Modified electrode plate, method for manufacturing the same, secondary battery, and power consumption device

Abstract

This application provides a modified electrode plate, a method for manufacturing the same, a secondary battery, and a power consumption device. The modified electrode plate includes an electrode plate having a sodium element or a lithium element on its surface and including a pre-lithified negative electrode plate or a pre-sodiumified negative electrode plate, and a protective film including a first group and a hydrophobic group, wherein the first group is attached to the surface of the electrode plate, the hydrophobic group is detached from the electrode plate, and the hydrophobic group is exposed on the surface of the protective film. By placing a protective film having a hydrophobic group on its surface on the electrode plate, the gram capacity of the electrode plate in the first cycle can be improved by effectively blocking water, oxygen, or carbon dioxide in the air and effectively preventing the reaction between water, oxygen, or carbon dioxide that has passed through the protective layer and the active component on the electrode plate.

Description

Cross-reference of related applications

[0001] This application claims priority to Chinese Patent Application 202311229296.X, proposed on September 22, 2023, titled "Modified electrode plate, method for manufacturing the same, secondary battery and power consumption device," and all contents of this application are incorporated herein by reference. [Technical Field]

[0002] This application relates to the battery technology field, and more particularly to modified electrodes, methods for manufacturing the same, secondary batteries, and power consumption devices. [Background technology]

[0003] During the initial charge-discharge cycle of a secondary battery, a solid electrolyte interface (SEI) film is formed on the surface of the negative electrode active material. This causes the continuous consumption of active ions (lithium or sodium) from the positive electrode, resulting in low initial Coulomb efficiency (ICE) and energy density. Particularly during repeated charging cycles, the negative electrode active material continuously expands and contracts during the process of detaching / absorbing active ions, leading to structural collapse and capacity degradation. This destabilizes the solid electrolyte interface film, and the continuous formation and destruction of the SEI film sustainably consumes active ions. However, a stable SEI film is a major factor in extending battery cycle life. Therefore, how to generate a tough and robust SEI film on the negative electrode without losing active ions is a crucial issue for improving performance.

[0004] Currently, pre-lithification or pre-sodiumization of the negative electrode is a relatively effective solution. By replenishing the active ions consumed during the reaction process and reducing the volume expansion of the negative electrode active material to some extent, the stability of the SEI film is improved, thereby enhancing the related performance of the secondary battery.

[0005] However, after pre-lithification or pre-sodiumification treatment, the anode's hydroxyl stability deteriorates, making it more susceptible to oxidation when exposed to air, thus limiting the gram capacity output of the anode during the first cycle. [Overview of the project]

[0006] This application provides a modified electrode plate for improving the stability of the electrode plate in air, a method for manufacturing the same, a secondary battery, and a power consumption device.

[0007] A first aspect of this application provides a modified electrode plate comprising an electrode plate having a sodium element or a lithium element on its surface and including a pre-lithified negative electrode plate or a pre-sodiumified negative electrode plate, and a protective film comprising a first group and a hydrophobic group, wherein the first group is attached to the surface of the electrode plate, the hydrophobic group is detached from the electrode plate, and the hydrophobic group is exposed on the surface of the protective film.

[0008] The pre-lithium-ionized negative electrode plate or pre-sodium-ionized negative electrode plate has an SEI film on its surface. The protective film installed on the electrode plate does not adversely affect the SEI film, ensuring that the SEI film functions normally. Furthermore, because the protective film has hydrophobic groups on its surface, it effectively blocks water, oxygen, or carbon dioxide from the air, and effectively mitigates the reaction between water, oxygen, or carbon dioxide that has passed through the protective layer and the active components on the electrode plate, thereby improving the gram capacity of the electrode plate in the first cycle.

[0009] In any embodiment of the first aspect, the first group includes one or more of a phosphate group, a silyl halide group, a siloxane group, a thiol group, a carboxylic acid group, or -N=N-. Each of the first groups is adsorbed onto the sodium or lithium element on the electrode surface by chemical bonding adsorption or electrostatic adsorption, the adsorption is relatively stable, and the formed protective film can provide long-term protection to the electrode.

[0010] In any embodiment of the first aspect, the hydrophobic group comprises one or more of a C6-C20 aryl group, a C1-C50 alkyl group, or a C1-C50 haloalkyl group, and selectively comprises one or more of a C6-C10 aryl group, a C1-C40 alkyl group, or a C1-C40 haloalkyl group. The aryl group, alkyl group, or haloalkyl group in the hydrophobic group is a hydrophobic group, and in application, the alkyl group or haloalkyl group acts as the outermost group of the hydrophobic group to realize the hydrophobic effect of the protective film.

[0011] In any embodiment of the first aspect, the protective film comprises one or more of the following: a C1-C50 alkylphosphonate film, a C1-C50 alkylchlorosilane film, a C1-C50 fluoroalkylsiloxane film, a C1-C50 thiol film, or a benzotriazole film. Selectively, the protective film comprises one or more of the following: a C1-C40 alkylphosphonate film, a C1-C30 alkylchlorosilane film, a C1-C40 fluoroalkylsiloxane film, or a C1-C10 thiol film. The substance forming each of the above protective films has self-assembly properties and can self-assemble on the electrode surface to form a protective film with an alkyl group or haloalkyl group as a hydrophobic group and a phosphonic acid group, chlorosilane group, siloxane group, thiol group, or -N=N- as the first group. The exposure of the hydrophobic groups of the protective film provides hydrophobic properties to the protective film, thereby sequestrating water oxygen from the air.

[0012] In any embodiment of the first aspect, the C1-C40 alkyl phosphonate film includes any one or more of a propyl phosphonate film, an octadecyl phosphonate film, or a dihexadecyl phosphonate film. Optionally, the C1-C30 alkylchlorosilane film includes any one or more of an n-propyltrichlorosilane film, an isopropyltrichlorosilane film, an n-butyltrichlorosilane film, a tert-butyltrichlorosilane film, an n-hexyltrichlorosilane film, an n-heptyltrichlorosilane film, a tridecyltrichlorosilane film, a tetradecyltrichlorosilane film, an octadecyltrichlorosilane film, or a tricosyltrichlorosilane film. Optionally, the C1-C30 fluoroalkylsiloxane film includes any one or more of a heptadecafluorodecyl-trimethoxysilane (FAS-17) film or a trifluoropropane trimethoxysilane (FAS-3) film. Optionally, the C1-C10 thiol film includes any one or more of an n-propylthiol film, an ethylthiol film, an isopropylthiol film, an n-butylthiol film, a tert-butylthiol film, an n-pentylthiol film, an n-hexylthiol film, or an n-decylthiol film.

[0013] In any embodiment of the first aspect, the modified electrode plate includes a current collector and an active layer disposed on at least one surface of the current collector. The protective film is adhered onto the active layer. The protective film includes a C1-C50 alkyl phosphonate film, and the mass content of P element in all elements of the active layer of the modified electrode plate and the protective film is 300 ppm to 500 ppm. Or the protective film includes a C1-C50 alkyl chlorosilane film, and the mass content of Si element in all elements of the active layer of the modified electrode plate and the protective film is 250 ppm to 400 ppm, and the mass content of Cl element in all elements of the active layer of the modified electrode plate and the protective film is 300 ppm to 500 ppm. Or the protective film includes a C1-C50 fluoroalkyl siloxane film, and the mass content of Si element in all elements of the active layer of the modified electrode plate and the protective film is 250 ppm to 400 ppm, and the mass content of F element in all elements of the active layer of the modified electrode plate and the protective film is 500 ppm to 750 ppm. Or the protective film includes a C1-C50 thiol film, and the mass content of S element in all elements of the active layer of the modified electrode plate and the protective film is 100 ppm to 300 ppm.

[0014] In any embodiment of the first aspect, the water contact angle of the modified electrode plate is 65° to 85°. It is explained that the larger the contact angle is, the better the tightness of the protective film is, and the better the protective effect on the electrode plate is.

[0015] In any embodiment of the first aspect, the protective film is a self-assembled monolayer. The self-assembled monolayer formed on the surface of the electrode plate has better tightness and uniformity, and can more effectively block the entry of hydrogen and oxygen in the air into the electrode plate. On the other hand, since the formed self-assembled monolayer is a monolayer, it can reach a thickness at the nanometer level. Such a thickness generally does not inhibit the transmission at the interface of lithium / sodium ions, and does not deteriorate the kinetic performance of the material, thereby not affecting the electrical characteristics of the electrode assembly.

[0016] In any embodiment of the first aspect, the prelithified anode plate optionally includes one or more of the following: a metallic lithium prelithified anode plate, a lithium alloy prelithified anode plate, or an organic lithium prelithified anode plate.

[0017] In any embodiment of the first aspect, the pre-sodiumized anode plate includes one or more of the following: a metallic sodium pre-sodiumized anode plate, an electrochemical pre-sodiumized anode plate, or an organosodium pre-sodiumized anode plate.

[0018] A second aspect of this application provides a method for manufacturing a modified electrode plate according to any one of the first aspects, the method comprising: manufacturing a protective solution containing a first group and a hydrophobic group; and immersing an electrode plate having sodium or lithium elements on its surface in the protective solution for a predetermined time, thereby causing the first group to adhere to the electrode plate surface, the hydrophobic group to detach from the electrode plate to form a protective film, and thereby obtaining a modified electrode plate.

[0019] The above manufacturing method is easy to operate, highly adaptable, and can be applied to the modification of various electrode plates. The protective film formed using the protective agent effectively blocks water and oxygen from reaching the electrode plate.

[0020] In any embodiment of the second aspect, the solvent of the protective agent solution comprises an ether-based solvent, which selectively comprises ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran (THF), methyltetrahydrofuran, or 1,3-dioxolane.

[0021] In any embodiment of the second aspect, the concentration of the protective agent solution is 0.01 wt% to 5 wt%, and selectively 0.5 wt% to 3 wt%. The density and mass of the formed protective film are adjusted by adjusting the concentration of the protective agent solution.

[0022] In any embodiment of the second aspect, the predetermined time is 2 min to 30 min, and selectively 10 min to 20 min. Within the predetermined time, the protective agent molecules gradually self-repair through continuous adsorption-desorption to the electrode surface, reaching dynamic equilibrium and forming a protective film.

[0023] A third aspect of this application provides a secondary battery comprising a positive electrode plate, a negative electrode plate, and an electrolyte, wherein the positive electrode plate or the negative electrode plate includes one of the modified electrode plates according to the first aspect described above.

[0024] A fourth aspect of this application provides a power consumption device, the power consumption device including a secondary battery, wherein the secondary battery includes any one of the secondary batteries according to the third aspect described above. [Brief explanation of the drawing]

[0025] To more clearly illustrate the technical concept of the embodiments of this application, the following is a brief introduction to the drawings that may be used in the embodiments of this application. It is obvious that the drawings described below represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without expending any creative effort. [Figure 1] This is a schematic diagram of a secondary battery according to one embodiment of the present application. [Figure 2] Figure 1 is an exploded view of a secondary battery according to one embodiment of this application. [Figure 3] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 4] This is a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 5] Figure 4 is an exploded view of a battery pack according to one embodiment of this application. [Figure 6] This is a schematic diagram showing a secondary battery according to one embodiment of this application used as a power consumption device for a power source.

[0026] In drawings, the drawings are not drawn to the actual scale. [Modes for carrying out the invention]

[0027] The embodiments of this application will be described in more detail below, linking them with the drawings and examples. The detailed descriptions of the embodiments and drawings below are for illustrative purposes to illustrate the principles of this application, but are not intended to limit the scope of this application; in other words, this application is not limited to the embodiments described.

[0028] The following describes in detail embodiments of the modified electrode plate, its manufacturing method, secondary battery, and power consumption device disclosed in this application, with appropriate reference to the drawings. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of well-known matters and redundant explanations of structures that are actually the same may be omitted. This is to avoid making the following explanation unnecessarily long and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and do not limit the topics described in the claims.

[0029] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the endpoints, and any combination is possible, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 can also be assumed. Furthermore, if the minimum range values ​​are listed as 1 and 2, and the maximum range values ​​are listed as 3, 4 and 5, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 can all be assumed. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression for any combination of real numbers a-b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply an abbreviated representation of combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0030] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0031] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0032] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the fact that the method referred to above may further include step (c) means that step (c) may be added to the method in any order, for example the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0033] [Secondary battery] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be used continuously after being discharged by activating the active material through a charging method.

[0034] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, and an electrolyte. During the charging and discharging process of the battery, active ions (e.g., lithium ions or sodium ions) move back and forth between the positive and negative electrode plates, undergoing intercalation and deintercalation. The electrolyte primarily acts as a conductor of active ions between the positive and negative electrode plates.

[0035] [Modified plate] As described in the background technology, after pre-lithification or pre-sodiumization treatment, the negative electrode plate becomes less stable in terms of water-oxygen stability, making it more susceptible to oxidation when exposed to air. This reduces the Coulomb efficiency of the negative electrode in the first cycle, further affecting the positive electrode capacity and leading to a decrease in battery cycle performance. On the other hand, the presence of sodium ions or lithium ions on the surface of the positive electrode plate also results in poor water-oxygen stability, which also leads to a decrease in the Coulomb efficiency of the positive electrode in the first cycle and a decrease in battery cycle performance. To improve the Coulomb efficiency of the electrode plate in the first cycle, the first embodiment of this application provides a modified electrode plate comprising an electrode plate and a protective film, wherein the electrode plate surface has sodium or lithium elements, the electrode plate includes a pre-lithified negative electrode plate or a pre-sodiumized negative electrode plate, and the protective film comprises a first group and a hydrophobic group, the first group being attached to the electrode plate surface, the hydrophobic group being detached from the electrode plate, and the hydrophobic group being exposed on the surface of the protective film.

[0036] The pre-lithium-ionized negative electrode plate or pre-sodium-ionized negative electrode plate has an SEI film on its surface. The protective film installed on the electrode plate does not adversely affect the SEI film, ensuring that the SEI film functions normally. Furthermore, because the protective film has hydrophobic groups on its surface, it effectively blocks water, oxygen, or carbon dioxide from the air, and effectively mitigates the reaction between water, oxygen, or carbon dioxide that has passed through the protective layer and the active components on the electrode plate, thereby improving the gram capacity of the electrode plate in the first cycle.

[0037] In some embodiments of this application, the first group includes one or more of a phosphoric acid group, a silyl halide group, a siloxane group, a thiol group, a carboxylic acid group, or -N=N-. Each of the first groups is adsorbed onto the sodium or lithium element on the electrode surface by chemical bonding adsorption or electrostatic adsorption, the adsorption is relatively stable, and the formed protective film can provide long-term protection to the electrode.

[0038] In some embodiments of this application, the hydrophobic group comprises one or more of the following: a C6-C20 aryl group, a C1-C50 alkyl group, or a C1-C50 haloalkyl group. Selectively, the hydrophobic group comprises one or more of the following: a C6-C10 aryl group, a C1-C40 alkyl group, or a C1-C30 haloalkyl group. Since all of the above hydrophobic groups are structurally relatively stable, they do not adversely affect the performance of the battery. The aryl group, alkyl group, or haloalkyl group in the above hydrophobic group is a hydrophobic group, and in application, the alkyl group or haloalkyl group acts as the outermost group of the hydrophobic group to realize the hydrophobic effect of the protective film.

[0039] Since the compound having the first group and the hydrophobic group has relatively good solubility in the electrolyte of a secondary battery, when the modified electrode plate of this application is used in a secondary battery, the protective film gradually dissolves in the electrolyte and does not affect the action of the active components of the electrode plate.

[0040] The material for forming the protective film in the above embodiments of this application can be selected from a general material having the above first group and a hydrophobic group, and in order to further control the influence of the protective film on secondary battery performance, in some embodiments of this application, the protective film comprises one or more of the following: a C1-C50 alkylphosphonate film, a C1-C50 alkylchlorosilane film, a C1-C50 fluoroalkylsiloxane film, a C1-C50 thiol film, or a benzotriazole film, and selectively, the protective film comprises one or more of the following: a C1-C40 alkylphosphonate film, a C1-C30 alkylchlorosilane film, a C1-C30 fluoroalkylsiloxane film, or a C1-C10 thiol film. The materials that form each of the above protective films have self-assembly properties and can self-assemble on the electrode surface to form a protective film with alkyl groups or haloalkyl groups as hydrophobic groups and phosphonic acid groups, chlorosilane groups, siloxane groups, thiol groups, or -N=N- as the primary group. When the hydrophobic groups of the protective film are exposed, the protective film provides hydrophobic properties and sequesters water and oxygen from the air.

[0041] In some embodiments of this application, the C1-C40 alkylphosphonate film selectively includes, but is not limited to, one or more of the following: a propylphosphonate film, an octadecylphosphonate (OPA) film, or a dihexadecylphosphonate (DHP) film. In particular, octadecylphosphonate (OPA) and dihexadecylphosphonate (DHP) have relatively low reduction potentials, thus possessing better chemical stability and effectively blocking water oxygen in the air. Furthermore, they do not undergo reduction reactions with the electrode surface even when present on the electrode surface for extended periods, effectively controlling by-products from chain scalding and dehydrogenation due to the redox reaction of the alkyl chain. Moreover, because the molecular chain of octadecylphosphonate is relatively smaller than that of dihexadecylphosphonate, the resulting protective film is denser and provides more pronounced protection to the electrode.

[0042] In some embodiments of this application, the C1-C30 alkylchlorosilane film selectively includes, but is not limited to, one or more of the following: n-propyltrichlorosilane film, isopropyltrichlorosilane film, n-butyltrichlorosilane film, tert-butyltrichlorosilane film, n-hexyltrichlorosilane film, n-heptyltrichlorosilane film, tridecyltrichlorosilane film, tetradecyltrichlorosilane film, octadecyltrichlorosilane film, and tricosyltrichlorosilane film. In some embodiments of this application, the C1-C30 fluoroalkylsiloxane film selectively includes, but is not limited to, one or more of the following: heptadecafluorodecyl-trimethoxysilane (FAS-17) film and trifluoropropanetrimethoxysilane (FAS-3) film. In some embodiments of this application, the C1-C10 thiol film selectively includes, but is not limited to, one or more of the following: n-propylthiol film, ethylthiol film, isopropylthiol film, n-butylthiol film, tert-butylthiol film, n-pentylthiol film, n-hexylthiol film, and n-decylthiol film. When the molecular chains of each of the above substances are relatively small, the density of the formed protective film improves, and the protective effect on the electrode plate improves.

[0043] In some embodiments of this application, the protective film can not only perform a protective function on the electrode plate, but if the protective film contains P, S, Si, or halogens, these elements can serve as evidence that the protective film is adsorbed onto the electrode plate, while these elements can also be used as active elements in the secondary battery. For example, P, S, Si, F, and Cl can be used as active elements to gradually create more stable substances in the battery as the battery charge and discharge progresses, such as PO4 3- SO4 2- Soluble and insoluble stable substances such as NaF (NaF has relatively low solubility in the electrolyte, and basically only dissolves at a rate of several tens of ppm, so NaF is generally considered an insoluble substance) can be formed. The soluble substances can increase the conductivity of the electrolyte to some extent, and the insoluble substances deposit on the negative electrode and prevent further reaction between the electrolyte and the negative electrode carbon material, thereby improving the performance of the battery.

[0044] In some embodiments, the modified electrode plate includes a current collector and an active layer installed on at least one surface of the current collector, and a protective film is attached to the active layer.

[0045] In some embodiments of this application, the protective film comprises a C1-C50 alkylphosphonate film, and the mass content of element P in the active layer of the modified electrode and the protective film is 300 ppm to 500 ppm.

[0046] In some embodiments of this application, the protective film comprises a C1-C50 alkylchlorosilane film, the total elemental mass content of Si in the active layer of the modified electrode and the protective film is 250 ppm to 400 ppm, and the total elemental mass content of Cl in the active layer of the modified electrode and the protective film is 300 ppm to 500 ppm.

[0047] In some embodiments of this application, the protective film comprises a C1-C50 fluoroalkylsiloxane film, the total mass content of Si in the active layer of the modified electrode and the protective film is 250 ppm to 400 ppm, and the total mass content of F in the active layer of the modified electrode and the protective film is 500 ppm to 750 ppm.

[0048] In some embodiments of this application, the protective film comprises a C1-C50 thiol film, and the mass content of element S in the active layer of the modified electrode and the protective film is 100 ppm to 300 ppm.

[0049] The above test results are obtained by employing the ICP test method.

[0050] Because the modified electrode plate surface of this application has hydrophobic groups exposed, the contact angle of the modified electrode plate is larger than the contact angle of the electrode plate. For example, if the protective film of this application is not installed, the electrode plate is relatively hydrophilic, so its water contact angle is 0°. After installing the protective film of this application, the contact angle clearly increases, and this change in contact angle also proves the adhesion method of the protective film on the electrode plate of this application. In some embodiments of this application, the water contact angle of the modified electrode plate is 65° to 85°. It is explained that the larger the contact angle, the better the density of the protective film and the better the protective effect on the electrode plate.

[0051] The above contact angle test method shall be carried out using a contact angle measuring instrument in accordance with the GB / T 14210 method.

[0052] On the other hand, after surface self-assembled monolayer (SAM) treatment, the BET specific surface area of ​​the electrode plate decreases slightly. The main reason for this is that SAM is formed by chemical bond adsorption, and according to the SAM formation principle, such a film is dense and uniform, which reduces the BET specific surface area. In some embodiments, the BET range of the modified electrode plate is 2.0 to 3.0 m². 2 It is / g.

[0053] In some embodiments of this application, the protective film is a self-assembled film, and more selectively, a self-assembled monolayer. The self-assembled monolayer formed by the self-assembled monolayer (SAM) is generated by adsorbing first groups from the liquid phase onto the lithium or sodium surface of the electrode plate, and then slowly organizing and aligning hydrophobic groups outward. Initially, when the density of adsorbed molecules on the electrode plate surface of the self-assembled molecules is relatively small, the adsorbed molecules begin to form disordered molecular clusters or ordered two-dimensional planar phases, and then dense, uniform, ordered layered phases with higher molecular coverage. The first groups organize on the electrode plate surface, while the hydrophobic groups organize at locations away from the electrode plate surface. The tightly deposited molecular regions nucleate and grow until the electrode plate surface is covered with a single molecular layer. The reason why adsorbed molecules are easily adsorbed is that they reduce the surface free energy of the electrode plate surface and are stabilized by strong chemisorption or electrostatic adsorption of the first groups. Furthermore, because the primary group of such a self-assembled monolayer has a strong chemical bond, it can achieve uniform self-assembly at the molecular level due to intermolecular interaction forces and strong repulsive forces against the solvent. The denser uniformity of the self-assembled monolayer formed on the electrode surface allows for more effective blocking of water-oxygen from entering the electrode. Moreover, because the formed self-assembled monolayer is a monolayer, it can reach a thickness at the nanometer level. Such a thickness generally does not hinder the transmission of lithium / sodium ions at the interface, does not degrade the dynamic performance of the material, and thus does not affect the electrical properties of the electrode assembly.

[0054] The electrode plate in the modified electrode plate of this application includes a pre-lithified negative electrode plate or a pre-sodiumified negative electrode plate. The composition of the negative electrode plate before pre-lithification or pre-sodiumification should be referred to with that of a conventional negative electrode plate. For example, a conventional negative electrode plate includes a negative electrode current collector and a negative electrode film layer (i.e., the aforementioned active layer) placed on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0055] For example, the negative electrode current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is placed on one or both of the two opposing surfaces of the negative electrode current collector.

[0056] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, the metal foil sheet used in a lithium-ion secondary battery may be copper foil, and the metal foil sheet used in a sodium-ion secondary battery may be aluminum foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material base layer (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0057] In some embodiments, the negative electrode active material may be a negative electrode active material used in batteries known in the art. For example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicone-based materials, tin-based materials, and lithium titanate. The silicone-based material may be selected from at least one of elemental silicone, silicone oxide, silicone-carbon composite, silicone-nitrogen composite, and silicone alloy. The tin-based material may be selected from at least one of elemental tin, tin oxide, and tin alloy. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may be used. These negative electrode active materials may be used individually or in combination of two or more. Those skilled in the art may select an appropriate negative electrode active material from the above materials for lithium-ion or sodium-ion secondary batteries depending on the secondary battery actually used, and this application does not describe such selection further here.

[0058] In some embodiments, the negative electrode film layer further selectively includes an adhesive. For example, the adhesive may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0059] In some embodiments, the negative electrode film layer further selectively includes a conductive agent. For example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0060] In some embodiments, the negative electrode film layer further selectively includes other auxiliary agents, such as thickeners, such as sodium carboxymethylcellulose (CMC-Na).

[0061] In some embodiments, a conventional negative electrode plate can be manufactured by the following method. Components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other component, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry. The negative electrode slurry is then coated onto a negative electrode current collector, and after processes such as drying and cold pressing, a conventional negative electrode plate is obtained.

[0062] The negative electrode plate in the modified negative electrode plate of this application may be a prelithified negative electrode plate obtained by a conventional prelithiation method or a presodium negative electrode plate obtained by a conventional presodium method, and the protective film may have different specific performance in different types of negative electrode plates, but in all cases it can provide good protection to the electrode plate. In some embodiments of this application, the prelithified negative electrode plate includes one or more of metallic lithium prelithified negative electrode plates, lithium alloy prelithified negative electrode plates, or organic lithium prelithified negative electrode plates, or the presodium negative electrode plate includes one or more of metallic sodium presodium negative electrode plates or organic sodium presodium negative electrode plates. This application does not describe in detail the prelithiation method for the prelithified negative electrode plate or the presodium method for the presodium negative electrode plate, and those skilled in the art can implement them by referring to conventional prelithiation or presodium methods.

[0063] [Manufacturing method for modified electrodes] A second embodiment of this application further provides a method for manufacturing the modified electrode plate, comprising: producing a protective solution containing a first group and a hydrophobic group; and immersing an electrode plate having sodium or lithium elements on its surface in the protective solution for a predetermined time, thereby adsorbing the first group onto the electrode plate surface, allowing the hydrophobic group to detach from the electrode plate and form a protective film, thereby obtaining a modified electrode plate.

[0064] The above manufacturing method is easy to operate, highly adaptable, and can be applied to the modification of various electrode plates. The protective film formed using the protective agent effectively blocks water and oxygen from reaching the electrode plate.

[0065] When treating electrode plates in a protective agent solution, the treatment method clearly affects the efficiency of protective film formation. To improve the dispersibility of the protective agent on the electrode plate surface and the efficiency of protective film formation, we tried the above treatment using stirring or ultrasonic methods, but found that the protective film formation effect was relatively poor and the battery capacity clearly decreased. When the electrode plates were immersed in the protective agent solution for a predetermined time, we found that the efficiency of protective film formation was relatively high and relatively uniform, the battery capacity was maintained before and after the protective film was applied, and the protective effect of the protective film before and after hydro-oxygen treatment allowed the battery to maintain a relatively high capacity.

[0066] This is because, during the pre-sodium or pre-lithiumization process, an incomplete SEI film is formed on the surface of the electrode plate, and this SEI film itself is relatively fragile and easily broken and peeled off. When the electrode plate is processed after pre-sodium or pre-lithiumization by stirring or ultrasonic treatment, the external force from stirring or ultrasonic treatment causes significant damage to the incomplete SEI film, altering its chemical properties and leading to peeling. This degrades sodium ion transmission, reduces battery capacity, and the peeling of the SEI film also affects the adhesion of the protective agent to the electrode plate surface. Therefore, even if a protective film is subsequently formed on the electrode plate surface, it cannot compensate for the defects caused by the peeling of the SEI film.

[0067] When the protective agent is a self-assembling monomolecule, it can form a self-assembling monomolecule.

[0068] In some embodiments of this application, the solvent of the protective agent solution includes an ether-based solvent, and selectively, the ether-based solvent includes ethylene glycol dimethyl ether (DME), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (TRGDME), tetraethylene glycol dimethyl ether (TEGDME), tetrahydrofuran (THF), methyltetrahydrofuran (Me-THF), or 1,3-dioxolane (DOL). Because the potential of the negative or positive electrode plate after pre-sodium / lithification is relatively low and the reducing properties are relatively strong, the chemical reaction between the protective agent solution and the electrode plate can be controlled by employing the above-mentioned ether-based solvent with strong anti-reducing properties.

[0069] In some embodiments of this application, the concentration of the protective agent solution is 0.01 wt% to 5 wt%, and selectively 0.5 wt% to 3 wt%. By adjusting the concentration of the protective agent solution, the density and mass of the formed protective film can be adjusted. If the concentration of the protective agent is too high, deposition will occur in the formed protective film, the uniformity of the protective film will be poor, and the efficiency of the hydrophobic effect will be reduced. If the concentration of the protective agent is too low, the efficiency of the protective film formation will be relatively low, the density will be relatively low, and the protective effect on the electrode plate will not be ideal. By controlling the concentration of the protective agent solution, when the protective agent used is attached to the electrode plate surface, it is possible to attach it in the form of a monolayer that is as uniform and dense as possible, thereby improving the performance of the hydrophobic effect. In some embodiments, the concentration of the protective agent solution is 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0070] In some embodiments of this application, the predetermined time is 2 min to 30 min, and selectively 10 min to 20 min. Within the predetermined time, the protective agent molecules gradually self-repair through continuous adsorption-desorption to the electrode surface, reaching dynamic equilibrium and forming a protective film. With increasing time, the amount of protective agent adhering increases, the solidity of adhesion increases, and a self-assembled monolayer can be formed. If the time is continuously extended, molecular stacking appears based on the self-assembled monolayer, further increasing the adhesion density, but this reduces the uniformity of the protective film, affects the hydrophobic action of the hydrophobic groups within it, and lowers the hydrophobic efficiency. In some embodiments, the predetermined time is selectively 2 min, 5 min, 10 min, 15 min, 20 min, 25 min, or 30 min.

[0071] [Positive electrode plate] The positive electrode plate generally includes a positive electrode current collector and a positive electrode film layer (i.e., the aforementioned active layer) placed on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0072] For example, a positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is placed on one or both of the two opposing surfaces of the positive electrode current collector.

[0073] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material base layer (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0074] In some embodiments, when the positive electrode plate is the positive electrode plate of a lithium-ion battery, the positive electrode active material may adopt a positive electrode active material used in batteries known in the art. For example, the positive electrode active material may include at least one material among lithium-containing phosphates having an olivine structure, lithium transition metal oxides, and modified compounds thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides are lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which may be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which may be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which may be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which may be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which may be abbreviated as NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.8 Co 0.15 Al 0.05It may include, but is not limited to, at least one of O2) and its modified compounds. Examples of lithium-containing phosphates with an olivine structure include, but is not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), composite materials of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.

[0075] In some embodiments, when the positive electrode plate is the positive electrode plate of a lithium-ion battery, the positive electrode active material may be a positive electrode active material used in batteries known in the art. For example, the positive electrode active material may include at least one material from sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, this application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for sodium-ion batteries may also be used.

[0076] As an optional technical application of this invention, in a sodium transition metal oxide, the transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. The sodium transition metal oxide is, for example, Na x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, 0 <x≦1である。

[0077] As an optional technical option in this application, polyanionic compounds include sodium ions, transition metal ions, and tetrahedral (YO4) compounds. n- The compound may have an anionic unit. The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y may be at least one of P, S, and Si, and n may be (YO4) n- This represents the valence of [something].

[0078] Polyanionic compounds include sodium ions, transition metal ions, and tetrahedral (YO4) ions. n- The compound may have an anionic unit and a halogen anion. The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y may be at least one of P, S, and Si, and n may be (YO4) n- This represents the valency, and the halogen may be at least one of F, Cl, and Br.

[0079] Polyanionic compounds include sodium ions, tetrahedral (YO4) type. n- Anion unit, polyhedral unit (ZO y ) m+ And may be compounds having selective halogen anions. Y may be at least one of P, S and Si, and n is (YO4) n- The valency is represented by Z, Z represents a transition metal which may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, and m is (ZO y ) m+ This represents the valency, and the halogen may be at least one of F, Cl, and Br.

[0080] Examples of polyanionic compounds include NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7), NaM'PO4F (where M' is one or more of V, Fe, Mn, and Ni), and Na3(VO y )2(PO4)2F 3-2y It is at least one of the following (0 ≤ y ≤ 1).

[0081] Prussian blue compounds include sodium ions, transition metal ions, and cyanide ions (CN - The compound may have ). The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. The Prussian blue compound may be, for example, Naa Me b Me' c (CN)6, where Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 <a≦2、0<b<1、0<c<1である。

[0082] In some embodiments, the positive electrode film layer further selectively includes an adhesive. For example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0083] In some embodiments, the positive electrode film layer further selectively includes a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0084] In some embodiments, a positive electrode plate can be manufactured by the following method. Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other component, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is then coated onto a positive electrode current collector, and after processes such as drying and cold pressing, a positive electrode plate is obtained.

[0085] [Electrolyte] The electrolyte plays a role in conducting ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and it can be selected according to the needs. For example, the electrolyte may be a liquid, a gel, or all-solid.

[0086] In some embodiments, the electrolyte is a liquid and comprises an electrolyte salt and a solvent.

[0087] When used in lithium-ion batteries, in some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, or lithium tetrafluoro(oxalato)phosphate. In some embodiments, the solvent includes at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, or diethyl sulfone.

[0088] When used in sodium-ion batteries, in some embodiments, the electrolyte salt includes at least one of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium perchlorate, sodium bisfluorosulfonylimide, sodium bistrifluoromethanesulfonylimide, sodium trifluoromethanesulfonate, sodium difluorophosphate, sodium difluoro(oxalato)borate, or sodium bis(oxalato)borate. In some embodiments, the solvent includes at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, or diethyl sulfone.

[0089] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include negative electrode film forming additives, positive electrode film forming additives, and further additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, or additives that improve the battery's high-temperature or low-temperature performance.

[0090] [Separator] In some embodiments, the secondary battery further includes a separator. This application does not particularly limit the type of separator, and any known porous separator having good chemical and mechanical stability may be selected.

[0091] In some embodiments, the material of the separator is at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. If the separator is a multilayer composite film, the materials of each layer may be the same or different, and is not particularly limited.

[0092] In some embodiments, the positive electrode plate, negative electrode plate, and separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0093] In some embodiments, the secondary battery includes secondary battery cells, or includes a battery module and a battery pack.

[0094] In some embodiments, the secondary battery may include an outer casing. This casing may be used to package the electrode assembly and electrolyte.

[0095] In some embodiments, the casing of the secondary battery may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case. The casing of the secondary battery may also be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0096] This application does not particularly limit the shape of the secondary battery cell, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows a secondary battery cell 5 with a rectangular structure as an example.

[0097] In some embodiments, referring to Figure 2, the casing may include a case 51 and a top cover assembly 53. The case 51 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing and forming a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the top cover assembly 53 can cover the opening to seal the housing cavity. The positive electrode plate, negative electrode plate and separator can form an electrode assembly 52 by a winding or lamination process. The electrode assembly 52 is packaged within the housing cavity. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery cell 5 may be one or more, and a person skilled in the art can specifically select according to actual needs.

[0098] In some embodiments, the secondary battery cells may be assembled into a battery module, and the number of secondary battery cells included in the battery module may be one or more, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0099] Figure 3 shows an example of a battery module 4. Referring to Figure 3, in the battery module 4, the multiple secondary battery cells 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple secondary battery cells 5 may be fixed in place with fasteners.

[0100] Selectively, the battery module 4 may further include a housing having a housing space, in which a plurality of secondary battery cells 5 are housed.

[0101] In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0102] Figures 4 and 5 show an example of a battery pack 1. Referring to Figures 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, the upper housing 2 covering the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0103] Furthermore, this application provides a power consumption device, the power consumption device including a secondary battery according to this application. The secondary battery may be used as a power source for the power consumption device, or as an energy storage unit for the power consumption device. The power consumption device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0104] As the power consumption device, a secondary battery cell, battery module, or battery pack can be selected according to the usage demand.

[0105] Figure 6 shows an example of a power consumption device. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high output and high energy density of the secondary battery of this power consumption device, a battery pack or battery module may be used.

[0106] [Examples] The following describes examples of the present application. The examples described below are illustrative and are used solely for interpreting this application and should not be understood as limitations thereon. Where specific techniques or conditions are not explicitly stated in the examples, they shall be carried out in accordance with the techniques or conditions or product descriptions described in the literature in the art. Unless the manufacturer of the reagents or equipment used is specified, they are all conventional products available on the market.

[0107] Some of the raw material records in the examples are as follows:

[0108] [Table 0]

[0109] Example 1 Manufacturing of the negative electrode plate: Hard carbon (negative electrode active material), carbon black (conductive agent), styrene-butadiene rubber (SBR) (adhesive), and sodium carboxymethylcellulose (CMC-Na) (thickener) are dissolved in deionized water in a weight ratio of 96.2:0.8:0.8:1.2. A negative electrode slurry is obtained by the action of a vacuum mixer. The negative electrode slurry is uniformly coated onto copper foil, the copper foil is dried at room temperature, then transferred to a 120°C oven and dried for 4 hours, and finally cold-pressed and slit to obtain a negative electrode plate with a negative electrode film layer. The coating amount per unit area is 0.17 g / 1540.25 mm 2 That is the case.

[0110] Pre-sodium treatment of the negative electrode plate: Biphenyl (3.7 g) and Na metal (0.55 g) were added to 30 mL of tetrahydrofuran (THF) to prepare a 0.8 mol / L solution, which was then stirred at room temperature for 24 hours to obtain a pre-sodium solution. The prepared negative electrode plate was placed in the prepared pre-sodium solution, immersed for 3 minutes, then removed, washed three times with ethylene glycol dimethyl ether (DME), and vacuum-dried at 120°C for 2 hours to obtain a pre-sodium negative electrode plate.

[0111] Installation of protective film: The pre-sodium-treated negative electrode plate produced in the above process was immersed in a protective agent solution for a predetermined time. The solvent was DME, and the concentration of the protective agent and the predetermined time were recorded in Table 1. After immersion, the electrode plate was removed, washed with DME, and dried to produce a modified negative electrode plate.

[0112] Examples 2-18 The only difference from Example 1 is that some materials or parameters in the protective film installation process were changed, as shown in Table 1. Everything else is the same as in Example 1.

[0113] Example 19 The negative electrode plate manufactured in Example 1 was subjected to pre-sodium treatment using the following method: The dried hard carbon electrode plate was assembled into a button cell, and sodium absorption was performed by discharging with a current of 0.05C. Discharge was stopped when the cutoff voltage reached 0.05V, and the hard carbon electrode plate after sodium absorption was disassembled and washed with dimethyl carbonate (DMC) to obtain the pre-sodium hard carbon electrode plate.

[0114] A protective film was applied to the obtained pre-sodium-treated negative electrode plate using the protective film application conditions of Example 1 to obtain the modified negative electrode plate of Example 19.

[0115] Comparative Example 1 The negative electrode plate manufactured in Example 1 was used as the negative electrode plate for Comparative Example 1.

[0116] Comparative Example 2 The pre-sodium-treated negative electrode plate manufactured in Example 1 was used as the negative electrode plate for Comparative Example 2.

[0117] Comparative Example 3 The pre-sodium-treated negative electrode plate from Example 1 was again immersed in a 5 wt% fluoroethylene carbonate DME solution, immersed for 3 minutes, then removed, immediately washed three times with DME, dried, and subjected to a film-forming additive treatment to obtain the pre-sodium-treated negative electrode plate.

[0118] Comparative Example 4 The only difference from Example 1 is that the protective film is stirred at 800 rpm during the installation process.

[0119] Comparative Example 5 The only difference from Example 1 is that the protective film installation process is modified to simultaneously perform ultrasonic treatment with a power of 2000W.

[0120] [Table 1]

[0121] Button battery manufacturing: Manufacturing of sodium-ion battery positive electrode plates: Sodium vanadium phosphate, conductive carbon black SP, and adhesive PVDF, which are the positive electrode active materials, are dispersed in the solvent N-methylpyrrolidone (NMP) in a weight ratio of 90:10:10 and uniformly mixed to obtain a positive electrode slurry. The positive electrode slurry is uniformly applied to the aluminum foil of the positive electrode current collector, dried, and cold-pressed to obtain a positive electrode plate. The coating amount per unit area is 0.27 g / 1540.25 mm 2 That is the case.

[0122] Preparation of sodium-ion battery electrolyte: In an argon gas atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were uniformly mixed in a volume ratio of 3:7 to form an organic solvent. NaPF6 lithium salt was added and dissolved in the organic solvent, and the mixture was uniformly stirred to obtain the electrolyte. The mass content of NaPF6 in the electrolyte was 12.5%.

[0123] Separator: A polypropylene film was used as the separator.

[0124] Manufacturing of sodium-ion batteries The dried negative electrode plate was placed in a glove box. The negative electrode shell was removed, an elastic piece was placed inside the negative electrode shell with the concave side of the elastic piece facing upwards, and 6-8 drops of the electrolyte were injected into the negative electrode shell using a disposable syringe. The gasket and sodium sheet were then pressed together with a stick adhesive and placed inside the negative electrode shell with the sodium sheet facing upwards. The separator was placed over the sodium sheet, and 2-4 drops of the electrolyte were injected onto the separator. The positive electrode shell with the positive electrode plate was placed over the negative electrode shell, and the positive electrode shell was pressed down with tweezers to completely embed the negative electrode shell into the positive electrode shell. The assembled battery was placed in the mold of a sealing machine, and the hydraulic arm was shaken to seal the positive and negative electrode shells, resulting in the manufactured button battery.

[0125] The negative electrode plates obtained in Examples 1-19 and Comparative Examples 1-5 were adopted as the negative electrode plates for a sodium-ion battery, the battery was assembled, and the following tests were performed.

[0126] 1. The elemental composition of the negative electrode film layer and protective film of the negative electrode plates finally obtained in Examples 1-19 and Comparative Examples 1-5 was analyzed by inductively coupled plasma (ICP) spectroscopy, and the analysis results of important elements in the protective film are recorded in Table 2.

[0127] 2. BET test: The positive electrode plates were crushed, and the specific surface area of ​​the solid material was measured according to the GB / T 19587-2004 gas adsorption BET method.

[0128] 3. Contact Angle Test: The hydrophilicity of the negative electrode plate surface obtained in Examples 1-19 and Comparative Examples 1-5 was tested using a contact angle measuring instrument according to the GB / T 14210 method.

[0129] 4. Button battery capacity test: The negative electrode side of the button battery was discharged to 5mV with a constant current of 0.05C, left to stand for 5 minutes, discharged to 5mV with a constant current of 50 μA, left to stand for 5 minutes, and finally discharged to 5mV with a constant current of 10 μA, left to stand for 5 minutes, and then charged to 2.0V with a constant current of 0.05C. The charge / discharge gram capacity and corresponding Coulomb efficiency of the modified negative electrode plate for the first cycle were obtained.

[0130] 5. Air stability evaluation 1) The negative electrode plate of Comparative Example 2 was placed in a constant humidity environment of 10% RH for 48 hours, then re-vacuum dried at 120°C for 1 hour, and then assembled into a button cell according to the above method.

[0131] 2) After placing the negative electrode plate with the protective film attached in each embodiment under constant humidity conditions of 10% RH for 48 hours, it was re-vacuum dried at 120°C for 1 hour, and then the button cell was assembled according to the above method.

[0132] The button batteries assembled in Part 5 according to the methods of Part 4 described above were tested, and the charge capacity, discharge capacity, and Coulomb efficiency of the negative electrode plate after the hydro-oxygen treatment were obtained for the first cycle. These results were then compared with the test results from Part 4 to evaluate the effect of hydro-oxygen in air on the modified negative electrode plate.

[0133] The results of each test are recorded in Table 2.

[0134] [Table 2-1] [Table 2-2]

[0135] NG indicates that the test could not be performed.

[0136] As can be seen from the comparison between Comparative Examples 1 and 2 in Table 2, after pre-sodium treatment of the negative electrode plate, the charge gram capacity of the negative electrode plate in the first cycle was equivalent before hydro-oxygen treatment, and the discharge gram capacity in the first cycle after pre-sodium treatment was clearly higher. However, the charge / discharge gram capacity and Coulomb efficiency in the first cycle of Comparative Example 2 after hydro-oxygen treatment were both clearly affected.

[0137] As can be seen from the comparison of Comparative Examples 1, 2, and 3 in Table 2, in Comparative Example 3, after treatment with a film-forming additive, the charge / discharge gram capacity in the first cycle increased in all cases, but the degradation compared to the charge / discharge gram capacity before pre-sodium treatment was evident, explaining that the water-oxygen protection effect of this treatment method is not ideal.

[0138] As can be seen from the comparison between each example and Comparative Example 2 in Table 2, the protective film installation method of this application does not have a significant adverse effect on the charge / discharge gram capacity and Coulomb efficiency of the pre-sodium-treated anode plate in the first cycle, and provides a clear and effective protective effect on the anode plate after pre-sodium treatment. The charge / discharge gram capacity and Coulomb efficiency of the modified anode plate in the first cycle after hydro-oxygen treatment are clearly improved compared to the pre-sodium-treated anode plate of Comparative Example 2. Furthermore, as can be seen from the comparison with Comparative Example 3, the installation of the protective film of this application allows the pre-sodium-treated anode plate to fully exhibit its charge / discharge gram capacity in the first cycle, and also improves its Coulomb efficiency.

[0139] As can be seen from the comparison of Examples 1 to 7 in Table 2, within a certain range, the greater the amount of protective agent used, the larger the contact angle and the clearer the improvement in the hydrophobicity of the pre-sodium-treated negative electrode plate.

[0140] As can be seen from the comparison of Example 1, Comparative Example 4, and Comparative Example 5, by adopting an immersion method when forming the protective film, the protective film formation effect was improved, the contact angle was increased, and the improvement in hydrophobicity was more evident.

[0141] Example 20 Manufacturing of graphite negative electrode plates: Graphite (negative electrode active material), carbon black (conductive agent), styrene-butadiene rubber (SBR) (adhesive), and sodium carboxymethylcellulose (CMC-Na) (thickener) are dissolved in deionized water (solvent) in a weight ratio of 96.2:0.8:0.8:1.2. A negative electrode slurry is obtained using a vacuum mixer. The negative electrode slurry is uniformly coated onto copper foil, and after drying the copper foil at room temperature, it is transferred to a 120°C oven for 4 hours. Finally, the plates are cold-pressed and slit to obtain graphite negative electrode plates. The coating amount per unit area is 0.17 g / 1540.25 mm². 2 That is the case.

[0142] Pre-lithiation treatment of graphite electrodes: Biphenyl (3.7 g) and Li metal (0.167 g) were added to 30 mL of THF to prepare a 0.8 mol / L solution, which was then stirred at room temperature for 24 hours to obtain a pre-lithiation solution. The manufactured graphite negative electrode was placed in the prepared pre-lithiation solution, immersed for 3 minutes, then removed, washed three times with DME, and vacuum-dried at 120°C for 2 hours to obtain a pre-lithified negative electrode.

[0143] Application of protective film: The pre-lithified negative electrode plate produced in the above process was immersed in a protective agent solution for a predetermined time. The solvent was DME, and the composition of the protective agent and the predetermined time were recorded in Table 3. After immersion, the electrode plate was removed, washed with DME, and dried to produce a modified negative electrode plate.

[0144] Examples 21-36 The only difference from Example 20 is that some materials or parameters in the protective film installation process were changed, as shown in Table 3. Everything else is the same as in Example 20.

[0145] Example 37 The negative electrode plate fabricated in Example 20 was subjected to pre-lithiation treatment using the following method: The dried graphite electrode plate was assembled into a button cell, discharge lithium absorption was performed using a current of 0.05C, discharge was stopped when the cutoff voltage reached 0.5V, and the graphite electrode plate after lithium absorption was disassembled, washed with dimethyl carbonate (DMC), and a pre-sodium hard carbon electrode plate was obtained.

[0146] The obtained pre-lithified negative electrode plate was subjected to protective film application using the protective film application conditions of Example 20 to obtain the modified negative electrode plate of Example 37.

[0147] Comparative Example 6 The negative electrode plate manufactured in Example 20 was used as the negative electrode plate for Comparative Example 6.

[0148] Comparative Example 7 The pre-lithium-ionized negative electrode plate manufactured in Example 20 was used as the negative electrode plate in Comparative Example 7.

[0149] Comparative Example 8 The pre-lithified negative electrode plate from Example 20 was again immersed in a 5 wt% fluoroethylene carbonate DME solution, removed after 3 minutes, immediately washed three times with DME, dried, and then subjected to a film-forming additive treatment to obtain the pre-lithified negative electrode plate.

[0150] [Table 3]

[0151] Button battery manufacturing: Manufacturing of lithium-ion battery positive electrode plates: Lithium iron phosphate, conductive carbon black SP, and adhesive PVDF, which are the positive electrode material active materials, are dispersed in the solvent N-methylpyrrolidone (NMP) in a weight ratio of 97:1.5:1.5 and uniformly mixed to obtain a positive electrode slurry. The positive electrode slurry is uniformly applied to the aluminum foil of the positive electrode current collector, dried, and cold-pressed to obtain a positive electrode plate. The coating amount per unit area is 0.27 g / 1540.25 mm². 2 That is the case.

[0152] Manufacturing of lithium-ion battery electrolyte: In an argon gas atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were uniformly mixed in a volume ratio of 3:7, lithium LiPF6 salt was added and dissolved in the organic solvent, and the mixture was uniformly stirred to obtain the electrolyte. The mass content of LiPF6 in the electrolyte was 12.5%.

[0153] Separator: A polypropylene film was used as the separator.

[0154] Manufacturing of lithium-ion batteries The dried negative electrode plate was placed in a glove box. The negative electrode shell was removed, an elastic piece was placed inside the negative electrode shell with the concave side of the elastic piece facing upwards, and 6-8 drops of the electrolyte were injected into the negative electrode shell using a disposable syringe. The gasket and lithium sheet were then pressed together with a stick adhesive and placed inside the negative electrode shell with the lithium sheet facing upwards. The separator was placed over the lithium sheet, and 2-4 drops of the electrolyte were injected onto the separator. The positive electrode shell with the positive electrode plate was placed over the negative electrode shell, and the positive electrode shell was pressed down with tweezers to completely embed the negative electrode shell into the positive electrode shell. The assembled battery was placed in the mold of a sealing machine, and the hydraulic arm was shaken to seal the positive and negative electrode shells, resulting in the manufactured button battery.

[0155] The negative electrode plates finally obtained in Examples 20-37 and Comparative Examples 6-8 were adopted as negative electrode plates for lithium-ion button batteries, and ICP tests, BET tests, contact angle tests, button battery capacity tests, and air stability evaluations were performed according to the method described above.

[0156] The test results are recorded in Table 4.

[0157] [Table 4-1] [Table 4-2]

[0158] NG indicates that the test could not be performed.

[0159] As can be seen from the comparison between Comparative Examples 6 and 7 in Table 4, after pre-lithification of the negative electrode plate, the charge gram capacity of the negative electrode plate in the first cycle was equivalent before hydro-oxygen treatment, and the discharge gram capacity in the first cycle after pre-lithification treatment was clearly higher. However, the charge / discharge gram capacity and Coulomb efficiency in the first cycle of Comparative Example 7 after hydro-oxygen treatment were both clearly affected.

[0160] As can be seen from the comparison of Comparative Examples 6, 7, and 8 in Table 4, in Comparative Example 8, after treatment with a film-forming additive, the charge / discharge gram capacity in the first cycle all increased, but the degradation compared to the charge / discharge gram capacity before pre-lithification was evident, explaining that the water-oxygen protection effect of this treatment method is not ideal.

[0161] As can be seen from the comparison between each example and Comparative Example 7 in Table 4, the protective film installation method of this application does not have any significant adverse effect on the charge / discharge gram capacity and coulomb efficiency of the pre-lithified negative electrode plate in the first cycle, and provides a clear and effective protective effect on the negative electrode plate after pre-lithification. The charge / discharge gram capacity and coulomb efficiency of the modified negative electrode plate in the first cycle after hydro-oxygen treatment are clearly improved compared to the pre-lithified negative electrode plate of Comparative Example 7. Furthermore, as can be seen from the comparison with Comparative Example 8, the installation of the protective film of this application allows the pre-lithified negative electrode plate to fully exhibit its charge / discharge gram capacity in the first cycle, and also improves its coulomb efficiency.

[0162] As can be seen from the comparison of Examples 20-26 in Table 4, within a certain range, the greater the amount of protective agent used, the larger the contact angle and the clearer the improvement in the hydrophobicity of the pre-lithium-ionized negative electrode plate.

[0163] While this application has been described with reference to preferred embodiments, various improvements can be made thereto, and components therein can be replaced with equivalents, without departing from the scope of this application. In particular, each technical feature referred to in each embodiment can be combined in any manner, provided that no structural conflicts exist. This application is not limited to the specific embodiments disclosed herein, but includes all technical ideas included in the claims. [Explanation of Symbols]

[0164] 1. Battery pack, 2. Upper casing, 3. Lower casing, 4. Battery module, 5. Secondary battery cell, 5. 1. Case, 5. 2. Electrode assembly, 5. 3. Top cover assembly.

Claims

1. Modified electrode plate, An electrode plate having a sodium element or a lithium element on its surface, and including a pre-lithium-ionized negative electrode plate or a pre-sodium-ionized negative electrode plate, A modified electrode plate comprising a protective film containing a first group and a hydrophobic group, wherein the first group is attached to the surface of the electrode plate, the hydrophobic group is separated from the electrode plate, and the hydrophobic group is exposed on the surface of the protective film.

2. The first group includes one or more of the following: a phosphoric acid group, a silyl halogenated group, a siloxane group, a thiol group, a carboxylic acid group, or -N=N-, and / or The modified electrode plate according to claim 1, wherein the hydrophobic group comprises one or more of the following: a C6-C20 aryl group, a C1-C50 alkyl group, or a C1-C50 haloalkyl group.

3. The modified electrode plate according to any one of claims 1 to 2, wherein the hydrophobic group comprises one or more of a C6-C10 aryl group, a C1-C40 alkyl group, or a C1-C30 haloalkyl group.

4. The modified electrode plate according to any one of claims 1 to 3, wherein the protective film comprises one or more of the following: a C1-C50 alkylphosphonate film, a C1-C50 alkylchlorosilane film, a C1-C50 fluoroalkylsiloxane film, a C1-C50 thiol film, or a benzotriazole film.

5. The modified electrode plate according to claim 4, wherein the protective film comprises one or more of the following: a C1-C40 alkylphosphonate film, a C1-C30 alkylchlorosilane film, a C1-C30 fluoroalkylsiloxane film, or a C1-C10 thiol film.

6. The C1-C40 alkylphosphonate membrane comprises one or more of the following: a propylphosphonate membrane, an octadecylphosphonate membrane, or a dihexadecylphosphonate membrane, or The C1-C30 alkylchlorosilane film includes one or more of the following: n-propyltrichlorosilane film, isopropyltrichlorosilane film, n-butyltrichlorosilane film, tert-butyltrichlorosilane film, n-hexyltrichlorosilane film, n-heptyltrichlorosilane film, tridecyltrichlorosilane film, tetradecyltrichlorosilane film, octadecyltrichlorosilane film, or tricosyltrichlorosilane film. The C1-C30 fluoroalkylsiloxane film comprises one or more of the heptadecafluorodecyl-trimethoxysilane film and the trifluoropropane-trimethoxysilane film, or The modified electrode plate according to claim 5, wherein the C1-C10 thiol film comprises one or more of the following: an n-propylthiol film, an ethylthiol film, an isopropylthiol film, an n-butylthiol film, a tert-butylthiol film, an n-pentylthiol film, an n-hexylthiol film, and an n-decylthiol film.

7. The modified electrode plate includes a current collector and an active layer installed on at least one surface of the current collector, and the protective film is attached on the active layer. The protective film comprises a C1-C50 alkylphosphonate film, and the mass content of element P in the active layer of the modified electrode plate and the protective film is 300 ppm to 500 ppm, or The protective film comprises a C1-C50 alkylchlorosilane film, the mass content of Si element in the total elements of the active layer of the modified electrode and the protective film is 250 ppm to 400 ppm, and the mass content of Cl element in the total elements of the active layer of the modified electrode and the protective film is 300 ppm to 500 ppm, or The protective film comprises a C1-C50 fluoroalkylsiloxane film, the mass content of Si element in the total elements of the active layer of the modified electrode and the protective film is 250 ppm to 400 ppm, and the mass content of F element in the total elements of the active layer of the modified electrode and the protective film is 500 ppm to 750 ppm, or The modified electrode according to any one of claims 1 to 6, wherein the protective film comprises a C1-C50 thiol film, and the mass content of element S in the active layer and protective film of the modified electrode is 100 ppm to 300 ppm.

8. The modified electrode plate according to any one of claims 1 to 7, wherein the water contact angle of the modified electrode plate is 65° to 85°.

9. The modified electrode plate according to any one of claims 1 to 8, wherein the protective film is a self-assembled monolayer.

10. The aforementioned pre-lithium-ionized negative electrode plate includes one or more of the following: a metallic lithium pre-lithium-ionized negative electrode plate, a lithium alloy pre-lithium-ionized negative electrode plate, or an organic lithium pre-lithium-ionized negative electrode plate. The modified electrode plate according to any one of claims 1 to 9, wherein the pre-sodium-based anode plate includes one or more of the following: a metallic sodium pre-sodium-based anode plate, an electrochemical pre-sodium-based anode plate, or an organosodium pre-sodium-based anode plate.

11. A method for manufacturing a modified electrode plate according to any one of claims 1 to 10, To produce a protective agent solution containing a first group and a hydrophobic group, A manufacturing method comprising immersing an electrode plate having a sodium element or a lithium element on its surface in the protective agent solution for a predetermined time, causing the first group to adhere to the surface of the electrode plate, the hydrophobic group to separate from the electrode plate and form a protective film, thereby obtaining the modified electrode plate.

12. The manufacturing method according to claim 11, wherein the solvent of the protective agent solution includes an ether-based solvent.

13. The manufacturing method according to any one of claims 11 to 12, wherein the ether-based solvent includes ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, methyltetrahydrofuran, or 1,3-dioxolane.

14. The manufacturing method according to any one of claims 11 to 13, wherein the concentration of the protective agent solution is 0.01 wt% to 5 wt%.

15. The manufacturing method according to claim 14, wherein the concentration of the protective agent solution is 0.5 wt% to 3 wt%.

16. The manufacturing method according to any one of claims 11 to 15, wherein the predetermined time is 2 min to 30 min.

17. The manufacturing method according to claim 16, wherein the predetermined time is 10 min to 20 min.

18. A secondary battery comprising a positive electrode plate, a negative electrode plate, and an electrolyte, wherein the positive electrode plate or the negative electrode plate includes a modified electrode plate according to any one of claims 1 to 10.

19. A power consumption device including a secondary battery, wherein the secondary battery includes the secondary battery described in claim 18.

Images