Compound and preparation method thereof, electrode plate, battery and electric equipment

Abstract

The invention relates to a compound and a preparation method thereof, an electrode plate, a battery and electric equipment, and belongs to the technical field of secondary batteries. The structural formula of the compound is shown as a formula (I): # imgabs0 # formula (I), wherein n is a positive integer. Wherein R1 and R2 respectively and independently comprise one or more of alkyl, ether and ester; r3 comprises a cyclic group, and the cyclic group comprises one or more of pyrrole, furan, thiophene, phenyl, pyridine, indole, benzothiazole, isoindole, isobenzofuran, pyrazole, imidazole, indazole, quinoline and pyrimidine. The compound is added into the electrode plate, so that the dispersion effect of conductive carbon in the electrode plate is better, and the flexibility of the electrode plate is improved.

Description

Technical Field

[0001] This application relates to the technical field of secondary batteries, and particularly to a compound, a preparation method thereof, an electrode sheet, a battery, and an electrical device. Background Art

[0002] Lithium-ion batteries have become ideal power sources in the fields of electric vehicles and energy storage due to their outstanding advantages such as high energy density, excellent cycle life, high working voltage, low self-discharge rate, and environmental friendliness. The energy density of the battery cell has always been a competitive point for each enterprise. To improve the energy density of the battery cell, a higher electrode sheet compaction density is required. However, while the ternary system improves the electrode sheet compaction density, it will deteriorate the flexibility of the electrode sheet, and the inner circle is prone to cracking after the battery cell is wound, thus triggering safety risks. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, this application provides a compound, a preparation method thereof, an electrode sheet, a battery, and an electrical device, which can improve the flexibility of the electrode sheet and make the dispersion effect of the conductive carbon in the electrode sheet better.

[0004] In a first aspect, an embodiment of this application provides a compound, and the structural formula of the compound is shown in Formula (I):

[0005] Wherein, n is a positive integer, and R1 and R2 each independently include one or more of alkyl, ether, and ester; R3 includes a cyclic group, and the cyclic group includes one or more of pyrrole, furan, thiophene, phenyl, pyridine, indole, benzothiazole, isoindole, isobenzofuran, pyrazole, imidazole, indazole, quinoline, and pyrimidine.

[0006] In the technical solution of the embodiment of this application, the compound contains an R3 group (an unsaturated cyclic group), which can form a π-π conjugate interaction with the surface of the conductive carbon, and the compound can be adsorbed onto the surface of the conductive carbon; due to the two ester groups in the compound, it can have a certain compatibility with the solvent in the electrode paste, so that the compound can be well dispersed in the solvent, and the conductive carbon adsorbed with the compound can also be well dispersed; in addition, the steric hindrance effect of the molecular chain of the compound can also prevent the aggregation of the conductive carbon, making the resistance of the electrode sheet formed by the electrode paste lower. The molecular chains of the compound and the binder in the electrode paste are intercalated with each other. The rigidity of the unsaturated cyclic group in the compound can expand the molecular spacing of the binder, and the role of the ester group can also promote the chain slippage of the binder, thereby reducing the crystallinity of the binder and improving the flexibility of the electrode sheet. Therefore, adding this compound as an additive in the electrode sheet can make the electrode sheet have a lower resistance and better flexibility, so as to improve the energy density of the battery, and the electrical performance of the battery can be guaranteed to a certain extent.

[0007] In some embodiments, the structural formula of the compound is as shown in Formula (II):

[0008]

[0009] Wherein, R1 and R2 are each independently selected from substituted or unsubstituted methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester or carbonate ester; R4 is none, substituted or unsubstituted methylene or ethylene; R5 is selected from H, substituted or unsubstituted methyl, ethyl, alkyl ether or polyether segment. The use of phenyl can make the π-π conjugation between the compound and the conductive carbon stronger, so that the adsorption effect between the compound and the conductive carbon is better, and the steric hindrance of the molecular chain is also stronger, thereby further improving the agglomeration of the conductive carbon and making the dispersion of the conductive carbon better; in addition, phenyl can be better embedded in the molecular chain of the binder, thereby further improving the flexibility of the electrode sheet. R1 and R2 are selected as the above groups, which can further improve the flexibility of the electrode sheet through the ester chain and have better compatibility with the solvent in the electrode paste, thereby further improving the dispersion effect of the conductive carbon and further increasing the energy density of the battery.

[0010] In some embodiments, the structural formula of the compound is as shown in Formula (III):

[0011]

[0012] Wherein, R1 and R2 are both selected from substituted or unsubstituted methyl, ethyl, propyl, isopropyl, phosphate ester, chain ester, chain alcohol ester or carbonate ester; R5 is selected from H, substituted or unsubstituted methyl, ethyl, alkyl ether or polyether segment. Phenyl is directly connected to the main chain of the repeating unit of the compound, and the steric hindrance effect of the molecular chain is stronger, which can further improve the dispersion effect of the conductive carbon; in addition, the flexible effect of the ester chain at the connection of R1 and R2 and the ether chain at the connection of R5 can better promote the molecular chain slip of the binder, thereby further improving the flexibility of the electrode sheet.

[0013] In some embodiments, R1 and R2 are both selected from substituted or unsubstituted methyl, ethyl, phosphate ester, chain ester, chain alcohol ester or carbonate ester; R5 is selected from H, substituted or unsubstituted methyl, ethyl, alkyl ether or polyether segment.

[0014] In some embodiments, R1 and R2 are both selected from substituted or unsubstituted methyl, ethyl, phosphate ester, C2-C10 chain ester containing one ester group, C5-C15 chain ester containing two ester groups, C2-C10 chain alcohol ester containing one ester group, C5-C15 chain alcohol ester containing two ester groups or carbonate ester; R5 is selected from H, substituted or unsubstituted methyl, ethyl, C2-C10 chain ether or polyether segment with a molecular weight range of 20 to 500.

[0015] In some embodiments, both R1 and R2 are selected from methyl, ethyl, a C2-C10 chain ester containing one ester group, or a C5-C15 chain ester containing two ester groups; R5 is selected from H, methyl, ethyl, or a C2-C10 chain ether.

[0016] In some embodiments, the structural formula of the compound is as follows:

[0017]

[0018]

[0019] In a second aspect, the present application provides an electrode sheet, which includes an active material layer. The active material layer includes conductive carbon, a binder, and an additive, and the additive includes the compound provided in any one of the first aspects above.

[0020] In the technical solution of the embodiment of the present application, the compound additive contains an R3 group (an unsaturated cyclic group), which can form a π-π conjugation with the surface of the conductive carbon, and the compound can be adsorbed onto the surface of the conductive carbon; due to the two ester groups in the compound, it has a certain compatibility with the solvent in the electrode slurry, so that the compound can be better dispersed in the solvent, and the conductive carbon adsorbed with the compound can also be well dispersed; in addition, the steric hindrance of the molecular chain of the compound can also prevent the aggregation of the conductive carbon, making the resistance of the electrode sheet formed by the electrode slurry lower. The molecular chains of the compound and the binder in the electrode slurry are inter-embedded. The rigidity of the unsaturated cyclic group in the compound can expand the molecular spacing of the binder, and the action of the ester group can also promote the chain slippage of the binder, thereby reducing the crystallinity of the binder and improving the flexibility of the electrode sheet. Therefore, adding this compound as an additive in the electrode sheet can make the resistance of the electrode sheet lower and the flexibility better, so as to improve the energy density of the battery, and the electrical performance of the battery can be guaranteed to a certain extent.

[0021] In some embodiments, the mass ratio of the compound in the active material layer is 0.01% to 2%. When the addition amount of the compound meets the foregoing conditions, the effect of the compound can be better exerted, the flexibility of the electrode sheet is better, the addition amount of the conductive carbon can be reduced to achieve a better conductive effect, the processing performance of the electrode sheet can be improved, and the energy density of the electrode sheet can be increased. Optionally, the mass ratio of the compound in the active material layer is 0.2% to 1%.

[0022] In some embodiments, the mass ratio of the conductive carbon in the active material layer is 0.5% to 5%. The lower limit of the addition of the conductive carbon is relatively low, and adding less conductive carbon can achieve a better conductive effect, so that the addition amount of the conductive carbon can be reduced, and the addition amount of the active material can be increased to improve the energy density of the battery. Optionally, the mass ratio of the conductive carbon in the active material layer is 1% to 3%.

[0023] In some embodiments, the mass ratio of the binder in the active material layer is 0.1% to 4%. The binder with this addition amount can achieve a good bonding effect, and in cooperation with the compound additive, it can reduce the crystallinity of the binder and improve the flexibility of the electrode sheet. Optionally, the mass ratio of the binder in the active material layer is 0.5% to 2%.

[0024] In some embodiments, the conductive carbon includes at least one of conductive carbon black, carbon fiber, carbon nanotube, Ketjen black, graphene, and acetylene black. These conductive carbons can interact with the compound additive, resulting in good dispersion of the conductive carbon in the electrode paste, and thus making the dispersion of the conductive carbon in the electrode sheet more uniform.

[0025] In some embodiments, the binder includes at least one of polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyacrylic acid, polymethacrylic acid, and sodium polyacrylate. These binders are prone to interact with the compound additive, causing the molecular chains of the two to interpenetrate and the molecular chains of the binder to slip, thereby making the electrode sheet more flexible. Optionally, the binder includes polyvinylidene fluoride or / and polyacrylic acid.

[0026] In a third aspect, the present application provides a battery, including the electrode sheet provided in any one of the second aspects.

[0027] In a fourth aspect, the present application provides an electrical device, including the battery provided in the third aspect.

[0028] In a fifth aspect, the present application provides a method for preparing a compound, including the following steps:

[0029]

[0030] Among them, R1 includes one or more of alkyl, ether, and ester; R3 includes a cyclic group, and the cyclic group includes one or more of pyrrole, furan, thiophene, phenyl, pyridine, indole, benzothiazole, isoindole, isobenzofuran, pyrazole, imidazole, indazole, quinoline, and pyrimidine.

[0031] In the technical solution of the embodiment of the present application, the compound prepared by the above preparation method contains an R3 group (unsaturated cyclic group), which can form a π-π conjugation with the surface of the conductive carbon, and the compound can be adsorbed on the surface of the conductive carbon; due to the two ester groups in the compound, it can have a certain compatibility with the solvent in the electrode paste, so that the compound can be better dispersed in the solvent, and the conductive carbon adsorbed with the compound can also be well dispersed; in addition, the steric hindrance of the molecular chain of the compound can also prevent the aggregation of the conductive carbon, making the resistance of the electrode sheet formed by the electrode paste lower. The molecular chains of the compound and the binder in the electrode paste are intercalated with each other. The rigidity of the unsaturated cyclic group in the compound can expand the molecular spacing of the binder, and the action of the ester group can also promote the chain slippage of the binder, thereby reducing the crystallinity of the binder and improving the flexibility of the electrode sheet. Therefore, adding this compound to the electrode sheet as an additive can make the resistance of the electrode sheet lower and the flexibility better, so as to improve the energy density of the battery, and the electrical performance of the battery can be guaranteed to a certain extent.

[0032] In some embodiments, the method includes the following steps:

[0033]

[0034] Wherein, R1 is selected from substituted or unsubstituted methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester or carbonate; R4 is none, substituted or unsubstituted methylene or ethyl. The use of phenyl can make the π-π conjugation between the compound and the conductive carbon stronger, so that the adsorption effect between the compound and the conductive carbon is better, and the steric hindrance of the molecular chain is also stronger, thereby further improving the aggregation of the conductive carbon and making the dispersion of the conductive carbon better; in addition, phenyl can be better embedded in the molecular chain of the binder, thereby further improving the flexibility of the electrode sheet. Selecting R1 as the above group can further improve the flexibility of the electrode sheet through the ester chain, and has better compatibility with the solvent in the electrode paste, thereby further improving the dispersion effect of the conductive carbon to further improve the energy density of the battery.

[0035] In some embodiments, the preparation method further includes:

[0036]

[0037] Wherein, X is H, methyl, alkyl ether or polyether segment.

[0038] In some embodiments, the method includes the following steps:

[0039]

[0040] Among them, R is selected from methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester or carbonate ester.

[0041] In some embodiments, the preparation method further includes:

[0042]

[0043] Among them, X is H, methyl, alkyl ether or polyether segment.

[0044] In some embodiments, the initiator includes dicumyl peroxide or / and benzoyl peroxide.

[0045] In some embodiments, the catalyst includes at least one of triethylamine, sodium hydroxide and potassium hydroxide.

[0046] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the following specifically illustrates the specific embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. And in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0048] Figure 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application;

[0049] Figure 2 is a schematic exploded view of a battery provided by some embodiments of the present application;

[0050] Figure 3 is a schematic structural diagram of a battery cell provided by some embodiments of the present application;

[0051] Figure 4 is an exploded view of a battery cell provided by some embodiments of the present application;

[0052] Figure 5 is a schematic diagram of the layer structure of a negative electrode plate provided by some embodiments of the present application;

[0053] Figure 6 is a resistance diagram of a positive electrode plate provided by Embodiment 1 and Comparative Example 1 of the present application;

[0054] Figure 7Camera - taken photo of the cracking situation of the positive electrode sheets provided in Example 1 and Comparative Example 1 of the present application;

[0055] Figure 8 Discharge DCR - SOC curve graphs of the batteries provided in Example 1 and Comparative Example 1 of the present application at 25°C and different state - of - charge conditions;

[0056] Figure 9 Discharge DCR - SOC curve graphs of the batteries provided in Example 1 and Comparative Example 1 of the present application at - 25°C and different state - of - charge conditions;

[0057] Figure 10 Cycling performance graph of the batteries provided in Example 1 and Comparative Example 1 of the present application.

[0058] Icons: 1000 - vehicle; 100 - battery; 10 - box; 11 - accommodation space; 12 - first part; 13 - second part; 20 - battery cell; 21 - outer shell; 211 - opening; 22 - end - cover assembly; 221 - end - cover; 222 - electrode terminal; 23 - electrode assembly; 231 - negative electrode sheet; 2311 - negative current collector; 2312 - negative active layer; 2312a - first negative active layer; 2312b - second negative active layer; 24 - current - collecting member; 25 - insulation protection member; 200 - controller; 300 - motor. Detailed implementation manners

[0059] Embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above - mentioned drawings are intended to cover non - exclusive inclusion.

[0061] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary - secondary relationship of the indicated technical features. In the description of the embodiments of the present application, "a plurality of" means more than two unless otherwise specifically defined.

[0062] References to "embodiments" in this document mean that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0063] In the description of the embodiments of the present application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally represents an "or" relationship between the associated objects before and after.

[0064] In the description of the embodiments of the present application, the term "plural" refers to two or more (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0065] In the description of the embodiments of the present application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0066] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0067] Currently, from the perspective of the development of the market situation, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power stations, but also widely used in electric transportation such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as military equipment and aerospace. With the continuous expansion of the application fields of power batteries, the market demand is also continuously increasing.

[0068] The power battery can be a lithium-ion battery. Lithium-ion batteries have become the ideal power source in the fields of electric vehicles and energy storage due to their outstanding advantages such as high energy density, excellent cycle life, high working voltage, low self-discharge rate, and environmental friendliness. The energy density of the battery cell has always been a competitive point for each enterprise. To increase the energy density of the battery cell, a higher electrode pressing density is required. However, while the ternary system increases the electrode pressing density, it will deteriorate the flexibility of the electrode, and the inner circle of the battery cell is prone to cracking after winding, thus triggering safety risks.

[0069] Based on the above considerations, in order to improve the flexibility of the electrode sheet and at the same time improve the dispersion of conductive carbon in the electrode sheet to improve the processing performance of the electrode sheet, a compound additive is designed to be added to the electrode sheet. The electrode sheet includes an active material layer, and the active material layer includes conductive carbon, a binder, and an additive. The additive includes a compound, and the structural formula of the compound is shown in formula (I):

[0070] Wherein, n is a positive integer, and R1 and R2 each independently include one or more of alkyl, ether, and ester; R3 includes a cyclic group, and the cyclic group includes one or more of pyrrole, furan, thiophene, phenyl, pyridine, indole, benzothiazole, isoindole, isobenzofuran, pyrazole, imidazole, indazole, quinoline, and pyrimidine.

[0071] In such an electrode sheet, the compound additive contains an R3 group (an unsaturated cyclic group), which can form a π-π conjugation with the surface of the conductive carbon, and can adsorb the compound onto the surface of the conductive carbon; due to the two ester groups in the compound, it can be somewhat compatible with the solvent in the electrode slurry, so that the compound can be well dispersed in the solvent, and the conductive carbon adsorbed with the compound can also be well dispersed; in addition, the steric hindrance of the molecular chain of the compound can also prevent the aggregation of the conductive carbon, making the resistance of the electrode sheet formed by the electrode slurry lower. The molecular chains of the compound and the binder in the electrode slurry are intercalated with each other. The rigidity of the unsaturated cyclic group in the compound can expand the molecular spacing of the binder, and the action of the ester group can also promote the chain slippage of the binder, thereby reducing the crystallinity of the binder and improving the flexibility of the electrode sheet. Therefore, adding this compound to the electrode sheet as an additive can make the electrode sheet have a lower resistance and better flexibility, so as to increase the energy density of the battery, and the electrical performance of the battery can be guaranteed to a certain extent.

[0072] The electrode sheet can be used to prepare an electrode assembly, which can be assembled into a battery. The battery can be a battery cell, a module, a battery pack, etc. The battery can be used, but not limited to, in electrical equipment such as vehicles, ships, or aircraft. The battery disclosed in this application can be used to form the power supply system of the electrical equipment. In this way, it is beneficial to improve the cycling performance of the battery and reduce the self-discharge and the decrease in Coulomb efficiency of the battery at the initial stage of charging.

[0073] Embodiments of the present application provide an electrical equipment using a battery as a power source. The electrical equipment can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or an extended-range electric vehicle, etc.; The spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc.; The electric toy includes a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, etc.; The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator, and an electric planer, etc. Embodiments of the present application do not impose special restrictions on the above electrical equipment.

[0074] For the convenience of description, the following embodiments take the electrical equipment as a vehicle as an example for description.

[0075] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a vehicle 1000 provided by some embodiments of the present application. A battery 100 is disposed inside the vehicle 1000. The battery 100 can be disposed at the bottom, the head, or the tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000. For example, the battery 100 can be used as the operating power source of the vehicle 1000.

[0076] The vehicle 1000 may further include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300. For example, it is used for the working power requirements during the start, navigation, and driving of the vehicle 1000.

[0077] In some embodiments of the present application, the battery 100 can not only be used as the operating power source of the vehicle 1000, but also be used as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0078] Figure 2 which is a schematic exploded view of a battery 100 provided by some embodiments of the present application. Please refer to Figure 2 ,the battery 100 includes a box body 10 and battery cells 20, and the battery cells 20 are received in the box body 10.

[0079] The box body 10 is used to provide a receiving space 11 for the battery cell 20. In some embodiments, the box body 10 may include a first part 12 and a second part 13, and the first part 12 and the second part 13 cover each other to define a receiving space 11 for receiving the battery cell 20. Of course, the connection between the first part 12 and the second part 13 can be sealed by a sealing member (not shown in the figure), and the sealing member can be a sealing ring, a sealant, etc.

[0080] The first part 12 and the second part 13 can be of various shapes, such as a cuboid, a cylinder, etc. The first part 12 can be a hollow structure with an opening on one side to form a receiving cavity for receiving the battery cell 20, and the second part 13 can also be a hollow structure with an opening on one side to form a receiving cavity for receiving the battery cell 20. When the opening side of the second part 13 covers the opening side of the first part 12, the box body 10 with the receiving space 11 is formed. Of course, as Figure 2 shown, it can also be that the first part 12 is a hollow structure with an opening on one side, and the second part 13 is a plate-like structure. When the second part 13 covers the opening side of the first part 12, the box body 10 with the receiving space 11 is formed.

[0081] In the battery 100, the battery cell 20 can be one or multiple. If there are multiple battery cells 20, the multiple battery cells 20 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection means that there are both series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid connection together, and then the whole formed by the multiple battery cells 20 is received in the box body 10; of course, it can also be that the multiple battery cells 20 are first connected in series, in parallel, or in a hybrid connection to form battery modules, and then the multiple battery modules are connected in series, in parallel, or in a hybrid connection to form a whole and are received in the box body 10. The battery cell 20 can be in the shape of a cylinder, a flat body, a cuboid, or other shapes, etc. Figure 2 An exemplary case where the battery cell 20 is square is shown.

[0082] In some embodiments, the battery 100 may further include a busbar component (not shown in the figure), and the multiple battery cells 20 can be electrically connected through the busbar component to achieve series, parallel, or hybrid connection of the multiple battery cells 20.

[0083] Figure 3 It is a schematic structural diagram of the battery cell 20 provided by some embodiments of the present application. Figure 4 It is an exploded view of the battery cell 20 provided by some embodiments of the present application. Please refer to Figure 3 and Figure 4, the battery cell 20 may include a housing 21, an end cap assembly 22, and an electrode assembly 23. The housing 21 has an opening 211, the electrode assembly 23 is accommodated within the housing 21, and the end cap assembly 22 is used to seal the opening 211.

[0084] The shape of the housing 21 can be determined according to the specific shape of the electrode assembly 23. For example, if the electrode assembly 23 is a cuboid structure, the housing 21 can be selected as a cuboid structure. Figure 3 and Figure 4 An exemplary case where the housing 21 and the electrode assembly 23 are square is shown.

[0085] The material of the housing 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiments of the present application do not make special restrictions on this.

[0086] The end cap assembly 22 includes an end cap 221 and electrode terminals 222. The end cap assembly 22 is used to seal the opening 211 of the housing 21 to form a sealed installation space (not shown in the figure), and the installation space is used to accommodate the electrode assembly 23. The installation space is also used to accommodate an electrolyte, such as an electrolyte solution. The end cap assembly 22 serves as a component for outputting the electrical energy of the electrode assembly 23, and the electrode terminals 222 in the end cap assembly 22 are used to electrically connect to the electrode assembly 23, that is, the electrode terminals 222 are electrically connected to the tabs of the electrode assembly 23. For example, the electrode terminals 222 and the tabs are connected through a current collecting member 24 to achieve the electrical connection between the electrode terminals 222 and the tabs.

[0087] It should be noted that the opening 211 of the housing 21 can be one or two. If the opening 211 of the housing 21 is one, the end cap assembly 22 can also be one, and two electrode terminals 222 can be provided in the end cap assembly 22, and the two electrode terminals 222 are respectively used to electrically connect to the positive tab and the negative tab of the electrode assembly 23. If the opening 211 of the housing 21 is two, for example, the two openings 211 are provided on opposite sides of the housing 21, the end cap assembly 22 can also be two, and the two end cap assemblies 22 respectively cover the two openings 211 of the housing 21. In this case, the electrode terminals 222 in one end cap assembly 22 can be positive electrode terminals for electrically connecting to the positive tab of the electrode assembly 23; the electrode terminals 222 in the other end cap assembly 22 can be negative electrode terminals for electrically connecting to the negative electrode plate 231 of the electrode assembly 23.

[0088] In some embodiments, such as Figure 4As shown, the battery cell 20 may further include an insulating protection member 25 fixed to the outer periphery of the electrode assembly 23, and the insulating protection member 25 is used for insulating and isolating the electrode assembly 23 from the housing 21. Exemplarily, the insulating protection member 25 is a tape adhered to the outer periphery of the electrode assembly 23. In some embodiments, the number of electrode assemblies 23 is multiple, and the insulating protection member 25 surrounds the outer periphery of the multiple electrode assemblies 23 and forms a whole structure of the multiple electrode assemblies 23 to keep the structure of the electrode assembly 23 stable. Among them, the electrode assembly 23 may be a wound electrode assembly or a stacked electrode assembly, and the embodiments of the present application are not limited thereto.

[0089] The electrode assembly 23 includes a positive electrode tab, a negative electrode tab, and a separator. The material of the separator may be PP (polypropylene) or PE (polyethylene), etc.

[0090] The positive electrode tab includes a positive current collector and a positive active material layer. The positive active material layer is disposed on the surface of the positive current collector, and the positive current collector without the positive active material layer coated thereon protrudes from the positive current collector with the positive active material layer coated thereon. The positive current collector without the positive active material layer coated thereon serves as the positive electrode tab. Among them, the material of the positive current collector may be aluminum, and the positive active material may be lithium iron phosphate manganese, lithium iron phosphate, lithium cobalt iron phosphate, lithium manganese phosphate, ternary material, quaternary material, etc.

[0091] The negative electrode tab includes a negative current collector and a negative active material layer. The negative active material layer is disposed on the surface of the negative current collector, and the negative current collector without the negative active material layer coated thereon protrudes from the negative current collector with the negative active material layer coated thereon. The negative current collector without the negative active material layer coated thereon serves as the negative electrode tab. Among them, the material of the negative current collector may be copper, and the negative active material may be graphite, silicon, silicon-carbon composite, etc.

[0092] The present application designs a compound, which can be used as an additive in the positive electrode tab or as an additive in the negative electrode tab, and is hereinafter collectively referred to as the electrode tab for description.

[0093] The electrode tab includes an active material layer, and the active material layer includes conductive carbon, a binder, and an additive. The additive includes a compound with the structural formula as shown in formula (I):

[0094] Among them, n is a positive integer, and R1 and R2 each independently include one or more of alkyl, ether, and ester; R3 includes a cyclic group, and the cyclic group includes one or more of pyrrole, furan, thiophene, phenyl, pyridine, indole, benzothiazole, isoindole, isobenzofuran, pyrazole, imidazole, indazole, quinoline, and pyrimidine.

[0095] "Alkyl" refers to a linear or branched saturated group having from 1 to 24, preferably from 1 to 16, more preferably from 1 to 14, even more preferably from 1 to 12, still more preferably 1, 2, 3, 4, 5 or 6 carbon atoms and bonded to the remainder of the molecule by a single bond, including, for example and without limitation, methyl, ethyl, isopropyl, isobutyl, tert-butyl, heptyl, octyl, decyl, dodecyl, lauryl, hexadecyl, octadecyl, pentyl, 2-ethylhexyl, 2-methylbutyl, 5-methylhexyl, etc.

[0096] "Cyclic group" refers to a hydrocarbonated ring of 3 to 10 members, wherein one or more of the atoms in the ring, optionally 1, 2 or 3 of the atoms in the ring, are elements other than carbon such as nitrogen, oxygen or sulfur, and may be unsaturated. For the purposes of this application, the heterocycle can be a monocyclic, bicyclic or tricyclic system, which can include a fused ring system; and the nitrogen, carbon or sulfur atoms in the residue heterocycle can be optionally oxidized; the nitrogen atoms can be optionally quaternized; and the residue heterocyclic group can be partially or fully saturated or aromatic. For example: the cyclic group includes one or more of pyrrole, furan, thiophene, phenyl, pyridine, indole, benzothiazole, isoindole, isobenzofuran, pyrazole, imidazole, indazole, quinoline, pyrimidine.

[0097] The active material layer refers to: a layer structure provided on a current collector (the negative electrode active material layer on the negative electrode current collector, or the positive electrode active material layer on the positive electrode current collector), and the active material layer includes an active material (the negative electrode active material layer contains a negative electrode active material, or the positive electrode active material layer contains a positive electrode active material), a conductive agent, a binder, an additive, etc.

[0098] The conductive carbon can be spherical, chain-like or network-like, including but not limited to at least one of conductive carbon black, carbon fiber, carbon nanotube, Ketjen black, graphene and acetylene black.

[0099] The binder is a high molecular compound having a binding property, including but not limited to at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyacrylic acid, polymethacrylic acid, sodium polyacrylate.

[0100] In the compound additive, the groups at R1 and R2 can be the same or different, and this application does not make a limitation. The R1 and R2 groups can be substituted or unsubstituted. The cyclic group at R3 can be connected to the main chain of the repeating unit or indirectly connected to the main chain of the repeating unit, and the R3 group can be substituted or unsubstituted.

[0101] In such an electrode sheet, the compound additive contains an R3 group (an unsaturated cyclic group) that can form a π-π conjugation with the surface of the conductive carbon, enabling the compound to be adsorbed onto the surface of the conductive carbon. Due to the two ester groups in the compound, it has a certain compatibility with the solvent in the electrode paste, allowing the compound to be well-dispersed in the solvent, and the conductive carbon adsorbed with the compound can also be well-dispersed. In addition, the steric hindrance effect of the molecular chain of the compound can also prevent the aggregation of the conductive carbon, resulting in a lower resistance of the electrode sheet formed by the electrode paste. The compound interpenetrates with the molecular chain of the binder in the electrode paste. The rigidity of the unsaturated cyclic group in the compound can expand the molecular spacing of the binder, and the action of the ester group can also promote the chain slippage of the binder, thereby reducing the crystallinity of the binder and improving the flexibility of the electrode sheet. Therefore, adding this compound as an additive in the electrode sheet can make the electrode sheet have a lower resistance and better flexibility, so as to improve the energy density of the battery, and the electrical performance of the battery can be guaranteed to a certain extent.

[0102] In some embodiments, the structural formula of the compound is shown in Formula (II):

[0103] Wherein, R1 and R2 are each independently selected from substituted or unsubstituted methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester or carbonate; R4 is none, substituted or unsubstituted methylene or ethylene; R5 is selected from H, substituted or unsubstituted methyl, ethyl, alkyl ether or polyether segment. R4 being none means that the phenyl group is directly connected to the main chain of the repeating unit without any other groups in between; of course, in other embodiments, it may also contain substituted or unsubstituted methylene or ethylene groups, etc.

[0104] It should be understood that the compounds of the present application as described herein can be partially substituted by any number of substituents or functional groups. Generally, the term "substituted (with)" and the substituents contained in the formulas of the present application all refer to the replacement of a hydrogen group in a given structure with a group of the designated substituent. When more than one position in any given structure can be substituted by more than one substituent selected from the designated group, the substituents can be the same or different at each position. As used herein, the term "substituted" is intended to include substitution with all permissible substituents of organic compounds and any substituents described herein.

[0105] For example, substituents include, but are not limited to, the following groups that result in the formation of stable moieties: aliphatic groups, alkyl groups, alkenyl groups, alkynyl groups, heteroaliphatic groups, heterocyclic groups, aryl groups, heteroaryl groups, acyl groups, oxo groups, imino groups, thiocarbonyl groups, cyano groups, isocyano groups, amino groups, azide groups, nitro groups, hydroxy groups, mercapto groups, and halo groups, and any combination thereof, including but not limited to the following groups: aliphatic amino groups, heteroaliphatic amino groups, alkylamino groups, heteroalkylamino groups, arylamino groups, heteroarylamino groups, alkylaryl groups, arylalkyl groups, aliphatic oxy groups, heteroaliphatic oxy groups, alkoxy groups, heteroalkoxy groups, aryloxy groups, heteroaryloxy groups, aliphatic thio groups, heteroaliphatic thio groups, alkylthio groups, heteroalkylthio groups, arylthio groups, heteroarylthio groups, acyloxy groups, etc. This application encompasses any and all such combinations to obtain stable substituents / moieties. For the purposes of this application, a heteroatom such as nitrogen may have hydrogen substituents and / or any suitable substituents as described herein that satisfy the valence of the heteroatom and result in the formation of a stable moiety.

[0106] When the compound contains a phenyl group, the π-π conjugation between the compound and the conductive carbon can be enhanced, resulting in better adsorption between the compound and the conductive carbon. Additionally, the steric hindrance of the molecular chain is stronger, which can further improve the agglomeration of the conductive carbon and enhance its dispersion. Moreover, the phenyl group can be better embedded into the molecular chain of the binder, thereby further improving the flexibility of the electrode sheet. When R1 and R2 are selected from the above groups, the flexibility of the electrode sheet can be further enhanced through the ester chain, and the compatibility with the solvent in the electrode paste is better, which can further improve the dispersion effect of the conductive carbon and further increase the energy density of the battery.

[0107] In some embodiments, the structural formula of the compound is as follows:

[0108] Wherein, both R1 and R2 are selected from substituted or unsubstituted methyl, ethyl, propyl, isopropyl, phosphate ester, chain ester, chain alcohol ester, or carbonate; R5 is selected from H, substituted or unsubstituted methyl, ethyl, alkyl ether, or polyether segment.

[0109] In the compound, the phenyl group is directly connected to the main chain of the repeating unit of the compound, and the steric hindrance effect of the molecular chain is stronger, which can further improve the dispersion effect of the conductive carbon. Additionally, the flexibility of the ester chain at the connection of R1 and R2 and the ether chain at the connection of R5 can better promote the slippage of the molecular chain of the binder, thereby further improving the flexibility of the electrode sheet.

[0110] In some embodiments, both R1 and R2 are selected from substituted or unsubstituted methyl, ethyl, phosphate ester, chain ester, chain alcohol ester, or carbonate; R5 is selected from H, substituted or unsubstituted methyl, ethyl, alkyl ether, or polyether segment.

[0111] Optionally, both R1 and R2 are selected from substituted or unsubstituted phosphate esters, chain esters, chain alcohol esters or carbonate esters, and R5 is selected from alkyl ethers or polyether segments. R1 and R2 (phosphate esters, chain esters, chain alcohol esters or carbonate esters) can form an ester chain with the connected ester group, and the ether chains of R5 can all promote the chain slippage of the molecular chains of the binder, thereby reducing the crystallinity of the binder to improve the flexibility of the binder, and thus better improving the flexibility of the electrode sheet.

[0112] In some embodiments, both R1 and R2 are selected from substituted or unsubstituted methyl, ethyl, phosphate esters, C2-C10 chain esters containing one ester group, C5-C15 chain esters containing two ester groups, C2-C10 chain alcohol esters containing one ester group, C5-C15 chain alcohol esters containing two ester groups or carbonate esters; R5 is selected from H, substituted or unsubstituted methyl, ethyl, C2-C10 chain ethers or polyether segments with a molecular weight range of 20 to 500.

[0113] Optionally, both R1 and R2 are selected from substituted or unsubstituted phosphate esters, C2-C10 chain esters containing one ester group, C5-C15 chain esters containing two ester groups, C2-C10 chain alcohol esters containing one ester group, C5-C15 chain alcohol esters containing two ester groups or carbonate esters, and R5 is selected from C2-C10 chain ethers or polyether segments with a molecular weight range of 20 to 500. R1 and R2 (phosphate esters, chain esters, chain alcohol esters or carbonate esters) can form an ester chain with the connected ester group, and the ether chains of R5 can all promote the chain slippage of the molecular chains of the binder, thereby reducing the crystallinity of the binder to improve the flexibility of the binder, and thus better improving the flexibility of the electrode sheet.

[0114] In some embodiments, both R1 and R2 are selected from methyl, ethyl, C2-C10 chain esters containing one ester group or C5-C15 chain esters containing two ester groups; R5 is selected from H, methyl, ethyl or C2-C10 chain ethers.

[0115] Optionally, both R1 and R2 are selected from C2-C10 chain esters containing one ester group or C5-C15 chain esters containing two ester groups, and R5 is selected from C2-C10 chain ethers. Both the ester chain and the ether chain can promote the chain slippage of the molecular chains of the binder, thereby reducing the crystallinity of the binder to improve the flexibility of the binder, and thus better improving the flexibility of the electrode sheet.

[0116] In some embodiments, the structural formula of the compound is as follows:

[0117]

[0118]

[0119] In some embodiments, the structural formula of the compound is as follows:

[0120]

[0121] In the compound, there is a benzene ring, which can make the π-π conjugation between the compound and the conductive carbon stronger, so that the adsorption effect between the compound and the conductive carbon is better, and the steric hindrance of the molecular chain is also stronger, thereby further improving the agglomeration of the conductive carbon and making the dispersion of the conductive carbon better; in addition, the phenyl group can be better embedded in the molecular chain of the binder, thereby further improving the flexibility of the electrode sheet. And, it also contains an ester group and an ether chain at the same time, which can better promote the molecular chain slip of the binder, thereby further improving the flexibility of the electrode sheet.

[0122] After introducing the structure of the compound additive above, the addition amounts of the components in the electrode sheet will be described below.

[0123] In some embodiments, the mass ratio of the compound in the active material layer is 0.01% to 2%. When the addition amount of the compound meets the foregoing conditions, the effect of the compound can be better exerted, the flexibility of the electrode sheet is better, the addition amount of the conductive carbon can be reduced to achieve a good conductive effect, the processing performance of the electrode sheet can be improved, and the energy density of the electrode sheet can be increased. In addition, the lower limit of the addition amount of the compound is very low, and when the addition amount is small, it can play a certain role in increasing the flexibility of the electrode sheet and improving the dispersion performance of the conductive carbon in the electrode sheet.

[0124] Exemplarily, the mass ratio of the compound in the active material layer is 0.01%, 0.02%, 0.04%, 0.06%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45% or 0.5%. Optionally, the mass ratio of the compound in the active material layer is 0.2% to 1%.

[0125] In some embodiments, the mass ratio of the conductive carbon in the active material layer is 0.5% to 5%. The lower limit of the addition of the conductive carbon is relatively low, and adding less conductive carbon can achieve a good conductive effect, so that the addition amount of the conductive carbon can be reduced, and the addition amount of the active material can be increased to improve the energy density of the battery.

[0126] Exemplarily, the mass ratio of the conductive carbon in the active material layer is 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%. Optionally, the mass ratio of the conductive carbon in the active material layer is 1% to 3%.

[0127] In some embodiments, the mass percentage of the binder in the active material layer is 0.1% to 4%. The binder added in such an amount can achieve a good bonding effect, and in combination with the compound additive, it can reduce the crystallinity of the binder and improve the flexibility of the electrode sheet.

[0128] Exemplarily, the mass percentage of the binder in the active material layer is 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5% or 4%. Optionally, the mass percentage of the binder in the active material layer is 0.5% to 2%.

[0129] In some embodiments, the conductive carbon includes conductive carbon black and / or carbon nanotubes. The surface of the conductive carbon black includes hydroxyl groups, carboxyl groups, amino groups, thiol groups, amide groups, etc., which can form stronger π-π conjugation with the unsaturated cyclic groups (such as phenyl groups) in the compound, so that the adsorption effect between the compound and the conductive carbon is better. Through the solvation chain segments (ester chains) of the compound, the compound can be better dispersed, so that the conductive carbon black has a good dispersion effect. At the same time, due to the steric hindrance of the molecular chains of the compound, the agglomeration of the conductive carbon black can be better hindered, the dispersion effect of the conductive carbon black is better, the resistance of the electrode sheet is reduced, and the processing performance of the electrode sheet is improved. In other embodiments, the conductive carbon may further include at least one of carbon fiber, Ketjen black, graphene, and acetylene black.

[0130] In some embodiments, the binder includes polyvinylidene fluoride and / or polyacrylic acid. These binders have a relatively high crystallinity. After the electrode sheet is formed, fragments are likely to be caused during the winding process. The role of the compound additive can cause the binders to interpenetrate each other to increase the molecular spacing in the binder, and the ether chains and ester chains in the compound can promote chain slippage, thereby reducing the crystallinity of the binder and improving the flexibility of the binder, and thus improving the flexibility of the electrode sheet.

[0131] The following takes polyvinylidene fluoride as the binder as an example to illustrate the detailed mechanism. The structural formula of polyvinylidene fluoride is: Polyvinylidene fluoride is solid by itself. When it is in a solid state, the two C-F bonds in the repeating unit will wind around each other, resulting in a relatively high crystallinity of polyvinylidene fluoride. If polyvinylidene fluoride is dispersed in the electrode paste, the two C-F bonds will open and have a certain spacing. If the above-mentioned compound (Formula (I), Formula (II) or Formula (III)) is added to the electrode paste, the molecular chain of the compound will interpenetrate with the molecular chain of polyvinylidene fluoride, and due to the rigid effect of the unsaturated cyclic group, it can be inserted between the two opened C-F bonds. Thus, even after the electrode paste dries, due to the rigid effect of the unsaturated cyclic group, the winding between the two C-F bonds can be reduced to a certain extent, and the molecular spacing of polyvinylidene fluoride can be enlarged. At the same time, the ether chain and ester chain in the compound can promote the chain slip of polyvinylidene fluoride, reduce the crystallinity of polyvinylidene fluoride, improve the flexibility of polyvinylidene fluoride, and thus improve the flexibility of the electrode sheet.

[0132] The present application provides a battery, including the electrode sheet provided in any one of the above.

[0133] The present application provides an electrical device, including the battery provided above.

[0134] After introducing the compound and its application (the application of the compound is: as an additive for the electrode sheet) above, the preparation method of the compound will be specifically introduced below.

[0135] In the compound of Formula (I), R1 and R2 are the same, and its preparation method includes the following steps:

[0136]

[0137] Among them, R1 includes one or more of alkyl, ether, and ester; R3 includes a cyclic group, and the cyclic group includes one or more of pyrrole, furan, thiophene, phenyl, pyridine, indole, benzothiazole, isoindole, isobenzofuran, pyrazole, imidazole, indazole, quinoline, and pyrimidine.

[0138] In some embodiments, in the compound of Formula (II), R1 and R2 are the same, and R5 is H. The preparation method of the compound of Formula (II) includes the following steps:

[0139]

[0140] Among them, R1 is selected from substituted or unsubstituted methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester, or carbonate; R4 is none, substituted or unsubstituted methylene or ethyl.

[0141] In some embodiments, in the compound of Formula (II), R1 and R2 are the same, and R5 is methyl, ethyl, alkyl ether, or polyether segment. The preparation method of the compound of Formula (II) includes the following steps:

[0142]

[0143]

[0144] Among them, R1 is selected from substituted or unsubstituted methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester or carbonate; R4 is none, substituted or unsubstituted methylene or ethyl, and X is H, methyl, alkyl ether or polyether segment.

[0145] In some embodiments, in the compound of formula (III), R1 and R2 are the same, R5 is H, and the preparation method of the compound of formula (III) includes the following steps:

[0146]

[0147] Among them, R is selected from methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester or carbonate.

[0148] In some embodiments, in the compound of formula (III), R1 and R2 are the same, R5 is methyl, ethyl, alkyl ether or polyether segment, and the preparation method of the compound of formula (III) includes the following steps:

[0149] Among them, R is selected from methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester or carbonate; X is H, methyl, alkyl ether or polyether segment. Optionally, R are all selected from methyl, C2-C10 chain ester containing one ester group or C5-C15 chain ester containing two ester groups; X is selected from H, methyl or C2-C10 chain ether.

[0150] In some embodiments, the initiator includes dicumyl peroxide or / and benzoyl peroxide.

[0151] In some embodiments, the catalyst includes at least one of triethylamine, sodium hydroxide and potassium hydroxide.

[0152] Mix the above compound as an additive with conductive carbon, binder and active material to form an electrode paste, and coat the electrode paste on the surface of the current collector and dry to form an electrode sheet.

[0153] Next, one or more embodiments will be described in more detail with reference to the following examples. Of course, these examples do not limit the scope of one or more embodiments.

[0154] Example 1

[0155] Prepare compound (III-1), the structural formula is as follows:

[0156]

[0157] The preparation method of compound III-1 includes:

[0158] Dissolve 0.1 mol of styrene and 1 mol of maleic anhydride in 500 mL of acetone solution, then add 0.01 mol of diisopropylbenzene peroxide initiator, and react at 80 °C for 6 h to obtain intermediate 1-1. The structural formula of intermediate 1-1 is as follows:

[0159]

[0160] Disperse intermediate 1-1 and 1 mol of in 500 mL of methyl ethyl ketone, then add 0.1 mol of triethylamine catalyst, and react at 80 °C for 10 h to obtain compound III-1.

[0161] (2) Preparation of the positive electrode plate

[0162] Mix the positive electrode active material lithium iron phosphate (LiFePO4), conductive agent Super P, binder polyvinylidene fluoride (PVDF), and compound III-1 with a mass ratio of 96.8:2:1:0.2 in the solvent N-methylpyrrolidone (NMP) to form a positive electrode active slurry with a solid content of 50 wt%.

[0163] Coat the positive electrode active slurry on the current collector aluminum foil (with a thickness of 6 μm) and dry it at 85 °C for 4 h, then perform cold pressing. The coating weight is 300 mg / 1540.25 mm 2 ; then perform edge trimming and slicing, and dry it at 85 °C under vacuum conditions for 4 h to obtain the positive electrode plate. Among them, the thickness of the single-sided positive electrode active material layer is 200 μm.

[0164] (3) Preparation of the negative electrode plate:

[0165] Disperse graphite, conductive agent Super P, binder styrene-butadiene rubber (SBR), and thickener CMC-Na with a mass ratio of 92:3:2.5:2.5 in deionized water and mix them evenly to obtain the negative electrode active slurry.

[0166] Coat the negative electrode active slurry on the current collector copper foil (with a thickness of 9 μm) and dry it at 85 °C for 4 h, then perform cold pressing, edge trimming, and slicing, and dry it at 120 °C under vacuum conditions for 12 h to obtain the negative electrode plate. Among them, the thickness of the single-sided negative electrode active material layer is 150 μm.

[0167] (4) Preparation of the electrode assembly:

[0168] The separator is made of PP (polypropylene), and the thickness of the separator is 16 μm. After laminating the negative electrode sheet, the first separator, the positive electrode sheet, and the second separator, it is wound 25 turns to form an electrode assembly.

[0169] (5) Prepare a battery cell:

[0170] Weld the tabs of the electrode assembly, place the electrode assembly into the battery case, and inject the electrolyte (the electrolyte is a 1M lithium hexafluorophosphate solution in EC / DMC (1:1 vol%)), and then through processes such as vacuum packaging, standing, formation, and shaping, a battery cell is obtained.

[0171] Example 2

[0172] Example 2 is basically the same as Example 1, except that Compound III-1 is replaced with Compound III-2, and the structural formula is as follows:

[0173]

[0174] The preparation method of Compound III-2 includes:

[0175] Dissolve 0.1 mol of styrene and 1 mol of maleic anhydride in 500 mL of acetone solution, then add 0.01 mol of diisopropylbenzene peroxide initiator, and react at 80 °C for 6 h to obtain Intermediate 2-1, and the structural formula of Intermediate 2-1 is as follows:

[0176]

[0177] Disperse Intermediate 2-1 and 1 mol of ethanol in 500 mL of butanone, then add 0.1 mol of triethylamine catalyst, and react at 80 °C for 7 h to obtain Intermediate 2-2, and the structural formula of Intermediate 2-2 is as follows:

[0178]

[0179] Mix Intermediate 2-2 and 1 mol of formaldehyde, and add 0.1 mol of hydrochloric acid with a volume concentration of 10% and 0.01 mol of zinc chloride, and react at 60 °C for 12 h to obtain Intermediate 2-3, and the structural formula of Intermediate 2-3 is as follows:

[0180]

[0181] Mix Intermediate 2-3, 1 mol of methanol and 0.2 mol of triethylamine, and react at 70 °C for 6 h to obtain Compound III-2.

[0182] Example 3

[0183] Example 3 is basically the same as Example 1, except that compound III-1 is replaced by compound III-3, and the structural formula is as follows:

[0184]

[0185] The preparation method of compound III-3 includes:

[0186] Dissolve 0.1 mol of styrene and 1 mol of maleic anhydride in 500 mL of acetone solution, then add 0.01 mol of diisopropylbenzene peroxide initiator, and react at 80 °C for 6 h to obtain intermediate 3-1. The structural formula of intermediate 3-1 is as follows:

[0187]

[0188] Disperse intermediate 3-1 and 1 mol of methanol in 500 mL of butanone, then add 0.1 mol of triethylamine catalyst, and react at 80 °C for 7 h to obtain intermediate 3-2. The structural formula of intermediate 3-2 is as follows:

[0189]

[0190] Mix intermediate 3-2 and 1 mol of formaldehyde, and add 0.1 mol of hydrochloric acid with a volume concentration of 10% and 0.01 g of zinc chloride, and react at 60 °C for 12 h to obtain intermediate 3-3. The structural formula of intermediate 3-3 is as follows:

[0191]

[0192] Mix intermediate 3-3, 1 mol of and 0.2 mol of triethylamine, and react at 70 °C for 6 h to obtain compound III-3.

[0193] Example 4

[0194] Example 2 is basically the same as Example 1, except that compound III-1 is replaced by compound III-4, and the structural formula is as follows:

[0195]

[0196] The preparation method of compound III-4 includes:

[0197] Dissolve 1 mol of styrene and 1 mol of maleic anhydride in 500 mL of acetone solution, then add 0.01 mol of diisopropylbenzene peroxide initiator, and react at 80 °C for 6 h to obtain intermediate 4-1. The structural formula of intermediate 4-1 is as follows:

[0198]

[0199] Disperse intermediate 4-1 and 1 mol of methanol in 500 mL of butanone, then add 0.01 mol of triethylamine catalyst, and react at 70 °C for 6 h to obtain compound III-4.

[0200] Examples 5 to 8

[0201] The difference between Examples 5 to 8 and Example 1 lies in the different addition amounts of compound III-1.

[0202] Examples 9 to 12

[0203] The difference between Examples 9 to 12 and Example 1 lies in the different addition amounts of conductive carbon black.

[0204] Example 13

[0205] The difference between Example 13 and Example 1 lies in that the binder is made of polyacrylic acid and the addition amount of the binder is different.

[0206] Example 14

[0207] The difference between Example 14 and Example 1 lies in that the conductive carbon is Ketjenblack and the addition amount of the binder is different.

[0208] Comparative Example 1

[0209] The difference between Comparative Example 1 and Example 1 lies in that compound III-1 is not added.

[0210] The viscosities of the positive electrode active pastes provided in Examples 1 to 14 and Comparative Example 1 were respectively detected, and the performances of the positive electrode plates and the batteries are shown in Table 1. Among them, the detection method is as follows:

[0211] (1) Viscosity of positive electrode active paste / mPa·s

[0212] After preparing the positive electrode active paste, measure its viscosity at room temperature of 25 °C using a Brookfield viscometer, and then measure its viscosity after standing for 5 h, 10 h, 15 h, 20 h, and 25 h respectively.

[0213] Among them, the viscosity change diagrams of the positive electrode active pastes provided in Example 1 and Comparative Example 1 after standing for different times are as Figure 5 , from Figure 5 It can be seen that after standing for 25 h, the positive electrode active paste provided in Example 1 of the present application has a smaller viscosity change value (the standing viscosity of Comparative Example 1 is reduced from 23500 mPa·s to the standing viscosity of Example 1 of 14800 mPa·s), indicating that the stability of the positive electrode active paste is better.

[0214] (2) Positive electrode sheet resistance / Ω

[0215] Use an ACCFILM, G2R type film resistance meter to measure the resistance values of the positive electrode sheet and the blank positive electrode sheet.

[0216] Among them, the resistances of the positive electrode sheets provided in Example 1 and Comparative Example 1 are as Figure 6 , from Figure 6 It can be seen that when the same conductive carbon black is added, the resistance of the positive electrode sheet in Example 1 is smaller (the resistance of the electrode sheet in Comparative Example 1 is 0.39 Ω, and after adding Compound III-1, the resistance of the electrode sheet in Example 1 obtained is 0.26 Ω, a decrease of 0.13 Ω), indicating that the dispersion effect of the conductive carbon black in Example 1 is better.

[0217] (3) Cracking test

[0218] Apply different pressures to the wound electrode assembly prepared in the example, hot press for 120 s, disassemble, observe the inner ring cracking condition of the positive electrode sheet of the electrode assembly, and detect the compaction density of the positive electrode sheet after hot pressing to determine the value of the critical compaction density when the inner ring does not crack.

[0219] The compaction density of the electrode sheet has the meaning well-known in the art. For the positive electrode sheet, reference can be made specifically to the national standard GB / T39864-2021 "Test Method for Initial Discharge Specific Capacity and Initial Charge-Discharge Efficiency of Lithium Manganese Oxide for Lithium-Ion Battery Cathode Materials" or GB / T 42161-2022 "Test Method for Electrochemical Performance of Lithium Iron Phosphate - Initial Discharge Specific Capacity and Initial Charge-Discharge Efficiency".

[0220] The specific test steps include: obtaining a battery electrode sheet meeting the processability requirements, using a stamping machine to punch out a positive electrode sheet with a diameter of 14 mm, and using an electronic balance and a desktop digital thickness gauge to measure the mass m c , thickness d c of the positive electrode sheet respectively; using a punching machine to punch out a sufficient number of aluminum foil substrates with a diameter of 14 mm, and using an electronic balance and a desktop digital thickness gauge to measure the mass m Al , thickness d Al of the aluminum foil substrate respectively.

[0221] Positive electrode sheet compaction density

[0222] In the formula:

[0223] ρ c is the positive electrode sheet compaction density, with the unit of grams per cubic centimeter (g / cm3);

[0224] m c is the positive electrode sheet mass, with the unit of grams (g);

[0225] m Al is the mass of the aluminum foil substrate, in grams (g);

[0226] is the diameter of the positive electrode sheet, in millimeters (mm);

[0227] d c is the thickness of the positive electrode sheet, in micrometers (μm);

[0228] d Al is the thickness of the aluminum foil substrate, in micrometers (μm).

[0229] The camera - taken photos of the cracking conditions of the positive electrode sheets provided in Example 1 and Comparative Example 1 are as shown in Figure 7 (hot - pressed for 120 s under 7T pressure), from Figure 7 it can be seen that the positive electrode sheet provided in Example 1 did not crack ( Figure 7 Figure B in Figure 7 ), and the positive electrode sheet provided in Comparative Example 1 cracked (

[0230] (4) Battery kinetics test

[0231] The discharge DCR (technical DC impedance) of the batteries provided in Example 1 and Comparative Example 1 was tested at different states of charge (SOC) and different temperatures. The specific process is as follows:

[0232] 20% SOC DC resistance test:

[0233] For each of the above - prepared batteries, they were respectively left standing for 30 minutes in a constant - temperature environment of 25°C, discharged at a constant current of 0.33C to 2.8V, left standing for 30 minutes, charged at a constant current of 0.33C to 4.25V, then charged at a constant voltage with a cut - off current of 0.05C, then left standing for 30 minutes, then discharged at 0.33C to 2.8V, the discharge capacity C0 was recorded, left standing for 30 minutes, charged at a constant current of 0.33C to 4.25V, then charged at a constant voltage with a cut - off current of 0.05C, then left standing for 5 minutes, then discharged at 0.33C with a cut - off current of 0.5C0, left standing for 1 hour, the voltage U1 at this time was recorded, discharged at a current of I = 5C for 30 seconds (5c represents the magnitude of the discharge current, for example, for a battery with a capacity of 2ah, 5c means discharging at 10a), the voltage U2 at this time was recorded, and then left standing for 5 minutes. The DCR resistance value = (U1 - U2) / I.

[0234] 50% SOC DC Resistance Test: For each of the batteries prepared above, they were left standing for 30 minutes in a constant temperature environment of 25°C, then discharged at a constant current of 0.33C until 2.8V, left standing for 30 minutes, charged at a constant current of 0.33C until 4.25V, then charged at a constant voltage with a cut-off current of 0.05C, and then left standing for 30 minutes. Then they were discharged at 0.33C until 2.8V, and the discharge capacity C0 was recorded. After standing for 30 minutes, they were charged at a constant current of 0.33C until 4.25V, then charged at a constant voltage with a cut-off current of 0.05C, and then left standing for 5 minutes. They were discharged at 0.33C with a cut-off current of 0.5C0, left standing for 1 hour, and the voltage U1 at this time was recorded. They were discharged at a current of I = 5C for 30 seconds, and the voltage U2 at this time was recorded. Then they were left standing for 5 minutes. The DCR resistance value = (U1 - U2) / I.

[0235] Among them, at 25°C, the discharge DCR-SOC curves of the batteries provided in Example 1 and Comparative Example 1 at different states of charge (SOC) are as Figure 8 shown; at -25°C, the discharge DCR-SOC curves of the batteries provided in Example 1 and Comparative Example 1 at different states of charge (SOC) are as Figure 9 shown. From Figure 8 and Figure 9 it can be seen that: at different temperatures, there is no obvious difference in the DCR-SOC curves of the two, indicating that the addition of the compound additive will not have a negative impact on the resistance of the electrode sheet.

[0236] (5) Cycle Performance Test

[0237] At 25°C, the batteries provided in Example 1 and Comparative Example 1 were repeatedly charged and discharged, and the capacitance retention rate (capacity) after n cycles (cycle) of charge and discharge was calculated. The cycle performance test is as follows:

[0238] At 25°C, the batteries prepared above were charged at a constant current of 1C to the charging cut-off voltage of 4.25V, then charged at a constant voltage until the current ≤ 0.05C, left standing for 5 min, and then discharged at a constant current of 0.33C to the discharge cut-off voltage of 2.8V, left standing for 5 min. This is one charge-discharge cycle. The batteries were subjected to charge-discharge cycle tests according to this method for 500 cycles, and the discharge capacity of each cycle was recorded.) Figure 10 is the cycle performance graph of the batteries provided in Example 1 and Comparative Example 1. From Figure 10 it can be seen that the batteries provided in Example 1 and Comparative Example 1 were cycled 500 cycles at 25°C, and their capacity retention rates were basically the same, indicating that the addition of the compound additive basically does not affect the cycle performance of the battery.

[0239] Table 1 Parameters and Performance of the Batteries

[0240]

[0241]

[0242] As can be seen from Table 1, compared with Comparative Example 1, in Examples 1 to 14 of the present application, the addition of the compound additive can reduce the resistance of the electrode sheet, increase the flexibility of the electrode sheet, improve the processing performance of the electrode sheet, and thus improve the energy density of the battery.

[0243] As can be seen from the comparison between Examples 1 to 4, the structural formula of the compound additive is III-1 (with an ether chain connected to the ester group), which can further improve the processing performance of the electrode sheet to improve the energy density of the battery.

[0244] As can be seen from the comparison between Example 1 and Examples 5 to 8, when the mass ratio of the compound additive is 0.2% to 1% (the addition amount is small), it can better play the role of dispersing conductive carbon, making the resistance of the electrode sheet small, and the electrode sheet is not easy to crack, and the processing performance is good.

[0245] As can be seen from the comparison between Example 1 and Examples 9 to 12, in the case of having the compound additive, the dispersion effect of the conductive carbon is good, and when the addition amount of the conductive carbon is small (the mass ratio is 1% to 3%), it can achieve a good effect of reducing the resistance of the electrode sheet. From the comparison between Comparative Example 1 and Example 10, it can be known that the addition amount of conductive carbon black in Comparative Example 1 is 2%, and the addition amount of conductive carbon black in Example 10 is 1%. However, the film resistance value of Example 10 is 0.36 Ω, and the film resistance value of Comparative Example 1 is 0.39 Ω. Compared with Comparative Example 1, the addition amount of conductive carbon black in Example 10 is reduced by half, but the film resistance value still has a small decrease, and the conductive effect is better, indicating that the addition of the compound additive III-1 can make the conductive carbon black have a good dispersion effect to increase the conductivity of the film.

[0246] The above-described embodiments are some embodiments of the present application, rather than all embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application claimed, but merely represents the selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.

Claims

1. A compound, characterized in that, The structural formula of the said compound is as shown in formula (I): Wherein, n is a positive integer, and each of R1 and R2 independently includes one or more of alkyl, ether, and ester; R3 includes a cyclic group, and the said cyclic group includes one or more of pyrrole, furan, thiophene, phenyl, pyridine, indole, benzothiazole, isoindole, isobenzofuran, pyrazole, imidazole, indazole, quinoline, and pyrimidine.

2. The compound according to claim 1, wherein The structural formula of the said compound is as shown in formula (II): Wherein, each of R1 and R2 independently is selected from substituted or unsubstituted methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester, or carbonate; R4 is none, substituted or unsubstituted methylene or ethylene; R5 is selected from H, substituted or unsubstituted methyl, ethyl, alkyl ether, or polyether segment.

3. The compound according to claim 2, characterized in that, The structural formula of the said compound is as shown in formula (III): Wherein, both R1 and R2 are selected from substituted or unsubstituted methyl, ethyl, propyl, isopropyl, phosphate ester, chain ester, chain alcohol ester, or carbonate; R5 is selected from H, substituted or unsubstituted methyl, ethyl, alkyl ether, or polyether segment.

4. The compound according to any one of claims 1 to 3, characterized in that, Both R1 and R2 are selected from substituted or unsubstituted methyl, ethyl, phosphate ester, chain ester, chain alcohol ester, or carbonate; R5 is selected from H, substituted or unsubstituted methyl, ethyl, alkyl ether, or polyether segment.

5. The compound according to claim 4, characterized in that, Both R1 and R2 are selected from substituted or unsubstituted methyl, ethyl, phosphate ester, C2-C10 chain ester containing one ester group, C5-C15 chain ester containing two ester groups, C2-C10 chain alcohol ester containing one ester group, C5-C15 chain alcohol ester containing two ester groups, or carbonate; R5 is selected from H, substituted or unsubstituted methyl, ethyl, C2-C10 chain ether, or polyether segment with a molecular weight range of 20-500.

6. The compound according to claim 5, characterized in that, Both R1 and R2 are selected from methyl, ethyl, C2-C10 chain ester containing one ester group, or C5-C15 chain ester containing two ester groups; R5 is selected from H, methyl, ethyl, or C2-C10 chain ether.

7. The compound according to any one of claims 1 to 6, characterized in that, The structural formula of the said compound is as follows:

8. An electrode sheet, characterized in that, The said electrode sheet includes an active material layer, the active material layer includes conductive carbon, binder, and additive, and the said additive includes the compound according to any one of claims 1-7.

9. The electrode sheet according to claim 8, wherein, The said electrode sheet satisfies one or more of the following conditions: (a) The mass ratio of the said compound in the active material layer is 0.01% - 2%; (b) The mass ratio of the conductive carbon in the active material layer is 0.5% - 5%; (c) The mass ratio of the binder in the active material layer is 0.1% - 4%.

10. The electrode sheet according to claim 9, characterized in that, The said electrode sheet satisfies one or more of the following conditions: (d) The mass ratio of the said compound in the active material layer is 0.2% - 1%; (e) The mass ratio of the conductive carbon in the active material layer is 1% - 3%; (f) The mass ratio of the binder in the active material layer is 0.5% - 2%.

11. The electrode sheet according to any one of claims 8 to 10, characterized in that, The said electrode sheet satisfies one or more of the following conditions: (g) The conductive carbon includes at least one of conductive carbon black, carbon fiber, carbon nanotube, Ketjen black, graphene, and acetylene black; (h) The binder includes at least one of polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyacrylic acid, polymethacrylic acid, and sodium polyacrylate; (i) The binder includes polyvinylidene fluoride or / and polyacrylic acid.

12. A battery, characterized in that, It includes the electrode sheet according to any one of claims 8 to 11.

13. An electrical device, characterized in that, It includes the battery according to claim 12.

14. A method for preparing a compound, characterized in that, It includes the following steps: Wherein, R1 includes one or more of alkyl, ether, and ester; R3 includes a cyclic group, and the cyclic group includes one or more of pyrrole, furan, thiophene, phenyl, pyridine, indole, benzothiazole, isoindole, isobenzofuran, pyrazole, imidazole, indazole, quinoline, and pyrimidine.

15. The preparation method according to claim 14, wherein, It includes the following steps: Wherein, R1 is selected from substituted or unsubstituted methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester, or carbonate; R4 is none, substituted or unsubstituted methylene or ethyl.

16. The preparation method according to claim 15, characterized in that, The preparation method further includes: Wherein, X is H, methyl, alkyl ether, or polyether segment.

17. The preparation method according to claim 14, wherein It includes the following steps: Wherein, R is selected from methyl, ethyl, propyl, isopropyl, alkyl ether, polyether segment, phosphate ester, chain ester, chain alcohol ester, or carbonate.

18. The preparation method according to claim 17, wherein, The preparation method further includes: Wherein, X is H, methyl, alkyl ether, or polyether segment.

19. The preparation method according to any one of claims 14 to 17, characterized in that, The initiator includes dicumyl peroxide or / and benzoyl peroxide.

20. The preparation method according to any one of claims 14 to 16, characterized in that, The catalyst includes at least one of triethylamine, sodium hydroxide, and potassium hydroxide.

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