Battery and electric device

Abstract

The invention relates to a battery and an electric device. The battery comprises an electrode pole piece, the electrode pole piece comprises a current collector and a film layer arranged on at least one side of the current collector, the film layer comprises an active substance and an adsorption polymer, and the adsorption polymer is added into a preset electrolyte at 45 DEG C to form a polymer system; after the polymer system is stood for 60 hours at 45 DEG C and is stood for more than or equal to 24 hours at 25 DEG C, the polymer system is filtered by a 200-mesh filter screen to obtain a first substance, the mass of the adsorption polymer is n (the unit is g), the mass of the first substance is m1 (the unit is g), and the adsorption polymer and the first substance meet the condition that m1 / n is more than or equal to 3 and less than or equal to 35; and drying the first substance at 60 DEG C for more than or equal to 24 hours to obtain a second substance, the mass of the second substance is m2, the unit of the second substance is g, and the second substance and the first substance meet the condition that m2 / n is more than or equal to 1.00 and less than or equal to 1.05.

Description

[0001] This application is a divisional application based on the invention with application number 202311457180.1, application date November 3, 2023, applicant CATL, and invention title "Electrode Sheet, Battery and Electrical Device".

[0002] Citation of relevant applications This application claims priority to international patent application PCT / CN2023 / 072036, filed on January 13, 2023, entitled “Polymers, Electrodes and Related Battery Cells, Batteries and Electrical Devices,” the entire contents of which are incorporated herein by reference.

[0003] This application also claims priority to international patent application PCT / CN2023 / 076843, filed on February 17, 2023, entitled “Ether polymers, electrodes and related battery cells, batteries and electrical devices thereof,” the entire contents of which are incorporated herein by reference.

[0004] This application also claims priority to international patent application PCT / CN2023 / 076793, filed on February 17, 2023, entitled “Ester polymers, electrodes and related battery cells, batteries and electrical devices thereof,” the entire contents of which are incorporated herein by reference.

[0005] This application also claims priority to international patent application PCT / CN2023 / 076789, filed on February 17, 2023, entitled “Aldehyde-ketone polymers, electrodes and related battery cells, batteries and electrical devices thereof,” the entire contents of which are incorporated herein by reference. Technical Field

[0006] This application relates to a battery and an electrical device. Background Technology

[0007] Batteries have the characteristics of high capacity and long life, so they are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0008] As batteries are used in a wider range of applications, the requirements for battery performance are becoming increasingly stringent. However, the cycle performance of batteries needs further improvement. Summary of the Invention

[0009] This application is made in view of the above-mentioned issues, and its purpose is to provide a battery and an electrical device.

[0010] In a first aspect, this application proposes a battery, which includes electrode sheets. The electrode sheets include a current collector and a film layer disposed on at least one side of the current collector. The film layer includes an active material and an adsorbent polymer. in, The adsorbed polymer is added to a preset electrolyte at 45°C to form a polymer system. The preset electrolyte includes dimethyl carbonate, ethyl methyl carbonate, ethylene carbonate, and lithium hexafluorophosphate. The mass of dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate is the same, and the concentration of lithium hexafluorophosphate is 1 mol / L. After the polymer system is allowed to stand at 45℃ for 60h and at 25℃ for ≥24h, the polymer system is filtered through a 200-mesh filter and the remaining first substance is obtained. The mass of the adsorbed polymer is n in g, and the mass of the first substance is m1 in g. The adsorbed polymer and the first substance satisfy: 3≤m1 / n≤35. After drying the first substance at 60℃ for ≥24h, the second substance is obtained. The mass of the second substance is m2, and its unit is g. The second substance and the first substance satisfy: 1.00≤m2 / n≤1.05.

[0011] Secondly, this application proposes a battery, which includes electrode sheets. The electrode sheets include a current collector and a film layer disposed on at least one side of the current collector. The film layer includes an active material and an adsorbent polymer. in, The adsorbed polymer is added to a preset electrolyte at 45°C to form a polymer system. The mass ratio of the preset electrolyte to the adsorbed polymer is 15:1. The preset electrolyte includes dimethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and lithium hexafluorophosphate. The mass of dimethyl carbonate, methyl ethyl carbonate, and ethylene carbonate is the same, and the concentration of lithium hexafluorophosphate is 1 mol / L. After the polymer system is allowed to stand at 45℃ for 60h and at 25℃ for ≥24h, the polymer system is filtered through a 200-mesh filter and the remaining first substance is obtained. The mass of the adsorbed polymer is n in g, and the mass of the first substance is m1 in g. The adsorbed polymer and the first substance satisfy: 3≤m1 / n≤35. After drying the first substance at 60℃ for ≥24h, the second substance is obtained. The mass of the second substance is m2, and its unit is g. The second substance and the first substance satisfy: 1.00≤m2 / n≤1.05.

[0012] Therefore, in the embodiments of this application, the adsorption of electrolyte by the adsorbed polymer is a physically reversible adsorption process. When the system temperature is slightly higher, such as the normal higher operating temperature of the battery system, the adsorbed polymer can achieve molecular chain extension, promoting mutual attraction and physical bonding between the adsorbed polymer molecular chains and the solvent, forming an in-situ gel-state substance. When the system temperature drops to the normal lower operating temperature of the battery system, the in-situ gel-state substance can adhere to the surface of the active material particles and lock the electrolyte in the space environment where the adsorbed polymer is located, protecting the active material interface while facilitating normal lithium-ion transport. Under conditions of higher system temperature, such as the normal higher operating temperature of the battery system, or dryness and lack of liquid, the locked electrolyte can be released, achieving flexible electrolyte storage. When the active particles expand and deform during charging and discharging, the gelled liquid-absorbing polymer can release liquid electrolyte in time to buffer the deformation of the polymer / active particle interface, thereby improving the cycle performance of the battery.

[0013] In some implementations, 5 ≤ m1 / n ≤ 35.

[0014] In some embodiments, the mass content of the adsorbed polymer is ≤5% based on the total mass of the membrane layer, and can be selected as 0.05% to 5%; In some implementations, the electrode is a positive electrode.

[0015] In some embodiments, the electrode sheet is a positive electrode sheet, and the mass content of the adsorbed polymer is 0.05% to 2% based on the total mass of the film.

[0016] In some implementations, the electrode is a negative electrode.

[0017] In some embodiments, the electrode sheet is a negative electrode sheet, and the mass content of the adsorbed polymer is 1% to 5% based on the total mass of the film layer; In some embodiments, the coating weight of the adsorbent polymer is 0.5 mg / 1540.25 mm. 2 Up to 2mg / 1540.25mm 2 When the content of the adsorbed polymer is within the above range, the adsorbed polymer can effectively improve the interfacial properties and structural stability of the electrode sheet.

[0018] In some embodiments, the adsorbent polymer includes a fluorinated polymer, 12 ≤ m1 / n ≤ 31; Optionally, The crystallinity of the fluorinated polymer, as determined by differential scanning calorimetry, is Xc1%, where 0 < Xc1 ≤ 30, and optionally, 8 ≤ Xc1 ≤ 25. The melting temperature of fluoropolymers is T m1 ℃, 0 < T m1 ≤140, optionally, 81≤T m1 ≤130; Further optionally, the glass transition temperature of the fluoropolymer is T. g1 ℃, -150≤T g1 ≤60, optionally, 5≤T g1 ≤25; Alternatively, the fluorinated polymer may include at least one of the compounds represented by formula (A1) to formula (AIII). Formula (AI) Formula (AII), In equations (AI) and (AII), R 11 R 12 R 13 and R 14 Each independently comprises a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and R 11 R 12 R 13 and R 14 At least one of them contains a fluorine atom; Formula (AIII) In equation (AIII), R 15 Includes single-bonded, substituted or unsubstituted C1-C3 alkyl groups; p is selected from any positive integer from 1 to 3; n is any positive integer from 1000 to 30000.

[0019] Therefore, fluorinated polymers possess relatively low crystallinity, melting temperature, or glass transition temperature. The better the flexibility of the fluorinated polymer molecular chains, the better the segmental flexibility, and the easier it is for adjacent molecular chains to open. Solvent molecules in the electrolyte enter between the fluorinated polymer molecular chains, forming a gel-like substance. This effectively stores the electrolyte on the surface of the active material, improving its wetting performance. At higher temperatures, the gel-like substance can release solvent molecules, restoring the polymer state and thus possessing a certain degree of elasticity. This allows the interface between the fluorinated polymer and the active material particles to deform, enabling deformation during battery cycle charging and discharging. This reduces the risk of internal electrode structure peeling, improves the overall structural stability of the electrode, and enhances the cycle performance of the battery cell.

[0020] In some embodiments, the adsorbent polymer includes ether polymers, where 7 ≤ m1 / n ≤ 15; Optionally, the ether polymer is formed into a sheet-like structure; the sheet-like structure is in (T m2The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K1, 1<K1<∞, T m2 ℃ represents the melting temperature of the ether polymer; optionally, 1 < K1 ≤ 100; further optionally, 1 < K1 ≤ 10; further optionally, 1.1 ≤ K1 ≤ 2; Optionally, the glass transition temperature of the ether polymer is T. g2 ℃, -100≤T g2 ≤50; optionally, -80≤T g2 ≤30; optionally, -65≤T g2 ≤0; Further optionally, the ether polymer includes at least one of the compounds shown in formula (BI) and formula (BII). Formula (BI), In formula (BI), R 21 and R 22 Each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; R 23 Including substituted or unsubstituted C1-C5 alkylene groups; Formula (BII) In formula (BII), R 24 To R 27 Each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group, and R 24 To R 27 At least one of them contains a substituted or unsubstituted C1-C3 alkoxy or ether group; The degree of polymerization n of ether polymers is selected from any positive integer from 1500 to 25000.

[0021] Therefore, when the ether polymers of the embodiments of this application meet the above-mentioned range, the molecular chain entanglement state can be further reduced, which is beneficial to the diffusion of solvent molecules in the electrolyte between molecular chains and to the formation of gel-like substances. Furthermore, the ether polymers still maintain a certain degree of molecular chain entanglement, which can effectively store electrolyte and improve the wetting performance of the active materials. At higher temperatures, the gel-like substances can release solvent molecules and restore the polymer state, thereby possessing a certain degree of elasticity. This allows the interface between the ether polymers and the active material particles to deform, enabling deformation during battery cycle charging and discharging. This reduces the risk of internal structure peeling off the electrode plates, improves the overall structural stability of the electrode plates, and enhances the cycle performance of the battery cells.

[0022] In some embodiments, the adsorbent polymer includes ester polymers, where 15 ≤ m1 / n ≤ 25; Optionally, Ester polymers are fabricated into sheet-like structures; the sheet-like structures are in (T m3 The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K2, 1<K2<∞, T m3 ℃ represents the melting temperature of the ester polymer; optionally, 1 < K2 ≤ 100; further optionally, 1 < K2 ≤ 10; further optionally, 1.1 ≤ K2 ≤ 2; Optionally, the glass transition temperature of the ester polymer is T. g3 ℃, -100≤T g3 ≤50; optionally, -80≤T g3 ≤30; further optionally, -50≤T g3 ≤0; Further, optionally, the ester polymer includes at least one of the compounds shown in formula (CI) to formula (CIII). Formula (CI), In formula (CI), R 31 R 32 and R 33 Each independently comprises a hydrogen atom, or a substituted or unsubstituted C1-C8 alkyl group; R 34 Including substituted or unsubstituted C1-C8 alkyl groups, or substituted or unsubstituted C1-C8 hydroxyalkyl groups; Formula (CII) In formula (CII), R 35 Includes substituted or unsubstituted C2-C6 methylene groups; optionally, R 35 Each independently includes substituted or unsubstituted C2-C4 methylene groups; Formula (CIII) In equation (CIII), R 36 R 37 and R 38 Each independently comprises a hydrogen atom, or a substituted or unsubstituted C1-C8 alkyl group; R 39 Including substituted or unsubstituted C1-C8 alkyl groups; Optionally, R 36 R 37 and R 38 Each independently comprises a hydrogen atom and a substituted or unsubstituted C1-C4 alkyl group; The degree of polymerization n of ester polymers is selected from any positive integer from 800 to 20000.

[0023] Therefore, when the ester polymers of the embodiments of this application meet the above-mentioned range, the molecular chain entanglement state can be further reduced, which is beneficial to the diffusion of solvent molecules in the electrolyte between molecular chains and to the formation of gel-like substances. Furthermore, the ester polymers still maintain a certain degree of molecular chain entanglement, which can effectively store electrolyte and improve the wetting performance of the active materials. At higher temperatures, the gel-like substances can release solvent molecules and restore the polymer state, thereby possessing a certain degree of elasticity. This allows the interface between the ester polymers and the active material particles to deform, enabling deformation during battery cycle charging and discharging. This reduces the risk of internal structure peeling off the electrode plates, improves the overall structural stability of the electrode plates, and enhances the cycle performance of the battery cells.

[0024] In some embodiments, the adsorbent polymer includes aldehyde-ketone polymers, where 7 ≤ m1 / n ≤ 12; Optionally, the aldehyde-ketone polymer is formed into a sheet-like structure; the sheet-like structure is in (T m4 The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K3, 0.8≤K3<∞, T m4 °C represents the melting temperature of the aldehyde-ketone polymer; optionally, 0.8 ≤ K3 ≤ 100; further optionally, 0.8 ≤ K3 ≤ 10; further optionally, 0.8 ≤ K3 ≤ 1; Optionally, the glass transition temperature of the aldehyde-ketone polymer is T. g4 ℃, -100≤T g4 ≤50; optionally, -80≤T g4 ≤30; further alternatively, -53≤T g4 ≤55; Further, optionally, the aldehyde-ketone polymer includes at least one of the compounds shown in formula (DI) and formula (DII). Formula (DI), In formula (DI), R 41 Including single-bonded, substituted, or unsubstituted C1-C6 methylene groups; R 42 Includes hydrogen atoms, substituted or unsubstituted C1-C6 alkyl groups; Formula (DII), In formula (DII), R 43 To R 46 Each of these components independently includes a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; r and s are each independently selected from integers from 0 to 5, and at least one of r and s is selected from any positive integer; The degree of polymerization n of aldehyde-ketone polymers is selected from any positive integer from 500 to 15000.

[0025] Therefore, when the aldehyde-ketone polymer of the present application satisfies the above-mentioned range, it can further reduce the molecular chain entanglement state, which is conducive to the diffusion of solvent molecules in the electrolyte between molecular chains and to the formation of gel-like substances. Furthermore, the aldehyde-ketone polymer still maintains a certain degree of molecular chain entanglement, which can effectively store electrolyte and improve the wetting performance of the active material. At higher temperatures, the gel-like substance can release solvent molecules and restore the polymer state, thereby possessing a certain degree of elasticity. This allows the interface between the aldehyde-ketone polymer and the active material particles to deform, thus enabling deformation during battery cycle charging and discharging, reducing the risk of internal structure peeling off the electrode plates, improving the overall structural stability of the electrode plates, and enhancing the cycle performance of the battery cells.

[0026] In some embodiments, the molecular weight of the adsorbed polymer is 2.0 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol.

[0027] In some embodiments, the electrode sheet is a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material and an adsorbed polymer. The positive electrode active material includes at least one of olivine-type phosphate active material and layered structure positive electrode active material.

[0028] In some embodiments, the electrode sheet is a negative electrode sheet, which includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material and an adsorbent polymer. The negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate.

[0029] Thirdly, this application proposes an electrical device, including a battery as described in the first or second aspect of this application. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced 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.

[0031] Figure 1This is a schematic diagram of one embodiment of the battery cell of this application.

[0032] Figure 2 yes Figure 1 An exploded view of the implementation method of the battery cell.

[0033] Figure 3 This is a schematic diagram of one embodiment of the battery module of this application.

[0034] Figure 4 This is a schematic diagram of one embodiment of the battery pack of this application.

[0035] Figure 5 yes Figure 4 An exploded view of an embodiment of the battery pack shown.

[0036] Figure 6 This is a schematic diagram of one embodiment of an electrical device that uses the battery cell of this application as a power source.

[0037] The accompanying drawings may not be drawn to scale.

[0038] The annotations in the attached figures are explained as follows: 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery module; 5. Battery cell; 51. Housing; 52. Electrode assembly; 53. Cover plate; 6. Electrical appliances. Detailed Implementation

[0039] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the electrode plates, battery, 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.

[0040] 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 the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, it is also expected that ranges of 60 to 110 and 80 to 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 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise stated, the numerical range "a to b" 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 to 5" means that all real numbers between "0 and 5" have been listed in this article; "0 to 5" is just a shortened representation of these numerical combinations. In addition, when a parameter is stated as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0042] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0043] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means 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.

[0044] In the embodiments of this application, the terms "multiple" or "multi-type" refer to two or more kinds.

[0045] The term "alkyl" encompasses both straight-chain and branched alkyl groups. For example, alkyl groups can be C1 to C5 alkyl, C1 to C4 alkyl, C1 to C3 alkyl, or C1 to C2 alkyl. In some embodiments, alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, etc. Additionally, alkyl groups may optionally be substituted. When substituted, the substituents include fluorine atoms.

[0046] The term "alkoxy group" refers to a group in which an alkyl group is bonded to an oxygen atom by a single bond. For example, an alkoxy group can be a C1-C5 alkoxy group, a C1-C3 alkoxy group, or a C1-C2 alkoxy group. In some embodiments, an alkoxy group may include a methoxy group, an ethoxy group, or a propoxy group. Additionally, an alkoxy group may optionally be substituted.

[0047] The term "halogen atom" refers to fluorine atoms, chlorine atoms, bromine atoms, etc.

[0048] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D), or 3H (tritium, T). In various embodiments, "hydrogen" may be 1H (protium, H).

[0049] The battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The positive electrode includes a positive electrode film layer containing a positive active material that can provide active ions. The negative electrode includes a negative electrode film layer containing a negative active material. The separator is placed between the positive and negative electrode and mainly serves to prevent short circuits between the positive and negative electrode, while allowing active ions to pass freely to form a circuit.

[0050] The active material layer often exhibits poor electrolyte affinity, resulting in poor electrolyte wetting and thus poor electrolyte storage capacity. During battery use, transportation, or assembly into modules, it may be subjected to external pressure, which can force the electrolyte out of the active material layer. This makes electrolyte reabsorption increasingly difficult, leading to battery capacity decay and deteriorating battery cycle performance.

[0051] In related technologies, introducing polymers capable of in-situ polymerization into the electrode sheets to lock in the electrolyte is considered. However, during the in-situ polymerization process to form an in-situ gel, this polymer essentially locks all the electrolyte inside, causing the electrolyte to lose its flow state. This results in a solid-solid interface between the polymer and the active material particles, leading to poor deformability of the electrode sheets. During battery cycle charging and discharging, the poor deformation adaptability of the electrode sheets makes them prone to solid-solid interface delamination, electrolyte breakage, and deterioration of battery cycle performance, thus failing to solve the aforementioned problems.

[0052] In view of the above problems, this application proposes an electrode sheet. The film layer of the electrode sheet includes an active material and an adsorbed polymer. The adsorbed polymer can physically adsorb electrolyte on the surface of the active material particles, forming a liquid-locking effect and improving the wetting performance of the electrolyte on the electrode sheet. Under liquid-deficient environments such as increased battery system temperature or dryness, it can elastically release electrolyte, thereby improving the deformation capability of the polymer and active material interface. During battery cycle charging and discharging, it can buffer the deformation of the adsorbed polymer and active material interface, improve the structural stability of the electrode sheet, and thus improve the cycle performance of the battery.

[0053] The technical solution of this application will now be described in detail.

[0054] Electrode plates In a first aspect, embodiments of this application propose an electrode sheet, comprising a current collector and a film layer disposed on at least one side of the current collector, wherein the film layer comprises an active material and an adsorbent polymer, wherein... The adsorbed polymer is added to a preset electrolyte at 45°C to form a polymer system. The mass ratio of the preset electrolyte to the adsorbed polymer is 15:1. The preset electrolyte includes dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and lithium hexafluorophosphate (LiPF6). The mass of dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate are the same, and the concentration of lithium hexafluorophosphate (LiPF6) is 1 mol / L. After the polymer system is allowed to stand at 45℃ for 60h and at 25℃ for ≥24h, the polymer system is filtered through a 200-mesh filter and the remaining first substance is obtained. The mass of the adsorbed polymer is n, in g, and the mass of the first substance is m1, in g. The adsorbed polymer and the first substance satisfy: 3≤m1 / n≤35. After drying the first substance at 60℃ for ≥24h, the second substance is obtained. The mass of the second substance is m2, and its unit is g. The second substance and the first substance satisfy: 1.00≤m2 / n≤1.05.

[0055] The pre-selected electrolyte has a composition similar to or essentially the same as the electrolyte in the battery. By mixing the adsorbed polymer with the pre-selected electrolyte, the state of the adsorbed polymer within the battery system can be simulated. Dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and ethylene carbonate (EC) can be considered as solvents for the pre-selected electrolyte, while lithium hexafluorophosphate (LiPF6) is the lithium salt of the pre-selected electrolyte.

[0056] After the polymer system is left to stand at 45°C for 60 hours and then at 25°C for ≥24 hours, undergoing two stages of standing treatment, at least a portion of the polymer system transforms into a gel-like substance. The polymer system after these two stages of standing treatment is then filtered through a 200-mesh filter, leaving the first substance. The pre-selected electrolyte that did not participate in the formation of the gel-like substance can be removed by filtration. In this embodiment, m1 / n can be defined as the precipitation value, which characterizes the ability of the adsorbed polymer and the pre-selected electrolyte to transform into a gel-like substance. The first substance mainly includes the gel-like substance formed by the adsorbed polymer and the pre-selected electrolyte; in this type of gel-like substance, the structural units of the adsorbed polymer remain essentially unchanged. 3≤m1 / n≤15 indicates that the adsorbed polymer has a strong ability to form a gel-like substance. At relatively high system temperatures, such as 45℃, the molecular chains can extend, promoting mutual attraction and physical bonding between the adsorbed polymer molecular chains and the solvent in the electrolyte. This facilitates the binding of the adsorbed polymer molecular chains and the solvent, thereby storing the electrolyte in the membrane layer. The adsorbed polymer may not be mobile within the lower safe operating temperature range of the battery, such as 25℃. It can remain attached to the surface of the active material and lock the electrolyte in the space where the adsorbed polymer is located, improving the electrolyte storage capacity of the membrane layer. Furthermore, the electrolyte has good wetting properties on the membrane layer, which is beneficial for normal lithium-ion transport. The adsorbed polymer also provides good protection for the active material, reducing interfacial side reactions, thereby improving the cycle performance of the secondary battery using the adsorbed polymer.

[0057] After the first substance is dried at 60°C for ≥24 hours, the second substance is obtained. The drying process is a process of loss of the preset electrolyte in the first substance. The preset electrolyte in the first substance gradually evaporates, and the remaining second substance mainly includes an adsorbed polymer. The adsorbed polymer has a structure and composition that is basically the same as the adsorbed polymer originally added to the preset electrolyte. In the embodiments of this application, m2 / n can be defined as the dehydration capacity, which can characterize the ability of the first substance to remove the preset electrolyte. 1.00≤m2 / n≤1.05 indicates that the content of the second substance and the adsorbed polymer is not much different, and the first substance has a strong ability to remove the preset electrolyte. After the adsorbed polymer forms a gel-state substance, it can release the preset electrolyte locked in the gel-state substance under relatively high temperature conditions or in environments with insufficient liquid such as dryness, thereby achieving elastic preset electrolyte storage. The adsorbed polymer remaining after the preset electrolyte is released can enhance the deformation capacity of the interface between the adsorbed polymer and the active material. During the battery cycle charge and discharge process, it can buffer the deformation of the interface between the adsorbed polymer and the active material, improve the structural stability of the electrode sheet, and thus improve the cycle performance of the battery.

[0058] In this embodiment, the adsorption of the electrolyte by the adsorbed polymer is a physically reversible adsorption process. At a slightly higher system temperature, such as the higher normal operating temperature of the battery system (first temperature), the adsorbed polymer can extend its molecular chains, promoting mutual attraction and physical bonding between the polymer molecular chains and the solvent, forming an in-situ gel-like substance. When the system temperature drops to the lower normal operating temperature of the battery system (second temperature), the in-situ gel-like substance can adhere to the surface of the active material particles, locking the electrolyte within the space where the adsorbed polymer is located, protecting the active material interface while facilitating normal lithium-ion transport. At even higher system temperatures, such as the higher normal operating temperature of the battery system (third temperature), or in dry, liquid-deficient environments, the locked electrolyte can be released, achieving flexible electrolyte storage. When the active particles expand and deform during charging and discharging, the gelled adsorbed polymer can promptly release the liquid electrolyte to buffer the deformation of the polymer / active particle interface, thereby improving the battery's cycle performance. In this embodiment, the second temperature is lower than the first temperature, and the first temperature is lower than the third temperature.

[0059] In this embodiment of the application, 3 ≤ m1 / n ≤ 35; optionally, 5 ≤ m1 / n ≤ 35. For example, m1 / n can be 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 or a range of any two of the above values.

[0060] In some embodiments, the adsorbent polymer may include at least one of fluorinated polymers, ether polymers, ester polymers, and aldehyde-ketone polymers. The adsorbent polymer can reversibly adsorb and desorb the electrolyte, enabling the electrolyte to effectively wet the active material and improve the structural stability of the electrode sheets, thereby enhancing the cycle performance of the battery cell.

[0061] The specific types of adsorbed polymers will be explained next.

[0062] [Fluoropolymers] In some embodiments, the adsorbent polymer may include a fluorinated polymer.

[0063] In some embodiments, the crystallinity of the fluorinated polymer, as determined by differential scanning calorimetry, is X. c1 %, 0 < X c1 ≤30. For example, the crystallinity X of the fluorinated polymer, measured by differential scanning calorimetry. c1% can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, or a range of any two of the above values.

[0064] In some embodiments, the melting temperature of the fluoropolymer is T. m1 ℃, 0 < T m1 ≤140. For example, the melting temperature of the polymer can be 10°C, 20°C, 50°C, 70°C, 90°C, 100°C, 120°C, 140°C, or a range of any two of the above values.

[0065] In some embodiments, the glass transition temperature of the fluorinated polymer is T. g1 ℃, -150≤T g1 ≤60. For example, the glass transition temperature of the fluoropolymer can be -150℃, -140℃, -135℃, -130℃, -125℃, -120℃, -110℃, -100℃, -90℃, -80℃, -70℃, -65℃, -60℃, -50℃, -45℃, -40℃, -35℃, -30℃, -25℃, -20℃, -15℃, -10℃, -5℃, 0℃, 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 40℃, 45℃, 50℃, 55℃, 60℃, or a range of any two of the above values.

[0066] Crystallization refers to the process by which atoms, ions, or molecules in a material arrange themselves in a specific spatial order to form an ordered structure. The conformation of adsorbed polymers during crystallization is determined by both intramolecular and intermolecular factors. Intermolecular forces affect the packing density between molecular chains. Crystallinity X C1 The degree of crystallinity in a material is characterized by differential scanning calorimetry (DSC). Specifically, the testing procedure is as follows: Take 0.5g to 0.8g of sample, place the sample in a crucible, and subject the sample to heating and cooling at a nitrogen atmosphere, with a heating rate of 10℃ / min from the intrinsic temperature of the material (T0). g1 The initial temperature was 20°C lower than the material's intrinsic temperature, and the temperature was increased to the material's intrinsic temperature. m1 The cutoff temperature for the 20°C increase is determined by the actual glass transition temperature T of the material, based on the peak values ​​of heat absorption and release or the transition point during the process. g1 and melting temperature T m1 wait.

[0067] Therefore, fluorinated polymers possess relatively low crystallinity, melting temperature, or glass transition temperature. The better the flexibility of the fluorinated polymer molecular chains, the better the segmental flexibility, and the easier it is for adjacent molecular chains to open. Solvent molecules in the electrolyte enter between the fluorinated polymer molecular chains, forming a gel-like substance. This effectively stores the electrolyte on the surface of the active material, improving its wetting performance. At higher temperatures, the gel-like substance can release solvent molecules, restoring the polymer state and thus possessing a certain degree of elasticity. This allows the interface between the fluorinated polymer and the active material particles to deform, enabling deformation during battery cycle charging and discharging. This reduces the risk of internal electrode structure peeling, improves the overall structural stability of the electrode, and enhances the cycle performance of the battery cell.

[0068] In some embodiments, the fluorinated polymer includes at least one of the compounds represented by formula (A1) to formula (AIII).

[0069] The compound represented by formula (AI) is shown below. Formula (AI) In formula (AI), R 11 R 12 R 13 and R 14 Each independently comprises a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group, and R 11 R 12 R 13 and R 14 At least one of them contains a fluorine atom.

[0070] Optionally, R 11 R 12 R 13 and R 14 Each of them independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1-C10 alkyl group, or a substituted or unsubstituted C1-C10 alkoxy group.

[0071] Optionally, R 11 R 12 R 13 and R 14 Each of them independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group.

[0072] Further optional, R 11 R 12 R 13 and R 14Each of these atoms independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, a fluoromethyl group, a methoxy group, or a perfluoromethoxy group.

[0073] In some embodiments, the degree of polymerization n of the fluoropolymer is selected from any positive integer from 1000 to 30000, such as 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, or a range of any two of the above values.

[0074] Optionally, when substituted, the substituent may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom. The halogen atom may include fluorine, bromine, etc., and may be a fluorine atom.

[0075] In some embodiments, the fluorinated polymer includes at least one of the compounds shown in formula (AI-1) to the compounds shown in formula (AI-11). Formula (AI-1) Formula (AI-2) Formula (AI-3) Formula (AI-4) Formula (AI-5) Formula (AI-6) Formula (AI-7) Formula (AI-8) Formula (AI-9) Formula (AI-10) Formula (AI-11).

[0076] The compounds represented by formula (AII) are shown below. Formula (AII), In formula (AII), R 11 R 12 R 13 and R 14 Each independently comprises a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group, and R 11 R 12 R 13 and R 14At least one of them contains a fluorine atom.

[0077] Optionally, R 11 R 12 R 13 and R 14 Each of them independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1-C10 alkyl group, or a substituted or unsubstituted C1-C10 alkoxy group.

[0078] Optionally, R 11 R 12 R 13 and R 14 Each of them independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group.

[0079] Further optional, R 11 R 12 R 13 and R 14 Each of these atoms independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, a fluoromethyl group, a methoxy group, or a perfluoromethoxy group.

[0080] In some embodiments, the degree of polymerization n of the fluoropolymer is selected from any positive integer from 1000 to 30000, such as 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, or a range of any two of the above values.

[0081] Optionally, when substituted, the substituent may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom. The halogen atom may include fluorine, bromine, etc., and may be a fluorine atom.

[0082] In some embodiments, the fluorinated polymer includes at least one of the compounds shown in formula (AII-1) to formula (AII-5). Formula (AII-1) Formula (AII-2) Formula (AII-3) Formula (AII-4) Formula (AII-5).

[0083] The compound represented by formula (AIII) is shown below. Formula (AIII) In equation (AIII), R 15 Includes single bonds, substituted or unsubstituted alkyl groups; when substituted, the substituents include fluorine atoms.

[0084] In some embodiments, when substituted, the substituent may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom.

[0085] Optionally, R 15 Includes single-bonded, substituted or unsubstituted C1-C3 alkyl groups.

[0086] In some implementations, p is selected from any positive integer from 1 to 3, such as 1, 2, or 3.

[0087] In some embodiments, the degree of polymerization n of the fluoropolymer is selected from any positive integer from 1000 to 30000, such as 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, or a range of any two of the above values.

[0088] In some embodiments, the fluorinated polymer includes at least one of the compounds shown in formula (AIII-1) to formula (AIII-3). Formula (AIII-1) Formula (AIII-2) Formula (AIII-3).

[0089] For example, fluorinated polymers include one or more of the following: perfluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroethylene-propylene copolymer (FEP), perfluoroalkoxy polymer (PFA), perfluoropolyether (PFPE), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE), and perfluoro(1-butenyl vinyl ether) polymer (CYTOP).

[0090] Optionally, the fluorinated polymer includes one or more of the following: perfluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroethylene propylene copolymer (FEP), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE).

[0091] The aforementioned fluorinated polymers can be derived from one or more of the following monomers: fluorinated cyclohexane, fluorinated vinylidene, 1,2-difluoroethylene, vinylidene fluoride, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropylene, trifluoropropylene, tetrafluoropropylene, and pentafluoropropylene. Optionally, the aforementioned fluorinated polymers can be derived from at least two of the following monomers: fluorinated cyclohexane, fluorinated vinylidene, 1,2-difluoroethylene, vinylidene fluoride, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropylene, trifluoropropylene, tetrafluoropropylene, and pentafluoropropylene.

[0092] In embodiments of this application, the polymer can also be obtained by copolymerizing the above-mentioned structural groups with small amounts of other types of structural groups (e.g., olefin compounds, ester monomers, nitrile monomers such as acrylonitrile, amide monomers such as acrylamide, acrylic acid, etc.). These small amounts of monomers have relatively poor hydrophilic properties; copolymerizing the monomers of the above-mentioned fluorinated polymer with these monomers can improve the swelling ratio and compressive modulus of the adsorbed polymer.

[0093] In some embodiments, the molecular weight of the adsorbed polymer is 2 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol.

[0094] For example, the molecular weight of the adsorbed polymer can be 2 × 10⁻⁶. 5 g / mol, 5×10 5 g / mol, 8×10 5 g / mol, 1×10 6 g / mol, 1.2×10 6 g / mol or a range consisting of any two of the above values.

[0095] [Ether polymers] In some embodiments, the adsorbent polymer includes ether polymers.

[0096] In some embodiments, the ether polymer is formed into a sheet-like structure; the sheet-like structure is in (T m2 The elastic modulus G' - energy dissipation modulus G'' curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G'' curve is K1, 1 < K1 < ∞, T m2°C indicates the melting temperature of ether polymers.

[0097] Specifically, the preparation process of the sheet-like structure is as follows: The ether polymer is vacuum dried at 80°C for 12 hours. The dried ether polymer is then hot-pressed into thin sheets using a flat vulcanizing machine, with the hot-pressing temperature set to (T...). m2 The temperature is +20℃, the calendering thickness is 1-2 min, the calendering time is 2 min, and the pressure is 8 MPa. After calendering for 2 min, the sample is removed and placed on another vulcanizing machine of the same model for cold pressing at a pressure of 10 MPa. Polymer discs (sheet-like structures) of a fixed size can be obtained using a circular mold with a diameter of 25 mm. For example, the sheet-like structure can be a disc with a thickness of 1-2 mm and a diameter of 25 mm; it can also be prepared according to the sample standard required by the testing equipment.

[0098] According to the conclusions of classical linear viscoelasticity, for polymers, especially linear polymers, the elastic modulus G'-energy dissipation modulus G" in the terminal region (the range approaching the maximum angular velocity) follows a frequency dependence, and the longest chain of the polymer plays a role in the viscoelastic behavior.

[0099] The specific steps of the dynamic frequency scanning test are as follows: A TA-AR2000EX rotational rheometer (TA Instruments, USA) is used for the dynamic frequency scanning test. The parallel plate diameter is 25mm and the thickness is 0.9mm. To ensure the test is conducted within the linear springback region, the strain during the dynamic frequency scanning test is 2%, and the test temperature is (T... m2 +20℃, test frequency sweep range: 500rad / s ≤ w 2 ≤0.05rad / s, so as to obtain data in the lowest possible frequency range.

[0100] Dynamic frequency scanning tests can characterize the degree of molecular chain entanglement under solid-state melting (molten state). Compared with linear or short-branched structures, long-branched, network, and low-crosslinked structures have a high degree of entanglement and exhibit deviations from linear end-product behavior. Ether polymers exhibit solid-state behavior. When the ether polymers of this application meet the above-mentioned range, the molecular chain entanglement state can be further reduced, which is beneficial to the diffusion of solvent molecules in the electrolyte between molecular chains and to the formation of gel-like substances. Furthermore, the ether polymers still maintain a certain degree of molecular chain entanglement, which can effectively store electrolyte and improve the wetting performance of active materials. At higher temperatures, the gel-like substances can release solvent molecules and restore the polymer state, thereby possessing a certain degree of elasticity. This allows the interface between the ether polymer and the active material particles to deform, enabling deformation during battery cycle charging and discharging. This reduces the risk of internal structure peeling off the electrode sheets, improves the overall structural stability of the electrode sheets, and enhances the cycle performance of the battery cells.

[0101] In some implementations, 1 < K1 ≤ 100; alternatively, 1 < K1 ≤ 10. For example, K1 can be 1.01, 1.1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000 or a range of any two of the above values.

[0102] In some embodiments, the glass transition temperature of the ether polymer is T. g2 ℃, -100≤T g2 ≤50; optionally, -80≤T g2 ≤30. For example, the glass transition temperature of the ether polymer can be -100℃, -90℃, -80℃, -70℃, -65℃, -60℃, -50℃, -45℃, -40℃, -35℃, -30℃, -25℃, -20℃, -15℃, -10℃, -5℃, 0℃, 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 40℃, 45℃, 50℃, or a range of any two of the above values. Ether polymers exhibit a certain degree of flexibility above their glass transition temperature, which is beneficial for forming gel-like substances, improving the wetting effect on the electrode sheets, and enhancing battery cycle performance.

[0103] In some embodiments, the ether polymer includes compounds represented by formula (BI). Formula (BI), In formula (BI), R 21 and R 22 Each independently comprises a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group; R 23 This includes single bonds, substituted or unsubstituted methylene groups.

[0104] Optionally, R 21 and R 22 Each of them independently includes a hydrogen atom, a substituted or unsubstituted C1-C10 alkyl group, or a substituted or unsubstituted C1-C10 alkoxy group.

[0105] Optionally, R 21 and R 22 Each of them independently includes a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group.

[0106] Optionally, R 23 Includes single-bonded, substituted or unsubstituted C1-C10 methylene groups.

[0107] Optionally, R 23 This includes single-bonded, substituted, or unsubstituted C1-C5 methylene groups.

[0108] For example, the ether polymer includes at least one of the compounds shown in formula (BI-1) to formula (BI-8). Formula (BI-1), Formula (BI-2), Formula (BI-3), Formula (BI-4), Formula (BI-5), Formula (BI-6), Formula (BI-7), Formula (BI-8).

[0109] In some embodiments, the ether polymer includes compounds represented by formula (BII). Formula (BII) In formula (BII), R 24 To R 27 Each independently comprises a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or an ether group, and R 24 To R 27 At least one of them contains a substituted or unsubstituted alkoxy or ether group.

[0110] Optionally, R 24 To R 27 Each of them independently includes a hydrogen atom, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, or an ether group.

[0111] Optionally, R 24 To R 27 Each of these groups independently includes a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group.

[0112] In some embodiments, the ether polymer includes at least one of the compounds shown in formula (BII-1) to formula (BII-7). Formula (BII-1) Formula (BII-2) Formula (BII-3) Formula (BII-4) Formula (BII-5) Formula (BII-6) (BII-7).

[0113] The polymers described above are merely examples of structural groups in the main molecular chains. In embodiments of this application, the polymers may also be obtained by copolymerizing the above structural groups with small amounts of other types of structural groups (e.g., olefin compounds, ester monomers, nitrile monomers such as acrylonitrile, amide monomers such as acrylamide, acrylic acid, etc.).

[0114] When the above groups are substituted, the substituents may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom. The halogen atom may include at least one of the following: fluorine atom and bromine atom; alternatively, it may be a fluorine atom.

[0115] In some embodiments, the degree of polymerization n of the ether polymer is selected from any positive integer from 1500 to 25000, such as 1500, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, or a range of any two of the above values.

[0116] Optionally, the degree of polymerization n of the ether polymer is selected from any positive integer from 3000 to 18000.

[0117] In some embodiments, the molecular weight of the adsorbed polymer is 2 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol. For example, the molecular weight of the polymer can be 2 × 10⁻⁶ g / mol. 5 g / mol, 5×10 5 g / mol, 8×10 5 g / mol, 1×10 6 g / mol, 1.2×10 6 g / mol or a range consisting of any two of the above values.

[0118] [Ester polymers] In some embodiments, the adsorbent polymer includes ester polymers.

[0119] In some embodiments, the ester polymer is formed into a sheet-like structure; the sheet-like structure is in (T m3 The elastic modulus G' - energy dissipation modulus G'' curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G'' curve is K2, 1 < K2 < ∞, T m3 °C represents the melting temperature of ester polymers.

[0120] Specifically, the preparation process of the sheet-like structure is similar to that of ether polymers, and will not be elaborated here. When the ester polymers of this application meet the above-mentioned requirements, they can further reduce the molecular chain entanglement state, which is beneficial for the diffusion of solvent molecules in the electrolyte between the molecular chains and for the formation of gel-like substances. Furthermore, the ester polymers still maintain a certain degree of molecular chain entanglement, effectively storing the electrolyte and improving the wetting performance of the active materials. At higher temperatures, the gel-like substances can release solvent molecules, restoring the polymer state and thus possessing a certain degree of elasticity. This allows the interface between the ester polymer and the active material particles to deform, enabling deformation during battery cycle charging and discharging. This reduces the risk of internal structure peeling off the electrode sheets, improves the overall structural stability of the electrode sheets, and enhances the cycle performance of the battery cells.

[0121] In some implementations, 1 < K2 ≤ 100; alternatively, 1 < K2 ≤ 10. For example, K2 can be 1.01, 1.1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000 or a range of any two of the above values.

[0122] In some embodiments, the glass transition temperature of the ester polymer is T. g3 ℃, -100≤T g3 ≤50; optionally, -80≤T g3 ≤30; For example, the glass transition temperature of ester polymers can be -100℃, -90℃, -80℃, -70℃, -65℃, -60℃, -50℃, -45℃, -40℃, -35℃, -30℃, -25℃, -20℃, -15℃, -10℃, -5℃, 0℃, 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 40℃, 45℃, 50℃, or a range of any two of the above values. Ester polymers have a certain degree of flexibility above the glass transition temperature, which is conducive to the formation of gel-like substances, improving the wetting effect on the electrode sheets and enhancing the battery cycle performance.

[0123] In some embodiments, the ester polymer includes compounds represented by formula (CI). Formula (CI), In formula (CI), R 31 R 32 and R 33 Each independently comprises a hydrogen atom, or a substituted or unsubstituted alkyl group; R 34 This includes substituted or unsubstituted alkyl groups, or substituted or unsubstituted hydroxyalkyl groups.

[0124] Optionally, R 31 R32 and R 33 Each of them independently includes a hydrogen atom or a substituted or unsubstituted C1-C10 alkyl group.

[0125] Optionally, R 31 R 32 and R 33 Each of them independently includes a hydrogen atom or a substituted or unsubstituted C1-C8 alkyl group.

[0126] In some implementations, R 34 This includes substituted or unsubstituted C1-C10 alkyl groups, or substituted or unsubstituted C1-C10 hydroxyalkyl groups.

[0127] In some implementations, R 34 This includes substituted or unsubstituted C1-C8 alkyl groups, or substituted or unsubstituted C1-C8 hydroxyalkyl groups.

[0128] In some implementations, R 31 This includes hydrogen atoms, or substituted or unsubstituted methyl groups.

[0129] In some implementations, R 32 and R 33 Each of them independently contains a hydrogen atom.

[0130] By way of example, ester polymers include at least one of the compounds shown in formula (CI-1) to the compounds shown in formula (CI-15). Formula (CI-1) Formula (CI-2) Formula (CI-3) Formula (CI-4) Formula (CI-5) Formula (CI-6) Formula (CI-7) Formula (CI-8) Formula (CI-9) Formula (CI-10) Formula (CI-11) Formula (CI-12) Formula (CI-13) Formula (CI-14) Formula (CI-15).

[0131] In some embodiments, the ester polymer includes compounds represented by formula (CII). Formula (CII) In formula (CII), R 35 This includes substituted or unsubstituted methylene groups.

[0132] Optionally, R 35 This includes substituted or unsubstituted C1-C10 methylene groups.

[0133] Optionally, R 35 This includes substituted or unsubstituted C2-C6 methylene groups.

[0134] Optionally, R 35 This includes substituted or unsubstituted C2-C4 methylene groups.

[0135] For example, the ester polymer includes at least one of the compounds shown in formula (CII-1) to the compounds shown in formula (CII-5). Formula (CII-1) Formula (CII-2) Formula (CII-3) Formula (CII-4) (CII-5).

[0136] In some embodiments, the ester polymer includes compounds represented by formula (CIII). Formula (CIII) In equation (CIII), R 36 R 37 and R 38 Each independently comprises a hydrogen atom, or a substituted or unsubstituted C1-C8 alkyl group; R 39 Including substituted or unsubstituted C1-C8 alkyl groups; Optionally, R 36 R 37 and R 38 Each of them independently includes a hydrogen atom and a substituted or unsubstituted C1-C4 alkyl group.

[0137] By way of example, the ester polymer includes at least one of the compounds shown in formula (CIII-1) to the compounds shown in formula (CIII-5). Formula (CIII-1) Formula (CIII-2) Formula (CIII-3) Formula (CIII-4) Formula (CIII-5) Formula (CIII-6).

[0138] The above-mentioned polymers are merely examples of structural groups of the main molecular chains. In the embodiments of this application, the adsorbent polymer can also be obtained by copolymerizing the above-mentioned structural groups with a small amount of other types of structural groups (such as olefin compounds, ester monomers, nitrile monomers such as acrylonitrile, amide monomers such as acrylamide, acrylic acid, etc.).

[0139] When the above groups are substituted, the substituents may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom.

[0140] In some embodiments, the degree of polymerization n of the ester polymer is selected from any positive integer from 800 to 20000, such as 800, 1000, 1500, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, or a range of any two of the above values.

[0141] In some embodiments, the degree of polymerization n of the ester polymer is selected from any positive integer from 1000 to 15000.

[0142] In some embodiments, the molecular weight of the adsorbed polymer is 2 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol.

[0143] For example, the molecular weight of the adsorbed polymer can be 2 × 10⁻⁶. 5 g / mol, 5×10 5 g / mol, 8×10 5 g / mol, 1×10 6 g / mol, 1.2×10 6 g / mol or a range consisting of any two of the above values.

[0144] [Aldehyde-ketone polymers] In some embodiments, the adsorbent polymer includes aldehyde-ketone polymers.

[0145] In some embodiments, the aldehyde-ketone polymer is formed into a sheet-like structure; the sheet-like structure is in (T m4 The elastic modulus G' - energy dissipation modulus G'' curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G'' curve is K3, 0.8≤K3<∞, T m4°C indicates the melting temperature of the aldehyde-ketone polymer.

[0146] Specifically, the preparation process of the sheet-like structure is similar to that of ether polymers and will not be elaborated here. When the aldehyde-ketone polymer of this application meets the above-mentioned range, it can further reduce the molecular chain entanglement state, which is conducive to the diffusion of solvent molecules in the electrolyte between the molecular chains and to the formation of gel-like substances. Furthermore, the aldehyde-ketone polymer still maintains a certain degree of molecular chain entanglement, which can effectively store electrolyte and improve the wetting performance of active materials. At higher temperatures, the gel-like substances can release solvent molecules and restore the polymer state, thereby possessing a certain degree of elasticity. This allows the interface between the aldehyde-ketone polymer and the active material particles to deform, thus enabling deformation during battery cycle charging and discharging, reducing the risk of internal structure peeling off the electrode sheet, improving the overall structural stability of the electrode sheet, and enhancing the cycle performance of the battery cell.

[0147] In some implementations, 0.8 ≤ K3 ≤ 100; alternatively, 0.8 ≤ K3 ≤ 10. For example, K3 can be 0.8, 0.85, 0.9, 1, 1.01, 1.1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000, or a range of any two of the above values.

[0148] In some embodiments, the glass transition temperature of the aldehyde-ketone polymer is T. g4 ℃, -100≤T g4 ≤50; optionally, -80≤T g4 ≤30; For example, the glass transition temperature of the aldehyde-ketone polymer can be -100℃, -90℃, -80℃, -70℃, -65℃, -60℃, -50℃, -45℃, -40℃, -35℃, -30℃, -25℃, -20℃, -15℃, -10℃, -5℃, 0℃, 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 40℃, 45℃, 50℃, or a range of any two of the above values. Aldehyde-ketone polymers exhibit a certain degree of flexibility above their glass transition temperature, which facilitates the formation of gel-like substances, improves the wetting effect on the electrode sheets, and enhances battery cycle performance.

[0149] In some embodiments, the aldehyde-ketone polymer comprises compounds represented by formula (DI). Formula (DI), In formula (DI), R 41 Including single-bonded, substituted, or unsubstituted C1-C6 methylene groups; R 42 Includes hydrogen atoms, substituted or unsubstituted C1-C6 alkyl groups.

[0150] Optionally, R41 This includes single-bonded, substituted, or unsubstituted C1-C2 methylene groups.

[0151] Optionally, R 42 Includes hydrogen atoms, substituted or unsubstituted C1-C3 alkyl groups.

[0152] In the embodiments of this application, a single bond indicates that the group does not exist, and the atoms on both sides of the group are connected by a single bond, such as R. 41 A single bond, representing R 41 The carbon atoms on both sides are connected by single bonds.

[0153] By way of example, the aldehyde-ketone polymer includes at least one of the compounds shown in formula (DI-1) to the compounds shown in formula (DI-6). Formula (DI-1) Formula (DI-2) Formula (DI-3) Formula (DI-4) Formula (DI-5) Formula (DI-6).

[0154] For example, aldehyde-ketone polymers include compounds represented by formula (DII). Formula (DII), In formula (DII), R 43 To R 46 Each independently includes a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; r and s are each independently selected from integers from 0 to 5, and at least one of r and s is selected from any positive integer.

[0155] Optionally, R 43 To R 46 Each of these components independently includes a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C2 hydroxyalkyl group, or a substituted or unsubstituted C1-C2 alkoxy group.

[0156] In some embodiments, the aldehyde-ketone polymer includes at least one of the compounds shown in formula (DII-1) to formula (DII-4). Formula (DII-1), Formula (DII-2), Formula (DII-3), Formula (DII-4).

[0157] The polymers described above are merely examples of structural groups in the main molecular chains. In embodiments of this application, the polymers can also be obtained by copolymerizing the above structural groups with other types of structural groups (such as olefin compounds, enol compounds, acrylonitrile compounds, etc.).

[0158] When the above groups are substituted, the substituents may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom. The halogen atom may include at least one of the following: fluorine, bromine, and chlorine.

[0159] In some embodiments, the degree of polymerization n of the aldehyde-ketone polymer is selected from any positive integer from 500 to 15000, such as 500, 800, 1000, 1500, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, or a range of any two of the above values.

[0160] Optionally, the degree of polymerization n of the aldehyde-ketone polymer is selected from any positive integer from 500 to 10000.

[0161] In some embodiments, the molecular weight of the aldehyde-ketone polymer is 1.2 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol.

[0162] For example, the molecular weight of the aldehyde-ketone polymer can be 1.2 × 10⁻⁶. 5 g / mol, 2×10 5 g / mol, 5×10 5 g / mol, 8×10 5 g / mol, 1×10 6 g / mol, 1.0×10 6 g / mol, 1.2×10 6 g / mol or a range consisting of any two of the above values.

[0163] The relevant parameters of the adsorbent polymer in the embodiments of this application can be detected by the following methods: The functional groups of the adsorbed polymer in the embodiments of this application can be detected by infrared spectrophotometry (IR). Specifically, the adsorbed polymer is tested using a Thermo Nicolet Nexus 670 attenuated total reflectance Fourier transform infrared spectrometer (FTIR-ATR), and then tested according to standard GB / T6040-2002. The test range is 600~4000 cm⁻¹ using the ATR method. -1 Repeatability: ±2cm-1 Resolution: better than 4cm -1 ; Transmission depth 0.2~0.6μm.

[0164] The structure of the adsorbed polymer in the embodiments of this application can be determined by nuclear magnetic resonance (NMR). Specifically, 1H NMR and 13C NMR are performed on a Varian Mercury Plus-400 NMR spectrometer at a test temperature of 20°C, with TMS as an internal standard, CDCl3 as a solvent, and a proton resonance frequency of 400MHz.

[0165] The polymer monomer type of the adsorbed polymer in this embodiment (especially suitable for monomers with a small proportion in the polymer) can be determined by pyrolysis-gas chromatography-mass spectrometry. The specific test steps are as follows: Accurately weigh 0.5 mg of sample into a sample cup, fix it to the injection rod, and then place it into the pyrolyzer installed near the GC (gas chromatography) injection port. After the pyrolyzer temperature reaches the set temperature, press the injection button. The sample cup will fall rapidly into the core of the pyrolysis furnace through free fall. In the inert gas N2 atmosphere, the volatile components will instantly vaporize and be carried into the gas chromatography column by the carrier gas for separation. Finally, it will be detected by flame ionization detector (FID) or mass spectrometer (MS) to obtain a gas chromatogram or total ion chromatogram.

[0166] The molecular weight of the adsorbent polymer in the embodiments of this application has a meaning known in the art and can be determined using commonly used equipment and methods in the art. It can be tested by gel permeation chromatography (GPC) according to GB / T21863-2008. The specific test steps are as follows: take an appropriate amount of the sample to be tested (the sample concentration should be 8%-12% opacity), add 20 ml of deionized water, and simultaneously incubate for 5 min (53 kHz / 120 W) to ensure that the sample is completely dispersed. Then, the sample is measured according to GB / T19077-2016 / ISO 13320:2009.

[0167] [Positive electrode plate] In some embodiments, the electrode sheet includes a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive active material and an adsorbed polymer. In this case, the negative electrode sheet may include a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative active material and an adsorbed polymer. Alternatively, the negative electrode sheet may include a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative active material, i.e., it does not contain an adsorbed polymer.

[0168] In other embodiments, the electrode assembly includes a negative electrode sheet, which includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material and an adsorbed polymer. In this case, the positive electrode film layer may include a positive electrode active material, i.e., it does not contain a fluorinated polymer.

[0169] Further research revealed that when both the positive and negative electrode films contain adsorbed polymers, the adsorbed polymers can improve the interfacial performance and structural stability of both the positive and negative electrode films, thereby effectively enhancing the cycle performance of the battery cell.

[0170] In some embodiments, the mass content of the adsorbed polymer is ≤5% based on the total mass of the positive electrode film; optionally, it is 0.05% to 5%; further optionally, it is 0.05% to 2%. When the mass content of the adsorbed polymer is within the above range, the adsorbed polymer can effectively improve the interfacial properties and structural stability of the positive electrode sheet.

[0171] For example, the mass content of the adsorbed polymer can be 0.05%, 0.08%, 0.10%, 0.11%, 0.12%, 0.15%, 0.16%, 0.18%, 0.20%, 0.22%, 0.25%, 0.28%, 0.30%, 0.32%, 0.35%, 0.38%, 0.40%, 0.42%, 0.45%, 0.48%, 0.50%, 0.55%, 0.58%, 0.60%, 0.70%, 0.80%, 0.90%, 0.95%, 1%, 1.1%, 1.2%, 1.3%. %, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, or a range consisting of any two of the above values.

[0172] In some embodiments, the coating weight of the adsorbent polymer is 0.05 mg / 1540.25 mm. 2 Up to 5mg / 1540.25mm 2 For example, 0.05mg / 1540.25mm 2 0.1mg / 1540.25mm 2 0.2mg / 1540.25mm 2 , 0.5mg / 1540.25mm2 、0.6mg / 1540.25mm 2 、0.7mg / 1540.25mm 2 、0.8mg / 1540.25mm 2 、0.9mg / 1540.25mm 2 、1.0mg / 1540.25mm 2 、1.1mg / 1540.25mm 2 、1.2mg / 1540.25mm 2 、1.3mg / 1540.25mm 2 、1.4mg / 1540.25mm 2 、1.5mg / 1540.25mm 2 、1.6mg / 1540.25mm 2 、1.7mg / 1540.25mm 2 、1.8mg / 1540.25mm 2 、1.9mg / 1540.25mm 2 、2.0mg / 1540.25mm 2 、2.1mg / 1540.25mm 2 、2.2mg / 1540.25mm 2 、2.3mg / 1540.25mm 2 、2.4mg / 1540.25mm 2 、2.5mg / 1540.25mm 2 、2.6mg / 1540.25mm 2 、2.7mg / 1540.25mm 2 、2.8mg / 1540.25mm 2 、2.9mg / 1540.25mm 2 、3.0mg / 1540.25mm 2 、3.1mg / 1540.25mm 2 、3.2mg / 1540.25mm 2 、3.3mg / 1540.25mm 2 、3.4mg / 1540.25mm 2 、3.5mg / 1540.25mm 2 、3.6mg / 1540.25mm 2 、3.7mg / 1540.25mm 2 、3.8mg / 1540.25mm 2 、3.9mg / 1540.25mm 24.0mg / 1540.25mm 2 4.1mg / 1540.25mm 2 4.2mg / 1540.25mm 2 4.3mg / 1540.25mm 2 4.4mg / 1540.25mm 2 4.5mg / 1540.25mm 2 4.6mg / 1540.25mm 2 4.7mg / 1540.25mm 2 4.8mg / 1540.25mm 2 4.9mg / 1540.25mm 2 5.0mg / 1540.25mm 2 Or it can be a range consisting of any two of the above values. The coating weight of the adsorbed polymer is the coating weight of the positive electrode film layer on one side of the positive electrode sheet.

[0173] In this application, the polymer mass content has a meaning known in the art and can be detected using equipment and methods known in the art. For example, it can be detected using thermogravimetric analysis (TGA) according to JYT014-1996. Specifically, based on the mass loss of the electrode during the heating process, a mass-temperature curve, i.e., a TG curve, is plotted. The mass loss corresponding to the polymer decomposition temperature is read as the total mass of the polymer in the electrode, thereby calculating the polymer mass content and coating weight. During the test, the following temperature rise program can be used in a nitrogen atmosphere: 5℃ / min, RT~500℃; 10℃ / min, 500~600℃; constant temperature at 600℃ for 10 min, then end.

[0174] The positive electrode film includes a positive electrode active material, which may be a positive electrode active material known in the art for use in battery cells. As an example, the positive electrode active material contains a lithium positive electrode active material, which may include at least one of the following materials: olivine-type phosphate active material and layered structure positive electrode active material.

[0175] For example, the general formula of olivine-type phosphate active substances (containing lithium phosphate compounds) is: Li x A y Me a M b P 1-c X c Y zWherein, 0≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F. Specifically, olivine-type phosphate active substances include one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0176] For example, layered cathode active materials (such as ternary, lithium nickel oxide / sodium, lithium cobalt oxide / sodium, lithium manganese oxide / sodium, lithium-rich layered, and rock salt phase layered materials). The general formula for layered cathode active materials is: Li x A y Ni a Co b Mn c M (1-a-b-c) Y z Wherein, 0≤x≤2.1, 0≤y≤2.1, and 0.9≤x+y≤2.1; 0≤a≤1, 0≤b≤1, 0≤c≤1, and 0.1≤a+b+c≤1; 1.8≤z≤3.5; A includes one or more of Na, K, and Mg; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; Y includes one or more of O and F. Optionally, y=0. Specifically, the layered structure positive electrode active material may include lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium manganese oxide (LMO), and LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NML33), LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 One or more of O2 (NCM811) and NCA.

[0177] During the charging and discharging process, active ions such as Li undergo insertion / extraction and consumption in a single battery cell. The molar content of Li varies depending on the discharge state of the cell. In the examples of positive electrode active materials in this application, the molar content of Li refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar content of Li may change when the positive electrode active material is applied to the battery system.

[0178] In the embodiments of this application, the molar content of oxygen (O) in the positive electrode active material is only a theoretical value. Oxygen release from the crystal lattice will cause the molar content of oxygen (O) to change. In reality, the molar content of oxygen (O) will fluctuate.

[0179] In the embodiments of this application, the modified compound may be modified by doping or coating. Doping modification may involve adding doping elements such as transition metals to the compound, while coating modification may involve surface coating with materials such as carbon, that is, forming a carbon coating layer on the outer surface of the particles.

[0180] In some embodiments, the mass content of the positive electrode active material is 80% to 99.9%, optionally 90% to 99%, based on the total mass of the positive electrode film. When the mass content of the positive electrode active material is within the above range, it is beneficial to improve the energy density of the battery cell.

[0181] In some embodiments, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer can be disposed on either or both of the two opposite surfaces of the positive current collector.

[0182] In some embodiments, the positive current collector may be a metal foil or a composite current collector. Examples of metal foils include aluminum foil or aluminum alloy foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. Examples of the metal material include one or more combinations selected from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The polymer substrate may include one or more combinations selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0183] In some embodiments, the positive electrode film layer may optionally include a positive electrode conductive agent. This application does not impose particular limitations on the type of positive electrode conductive agent. As an example, the positive electrode conductive agent includes one or more combinations selected from superconducting carbon, conductive carbon black, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the positive electrode conductive agent is less than 5% based on the total mass of the positive electrode film layer.

[0184] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. This application does not impose particular limitations on the type of positive electrode binder. As an example, the positive electrode binder may include one or more combinations selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins. In some embodiments, the mass percentage of the positive electrode binder is less than 5% based on the total mass of the positive electrode film layer. Compared to the crystallinity of the fluorinated polymers in this application, the positive electrode binder has a higher crystallinity.

[0185] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing the positive electrode active material, adsorbent polymer, optional conductive agent, optional binder, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to this. Of course, the preparation of the positive electrode sheet is not limited to the above methods; the preparation methods described earlier can also be used.

[0186] [Negative electrode plate] In some embodiments, the electrode sheet includes a negative electrode sheet, which includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material and an adsorbed polymer.

[0187] In some embodiments, the mass content of the adsorbed polymer is ≤6% based on the total mass of the negative electrode film; optionally ≤5%; optionally from 0.05% to 5%. When the mass content of the adsorbed polymer is within the above range, the adsorbed polymer can effectively improve the interfacial properties and structural stability of the negative electrode sheet.

[0188] For example, the mass content of the adsorbed polymer can be 0.05%, 0.08%, 0.10%, 0.11%, 0.12%, 0.15%, 0.16%, 0.18%, 0.20%, 0.22%, 0.25%, 0.28%, 0.30%, 0.32%, 0.35%, 0.38%, 0.40%, 0.42%, 0.45%, 0.48%, 0.50%, 0.55%, 0.58%, 0.60%, 0.70%, 0.80%, 0.90%, 0.95%, 1%, 1.1%, 1.2%, 1.3%. %, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, or a range consisting of any two of the above values.

[0189] In some embodiments, the coating weight of the adsorbent polymer is 0.5 mg / 1540.25 mm. 2 Up to 5mg / 1540.25mm 2 For example, 0.5mg / 1540.25mm 2 0.6mg / 1540.25mm 2 0.7mg / 1540.25mm 2 0.8mg / 1540.25mm 2 0.9mg / 1540.25mm 2 1.0mg / 1540.25mm 2 1.1mg / 1540.25mm 2 1.2mg / 1540.25mm 2 1.3mg / 1540.25mm 2 1.4mg / 1540.25mm 2 1.5mg / 1540.25mm 2 1.6mg / 1540.25mm 2 1.7mg / 1540.25mm 2 1.8mg / 1540.25mm 2 1.9mg / 1540.25mm 2 2.0mg / 1540.25mm 2 2.1mg / 1540.25mm 22.2mg / 1540.25mm 2 2.3mg / 1540.25mm 2 2.4mg / 1540.25mm 2 2.5mg / 1540.25mm 2 2.6mg / 1540.25mm 2 2.7mg / 1540.25mm 2 2.8mg / 1540.25mm 2 2.9mg / 1540.25mm 2 3.0mg / 1540.25mm 2 3.1mg / 1540.25mm 2 3.2mg / 1540.25mm 2 3.3mg / 1540.25mm 2 3.4mg / 1540.25mm 2 3.5mg / 1540.25mm 2 3.6mg / 1540.25mm 2 3.7mg / 1540.25mm 2 3.8mg / 1540.25mm 2 3.9mg / 1540.25mm 2 4.0mg / 1540.25mm 2 4.1mg / 1540.25mm 2 4.2mg / 1540.25mm 2 4.3mg / 1540.25mm 2 4.4mg / 1540.25mm 2 4.5mg / 1540.25mm 2 4.6mg / 1540.25mm 2 4.7mg / 1540.25mm 2 4.8mg / 1540.25mm 2 4.9mg / 1540.25mm 2 5.0mg / 1540.25mm 2 Or it can be a range consisting of any two of the above values. The coating weight of the adsorbed polymer is the coating weight of the negative electrode film layer on one side of the negative electrode sheet.

[0190] The negative electrode active material may be any negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include at least one of elemental tin, tin oxide, and tin alloys.

[0191] In some embodiments, the negative electrode current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0192] In some embodiments, the negative electrode film layer may optionally include a negative electrode conductive agent. This application does not impose particular limitations on the type of negative electrode conductive agent. As an example, the negative electrode conductive agent may include at least one selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the negative electrode conductive agent is ≤5% based on the total mass of the negative electrode film layer.

[0193] In some embodiments, the negative electrode film layer may optionally include a negative electrode binder. This application does not impose particular limitations on the type of negative electrode binder. As an example, the negative electrode binder may include at least one 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). In some embodiments, the mass percentage of the negative electrode binder is ≤5% based on the total mass of the negative electrode film layer.

[0194] In some embodiments, the negative electrode film may optionally include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc. In some embodiments, the mass percentage of other additives is ≤2% based on the total mass of the negative electrode film.

[0195] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0196] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, adsorbent polymer, optional conductive agent, optional binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these. Of course, the preparation of the negative electrode sheet is not limited to the above methods; the preparation methods described earlier can also be used.

[0197] 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 of this application further includes a conductive undercoating layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode sheet of this application further includes a protective layer covering the surface of the negative electrode film layer.

[0198] battery cell Secondly, this application also proposes a battery cell. The battery cell includes a positive electrode as described in any embodiment of the first aspect of this application, which can effectively improve the cycle performance of the battery cell.

[0199] [Isolation membrane] In some implementations, the battery cell includes a separator.

[0200] In some embodiments, the separator includes a substrate.

[0201] In some embodiments, the separator includes a substrate and a coating disposed on at least one surface of the substrate.

[0202] The embodiments of this application do not have particular limitations on the material of the substrate. Any known substrate with good chemical and mechanical stability can be selected, such as at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The substrate can be a single-layer film or a multi-layer composite film. When the substrate is a multi-layer composite film, the materials of each layer can be the same or different.

[0203] In some embodiments, the coating may also include heat-resistant fillers. Further, the heat-resistant fillers may include at least one of inorganic particles and organic particles.

[0204] In some embodiments, the decomposition temperature of the heat-resistant filler can be above 200°C, thereby giving the heat-resistant filler good thermal stability and resistance to decomposition, which can further improve the heat resistance of the separator.

[0205] Inorganic particles possess high thermal stability and are not easily decomposed. Optionally, the inorganic particles include at least one of the following: inorganic particles with a dielectric constant of 5 or higher, inorganic particles with ionic conductivity but without ion storage, and inorganic particles capable of undergoing electrochemical reactions.

[0206] Optionally, inorganic particles with a dielectric constant of 5 or higher include boehmite, alumina, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hydropyrite, zirconium titanate, barium titanate, Pb(Zr,Ti)O3 (abbreviated as PZT), and Pb 1-m La m Zr 1-n Ti n O3 (abbreviated as PLZT, 0 < m < 1, 0 < n < 1), Pb(Mg3Nb) 2 / 3 The coating comprises at least one of PbTiO3 (PMN-PT) and its modified inorganic particles. Optionally, the modification of each inorganic particle can be chemical modification and / or physical modification. Chemical modification methods include coupling agent modification (e.g., using silane coupling agents, titanate coupling agents, etc.), surfactant modification, polymer grafting modification, etc. Physical modification methods can include mechanical dispersion, ultrasonic dispersion, high-energy treatment, etc. Modification treatment can reduce the agglomeration of inorganic particles, thereby enabling them to form a more stable and uniform spatial network structure with nanocellulose; in addition, by selecting coupling agents, surfactants or polymers with specific functional groups to modify inorganic particles, it is also helpful to improve the wetting characteristics of the coating to the electrolyte and improve the adhesion strength between the coating and the substrate.

[0207] Optionally, inorganic particles that are ion-conductive but do not store ions include Li3PO4 and lithium titanium phosphate (Li). x1 Ti y1 (PO4)3, Lithium aluminum titanium phosphate (Li) x2 Al y2 Ti z1 (PO4)3、(LiAlTiP) x3 Oy3 Type glass, lithium lanthanum titanate (Li) x4 La y4 TiO3, lithium germanium thiophosphate (Li) x5 Ge y5 P z2 S w Lithium nitride (Li) x6 N y6 SiS2 type glass Li x7 Si y7 S z3 and P2S5 type glass Li x8 P y8 S z4 At least one of the following: 0 < x1 < 2, 0 < y1 < 3, 0 < x2 < 2, 0 < y2 < 1, 0 < z1 < 3, 0 < x3 < 4, 0 < y3 < 13, 0 < x4 < 2, 0 < y4 < 3, 0 < x5 < 4, 0 < y5 < 1, 0 < z2 < 1, 0 < w < 5, 0 < x6 < 4, 0 < y6 < 2, 0 < x7 < 3, 0 < y7 < 2, 0 < z3 < 4, 0 < x8 < 3, 0 < y8 < 3, 0 < z4 < 7. This can further improve the ion transport characteristics of the separator.

[0208] Organic particles have good thermal stability and are not easily decomposed, which can improve the heat resistance of the separator. At the same time, when the internal temperature of the battery cell reaches the melting point of the organic particles due to overcharging, abuse, or thermal abuse, the organic particles can melt and be drawn into the micropores of the substrate by capillary action, thus playing a role in closing the pores and breaking the circuit, which helps to ensure that the battery cell has high safety performance.

[0209] In some embodiments, the organic particles include, but are not limited to, at least one of the following: polyethylene particles, polypropylene particles, polystyrene particles, melamine resin particles, phenolic resin particles, polyester particles (e.g., polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyimide particles, polyamide-imide particles, polyarylamide particles, polyphenylene sulfide particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, polyaryletherketone particles, and copolymers of butyl acrylate and ethyl methacrylate (e.g., crosslinked polymers of butyl acrylate and ethyl methacrylate).

[0210] In some embodiments, the coating also includes an adhesive. This application does not impose any particular limitation on the type of adhesive; any known material with good adhesion can be selected. As an example, the adhesive includes at least one of aqueous acrylic resins (e.g., homopolymers of acrylic acid, methacrylic acid, sodium acrylate monomers, or copolymers with other comonomers), polyvinyl alcohol, isobutylene-maleic anhydride copolymers, and polyacrylamide.

[0211] Optionally, the binder content in the coating is <30%, based on the mass of the coating.

[0212] Electrolyte In some implementations, the battery cell includes an electrolyte.

[0213] During the charging and discharging process of a single battery cell, active ions repeatedly insert and extract between the positive and negative electrode plates, while the electrolyte acts as a conductor for these active ions. This application does not impose any particular restrictions on the type of electrolyte; it can be selected according to actual needs.

[0214] Electrolytes consist of electrolyte salts and solvents. The types of electrolyte salts and solvents are not specifically limited and can be selected according to actual needs.

[0215] As an example, the electrolyte salt may include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0216] As an example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester 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), and diethyl sulfone (ESE).

[0217] 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, and additives that improve battery low-temperature power performance.

[0218] In some implementations, the positive electrode, separator, and negative electrode can be fabricated into an electrode assembly using a winding process and / or a stacking process.

[0219] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0220] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0221] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. Figure 1 The example shown is a square-structured battery cell 5.

[0222] In some embodiments, such as Figure 1 and Figure 2 As shown, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 may be one or more, and can be adjusted according to requirements.

[0223] The method for preparing the battery cell of this application is well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, a battery cell is obtained.

[0224] In some embodiments of this application, the battery cells according to this application can be assembled into a battery module. The number of battery cells contained in the battery module can be one or more, and the specific number can be adjusted according to the application and capacity of the battery module.

[0225] Figure 3 This is a schematic diagram of battery module 4 as an example. Figure 3As shown, in battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0226] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0227] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0228] Both battery module 4 and battery pack can be used as specific examples of batteries in the embodiments of this application.

[0229] Figure 4 and Figure 5 This is a schematic diagram of battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3. The upper body 2 covers the lower body 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0230] Electrical appliances Thirdly, this application provides an electrical device, which includes at least one of the battery cell, battery module, and battery pack described in this application. The battery cell, battery module, and battery pack can be used as the power source for the electrical device or as the energy storage unit of the electrical device. The electrical device can be, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. In some embodiments, the battery cell includes an injection hole for injecting electrolyte; when the battery cell is applied to the electrical device, the injection hole is located at the bottom of the battery cell in the vertical direction. Since the amount of free electrolyte in the battery cell is extremely small, or even non-existent, placing the injection hole at the bottom of the battery cell in the vertical direction can improve the reliability of the battery cell, thereby improving the reliability of the electrical device.

[0231] Electrical devices can be equipped with individual battery cells, battery modules, or battery packs depending on their usage requirements. Figure 6This is a schematic diagram of an example electrical device. The electrical device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of this electrical device, a battery pack 1 or a battery module can be used. Another example electrical device could be a mobile phone, tablet, laptop, etc. These devices typically require a slim and lightweight design, and can use individual battery cells as their power source.

[0232] Example The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0233] Example A1: Preparation of Lithium-ion Batteries - Fluorinated Polymers (1) Preparation of the positive electrode sheet: Aluminum foil is used as the positive current collector.

[0234] A positive electrode slurry is prepared by adding a liquid-absorbing polymer, a positive electrode active material, a conductive agent (carbon black), and a binder such as polyvinylidene fluoride (PVDF) to N-methylpyrrolidone (NMP). The positive electrode slurry is coated onto an aluminum foil current collector and dried at 85°C, then cold-pressed. After edge trimming, cutting, and slitting, it is dried under vacuum at 85°C for 4 hours to form a positive electrode film on the current collector, thus producing the positive electrode sheet. The mass ratio of the liquid-absorbing polymer, LiFePO4, carbon black, and PVDF in the positive electrode film is 0.5:96.8:2:0.7. The binder, polyvinylidene fluoride (PVDF), has a crystallinity of 48%, a melting temperature of 164°C, and a glass transition temperature of 39°C.

[0235] (2) Preparation of negative electrode sheet: Copper foil is used as the negative electrode current collector.

[0236] The absorbent polymer, artificial graphite (negative electrode active material), carbon black (conductive agent), styrene-butadiene rubber (SBR) (adhesive), and sodium carboxymethyl cellulose (CMC) (thickener) were mixed evenly in deionized water at a weight ratio of 2.5:94:0.5:2:1 to prepare a negative electrode slurry. The negative electrode slurry was coated onto a copper foil current collector and dried at 85°C. After cold pressing, edge trimming, cutting, and slitting, it was dried under vacuum at 120°C for 12 hours to produce the negative electrode sheet.

[0237] (3) Preparation of electrolyte: In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate EC and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 3:7 to obtain an electrolyte solvent. Subsequently, lithium salt LiPF6 was mixed with the mixed solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0238] (4) Preparation of lithium-ion batteries: Polyethylene film (PE) is used as the separator. The positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. Then, the electrode assembly is wound to obtain the electrode assembly. The electrode assembly is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a lithium-ion battery is obtained.

[0239] Examples A2 to A4 Lithium-ion batteries were prepared using a method similar to that of Example A1. The difference between Examples A2 and A4 is that the types of adsorbed polymers were adjusted.

[0240] Examples A5 to A6 Lithium-ion batteries were prepared using a method similar to that of Example A1, except that the amount of adsorbent polymer used in Examples A5 to A6 was adjusted.

[0241] Examples A7 and A8 Lithium-ion batteries were prepared using a method similar to that of Example A1. The difference between Example A1 and Example A7 and Example A8 is that the types of adsorbed polymers were adjusted.

[0242] Examples A9 to A15 Lithium-ion batteries were prepared using a method similar to that of Example A1. The difference from Example A1 is that the type and amount of adsorbed polymer were adjusted in Examples A9 to A15.

[0243] Comparative Example A1 Lithium-ion batteries were prepared using a method similar to that of Example A1. The difference from Example 1 is that neither the positive nor negative electrode in Comparative Example A1 used adsorbed polymers. (1) Preparation of the positive electrode sheet: Aluminum foil is used as the positive current collector.

[0244] A positive electrode slurry is prepared by combining a positive electrode active material, a conductive agent (carbon black), and binders such as polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP). The positive electrode slurry is coated onto an aluminum foil current collector and dried at 85°C, then cold-pressed. After edge trimming, cutting, and slitting, it is dried under vacuum at 85°C for 4 hours to form a positive electrode film on the current collector, thus producing the positive electrode sheet. The mass ratio of LiFePO4, conductive carbon black, and PVDF in the positive electrode film is 96.8:2:1.2.

[0245] (2) Preparation of negative electrode sheet: Copper foil is used as the negative electrode current collector.

[0246] Artificial graphite (negative electrode active material), carbon black (conductive agent), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethyl cellulose (CMC) (thickener) were added to deionized water at a weight ratio of 96.5:0.5:2:1 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry was coated onto a copper foil current collector and dried at 85°C. Then, it was cold-pressed, trimmed, cut into sheets, and slit. Finally, it was dried under vacuum at 120°C for 12 hours to prepare the negative electrode sheet.

[0247] Comparative Example A2 Lithium-ion batteries were prepared using a method similar to that of Example 1, except that the type of polymer was adjusted in Comparative Example A2.

[0248] Test section 1. Lithium-ion battery capacity retention test The battery's operating voltage is V1-V2. For LiFePO4, V1=2.0V and V2=3.8V.

[0249] The lithium-ion batteries prepared in the examples and comparative examples were first subjected to a fixed capacity test, and C0 was tested: after discharging to V1 at 1C, they were left to stand for 5 minutes, then charged to V2 at a constant current of 1 / 3C, and then charged to V2 at a constant voltage of 0.05C. After standing for 5 minutes, they were discharged to V1 at 1C. The capacity discharged at this time was recorded as C0.

[0250] Then, the battery is charged to V2 at an equivalent 1.2C step charge in a normal temperature environment (charged at a constant current of 1.2C for 0.5C0Ah, then at a constant current of 0.87C for 0.3C0Ah, and then at a constant current of 1 / 3C to V2). It is then charged at a constant voltage of V2 to a current of 0.05C, rested for 5 minutes, and then discharged to V1 at 0.33C. The resulting capacity is recorded as the initial capacity C0. The initial clamping force of the lithium-ion battery is set to 15000N. The above steps are repeated for the same battery, and the discharge capacity Cn of the battery after the nth cycle is recorded. The battery capacity retention rate Pn after each cycle is calculated as Pn = Cn / C0 * 100%. Using the 200 points P1, P2...P200 as the ordinate and the corresponding cycle number as the abscissa, a curve showing the battery capacity retention rate versus cycle number for the polymers in the examples and comparative examples is obtained.

[0251] In this test, the first cycle corresponds to n=1, the second cycle to n=2, and so on, up to the 200th cycle, which corresponds to n=200. For example, the battery capacity retention data corresponding to the embodiments in Tables 1 to 4 are data measured after 200 cycles under the above test conditions, i.e., the value of P200. The test process for the comparative examples and other embodiments is the same as above.

[0252] 2. Lithium-ion battery DC impedance test The battery's operating voltage is V1-V2. For LiFePO4, V1=2.0V and V2=3.8V.

[0253] The lithium-ion batteries prepared in the examples and comparative examples were first subjected to a fixed capacity test, and C0 was tested: after discharging to V1 at 1C, they were left to stand for 5 minutes, then charged to V2 at a constant current of 1 / 3C, and then charged to V2 at a constant voltage of 0.05C. After standing for 5 minutes, they were discharged to V1 at 1C. The capacity discharged at this time was recorded as C0.

[0254] The lithium-ion batteries prepared in the examples and comparative examples were charged at 25°C with an equivalent 1.2C step charge to V2 (charged at a constant current of 1.2C for 0.5C0Ah, then at a constant current of 0.87C for 0.3C0Ah, and then at a constant current of 1 / 3C to V2). They were then charged at a constant voltage of V2 until the current reached 0.05C. After resting for 5 minutes, the voltage V3 was recorded. Then, the batteries were discharged at 1 / 3C for 30 seconds, and the voltage V2 was recorded. The internal resistance DCR1 of the battery after the first cycle was obtained by calculating (V3-V2) / 1 / 3C. The above steps were repeated for the same battery, and the internal resistance DCRn (n=1, 2, 3…200) of the battery after the nth cycle was recorded. The 200 points (DCR1, DCR2, DCR3…DCR200) ​​were plotted on the ordinate, and the corresponding cycle number was plotted on the abscissa to obtain the discharge DCIR versus cycle number curves for the polymers of the examples and comparative examples.

[0255] During this test, the first cycle corresponds to n=1, the second cycle corresponds to n=2, ... the 200th cycle corresponds to n=200. For example, the battery internal resistance increase rate in the embodiments in Tables 1 to 4 is (DCRn-DCR1) / DCR1*100%, and the test process for the comparative examples and other embodiments is the same as above.

[0256] The data in Tables 1 to 4 were obtained after 200 cycles under the above test conditions.

[0257] Test Results Table 1 In Table 1, VDF represents vinylidene fluoride, HFP represents hexafluoropropylene, and TFE represents tetrafluoroethylene. 90% VDF refers to the total molar amount of VDF and HFP, where the molar percentage of VDF is 90%, and 10% FEP refers to the molar percentage of FEP being 10%. Due to variations in polymerization conditions (polymerization temperature, polymerization pressure, etc.), the properties of polymers formed even using the same type of monomers may change; for example, the glass transition temperature may vary.

[0258] As shown in Table 1, compared to Comparative Example A1, the addition of the polymer of this application to the positive and / or negative electrode sheets in the embodiments of this application improves the cycle performance of the lithium-ion battery. Compared to Comparative Example A2, when 3≤m1 / n≤35 and 1.00≤m2 / n≤1.05, the molecular chain arrangement of the embodiments of this application tends to be loose, the interaction force between molecular chains is small, adjacent molecular chains are easily opened, and chain segment movement is achieved through intermolecular rotation, forming a highly flexible molecular chain structure. This structure can physically adsorb electrolyte on the surface of active material particles, forming a liquid-locking effect and improving the wetting performance of the electrolyte on the electrode sheets. Under conditions of insufficient liquid, such as increased battery system temperature or dryness, it can elastically release electrolyte, thereby improving the deformation ability of the polymer and active material interface. During battery cycle charging and discharging, it can buffer the deformation of the adsorbed polymer and active material interface, improve the structural stability of the electrode sheets, and thus improve the cycle performance of the battery.

[0259] Example B1: Preparation of Lithium-ion Batteries - Liquid Absorbent Polymer Used as an Ether Polymer (1) Preparation of the positive electrode sheet: Aluminum foil is used as the positive current collector.

[0260] A positive electrode slurry was prepared by adding ether polymers, positive electrode active material LiFePO4, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) to N-methylpyrrolidone (NMP) in a mass ratio of 0.5:96.8:2:0.7. The positive electrode slurry was coated onto current collector aluminum foil, dried at 85°C, and then cold-pressed. After edge trimming, cutting, and slitting, the slurry was dried under vacuum at 85°C for 4 hours to form the positive electrode sheet. The binder polyvinylidene fluoride (PVDF) had a crystallinity of 48%, a melting temperature of 164°C, and a glass transition temperature of 39°C.

[0261] (2) Preparation of negative electrode sheet: Copper foil is used as the negative electrode current collector.

[0262] An ether polymer, artificial graphite (anode active material), carbon black, styrene-butadiene rubber (SBR) binder, and sodium carboxymethyl cellulose (CMC) thickener were mixed evenly in deionized water at a weight ratio of 2.5:94:0.5:2:1 to prepare a negative electrode slurry. The negative electrode slurry was coated onto a copper foil current collector and dried at 85°C. Then, it was cold-pressed, trimmed, cut into sheets, and slit. Finally, it was dried under vacuum at 120°C for 12 hours to prepare the negative electrode sheet.

[0263] (3) Preparation of electrolyte In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate EC and ethyl methyl carbonate (EMC) are mixed at a volume ratio of 3:7 to obtain an electrolyte solvent. Then, lithium salt LiPF6 is mixed with the mixed solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0264] (4) Preparation of lithium-ion batteries: Polyethylene film (PE) is used as the separator. The positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. Then, the electrode assembly is wound to obtain the electrode assembly. The electrode assembly is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a lithium-ion battery is obtained.

[0265] Comparative Example B1 Lithium-ion batteries were prepared using a method similar to that of Example B1. The difference from Example B1 is that no ether polymers were added to the positive electrode of Comparative Example B1, and no ether polymers were added to the negative electrode of Comparative Example B1.

[0266] Comparative Example B2 A lithium-ion battery was prepared using a method similar to that of Example B1. The difference from Example B1 is that the positive and negative electrode materials of Comparative Example B2 were replaced with ether polymers.

[0267] Examples B2 to B4 Lithium-ion batteries were prepared using a method similar to that of Example B1. The difference from Example B1 is that the positive and negative electrode sheets in Examples B2 to B4 were made of ether polymer instead of ether polymer.

[0268] Example B5 Lithium-ion batteries were prepared using a method similar to that of Example B1. The difference from Example B1 is that an ether polymer was added to the positive electrode of Example B5, while no ether polymer was added to the negative electrode of Example B5.

[0269] Examples B6 to B9 Lithium-ion batteries were prepared using a method similar to that of Example B1, except that the content of ether polymers in the positive electrode sheets of Examples B6 to B9 was adjusted.

[0270] Examples B10 to B12 Lithium-ion batteries were prepared using a method similar to that of Example B1, except that the content of ether polymers in the negative electrode sheets of Examples B10 to B12 was adjusted.

[0271] The performance characterization method for lithium-ion batteries is the same as the test section above. The data from the examples and comparative examples, as well as the performance test results of the lithium-ion batteries, are shown in Table 2.

[0272] Table 2 In Table 2, 100% ethylene oxide refers to the total mass of monomer 1 and monomer 2, where the mass percentage of ethylene oxide is 100%.

[0273] 80% ethylene oxide refers to the total mass of monomers 1 and 2, where the mass percentage of ethylene oxide is 80%; 20% 2-ethyl ester ethylene oxide refers to the total mass of monomers 1 and 2, where the mass percentage of 2-ethyl ester ethylene oxide is 20%.

[0274] As shown in Table 2, compared to Comparative Example B1, the addition of the ether polymer of this application to the positive and / or negative electrode sheets in the embodiments of this application improves the cycle performance of the lithium-ion battery. Compared to Comparative Example B2, when 3≤m1 / n≤35 and 1.00≤m2 / n≤1.05, the molecular chain arrangement of the embodiments of this application tends to be loose, the interaction force between molecular chains is small, adjacent molecular chains are easily opened, and chain segment movement is achieved through intermolecular rotation, forming a highly flexible molecular chain structure. This structure can physically adsorb electrolyte on the surface of active material particles, forming a liquid-locking effect and improving the wetting performance of the electrolyte on the electrode sheets. Under conditions of insufficient liquid, such as increased battery system temperature or dryness, it can elastically release electrolyte, thereby improving the deformation ability of the polymer and active material interface. During battery cycle charging and discharging, it can buffer the deformation of the adsorbed polymer and active material interface, improve the structural stability of the electrode sheets, and thus improve the cycle performance of the battery.

[0275] Example C1: Preparation of Lithium-ion Batteries - Liquid-absorbing Polymer: Ester Polymer (1) Preparation of the positive electrode sheet: Aluminum foil is used as the positive current collector.

[0276] An ester polymer, positive electrode active material LiFePO4, conductive agent carbon black, and binder such as polyvinylidene fluoride (PVDF) were added to N-methylpyrrolidone (NMP) in a mass ratio of 0.5:96.8:2:0.7 to prepare a positive electrode slurry. The positive electrode slurry was coated onto current collector aluminum foil, dried at 85°C, and then cold-pressed. After edge trimming, cutting, and slitting, it was dried under vacuum at 85°C for 4 hours to produce the positive electrode sheet. The binder, polyvinylidene fluoride (PVDF), had a crystallinity of 48%, a melting temperature of 164°C, and a glass transition temperature of 39°C.

[0277] (2) Preparation of negative electrode sheet: Copper foil is used as the negative electrode current collector.

[0278] An ester polymer, artificial graphite (the negative electrode active material), carbon black (the conductive agent), styrene-butadiene rubber (SBR) (the binder), and sodium carboxymethyl cellulose (CMC) (the thickener) are mixed evenly in deionized water at a weight ratio of 2.5:94:0.5:2:1 to prepare a negative electrode slurry. The negative electrode slurry is coated onto a copper foil current collector and dried at 85°C. Then, it is cold-pressed, trimmed, cut into sheets, and slit. Finally, it is dried under vacuum at 120°C for 12 hours to produce the negative electrode sheet.

[0279] (3) Preparation of electrolyte: In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed at a volume ratio of 3:7 to obtain an electrolyte solvent. Then, lithium salt LiPF6 is mixed with the mixed solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0280] (4) Preparation of lithium-ion batteries: Polyethylene film (PE) is used as the separator. The positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. Then, the electrode assembly is wound to obtain the electrode assembly. The electrode assembly is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a lithium-ion battery is obtained.

[0281] Comparative Example C1 Lithium-ion batteries were prepared using a method similar to that of Example C1. The difference from Example C1 is that no ester polymers were added to the positive electrode of Comparative Example C1, and no ester polymers were added to the negative electrode of Comparative Example C1.

[0282] Comparative Example C2 A lithium-ion battery was prepared using a method similar to that of Example C1. The difference from Example C1 is that the positive and negative electrode materials of Comparative Example C2 were replaced with ester polymers.

[0283] Examples C2 to C4 Lithium-ion batteries were prepared using a method similar to that of Example C1. The difference from Example C1 is that the positive and negative electrode sheets in Examples C2 to C4 were made of ester polymer instead of ester polymer.

[0284] Example C5 Lithium-ion batteries were prepared using a method similar to that of Example C1. The difference from Example C1 is that ester polymers were added to the positive electrode of Example C5, while ester polymers were not added to the negative electrode of Example C5.

[0285] Examples C6 to C9 Lithium-ion batteries were prepared using a method similar to that of Example C1, except that the content of ester polymers in the positive electrode sheets of Examples C6 to C9 was adjusted.

[0286] Examples C10 to C12 Lithium-ion batteries were prepared using a method similar to that of Example C1, except that the content of ester polymers in the negative electrode sheets of Examples C10 to C12 was adjusted.

[0287] The performance characterization method for lithium-ion batteries is the same as the test section above. The data from the examples and comparative examples, as well as the performance test results of the lithium-ion batteries, are shown in Table 3.

[0288] Table 3 In Table 3, 100% methyl methacrylate refers to methyl methacrylate with a mass percentage of 100% based on the total mass of monomers 1, 2, and 3. 85% vinyl acetate refers to vinyl acetate by mass percentage, based on the total mass of monomers 1, 2, and 3; 15% ethylene refers to ethylene by mass percentage, based on the total mass of monomers 1, 2, and 3.

[0289] As shown in Table 1, compared to Comparative Example C1, Example C of this application improves the cycle performance of the lithium-ion battery by adding the ester polymer of this application to the positive and / or negative electrode sheets. Compared to Comparative Example C2, when 3≤m1 / n≤35 and 1.00≤m2 / n≤1.05, the molecular chain arrangement of Example C of this application tends to be loose, the interaction force between molecular chains is small, adjacent molecular chains are easily opened, and chain segment movement is achieved through intermolecular rotation, forming a highly flexible molecular chain structure. This structure can physically adsorb electrolyte on the surface of active material particles, forming a liquid-locking effect and improving the wetting performance of the electrolyte on the electrode sheets. Under conditions of insufficient liquid, such as increased battery system temperature or dryness, it can elastically release electrolyte, thereby improving the deformation ability of the polymer and active material interface. During battery cycle charging and discharging, it can buffer the deformation of the adsorbed polymer and active material interface, improve the structural stability of the electrode sheets, and thus improve the cycle performance of the battery.

[0290] Example D1: Preparation of Lithium-ion Batteries - Liquid-absorbing Polymer: Aldehyde-ketone Polymer (1) Preparation of the positive electrode sheet: Aluminum foil is used as the positive current collector.

[0291] A positive electrode slurry was prepared by adding an aldehyde-ketone polymer, the positive electrode active material LiFePO4, the conductive agent carbon black, and the binder polyvinylidene fluoride (PVDF) to N-methylpyrrolidone (NMP) in a mass ratio of 0.5:96.8:2:0.7. The positive electrode slurry was coated onto a current collector aluminum foil, dried at 85°C, and then cold-pressed. After edge trimming, cutting, and slitting, it was dried under vacuum at 85°C for 4 hours to form the positive electrode sheet. The binder polyvinylidene fluoride (PVDF) had a crystallinity of 48%, a melting temperature of 164°C, and a glass transition temperature of 39°C.

[0292] (2) Preparation of negative electrode sheet: Copper foil is used as the negative electrode current collector.

[0293] An aldehyde-ketone polymer, artificial graphite (the negative electrode active material), carbon black (the conductive agent), styrene-butadiene rubber (SBR) (the binder), and sodium carboxymethyl cellulose (CMC) (the thickener) are mixed evenly in deionized water at a weight ratio of 2.5:94:0.5:2:1 to prepare a negative electrode slurry. The negative electrode slurry is coated onto a copper foil current collector and dried at 85°C. Then, it is cold-pressed, trimmed, cut into sheets, and slit. Finally, it is dried under vacuum at 120°C for 12 hours to produce the negative electrode sheet.

[0294] (3) Preparation of electrolyte In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate EC and ethyl methyl carbonate (EMC) are mixed at a volume ratio of 3:7 to obtain an electrolyte solvent. Then, lithium salt LiPF6 is mixed with the mixed solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0295] (4) Preparation of lithium-ion batteries: Polyethylene film (PE) is used as the separator. The positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. Then, the electrode assembly is wound to obtain the electrode assembly. The electrode assembly is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a lithium-ion battery is obtained.

[0296] Comparative Example D1 Lithium-ion batteries were prepared using a method similar to that of Example D1. The difference from Example D1 is that no aldehyde-ketone polymer was added to the positive electrode of Comparative Example D1, and no aldehyde-ketone polymer was added to the negative electrode of Comparative Example D1.

[0297] Comparative Example D2 A lithium-ion battery was prepared using a method similar to that of Example D1. The difference from Example D1 is that the positive and negative electrode plates of Comparative Example D2 were made of aldehyde-ketone polymer instead of aldehyde-ketone polymer.

[0298] Examples D2 to D4 Lithium-ion batteries were prepared using a method similar to that of Example D1. The difference from Example D1 is that the positive and negative electrode sheets of Examples D2 to D4 were made of aldehyde-ketone polymer instead of aldehyde-ketone polymer.

[0299] Example D5 Lithium-ion batteries were prepared using a method similar to that of Example D1. The difference from Example D1 is that an aldehyde-ketone polymer was added to the positive electrode of Example D5, while no aldehyde-ketone polymer was added to the negative electrode of Example D5.

[0300] Examples D6 to D9 Lithium-ion batteries were prepared using a method similar to that of Example D1, except that the content of aldehyde-ketone polymers in the positive electrode sheets of Examples D6 to D9 was adjusted.

[0301] Examples D10 to D12 Lithium-ion batteries were prepared using a method similar to that of Example D1, except that the content of aldehyde-ketone polymers was adjusted in the negative electrode sheets of Examples D10 to D12.

[0302] The performance characterization method for lithium-ion batteries is the same as the test section above. The data from the examples and comparative examples, as well as the performance test results of the lithium-ion batteries, are shown in Table 4.

[0303] Table 4 In Table 4, 100% formaldehyde refers to the total mass of monomer 1 and monomer 2, with a formaldehyde mass percentage of 100%.

[0304] 30% polyvinyl alcohol refers to a polyvinyl alcohol content of 30% based on the total mass of monomer 1 and monomer 2.

[0305] As shown in Table 4, compared to Comparative Example D1, the addition of the aldehyde-ketone polymer of this application to the positive and / or negative electrode sheets in Example D of this application improves the cycle performance of the lithium-ion battery. Compared to Comparative Example D2, when 3≤m1 / n≤35 and 1.00≤m2 / n≤1.05, the molecular chain arrangement of the embodiment of this application tends to be loose, the interaction force between molecular chains is small, adjacent molecular chains are easily opened, and chain segment movement is achieved through intermolecular rotation, forming a highly flexible molecular chain structure. This structure can physically adsorb electrolyte on the surface of active material particles, forming a liquid-locking effect and improving the wetting performance of the electrolyte on the electrode sheet. Under conditions of insufficient liquid, such as increased battery system temperature or dryness, it can elastically release electrolyte, thereby improving the deformation ability of the polymer and active material interface. During battery cycle charging and discharging, it can buffer the deformation of the adsorbed polymer and active material interface, improve the structural stability of the electrode sheet, and thus improve the cycle performance of the battery.

[0306] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the present application, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. A battery comprising an electrode sheet, the electrode sheet including a current collector and a film layer disposed on at least one side of the current collector, the film layer comprising an active material and an adsorbent polymer. in, The adsorbed polymer is added to a preset electrolyte at 45°C to form a polymer system. The preset electrolyte includes dimethyl carbonate, ethyl methyl carbonate, ethylene carbonate, and lithium hexafluorophosphate. The mass of the dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate is the same, and the concentration of the lithium hexafluorophosphate is 1 mol / L. The polymer system is allowed to stand at 45°C for 60 hours and then at 25°C for ≥24 hours. After being filtered through a 200-mesh filter, the remaining polymer system contains the first substance. The mass of the adsorbed polymer is n (in g), and the mass of the first substance is m1 (in g). The adsorbed polymer and the first substance satisfy the following condition: 3 ≤ m1 / n ≤ 35. The first substance is dried at 60°C for ≥24 hours to obtain the second substance. The mass of the second substance is m2, and its unit is g. The second substance and the first substance satisfy: 1.00≤m2 / n≤1.

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2. A battery, comprising an electrode sheet, the electrode sheet including a current collector and a film layer disposed on at least one side of the current collector, the film layer including an active material and an adsorbent polymer. in, The adsorbed polymer is added to a preset electrolyte at 45°C to form a polymer system. The mass ratio of the preset electrolyte to the adsorbed polymer is 15:

1. The preset electrolyte includes dimethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and lithium hexafluorophosphate. The mass of dimethyl carbonate, methyl ethyl carbonate, and ethylene carbonate is the same. The concentration of lithium hexafluorophosphate is 1 mol / L. The polymer system is allowed to stand at 45°C for 60 hours and then at 25°C for ≥24 hours. After being filtered through a 200-mesh filter, the remaining polymer system contains the first substance. The mass of the adsorbed polymer is n (in g), and the mass of the first substance is m1 (in g). The adsorbed polymer and the first substance satisfy the following condition: 3 ≤ m1 / n ≤ 35. The first substance is dried at 60°C for ≥24 hours to obtain the second substance. The mass of the second substance is m2, and its unit is g. The second substance and the first substance satisfy: 1.00≤m2 / n≤1.

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3. The battery according to claim 1 or 2, wherein, 5≤m1 / n≤35.

4. The battery according to any one of claims 1 to 3, wherein, Based on the total mass of the membrane layer, the mass content of the adsorbed polymer is ≤5%, and can be selected from 0.05% to 5%; Optionally, the electrode sheet is a positive electrode sheet; further optionally, based on the total mass of the film layer, the mass content of the adsorbed polymer is 0.05% to 2%; Optionally, the electrode sheet is a negative electrode sheet; further optionally, based on the total mass of the film layer, the mass content of the adsorbed polymer is 1% to 5%; and / or The coating weight of the adsorbent polymer is 0.5 mg / 1540.25 mm. 2 Up to 2mg / 1540.25mm 2 .

5. The battery according to any one of claims 1 to 4, wherein, The adsorbed polymer includes fluorinated polymers, where 12 ≤ m1 / n ≤ 31; Optionally, The crystallinity of the fluorinated polymer, as determined by differential scanning calorimetry, is Xc1%, where 0 < Xc1 ≤ 30, and optionally, 8 ≤ Xc1 ≤ 25. The melting temperature of the fluoropolymer is T. m1 ℃, 0 < T m1 ≤140, optionally, 81≤T m1 ≤130; Further optionally, the glass transition temperature of the fluorinated polymer is T. g1 ℃, -150≤T g1 ≤60, optionally, 5≤T g1 ≤25; Alternatively, the fluorinated polymer may include at least one of the compounds represented by formula (A1) to formula (AIII). AI (Artificial Intelligence) Formula (AII), In equations (AI) and (AII), R 11 R 12 R 13 and R 14 Each independently comprises a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and R 11 R 12 R 13 and R 14 At least one of them contains a fluorine atom; Formula (AIII) In equation (AIII), R 15 Includes single-bonded, substituted or unsubstituted C1-C3 alkyl groups; p is selected from any positive integer from 1 to 3; n is any positive integer from 1000 to 30000.

6. The battery according to any one of claims 1 to 5, wherein, The adsorbed polymer includes ether polymers, where 7 ≤ m1 / n ≤ 15; Optionally, the ether polymer is formed into a sheet-like structure; the sheet-like structure is in (T m2 The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K1, 1 < K1 < ∞, T m2 ℃ represents the melting temperature of the ether polymer; optionally, 1 < K1 ≤ 100; further optionally, 1 < K1 ≤ 10; further optionally, 1.1 ≤ K1 ≤ 2; Optionally, the glass transition temperature of the ether polymer is T. g2 ℃, -100≤T g2 ≤50; optionally, -80≤T g2 ≤30; optionally, -65≤T g2 ≤0; Further optionally, the ether polymer includes at least one of the compounds represented by formula (BI) and formula (BII). Formula (BI), In formula (BI), R 21 and R 22 Each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; R 23 Including substituted or unsubstituted C1-C5 alkylene groups; Formula (BII), In formula (BII), R 24 To R 27 Each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group, and R 24 To R 27 At least one of them contains a substituted or unsubstituted C1-C3 alkoxy or ether group; The degree of polymerization n of the ether polymer is selected from any positive integer from 1500 to 25000.

7. The battery according to any one of claims 1 to 6, wherein, The adsorbed polymer includes the ester polymer, where 15 ≤ m1 / n ≤ 25; Optionally, The ester polymer is formed into a sheet-like structure; the sheet-like structure is in (T m3 The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K2, 1 < K2 < ∞, T m3 ℃ represents the melting temperature of the ester polymer; optionally, 1 < K2 ≤ 100; further optionally, 1 < K2 ≤ 10; further optionally, 1.1 ≤ K2 ≤ 2; Optionally, the glass transition temperature of the ester polymer is T. g3 ℃, -100≤T g3 ≤50; optionally, -80≤T g3 ≤30; further optionally, -50≤T g3 ≤0; Further optionally, the ester polymer includes at least one of the compounds represented by formula (CI) to formula (CIII). Formula (CI), In formula (CI), R 31 R 32 and R 33 Each independently comprises a hydrogen atom, or a substituted or unsubstituted C1-C8 alkyl group; R 34 Including substituted or unsubstituted C1-C8 alkyl groups, or substituted or unsubstituted C1-C8 hydroxyalkyl groups; Formula (CII), In formula (CII), R 35 Includes substituted or unsubstituted C2-C6 methylene groups; optionally, R 35 Each independently includes substituted or unsubstituted C2-C4 methylene groups; Formula (CIII), In equation (CIII), R 36 R 37 and R 38 Each independently comprises a hydrogen atom, or a substituted or unsubstituted C1-C8 alkyl group; R 39 Including substituted or unsubstituted C1-C8 alkyl groups; Optionally, R 36 R 37 and R 38 Each independently comprises a hydrogen atom and a substituted or unsubstituted C1-C4 alkyl group; The degree of polymerization n of the ester polymer is selected from any positive integer from 800 to 20000.

8. The battery according to any one of claims 1 to 7, wherein, The adsorbent polymer includes aldehyde-ketone polymers. 7≤m1 / n≤12; Optionally, The aldehyde-ketone polymer is formed into a sheet-like structure; the sheet-like structure is in (T m4 The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K3, 0.8≤K3<∞, T m4 °C represents the melting temperature of the aldehyde-ketone polymer; Optionally, 0.8 ≤ K3 ≤ 100; further optionally, 0.8 ≤ K3 ≤ 10; further optionally, 0.8 ≤ K3 ≤ 1; Optionally, the glass transition temperature of the aldehyde-ketone polymer is T. g4 ℃, -100≤T g4 ≤50; optionally, -80≤T g4 ≤30; further optionally, -53≤T g4 ≤55; Further optionally, the aldehyde-ketone polymer comprises at least one of the compounds shown in formula (DI) and formula (DII). Formula (DI), In formula (DI), R 41 Including single-bonded, substituted, or unsubstituted C1-C6 methylene groups; R 42 Includes hydrogen atoms, substituted or unsubstituted C1-C6 alkyl groups; Equation (DII), In formula (DII), R 43 To R 46 Each of these components independently includes a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; r and s are each independently selected from integers from 0 to 5, and at least one of r and s is selected from any positive integer; The degree of polymerization n of the aldehyde-ketone polymer is selected from any positive integer from 500 to 15000.

9. The battery according to any one of claims 1 to 8, wherein, The molecular weight of the adsorbed polymer is 2.0 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol.

10. The battery according to any one of claims 1 to 9, wherein, The electrode sheet is a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material and an adsorbed polymer. The positive electrode active material includes at least one of olivine-type phosphate active material and layered structure positive electrode active material. and / or The electrode sheet is a negative electrode sheet, which includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material and an adsorption polymer. The negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate.

11. An electrical device comprising a battery according to any one of claims 1 to 10.

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