Isolating membrane and preparation method thereof, battery and electric device

Abstract

The invention discloses an isolating membrane and a preparation method thereof, a battery and a power utilization device, the isolating membrane comprises a base membrane and a bonding layer at least located on one side of the base membrane, the bonding layer comprises a polymer, and the loss modulus of the polymer at 10 DEG C is 5 * 10 < 6 > Pa to 9 * 10 < 8 > Pa. Therefore, the isolating membrane has better adhesion and swelling resistance.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and more specifically, to a separator membrane, a preparation method thereof, a battery, and an electrical device. Background Art

[0002] In recent years, with the development of battery technology, the market has a more urgent demand for power batteries with high-power output and fast charging and discharging, and higher requirements for battery performance have also been put forward. Although the separator membrane does not participate in the electrochemical reaction in the battery, it plays a key role in improving the structural stability of the battery and the kinetic performance of the battery. However, there are still many problems to be solved in the industrial production and application of the current separator membrane.

[0003] It should be noted that the above statements are only used to provide background technical information related to the present application, and do not necessarily constitute prior art. Summary of the Invention

[0004] In a first aspect of the present application, a separator membrane is proposed, which includes a base film and at least one adhesive layer located on one side of the base film. The adhesive layer includes a polymer, and the loss modulus of the polymer at 10 °C is 5×10 6 Pa - 9×10 8 Pa. Thus, the separator membrane has excellent adhesiveness and anti-swelling performance.

[0005] In some embodiments, the crosslinking degree of the polymer is a, a ≥ 75%. Thus, it helps to make the polymer have an appropriate loss modulus.

[0006] In some embodiments, the mass swelling degree of the polymer at 70 °C is b, 36% ≤ b ≤ 75%. Thus, it helps to improve the anti-swelling performance of the polymer.

[0007] In some embodiments, 80% ≤ a ≤ 90%, and 43% ≤ b ≤ 60%. Thus, it helps to further improve the anti-swelling performance of the polymer.

[0008] In some embodiments, the loss modulus of the polymer at 25 °C is 1×10 6 Pa - 9×10 7 Pa. Thus, the separator membrane has excellent adhesiveness at room temperature.

[0009] In some embodiments, the monomer of the polymer and derivatives of the monomer of the polymer at least include a first monomer, and the structure of the first monomer is shown in Formula 1:

[0010] Among them, R1 includes a hydrogen atom or an alkyl group with 1 to 4 carbon atoms, and R2 includes a substituted or unsubstituted alkyl group with 1 to 4 carbon atoms, a substituted or unsubstituted isobornyl group with 3 to 4 carbon atoms, -CH2(CH2) n1 -O-benzene ring, -CH2(CH2) n2 -O epoxy group, where the substituent of the substituted alkyl group with 1 to 4 carbon atoms includes a hydroxyl group or an alkyl group with 1 to 6 carbon atoms, and n1 and n2 are independently 1 to 3 respectively. Thereby, it helps to improve the adhesion performance of the polymer.

[0011] In some embodiments, the first monomer includes at least one of ethyl acrylate, n-butyl acrylate, n-propyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isooctyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, vinyl acetate, trimethylolpropane triacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, 2-phenoxyethyl acrylate. Thereby, it helps to further improve the adhesion performance of the polymer.

[0012] In some embodiments, the monomer of the polymer and the derivative of the monomer of the polymer further include a second monomer, and the structure of the second monomer is as shown in Formula 2 and / or Formula 3:

[0013] And / or

[0014] Among them, R3 includes a hydrogen atom or an alkyl group with 1 to 8 carbon atoms, and R4 includes a hydrogen atom or an alkyl group with 1 to 8 carbon atoms. Thereby, the second monomer can improve the rigidity of the polymer.

[0015] In some embodiments, the second monomer includes at least one of acrylonitrile, methacrylonitrile, ethylacrylonitrile, acrylic acid, methacrylic acid, crotonic acid, heptenoic acid. Thereby, the second monomer can further improve the rigidity of the polymer.

[0016] In some embodiments, the monomer of the polymer and the derivative of the monomer of the polymer further include a third monomer, and the structure of the third monomer is as shown in Formula 4:

[0017] Among them, R5 includes a hydrogen atom, a C1-C6 alkyl group substituted with a hydroxyl group, or a C1-C6 alkoxy group, and R6 includes a hydrogen atom or a C1-C6 alkyl group. Thus, the third monomer can improve the adhesiveness and anti-swelling performance of the polymer.

[0018] In some embodiments, the third monomer includes at least one of acrylamide, N-hydroxymethylacrylamide, and N-butoxymethylacrylamide. Thus, the third monomer can further improve the adhesiveness and anti-swelling performance of the polymer.

[0019] In some embodiments, the base film includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polysulfone, polyphenylene ether, cycloolefin copolymer, polyphenylene sulfide, and polyethylene naphthalene. Thus, it is beneficial to improve the adhesion of the polymer to the base film.

[0020] In a second aspect of the present application, the present application provides a method for preparing the aforementioned separator membrane, in which a polymer is disposed on at least one side of a base film to form an adhesive layer to obtain the separator membrane. Thus, the aforementioned separator membrane can be prepared by a simple method.

[0021] In some embodiments, providing the polymer includes: blending and stirring the constituent monomers, emulsifier, and initiator of the polymer in a molar ratio of 100:(2-10):(0.2-1), heating and reacting to obtain a polymer emulsion, and spray-drying the polymer emulsion to obtain a polymer. Thus, the yield of the polymer can be improved.

[0022] In some embodiments, the constituent monomers of the polymer include a first monomer, a second monomer, and a third monomer, wherein the mass ratio of the first monomer, the second monomer, and the third monomer is 100:(1-50):(10-40). Thus, the adhesiveness and anti-swelling performance of the polymer can be improved.

[0023] In some embodiments, the loss modulus of the polymer at 10 °C is 6×10 7 Pa - 1.4×10 8 Pa. Thus, the separator membrane has excellent adhesiveness and anti-swelling performance.

[0024] In a third aspect of the present application, the present application provides a battery, including the aforementioned separator membrane, and / or a separator membrane obtained by the aforementioned method. Thus, the battery has all the features and advantages of the aforementioned separator membrane and the method for preparing the separator membrane, which will not be elaborated herein.

[0025] In some embodiments, the battery is a lithium-ion battery. At 10°C, the lithium plating window of the battery is 0.7C - 1.5C. Thus, the battery has excellent low-temperature cycling performance.

[0026] In a fourth aspect of the present application, an electrical device is proposed, including the aforementioned battery. Thus, the electrical device has all the features and advantages of the aforementioned battery, which will not be elaborated herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0028] Figure 1 is a schematic structural diagram of a separator of an embodiment of the present application;

[0029] Figure 2 is a schematic structural diagram of a separator of another embodiment of the present application;

[0030] Figure 3 is a schematic diagram of a battery cell of an embodiment of the present application;

[0031] Figure 4 is Figure 3 an exploded view of the battery cell shown in an embodiment of the present application;

[0032] Figure 5 is a schematic diagram of a battery module of an embodiment of the present application;

[0033] Figure 6 is a schematic diagram of a battery pack of an embodiment of the present application;

[0034] Figure 7 is Figure 6 an exploded view of the battery pack shown in an embodiment of the present application;

[0035] Figure 8 is a schematic diagram of an electrical device using the battery of an embodiment of the present application as a power source.

[0036] DESCRIPTION OF THE REFERENCE NUMERALS:

[0037] 1 battery pack; 2 upper box body; 3 lower box body; 4 battery module; 5 battery cell;

[0038] 11 base film; 12 polymer; 51 housing; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application.

[0040] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; unless otherwise specified, the numerical values of the various parameters mentioned in the present application can be measured by various common measurement methods in the art (for example, they can be tested according to the methods given in the embodiments of the present application).

[0041] The terms "comprising" and "having" and any variations thereof in the description and claims of the present application are open expressions, that is, including the content specified in the present application, but not excluding other aspects.

[0042] In the description of the present application, all the numbers disclosed herein are approximate values, whether or not the words "about" or "approximately" are used. There may be a difference of less than 10% or a reasonable difference considered by those skilled in the art for each numerical value, such as a difference of 1%, 2%, 3%, 4% or 5%.

[0043] In the description of the present application, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. The "first feature" and "second feature" may include one or more of such features.

[0044] The "scope" disclosed in this application is defined in the form of a lower limit and an upper limit. A given scope is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular scope. The scope defined in this way can include or exclude the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a scope. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are understood to be contemplated. In addition, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In this application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] In the description of this application, "A and / or B" can include the case of A alone, the case of B alone, and any one of the cases of A and B, where A and B are only for example and can be any technical features connected by "and / or" in this application.

[0046] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

[0047] If there is no special instruction, all technical features and optional technical features of this application can be combined with each other to form new technical solutions.

[0048] In this application, the writing order of each step does not mean a strict execution order that constitutes any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. If there is no special instruction, all steps of this application can be carried out sequentially or randomly, and preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0049] In a battery, the separator can promote the diffusion of the electrolyte in the battery between the positive and negative electrodes, thereby facilitating the cyclic deintercalation and intercalation of metal active ions between the positive and negative electrodes. At the end of the battery cycle, the electrolyte in the battery is relatively scarce, and at this time, the promoting effect of the separator is more prominent. In order to improve the bonding strength between the separator and the electrode, the separator may include a base film and an adhesive layer located on the surface of the base film. By providing the adhesive layer, the adhesion between the separator and the electrode can be effectively improved, thereby promoting the cyclic deintercalation and intercalation of metal active ions between the positive and negative electrodes and improving the structural stability of the battery. The constituent material of the adhesive layer located on the surface of the base film is usually a polymer. Due to the large size difference between the macromolecular segments in the polymer and the small molecule solvents in the electrolyte, the small molecule solvents in the electrolyte will first penetrate and diffuse between the macromolecular segments of the polymer, weakening the interaction force between the macromolecular segments and causing the polymer to swell in volume, that is, the polymer will swell in the electrolyte. When the swelling of the polymer in the electrolyte is too large, on the one hand, it will cause problems such as increased volume expansion and electrode pulverization during the charge and discharge process of the battery, and even cause the precipitation of oligomers remaining in the polymer, resulting in the blockage of the separator pores. On the other hand, the swelling will further consume the already scarce electrolyte. Eventually, the swelling of the polymer becomes too large, the bonding effect between the electrode and the separator drops significantly, the separator cannot effectively inhibit the volume expansion generated by the negative electrode during overcharge in the cycle, especially the volume expansion generated by the silicon-based negative electrode system (the silicon content in the negative electrode active material is greater than 10% wt), causing wrinkling at the electrode interface, further causing an accelerated decline in the reversible capacity and a deterioration of the battery cycle kinetics.

[0050] The swelling of the polymer is closely related to the monomer composition of the polymer. When the crosslinking degree of the polymer is low and / or there are more flexible monomers in the polymer, the molecular segments of the polymer are more likely to move, thereby exacerbating the swelling of the polymer in the electrolyte. In addition, the movement state of the polymer molecular segments is also affected by temperature. The higher the temperature, the faster the movement of the polymer molecular chains, resulting in the inability to clearly determine the reason for excessive polymer swelling even at room temperature. Also, since the polymer hardly swells at low temperatures, and the swelling degree and crosslinking degree of the polymer are not easy to measure at low temperatures, the anti-swelling performance of the polymer cannot be effectively adjusted based on the swelling performance.

[0051] In the present application, by defining the loss modulus of the polymer at low temperature, where the loss modulus reflects the energy dissipated as heat during the deformation of the polymer under stress and can directly reflect the viscous component in the polymer, and the viscous component in the polymer is directly related to the crosslinking degree and the rigidity of the molecular segments of the polymer. Moreover, since the movement of the molecular segments of the polymer at low temperature is relatively slow, the loss modulus of the polymer at low temperature can directly reflect the crosslinking degree and the rigidity of the molecular segments of the polymer. Thus, by optimally selecting the loss modulus of the polymer at low temperature, a polymer with appropriate crosslinking degree and molecular segment rigidity can be obtained, thereby improving the adhesiveness and anti-swelling performance of the polymer, and further enhancing the adhesion effect and anti-swelling performance between the separator and the adjacent electrode sheet.

[0052] The loss modulus, also known as the viscous modulus, refers to the amount of energy dissipated due to viscous deformation (irreversible) when the material deforms, reflecting the viscosity of the material.

[0053] In the first aspect of the present application, the present application proposes a separator, referring to Figure 1 , including a base film 11 and at least one adhesive layer 12 located on one side of the base film 11. The adhesive layer includes a polymer, and the loss modulus of the polymer at 10 °C is 5×10 6 Pa - 9×10 8 Pa.

[0054] There is a strong correlation between the loss modulus of the polymer and the adhesiveness of the polymer. When the loss modulus of the polymer is within an appropriate range, the polymer has high adhesiveness and excellent anti-swelling performance.

[0055] When the loss modulus of the polymer at 10 °C is within the aforementioned range, the polymer contains an appropriate amount of rigid monomers and has an appropriate crosslinking degree, so that the mobility of the molecular segments in the polymer is poor and it is not easy to swell excessively in the electrolyte. At the same time, the polymer with the aforementioned loss modulus at 10 °C also has excellent low-temperature adhesiveness, which is beneficial to improving the adhesion effect between the separator and the adjacent electrode sheet, improving the low-temperature kinetic performance of the battery using the aforementioned separator, and further enhancing the cycle performance of the battery.

[0056] In the present application, the loss modulus of the polymer at 10 °C can be measured by methods well-known in the art. As an example, it can be measured by the following method:

[0057] (1) Preparation of the gel film: The polymer emulsion is formulated into an aqueous solution with a solid content of 50%, and left to stand at 25 °C for 24 hours on a petri dish to form a 1 mm thick gel film; (2) Place the prepared gel film on an Anton Paar device (Anton paar, MCR302); (3) Press a rotor with a diameter of 8 mm onto the gel film from above; (4) Set the pressure to 1.0 N; (5) Increase the temperature at a rate of 1 °C per minute and test at a frequency of 1 Hz. Record the value at 10 °C from -25 °C to 50 °C to obtain the loss modulus of the polymer at 10 °C.

[0058] In some embodiments, with reference to Figure 2 , on two surfaces of the base film 11 opposite to each other in its own thickness direction, the adhesive layers 12 are disposed on the two opposite surfaces of the base film 12. Thus, when the separator is disposed between the positive electrode plate and the negative electrode plate, the adhesive effect between the separator and the positive electrode plate and the negative electrode plate is relatively good.

[0059] In some embodiments, the crosslinking degree of the polymer is a, and a ≥ 75%.

[0060] As an example, the crosslinking degree of the polymer can be 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%.

[0061] When the crosslinking degree of the polymer is within the aforementioned range, the molecular chain segments in the polymer move slowly in the electrolyte, and the small molecule solvents in the electrolyte are not easily penetrated between the molecular chain segments, which helps to improve the excessive swelling of the polymer in the electrolyte, and at the same time can reduce the situation that the pores of the base film are blocked due to the excessive volume expansion of the polymer particles.

[0062] The crosslinking degree a of the polymer can be tested by methods well known in the art. As an example, the test method can adopt the following steps:

[0063] (1) Weigh 6 g of polymer particles by stacking 2 layers of weighing paper (the weighing balance uses a Uni Bloc SHIMADZU AUY220 one-millionth balance);

[0064] (2) Place the weighed polymer particles in a vacuum oven at 105 °C (the vacuum oven uses a Lijia LDZF-6090 with dimensions 450*450*450 RT~250 °C) and dry for 6 h;

[0065] (3) Stack 2 layers of medium-speed filter paper (the medium-speed filter paper used is the Nova quantitative medium-speed filter paper) and number them. At the same time, place them in a 105°C vacuum oven (the vacuum oven used is the Lijia LDZF-6090 with dimensions 450*450*450, RT~250°C) and dry for 6 hours;

[0066] (4) After taking out the polymer particles and the weighing paper from the vacuum oven, immediately seal them with a sealed bag to prevent water absorption;

[0067] (5) After taking out the medium-speed filter paper from the vacuum oven, immediately put it into a self-sealing bag and weigh it. Record the total weight m1 of the medium-speed filter paper and the self-sealing bag, and retain the weight value to 4 decimal places;

[0068] (6) Pour the polymer particles obtained in step (4) into a small crusher (the crusher used is Baixin LG-01, with a power of 350W, a fineness of 30-300 mesh, a rotation speed of 2500r / m, and a crushing capacity of 500g / m). Cover the lid and tighten it;

[0069] (7) Plug in the power supply, turn on the power switch, and use a stopwatch to count for 30S and then turn off the power switch;

[0070] (8) Let the crusher stand for 5 minutes. After the powder in the crusher has settled, unscrew the lid of the crusher, and the sample will be in a uniform powder state;

[0071] (9) Use a brush to transfer the crushed sample to a self-sealing bag and seal it immediately;

[0072] (10) After taring the centrifuge tube and the centrifuge tube lid on the balance, take out the sample bag from the drying dish, pour about 2±0.2g of the sample into the centrifuge tube, immediately cover the centrifuge tube lid, and weigh the actual weight m2 of the sample;

[0073] (11) Add 50 ml of dimethyl carbonate (DMC) according to the scale on the 50 ml centrifuge tube;

[0074] (12) Transfer the centrifuge tube to a 60°C oven (the oven used is Boxun GZX-9146MBE, with a capacity of 129L, RT+5°C~300°C) and keep it warm for 12 hours;

[0075] (13) After taking out the centrifuge tube from the oven, pour the sample onto the medium-speed filter paper, filter the solution, and retain the residue on the filter;

[0076] (14) Rinse the centrifuge tube with a large amount of DMC solution to prevent any sample from remaining in the centrifuge tube;

[0077] (15) Dry the residue on the filter in a 105°C oven for 2 hours;

[0078] (16) After the sample baking is completed, put the sample into the corresponding self-sealing bag and weigh it;

[0079] (17) Zero the scale, weigh the total mass of the filter residue, medium-speed filter paper and self-sealing bag, and record the mass m3.

[0080] Calculate the crosslinking degree a of the polymer particles.

[0081] In some embodiments, the mass swelling degree of the polymer at 70 °C is b, and 36% ≤ b ≤ 75%.

[0082] In some embodiments, when 36% ≤ b ≤ 75%, a / b can be greater than or equal to 1.

[0083] When a / b is within the foregoing range, the polymer particles have a suitable loss modulus, which can improve the adhesion of the polymer. At the same time, the polymer particles will not swell too much in the electrolyte and consume too much electrolyte, and at the same time reduce the situation that the polymer particles expand too much in volume and block the pores of the base film.

[0084] In some embodiments, 80% ≤ a ≤ 90%, and 43% ≤ b ≤ 60%.

[0085] In some embodiments, when 80% ≤ a ≤ 90% and 43% ≤ b ≤ 60%, a / b can be 1 - 2.1, which helps to further improve the anti-swelling performance of the polymer.

[0086] As an example, a / b can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 or 2.1.

[0087] The mass swelling degree b of the polymer at 70 °C can be tested by methods well known in the art. As an example, the testing method can adopt the following steps:

[0088] (1) Dissolution: Take 10 g of polymer particle powder and mix it with 90 g of N-methylpyrrolidone (NMP), and stir and dissolve at 40 °C for 7 h;

[0089] (2) Preparation of the gelatinous film: Place the stirred polymer particle powder gelatinous liquid in a 250 mL beaker, and bake it at 70 °C for 8 days to obtain a dry gelatinous film;

[0090] (3) Swelling rate test: Take about 3 g of the dry gelatinous film with a thickness of 2 mm, weigh its exact mass and record it as M1, soak it in the electrolyte (the mass ratio of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in the electrolyte solvent is 3:5:2, and prepare a 1 mol / L electrolyte by mixing the electrolyte solvent with lithium hexafluorophosphate (LiPF6)), place it in an oven at 70 °C and bake. After taking out the sample piece and standing for 1 h, wipe it clean and weigh its mass M2. According to Calculate the mass swelling degree b of the polymer particles.

[0091] In some embodiments, the loss modulus of the polymer at 25 °C is 1×10 6 Pa - 9×10 7 Pa.

[0092] The loss modulus of the polymer is inversely proportional to the temperature of the polymer. When the loss modulus of the polymer at 25 °C is within the aforementioned range, the polymer has excellent adhesion and anti - swelling properties at 25 °C. At the same time, the loss modulus of the polymer at 10 °C is within the aforementioned range.

[0093] By using suitable polymer monomers, the polymer can have excellent cross - linking degree and molecular chain segment rigidity, and thus the polymer has a suitable loss modulus.

[0094] In the present application, the loss modulus of the polymer at 25 °C can be tested by methods well - known in the art. As an example, it can be obtained by the following method:

[0095] (1) Prepare a glue film: Prepare an aqueous solution with a solid content of 50% from the polymer emulsion, and let it stand at 25 °C for 24 hours on a petri dish to form a 1 - mm - thick glue film; (2) Place the prepared glue film on an Anton Paar device (Anton paar, MCR302); (3) Press a rotor with a diameter of 8 mm onto the glue film from above; (4) Set the pressure to 1.0 N; (5) Heat up at a rate of 1 °C per minute and test at a frequency of 1 Hz. From - 25 °C to 50 °C, record the value at 25 °C, and the loss modulus of the polymer at 25 °C can be obtained.

[0096] In some embodiments, the polymer monomer containing a hydroxyl group can be used as an internal cross - linker to improve the cross - linking degree of the polymer.

[0097] In some embodiments, the monomer of the polymer and the derivative of the monomer of the polymer at least include a first monomer, and the structure of the first monomer is shown in Formula 1:

[0098] Among them, R1 includes a hydrogen atom or an alkyl group of C1 - C4, and R2 includes a substituted or unsubstituted alkyl group of C1 - C4, a substituted or unsubstituted isobornyl group of C3 - C4, - CH2(CH2) n1 - O - benzene ring, - CH2(CH2) n2 - O epoxy group, where the substituent of the substituted alkyl group of C1 - C4 includes a hydroxyl group or an alkyl group of C1 - C6, and n1 and n2 are independently 1 - 3.

[0099] In some embodiments, when R2 is - CH2(CH2) n1-O benzene ring or -CH2(CH2) n2 When it is -O epoxy group, the R2 group is connected to the oxygen atom through a methylene group.

[0100] During the manufacturing process of the battery, the separator needs to be tightly bonded to the electrode sheet through a hot pressing process or a cold pressing process so that the hardness of the battery cell is sufficient to quickly and efficiently enter the shell. The first monomer includes an unsaturated ester group, which is beneficial to the polymerization of the monomer and can form the backbone of the polymer molecular chain segment, making the polymer have better molecular chain segment rigidity and adhesiveness, helping to improve the anti-swelling performance of the polymer. The appropriate anti-swelling performance helps to improve the contribution of the separator to the kinetics in the liquid-starved state during the later stage of battery cycling.

[0101] In some embodiments, the first monomer includes at least one of ethyl acrylate, n-butyl acrylate, n-propyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isooctyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, vinyl acetate, trimethylolpropane triacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, 2-phenoxyethyl acrylate.

[0102] Using any one or more of the above first monomers can adjust the adhesive performance and anti-swelling performance of the polymer.

[0103] In some embodiments, the monomer of the polymer and the derivative of the monomer of the polymer further include a second monomer, and the structure of the second monomer is as shown in Formula 2 and / or Formula 3:

[0104] and / or,

[0105] Among them, R3 includes a hydrogen atom or an alkyl group with 1 to 8 carbon atoms, and R4 includes a hydrogen atom or an alkyl group with 1 to 8 carbon atoms.

[0106] The second monomer contains carboxyl and / or cyano functional groups. On the one hand, the carboxyl and cyano groups can both improve the adhesive performance between the polymer and the electrode sheet. On the other hand, they can increase the cross-linking active sites of the polymer, that is, enter the macromolecular structure chain as an internal cross-linking agent during monomer polymerization, thereby increasing the cross-linking degree of the polymer and improving the rigidity and anti-swelling performance of the polymer. In addition, both the carboxyl and cyano functional groups are polar functional groups, which are beneficial to enhancing the solvation and desolvation ability of lithium ions, and further enhancing the ion conduction ability of the separator and improving the battery kinetic performance.

[0107] In some embodiments, the second monomer includes at least one of acrylonitrile, methacrylonitrile, ethylacrylonitrile, acrylic acid, methacrylic acid, crotonic acid, and heptenoic acid.

[0108] By using any one or more of the above-mentioned second monomers, the adhesion performance of the polymer can be adjusted. Among them, the monomer containing a cyano group can also improve the ionic conductivity of the polymer and improve the kinetic performance of the polymer.

[0109] In some embodiments, the monomer of the polymer and the derivative of the monomer of the polymer further include a third monomer, and the structure of the third monomer is shown in Formula 4:

[0110] Wherein, R5 includes a hydrogen atom, a C1-C6 alkyl group substituted with a hydroxyl group or a C1-C6 alkoxy group, and R6 includes a hydrogen atom or a C1-C6 alkyl group.

[0111] The structure of the third monomer includes an unsaturated amide group, which is beneficial to the polymerization of the monomer. This type of monomer plays a role in adjusting the molecular weight, and at the same time has good adhesion and anti-swelling properties. The amide group can also form a bond with the functional group on the base film to improve the adhesion performance of the polymer to the base film.

[0112] In some embodiments, the third monomer includes at least one of acrylamide, N-hydroxymethylacrylamide, and N-butoxymethylacrylamide.

[0113] By using any one or more of the above-mentioned third monomers, the molecular weight can be adjusted to adjust the molecular weight of the polymer. The molecular weight of the polymer within a certain range helps to improve the adhesion.

[0114] In some embodiments, the base film includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyaryl ether ketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cycloolefin copolymer, polyphenylene sulfide, and polyethylene naphthalene. Thereby, it is beneficial to improve the adhesion of the polymer to the base film.

[0115] By using the base film of the above-mentioned materials, the adhesion of the polymer to the base film can be effectively improved, and the structural stability of the separator can be improved.

[0116] The base film is a porous membrane material with good chemical stability and mechanical stability. In some embodiments, the base film can be a single-layer membrane material or a multi-layer composite membrane material. When the base film is a multi-layer composite membrane material, the materials of each layer can be the same or different.

[0117] In some embodiments, the base film has a porosity of 10%-95%, such as 15%-90%, 20%-85%, 25%-80%, 30%-75%, 35%-70%, 40%-65%, 45%-60%, 50%-55%. Thus, while improving the ion conductivity of the separator, the probability of direct contact between the positive electrode and the negative electrode can be reduced.

[0118] In some embodiments, the base film has a pore diameter of 0.1 μm - 50 μm, such as 0.5 μm - 50 μm, 1 μm - 45 μm, 5 μm - 40 μm, 10 μm - 35 μm, 15 μm - 30 μm, 20 μm - 25 μm. Selecting a base film with the above pore structure enables the separator to have good ion conductivity, reduces the probability of direct contact between the positive electrode and the negative electrode, and improves the kinetics of the battery.

[0119] In some embodiments, the loss modulus of the polymer at 10 °C is 6×10 7 Pa - 1.4×10 8 Pa. Thus, the separator has excellent adhesion and anti-swelling properties.

[0120] In the second aspect of the present application, the present application provides a method for preparing the aforementioned separator, including:

[0121] S1: Provide a base film

[0122] In some embodiments, the relevant parameters of the base film can refer to some or all of the technical features in the aforementioned embodiments. For the parts not described in this embodiment, reference can also be made to the aforementioned embodiments and the relevant drawings, which will not be elaborated here.

[0123] S2: Dispose the polymer on at least one side of the base film

[0124] In some embodiments, by disposing the polymer on one side of the base film to form an adhesive layer, the aforementioned separator can be prepared by a simple method.

[0125] In some embodiments, S2 can be carried out by the following steps: (S2-1) Provide an adhesive layer slurry, and the adhesive layer slurry includes a polymer; (S2-2) Coat the adhesive layer slurry on at least one side of the base film and dry it to obtain the separator.

[0126] In some embodiments, in step (S2-1), the solvent in the adhesive layer slurry can be water, such as deionized water.

[0127] In some embodiments, in step (2-1), the adhesive layer slurry can also include other organic compounds. For example, it can also include polymers for improving heat resistance, dispersants, wetting agents, etc.

[0128] In some embodiments, in step (2-2), the coating can be carried out using a coater.

[0129] In some embodiments, in step (2-2), the coating can adopt at least one of transfer coating, spin spraying, and dip coating.

[0130] In some embodiments, the coater includes a gravure roll; the gravure roll is used to transfer the adhesive layer slurry onto the base film.

[0131] In some embodiments, the polymer in the adhesive layer slurry can be provided by the following method: the constituent monomers, emulsifier, and initiator of the polymer are blended and stirred in a molar ratio of 100:(2-10):(0.2-1), and then heated and reacted to obtain a polymer emulsion. The polymer emulsion is spray-dried to obtain the polymer. Thus, the polymer emulsion can be obtained by emulsion polymerization, and the yield of the polymer can be increased.

[0132] Emulsion polymerization. Emulsion polymerization is a process in which monomers are dispersed in water to form an emulsion with the aid of an emulsifier and mechanical stirring, and then an initiator is added to initiate the polymerization of the monomers.

[0133] An emulsifier is a substance that can transform immiscible oil and water into an emulsion that is difficult to separate. Emulsifiers are usually surfactants with both hydrophilic polar groups and hydrophobic (lipophilic) non-polar groups.

[0134] An initiator is a substance that can initiate the polymerization reaction of monomers. For example, a free radical initiator refers to a class of compounds that are easily decomposed by heat into free radicals (i.e., primary free radicals), and can be used to initiate the free radical polymerization and copolymerization reactions of vinyl monomers and diene monomers.

[0135] In some embodiments, the emulsifier can include at least one of sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium dodecyl benzene sulfate, sodium laurate, sodium stearate, and sodium palmitate.

[0136] In some embodiments, the initiator can meet at least one of the following conditions: the persulfate initiator includes at least one of potassium persulfate and ammonium persulfate; the acyl peroxide initiator includes at least one of benzoyl peroxide and di-n-octanoyl peroxide; the azo initiator includes at least one of azobisisobutyronitrile and dimethyl azobisisobutyrate.

[0137] In some embodiments, the constituent monomers of the polymer may include the aforementioned first monomer, second monomer, and third monomer. Among them, the mass ratio of the first monomer, second monomer, and third monomer may be 100:(1 - 50):(10 - 40). Thus, while the polymer combines the respective advantages of the first monomer, second monomer, and third monomer, it also has relatively excellent adhesiveness and anti-swelling properties.

[0138] In some embodiments, the adhesive layer is provided only on one surface of the base film. In other embodiments, the adhesive layer is provided on both surfaces of the base film simultaneously.

[0139] In the third aspect of the present application, the present application provides a battery, including the aforementioned separator, and / or the separator obtained by the aforementioned method. Thus, the battery has all the features and advantages of the aforementioned separator and the method for preparing the separator, which will not be elaborated here.

[0140] Generally, a battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charge and discharge process of the battery, active ions intercalate and deintercalate back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in conducting active ions between the positive electrode plate and the negative electrode plate. The separator is disposed between the positive electrode plate and the negative electrode plate, mainly to prevent the positive and negative electrodes of the battery from short-circuiting, and at the same time allows ions to pass through.

[0141] In some embodiments, the battery is a lithium-ion battery. At 10°C, the lithium deposition window of the battery is 0.7C - 1.5C.

[0142] At low temperatures, the mobility of lithium ions in lithium batteries decreases significantly, resulting in a sharp increase in battery internal resistance, serious loss of discharge capacity, a reduction in the lithium deposition window during battery charging, and lithium deposition may occur with a slightly larger charging current. The deposited metallic lithium dendrites may pierce the separator, causing thermal runaway.

[0143] The lithium deposition window refers to the maximum current that the battery can achieve without lithium deposition (no white spots on the surface of the negative electrode plate), also known as the maximum non-lithium-depositing rate of the battery.

[0144] When the aforementioned separator is used in the battery, since the separator still has good adhesiveness at low temperatures, it is beneficial to improve the adhesion effect between the separator and the adjacent electrode plates, improve the low-temperature kinetic performance of the battery using the aforementioned separator, broaden the lithium deposition window of the battery, which is consistent with the lithium deposition window of the battery at room temperature, and thus improve the cycle performance of the battery.

[0145] The lithium plating window of the battery can be tested by methods well-known in the art. As an example, the testing method can include the following steps: The sample preparation steps include: (1) Take an unrolled bare battery cell, place three or more copper wires at the middle position corresponding to the separator film on the second outermost negative electrode sheet, and fix them with tape at the upper edge of the anode sheet; (2) Apply a small piece of separator film on the copper wires to ensure that the copper wires are covered and do not touch each other, and fix the separator film with tape; if it is a four-electrode battery, one or more copper wires (SE) need to be uncovered by the separator film and marked to distinguish them from the other copper wires; (3) Roll up the bare battery cell again, being careful not to displace the copper wires, and pay attention to keeping the dimensions of the negative electrode sheet in the length and width directions larger than those of the positive electrode sheet; (4) Continue with the rolling process, first cold press (25 °C, 3 MPa, 10 s), then hot press (55 °C, 5 MPa, 15 s) to obtain the battery cell to be tested.

[0146] The testing steps include capacity testing and continuous charging window testing. Taking the positive electrode active material being nickel-cobalt-manganese ternary material as an example, among them, the capacity testing includes: (1) Let the battery cell to be tested stand for 30 min; (2) Charge it directly at a rate of 0.33C to 2.8V; (3) Stand for 5 min; (4) Charge it at a constant current of 0.33C to 4.35V, and then charge it at a constant voltage until the current ≤ 0.05C; (5) Stand for 5 min; (6) Discharge it directly at a rate of 0.33C to 2.8V, and record the battery capacity C n ; (7) Stand for 5 min. Among them, during the entire capacity testing process, the testing temperature is 25 °C, and the testing sampling interval is 10S / mA / mV.

[0147] The continuous charging window testing includes: (1) Let the battery cell to be tested stand for 30 min; (2) Charge it directly at a rate of 0.33C to 2.8V; (3) Stop the current supply and place it at -10 °C; (4) Stand for 2 h; (5) Charge it to 4.35V at different rates, read the capacity C1 before the jump (the jump point is when the negative electrode potential reaches -10 mV or the voltage reaches 4.35V), and conduct the test for the next rate. The testing rates include in sequence: 0.08C, 0.1C, 0.2C, 0.4C, 0.6C, 0.8C, 1C, 1.5C, 2C, 3C. C1 / C n is the SOC at the time of the jump. Taking the SOC as the X-axis and the rate as the Y-axis, obtain the rate-SOC curve at this temperature. Through the rate-SOC curve, the charging rate corresponding to 50% SOC can be obtained, and the C1 corresponding to 50% SOC is the rate at which no lithium plating occurs at this temperature.

[0148] The test temperature for steps (1) and (2) in the continuous charging window test is 25°C, and the test sampling interval is 60S / mA / mV; the test temperature for steps (3) and (4) is -10°C, and the test sampling interval is 60S / mA / mV; the test temperature for step (5) is -10°C, and the test sampling interval is 10S / mA / mV.

[0149] [Positive electrode plate]

[0150] As an example, refer to Figure 2 , the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material layer 22 is disposed on any one or both of the two opposite surfaces of the positive electrode current collector 21.

[0151] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0152] In some embodiments, when the battery is a lithium-ion battery, the positive electrode active material can be a positive electrode active material known in the art for lithium-ion batteries.

[0153] As an example, the positive electrode active material can include at least one of the following materials: lithium phosphate with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides can include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn0.25 O2 (which can also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds. Examples of olivine-structured lithium-containing phosphates can include but are not limited to lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), composites of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and composites of lithium manganese iron phosphate and carbon. The modified compounds of the above materials can be doping modification and / or surface coating modification of the materials.

[0154] During the charge and discharge process of the battery, the deintercalation and consumption of Li will occur, and the molar content of Li is different when the battery is discharged to different states. In the listing of the positive electrode active materials in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. When the positive electrode active material is applied to the battery system, after charge and discharge cycles, the molar content of Li will change.

[0155] In some embodiments, when the battery is a sodium-ion battery, the positive electrode active material can adopt the positive electrode active materials known in the art for sodium-ion batteries.

[0156] As an example, the positive electrode active material can include at least one of the following materials: sodium transition metal oxides, polyanion compounds, and Prussian blue-type sodium compounds and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. The modified compounds of the above materials can be doping modification and / or surface coating modification of the materials.

[0157] In some embodiments, the transition metal in the sodium transition metal oxide can be at least one of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, Cu. The chemical formula of the sodium transition metal oxide can satisfy Na x MO2, where M includes at least one of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, Cu, and 0 < x ≤ 1.

[0158] In some embodiments, the polyanionic compound can be a compound having sodium ions, transition metal ions, and tetrahedral (YO4) n- anion units. Among them, the transition metal can include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, Ce; Y can include at least one of P, S, Si; n represents the n- valence state of (YO4).

[0159] In some embodiments, the polyanionic compound can also be a compound having sodium ions, transition metal ions, tetrahedral (YO4) n- anion units and halogen anions. The transition metal can include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, Ce; Y can include at least one of P, S, Si, n represents the n- valence state of (YO4), and the halogen can include at least one of F, Cl, Br.

[0160] In some embodiments, the polyanionic compound can also be a compound having sodium ions, tetrahedral (YO4) n- anion units, polyhedral units (ZO y ) m+ and optionally halogen anions. M can include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y can include at least one of P, S, Si, n represents the n- valence state of (YO4), Z represents a transition metal, m represents the y valence state of (ZO m+ ) and the halogen can include at least one of F, Cl, Br.

[0161] As an example, the polyanionic compound can satisfy at least one of the chemical formulas NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7), NaM’PO4F (M’ includes at least one of V, Fe, Mn, and Ni), and Na3(VO y )2(PO4)2F 3-2y (0 ≤ y ≤ 1).

[0162] In some embodiments, the Prussian blue compound can be a compound having sodium ions, transition metal ions, and cyanide ions (CN - ). The transition metal can include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce.

[0163] As an example, Prussian blue compounds can satisfy the chemical formula Na a Me b Me’ c (CN)6, where Me and Me’ each independently include at least one of Ni, Cu, Fe, Mn, Co, and Zn, 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0164] During the charge and discharge process of the battery, the insertion and extraction and consumption of Na will occur, and the molar content of Na is different when the battery is discharged to different states. In the listing of the positive electrode active material in this application, the molar content of Na is the initial state of the material, that is, the state before feeding. When the positive electrode active material is applied to the battery system, after charge and discharge cycles, the molar content of Na will change.

[0165] In the listing of the positive electrode active material in this application, the molar content of O is only the theoretical state value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0166] In some embodiments, the positive electrode active material layer may further optionally include a binder.

[0167] As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0168] In some embodiments, the positive electrode active material layer may further optionally include a conductive agent.

[0169] As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0170] In some embodiments, the positive electrode plate can be prepared by the following method: dispersing the above-mentioned components for preparing the positive electrode plate, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate can be obtained.

[0171] [Negative electrode plate]

[0172] The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

[0173] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0174] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, copper foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0175] In some embodiments, the negative electrode active material can be a negative electrode active material for a battery well-known in the art. As an example, the negative electrode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials include at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0176] In some embodiments, the negative electrode active material layer may optionally further include a conductive agent. The conductive agent includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0177] In some embodiments, the negative electrode active material layer may optionally further include other additives, such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0178] In some embodiments, the negative electrode plate can be prepared by the following method: dispersing the above components for preparing the negative electrode plate, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode plate can be obtained.

[0179] [Electrolyte]

[0180] The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. The present application has no specific limitation on the type of the electrolyte, and it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or all-solid-state.

[0181] In some embodiments, the electrolyte is an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0182] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0183] In some embodiments, the solvent includes at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0184] In some embodiments, the electrolytic solution may optionally further include an additive. For example, the additive may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may also include additives that can improve certain battery performances, such as additives for improving the overcharge performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, and the like.

[0185] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly through a winding process or a stacking process.

[0186] In some embodiments, the battery may include an outer package. The outer package can be used to encapsulate the above-mentioned electrode assembly and electrolyte.

[0187] In some embodiments, the outer package of the battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic. As plastics, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed, etc.

[0188] This application has no particular limitation on the shape of the battery, and it can be cylindrical, square, or any other arbitrary shape. For example, Figure 3 is a battery cell 5 with a square structure as an example.

[0189] In some embodiments, with reference to Figure 4, the outer packaging may include a housing 51 and a top cover assembly 53. Among them, the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the separator can be formed into an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual requirements.

[0190] In some embodiments, the battery can be assembled into a battery module. The number of batteries included in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0191] Figure 5 is a battery module 4 as an example. Refer to Figure 5 , in the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other way. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0192] Optionally, the battery module 4 may further include a housing having a receiving space, and a plurality of battery cells 5 are received in the receiving space.

[0193] In some embodiments, the above battery module can be further assembled into a battery pack. The number of battery modules included in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0194] Figure 6 and Figure 7 is a battery pack 1 as an example. Refer to Figure 6 and Figure 7 , in the battery pack 1, it may include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can be covered on the lower box body 3 and form a closed space for receiving the battery module 4. The plurality of battery modules 4 can be arranged in the battery box in any way.

[0195] In the fourth aspect of the present application, the present application proposes an electrical device including the aforementioned battery. Thus, the electrical device has all the features and advantages of the aforementioned battery, which will not be elaborated here.

[0196] The power-consuming device includes at least one of the battery, battery module, or battery pack provided in the present application. The battery, battery module, or battery pack can be used as the power source of the power-consuming device or as the energy storage unit of the power-consuming device. The power-consuming device can include mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (see Figure 8 , such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but not limited thereto.

[0197] As the power-consuming device, the battery, battery module, or battery pack can be selected according to its usage requirements.

[0198] The solution of the present application will be described below through specific embodiments. It should be noted that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For those reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0199] Example 1

[0200] 1. Preparation of polymer

[0201] (1) Preparation of polymer emulsion

[0202] Weigh the first monomer methyl acrylate, the second monomer methacrylic acid, and the third monomer acrylamide according to the mass ratio of 80:5:15 of the first monomer, the second monomer, and the third monomer, and mix the monomers evenly. Add 1000 g of the mixed monomers, 30 g of sodium dodecyl sulfate emulsifier, 10 g of ammonium persulfate initiator, and 1200 g of deionized water to a 5 L four-necked flask equipped with a mechanical stirrer, a thermometer, and a condenser, and stir at high speed for emulsification for 30 min. Under nitrogen protection, heat up to 75 °C and react for 4 h, then cool down to below 40 °C, adjust the pH to neutral, filter and discharge to obtain the polymer emulsion.

[0203] (2) The polymer emulsion is made into the adhesive for the separator by spray drying process. The conditions of the spray drying process are an inlet air temperature of 110 °C, an outlet air temperature of 50 °C, and a wind pressure of 0.5 kPa.

[0204] 2. Preparation of battery:

[0205] (1) Preparation of separator

[0206] A commercially available PE microporous film with a thickness of 7 μm and an average pore diameter of 80 nm (from Zhuogao Electronic Technology Co., Ltd.) was used as the base film. The polymer prepared above was stirred and mixed evenly in deionized water to obtain a slurry (solid content: 20%). The slurry was sprayed on both surfaces of the base film, and the solvent was removed by drying. The coating density of the polymer on the base film was 1.5 g / m 2 , and a separator film was obtained.

[0207] (2) Preparation of the positive electrode sheet

[0208] Polyvinylidene fluoride (PVDF), NCM811, conductive agent carbon black, and N-methylpyrrolidone (NMP) were mixed in a mass ratio of 1.2:58.38:0.42:40 and stirred thoroughly to prepare a positive electrode slurry. The positive electrode slurry was uniformly coated on the positive electrode current collector aluminum foil at a loading of 200 g / m 2 . After drying, cold pressing, and slitting, a positive electrode sheet was obtained.

[0209] (3) Preparation of the negative electrode sheet

[0210] Artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) were added to deionized water in a mass ratio of 96.2:1.0:1.6:1.2 and stirred thoroughly to prepare a negative electrode slurry (solid content: 63%). The negative electrode slurry was coated on the negative electrode current collector copper foil at a loading of 98 g / m 2 . After drying, cold pressing, and slitting, a negative electrode sheet was obtained.

[0211] (4) Preparation of the electrolyte

[0212] At 25 °C, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain a mixed solvent, and then LiPF6 was dissolved in the above mixed solvent to obtain an electrolyte, where the concentration of LiPF6 was 1 mol / L.

[0213] (5) Assembly of the battery

[0214] The above positive electrode sheet, separator film, and negative electrode sheet were stacked, wound, and cold-pressed in sequence (during which the separator film was bonded to the electrode sheet) to obtain a bare battery cell; the bare battery cell was placed in an outer package, the above-prepared electrolyte was added, and after processes such as encapsulation, standing, formation, and aging, a battery was obtained.

[0215] Examples 2-9, Comparative Examples 1-2 are different from Example 1 as shown in Table 1.

[0216] Table 1

[0217]

[0218] The polymers in the above-mentioned examples and comparative examples were tested as follows, and the test results are shown in Table 2:

[0219] Loss modulus: The polymer emulsion was formulated into an aqueous solution with a solid content of 50%, and left to stand at 25 °C for 24 hours on a petri dish to form a 1 mm thick film; (2) The prepared film was placed on an Anton Paar device (Anton paar, MCR302); (3) A rotor with a diameter of 8 mm was pressed onto the film from above; (4) The pressure was set to 1.0 N; (5) The temperature was increased at a rate of 1 °C per minute, and tested at a frequency of 1 Hz. From -25 °C to 50 °C, the values at 10 °C and 25 °C were recorded to obtain the loss modulus of the polymer at 10 °C and 25 °C.

[0220] Crosslinking degree: (1) Weigh 6 g of polymer particles with two layers of weighing paper (use Uni Bloc SHIMADZU AUY220 one-millionth balance for weighing); (2) Place the weighed polymer particles in a 105 °C vacuum oven (use Lijia LDZF-6090 with dimensions 450*450*450, RT~250 °C) and dry for 6 h; (3) Stack two layers of medium-speed filter paper (use Xinxing quantitative medium-speed filter paper) and number them, and at the same time place them in a 105 °C vacuum oven (use Lijia LDZF-6090 with dimensions 450*450*450, RT~250 °C) and dry for 6 h; (4) After taking out the polymer particles and weighing paper from the vacuum oven, immediately seal them with a sealed bag to prevent water absorption; (5) After taking out the medium-speed filter paper from the vacuum oven, immediately put it into a self-sealing bag and weigh it, record the total weight m1 of the medium-speed filter paper and the self-sealing bag, and retain the weight value to 4 decimal places; (6) Pour the polymer particles obtained in step (4) into a small crusher (use Baixin LG-01, power 350 W, fineness 30~300 mesh, rotation speed 2500 r / m, crushing capacity 500 g / m), cover the lid and tighten it; (7) Plug in the power supply, turn on the power switch, and turn off the power switch after counting 30 S with a stopwatch; (8) Let the crusher stand for 5 min. After the powder in the crusher has settled, unscrew the lid of the crusher, and the sample is in a uniform powder state; (9) Use a brush to transfer the crushed sample to a self-sealing bag and seal it immediately; (10) After taring the centrifuge tube and the centrifuge tube lid on the balance, take out the sample bag from the drying dish, pour about 2±0.2 g of the sample into the centrifuge tube, immediately cover the centrifuge tube lid, and weigh the actual weight m2 of the sample; (11) Add 50 ml of dimethyl carbonate (DMC) according to the scale on the 50 ml centrifuge tube; (12) Transfer the centrifuge tube to a 60 °C oven (use Boxun GZX-9146MBE, capacity 129 L, RT+5 °C~300 °C) and keep it warm for 12 h; (13) After taking out the centrifuge tube from the oven, pour the sample into the medium-speed filter paper, filter the solution, and retain the residue on the filter; (14) Rinse the centrifuge tube with a large amount of DMC solution to prevent any sample from remaining in the centrifuge tube; (15) Dry the residue on the filter in a 105 °C oven for 2 h; (16) After the sample baking is completed, put the sample into the corresponding self-sealing bag and weigh it; (17) Zero the scale, weigh the total mass of the residue on the filter, the medium-speed filter paper and the self-sealing bag, and record the mass m3; Calculate the crosslinking degree a of the polymer particles.

[0221] Mass swelling degree: (1) Dissolution: Mix 10 g of polymer particle powder and 90 g of N-methylpyrrolidone (NMP), and stir and dissolve at 40 °C for 7 h; (2) Preparation of the gel film: Place the stirred polymer particle powder gel liquid in a 250 mL beaker and bake at 70 °C for 8 days to obtain a dry gel film; (3) Swelling rate test: Take a dry gel film about 3 g in size with a thickness of 2 mm, weigh its exact mass as M1, soak it in the electrolyte (the mass ratio of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in the electrolyte solvent is 3:5:2, and prepare a 1 mol / L electrolyte by mixing the electrolyte solvent with lithium hexafluorophosphate (LiPF6)), place it in an oven at 70 °C, take out the sample piece after 24 h, let it stand for 1 h, wipe it clean, and weigh its mass M2. Calculate the mass swelling degree b of the polymer particles.

[0222] Table 2

[0223]

[0224] Perform the following tests on the batteries in the above examples and comparative examples, and the test results are shown in Table 3:

[0225] 1. Low-temperature adhesion performance:

[0226] (1) Select the prepared separator with a length of 300 mm × a width of 100 mm, as well as the positive and negative electrode plates prepared above.

[0227] (2) Wrap the upper and lower surfaces of the separator with paper, and use a knife die and a stamping machine to punch it into samples with a size of 54.2 mm × 72.5 mm.

[0228] (3) Neatly stack the punched separator samples with the positive electrode plate, place a Teflon with a size of 130 mm × 130 mm on each of the upper and lower surfaces, place the stacked samples in the middle of a 200 mm × 200 mm cardboard, and cover it with another 150 mm × 160 mm cardboard.

[0229] (4) Place the stacked samples in a flat press to adjust the pressure, adjust the air pressure, the flat press pressure = 3500 KG ± 10 KG (the contact area is about 50 mm × 100 mm, and the actual pressure after conversion is about 7 MPa), set T = 25 °C, and set the time to 10 s for pressing.

[0230] (5) Use a knife die and a stamping machine to punch the hot-pressed samples into small strips with a size of 72.5 mm × 15 mm.

[0231] (6) Fix one side of the positive electrode plate on the steel plate with double-sided tape, and bond a separator film on the other side. Use double-sided tape to bond an A4 paper strip with a width of 15 mm to the separator film to complete the production of the test sample.

[0232] (7) Turn on the high-speed tensile testing machine and set the parameters in sequence: adhesion force test, speed 50 mm / min, initial fixture spacing 40 mm.

[0233] (8) Place the test sample between the fixtures, fix the end of the steel plate to the lower chuck, and fix the A4 paper to the upper chuck. Clamp the upper and lower chucks tightly with fixtures respectively.

[0234] (9) Click on the stretching operation interface on the computer desktop, zero the force, displacement, etc., and then click "Start" to perform a pre-stretch of about 5 mm; after the pre-stretch, zero the force, displacement, etc. again and start the test. During the test, fix the steel plate with the fixed electrode plate, and the tensile testing machine pulls the A4 paper strip upward to separate the separator film from the positive electrode plate. After the test, export and save the complete data.

[0235] (10) Measure at least 5 test samples in each group. If the curves of the adhesion force tests of the 5 test samples have good repeatability, then proceed to the next group of tests. Otherwise, additional tests are required until the repeatability of the 5 test samples is good.

[0236] (11) After the test, plot the adhesion strength (N / m)-displacement curve, and take the average value of the data points from the 100th to the 300th as the adhesion force, and record the measured adhesion force as F1.

[0237] 2. Capacity retention rate at 25°C:

[0238] At 25°C, fix the battery with three-piece steel fixtures. There is a 1-mm unilateral heat insulation pad between the fixture and the battery. Apply a pre-tightening force of 0.1 MPa, then charge the battery at a constant current of 1C to the charging cut-off voltage of 3.65V, then charge at a constant voltage until the current ≤ 0.05C, let it stand for 5 min, and then discharge at a constant current of 0.33C to the discharge cut-off voltage of 2.8V, and let it stand for 5 min. Record the battery capacity C0 at this time. Charge and discharge the battery 1500 times in accordance with this method, and record the battery capacity after 1500 cycles as C1.

[0239] The cycle capacity retention rate of the battery at 25°C = C1 / C0 × 100%

[0240] 3. Low-temperature three-electrode lithium plating window:

[0241] The sample preparation steps include: (1) Take an unrolled bare battery cell, place three or more copper wires at the middle position of the separator film corresponding to the second outermost negative electrode tab, and fix them with tape at the upper edge of the anode tab; (2) Apply a small piece of separator film on the copper wires to ensure that the copper wires are covered and do not touch each other, and fix the separator film with tape; if it is a four-electrode battery, one or more copper wires (SE) need to be uncovered by the separator film and marked to distinguish them from the other copper wires; (3) Re-roll the bare battery cell carefully without shifting the copper wires, and pay attention to keeping the dimensions of the negative electrode tab in both the length and width directions larger than those of the positive electrode tab; (4) Continue with the rolling process, first cold press (25°C, 3 MPa, 10 s), then hot press (55°C, 5 MPa, 15 s) to obtain the battery cell to be tested.

[0242] The test steps include capacity test and continuous charging window test. The capacity test includes: (1) Let the battery cell to be tested stand for 30 min; (2) Charge it at a DC rate of 0.33C to 2.8 V; (3) Let it stand for 5 min; (4) Charge it at a constant current of 0.33C to 4.35 V, and then charge it at a constant voltage until the current ≤ 0.05C; (5) Let it stand for 5 min; (6) Discharge it at a DC rate of 0.33C to 2.8 V, and record the battery capacity C n ; (7) Let it stand for 5 min. Among them, during the entire capacity test process, the test temperature is 25°C, and the test sampling interval is 10S / mA / mV.

[0243] The continuous charging window test includes: (1) Let the battery cell to be tested stand for 30 min; (2) Charge it at a DC rate of 0.33C to 2.8 V; (3) Stop the current supply and place it at -10°C; (4) Let it stand for 2 h; (5) Charge it to 4.35 V at different rates, read the capacity C1 before the jump (the jump point is when the negative electrode potential reaches -10 mV or the voltage reaches 4.35 V), and conduct the test for the next rate. The test rates include: 0.08C, 0.1C, 0.2C, 0.4C, 0.6C, 0.8C, 1C, 1.5C, 2C, 3C. C1 / C n is the SOC at the jump. Taking SOC as the X-axis and the rate as the Y-axis, obtain the rate-SOC curve at this temperature. Through the rate-SOC curve, the charging rates corresponding to 5% SOC and 50% SOC can be obtained. The C1 corresponding to the corresponding SOC is the rate without lithium plating at this temperature. In the continuous charging window test, the test temperature for steps (1) and (2) is 25°C, and the test sampling interval is 60S / mA / mV; the test temperature for steps (3) and (4) is -10°C, and the test sampling interval is 60S / mA / mV; the test temperature for step (5) is -10°C, and the test sampling interval is 10S / mA / mV.

[0244] Table 3

[0245]

[0246] The test results show that the loss modulus of the polymer in Comparative Example 1 at 10 °C is less than 5×10 6 Pa, resulting in excessive swelling of the polymer. The mass swelling degree at 70 °C is 120%, deteriorating the bonding effect of the battery, while consuming too much electrolyte and causing a decline in the battery cycle performance. The loss modulus of the polymer in Comparative Example 2 at 10 °C is greater than 9×10 8 Pa, leading to the deterioration of the bonding effect of the separator at low temperature, the separation of the electrode sheet from the separator, and a significant decline in the battery cycle performance.

[0247] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same structure and the same effect as the technical idea within the scope of the technical solution of this application are included in the technical scope of this application. In addition, within the scope of not departing from the main idea of this application, various modifications that can be thought of by those skilled in the art to the embodiments, and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of this application.

Claims

1. An isolation film, characterized in that, It includes a base film and at least an adhesive layer on one side of the base film. The adhesive layer includes a polymer, and the loss modulus of the polymer at 10 °C is 5×10 6 Pa - 9×10 8 Pa.

2. The separator film according to claim 1, characterized in that, The crosslinking degree of the polymer is a, where a ≥ 75%.

3. The separator film according to claim 1 or 2, characterized in that, The mass swelling degree of the polymer at 70 °C is b, where 36% ≤ b ≤ 75%.

4. The separator film according to claim 3, characterized in that, 80% ≤ a ≤ 90%, and 43% ≤ b ≤ 60%.

5. The separator film according to any one of claims 1-4, characterized in that, The loss modulus of the polymer at 25 °C is 1×10 6 Pa - 9×10 7 Pa.

6. The separator film according to any one of claims 1-5, characterized in that, The monomer of the polymer and the derivatives of the monomer of the polymer at least include a first monomer, and the structure of the first monomer is shown in Formula 1: Among them, R1 includes a hydrogen atom or an alkyl group of C1-C4, and R2 includes a substituted or unsubstituted alkyl group of C1-C4, a substituted or unsubstituted isobornyl group of C3-C4, -CH2(CH2) n1 -O-benzene ring, -CH2(CH2) n2 -O epoxy group, wherein the substituent of the substituted alkyl group of C1-C4 includes a hydroxyl group or an alkyl group of C1-C6, and the n1 and the n2 are each independently 1-3.

7. The separator film according to claim 6, wherein, The first monomer includes at least one of ethyl acrylate, n-butyl acrylate, n-propyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isooctyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, vinyl acetate, trimethylolpropane triacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, 2-phenoxyethyl acrylate.

8. The separator film according to any one of claims 1-7, characterized in that, The monomer of the polymer and the derivatives of the monomer of the polymer further include a second monomer, and the structure of the second monomer is shown in Formula 2, and / or, Formula 3: and / or Wherein, R3 includes a hydrogen atom or an alkyl group of C1-C8, and R4 includes a hydrogen atom or an alkyl group of C1-C8.

9. The separator film according to claim 8, wherein, The second monomer includes at least one of acrylonitrile, methacrylonitrile, ethyl acrylonitrile, acrylic acid, methacrylic acid, crotonic acid, heptenoic acid.

10. The separator film according to any one of claims 1-9, characterized in that, The monomer of the polymer and the derivatives of the monomer of the polymer further include a third monomer, and the structure of the third monomer is shown in Formula 4: Wherein, R5 includes a hydrogen atom, a C1-C6 alkyl group substituted by a hydroxyl group or a C1-C6 alkoxy group, and R6 includes a hydrogen atom or an alkyl group of C1-C6.

11. The separator film according to claim 10, wherein The third monomer includes at least one of acrylamide, N-hydroxymethyl acrylamide, and N-butoxymethyl acrylamide.

12. The separator film according to any one of claims 1-11, characterized in that, The base film includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyaryl ether ketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cycloolefin copolymer, polyphenylene sulfide, polyvinylnaphthalene.

13. The separator film according to any one of claims 1-12, characterized in that, The loss modulus of the polymer at 10 °C is 6×10 7 Pa - 1.4×10 8 Pa.

14. A method for preparing the separator membrane according to any one of claims 1-13, characterized in that The polymer is disposed on at least one side of the base film to form an adhesive layer to obtain the separator membrane.

15. The method according to claim 14, wherein Providing the polymer includes: Blending and stirring the constituent monomers, emulsifier, and initiator of the polymer in a molar ratio of 100:(2-10):(0.2-1), and heating and reacting to obtain a polymer emulsion. The polymer emulsion is spray-dried to obtain a polymer.

16. The method according to claim 14 or 15, characterized in that The constituent monomers of the polymer include a first monomer, a second monomer, and a third monomer, wherein the mass ratio of the first monomer, the second monomer, and the third monomer is 100:(1-50):(10-40).

17. A battery, characterized in that, The separator membrane according to any one of claims 1-13, and / or the separator membrane obtained by the method according to any one of claims 14-16.

18. The battery according to claim 17, characterized in that, The battery is a lithium-ion battery, and at 10 °C, the lithium plating window of the battery is 0.7C - 1.5C.

19. An electrical device, characterized in that, Comprising the battery according to claim 17 or 18.

Images