Modified cathode material, method for manufacturing the same, cathode sheet, secondary battery, battery module, battery pack, and power consumption device

Abstract

The present application provides a modified positive electrode material, its manufacturing method, a positive electrode sheet, a secondary battery, a battery module, a battery pack and a power consumption device. The modified positive electrode material includes a core and a coating layer, the core being a positive electrode material, and the coating layer including a polymer electrolyte body and a ferroelectric ceramic material dispersed in the polymer electrolyte body. The polymer electrolyte body forms a membrane-like coating layer on the particle outer layer of the positive electrode material, which reduces the side reaction between the surface layer of the positive electrode material and the electrolyte and improves the storage performance. Secondly, the flexible coating layer formed by the polymer electrolyte body can to some extent suppress the contraction and expansion of the positive electrode material during the charging and discharging process, thereby reducing the cracking / pulverization of the positive electrode material. At the same time, the composite coating layer has high ionic conductivity, provides more channels for ion transmission, and improves the rate performance of the synthesized positive electrode material. Therefore, the above modified positive electrode material has good structural stability, and improves the rate performance, material storage and cycle characteristics.

Description

[Technical Field]

[0001] This application relates to the battery technology field, and more particularly to modified cathode materials, methods for manufacturing the same, cathode sheets, secondary batteries, battery modules, battery packs, and power consumption devices. [Background technology]

[0002] Lithium-ion batteries are already the most energy-dense electrochemical energy storage systems in use. With the increasing application of lithium-ion batteries in fields such as powered vehicles and large-scale energy storage, the market is demanding higher energy density and safety performance.

[0003] In lithium-ion batteries, the positive electrode material accounts for a large proportion, approximately 3 to 4 times that of the negative electrode material. As can be seen from this, the performance of the positive electrode material directly affects the performance of the battery, and developing lithium-ion battery positive electrode materials with higher energy density is an unavoidable step in the development of lithium-ion batteries. Since lithium-ion batteries were commercialized in the 1990s, most efforts have been made to improve the energy density of lithium-ion batteries by increasing the content of active material and decreasing the content of inactive material in the paste. However, in recent years, this approach has become a bottleneck, and it has already become difficult to increase the proportion of active material.

[0004] Therefore, the focus is on improving the initial Coulombic efficiency and cycle capacity retention rate of batteries. Initial Coulombic efficiency refers to the formation of a solid electrolyte film on the surface of the electrode material during the initial charge-discharge process. However, a significant portion of lithium ions are lost during the formation of the solid electrolyte film, reducing the capacity of the lithium battery and lowering its energy density. Currently, there are two main methods considered to improve the initial Coulombic efficiency of lithium batteries: replenishing lithium in the negative electrode and pre-coating the electrode material with a solid electrolyte film layer. The lithium replenishment process and operation of the negative electrode are complex, and few methods have been commercialized to date. In contrast, pre-coating with a material is a common material modification method and is easy to implement. By pre-coating the surface of the electrode material with a solid electrolyte film, it is possible not only to prevent the reaction of the electrolyte during the initial charge-discharge process, but also to significantly improve the initial Coulombic efficiency of the battery. Furthermore, the strong controllability of artificial solid electrolyte films can be utilized to achieve optimized structural design. This is a promising method for improving the initial Coulombic efficiency of batteries and represents an important future direction in electrode material modification. The capacity retention rate during the battery cycle is essential for achieving high energy density. During the cycle, materials constantly expand and contract, causing cracks, and the electrolyte permeates through the artificial solid electrolyte membrane and reacts further, affecting the electrical and chemical performance of the battery, such as impedance and capacity retention rate. [Overview of the project]

[0005] This application provides a modified cathode material that improves the structural stability and rate performance of cathode materials, a method for manufacturing the same, a cathode sheet, a secondary battery, a battery module, a battery pack, and a power consumption device.

[0006] A first aspect of the present application provides a modified cathode material comprising a core and a coating layer, wherein the core is a cathode material and the coating layer comprises a polymer electrolyte body and a ferroelectric ceramic material dispersed in the polymer electrolyte body.

[0007] In this modified cathode material, the polymer electrolyte body forms a film-like coating layer on the outer layer of the cathode material particles, reducing side reactions between the surface layer of the cathode material and the electrolyte, inhibiting the dissolution of the cathode material, and improving storage performance. Next, the flexible coating layer formed by the polymer electrolyte body can suppress the contraction and expansion of the cathode material during the charge-discharge process to some extent, thereby reducing cracking / pulverization of the cathode material. At the same time, the composite coating layer containing the polymer electrolyte and ferroelectric ceramic material has high ionic conductivity, providing more channels for ion transmission and improving the rate performance of the synthesized cathode material. As described above, the modified cathode material of this application has good structural stability and improves rate performance, material storage, and cycle characteristics.

[0008] In any embodiment of the first aspect, the mass of the coating layer is 0.5 wt% to 5 wt% of the mass of the modified cathode material, thereby achieving the most complete and comprehensive coating possible on the cathode material. Selectively, the mass content of the ferroelectric ceramic material in the coating layer is 2% to 10%, and more selectively, 2% to 5%, thereby making better use of the ferroelectric ceramic material to improve the ionic conductivity of the polymer electrolyte.

[0009] In any embodiment of the first aspect, the ion diffusion coefficient of the modified cathode material. JPEG0007833029000001.jpg3041 is 10 -11 ~10 -10 S / cm 2and thereby further optimize the rate performance of the modified cathode material. In any embodiment of the first aspect, optionally, the polymer electrolyte body is one or more selected from the group consisting of polyethylene oxide (PEO), polyethylene glycol (PEG), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), vinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE copolymer), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP copolymer), vinylidene fluoride-chlorotrifluoroethylene copolymer (PVDF-CTFE copolymer). Each of the above materials is dried using conventional materials and has a low cost.

[0010] In any embodiment of the first aspect, the weight average molecular weight of the polymer electrolyte body is 1500 to 80000, thereby forming a coating layer with better mechanical properties.

[0011] In any embodiment of the first aspect, the ferroelectric ceramic material has the general formula XYO3, where X is Li + , Na + , K + , Mg 2+ , Ca 2+ , Sr 2+ , Pb 2+ , Ba 2+ and La 2+ and one or more of the group consisting of, Y is Ti 4+ , Zr 4+ , V 5+ , Nb 5+ and Ta 2+ and one or more of the group consisting of, optionally, X is Li + , Sr 2+ , Pb 2+ and Ba 2+ and one or more of the group consisting of, Y is Ti 4+ and / or Nb 5+ is. Each of the ferroelectric ceramic materials is a material known in the art, has good chemical stability, and excellent polarization performance.

[0012] In any embodiment of the first aspect, the ferroelectric ceramic material D V50 The particle size is 5 nm to 100 nm, and selectively, D is a ferroelectric ceramic material. V50 The particle size is 5 nm to 60 nm. By employing nano-order ferroelectric ceramic materials, it is advantageous for the ferroelectric ceramic material to adhere to the surface of the cathode material, and also advantageous for the ferroelectric ceramic material to disperse in the gaps between the segments of the polymer electrolyte. This more effectively reduces the crystallinity of the polymer electrolyte and improves its ionic conductivity.

[0013] In any embodiment of the first aspect, the thickness of the coating layer is 2 nm to 40 nm, and a coating layer within this thickness range can repeatedly provide protection to the positive electrode material, effectively avoid surface side reactions, and avoid an increase in impedance due to the coating layer being too thick.

[0014] In any embodiment of the first aspect, selectively, the modified cathode material D V50 The particle size is 2 μm to 10 μm. This material is advantageous in exhibiting better specific capacity, and the cycle characteristics of batteries using this material are superior.

[0015] In any embodiment of the first aspect, the cathode material is one or more of the group consisting of layered cathode materials, lithium-rich manganese-based cathode materials, spinel-type cathode materials, and conversion-type cathode materials.

[0016] All of the above-mentioned cathode materials are common cathode materials in this field, and after coating them with the above-mentioned coating layer, their storage stability, structural stability, and rate performance can all be improved.

[0017] In any embodiment of the first aspect, the phase state of the cathode material is the O3 phase, and the modified cathode material has a higher capacity.

[0018] A second aspect of the present application provides a method for manufacturing any of the above-mentioned modified cathode materials, the manufacturing method comprising steps S1 to S3, wherein in step S1, a polymer electrolyte solution is prepared; in step S2, a ferroelectric ceramic material and a cathode material are mixed to obtain a cathode material coated with the ferroelectric ceramic material; and in step S3, the polymer electrolyte solution and the cathode material coated with the ferroelectric ceramic material are mixed and dried to obtain a modified cathode material.

[0019] The present invention relates to a manufacturing method in which a ferroelectric ceramic material is first dispersed on the surface of a positive electrode material to form a positive electrode material coated with the ferroelectric ceramic material, then mixed with a liquid polymer electrolyte, dried, and then the polymer electrolyte is bonded to form a film, that is, a coating layer is formed on the positive electrode material. The above manufacturing method is simple and easily adopted and applied industrially.

[0020] In any embodiment of the second aspect, if the total mass of the polymer electrolyte, cathode material and ferroelectric ceramic material is W1, the mass of the polymer electrolyte is W2, and the mass of the ferroelectric ceramic material is W3, then W2 / W1 is between 0.5wt% and 5wt%, thereby achieving the most complete and comprehensive coating possible on the cathode material. Selectively, W3 / (W2+W3) is between 2% and 10%, and selectively between 2% and 5%, further utilizing the ferroelectric ceramic material to improve the ionic conductivity of the polymer electrolyte. Selectively, the polymer electrolyte is one or more selected from the group consisting of polyethylene oxide (PEO), polyethylene glycol (PEG), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), vinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE copolymer), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP copolymer), and vinylidene fluoride-chlorotrifluoroethylene copolymer (PVDF-CTFE copolymer).

[0021] In any embodiment of the second aspect, the mass content of the polymer electrolyte in the polymer electrolyte solution is 0.5% to 10%, which facilitates the dispersion of the positive electrode material coated with a ferroelectric ceramic material, thereby achieving an ideal mixing effect between the two. Selectively, the solvent used in the polymer electrolyte solution is one or more selected from the group consisting of anhydrous ethanol, N-methylpyrrolidone (NMP), and N,N-dimethylformamide (DMF). Each of these solvents has high solubility in the polymer electrolyte and is easily removed during the drying process.

[0022] In any embodiment of the second aspect, the drying in step S3 is spray drying, and selectively, the intake air temperature for spray drying is 130°C to 220°C, and the exhaust air temperature for spray drying is 60°C to 100°C. This results in a modified cathode material with a uniform particle size distribution on the order of micrometers.

[0023] A third aspect of the present application provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer placed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises any one of the above-mentioned modified positive electrode materials. The modified positive electrode material of the present application has good structural stability, thereby improving rate performance, material storage, and cycle characteristics, and the positive electrode sheet having it also has the above advantages.

[0024] In any embodiment of the third aspect, the content of the modified cathode material in the cathode film layer is selectively 90% by weight or more, and selectively 95% to 98% by weight, relative to the total weight of the cathode film layer. This fully demonstrates the advantages of the modified cathode material of the present invention.

[0025] A fourth aspect of the present application provides a secondary battery comprising any one of the modified positive electrode materials of the first aspect or a positive electrode sheet of the third aspect.

[0026] According to the fifth aspect of this application, a battery module including a secondary battery of the fourth aspect is provided.

[0027] According to the sixth aspect of the present application, a battery pack including the battery module of the fifth aspect is provided.

[0028] According to the seventh aspect of this application, a power consumption device is provided that includes a secondary battery selected from the fourth aspect, a battery module of the fifth aspect, or a battery pack of the sixth aspect.

[0029] The features of the modified cathode material of this application are that secondary batteries, battery modules, and battery packs having it have high rate performance and cycle characteristics, and that power consumption devices having the secondary battery, battery module, or battery pack of this application have high power cycle stability. [Brief explanation of the drawing]

[0030] To more clearly explain the technical solutions in the embodiments of this application, the necessary drawings for the embodiments are briefly described below. It should be understood that the drawings shown below represent only a few embodiments of this application, and those skilled in the art can obtain further drawings based on these without requiring any creative effort. Note that the drawings are not necessarily drawn to actual proportions. [Figure 1] This is a scanning electron microscope image of the cathode material of Comparative Example 1. [Figure 2] This is a scanning electron microscope image of the coated cathode material obtained in Comparative Example 3. [Figure 3] This is a scanning electron microscope image of the coated cathode material obtained in Example 9. [Figure 4] This is a scanning electron microscope image of the coated cathode material obtained in Example 1. [Figure 5] This is a scanning electron microscope image of the coated cathode material obtained in Example 4. [Figure 6] This is a schematic diagram of a secondary battery according to one embodiment of the present invention. [Figure 7] Figure 6 is an exploded view of a secondary battery according to one embodiment of the present invention. [Figure 8] This is a schematic diagram of a battery module according to one embodiment of the present invention. [Figure 9] This is a schematic diagram of a battery pack according to one embodiment of the present invention. [Figure 10] Figure 9 is an exploded view of a battery pack according to one embodiment of the present invention. [Figure 11] This is a schematic diagram of a power consumption device that uses a secondary battery as a power source according to one embodiment of the present invention. [Modes for carrying out the invention]

[0031] Embodiments of the present application will be described in more detail below with reference to the drawings and examples. The detailed description of the following embodiments and drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, and the present application is not limited to the embodiments described.

[0032] The following describes in detail embodiments of the modified cathode material and its manufacturing method, cathode sheet, secondary battery, battery module, battery pack, and power consumption device of the present application, with reference to the drawings as appropriate. However, unnecessary details may be omitted. For example, detailed explanations of well-known matters or redundant explanations of substantially identical structures may be omitted. This is to avoid unnecessarily verbose explanations and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following explanation are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0033] The “range” disclosed herein is defined in the form of a lower and upper limit, and a given range is defined by selecting one lower limit and one upper limit, the selected lower and upper limits defining the boundaries of a particular range. Ranges defined in this manner may or may not include the values ​​at both ends and can be combined in any way, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also expected. Similarly, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are listed, the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 are all intended. In this application, unless otherwise specified, the numerical range “a-b” means an abbreviated expression for any combination of real numbers between a and b, where both a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are listed in this specification, and "0 to 5" is merely an abbreviated expression for combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0034] All embodiments and optional embodiments of this application can be combined to form new technical solutions unless otherwise specified.

[0035] All of the technical features and selectable technical features of this application can be combined to form new technical solutions, unless otherwise specified.

[0036] All steps of this application may be performed sequentially or randomly unless otherwise specified, preferably in order. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, if the method may further include step (c), it means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0037] As used herein, “includes” and “inclusive” refer to both open and closed forms unless otherwise specified. For example, “includes” and “inclusive” may include or include other components not listed, or may include or include only the listed components.

[0038] In this application, unless otherwise specified, the term “or” is inclusive. For example, the phrase “A or B” means “A, B, or both A and B.” More specifically, the condition “A or B” is satisfied by either A being true (or existing) and B being false (or not existing), A being false (or not existing) and B being true (or existing), or both A and B being true (or existing).

[0039] [Secondary battery] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be used continuously by reactivating the active material through a charging method after the battery has been discharged.

[0040] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charging and discharging process of the battery, active ions (e.g., lithium ions) reciprocate between the positive and negative electrode sheets, being inserted and removed. The separator is placed between the positive and negative electrode sheets and primarily serves to prevent short circuits between the positive and negative electrodes while also allowing active ions to pass through. The electrolyte primarily serves to conduct active ions between the positive and negative electrode sheets.

[0041] One embodiment of the present application provides a modified cathode material comprising a core and a coating layer, wherein the core is a cathode material and the coating layer comprises a polymer electrolyte body and a ferroelectric ceramic material dispersed in the polymer electrolyte body.

[0042] In the modified cathode material described above, the polymer electrolyte body forms a film-like coating layer on the outer layer of the cathode material particles, reducing side reactions between the surface layer of the cathode material and the electrolyte, inhibiting the dissolution of the cathode material, and improving storage performance. Next, the flexible coating layer formed by the polymer electrolyte body can suppress the contraction and expansion of the cathode material during the charge-discharge process to some extent, thereby reducing cracking / pulverization of the cathode material. At the same time, the ferroelectric ceramic filler has a permanent dipole and therefore has a stronger Lewis acid-base effect with the polymer electrolyte, thereby reducing the crystallinity of the polymer electrolyte, improving ion conductivity, providing more channels for ion transport, and improving the rate performance of the synthesized cathode material. As described above, the modified cathode material of this application has good structural stability and improves rate performance, material storage, and cycle characteristics.

[0043] In some embodiments, the mass of the coating layer is 0.5 wt% to 5 wt% of the mass of the modified cathode material. This not only avoids the coating layer being too high and affecting the performance of the cathode material itself, but also enables the most complete and comprehensive coating possible on the cathode material.

[0044] Ferroelectric ceramic materials can reduce the crystallinity of polymer electrolytes, but if too much ferroelectric ceramic material is used, the mechanical buffering capacity of the coating layer decreases, reducing its ability to reduce cracking / pulverization of the cathode material. If too little ferroelectric ceramic material is used, the effect of improving the ionic conductivity of the electrolyte polymer becomes unclear. In some embodiments, the mass content of ferroelectric ceramic material in the coating layer is 2% to 10%, and more selectively 2% to 7%, thereby further utilizing the ferroelectric ceramic material to improve the ionic conductivity of the polymer electrolyte and providing the coating layer with sufficient mechanical buffering capacity.

[0045] The ionic conductivity of typical polymer electrolytes is 10 -4 Less than or equal to S / cm, for example 10 -4 ~10 -8 The ion conductivity is S / cm, and the coating layer of this invention mainly consists of a polymer electrolyte, but by modifying it with a ferroelectric ceramic material, the ion conductivity of the polymer electrolyte is improved, thereby increasing the ion diffusion coefficient of the modified cathode material. JPEG0007833029000002.jpg3041 is 10 -11 ~10 -10 S / cm 2 This further optimizes the rate performance of the modified cathode material. The ion diffusion coefficient of the above modified cathode material can be measured by the following method.

[0046] The ion diffusion coefficient is detected by the AC impedance method, for example, using a CHI604D impedance analyzer with the amplitude voltage set to 5mV and the frequency range set to 10 -2 ~10 5 Set to Hz, measure the charge transfer impedance after 300 cycles at room temperature, and use the formula JPEG0007833029000003.jpg3041=RT / nFR ct Lithium ion diffusion coefficient The image JPEG0007833029000004.jpg3041 is calculated, where Rct is the charge transfer impedance, F is the Faraday impedance constant, T is the absolute temperature, n is the number of electrons gained or lost, and R is the gas constant.

[0047] The polymer electrolyte used to form the polymer electrolyte body of this application may be a polymer that functions as an electrolyte as conventionally defined in the art, and in some embodiments, the polymer electrolyte body is one or more selected from the group consisting of polyethylene oxide, polyethylene glycol, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, vinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE copolymer), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP copolymer), and vinylidene fluoride-chlorotrifluoroethylene copolymer (PVDF-CTFE copolymer). Each of the above materials is a conventional material, for example, a known modified or unmodified corresponding polymer, and a detailed description of specific substances is omitted in this application.

[0048] In some embodiments, the weight-average molecular weight of the polymer electrolyte body is 1500 to 800000 in order to form a coating layer with better mechanical properties. If the weight-average molecular weight of the polymer electrolyte body is lower than 1500, the formed coating layer has poor coating properties on the cathode material and is prone to leaching during the cycling process. If the weight-average molecular weight of the polymer electrolyte is higher than 800000, the flexibility of the formed coating layer will vary.

[0049] The ferroelectric ceramic material used in this application can be selected from known ferroelectric ceramic materials, and in some embodiments, the ferroelectric ceramic material has the general formula XYO3, where X is Li + na + , K + Mg 2+ Ca 2+ Sr 2+ Pb 2+ Ba 2+ and La2+ It is one or more of the groups consisting of Ti, where Y is Ti 4+ , Zr 4+ , V 5+ Nb 5+ and Ta 2+ It is one or more of the group consisting of, and selectively, X is Li + Sr 2+ Pb 2+ and Ba 2+ It is one or more of the groups consisting of Ti, where Y is Ti 4+ and / or Nb 5+ The above ferroelectric ceramic materials are all known materials in this field, possessing good chemical stability and excellent polarization performance.

[0050] In some embodiments, D of ferroelectric ceramic material V50 The particle size is 5 nm to 100 nm, and selectively, D is a ferroelectric ceramic material. V50 The particle size is 5 nm to 60 nm. By employing nano-order ferroelectric ceramic materials, it is advantageous for the ferroelectric ceramic material to adhere to the surface of the cathode material, and also advantageous for the ferroelectric ceramic material to disperse in the gaps between the segments of the polymer electrolyte, thereby more effectively reducing the crystallinity of the polymer electrolyte and improving its ionic conductivity.

[0051] The coating layer of this application can protect the positive electrode material while simultaneously improving rate performance. In some embodiments, the thickness of the coating layer is 2 nm to 40 nm. A coating layer within this thickness range can repeatedly provide protection to the positive electrode material, effectively avoid surface side reactions, and prevent an increase in impedance due to an excessively thick coating layer.

[0052] In some embodiments, the modified cathode material D V50 The particle size is 1 μm to 10 μm. This material is advantageous in exhibiting better specific capacity, and the cycle characteristics of batteries using this material are superior.

[0053] In any embodiment of the first aspect, the positive electrode material is any one or more of the group consisting of a layered positive electrode material, a lithium-excess manganese-based positive electrode material, a spinel-type positive electrode material, and a conversion-type positive electrode material. Each of the above various positive electrode materials is a common positive electrode material in this field, and after being coated with the above coating layer, the storage stability, structural stability, and rate performance can all be improved. The above layered positive electrode material may be lithium cobaltate, a nickel cobalt manganese ternary material, etc., for example, NCM111, NCM523, NCM622, NCM715, NCM811, NCM9655, NCM9631, NCA, and materials after corresponding doping modification and coating modification. For high-nickel ternary materials, the coating layer further plays a role in reducing the lithium impurity content on the surface. The above lithium-excess manganese-based positive electrode material may be lithium-excess lithium manganate Li2MnO3, Li[Li 1 / 3 Mn 2 / 3 O2 or xLiMO 2· (1-x) Li[Li 1 / 3 Mn 2 / 3 O2 (0 < x < 1), etc., and any one of the corresponding doping modifications and materials after coating modification. The spinel-type positive electrode material may be lithium manganate LiMn2O4 with a spinel structure, doped lithium manganate LiMn 2-x M x O4 (0 < x < 2, M is Ni, V, Cr, Cu, Co, or Fe, etc.). The conversion-type positive electrode material is selected from MX m , where M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, etc., X = F, Cl, O, S, N, P, etc., and m makes the valence of MX m zero. Each of the above positive electrode materials may be single crystal or polycrystalline, but preferably polycrystalline.

[0054] In some embodiments, the phase state of the above positive electrode material is the O3 phase, and the modified positive electrode material has a higher capacity.

[0055] Another embodiment of the present application provides a method for producing any of the above-described modified cathode materials, the method comprising steps S1 to S3. In step S1, a polymer electrolyte solution is produced. In step S2, a ferroelectric ceramic material and a cathode material are mixed to obtain a cathode material coated with the ferroelectric ceramic material. In step S3, the polymer electrolyte solution and the cathode material coated with the ferroelectric ceramic material are mixed and dried to obtain a modified cathode material.

[0056] The present invention relates to a manufacturing method in which a ferroelectric ceramic material is first dispersed on the surface of a positive electrode material to form a positive electrode material coated with the ferroelectric ceramic material, then mixed with a liquid polymer electrolyte, dried, and then the polymer electrolyte is bonded to form a film, that is, a coating layer is formed on the positive electrode material. The above manufacturing method is simple and easily adopted and applied industrially.

[0057] In the manufacturing process, without considering losses, in some embodiments, if the total mass of the polymer electrolyte, cathode material, and ferroelectric ceramic material is W1, the mass of the polymer electrolyte is W2, and the mass of the ferroelectric ceramic material is W3, then (W2+W3) / W1 is between 0.5wt% and 5wt%, achieving the most complete and comprehensive coating possible on the cathode material. Selectively, W3 / (W2+W3) is between 2% and 10%, and selectively between 2% and 7%, further utilizing the ferroelectric ceramic material to improve the ionic conductivity of the polymer electrolyte.

[0058] The polymer electrolyte described above may be a polymer that functions as an electrolyte as conventionally defined in this art. In some embodiments, the polymer electrolyte body is one or more selected from the group consisting of polyethylene oxide, polyethylene glycol, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, vinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE copolymer), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP copolymer), and vinylidene fluoride-chlorotrifluoroethylene copolymer (PVDF-CTFE copolymer). Each of the above materials is a conventional material, for example, a known modified or unmodified corresponding polymer, and a detailed description of specific substances is omitted in this application.

[0059] This invention aims to thoroughly and uniformly mix a polymer electrolyte, a cathode material, and a ferroelectric ceramic material, and to dissolve the polymer electrolyte in a solvent to form a solution. In some embodiments, the mass content of the polymer electrolyte in the solution is 0.5% to 10%, facilitating the dispersion of the cathode material coated with the ferroelectric ceramic material, thereby achieving an ideal mixing effect between the two. To minimize the amount of solvent used to dissolve the polymer electrolyte and to facilitate the removal of the solvent, in some embodiments, the solvent used in the polymer electrolyte solution is one or more selected from the group consisting of anhydrous ethanol, N-methylpyrrolidone (NMP), and N,N-dimethylformamide (DMF). Each of these solvents has high solubility in the polymer electrolyte and is easily removed during the drying process.

[0060] The drying in step S3 above may be vacuum drying, hot air drying, or spray drying. If vacuum drying or hot air drying is selected, the particle size is further pulverized after drying to control the particle size. In some embodiments, the drying in step S3 is spray drying. To improve the efficiency of spray drying and to control the particle size of the modified cathode material obtained by spray drying, in some embodiments, the intake air temperature for spray drying is controlled to 130°C to 220°C, and the exhaust air temperature for spray drying is controlled to 60°C to 100°C. This ensures a uniform particle size distribution and D V50 Modified cathode materials with particle sizes on the micrometer order, ranging from 1 μm to 10 μm, can be obtained.

[0061] [Positive electrode sheet] A positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer placed on at least one surface of the positive electrode current collector, the positive electrode film layer containing a positive electrode active material, and the positive electrode active material containing any of the above-mentioned modified positive electrode materials. The modified positive electrode material of the present invention has good structural stability, so rate performance, material storage and cycle characteristics are all improved, and a positive electrode sheet having it also has the above advantages.

[0062] For example, 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.

[0063] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. As the metal foil, for example, aluminum foil can be used. The composite current collector may include a polymer substrate layer and a metal layer formed on at least one surface of the polymer substrate layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0064] In some embodiments, the cathode active material may further use a known cathode active material for batteries. As an example, the cathode active material may include at least one of lithium-containing phosphates having an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as the cathode active material of the battery may also be used. These cathode active materials may be used alone or in combination of two or more. 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 (abbreviation NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviation NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviation NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (abbreviation NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (abbreviation NCM 811 ))、lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05The olivine structure lithium-containing phosphate may include, but is not limited to, at least one of O2 and its modified compounds. For example, the olivine structure lithium-containing phosphate may include, but is not limited to, at least one of lithium ferric phosphate (e.g., LiFePO4 (abbreviated as LFP)), a composite material of lithium ferric phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0065] In some embodiments, the positive electrode film layer may selectively further contain a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resins.

[0066] In some embodiments, the positive electrode film layer may further selectively contain 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.

[0067] In some embodiments, a positive electrode sheet can be manufactured by the following method. Components for manufacturing the positive electrode sheet, such as a positive electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode paste. The positive electrode paste is then applied to a positive electrode current collector, and the positive electrode sheet can be obtained through processes such as drying and cold pressing.

[0068] [Negative electrode sheet] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer placed on at least one surface of the negative electrode current collector and containing a negative electrode active material.

[0069] For example, the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0070] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector may include a polymer substrate layer and a metal layer formed on at least one surface of the polymer substrate. The composite current collector can be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0071] In some embodiments, the negative electrode active material can be any known negative electrode active material for batteries. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. Silicon-based materials can be selected from at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials can be selected from at least one of elemental tin, tin oxide, and tin alloys. However, this application is not limited to these materials, and other conventional materials usable as negative electrode active materials for batteries may be used. These negative electrode active materials may be used individually or in combination of two or more types.

[0072] In some embodiments, the negative electrode film layer may selectively further contain a binder. As an example, the binder can be selected from at least one of polyvinylidene fluoride (PVDF), 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).

[0073] In some embodiments, the negative electrode film layer may further selectively contain a conductive agent. As an example, the conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0074] In some embodiments, the negative electrode film layer further comprises other additives, such as a selective thickener (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0075] In some embodiments, a negative electrode sheet can be manufactured by the following method. Components for manufacturing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode paste. The negative electrode paste is then applied to a negative electrode current collector, and the negative electrode sheet can be obtained through processes such as drying and cold pressing.

[0076] [Electrolytes] The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. This application does not particularly limit the type of electrolyte, and it can be selected as needed. For example, the electrolyte may be a liquid, a gel, or a solid.

[0077] In some embodiments, the electrolyte is a liquid and comprises an electrolyte salt and a solvent.

[0078] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluoride phosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoride arsenate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bisoxalate borate, lithium difluorooxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0079] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0080] In some embodiments, the electrolyte selectively further comprises additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and further additives that can improve specific characteristics of the battery, such as additives that improve the overcharge characteristics of the battery, or additives that improve the high-temperature or low-temperature characteristics of the battery.

[0081] [Separator] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous structure separator having good chemical and mechanical stability can be selected.

[0082] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. If the separator is a multilayer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0083] In some embodiments, the positive electrode sheet, negative electrode sheet, and separator can be manufactured into an electrode assembly via a winding process or a lamination process.

[0084] In some embodiments, the secondary battery may include an outer casing. This casing is used to enclose the electrode assembly and electrolyte.

[0085] In some embodiments, the casing material of the secondary battery may be a hard case such as a rigid plastic case, an aluminum case, or a steel case. The casing material of the secondary battery may also be a soft pack such as a pouch-type soft pack. The material of the soft pack may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0086] This invention does not particularly limit the shape of the secondary battery, and it may be cylindrical, prismatic, or any other shape. For example, Figure 6 shows a prismatic secondary battery 5 as an example.

[0087] In some embodiments, referring to Figure 7, the exterior material may include a housing 51 and a cap assembly 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates surround and form a housing cavity. The housing 51 has an opening that communicates with the housing cavity, and the cap assembly 53 can cover the opening to seal the housing cavity. An electrode assembly 52 can be formed from a positive electrode sheet, a negative electrode sheet, and a separator via a winding or lamination process. The electrode assembly 52 is sealed within the housing cavity. The electrode assembly 52 is impregnated in an electrolyte. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art can select according to specific practical requirements.

[0088] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, the specific number of which can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0089] Figure 8 shows an example of a battery module 4. Referring to Figure 8, in the battery module 4, multiple secondary batteries 5 can be installed in sequence along the length of the battery module 4. Of course, they can be arranged in any other way. Furthermore, these multiple secondary batteries 5 can be fixed in place with fasteners.

[0090] Selectively, the battery module 4 may further comprise an outer case having a housing space for accommodating multiple secondary batteries 5.

[0091] In some embodiments, the battery modules can be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, the specific number of which can be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0092] Figures 9 and 10 show an example of a battery pack 1. Referring to Figures 9 and 10, the battery pack 1 may include a battery case and a plurality of battery modules 4 installed inside the battery case. The battery case includes an upper housing 2 and a lower housing 3, the upper housing 2 can be placed over the lower housing 3 and form a sealed space for housing the battery modules 4. The plurality of battery modules 4 can be arranged inside the battery case in any way.

[0093] Furthermore, the present application provides a power consumption device comprising at least one of a secondary battery, a battery module, or a battery pack relating to the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device, or as an energy storage element for the power consumption device. The power consumption device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships and satellites, energy storage systems, etc.

[0094] As the power consumption device, a secondary battery, battery module, or battery pack can be selected according to the usage requirements.

[0095] Figure 11 shows an example of a power consumption device. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power output and high energy density requirements for the secondary battery of this power consumption device, a battery pack or battery module can be used.

[0096] [Examples] The following describes examples of the present application. The examples described below are illustrative and are for illustrative purposes only, and should not be understood as limiting the present application. If specific techniques or conditions are not shown in the examples, they should be carried out in accordance with the techniques or conditions described in the literature in the art, or in accordance with the product instructions. If the manufacturer of the reagents or equipment used is not specified, they are all commercially available common products.

[0097] The source and main characteristics of the polymer electrolyte used in the examples are shown in the table below. JPEG0007833029000005.jpg114170

[0098] Comparative Example 1 NCM811 is a cathode material raw material, D V50 It is approximately 9 μm in size.

[0099] Comparative Example 2 A PVDF-HFP / NMP solution was prepared at a concentration of 2 w / v%, and the NCM811 cathode material raw material was added to the PVDF-HFP / NMP solution with a solid-liquid mass-to-volume ratio of 1:1. After uniform stirring, a cathode material coated with PVDF-HFP was obtained by spray drying (intake temperature 180°C, exhaust temperature 80°C), with a coating layer ratio of 2 wt%.

[0100] Comparative Example 3 BaTiO3 was dry-mixed with NCM811 cathode material raw materials at a concentration of 5000 ppm to obtain an NCM811 cathode material coated with BaTiO3, and the mass ratio of the coating layer to the total material was 0.5 wt%.

[0101] Comparative Example 4 A PVDF-HFP / NMP solution was prepared at a concentration of 1 w / v%, and Al2O3 was mixed with the NCM811 cathode material raw material at a concentration of 700 ppm to form an NCM811 material coated with Al2O3. The Al2O3-coated NCM811 material was added to the PVDF-HFP / NMP solution, with a solid-liquid ratio of 1:1. After uniform stirring, it was spray-dried (intake temperature 180°C, exhaust temperature 80°C) to obtain an NCM811 cathode material coated with Al2O3 / PVDF-HFP. The mass ratio of the coating layer to the total material was 1 wt%, and the mass ratio of the filler to the total coating layer was 7 wt%.

[0102] Example 1 A PVDF-HFP / NMP solution was prepared at a concentration of 1 w / v%, and BaTiO3 was mixed with the NCM811 cathode material raw material at a concentration of 700 ppm to form an NCM811 material coated with BaTiO3. The BaTiO3-coated NCM811 material was added to the PVDF-HFP solution, with a solid-liquid mass-to-volume ratio of 1:1. After uniform stirring, the mixture was spray-dried (intake temperature 180°C, exhaust temperature 80°C) to obtain an NCM811 cathode material coated with BaTiO3 / PVDF-HFP. The mass ratio of the coating layer to the total material was 1 wt%, and the mass ratio of the filler to the total coating layer was 7 wt%.

[0103] Example 2 A PEG / anhydrous ethanol solution was prepared at a concentration of 2 w / v%, and LiNbO3 was mixed with the NCM9255 cathode material raw material at a concentration of 500 ppm to form an NCM9255 cathode material coated with LiNbO3. The LiNbO3-coated NCM9255 cathode material was added to the PEG / anhydrous ethanol solution, with a solid-liquid mass-to-volume ratio of 1:1. After uniform stirring, it was spray-dried (intake temperature 180°C, exhaust temperature 80°C) to obtain an NCM9255 cathode material coated with LiNbO3 / PEG. The mass ratio of the coating layer to the total material was 2 wt%, and the mass ratio of the filler to the total coating layer was 2.5 wt%.

[0104] Example 3 A PAN / DMF solution was prepared at a concentration of 5 w / v%, and SrTiO3 was mixed with the NCM9255 cathode material raw material at a concentration of 5000 ppm to form an NCM9255 cathode material coated with SrTiO3. The SrTiO3-coated high-nickel NCM cathode material was added to the PAN / DMF solution, with a solid-liquid mass-to-volume ratio of 1:1. After uniform stirring, it was spray-dried (intake temperature 180°C, exhaust temperature 80°C) to obtain a high-nickel NCM cathode material coated with SrTiO3 / PAN. The mass ratio of the coating layer to the total material was 5 wt%, and the mass ratio of the filler to the total coating layer was 10 wt%.

[0105] Example 4 The difference from Example 1 is that the concentration of PVDF-HFP was adjusted to 0.5 w / v%, BaTiO3 was mixed with the NCM811 cathode material raw material at a concentration of 350 ppm to form an NCM811 material coated with BaTiO3, and the mass ratio of the coating layer to the total material was reduced to 0.5 wt%, with no other changes.

[0106] Example 5 The only difference from Example 1 is that the amount of BaTiO3 used was adjusted to 500 ppm, and the mass content of BaTiO3 in the coating layer was set to 5%; everything else remained unchanged.

[0107] Example 6 The only difference from Example 1 is that the amount of BaTiO3 used was adjusted to 200 ppm, and the mass content of BaTiO3 in the coating layer was set to 2%; everything else remained unchanged.

[0108] Example 7 The only difference from Example 1 is that the amount of BaTiO3 used was adjusted to 100 ppm, and the mass content of BaTiO3 in the coating layer was set to 1%; everything else remained unchanged.

[0109] Example 8 The only difference from Example 1 is that the amount of BaTiO3 used was adjusted to 1500 ppm, and the mass content of BaTiO3 in the coating layer was set to 15%; everything else remained unchanged.

[0110] Example 9 A PVDF-HFP / NMP solution is prepared at a concentration of 1 w / v%, and BaTiO3 is mixed with the NCM811 cathode material raw material at a concentration of 700 ppm to form an NCM811 material coated with BaTiO3. The BaTiO3-coated NCM811 material is added to the PVDF-HFP / NMP solution, with a solid-liquid mass-to-volume ratio of 1:1. After uniform stirring, it is dried at 80°C for 24 hours, and then the dried raw material is pulverized to obtain a high-nickel NCM cathode material coated with BaTiO3 / PVDF-HFP. The mass ratio of the coating layer to the total high-nickel NCM cathode material coated with BaTiO3 / PVDF-HFP is 1 wt%, and the mass ratio of BaTiO3 to the coating layer is 7 wt%.

[0111] Example 10 The only difference from Example 1 is that PVDF-HFP was replaced with PEO; everything else remains unchanged.

[0112] Example 11 The only difference from Example 1 is that PMMA was used to replace PVDF-HFP; everything else remains unchanged.

[0113] Example 12 The only difference from Example 1 is that PVDF-TrFE was used to replace PVDF-HFP; everything else remains unchanged.

[0114] Example 13 The only difference from Example 1 is that PVDF-CTFE was used to replace PVDF-HFP; everything else remains unchanged.

[0115] Example 14 The only difference from Example 1 is that BaTiO3 was replaced with SrTiO3; everything else remains unchanged.

[0116] Example 15 The difference from Example 1 is that the amount of PVDF-HFP used was adjusted to 5 wt%, the amount of BaTiO3 used was set to 3500 ppm, and the content of the coating layer was set to 5%; everything else remains unchanged.

[0117] Example 16 The difference from Example 1 is that the amount of PVDF-HFP used was adjusted to 7 wt%, the amount of BaTiO3 used was set to 4900 ppm, and the content of the coating layer was set to 7%; everything else remains unchanged.

[0118] Example 17 The only difference from Example 1 is that the intake air temperature for spray drying was changed to 130°C and the exhaust air temperature was changed to 60°C; everything else remains unchanged.

[0119] Example 18 The only difference from Example 1 is that the intake air temperature for spray drying was changed to 220°C and the exhaust air temperature was changed to 110°C; everything else remains unchanged.

[0120] Example 19 The only difference from Example 1 is that the intake air temperature for spray drying was changed to 80°C and the exhaust air temperature to 30°C; everything else remained unchanged. Due to the lower spray drying temperature, the resulting modified cathode material slightly aggregated.

[0121] Example 20 The only difference from Example 1 is that the intake air temperature for spray drying was changed to 260°C and the exhaust air temperature was changed to 160°C; everything else remains unchanged.

[0122] Example 21 The difference from Example 1 is the D of the NCM811 cathode material raw material used. V50 The particle size is approximately 2 μm.

[0123] Example 22 The difference from Example 1 is the D of the BaTiO3 used. V50 The size is approximately 5 nm.

[0124] Example 23 The difference from Example 1 is the D of the BaTiO3 used. V50 The wavelength is approximately 60 nm.

[0125] Example 24 The difference from Example 1 is that the D of the used BaTiO3 V50 is about 100 nm.

[0126] Example 25 The difference from Example 1 is that the D of the used BaTiO3 V50 is about 150 nm.

[0127] Measurement 1) Lithium impurity content Using the automatic potentiometric titrator - 905 from Metrohm AG, Switzerland, in accordance with GB / T 9736 - 2008, measure the lithium impurity content of the cathode materials or modified cathode materials obtained in each example and comparative example, and record the results in Table 1.

[0128] 2) Morphology, thickness of the coating layer, particle size of the cathode material after coating Using the field emission scanning electron microscope (Sigma300), transmission electron microscope (TECNAI G2 F20 STWIN) from Carl Zeiss AG, Germany, and laser particle size analyzer (GB / T 19077.1 - 2016 / ISO 13320:2009 (laser analysis method for particle size distribution)), measure the materials obtained in the examples, and record the morphology, thickness of the coating layer, D of the ferroelectric ceramic material V50 particle size, D of the obtained cathode material V50 particle size test results in Table 1. The SEM images obtained in Comparative Example 1, Comparative Example 3, Example 9, Example 1, and Example 4 are Figures 1 to 5 in sequence. [[ID=3​​​​​​​​​[Positive Electrode Sheet] The positive electrode active material obtained above, polyvinylidene fluoride (PVDF), and acetylene black are added to NMP in a weight ratio of 90:5:5 and stirred in a drying chamber to create a paste. The paste is applied to aluminum foil, dried, and cold-pressed to produce a positive electrode sheet. The application amount is 0.01 g / cm². 2 The compacted flour density is 3.5 g / cm³. 3 That is the case.

[0131] [Negative electrode sheet] A 0.5 mm thick lithium metal sheet is used as the negative electrode sheet.

[0132] [Electrolyte] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1, and then LiPF6 is uniformly dissolved in the above solution to obtain the electrolyte, with a LiPF6 concentration of 1 mol / L.

[0133] [Separator] I will purchase the separator from Cellgard, model number Cellgard 2400.

[0134] The manufactured positive electrode sheet, negative electrode sheet, separator, and electrolyte are assembled into a CR2032 type button battery (hereinafter also referred to as "button battery") in a button battery box.

[0135] Testing of initial specific capacity and initial Coulomb efficiency of button batteries

[0136] The button battery is charged at 0.1C to 4.3V from 2.8 to 4.3V, then charged at a constant voltage of 4.3V until the current is ≤0.05mA, and left to stand for 2 minutes. The charged capacity at this time is denoted as C0. Then, it is discharged at 0.1C to 2.8V. The discharged capacity at this time is the initial relative capacity and is denoted as D0. The initial Coulomb efficiency is calculated as D0 / C0 * 100%.

[0137] The results are shown in Table 2.

[0138] 5) Production of all batteries [Positive Electrode Sheet] The positive electrode active material obtained above, acetylene black, and polyvinylidene fluoride (PVDF) are uniformly mixed in an N-methylpyrrolidone solvent system in a weight ratio of 94:3:3. This mixture is then applied to aluminum foil, dried, and cold-pressed to obtain a positive electrode sheet. The application amount is 0.02 g / cm². 2 The compacted flour density is 3.5 g / cm³. 3 That is the case.

[0139] [Negative Electrode Sheet] Artificial graphite (anode active material), hard carbon, acetylene black (conductive agent), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethylcellulose (CMC-Na) (thickener) are uniformly mixed in deionized water in a weight ratio of 90:5:2:2:1. This mixture is then applied to copper foil, dried, and cold-pressed to obtain a negative electrode sheet. The application amount is 0.015 g / cm². 2 The compacted flour density is 1.6 g / cm³. 3 That is the case.

[0140] [Electrolyte] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1, and then LiPF6 is uniformly dissolved in the above solution to obtain the electrolyte, with a LiPF6 concentration of 1 mol / L.

[0141] [Separator] A porous polymerized PE film is used as the separator.

[0142] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator positioned between the positive and negative electrodes to act as an separator, and then wound up to obtain a bare cell. The bare cell is placed in an outer casing, and the electrolyte is injected and sealed to obtain a complete battery (hereinafter also referred to as a "full cell"). The dimensions of the complete battery are length × width × height = 90 mm × 30 mm × 60 mm, and the battery margin is 91.0%.

[0143] The full cell capacity is measured at 1 / 3C, the 25°C / 45°C cycle is measured at 1C / 1C, and the gas generation trend is measured at 70°C.

[0144] Measurement of the initial specific volume of a full cell Under a constant temperature environment of 25°C, the battery was left standing for 5 minutes, discharged to 2.8V at 1 / 3C, left standing for 5 minutes, discharged to 4.25V at 1 / 3C, then charged at a constant voltage of 4.25V with a current of ≤0.05C, left standing for 5 minutes, and then discharged to 2.8V at 1 / 3C. The discharge capacity at this time is the initial relative capacity and is denoted as D0. The results are shown in Table 2.

[0145] Total battery capacity retention rate at 25℃ At 25°C, the battery is charged to 4.25V with a constant current of 1C, then charged again with a constant voltage of 4.25V until the current drops to 0.05C, and finally discharged to 2.8V with a constant current of 1C to obtain the discharge ratio capacity (Cd1) for the first cycle. This charging and discharging process is repeated up to 300 cycles to obtain the discharge ratio capacity of the lithium-ion battery after n cycles, which is denoted as Cdn. Capacity retention rate = Discharge ratio capacity after n cycles (Cdn) / Discharge ratio capacity for the first cycle (Cd1). The results are shown in Table 2.

[0146] Total battery capacity retention rate at 45℃ At 45°C, the battery is charged to 4.25V with a constant current of 1C, then charged again with a constant voltage of 4.25V until the current drops to 0.05C, and finally discharged to 2.8V with a constant current of 1C to obtain the discharge ratio capacity (Cd1) for the first cycle. This charging and discharging process is repeated up to 300 cycles to obtain the discharge ratio capacity of the lithium-ion battery after n cycles, which is denoted as Cdn. Capacity retention rate = Discharge ratio capacity after n cycles (Cdn) / Discharge ratio capacity for the first cycle (Cd1). The results are shown in Table 2.

[0147] Gas expansion test of all batteries at 70°C All batteries in a 100% charged state (SOC) are stored at 70°C. The SOC is monitored by measuring the open-circuit voltage (OCV) and AC internal resistance (IMP) of the cells before, during, and after storage, and the cell volume is also measured. Every 48 hours of storage, all batteries are removed, left to stand for 1 hour, then the OCV and IMP are tested, and after cooling to room temperature, the cell volume is measured by the drainage method. The drainage method involves first measuring the gravitational force F1 of the cell alone using a balance that automatically converts units using dial data, and then immersing the cell in deionized water (density 1 g / cm³).3 The cell is completely placed in the furnace (which is known to be the case), and the gravitational force F2 of the cell at this time is measured. The buoyancy F acting on the cell is equal to F1-F2, and then the volume of the cell V=(F1-F2) / ρg is calculated based on Archimedes' principle F=ρgV. After measuring the volume each time, the cell is charged with a constant current of 1C up to 4.25V, and then charged with a constant voltage of 4.25V until the current drops to 0.05C. After charging is complete, the cell is placed in the furnace and the test is continued. After storage for 30 days, the volume of the cell is measured, and the corresponding volume of the cell before storage and the increase in volume of the cell after storage, i.e., the amount of gas generated, are calculated. The test results are recorded in Table 2.

[0148] 6) Ion diffusion coefficient AC impedance method (CHI604D impedance analyzer, amplitude voltage is 5mV, frequency range is 10 -2 ~10 5 The charge transfer impedance after 300 cycles at room temperature was tested using (Hz), and the lithium ion diffusion coefficient was calculated using the following formula ( Calculate (JPEG0007833029000006.jpg3041) and record the test results in Table 2.

[0149] JPEG0007833029000007.jpg3041=RT / nFR ct Here, Rct is the charge transfer impedance, F is the Faraday impedance constant, T is the absolute temperature, n is the number of electrons gained or lost, and R is the gas constant.

[0150] Table 1 JPEG0007833029000008.jpg250129

[0151] Table 2 JPEG0007833029000009.jpg231170

[0152] As can be seen from the comparative analysis by electron microscope scanning of the samples produced in Comparative Examples 1 and 3 and Examples 1, 4, and 9, a single ferroelectric ceramic coating can form island-like coatings on the surface of the cathode material, while a composite polymer electrolyte coating can form a uniform film-like coating layer on the surface of the cathode material, and the continuity of the film improves with increasing polymer coating amount.

[0153] As can be seen from the comparative analysis of lithium impurity data of the samples produced in Comparative Examples 1-3 and the Examples, the presence of a film-like coating layer segregates H2O and CO2 to some extent, thereby reducing NCM lithium impurities. Furthermore, the better the continuity of the film, the less lithium impurities there are, improving capacity, enhancing cycle characteristics, and reducing gas generation.

[0154] Comparing the cycling effects of the samples produced in Comparative Example 4 and Examples 1-4, the interaction between Al2O3 and the polymer electrolyte is weak, limiting the improvement in the ion transport function of the coating layer. Furthermore, Al2O3 is an inert substance and an insulator of electrons and ions, causing a decrease in capacity.

[0155] As can be seen from the comparative analysis of the performance data of the samples produced in Examples 1, 4, and 15-16, a continuous composite polymer electrolyte coating layer of appropriate thickness is advantageous for increasing cycles and suppressing gas generation. If the coating layer is not continuous, the cathode material remains exposed to the electrolyte, and if the coating layer is too thick, electron transmission is suppressed. With a reasonable coating amount, the produced cathode material exhibits high capacity, good cycle characteristics, low gas generation, and high structural stability.

[0156] As can be seen by comparing the performance data of the samples in Example 1 and Examples 22-25, the particle size of BaTiO3 affects both the capacity and cycle characteristics. In Example 25, when the particle size is too large, the improvement effect on the crystallinity of the polymer electrolyte is not clear, and the improvement in the rate performance of the cathode material is insufficient.

[0157] While the present application has been described with reference to preferred embodiments, various improvements and substitutions of components with equivalents can be made without departing from the scope of the application. In particular, each technical feature mentioned in each embodiment can be combined in any way, provided that there is no structural inconsistency. The present application is not limited to the specific embodiments disclosed herein and includes all technical solutions included in the claims. [Explanation of symbols]

[0158] 1 Battery pack 2 Upper cabinet 3 Lower cabinet 4 Battery Modules 5 Secondary battery 51 Housing 52 Electrode Assembly 53 Cap Assembly

Claims

1. Including a core and a coating layer, The aforementioned core is a positive electrode material, The coating layer comprises a polymer electrolyte body and a ferroelectric ceramic material dispersed in the polymer electrolyte body. The polymer electrolyte body is one or more selected from the group consisting of polyethylene oxide, polyethylene glycol, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, and vinylidene fluoride-chlorotrifluoroethylene copolymer. The aforementioned ferroelectric ceramic material is given by the general formula XYO ３ X has Li ＋ , Sr ２＋ Pb ２＋ and Ba ２＋ It is one or more of the groups consisting of Ti ４＋ and / or Nb ５＋ The ferroelectric ceramic material is SrTiO ３ does not include Modified cathode material.

2. The modified cathode material according to claim 1, wherein the mass of the coating layer is 0.5 wt% to 5 wt% of the mass of the modified cathode material, and selectively, the mass content of the ferroelectric ceramic material in the coating layer is 2% to 10%, and more selectively, 2% to 7%.

3. The ion diffusion coefficient of the modified positive electrode material is 10 －１１ to 10 －１０ S / cm ２ The modified positive electrode material according to claim 1 or 2, wherein the ion diffusion coefficient is as above.

4. The modified cathode material according to claim 1 or 2, wherein the weight-average molecular weight of the polymer electrolyte body is 1,500 to 800,000.

5. The ferroelectric ceramic material D Ｖ５０ The particle size is 5 nm to 100 nm, and selectively the D of the ferroelectric ceramic material. Ｖ５０ The modified cathode material according to claim 1 or 2, wherein the particle size is 5 nm to 60 nm.

6. The thickness of the coating layer is 2 nm to 40 nm, and selectively, the modified cathode material D Ｖ５０ The modified cathode material according to claim 1 or 2, wherein the particle size is 2 μm to 10 μm.

7. The modified cathode material according to claim 1 or 2, wherein the cathode material is one or more of the group consisting of a layered cathode material, a lithium-rich manganese cathode material, a spinel-type lithium nickel manganate cathode material, and a conversion-type cathode material, and selectively, the phase state of the cathode material is the O3 phase.

8. A method for producing a modified cathode material according to claim 1 or 2, Step S1 for preparing a polymer electrolyte solution, Step S2 involves mixing a ferroelectric ceramic material and a cathode material to obtain a cathode material coated with the ferroelectric ceramic material, Step S3 involves mixing the polymer electrolyte solution and the positive electrode material coated with the ferroelectric ceramic material, drying them, and obtaining the modified positive electrode material. A method for producing a modified cathode material containing [the specified substance].

9. The manufacturing method according to claim 8, wherein W1 is the total mass of the polymer electrolyte, the positive electrode material and the ferroelectric ceramic material, W2 is the mass of the polymer electrolyte and W3 is the mass of the ferroelectric ceramic material, and W2 / W1 is between 0.5 wt% and 5 wt%, and W3 / (W2 + W3) is between 2% and 10%, and selectively between 2% and 5%.

10. The manufacturing method according to claim 9, wherein the mass content of the polymer electrolyte in the solution of the polymer electrolyte is 0.5% to 10%, and the solvent used in the solution of the polymer electrolyte is one or more selected from the group consisting of anhydrous ethanol, N-methylpyrrolidone (NMP), and N,N-dimethylformamide (DMF).

11. The manufacturing method according to claim 9, wherein the drying in step S3 is spray drying, and selectively, the intake air temperature for the spray drying is 130°C to 220°C, and the exhaust air temperature for the spray drying is 60°C to 80°C.

12. A positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer installed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprises the modified positive electrode material described in claim 1, and selectively, the content of the modified positive electrode material in the positive electrode film layer is 70% by weight or more, and selectively, 80% to 90% by weight, relative to the total weight of the positive electrode film layer.

13. A secondary battery comprising the positive electrode sheet described in claim 12.

14. A battery module including the secondary battery described in claim 13.

15. A battery pack comprising the battery module described in claim 14.

16. A power consumption device comprising at least one selected from the secondary battery described in claim 13, the battery module described in claim 14, or the battery pack described in claim 15.

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