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] This application relates to the field of lithium battery technology, in particular binder The present invention relates to 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. As the application of lithium-ion batteries becomes more widespread, the requirements for their cycle performance, service life, etc. are also increasing.

[0003] binder is a commonly used material in lithium-ion batteries and is highly required for battery plates, separators, packaging, etc. binder The poor adhesion of the battery leads to a significant decrease in performance during use, which further affects the battery's service life. binder There is still room for improvement. Summary of the Invention

[0004] The present application has been made in view of the above problems, and its purpose is to: binder for improving battery performance by reducing swelling in electrolyte binder , and the binder and (c) providing an electrode comprising:

[0005] According to a first aspect of the present application, binder This provides binder is a polymer containing structural units shown in Formula I and Formula II, JPEG0007739457000001.jpg41170 where R1, R2, R3, R5, R6, and R7 each independently represent hydrogen or a C group 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 method for improving the polarity of a polymer by including -COOM groups, i.e., carboxylic acids or carboxylate salt groups, in the polymer, binder This can reduce the absorption of solvents in the electrolyte by the carboxylic acid or carboxylic acid salt, 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 carboxylic acid salt has high chemical stability and oxidation stability in the electrolyte. In addition, the Li generated after ionization of the carboxylic acid salt present in the polymer + , Na + Metal cations such as 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 moles of all structural units in the polymer. By controlling the ratio of the structural unit shown in Formula II, binder This allows the solubility in the oil-based solvent and the absorption rate in the electrolyte to be compatible, and further reduces the DC resistance of the battery, improving the power performance and cycle performance of the battery.

[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 strength, ductility, and adhesive properties; and binder This reduces the absorption of electrolyte by the electrode, thereby making the electrode more resistant to swelling.

[0009] In any embodiment, the molar content of the second structural unit is 20% to 90%, and optionally 50% to 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, it is possible to improve the adhesiveness of the polymer and reduce the absorption of the electrolyte by the polymer.

[0010] According to a second aspect of the present application, binder The method for producing the compound of formula (1) is provided, which method comprises 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; JPEG0007739457000002.jpg52164 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; 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, wherein M is selected from H, Li, Na, K or NH4.

[0011] The method has a simple manufacturing process, abundant raw materials, and low cost. The cyano group, aldehyde group, and ester group are hydrolyzed under alkaline conditions to convert some or all of them into carboxylic acid or carboxylate groups, thereby improving the polarity of the polymer. binder This reduces the absorption of electrolyte, particularly polyester-based electrolyte, by the binder It also improves the chemical and oxidative stability of the polymer. + , Na + Metal cations such as 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 shown in Formula III, in which R4 is a cyano group, an aldehyde group, or an ester group, and a second monomer 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, binder It is possible to achieve both liquid absorption, flexibility and processability.

[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 substance is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, and aqueous ammonia, which are simple, readily available, and low in cost, favorable for widespread use and application.

[0018] In any embodiment, the molar ratio of the total amount of functional groups (cyano, aldehyde, and ester) 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 functional groups (cyano, aldehyde, and ester) in the first monomer to the alkaline substance within an appropriate range, the degree of hydrolysis of the functional groups can be controlled, ensuring that the intermediate polymer has low absorption in the electrolyte and high solubility in oil-based solvents, and achieving both the usability and processability of the electrode plate.

[0019] In any embodiment, the reaction temperature of the modification reaction is 35° C. to 120° C., and optionally 60 to 90° C. By controlling the reaction temperature within an appropriate range, the degree of hydrolysis of the functional group can be controlled, and it is possible to ensure that the intermediate polymer has low absorption in the electrolyte and high solubility in the oil-based solvent, and also to achieve both the use performance and processability of the electrode plate.

[0020] In any embodiment, the reaction time of the modification reaction is 1 to 24 hours, optionally 4 to 10 hours. By controlling the reaction time 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 usability and processability of the electrode plate.

[0021] In an optional embodiment, the method further comprises, after the completion of the reforming reaction, 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 a weak acidic or neutral state, the electrode slurry can be produced in a process. binder This can prevent gelation of the slurry due to the above-mentioned reaction, thereby improving the stability of the slurry.

[0022] According to a third aspect of the present application, there is provided a secondary battery, the secondary battery including an electrode assembly and an electrolyte, the electrode assembly including a positive electrode plate, a separator, and a negative electrode plate, the positive electrode plate including a positive electrode active material and the negative electrode active material according to the first or second aspect of the present application. binder The positive electrode plate has a low swelling rate in an 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, which includes 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, which includes 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 aspect and the battery pack of the fifth aspect of the present application include the secondary battery of the third aspect, and therefore have the same advantages as the secondary battery. [Brief explanation of the drawings]

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

[0028] Hereinafter, the present application will be described with appropriate reference to the drawings. binder The following detailed description will be given of embodiments specifically disclosing the present invention, a manufacturing method, an electrode, a battery, and a power consumption device. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of structures that are actually the same may be omitted. This is to avoid the following description becoming unnecessarily long and to facilitate understanding by those skilled in the art. The drawings and the following description are provided to enable 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 any combination is possible; i.e., any lower limit can be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also possible. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all possible. In this application, unless otherwise specified, a numerical range "a to b" is a shorthand notation for any combination of real numbers a to b, where a and b are both real numbers. For example, the numerical range "0-5" represents that the present specification has already listed all real numbers between "0-5," and "0-5" is merely 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 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 sequentially or randomly, preferably sequentially. For example, a reference to a method including 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, a reference to a method that may further include step (c) means that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0033] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open-ended or closed-ended. For example, "comprise" and "comprises" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[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 when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0035] As the cost of PVDF raw materials increases, ester-containing non-fluorinated resins with good flexibility are becoming more popular. binder However, this ester-containing binder However, since the electrode itself absorbs the electrolyte, the swelling degree of the electrode plate in the electrolyte significantly increases, and the cycle performance and power performance of the battery are significantly reduced. binder This will significantly improve the power and cycle performance of the battery. [ binder ]

[0036] Based on this, the present application: binder This provides binder is a polymer containing structural units shown in Formula I and Formula II, JPEG0007739457000003.jpg42170 where R1, R2, R3, R5, R6, and R7 each independently represent hydrogen or a C group 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 " binder " refers to chemical compounds, polymers, and mixtures that form colloidal solutions or dispersions in a dispersing medium.

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

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

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

[0041] In some embodiments, binder is the negative electrode binder As such, it is used to adhere a negative electrode active material and / or a 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 which differ 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 the macromolecules, and may be chemically homogeneous or chemically heterogeneous compounds.

[0043] In this specification, the term "C 1-3 "Alkyl group" refers to a straight or branched chain hydrocarbon group composed 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 of the general formula -COOR9, where R9 is a C 1-5 Examples of ester groups include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl, isooctyl, and the like.

[0047] As used herein, the term "substituted" means substituted by a substituent, wherein the substituents are each 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 alkoxy groups.

[0048] As used herein, the term "swelling" refers to the phenomenon in which a high molecular weight polymer absorbs a solvent, expanding its volume and the volume of the electrode in which it is located.

[0049] The present application provides a polymer that is made more polar by including -COOM groups, i.e., carboxylic acids or carboxylate salt groups, in the polymer; binder This can reduce the absorption of solvents in the electrolyte by the carboxylic acid or carboxylic acid salt, 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 carboxylic acid salt has high chemical stability and oxidation stability in the electrolyte. In addition, the Li generated after ionization of the carboxylic acid salt present in the polymer + , Na + Metal cations such as 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, the molar content of the structural unit according to Formula II, based on the total number of moles of all structural units in the polymer, is 0.1% to 60%, or 10% to 40%. In some embodiments, the molar content of the structural unit according to Formula II, based on the total number of moles of all structural units in the polymer, 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 polymer will have too much polarity, making it difficult to dissolve in an oily 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 will easily absorb 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, binder This allows the solubility in the oil-based solvent and the absorption rate in the electrolyte to be compatible, and further reduces the DC resistance of the battery, improving the power performance and cycle performance of the battery.

[0052] In some embodiments, the polymer comprises a first structural unit according to Formula I, wherein R4 is an aldehyde group or an ester group, and a second structural unit according to Formula I, wherein 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 hard segments for the polymer and can provide the polymer with a certain degree of crystallinity; binder provides mechanical strength for binder The first structural unit reduces the absorption of the electrolyte by the polymer, and by combining with the first structural unit containing an ester group or an aldehyde group, the first structural unit provides a soft segment for the polymer, providing ductility to the polymer. Thus, by combining the first structural unit and the second structural unit, the polymer is provided with a certain strength, ductility, and adhesiveness, and binder This reduces the absorption of electrolyte by the electrode, thereby making the electrode more resistant to swelling.

[0055] In some embodiments, the molar content of the second structural unit, based on the total number of moles of all structural units in the polymer, is 20% to 90%, or 50% to 80%. In some embodiments, the molar content of the second structural unit, based on the total number of moles of all structural units in the polymer, 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 proportion of the second structural unit in the polymer is too high, the stiffness of the polymer increases and the adhesion decreases. binder If the ratio of the first structural unit in the polymer is too high, the polymer will absorb more electrolyte, resulting in a decrease in the electrode's swelling resistance and the battery's power and cycle performance. By controlling the ratio of the second structural unit in the polymer, it is possible to improve the polymer's adhesiveness and reduce the polymer's absorption of electrolyte.

[0057] In some embodiments, the weight average molecular weight of the polymer is 5×10 4 ~1.5×10 6 or 1.5 x 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 x 10 5 ~7×10 5 , or 3 × 10 5 ~7×10 5 , or 2 × 10 5 ~6×10 5 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 improving the dynamic conditions of the electrode and further improving the battery performance.

[0060] In one embodiment of the present application, binder The method comprises the steps of: Preparation of the 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; JPEG0007739457000004.jpg55170 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: 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.

[0061] As can be seen, the modification reaction does not significantly affect the weight average molecular weight of the intermediate polymer, and binder The difference between the weight average molecular weight of the corresponding intermediate polymer is 1000 or less.

[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, and acrylonitrile-acrolein copolymer.

[0063] In some embodiments, 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, 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, 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, thereby converting the -COOM groups on the intermediate polymer to carboxylic acid groups.

[0064] In some embodiments, in the step of preparing the intermediate polymer, the monomers are selected from a first monomer shown in Formula III, where R4 is a cyano group, an aldehyde group, or an ester group, and a second monomer shown in Formula III, where 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. The cyano group, aldehyde group, and ester group are hydrolyzed under alkaline conditions to convert some or all of them into carboxylic acid or carboxylate groups, thereby improving the polarity of the polymer. binder This reduces the absorption of electrolyte, particularly polyester-based electrolyte, by the binder It also improves the chemical and oxidative stability of the polymer. + , Na + Metal cations such as 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, which are simple, readily available, and low in cost, favoring widespread use 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 advantageous for widespread use and application.

[0068] In some embodiments, 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.

[0069] If the ratio of the second monomer is too high, binder The flexibility of the electrode becomes low, and the electrode plate becomes too brittle and difficult to process. However, if the ratio of the first monomer is too high, binder The polarity of the second monomer becomes too high, making it difficult to dissolve in organic solvents. By controlling the ratio of the second monomer to the first monomer within an appropriate range, binder It is possible to achieve both liquid absorption, flexibility and processability.

[0070] In some embodiments, the weight average molecular weight of the intermediate polymer is 5×10 4 ~1.5×106 or 1.5 x 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 x 10 5 ~7×10 5 , or 3 × 10 5 ~7×10 5 , or 2 × 10 5 ~6×10 5 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 substance is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, and aqueous ammonia. In some embodiments, the alkaline substance is an organic base. The above materials are simple, readily available, and low cost, which is advantageous for widespread use and application.

[0073] In some embodiments, the molar ratio of the total amount of cyano, aldehyde, and ester functional 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 cyano, aldehyde, and ester functional 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 cyano, aldehyde, and ester functional groups in the first monomer to the alkaline substance within an appropriate range, the degree of hydrolysis of the functional groups can be controlled, ensuring low absorption of the intermediate polymer in the electrolyte and high solubility in oil-based solvents, while also achieving both excellent usability and processability of the electrode plate.

[0074] In some embodiments, the reaction temperature of the modification reaction is 35°C to 120°C, optionally 60°C to 90°C. In some embodiments, the upper or lower limit of the reaction temperature for mixing and reacting the intermediate polymer with the aqueous alkaline substance 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 groups can be controlled, ensuring that the intermediate polymer has low absorption in the electrolyte and high solubility in oil-based solvents, while also achieving both the usability and processability of the electrode plate.

[0075] In some embodiments, the reaction time for the modification reaction is 1 to 24 hours, optionally 4 to 10 hours. In some embodiments, the reaction time for mixing and reacting the intermediate polymer with the aqueous alkaline substance is 1 hour, 4 hours, 8 hours, 10 hours, 12 hours, 18 hours, or 24 hours. By controlling the reaction time within an appropriate range, the degree of hydrolysis of the functional groups can be controlled, ensuring that the intermediate polymer has low absorption in the electrolyte and high solubility in oil-based solvents, and achieving both the usability and processability of the electrode plate.

[0076] In some embodiments, the method further includes, after completion of the reforming reaction, adding an acidic solution to the reaction product to adjust the pH of the reaction system to 6 to 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 to 20 wt %.

[0077] binder By adjusting the pH to weakly acidic or neutral, the electrode slurry manufacturing process binder This can prevent gelation of the slurry due to the above-mentioned reaction, thereby improving the stability of the slurry.

[0078] In one embodiment of the present application, an electrode is provided, comprising an electrode active material and binder Or manufactured by the manufacturing method of any one of the embodiments. binder The electrode has a low swelling rate in an electrolyte, which can reduce the internal resistance of the 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 coated on the surface of the current collector, the electrode film including an electrode active material and the electrode active material according to any one of the embodiments. binder Or manufactured by the manufacturing method of any one of the embodiments. binder This includes:

[0081] In some embodiments, any one of the embodiments binder Or manufactured by the manufacturing method of any one of the embodiments. binder The mass percentage of the polymer in the film 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 consumption 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, active ions shuttle between the positive and negative electrodes, absorbing and releasing ions. The electrolyte functions to conduct ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes and allows ions to pass through. [Positive electrode]

[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 surfaces that face each other in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two facing 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, 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 alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[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 a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and a modified compound of each. However, the present application is not limited to these materials, and other conventional materials usable 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., LiCoO), lithium nickel oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and 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 0.05O2) and modified compounds thereof, etc. Examples 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, by way of example, at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

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

[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 surfaces that face each other in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two facing 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 material base layer and a metal layer formed on at least one surface of the polymeric material 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, or silver alloy) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0095] In some embodiments, the negative electrode active material may be a battery negative electrode active material 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, a silicon-based material, a tin-based material, and lithium titanate. The silicon-based material may be selected from at least one of silicon elemental, silicon oxide, silicon carbon composite, silicon nitrogen composite, and silicon alloy. The tin-based material may be selected from at least one of tin elemental, tin oxide, and tin alloy. However, the present application is not limited to these materials, and other conventional materials usable as a battery negative electrode active material may also be used. These negative electrode active materials may be used alone or in combination.

[0096] In some embodiments, the negative electrode film layer optionally comprises binder The above further includes binder 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 film 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 thickener (e.g., sodium carboxymethylcellulose (CMC-Na)).

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

[0100] The electrolyte serves to conduct ions between the positive and negative electrodes. The present application does not specifically limit the type of electrolyte, and the electrolyte may be selected as needed. For example, the electrolyte may be liquid, gel, or all solid.

[0101] In some embodiments, the electrolyte employs an electrolytic solution, the electrolytic 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(trifluoromethanesulfonyl)imide, 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 contains additives, which may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some battery performance, such as an additive that improves the overcharge performance of the battery, or an additive that improves the high-temperature or low-temperature performance of the battery. [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 separator with a well-known porous structure having good chemical stability and mechanical stability may be selected.

[0106] In some embodiments, the separator may be made of at least one material selected from 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, without any particular limitation. When the separator is a multi-layer composite thin film, the materials of each layer may be the same or different, without any particular limitation. [Secondary battery]

[0107] In some embodiments, the positive and negative electrode plates and separator may be wound or stacked to form an electrode assembly.

[0108] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and 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 pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0110] The present application does not particularly limit the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows an example of a rectangular secondary battery 5.

[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 side plates connected to the bottom plate, and the bottom plate and side plates surround and 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 and close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. An electrolyte is impregnated into 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, and the specific number can be selected by those 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, a plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fastened with fasteners.

[0114] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of 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, the specific number of which can be selected by those 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 FIGS. 4 and 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, forming an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in 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 as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

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

[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, which may employ a battery pack or a battery module to meet the high power and high energy density demands of secondary batteries.

[0121] Other example devices may be mobile phones, tablet computers, laptop computers, etc. Such devices are generally required to be lightweight and may employ secondary batteries as their power source. Example

[0122] Examples of the present application are described below. The examples described below are illustrative and are intended only to interpret the present application, and should not be understood as limitations on the present application. If specific techniques or conditions are not specified in the examples, they will be carried out in accordance with the techniques or conditions described in the technical literature or the product instructions. Reagents or instruments used without a specified manufacturer are all common products that can be purchased commercially. Example 1 1) binder Manufacturing

[0123] binder The manufacturing method is as follows.

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

[0125] Modification reaction: 100g of ethylene-methyl acrylate polymer powder and 300mL of deionized water were added to the reactor and stirred for 30 minutes to ensure uniform mixing. Then, 12.1g of LiOH was dissolved in 50mL of deionized water to prepare an alkaline solution, which was then added to the reactor. The temperature of the reactor was then raised to 90°C and the reaction was continued for 4 hours. After the reaction was completed and the reactor temperature returned to room temperature, a 5% acetic acid solution was prepared and added dropwise to the reactor to adjust the pH of the product to neutral. The product was then dried. binder The functional groups of the ester groups derived from the first monomer, methyl acrylate, on the intermediate polymer were converted to -COOLi groups by a modification reaction. 2) Manufacturing of positive electrode plates

[0126] Produced in Example 1 binderThe 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 onto a positive electrode current collector, which was then dried, cold pressed, and slit to obtain a positive electrode plate. 3) Manufacturing of negative electrode plates

[0127] Artificial graphite as an active material and carbon black as a conductive agent. binder Styrene butadiene rubber (SBR) and carboxymethyl cellulose sodium (CMC-Na) as a thickener were dissolved in deionized water as a solvent in a weight ratio of 96.2:0.8:0.8:1.2 and mixed uniformly to produce anode slurry. The cathode slurry was then uniformly coated onto the copper foil of the cathode current collector in one or several coats, followed by drying, cold pressing, and slitting to obtain anode plates. 4) Separator

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

[0129] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), the organic solvents ethylene carbonate (EC) and 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 prepared in Example 1 were stacked in this order, with a separator positioned between the positive and negative electrodes to provide isolation, and then wound to obtain a bare cell. Tabs were welded to the bare cell, which was then inserted into an aluminum case and baked at 80°C to remove moisture. An electrolyte was immediately poured into the case 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, 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 methods similar to those of the battery of Example 1. binder The raw materials and reaction conditions for the preparation were adjusted, and 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 on the intermediate polymer derived from the first monomer, acrylonitrile, was converted to a -COOLi group by a modification reaction.

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

[0134] In Example 4, the monomers used to produce 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 on the intermediate polymer derived from the first monomer, acrolein, were converted to -COOLi groups by a 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 groups of the ester groups derived from methyl acrylate, the first monomer, on the intermediate polymer were converted to -COONa groups 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 through 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, binder In the process of producing methyl acrylate, after the modification reaction is completed, 5% acetic acid solution is added dropwise to adjust the pH of the product in the reactor to 2-3, followed by stirring for 2 hours. The product is then dried, washed three times with deionized water, and dried again. Through the modification reaction, the functional groups of the ester groups derived from the first monomer, methyl acrylate, on the intermediate polymer are converted to -COOH groups.

[0142] In Example 10, the molar ratio of ethylene to methyl acrylate was 6:4.

[0143] In Example 11, the molar ratio of ethylene to methyl acrylate was 5:5.

[0144] In Example 12, the molar ratio of ethylene to methyl acrylate was 4:6.

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

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

[0147] In Example 15, the molar ratio of ethylene to methyl acrylate 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 modification reaction in Example 24 was 60°C, and the reaction time was 0.2 hours. The reaction temperature of the modification reaction in Example 25 was 60°C, and the reaction time was 1 hour. The reaction temperature of the modification reaction in Example 26 was 60°C, and the reaction time was 8 hours. The reaction temperature of the modification reaction in Example 27 was 60°C, and the reaction time was 10 hours. The reaction temperature of the modification reaction in Example 28 was 60°C, and the reaction time was 24 hours. Other parameters in Examples 24-28 are consistent with Example 1.

[0156] Comparative Examples 1-5 are the results of directly reacting the intermediate polymers prepared in Examples 1-5, respectively. binder and without carrying out a modification reaction of the intermediate polymer with an alkaline substance, Comparative Examples 6-11 were prepared by directly reacting the intermediate polymers prepared in Examples 10-15, respectively. binder The intermediate polymer was not converted with an alkaline substance, and the specific parameters were as shown in Table 1.

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

[0158] Furthermore, the performance of the electrodes and batteries obtained in Examples 1 to 28 and Comparative Examples 1 to 11 was measured by the following method. 1.Method for measuring weight-average molecular weight

[0159] Obtained in Example 1 binder The product was vacuum-dried in a vacuum oven at 80°C for 12 hours, and 0.1 g of the solution was dissolved in 20 mL of N-methylpyrrolidone. The solution was filtered using a 10 μm pore size filter membrane, and 5 mL of the solution was used to measure the weight-average molecular weight by gel permeation chromatography. The detector used was a differential refractive index detector, and the standard substance was polystyrene. 2. 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 employed. binder Mass percentage W of metal element M in M The decomposition method is the plate method, and the decomposition solvent is concentrated nitric acid. binder The sample powder was washed three times with deionized water to remove free metal ions adsorbed on the surface, and then the product was dried and subjected to 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 teeth, binder is the molecular weight of the structural unit of M M is the molecular weight of the M element.

[0163] When M in formula II is H or NH4, first binder It is necessary to carry out ion substitution treatment to replace M with Na, and the specific plan is as follows: binder The powder was placed in 200 mL of a 5 wt% aqueous solution of sodium chloride and stirred at 40 °C for 1 h to carry out ion exchange. After that, it was filtered and the resulting powder was washed three times with deionized water to remove sodium ions adsorbed on the surface. After that, the product was dried and the mass percentage of sodium element W was 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 (%)=WNa *M 総 / twenty three In the formula, M 総 teeth, binder is the molecular weight of the structural unit. 3. Molar content of the second structural unit

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

[0167] The measurement process of the plate swelling rate is as follows: the positive plate prepared in the examples or comparative examples is cold-pressed, and then cut out to an area of ​​5*5 cm, weighed, and recorded as m0; the corresponding battery in the examples or comparative examples is stored at 60°C for 7 days, and then a 5*5 cm piece is cut out from the positive plate, and the remaining electrolyte on the surface is immediately wiped off, 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 for the DC impedance of a battery is as follows: At 25°C, a battery manufactured in the example or comparative example was charged to 4.3 V at a constant current of 1 / 3 C, and then further charged at a constant voltage of 4.3 V until the current reached 0.05 C. After 5 minutes of standing, the voltage V1 was recorded. The battery was then discharged at 1 / 3 C for 30 seconds, and the voltage V2 was recorded. The internal resistance DCR of the battery after the first cycle was calculated as (V2 - V1) / 1 / 3 C. 6.Battery capacity maintenance rate measurement

[0170] The battery capacity retention measurement process is as follows: At 25°C, the fabricated battery was charged to 4.3V at a constant current of 1 / 3C, then further charged at a constant voltage of 4.3V until the current reached 0.05C, left for 5 minutes, and then discharged to 2.8V at 1 / 3C. The resulting capacity was recorded as the initial capacity C0. The same battery was repeatedly subjected to the above steps, and the discharge capacity Cn of the battery after the nth cycle was recorded. The battery capacity retention rate Pn after each cycle was calculated as Cn / C0*100%, where the values ​​of the 100 points P1, P2...P100 are the ordinate and the corresponding cycle number is the abscissa. In this measurement process, the first cycle corresponds to n=1, the second cycle corresponds to n=2, and the 100th cycle corresponds to n=100. The battery capacity retention data in Table 2 for the Examples and Comparative Examples were measured after 100 cycles under the above measurement conditions, i.e., the value 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. JPEG0007739457000005.jpg229133JPEG0007739457000006.jpg226130JPEG0007739457000007.jpg226134 JPEG0007739457000008.jpg228137JPEG0007739457000009.jpg229132JPEG0007739457000010.jpg228134

[0172] In Examples 1 to 28, binder and binder is a polymer containing structural units shown in Formula I and Formula II, JPEG0007739457000011.jpg45170 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 electrode plate swelling rates were all reduced, the internal resistance of the battery was reduced, 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 was 0.1% to 60% based on the total number of moles of all structural units in the polymer. Compared to Comparative Examples 1 to 11, the electrode plate swelling rate was reduced in all cases, the internal resistance of the battery was reduced, and the capacity retention rate was increased. In Examples 1 to 28, when the molar content of the structural unit shown in Formula II was 10% to 40%, the decrease in the internal resistance of the battery was more significant and the cycle capacity retention rate was higher.

[0174] In Examples 1 to 28, the polymers contained 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 were different. Compared with Comparative Examples 1 to 11, the electrode plate swelling ratios were 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 was 20% to 90% based on the total number of moles of all structural units in the polymer. Compared to Comparative Examples 1 to 11, the electrode plate swelling rate was reduced in all cases, the internal resistance of the battery was reduced, and the cycle capacity retention rate was increased. In Example 15, when the ratio of structural units derived from ethylene monomers in the polymer was 90%, the electrode plate swelling rate was lower, but the electrode plate adhesion was poor and the cycle stability of the battery was reduced, resulting in a decrease in the cycle capacity retention rate of the battery. When the molar content of the second structural unit was 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-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. Furthermore, various modifications that a person skilled in the art can make to the embodiments without departing from the spirit of the present application, and other forms constructed by combining some of the components of the embodiments, are also included within the scope 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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