional costs or processes.

[0161] Step S10 includes providing electrode plates and providing a separator.

[0162] In some implementations, step S10, which provides the electrode plates, may include:

[0163] A first electrode slurry containing a gel electrolyte monomer and a second electrode slurry not containing a gel electrolyte monomer are provided respectively; the first electrode slurry and the second electrode slurry are respectively coated on at least one side of the current collector to form a gel region and a non-gel region respectively.

[0164] In this embodiment, the gel electrolyte monomer is added to the electrode slurry so that the gel electrolyte monomer and the electrode active material can be dispersed and mixed. During the subsequent electrode film curing process, the gel electrolyte monomer is introduced into the electrode film. The gel electrolyte monomer is then polymerized by an initiator to obtain a gel electrolyte, thereby forming a gel region in the electrode film.

[0165] In some embodiments, the mass content of the gel electrolyte monomer in the first electrode slurry can be from 0.03% to 0.06%. Exemplarily, the mass content of the gel electrolyte monomer in the first electrode slurry can be 0.03%, 0.04%, 0.05%, 0.06%, or any range of the above values.

[0166] By limiting the content of gel electrolyte monomers in the first electrode slurry to the above range, an electrode film layer with a suitable gel electrolyte content can be formed. While improving electrolyte wettability and reducing electrolyte side reactions at high temperatures, the electrode film layer has a high content of active materials, and the battery cell can have both high lifespan and capacity.

[0167] In some embodiments, step S10, providing the isolation membrane, may include:

[0168] A first separator slurry containing a gel electrolyte monomer and a second separator slurry not containing a gel electrolyte monomer are provided respectively; the first separator slurry and the second separator slurry are respectively coated on at least one side of the current collector to form a gel region and a non-gel region respectively.

[0169] In this embodiment, the gel electrolyte monomer is added to the separator slurry so that the gel electrolyte monomer and the separator coating material can be dispersed and mixed. During the subsequent curing process of the separator coating, the gel electrolyte monomer is introduced into the separator coating. The gel electrolyte monomer is further polymerized by an initiator to obtain a gel electrolyte, thereby forming a gel region in the separator coating.

[0170] In some embodiments, the mass content of the gel electrolyte monomer in the first separator slurry can be from 0.03% to 0.06%. Exemplarily, the mass content of the gel electrolyte monomer in the first electrode slurry can be 0.03%, 0.04%, 0.05%, 0.06%, or any range of the above values.

[0171] In some embodiments, the gel electrolyte monomer may include one or more of acrylic acid and its derivatives, acrylamide and its derivatives, acrylonitrile, and ethylene oxide.

[0172] The aforementioned gel electrolyte monomers can form gel electrolytes with high thermal stability and electrical conductivity under the action of an initiator.

[0173] In some embodiments, the initiator may include one or more of azobisisobutyronitrile, dimethyl azobisisobutyrate, and azobisisoheptanenitrile.

[0174] In some embodiments, the mass ratio of gel electrolyte monomer to initiator can be 1:(0.8-1.5), or optionally 1:(0.9-1.2).

[0175] By limiting the ratio of gel electrolyte monomer to initiator within the above range, it is beneficial for the gel electrolyte monomer to fully polymerize and form a gel electrolyte.

[0176] In some embodiments, the first temperature can be from 40°C to 60°C. Exemplarily, the first temperature can be 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, or any range of the above values.

[0177] Example

[0178] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0179] Example 1

[0180] Positive electrode sheet

[0181] The positive electrode active material lithium iron phosphate (LiFePO4), conductive agent conductive carbon black, binder polyvinylidene fluoride (PVDF), and gel electrolyte monomer methyl methacrylate were mixed in a mass ratio of 89.97:5:5:0.03 and then added to the solvent N-methylpyrrolidone (NMP) and uniformly dispersed to obtain the first positive electrode slurry.

[0182] The positive electrode active material lithium iron phosphate (LiFePO4), conductive agent conductive carbon black, and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 90:5:5 and then added to the solvent N-methylpyrrolidone (NMP) and uniformly dispersed to obtain the second positive electrode slurry.

[0183] Referring to Figure 4, the first positive electrode slurry is coated onto the middle area of ​​the surface of the positive electrode current collector aluminum foil, and the other areas of the aluminum foil surface are coated with the second positive electrode slurry. The area of ​​the first positive electrode slurry coating area accounts for 20%. After drying, cold pressing and slitting, the positive electrode sheet is obtained.

[0184] Negative electrode sheet

[0185] The first negative electrode slurry was prepared by uniformly mixing graphite (anode active material), Super P (conductive agent), carboxymethyl cellulose (CMC) (thickener), styrene-butadiene rubber (SBR) (binder), and methyl methacrylate (gel electrolyte monomer) in deionized water at a mass ratio of 79.97:15:3:2:0.03.

[0186] The negative electrode active material graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) are mixed evenly in deionized water at a mass ratio of 80:15:3:2 to prepare the second negative electrode slurry.

[0187] The first negative electrode slurry and the second negative electrode slurry are evenly coated on the current collector copper foil and dried at 85°C. The first negative electrode slurry is coated in the middle area of ​​the copper foil, accounting for 20% of the coating area. Then, the copper foil is cold-pressed and cut to obtain the negative electrode sheet.

[0188] Separating membrane

[0189] A polyethylene (PE) film with a thickness of 13μm was selected.

[0190] electrolyte

[0191] The electrolyte solvent is a mixture of ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. The electrolyte salt is LiPF6 with a concentration of 1 mol / L. Azobisisobutyronitrile (AIBN) is added as an initiator, and the mass ratio of the initiator to methyl methacrylate in the first positive electrode slurry is 1:1.

[0192] battery cell

[0193] The positive electrode, negative electrode, and separator are stacked in sequence, electrolyte is injected, and the cells are encapsulated to obtain a coin cell. The coin cell is then left to stand at 50°C for 14 hours.

[0194] Examples 2 to 8

[0195] The preparation methods of the battery cells in Examples 2 to 8 are similar to those in Examples 1, except that the preparation parameters of the positive electrode and the negative electrode are adjusted. For details of the parameter adjustments, please refer to Table 1.

[0196] Table 1

[0197] Example 9

[0198] The preparation method of the battery cell is similar to that in Example 1, except that no gel region is set in the negative electrode film layer.

[0199] Example 10

[0200] The preparation method of the battery cell is similar to that in Example 1, except that no gel region is set in the positive electrode film layer.

[0201] Examples 11 to 15

[0202] Battery cells are produced by the following methods:

[0203] Positive electrode sheet

[0204] Lithium iron phosphate (LiFePO4), conductive carbon black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 90:5:5 and then added to the solvent N-methylpyrrolidone (NMP) to uniformly disperse and obtain a positive electrode slurry. The positive electrode slurry was coated onto the surface of the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0205] Negative electrode sheet

[0206] A negative electrode slurry is prepared by uniformly mixing graphite (a negative electrode active material), Super P (a conductive agent), carboxymethyl cellulose (CMC) (a thickener), and styrene-butadiene rubber (SBR) (a binder) in deionized water at a mass ratio of 80:15:3:2. The negative electrode slurry is then uniformly coated onto copper foil (a current collector) and dried at 85°C. After cold pressing and slitting, the negative electrode sheet is obtained.

[0207] Separating membrane

[0208] A polyethylene (PE) film with a thickness of 13 μm was selected as the base film;

[0209] Alumina and gel electrolyte monomer methyl methacrylate were dispersed into binder polyvinylidene fluoride at a mass ratio of 99.97:0.03 and mixed evenly to obtain the first separator slurry with a solid content of 35%.

[0210] Alumina was dispersed in polyvinylidene fluoride and mixed evenly to obtain a second separator slurry with a solid content of 35%.

[0211] Referring to Figure 5, the first separator slurry and the second separator are coated onto the surface of the base film, and then dried and slit to obtain the separator.

[0212] electrolyte

[0213] The electrolyte solvent is a mixture of ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. The electrolyte salt is LiPF6 with a concentration of 1 mol / L. Azobisisobutyronitrile (AIBN) is added as an initiator, and the mass ratio of the initiator to methyl methacrylate in the first positive electrode slurry is 1:1.

[0214] battery cell

[0215] The positive electrode, negative electrode, and separator are stacked in sequence, electrolyte is injected, and the cells are encapsulated to obtain a coin cell. The coin cell is then left to stand at 50°C for 14 hours.

[0216] The product parameters for each embodiment are detailed in Table 2.

[0217] Table 2

[0218] Comparative Example 1

[0219] Battery cells are produced by the following methods:

[0220] Positive electrode sheet

[0221] Lithium iron phosphate (LiFePO4), conductive carbon black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 90:5:5 and then added to the solvent N-methylpyrrolidone (NMP) to uniformly disperse and obtain a positive electrode slurry. The positive electrode slurry was coated onto the surface of the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0222] Negative electrode sheet

[0223] A negative electrode slurry is prepared by uniformly mixing graphite (a negative electrode active material), Super P (a conductive agent), carboxymethyl cellulose (CMC) (a thickener), and styrene-butadiene rubber (SBR) (a binder) in deionized water at a mass ratio of 80:15:3:2. The negative electrode slurry is then uniformly coated onto copper foil (a current collector) and dried at 85°C. After cold pressing and slitting, the negative electrode sheet is obtained.

[0224] Separating membrane

[0225] A polyethylene (PE) film with a thickness of 13μm was selected.

[0226] electrolyte

[0227] The electrolyte solvent is a mixture of ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. The electrolyte salt is LiPF6 with a concentration of 1 mol / L. Azobisisobutyronitrile (AIBN) is added as an initiator, and the mass ratio of the initiator to methyl methacrylate in the first positive electrode slurry is 1:1.

[0228] battery cell

[0229] The positive electrode, negative electrode, and separator are stacked in sequence, injected with electrolyte, and then encapsulated to obtain a button cell.

[0230] Test section

[0231] 1. Capacity

[0232] The battery cell is charged at a constant current of 0.1C to the upper limit of the cutoff voltage, charged at a constant voltage to 0.05C, and then discharged at a constant current of 0.1C to the lower limit of the cutoff voltage. The specific capacity of the battery cell is the ratio of the initial discharge capacity of the battery cell to the mass of the active material.

[0233] 2. Fast charging cycle performance

[0234] The battery cells were charged at 3C to 3.65V in a constant temperature environment of 60℃ at a voltage of 2.5~3.65V, and then charged at a constant voltage of 3.65V until the current ≤0.05mA. After standing for 5 minutes, they were discharged at 3C to 2.5V. The capacity was recorded as Dn (n=0, 1, 2, ……). The above operation was repeated for 500 cycles, and the capacity retention rate was measured.

[0235] 3. High-temperature storage life

[0236] The battery cells were charged at a constant current of 0.1C to the upper limit cutoff voltage and then stored in a 60°C oven. Every so often, the cells were taken out to test their reversible capacity and the ratio of the reversible capacity to the initial capacity after 60 days of storage was recorded.

[0237] For detailed performance test results, please refer to Table 3.

[0238] Table 3

[0239] Based on the data in Table 3, the embodiments of this application can effectively improve the cycle performance and kinetic performance of the battery cell by setting a gel region containing a gel electrolyte in the positive electrode / negative electrode or separator.

[0240] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell, comprising an electrode sheet and a separator, wherein the electrode sheet comprises a current collector and an electrode film layer located on at least one side of the current collector, and the separator comprises a base film and a coating layer located on at least one side of the base film; The electrode film and / or the coating include gel regions and non-gel regions, wherein the gel regions contain gel electrolytes.

2. The battery cell according to claim 1, wherein, Based on the total area of ​​the electrode film, the area of ​​the gel region accounts for 10% to 50%; and / or Based on the total area of ​​the coating, the area of ​​the gel region accounts for 10% to 50%.

3. The battery cell according to claim 2, wherein, Based on the total area of ​​the electrode film, the area of ​​the gel region accounts for 20% to 30%; and / or Based on the total area of ​​the coating, the area of ​​the gel region accounts for 20% to 30%.

4. The battery cell according to any one of claims 1 to 3, wherein, The gel region is located in the middle area of ​​the electrode sheet; and / or The gel region is located in the middle area of ​​the isolation membrane.

5. The battery cell according to any one of claims 1 to 4, wherein, A portion of the gel electrolyte forms a gel layer on the surface of the gel region, the thickness of which is 0.1 μm to 0.5 μm.

6. The battery cell according to any one of claims 1 to 5, wherein, The mass content of the gel electrolyte in the gel region is 0.03% to 0.06%.

7. The battery cell according to any one of claims 1 to 6, wherein, The gel electrolyte includes one or more of the following: polyacrylate gel, polyacrylamide gel, polyvinyl alcohol gel, polyacrylonitrile gel, and polyethylene oxide gel.

8. The battery cell according to any one of claims 1 to 7, wherein, The electrode plates include at least one of a positive electrode plate and a negative electrode plate.

9. A method for preparing a single battery cell, comprising the following steps: An electrode sheet and a separator are provided respectively. The electrode sheet includes a current collector and an electrode film layer located on at least one side of the current collector. The separator includes a base film and a coating layer located on at least one side of the base film. The electrode film layer and / or the coating layer include a gel region and a non-gel region. The gel region contains a gel electrolyte monomer. The electrode plates and the separator are assembled to form an electrode assembly, the electrode assembly is placed in a housing, an electrolyte containing an initiator is injected, and the housing is encapsulated to obtain a battery cell; The battery cell is left to stand at a first temperature, allowing the initiator to initiate the polymerization of the gel electrolyte monomer to form a gel electrolyte.

10. The preparation method according to claim 9, wherein, The provided electrode sheet includes: A first electrode slurry containing the gel electrolyte monomer and a second electrode slurry not containing the gel electrolyte monomer are provided respectively; The first electrode slurry and the second electrode slurry are respectively coated on at least one side of the current collector to form the gel region and the non-gel region, respectively.

11. The preparation method according to claim 10, wherein, The mass content of the gel electrolyte monomer in the first electrode slurry is 0.03% to 0.06%.

12. The preparation method according to claim 9 or 11, wherein, The provision of the insulating membrane includes: A first separator slurry containing the gel electrolyte monomer and a second separator slurry not containing the gel electrolyte monomer are provided respectively; The first separator slurry and the second separator slurry are respectively coated on at least one side of the base film to form the gel region and the non-gel region, respectively.

13. The preparation method according to claim 12, wherein, The mass content of the gel electrolyte monomer in the first separator slurry is 0.03% to 0.06%.

14. The preparation method according to any one of claims 9 to 13, wherein, The gel electrolyte monomer includes one or more of acrylic acid and its derivatives, acrylamide and its derivatives, acrylonitrile, and ethylene oxide.

15. The preparation method according to any one of claims 9 to 14, wherein, The mass ratio of the gel electrolyte monomer to the initiator is 1:(0.8-1.5).

16. The preparation method according to any one of claims 9 to 12, wherein, The initiator includes one or more of azobisisobutyronitrile, dimethyl azobisisobutyrate, and azobisisoheptanenitrile.

17. The preparation method according to any one of claims 9 to 13, wherein, The first temperature is 40°C to 60°C.

18. A battery device comprising a battery cell according to any one of claims 1 to 8 or a battery cell obtained by the preparation method according to any one of claims 9 to 17.

19. An electrical device comprising the battery device of claim 18.

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