Binder, manufacturing method, secondary battery, battery module, battery pack, and power consumption device

Abstract

The present application provides an adhesive, a manufacturing method, a secondary battery, a battery module, a battery pack, and a power consuming device. The adhesive is a polymer containing structural units shown in Formula I and Formula II, JPEG2024526517000015.jpg40139 where R1, R2, R3, R5, R6, and R7 are each independently hydrogen or C substituted or unsubstituted by a substituent. 1-3 R4 is selected from hydrogen, a cyano group, an aldehyde group or an ester group, and M is selected from H, Li, Na, K or NH4. The adhesive of the present application has good swelling resistance, and the cycle performance and power performance of the corresponding secondary battery are significantly improved.

Description

[Technical field]

[0001] The present application relates to the field of lithium battery technology, and in particular to an adhesive, a manufacturing method, a secondary battery, a battery module, a battery pack and a power consuming device. [Background technology]

[0002] In recent years, lithium-ion batteries have been widely applied in energy storage power systems such as hydroelectric, thermal, wind and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the widespread use of lithium-ion batteries, the requirements for their cycle performance, service life, etc. are increasing.

[0003] Adhesives are commonly used materials in lithium-ion batteries and are in high demand in battery plates, separators, packaging parts, etc. However, traditional adhesives have poor adhesion, which leads to a significant decrease in performance during battery use and further affects the service life of the battery. Therefore, traditional adhesives still need to be improved. Summary of the Invention

[0004] The present application has been made in view of the above problems, and an object of the application is to provide an adhesive for improving battery performance by reducing swelling of the adhesive in an electrolyte, and an electrode including the adhesive.

[0005] According to a first aspect of the present application, there is provided an adhesive, the adhesive being a polymer containing structural units as shown in Formula I and Formula II, JPEG2024526517000002.jpg37136 where R1, R2, R3, R5, R6, and R7 are each independently hydrogen or C substituted or unsubstituted by a substituent. 1-3 R4 is selected from hydrogen, a cyano group, an aldehyde group or an ester group; and M is selected from H, Li, Na, K or NH4.

[0006] Thus, the present application provides a polymer containing -COOM groups, i.e., carboxylic acid or carboxylate groups, which can improve the polarity of the polymer and reduce the absorption of the solvent in the electrolyte by the adhesive, and further reduce the swelling rate of the electrode, reduce the DC resistance of the battery, and improve the power performance and cycle performance of the battery. At the same time, the carboxylic acid or carboxylate groups have high chemical stability and oxidation stability in the electrolyte. In addition, the Li generated after ionization of the carboxylate salt present in the polymer can be easily dissolved by the ionization of the carboxylate salt. + , Na + Such metal cations can increase the content of dissociated ions in the battery electrolyte, promote the transport of charge carriers, and improve the dynamic performance of the battery.

[0007] In any embodiment, the molar content of the structural unit shown in formula II is 0.1% to 60%, or 10% to 40%, based on the total molar number of all structural units in the polymer. By controlling the ratio of the structural unit shown in formula II, the adhesive can be made to have both solubility in an oil-based solvent and absorptivity for an electrolyte, and the DC resistance of the battery can be reduced, and the power performance and cycle performance of the battery can be improved.

[0008] In an optional embodiment, the polymer comprises a first structural unit according to formula I, where R4 is an aldehyde group or an ester group, and a second structural unit according to formula I, where R4 is hydrogen or a cyano group, and the first structural unit and the second structural unit are different. The combination of the first structural unit and the second structural unit provides the polymer with a certain strength, as well as ductility and adhesiveness, and reduces the absorption of electrolyte by the adhesive, thereby improving the swelling resistance of the electrode.

[0009] In any embodiment, the molar content of the second structural unit is 20%-90%, optionally 50%-80%, based on the total molar number of all structural units in the polymer. By controlling the ratio of the second structural unit in the polymer, the adhesion of the polymer can be improved and the absorption of the electrolyte by the polymer can be reduced.

[0010] According to a second aspect of the present application, there is provided a method for producing an adhesive, the method comprising the steps of: preparing an intermediate polymer, comprising polymerizing a monomer according to formula III to form an intermediate polymer containing at least a cyano group, an aldehyde group, or an ester group; JPEG2024526517000003.jpg3878 In formula III, R1, R2, and R3 are each independently hydrogen, substituted or unsubstituted C 1-3 alkyl group, and R4 is selected from hydrogen, a cyano group, an aldehyde group, or an ester group; and a modification reaction step of subjecting the intermediate polymer to a modification reaction with an aqueous solution of an alkaline substance to convert at least a portion of the cyano groups, aldehyde groups or ester groups in the intermediate polymer to COOM, where M is selected from H, Li, Na, K or NH4.

[0011] The method has a simple manufacturing process, abundant raw materials, and low cost. Cyano groups, aldehyde groups, and ester groups are hydrolyzed under alkaline conditions to convert some or all of them into carboxylic acids or carboxylate groups, thereby improving the polarity of the polymer, reducing the absorption of electrolytes by the adhesive, especially polyester electrolytes, and improving the chemical and oxidative stability of the adhesive. In addition, the Li generated after ionization of the carboxylate salts present in the polymer can be used as a catalyst. + , Na + Such metal cations can increase the content of dissociated ions in the battery electrolyte, promote the transport of charge carriers, and improve the dynamic performance of the battery.

[0012] In an optional embodiment, in the step of preparing the intermediate polymer, the monomers are selected from a first monomer as shown in formula III, in which R4 is a cyano group, an aldehyde group, or an ester group, and a second monomer as shown in formula III, in which R4 is hydrogen or a cyano group, and the second monomer and the first monomer are different in structure.

[0013] In an optional embodiment, the first monomer is selected from one or more of acrolein, acrylonitrile, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate.

[0014] In an optional embodiment, the second monomer is selected from one or more of ethylene, propylene, butene, and acrylonitrile.

[0015] In any embodiment, the molar ratio of the second monomer to the first monomer is 2:8 to 9:1, optionally 3:7 to 8:2, and further optionally 5:5 to 8:2. By controlling the ratio of the second monomer to the first monomer within an appropriate range, it is possible to achieve a balance between the liquid absorption property, flexibility, and processability of the adhesive.

[0016] In an optional embodiment, the weight average molecular weight of the intermediate polymer is 5×10 4 ~1.5×10 6 and optionally 1.5×10 5 ~8×10 5 The processing performance of the intermediate polymer can be adjusted by controlling the weight average molecular weight of the intermediate polymer. If the molecular weight is too low, the intermediate polymer will be brittle and have insufficient adhesive strength, but if the molecular weight is too high, the intermediate polymer will be prone to gelation, and the modified product will be prone to solidification and difficult to extract.

[0017] In any embodiment, the alkaline material is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, and aqueous ammonia. The above materials are simple, readily available, and low in cost, which is favorable for popularization and application.

[0018] In any embodiment, the molar ratio of the total amount of the functional groups of the cyano group, the aldehyde group, and the ester group in the first monomer to the alkaline substance is 1:0.1 to 1:2, or 1:0.5 to 1:1.5. By controlling the molar ratio of the total amount of the functional groups of the cyano group, the aldehyde group, and the ester group in the first monomer to the alkaline substance within an appropriate range, the hydrolysis degree of the functional groups can be controlled, and the intermediate polymer can be guaranteed to have low absorption in the electrolyte and high solubility in the oil-based solvent, while achieving both the use performance and processing performance of the electrode plate.

[0019] In any embodiment, the reaction temperature of the reforming reaction is 35° C. to 120° C., and optionally 60° C. to 90° C. By controlling the reaction temperature within an appropriate range, the degree of hydrolysis of the functional group can be controlled, and the intermediate polymer can be guaranteed to have low absorption in the electrolyte and high solubility in the oil-based solvent, while achieving both the use performance and processing performance of the electrode plate.

[0020] In any embodiment, the reaction time of the modification reaction is 1 to 24 hours, and optionally 4 to 10 hours. By controlling the reaction time within an appropriate range, the hydrolysis degree of the functional group can be controlled, and the intermediate polymer can be guaranteed to have low absorption in the electrolyte and high solubility in the oil-based solvent, while achieving both the use performance and processing performance of the electrode plate.

[0021] In an optional embodiment, the method further includes, after the modification reaction is completed, adding an acidic solution to the reaction product to adjust the pH of the reaction system to 6 to 8. By adjusting the pH of the reaction system to be weakly acidic or neutral, gelation of the slurry caused by the adhesive in the manufacturing process of the electrode slurry can be prevented, and the stability of the slurry can be improved.

[0022] According to a third aspect of the present application, there is provided a secondary battery, the secondary battery comprising an electrode assembly and an electrolyte, the electrode assembly comprising a positive electrode plate, a separator, and a negative electrode plate, the positive electrode plate comprising a positive electrode active material and the adhesive according to the first or second aspect of the present application, the positive electrode plate having a low swelling rate in the electrolyte, which can reduce the internal resistance of the battery and improve the power performance and cycle performance of the battery.

[0023] According to a fourth aspect of the present application, there is provided a battery module, the battery module including the secondary battery according to the third aspect of the present application, the battery having reduced internal resistance and improved power performance and cycle performance.

[0024] According to a fifth aspect of the present application, there is provided a battery pack, the battery pack including the battery module of the fourth aspect of the present application.

[0025] According to a sixth aspect of the present application, there is provided a power consumption device, the power consumption device including at least one of the secondary battery of the third aspect of the present application, the battery module of the fourth aspect of the present application, and the battery pack of the fifth aspect of the present application.

[0026] The battery module of the fourth embodiment and the battery pack of the fifth embodiment of the present application include the secondary battery of the third embodiment, and therefore have the same advantages as the secondary battery. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application. [Diagram 2] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. [Diagram 3] FIG. 1 is a schematic diagram of a battery module according to an embodiment of the present application. [Figure 4] FIG. 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Diagram 5] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application. [Figure 6]1 is a schematic diagram of a power consuming device in which a secondary battery according to an embodiment of the present application is used as a power source; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the adhesive, manufacturing method, electrode, battery, and power consumption device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and duplicated description of structures that are actually the same may be omitted. This is to avoid the following description becoming unnecessarily long and to allow those skilled in the art to easily understand. Note that the drawings and the following description are provided to allow those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0029] The "ranges" disclosed in this application are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the end values, and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also envisaged. It is noted that if 1 and 2 are listed as the minimum range values, and 3, 4, and 5 are listed as the maximum range values, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all envisaged. In this application, unless otherwise specified, a numerical range "a-b" represents a shorthand representation of any combination of real numbers a-b, where a and b are both real numbers. For example, the numerical range "0-5" represents a list of all real numbers between "0-5" already listed in this specification, and "0-5" is only a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0030] Unless otherwise stated, all the embodiments and optional embodiments in the present application can be combined with each other to form a new technical solution.

[0031] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0032] Unless otherwise stated, all steps in this application may be performed in sequence, randomly, and preferably in sequence. For example, a method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), etc.

[0033] Unless otherwise stated, the terms "comprise" and "comprises" referred to in this application may be open ended or closed ended. For example, "comprise" and "comprises" may further include or include other ingredients not listed, or may include or include only the listed ingredients.

[0034] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied in the following cases: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) but B is true (or exists); and A and B are both true (or exist).

[0035] As the cost of PVDF raw materials increases, ester-containing non-fluorinated adhesives with good flexibility are increasingly used in the manufacturing process of electrodes. However, this ester-containing adhesive absorbs electrolyte by itself, which significantly increases the swelling degree of the electrodes in the electrolyte, and further causes a significant decrease in the cycle performance and power performance of the battery. Based on the above technical problems, the present application develops an adhesive that provides electrodes with good swelling resistance, and significantly improves the power performance and cycle performance of the battery. [glue]

[0036] Based on this, the present application provides an adhesive, which is a polymer containing structural units as shown in formula I and formula II, JPEG2024526517000004.jpg38132 where R1, R2, R3, R5, R6, and R7 are each independently hydrogen or C substituted or unsubstituted by a substituent. 1-3 R4 is selected from hydrogen, a cyano group, an aldehyde group or an ester group; and M is selected from H, Li, Na, K or NH4.

[0037] As used herein, the term "adhesive" refers to a chemical compound, polymer, or mixture that forms a colloidal solution or dispersion in a dispersing medium.

[0038] In some embodiments, the adhesive dispersion medium is an aqueous solvent, such as water. In some embodiments, the adhesive dispersion medium is an oil-based solvent, examples of which include, but are not limited to, dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, acetone, dimethyl carbonate, ethyl cellulose, and polycarbonate.

[0039] In some embodiments, an adhesive is used to hold the electrode materials and / or conductive agents in place and adhere them to the conductive metal members to form the electrodes.

[0040] In some embodiments, the adhesive is used as a positive electrode adhesive to adhere a positive electrode active material and / or a conductive agent to form an electrode.

[0041] In some embodiments, the adhesive is used as a negative electrode adhesive to adhere the negative electrode active material and / or conductive agent to form an electrode.

[0042] As used herein, the term "polymer" includes chemically homogeneous macromolecular assemblies produced by polymerization reactions (copolymerization, homopolymerization), but differing in degree of polymerization, molar mass and chain length, while the term also includes derivatives of such macromolecular assemblies formed by polymerization reactions, i.e. those obtained by reactions, e.g. addition or substitution, of functional groups on said macromolecules, and may be chemically homogeneous or chemically heterogeneous compounds.

[0043] In this specification, the term “C 1-3 "Alkyl" refers to a linear or branched chain hydrocarbon group consisting solely of carbon and hydrogen atoms, the group being free of unsaturation, having from 1 to 3 carbon atoms and connected to the rest of the molecule through a single bond. 1-5 "Alkyl group" should be construed accordingly. 1-3 Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, and 1-methylethyl (isopropyl) groups.

[0044] As used herein, the term "cyano" refers to a -CN group.

[0045] As used herein, the term "aldehyde group" refers to a -CHO group.

[0046] As used herein, the term "ester group" refers to a group of structural units having the general formula -COOR9, where R9 is a C 1-5 Examples of ester groups are selected from alkyl groups, including, but not limited to, methyl, ethyl, propyl, butyl, pentyl, isooctyl, and the like.

[0047] As used herein, the term "substituted" means substituted with a substituent, where each of the substituents is independently a hydroxy group, a mercapto group, an amino group, a cyano group, a nitro group, an aldehyde group, a halogen atom, a C 1-6 Alkyl group, C 1-6 The alkoxy group is selected from the group consisting of aryl, ... and aryl groups.

[0048] As used herein, the term "swelling" refers to the phenomenon in which a polymer absorbs a solvent and expands in volume both of itself and the electrode in which it is located.

[0049] In the present application, by incorporating a -COOM group, i.e., a carboxylic acid or a carboxylate group, into the polymer, the polarity of the polymer can be improved, the absorption of the solvent in the electrolyte by the adhesive can be reduced, and the swelling rate of the electrode can be reduced, the DC resistance of the battery can be reduced, and the power performance and cycle performance of the battery can be improved. At the same time, the carboxylic acid or the carboxylate group has high chemical stability and oxidation stability in the electrolyte. In addition, the Li generated after ionization of the carboxylate salt present in the polymer can be easily dissolved. + , Na + Such metal cations can increase the content of dissociated ions in the battery electrolyte, promote the transport of charge carriers, and improve the dynamic performance of the battery.

[0050] In some embodiments, based on the total moles of all structural units in the polymer, the molar content of the structural units shown in formula II is 0.1% to 60%, or 10% to 40%. In some embodiments, based on the total moles of all structural units in the polymer, the molar content of the structural units shown in formula II is 1% to 60%, or 2% to 60%, or 5% to 60%, or 8% to 60%, or 10% to 60%, or 0.1% to 70%, or 0.1% to 60%, or 0.1% to 50%, or 2% to 40%, or 2% to 30%, or 5% to 50%, or 5% to 40%, or 5% to 30%, or 5% to 20%, or 10% to 40%, or 10% to 30%.

[0051] If the ratio of the structural unit shown in formula II is too high, the polarity of the polymer becomes too large, making it difficult to dissolve in an oil-based solvent and form into an electrode, especially a positive electrode. If the ratio of the structural unit shown in formula II is too low, the polymer is prone to absorbing the electrolyte, resulting in a decrease in the cycle performance and power performance of the battery. By controlling the ratio of the structural unit shown in formula II, it is possible to achieve both the solubility of the adhesive in the oil-based solvent and the absorption rate of the electrolyte, and further reduce the DC resistance of the battery, thereby improving the power performance and cycle performance of the battery.

[0052] In some embodiments, the polymer comprises a first structural unit as shown in formula I, where R4 is an aldehyde group or an ester group, and a second structural unit as shown in formula I, where R4 is hydrogen or a cyano group, wherein the first structural unit and the second structural unit are different.

[0053] In some embodiments, the polymer comprises a first structural unit in which R4 is an aldehyde group or an ester group, and a second structural unit in which R4 is hydrogen.

[0054] The second structural unit, in which R4 is hydrogen or a cyano group, provides a hard segment for the polymer, which can provide the polymer with a certain crystallinity, which can provide mechanical strength for the adhesive and reduce the absorption of electrolyte by the adhesive, and in combination with the first structural unit containing an ester group or an aldehyde group, which can provide a soft segment for the polymer and provide ductility to the polymer. Thus, the combination of the first structural unit and the second structural unit provides the polymer with a certain strength, ductility, adhesiveness, and reduced absorption of electrolyte by the adhesive, thereby increasing the swelling resistance of the electrode.

[0055] In some embodiments, based on the total number of moles of all structural units in the polymer, the molar content of the second structural unit is 20% to 90%, or 50% to 80%. In some embodiments, based on the total number of moles of all structural units in the polymer, the molar content of the second structural unit is 20% to 85%, or 20% to 80%, or 30% to 90%, or 30% to 85%, or 30% to 80%, or 40% to 90%, or 40% to 85%, or 40% to 80%, or 45% to 90%, or 45% to 85%, or 45% to 80%, or 55% to 80%, or 60% to 80%.

[0056] If the ratio of the second structural unit in the polymer is too high, the rigidity of the polymer increases, the adhesiveness decreases, and it becomes difficult to exert the adhesive effect, and if the ratio of the first structural unit in the polymer is too high, the absorption of the electrolyte by the polymer increases, and the swelling resistance of the electrode and the power performance and cycle performance of the battery decrease. By controlling the ratio of the second structural unit in the polymer, it is possible to improve the adhesiveness of the polymer and reduce the absorption of the electrolyte by the polymer.

[0057] In some embodiments, the weight average molecular weight of the polymer is 5×10 4 ~1.5×10 6 or 1.5 × 10 5 ~8×10 5 In some embodiments, the weight average molecular weight of the polymer is 2×10 5 ~8×10 5 or 2 × 10 5 ~7×10 5 , or 3 × 10 5 ~7×10 5 , or 2 × 10 5 ~6×10 5 It is.

[0058] As used herein, the term "weight average molecular weight" refers to the statistical average molecular weight of the average weight of molecules of different molecular weights in a polymer.

[0059] By controlling the weight-average molecular weight of the polymer, it is possible to ensure the viscosity of the polymer and the rational combination of segments with different molecular weights, thereby enhancing the dynamic conditions of the electrode and further improving the battery performance.

[0060] In one embodiment of the present application, there is provided a method for producing an adhesive, the method comprising: Preparation of an intermediate polymer: polymerizing a monomer according to formula III to form an intermediate polymer containing at least a cyano group, an aldehyde group, or an ester group, JPEG2024526517000005.jpg3767 In formula III, R1, R2, and R3 are each independently hydrogen, substituted or unsubstituted C 1-3 alkyl group, and R4 is selected from hydrogen, a cyano group, an aldehyde group, or an ester group; Modification reaction: modifying the intermediate polymer with an aqueous solution of an alkaline substance to convert at least a portion of the cyano, aldehyde or ester groups in the intermediate polymer to COOM, where M is selected from H, Li, Na, K or NH4.

[0061] As can be seen, the modification reaction does not significantly affect the weight average molecular weight of the intermediate polymer, and the difference between the weight average molecular weight of the adhesive in this application and the weight average molecular weight of its corresponding intermediate polymer is less than 1000.

[0062] In some embodiments, the intermediate polymer is the homopolymerization of one type of monomer. In some embodiments, the intermediate polymer is the copolymerization of two or more types of monomer. In some embodiments, the intermediate polymer is selected from one or more of ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-amyl acrylate copolymer, ethylene-isooctyl acrylate copolymer, ethylene-acrylonitrile copolymer, ethylene-acrolein copolymer, acrylonitrile-methyl acrylate copolymer, acrylonitrile-isooctyl acrylate copolymer, acrylonitrile-acrolein copolymer.

[0063] In some embodiments, the cyano, aldehyde or ester groups on the intermediate polymer are converted to sodium carboxylate groups by the action of NaOH in the modification reaction. In some embodiments, the cyano, aldehyde or ester groups on the intermediate polymer are converted to potassium carboxylate groups by the action of KOH in the modification reaction. In some embodiments, the cyano, aldehyde or ester groups on the intermediate polymer are converted to ammonium carboxylate groups by the action of aqueous ammonia in the modification reaction. In some embodiments, after the modification reaction, an acidic solution is added to the reaction system to adjust the pH to acidic, and the -COOM groups on the intermediate polymer are converted to carboxylate groups.

[0064] In some embodiments, in the step of preparing the intermediate polymer, the monomers are selected from a first monomer as shown in formula III, in which R4 is a cyano group, an aldehyde group, or an ester group, and a second monomer as shown in formula III, in which R4 is hydrogen or a cyano group, and the second monomer and the first monomer are different in structure.

[0065] The method has a simple manufacturing process, abundant raw materials, and low cost. Cyano groups, aldehyde groups, and ester groups are hydrolyzed under alkaline conditions to convert some or all of them into carboxylic acids or carboxylate groups, thereby improving the polarity of the polymer, reducing the absorption of electrolytes by the adhesive, especially polyester electrolytes, and improving the chemical and oxidative stability of the adhesive. In addition, the Li generated after ionization of the carboxylate salts present in the polymer can be used as a catalyst. + , Na + Such metal cations can increase the content of dissociated ions in the battery electrolyte, promote the transport of charge carriers, and improve the dynamic performance of the battery.

[0066] In some embodiments, the first monomer is selected from one or more of acrolein, acrylonitrile, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, and methyl methacrylate. The above materials are simple, readily available, and low in cost, which is favorable for popularization and application.

[0067] In some embodiments, the second monomer is selected from one or more of ethylene, propylene, butene, and acrylonitrile. The above materials are simple, readily available, and low in cost, which is favorable for popularization and application.

[0068] In some embodiments, the molar ratio of the second monomer to the first monomer is from 2:8 to 9:1, optionally from 3:7 to 8:2, and further optionally from 5:5 to 8:2.

[0069] If the ratio of the second monomer is too high, the flexibility of the adhesive decreases, causing the plate to become too brittle and difficult to process, but if the ratio of the first monomer is too high, the polarity of the adhesive becomes too high and it becomes difficult to dissolve in organic solvents. By controlling the ratio of the second monomer to the first monomer within an appropriate range, it is possible to achieve a balance between the adhesive's liquid absorption, flexibility, and processability.

[0070] In some embodiments, the weight average molecular weight of the intermediate polymer is 5×10 4 ~1.5×10 6 or 1.5 × 10 5 ~8×10 5 In some embodiments, the weight average molecular weight of the intermediate polymer is 2×10 5 ~8×10 5 or 2 × 10 5 ~7×10 5 , or 3 × 10 5 ~7×10 5 , or 2 × 10 5 ~6×10 5 It is.

[0071] The processing performance of the intermediate polymer can be adjusted by controlling the weight average molecular weight of the intermediate polymer. If the molecular weight is too low, the intermediate polymer will be brittle and will have insufficient adhesive strength, but if the molecular weight is too high, the intermediate polymer will be prone to gelation, and the modified product will be prone to solidification and difficult to extract.

[0072] In some embodiments, the alkaline material is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, and aqueous ammonia. In some embodiments, the alkaline material is an organic base. The above materials are simple, readily available, and low in cost, which is favorable for popularization and application.

[0073] In some embodiments, the molar ratio of the total amount of functional groups of cyano groups, aldehyde groups, and ester groups in the first monomer to the alkaline substance is 1:0.1 to 1:2, or 1:0.5 to 1:1.5. In some embodiments, the molar ratio of the total amount of functional groups of cyano groups, aldehyde groups, and ester groups in the first monomer to the alkaline substance is 1:0.5 to 1:2. By controlling the molar ratio of the total amount of functional groups of cyano groups, aldehyde groups, and ester groups in the first monomer to the alkaline substance within an appropriate range, the hydrolysis degree of the functional groups can be controlled, and the intermediate polymer can be guaranteed to have low absorption in the electrolyte and high solubility in an oil-based solvent, while achieving both the use performance and processing performance of the electrode plate.

[0074] In some embodiments, the reaction temperature of the reforming reaction is 35°C to 120°C, and optionally 60°C to 90°C. In some embodiments, the upper or lower limit of the reaction temperature at which the intermediate polymer and the aqueous solution of the alkaline substance are mixed and reacted is selected from 35°C, 45°C, 55°C, 60°C, 70°C, 80°C, 90°C, 100°C, and 120°C. By controlling the reaction temperature within an appropriate range, the degree of hydrolysis of the functional group can be controlled, and it is ensured that the intermediate polymer has little absorption in the electrolyte and high solubility in the oil-based solvent, while the use performance and processing performance of the electrode plate can be compatible.

[0075] In some embodiments, the reaction time of the modification reaction is 1 to 24 h, optionally 4 to 10 h. In some embodiments, the reaction time for mixing and reacting the intermediate polymer with the aqueous solution of the alkaline substance is 1 h, 4 h, 8 h, 10 h, 12 h, 18 h, or 24 h. By controlling the reaction time within an appropriate range, the hydrolysis degree of the functional group can be controlled, and the intermediate polymer can be guaranteed to have low absorption in the electrolyte and high solubility in the oil-based solvent, while achieving both the use performance and processing performance of the electrode plate.

[0076] In some embodiments, the method further comprises adding an acidic solution to the reaction product after the completion of the reforming reaction to adjust the pH of the reaction system to 6-8. In some embodiments, the acidic solution is one or more of a hydrochloric acid solution, a sulfuric acid solution, an oxalic acid solution, and an acetic acid solution. In some embodiments, the mass fraction of the acidic solution is 5-20 wt%.

[0077] By adjusting the pH of the adhesive to be weakly acidic or neutral, gelation of the slurry caused by the adhesive in the manufacturing process of the electrode slurry can be prevented, and the stability of the slurry can be improved.

[0078] In one embodiment of the present application, an electrode is provided, comprising an electrode active material and an adhesive according to any one of the embodiments or an adhesive manufactured by the manufacturing method according to any one of the embodiments, the electrode having a low swelling rate in an electrolyte, which can reduce the internal resistance of a battery and improve the power performance and cycle performance of the battery.

[0079] In some embodiments, the electrode active material is a positive electrode active material, and the positive electrode active material comprises a lithium-containing transition metal oxide.

[0080] In some embodiments, the electrode plate includes a current collector and an electrode film applied to a surface of the current collector, the electrode film including an electrode active material and an adhesive of any one of the embodiments or an adhesive produced by the manufacturing method of any one of the embodiments.

[0081] In some embodiments, the mass percentage of the adhesive of any one of the embodiments or the adhesive film produced by the manufacturing method of any one of the embodiments is 1% to 8%, or 1% to 4%, or 2% to 4%.

[0082] In one embodiment of the present application, a battery is provided, comprising the electrode of any one of the embodiments, the battery having reduced internal resistance and improved power and cycle performance.

[0083] The secondary battery, battery module, battery pack and power consuming device of the present application will be described below with appropriate reference to the drawings.

[0084] In one embodiment of the present application, a secondary battery is provided.

[0085] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During charging and discharging of the battery, active ions shuttle between the positive electrode plate and the negative electrode plate, absorbing and releasing them. The electrolyte functions to conduct ions between the positive electrode plate and the negative electrode plate. The separator is installed between the positive electrode plate and the negative electrode plate, and mainly serves to prevent short-circuiting between the positive and negative electrodes, while allowing ions to pass through. [Positive plate]

[0086] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including the positive electrode active material of the first aspect of the present application.

[0087] For example, the positive electrode current collector has two opposing surfaces in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on either or both of the two opposing surfaces of the positive electrode current collector.

[0088] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, an aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0089] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries well known in the art. For example, the positive electrode active material may include at least one of lithium-containing phosphates 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 positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (may be abbreviated as "LiNi") 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (may be abbreviated as "LiNi") 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as "LiNi") 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (may be abbreviated as "LiNi") 0.8 Co 0.1 Mn 0.1 O2(NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05Examples of the lithium-containing phosphate having an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0090] In some embodiments, the positive electrode membrane layer optionally further comprises a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, by way of example.

[0091] In some embodiments, the positive electrode plate may be manufactured by the following method: The above-mentioned components for manufacturing the positive electrode plate, such as the positive electrode active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, and the positive electrode slurry is coated on a positive electrode current collector, and the positive electrode plate is obtained through processes such as drying and cold pressing. [Negative plate]

[0092] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0093] For example, the negative electrode current collector has two opposing surfaces in the thickness direction of the negative electrode current collector, and the negative electrode film layer is disposed on either one or both of the two opposing surfaces of the negative electrode current collector.

[0094] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, a copper foil may be used as the metal foil sheet. The composite current collector may include a polymeric base layer and a metal layer formed on at least one surface of the polymeric substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymeric substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0095] In some embodiments, the negative electrode active material may be a negative electrode active material for batteries well known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate. The silicon-based material may be selected from at least one of silicon, silicon oxide, silicon carbon composite, silicon nitrogen composite, and silicon alloy. The tin-based material may be selected from at least one of tin, tin oxide, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material for a battery may be used. These negative electrode active materials may be used alone or in combination of two or more.

[0096] In some embodiments, the negative electrode membrane layer optionally further comprises an adhesive, which may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0097] In some embodiments, the negative electrode membrane layer optionally further comprises a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0098] In some embodiments, the negative electrode membrane layer optionally further comprises other auxiliary agents, such as a thickening agent (eg, sodium carboxymethylcellulose (CMC-Na)).

[0099] In some embodiments, the negative electrode plate may be manufactured by the following method: The above-mentioned components for manufacturing the negative electrode plate, such as the negative electrode active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, and the negative electrode slurry is coated on a negative electrode current collector, followed by processes such as drying and cold pressing to obtain a negative electrode plate. [Electrolyte]

[0100] The electrolyte serves to conduct ions between the positive and negative plates. The present application is not specifically limited to the type of electrolyte, which can be selected according to need. For example, the electrolyte may be liquid, gel, or all solid.

[0101] In some embodiments, the electrolyte employs an electrolyte solution, the electrolyte solution including an electrolyte salt and a solvent.

[0102] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonate), lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0103] In some embodiments, the solvent may be selected from 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, ethyl methyl sulfone, and diethyl sulfone.

[0104] In some embodiments, the electrolyte solution optionally further includes additives. The additives may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some performance of the battery, such as an additive that improves the overcharge performance of the battery, an additive that improves the high temperature or low temperature performance of the battery, etc. [Separator]

[0105] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any well-known separator with a porous structure having good chemical stability and mechanical stability may be selected.

[0106] In some embodiments, the material of the separator may be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer thin film or a multi-layer composite thin film, and there is no particular limitation. When the separator is a multi-layer composite thin film, the materials of each layer may be the same or different, and there is no particular limitation. [Secondary battery]

[0107] In some embodiments, the positive and negative plates and the separator may be fabricated into an electrode assembly by a winding or lamination process.

[0108] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0109] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0110] The present application is not particularly limited to the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, FIG. 1 shows a secondary battery 5 with a rectangular structure as an example.

[0111] In some embodiments, referring to FIG. 2, the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected on the bottom plate, and the bottom plate and the side plate surround the bottom plate to form a receiving cavity. The case 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be provided to cover the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate and the separator can form an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte permeates the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and can be selected by those skilled in the art according to actual specific needs. [Battery module]

[0112] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, with the specific number being selectable by one skilled in the art based on the application and capacity of the battery module.

[0113] Fig. 3 shows an example of a battery module 4. Referring to Fig. 3, in the battery module 4, the secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the secondary batteries 5 may be fixed by fasteners.

[0114] Optionally, the battery module 4 may further include a housing having an accommodating space, and the multiple secondary batteries 5 are accommodated in the accommodating space. [Battery pack]

[0115] In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and the specific number can be selected by one skilled in the art based on the application and capacity of the battery pack.

[0116] 4 and 5 show an example of a battery pack 1. Referring to FIG. 4 and FIG. 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 is provided to cover the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box according to any manner. [Power consumption equipment]

[0117] In one embodiment of the present application, a power consuming device is provided, comprising a battery according to any one of the embodiments.

[0118] The power consuming device includes at least one of a secondary battery, a battery module, or a battery pack according to the present application. The secondary battery, the battery module, or the battery pack may be used as a power source for the power consuming device, or may be used as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, a mobile device (e.g., a mobile phone, a laptop, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0119] The power consumption device can be selected as a secondary battery, a battery module, or a battery pack depending on the demands of the usage.

[0120] 6 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. A battery pack or a battery module can be adopted to meet the power consuming device's demand for high power and high energy density of secondary batteries.

[0121] Another example of the device may be a mobile phone, a tablet computer, a notebook computer, etc. Such devices are generally required to be lightweight and may employ a secondary battery as a power source. Working Example

[0122] The following describes the examples of the present application. The examples described below are illustrative and are only for interpreting the present application, and should not be understood as limitations on the present application. If no specific techniques or conditions are specified in the examples, they will be performed according to the techniques or conditions described in the technical literature or the product instructions. For reagents or instruments used, those without the manufacturer's name are all common products that can be purchased commercially. Example 1 1) Adhesive manufacturing

[0123] The method for producing the adhesive is as follows.

[0124] Preparation of intermediate polymer: 100g methyl acrylate (first monomer), 300mL deionized water, 2g emulsifier alkylphenol ethoxylate OP-10, and 3g ammonium persulfate as initiator are added to a high-pressure reactor, and mixed uniformly. Then, the temperature is raised to 90°C, 8.2g ethylene (second monomer) is added, and the pressure is controlled to 10MPa to react for 6h. After the reaction is completed, the reaction emulsion is left at 0°C for 10h to precipitate solids, and then suction filtered and dried to obtain ethylene-methyl acrylate (second monomer-first monomer) polymer, i.e., intermediate polymer, in which the molar ratio of ethylene to methyl acrylate in the ethylene-methyl acrylate copolymer is 8:2.

[0125] Modification reaction: 100g of ethylene-methyl acrylate polymer powder and 300mL of deionized water were added to the reaction kettle, and the mixture was stirred for 30min to mix uniformly. Then, 12.1g of LiOH was dissolved in 50mL of deionized water to prepare an alkaline solution, which was then added to the reaction kettle. The temperature of the reaction kettle was then raised to 90°C and reacted for 4h. After the reaction, the temperature of the reaction kettle returned to room temperature, and a 5% acetic acid solution was prepared and added drop by drop to the reaction kettle to adjust the pH of the product to neutral. The product was then dried to obtain an adhesive. Through the modification reaction, the functional groups of the ester groups derived from the first monomer, methyl acrylate, on the intermediate polymer were converted to -COOLi groups. 2) Manufacturing of positive electrodes

[0126] The adhesive produced in Example 1, the lithium iron phosphate positive electrode active material, carbon black as a conductive agent, and N-methylpyrrolidone (NMP) were stirred and mixed uniformly in a weight ratio of 1.28:62.2:0.52:36 to obtain a positive electrode slurry. The positive electrode slurry was then uniformly coated on a positive electrode current collector, which was then dried, cold pressed, and slit to obtain a positive electrode plate. 3) Manufacturing of negative electrodes

[0127] The active material, artificial graphite, the conductive agent, carbon black, the adhesive, styrene butadiene rubber (SBR), and the thickener, sodium carboxymethyl cellulose (CMC-Na), were dissolved in the solvent, deionized water, in a weight ratio of 96.2:0.8:0.8:1.2, and mixed uniformly to produce anode slurry. The anode slurry was uniformly coated on the copper foil of the anode current collector once or several times, and the anode plate was obtained after drying, cold pressing, and slitting. 4) Separator

[0128] A polypropylene membrane serves as the separator. 5) Electrolyte production

[0129] In a glove box with an argon atmosphere (H2O<0.1ppm, O2<0.1ppm), the organic solvents ethylene carbonate (EC) / ethyl methyl carbonate (EMC) were mixed uniformly in a volume ratio of 3 / 7, and LiPF6 lithium salt was dissolved in the organic solvent to prepare a 12.5% ​​solution, resulting in the electrolyte. 6) Battery manufacturing

[0130] The positive electrode plate, separator, and negative electrode plate manufactured in Example 1 were stacked in order, with a separator positioned between the positive and negative electrodes to perform an isolating function, and then wound to obtain a bare cell, which was then welded to a tab, inserted into an aluminum case, baked at 80°C to remove moisture, and immediately injected with electrolyte and sealed to obtain an uncharged battery. The uncharged battery was then subjected to processes such as standing, hot and cold pressing, chemical formation, shaping, and capacity measurement in order to obtain the finished lithium ion battery of Example 1.

[0131] The batteries of Examples 2 to 28 and Comparative Examples 1 to 10 were manufactured using a method similar to that of the battery of Example 1, but the raw materials and reaction conditions for manufacturing the adhesive were adjusted. The details of the different parameters are shown in Table 1.

[0132] in particular, In Example 2, the monomers used to produce the intermediate polymer were ethylene and acrylonitrile, and the cyano group derived from the first monomer, acrylonitrile, on the intermediate polymer was converted to a -COOLi group by the modification reaction.

[0133] In Example 3, the monomers used to produce the intermediate polymer were ethylene and acrolein, and the aldehyde groups derived from the first monomer, acrolein, on the intermediate polymer were converted to -COOLi groups by the modification reaction.

[0134] In Example 4, the monomers used to prepare the intermediate polymer were acrylonitrile and methyl acrylate, and the ester groups on the intermediate polymer derived from the first monomer, methyl acrylate, were converted to -COOLi groups by a modification reaction.

[0135] In Example 5, the monomers used to produce the intermediate polymer were acrylonitrile and acrolein, and the aldehyde groups derived from the first monomer, acrolein, on the intermediate polymer were converted to -COOLi groups by the modification reaction.

[0136] Other parameters in Examples 2-5 are consistent with Example 1.

[0137] The alkaline substance in Example 6 was sodium hydroxide, and the functional group of the ester group derived from methyl acrylate, which is the first monomer, on the intermediate polymer was converted to a -COONa group by a modification reaction.

[0138] The alkaline substance in Example 7 was aqueous ammonia, and the functional groups of the ester groups derived from methyl acrylate, the first monomer, on the intermediate polymer were converted to -COONH4 groups by a modification reaction.

[0139] Other parameters in Examples 6-7 are consistent with Example 1.

[0140] The alkaline substance in Example 8 was potassium hydroxide, and the functional groups of the ester groups derived from methyl acrylate, the first monomer, on the intermediate polymer were converted to -COOK groups by a modification reaction.

[0141] In Example 9, in the process of producing the adhesive, after the modification reaction is completed, 5% acetic acid solution is added dropwise to adjust the pH of the product in the reaction vessel to 2-3, followed by stirring for 2 hours. After that, the product is dried, washed with deionized water three times, and dried. Through the modification reaction, the functional group of the ester group derived from the first monomer, methyl acrylate, on the intermediate polymer is converted to a -COOH group.

[0142] The molar ratio of ethylene to methyl acrylate in Example 10 was 6:4.

[0143] The molar ratio of ethylene to methyl acrylate in Example 11 was 5:5.

[0144] The molar ratio of ethylene to methyl acrylate in Example 12 was 4:6.

[0145] The molar ratio of ethylene to methyl acrylate in Example 13 was 3:7.

[0146] The molar ratio of ethylene to methyl acrylate in Example 14 was 2:8.

[0147] The molar ratio of ethylene to methyl acrylate in Example 15 was 9:1.

[0148] Other parameters in Examples 10-15 are consistent with Example 1.

[0149] The molar ratio of methyl acrylate to lithium hydroxide in Example 16 is 1:0.5.

[0150] The molar ratio of methyl acrylate to lithium hydroxide in Example 17 is 1:1.5.

[0151] The molar ratio of methyl acrylate to lithium hydroxide in Example 18 is 1:2.

[0152] The molar ratio of methyl acrylate to lithium hydroxide in Example 19 is 1:0.1.

[0153] Other parameters in Examples 16-19 are consistent with Example 1.

[0154] The reaction temperature of the reforming reaction in Example 20 was 35° C. The reaction temperature of the reforming reaction in Example 21 was 60° C. The reaction temperature of the reforming reaction in Example 22 was 75° C. The reaction temperature of the reforming reaction in Example 23 was 120° C. Other parameters in Examples 16-23 are consistent with Example 1.

[0155] The reaction temperature of the reforming reaction in Example 24 was 60° C., and the reaction time was 0.2 h. The reaction temperature of the reforming reaction in Example 25 was 60° C., and the reaction time was 1 h. The reaction temperature of the reforming reaction in Example 26 was 60° C., and the reaction time was 8 h. The reaction temperature of the reforming reaction in Example 27 was 60° C., and the reaction time was 10 h. The reaction temperature of the reforming reaction in Example 28 was 60° C., and the reaction time was 24 h. Other parameters in Examples 24-28 are consistent with Example 1.

[0156] In Comparative Examples 1-5, the intermediate polymers produced in Examples 1-5 were directly used as adhesives, without modifying the intermediate polymers with alkaline substances. In Comparative Examples 6-11, the intermediate polymers prepared in Examples 10-15 were directly used as adhesives, without conversion of the intermediate polymers with alkaline substances. The specific parameters are as shown in Table 1.

[0157] The relevant parameters of the adhesives of Examples 1 to 28 and Comparative Examples 1 to 11 are as shown in Table 1 below.

[0158] In addition, the performance of the electrodes and batteries obtained in Examples 1 to 28 and Comparative Examples 1 to 11 was measured, and the measurement method was as follows. 1. Method for measuring weight-average molecular weight

[0159] The adhesive obtained in Example 1 was vacuum-dried in a vacuum oven at 80°C for 12 hours, 0.1 g of the adhesive was dissolved in 20 mL of N-methylpyrrolidone, and the solution was filtered using a filter membrane with a pore size of 10 μm. 5 mL of the solution was then taken and the weight-average molecular weight was measured by gel permeation chromatography. The detector used was a differential refractive index detection method, and the standard substance was polystyrene. 2. The molar content N of the structural unit shown in formula II II Measurement of (%)

[0160] When M in formula II is a metal element, i.e., Li, Na, or K, inductively coupled plasma emission spectroscopy (ICP) is used to measure the mass percentage W of the metal element M in the adhesive. M (%), the decomposition method is the plate method, and the decomposition solvent is concentrated nitric acid. Before the measurement, the adhesive sample powder was washed three times with deionized water to remove the free metal ions adsorbed on the surface, and then the product was dried and subjected to the measurement.

[0161] Molar content N of structural units of formula II II (%) can be calculated using the following formula:

[0162] N II (%)=W M *M 総 / M M In the formula, M総 is the molecular weight of the structural unit of the adhesive, and M M is the molecular weight of the M element.

[0163] When M in formula II is H or NH4, the adhesive must first be subjected to ion exchange treatment to replace M with Na, and the specific scheme is as follows: 10 g of adhesive powder is placed in 200 mL of 5 wt% sodium chloride aqueous solution, stirred at 40°C for 1 h to carry out ion exchange, then filtered, and the resulting powder is washed with deionized water three times to remove sodium ions adsorbed on the surface, and then the product is dried and the mass percentage of sodium element W is measured by ICP. Na (%) was measured.

[0164] Molar content N of structural units of formula II II (%) can be calculated using the following formula:

[0165] N II (%)=W Na *M 総 / twenty three In the formula, M 総 is the molecular weight of the structural unit of the adhesive. 3. Molar content of the second structural unit

[0166] Molar content of second structural unit = second monomer charge / (second monomer charge + first monomer charge) 4. Plate swelling rate measurement

[0167] The measurement process of the plate swelling rate is as follows: the positive plate prepared in the embodiment or comparative example is cold pressed, and then cut out an area of ​​5*5cm, weighed, and recorded as m0; and the corresponding battery in the embodiment or comparative example is stored at 60°C for 7 days, and then cut out an area of ​​5*5cm from the positive plate, immediately wiped off the electrolyte remaining on the surface, and then weighed, and recorded as m1; the plate swelling rate can be calculated by the following formula:

[0168] Plate swelling rate (%)=(m1-m0) / m0×100% 5. Battery DC impedance measurement

[0169] The measurement process of the DC impedance of the battery is as follows: At 25°C, the battery manufactured in the embodiment or comparative example is charged to 4.3V at a constant current of 1 / 3C, and then charged to a constant voltage of 4.3V until the current becomes 0.05C, and after leaving it for 5 minutes, the voltage V1 is recorded. Then, it is discharged at 1 / 3C for 30s, and the voltage V2 is recorded, and the internal resistance DCR of the battery after the first cycle is obtained as (V2-V1) / 1 / 3C. 6.Battery capacity maintenance rate measurement

[0170] The measurement process of the battery capacity retention is as follows: At 25°C, the manufactured battery is charged to 4.3V at a constant current of 1 / 3C, further charged at a constant voltage of 4.3V until the current becomes 0.05C, left for 5 minutes, and further discharged to 2.8V at 1 / 3C, and the obtained capacity is recorded as the initial capacity C0. The above steps are repeated for the same battery, and the discharge capacity Cn of the battery after the nth cycle is recorded, so that the capacity retention rate of the battery after each cycle Pn=Cn / C0*100%, where the values ​​of 100 points of P1, P2...P100 are the ordinate and the corresponding number of cycles is the abscissa. In this measurement process, the first cycle corresponds to n=1, the second cycle corresponds to n=2,...the 100th cycle corresponds to n=100. The data of the battery capacity retention rate corresponding to the examples or comparative examples in Table 2 are the data measured after 100 cycles under the above measurement conditions, that is, the value of P100. The measurement process for the other examples and comparative examples is similar to that described above.

[0171] The performance measurement results of the electrodes and batteries obtained in Examples 1 to 28 and Comparative Examples 1 to 11 are shown in Table 1. JPEG2024526517000006.jpg229133JPEG2024526517000007.jpg226130JPEG20245265170 00008.jpg226134JPEG2024526517000009.jpg228137JPEG2024526517000010.jpg229132 JPEG2024526517000011.jpg228134

[0172] In Examples 1 to 28, adhesives are provided, the adhesives being polymers containing structural units shown in Formula I and Formula II, JPEG2024526517000012.jpg40128 where R1, R2, R3, R5, R6, and R7 are each independently selected from hydrogen, R4 is selected from hydrogen, a cyano group, an aldehyde group, or an ester group, and M is selected from H, Li, Na, K, or NH4. Compared with Comparative Examples 1 to 11, the plate swelling rate was all decreased, the internal resistance of the battery was decreased, and the cycle capacity retention rate was increased.

[0173] In Examples 1 to 28, the molar content of the structural unit shown in formula II is 0.1% to 60% based on the total number of moles of all structural units in the polymer. Compared with Comparative Examples 1 to 11, the plate swelling rate was lower in all cases, the internal resistance of the battery was lower, and the capacity retention rate was higher. In Examples 1 to 28, when the molar content of the structural unit shown in formula II is 10% to 40%, the decrease in the internal resistance of the battery is more significant, and the cycle capacity retention rate is higher.

[0174] In Examples 1 to 28, the polymer includes a first structural unit represented by formula I, in which R4 is a cyano group, an aldehyde group, or an ester group, and a second structural unit represented by formula I, in which R4 is hydrogen or a cyano group, and the first structural unit and the second structural unit are different. Compared with Comparative Examples 1 to 11, the electrode plate swelling rate was all reduced, the internal resistance of the battery was reduced, and the cycle capacity retention rate was increased.

[0175] In Examples 1 to 28, the molar content of the second structural unit is 20% to 90% based on the total number of moles of all structural units in the polymer. Compared with Comparative Examples 1 to 11, the plate swelling rate was lower in all cases, the internal resistance of the battery was lower, and the cycle capacity retention rate was higher. In Example 15, when the ratio of the structural unit derived from an ethylene monomer in the polymer was 90%, the plate swelling rate was lower, but the adhesion of the plate was poor and the cycle stability of the battery was lower, so the cycle capacity retention rate of the battery was lower. When the molar content of the second structural unit is 50% to 80% based on the total number of moles of all structural units in the polymer, the battery resistance was lower and the cycle capacity retention rate was higher.

[0176] It should be noted that the present application is not limited to the above-mentioned embodiment. The above-mentioned embodiment is an example, and any embodiment having substantially the same configuration as the technical idea and achieving the same effect within the scope of the technical proposal of the present application is included in the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiment and other forms constructed by combining some of the components in the embodiment are also included in the scope of the present application, within the scope of the purpose of the present application. [Explanation of symbols]

[0177] 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 secondary battery, 51 case, 52 electrode assembly, 53 top cover assembly

Claims

1. A method for producing a binder, comprising: The binder is a polymer containing structural units shown in Formula I and Formula II, wherein R 1 , R 2 , R 3 , R 5 , R 6 and R 7 are each independently selected from hydrogen or a substituted or unsubstituted C 1-3 alkyl group; R 4 is selected from hydrogen, a cyano group, an aldehyde group or an ester group; M is selected from Li, Na, K or NH 4 ; The polymer comprises a first structural unit according to Formula I, wherein R 4 is an aldehyde group or an ester group, and a second structural unit according to Formula I, wherein R 4 is a cyano group, wherein the first structural unit and the second structural unit are different: Based on the total number of moles of all structural units in the polymer, the molar content of the structural unit shown in formula II is 0.1% to 60%; The manufacturing method includes: preparing an intermediate polymer by polymerizing a monomer according to formula III to form an intermediate polymer containing at least a cyano group, an aldehyde group, or an ester group; In the formula III, R １ , R ２ , R ３ are each independently hydrogen, substituted or unsubstituted C １－３ alkyl groups, R ４ is selected from hydrogen, a cyano group, an aldehyde group, or an ester group; The monomer is R ４ a first monomer of formula III, wherein R is an aldehyde group or an ester group; ４ is a cyano group, and the second monomer and the first monomer are different in structure; In a modification reaction step, the intermediate polymer is subjected to a modification reaction with an aqueous solution of an alkaline substance to convert at least a part of the cyano group, aldehyde group or ester group in the intermediate polymer into COOM, wherein M is Li, Na, K or NH ４ and a step selected from the group consisting of:

2. A method for producing a binder as described in claim 1, characterized in that the molar content of the second structural unit is 20% to 90% based on the total number of moles of all structural units in the polymer.

3. 2. The method for producing a binder according to claim 1, wherein a molar ratio of the second monomer to the first monomer is 2:8 to 9:

1.

4. 2. The method for producing a binder according to claim 1, wherein the first monomer is selected from one or more of acrolein, acrylonitrile, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, and methyl methacrylate.

5. The method for producing a binder according to claim 1 , wherein the second monomer is selected from one or more of ethylene, propylene, butene, and acrylonitrile.

6. The weight average molecular weight of the intermediate polymer is 5×10 ４ ~1.5 x 10 ６ 2. The method for producing a binder according to claim 1, wherein

7. 2. The method for producing a binder according to claim 1, wherein the alkaline substance is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, and aqueous ammonia.

8. 2. The method for producing a binder according to claim 1, wherein a molar ratio of a total amount of functional groups of a cyano group, an aldehyde group, and an ester group in the first monomer to the alkaline substance is 1:0.1 to 1:

2.

9. 2. The method for producing a binder according to claim 1, wherein the reaction temperature of the modification reaction is 35°C to 120°C.

10. 2. The method for producing a binder according to claim 1, wherein the reaction time of the modification reaction is 1 to 24 hours.

11. 2. The method for producing a binder according to claim 1, further comprising adding an acidic solution to the reaction product to adjust the pH of the reaction system to 6 to 8 after the modification reaction is completed.

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