Polythiophene conductive polymer, positive electrode slurry, positive electrode sheet and preparation method therefor, battery cell, battery, and electric device

Abstract

The present application discloses a polythiophene conductive polymer, a positive electrode slurry, a positive electrode sheet and a preparation method therefor, a battery cell, a battery, and an electric device. The polythiophene conductive polymer comprises a first structural unit shown in formula (1) and at least one of a second structural unit shown in formula (2), a third structural unit shown in formula (3) and a fourth structural unit shown in formula (4).

Description

Polythiophene conductive polymer, positive electrode slurry, positive electrode sheet and preparation method thereof, battery cell, battery and electrical device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202310806166.1 filed on July 3, 2023, entitled “Polythiophene conductive polymer, positive electrode slurry, positive electrode sheet and preparation method thereof, battery cell, battery and electrical device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to a polythiophene conductive polymer, a positive electrode slurry, a positive electrode plate and a preparation method thereof, a battery cell, a battery and an electrical device. Background Art

[0004] In recent years, batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. In recent years, with the continuous expansion of battery applications, the requirements for comprehensive battery performance have also continued to increase. However, how to make batteries have both high energy density and good processing performance and rate performance remains a technical challenge that needs to be solved. The above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art.

[0005] Summary of the Invention

[0006] The present application provides a polythiophene conductive polymer, a positive electrode slurry, a positive electrode plate and a preparation method thereof, a battery cell, a battery and an electrical device, which can enable the battery to have both high energy density and good rate performance.

[0007] In a first aspect, the present application provides a polythiophene conductive polymer comprising: a first structural unit represented by formula (1); and at least one of a second structural unit represented by formula (2), a third structural unit represented by formula (3), and a fourth structural unit represented by formula (4).

[0008] R 11 Including C1-C8 alkyl or C1-C8 alkyl alkoxy, R 12 including hydrogen atoms or C1-C3 alkyl groups; R 21 Including C1-C5 alkylene, R 22 including hydrogen atoms or C1-C3 alkyl groups, M including monovalent metals; R 31 Including C1-C5 alkylene, R 32 including hydrogen atoms or C1-C3 alkyl groups; R 41Including C1-C5 alkylene, R 42 Including diisocyanate residues, R 43 Including C2-C6 alkylene, R 44 Including C1-C3 alkyl, R 45 Including a hydrogen atom or a C1-C3 alkyl group, s≥1; n1>0; n2≥0, n3≥0, n4≥0, and n2+n3+n4>0.

[0009] By making the positive electrode plate include the polythiophene conductive polymer of the present application, the cohesion and adhesion of the positive electrode plate can be improved, the electrolyte wettability of the positive electrode plate can be improved, and the processing performance and dynamic performance of the positive electrode plate can be improved, thereby enabling the battery to have both high energy density and good rate performance.

[0010] In any embodiment, the polythiophene conductive polymer has a number average molecular weight of 3,000-45,000, optionally 5,000-34,000. When the number average molecular weight of the polythiophene conductive polymer is within the above range, the positive electrode sheet can have good flexibility, thereby improving the processing performance of the positive electrode sheet and the battery; in addition, the positive electrode slurry can have good dispersibility, thereby further improving the performance of the battery.

[0011] In any embodiment, the polythiophene conductive polymer satisfies at least one of the following conditions (1) to (13):

[0012] (1)R 11 including C4-C6 alkyl or C4-C6 alkylalkoxy;

[0013] (2)R 12 including hydrogen atoms;

[0014] (3)R 21 including C1-C3 alkylene;

[0015] (4)R 22 including hydrogen atoms;

[0016] (5) M includes Li and / or Na;

[0017] (6)R 31 including C1-C3 alkylene;

[0018] (7)R 32 including hydrogen atoms;

[0019] (8)R 41 including C1-C3 alkylene;

[0020] (9)R 42 Including R a Substituted or unsubstituted C1-C6 alkylene, and one of the following groups:

[0021] # indicates the connection position, R a Each independently includes C1-C3 alkyl, R b Each independently includes a C1-C3 alkyl group, p represents an integer of 0-4, and q represents an integer of 0-6;

[0022] (10)R 43 Includes the following groups:

[0023] (11)R 44 including methyl;

[0024] (12)R 45 including hydrogen atoms;

[0025] (13)s is 3-140, and can be selected as 10-90.

[0026] In any embodiment, n2>0, n3=0, n4=0; or, n2=0, n3>0, n4=0; or, n2=0, n3>0, n4>0; or, n2>0, n3>0, n4>0.

[0027] The second aspect of the present application provides a positive electrode slurry, comprising a solvent and a non-solvent component, wherein the non-solvent component comprises a positive electrode active material, a positive electrode binder and a positive electrode conductor, and the positive electrode conductor comprises the polythiophene conductive polymer of the first aspect of the present application.

[0028] In any embodiment, the solvent includes a non-aqueous solvent, optionally including N-methylpyrrolidone, and the positive electrode binder includes an oily binder, and 0.35≤n1 / (n1+n2+n3+n4)≤0.65; optionally, 0.40≤n1 / (n1+n2+n3+n4)≤0.60. When n1 / (n1+n2+n3+n4) is within the above range, the dispersibility of the non-aqueous positive electrode slurry can be improved, the processing performance of the prepared positive electrode sheet can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0029] In any embodiment, the positive electrode binder includes one or more of polyvinylidene fluoride, polyimide, and polyurethane.

[0030] In any embodiment, the positive electrode binder includes an oily binder, and 0≤n2 / (n1+n2+n3+n4)≤0.25, and optionally, 0≤n2 / (n1+n2+n3+n4)≤0.10. This can improve the dispersibility of the non-aqueous positive electrode slurry and the dynamic performance of the positive electrode sheet and the battery.

[0031] In any embodiment, the positive electrode binder includes an oily binder, and 0.35≤(n3+n4) / (n1+n2+n3+n4)≤0.65, optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60. When (n3+n4) / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the bonding strength and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can be improved.

[0032] In any embodiment, the positive electrode binder includes an oily binder, and 0 ≤ n4 / (n3+n4) ≤ 0.20, optionally, 0 < n4 / (n3+n4) ≤ 0.15. When n4 / (n3+n4) is within the above range, the processing performance of the positive electrode sheet and the battery can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0033] In any embodiment, the solvent includes water, the positive electrode binder includes an aqueous binder, and 0.05≤n1 / (n1+n2+n3+n4)≤0.25; optionally, 0.08≤n1 / (n1+n2+n3+n4)≤0.22. When n1 / (n1+n2+n3+n4) is within the above range, the dispersibility of the aqueous positive electrode slurry can be improved, the bonding strength and processing performance of the prepared positive electrode sheet can be improved, and the dynamic performance of the positive electrode sheet and the battery can be improved.

[0034] In any embodiment, the positive electrode binder includes one or more of carboxymethyl cellulose and its derivatives, sodium alginate, polyacrylic acid and its derivatives, agarose, gelatin, carrageenan, xanthan gum, guar gum, polyvinyl alcohol, and polyacrylamide.

[0035] In any embodiment, the positive electrode binder includes an aqueous binder, and 0.15≤n2 / (n1+n2+n3+n4)≤0.45, optionally, 0.25≤n2 / (n1+n2+n3+n4)≤0.40. When n2 / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the bonding strength and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can be improved.

[0036] In any embodiment, the positive electrode binder includes an aqueous binder, and 0.30≤(n3+n4) / (n1+n2+n3+n4)≤0.80, optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60. When (n3+n4) / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the bonding strength and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can be improved.

[0037] In any embodiment, the positive electrode binder includes an aqueous binder, and 0≤n4 / (n3+n4)≤0.20, optionally, 0.04≤n4 / (n3+n4)≤0.15. When n4 / (n3+n4) is within the above range, the processing performance of the positive electrode sheet and the battery can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0038] In any embodiment, the positive electrode active material includes one or more of lithium transition metal oxides, lithium-containing phosphates, and modified compounds thereof.

[0039] In any embodiment, the positive electrode slurry further includes a second conductive agent, and the second conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0040] In any embodiment, the content of the polythiophene conductive polymer in the non-solvent component is 0.2-4%, optionally 0.5-3%, based on the total weight of the non-solvent component.

[0041] The third aspect of the present application provides a positive electrode plate, comprising a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material, a positive electrode binder and a positive electrode conductor, and the positive electrode conductor comprises the polythiophene conductive polymer of the first aspect of the present application.

[0042] In any embodiment, the positive electrode binder includes an oily binder, and 0.35≤n1 / (n1+n2+n3+n4)≤0.65; optionally, 0.40≤n1 / (n1+n2+n3+n4)≤0.60. When n1 / (n1+n2+n3+n4) is within the above range, the uniformity of the positive electrode film layer can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0043] In any embodiment, the positive electrode binder includes one or more of polyvinylidene fluoride, polyimide, and polyurethane.

[0044] In any embodiment, the positive electrode binder includes an oily binder, and 0≤n2 / (n1+n2+n3+n4)≤0.25, and optionally, 0≤n2 / (n1+n2+n3+n4)≤0.10. This can improve the uniformity of the positive electrode film layer and the dynamic performance of the positive electrode sheet and the battery.

[0045] In any embodiment, the positive electrode binder includes an oily binder, and 0.35≤(n3+n4) / (n1+n2+n3+n4)≤0.65, optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60. When (n3+n4) / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the bonding strength and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can be improved.

[0046] In any embodiment, the positive electrode binder includes an oily binder, and 0 ≤ n4 / (n3+n4) ≤ 0.20, optionally, 0 < n4 / (n3+n4) ≤ 0.15. When n4 / (n3+n4) is within the above range, the processing performance of the positive electrode sheet and the battery can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0047] In any embodiment, the positive electrode binder includes an aqueous binder, and 0.05 ≤ n1 / (n1+n2+n3+n4) ≤ 0.25; optionally, 0.08 ≤ n1 / (n1+n2+n3+n4) ≤ 0.22. When n1 / (n1+n2+n3+n4) is within the above range, the uniformity of the positive electrode film layer can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0048] In any embodiment, the positive electrode binder includes one or more of carboxymethyl cellulose and its derivatives, sodium alginate, polyacrylic acid and its derivatives, agarose, gelatin, carrageenan, xanthan gum, guar gum, polyvinyl alcohol, and polyacrylamide.

[0049] In any embodiment, the positive electrode binder includes an aqueous binder, and 0.15≤n2 / (n1+n2+n3+n4)≤0.45, optionally, 0.25≤n2 / (n1+n2+n3+n4)≤0.40. When n2 / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the bonding strength and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can be improved.

[0050] In any embodiment, the positive electrode binder includes an aqueous binder, and 0.30≤(n3+n4) / (n1+n2+n3+n4)≤0.80, optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60. When (n3+n4) / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the bonding strength and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can be improved.

[0051] In any embodiment, the positive electrode binder includes an aqueous binder, and 0≤n4 / (n3+n4)≤0.20, optionally, 0.04≤n4 / (n3+n4)≤0.15. When n4 / (n3+n4) is within the above range, the processing performance of the positive electrode sheet and the battery can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0052] In any embodiment, the positive electrode active material includes one or more of lithium transition metal oxides, lithium-containing phosphates, and modified compounds thereof.

[0053] In any embodiment, the positive electrode plate further includes a second conductive agent, which includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0054] In any embodiment, the content of the polythiophene conductive polymer in the positive electrode film layer is 0.2-4%, optionally 0.5-3%, based on the total weight of the positive electrode film layer.

[0055] The fourth aspect of the present application provides a method for preparing a positive electrode sheet, comprising the following steps: coating the positive electrode slurry of the second aspect of the present application on at least one surface of a positive electrode current collector, drying and rolling to obtain an initial positive electrode sheet; irradiating the initial positive electrode sheet obtained with a laser, and obtaining a positive electrode sheet after completion, wherein the laser wavelength is 445-505nm.

[0056] By using the above-mentioned polythiophene conductive polymer in the positive electrode plate and irradiating the positive electrode plate with blue light, photothermal conversion can be quickly performed, heating efficiency can be improved, and the adverse effects of blue light irradiation on the positive electrode active material can be reduced.

[0057] Blue light irradiation can rapidly heat the polythiophene conductive polymer, thereby releasing some stress and facilitating the formation of a positive electrode film with a higher porosity, thereby reducing the amount of residual solvent and improving the electrolyte wettability of the positive electrode sheet. Blue light irradiation can also remove substances such as dispersants and surfactants introduced during the processing of the positive electrode sheet. The heating efficiency is high, and the heating temperature is usually higher than the softening point of the positive electrode binder. This allows the positive electrode binder to be evenly distributed throughout the thickness of the positive electrode sheet, thereby helping to improve the cohesion and adhesion of the positive electrode sheet, reduce the positive electrode resistance, and thus improve the battery's rate performance.

[0058] In any embodiment, the laser is emitted in a continuous manner.

[0059] In any embodiment, the number of lasers is 1-10, and the total power is 100-2500W.

[0060] In any embodiment, the time for the initial positive electrode plate to pass through the laser spot is 0.05-0.5s.

[0061] In any embodiment, the vertical distance between the laser and the initial positive electrode plate is 5-15 cm.

[0062] A fifth aspect of the present application provides a battery cell, comprising the positive electrode sheet of the third aspect of the present application or the positive electrode sheet prepared by the preparation method of the fourth aspect of the present application.

[0063] A sixth aspect of the present application provides a battery, comprising a battery cell according to the fifth aspect of the present application.

[0064] The seventh aspect of the present application provides an electrical device, which includes the battery of the sixth aspect of the present application.

[0065] The electric device of the present application includes the battery provided by the present application, and thus has at least the same advantages as the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on the drawings without inventive effort.

[0067] FIG1 is a schematic structural diagram of a battery cell provided in some embodiments of the present application.

[0068] FIG2 is an exploded schematic diagram of a battery cell provided in some embodiments of the present application.

[0069] FIG3 is a schematic structural diagram of a battery module provided in some embodiments of the present application.

[0070] FIG4 is a schematic structural diagram of a battery pack provided in some embodiments of the present application.

[0071] FIG5 is an exploded schematic diagram of the battery pack shown in FIG4 .

[0072] FIG6 is a schematic diagram of an electrical device provided in some embodiments of the present application.

[0073] FIG7 is a discharge curve of the battery of Example 1-1 and Comparative Example 1-1 at different rates.

[0074] In the accompanying drawings, which are not necessarily drawn to scale, the reference numerals are as follows: 1. battery pack; 2. upper housing; 3. lower housing; 4. battery module; 5. battery cell; 51. housing; 52. electrode assembly; 53. cover plate. DETAILED DESCRIPTION

[0075] Below, with appropriate reference to the accompanying drawings, the embodiments of the polythiophene conductive polymer, positive electrode slurry, positive electrode sheet and its preparation method, battery cell, battery and electrical device of the present application are specifically disclosed in detail. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0076] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0077] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0078] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0079] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0080] Unless otherwise specified, in this application, the terms "first", "second", "third", "fourth", etc. are used to distinguish different objects rather than to describe a specific order or a primary-secondary relationship.

[0081] In this application, the terms "plurality" and "multiple" refer to two or more.

[0082] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0083] Unless otherwise stated, the numerical values ​​of the various parameters mentioned in this application can be measured using various test methods commonly used in the art, for example, they can be measured according to the test methods given in the examples of this application. Unless otherwise stated, the test temperature of each parameter is 25°C.

[0084] The term "alkyl" encompasses straight-chain and branched-chain alkyl groups.

[0085] The term "alkylene" encompasses straight chain and branched chain alkylene groups.

[0086] The term "alkylalkoxy" encompasses straight chain alkylalkoxy and branched chain alkylalkoxy.

[0087] The term "hydrogen atom" covers 1 H(H), 2 H(D) and 3 H(T).

[0088] Throughout this manual, “#” indicates a connection location.

[0089] Throughout the present specification, the expression "a single bond passes through a ring or a ring system" means that the single bond can be attached to any accessible position of the ring or the ring system.

[0090] Throughout this specification, substituents of compounds are disclosed in groups or ranges. It is expressly contemplated that this description includes each individual subcombination of members of these groups and ranges. For example, it is expressly contemplated that the term "C1-C6 alkyl" individually discloses C1, C2, C3, C4, C5, C6, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C6, C2-C5, C2-C4, C2-C3, C3-C6, C3-C5, C3-C4, C4-C6, C4-C5, C5-C6 alkyl. As another example, integers ranging from 3 to 10 are expressly contemplated to individually disclose 3, 4, 5, 6, 7, 8, 9, and 10. Accordingly, other groups or ranges may be expressly contemplated.

[0091] The battery mentioned in the embodiments of the present application may be a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery cell, a battery module, or a battery pack.

[0092] A battery cell is the smallest unit of a battery, independently capable of charging and discharging. A battery cell can be cylindrical, rectangular, or have other shapes, though this is not a limitation in the present invention. Figure 1 shows a battery cell 5 with a rectangular structure as an example.

[0093] When there are multiple battery cells, the multiple battery cells are connected in series, in parallel, or in mixed series via a busbar. In some embodiments, the battery may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. In some embodiments, the battery may be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed in the housing. In some embodiments, the housing may serve as part of the vehicle's chassis structure. For example, a portion of the housing may form at least a portion of the vehicle's floor, or a portion of the housing may form at least a portion of the vehicle's crossbeam or longitudinal beam.

[0094] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0095] The battery cells provided in the embodiments of the present application include lithium-ion battery cells, lithium metal battery cells, etc., which are not limited in the embodiments of the present application.

[0096] A battery cell generally includes an electrode assembly and an electrolyte. The electrode assembly generally includes a positive electrode sheet and a negative electrode sheet. The electrode assembly can be a wound structure or a stacked structure, which is not limited in the present embodiment.

[0097] The battery cell may also include an outer packaging, which can be used to encapsulate the electrode assembly and electrolyte. The outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, steel shell, etc. The outer packaging can also be a soft package, such as a pouch-type soft package. The soft package can be made of plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0098] In some embodiments, as shown in Figure 2, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, which together form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening, thereby sealing the receiving cavity. The electrode assembly 52 is enclosed in the receiving cavity. The number of electrode assemblies 52 contained in a battery cell 5 can be one or more, and can be adjusted according to needs.

[0099] In some embodiments, battery cells can be assembled into a battery module. The number of battery cells contained in a battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module. Figure 3 is a schematic diagram of a battery module 4 as an example. As shown in Figure 3, in the battery module 4, multiple battery cells 5 can be arranged in sequence along the length of the battery module 4. Of course, they can also be arranged in any other manner. The multiple battery cells 5 can further be fixed by fasteners.

[0100] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0101] In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0102] Figures 4 and 5 are schematic diagrams of an exemplary battery pack 1. As shown in Figures 4 and 5, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The housing comprises an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3 and forms an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 may be arranged in any manner within the housing.

[0103] The positive electrode is an important component of the battery, and its performance has a crucial impact on battery performance.

[0104] In order to further improve the energy density of the battery, the current common practice is to prepare thick-coated positive electrode sheets or high-density positive electrode sheets. However, thick-coated and / or high-density positive electrode sheets generally have poor flexibility and processing performance. During bending, winding, or hot pressing of the electrode assembly, the positive electrode film layer is prone to cracking or partial shedding of the positive electrode film layer from the surface of the positive electrode current collector (i.e., powder loss). In addition, residual solvents (such as water, N-methylpyrrolidone, etc.) in the positive electrode sheet are difficult to fully remove, resulting in poor electrolyte wettability of the positive electrode film layer, making it difficult to fully distribute the electrolyte in the positive electrode film layer, which in turn affects the battery's rate performance.

[0105] Therefore, how to make the battery have good processing performance and rate performance while having high energy density is still a technical problem that needs to be solved.

[0106] In view of this, the inventors proposed a new polythiophene conductive polymer, which is used in the positive electrode. After laser irradiation treatment, the processing performance of the positive electrode can be improved, and the battery can also have high energy density and good rate performance.

[0107] [Polythiophene conductive polymer]

[0108] The polythiophene conductive polymer provided in the embodiment of the present application includes a first structural unit represented by formula (1) and at least one of a second structural unit represented by formula (2), a third structural unit represented by formula (3), and a fourth structural unit represented by formula (4).

[0109] R 11 Including C1-C8 alkyl or C1-C8 alkyl alkoxy, R 12 This includes a hydrogen atom or a C1-C3 alkyl group.

[0110] R 21 Including C1-C5 alkylene, R 22 includes a hydrogen atom or a C1-C3 alkyl group, and M includes a monovalent metal.

[0111] R 31 Including C1-C5 alkylene, R 32 This includes a hydrogen atom or a C1-C3 alkyl group.

[0112] R 41 Including C1-C5 alkylene, R 42 Including diisocyanate residues, R 43 Including C2-C6 alkylene, R 44 Including C1-C3 alkyl, R 45 Including hydrogen atom or C1-C3 alkyl, s≥1. 42Including the residue of diisocyanate, that is, diisocyanate O=C=N-R 42 —N=C=O is the remaining group after removing the isocyanate groups at both ends.

[0113] n1>0.

[0114] n2≥0, n3≥0, n4≥0, and n2+n3+n4>0.

[0115] To reduce positive electrode resistance, the current common practice is to increase the amount of positive electrode conductive agents, such as conductive carbon, when preparing the positive electrode slurry. This not only reduces the overall resistance of the positive electrode film, but also improves the battery's rate performance. However, for high-energy-density battery systems, due to the high coating weight and high compaction density of the positive electrode sheet, the dispersion uniformity of the conductive carbon deteriorates. Therefore, this method has limited effect on improving the battery's internal resistance and rate performance. At the same time, the processing performance of the positive electrode sheet and battery is still relatively poor.

[0116] The inventors have found that by making the positive electrode plate include the polythiophene conductive polymer provided in the embodiments of the present application, the cohesion and adhesion of the positive electrode plate can be improved, the electrolyte wettability of the positive electrode plate can be improved, and the processing performance and dynamic performance of the positive electrode plate can be improved, thereby enabling the battery to have both high energy density and good rate performance.

[0117] The positive electrode active material in the positive electrode plate has a low absorption rate for blue light, while the polythiophene conductive polymer provided in the embodiment of the present application has a high blue light absorption capacity. Therefore, by using the polythiophene conductive polymer provided in the embodiment of the present application in the positive electrode plate and irradiating the positive electrode plate with blue light, photothermal conversion can be quickly performed, heating efficiency can be improved, and the adverse effects of blue light irradiation on the positive electrode active material can be reduced.

[0118] The polythiophene conductive polymer provided in the embodiments of the present application has good thermal conductivity. When it is used for the positive electrode sheet and the positive electrode sheet is irradiated with blue light, the polythiophene conductive polymer can be quickly heated, thereby releasing some stress, which is conducive to forming a positive electrode film layer with higher porosity, thereby reducing the amount of residual solvent and improving the electrolyte wettability of the positive electrode sheet; when heated, the positive electrode binder can also be softened, so that the polythiophene conductive polymer and the positive electrode binder are more evenly distributed in the positive electrode film layer, thereby increasing the cohesion and adhesion of the positive electrode sheet, and reducing the positive electrode resistance, thereby improving the dynamic performance of the positive electrode sheet and the battery.

[0119] The polythiophene conductive polymer provided in the embodiment of the present application includes at least one of the second structural unit shown in formula (2), the third structural unit shown in formula (3) and the fourth structural unit shown in formula (4). The second structural unit shown in formula (2), the third structural unit shown in formula (3) and the fourth structural unit shown in formula (4) have strong polar groups, such as hydroxyl groups, ester groups, carbamate groups, etc. These strong polar groups can red-shift the absorption wavelength of the polythiophene conductive polymer, thereby reducing the electrochemical band gap between the HOMO orbital and the LUMO orbital, and further increasing the position of the maximum absorption peak of the polythiophene conductive polymer, thereby improving the heating efficiency. The polythiophene conductive polymer provided in the embodiment of the present application also includes the first structural unit shown in formula (1), thereby making the positive electrode film layer have good electrolyte wettability and preventing the polythiophene conductive polymer from dissolving.

[0120] The polythiophene conductive polymers provided in the embodiments of this application, when used in the positive electrode film, can also improve the flexibility and processing performance of positive electrode sheets, particularly those with thick coatings and / or high compaction densities. Furthermore, the polythiophene conductive polymers provided in the embodiments of this application are electrically conductive and, when used in positive electrode sheets, can also provide a good electron conduction pathway.

[0121] Therefore, the polythiophene conductive polymer provided in the embodiment of the present application can improve the processing performance of the positive electrode sheet, improve the cohesion and adhesion of the positive electrode sheet, and reduce the positive electrode resistance. When used in a battery, a battery with both high energy density and good rate performance can be obtained.

[0122] The polythiophene conductive polymer provided in the embodiment of the present application includes a first structural unit represented by formula (1) and at least one of a second structural unit represented by formula (2), a third structural unit represented by formula (3), and a fourth structural unit represented by formula (4). For example, in some embodiments, the polythiophene conductive polymer includes a first structural unit represented by formula (1) and a second structural unit represented by formula (2), in which case n2>0, n3=0, and n4=0; in some embodiments, the polythiophene conductive polymer includes a first structural unit represented by formula (1) and a third structural unit represented by formula (3), in which case n2=0, n3>0, and n4=0; in some embodiments, the polythiophene conductive polymer includes a first structural unit represented by formula (1), a third structural unit represented by formula (3), and a fourth structural unit represented by formula (4), in which case n2=0, n3>0, and n4>0; in some embodiments, the polythiophene conductive polymer includes a first structural unit represented by formula (1), a second structural unit represented by formula (2), a third structural unit represented by formula (3), and a fourth structural unit represented by formula (4), in which case n2>0, n3>0, and n4>0.

[0123] In some embodiments, the number average molecular weight of the polythiophene conductive polymer can be 3000-45000, for example, 3000, 4000, 5000, 7600, 8600, 10000, 12000, 15000, 18000, 20500, 23000, 25200, 28000, 30000, 34000, 40000, 45000, or any range thereof. In some embodiments, the polythiophene conductive polymer may optionally have a number average molecular weight of 5000-34000, 7600-34000, 10000-34000, 5000-30000, 7600-30000, 10000-30000, 5000-28000, 7600-28000, 10000-28000, 5000-25200, 7600-25200, 10000-25200.

[0124] When the number average molecular weight of the polythiophene conductive polymer is within the above range, the positive electrode sheet can have good flexibility, thereby improving the processing performance of the positive electrode sheet and the battery; in addition, the positive electrode slurry can have good dispersibility and the polythiophene conductive polymer can be prevented from dissolving in the electrolyte, thereby better improving the performance of the battery.

[0125] When the number average molecular weight of the polythiophene conductive polymer is within the above range, the polythiophene conductive polymer can also have good thermal conductivity and electronic conductivity, thereby improving heating efficiency and reducing positive electrode resistance.

[0126] The number average molecular weight of the polythiophene conductive polymer has a well-known meaning in the art and can be measured using instruments and methods known in the art, for example, by gel permeation chromatography (GPC).

[0127] In some embodiments, R 11 A C4-C6 alkyl group or a C4-C6 alkylalkoxy group may be included.

[0128] In some embodiments, R 12 Hydrogen atoms may be included.

[0129] In some embodiments, R 11 Including C4-C6 alkyl or C4-C6 alkylalkoxy, R 12 Including hydrogen atoms.

[0130] In some embodiments, R 21 C1-C3 alkylene groups may be included.

[0131] In some embodiments, R 22 Hydrogen atoms may be included.

[0132] In some embodiments, M may include Li and / or Na.

[0133] In some embodiments, R 21 Including C1-C3 alkylene, R 22 includes a hydrogen atom, and M includes Li and / or Na.

[0134] In some embodiments, R 31 C1-C3 alkylene groups may be included.

[0135] In some embodiments, R 32 Hydrogen atoms may be included.

[0136] In some embodiments, R 31 Including C1-C3 alkylene, R 32 Including hydrogen atoms.

[0137] In some embodiments, R 41 C1-C3 alkylene groups may be included.

[0138] In some embodiments, R 42 may represent the residue of an aliphatic, alicyclic and / or aromatic diisocyanate. 42 Including R a Substituted or unsubstituted C1-C6 alkylene, and one of the following groups:

[0139] # indicates the connection position, R a Each independently includes C1-C3 alkyl, R b Each independently includes a C1-C3 alkyl group, p represents an integer from 0 to 4, and q represents an integer from 0 to 6. When p is 0, it indicates that no substitution occurs at that position. When q is 0, it indicates that no substitution occurs at that position.

[0140] In some embodiments, R 43 The following groups may be included:

[0141] In some embodiments, R 44 A methyl group may be included.

[0142] In some embodiments, R 45 Hydrogen atoms may be included.

[0143] In some embodiments, s may be 3-140, for example, 3, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, or any range thereof. In some embodiments, s may be 10-90, 10-80, 10-70, 10-60, 10-50, 20-90, 20-80, 20-70, 20-60, 20-50, 25-90, 25-80, 25-70, 25-60, 25-50.

[0144] [Preparation method of polythiophene conductive polymer]

[0145] The present application also provides a method for preparing the polythiophene conductive polymer.

[0146] The method comprises at least the steps of: providing a monomer compound or a precursor compound for preparing a polythiophene conductive polymer; and subjecting the monomer compound or the precursor compound to oxidative polymerization to obtain the polythiophene conductive polymer. The oxidative polymerization method may be a chemical oxidative polymerization method or an electrochemical oxidative polymerization method. For example, the oxidant in the chemical oxidative polymerization method may be FeCl3.

[0147] Those skilled in the art can select appropriate monomer compounds or their precursor compounds according to the target product.

[0148] For example, the first monomer compound used to form the first structural unit can be

[0149] As an example, the first monomer compound may include one or more of 3-butoxythiophene and 3-pentoxythiophene.

[0150] The first monomer compound can be obtained by alkyl chain displacement using methoxythiophene as a raw material. In some embodiments, methoxythiophene, an alcohol (e.g., n-butanol, n-pentanol, etc.), anhydrous sodium bisulfate, and toluene are sequentially added to a reaction system in a nitrogen environment, heated and stirred at 80-100° C. for 2-5 hours, and then distilled under reduced pressure to obtain the first monomer compound.

[0151] The second monomer compound used to form the second structural unit can be or its precursor compound R 23 Including C1-C8 alkyl.

[0152] As an example, the second monomer compound may include one or more of sodium thiophene-3-oxyacetate, lithium thiophene-3-oxyacetate, sodium 2-(thiophene-3-oxy)propionate, lithium 2-(thiophene-3-oxy)propionate, sodium 3-(thiophene-3-oxy)propionate, and lithium 3-(thiophene-3-oxy)propionate, and the precursor compound of the second monomer compound may include one or more of methyl thiophene-3-oxyacetate, ethyl thiophene-3-oxyacetate, methyl 2-(thiophene-3-oxy)propionate, ethyl 2-(thiophene-3-oxy)propionate, methyl 3-(thiophene-3-oxy)propionate, and ethyl 3-(thiophene-3-oxy)propionate.

[0153] The precursor compound of the second monomer compound can be obtained by alkyl chain displacement using methoxythiophene as a raw material. In some embodiments, in a nitrogen environment, methoxythiophene, an ester (e.g., methyl glycolate, ethyl glycolate, methyl lactate, ethyl lactate, methyl β-hydroxypropionate, ethyl β-hydroxypropionate, etc.), anhydrous sodium bisulfate, and toluene are sequentially added to a reaction system, heated and stirred at 80-100° C. for 2-5 hours, and the precursor compound of the second monomer compound is obtained by distillation under reduced pressure.

[0154] The second monomer compound can be prepared by placing a precursor compound of the second monomer compound in an alkaline solution, adjusting the pH, and stirring the solution to obtain the second monomer compound. The alkaline solution can include MOH, where M includes a monovalent metal, optionally including Li and / or Na.

[0155] The third monomer compound used to form the third structural unit can be

[0156] As an example, the third monomer compound may include one or more of 3-thiophene methanol and 3-thiophene ethanol.

[0157] The fourth monomer compound used to form the fourth structural unit can be

[0158] The fourth monomer compound can be prepared by the following method: under nitrogen environment, OH—(R 43 ) s —O—R 44 , diisocyanate OCN-R 42 —NCO is dissolved in a solvent (such as N,N-dimethylformamide), stirred at 70°C for 1-4h, and then added The reaction was continued at 70° C. with stirring under nitrogen protection for 4-8 hours to obtain the fourth monomer compound.

[0159] OH—(R 43 ) s —O—R 44It may include polyethylene glycol monomethyl ether (MPEG) and polybutylene glycol monomethyl ether.

[0160] In some embodiments, the method includes the steps of: dissolving a monomer compound or a precursor compound thereof in chloroform, then adding it to a chloroform solution of anhydrous FeCl3 under nitrogen protection, performing a polymerization reaction at 20-25°C (e.g., 24-96 hours), then adding methanol to precipitate the polymerization product, and finally extracting the precipitate in ethanol (e.g., 24-96 hours), and obtaining a polythiophene conductive polymer after drying.

[0161] In some embodiments, the method comprises the steps of: dissolving the first monomer compound, the second monomer compound, and the third monomer compound in chloroform, then adding them to a chloroform solution of anhydrous FeCl3 under nitrogen protection, performing a polymerization reaction at 20-25°C (e.g., 24-96 hours), then adding methanol to precipitate the polymer product, and finally extracting the precipitate in ethanol (e.g., 24-96 hours); under nitrogen environment, 43 ) s —O—R 44 , diisocyanate OCN-R 42 —NCO is dissolved in a solvent (e.g., N,N-dimethylformamide) and stirred at 65-75°C for 1-4 hours. The precipitate solution (the solvent can be N,N-dimethylformamide) is then added and stirred at 65-75°C for 4-8 hours under nitrogen protection. The mixture is then extracted with ethanol (e.g., for 12-48 hours) and vacuum dried to obtain a polythiophene conductive polymer. The polythiophene conductive polymer includes a first structural unit, a second structural unit, a third structural unit, and a fourth structural unit.

[0162] In some embodiments, the method comprises the steps of: dissolving a first monomer compound, a precursor compound of a second monomer compound, and a third monomer compound in chloroform, then adding them to a chloroform solution of anhydrous FeCl3 under nitrogen protection, performing a polymerization reaction at 20-25°C (e.g., 24-96 hours), then adding methanol to precipitate the polymer product, and finally extracting the precipitate in ethanol (e.g., 24-96 hours); under nitrogen environment, 43 ) s —O—R 44 , diisocyanate OCN-R 42—NCO is dissolved in a solvent (e.g., N,N-dimethylformamide), stirred and reacted at 65-75°C for 1-4 hours, then the above-mentioned precipitate solution (the solvent can be N,N-dimethylformamide) is added, and the stirring reaction is continued at 65-75°C under nitrogen protection for 4-8 hours. After that, it is extracted with ethanol (e.g., 12-48 hours), vacuum-dried, and the product is dispersed in water. MOH is added to adjust the pH of the system (e.g., 7-9), and stirred and reacted to obtain a polythiophene conductive polymer. The polythiophene conductive polymer includes a first structural unit, a second structural unit, a third structural unit, and a fourth structural unit.

[0163] By adjusting parameters such as the type and concentration of monomers, the type and concentration of oxidants, reaction temperature, reaction time, etc., polythiophene conductive polymers with different molecular weights can be obtained.

[0164] [Cathode slurry]

[0165] The embodiment of the present application also provides a positive electrode slurry.

[0166] The positive electrode slurry includes a solvent and a non-solvent component. The non-solvent component includes a positive electrode active material, a positive electrode binder, and a positive electrode conductor. The positive electrode conductor includes the polythiophene conductive polymer described above in this application.

[0167] The polythiophene conductive polymer provided in the embodiments of the present application can be used in both non-aqueous positive electrode slurry and aqueous positive electrode slurry.

[0168] In some embodiments, the solvent includes a non-aqueous solvent, optionally including N-methylpyrrolidone, the positive electrode binder includes an oily binder, and 0.35 ≤ n1 / (n1+n2+n3+n4) ≤ 0.65. For example, n1 / (n1+n2+n3+n4) can be 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, or a range consisting of any of the above values.

[0169] Optionally, 0.40≤n1 / (n1+n2+n3+n4)≤0.60.

[0170] When n1 / (n1+n2+n3+n4) is within the above range, the dispersibility of the non-aqueous positive electrode slurry can be improved, the processing performance of the prepared positive electrode sheet can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0171] In some embodiments, the positive electrode binder includes an oily binder. For example, the positive electrode binder may include one or more of polyvinylidene fluoride, polyimide, and polyurethane. The weight-average molecular weight of the polyvinylidene fluoride may be 50,000 to 2,000,000, thereby improving the bonding strength of the positive electrode sheet and the processing performance of the positive electrode sheet.

[0172] In some embodiments, the positive electrode binder includes an oily binder, 0≤n2 / (n1+n2+n3+n4)≤0.25, for example, n2 / (n1+n2+n3+n4) can be 0, 0.05, 0.10, 0.15, 0.20, 0.25, or a range consisting of any of the above values.

[0173] In some embodiments, the positive electrode binder includes an oily binder, 0≤n2 / (n1+n2+n3+n4)≤0.10, optionally, n2 / (n1+n2+n3+n4)=0.

[0174] This can improve the dispersibility of non-aqueous positive electrode slurry and improve the dynamic performance of positive electrode sheets and batteries.

[0175] In some embodiments, the positive electrode binder includes an oily binder, 0.35≤(n3+n4) / (n1+n2+n3+n4)≤0.65, for example, (n3+n4) / (n1+n2+n3+n4) can be 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, or a range consisting of any of the above values.

[0176] Optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60.

[0177] When (n3+n4) / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the adhesion and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0178] In some embodiments, 0≤n4 / (n3+n4)≤0.20, for example, n4 / (n3+n4) can be 0, 0.05, 0.10, 0.12, 0.15, 0.20, or a range consisting of any of the above values.

[0179] Optionally, 0<n4 / (n3+n4)≤0.15, 0<n4 / (n3+n4)≤0.12.

[0180] When n4 / (n3+n4) is within the above range, the processing performance of the positive electrode sheet and the battery can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0181] In some embodiments, the solvent includes a non-aqueous solvent, which may optionally include N-methylpyrrolidone, the positive electrode binder includes an oily binder, and 0.35≤n1 / (n1+n2+n3+n4)≤0.65, 0≤n2 / (n1+n2+n3+n4)≤0.25, 0.35≤(n3+n4) / (n1+n2+n3+n4)≤0.65, and 0<n4 / (n3+n4)≤0.15.

[0182] In some embodiments, the solvent includes a non-aqueous solvent, which may optionally include N-methylpyrrolidone, the positive electrode binder includes an oily binder, and 0.40≤n1 / (n1+n2+n3+n4)≤0.60, 0≤n2 / (n1+n2+n3+n4)≤0.10, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60, and 0<n4 / (n3+n4)≤0.15.

[0183] In some embodiments, the solvent includes a non-aqueous solvent, which may optionally include N-methylpyrrolidone, the positive electrode binder includes an oily binder, and 0.40≤n1 / (n1+n2+n3+n4)≤0.60, n2 / (n1+n2+n3+n4)=0, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60, 0<n4 / (n3+n4)≤0.15.

[0184] In some embodiments, the solvent includes water, the positive electrode binder includes an aqueous binder, and 0.05 ≤ n1 / (n1+n2+n3+n4) ≤ 0.25. For example, n1 / (n1+n2+n3+n4) can be 0.05, 0.08, 0.11, 0.15, 0.20, 0.22, 0.25, or a range consisting of any of the above values.

[0185] Optionally, 0.08≤n1 / (n1+n2+n3+n4)≤0.22, 0.11≤n1 / (n1+n2+n3+n4)≤0.22.

[0186] When n1 / (n1+n2+n3+n4) is within the above range, the dispersibility of the aqueous positive electrode slurry can be improved, the adhesion and processing performance of the prepared positive electrode sheet can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0187] In some embodiments, the positive electrode binder includes an aqueous binder. For example, the positive electrode binder may include one or more of carboxymethyl cellulose and its derivatives, sodium alginate, polyacrylic acid and its derivatives, agarose, gelatin, carrageenan, xanthan gum, guar gum, polyvinyl alcohol, and polyacrylamide. When the positive electrode binder is within the above range, it is more environmentally friendly and can also improve the electrolyte affinity of the positive electrode film layer.

[0188] In some embodiments, the positive electrode binder includes an aqueous binder, 0.15≤n2 / (n1+n2+n3+n4)≤0.45, for example, n2 / (n1+n2+n3+n4) can be 0.15, 0.20, 0.25, 0.30, 0.36, 0.40, 0.45, or a range consisting of any of the above values.

[0189] Optionally, 0.25≤n2 / (n1+n2+n3+n4)≤0.40, 0.25≤n2 / (n1+n2+n3+n4)≤0.36.

[0190] When n2 / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the bonding force and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can be improved.

[0191] In some embodiments, the positive electrode binder includes an aqueous binder, 0.30≤(n3+n4) / (n1+n2+n3+n4)≤0.80, for example, (n3+n4) / (n1+n2+n3+n4) can be 0.30, 0.35, 0.40, 0.42, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, or a range consisting of any of the above values.

[0192] Optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60, 0.42≤(n3+n4) / (n1+n2+n3+n4)≤0.60.

[0193] When (n3+n4) / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the adhesion and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0194] In some embodiments, the positive electrode binder includes an aqueous binder, 0≤n4 / (n3+n4)≤0.20, for example, n4 / (n3+n4) can be 0, 0.03, 0.04, 0.05, 0.08, 0.10, 0.12, 0.15, 0.20, or a range consisting of any of the above values.

[0195] Optionally, 0.04≤n4 / (n3+n4)≤0.15.

[0196] When n4 / (n3+n4) is within the above range, the processing performance of the positive electrode sheet and the battery can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0197] In some embodiments, the solvent includes water, the positive electrode binder includes an aqueous binder, and 0.05≤n1 / (n1+n2+n3+n4)≤0.25, 0.15≤n2 / (n1+n2+n3+n4)≤0.45, 0.30≤(n3+n4) / (n1+n2+n3+n4)≤0.80, and 0.04≤n4 / (n3+n4)≤0.15.

[0198] In some embodiments, the solvent includes water, the positive electrode binder includes an aqueous binder, and 0.08≤n1 / (n1+n2+n3+n4)≤0.22, 0.25≤n2 / (n1+n2+n3+n4)≤0.40, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60, and 0.04≤n4 / (n3+n4)≤0.15.

[0199] In some embodiments, the solvent includes water, the positive electrode binder includes an aqueous binder, and 0.11≤n1 / (n1+n2+n3+n4)≤0.22, 0.25≤n2 / (n1+n2+n3+n4)≤0.36, 0.42≤(n3+n4) / (n1+n2+n3+n4)≤0.60, and 0.04≤n4 / (n3+n4)≤0.15.

[0200] In some embodiments, the positive electrode active material may include one or more of a lithium transition metal oxide, a lithium-containing phosphate, and their respective modified compounds. Examples of lithium transition metal oxides may include one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of lithium-containing phosphates may include one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon, and their respective modified compounds. The present application is not limited to these materials, and other conventionally known materials that can be used as battery positive electrode active materials may also be used.

[0201] In some embodiments, the positive electrode active material may include a lithium-containing phosphate, optionally including one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and modified compounds thereof. These positive electrode active materials may be used alone or in combination of two or more.

[0202] The modified compounds of the above-mentioned positive electrode active materials may be used to perform doping modification and / or surface coating modification on the positive electrode active materials.

[0203] In some embodiments, the positive electrode slurry may further include a second conductive agent. As an example, the second conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0204] In some embodiments, the content of the polythiophene conductive polymer in the non-solvent component may be 0.2-4%, optionally 0.5-3%, based on the total weight of the non-solvent component.

[0205] The relative contents of different structural units in polythiophene conductive polymers can be measured by nuclear magnetic resonance spectroscopy (NMR).

[0206] [Positive electrode]

[0207] The embodiment of the present application also provides a positive electrode plate.

[0208] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material, a positive electrode binder and a positive electrode conductor. The positive electrode conductor includes the polythiophene conductive polymer described above in this application.

[0209] The positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is arranged on either one or both of the two opposite surfaces of the positive electrode current collector.

[0210] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. Alternatively, the aluminum foil may be 1060, 1070, 1100, or 1235, and the purity may be greater than 99%. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0211] In some embodiments, the thickness of the positive electrode current collector may be 10-20 μm.

[0212] In some embodiments, the positive electrode binder includes an oily binder. For example, the positive electrode binder may include one or more of polyvinylidene fluoride, polyimide, and polyurethane. The weight-average molecular weight of the polyvinylidene fluoride may be 50,000 to 2,000,000, thereby improving the bonding strength of the positive electrode sheet and the processing performance of the positive electrode sheet.

[0213] In some embodiments, the positive electrode binder includes an oily binder, and 0.35≤n1 / (n1+n2+n3+n4)≤0.65. For example, n1 / (n1+n2+n3+n4) can be 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, or a range consisting of any of the above values.

[0214] Optionally, 0.40≤n1 / (n1+n2+n3+n4)≤0.60.

[0215] When n1 / (n1+n2+n3+n4) is within the above range, the uniformity of the positive electrode film layer can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0216] In some embodiments, the positive electrode binder includes an oily binder, 0≤n2 / (n1+n2+n3+n4)≤0.25, for example, n2 / (n1+n2+n3+n4) can be 0, 0.05, 0.10, 0.15, 0.20, 0.25, or a range consisting of any of the above values.

[0217] In some embodiments, the positive electrode binder includes an oily binder, 0≤n2 / (n1+n2+n3+n4)≤0.10, optionally, n2 / (n1+n2+n3+n4)=0.

[0218] This can improve the uniformity of the positive electrode film layer and also improve the dynamic performance of the positive electrode sheet and battery.

[0219] In some embodiments, the positive electrode binder includes an oily binder, 0.35≤(n3+n4) / (n1+n2+n3+n4)≤0.65, for example, (n3+n4) / (n1+n2+n3+n4) can be 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, or a range consisting of any of the above values.

[0220] Optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60.

[0221] When (n3+n4) / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the adhesion and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0222] In some embodiments, the positive electrode binder includes an oily binder, 0≤n4 / (n3+n4)≤0.20, for example, n4 / (n3+n4) can be 0, 0.05, 0.10, 0.12, 0.15, 0.20, or a range consisting of any of the above values.

[0223] Optionally, 0<n4 / (n3+n4)≤0.15, 0<n4 / (n3+n4)≤0.12.

[0224] When n4 / (n3+n4) is within the above range, the processing performance of the positive electrode sheet and the battery can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0225] In some embodiments, the positive electrode binder includes an oily binder, and 0.35≤n1 / (n1+n2+n3+n4)≤0.65, 0≤n2 / (n1+n2+n3+n4)≤0.25, 0.35≤(n3+n4) / (n1+n2+n3+n4)≤0.65, and 0<n4 / (n3+n4)≤0.15.

[0226] In some embodiments, the positive electrode binder includes an oily binder, and 0.40≤n1 / (n1+n2+n3+n4)≤0.60, 0≤n2 / (n1+n2+n3+n4)≤0.10, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60, and 0<n4 / (n3+n4)≤0.15.

[0227] In some embodiments, the positive electrode binder includes an oily binder, and 0.40≤n1 / (n1+n2+n3+n4)≤0.60, n2 / (n1+n2+n3+n4)=0, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60, and 0<n4 / (n3+n4)≤0.15.

[0228] In some embodiments, the positive electrode binder includes an aqueous binder. For example, the positive electrode binder may include one or more of carboxymethyl cellulose and its derivatives, sodium alginate, polyacrylic acid and its derivatives, agarose, gelatin, carrageenan, xanthan gum, guar gum, polyvinyl alcohol, and polyacrylamide. When the positive electrode binder is within the above range, it is more environmentally friendly and can also improve the electrolyte affinity of the positive electrode film layer.

[0229] In some embodiments, the positive electrode binder includes an aqueous binder, and 0.05≤n1 / (n1+n2+n3+n4)≤0.25. For example, n1 / (n1+n2+n3+n4) can be 0.05, 0.08, 0.11, 0.15, 0.20, 0.22, 0.25, or any range thereof.

[0230] Optionally, 0.08≤n1 / (n1+n2+n3+n4)≤0.22, 0.11≤n1 / (n1+n2+n3+n4)≤0.22.

[0231] When n1 / (n1+n2+n3+n4) is within the above range, the uniformity of the positive electrode film layer can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0232] In some embodiments, the positive electrode binder includes an aqueous binder, 0.15≤n2 / (n1+n2+n3+n4)≤0.45, for example, n2 / (n1+n2+n3+n4) can be 0.15, 0.20, 0.25, 0.30, 0.36, 0.40, 0.45, or a range consisting of any of the above values.

[0233] Optionally, 0.25≤n2 / (n1+n2+n3+n4)≤0.40, 0.25≤n2 / (n1+n2+n3+n4)≤0.36.

[0234] When n2 / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the bonding force and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can be improved.

[0235] In some embodiments, the positive electrode binder includes an aqueous binder, 0.30≤(n3+n4) / (n1+n2+n3+n4)≤0.80, for example, (n3+n4) / (n1+n2+n3+n4) can be 0.30, 0.35, 0.40, 0.42, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, or a range consisting of any of the above values.

[0236] Optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60, 0.42≤(n3+n4) / (n1+n2+n3+n4)≤0.60.

[0237] When (n3+n4) / (n1+n2+n3+n4) is within the above range, the heating efficiency of the positive electrode sheet can be improved, the adhesion and cohesion of the positive electrode sheet can be enhanced, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0238] In some embodiments, the positive electrode binder includes an aqueous binder, 0≤n4 / (n3+n4)≤0.20, for example, n4 / (n3+n4) can be 0, 0.03, 0.04, 0.05, 0.08, 0.10, 0.12, 0.15, 0.20, or a range consisting of any of the above values.

[0239] Optionally, 0.04≤n4 / (n3+n4)≤0.15.

[0240] When n4 / (n3+n4) is within the above range, the processing performance of the positive electrode sheet and the battery can be improved, and the dynamic performance of the positive electrode sheet and the battery can also be improved.

[0241] In some embodiments, the positive electrode binder includes an aqueous binder, and 0.05≤n1 / (n1+n2+n3+n4)≤0.25, 0.15≤n2 / (n1+n2+n3+n4)≤0.45, 0.30≤(n3+n4) / (n1+n2+n3+n4)≤0.80, and 0.04≤n4 / (n3+n4)≤0.15.

[0242] In some embodiments, the positive electrode binder includes an aqueous binder, and 0.08≤n1 / (n1+n2+n3+n4)≤0.22, 0.25≤n2 / (n1+n2+n3+n4)≤0.40, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60, and 0.04≤n4 / (n3+n4)≤0.15.

[0243] In some embodiments, the positive electrode binder includes an aqueous binder, and 0.11≤n1 / (n1+n2+n3+n4)≤0.22, 0.25≤n2 / (n1+n2+n3+n4)≤0.36, 0.42≤(n3+n4) / (n1+n2+n3+n4)≤0.60, and 0.04≤n4 / (n3+n4)≤0.15.

[0244] In some embodiments, the positive electrode conductive agent may further include a second conductive agent. As an example, the second conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0245] In some embodiments, the content of the polythiophene conductive polymer in the positive electrode film layer may be 0.2-4%, optionally 0.5-3%, based on the total weight of the positive electrode film layer.

[0246] In some embodiments, the content of the positive electrode conductive agent (including the polythiophene conductive polymer and the second conductive agent) in the positive electrode film layer may be 0.5-4%, based on the total weight of the positive electrode film layer.

[0247] In some embodiments, the content of the positive electrode active material in the positive electrode film layer may be 92-98%, based on the total weight of the positive electrode film layer.

[0248] In some embodiments, the content of the positive electrode binder in the positive electrode film layer may be 1-10%, based on the total weight of the positive electrode film layer.

[0249] The positive electrode active material can be any material known in the art, and the present invention is not limited thereto. In some embodiments, the positive electrode active material includes a material capable of reversibly extracting and inserting lithium ions.

[0250] In some embodiments, the positive electrode active material may include one or more of a lithium transition metal oxide, a lithium-containing phosphate, and their respective modified compounds. Examples of lithium transition metal oxides may include one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of lithium-containing phosphates may include one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon, and their respective modified compounds. The present application is not limited to these materials, and other conventionally known materials that can be used as battery positive electrode active materials may also be used.

[0251] In some embodiments, the positive electrode active material may include a lithium-containing phosphate, optionally including one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and modified compounds thereof. These positive electrode active materials may be used alone or in combination of two or more.

[0252] The modified compounds of the above-mentioned positive electrode active materials may be used to perform doping modification and / or surface coating modification on the positive electrode active materials.

[0253] In some embodiments, the positive electrode active material may include lithium-containing phosphate, and the volume distribution particle size Dv50 of the positive electrode active material may be 1-10 μm.

[0254] In some embodiments, the positive electrode active material may include lithium-containing phosphate, and the surface density of the positive electrode sheet may be 0.2-0.8 g / 1540.25 mm 2 .

[0255] In some embodiments, the positive electrode active material may include lithium-containing phosphate, and the compaction density of the positive electrode sheet may be 2.2-2.5 g / cm 3 This allows the battery to have a high energy density.

[0256] [Preparation method of positive electrode sheet]

[0257] The embodiment of the present application also provides a method for preparing a positive electrode plate.

[0258] The method comprises the following steps: applying the positive electrode slurry described above to at least one surface of a positive electrode current collector, drying, and rolling to obtain an initial positive electrode sheet; and irradiating the initial positive electrode sheet with a laser to obtain a positive electrode sheet. The laser wavelength may be 445-505 nm.

[0259] The positive electrode active material in the positive electrode plate has a low absorption rate for blue light (wavelength of 445-505nm), while the polythiophene conductive polymer provided in the embodiment of the present application has a high blue light absorption capacity. Therefore, by using the polythiophene conductive polymer provided in the embodiment of the present application in the positive electrode plate and irradiating the positive electrode plate with blue light, photothermal conversion can be carried out quickly, heating efficiency can be improved, and the adverse effects of blue light irradiation on the positive electrode active material can be reduced.

[0260] Blue light irradiation can rapidly heat the polythiophene conductive polymer, thereby releasing some stress and facilitating the formation of a positive electrode film with a higher porosity, thereby reducing the amount of residual solvent and improving the electrolyte wettability of the positive electrode sheet. Blue light irradiation can also remove substances such as dispersants and surfactants introduced during the processing of the positive electrode sheet. The heating efficiency is high, and the heating temperature is usually higher than the softening point of the positive electrode binder. This allows the positive electrode binder to be evenly distributed throughout the thickness of the positive electrode sheet, thereby helping to improve the cohesion and adhesion of the positive electrode sheet, reduce the positive electrode resistance, and thus improve the battery's rate performance.

[0261] In some embodiments, the laser may be emitted continuously.

[0262] In some embodiments, the number of lasers may be 1-10, and the total power may be 100-2500W.

[0263] In some embodiments, the time for the initial positive electrode piece to pass through the laser spot can be 0.05-0.5s. The time for the initial positive electrode piece to pass through the laser spot refers to the time from the initial positive electrode piece contacting the laser spot to the laser spot leaving the laser spot and stopping irradiation.

[0264] In some embodiments, the vertical distance between the laser and the initial positive electrode plate can be 5-15 cm.

[0265] [Negative electrode]

[0266] The battery cell includes a negative electrode plate. The structure and composition of the negative electrode plate can be selected according to the type of battery cell, and the embodiments of the present application are not limited thereto.

[0267] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0268] The negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is arranged on either one or both of the two opposite surfaces of the negative electrode current collector.

[0269] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As examples of metal foils, copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0270] The negative electrode active material may be a material known in the art. In some embodiments, as an example, the negative electrode active material may include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloy materials. Tin-based materials may include one or more of elemental tin, tin oxide, and tin alloy materials. The present application is not limited to these materials, and other conventionally known materials that can be used as negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0271] In some embodiments, the negative electrode film layer may further optionally include a negative electrode conductive agent. The present application does not particularly limit the type of the negative electrode conductive agent. For example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0272] In some embodiments, the negative electrode film layer may further optionally include a negative electrode binder. The present application does not particularly limit the type of the negative electrode binder. As examples, the negative electrode binder may include one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0273] In some embodiments, the negative electrode film layer may further optionally include other additives, such as thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, and the like.

[0274] The negative electrode film layer is typically formed by coating the negative electrode slurry onto the negative electrode current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing the negative electrode active material, an optional negative electrode conductive agent, an optional negative electrode binder, and other optional additives in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0275] The negative electrode plate does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode plate may further include a conductive primer layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector; in some embodiments, the negative electrode plate may further include a protective layer covering the surface of the negative electrode film layer.

[0276] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a first metal layer disposed on at least one surface of the negative electrode current collector. The metal element in the first metal layer may include lithium.

[0277] In some embodiments, the metal material in the first metal layer may include one or more of lithium element and lithium alloy.

[0278] Lithium alloys can be alloys of metallic lithium with other metallic elements or non-metallic elements. For example, the other metallic elements in a lithium alloy may include one or more of tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum. The non-metallic elements in a lithium alloy may include one or more of boron, carbon, and silicon.

[0279] In some embodiments, the negative electrode sheet may include a negative electrode current collector but not the first metal layer, so as to be assembled into a negative electrode metal-free battery cell.

[0280] In some embodiments, the negative electrode plate may also be made of a sheet (or foil) of lithium or a lithium alloy.

[0281] [Electrolytes]

[0282] The battery cells provided in the embodiments of the present application include an electrolyte. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The present application does not specifically limit the type of electrolyte, and the electrolyte may be selected based on needs. For example, the electrolyte may include one or more of a solid electrolyte, a gel electrolyte, and a liquid electrolyte (i.e., an electrolyte solution).

[0283] In some embodiments, the electrolyte is an electrolyte solution including an electrolyte salt and a solvent.

[0284] The type of electrolyte salt is not particularly limited and can be selected according to actual needs. In some embodiments, as an example, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalatophosphate) (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).

[0285] The type of solvent is not specifically limited and can be selected according to actual needs. In some embodiments, the solvent may include one or more of an ester solvent, a sulfone solvent, and an ether solvent. As an example, the solvent may include but is not limited to ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl 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), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), diethyl sulfone (ESE), tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, dimethoxymethane, diethoxymethane, dipropoxymethane, 1,2-dimethoxyethane, 1,2-dimethoxypropane, 1,2-diethoxyethane, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether or one or more.

[0286] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, or additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.

[0287] [Isolation film]

[0288] The battery cells provided in the embodiments of this application may also include a separator. This separator can be positioned between the positive and negative electrode plates, primarily to prevent internal short circuits. This application does not specifically limit the type of separator; any known porous membrane with good chemical and mechanical stability may be used.

[0289] In some embodiments, the material of the isolation membrane may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and polyimide. The isolation membrane may be a single-layer film or a multi-layer composite film. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different.

[0290] The preparation method of the battery cell provided in the embodiments of the present application is well known. In some embodiments, the positive electrode sheet, the separator, the negative electrode sheet and the electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, the separator, and the negative electrode sheet can be formed into an electrode assembly through a winding process and / or a lamination process, and the electrode assembly is placed in an outer package, dried and injected with the above-mentioned electrolyte, and then subjected to vacuum packaging, standing, formation, shaping and other processes to obtain a battery cell. Multiple battery cells can also be further connected in series, in parallel or in a mixed manner to form a battery module. Multiple battery modules can also be connected in series, in parallel or in a mixed manner to form a battery pack. In some embodiments, multiple battery cells can also directly form a battery pack.

[0291] The present application also provides an electrical device, which includes a battery provided in the present application. The battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device can be, but is not limited to, a mobile device (such as a mobile phone, a tablet computer, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0292] The electrical device can select a specific type of battery according to its usage requirements, for example, a battery cell, a battery module or a battery pack.

[0293] Figure 6 is a schematic diagram of an exemplary electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of this device, a battery pack or battery module may be used.

[0294] As another example, an electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such an electric device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0295] Example

[0296] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further processing, and all instruments used in the examples are commercially available.

[0297] Example 1-1

[0298] (1) Preparation of polythiophene conductive polymers

[0299] In a nitrogen environment, 1 mol of methoxythiophene, 1.5 mol of n-pentanol, and 2 g of anhydrous sodium bisulfate were added to a reactor in sequence, heated and stirred at 110° C. for 3 h, and 3-pentyloxythiophene was obtained after reduced pressure distillation.

[0300] 3-Pentyloxythiophene (first monomer compound) and 3-thiophene methanol (third monomer compound) were dry-mixed in a molar ratio of 3:4, and a total of about 10 g was dissolved in 100 mL of chloroform. Then, 500 mL of a 0.2 mol / L anhydrous FeCl3 chloroform solution was added in a nitrogen environment, and the polymerization reaction was carried out at 25°C for about 24 hours; methanol was then added to the reaction system to precipitate the polymerization product, and the obtained precipitate was extracted in ethanol for 48 hours and dried to obtain an intermediate.

[0301] Under nitrogen, approximately 5 g of polyethylene glycol monomethyl ether (MPEG) with a molecular weight of 1000 and approximately 1 g of diphenylmethane diisocyanate were dissolved in 100 mL of N,N-dimethylformamide and stirred at 70°C for approximately 2 hours. Subsequently, 50 mL of the N,N-dimethylformamide solution containing approximately 6 g of the intermediate was added, and stirring continued at 70°C under nitrogen for approximately 6 hours. The reaction product was extracted with ethanol for 24 hours and vacuum-dried to obtain a polythiophene conductive polymer. The polythiophene conductive polymer comprises the first, third, and fourth structural units shown in Table 1, with an n1:n2:(n3+n4) ratio of 3:0:4 and an n4 / (n3+n4) ratio of 0.12. The number average molecular weight of the polythiophene conductive polymer is shown in Table 1. Nuclear magnetic resonance spectroscopy (NMR) can be used to determine the relative content of the different structural units in the polythiophene conductive polymer.

[0302] (2) Preparation of positive electrode sheet

[0303] The positive electrode active material lithium iron phosphate with a volume distribution particle size Dv50 of 7 μm was uniformly dispersed in NMP according to a weight ratio of 96:2:1.5:0.5 to obtain a positive electrode slurry. The positive electrode slurry was coated on both sides of a 13 μm thick 1060 aluminum foil, and then dried to evaporate the solvent. After cold pressing, the surface density of the foil was 0.6 g / 1540.25 mm. 2 , compacted density is 2.5g / cm 3 The initial positive electrode.

[0304] One of the positive electrode film layers of the above-mentioned initial positive electrode sheet was continuously irradiated with 495nm blue light with a total power of 2000W composed of 5 lasers with a residence time of 0.5s, and the vertical distance between the laser and the initial positive electrode sheet was 10cm; then the other positive electrode film layer of the initial positive electrode sheet was treated in the same way, and a positive electrode sheet was obtained after completion.

[0305] (3) Preparation of negative electrode sheet

[0306] The negative electrode active material artificial graphite, the conductive agent conductive carbon black (Super P), the thickener carboxymethyl cellulose, and the binder styrene-butadiene rubber (SBR) were fully stirred and mixed in an appropriate amount of solvent deionized water at a weight ratio of 96:1:1:2 to form a uniform negative electrode slurry; the negative electrode slurry was coated on both sides of a 6μm thick copper foil, and after drying and cold pressing, a negative electrode sheet was obtained.

[0307] (4) Preparation of electrolyte

[0308] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent, and then fully dried LiPF6 is dissolved in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0309] (5) Preparation of isolation membrane

[0310] A porous polyethylene film was used as the separator.

[0311] (6) Preparation of batteries

[0312] The positive electrode sheet, separator, and negative electrode sheet are stacked and wound in sequence to obtain an electrode assembly; the electrode assembly is placed in an outer package, dried, and then injected with electrolyte, and a battery is obtained after vacuum packaging, standing, and formation processes.

[0313] Example 1-2

[0314] The preparation method of the battery is similar to that of Example 1-1, except that the preparation processes of the polythiophene conductive polymer and the positive electrode are different.

[0315] (1) Preparation of polythiophene conductive polymers

[0316] In a nitrogen environment, 1 mol of methoxythiophene, 1.5 mol of n-butanol, 2 g of anhydrous sodium bisulfate, and 100 mL of toluene were added to a reactor in sequence, heated and stirred at 80°C for 4 h, and 3-butoxythiophene was obtained after reduced pressure distillation.

[0317] 3-Butoxythiophene (first monomer compound) and 3-thiophene methanol (third monomer compound) were dry-mixed in a molar ratio of 3:4, and a total of about 10 g was dissolved in 100 mL of chloroform. Then, 500 mL of a 0.2 mol / L anhydrous FeCl3 chloroform solution was added in a nitrogen environment, and the polymerization reaction was carried out at 25°C for about 48 hours; methanol was then added to the reaction system to precipitate the polymerization product, and the obtained precipitate was extracted in ethanol for 36 hours and dried to obtain an intermediate.

[0318] In a nitrogen atmosphere, approximately 4 g of polyethylene glycol monomethyl ether (MPEG) with a molecular weight of 400 and approximately 1 g of diphenylmethane diisocyanate were dissolved in 100 mL of N,N-dimethylformamide and stirred at 70°C for 3 hours. Subsequently, 50 mL of an N,N-dimethylformamide solution containing approximately 7 g of the intermediate was added, and stirring continued at 70°C under nitrogen for approximately 5 hours. The reaction product was extracted with ethanol for 48 hours and vacuum-dried to obtain a polythiophene conductive polymer. The polythiophene conductive polymer comprises the first, third, and fourth structural units shown in Table 1, with an n1:n2:(n3+n4) ratio of 3:0:4 and an n4 / (n3+n4) ratio of 0.12. The number average molecular weight of the polythiophene conductive polymer is shown in Table 1.

[0319] (2) Preparation of positive electrode sheet

[0320] The positive electrode active material lithium iron phosphate with a volume distribution particle size Dv50 of 5 μm, polyvinylidene fluoride, polythiophene conductive polymer, and conductive carbon black (Super P) were added to NMP in a weight ratio of 97:1:1.3:0.7 and uniformly dispersed to obtain a positive electrode slurry; the positive electrode slurry was coated on both sides of a 15 μm thick 1070 aluminum foil, and then dried to evaporate the solvent, and then cold pressed to obtain a surface density of 0.65 g / 1540.25 mm 2 , compacted density is 2.45g / cm 3 The initial positive electrode.

[0321] One of the positive electrode film layers of the above-mentioned initial positive electrode sheet was continuously irradiated with 455nm blue light with a total power of 2500w composed of 4 lasers with a residence time of 0.3s, and the vertical distance between the laser and the initial positive electrode sheet was 5cm; then the other positive electrode film layer of the initial positive electrode sheet was treated in the same way, and a positive electrode sheet was obtained after completion.

[0322] Examples 1-3

[0323] The preparation method of the battery is similar to that of Example 1-1, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0324] In the process of preparing the polythiophene conductive polymer, 3-thiopheneethanol is used instead of 3-thiophenemethanol. The polythiophene conductive polymer includes the first structural unit, the third structural unit, and the fourth structural unit shown in Table 1, and the content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 1.

[0325] Examples 1-4

[0326] The preparation method of the battery is similar to that of Example 1-1, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0327] In the process of preparing polythiophene conductive polymer, hexamethylene diisocyanate is used instead of diphenylmethane diisocyanate.

[0328] The polythiophene conductive polymer includes the first structural unit, the third structural unit and the fourth structural unit shown in Table 1, and the content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 1.

[0329] Examples 1-5

[0330] The preparation method of the battery is similar to that of Example 1-1, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0331] In the process of preparing polythiophene conductive polymer, dicyclohexylmethane diisocyanate is used instead of diphenylmethane diisocyanate.

[0332] The polythiophene conductive polymer includes the first structural unit, the third structural unit and the fourth structural unit shown in Table 1, and the content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are respectively shown in Table 1.

[0333] Examples 1-6

[0334] The preparation method of the battery is similar to that of Example 1-1, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0335] When preparing the polythiophene conductive polymer, polyethylene glycol monomethyl ether (MPEG) and diphenylmethane diisocyanate were not added. The prepared polythiophene conductive polymer includes the first structural unit and the third structural unit shown in Table 1, and the content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 1.

[0336] Examples 1-7

[0337] The preparation method of the battery is similar to that of Example 1-1, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0338] (1) Preparation of polythiophene conductive polymers

[0339] In a nitrogen environment, 1 mol of methoxythiophene, 1.5 mol of methyl lactate, 2 g of anhydrous sodium bisulfate, and 100 mL of toluene were added to the reaction system in sequence, heated and stirred at 85°C for 3.5 h, and methyl 2-(thiophene-3-oxy)propionate was obtained after reduced pressure distillation.

[0340] 3-pentyloxythiophene (first monomer compound), methyl 2-(thiophene-3-oxy)propionate (precursor compound of the second monomer compound), and 3-thiophene methanol (third monomer compound) were dry-mixed in a molar ratio of 5:0.5:4.5, and a total of about 10 g was dissolved in 100 mL of chloroform. Then, 500 mL of a 0.2 mol / L anhydrous FeCl3 chloroform solution was added in a nitrogen environment, and the polymerization reaction was carried out at 25°C for about 72 hours; methanol was then added to the reaction system to precipitate the polymerization product, and the obtained precipitate was extracted in ethanol for 36 hours and dried to obtain an intermediate.

[0341] 5 g of the intermediate was dispersed in water, NaOH was added to adjust the pH to 8.5, and stirring was continued for about 6 h; then dried to obtain a polythiophene conductive polymer.

[0342] The polythiophene conductive polymer includes the first structural unit, the second structural unit and the third structural unit shown in Table 1, and the content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 1.

[0343] Examples 1-8

[0344] The preparation method of the battery is similar to that of Example 1-1, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0345] (1) Preparation of polythiophene conductive polymers

[0346] 3-pentyloxythiophene (first monomer compound), methyl 2-(thiophene-3-oxy)propionate (precursor compound of the second monomer compound), and 3-thiophene methanol (third monomer compound) were dry-mixed in a molar ratio of 5:1:4.5, and a total of about 10 g was dissolved in 100 mL of chloroform. Then, 500 mL of a 0.2 mol / L anhydrous FeCl3 chloroform solution was added in a nitrogen environment, and the polymerization reaction was carried out at 25°C for about 96 hours; methanol was then added to the reaction system to precipitate the polymerization product, and the obtained precipitate was extracted in ethanol for 36 hours and dried to obtain the first intermediate.

[0347] In a nitrogen environment, 5 g of polyethylene glycol monomethyl ether (MPEG) with a molecular weight of 1000 and 1 g of diphenylmethane diisocyanate were dissolved in 100 mL of N,N-dimethylformamide and stirred at 70°C for about 2 h. Subsequently, 50 mL of N,N-dimethylformamide solution containing 6 g of the above intermediate was added, and stirring was continued at 70°C in a nitrogen environment for about 6 h. The reaction product was extracted with ethanol for 24 h and vacuum dried to obtain a second intermediate.

[0348] 5 g of the second intermediate was dispersed in water, NaOH was added to adjust the pH to 8.5, and stirring was continued for 6 h; and then dried to obtain a polythiophene conductive polymer.

[0349] The polythiophene conductive polymer includes the first structural unit, the second structural unit, the third structural unit and the fourth structural unit shown in Table 1, and the content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 1.

[0350] Examples 1-9 to 1-12

[0351] The preparation method of the battery is similar to that of Example 1-1, except that the number average molecular weight of the polythiophene conductive polymer is different, as shown in Table 3 for details.

[0352] Examples 1-13 to 1-17

[0353] The preparation method of the battery is similar to that of Example 1-1, except that the content and number average molecular weight of each structural unit in the polythiophene conductive polymer are different, as shown in Table 3 for details.

[0354] Examples 1-18 to 1-21

[0355] The preparation method of the battery is similar to that of Example 1-1, except that the content and number average molecular weight of each structural unit in the polythiophene conductive polymer are different, as shown in Table 3 for details.

[0356] When preparing the polythiophene conductive polymers of the above embodiments, one or more of the parameters such as the type and concentration of the monomer, the concentration of the oxidant FeCl3, the reaction temperature and the reaction time can be adjusted according to methods known in the art to obtain different number average molecular weights.

[0357] Comparative Example 1-1

[0358] The preparation method of the battery is similar to that of Example 1-1, except that the preparation process of the positive electrode is different.

[0359] The positive electrode active material lithium iron phosphate with a volume distribution particle size Dv50 of 7 μm, polyvinylidene fluoride, and conductive carbon black (Super P) were added to NMP in a weight ratio of 96:2:2 and uniformly dispersed to obtain a positive electrode slurry; the positive electrode slurry was coated on both sides of a 13 μm thick 1060 aluminum foil, and then dried to evaporate the solvent, and then cold pressed to obtain a surface density of 0.6 g / 1540.25 mm 2 , compacted density is 2.5g / cm 3 The positive electrode.

[0360] Comparative Example 1-2

[0361] The preparation method of the battery is similar to that of Example 1-1, except that the preparation process of the positive electrode is different.

[0362] The positive electrode active material lithium iron phosphate with a volume distribution particle size Dv50 of 7 μm, polyvinylidene fluoride, homopolymer polythiophene (the monomer is thiophene, the number average molecular weight is between 15000-20000), and conductive carbon black (Super P) are added into NMP in a weight ratio of 96:2:1.3:0.7 and uniformly dispersed to obtain a positive electrode slurry; the positive electrode slurry is coated on both sides of a 13 μm thick 1060 aluminum foil, and then dried to evaporate the solvent, and then cold pressed to obtain a surface density of 0.6 g / 1540.25 mm 2 , compacted density is 2.5g / cm 3 The initial positive electrode.

[0363] One of the positive electrode film layers of the above-mentioned initial positive electrode sheet was continuously irradiated with 495nm blue light with a total power of 2000W composed of 5 lasers with a residence time of 0.5s, and the vertical distance between the laser and the initial positive electrode sheet was 10cm; then the other positive electrode film layer of the initial positive electrode sheet was treated in the same way, and a positive electrode sheet was obtained after completion.

[0364] Test section

[0365] (1) Resistance test of positive electrode

[0366] Cut the cold-pressed positive electrode sheet into 5cm x 5cm pieces and place it between the two electrodes of a resistance tester. Measure the resistance of the positive electrode sheet. A resistance tester such as the Yuanneng Technology BER2500 can be used. The test temperature is 25°C.

[0367] (2) Adhesion test of positive electrode

[0368] The positive electrode sheet was washed with N-methylpyrrolidone to remove the positive electrode film layer on one side and dried, and then the single-sided coated positive electrode sheet was cut into 20mm×100mm test specimens for use; the test specimen was adhered to the side to be tested with double-sided tape and compacted with a pressure roller to make the double-sided tape completely fit the test specimen; the other side of the double-sided tape was adhered to the stainless steel surface, and one end of the test specimen was bent in the opposite direction with a bending angle of 180°; a high-speed rail tensile testing machine was used for testing, one end of the stainless steel was fixed to the lower fixture of the tensile testing machine, and the bent end of the test specimen was fixed to the upper fixture, the angle of the test specimen was adjusted to ensure that the upper and lower ends were in a vertical position, and then the test specimen was stretched at a speed of 50mm / min until it was completely peeled off from the substrate, and the displacement and force during the process were recorded, and the force when the forces were balanced was used as the bonding force of the positive electrode sheet.

[0369] (3) Porosity test of positive electrode sheet

[0370] Cut the positive electrode sheet into 20 circular pieces with a diameter of 14 mm. Record the weight and thickness of the positive electrode sheets and calculate the volume density. Place the circular pieces into the sample cup of a true density porosity tester. Use helium displacement and combine Archimedes' principle and Bohr's law to determine the true volume of the positive electrode sheet, and then calculate the true density of the positive electrode sheet. Porosity of the positive electrode sheet = (1 - volume density / true density).

[0371] (4) Gram capacity test of positive electrode active material

[0372] The positive electrode sheet was washed with N-methylpyrrolidone to remove the positive electrode film layer on one side and dried, and then punched into a single-sided circular sheet with a diameter of 14 mm and weighed; at the same time, the weight of the corresponding positive electrode current collector under the 14 mm diameter circular sheet was weighed to obtain the weight of the positive electrode film layer, and then the mass of the positive electrode active material was calculated.

[0373] The 2032 button battery was equipped with a negative electrode shell, nickel foam, a 16 mm diameter lithium sheet, an 18 mm diameter Celgard2325 separator, and 0.1 g 1 mol·L -1 A 2032 button cell is assembled with LiPF6's EC:DMC:EMC (mass ratio 1:1:1) electrolyte, a 14mm diameter single-sided circular electrode, and a 2032 button cell positive electrode shell.

[0374] The assembled button cell was left to rest for 12 hours before testing. The battery capacity, denoted as C, is the mass of the positive electrode active material multiplied by the theoretical gram capacity. The button cell was charged at a current of 0.1C to the upper cutoff voltage and then discharged at a current of 0.1C to the upper cutoff voltage. The gram capacity of the positive electrode active material was obtained by dividing the discharge capacity of the button cell by the mass of the positive electrode active material.

[0375] (5) Battery DC internal resistance (DCR) test

[0376] At 25°C, the batteries prepared in each example and comparative example were charged at a constant current of 0.33C to a full charge state (100% SOC), then discharged at a constant current of 0.33C to 0.5Cn (Cn represents the battery capacity) to adjust the battery to 50% SOC. The battery was allowed to rest for 30 minutes, with the voltage at the end of the rest period recorded as V1. The battery was then discharged at a current of 3C (recorded as I) for 30 seconds, with the discharge cut-off voltage recorded as V2. The DC internal resistance of the battery, DCR, = (V1-V2) / I, where V1 represents the rest end voltage, V2 represents the discharge cut-off voltage, and I represents the discharge current.

[0377] (6) Battery rate performance test

[0378] At 25°C, the batteries prepared in each example and comparative example were charged at a constant current of 0.33C to 3.65V, then continued to charge at a constant voltage to a current of 0.05C. After standing for 5 minutes, the batteries were discharged at a constant current of 0.33C to 2.5V to obtain the discharge capacity of the battery at a rate of 0.33C. After the batteries were stood for 30 minutes, they were charged at a constant current of 0.33C to 3.65V, then charged at a constant voltage to a current of 0.05C. After standing for 5 minutes, the batteries were discharged at a constant current of 3C to 2.5V to obtain the discharge capacity of the battery at a rate of 3C. The ratio of the discharge capacity of the battery at a rate of 3C to the discharge capacity of the battery at a rate of 0.33C represents the rate performance of the battery. The larger the ratio, the better the rate performance of the battery.

[0379] The test results of Examples 1-1 to 1-21 and Comparative Examples 1-1 to 1-2 are shown in Tables 2 and 3.

[0380] As shown in Tables 1 to 3, the positive electrode sheets provided in the examples of the present application, after exposure to blue light, exhibit low resistance, high adhesion, high porosity, and high specific capacity. Application in batteries can reduce internal resistance and improve rate performance. Figure 7 shows the discharge curves of the batteries of Example 1-1 and Comparative Example 1-1 at different rates. As shown in Figure 7, the battery prepared in Example 1-1 has a higher discharge capacity retention rate at a 3C rate.

[0381] The positive electrode conductive agent in the positive electrode sheets of Examples 1-1 to 1-21 includes a functionalized polythiophene conductive polymer, which has a higher absorption rate for blue light wavelengths and a higher heating efficiency when irradiated with blue light. This can better improve the distribution of the positive electrode binder in the positive electrode sheet, thereby enhancing the bonding strength and cohesion of the positive electrode sheet and reducing the positive electrode resistance. Stress can also be released during blue light irradiation, which is conducive to the formation of a positive electrode film layer with higher porosity, thereby improving the electrolyte wettability of the positive electrode sheet.

[0382] It can also be seen from the test results of Comparative Examples 1-2 that when the positive electrode conductive agent includes homopolymerized polythiophene, due to the lack of red-shifted functional groups, the wavelength corresponding to the maximum absorption peak of the positive electrode plate is not within the blue light wavelength range, which results in a low absorption rate of blue light irradiation, and thus the improvement effect on the positive electrode plate and the battery is not obvious.

[0383] Example 2-1

[0384] The preparation method of the battery is similar to that of Example 1-1, except that the preparation processes of the polythiophene conductive polymer and the positive electrode are different.

[0385] (1) Preparation of polythiophene conductive polymers

[0386] In a nitrogen environment, 1 mol of methoxythiophene, 1.5 mol of ethyl glycolate, 2 g of anhydrous sodium bisulfate, and 100 mL of toluene were added to the reaction system in sequence, heated and stirred at 90°C for 3 h, and ethyl thiophene-3-oxyacetate was obtained after reduced pressure distillation.

[0387] 3-pentyloxythiophene (first monomer compound), thiophene-3-oxyethyl acetate (precursor compound of the second monomer compound), and 3-thiophene methanol (third monomer compound) were dry-mixed in a molar ratio of 15:20:45, and a total of about 10 g was dissolved in 100 mL of chloroform. Then, 500 mL of a 0.2 mol / L anhydrous FeCl3 chloroform solution was added in a nitrogen environment, and the polymerization reaction was carried out at 25°C for about 48 hours; methanol was then added to the reaction system to precipitate the polymerization product, and the obtained precipitate was extracted in ethanol for 36 hours and dried to obtain the first intermediate.

[0388] In a nitrogen environment, about 8 g of polyethylene glycol monomethyl ether with a molecular weight of 6000 and about 2 g of diphenylmethane diisocyanate were dissolved in 100 mL of N,N-dimethylformamide and stirred at 70°C for 3 h. Subsequently, 50 mL of N,N-dimethylformamide solution containing about 7 g of the above-mentioned first intermediate was added, and stirring was continued at 70°C in a nitrogen environment for about 5 h. The reaction product was extracted with ethanol for 36 h and vacuum dried to obtain a second intermediate.

[0389] 5 g of the second intermediate was dispersed in water, and NaOH was added to adjust the pH to 8.5. The mixture was stirred for approximately 6 hours, followed by drying to obtain a neutralized polythiophene conductive polymer. The polythiophene conductive polymer comprised the first structural unit, the second structural unit, the third structural unit, and the fourth structural unit shown in Table 4, with an n1:n2:(n3+n4) ratio of 15:20:45, and an n4 / (n3+n4) ratio of 0.05. The number average molecular weight of the polythiophene conductive polymer is shown in Table 4.

[0390] (2) Preparation of positive electrode sheet

[0391] The positive electrode active material lithium iron phosphate with a volume distribution particle size Dv50 of 7 μm was uniformly dispersed with sodium carboxymethyl cellulose, polythiophene conductive polymer, and conductive carbon black (Super P) in a weight ratio of 96:2:1.3:0.7 in deionized water to obtain a positive electrode slurry. The positive electrode slurry was coated on both sides of a 20 μm thick 1070 aluminum foil, and then dried to evaporate the solvent. After cold pressing, the surface density of the foil was 0.7 g / 1540.25 mm 2 , compacted density is 2.4g / cm 3 The initial positive electrode.

[0392] One of the positive electrode film layers of the above-mentioned initial positive electrode sheet was continuously irradiated with 485nm blue light with a total power of 2500w composed of 10 lasers with a residence time of 0.25s, and the vertical distance between the laser and the initial positive electrode sheet was 15cm; then the other positive electrode film layer of the initial positive electrode sheet was treated in the same way, and a positive electrode sheet was obtained after completion.

[0393] Example 2-2

[0394] The preparation method of the battery is similar to that of Example 2-1, except that the preparation processes of the polythiophene conductive polymer and the positive electrode are different.

[0395] 3-pentyloxythiophene (first monomer compound), methyl 2-(thiophene-3-oxy)propionate (precursor compound of the second monomer compound), and 3-thiophene methanol (third monomer compound) were dry-mixed in a molar ratio of 15:20:45, and a total of about 10 g was dissolved in 100 mL of chloroform. Then, 500 mL of a 0.2 mol / L anhydrous FeCl3 chloroform solution was added in a nitrogen environment, and the polymerization reaction was carried out at 25°C for about 24 hours; methanol was then added to the reaction system to precipitate the polymerization product, and the obtained precipitate was extracted in ethanol for 48 hours and dried to obtain the first intermediate.

[0396] In a nitrogen environment, about 6.5 g of polyethylene glycol monomethyl ether with a molecular weight of 500 and about 1.5 g of diphenylmethane diisocyanate were dissolved in 100 mL of N,N-dimethylformamide and stirred at 70°C for 3 h. Subsequently, 50 mL of N,N-dimethylformamide solution containing about 7 g of the above-mentioned first intermediate was added, and stirring was continued at 70°C in a nitrogen environment for about 6 h. The reaction product was extracted with ethanol for 48 h and vacuum dried to obtain a second intermediate.

[0397] 5.5 g of the second intermediate was dispersed in water, and LiOH was added to adjust the pH to 7.5. The mixture was stirred for approximately 12 hours and then dried to obtain a polythiophene conductive polymer. The polythiophene conductive polymer comprised the first structural unit, the second structural unit, the third structural unit, and the fourth structural unit shown in Table 4, with an n1:n2:(n3+n4) ratio of 15:20:45 and an n4 / (n3+n4) ratio of 0.05. The number average molecular weight of the polythiophene conductive polymer is shown in Table 4.

[0398] (2) Preparation of positive electrode sheet

[0399] The positive electrode active material lithium iron phosphate with a volume distribution particle size Dv50 of 5 μm, sodium alginate, polythiophene conductive polymer, and conductive carbon black (Super P) were added to deionized water in a weight ratio of 96.5:1.5:1.4:0.6 and uniformly dispersed to obtain a positive electrode slurry; the positive electrode slurry was coated on both sides of a 20 μm thick 1070 aluminum foil, and then dried to evaporate the solvent, and then cold pressed to obtain a surface density of 0.7 g / 1540.25 mm 2 , compacted density is 2.4g / cm 3 The initial positive electrode.

[0400] One of the positive electrode film layers of the above-mentioned initial positive electrode sheet was continuously irradiated with 505nm blue light with a total power of 1500w composed of 8 lasers with a residence time of 0.2s, and the vertical distance between the laser and the initial positive electrode sheet was 7.5cm; then the other positive electrode film layer of the initial positive electrode sheet was treated in the same way, and a positive electrode sheet was obtained after completion.

[0401] Example 2-3

[0402] The preparation method of the battery is similar to that of Example 2-2, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0403] During the preparation of the polythiophene conductive polymer, methyl 2-(thiophene-3-oxy) lactate was used instead of methyl 2-(thiophene-3-oxy) propionate. The polythiophene conductive polymer included the first structural unit, the second structural unit, the third structural unit, and the fourth structural unit shown in Table 4. The content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 4.

[0404] Examples 2-4

[0405] The preparation method of the battery is similar to that of Example 2-2, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0406] During the preparation of the polythiophene conductive polymer, 3-thiopheneethanol was used instead of 3-thiophenemethanol. The polythiophene conductive polymer included the first structural unit, the second structural unit, the third structural unit, and the fourth structural unit shown in Table 4. The content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 4.

[0407] Examples 2-5

[0408] The preparation method of the battery is similar to that of Example 2-2, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0409] In the process of preparing the polythiophene conductive polymer, hexamethylene diisocyanate was used instead of diphenylmethane diisocyanate. The polythiophene conductive polymer includes the first structural unit, the second structural unit, the third structural unit, and the fourth structural unit shown in Table 4. The content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 4.

[0410] Examples 2-6

[0411] The preparation method of the battery is similar to that of Example 2-2, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0412] During the preparation of the polythiophene conductive polymer, dicyclohexylmethane diisocyanate was used instead of diphenylmethane diisocyanate. The polythiophene conductive polymer included the first structural unit, the second structural unit, the third structural unit, and the fourth structural unit shown in Table 4. The content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 4.

[0413] Examples 2-7

[0414] The preparation method of the battery is similar to that of Example 2-2, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0415] During the preparation of the polythiophene conductive polymer, no second monomer compound, polyethylene glycol monomethyl ether (MPEG), and diphenylmethane diisocyanate were added. The prepared polythiophene conductive polymer included the first structural unit and the third structural unit shown in Table 4. The content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 4.

[0416] Examples 2-8

[0417] The preparation method of the battery is similar to that of Example 2-2, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0418] When preparing the polythiophene conductive polymer, no second monomer compound was added. The prepared polythiophene conductive polymer includes the first structural unit, the third structural unit, and the fourth structural unit shown in Table 4, and the content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 4.

[0419] Examples 2-9

[0420] The preparation method of the battery is similar to that of Example 2-2, except that the structure and preparation process of the polythiophene conductive polymer are different.

[0421] When preparing the polythiophene conductive polymer, no second monomer compound was added. The prepared polythiophene conductive polymer includes the first structural unit, the third structural unit, and the fourth structural unit shown in Table 4, and the content of each structural unit and the number average molecular weight of the polythiophene conductive polymer are also shown in Table 4.

[0422] Examples 2-10 to 1-14

[0423] The preparation method of the battery is similar to that of Example 2-2, except that the number average molecular weight of the polythiophene conductive polymer is different, as shown in Table 6 for details.

[0424] Examples 2-15 to 1-18

[0425] The preparation method of the battery is similar to that of Example 2-2, except that the content and number average molecular weight of each structural unit in the polythiophene conductive polymer are different, as shown in Table 6 for details.

[0426] Examples 2-19 to 1-22

[0427] The preparation method of the battery is similar to that of Example 2-2, except that the content and number average molecular weight of each structural unit in the polythiophene conductive polymer are different, as shown in Table 6 for details.

[0428] Example 2-23

[0429] The preparation method of the battery is similar to that of Example 2-2, except that the pH of the second intermediate is adjusted to 7.5 with NaOH.

[0430] When preparing the polythiophene conductive polymers of the above embodiments, one or more of the parameters such as the type and concentration of the monomer, the concentration of the oxidant FeCl3, the reaction temperature and the reaction time can be adjusted according to methods known in the art to obtain different number average molecular weights.

[0431] Comparative Example 2-1

[0432] The preparation method of the battery is similar to that of Example 2-2, except that the preparation process of the positive electrode is different.

[0433] The positive electrode active material lithium iron phosphate with a volume distribution particle size Dv50 of 5 μm, sodium alginate, and conductive carbon black (Super P) were uniformly dispersed in deionized water at a weight ratio of 96.5:1.5:2 to obtain a positive electrode slurry. The positive electrode slurry was coated on both sides of a 20 μm thick 1070 aluminum foil, and then dried to evaporate the solvent. After cold pressing, the surface density of the foil was 0.7 g / 1540.25 mm 2 , compacted density is 2.4g / cm 3 The positive electrode.

[0434] Comparative Example 2-2

[0435] The preparation method of the battery is similar to that of Example 2-2, except that the preparation process of the positive electrode is different.

[0436] The positive electrode active material lithium iron phosphate with a volume distribution particle size Dv50 of 5 μm, sodium alginate, homopolymerized polythiophene (the monomer is thiophene, with a number average molecular weight between 15000 and 20000), and conductive carbon black (Super P) were added to deionized water in a weight ratio of 96.5:1.5:1.4:0.6 and uniformly dispersed to obtain a positive electrode slurry; the positive electrode slurry was coated on both sides of a 20 μm thick 1070 aluminum foil, and then dried to evaporate the solvent, and then cold pressed to obtain a surface density of 0.7 g / 1540.25 mm 2 , compacted density is 2.4g / cm 3 The initial positive electrode.

[0437] One of the positive electrode film layers of the above-mentioned initial positive electrode sheet was continuously irradiated with 505nm blue light with a total power of 1500w composed of 8 lasers with a residence time of 0.2s, and the vertical distance between the laser and the initial positive electrode sheet was 7.5cm; then the other positive electrode film layer of the initial positive electrode sheet was treated in the same way, and a positive electrode sheet was obtained after completion.

[0438] The test methods of Examples 2-1 to 2-23 and Comparative Examples 2-1 to 2-2 were the same as those of Examples 1-1 to 1-21. The results are shown in Tables 5 and 6.

[0439] It can be seen from Tables 4 to 6 that the positive electrode sheets provided in the embodiments of the present application have the characteristics of low resistance, high adhesion, high porosity, and high specific capacity after being irradiated with blue light. When applied to batteries, they can reduce the internal resistance of the battery and improve the rate performance of the battery.

[0440] The positive electrode conductive agent in the positive electrode sheets of Examples 2-1 to 2-23 includes a functionalized polythiophene conductive polymer, which has a higher absorption rate for blue light wavelengths and a higher heating efficiency when irradiated with blue light. This can better improve the distribution of the positive electrode binder in the positive electrode sheet, thereby enhancing the bonding strength and cohesion of the positive electrode sheet and reducing the positive electrode resistance. Stress can also be released during blue light irradiation, which is conducive to the formation of a positive electrode film layer with higher porosity, thereby improving the electrolyte wettability of the positive electrode sheet.

[0441] It can also be seen from the test results of Comparative Example 2-2 that when the positive electrode conductive agent includes homopolymerized polythiophene, due to the lack of red-shifted functional groups, the wavelength corresponding to the maximum absorption peak of the positive electrode plate is not within the blue light wavelength range, which results in a low absorption rate of blue light irradiation, and thus the improvement effect on the positive electrode plate and the battery is not obvious.

[0442] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A polythiophene conductive polymer comprising: A first structural unit represented by formula (1); as well as at least one of the second structural unit represented by formula (2), the third structural unit represented by formula (3), and the fourth structural unit represented by formula (4), R 11 Including C1-C8 alkyl or C1-C8 alkyl alkoxy, R 12 including a hydrogen atom or a C1-C3 alkyl group; R 21 Including C1-C5 alkylene, R 22 includes a hydrogen atom or a C1-C3 alkyl group, and M includes a monovalent metal; R 31 Including C1-C5 alkylene, R 32 including a hydrogen atom or a C1-C3 alkyl group; R 41 Including C1-C5 alkylene, R 42 Including the residue of diisocyanate, R 43 Including C2-C6 alkylene, R 44 Including C1-C3 alkyl, R 45 Including hydrogen atom or C1-C3 alkyl, s≥1; n1＞0； n2≥0, n3≥0, n4≥0, and n2+n3+n4>0.

2. The polythiophene conductive polymer according to claim 1, wherein The number average molecular weight of the polythiophene conductive polymer is 3000-45000, and can be optionally 5000-34000.

3. The polythiophene conductive polymer according to claim 1 or 2, wherein: The polythiophene conductive polymer satisfies at least one of the following conditions (1) to (13): (1)R 11 Including C4-C6 alkyl or C4-C6 alkylalkoxy; (2)R 12 Includes hydrogen atoms; (3)R 21 Including C1-C3 alkylene; (4)R 22 Includes hydrogen atoms; (5) M includes Li and / or Na; (6)R 31 Including C1-C3 alkylene; (7)R 32 Includes hydrogen atoms; (8)R 41 Including C1-C3 alkylene; (9)R 42 Including R a Substituted or unsubstituted C1-C6 alkylene, and one of the following groups: # indicates the connection position, R a Each independently includes C1-C3 alkyl, R b Each independently includes a C1-C3 alkyl group, p represents an integer of 0-4, and q represents an integer of 0-6; (10)R 43 Includes the following groups: (11)R 44 Includes methyl; (12)R 45 Includes hydrogen atoms; (13)s is 3-140, and can be optionally 10-90.

4. The polythiophene conductive polymer according to any one of claims 1 to 3, wherein: n2>0, n3=0, n4=0; or, n2=0,n3>0,n4=0;or, n2=0,n3>0,n4>0;or, n2>0, n3>0, n4>0.

5. A positive electrode slurry, comprising a solvent and a non-solvent component, wherein the non-solvent component comprises a positive electrode active material, a positive electrode binder and a positive electrode conductor, wherein: The positive electrode conductive agent comprises the polythiophene conductive polymer according to any one of claims 1 to 4.

6. The positive electrode slurry according to claim 5, wherein: The non-aqueous solvent may include N-methylpyrrolidone, the positive electrode binder may include an oily binder, and 0.35≤n1 / (n1+n2+n3+n4)≤0.65; Optionally, 0.40≤n1 / (n1+n2+n3+n4)≤0.60; and / or, Optionally, the positive electrode binder includes one or more of polyvinylidene fluoride, polyimide, and polyurethane.

7. The positive electrode slurry according to claim 6, wherein: 0≤n2 / (n1+n2+n3+n4)≤0.25, optionally, 0≤n2 / (n1+n2+n3+n4)≤0.10; and / or, 0.35≤(n3+n4) / (n1+n2+n3+n4)≤0.65, Optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60; and / or, 0≤n4 / (n3+n4)≤0.20, optionally, 0<n4 / (n3+n4)≤0.

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8. The positive electrode slurry according to claim 5, wherein: The solvent includes water, the positive electrode binder includes an aqueous binder, and 0.05≤n1 / (n1+n2+n3+n4)≤0.25; Optionally, 0.08≤n1 / (n1+n2+n3+n4)≤0.22; and / or, Optionally, the positive electrode binder includes one or more of carboxymethyl cellulose and its derivatives, sodium alginate, polyacrylic acid and its derivatives, agarose, gelatin, carrageenan, xanthan gum, guar gum, polyvinyl alcohol, and polyacrylamide.

9. The positive electrode slurry according to claim 8, wherein: 0.15≤n2 / (n1+n2+n3+n4)≤0.45, optionally, 0.25≤n2 / (n1+n2+n3+n4)≤0.40; and / or, 0.30≤(n3+n4) / (n1+n2+n3+n4)≤0.80, Optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60; and / or, 0≤n4 / (n3+n4)≤0.20, optionally, 0.04≤n4 / (n3+n4)≤0.

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10. The positive electrode slurry according to any one of claims 5 to 9, wherein: The positive electrode active material includes one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds; and / or, The positive electrode slurry further includes a second conductive agent, wherein the second conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers; and / or, The content of the polythiophene conductive polymer in the non-solvent component is 0.2-4%, optionally 0.5-3%, based on the total weight of the non-solvent component.

11. A positive electrode sheet, comprising a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein: The positive electrode film layer comprises a positive electrode active material, a positive electrode binder and a positive electrode conductor, and the positive electrode conductor comprises the polythiophene conductive polymer according to any one of claims 1 to 4.

12. The positive electrode sheet according to claim 11, wherein: The positive electrode binder includes an oily binder, and 0.35≤n1 / (n1+n2+n3+n4)≤0.65; Optionally, 0.40≤n1 / (n1+n2+n3+n4)≤0.60; and / or, Optionally, the positive electrode binder includes one or more of polyvinylidene fluoride, polyimide, and polyurethane.

13. The positive electrode sheet according to claim 12, wherein: 0≤n2 / (n1+n2+n3+n4)≤0.25, optionally, 0≤n2 / (n1+n2+n3+n4)≤0.10; and / or, 0.35≤(n3+n4) / (n1+n2+n3+n4)≤0.65, Optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60; and / or, 0≤n4 / (n3+n4)≤0.20, optionally, 0<n4 / (n3+n4)≤0.

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14. The positive electrode sheet according to claim 11, wherein: The positive electrode binder includes an aqueous binder, and 0.05≤n1 / (n1+n2+n3+n4)≤0.25; Optionally, 0.08≤n1 / (n1+n2+n3+n4)≤0.22; and / or, Optionally, the positive electrode binder includes one or more of carboxymethyl cellulose and its derivatives, sodium alginate, polyacrylic acid and its derivatives, agarose, gelatin, carrageenan, xanthan gum, guar gum, polyvinyl alcohol, and polyacrylamide.

15. The positive electrode sheet according to claim 14, wherein: 0.15≤n2 / (n1+n2+n3+n4)≤0.45, optionally, 0.25≤n2 / (n1+n2+n3+n4)≤0.40; and / or, 0.30≤(n3+n4) / (n1+n2+n3+n4)≤0.80, Optionally, 0.40≤(n3+n4) / (n1+n2+n3+n4)≤0.60; and / or, 0≤n4 / (n3+n4)≤0.20, optionally, 0.04≤n4 / (n3+n4)≤0.

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16. The positive electrode sheet according to any one of claims 11 to 15, wherein: The positive electrode active material includes one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds; and / or, The positive electrode plate further includes a second conductive agent, wherein the second conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers; and / or, The content of the polythiophene conductive polymer in the positive electrode film layer is 0.2-4%, and optionally 0.5-3%, based on the total weight of the positive electrode film layer.

17. A method for preparing a positive electrode sheet, wherein: The steps include: Applying the positive electrode slurry according to any one of claims 5 to 10 on at least one surface of the positive electrode current collector, drying and rolling to obtain an initial positive electrode sheet; The initial positive electrode sheet is obtained by laser irradiation, and a positive electrode sheet is obtained after completion, wherein the laser wavelength is 445-505nm.

18. The preparation method according to claim 17, wherein: The laser is emitted in a continuous manner; and / or, The number of lasers is 1-10 and the total power is 100-2500W; and / or, The time for the initial positive electrode plate to pass through the laser spot is 0.05-0.5s; and / or, The vertical distance between the laser and the initial positive electrode plate is 5-15 cm.

19. A battery cell, wherein: A positive electrode sheet comprising the positive electrode sheet described in any one of claims 11 to 16 or a positive electrode sheet prepared by the preparation method described in any one of claims 17 to 18.

20. A battery, wherein: Comprising the battery cell as claimed in claim 19.

21. An electrical device, wherein: Comprising the battery of claim 20.

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