An adhesive and its preparation method, an additive, a coating slurry, a battery separator and their applications

Abstract

The present application provides a binder, a preparation method thereof, an additive, a coating slurry, a battery separator and their applications, belonging to the technical field of battery manufacturing. The binder includes a first functional unit and / or a second functional unit. The first functional unit is used to react with HF, and the second functional unit is used to adsorb transition metal ions. By means of this binder, the problems of poor battery capacity and short battery cycle life of the corresponding battery can be improved to a certain extent.

Description

[0001] This application claims the priority of Chinese Patent Application No. 2023103729309, titled "A Binder, Additive, Coating Slurry, Battery Separator and Their Applications", filed on April 7, 2023, the entire content of which is incorporated herein by reference. Technical Field

[0002] This application relates to the technical field of battery manufacturing. Specifically, it relates to a binder and its preparation method, an additive, a coating slurry, a battery separator and their applications. Background Art

[0003] In the prior art, due to the instability of the electrolyte components in the battery, the current batteries have problems with poor battery capacity and battery cycle life. Summary of the Invention

[0004] The purpose of this application is to provide a binder and its preparation method, an additive, a coating slurry, a battery separator and their applications, which can, to a certain extent, improve the problems of poor battery capacity and battery cycle life of the corresponding battery.

[0005] The embodiments of this application are implemented as follows:

[0006] In a first aspect, an embodiment of this application provides a binder, including a first functional unit and / or a second functional unit. The first functional unit is used to react with HF, and the second functional unit is used to adsorb transition metal ions.

[0007] In the above technical solution, the binder includes a first functional unit capable of reacting with HF and a second functional unit capable of adsorbing transition metal ions, so that the battery containing this binder has a higher battery capacity and a longer cycle life. Among them, the first functional unit is used to react with the HF precipitated in the electrolyte (the existing electrolyte components usually precipitate HF, which will corrode the positive and negative electrodes of the battery), so as to reduce the risk of the positive and negative electrodes of the battery being corroded and damaged by HF, so that the battery containing this binder has a higher battery capacity. At the same time, it can also alleviate the dissolution phenomenon of transition metal ions in the battery positive electrode (HF will cause the precipitation of transition metal ions in the positive electrode); the second functional unit is used to adsorb the transition metal ions dissolved from the battery positive electrode, so as to reduce the risk of the transition metal ions depositing on the battery negative electrode and damaging the battery negative electrode, so that the battery containing this binder has a longer battery cycle life. Through the combined action of the two functional units, the adverse effects of the HF precipitated from the electrolyte on the battery can be reduced. At the same time, it can also effectively reduce the risk of the transition metal ions depositing on the battery negative electrode and damaging the battery negative electrode, thereby being able to improve the problems of poor battery capacity and battery cycle life of the corresponding battery to a certain extent.

[0008] In some alternative embodiments, the first functional unit includes substituents having silicon-oxygen bonds and / or silicon-nitrogen bonds.

[0009] In the above technical solution, the silicon-oxygen bond and / or silicon-nitrogen bond in the substituent acts as an electron donor and can react well with the electron acceptor HF to achieve the purpose of capturing HF, thereby reducing the risk of corrosion damage to the positive and negative electrodes of the battery, so that the battery containing this binder has a higher battery capacity. At the same time, it can also alleviate the dissolution phenomenon of transition metal ions in the positive electrode of the battery.

[0010] In some alternative embodiments, the first functional unit with substituents having silicon-oxygen bonds includes organosilicon olefins.

[0011] In the above technical solution, organosilicon olefins can react well with HF, thus more conveniently removing HF.

[0012] In some alternative embodiments, the second functional unit includes pyridine substituents and / or crown ether substituents.

[0013] In some alternative embodiments, the second functional unit includes one or more of pyridine substituents, imidazole substituents, and crown ether substituents.

[0014] In the above technical solution, pyridine, imidazole, and / or crown ether in the substituent can adsorb transition metal ions well, thereby reducing the risk of deposition of transition metal ions on the negative electrode of the battery and damaging the negative electrode of the battery, so that the battery containing this binder has a longer battery cycle life.

[0015] In some alternative embodiments, the binder includes a flocculant, and the flocculant includes one or more of polyacrylamide, chitosan, and cyclodextrin.

[0016] The flocculant provided in the embodiments of the present application can effectively adsorb transition metal ions well, which is beneficial to cooperate with the second functional unit to reduce the risk of deposition of transition metal ions on the negative electrode of the battery and damaging the negative electrode of the battery, so that the battery containing this binder has a longer battery cycle life.

[0017] In some alternative embodiments, the monomers of the binder include one or more of acrylate, acrylic acid, acrylonitrile, vinyl acetate, styrene, vinyl fluoride, vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene;

[0018] Optionally, the monomers of the binder further include at least one of carboxylic acid olefins and amide olefins.

[0019] The monomers of the binder provided by the embodiments of the present application include the above-mentioned various material types, that is, they can polymerize one or more monomers such as acrylate, acrylic acid, acrylonitrile, acrylamide, vinyl acetate, styrene, vinyl fluoride, vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene to form a polymer backbone, thereby facilitating the popularization and application of the technical solutions provided by the embodiments of the present application.

[0020] Furthermore, on this basis, monomers such as carboxylic acid olefins and amide olefins can be grafted onto the backbone to make the finally prepared binder have a better morphology and more suitable size.

[0021] In some alternative embodiments, the binder includes secondary particles.

[0022] In the above technical solution, the binder includes secondary particles (i.e., aggregated by a large number of primary particles). Compared with directly using primary particles as the binder, secondary particles can provide more contact sites, thereby providing stronger adhesion. At the same time, a large number of pores are generated during the particle packing process of secondary particles, which is beneficial to ion mass transfer, enabling the battery to have better comprehensive electrical properties.

[0023] In some alternative embodiments, the Dv of the secondary particles in the binder 50 is 3 - 50 μm;

[0024] Optionally, the Dv of the secondary particles in the binder 50 is 5 - 40 μm;

[0025] Optionally, the Dv of the secondary particles in the binder 50 is 10 - 30 μm.

[0026] In the above technical solution, the particle size of the binder is limited to a specific range because the binder within this size range has a more suitable size (i.e., contains an appropriate number of primary particles), thereby being able to provide an appropriate number of contact sites and thus an appropriate adhesion force.

[0027] Furthermore, limiting the particle size of the binder to a more preferred range can provide a more appropriate adhesion force.

[0028] In some alternative embodiments, the specific surface area of the secondary particles in the binder is 30 - 300 m 2 / g;

[0029] Optionally, the specific surface area of the secondary particles in the binder is 50 - 300 m 2 / g;

[0030] Optionally, the specific surface area of the secondary particles in the binder is 80 - 300 m 2 / g.

[0031] In the above technical solution, the binder has a large specific surface area, which is convenient for ion mass transfer, so that the battery has better comprehensive electrical properties.

[0032] In some alternative embodiments, the ash weight of the binder accounts for 0-10% of the binder weight;

[0033] Optionally, the ash weight of the binder accounts for 0-5% of the binder weight.

[0034] Optionally, the first functional unit accounts for 1-20 wt% of the binder weight, and the ash weight of the binder accounts for 0.25-5 wt% of the binder weight. In the above technical solution, the ash weight of the binder is within the above specific range, which proves that the binder has a first functional unit with an appropriate mass ratio, so that HF can be better removed.

[0035] In a second aspect, an embodiment of the present application provides a preparation method of the binder provided in the first aspect embodiment, which includes the following steps:

[0036] Dissolve the emulsifier in water and mix at a preset temperature to obtain a first reaction solution;

[0037] Dissolve the initiator in water and mix to obtain a second reaction solution;

[0038] Mix the first monomer, the functional monomer and the first chelating agent to obtain a third reaction solution, wherein the functional monomer is used to provide the first functional unit, and the first chelating agent is used to provide the second functional unit;

[0039] Mix the second reaction solution and the third reaction solution, then add them to the first reaction solution and mix to obtain a mixed solution;

[0040] React the mixed solution at a preset temperature to obtain a precursor solution;

[0041] Add a flocculant to the precursor solution and mix to obtain a solution containing the binder.

[0042] In the above technical solution, the first monomer and the functional monomer undergo a polymerization reaction with the assistance of the emulsifier and the initiator to form a polymer backbone. The first chelating agent is embedded in the polymer chain under the action of hydrogen bonds to form primary particles containing both the first functional unit and the second functional unit. Then, under the action of the flocculant, the primary particles agglomerate to form secondary particles to prepare a solution containing the binder.

[0043] In some alternative embodiments, the first monomer includes one or more of acrylate, styrene, tetrafluoroethylene, and vinylidene fluoride; and / or,

[0044] The functional monomer includes organosilicon olefins; and / or,

[0045] The first chelating agent includes one or more of polyamine chelating agents and cyclic chelating agents;

[0046] Optionally, by weight, the weight ratio of the first monomer, the functional monomer, and the first chelating agent is successively (100-300):(0.1-50):(0.1-50).

[0047] The above-mentioned first monomer, functional monomer, and first chelating agent have good cooperation effects. Selecting a suitable ratio is beneficial to making the primary particles contain appropriate first functional units and second functional units simultaneously, is beneficial to reducing the adverse effects of HF precipitated from the electrolyte on the battery, and at the same time, can effectively reduce the risk of transition metal ions depositing on the negative electrode of the battery and damaging the negative electrode of the battery, thereby being able to improve the problems of poor battery capacity and battery cycle life of the corresponding battery to a certain extent.

[0048] In some alternative embodiments, the weight ratio of the flocculant to the first monomer is (1-5):(100-300);

[0049] Optionally, the flocculant includes one or more of polyacrylamide, chitosan, and cyclodextrin.

[0050] Utilizing the above selection of the flocculant is not only beneficial to agglomerating the primary particles to form secondary particles with a reasonable particle size, beneficial to providing stronger adhesion, and beneficial to making the battery have better comprehensive electrical properties, but also the addition of the flocculant is beneficial to the adsorption of transition metal ions.

[0051] In some alternative embodiments, in the step of preparing the second reaction solution, it further includes: adding a second monomer and a second chelating agent to the mixture of the initiator and water, wherein the second monomer includes one or more of carboxylic acid olefins and amide olefins, and the second chelating agent includes amino carboxylic acid chelating agents.

[0052] By selectively adding the second monomer and the second chelating agent, it is possible to make the binder prepared subsequently have a better morphology and a more suitable particle size.

[0053] Optionally, by weight, the weight ratio of the second monomer, the second chelating agent, and water in the second reaction solution is successively (10-200):(0.1-50):(100-300). Thirdly, an embodiment of the present application provides a coating slurry containing the binder provided in the embodiment of the first aspect.

[0054] In some alternative embodiments, the coating slurry further includes at least one inorganic material.

[0055] In the above technical solution, adding inorganic materials to the coating slurry can endow the coating slurry with more abundant functions.

[0056] In some alternative embodiments, the inorganic materials include one or more of alumina, boehmite, silica, titanium oxide, cerium oxide, calcium oxide, zinc oxide, magnesium oxide, lithium nitride, calcium carbonate, barium sulfate, lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, cerium titanate, calcium titanate, barium titanate, and lithium lanthanum titanate.

[0057] The technical solution of the present application is applicable to the above-mentioned various inorganic material systems, which can provide more alternative embodiments, thus facilitating the popularization and application of the technical solution of the present application.

[0058] Fourthly, an embodiment of the present application provides a battery separator, including a base film and a coating containing the binder provided in the third aspect embodiment, and the coating is located on at least one surface of the base film.

[0059] Fifthly, an embodiment of the present application provides a battery separator, including a ceramic coated film and a coating containing the binder provided in the third aspect embodiment, and the coating is located on at least one surface of the base film.

[0060] In some alternative embodiments, the adhesion of the battery separator is 5 to 50 N / m;

[0061] Optionally, the adhesion of the battery separator is 10 to 50 N / m;

[0062] Optionally, the adhesion of the battery separator is 20 to 50 N / m.

[0063] Sixthly, an embodiment of the present application provides an application of the battery separator provided in the fourth aspect and / or the fifth aspect embodiment in a secondary battery.

[0064] In some alternative embodiments, the following conditions A and / or B are satisfied:

[0065] A. The HF removal rate of the binder in the secondary battery is 0 to 90%;

[0066] Optionally, the HF removal rate of the binder in the secondary battery is 30 to 90%;

[0067] Optionally, the HF removal rate of the binder in the secondary battery is 50 to 90%;

[0068] B. The transition metal ion removal rate of the binder in the secondary battery is 0 to 90%;

[0069] Optionally, the transition metal ion removal rate of the binder in the secondary battery is 30 to 90%;

[0070] Optionally, the binder has a transition metal ion removal rate of 50-90% in the secondary battery.

[0071] In some alternative embodiments, the secondary battery includes one or more of a lithium-ion secondary battery and a sodium-ion secondary battery.

[0072] The battery separator provided by the embodiments of the present application is applicable to the above-mentioned various secondary battery systems, and can provide more implementable solutions, thereby facilitating the popularization and application of the technical solutions provided by the embodiments of the present application.

[0073] In a seventh aspect, an additive is provided according to an embodiment of the present application, including a first functional unit and / or a second functional unit. The first functional unit is used to react with HF, and the second functional unit is used to adsorb transition metal ions.

[0074] In the above technical solution, the additive includes a first functional unit capable of reacting with HF and a second functional unit capable of adsorbing transition metal ions, so that the battery containing the additive has a higher battery capacity and a longer cycle life. Among them, the first functional unit is used to react with the HF precipitated in the electrolyte (the existing electrolyte components usually precipitate HF, which will corrode the positive and negative electrodes of the battery), so as to reduce the risk of the positive and negative electrodes of the battery being corroded and damaged by HF, so that the battery containing the additive has a higher battery capacity. At the same time, it can also alleviate the dissolution phenomenon of transition metal ions in the battery positive electrode (HF will cause the transition metal ions in the positive electrode to precipitate); the second functional unit is used to adsorb the transition metal ions dissolved from the battery positive electrode, so as to reduce the risk of the transition metal ions depositing on the battery negative electrode and damaging the battery negative electrode, so that the battery containing the additive has a longer battery cycle life. Through the combined action of the two functional units, the adverse effects of the HF precipitated from the electrolyte on the battery can be reduced. At the same time, the risk of the transition metal ions depositing on the battery negative electrode and damaging the battery negative electrode can be effectively reduced, thereby improving the problems of poor battery capacity and battery cycle life of the corresponding battery to a certain extent.

[0075] In an eighth aspect, a coating slurry is provided according to an embodiment of the present application, containing the additive provided by the embodiment of the seventh aspect.

[0076] In a ninth aspect, a battery separator is provided according to an embodiment of the present application, including:

[0077] a base film; and

[0078] a coating containing the coating slurry provided by the embodiment of the eighth aspect, the coating being located on at least one surface of the base film.

[0079] In a tenth aspect, a battery separator is provided according to an embodiment of the present application, including:

[0080] a ceramic coated film; and

[0081] A coating containing the coating slurry provided in the embodiment of the eighth aspect, the coating being located on at least one surface of the ceramic coated film.

[0082] In the eleventh aspect, the embodiment of the present application provides an application of the battery separator provided in the embodiment of the ninth or tenth aspect in a secondary battery. Description of the Drawings

[0083] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0084] Figure 1 SEM result diagram at low magnification of the binder prepared in Example 1 of the present application;

[0085] Figure 2 SEM result diagram at high magnification of the binder prepared in Example 1 of the present application;

[0086] Figure 3 DLS result diagram before and after the agglomeration of primary particles provided in the embodiment of the present application;

[0087] Figure 4 Effect diagram of HF removal of the binders provided in Example 1 of the present application and Comparative Example 1;

[0088] Figure 5 Effect diagram of transition metal ion removal of the binders provided in Example 1 of the present application and Comparative Example 1;

[0089] Figure 6 Adhesion test result diagram of the binders provided in Example 1 of the present application and Comparative Example 1. Detailed Description of the Embodiments

[0090] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0091] It should be noted that "and / or" in the present application, such as "feature 1 and / or feature 2", refers to the three cases of "feature 1" alone, "feature 2" alone, and "feature 1" plus "feature 2".

[0092] In addition, in the description of the present application, unless otherwise specified, "multiple" in "one or more" means two or more; the range of "numerical value a to numerical value b" includes the two end values "a" and "b", and the "measurement unit" in "numerical value a to numerical value b + measurement unit" represents the "measurement unit" of both "numerical value a" and "numerical value b".

[0093] In the prior art, the electrolyte components in the battery (such as LiPF6 or NaPF6) usually precipitate HF. On the one hand, the generated HF will corrode and damage the positive and negative electrodes of the battery, resulting in the attenuation of the battery capacity; on the other hand, HF will cause the dissolution of transition metal ions in the positive electrode of the battery, and the dissolved transition metal ions will deposit on the negative electrode of the battery and cause damage to the negative electrode of the battery, thereby reducing the cycle life of the battery.

[0094] Currently, the commonly used solutions are as follows:

[0095] (1) Element substitution in the active material, that is, using other elements to replace the transition metal elements in the positive electrode material.

[0096] (2) Adding a coating on the surface of the active material to avoid direct contact between the positive electrode of the battery and the electrolyte through the coating, thereby reducing the attack of HF.

[0097] (3) Passivation of the positive and negative electrodes of the battery, that is, forming a protective film on the positive and negative electrodes through electrolyte additives.

[0098] However, it is difficult to achieve good results by combining one or more of the above methods.

[0099] Based on this, the inventors of the present application have found through research that by endowing the battery binder with more functions, that is, adding functional units capable of reacting with HF and functional units capable of adsorbing transition metal ions, the problems of poor battery capacity and poor battery cycle life of the corresponding battery can be improved to a certain extent.

[0100] The following specifically describes a binder, its preparation method, additive, coating slurry, battery separator and its application in the embodiments of the present application.

[0101] In a first aspect, an embodiment of the present application provides a binder, including a first functional unit and / or a second functional unit, the first functional unit is used to react with HF, and the second functional unit is used to adsorb transition metal ions.

[0102] It should be noted that in the art, in addition to having corresponding functional units, polymer binders usually contain a hydrophobic polymer backbone, which is generally formed by polymerization of corresponding monomers so as to be able to prepare a binder in the form of particles.

[0103] It is understandable that the monomer type of the hydrophobic polymer backbone is not limited and can be set according to the conventional selection in the art.

[0104] In the present application, the binder includes a first functional unit capable of reacting with HF and a second functional unit capable of adsorbing transition metal ions, so that the battery containing the binder has a higher battery capacity and a longer cycle life. Among them, the first functional unit is used to react with the HF precipitated in the electrolyte (the existing electrolyte components usually precipitate HF, which will corrode the positive and negative electrodes of the battery), so as to reduce the risk of corrosion damage of the positive and negative electrodes of the battery by HF, so that the battery containing the binder has a higher battery capacity. At the same time, it can also alleviate the dissolution phenomenon of transition metal ions in the battery positive electrode (HF will cause the precipitation of transition metal ions in the positive electrode); the second functional unit is used to adsorb the transition metal ions dissolved from the battery positive electrode, so as to reduce the risk of deposition of transition metal ions on the battery negative electrode and damage the battery negative electrode, so that the battery containing the binder has a longer battery cycle life. Through the combined action of the two functional units, the adverse effects of HF precipitated from the electrolyte on the battery can be reduced. At the same time, the risk of deposition of transition metal ions on the battery negative electrode and damage to the battery negative electrode can also be effectively reduced, so as to improve the problems of poor battery capacity and battery cycle life of the corresponding battery to a certain extent.

[0105] As an example, the first functional unit includes a substituent having a silicon-oxygen bond and / or a silicon-nitrogen bond.

[0106] In this embodiment, the silicon-oxygen bond and / or silicon-nitrogen bond in the substituent act as electron donors and can react with the electron acceptor HF to achieve the purpose of capturing HF, thereby reducing the risk of corrosion damage of the positive and negative electrodes of the battery by HF, so that the battery containing the binder has a higher battery capacity. At the same time, it can also alleviate the dissolution phenomenon of transition metal ions in the battery positive electrode. In particular, the silicon-nitrogen bond in the substituent has a high electron donor ability and can scavenge HF and PF5 and form a good complex with HF. As an example, the first functional unit with a substituent having a silicon-oxygen bond includes organosilicon olefins.

[0107] In this embodiment, organosilicon olefins can react well with HF, thus more conveniently removing HF.

[0108] As an example, the second functional unit includes pyridine-based substituents and / or crown ether-based substituents.

[0109] In this embodiment, pyridine and / or crown ether in the substituent can adsorb transition metal ions, thereby reducing the risk of transition metal ions depositing on the negative electrode of the battery and damaging the negative electrode of the battery, so that the battery containing this binder has a long battery cycle life. Among them, because the crown ether substituents have multiple coordinating atoms, they can coordinate with metal ions of different sizes, and different crown ether substituents have different selectivities for transition metal ions.

[0110] As an example, the second functional unit includes one or more of pyridine substituents, imidazole substituents, and crown ether substituents.

[0111] In this embodiment, pyridine, imidazole, and / or crown ether in the substituent can all adsorb transition metal ions, which is beneficial to making the battery containing this binder have a long battery cycle life.

[0112] As an example, the monomers of the binder include one or more of acrylate, acrylic acid, acrylonitrile, vinyl acetate, styrene, vinyl fluoride, vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene.

[0113] Optionally, the monomers of the binder further include at least one of carboxylic acid olefins and amide olefins.

[0114] In this embodiment, the monomers of the binder provided in the embodiments of the present application include the above-mentioned various material types, that is, they can polymerize with one or more monomers such as acrylate, acrylic acid, acrylonitrile, acrylamide, vinyl acetate, styrene, vinyl fluoride, vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene to form a polymer backbone, thus facilitating the popularization and application of the technical solutions provided in the embodiments of the present application.

[0115] Furthermore, on this basis, monomers such as carboxylic acid olefins and amide olefins can be grafted onto the backbone to make the finally prepared binder have a better morphology and more suitable size.

[0116] As an example, the binder includes secondary particles.

[0117] In this embodiment, the binder includes secondary particles (i.e., aggregated by a large number of primary particles). Compared with directly using primary particles as the binder, secondary particles can provide more contact sites, thereby providing stronger adhesion. At the same time, a large number of pores are generated during the particle stacking process of secondary particles, which is beneficial to ion mass transfer, so that the battery has good comprehensive electrical properties.

[0118] As an example, the Dv of the secondary particles in the binder 50 is 3 - 50 μm, for example but not limited to Dv 50It is any one of the point values of 3 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, and 50 μm or the range value between any two of them.

[0119] Optionally, the Dv of the secondary particles in the binder 50 is 5 - 40 μm. For example, but not limited to, Dv 50 is any one of the point values of 5 μm, 10 μm, 20 μm, 30 μm, and 40 μm or the range value between any two of them.

[0120] Optionally, the Dv of the secondary particles in the binder 50 is 10 - 30 μm. For example, but not limited to, Dv 50 is any one of the point values of 10 μm, 20 μm, and 30 μm or the range value between any two of them.

[0121] In this embodiment, the particle size of the binder is limited within a specific range because the binder within this size range has a more suitable size (i.e., contains a suitable number of primary particles), thus being able to provide a suitable number of contact sites and further providing a suitable adhesive force.

[0122] Furthermore, limiting the particle size of the binder within a more preferred range can provide a more suitable adhesive force.

[0123] As an example, the specific surface area of the secondary particles in the binder is 30 - 300 m 2 / g. For example, but not limited to, the specific surface area is 30 m 2 / g, 50 m 2 / g, 100 m 2 / g, 150 m 2 / g, 200 m 2 / g, 250 m 2 / g, and 300 m 2 / g, which is any one of the point values or the range value between any two of them.

[0124] Optionally, the specific surface area of the secondary particles in the binder is 50 - 300 m 2 / g. For example, but not limited to, the specific surface area is 50 m 2 / g, 100 m 2 / g, 150 m 2 / g, 200 m 2 / g, 250 m 2 / g, and 300 m 2 / g, which is any one of the point values or the range value between any two of them.

[0125] Optionally, the specific surface area of the secondary particles in the binder is 80 - 300 m 2 / g, such as but not limited to a specific surface area of 80 m 2 / g, 100 m 2 / g, 150 m 2 / g, 200 m 2 / g, 250 m 2 / g, and 300 m 2 / g, any one of the point values or the range values between any two of them.

[0126] In this embodiment, the binder has a large specific surface area, which facilitates ion mass transfer, so that the battery has better comprehensive electrical properties.

[0127] As an example, the ash weight of the binder accounts for 0-10% of the binder weight.

[0128] Optionally, the ash weight of the binder accounts for 0-5% of the binder weight.

[0129] Optionally, the first functional unit accounts for 1-20 wt% of the binder weight, and the ash weight of the binder accounts for 0.25-5 wt% of the binder weight.

[0130] It can be understood that ash refers to a series of physical and chemical changes that occur when the binder is burned at high temperature. Finally, the organic components volatilize and disperse, while the inorganic components remain. These residues are called ash. The ash of the binder is mainly silicon oxide and silicon nitride that make up the first functional unit. In this embodiment, the ash weight of the binder is within the above specific range, which proves that the binder has an appropriate mass ratio of the first functional unit, so as to better remove HF.

[0131] It should be noted that, in order to better understand the technical solution, the preparation method of the binder will be described below.

[0132] In the second aspect, the preparation method of the binder provided in the embodiment of the present application includes the following steps:

[0133] Dissolve the emulsifier in water and mix at a preset temperature to obtain a first reaction solution;

[0134] Dissolve the initiator in water and mix to obtain a second reaction solution;

[0135] Mix the first monomer, the functional monomer and the first chelating agent to obtain a third reaction solution, wherein the functional monomer is used to provide the first functional unit, and the first chelating agent is used to provide the second functional unit;

[0136] Mix the second reaction solution and the third reaction solution, then add them to the first reaction solution and mix to obtain a mixed solution;

[0137] React the mixed solution at a preset temperature to obtain a precursor solution;

[0138] A flocculant is added to the precursor solution and mixed to obtain a solution containing a binder.

[0139] In this embodiment, the first monomer and the functional monomer undergo a polymerization reaction with the assistance of an emulsifier and an initiator to form a polymer backbone. The first chelating agent is embedded in the polymer chain under the action of hydrogen bonds to form primary particles containing both the first functional unit and the second functional unit. Then, under the action of the flocculant, the primary particles agglomerate to form secondary particles, so as to prepare a solution containing a binder.

[0140] It should be noted that what exists in the precursor solution are primary particles, that is, the monomer form of the secondary particles.

[0141] It can be understood that in order to be able to prepare a binder with a suitable size, the particle size of the primary particles can be adjusted.

[0142] As an example, the particle size of the primary particles is 50 - 1000 nm.

[0143] It should be noted that when preparing a binder having only the first functional unit or the second functional unit, in the stage of preparing the third reaction solution, only the functional monomer and the first chelating agent need to be selectively added, wherein the functional monomer corresponds to forming the first functional unit capable of reacting with HF, and the first chelating agent corresponds to forming the second functional unit for adsorbing transition metal ions.

[0144] It should be noted that the mass ratio of the emulsifier in the first reaction solution is not limited and can be adjusted according to actual needs.

[0145] As an example, by weight, the weight ratio of water to the emulsifier is (500 - 700):(0.1 - 2).

[0146] It should be noted that the type of the emulsifier is not limited and can be set according to the conventional selection in the art.

[0147] As an example, the emulsifier includes one or more of sodium dodecyl sulfonate and sodium dodecyl benzene sulfonate.

[0148] It should be noted that the preset temperature is not limited and can be adjusted according to actual needs.

[0149] As an example, the preset temperature is 60 - 80 °C.

[0150] It should be noted that the mass ratio of the initiator in the second reaction solution is not limited and can be adjusted according to actual needs.

[0151] As an example, the weight ratio of water to the initiator is (100 to 300):(0.1 to 3) by weight parts.

[0152] It should be noted that the type of the initiator is not limited and can be set according to the conventional selection in the art.

[0153] As an example, the initiator includes one or more of potassium persulfate, ammonium persulfate, and sodium persulfate.

[0154] As an example, in the step of preparing the second reaction solution, it further includes: adding a second monomer and a second chelating agent to the mixture of the initiator and water.

[0155] In this embodiment, the prepared second reaction solution contains the second monomer and the second chelating agent, which can enable the binder prepared subsequently to have a better morphology and a more suitable particle size.

[0156] It should be noted that the mass ratio of the second monomer and the second chelating agent in the second reaction solution is not limited and can be adjusted according to actual needs.

[0157] As an example, by weight parts, the weight ratio of the second monomer, the second chelating agent, and water is (10 to 200):(0.1 to 50):(100 to 300) in sequence.

[0158] It should be noted that the types of the second monomer and the second chelating agent are not limited and can be set according to the conventional selection in the art.

[0159] As an example, the second monomer includes one or more of carboxylic acid olefins and amide olefins.

[0160] Optionally, the carboxylic acid olefins include one or more of acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid.

[0161] Optionally, the amide olefins include one or more of acrylamide, methacrylamide, acrylonitrile, acrylamide, and vinyl acetate.

[0162] As an example, the second chelating agent includes amino carboxylic acid chelating agents.

[0163] Optionally, the amino carboxylic acid chelating agents include one or more of ethylenediaminetetraacetic acid, ethylene glycol tetraacetic acid, ethylenediamine diacetic acid, diethylenetriamine pentaacetic acid, and sodium iminodiacetate.

[0164] It should be noted that the mass ratio of each component in the third reaction solution is not limited and can be adjusted according to actual needs.

[0165] As an example, by weight parts, the weight part ratio of the first monomer, the functional monomer and the first chelating agent is successively (100 to 300):(0.1 to 50):(0.1 to 50).

[0166] It should be noted that the types of the first monomer, the functional monomer and the first chelating agent are not limited and can be set according to the conventional selection in the art.

[0167] As an example, the first monomer includes one or more of acrylate, styrene, tetrafluoroethylene and vinylidene fluoride.

[0168] Optionally, the acrylate includes one or more of ethyl acrylate, isooctyl acrylate, methyl acrylate, methyl methacrylate, butyl acrylate and butyl methacrylate.

[0169] Optionally, the styrene includes one or more of styrene and methylstyrene.

[0170] As an example, the functional monomer includes organosilicon olefins.

[0171] Optionally, the organosilicon olefins include one or more of methacryloxypropyltrimethoxysilane and vinyltriethoxysilane.

[0172] As an example, the first chelating agent includes one or more of polyamine chelating agents and cyclic chelating agents.

[0173] Optionally, the polyamine chelating agents include one or more of dimethylpyridineamine, 4-vinylpyridine and 2,2-bipyridine.

[0174] Optionally, the cyclic chelating agents include one or more of 18-crown-6 and 15-crown-5.

[0175] It should be noted that the dosage of the flocculant is not limited and can be set according to the conventional selection in the art.

[0176] As an example, by weight parts, the weight part ratio of the flocculant and the first monomer is (1 to 5):(100 to 300).

[0177] It should be noted that the type of the flocculant is not limited and can be set according to the conventional selection in the art.

[0178] As an example, the flocculant includes one or more of polyacrylamide and chitosan.

[0179] It should be noted that in the step of adding the first reaction solution and mixing after mixing the second reaction solution and the third reaction solution, the adding method is not limited and can be set according to the conventional selection in the art.

[0180] As an example, the dropping method is adopted.

[0181] It should be noted that the dropping time is not limited and can be adjusted according to actual needs.

[0182] As an example, the dropping time is 1 - 5 h.

[0183] It should be noted that the reaction duration of the mixed solution at the preset temperature is not limited and can be adjusted according to actual needs.

[0184] As an example, the reaction time is 3 - 7 h.

[0185] It should be noted that for the steps or processes not specifically described or limited in the preparation process of the binder, there are no limitations, and they can be set according to the conventional selection in the art.

[0186] As an example, after obtaining the solution containing the binder, it further includes the step of drying the solution containing the binder to obtain the binder powder.

[0187] In a third aspect, an embodiment of the present application provides a coating slurry containing the binder provided in the embodiment of the first aspect.

[0188] As an example, the coating slurry further includes at least one inorganic material.

[0189] In this embodiment, adding an inorganic material to the coating slurry can endow the coating slurry with more abundant functions.

[0190] As an example, the inorganic material includes one or more of alumina, boehmite, silica, titanium oxide, cerium oxide, calcium oxide, zinc oxide, magnesium oxide, lithium nitride, calcium carbonate, barium sulfate, lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, cerium titanate, calcium titanate, barium titanate, and lithium lanthanum titanate.

[0191] In this embodiment, the technical solution of the present application is applicable to the above - mentioned various inorganic material systems, which can provide more implementation schemes, thus facilitating the popularization and application of the technical solution of the present application.

[0192] It can be understood that in addition to including the binder provided in the embodiment of the first aspect, various auxiliary additives can also be added to the coating slurry.

[0193] As an example, the coating slurry further includes one or more of a dispersant, a wetting agent, a thickener, a ceramic, and an adhesive.

[0194] It should be noted that the type of each component is not limited and can be set according to the conventional selection in the art.

[0195] As an example, the dispersant includes one or more of polyether silane and sodium polyacrylate.

[0196] As an example, the wetting agent includes sodium dodecylbenzenesulfonate.

[0197] As an example, the thickener includes hydroxymethyl cellulose.

[0198] As an example, the ceramic includes one or more of alumina, boehmite, barium sulfate, and silica.

[0199] As an example, the binder includes one or more of polyacrylic acid, polyacrylonitrile, styrene-butadiene copolymer, and polyurethane.

[0200] It should be noted that the mass ratio of each component in the coating slurry is not limited and can be set according to the conventional selection in the art.

[0201] In a fourth aspect, an embodiment of the present application provides a battery separator, including a base film and a coating containing the binder provided in the embodiment of the first aspect, and the coating is located on at least one surface of the base film.

[0202] It should be noted that the material of the base film is not limited and can be set according to the conventional selection in the art.

[0203] As an example, the material of the base film includes one or more of PE, PP, PET, and polyimide.

[0204] It should be noted that for other components in the coating, the components of a coating slurry provided in the embodiment of the second aspect can be referred to for setting.

[0205] It should be noted that the coating method during the preparation of the coating is not limited and can be set according to the conventional selection in the art.

[0206] As an example, the coating method includes one or more of gravure roll coating, wire bar coating, and extrusion coating.

[0207] It should be noted that the specific process and step parameters during the coating process are not limited and can be set according to the conventional selection in the art.

[0208] To better understand the technical solution, the following is described through a specific separator preparation process.

[0209] As an example, the separator preparation process includes the following steps:

[0210] Mix water, a dispersant, a thickener, and ceramic particles according to the required mass ratio to obtain a first solution;

[0211] The first solution is ground, and a binder, an adhesive, and a wetting agent are added to the ground first solution and mixed to obtain a coating slurry;

[0212] The coating slurry is coated on both sides of a PE base film by roll coating to obtain a separator.

[0213] It should be noted that the process steps and parameter settings in the separator preparation process are not limited and can be set according to the conventional selection in the art.

[0214] In a fifth aspect, an embodiment of the present application provides a battery separator, including a ceramic coating film and a coating containing the binder provided in the embodiment of the third aspect, and the coating is located on at least one surface of the base film.

[0215] As an example, the adhesion of the battery separator is 5 to 50 N / m, such as but not limited to any one of the point values of 5 N / m, 10 N / m, 20 N / m, 30 N / m, 40 N / m, and 50 N / m or the range values between any two of them.

[0216] Optionally, the adhesion of the battery separator is 10 to 50 N / m, such as but not limited to any one of the point values of 10 N / m, 20 N / m, 30 N / m, 40 N / m, and 50 N / m or the range values between any two of them.

[0217] Optionally, the adhesion of the battery separator is 20 to 50 N / m, such as but not limited to any one of the point values of 20 N / m, 30 N / m, 40 N / m, and 50 N / m or the range values between any two of them.

[0218] In a sixth aspect, an embodiment of the present application provides an application of the battery separator provided in the embodiment of the fourth aspect in a secondary battery.

[0219] As an example, it satisfies A and / or B in the following conditions:

[0220] A. The HF removal rate of the binder in the secondary battery is 0 to 90%, such as but not limited to any one of the point values of 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% or the range values between any two of them.

[0221] Optionally, the HF removal rate of the binder in the secondary battery is 30 to 90%, such as but not limited to any one of the point values of 30%, 40%, 50%, 60%, 70%, 80%, and 90% or the range values between any two of them.

[0222] Optionally, the HF removal rate of the binder in the secondary battery is 50 to 90%, for example but not limited to any one of the point values of 50%, 60%, 70%, 80%, and 90% or the range value between any two of them for the HF removal rate.

[0223] It should be noted that since the electrolyte composition in the secondary electrolytic cell is unstable, it will react with the measured water present in the battery to generate HF.

[0224] It should be noted that in this field, the test of the HF removal rate is usually to soak the separator in the electrolyte for a certain period of time, and then determine the removal rate according to the difference in HF concentration before and after soaking.

[0225] It should be noted that the specific model of the secondary battery is not limited and can be set according to the conventional selection in this field.

[0226] As an example, the electrolyte in the secondary battery is an ester-based electrolyte containing lithium hexafluorophosphate or sodium hexafluorophosphate.

[0227] As an example, the positive electrode active material in the secondary battery is of the type containing transition metals, such as lithium iron manganese phosphate and high-nickel positive electrodes, etc.

[0228] B. The removal rate of the binder for transition metal ions in the secondary battery is 0 to 90%, for example but not limited to any one of the point values of 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% or the range value between any two of them for the removal rate of transition metal ions.

[0229] Optionally, the removal rate of the binder for transition metal ions in the secondary battery is 30 to 90%, for example but not limited to any one of the point values of 30%, 40%, 50%, 60%, 70%, 80%, and 90% or the range value between any two of them for the removal rate of transition metal ions.

[0230] Optionally, the removal rate of the binder for transition metal ions in the secondary battery is 50 to 90%, for example but not limited to any one of the point values of 50%, 60%, 70%, 80%, and 90% or the range value between any two of them for the HF removal rate.

[0231] It should be noted that the battery positive electrode active material usually contains transition metal elements, and HF will cause it to dissolve out from the positive electrode active material to form transition metal ions.

[0232] It should be noted that the test method of the transition metal ion removal rate and the general application system can refer to the content of the HF removal rate.

[0233] As an example, the secondary battery includes one or more of a lithium-ion secondary battery and a sodium-ion secondary battery.

[0234] In this embodiment, the battery separator provided by the embodiment of the present application is applicable to the above-mentioned various secondary battery systems, and can provide more implementable solutions, thereby facilitating the popularization and application of the technical solution provided by the embodiment of the present application.

[0235] In a seventh aspect, the embodiment of the present application provides an additive, including a first functional unit and / or a second functional unit. The first functional unit is used to react with HF, and the second functional unit is used to adsorb transition metal ions.

[0236] In the present application, the additive includes a first functional unit capable of reacting with HF and a second functional unit capable of adsorbing transition metal ions, so that the battery containing the additive has a higher battery capacity and a longer cycle life. Among them, the first functional unit is used to react with the HF precipitated in the electrolyte (the existing electrolyte components usually precipitate HF, which will corrode the positive and negative electrodes of the battery), so as to reduce the risk of the positive and negative electrodes of the battery being corroded and damaged by HF, so that the battery containing the additive has a higher battery capacity. At the same time, it can also alleviate the dissolution phenomenon of transition metal ions in the positive electrode of the battery (HF will cause the transition metal ions in the positive electrode to precipitate); the second functional unit is used to adsorb the transition metal ions dissolved from the positive electrode of the battery, so as to reduce the risk of the transition metal ions depositing on the negative electrode of the battery and damaging the negative electrode of the battery, so that the battery containing the additive has a longer battery cycle life. Through the combined action of the two functional units, the adverse effects of the HF precipitated from the electrolyte on the battery can be reduced. At the same time, it can also effectively reduce the risk of the transition metal ions depositing on the negative electrode of the battery and damaging the negative electrode of the battery, thereby being able to improve the problems of poor battery capacity and poor battery cycle life of the corresponding battery to a certain extent.

[0237] As an example, the first functional unit includes a substituent having a silicon-oxygen bond and / or a silicon-nitrogen bond.

[0238] In this embodiment, the silicon-oxygen bond and / or the silicon-nitrogen bond in the substituent act as electron donors and can react with the electron acceptor HF to achieve the purpose of capturing HF, thereby reducing the risk of the positive and negative electrodes of the battery being corroded and damaged by HF, so that the battery containing the binder has a higher battery capacity. At the same time, it can also alleviate the dissolution phenomenon of transition metal ions in the positive electrode of the battery. In particular, the silicon-nitrogen bond in the substituent has a high electron donor ability and can scavenge HF and PF5, and can form a good complex with HF. As an example, the first functional unit of the substituent having a silicon-oxygen bond includes organosilicon olefins.

[0239] In this embodiment, the organosilicon olefins can react well with HF, so as to more conveniently remove HF.

[0240] As an example, the second functional unit includes a pyridine-based substituent and / or a crown ether-based substituent.

[0241] In this embodiment, pyridine and / or crown ether in the substituent can adsorb transition metal ions, thereby reducing the risk of transition metal ions depositing on the negative electrode of the battery and damaging the negative electrode of the battery, so that the battery containing this binder has a long battery cycle life. Among them, since the crown ether-based substituent has multiple coordination atoms, it can coordinate with metal ions of different sizes, and different crown ether-based substituents have different selectivities for transition metal ions. In the eighth aspect, an embodiment of the present application provides a coating slurry containing the additive provided in the embodiment of the seventh aspect.

[0242] In the ninth aspect, an embodiment of the present application provides a battery separator, including:

[0243] a base film; and

[0244] a coating containing the coating slurry provided in the embodiment of the eighth aspect, and the coating is located on at least one surface of the base film.

[0245] In the tenth aspect, an embodiment of the present application provides a battery separator, including:

[0246] a ceramic-coated film; and

[0247] a coating containing the coating slurry provided in the embodiment of the eighth aspect, and the coating is located on at least one surface of the ceramic-coated film.

[0248] In the eleventh aspect, an embodiment of the present application provides an application of the battery separator provided in the ninth or tenth aspect in a secondary battery. The features and performance of the present application will be further described in detail below in conjunction with embodiments.

[0249] It should be noted that the parts in the following examples and comparative examples are all parts by weight.

[0250] Example 1

[0251] An embodiment of the present application provides a method for preparing a binder, including the following steps:

[0252] Dissolve 0.5 parts of sodium dodecyl sulfonate in 700 parts of water and stir and mix at a temperature of 60 °C to obtain a first reaction solution; dissolve 30 parts of methacrylamide, 20 parts of acrylonitrile and 3 parts of ammonium persulfate in 100 parts of water and stir and mix to obtain a second reaction solution; stir and mix 200 parts of styrene, 10 parts of methacryloxypropyltrimethoxysilane and 2 parts of dimethylpyridineamine to obtain a third reaction solution; mix the second reaction solution and the third reaction solution and then drop them into the first reaction solution and stir and mix to obtain a mixed solution, wherein the dropping time is 3 h; react the mixed solution at a temperature of 60 °C for 7 h to obtain a precursor solution, wherein the Dv50 of the primary particles in the precursor solution is 100 nm; add 2 parts of chitosan to the precursor solution and stir and mix to obtain a solution containing a binder, wherein the Dv50 of the binder (i.e., the secondary particles) is 6 μm; dry the solution containing the binder to obtain a binder powder.

[0253] Example 2

[0254] The difference from Example 1 is only that: crown ether is used to replace dimethylpyridineamine.

[0255] Example 3

[0256] The difference from Example 1 is only that: 1 part of dimethylpyridineamine and 1 part of 18-crown-6 are used together to replace 2 parts of dimethylpyridineamine in Example 1.

[0257] Example 4

[0258] Dissolve 0.5 parts of sodium dodecyl sulfonate in 700 parts of water and stir and mix at a temperature of 60 °C to obtain a first reaction solution; dissolve 30 parts of methacrylamide, 20 parts of acrylonitrile and 3 parts of ammonium persulfate in 100 parts of water and stir and mix to obtain a second reaction solution; stir and mix 200 parts of styrene, 10 parts of methacryloxypropyltrimethoxysilane and 2 parts of dimethylpyridineamine to obtain a third reaction solution; mix the second reaction solution and the third reaction solution and then drop them into the first reaction solution and stir and mix to obtain a mixed solution, wherein the dropping time is 3 h; react the mixed solution at a temperature of 60 °C for 7 h, and dry to obtain a binder powder.

[0259] Example 5

[0260] The difference from Example 1 is only that: itaconic acid is used to replace methacrylamide.

[0261] Example 6

[0262] The difference from Example 1 is only that: maleic anhydride is used to replace methacrylamide.

[0263] Example 7

[0264] The difference from Example 6 is only that: dimethylimidazole is used to replace dimethylpyridineamine.

[0265] Example 8

[0266] The difference from Example 6 is only that: cyclodextrin is used to replace chitosan.

[0267] Example 9

[0268] The difference from Example 7 is only that: 1 part of dimethylimidazole and 1 part of 18-crown-6 are used together to replace 2 parts of dimethylimidazole in Example 7.

[0269] Example 10

[0270] Dissolve 2 parts of sodium dodecyl sulfate in 750 parts of water, and stir and mix at a temperature of 60 °C to obtain a first reaction solution; dissolve 30 parts of acrylic acid and 2 parts of ammonium persulfate in 50 parts of water and stir and mix to obtain a second reaction solution; stir and mix 200 parts of styrene and 10 parts of methacryloxypropyltrimethoxysilane to obtain a third reaction solution; mix the second reaction solution and the third reaction solution and then drop them into the first reaction solution and stir and mix to obtain a mixed solution, wherein the dropping time is 4 h; react the mixed solution at a temperature of 60 °C for 6 h to obtain a precursor solution, and dry the precursor solution to obtain a binder powder.

[0271] Example 11

[0272] Dissolve 2 parts of sodium dodecyl sulfate in 750 parts of water, and stir and mix at a temperature of 60 °C to obtain a first reaction solution; dissolve 30 parts of acrylic acid and 2 parts of ammonium persulfate in 50 parts of water and stir and mix to obtain a second reaction solution; stir and mix 200 parts of styrene and 2 parts of dimethylpyridineamine to obtain a third reaction solution; mix the second reaction solution and the third reaction solution and then drop them into the first reaction solution and stir and mix to obtain a mixed solution, wherein the dropping time is 4 h; react the mixed solution at a temperature of 60 °C for 6 h to obtain a precursor solution, and dry the precursor solution to obtain a binder powder.

[0273] Comparative Example 1

[0274] A method for preparing a binder, comprising the following steps:

[0275] Dissolve 2 parts of sodium dodecyl sulfonate in 750 parts of water and stir and mix at a temperature of 60 °C to obtain a first reaction solution; dissolve 30 parts of acrylic acid and 2 parts of ammonium persulfate in 50 parts of water and stir and mix to obtain a second reaction solution; stir and mix 200 parts of styrene to obtain a third reaction solution; mix the second reaction solution and the third reaction solution and then drop them into the first reaction solution and stir and mix to obtain a mixed solution, wherein the dropping time is 4 h; react the mixed solution at a temperature of 60 °C for 6 h to obtain a precursor solution, wherein the Dv50 of the primary particles in the precursor solution is 120 nm; dry the precursor solution to obtain a binder powder.

[0276] It should be noted that in Comparative Example 1, no functional monomer and first chelating agent were added, and no flocculant was added, so the prepared binder was a conventional binder, that is, it did not have the first functional unit and the second functional unit, and existed in the form of primary particles with a nanoscale size.

[0277] Test Example 1

[0278] Morphology test of the binder:

[0279] Test method:

[0280] Prepare the binder powder prepared in Example 1 into a solution, and then use a SEM device to characterize the morphology of the binder powder at low magnification and high magnification, respectively.

[0281] Refer to Figure 1 and Figure 2 It can be seen that the size of the binder powder is in the micron level.

[0282] Test Example 2

[0283] Particle size test of the binder

[0284] Test method:

[0285] Prepare the primary particles in the precursor solution during the preparation process of each example and Comparative Example 1 and the powder of the prepared binder into solutions, and then use a DLS device to test the DLS particle sizes of both, and the results are shown in Table 2.

[0286] Figure 3 It is the DLS result diagram before and after the agglomeration of the primary particles. Refer to Figure 3 It can be seen that before the addition of the flocculant, the binder existed in the form of small particles with a nanoscale size, and after the addition of the flocculant, the binder agglomerated into large particles with a micron scale, which matched the TEM results in Test Example 1.

[0287] Test Example 4

[0288] HF removal effect test:

[0289] Test method:

[0290] The binder powders prepared in each example and Comparative Example 1 were respectively made into slurries, and then the corresponding slurries were coated on a base film to prepare diaphragms. Then, the diaphragms were assembled into pocket batteries, and 400 ppm of water was added thereto. Using a titration method, the initial content of HF therein was tested. Then, the battery was left for 1 day, a certain amount of electrolyte was taken, and the content of HF in the electrolyte was tested again.

[0291] Among them, the HF removal rate (R HF ) = (C1 - C0) / C1: C1 is the HF concentration in the electrolyte before soaking the composite diaphragm, and C0 is the HF concentration in the electrolyte after soaking the composite diaphragm.

[0292] The preparation steps of the diaphragm are as follows:

[0293] 0.6 parts of water, 0.5 parts of sodium polyacrylate dispersant, 0.55 parts of carboxymethyl cellulose thickener, 0.05 parts of polyacrylic acid binder, and 0.48 parts of binder powder were vigorously stirred on a dispersion pan stirrer for 120 minutes, then 8.14 parts of water were added, and stirring was continued for 30 minutes. Then 0.06 parts of wetting agent and 0.14 parts of acrylic emulsion binder were added, and stirring was carried out at low speed for 60 minutes to obtain a slurry; then, the obtained slurry was coated on both sides of a SV9B22 diaphragm (from Shanghai Enjie Co., Ltd., with 2 μm of boehmite double-sidedly coated on a 9 μm wet diaphragm) by means of gravure roll coating, and the thickness was controlled at 1 μm to obtain a diaphragm.

[0294] The assembly process of the battery is as follows:

[0295] The obtained diaphragm was assembled with a positive electrode (NCM532), a negative electrode (graphite), an electrolyte (1 mol / L LiPF6 in EC:EMC:DMC = (1:1:1)), and an aluminum-plastic film into a pocket battery.

[0296] The test results are shown in Table 2.

[0297] Among them, Figure 4 is the HF removal effect diagram of the binders provided in Example 1 and Comparative Example 1. Refer to Figure 4 It can be seen that the binder prepared in Example 1 of the present application can significantly reduce the content of HF acid in the electrolyte compared with the binder prepared in Comparative Example 1 (i.e., a conventional binder).

[0298] Test Example 5

[0299] Test on the removal effect of transition metal ions:

[0300] Test method:

[0301] The difference from Test Example 4 is only that: Mn 2+ The content before and after immersion is directly detected by an ICP-OES device. The results are shown in Table 2.

[0302] Figure 5 The removal effect diagram of transition metal ions of the binder provided in Example 1 and Comparative Example 1 of the present application is shown in Figure 5 As can be seen, compared with the binder prepared in Comparative Example 1 (i.e., the conventional binder), the binder prepared in Example 1 of the present application can significantly reduce the content of Mn 2+ in the electrolyte.

[0303] Test Example 6

[0304] Adhesion test of the binder:

[0305] Test method:

[0306] The difference from Test Example 4 is only that: the bonding strength between the electrode sheet and the separator is measured by the hot pressing method (hot pressing temperature = 60 °C, pressure 3.5 Mpa). Specifically: the test method for the bonding strength between the battery separator and the electrode sheet is as follows: The negative electrode sheet of 85×140 mm and the battery separator are hot pressed at a temperature of 60 °C under a pressure of 3.5 MPa for 60 s. After cutting it into a spline of 30×140 mm, it is tested on a universal tensile testing machine at a tensile rate of 300 mm / min, and the obtained data is the adhesion between the separator and the negative electrode sheet.

[0307] Among them, Figure 6 The adhesion test result diagram of the binder provided in Example 1 and Comparative Example 1 of the present application is shown in Figure 6 As can be seen, compared with the binder prepared in Comparative Example 1 (i.e., the conventional binder), the binder prepared in Example 1 of the present application has a greater adhesion.

[0308] Each test selects the separators prepared in different batches of the same example or comparative example and repeats them three times, and the average result is used as the adhesion test result. The test results obtained are shown in Table 2. Among them, the test method for specific surface area is the BET test method after nitrogen adsorption.

[0309] Table 2 Test results

[0310]

[0311] As can be seen from Examples 1, 2, and 3, both the crown ether added alone and the dimethylpyridineamine added alone can cooperate with methacryloxypropyltrimethoxysilane to prepare a binder with good adhesion, HF removal rate, and transition metal removal rate. However, when the two cooperate with each other and act synergistically, the transition metal removal rate can be significantly improved.

[0312] As can be seen from Example 1 and Example 4, in Example 4, due to the absence of chitosan, it is basically impossible to form secondary particles, the adhesion force becomes significantly worse, and the transition metal removal rate also decreases. This shows that the addition of chitosan helps to form secondary particles, and the formation of secondary particles can improve the adhesion force. The addition of chitosan can also improve the transition metal removal rate.

[0313] As can be seen from Examples 1, 5, and 6, the selection of the second monomer not only affects the morphology and particle size of the binder, but also affects the HF removal rate and transition metal removal rate of the finally obtained product.

[0314] As can be seen from Examples 7 and 8, when the flocculant is chitosan or cyclodextrin, a binder with good adhesion, HF removal rate, and transition metal removal rate can be prepared. Among them, the improvement effect of chitosan on the binder is better than that of cyclodextrin.

[0315] As can be seen from Examples 7 and 9, the compounding effect of dimethylimidazole and crown ether is better than that of dimethylimidazole alone, and the performance of the binder can be effectively improved.

[0316] As can be seen from Example 10, methacryloxypropyltrimethoxysilane has a good HF removal rate. As can be seen from Example 11, dimethylpyridineamine has a good transition metal removal rate.

[0317] The above-described embodiments are some embodiments of the present application, rather than all embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application claimed, but merely represents the selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.

Claims

1. An adhesive, characterized in that, It includes a first functional unit and a second functional unit. The first functional unit is used to react with HF, and the second functional unit is used to adsorb transition metal ions. Among them, the first functional unit includes substituents with siloxane bonds and / or substituents with silicon-nitrogen bonds, and the second functional unit includes pyridine-based substituents and / or crown ether-based substituents.

2. The binder according to claim 1, characterized in that, The first functional unit with substituents having siloxane bonds includes organosilicon olefins.

3. The binder according to claim 1, characterized in that, The second functional unit includes one or more of pyridine-based substituents, imidazole-based substituents, and crown ether-based substituents.

4. The binder according to claim 1, characterized in that, The binder includes a flocculant, and the flocculant includes one or more of polyacrylamide, chitosan, and cyclodextrin.

5. The binder according to any one of claims 1 to 4, characterized in that, The monomers of the binder include one or more of acrylate esters, acrylic acids, acrylonitrile, vinyl acetate, styrene-based compounds, vinyl fluoride, vinylidene fluoride, hexafluoropropene, and tetrafluoroethylene.

6. The binder according to claim 5, characterized in that, The monomers of the binder further include at least one of carboxylic acid olefins and amide olefins.

7. The binder according to any one of claims 1 to 4, characterized in that, The binder includes secondary particles.

8. The binder according to claim 7, characterized in that, The Dv of the secondary particles in the binder 50 is 3 to 50 μm.

9. The binder according to claim 7, characterized in that, The Dv of the secondary particles in the binder 50 is 5 to 40 μm.

10. The binder according to claim 7, wherein, The Dv of the secondary particles in the binder 50 is 10 to 30 μm.

11. The binder according to claim 8, characterized in that, The specific surface area of the secondary particles in the binder is 30 to 300 m 2 / g.

12. The binder according to claim 8, characterized in that, The specific surface area of the secondary particles in the binder is 50 to 300 m 2 / g.

13. The binder according to claim 8, characterized in that, The specific surface area of the secondary particles in the binder is 80 to 300 m 2 / g.

14. The binder according to any one of claims 1 to 4, characterized in that, The ash content of the binder accounts for 0 to 10% of the weight of the binder.

15. The binder according to any one of claims 1 to 4, characterized in that, The ash content of the binder accounts for 0 to 5% of the weight of the binder.

16. The binder according to any one of claims 1 to 4, characterized in that, The first functional unit accounts for 1 to 20 wt% of the weight of the binder, and the ash content of the binder accounts for 0.25 to 5 wt% of the weight of the binder.

17. A method for preparing a binder according to any one of claims 1 to 16, characterized in that, It includes the following steps: Dissolve the emulsifier in water and mix at a preset temperature to obtain a first reaction solution. Dissolve the initiator in water and mix to obtain a second reaction solution. Mix the first monomer, the functional monomer, and the first chelating agent to obtain a third reaction solution, where the functional monomer is used to provide the first functional unit, and the first chelating agent is used to provide the second functional unit. Mix the second reaction solution and the third reaction solution, then add them to the first reaction solution and mix to obtain a mixed solution. React the mixed solution at a preset temperature to obtain a precursor solution. Add a flocculant to the precursor solution and mix to obtain a solution containing the binder.

18. According to the preparation method described in claim 17, wherein The first monomer includes one or more of acrylate esters, styrene-based compounds, tetrafluoroethylene, and vinylidene fluoride; and / or The functional monomer includes organosilicon olefins; and / or The first chelating agent includes one or more of polyamine-based chelating agents and cyclic chelating agents.

19. The preparation method according to claim 17, characterized in that, By weight, the weight ratio of the first monomer, the functional monomer, and the first chelating agent is (100 to 300):(0.1 to 50):(0.1 to 50) in sequence.

20. The preparation method according to claim 17, wherein, The weight ratio of the flocculant to the first monomer is (1 to 5):(100 to 300).

21. The preparation method according to claim 17, characterized in that, The flocculant includes one or more of polyacrylamide, chitosan, and cyclodextrin.

22. The preparation method according to claim 17, characterized in that, In the step of preparing the second reaction solution, it further includes: adding a second monomer and a second chelating agent to the mixture of the initiator and water, where the second monomer includes one or more of carboxylic acid olefins and amide olefins, and the second chelating agent includes amino carboxylic acid-based chelating agents.

23. The preparation method according to claim 22, characterized in that, In parts by weight, the weight ratio of the second monomer, the second chelating agent, and water in the second reaction solution is successively (10 to 200):(0.1 to 50):(100 to 300).

24. A coating slurry, characterized in that, Containing the binder according to any one of claims 1 to 16.

25. The coating slurry according to claim 24, wherein The coating slurry further includes at least one inorganic material.

26. The coating slurry according to claim 25, characterized in that, The inorganic material includes one or more of alumina, boehmite, silica, titanium oxide, cerium oxide, calcium oxide, zinc oxide, magnesium oxide, lithium nitride, calcium carbonate, barium sulfate, lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, cerium titanate, calcium titanate, barium titanate, and lithium lanthanum titanate.

27. A battery separator, characterized in that, Comprising: A base film; And A coating containing the coating slurry according to any one of claims 24 to 26, the coating being located on at least one surface of the base film.

28. A battery separator, characterized in that, Comprising: A ceramic coated film; And A coating containing the coating slurry according to any one of claims 24 to 26, the coating being located on at least one surface of the ceramic coated film.

29. The battery separator according to claim 27 or 28, characterized in that, The adhesion of the battery separator is 5 to 50 N / m; Or, the adhesion of the battery separator is 10 to 50 N / m; Or, the adhesion of the battery separator is 20 to 50 N / m.

30. Use of a battery separator according to any one of claims 27 to 29 in a secondary battery.

31. The application according to claim 30, characterized in that, Satisfying A and / or B among the following conditions: A. The HF removal rate of the binder in the secondary battery is 0 to 90%; Or, the HF removal rate of the binder in the secondary battery is 30 to 90%; Or, the HF removal rate of the binder in the secondary battery is 50 to 90%; B. The transition metal ion removal rate of the binder in the secondary battery is 0 to 90%; Or, the transition metal ion removal rate of the binder in the secondary battery is 30 to 90%; Or, the transition metal ion removal rate of the binder in the secondary battery is 50 to 90%.

32. The application according to claim 30, wherein, The secondary battery includes one or more of a lithium ion secondary battery and a sodium ion secondary battery.

33. An additive, characterized in that, Including a first functional unit and a second functional unit, the first functional unit is used to react with HF, and the second functional unit is used to adsorb transition metal ions, wherein the first functional unit includes a substituent having a silicon-oxygen bond and / or a substituent having a silicon-nitrogen bond, and the second functional unit includes a pyridine-based substituent and / or a crown ether-based substituent.

34. A coating slurry, characterized in that, Containing the additive according to claim 33.

35. A battery separator, characterized in that, Comprising: A base film; And A coating containing the coating slurry according to claim 34, the coating being located on at least one surface of the base film.

36. A battery separator, characterized in that, Comprising: A ceramic coated film; And A coating containing the coating slurry according to claim 34, the coating being located on at least one surface of the ceramic coated film.

37. Use of a battery separator according to claim 35 or 36 in a secondary battery.

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