Positive electrode slurry, positive electrode plate, and secondary battery including the positive electrode plate

Abstract

A positive electrode slurry is provided that includes a polyether phosphate ester, the polyether phosphate ester comprising at least [C1] The polyether phosphate ester is added to the positive electrode plate to increase the coating weight of the positive electrode plate, thereby improving the energy density of the battery.

Description

Technical Field

[0001] The present application relates to the field of lithium battery technology, and particularly to a positive electrode plate containing polyether phosphate ester. In addition, the present application further relates to a secondary battery including the positive electrode plate, a battery pack and a battery module including the secondary battery, and a power consumption device.

Background Art

[0002] In recent years, with the increasingly wide application range of lithium-ion batteries, lithium-ion batteries have been widely applied in a plurality of fields such as energy storage power systems such as hydraulic power, thermal power, wind power and solar power plants, and electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. Due to the leapfrog development of lithium-ion batteries, higher requirements are also demanded for the improvement of their energy density and cost reduction.

[0003] Currently, one of the effective ways to improve the energy density of lithium-ion batteries is to improve the coating weight of the positive electrode plate. However, if the coating weight of the positive electrode plate is improved, there are significant risks during the manufacture of the electrode plate. Since the positive electrode slurry characteristics and the electrode plate characteristics directly affect the manufacture of battery cells, the improvement of the coating weight of the positive electrode plate makes it difficult to manufacture battery cells.

[0004] Therefore, the positive electrode plate still needs to be improved.

Summary of the Invention

[0005] The present application has been made in view of the above problems, and its purpose is to provide a positive electrode slurry containing a specific polyether phosphate ester, a positive electrode plate manufactured using the positive electrode slurry, or a positive electrode plate containing the positive electrode slurry.

[0006] Therefore, the first aspect of the present application provides a positive electrode slurry, which includes a positive electrode active material and a polyether phosphate ester, wherein the polyether phosphate ester is at least [Chemical formula] comprises a structural unit and a structural unit (IV) phosphate ester group, wherein A is hydrogen, a halogen or a halogenated alkyl group, said halogen being optionally fluorine, chlorine or bromine, and said A being optionally hydrogen or a fluoromethyl group, B is a hydroxyl group, R, OR, or ROR', where R and R' are each independently a straight-chain or branched-chain alkyl group containing 1 to 8 carbons, and optionally, B is a methyl group, an ethyl group or an ethoxymethyl group, E is a phenyl group, a phenyl group substituted with an alkyl group, an etherified phenyl group or a halogenated phenyl group, and said E is optionally a phenyl group or a fluorophenyl group.

[0007] In any embodiment of the present application, after adding the polyether phosphate ester to the positive electrode slurry, the resulting lithium-ion battery has a significantly improved energy density. Also, due to the improvement of the positive electrode plate, the usage amount of battery cells can be saved, thereby reducing the total material cost of battery cells.

[0008] In some embodiments, the number average molecular weight range of the polyether phosphate ester is 10,000 to 80,000, the selectable range is 10,000 to 60,000, and the further selectable range is 30,000 to 50,000.

[0009] If the molecular weight is too small, the stability of the positive electrode slurry is low, physical gelation is likely to occur, the positive electrode film resistance is deteriorated, and the battery performance is also adversely affected. If the molecular weight is too large, it is disadvantageous for the dispersion of the polyether phosphate ester in the positive electrode slurry. Therefore, the number average molecular weight of the polyether phosphate ester needs to be controlled within the above range.

[0010] The molar ratio of structural unit (I) is 0 to 75 mol% based on the total molar amount of structural units (I) to (IV), the molar ratio of structural unit (II) is 0 to 65 mol%, the molar ratio of structural unit (III) is 5 to 65 mol%, and the molar ratio of structural unit (IV) is 4 to 15 mol%, where the molar ratios of structural unit (I) and structural unit (II) are not zero simultaneously.

[0011] The molar ratios of the above structural units (I) to (IV) ensure that sufficient hydrogen bonds and an appropriate amount of covalent bonds are formed between the obtained polyether siloxane and the positive electrode active material, current collector, etc., and further ensure the stability in the manufacturing process of the positive electrode plate, as well as the flexibility of the positive electrode plate and the dispersibility of various positive electrode materials, so as to improve the energy density of the battery.

[0012] In some embodiments, the weight ratio of the polyether phosphate ester to the positive electrode active material is 0.0005 to 0.030, the selectable range is 0.001 to 0.02, the further selectable range is 0.001 to 0.01, and the most selectable range is 0.001 to 0.007.

[0013] When the value of this ratio is too small, the positive electrode plate will crack at high coating weights, and when the value of this ratio is too large, it will have an adverse effect on battery performance.

[0014] In some embodiments, the positive electrode active material is selected from at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium nickelate, or a mixture thereof.

[0015] When the positive electrode active material is at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium nickelate or a mixture thereof, the addition of the polyether phosphate ester can better realize effects such as improving the flexibility of the electrode plate and increasing the maximum coating weight of the electrode plate. In some embodiments, the range of the gelation factor G of the positive electrode slurry is 0 to 1, and the selectable range is 0 to 0.3. Here, G = (m1 - m2) / m1. When G = 0 to 0.3, it is determined that the slurry does not gel. When G > 0.3, it is determined that it is a gel. m1 is the mass of the positive electrode slurry obtained after filtering 2 kg of the initial positive electrode slurry for 10 minutes using a 100-mesh filter screen. m2 is the mass of the positive electrode slurry obtained after filtering 2 kg of the positive electrode slurry left standing for 48 hours for 10 minutes using a 100-mesh filter screen. Here, The positive electrode slurry used when measuring m1 and the positive electrode slurry used when measuring m2 are the same lot of positive electrode slurry.

[0016] The closer the mass of the positive electrode slurry obtained after filtering the positive electrode slurry left standing for 48 h is to the mass obtained initially, the smaller the G value, indicating that the slurry is less likely to gel and the slurry state is better. The positive electrode slurry described in this application has excellent gelation performance.

[0017] The second aspect of this application provides a positive electrode plate, which a positive electrode current collector, and It includes a positive electrode film layer located on at least one surface of the positive electrode current collector, and the positive electrode film layer contains the positive electrode slurry described in the first aspect of the present application. As described above, by adding the polyether phosphate ester, the present application allows for an improvement in the maximum coating weight in the positive electrode plate. This is also manifested in terms of an increase in the maximum weight of the positive electrode film layer. In some embodiments, the range of the mass per unit area of the positive electrode film layer on the electrode plate is 13 - 43 mg / cm 2 and the selectable range is 22 - 31 mg / cm 2 and the further selectable range is 22 - 29 mg / cm 2 wherein the mass is the mass of the positive electrode film layer on one side of the electrode plate. If there are positive electrode film layers on both surfaces of the positive electrode plate, the range of the mass per unit area of the positive electrode film layer on the electrode plate is twice the above range, that is, the range is 26 - 86 mg / cm 2 and the selectable range is 44 - 62 mg / cm 2 and the further selectable range is 44 - 58 mg / cm 2 wherein the mass is the mass of the positive electrode film layer on two surfaces of the electrode plate.

[0018] If the weight of the positive electrode film layer per unit area of the electrode plate is too small, the uniformity of the electrode plate is low. If the weight of the positive electrode film layer per unit area of the electrode plate is too large, the electrode plate will severely crack during the coating process and it will be impossible to continue production. The present application limits the weight of the positive electrode film layer per unit area of the electrode plate within the above range to ensure that the highest effect is achieved within this range.

[0019] The positive electrode plate described in the present application has very excellent flexibility and the coating weight has been significantly improved. Applying the positive electrode plate to a secondary battery, for example, directly adding it to the positive electrode slurry during manufacturing can significantly improve the energy density of the battery.

[0020] In some embodiments, the positive electrode film layer includes two sub-layers that are parallel to the positive electrode current collector and laminated to each other. Here, the range of the ratio of the weight content of the polyether phosphate ester in the sub-layer closest to the positive electrode current collector to the weight content of the polyether phosphate ester in the sub-layer farthest from the positive electrode current collector is 0 to 60, and the selectable range is 0.1 to 30.

[0021] When the coating weight is 23 mg / cm 2 When it is as above, compared with a single thick coating, coating in two steps can reduce the material cost of the flexibility additive, and the polyether phosphate ester described in the present application can function better without affecting the electrical performance.

[0022] In some embodiments, when measuring the flexibility of the positive electrode plate by the winding pin described in the present application, when the diameter R of the winding pin is ≤ 3.0 mm, no crack occurs in the positive electrode plate, or when the diameter R of the winding pin is 3.0 mm, cracks occur in the positive electrode plate, but when the diameter R of the winding pin is 4.0 mm, there are no cracks.

[0023] After adding the polyether phosphate ester described in the present application, by reducing the cold pressing pressure, cracks can be reduced and the risk of tape breakage can be reduced, and furthermore, the flexibility of the electrode plate can be improved.

[0024] In some embodiments, the range of the improvement rate I of the infiltration rate of the positive electrode plate is 2 to 20%, and the selectable range is 6 to 15%. Here, I = (I2 - I1) / I1 × 100%, I2 is the infiltration rate of the positive electrode plate in the electrolyte, I1 is the infiltration rate of the positive electrode plate without the polyether phosphate ester in the electrolyte. Here, the positive electrode plate used during the measurement of I1 is the same as the positive electrode plate used during the measurement of I2. The positive electrode plate used during the measurement of I1 does not contain the polyether phosphate ester, while the positive electrode plate used during the measurement of I2 contains the polyether phosphate ester, and they differ only in this regard.

[0025] When the wettability of the electrode plate is high, by achieving good wetting and liquid retention properties with respect to the electrolyte, effective wetting of the battery cell electrode plate can be realized, insufficient wetting of the electrode plate can be avoided, and by improving the liquid injection efficiency of the battery cell and the wettability of the electrode plate during the cycle process, the performance of the battery product can be effectively improved. The positive electrode plate described in this application has excellent wetting performance in the electrolyte.

[0026] The third aspect of this application is the 2 aspect described in this application Positive to provide a secondary battery including an electrode plate.

[0027] The fourth aspect of this application is to provide a battery module including the secondary battery described in the 3 aspect of this application.

[0028] The fifth aspect of this application is to provide a battery pack including the battery module described in the 4 aspect of this application.

[0029] The sixth aspect of this application is to provide a power consumption device including at least one of the secondary battery described in the third aspect of this application, the battery module described in the fourth aspect of this application, or the battery pack described in the fifth aspect of this application.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0031] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the negative electrode plate of the present application and its manufacturing method, positive electrode plate, secondary battery, battery module, battery pack, and electrical device will be described in detail. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of well-known matters and duplicate descriptions of actually identical structures may be omitted. This is to avoid the following description becoming unnecessarily long and to make it easily understandable to those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not for limiting the subject matter described in the claims.

[0032] The "range" disclosed in this application is limited in the form of a lower limit and an upper limit. A predetermined range is limited by selecting one lower limit and one upper limit that define the boundaries of the specific range. The range thus limited may or may not include the end values and may be arbitrarily combined, that is, any lower limit and any upper limit may be combined to form one range. For example, when ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also understood to be anticipated. In addition, when the minimum range values 1 and 2, and the maximum range values 3, 4, and 5 are listed, all of the ranges of 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 6 can be assumed. In this application, unless otherwise stated, the numerical range "a - b" is a shortened expression representing all combinations of real numbers between a and b, where both a and b are real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are listed in this specification, and "0 - 5" is merely an abbreviated representation of these numerical combinations. Also, when it is described that a certain parameter is an integer ≧2, this is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] Unless otherwise specifically described, all embodiments and selectable embodiments of this application may be combined with each other to form a new technical solution.

[0034] Unless otherwise specifically described, all technical features and selectable technical features of this application may be combined with each other to form a new technical solution.

[0035] Unless otherwise specified, all steps of this application may be performed sequentially, randomly, or optionally, sequentially. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the fact that the method mentioned above further includes 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 steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0036] Unless otherwise specified, the terms "comprising" and "including" mentioned in this application represent an open type and may also be a closed type. For example, the above "comprising" and "including" may further comprise or include other components not listed, or may only comprise or include the listed components.

[0037] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" represents "A, B, or both A and B". More specifically, any one of the following conditions satisfies the condition of "A or B". A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), or both A and B are true (or exist).

[0038] Concept of the invention For lithium-ion batteries, it has become a trend to improve the energy density. One way to improve the energy density is to increase the coating weight of the positive electrode plate. However, as discovered by the inventor of the present application, as shown in FIG. 2, during the coating process of a general positive electrode slurry, due to the action of capillary tension during or after solvent evaporation, the positive electrode plate will crack, and the crack will further propagate to cause a large-area crack. In addition, in this process, there is also a phenomenon that the edge of the electrode plate curls. Also, because the positive electrode plate is hard and brittle, it will break during the cold pressing process and the inner ring will break severely during the winding process. Based on this, the inventor of the present application designed and synthesized a flexible polymer material, polyether phosphate ester. By adding this flexible material, the coating weight is increased, the coating quality is improved, the risk problems during the cold pressing and winding processes are solved, and the total cost of the materials used in battery manufacturing is reduced.

[0039] Therefore, a first aspect of the present application provides a positive electrode slurry containing a positive electrode active material and polyether phosphate ester, and the polyether phosphate ester includes at least

Chemical formula

[0040] In the polyether phosphate ester described in the present application, the structural unit (IV) exists as a terminal group.

[0041] Optionally, in some embodiments, the polyether phosphate ester is (a) ethylene oxide which is unsubstituted or substituted with a halogen or a halogenated C 1-8 alkyl group, and (b) ethylene oxide substituted with a hydroxyl group, a hydroxyalkyl group, R, OR, or ROR', where R and R' are each independently a C 1-8 alkyl group, and the alkyl group in the hydroxyalkyl group is a C 1-8 alkyl group, and (c) ethylene oxide substituted with a halogenated phenyl group, a halogenated alkylphenyl group or a phenyl group, and (d) a polymerization product of a phosphorus agent which is diphosphorus pentoxide, wherein, based on the total molar amount of components (a) to (d), the molar ratio of component (a) is 0 to 75 mol%, the molar ratio of component (b) is 0 to 65 mol%, the molar ratio of component (c) is 5 to 65 mol%, and the molar ratio of component (d) is 4 to 15 mol%, wherein components (a) and (b) are not zero simultaneously.

[0042] In some embodiments, optionally, component (a) is selected from ethylene oxide, epifluorohydrin, epichlorohydrin, epibromohydrin.

[0043] In some embodiments, optionally, component (b) is selected from propylene oxide, ethyl glycidyl ether, isopropyl glycidyl ether, butyl glycidyl ether, isopropyl glycidyl ether, butylene oxide, 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxydecane, 1,2-epoxy-3-methylbutane, glycidol.

[0044] In some embodiments, optionally, component (c) is selected from styrene oxide and phenyl group.

[0045] In the present application, C 1-8 The alkyl group is a linear or branched alkyl group containing 1 to 8 carbons, and the linear or branched alkyl group containing 1 to 8 carbons is, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, isopropyl group, isobutyl group, t-butyl group, isopentyl group, t-pentyl group, neopentyl group, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 2,2-dimethylhexane, 3,3-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,4-dimethylhexane, 3-ethylhexane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane, 2,3,3-trimethylpentane, 2,3,4-trimethylpentane, 2-methyl-3-ethylpentane, 3-methyl-3-ethylpentane, 2,2,3,3-tetramethylbutane, and may be selected from them.

[0046] In the present application, C 1-8 The alkenyl group is a linear or branched alkenyl group containing 1 to 8 carbons, and it may include, but is not limited to, vinyl group, propenyl group, allyl group, 1-methylprop-2-en-1-yl, 2-methylprop-2-en-1-yl, but-2-en-1-yl, but-3-en-1-yl, 1-methylbut-3-en-1-yl, and 1-methylbut-2-en-1-yl.

[0047] In the present application, the alkyl substituent may be a straight-chain or branched-chain alkyl group containing 1 to 8 carbons, which may optionally be selected from a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group. Optionally, the alkyl substitution is mono-substitution or di-substitution. In some embodiments, the phenyl group substituted with an alkyl group may be selected from, for example, 3,4-dimethylphenyl, 2-methylphenyl, 3,5-dimethylphenyl, and 4-(2-methylpropyl)phenyl.

[0048] In the present application, the alkyl group in the alkyl halide group may optionally be a straight-chain or branched-chain alkyl group containing 1 to 8 carbons. For example, the alkyl group in the alkyl halide group may optionally be selected from a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, an isopropyl group, an isobutyl group, a t-butyl group, an isopentyl group, a t-pentyl group, a neopentyl group, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 2,2-dimethylhexane, 3,3-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,4-dimethylhexane, 3-ethylhexane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane, 2,3,3-trimethylpentane, 2,3,4-trimethylpentane, 2-methyl-3-ethylpentane, 3-methyl-3-ethylpentane, and 2,2,3,3-tetramethylbutane. The halogen in the alkyl halide group may be selected from fluorine, chlorine, bromine, and iodine.

[0049] In the present application, the ether substituent may be a linear or branched alkoxy group containing 1 to 8 carbons, and optionally, is selected from a methoxy group, an ethoxy group, a propoxy group, or a butoxy group. In some embodiments, the etherified phenyl group may be selected from, for example, 4-methoxyphenyl, 3-methoxyphenyl, and the like.

[0050] In the present application, the halogenated alkylphenyl group refers to a phenyl group substituted with a halogenated alkyl group, where the halogenated alkyl group refers to an alkyl group substituted with a halogen, where the alkyl group is C 1-8 alkyl group.

[0051] In the present application, the halogenated phenyl group represents a phenyl group substituted with a halogen. In the present application, the halogen may be selected from fluorine, chlorine, bromine, and iodine. In some embodiments, the halogenated phenyl group may be selected from, for example, 4-fluorophenyl, 2-fluorophenyl, 2,6-difluorophenyl, 4-(trifluoromethyl)phenyl, 4-chlorophenyl, 3-chlorophenyl, 4-bromophenyl, 3-bromophenyl, or 2-bromophenyl.

[0052] In the structural formula (1) of the polyether phosphate ester described in the present application, the structural unit (I) (or the structural unit formed by the component (a)) can improve the ability of the polymer to form hydrogen bonds with the surface of the positive electrode particles, conductive carbon, and aluminum foil. The structural unit (II) (or the structural unit formed by the component (b)) can extend the branched chain of the molecule and ensure that the polyether phosphate ester forms a covalent bond with the surface of the positive electrode particles, conductive carbon, and aluminum foil surface, thereby ensuring that the positive electrode particles do not move during the coating process. The structural unit (III) (or the structural unit formed by the component (c)) can improve the rigidity of the polyether phosphate ester, endow it with certain strength and hardness, thereby improving the oxidation resistance and electrolyte resistance of the polyether phosphate ester. At the same time, the benzene ring forms an interaction with the surface of the positive electrode particles to ensure the dispersibility of the polyether phosphate ester. The phosphate ester end group plays the role of an anchor and can uniformly and stably disperse the positive electrode active component particles in the NMP medium as a wetting dispersant.

[0053] As shown in FIG. 1, the polyether phosphate ester of the present application is a long flexible chain, which may form a hydrogen bond with the positive electrode active material and the positive electrode current collector through the structural unit (I) (or the structural unit formed by the component (a)), or may also form a covalent bond with the positive electrode active material and the positive electrode current collector through the structural unit (II) (or the structural unit formed by the component (b)), and may also interact with the surface of the positive electrode active material particles through the benzene ring in the structural unit (III) (or the structural unit formed by the component (c)). In addition, a covalent bond may also be formed between the polyether phosphate esters of the present application. Therefore, by adding a flexibility additive, that is, the polyether phosphate ester described in the present application, to the positive electrode slurry, the stability of the positive electrode slurry can be improved, the flexibility of the positive electrode plate can be improved, and the coating weight of the positive electrode plate can be improved by ensuring the dispersibility of each substance in the positive electrode plate. As shown in FIG. 3, after adding the polyether siloxane, the positive electrode slurry of the present application did not crack during the coating process. As shown in FIG. 4, after adding the polyether phosphate ester of the present application, the maximum coating thickness (weight) of the positive electrode plate was significantly improved.

[0054] The polyether phosphate ester described in the present application may be obtained by general technical means in the art or may be produced by the following steps. Step 1: Generate a polyether from an alkylene oxide monomer under alkaline conditions. Here, optionally, the solvent used is one or more of dimethyl sulfoxide, acetone, and diethyl ether. Optionally, the basic substance that can be added during the production is, for example, NaOH, KOH, or dicyclohexylcarbodiimide. Optionally, the reaction temperature range of this reaction is 80 to 160 °C, the reaction time range is 3 to 7 h, optionally, during the reaction process, the stirring speed range is 1000 to 2000 revolutions per minute, and optionally, after the reaction is completed, a vacuum distillation purification step is performed.

[0055] Step 2: React the polyether in step (1) with a phosphorus agent to produce a polyether phosphate ester. Here, optionally, the reaction is carried out in a reaction kettle. Optionally, the reaction temperature range of this reaction is 60 - 130 °C. Optionally, the reaction time range is 2 - 15 h. Optionally, stirring is performed during the reaction process, and the stirring time range is optionally 1 - 10 h. The stirring speed range is optionally 1000 - 2000 r / min. Optionally, after the reaction is completed, a vacuum distillation and purification step is carried out.

[0056] In some embodiments, the pH range of the positive electrode slurry described in this application at 20 - 60 °C is about 6 - 9. The pH value is tested by common means in the art.

[0057] In any embodiment of this application, after adding the polyether phosphate ester to the positive electrode slurry, the obtained lithium-ion battery has an obviously improved energy density. Also, due to the improvement of the positive electrode plate, the usage amount of battery cells can be saved, thereby reducing the total material cost of battery cells.

[0058] In some embodiments, the number average molecular weight range of the polyether phosphate ester is 10,000 - 80,000, the selectable range is 10,000 - 60,000, and the further selectable range is 30,000 - 50,000.

[0059] The size of the molecular weight affects the processing performance of the positive electrode plate. When the molecular weight is small, the flexibility of the positive electrode plate is not obviously improved, and the phenomenon of cracking still occurs during coating, and there may be problems such as cold press tape breakage and winding breakage. When the molecular weight is too small, the stability of the positive electrode slurry is low, and the physical gelation phenomenon is likely to occur, deteriorating the positive electrode film resistance and also having an adverse effect on battery performance. When the molecular weight is too large, it is disadvantageous for the dispersion of the polyether phosphate ester in the positive electrode slurry. Therefore, the number average molecular weight of the polyether phosphate ester needs to be controlled within the above range.

[0060] In some embodiments, in the polyether phosphate ester described in the present application, with respect to the total molar amount of structural unit (I) to structural unit (IV), the molar ratio of structural unit (I) is 0 to 75 mol%, the molar ratio of structural unit (II) is 0 to 65 mol%, the molar ratio of structural unit (III) is 5 to 65 mol%, and the molar ratio of structural unit (IV) is 4 to 15 mol%, where the molar ratios of structural unit (I) and structural unit (II) are not simultaneously zero.

[0061] Optionally, with respect to the total molar amount of structural unit (I) to structural unit (IV), the molar ratio of structural unit (I) (or with respect to the total molar amount of components (a) to (d), the molar ratio of component (a)) may be about 0 mol%, about 5 mol%, about 10 mol%, about 14 mol%, about 15 mol%, about 17 mol%, about 20 mol%, about 25 mol%, about 26 mol%, about 27 mol%, about 28 mol%, about 29 mol%, about 30 mol%, about 31 mol%, about 32 mol%, about 33 mol%, about 35 mol%, about 40 mol%, about 42 mol%, about 45 mol%, about 50 mol%, about 55 mol%, about 60 mol%, about 62 mol%, about 65 mol%, about 68 mol%, about 70 mol%, about 72 mol% or about 75 mol%. Or, the molar ratio of structural unit (I) is within any range consisting of any of the above values.

[0062] Optionally, with respect to the total molar amount of structural unit (I) to structural unit (IV), the molar ratio of structural unit (II) (or with respect to the total molar amount of components (a) to (d), the molar ratio of component (b)) may be about 0 mol%, about 5 mol%, about 10 mol%, about 14 mol%, about 15 mol%, about 17 mol%, about 20 mol%, about 22 mol%, about 25 mol%, about 30 mol%, about 31 mol%, about 35 mol%, about 40 mol%, about 42 mol%, about 43 mol%, about 45 mol%, about 50 mol%, about 52 mol%, about 53 mol%, about 54 mol%, about 55 mol%, about 56 mol%, about 58 mol%, about 60 mol%, about 63 mol%, about 65 mol%. Or, the molar ratio of structural unit (II) is within any range consisting of any of the above values.

[0063] Optionally, based on the total molar amount of structural unit (I) to structural unit (IV), the molar ratio of structural unit (III) (or based on the total molar amount of components (a) to (d), the molar ratio of component (c)) is about 5 mol%, about 6 mol%, about 7 mol%, about 9 mol%, about 10 mol%, about 11 mol%, about 15 mol%, about 20 mol%, about 23 mol%, about 24 mol%, about 25 mol%, about 26 mol%, about 30 mol%, about 31 mol%, about 33 mol%, about 35 mol%, about 40 mol%, about 45 mol%, about 50 mol%, about 55 mol%, about 59 mol%, about 60 mol%, about 61 mol% or about 65 mol%. Or, the molar ratio of structural unit (III) is within any range consisting of any of the above values.

[0064] Optionally, based on the total molar amount of structural unit (I) to structural unit (IV), the molar ratio of structural unit (IV) (or based on the total molar amount of components (a) to (d), the molar ratio of component (d)) is about 4 mol%, about 5 mol%, about 6 mol%, about 7 mol%, about 8 mol%, about 9 mol%, about 10 mol%, about 11 mol%, about 12 mol%, about 13 mol%, about 14 mol% or about 15 mol%. Or, the molar ratio of structural unit (IV) is within any range consisting of any of the above values.

[0065] In this application, "about" a numerical value represents a range, namely a range of ±3% of that numerical value.

[0066] The molar ratios of the above structural units (I) to (IV) (or components (a) to (d)) ensure that sufficient hydrogen bonds and an appropriate amount of covalent bonds are formed between the obtained polyether phosphate ester and the positive electrode active material, current collector, etc., and further ensure the stability in the manufacturing process of the positive electrode plate, as well as the flexibility of the positive electrode plate and the dispersibility of various positive electrode materials, thereby improving the energy density of the battery.

[0067] In some embodiments, the weight ratio of the polyether phosphate ester to the positive electrode active material is 0.0005 to 0.030, the selectable range is 0.001 to 0.02, the further selectable range is 0.001 to 0.01, and the most selectable range is 0.001 to 0.007.

[0068] The weight ratio of the polyether phosphate ester to the positive electrode active material is 0.0005 to 0.030. If the ratio is too small, the positive electrode plate will crack at high coating weights, and if the ratio is too large, it will have an adverse effect on battery performance.

[0069] In some embodiments, the positive electrode active material is selected from at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium nickelate, or a mixture thereof.

[0070] Theoretically, for the positive electrode of a secondary battery, this application may employ any positive electrode active material for batteries that is well known in the art. As an example, the positive electrode active material may include at least one material of olivine-structured lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery 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 are 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 (which may also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn0.3 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 0.05 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.

[0071] However, the inventors of the present application have discovered that when the positive electrode active material is at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobalt oxide, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium nickel oxide, or a mixture thereof, the addition of the polyether phosphate ester can better realize effects such as improving the flexibility of the electrode plate and increasing the maximum coating weight of the electrode plate.

[0072] In some embodiments, the gelation factor G of the positive electrode slurry is in the range of 0 to 1, with a selectable range being 0 to 0.3; Here, G=(m1-m2) / m1, and when G=0 to 0.3, it is determined that the slurry does not gel, and when G>0.3, it is determined that the slurry gels. m1 is the mass of the positive electrode slurry obtained after filtering 2 kg of the initial positive electrode slurry for 10 minutes using a 100-mesh filter screen, m2 is the mass of the positive electrode slurry obtained after filtering 2 kg of the positive electrode slurry left standing for 48 hours for 10 minutes using a 100-mesh filter screen, where the positive electrode slurry used when measuring m1 and the positive electrode slurry used when measuring m2 are from the same lot of positive electrode slurry.

[0073] The closer the mass of the positive electrode slurry obtained after filtering the positive electrode slurry left standing for 48 h is to the initially obtained mass, the smaller the G value, the less likely the slurry is to gel, and the better the slurry state. The positive electrode slurry described in this application has excellent gelling performance.

[0074] The second aspect of this application provides a positive electrode plate, which includes a positive electrode current collector, and a positive electrode film layer located on at least one surface of the positive electrode current collector, and the positive electrode film layer includes the positive electrode slurry described in the first aspect of this application. As described above, by adding the polyether phosphate ester, this application allows an improvement in the maximum coating weight in the positive electrode plate. This also appears in terms of the increase in the maximum weight of the positive electrode film layer. In some embodiments, the range of the mass per unit area of the positive electrode film layer on the electrode plate is 13 - 43 mg / cm 2 and the selectable range is 22 - 31 mg / cm 2 and the further selectable range is 22 - 29 mg / cm 2 and the mass is the mass of the positive electrode film layer on one side of the electrode plate. If there are positive electrode film layers on both surfaces of the positive electrode plate, the range of the mass per unit area of the positive electrode film layer on the electrode plate is twice the above range, that is, the range is 26 - 86 mg / cm 2 and the selectable range is 44 - 62 mg / cm 2 and the further selectable range is 44 - 58 mg / cm 2 and the mass is the mass of the positive electrode film layer on both surfaces of the electrode plate.

[0075] In some embodiments, after adding the polyether phosphate ester described in the present application, the coating weight per unit area on the positive electrode plate can reach up to 41 mg / cm 2 Optionally, the coating weight per unit area on the positive electrode plate may be in the range of 23 to 41 mg / cm 2 as well.

[0076] If the weight of the positive electrode film layer per unit area of the electrode plate is too small, the uniformity of the electrode plate is low. If the weight of the positive electrode film layer per unit area of the electrode plate is too large, the electrode plate will severely crack during the coating process and it will be impossible to continue production. The present application limits the weight of the positive electrode film layer per unit area of the electrode plate within the above range to ensure that the highest effect is achieved within this range.

[0077] The positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0078] In the lithium-ion battery of the present application, the positive electrode current collector may adopt a metal foil sheet or a composite current collector. For example, as the metal foil sheet, an aluminum foil may be adopted. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as substrates of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0079] In the positive electrode plate, the mass content of the positive electrode active material in the positive electrode film layer is 90 to 97% with respect to the positive electrode film layer. This content may be measured by EDS. If the mass content is too small, the manufactured battery has a low energy density and cannot meet the demand for battery capacity. If the mass content is too large, there is a shortage of adhesive and conductive agent, leading to a decrease in battery performance.

[0080] In the positive electrode plate, the mass content of the adhesive in the positive electrode film layer is 2 to 5% with respect to the total mass of the positive electrode film layer. As an example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. In a conventional general positive electrode plate, an adhesive with a specific crystallinity or a similar crystallinity is used. After coating and drying to form a film, it is brittle, and under the action of stress, the electrode plate is prone to cracking. However, in the positive electrode plate of the present application, an adhesive with such a crystallinity is used, and the electrode plate does not crack.

[0081] In some embodiments, the positive electrode film layer may optionally further include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0082] In some embodiments, the positive electrode plate can be manufactured in the following manner. The above components for manufacturing the positive electrode plate, such as the positive electrode active material, conductive agent, adhesive, and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is applied onto a positive electrode current collector, and after processes such as drying and cold pressing, a positive electrode plate is obtained.

[0083] The positive electrode plate described in this application has extremely excellent flexibility and a significantly improved coating weight. When the positive electrode plate is applied to a secondary battery, for example, it can be directly added to the positive electrode slurry during manufacturing, and the energy density of the battery can be significantly improved.

[0084] In some embodiments, the positive electrode film layer includes two sub-layers that are parallel to the positive electrode current collector and laminated to each other. Here, the range of the ratio of the weight content of polyether phosphate ester in the sub-layer closest to the positive electrode current collector (i.e., the sub-layer close to the current collector) to the weight content of polyether phosphate ester in the sub-layer farthest from the positive electrode current collector (i.e., the sub-layer far from the current collector) is 0 to 60, and the selectable range is 0.1 to 30.

[0085] In some embodiments, the ratio of the weight content of polyether phosphate ester in the sub-layer closest to the positive electrode current collector to the weight content of polyether phosphate ester in the sub-layer farthest from the positive electrode current collector may be about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, about 20, about 21, about 22, about 23, about 24, about 25, about 26, about 27, about 28, about 29, about 30, about 31, about 32, about 33, about 34, about 35, about 36, about 37, about 38, about 39, about 40, about 41, about 42, about 43, about 44, about 45, about 46, about 47, about 48, about 49, about 50, about 51, about 52, about 53, about 54, about 55, about 56, about 57, about 58, about 59 or about 60. Or, the ratio of the weight content of polyether phosphate ester in the sub-layer closest to the positive electrode current collector to the weight content of polyether phosphate ester in the sub-layer farthest from the positive electrode current collector is within any range consisting of any of the above values.

[0086] In some optional embodiments, in the sub-layer close to the current collector, the weight ratio of the polyether phosphate ester to the cathode active material is 0 to 0.043, and in the sub-layer far from the current collector, the weight ratio of the polyether phosphate ester to the cathode active material is 0.0006 to 0.004.

[0087] When the coating weight is 23 mg / cm 2 When it is above, compared with a single thick coating, applying in multiple times can reduce the material cost of the flexibility additive, and the polyether phosphate ester described in the present application can function better without affecting the electrical performance.

[0088] Optionally, when manufacturing a cathode film layer having two sub-layers, first, two cathode slurries containing different amounts of polyether phosphate ester are manufactured, and then one slurry is applied to the current collector and dried, and then the other slurry is applied and dried.

[0089] In some embodiments, when measuring the flexibility of the cathode plate by a winding pin, When the diameter R of the winding pin is ≤ 3.0 mm, no crack occurs in the cathode plate, or When the diameter R of the winding pin is 3.0 mm, a crack occurs in the cathode plate, but when the diameter R of the winding pin is 4.0 mm, there is no crack.

[0090] In any embodiment, in the cathode plate described in the present application, when measuring the flexibility of the cathode plate by a winding pin , width A 50 mm × 100 mm long electrode plate sample is manufactured, wound around a specially ordered winding pin, and the crack situation of the electrode plate is observed by combining visual inspection and a microscope. The flexibility level is judged based on the following method, The diameter of the winding pin is R, When R ≤ 3.0 mm, no crack occurs in the electrode plate and the flexibility is first-class, When R = 3.0 mm, there is a crack, and when R = 4.0 mm, there is no crack, and the flexibility is second-class, When R = 4.0 mm, there are cracks. When R = 5.0 mm, there are no cracks, and the flexibility is grade three. When R = 5.0 mm, there are no cracks. When R = 6.0 mm, there are cracks, and the flexibility is grade four. When R = 6.0 mm, there are no cracks. When R = 7.0 mm, there are cracks, and the flexibility is grade five.

[0091] The manufacturing method of the winding pin is as follows.

[0092] Cut 60 mm from 304 stainless steel bars with general diameters of 3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm, and 7.0 mm respectively, and weld and fix them to a steel plate of 150 mm × 300 mm, then the above-mentioned winding pin can be obtained.

[0093] It shows that the smaller the diameter of the used winding pin and the higher the flexibility of the electrode plate so that the electrode plate does not crack. Conversely, the larger the diameter of the used winding pin and the more cracks in the electrode plate, the poorer the flexibility of the electrode plate.

[0094] In the cold pressing process, the formed hydrogen bonds are broken and the flexible main chain extends. However, after adding the polyether phosphate ester described in this application, by reducing the cold pressing pressure, the cracks can be reduced and the risk of tape breakage can be reduced.

[0095] In some embodiments, the range of the improvement rate I of the infiltration rate of the positive electrode plate is 2 - 20%, and the selectable range is 6 - 15%. Here, I = (I2 - I1) / I1 × 100%, I2 is the infiltration rate of the positive electrode plate in the electrolyte. I1 is the infiltration rate of the positive electrode plate without the polyether phosphate ester in the electrolyte. Here, the positive electrode plate used during the measurement of I1 is the same as the positive electrode plate used during the measurement of I2. The positive electrode plate used during the measurement of I1 does not contain the polyether phosphate ester, while the positive electrode plate used during the measurement of I2 contains the polyether phosphate ester, and this is the only difference.

[0096] When the wettability of the electrode plate is high, by achieving good wetting and liquid retention properties with respect to the electrolyte, effective wetting of the battery cell electrode plate can be realized, insufficient wetting of the electrode plate can be avoided, and by improving the liquid injection efficiency of the battery cell and the wettability of the electrode plate during the cycle process, the performance of the battery product can be effectively improved. The positive electrode plate described in the present application has excellent wetting performance in the electrolyte.

[0097] The third aspect of the present application provides a secondary battery, which includes the positive electrode plate described in the second aspect of the present application, or a positive electrode plate manufactured from the positive electrode slurry described in the first aspect of the present application. The energy density of the secondary battery described in the present application has been significantly improved. In addition, when manufacturing the battery, the total cost of the materials has been reduced.

[0098] Hereinafter, the secondary battery, battery module, battery pack, and power consumption device of the present application will be described.

[0099] Secondary battery Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charge and discharge process of the battery, active ions reciprocate between the positive electrode plate and the negative electrode plate for intercalation and deintercalation. The electrolyte plays a role of conducting ions between the positive electrode plate and the negative electrode plate. The separator is provided between the positive electrode plate and the negative electrode plate, mainly plays a role of preventing short - circuit between the positive and negative electrodes, and can allow ions to pass through.

[0100] [Positive electrode plate] The positive electrode plate described in the second aspect of the present application is adopted, or the positive electrode plate is manufactured from the positive electrode slurry described in the first aspect of the present application.

[0101] [Negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, and the negative electrode film layer contains a negative electrode active material.

[0102] As an example, the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is provided on either one or both of the two opposing surfaces of the negative electrode current collector.

[0103] In some embodiments, the negative electrode current collector may employ a metal foil sheet or a composite current collector. For example, as the metal foil sheet, a copper foil may be employed. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base. 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 polymer material base (such as a base of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0104] In some embodiments, the negative electrode active material may employ a negative electrode active material for batteries well-known in the art. As an example, the negative electrode active material may include at least one material among artificial graphite, natural graphite, soft carbon, hard carbon, phosphorus-based materials, tin-based materials, and lithium titanate. The phosphorus-based material may be selected from at least one of elemental phosphorus, phosphorus oxides, phosphorus-carbon composites, phosphorus-nitrogen composites, and phosphorus alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, in this application, it is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery may be used. These negative electrode active materials may be used alone or in combination of two or more.

[0105] In some embodiments, the negative electrode membrane layer optionally further includes an adhesive. The adhesive 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).

[0106] In some embodiments, the negative electrode membrane layer optionally further includes a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0107] In some embodiments, the negative electrode membrane layer optionally further includes other auxiliaries, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0108] In some embodiments, the negative electrode plate can be manufactured in the following manner. The above 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. The negative electrode slurry is applied to the negative electrode current collector, and after processes such as drying and cold pressing, a negative electrode plate is obtained.

[0109] [Electrolyte] The electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate. The present application does not specifically limit the type of the electrolyte, and it can be selected according to requirements. For example, the electrolyte may be selected from at least one of a solid electrolyte and a liquid electrolyte (i.e., an electrolytic solution).

[0110] In some embodiments, the electrolyte employs an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0111] In some embodiments, the electrolyte salt may be selected from one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonylimide) (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0112] In some embodiments, the solvent may be one or more selected from ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfone (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0113] In some embodiments, the electrolyte solution may further optionally contain an additive. For example, the additive may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve any performance of the battery, such as an additive that improves the overcharge performance of the battery, an additive that improves the high-temperature performance of the battery, an additive that improves the low-temperature performance of the battery, and the like.

[0114] [Separator] In some embodiments, the secondary battery further includes a separator. The separator is disposed between the positive electrode plate and the negative electrode plate and serves as an isolation function. In this application, there is no particular limitation on the type of the separator, and any separator having a porous structure with well-known good chemical stability and mechanical stability may be selected.

[0115] In some embodiments, the material of the separator may be selected from at least one of glass fiber, non-woven 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.

[0116] [Outer package] In some embodiments, the secondary battery may include an outer package for packaging the positive electrode plate, the negative electrode plate, and the electrolyte. As an example, the positive electrode plate, the negative electrode plate, and the separator can form a laminated structure battery cell or a wound structure battery cell by lamination or winding. The battery cell is packaged in the outer package, and the electrolyte may employ an electrolytic solution immersed in the battery cell. The number of battery cells in the secondary battery may be one or several, and may be adjusted according to demand.

[0117] In one embodiment, this application provides an electrode assembly. In some embodiments, the positive electrode plate, the negative electrode plate, and the separator may be used to manufacture the electrode assembly by a winding process or a lamination process. This outer package may be used for packaging the above electrode assembly and the electrolyte.

[0118] In some embodiments, the exterior of the secondary battery may be a flexible package, such as a pouch-type flexible package. The material of the flexible package may be plastic, and may include, for example, one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc. In some embodiments, the exterior of the secondary battery may be a rigid shell, such as a rigid plastic shell, an aluminum shell, a steel shell, etc.

[0119] Method for manufacturing a secondary battery In one embodiment, the present application provides a method for manufacturing a secondary battery, where the negative electrode plate described in the present application or a negative electrode plate manufactured based on the method described in the present application is used.

[0120] The manufacturing of the secondary battery may further include the step of assembling the negative electrode plate, positive electrode plate and electrolyte of the present application to form a secondary battery. In some embodiments, the positive electrode plate, separator, and negative electrode plate may be wound or laminated in sequence, with the separator intervening between the positive electrode plate and the negative electrode plate to play a role of isolation, and a battery cell may be obtained. The battery cell is placed in an exterior body, an electrolytic solution is injected and sealed to obtain a secondary battery.

[0121] In some embodiments, the manufacturing of the secondary battery may further include the step of manufacturing a positive electrode plate. As an example, a positive electrode active material, a conductive agent, and an adhesive may be dispersed in a solvent (for example, N-methylpyrrolidone, abbreviated as NMP) to form a uniform positive electrode slurry. The positive electrode slurry is applied to a positive electrode current collector, and after processes such as drying and cold pressing, a positive electrode plate is obtained.

[0122] In some embodiments, the manufacturing of the secondary battery includes the step of manufacturing a negative electrode plate based on the method described in the present application.

[0123] In the present application, there is no particular limitation on the shape of the secondary battery, and it may be cylindrical, square, or any other shape.

[0124] In some embodiments, the present application provides a power consumption device, a battery module, or a battery pack, where the power consumption device, the battery module, or the battery pack includes a secondary battery described in the present application or a secondary battery manufactured based on the method described in the present application.

[0125] In some embodiments, the secondary battery may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more. Those skilled in the art may select a specific number based on the application and capacity of the battery module.

[0126] In some embodiments, the above battery module may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more. Those skilled in the art may select a specific number based on the application and capacity of the battery pack.

[0127] The present application further provides a power consumption device including at least one of the secondary battery, the battery module, or the battery pack according to the present application. The secondary battery, the battery module, or the battery pack may be used as a power source of the power consumption device or as an energy storage unit of the power consumption device. The power consumption device may include, but is not limited to, mobile equipment (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc. Another example of the device may be a mobile phone, a tablet computer, a notebook computer, etc. This device generally requires weight reduction and can adopt a secondary battery as a power source. As the power consumption device, a secondary battery, a battery module, or a battery pack may be selected according to the usage requirements.

[0128] Therefore, the present application provides a battery module including the secondary battery described in the present application.

[0129] In addition, this application further provides a battery pack including the above battery module.

[0130] This application further provides a power consumption device including at least one of the secondary battery, the battery module, or the battery pack described in this application.

[0131] Examples Hereinafter, this application will be described in detail by way of examples, and the description is not restrictive.

[0132] 1. Production of polyether phosphate Step 1: Generate polyether under alkaline conditions with precursor 1, precursor 2, and precursor 3 (see Table 1 for specific types and usage amounts). When the number average molecular weight of the polyether reaches 2w (i.e., 20,000), stop the reaction. Step 2: React the polyether produced in step (1) with a phosphorus agent (phosphorus pentoxide) (see Table 1 for specific usage amount) to generate polyether phosphate. After the reaction is completed, through filtration and dialysis, cut off the polyether phosphate with a number average molecular weight of 2w - 3w (i.e., 20,000 - 30,000).

[0133] 2. Production of positive electrode slurry Mix the positive electrode active material (lithium iron phosphate), conductive agent (conductive carbon black Super P), and adhesive PVDF (see Table 2 for specific usage amounts) for 30 minutes. Then, add the obtained mixture to NMP and stir for 180 minutes to disperse it uniformly. Finally, add the polyether phosphate produced in step 1, and then stir well for 60 minutes to form a uniform positive electrode slurry.

[0134] 3. Production of positive electrode plate The positive electrode slurry is applied to the surface of the positive electrode current collector aluminum foil. After drying and cold pressing the electrode plate, a positive electrode plate is obtained. Through a series of positive electrode plate performance tests (mainly (1) testing whether the electrode plate cracks during coating, (2) testing whether it breaks after cold pressing, and (3) performing the flexibility test method of the positive electrode plate described in this specification, when the flexibility is below grade two, and it does not crack during coating and does not break after cold pressing, the maximum coating weight is the maximum coating weight per unit area), the maximum coating weight per unit area is 41 mg / cm 2 is obtained.

[0135] 4. Manufacturing of the negative electrode plate The negative electrode active material (graphite), conductive agent (Super P), adhesive (SBR), and thickening agent (CMC) are sufficiently stirred and mixed in an appropriate amount of deionized water at a mass ratio of 96.2:0.8:1.8:1.2 to form a uniform negative electrode slurry. This negative electrode slurry is applied to both surfaces of the negative electrode current collector copper foil. After drying and cold pressing, a negative electrode plate is obtained.

[0136] 5. Manufacturing of the electrolyte Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed according to a volume ratio of 1:1:1. Subsequently, LiPF6 is uniformly dissolved in the above solution to obtain an electrolyte, where the concentration of LiPF6 is 1 mol / L.

[0137] 6. Separator A polyethylene (PE) film is adopted.

[0138] 7. Manufacturing of the secondary battery The above positive electrode plate, separator, and negative electrode plate are laminated in sequence. After winding, an electrode assembly is obtained. The electrode assembly is placed in an outer package, the above electrolyte is added, and after processes such as packaging, standing, forming, and aging, the secondary battery of Example 1 is obtained. The outer package selects a hard case with a length × width × height of 148 mm × 28.5 mm × 97.5 mm.

[0139] Examples 2 to 19 and Comparative Example 1 Performed similarly to Example 1, the difference is that raw materials and usage amounts as shown in Tables 1 and 2 are used, and the number average molecular weights of the polyether phosphate esters as shown in Tables 5 to 6 are cut off during production. Here, in Comparative Example 1, no polyether phosphate ester is used.

[0140] Example 21 For the manufacturing processes of Steps 1, 4 to 7, refer to Example 1. The cut-off range of the number average molecular weight of the polyether phosphate ester is as shown in the table 7 as follows, and the manufacturing processes of Steps 2 to 3 are changed as follows.

[0141] Step 2, Manufacture of Positive Electrode Slurry Mix 3124.9 g of positive electrode active material (lithium iron phosphate), 32.5 g of conductive agent (Super P), and 81.25 g of adhesive PVDF for 30 min. Then, add the obtained mixture to 1750 g of NMP solvent and stir for 180 min to disperse it uniformly. Finally, add 11.38 g of the polyether phosphate ester manufactured in Step 1, and then stir well for 60 min to form a uniform positive electrode slurry 1.

[0142] Mix 3134.6 g of positive electrode active material (lithium iron phosphate), 32.5 g of conductive agent (Super P), and 81.25 g of adhesive PVDF for 30 min. Then, add the obtained mixture to 1750 g of NMP solvent and stir for 180 min to disperse it uniformly. Finally, add 1.63 g of the polyether phosphate ester manufactured in Step 1, and then stir well for 60 min to form a uniform positive electrode slurry 2.

[0143] Step 3, Manufacture of Positive Electrode Plate Apply the positive electrode slurry 1 in Step 2 onto the surface of the positive electrode current collector aluminum foil. After drying, apply the positive electrode slurry 2 onto the surface of the dried slurry 1, and maintain the coating thicknesses of the positive electrode slurry 1 and the positive electrode slurry 2 to be the same. Through a series of positive electrode plate performance tests (mainly testing whether the electrode plate cracks during coating and whether it breaks after cold pressing. Refer to the flexibility test method of the positive electrode plate described in this specification. When the flexibility is below grade two, and it does not crack during coating and does not break after cold pressing, the maximum coating weight is the maximum coating weight per unit area), the coating weight per total unit area is 41 mg / cm 2 is achieved.

[0144] Example 20 The difference from Example 21 is that the positive electrode slurry 1 does not contain polyether phosphate ester. Other manufacturing processes are similar to those in Example 21. For specific method parameters, refer to Table 1 and Table 3. The cut-off number average molecular weight range is as shown in Table 7.

[0145] Examples 22 - 26 The manufacturing process is similar to that in Example 21. The difference is that raw materials and their usage amounts as shown in Table 1 and Table 3 are used, and the number average molecular weight is cut off as shown in the table 7 is carried out.

[0146] In this application, for all positive electrode plates in the examples and comparative examples, the positive electrode slurry is applied to both surfaces of the positive electrode current collector, that is, double-sided coating.

[0147]

Table 1

[0148] The precursors 1 - 3 and the phosphorusizing agent used in Examples 13 - 26 are all the same as those in Example 1.

[0149]

Table 2

[0150] In Table 2, in Examples 1 and 13 to 19, 1750 g of the solvent NMP, 32.5 g of the conductive carbon super P, and 81.25 g of the adhesive PVDF were all used. In Examples 2 to 12, the usage amounts of each substance for manufacturing the positive electrode slurry were all the same as those in Example 1.

[0151]

Table 3

[0152] IV. Performance Evaluation of the Positive Electrode Slurry and Positive Electrode Plate of the Present Application Test of slurry parameters, 1. Gelation Factor of Positive Electrode Slurry The gelation of the positive electrode slurry was evaluated by the following method, The gelation factor of the positive electrode slurry is denoted as G, and G = |(m2 - m1) / m1|, where, m1 is the mass of the positive electrode slurry obtained after filtering 2 kg of the initial positive electrode slurry for 10 minutes using a 200-mesh filter screen, m2 is the mass of the positive electrode slurry obtained after filtering 2 kg of the positive electrode slurry placed for 48 hours using a 200-mesh filter screen for 10 minutes. Here, the positive electrode slurry used when measuring m1 and the positive electrode slurry used when measuring m2 are of the same lot of positive electrode slurry.

[0153] If G is within the range of 0 to 0.3, it is determined that gelation does not occur. If G > 0.3, it is determined that it is a gel.

[0154] Test of positive electrode plate parameters 1. Flexibility Test of Positive Electrode Plate The flexibility of the positive electrode plate was evaluated by a winding pin, and the test method is as follows.

[0155] widthManufacture a current collector sample with a size of 50 mm × 100 mm in length, wind it around a specially ordered winding pin, and observe the cracking condition of the current collector by combining visual inspection and microscope.

[0156] Specially ordered winding pin, Cut 60 mm from 304 stainless steel rods with general diameters of 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm, and 7.0 mm respectively, and weld and fix them to a steel plate of 150 mm × 300 mm, as shown in Figure 5.

[0157] Judge the flexibility level based on the following method, The diameter of the winding pin is R, When R ≤ 3.0 mm, no crack occurs in the current collector, and the flexibility is of the first level. When R = 3.0 mm, there is a crack; when R = 4.0 mm, there is no crack, and the flexibility is of the second level. When R = 4.0 mm, there is a crack; when R = 5.0 mm, there is no crack, and the flexibility is of the third level. When R = 5.0 mm, there is no crack; when R = 6.0 mm, there is a crack, and the flexibility is of the fourth level. When R = 6.0 mm, there is no crack; when R = 7.0 mm, there is a crack, and the flexibility is of the fifth level.

[0158] 2. Improvement rate of the infiltration rate of the positive current collector The improvement rate of the infiltration rate of the positive current collector is denoted as I, and I = (I2 - I1) / I1 × 100%, Here, I2 is the infiltration rate of the positive current collector in the electrolyte, I1 is the infiltration rate of the positive current collector without the polyether phosphate ester in the electrolyte, Here, the positive current collector used during the measurement of I1 is the same as the positive current collector used during the measurement of I2. The positive current collector used during the measurement of I1 does not contain the polyether phosphate ester, while the positive current collector used during the measurement of I2 contains the polyether phosphate ester, which is the only difference.

[0159] The measurement processes of I1 and I2 are as follows.

[0160] Test the liquid absorption rate of the electrode plate by the capillary method. Prepare an electrode plate with a size of ≧50mm * 50mm, a smooth surface without wrinkles, no film peeling or powder falling, select a capillary with an inner diameter d = 100um, polish it with sandpaper until the ports are even, suck the electrolyte h = 5mm into the capillary, control the electrolyte height to 5mm, place the capillary on a microscope, contact it with the electrode plate, record the time with a stopwatch as the liquid level in the capillary drops, after the liquid level drop is completed, read the liquid absorption time, record the data t, and the infiltration rate of the electrolyte is

Number

[0161] 3. Measurement of the coating weight per unit area Prepare blank aluminum foil and a positive electrode plate dried during the coating process (both sides of the positive electrode current collector of this positive electrode plate have coatings), trim 15 small circular plates with an area of 1540.25mm 2 each. Subtract the average mass of the empty aluminum foil small circular plates from the average mass of the electrode plate small circular plates and divide by 2 to obtain the coating weight per unit area. The above-mentioned "one side" refers to coating only on one surface of the current collector, which is not the same concept as the number of layers of the "sub-layer" described in this application. The maximum coating weight per unit area in the table refers to the weight of one side.

[0162] The data of the coating weight in the table of the examples of this application all refer to the data of the maximum coating weight per unit area of one side, and both the electrode plate performance and the battery performance are measured by the maximum coating weight.

[0163] The maximum coating weight per unit area refers to the maximum coating weight when (1) testing whether it cracks during the electrode plate coating process, (2) testing whether it breaks during cold pressing, and (3) after performing the positive electrode plate flexibility test described in this application, the flexibility is below the second level, and it does not crack during coating and does not break after cold pressing.

[0164] [Battery-related Performance Tests]

[0165] 1. Measurement of Energy Density The batteries manufactured in the examples and comparative examples were weighed to obtain the mass of the entire battery. After performing capacity formation on the battery, the battery was left standing at 25°C for 10 min and then charged at 0.33C until it reached 100% SOC. After depolarization with a small current, it was left standing for 10 min, and then discharged at 0.33 until it reached 0% SOC. The obtained capacity is the 0.33C capacity of the battery. After the battery was left standing for 30 min, it was charged until it reached 100% SOC, then left standing for 30 min, and then discharged at a constant current of 0.01C for 30 min. The voltage had a stable process, and this stable value was the charge-discharge plateau, that is, the plateau voltage was obtained. Finally, the weight energy density of the battery was calculated, that is, battery mass energy density = battery capacity × discharge plateau voltage / total weight of the battery, and the basic unit is Wh / kg (watt-hour / kilogram).

[0166] 2. Measurement of Direct Current Resistance (abbreviated as DCR) A capacity test was performed on the battery at 25°C, and the capacity test method was as described above. Then, constant voltage charging at 0.05C was performed, and the battery was left standing for 60 min. It was discharged at 0.33C until it reached 50% SOC, left standing for 60 min, discharged at 0.33C until it reached 20% SOC, left standing for 60 min, discharged at 0.33C until it reached 0% SOC, the open-circuit voltage at 0% SOC was tested, and the DCR data for 30 s was sorted out.

[0167] Please refer to Tables 4 to 7 for the measurement results. Here, " / " in the table represents that this item is absent, not added, or not detected.

[0168] In Tables 4 to 7, “(I) / (II) / (III) / (IV)” represents the molar amount of display structure unit (I) / molar amount of structure unit (II) / molar amount of structure unit (3) / molar amount of structure unit (IV). Here, the molar amount of structure unit (I) corresponds to the molar amount of precursor 1 in each example, the molar amount of structure unit (II) corresponds to the molar amount of precursor 2 in each example, the molar amount of structure unit (3) corresponds to the molar amount of precursor 3 in each example, and the molar amount of structure unit (IV) corresponds to the molar amount of phosphate ester group in each example.

[0169]

Table 4

[0170] As can be seen from Table 4, compared with Comparative Example 1, after adding polyether phosphate ester to the positive electrode slurry in the examples, the coating weight per unit area increased by 24%, the energy density increased by 4%, and the battery performance was significantly improved.

[0171]

Table 5

Table 6

[0172] As can be seen from Table 5, the molecular weight of polyether phosphate ester affects the coating weight per unit area and the battery energy density. When the molecular weight is too small, the stability of the positive electrode slurry is low, the physical gelation phenomenon is likely to occur, the flexibility of the positive electrode plate is not significantly improved, and the cracking phenomenon still occurs during coating. When the molecular weight is too large, there are many non-conductive polymers in the slurry, and the polymers are likely to crosslink, leading to gelation of the slurry and affecting the film resistance of the electrode plate.

[0173]

Table 7

[0174] As can be seen from Table 6, the weight ratio of the polyether phosphate ester to the positive electrode active material affects the coating weight per unit area of the electrode plate. When the weight ratio of the polyether phosphate ester to the positive electrode active material is <0.0005 (Example 18), the positive electrode plate cracks at high coating weights, and the energy density of the corresponding battery is low. When the weight ratio of the polyether phosphate ester to the positive electrode active material is >0.03 (Example 19), the film resistance of the electrode plate deteriorates, the battery impedance DCR is high, and it has a great impact on the rate performance of the battery.

[0175]

Table 8

Table 9

[0176] As can be seen from Table 7, in the examples, on the premise that the coating weight per unit area is basically the same, the energy density of the battery corresponding to the positive electrode plate having two sub-layers is high. Furthermore, the ratio of the weight content of the polyether phosphate ester in the sub-layer closest to the positive electrode current collector to the weight content of the polyether phosphate ester in the sub-layer farthest from the positive electrode current collector is within the range of 0 to 60. When the ratio >60 (Example 26), it affects the stability of the slurry and the film resistance of the electrode plate, and the DCR of the battery cell is large.

[0177] It should be noted that this application is not limited to the above embodiments. The above embodiments are merely examples. Any embodiments that have substantially the same configuration in terms of technical idea and exhibit the same functions and effects within the scope of the technical solution of this application are included in the technical scope of this application. In addition, within the scope not departing from the gist of this application, various modifications that can be conceived by those skilled in the art can be implemented on the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of this application.

Claims

1. A positive electrode slurry comprising a positive electrode active material and a polyether phosphate ester, wherein the polyether phosphate ester 【Chemical 1】 contains at least one of the structural units of and 【Chemical Formula 2】 contains the structural unit of and the structural unit (IV) phosphate ester group, wherein A is hydrogen, a halogen or a halogenated alkyl group, the halogen is optionally fluorine, chlorine or bromine, and A is optionally hydrogen or a fluoromethyl group, B is a hydroxyl group, R, OR, or ROR', where R and R' are each independently a linear or branched alkyl group containing 1 to 8 carbons, and optionally B is a methyl group, an ethyl group or an ethoxymethyl group, E is a phenyl group, a phenyl group substituted with an alkyl group, an etherified phenyl group or a halogenated phenyl group, and optionally E is a phenyl group or a fluorophenyl group, The positive electrode slurry, wherein the number average molecular weight range of the polyether phosphate ester is 10,000 to 80,000.

2. The positive electrode slurry according to claim 1, wherein the number average molecular weight range of the polyether phosphate ester is 10,000 to 60,000.

3. The positive electrode slurry according to claim 1 or 2, wherein the number average molecular weight range of the polyether phosphate ester is 30,000 to 50,000.

4. Based on the total molar amount of structural units (I) to (IV), the molar ratio of structural unit (I) is 0 to 75 mol%, the molar ratio of structural unit (II) is 0 to 65 mol%, the molar ratio of structural unit (III) is 5 to 65 mol%, and the molar ratio of structural unit (IV) is 4 to 15 mol%, provided that the molar ratios of structural unit (I) and structural unit (II) are not both zero at the same time. The positive electrode slurry according to claim 1.

5. The positive electrode slurry according to any one of claims 1 to 4, wherein the weight ratio of the polyether phosphate ester to the positive electrode active material is 0.0005 to 0.

030.

6. The positive electrode slurry according to any one of claims 1 to 4, wherein the weight ratio of the polyether phosphate ester to the positive electrode active material is 0.001 to 0.

02.

7. The positive electrode slurry according to any one of claims 1 to 4, wherein the weight ratio of the polyether phosphate ester to the positive electrode active material is 0.001 to 0.

01.

8. The weight ratio of the polyether phosphate ester to the positive electrode active material is 0.001 to 0.

007. The positive electrode slurry according to any one of claims 1 to 4.

9. The positive electrode active material is selected from at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium nickelate, or a mixture thereof. The positive electrode slurry according to any one of claims 1 to 8.

10. The range of the gelation factor G of the positive electrode slurry is 0 to 1. Here, G = (m1 - m2) / m1. When G = 0 to 0.3, it is determined that the slurry does not gel. When G > 0.3, it is determined that it is a gel. m1 is the mass of the positive electrode slurry obtained after filtering 2 kg of the initial positive electrode slurry for 10 minutes using a 100-mesh filter net. m2 is the mass of the positive electrode slurry obtained after filtering 2 kg of the positive electrode slurry left for 48 hours for 10 minutes using a 100-mesh filter net. Here, The positive electrode slurry used when measuring m1 and the positive electrode slurry used when measuring m2 are the same lot of positive electrode slurry. The positive electrode slurry according to any one of claims 1 to 9.

11. The range of the gelation factor G of the positive electrode slurry is 0 to 0.

3. Here, G = (m1 - m2) / m1. When G = 0 to 0.3, it is determined that the slurry does not gel. When G > 0.3, it is determined that it is a gel. m1 is the mass of the positive electrode slurry obtained after filtering 2 kg of the initial positive electrode slurry for 10 minutes using a 100-mesh filter net. m2 is the mass of the positive electrode slurry obtained after filtering 2 kg of the positive electrode slurry left for 48 hours for 10 minutes using a 100-mesh filter net. Here, The positive electrode slurry used when measuring m1 and the positive electrode slurry used when measuring m2 are the same lot of positive electrode slurry. The positive electrode slurry according to any one of claims 1 to 9.

12. A positive electrode plate, A positive electrode current collector, It includes a positive electrode film layer located on at least one surface of the positive electrode current collector, the positive electrode film layer is manufactured with the positive electrode slurry according to any one of claims 1 to 11, and the positive electrode film layer has a mass range per unit area of the electrode plate of 13 to 43 mg / cm ２ wherein the mass is the mass of the positive electrode film layer on one side of the electrode plate, and it is a positive electrode plate.

13. A positive electrode plate, A positive electrode current collector, It includes a positive electrode film layer located on at least one surface of the positive electrode current collector, the positive electrode film layer is manufactured with the positive electrode slurry according to any one of claims 1 to 11, and the mass range of the positive electrode film layer per unit area on the electrode plate is 20 to 43 mg / cm ２ and the mass is the mass of the positive electrode film layer on one side of the electrode plate, a positive electrode plate.

14. A positive electrode plate, A positive electrode current collector, It includes a positive electrode film layer located on at least one surface of the positive electrode current collector, the positive electrode film layer is manufactured with the positive electrode slurry according to any one of claims 1 to 11, and the positive electrode film layer has a mass range per unit area of the electrode plate of 22 to 33 mg / cm ２ wherein the mass is the mass of the positive electrode film layer on one side of the electrode plate, and it is a positive electrode plate.

15. A positive electrode plate, A positive electrode current collector, It includes a positive electrode film layer located on at least one surface of the positive electrode current collector, the positive electrode film layer is manufactured with the positive electrode slurry according to any one of claims 1 to 11, and the range of the mass per unit area of the positive electrode film layer on the electrode plate is 25 to 31 mg / cm ２ and the mass is the mass of the positive electrode film layer on one side of the electrode plate, a positive electrode plate.

16. The positive electrode film layer includes two sub-layers that are parallel to the positive electrode current collector and laminated to each other. Here, the range of the ratio between the weight content of the polyether phosphate ester in the sub-layer closest to the positive electrode current collector and the weight content of the polyether phosphate ester in the sub-layer farthest from the positive electrode current collector is 0 to 60. The positive electrode plate according to any one of claims 12 to 15.

17. The positive electrode film layer includes two sub-layers that are parallel to the positive electrode current collector and laminated to each other. Here, the range of the ratio between the weight content of the polyether phosphate ester in the sub-layer closest to the positive electrode current collector and the weight content of the polyether phosphate ester in the sub-layer farthest from the positive electrode current collector is 0.1 to 30. The positive electrode plate according to any one of claims 12 to 15.

18. When measuring the flexibility of the positive electrode plate with a winding pin, When the diameter R of the winding pin is ≤ 3.0 mm, no cracks occur in the positive electrode plate, or When the diameter R of the winding pin is 3.0 mm, cracks occur in the positive electrode plate, but when the diameter R of the winding pin is 4.0 mm, there are no cracks. The positive electrode plate according to any one of claims 12 to 17.

19. The range of the improvement rate I of the infiltration rate of the positive electrode plate is 2 to 20%, Here, I = (I2 - I1) / I1 × 100%, I2 is the infiltration rate of the positive electrode plate in the electrolyte, I1 is the infiltration rate of the positive electrode plate without the polyether phosphate ester in the electrolyte, Here, the positive electrode plate used when measuring I1 is the same as the positive electrode plate used when measuring I2, and the positive electrode plate used when measuring I1 does not contain the polyether phosphate ester, while the positive electrode plate used when measuring I2 contains the polyether phosphate ester, and they are different only in this point. The positive electrode plate according to any one of claims 12 to 18.

20. The range of the improvement rate I of the infiltration rate of the positive electrode plate is 6 to 15%, Here, I = (I2 - I1) / I1 × 100%, I2 is the infiltration rate of the positive electrode plate in the electrolyte, I1 is the infiltration rate of the positive electrode plate without the polyether phosphate ester in the electrolyte, Here, the positive electrode plate used during the measurement of I1 is the same as the positive electrode plate used during the measurement of I2, and the positive electrode plate used during the measurement of I1 does not contain the polyether phosphate ester, whereas the positive electrode plate used during the measurement of I2 contains the polyether phosphate ester, and they are different only in this respect. The positive electrode plate according to any one of claims 12 to 18.

21. A secondary battery comprising the positive electrode plate according to any one of claims 12 to 20, or a positive electrode plate obtained from the positive electrode slurry according to any one of claims 1 to 11.

Images