Negative electrode sheet, preparation method therefor, secondary battery and electrical apparatus

Abstract

A negative electrode sheet, a preparation method therefor, a secondary battery and an electrical apparatus. The negative electrode sheet comprises a negative electrode active material layer, the negative electrode active material layer containing an additive, and the additive comprising a compound containing carbon-carbon double bonds and lithium sulfonate groups or sodium sulfonate groups. In the preparation process for a battery negative electrode paste, the additive containing carbon-carbon double bond and lithium silicate or sodium silicate is added. By means of in-situ electrochemical polymerization technology, the additive can polymerize an ultrathin polymer film protection layer on the surface of a graphite negative electrode, finally remarkably improving the overall performance of the negative electrode sheet and even a battery.

Description

Negative electrode sheet, preparation method thereof, secondary battery and electric device

[0001] Related applications

[0002] The present application claims priority to the Chinese patent application No. 2024105713329, filed on May 9, 2024, and entitled "Negative electrode sheet, preparation method thereof, secondary battery and electric device", the contents of which are hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of secondary batteries, and in particular to a negative electrode sheet, a preparation method thereof, a secondary battery and an electric device. BACKGROUND

[0004] The statements herein are provided only to complement what is in the application and are not necessarily to constitute the prior art.

[0005] Secondary batteries are widely used in various consumer electronic products, electric vehicles, aerospace, large-scale energy storage and other fields due to their light weight, no pollution, no memory effect and other outstanding characteristics. Graphite is the most commonly used negative active material for secondary batteries, which has the advantages of abundant raw materials, low cost, low working potential (0.01 V vs. Li + / Li), good cycle performance, etc.

[0006] During the first charge and discharge process of the battery, the electrolyte will undergo a reduction decomposition reaction on the surface of the graphite negative electrode, thereby forming a solid electrolyte interface (SEI) film on the surface of the graphite. The ideal SEI film should be able to passivate the surface of the graphite negative electrode and effectively prevent the electrolyte from continuing to react on the surface of the graphite negative electrode; at the same time, the SEI film should have excellent ion conductivity and electronic insulation capacity. However, in actual situations, the graphite negative electrode will undergo a certain degree of volume expansion during lithium intercalation, causing the SEI film to break and expose new active sites, thereby causing the electrolyte to continue to decompose, resulting in continuous increase in the thickness of the SEI film and the increase in the internal resistance of the battery, ultimately leading to the capacity attenuation and cycle performance degradation of the battery.

[0007] SUMMARY

[0008] The present application provides a negative electrode sheet, a preparation method thereof, a secondary battery and an electric device which can effectively improve the cycle performance while taking into account the capacity.

[0009] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a negative electrode sheet, comprising a negative active material layer, wherein the negative active material layer comprises an additive, and the additive comprises a compound containing a carbon-carbon double bond and a sulfonate group, and the sulfonate group comprises one of a lithium sulfonate group and a sodium sulfonate group.

[0010] Therefore, the application sets the additive in the negative active material layer of the negative electrode sheet, and the additive includes a compound containing a carbon-carbon double bond and a sulfonate group, and the sulfonate group includes a lithium sulfonate group or a sodium sulfonate group. Due to the carbon-carbon double bond, the additive can preferentially undergo electropolymerization on the surface of the negative active material at a lower potential during the battery cycle, and an ultrathin polymer film layer is generated in situ, thereby effectively reducing or even avoiding the problems of the rupture of the SEI film, the exposure of new active sites, the continuous decomposition of the electrolyte, and the continuous increase of the SEI film thickness and the battery internal resistance caused by the volume expansion of the negative active material during the battery charge and discharge cycle. At the same time, the polymer film generated by the polymerization of the additive has good mechanical strength and toughness, thereby effectively protecting the stability of the negative active material. Therefore, the negative electrode sheet provided by the application has excellent cycle performance while considering the capacity. In addition, the lithium ion or sodium ion can be transmitted due to the lithium sulfonate group or sodium sulfonate group in the additive, so that the polymer film generated by the polymerization of the additive can protect the negative active material while improving its electrochemical performance, and finally improve the comprehensive performance of the battery.

[0011] In some embodiments of the application, the additive includes a compound having a structure shown in the following formula (I):

[0012] wherein the M element includes one of Li and Na.

[0013] In some embodiments of the application, the M element is Li, and the additive includes a lithium allyl phenyl ether sulfonate.

[0014] In some embodiments of the application, the additive includes one or more of a 2-allyl phenyl ether lithium sulfonate, a 3-allyl phenyl ether lithium sulfonate, and a 4-allyl phenyl ether lithium sulfonate.

[0015] In some embodiments of the application, the M element is Na, and the additive includes a sodium allyl phenyl ether sulfonate.

[0016] In some embodiments of the application, the additive includes one or more of a 2-allyl phenyl ether sodium sulfonate, a 3-allyl phenyl ether sodium sulfonate, and a 4-allyl phenyl ether sodium sulfonate.

[0017] In some embodiments of the application, the mass ratio of the additive in the negative active material layer is 0.5%-3%.

[0018] In some embodiments of the application, the negative active material layer further includes one or more of a negative active material, a conductive agent, and a binder.

[0019] In some embodiments of the present application, the negative active material comprises a carbon-based material.

[0020] In some embodiments of the present application, the negative active material comprises one or more of natural graphite, artificial graphite, and mesocarbon microbeads.

[0021] In some embodiments of the present application, the mass percentage of the negative active material in the negative active material layer is 94%-98%.

[0022] In some embodiments of the present application, the mass percentage of the conductive agent in the negative active material layer is 0.5%-3%.

[0023] In some embodiments of the present application, the mass percentage of the binder in the negative active material layer is 1%-3%.

[0024] A second aspect of the present application provides a preparation method of the negative electrode sheet of the first aspect of the present application, the preparation method comprising a step of preparing a negative electrode slurry for forming the negative active material layer, the negative electrode slurry comprising the additive.

[0025] In some embodiments of the present application, the additive comprises sodium allyl phenyl ether sulfonate, and a preparation method of the sodium allyl phenyl ether sulfonate comprises:

[0026] In a protective atmosphere, sodium hydroxybenzenesulfonate, sodium methoxide, and methanol are mixed to prepare a mixed solution;

[0027] After the protective gas is introduced into the mixed solution, allyl bromide is added to perform a first reaction to prepare the sodium allyl phenyl ether sulfonate.

[0028] In some embodiments of the present application, the sodium hydroxybenzenesulfonate comprises one or more of sodium 2-hydroxybenzenesulfonate, sodium 3-hydroxybenzenesulfonate, and sodium 4-hydroxybenzenesulfonate.

[0029] In some embodiments of the present application, the molar ratio of the sodium hydroxybenzenesulfonate to the sodium methoxide is 1:(2-6).

[0030] In some embodiments of the present application, the molar ratio of the sodium hydroxybenzenesulfonate to the sodium methoxide is 1:(2-3).

[0031] In some embodiments of the present application, the molar ratio of the sodium methoxide to the methanol is 1:(6-12).

[0032] In some embodiments of the present application, the molar ratio of the sodium methoxide to the methanol is 1:(6-8).

[0033] In some embodiments of the present application, the molar ratio of the allyl bromide and the sodium hydroxybenzenesulfonate is (2-6): 1.

[0034] In some embodiments of the present application, the molar ratio of the allyl bromide and the sodium hydroxybenzenesulfonate is (2-3): 1.

[0035] In some embodiments of the present application, the temperature of the first reaction is 70-80°C.

[0036] In some embodiments of the present application, the time of the first reaction is 1-10h.

[0037] In some embodiments of the present application, the time of the first reaction is 2-5h.

[0038] In some embodiments of the present application, the additive comprises lithium allyl phenyl ether sulfonate, and a preparation method of the lithium allyl phenyl ether sulfonate comprises:

[0039] Preparation of sodium allyl phenyl ether sulfonate by using the above-mentioned method for preparing sodium allyl phenyl ether sulfonate;

[0040] Mixing the sodium allyl phenyl ether sulfonate with an aqueous solution containing a lithium salt, and performing a second reaction to prepare the lithium allyl phenyl ether sulfonate.

[0041] In some embodiments of the present application, the molar ratio of the sodium allyl phenyl ether sulfonate and the lithium salt is 1:(1-5).

[0042] In some embodiments of the present application, the molar ratio of the sodium allyl phenyl ether sulfonate and the lithium salt is 1:(2-3).

[0043] In some embodiments of the present application, the lithium salt comprises one or more of LiCl, LiBr, Li2SO4, LiNO3, Li2CO3 and Li3PO4.

[0044] In some embodiments of the present application, the concentration of the aqueous solution containing the lithium salt is 1-6mol / L.

[0045] In some embodiments of the present application, the concentration of the aqueous solution containing the lithium salt is 1-2mol / L.

[0046] In some embodiments of the present application, the temperature of the second reaction is 60-100°C.

[0047] In some embodiments of the present application, the temperature of the second reaction is 70-90°C.

[0048] In some embodiments of the present application, the second reaction is performed for 12-24 hours.

[0049] The third aspect of the present application provides a secondary battery comprising the negative electrode tab of the first aspect of the present application or the negative electrode tab prepared by the preparation method of the second aspect of the present application.

[0050] The secondary battery of the present application comprises the negative electrode tab of the present application, and has excellent cycle performance while the capacity is taken into account.

[0051] In some embodiments of the present application, the secondary battery is a lithium ion battery.

[0052] In some embodiments of the present application, the secondary battery is a sodium ion battery.

[0053] The fourth aspect of the present application provides a power-using device comprising the secondary battery of the third aspect of the present application. The power-using device of the present application comprises the secondary battery provided by the present application, and thus has at least the same advantages as the secondary battery.

[0054] The details of one or more embodiments of the present application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the present application will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF DRAWINGS

[0055] To better describe and illustrate the embodiments or examples provided by the present application, one or more drawings can be referred to. Additional details or examples used to describe the drawings should not be considered as limiting the scope of the disclosed application, the presently described embodiments or examples, and any one of the best modes of these applications presently understood. Moreover, the same reference numbers are used to represent the same components throughout the drawings. In the drawings:

[0056] FIG. 1 is a principle of electro-polymerization of a compound having a structure as shown in formula (I).

[0057] FIG. 2 is a schematic diagram of a battery cell according to an embodiment of the present application.

[0058] FIG. 3 is an exploded view of the battery cell according to an embodiment of the present application shown in FIG. 2.

[0059] FIG. 4 is a schematic diagram of a battery module according to an embodiment of the present application.

[0060] FIG. 5 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0061] FIG. 6 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 5.

[0062] FIG. 7 is a schematic diagram of a power-using device using the secondary battery according to an embodiment of the present application as a power source.

[0063] Figure 8 is a nuclear magnetic resonance spectrum of lithium 4-allyl phenyl ether sulfonate prepared in Example 1.

[0064] Figure 9 is an infrared spectrum of graphite and lithium 4-allyl phenyl ether sulfonate electro-polymerized on graphite prepared in Example 1.

[0065] Figure 10 is the first cycle charge-discharge curve of the electrode prepared in Examples 1-3 and Comparative Example 1 in a battery.

[0066] Figure 11 is a TEM image of the electrode prepared in Examples 1 and Comparative Example 1 after battery cycle test.

[0067] Figure 12 is the cycle stability test results of the electrode prepared in Examples 1 and Comparative Example 1 in a battery.

[0068] Figure 13 is the change of DCR with cycle number during the battery cycle of the electrode prepared in Examples 1 and Comparative Example 1.

[0069] BRIEF DESCRIPTION OF DRAWINGS DETAILED DESCRIPTION

[0070] Hereinafter, some embodiments of the modified negative electrode material and the preparation method thereof, the negative electrode, the secondary battery, and the electric device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed descriptions are omitted. For example, there will be cases where detailed descriptions of matters known well, repetitive descriptions of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0071] "ranges" disclosed herein can be defined, for example, by the lower and upper values. Any lower limit can independently be combined with any upper limit to define a range of any value. For example, if a range of 60-120 and 80-110 is listed as exemplary, it is understood that a range of 60-110 and 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and 2 is listed, and if a maximum range value of 3, 4, and 5 is also listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, the use of "a" or "an" to describe a singular entity includes the meaning of "one", unless otherwise indicated. In this application, the use of "comprising" means "including, but not limited to". In this application, the use of "based on" means "based, at least in part, on". In this application, the use of "optionally" means "may be selected from the group consisting of optionally and necessarily" and similarly "optionally" each occurrence describes a group including at least one member, which can be selected from the group consisting of optionally and necessarily. In this application, the use of "including" does not exclude the presence of additional information. In this application, the use of "when" indicates "upon or upon detection of, and / or when a condition is met". In this application, the use of "about" indicates that a value can vary from the stated value by a reasonable amount, or by an amount that would not make a significant difference to one of ordinary skill in the art. Non-limiting examples of the amount that would not make a significant difference to one of ordinary skill in the art include 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, and 99%. In this application, the use of "a number of" means "one or more than one", unless otherwise indicated. In this application, the use of "at least one of' means "one or more than one", unless otherwise indicated. In this application, the use of "one or more of" means "one or more than one", unless otherwise indicated. In this application, the use of "or" means "and / or" unless otherwise indicated. In this application, the use of "based on" means "based, at least in part, on". In this application, the use of "comprising" means "including, but not limited to". In this application, the use of "consisting essentially of means "including, but not limited to, and not including an excluded member that can affect a basic or novel characteristic" of the compositions or processes claimed. In this application, the use of "consisting of means "including, and limited to, whatever follows the consist of autonomously. In this application, unless otherwise indicated, a value range "a-b" represents a shorthand manner of describing any integer combination of the range between a and b, where a and b are both real numbers. For example, the value range "0-5" represents that all real numbers between "0-5" have been listed herein, and "0-5" is just a shorthand manner of describing these value combinations. In addition, when it is stated that a parameter is an integer ≥2, it is equivalent to listing the parameter as, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when it is stated that a parameter is an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0072] In this application, the use of "a plurality" or "a plurality of" means "two or more than two", unless otherwise indicated.

[0073] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0074] In this document, reference to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment or implementation of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. It is explicitly contemplated that embodiments described herein can be combined with other embodiments. In this document, reference to "implementation" has a similar meaning.

[0075] Those skilled in the art can understand that the order of writing each step in the method of each embodiment or example does not mean a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. If not specifically stated, all steps of the present application can be performed in sequence or randomly, preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method can also comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0076] In the present application, the open technical features or technical solutions described with the words "containing", "including", "comprising" and the like do not exclude additional members other than the listed members, and can be regarded as providing both the closed features or solutions composed of the listed members and the open features or solutions including additional members other than the listed members. For example, A includes a1, a2 and a3, and unless otherwise specified, it can also include other members or can not include additional members, and can be regarded as providing the feature or solution that "A is composed of a1, a2 and a3", and also providing the feature or solution that "A includes a1, a2 and a3, and also includes other members". In the present application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0077] In the present application, "optionally", "optional" and "optional" mean that it can or can not exist, that is, it means to choose either of the two parallel solutions "yes" or "no". If there are multiple "options" in a technical solution, unless otherwise specified, and there is no contradiction or mutual restriction, each "option" is independent.

[0078] The secondary battery using a graphite negative electrode has problems of capacity attenuation and cycle performance degradation during charge and discharge cycles.

[0079] In the related art, the improvement methods mainly include: (1) material surface coating: amorphous carbon, metal or non-metal and its oxide, etc. are coated on the surface of graphite. Although the coating layer has good strength and stability, due to the brittleness of the inorganic coating layer, it cannot well limit the volume change of the graphite material in the charging and discharging process, which easily leads to the breakage and peeling of the inorganic coating layer, so that the coated graphite material cannot be actually applied. (2) Element doping: by doping heteroatoms into graphite, the electronic structure and surface properties of graphite can be changed, so that the chemical reaction activity of graphite material can be improved. However, the preparation process of this doping is relatively complex, the manufacturing cost is high, and it also brings environmental pollution, safety hazards and other problems. (3) Electrolyte functional additive: by adding a small amount of additives such as vinylene carbonate in the electrolyte, it can decompose on the surface of graphite to form SEI film during the battery cycle, and then protect the graphite negative electrode material. Although the formation of SEI film can help to passivate the surface of graphite, the residual additives in the battery will cause the continuous growth of the SEI film on the surface of graphite, which will cause the internal resistance of the battery to rise, and then affect the long-term stability of the battery. In addition, due to the small or insoluble solubility of many types of functional additives in the electrolyte solvent, the selection of the type of functional additive is restricted to some extent, which leads to high manufacturing and using cost.

[0080] Based on the above problems, in the preparation of the negative electrode sheet, an additive containing carbon-carbon double bond and lithium silicate or sodium silicate is added in the preparation process of the battery negative electrode slurry. By using the technology of in-situ electrochemical polymerization, the additive can polymerize a layer of ultra-thin polymer film protective layer on the surface of the graphite negative electrode, which can significantly improve the comprehensive performance of the negative electrode sheet and the battery.

[0081] The embodiment of the present application provides a negative electrode sheet, which comprises a negative electrode active material layer, and the negative electrode active material layer comprises an additive, and the additive comprises a compound containing carbon-carbon double bond and sulfonate group, and the sulfonate group comprises one of lithium sulfonate group and sodium sulfonate group.

[0082] Understandably, by arranging the additive in the negative active material layer of the negative electrode sheet, and the additive comprises a compound containing a carbon-carbon double bond and a sulfonate group, the sulfonate group comprises a lithium sulfonate group or a sodium sulfonate group; due to the carbon-carbon double bond, during the battery cycle, the additive can preferentially undergo electropolymerization on the surface of the negative active material at a lower potential, generating an ultra-thin polymer film layer in situ, thereby effectively reducing or even avoiding the exposure of new active sites due to the rupture of the SEI film caused by the volume expansion of the negative active material during the battery charge and discharge cycle, the continuous decomposition of the electrolyte, and the resulting problems of the increasing thickness of the SEI film, the increasing of the battery internal resistance and other problems; at the same time, the polymer film generated by the polymerization of the additive has good mechanical strength and toughness, thereby effectively protecting the stability of the negative active material; therefore, the negative electrode sheet provided by the present application has excellent cycle performance while considering the capacity. In addition, due to the lithium sulfonate group or the sodium sulfonate group contained in the additive, lithium ions or sodium ions can be transmitted, so that the polymer film generated by the polymerization of the additive can protect the negative active material while improving its electrochemical performance, and ultimately improve the comprehensive performance of the battery.

[0083] As an example, the type of the above-mentioned additive and the contained functional groups can be determined by nuclear magnetic resonance method and infrared spectrophotometry.

[0084] In some embodiments, the additive comprises a compound having a structure as shown in the following formula (I):

[0085] Wherein, the M element comprises one of Li and Na.

[0086] The electropolymerization principle of the compound having a structure as shown in formula (I) is shown in FIG. 1. As can be seen from FIG. 1, the additive can generate a polymer film layer in situ through electropolymerization.

[0087] In some exemplary embodiments, the M element is Li, and the additive comprises a lithium allyl phenyl ether sulfonate. Thus, the additive can be used in a lithium ion battery.

[0088] In some alternative embodiments, the additive comprises one or more of a 2-allyl phenyl ether lithium sulfonate, a 3-allyl phenyl ether lithium sulfonate, and a 4-allyl phenyl ether lithium sulfonate.

[0089] In some of the embodiments, the M element is Na, and the additive comprises a sodium allyl phenyl ether sulfonate. Thus, the additive can be used in a sodium ion battery.

[0090] In some alternative embodiments, the additive comprises one or more of a 2-allyl phenyl ether sodium sulfonate, a 3-allyl phenyl ether sodium sulfonate, and a 4-allyl phenyl ether sodium sulfonate.

[0091] As one possible implementation, the additive can have a mass percentage in the negative active material layer of 0.5% to 3%; for example, the additive can have a mass percentage in the negative active material layer of 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, or a range between any two of the foregoing values. When the additive has a mass percentage in the negative active material layer within the foregoing range, the additive can form a sufficient polymer film to protect the surface of the negative electrode while not increasing the cycle DCR of the battery and degrading the performance of the battery.

[0092] As an example, the mass percentage of the additive in the negative active material layer mentioned above can be determined by inductively coupled plasma (ICP) to measure the content of element S, and then the content of the additive can be deduced.

[0093] In some embodiments, the negative active material layer further comprises one or more of a negative active material, a conductive agent, and a binder.

[0094] As one possible implementation, the negative active material comprises a carbon-based material.

[0095] In some alternative embodiments, the negative active material comprises one or more of natural graphite, artificial graphite, and mesocarbon microbeads.

[0096] In some embodiments, the negative active material can also comprise a negative active material known in the art for use in batteries. As non-limiting examples, the negative active material can comprise one or more of a silicon-based material, a tin-based material, and lithium titanate, etc. The silicon-based material can comprise one or more of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can comprise one or more of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as negative active materials for batteries can also be used. These negative active materials can be used alone or in combination with two or more.

[0097] In some alternative embodiments, the negative active material can have a mass percentage in the negative active material layer of 94% to 98%; as an example, the negative active material can have a mass percentage in the negative active material layer of 94%, 95%, 96%, 97%, 98%, or a range between any two of the foregoing values, etc.

[0098] In some optional embodiments, the mass percentage of the conductive agent in the negative active material layer is 0.5%-3%. For example, the mass percentage of the conductive agent in the negative active material layer can be, but is not limited to, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.7%, 2%, 2.3%, 2.5%, 2.7%, 3%, or a range between any two of the above values, etc.

[0099] In some embodiments, the conductive agent can include one or more of conductive carbon black, super conductive carbon black, conductive graphite, acetylene black, ketjen black, graphene, and carbon nanotube.

[0100] In some embodiments, the mass percentage of the binder in the negative active material layer is 1%-3%. For example, the mass percentage of the binder in the negative active material layer can be, but is not limited to, 1%, 1.3%, 1.5%, 1.7%, 2%, 2.3%, 2.5%, 2.7%, 3%, or a range between any two of the above values, etc.

[0101] In some embodiments, the binder includes one or more of polytetrafluoroethylene, polyvinylidene fluoride, polyacrylic acid, polyimide, and polyacrylonitrile. The binder can also optionally include one or more of sodium polyacrylate (PAAS), polyacrylamide (PAM), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0102] In some embodiments, the negative active material layer includes, in mass percentage, 94%-98% of the negative active material, 0.5%-3% of the conductive agent, 1%-3% of the binder, and 0.5%-3% of the additive.

[0103] In some embodiments, the negative active material layer can also optionally include other auxiliary agents, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), etc.

[0104] The negative electrode sheet also includes a negative current collector, and the negative active material layer is located on at least one side of the negative current collector. As a non-limiting example, the negative current collector has two surfaces opposite in its own thickness direction, and the negative active material layer is disposed on either one or both of the two opposite surfaces of the negative current collector.

[0105] In some embodiments, the negative current collector can employ a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base. The composite current collector can be obtained by forming a metal material on a polymer material base. Non-limiting examples of the metal material in the negative current collector can include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, and the like. Non-limiting examples of the polymer material base in the negative current collector can include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and the like.

[0106] Embodiments of the present application provide a method for preparing a negative electrode tab, which can be used to prepare the aforementioned negative electrode tab. The method includes a step of preparing a negative electrode slurry for forming a negative electrode active material layer, the negative electrode slurry comprising the additive.

[0107] Understandably, in the preparation process of the battery negative electrode slurry, the additive containing carbon-carbon double bond and lithium silicate or sodium silicate is added, and by using the technology of in-situ electrochemical polymerization, the additive can be polymerized on the surface of the graphite negative electrode to form an ultra-thin polymer film protective layer, thereby significantly improving the comprehensive performance of the negative electrode tab and the battery.

[0108] In some embodiments, the negative electrode tab can be prepared by dispersing components for preparing the negative electrode tab, such as a negative electrode active material, a conductive agent, a binder, and an additive, in a solvent (non-limiting examples of the solvent include deionized water) to form a negative electrode slurry; coating the negative electrode slurry on at least one side surface of the negative electrode current collector, and after drying, cold pressing, and the like, the negative electrode tab can be obtained. The surface of the negative electrode current collector coated with the negative electrode slurry can be on a single surface of the negative electrode current collector, or on both surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 40wt%-60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000mPa·s-10000mPa·s. When coating the negative electrode slurry, the coating unit area density (excluding the solvent) can be 0.05g / 1540.25mm 2 -0.18g / 1540.25mm 2 . The compaction density of the negative electrode tab can be 1.0g / cm 3 -1.8g / cm 3 .

[0109] In some embodiments, the additive comprises sodium allyl phenyl ether sulfonate, and a method for preparing the sodium allyl phenyl ether sulfonate comprises: mixing sodium hydroxybenzenesulfonate, sodium methoxide and methanol in a protective atmosphere to prepare a mixed solution; after passing a protective gas into the mixed solution, adding allyl bromide to perform a first reaction to prepare the sodium allyl phenyl ether sulfonate. The preparation method is convenient to operate, does not increase too many components, and does not cause environmental pollution, safety hazards and other problems.

[0110] As a possible implementation, the method for preparing the mixed solution comprises: adding sodium hydroxybenzenesulfonate and sodium methoxide into methanol under stirring in a protective atmosphere to prepare a mixed solution.

[0111] As a non-limiting example, the allyl bromide is added in a drop-by-drop manner.

[0112] In some embodiments, the sodium hydroxybenzenesulfonate comprises one or more of sodium 2-hydroxybenzenesulfonate, sodium 3-hydroxybenzenesulfonate and sodium 4-hydroxybenzenesulfonate.

[0113] As a possible implementation, the molar ratio of the sodium hydroxybenzenesulfonate and the sodium methoxide is 1:(2-6); for example, it can be but is not limited to 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6 or a range between any two of the above ratios, etc. When the molar ratio of the sodium hydroxybenzenesulfonate and the sodium methoxide is in the above range, it is beneficial to improve the yield and reduce the generation of impurities.

[0114] In some optional embodiments, the molar ratio of the sodium hydroxybenzenesulfonate and the sodium methoxide is 1:(2-3).

[0115] In some embodiments, the molar ratio of the sodium methoxide and the methanol is 1:(6-12); for example, it can be but is not limited to 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:10, 1:10.5, 1:11, 1:11.5, 1:12 or a range between any two of the above ratios, etc. When the molar ratio of the sodium methoxide and the methanol is in the above range, it is beneficial to improve the yield and reduce the generation of impurities.

[0116] In some optional embodiments, the molar ratio of the sodium methoxide and the methanol is 1:(6-8).

[0117] As a possible implementation, the molar ratio of the allyl bromide and the sodium hydroxybenzenesulfonate is (2-6):1; for example, it can be but is not limited to 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1 or a range between any two of the above ratios, etc. When the molar ratio of the allyl bromide and the sodium hydroxybenzenesulfonate is in the above range, it is beneficial to improve the yield and reduce the generation of impurities.

[0118] In some alternative embodiments, the molar ratio of allyl bromide to sodium 4-hydroxybenzenesulfonate is (2-3):1.

[0119] In some embodiments, the temperature of the first reaction is 70-80℃; for example, but not limited to, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, or a range between any two of the aforementioned temperatures, etc. When the temperature of the first reaction is within the aforementioned range, the reaction speed is relatively fast, and the reactants are not decomposed due to the high temperature.

[0120] As a possible embodiment, the time of the first reaction is 1-10h; for example, but not limited to, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, or a range between any two of the aforementioned times, etc.

[0121] In some alternative embodiments, the time of the first reaction is 2-5h.

[0122] It should be noted that the temperature and time of the first reaction can be combined in any suitable manner, and both can be selected from any of the temperatures and times of the first reaction described herein.

[0123] In some embodiments, the product of the first reaction is cooled to room temperature to precipitate the solid, the solid is washed with methanol, and finally the product is vacuum dried at 50-80℃ for 12-36h to obtain sodium allyl phenyl ether sulfonate.

[0124] As a possible embodiment, the protective atmosphere comprises nitrogen.

[0125] In some alternative embodiments, the protective gas is introduced into the mixture for 10-60min.

[0126] In some embodiments, the additive comprises lithium allyl phenyl ether sulfonate, and the method for preparing lithium allyl phenyl ether sulfonate comprises: preparing sodium allyl phenyl ether sulfonate by using the method described above for preparing sodium allyl phenyl ether sulfonate; mixing the sodium allyl phenyl ether sulfonate with an aqueous solution containing lithium salt to perform a second reaction to prepare lithium allyl phenyl ether sulfonate.

[0127] It should be noted that in the present application, the terms "first", "second", etc. in "first reaction", "second reaction", etc. are only for the purpose of description, and cannot be understood as indicating or implying relative importance or quantity, nor can it be understood as implying the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumeration description, and should be understood as not constituting a closed limitation on the quantity.

[0128] In some embodiments, the molar ratio of sodium allyl phenyl ether sulfonate and lithium salt is 1 : (1-5); for example, it can be but not limited to 1 : 1, 1 : 1.5, 1 : 2, 1 : 2.5, 1 : 3, 1 : 3.5, 1 : 4, 1 : 4.5, 1 : 5, or a range between any two of the above ratios, etc. When the molar ratio of sodium allyl phenyl ether sulfonate and lithium salt is in the above range, it is beneficial to increase the yield and reduce the generation of impurities.

[0129] As a possible embodiment, the lithium salt comprises one or more of LiCl, LiBr, Li2SO4, LiNO3, Li2CO3, and Li3PO4.

[0130] In some of the embodiments, the concentration of the aqueous solution containing lithium salt is 1 mol / L-6 mol / L; for example, it can be but not limited to 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, 6 mol / L, or a range between any two of the above concentrations, etc.

[0131] In some alternative embodiments, the concentration of the aqueous solution containing lithium salt is 1 mol / L-2 mol / L.

[0132] As a possible embodiment, the temperature of the second reaction is 60°C-100°C; for example, it can be but not limited to 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, or a range between any two of the above temperatures, etc. When the temperature of the second reaction is in the above range, it has a faster reaction speed, and at the same time, it does not cause the loss of reactants and the decomposition of products due to too high temperature.

[0133] In some alternative embodiments, the temperature of the second reaction is 70°C-90°C.

[0134] In some alternative embodiments, the temperature of the second reaction is 80°C.

[0135] In some alternative embodiments, the time of the second reaction is 12h-24h; for example, it can be but not limited to 12h, 14h, 16h, 18h, 20h, 22h, 24h, or a range between any two of the above times, etc.

[0136] When necessary, the temperature and time of the second reaction can be combined in any suitable manner, and both can be selected from any of the temperatures and times of the second reaction described herein.

[0137] As a non-limiting example, the product of the second reaction is cooled to room temperature to precipitate a solid, which is then washed with deionized water until neutral, and finally the product is vacuum dried at 80-100°C for 12-36 hours to obtain the lithium allyl phenyl ether sulfonate.

[0138] In some embodiments, the method of preparing sodium allyl phenyl ether sulfonate comprises:

[0139] S1, mixing sodium hydroxybenzenesulfonate, sodium methoxide and methanol in a protective atmosphere to prepare a mixed solution. The molar ratio of sodium hydroxybenzenesulfonate to sodium methoxide is 1:(2-6). The molar ratio of sodium methoxide to methanol is 1:(6-12). The protective atmosphere includes nitrogen.

[0140] S2, after introducing the protective gas into the mixed solution, adding allyl bromide to carry out the first reaction to prepare sodium allyl phenyl ether sulfonate. The molar ratio of allyl bromide to sodium hydroxybenzenesulfonate is (2-6):1. The temperature of the first reaction is 70-80°C. The time of the first reaction is 1-10 hours. The protective gas is introduced into the mixed solution for 10-60 minutes.

[0141] As a non-limiting example, the method of preparing lithium allyl phenyl ether sulfonate comprises:

[0142] S1, mixing sodium hydroxybenzenesulfonate, sodium methoxide and methanol in a protective atmosphere to prepare a mixed solution. The molar ratio of sodium hydroxybenzenesulfonate to sodium methoxide is 1:(2-6). The molar ratio of sodium methoxide to methanol is 1:(6-12). The protective atmosphere includes nitrogen.

[0143] S2, after introducing the protective gas into the mixed solution, adding allyl bromide to carry out the first reaction to prepare sodium allyl phenyl ether sulfonate. The molar ratio of allyl bromide to sodium hydroxybenzenesulfonate is (2-6):1. The temperature of the first reaction is 70-80°C. The time of the first reaction is 1-10 hours. The protective gas is introduced into the mixed solution for 10-60 minutes.

[0144] S3, mixing sodium allyl phenyl ether sulfonate with an aqueous solution containing a lithium salt to carry out the second reaction to prepare lithium allyl phenyl ether sulfonate. The molar ratio of sodium allyl phenyl ether sulfonate to lithium salt is 1:(1-5). The lithium salt includes one or more of LiCl, LiBr, Li2SO4, LiNO3, Li2CO3 and Li3PO4. The concentration of the aqueous solution containing the lithium salt is 1-6 mol / L. The temperature of the second reaction is 60-100°C. The time of the second reaction is 12-24 hours.

[0145] In addition, the secondary battery and the electric device of the present application are described below with appropriate reference to the accompanying drawings.

[0146] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During charging and discharging of the battery, active ions are intercalated and deintercalated between the positive electrode sheet and the negative electrode sheet. The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, and functions to prevent short circuiting between the positive electrode and the negative electrode, while allowing ions to pass through.

[0147] The secondary battery of the present application includes the negative electrode sheet of the present application or the negative electrode sheet prepared by the preparation method of the negative electrode sheet of the present application, and has excellent cycle performance while taking into account capacity.

[0148] Positive electrode sheet

[0149] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.

[0150] As a non-limiting example, the positive electrode current collector has two opposite surfaces in the thickness direction thereof, and the positive electrode active material layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0151] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be obtained by forming a metal material on a polymer material base material. In the positive electrode current collector, non-limiting examples of the metal material can include one or more of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. In the positive electrode current collector, non-limiting examples of the polymer material base material can include one or more of a polypropylene (PP) base material, a polyethylene terephthalate (PET) base material, a polybutylene terephthalate (PBT) base material, a polystyrene (PS) base material, and a polyethylene (PE) base material.

[0152] In some embodiments, the secondary battery is a lithium ion battery; and the positive electrode active material of the lithium ion battery includes a lithium ion active material.

[0153] In some embodiments, the positive electrode active material can further include one or more of a ternary material and a lithium iron manganese phosphate material; wherein the ternary material includes Li x (Ni a Co b Mn c ) 1-d M d O 2-y A y(x is 0.2-1.2, 0≤a≤1, 0≤b≤1, 0≤c≤1, a+b+c=1, 0≤d≤1, 0≤y≤2, M includes at least one element selected from Mg, Zr, Al, B, Ta, Mo, W, Nb, Ti, Sr, Cr, Ce, V, Sb, and La, A includes one or more elements selected from F, N, P, S) and / or Li x A e (Ni a Co b Mn c ) 1-d M d O 2-y D y (x+e is 0.2-1.2, 0≤a≤1, 0≤b≤1, 0≤c≤1, a+b+c=1, 0≤d≤1, 0≤y≤2, A includes other cations, M includes at least one element selected from Mg, Zr, Al, B, Ta, Mo, W, Nb, Ti, Sr, Cr, Ce, V, Sb, and La, D includes one or more elements selected from F, N, P, S); the lithium manganese iron phosphate material includes Li a Mn 1-y B y P 1-z C z O 4-n D n (a is 0-1.1, y is 0-0.6, z is 0-0.1, n is 0-0.1, B includes one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Sr, Cr, Ce, La, Ni, Co, Ga, Sn, Sb, Nb, and Ge, C includes one or more elements selected from B (boron), S, Si, and N, D includes one or more elements selected from S, F, Cl, and Br) and / or Li a A x Mn 1-y B y P 1-z C z O 4-n D n (a+x is 0-1.1, x is 0.9-1.1, y is 0-0.6, z is 0-0.1, n is 0-0.1, A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W, B includes one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Sr, Cr, Ce, La, Ni, Co, Ga, Sn, Sb, Nb, and Ge, C includes one or more elements selected from B (boron), S, Si, and N, D includes one or more elements selected from S, F, Cl, and Br).

[0154] It should be noted that the above limitation of x includes the molar content of Li in different charge-discharge states of the battery (usually the battery voltage is between 2-5V).

[0155] It can be understood that the battery will be accompanied by lithium (Li) deintercalation and consumption during charging and discharging, and the content of Li in the positive plate is different when the battery is discharged to different states. In the enumeration of the positive electrode material in this application, the content of Li is the initial state of the material unless otherwise specified. When the positive electrode material is applied to the positive plate in the battery system, the content of Li in the positive electrode material contained in the plate will usually change after charging and discharging cycle. Among them, the content of Li can be quantified by molar content, but it is not limited to this. As for "the content of Li is the initial state of the material", the initial state of the material refers to the state before the material is put into the positive slurry. It can be understood that the new material obtained by properly modifying the listed positive electrode material is also within the scope of the positive electrode material, and the foregoing proper modification refers to acceptable modification of the positive electrode material, and non-limiting examples include coating modification.

[0156] In the enumeration of the positive electrode material in this application, the content of oxygen (O) is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual content of O will fluctuate. Among them, the content of O can be quantified by molar content, but it is not limited to this.

[0157] In some embodiments, the positive active material can also use other positive active materials for batteries known in the art. As a non-limiting example, the positive active material can include one or more of the following materials: lithium-containing phosphate with olivine structure, lithium transition metal oxide and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as positive active materials for batteries can also be used. These positive active materials can be used alone or in combination with two or more. Among them, examples of lithium transition metal oxides can include but are not limited to one or more of lithium cobalt oxide (such as LiCoO2), 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 modified compounds, etc. Non-limiting examples of lithium-containing phosphate with olivine structure can include but are not limited to one or more of lithium iron phosphate, lithium iron phosphate and carbon composite, lithium manganese phosphate, lithium manganese phosphate and carbon composite, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composite. Non-limiting examples of lithium cobalt oxide can include LiCoO2; non-limiting examples of lithium nickel oxide can include LiNiO2; non-limiting examples of lithium manganese oxide can include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxide can include LiNi 1 / 3 Co 1 / 3 Mn1 / 3 O2(also can be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also can be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also can be referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also can be referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to as NCM 811 ), etc. Non-limiting examples of lithium nickel cobalt aluminum oxides can include LiNi 0.80 Co 0.15 Al 0.05 O2.

[0158] In some embodiments, the secondary battery is a sodium-ion battery; the positive electrode material of the sodium-ion battery comprises a sodium-ion active material.

[0159] As non-limiting examples, the sodium-ion active material can comprise one or more of the following materials: one or more of sodium transition metal oxides, polyanionic compounds, and Prussian blue type compounds. However, the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials of sodium-ion batteries can also be used.

[0160] As an optional technical solution of the present application, in the sodium transition metal oxide, the transition metal can comprise one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Non-limiting examples of sodium transition metal oxides can be Na x MO2, wherein M can comprise one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, and 0 < x < 1.

[0161] As an optional technical solution of the present application, the polyanionic compound can be a type of compound having sodium ions, transition metal ions, and tetrahedral (YO4) n- anion units. The transition metal can comprise one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be one or more of P, S, and Si; and n represents the valence of (YO4) n- .

[0162] Polyanionic compounds can also contain sodium ions, transition metal ions, or tetrahedral (YO4) ions. n- A class of compounds consisting of anionic units and halide anions. Transition metals may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y may be one or more of P, S, and Si, and n represents (YO4). n- The valence state; halogens can be one or more of F, Cl and Br.

[0163] Polyanionic compounds can also be sodium-containing tetrahedral (YO4) compounds. n- Anionic unit, polyhedral unit (ZO) y ) m+ And a class of compounds with optional halide anions. Y can be one or more of P, S, and Si, and n represents (YO4). n- The valence state; Z represents a transition metal, which can include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and m represents (ZO). y ) m+ The valence state; halogens can be one or more of F, Cl and Br.

[0164] Polyanionic compounds can include NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2 (P2O7), NaM'PO4F and Na3(VO y )2(PO4)2F 3-2y One or more of (0≤y≤1). Among them, M' in NaM'PO4F can include one or more of V, Fe, Mn and Ni.

[0165] Prussian blue compounds can contain sodium ions, transition metal ions, and cyanide ions (CN). - A class of compounds containing Prussian blue. Transition metals may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. A non-limiting example of Prussian blue compounds is Na. a Me b Me' c (CN)6, wherein Me and Me' can each be one or more of Ni, Cu, Fe, Mn, Co and Zn, 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0166] In some embodiments, the positive electrode active material layer optionally further includes a binder. As non-limiting examples, the binder can include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0167] In some embodiments, the positive electrode active material layer optionally further includes a conductive agent. As non-limiting examples, the conductive agent can include one or more of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0168] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent to form a positive electrode slurry; coating the positive electrode slurry on at least one side surface of the positive electrode current collector, and after processes such as drying, cold pressing, etc., the positive electrode tab can be obtained. The type of the solvent can be selected from, but is not limited to, any of the aforementioned embodiments, such as N-methyl pyrrolidone (NMP). The surface of the positive electrode current collector coated with the positive electrode slurry can be on a single surface of the positive electrode current collector, or on both surfaces of the positive electrode current collector. The surface of the positive electrode current collector coated with the positive electrode slurry can be on a single surface of the positive electrode current collector, or on both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40wt%-80wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000mPa-s-25000mPa-s. When coating the positive electrode slurry, the coating unit area density, in terms of dry weight (excluding the solvent), can be 0.2g / 15 40.25mm 2 -0.45g / 15 40.25mm 2 . The compaction density of the positive electrode tab can be 2.4g / cm 3 -2.8g / cm 3 , optionally 2.4g / cm 3 -2.7g / cm 3 .

[0169] Electrolyte

[0170] The electrolyte has the function of conducting ions between the positive electrode tab and the negative electrode tab. The type of the electrolyte is not particularly limited in the present application and can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0171] In some embodiments, the electrolyte uses an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0172] In some embodiments, the electrolyte salt can include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluoro-oxalato-borate (LiDFOB), lithium bis-oxalato-borate (LiBOB), lithium difluoro-bis-oxalato-phosphate (LiDFOP), and lithium tetrafluoro-oxalato-phosphate (LiTFOP).

[0173] In some embodiments, the solvent can include one or more of ethylene carbonate (EC, ), propylene carbonate (PC, ), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, methyl ethyl sulfone, and diethyl sulfone.

[0174] In some embodiments, the electrolyte solution can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive capable of improving certain properties of the battery, such as an additive for improving overcharge performance of the battery, an additive for improving high-temperature or low-temperature performance of the battery, etc.

[0175] In some embodiments, the additive in the electrolyte solution can include, but is not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), etc.

[0176] Separator film

[0177] In some embodiments, the secondary battery further includes a separator film. The type of the separator film is not particularly limited in the present application, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0178] In some embodiments, the material of the separator film can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the respective layers can be the same or different, and are not particularly limited.

[0179] In some embodiments, the thickness of the separator film is 6-40 μm, optionally 10-16 μm.

[0180] In some of the embodiments, the positive electrode tab, the negative electrode tab and the separator film can be formed into an electrode assembly by a winding process or a stacking process.

[0181] In some of the embodiments, the secondary battery can include an outer package. The outer package can be used to encapsulate the electrode assembly and the electrolyte as described above.

[0182] In some of the embodiments, the outer package of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery can also be a soft package, such as a pouch-type soft package. The soft package can be made of plastic, and further, non-limiting examples of the plastic can include one or more of polypropylene, polybutylene terephthalate, polybutylene succinate, etc.

[0183] The secondary battery includes at least one battery cell. The secondary battery can include one or more battery cells.

[0184] In the present application, unless otherwise specified, a "battery cell" refers to a basic unit capable of converting chemical energy and electrical energy to each other, and further, generally includes at least a positive electrode tab, a negative electrode tab and an electrolyte. During the charging and discharging of the battery, active ions are inserted and extracted between the positive electrode tab and the negative electrode tab. The electrolyte functions to conduct the active ions between the positive electrode tab and the negative electrode tab.

[0185] The shape of the battery cell is not particularly limited in the present application, and can be cylindrical, square or any other arbitrary shape. For example, FIG. 2 is a battery cell 5 having a square structure as an example.

[0186] In some of the embodiments, referring to FIG. 3, the outer package can include a housing 51 and a cover plate 53. The housing 51 can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be provided on the opening to close the receiving cavity. The positive electrode tab, the negative electrode tab and the separator film can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of the electrode assembly 52 included in the battery cell 5 can be one or more, which can be selected by a person skilled in the art according to actual needs.

[0187] The secondary battery can be a battery module 4 or a battery pack 1.

[0188] The battery module includes at least one battery cell. The number of the battery cells included in the battery module can be one or more, which can be selected by a person skilled in the art according to the application and capacity of the battery module.

[0189] FIG. 4 is a battery module 4 as an example. Referring to FIG. 4, in the battery module 4, a plurality of battery cells 5 can be arranged in series along a length direction of the battery module 4. Of course, the plurality of battery cells 5 can be arranged in any other manner. The plurality of battery cells 5 can be fixed by fasteners.

[0190] Optionally, the battery module 4 can further include a housing having an accommodation space, and the plurality of battery cells 5 can be accommodated in the accommodation space.

[0191] In some embodiments, the above-described battery module can be assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more, and a person skilled in the art can select a suitable number according to the application and capacity of the battery pack.

[0192] FIGS. 5 and 6 are a battery pack 1 as an example. Referring to FIGS. 5 and 6, the battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be arranged on the lower box body 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0193] In addition, the application also provides a power utilization device including the secondary battery provided by the application. The secondary battery can be used as a power supply of the power utilization device, or can be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device, an electric vehicle, an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto. Among them, the mobile device can be a mobile phone, a notebook computer, etc.; the electric vehicle can be 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., but is not limited thereto.

[0194] As the power utilization device, the secondary battery can be selected according to the use requirement thereof.

[0195] FIG. 7 is a power utilization device 6 as an example. The power utilization device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirement of high power and high energy density of the secondary battery for the power utilization device, a battery pack or a battery module can be used.

[0196] As another example of the device, it can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thin and light, and the secondary battery can be used as a power supply.

[0197] Embodiments

[0198] Hereinafter, the examples of the present application will be described. The examples described below are illustrative and are intended to be purely exemplary of the application and are not intended to limit the present application. Unless otherwise indicated, technical or scientific terms used in the examples have the meanings as commonly understood by one of ordinary skill in the art to which the application pertains. Unless otherwise indicated, all reagents or instruments were obtained from commercial suppliers such as Sigma-Aldrich, Fisher Scientific, VWR, Mallinckrodt Baker, and Acros Organics and were used without further purification.

[0199] I. Preparation of the electrode sheet

[0200] Example 1

[0201] Step S1, under nitrogen atmosphere and stirring, sodium 4-hydroxybenzenesulfonate and sodium methoxide were added to solvent methanol, the molar ratio of sodium 4-hydroxybenzenesulfonate and sodium methoxide was 1:2, the molar ratio of sodium methoxide and solvent methanol was 1:6, after nitrogen blowing for 60 min, allyl bromide was added dropwise, the molar ratio of allyl bromide and sodium 4-hydroxybenzenesulfonate was 2:1, the first reaction was carried out at 80°C reflux for 10 h, after the reaction was completed, the solid was precipitated after cooling to room temperature, then the solid was washed with methanol, and the solid was vacuum dried at 80°C for 36 h to obtain sodium 4-allyl phenyl ether sulfonate.

[0202] Step S2, sodium 4-allyl phenyl ether sulfonate was added to 1 mol / L aqueous solution containing lithium salt LiCl, the molar ratio of sodium 4-allyl phenyl ether sulfonate and lithium-containing salt was 1:2, the second reaction was carried out at 80°C heating reflux for 12 h, after the reaction was completed, the solid was precipitated after cooling to room temperature, then the solid was washed with deionized water until it was neutral, and finally the solid was vacuum dried at 80°C for 36 h to obtain lithium 4-allyl phenyl ether sulfonate.

[0203] Step S3, artificial graphite, conductive agent SP, CMC-SBR (carboxymethyl cellulose-styrene butadiene rubber) mixed binder and additive lithium 4-allyl phenyl ether sulfonate were mixed at a mass ratio of 96:0.5:2.5:1, deionized water was added, and a negative electrode slurry was obtained under the action of a vacuum stirrer; the negative electrode slurry was uniformly coated on the double-sided surface of a copper foil, the copper foil was dried at room temperature, then transferred to a 120°C oven for drying for 1 h, and then over-cooled, cut to obtain an electrode sheet, wherein the coating amount per unit area on both sides was 0.15 g / 15 40.25 mm 2 .

[0204] The NMR spectrum of the lithium 4-allyl phenyl ether sulfonate prepared in Example 1 is shown in Figure 8. From Figure 8, it can be seen that in the NMR spectrum of the lithium 4-allyl phenyl ether sulfonate, the peak at about 3.33 ppm is the peak of water, and the peak at about 2.5 ppm is the peak of the solvent. There is an obvious para-substitution in the aromatic region, and the chemical shifts of the ortho protons of the sulfonic acid group (A) and the ether bond (B) are 7.5 ppm and 6.9 ppm, respectively, and the integrals are both 2H. The doublet at 4.6 ppm (E) with an integral of 2H is due to the fact that the protons in E are connected to electronegative groups (-O), and the chemical shift is shifted to the low field. The methanolic protons are chemically not equivalent, and two triplets at 5.3 ppm (D) with an integral of 2H are observed. The complex multiplet with an integral of 1H at 6.0 ppm corresponds to the secondary vinyl protons (C). Thus, it can be seen that the lithium 4-allyl phenyl ether sulfonate prepared in Example 1 contains a carbon-carbon double bond and a lithium sulfonate group.

[0205] The infrared spectra of the graphite and the lithium 4-allyl phenyl ether sulfonate after electro-polymerization of the lithium 4-allyl phenyl ether sulfonate on the graphite in Example 1 are shown in Figure 9. From Figure 9, it can be seen that in the infrared spectrum of the lithium 4-allyl phenyl ether sulfonate / graphite, the absorption peaks at 1410 cm -1 , 1481 cm -1 and 1620 cm -1 correspond to the benzene ring skeleton stretching vibration, indicating that the benzene ring exists in the compound; the absorption peak at 860 cm -1 indicates para-disubstituted benzene; the absorption peak at 930 cm -1 corresponds to the S-O bond; the absorption peaks at 1007 cm -1 , 1044 cm -1 and 1124 cm -1 correspond to the O=S=O stretching vibration; and the absorption peak at 1179 cm -1 corresponds to the C-O stretching vibration. These results indicate that the lithium 4-allyl phenyl ether sulfonate forms the expected polymer on the surface of the graphite electrode.

[0206] Examples 2-8

[0207] Examples 2-8 and the preparation method of Example 1 are similar, and the differences are shown in Table 1. Among them, Examples 2 and 5-7 further include the following differences from Example 1:

[0208] The binder used in step S3 of Example 2 is a polyacrylic acid binder.

[0209] In Example 5, the nitrogen was bubbled for 10 minutes in Step S1; the product of the first reaction was cooled to room temperature to precipitate the solid, which was washed with methanol, and then the solid was dried at 80°C under vacuum for 12 hours. In Step S2, the concentration of the lithium salt in the aqueous solution was 6 mol / L; the product of the second reaction was cooled to room temperature to precipitate the solid, which was washed with deionized water until it was neutral, and then the solid was dried at 100°C for 12 hours. In Step S3, the negative electrode active material used was natural graphite, and the conductive agent used was acetylene black.

[0210] In Example 6, the nitrogen was bubbled for 30 minutes in Step S1; the product of the first reaction was cooled to room temperature to precipitate the solid, which was washed with methanol, and then the solid was dried at 80°C under vacuum for 12 hours. In Step S2, the product of the second reaction was cooled to room temperature to precipitate the solid, which was washed with deionized water until it was neutral, and then the solid was dried at 100°C for 12 hours. In Step S3, the negative electrode active material used was natural graphite, and the binder used was a polyacrylic binder.

[0211] In Example 7, the nitrogen was bubbled for 30 minutes in Step S1; the product of the first reaction was cooled to room temperature to precipitate the solid, which was washed with methanol, and then the solid was dried at 80°C under vacuum for 12 hours. In Step S2, the concentration of the lithium salt in the aqueous solution was 2 mol / L; the product of the second reaction was cooled to room temperature to precipitate the solid, which was washed with deionized water until it was neutral, and then the solid was dried at 100°C for 12 hours. In Step S3, the negative electrode active material used was natural graphite, and the binder used was a polyacrylic binder.

[0212] Comparative Example 1

[0213] In Comparative Example 1, no additives were added; the details are as follows:

[0214] The artificial graphite, the conductive agent acetylene black, and the CMC-SBR (carboxymethyl cellulose-styrene butadiene rubber) mixed binder were mixed in a mass ratio of 96:0.5:3.5; the negative slurry was uniformly coated on both sides of the copper foil, the copper foil was dried at room temperature, then transferred to a 120°C oven for drying for 1 hour, and then over-cooled, cut, to obtain the electrode sheet, wherein the coating amount per unit area on both sides was 0.15 g / 1540.25 mm 2 .

[0215] Comparative Example 2

[0216] In Comparative Example 2, no additives were added; the details are as follows:

[0217] The natural graphite, the conductive agent SP, and the polyacrylic acid binder were mixed in a mass ratio of 96:0.5:3.5, deionized water was added, and a negative electrode slurry was obtained under the action of a vacuum stirrer; the negative slurry was uniformly coated on the double-sided surface of a copper foil, the copper foil was dried at room temperature, then transferred to a 120℃ oven for drying for 1h, and then over-cooled, cut, to obtain an electrode sheet, wherein the coating amount per unit area on the double sides was 0.15g / 1540.25mm 2 .

[0218] Comparative Example 3

[0219] The difference between Comparative Example 3 and Example 1 is that lithium dodecyl sulfonate is used instead of lithium 4-allyl phenyl ether sulfonate, and the preparation method of the negative electrode sheet is the same.

[0220] Comparative Example 4

[0221] The difference between Comparative Example 4 and Example 1 is that vinyl phosphoric acid is used instead of lithium 4-allyl phenyl ether sulfonate, and the preparation method of the negative electrode sheet is the same.

[0222] The preparation parameters of the above examples and comparative examples are shown in Table 1.

[0223] Table 1

[0224] In Table 1, n1 represents the molar ratio of sodium hydroxybenzenesulfonate and sodium methoxide; n2 represents the molar ratio of sodium methoxide and methanol; n3 represents the molar ratio of allyl bromide and sodium hydroxybenzenesulfonate; n4 represents the molar ratio of sodium allyl phenyl ether sulfonate and lithium salt; and n5 represents the mass ratio of negative electrode active material, conductive agent, binder, and additive in the negative electrode slurry.

[0225] II. Performance Test

[0226] 1. First coulombic efficiency test

[0227] The electrode sheets prepared in the above examples and comparative examples were assembled into batteries in a 2016 type button cell shell, wherein the prepared electrode sheet was used as the positive electrode, a Celgard film (diameter 19mm) was used as the separator, metallic lithium was used as the negative electrode, and 1M LiPF6 / EC:DMC (EC:DMC, v:v=1:1) was used as the electrolyte. The entire process of assembling the battery was carried out in an argon glove box (H2O<0.1ppm, O2<0.1ppm). After assembly, the battery was left to stand for four hours and was ready for use. The battery was charged at 0.33C constant current to 3.65V, and then charged at 3.65V constant voltage to 0.05C, at which time the total charge capacity was recorded as C0. Subsequently, the battery was discharged at 0.33C constant current to 2.5V, and then discharged at 0.04C constant current to 2.0V, at which time the total discharge capacity was D0. D0 / C0 was the first coulombic efficiency.

[0228] The first circle charge-discharge curves of the pole pieces prepared in Examples 1-3 and Comparative Example 1 in the battery are shown in FIG. 10. As can be seen from FIG. 10, the capacity of the electrode is improved by the introduction of the additive; this can be due to the fact that the sulfonated polyallyl phenyl ether itself has an electrochemical lithiation effect in addition to the effect of conducting lithium ions; the carbon-carbon double bond and the sulfonic acid group oxygen are active sites for lithium storage, and they can produce additional capacity for the electrode.

[0229] 2. Cycle performance test

[0230] Preparation of the positive pole piece: lithium iron phosphate, conductive carbon black SP and binder PVDF were dispersed in a solvent N-methyl pyrrolidone in a weight ratio of 96:2:2, mixed uniformly to obtain a positive electrode slurry; the positive electrode slurry was uniformly coated on the double-sided surface of the positive electrode current collector aluminum foil, and after drying and cold pressing, the positive electrode pole piece was obtained, wherein the coating amount per unit area of the double-sided surface was 0.25 g / 1540.25 mm 2 .

[0231] The pole pieces prepared in the above examples and comparative examples were used as negative pole pieces, respectively.

[0232] Separator: a 12 μm thick polyethylene separator was selected.

[0233] Preparation of the electrolyte: the organic solvent was a mixture containing ethylene carbonate (EC) and diethyl carbonate (DEC), wherein the volume ratio of EC to DEC was 3:7. In an argon glove box with a water content of <10 ppm, fully dried lithium salt LiPF6 was dissolved in the organic solvent, 2 wt% of fluoroethylene carbonate (FEC) was added, and the mixture was uniformly mixed to obtain the electrolyte. The concentration of the lithium salt was 1 mol / L.

[0234] Assembly of the secondary battery: the positive pole piece / separator / negative pole piece were sequentially laminated in the order of lamination to form an electric core, and the bare electric core was placed in an outer package, the electrolyte was injected and packaged, and a secondary battery was obtained.

[0235] The secondary battery was charged at 0.5 C to 3.65 V, and then discharged at 0.5 C to 2.5 V. The process was repeated for multiple cycles until the battery was cycled to 600 cycles, the discharge capacity D1 at this time was recorded, and the capacity retention rate at 600 cycles was further calculated.

[0236] TEM images of the pole pieces prepared in Example 1 and Comparative Example 1 after battery cycle test are shown in Figure 11. In Figure 11, (a) is the pole piece prepared in Comparative Example 1, and (b) is the pole piece prepared in Example 1. As can be seen from Figure 11, the SEI film layer on the surface of the graphite of the pole piece of Comparative Example 1 is thick and uneven after 600 cycles of battery cycle test, because the pole piece of Comparative Example 1 does not have a protective layer. The SEI film layer on the surface of the graphite of the pole piece prepared in Example 1 is thin and evenly distributed on the surface of the graphite even after 600 cycles, because the pole piece has a protective layer, so that the stability of the battery is better.

[0237] The cycle stability test results of the pole pieces prepared in Example 1 and Comparative Example 1 in the battery are shown in Figure 12. As can be seen from Figure 12, the capacity retention rate of the battery of Comparative Example 1 is 95.7% after 600 cycles, and the capacity retention rate of the battery of Example 1 is 96.3% after 600 cycles, which is better than the battery performance of Comparative Example. It shows that after the same number of cycles, Example 1 has a higher discharge capacity compared with Comparative Example 1, and it shows that the pole piece provided by the application has more excellent cycle performance.

[0238] 3. DCR test

[0239] The data in the discharge process of the cycle performance test is taken to obtain the DCR change data in the cycle process, which can reflect the discharge polarization of the battery cell with the cycle. The results are shown in Table 2. The change of DCR of Example 1 and Comparative Example 1 with the cycle number is shown in Figure 13.

[0240] The test results of the above examples and comparative examples are shown in Table 2.

[0241] Table 2

[0242] As can be seen from the results of Examples 1-8 and Comparative Examples 1-4 in Table 2, the negative pole piece provided by the application has better cycle performance and lower DCR while taking into account the capacity.

[0243] As can be seen from the results of Example 1 and Comparative Examples 3-4, the additive containing both carbon-carbon double bond and lithium sulfonate group has a synergistic effect.

[0244] The above description of each example tends to emphasize the differences between each example, and the same or similar parts can be referred to each other. For the sake of brevity, the same or similar parts will not be described again.

[0245] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration, function, and effect as the technical idea of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications to the embodiments, or by combining part of the configurations of the embodiments, which can be conceived by those skilled in the art without departing from the spirit of the present application, are also included in the scope of the present application.

Claims

1. A negative electrode sheet, comprising a negative electrode active material layer, wherein the negative electrode active material layer comprises an additive, and the additive comprises a compound comprising a carbon-carbon double bond and a sulfonate group, and the sulfonate group comprises one of a lithium sulfonate group and a sodium sulfonate group.

2. The negative electrode sheet according to claim 1, wherein The additive includes a compound having a structure according to formula (I): The M element comprises one of Li and Na.

3. The negative electrode sheet according to claim 2, wherein The M element is Li, and the additive comprises a lithium allyl phenyl ether sulfonate.

4. The negative electrode sheet according to claim 3, wherein The additive comprises one or more of a 2-allyl phenyl ether lithium sulfonate, a 3-allyl phenyl ether lithium sulfonate, and a 4-allyl phenyl ether lithium sulfonate.

5. The negative electrode sheet according to claim 2, wherein The M element is Na, and the additive comprises a sodium allyl phenyl ether sulfonate.

6. The negative electrode sheet according to claim 5, wherein The additive comprises one or more of a 2-allyl phenyl ether sodium sulfonate, a 3-allyl phenyl ether sodium sulfonate, and a 4-allyl phenyl ether sodium sulfonate.

7. The negative electrode sheet according to any one of claims 1 to 6, wherein The additive has a mass ratio of 0.5%-3% in the negative electrode active material layer.

8. The negative electrode sheet according to any one of claims 1 to 7, wherein The negative electrode active material layer further comprises one or more of a negative electrode active material, a conductive agent, and a binder.

9. The negative electrode sheet according to claim 8, wherein The negative electrode active material comprises a carbon-based material.

10. The negative electrode sheet according to any one of claims 8 to 9, wherein The negative electrode active material comprises one or more of natural graphite, artificial graphite, and mesocarbon microbeads. 11.A method for preparing the negative electrode sheet according to any one of claims 1 to 10, the method comprising a step of preparing a negative electrode slurry for forming the negative electrode active material layer, wherein the negative electrode slurry comprises the additive.

12. The production method according to claim 11, wherein The additive comprises a sodium allyl phenyl ether sulfonate, and the method for preparing the sodium allyl phenyl ether sulfonate comprises: mixing sodium hydroxybenzenesulfonate, sodium methoxide, and methanol in a protective atmosphere to prepare a mixed solution; after the protective gas is introduced into the mixed solution, adding allyl bromide to perform a first reaction to prepare the sodium allyl phenyl ether sulfonate.

13. The production method according to claim 12, wherein The sodium hydroxybenzenesulfonate comprises one or more of 2-sodium hydroxybenzenesulfonate, 3-sodium hydroxybenzenesulfonate, and 4-sodium hydroxybenzenesulfonate.

14. The production method according to any one of claims 12 to 13, wherein The molar ratio of the sodium hydroxybenzenesulfonate to the sodium methoxide is 1:(2-6).

15. The production process according to any one of claims 12 to 14, wherein The molar ratio of the sodium methoxide to the methanol is 1:(6-12).

16. The production process according to any one of claims 12 to 15, wherein The molar ratio of the allyl bromide to the sodium hydroxybenzenesulfonate is (2-6):

1.

17. The production process according to any one of claims 12 to 16, wherein The temperature of the first reaction is 70℃-80℃.

18. The production process according to any one of claims 12 to 17, wherein The time of the first reaction is 1h-10h.

19. The production method according to claim 11, wherein The additive comprises a lithium allyl phenyl ether sulfonate, and the method for preparing the lithium allyl phenyl ether sulfonate comprises: The method for preparing the sodium allyl phenyl ether sulfonate according to claim 12 is used to prepare the lithium allyl phenyl ether sulfonate; The sodium allyl phenyl ether sulfonate is mixed with an aqueous solution containing a lithium salt to perform a second reaction to prepare the lithium allyl phenyl ether sulfonate.

20. The production method according to claim 19, wherein The molar ratio of the sodium allyl phenyl ether sulfonate to the lithium salt is 1:(1-5).

21. The production process according to any one of claims 19 to 20, wherein, The lithium salt comprises one or more of LiCl, LiBr, Li2SO4, LiNO3, Li2CO3, and Li3PO4.

22. The production process according to any one of claims 19 to 21, wherein, The concentration of the aqueous solution containing the lithium salt is 1mol / L-6mol / L.

23. The production process according to any one of claims 19 to 22, wherein The temperature of the second reaction is 60℃-100℃.

24. The production process according to any one of claims 19 to 23, wherein, The time of the second reaction is 12h-24h.

25. A secondary battery comprising the negative electrode sheet according to any one of claims 1 to 10 or the negative electrode sheet prepared by the production method according to any one of claims 11 to 24.

26. The secondary battery of claim 25, wherein, The secondary battery is a lithium ion battery.

27. The secondary battery of claim 25, wherein, The secondary battery is a sodium ion battery.

28. An electric device comprising the secondary battery according to any one of claims 25 to 27.

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