Electrode tab, method of manufacturing the same, secondary battery, and electric device

Abstract

Embodiments of the present application provide an electrode tab, a preparation method thereof, a secondary battery and an electric device. The electrode tab comprises a current collector, an active material layer arranged on at least one surface of the current collector, an insulation layer arranged on the active material layer, and a coating layer arranged on the insulation layer, wherein the coating layer comprises an ion capturing agent, and the ion capturing agent has a reduction potential of 0-2 V relative to lithium metal. The cycle performance of the secondary battery comprising the electrode tab is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to an electrode tab, a preparation method thereof, a secondary battery and a power utilization device. BACKGROUND

[0002] In recent years, secondary batteries are widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. due to their high energy density and cyclic performance. With the great development and wide application of secondary batteries, higher requirements are put forward for their electrochemical performance.

[0003] Therefore, how to provide a secondary battery with good performance is an urgent technical problem to be solved. SUMMARY

[0004] The present application is made in view of the above technical problems, and aims to provide an electrode tab, a preparation method thereof, a secondary battery and a power utilization device, and the cyclic performance of the secondary battery containing the electrode tab is improved.

[0005] In a first aspect, the present application provides an electrode tab, comprising: a current collector; an active material layer disposed on at least one surface of the current collector; an insulating layer disposed on the active material layer; and a coating layer disposed on the insulating layer, wherein the coating layer comprises an ion capturing agent, and the reduction potential of the ion capturing agent relative to lithium metal is 0-2V.

[0006] In the present application, the coating layer of the electrode tab comprises an ion capturing agent, and the reduction potential of the ion capturing agent relative to lithium metal is 0-2V. The positive electrode material is an important component of the secondary battery, and directly affects the performance of the secondary battery. The positive electrode material containing transition metal will inevitably cause the phenomenon of transition metal ion dissolution in the electrochemical environment. On the one hand, the dissolved transition metal ions destroy the structural stability of the original positive electrode material, thereby affecting the service life of the secondary battery. On the other hand, the dissolved transition metal ions will migrate and deposit on the surface of the negative electrode material, catalyze the decomposition and regeneration of the electrolyte and the negative electrode interface film, continuously consume the reversible active metal, and ultimately lead to the decline of the performance of the secondary battery. In the technical solution of the present application, the reduction potential of the ion capturing agent in the coating layer of the electrode tab relative to lithium metal is 0-2V, and the reduction potential of the transition metal ion relative to lithium metal is generally above 2V. Therefore, the ion capturing agent can reduce the dissolved transition metal ions in the secondary battery into low-valence ions that are not easy to dissolve, or into metal elements, thereby improving the situation of catalyzing the decomposition of the electrolyte and the negative electrode interface film by the transition metal ions, and improving the cyclic performance of the secondary battery. In addition, since the H +The reduction potential of lithium metal relative to lithium is higher than that of transition metal ions relative to lithium metal; therefore, ion scavengers can also remove H+ from battery cells. + Reduction, in other words, removes acidic substances (such as HF, organic acids, and RH) from the electrolyte. + The ion-scavenging agent (H· free radicals, etc.) further enhances the performance of the secondary battery. The electrode plates are coated with an ion-scavenging agent, and an insulating layer is used to isolate the active material layer from the coating. This reduces the possibility of direct contact between the ion-scavenging agent and the electrode active material, thereby reducing the risk of the ion-scavenging agent losing its redox activity and also reducing the risk of the ion-scavenging agent affecting the performance of the electrode active material.

[0007] In one possible implementation, the ion scavenger comprises at least one compound of an active metal and an alkali metal. Optionally, the active metal comprises at least one of Li, Na, K, Rb, Cs, Fr, Mg, Ca, Sr, Ba, Al, Ti, or V; alternatively, the active metal comprises at least one of Li, Na, Mg, Al, Ti, or V; alternatively, the alkali metal compound comprises A. 1 x B, A 2 y Ti5O 12 and at least one of the compounds represented by formula (I), formula (II) or formula (III):

[0008] RA 3 (I)

[0009] Among them, A 1 A 2 A 3 A 4 A 5 A 6 Each of the following elements independently includes at least one of Li, Na, or K; B includes C, Si, or Sn; x ≥ 0.05; y > 4; and R, R1, R2, R3, and R4 each independently include a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms substituted with a sulfonic acid group or a sulfonyl group, an alkenyl group having 2 to 20 carbon atoms substituted with a sulfonic acid group or a sulfonyl group, or an alkenyl group having 6 carbon atoms. At least one of the following: an aryl group having 6 to 26 carbon atoms substituted with an aryl group, a sulfonic acid group, or a sulfonyl group; a carboxyl group having 1 to 20 carbon atoms substituted with an aryl group, a sulfonic acid group, or a sulfonyl group; a carbonyl group having 1 to 20 carbon atoms substituted with an aryl group, a aryloxy group having 6 to 26 carbon atoms substituted with an aryl group, a sulfonic acid group, or a sulfonyl group; and an aryloxy group having 6 to 26 carbon atoms substituted with an aryl group, a 26- ...

[0010] In one possible implementation, the A 1 x B includes Li 1 / 6 C, Na 1 / 6 C, K 1 / 8 C, Li 4.4 Si, or Li 4.4 At least one of Sn.

[0011] In one possible implementation, 5 ≤ y ≤ 7, the A 2 y Ti5O 12 Including Li7Ti5O 12 or Na7Ti5O 12 At least one of them.

[0012] In one possible implementation, the compound represented by formula (I) includes at least one of n-butyllithium, naphthyllithium, or biphenyllithium.

[0013] In one possible implementation, the compound represented by formula (II) includes At least one of them.

[0014] In one possible implementation, the compound represented by formula (III) includes At least one of them.

[0015] In one possible implementation, the ion trapping agent accounts for 50% to 99% of the mass of the coating; alternatively, the ion trapping agent accounts for 80% to 98% of the mass of the coating.

[0016] Within the given range, the ion scavenger in the coating can effectively reduce transition metal ions, thereby further improving the cycle performance of the battery.

[0017] In one possible implementation, the thickness d1 of the coating is 0.01 μm to 20 μm, and optionally, d1 is 0.1 μm to 10 μm.

[0018] If the coating thickness is too small, the content of ion scavengers within the electrode sheet is too low, and the ion scavengers cannot effectively perform their function of chemically reducing transition metal ions. If the coating thickness is too large, it will hinder the migration of active metal ions in the active material of the electrode sheet, thus degrading the performance of the secondary battery, for example, affecting its cycle performance. Therefore, setting the coating thickness to 0.01 μm to 20 μm is beneficial for improving the performance of the secondary battery.

[0019] In one possible implementation, the thickness d2 of the insulating layer is 0.01 μm to 20 μm, and optionally, d2 is 0.1 μm to 10 μm.

[0020] If the insulation layer is too thin, it cannot effectively isolate the ion trapping agent and the electrode active material; if the insulation layer is too thick, it will hinder the migration of active metal ions in the active material of the electrode, thus degrading the performance of the secondary battery, such as affecting its cycle performance. Therefore, setting the insulation layer thickness to 0.01 μm to 20 μm is beneficial to improving the performance of the secondary battery.

[0021] In one possible implementation, the coating further includes an adhesive; optionally, the adhesive includes at least one of polyacrylate, polyacrylic acid, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-trichloroethylene copolymer, polyvinylpyrrolidone, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, polyacrylonitrile, polyvinyl alcohol, polyethylene, polypropylene, starch, or cyanoethyl amylopectin.

[0022] The ion scavenger in the coating can be bonded to the active material layer by the adhesive, so that there is good adhesion between the ion scavenger and the active material layer, thereby improving the overall structural strength of the electrode sheet.

[0023] In one possible implementation, the coating further includes a filler;

[0024] Optionally, the filler comprises at least one of inorganic particles, organic particles, or organometallic framework materials; optionally, the inorganic particles comprise at least one of inorganic particles having a dielectric constant of 5 or greater, or inorganic particles having ionic conductivity but not storing ions; optionally, the organic particles comprise at least one of polycarbonate, polythiophene, polypyridine, polystyrene, polyacrylic wax, polyethylene, polypropylene, cellulose, cellulose modifier, melamine resin, phenolic resin, polyester, silicone resin, polyimide, polyamide-imide, polyarylamide, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyaryletherketone, or a copolymer of butyl acrylate and ethyl methacrylate; optionally, the organometallic framework material comprises at least one of nitrogen-containing heterocyclic ligand structures, organic carboxylic acid ligand structures, and nitrogen-oxygen mixed ligand structures.

[0025] Adding fillers to the coating creates channels for ions to pass through, thereby improving the cycle performance of the secondary battery.

[0026] In one possible implementation, the insulating layer comprises at least one of inorganic particles, organic particles, or an organometallic framework material; optionally, the inorganic particles comprise at least one of inorganic particles having a dielectric constant of 5 or greater, or inorganic particles having ionic conductivity but not storing ions; optionally, the organic particles comprise at least one of polycarbonate, polythiophene, polypyridine, polystyrene, polyacrylic wax, polyethylene, polypropylene, cellulose, cellulose modifier, melamine resin, phenolic resin, polyester, silicone resin, polyimide, polyamide-imide, polyarylamide, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyaryletherketone, or a copolymer of butyl acrylate and ethyl methacrylate; optionally, the organometallic framework material comprises at least one of nitrogen-containing heterocyclic ligand structures, organic carboxylic acid ligand structures, and nitrogen-oxygen mixed ligand structures.

[0027] The insulating materials provided by the above technical solutions all have good insulating properties and can play a good role in electronic insulation and isolating ion scavengers and electrode active materials.

[0028] In a second aspect, a method for preparing an electrode sheet is provided, comprising: providing a current collector; providing an active material slurry, coating the active material slurry onto at least one surface of the current collector to form an active material layer; providing an insulating slurry, coating the insulating slurry onto the active material layer to form an insulating layer; providing a coating slurry, the coating slurry comprising an ion scavenger, the ion scavenger having a reduction potential of 0 to 2V relative to lithium metal, and coating the coating slurry onto the insulating layer to obtain an electrode sheet.

[0029] Thirdly, a secondary battery is provided, including electrode plates as described in the first aspect and any possible implementation thereof.

[0030] Fourthly, an electrical device is provided, comprising the secondary battery described in the third aspect.

[0031] This application provides an electrode sheet whose coating includes an ion scavenger, and the reduction potential of the ion scavenger relative to lithium metal is 0-2V. The positive electrode material is a crucial component of a secondary battery, directly affecting its performance. However, positive electrode materials containing transition metals inevitably experience the dissolution of transition metal ions in an electrochemical environment. On one hand, the dissolved transition metal ions disrupt the structural stability of the original positive electrode material, thus affecting the battery's lifespan. On the other hand, the dissolved transition metal ions migrate and deposit on the surface of the negative electrode material, catalyzing the decomposition and regeneration of the electrolyte and negative electrode interface film, continuously consuming reversible active metals, ultimately leading to a decline in the secondary battery's performance. In the technical solution of this application, the ion scavenger in the electrode sheet coating has a reduction potential of 0-2V relative to lithium metal, while the reduction potential of transition metal ions relative to lithium metal is generally above 2V. Therefore, the ion scavenger can reduce the dissolved transition metal ions in the secondary battery to less soluble low-valence ions, or reduce them to elemental metals, thereby improving the catalytic decomposition of the electrolyte and negative electrode interface film by transition metal ions, thus enhancing the cycle performance of the secondary battery. Furthermore, due to H... + The reduction potential of lithium metal relative to lithium is higher than that of transition metal ions relative to lithium metal; therefore, ion scavengers can also remove H+ from battery cells. + Reduction, in other words, removes acidic substances (such as HF, organic acids, and RH) from the electrolyte. + The ion-scavenging agent (H· free radicals, etc.) further enhances the performance of the secondary battery. The electrode plates are coated with an ion-scavenging agent, and an insulating layer is used to isolate the active material layer from the coating. This reduces the possibility of direct contact between the ion-scavenging agent and the electrode active material, thereby reducing the risk of the ion-scavenging agent losing its redox activity and also reducing the risk of the ion-scavenging agent affecting the performance of the electrode active material. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of an electrode sheet according to an embodiment of this application;

[0034] Figure 2 This is a schematic diagram of an electrode sheet according to an embodiment of this application;

[0035] Figure 3 This is a schematic diagram of an electrode sheet according to an embodiment of this application;

[0036] Figure 4 This is a schematic diagram of a method for preparing an electrode sheet according to an embodiment of this application;

[0037] Figure 5 This is a schematic diagram of a secondary battery disclosed in an embodiment of this application;

[0038] Figure 6 This is an exploded structural diagram of a secondary battery disclosed in an embodiment of this application;

[0039] Figure 7 This is a schematic diagram of the structure of a battery module disclosed in one embodiment of this application;

[0040] Figure 8 This is an exploded structural diagram of a battery pack disclosed in an embodiment of this application;

[0041] Figure 9 This is a schematic diagram of an electrical device disclosed in an embodiment of this application.

[0042] The accompanying drawings are not drawn to scale. Detailed Implementation

[0043] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the electrode plates, battery cells, batteries, and power-consuming devices of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0044] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0047] Unless otherwise specified, the terms "comprising" and "including" as used in this application are open-ended. For example, "comprising" and "including" may mean including or containing other components not listed.

[0048] Unless otherwise specified, the term "and / or" is inclusive in this application. For example, the phrase "A and / or B" means "A, B, or both A and B". More specifically, the condition "A and / or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0049] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0050] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0051] Unless otherwise specified, the following terms have the following meanings. Any undefined terms have their technically accepted meanings.

[0052] "Alkyl" refers to a monovalent saturated hydrocarbon group having one or more carbon atoms, optionally with 1 to 20 carbon atoms. For example, alkyl groups include straight-chain hydrocarbon groups and branched hydrocarbon groups, such as methyl (CH3-), ethyl (CH3CH2-), n-propyl (CH3CH2CH2-), isopropyl ((CH3)2CH-), n-butyl (CH3CH2CH2CH2-), isobutyl ((CH3)2CHCH2-), sec-butyl ((CH3)(CH3CH2)CH-), tert-butyl ((CH3)3C-), n-pentyl (CH3CH2CH2CH2CH2-), neopentyl ((CH3)3CCH2-), etc.

[0053] "Alkenyl" refers to a straight-chain or branched hydrocarbon group having one or more carbon atoms and at least one unsaturated double bond site, optionally with 2 to 20 carbon atoms. Examples include vinyl (CH2=CH-), propenyl (CH3CH=CH-), allyl (CH2=CH-CH2-), and n-butenyl (-CH3CH2CH=CH-).

[0054] "Aryl" refers to an aromatic compound having a single ring or multiple condensed rings, optionally with 6 to 26 carbon atoms. Examples of aryl compounds include phenyl, naphthyl, and indene. Aryl compounds also include monocyclic compounds fused with an aryl group, such as tetrahydronaphthyl and 2,3-dihydroindene.

[0055] "Carboxyl group" refers to a group having one or more carbon atoms and a -CO2H functional group, optionally having 1 to 20 carbon atoms.

[0056] "Carbonyl" refers to a group having one or more carbon atoms and a -CO- functional group, optionally having 1 to 20 carbon atoms.

[0057] "Aryloxy group" refers to a group formed by connecting at least one carbon atom on the aromatic ring of an aryl group with an oxygen atom, optionally having 6 to 26 carbon atoms.

[0058] "Sulfonic acid group" refers to -SO3H.

[0059] "Sulfoyl" refers to RS(=O)2-, where R includes hydrogen atoms, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclic, etc.

[0060] A rechargeable battery is a battery that can be recharged after discharge to reactivate its active materials and continue to be used. Typically, a rechargeable battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The separator, positioned between the positive and negative electrodes, serves as a barrier. The electrolyte, acting as a conductor of ions, lies between the positive and negative electrodes.

[0061] Due to their high energy density and cycleability, rechargeable batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields. With the significant development and widespread application of rechargeable batteries, higher requirements have been placed on their energy density, cycle performance, discharge capacity, and other performance characteristics.

[0062] Cathode materials are one of the key materials determining the performance of secondary batteries. They mainly include metal oxides and polyanionic salts, among which layered metal oxides and spinel-type metal oxides containing transition metals are widely used as cathode materials. These cathode materials containing transition metals have advantages such as high energy density and good cycle performance, which are beneficial for improving the performance of secondary batteries. However, in the electrochemical environment, transition metal ion dissolution is inevitable in cathode materials containing transition metals. On the one hand, the dissolved transition metal ions disrupt the structural stability of the original cathode material, thus affecting the lifespan of the secondary battery. On the other hand, the dissolved transition metal ions migrate and deposit on the surface of the anode material, catalyzing the decomposition and regeneration of the electrolyte and anode interface film, continuously consuming reversible active metals, ultimately leading to a decline in the performance of the secondary battery.

[0063] In view of this, embodiments of this application provide an electrode sheet comprising a current collector; an active material layer disposed on at least one surface of the current collector; an insulating layer disposed on the active material layer; and a coating disposed on the insulating layer, wherein the coating comprises an ion scavenger. The ion scavenger has a reduction potential of 0–2V relative to lithium metal, while the reduction potential of transition metal ions relative to lithium metal is generally above 2V. Therefore, the ion scavenger can reduce the transition metal ions dissolved in the secondary battery into low-valence ions that are not easily dissolved, or reduce them into elemental metals, thereby improving the catalytic decomposition of the electrolyte and negative electrode interface film by transition metal ions, and thus improving the cycle performance of the secondary battery. Furthermore, due to H… + The reduction potential of lithium metal relative to lithium is higher than that of transition metal ions relative to lithium metal; therefore, ion scavengers can also remove H+ from battery cells. + Reduction, in other words, removes acidic substances (such as HF, organic acids, and RH) from the electrolyte. +The ion-scavenging agent (H· free radicals, etc.) further enhances the performance of the secondary battery. The electrode plates are coated with an ion-scavenging agent, and an insulating layer is used to isolate the active material layer from the coating. This reduces the possibility of direct contact between the ion-scavenging agent and the electrode active material, thereby reducing the risk of the ion-scavenging agent losing its redox activity and also reducing the risk of the ion-scavenging agent affecting the performance of the electrode active material.

[0064] [Electrode Plate]

[0065] Figure 1 This is a schematic diagram of an electrode plate 1 according to an embodiment of this application. Figure 1 As shown, the electrode 1 includes a current collector 11, an active material layer 12 disposed on at least one surface of the current collector 11, an insulating layer 14 disposed on the active material layer 12, and a coating layer 13 disposed on the insulating layer 14. For example, along the thickness direction of the electrode 1 (e.g., ... Figure 1 In the z-direction of lithium metal, a current collector 11, an active material layer 12, an insulating layer 14, and a coating layer 13 are sequentially arranged. The coating layer 13 includes an ion trapping agent, and the reduction potential of the ion trapping agent relative to lithium metal is 0–2V.

[0066] The electrode plates provided in the embodiments of this application can be either positive or negative electrode plates.

[0067] The ion scavengers described here refer to a class of substances capable of consuming free transition metal ions in a secondary battery. The reduction potential of ion scavengers relative to lithium metal is 0–2V, while the reduction potential of transition metal ions relative to lithium metal is generally above 2V. Therefore, the reducing power of ion scavengers is stronger than that of transition metal ions. Ion scavengers can reduce free transition metal ions into lower valence states that are not easily dissolved in the electrolyte, or reduce them to elemental metals.

[0068] The cathode material is a crucial component of rechargeable batteries, directly impacting their performance. However, cathode materials containing transition metals inevitably experience transition metal ion dissolution in the electrochemical environment. On one hand, these dissolved transition metal ions disrupt the structural stability of the original cathode material, affecting battery life. On the other hand, they migrate and deposit on the surface of the anode material, catalyzing the decomposition and regeneration of the electrolyte and anode interfacial film, continuously consuming reversible active metals, ultimately leading to a decline in battery performance. To address this, the electrode sheets are coated with an ion-scavenging agent, and an insulating layer isolates the active material layer from the coating. This reduces the likelihood of direct contact between the ion-scavenging agent and the electrode active material, mitigating the risk of the ion-scavenging agent losing its redox activity and simultaneously reducing the risk of the ion-scavenging agent affecting the performance of the electrode active material.

[0069] For example, cathode materials can include phosphate materials with an olivine structure, materials with a spinel structure, and transition metal oxides with a layered structure. Specifically, examples include lithium iron phosphate (LiFePO4), lithium manganese iron phosphate (LiMnFePO4), lithium manganese oxide (LiMn2O4), and ternary materials. In these cathode materials, iron ions, nickel ions, and manganese ions can all dissolve from the cathode material.

[0070] The electrode coating provided in this application includes an ion scavenger, and the reduction potential of the ion scavenger relative to lithium metal is 0-2V, while the reduction potential of transition metal ions relative to lithium metal is generally above 2V. Therefore, the ion scavenger can reduce the transition metal ions dissolved in the secondary battery into lower valence ions that are not easily dissolved, or reduce them into elemental metals, thereby improving the catalytic decomposition of the electrolyte and negative electrode interface film by transition metal ions, and thus improving the cycle performance of the secondary battery. Furthermore, due to H... + The reduction potential of lithium metal relative to lithium is higher than that of transition metal ions relative to lithium metal; therefore, ion scavengers can also remove H+ from battery cells. + Reduction, in other words, removes acidic substances (such as HF, organic acids, and RH) from the electrolyte. + The effects of H· free radicals, etc., further enhance the performance of secondary batteries.

[0071] It should be understood that in the embodiments of this application, different types of ion traps can be selected according to the different types of free transition metal ions dissolved in the secondary battery.

[0072] Optionally, in some embodiments, the ion scavenger includes at least one of an active metal or an alkali metal compound.

[0073] Specifically, the active metal may include at least one of Li, Na, K, Rb, Cs, Fr, Mg, Ca, Sr, Ba, Al, Ti, or V. Optionally, the active metal may include at least one of Li, Na, Mg, Al, Ti, or V.

[0074] Alternatively, alkali metal compounds include A 1 x B, A 2 y Ti5O 12 and at least one of the compounds represented by formula (I), formula (II) or formula (III):

[0075] RA 3 (I)

[0076] Among them, A 1 A 2A 3 A 4 A 5 A 6 Each of the following elements independently includes at least one of Li, Na, or K; B includes C, Si, or Sn; x ≥ 0.05; y > 4; and R, R1, R2, R3, and R4 each independently include a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms substituted with a sulfonic acid group or a sulfonyl group, an alkenyl group having 2 to 20 carbon atoms substituted with a sulfonic acid group or a sulfonyl group, or an alkenyl group having 6 carbon atoms. At least one of the following: an aryl group having 6 to 26 carbon atoms substituted with an aryl group, a sulfonic acid group, or a sulfonyl group; a carboxyl group having 1 to 20 carbon atoms substituted with an aryl group, a sulfonic acid group, or a sulfonyl group; a carbonyl group having 1 to 20 carbon atoms substituted with an aryl group, a aryloxy group having 6 to 26 carbon atoms substituted with an aryl group, a sulfonic acid group, or a sulfonyl group; and an aryloxy group having 6 to 26 carbon atoms substituted with an aryl group, a 26- ...

[0077] In the embodiments of this application, the dashed line in equation (II) indicates that R1 and R2 can be connected to form a loop or not; the dashed line in equation (III) indicates that R3 and R4 can be connected to form a loop or not.

[0078] Optionally, A 1 x B includes LiC6, NaC6, KC8, and Li 4.4 Si, Li 4.4 Sn or Li 22 At least one of Si5.

[0079] In this embodiment of the application, A 1 x The value of x in B is related to the specific substance of B. For example, when B is carbon (C), the upper limit of the value of x is 1 / 6; and when B is silicon (Si) or tin (Sn), the upper limit of the value of x is 4.4.

[0080] Alternatively, 5≤y≤7, A 2 y Ti5O 12 Including Li7Ti5O 12 or Na7Ti5O 12 At least one of them.

[0081] Optionally, the compound represented by formula (I) includes at least one of n-butyllithium, naphthyllithium, or biphenyllithium.

[0082] Optionally, the compound represented by formula (II) includes At least one of them.

[0083] Optionally, the compound represented by formula (III) includes At least one of them.

[0084] The current collector 11 is a structure for collecting current in the electrode plate 1. Its main function is to collect the current generated by the electroactive material in order to form a larger current for external output. Therefore, the current collector 11 should be in full contact with the active material, and its internal resistance should be as small as possible.

[0085] Optionally, the current collector 11 may be a metal foil or a composite current collector. For example, a composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.). As another example, as a metal foil, the positive electrode current collector may be made of aluminum foil, and the negative electrode current collector may be made of copper foil.

[0086] Optionally, the active material provided by the active material layer 12 may be an active material known in the art for use in secondary batteries. For example, in lithium-ion batteries, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for lithium-ion batteries 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 may include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0087] For example, in lithium-ion batteries, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials in batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0088] The current collector 11 has two surfaces arranged along its thickness direction. Optionally, as... Figure 1 As shown, both surfaces of the current collector 11 are provided with an active material layer 12. On both sides of the current collector 11, along the thickness direction of the electrode sheet 1 (for example, ...), Figure 1 The active material layer 12, insulating layer 14 and coating layer 13 in the z-direction are arranged sequentially.

[0089] Figure 2 This is a schematic diagram of an electrode sheet according to an embodiment of this application. In some other embodiments, such as... Figure 2 As shown, one of the two opposing surfaces of the current collector 11 along the thickness direction is provided with an active material layer 12. On one side of the current collector 11, along the thickness direction of the electrode sheet 1 (for example, ...), Figure 2 The active material layer 12, the insulating layer 14, and the coating layer 13 are arranged sequentially in the z-direction.

[0090] Optionally, in some embodiments, the ion trapping agent accounts for 50% to 99% of the mass of the coating 13; alternatively, the ion trapping agent accounts for 80% to 98% of the mass of the coating 13.

[0091] Specifically, the mass percentage of the ion trapping agent in the coating 13 can be 50%, 60%, 70%, 80%, 90%, 96%, 98%, 99%, or any value between any two of the above.

[0092] Within the given range, the mass ratio of ion scavengers in the porous coating can effectively reduce transition metal ions, thereby further improving the cycle performance of the battery.

[0093] Alternatively, in some embodiments, such as Figures 1-2 As shown, the thickness d2 of the insulating layer 14 is 0.01μm to 20μm, and optionally, d2 is 0.1μm to 10μm.

[0094] Specifically, the thickness d2 of the insulating layer 14 can be 0.01μm, 0.05μm, 0.1μm, 0.5μm, 1μm, 5μm, 10μm, 15μm, 20μm, or any value between any two of the above.

[0095] If the insulation layer is too thin, it cannot effectively isolate the ion trapping agent and the electrode active material; if the insulation layer is too thick, it will hinder the migration of active metal ions in the active material of the electrode 1, thus degrading the performance of the secondary battery, such as affecting its cycle performance. Therefore, setting the thickness of the insulation layer 14 to 0.01 μm to 20 μm is beneficial to improving the performance of the secondary battery.

[0096] Optionally, in some embodiments, the coating 13 may be disposed on at least one side of the surface of the current collector 11. For example, as Figure 3 As shown, both surfaces of the current collector 11 are coated with a coating 13, and the active material layer 12 is disposed on the coating 13. For example, along the thickness direction of the electrode sheet 1 ( Figure 3 In the z-direction), the current collector 11, the coating 13 and the active material layer 12 are arranged in sequence.

[0097] Alternatively, in some embodiments, such as Figures 1-3 As shown, the thickness d1 of coating 13 is 0.01μm to 20μm, and optionally, d1 is 0.1μm to 10μm.

[0098] Specifically, the thickness d1 of the coating 13 can be 0.01μm, 0.05μm, 0.1μm, 0.5μm, 1μm, 5μm, 10μm, 15μm, 20μm, or any value between any two of the above.

[0099] If the coating 13 is too thin, the content of ion scavenger in the electrode 1 is too low, and the ion scavenger cannot effectively reduce transition metal ions through chemical reaction. If the coating 13 is too thick, it will hinder the migration of active metal ions in the active material of the electrode 1, thus degrading the performance of the secondary battery, such as affecting its cycle performance. Therefore, setting the coating 13 thickness to 0.01 μm to 20 μm is beneficial to improving the performance of the secondary battery.

[0100] The thickness of the material can be measured using a micrometer. The thickness of the material is measured at multiple different locations using a micrometer, and the average of the multiple measurements is recorded as the final thickness.

[0101] The material thickness in this embodiment can be measured using the methods described above, but is not limited to the methods described above. For example, it can also be measured using spectroscopy. For specific detection methods, refer to known methods for measuring thickness using spectroscopy.

[0102] Optionally, in some embodiments, coating 13 further includes an adhesive.

[0103] Optionally, the binder includes at least one of polyacrylate, polyacrylic acid, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-trichloroethylene copolymer, polyvinylpyrrolidone, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, polyacrylonitrile, polyvinyl alcohol, polyethylene, polypropylene, starch, or cyanoethyl amylopectin.

[0104] Optionally, in some embodiments, the insulating layer 14 includes at least one of inorganic particles, organic particles, or an organic-metal framework material;

[0105] Optionally, the inorganic particles include at least one of inorganic particles having a dielectric constant of 5 or greater, or inorganic particles having ion conductivity but not storing ions.

[0106] Optionally, the organic particles include at least one of polycarbonate, polythiophene, polypyridine, polystyrene, polyacrylic wax, polyethylene, polypropylene, cellulose, cellulose modifier, melamine resin, phenolic resin, polyester, silicone resin, polyimide, polyamide-imide, polyarylamide, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyaryletherketone, or a copolymer of butyl acrylate and ethyl methacrylate;

[0107] Optionally, the organometallic framework material includes at least one of nitrogen-containing heterocyclic ligand structures, organic carboxylic acid ligand structures, and nitrogen-oxygen mixed ligand structures.

[0108] The insulating materials provided by the above technical solutions all have good insulating properties and can play a good role in electronic insulation and isolating ion scavengers and electrode active materials.

[0109] Optionally, in some embodiments, coating 13 may also include fillers, for example, when the ion trapping agent added to coating 13 is non-particulate, fillers may be added to coating 13 to provide channels for ions to pass through in the coating.

[0110] Optionally, the filler includes at least one of inorganic particles, organic particles, or organic-metal framework materials;

[0111] Optionally, the inorganic particles include at least one of inorganic particles having a dielectric constant of 5 or greater, or inorganic particles having ion conductivity but not storing ions.

[0112] Optionally, the organic particles include at least one of polycarbonate, polythiophene, polypyridine, polystyrene, polyacrylic wax, polyethylene, polypropylene, cellulose, cellulose modifier, melamine resin, phenolic resin, polyester, silicone resin, polyimide, polyamide-imide, polyarylamide, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyaryletherketone, or a copolymer of butyl acrylate and ethyl methacrylate;

[0113] Optionally, the organometallic framework material includes at least one of nitrogen-containing heterocyclic ligand structures, organic carboxylic acid ligand structures, and nitrogen-oxygen mixed ligand structures.

[0114] A filler is added to coating 13 to provide pores for ions to pass through, thereby improving the cycle performance of the secondary battery.

[0115] Optionally, in some embodiments, the active material layer may further include a binder. For example, the binder in the positive electrode active material layer may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0116] For example, the binder in the negative electrode active material layer may include 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).

[0117] Optionally, in some embodiments, the active material layer may further include 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.

[0118] [Electrode preparation method]

[0119] Figure 4 This is a method for preparing a separator membrane according to an embodiment of this application. For example... Figure 4 As shown, the preparation method 500 includes the following steps.

[0120] Step 510, provide a current collector;

[0121] Step 520: Provide an active material slurry and coat the active material slurry onto at least one surface of the current collector to form an active material layer;

[0122] Step 530: Provide an insulating slurry and coat the insulating slurry onto the active material layer to form an insulating layer;

[0123] Step 540: Provide a coating slurry and apply the coating slurry onto the insulating layer to obtain an electrode sheet.

[0124] The coating includes an ion trapping agent with a reduction potential of 0–2V relative to lithium metal.

[0125] The electrode sheets prepared by the above method can improve the cycle performance of secondary batteries when applied to them.

[0126] [Electrolytes]

[0127] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0128] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0129] In some embodiments, the electrolyte salt may be selected from 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 difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0130] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0131] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0132] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0133] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0134] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0135] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 5 This is an example of a square-structured secondary battery 20.

[0136] In some implementations, refer to Figure 6 The outer packaging may include a housing 21 and a cover plate 23. The housing 21 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The housing 21 has an opening communicating with the receiving cavity, and the cover plate 23 can be placed over the opening to close the receiving cavity. The positive electrode, negative electrode, and separator can be formed into an electrode assembly 22 by a winding process or a stacking process. The electrode assembly 22 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 22. The secondary battery 20 may contain one or more electrode assemblies 22, which can be selected by those skilled in the art according to specific practical needs.

[0137] Figure 7 This is a battery module 30 used as an example. (See reference...) Figure 7 The battery module 30 may include multiple secondary batteries 20. These secondary batteries 20 may be arranged sequentially along the length of the battery module 30. Alternatively, they may be arranged in any other manner. Furthermore, the multiple secondary batteries 20 can be secured using fasteners.

[0138] The battery module 30 may also include a housing with a receiving space in which a plurality of secondary batteries 20 are received.

[0139] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0140] Figure 8 This is a sample battery pack 40. (See reference) Figure 8The battery pack 40 may include a housing 41, which has a hollow interior structure, and multiple battery modules 30 are housed within the housing 41. The multiple battery modules 30 can be arranged in any manner within the housing 41.

[0141] In addition, this application also provides an electrical device, which includes at least one of the battery cell, battery module, or battery provided in this application. The battery cell, battery module, or battery can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device 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.

[0142] As for this electrical device, battery cells, battery modules, or batteries can be selected according to its usage requirements.

[0143] Figure 9 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of individual battery cells, batteries or battery modules can be used.

[0144] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0145] [Example]

[0146] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0147] 1. Preparation of positive electrode sheet

[0148] Positive electrode plate 1:

[0149] Provide active material slurry: Dissolve the active material lithium manganese oxide (LiMn2O4), the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) in the solvent N-methylpyrrolidone (NMP) at a mass ratio of 90%:5%:5%. After thorough stirring and mixing, coat the mixture onto Al foil, dry it, and cold press it to obtain the positive electrode sheet 1.

[0150] Positive electrode plate 2:

[0151] Provide insulating paste: Dissolve insulating material aluminum oxide (Al2O3) and binder PVDF in solvent NMP at a mass ratio of 90%:10%, stir and mix thoroughly, and then coat it on the active material layer of positive electrode 1 to form an insulating layer. After drying, positive electrode 2 is obtained, wherein the thickness of the insulating layer is 2μm.

[0152] Positive electrode plate 3:

[0153] Provide coating slurry: ion scavenger Li7Ti5O 12 The binder PVDF is dissolved in the solvent NMP at a mass ratio of 90%:10%. After thorough mixing, the mixture is coated onto the insulating layer of the positive electrode 2 to form a coating, thus obtaining the positive electrode 3, wherein the coating thickness is 2μm.

[0154] Positive electrode 4: The preparation of positive electrode 4 is similar to that of positive electrode 3, except that the coating thickness in positive electrode 4 is 0.01 μm.

[0155] Positive electrode 5: The preparation of positive electrode 5 is similar to that of positive electrode 3, except that the coating thickness in positive electrode 5 is 0.1 μm.

[0156] Positive electrode 6: The preparation of positive electrode 7 is similar to that of positive electrode 3, except that the coating thickness in positive electrode 6 is 10μm.

[0157] Positive electrode 7: The preparation of positive electrode 7 is similar to that of positive electrode 3, except that the coating thickness in positive electrode 7 is 20μm.

[0158] Positive electrode 8: The preparation of positive electrode 8 is similar to that of positive electrode 3, except that the thickness of the insulating layer in positive electrode 8 is 0.01 μm.

[0159] Positive electrode 9: The preparation of positive electrode 9 is similar to that of positive electrode 3, except that the thickness of the insulating layer in positive electrode 9 is 0.1 μm.

[0160] Positive electrode 10: The preparation of positive electrode 10 is similar to that of positive electrode 3, except that the thickness of the insulating layer in positive electrode 10 is 10 μm.

[0161] Positive electrode 11: The preparation of positive electrode 11 is similar to that of positive electrode 3, except that the thickness of the insulating layer in positive electrode 11 is 20 μm.

[0162] Positive electrode 12: The preparation of positive electrode 12 is similar to that of positive electrode 3, except that the coating thickness in positive electrode 12 is 30 μm.

[0163] Positive electrode 13: The preparation of positive electrode 13 is similar to that of positive electrode 3, except that the thickness of the insulating layer in positive electrode 13 is 30 μm.

[0164] Positive electrode 14: The preparation of positive electrode 14 is similar to that of positive electrode 3, except that the ion scavenger in the coating of positive electrode 14 is Li powder.

[0165] Positive electrode 15: The preparation of positive electrode 15 is similar to that of positive electrode 3, except that the ion scavenger in the coating of positive electrode 15 is Li. 1 / 6 C.

[0166] Positive electrode 16: The preparation of positive electrode 16 is similar to that of positive electrode 3, except that the ion scavenger in the coating of positive electrode 16 is n-butyllithium.

[0167] Positive electrode 17: The preparation of positive electrode 17 is similar to that of positive electrode 3, except that the ion scavenger in the coating of positive electrode 17 is...

[0168] Positive electrode 18: The preparation of positive electrode 18 is similar to that of positive electrode 3, except that the ion scavenger in the coating of positive electrode 18 is...

[0169] Positive electrode 19: The preparation of positive electrode 19 is similar to that of positive electrode 3, except that the coating of positive electrode 19 contains inorganic Al2O3 ceramic particles, in which the ion scavenger Li7Ti5O 12 The mass ratio of inorganic Al2O3 ceramic particles to PVDF binder is 50%:40%:10%.

[0170] 2. Preparation of negative electrode sheet

[0171] Negative electrode 1: The active material artificial graphite, the conductive agent acetylene black, and the binder PVDF are dissolved in the solvent NMP at a mass ratio of 90%:5%:5%. After being thoroughly stirred and mixed evenly, the mixture is coated onto Cu foil, dried, and cold-pressed to obtain negative electrode 1.

[0172] Negative electrode 2: The insulating material Al2O3 and the binder PVDF are dissolved in the solvent NMP at a mass ratio of 90%:10%. After being thoroughly stirred and mixed, the mixture is coated onto the negative electrode 1 to obtain the negative electrode 2, wherein the thickness of the insulating layer is 2μm.

[0173] Negative electrode 3: Li7Ti5O ion scavenger 12 The binder PVDF is dissolved in solvent NMP at a mass ratio of 90%:10%, and after being thoroughly stirred and mixed, it is coated onto the negative electrode 2 to obtain the negative electrode 3, wherein the coating thickness is 2μm.

[0174] 2. Preparation of secondary batteries

[0175] [Example 1]

[0176] (1) Positive electrode plate

[0177] The positive electrode sheet is the positive electrode sheet 3 prepared as described above.

[0178] (2) Negative electrode plate

[0179] The negative electrode sheet is the negative electrode sheet 1 prepared as described above.

[0180] (3) Preparation of electrolyte

[0181] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of 30:70, and 1M lithium hexafluorophosphate (LiPF6) electrolyte salt was dissolved to obtain the electrolyte.

[0182] (4) Preparation of the separating membrane

[0183] Conventional polypropylene film is used as the separator.

[0184] (5) Assembly of lithium-ion secondary battery: The positive electrode 3, the separator and the negative electrode 1 are stacked in sequence, so that the separator is between the positive electrode 3 and the negative electrode 1 to play a role in isolation, and then the electrode assembly is wound to obtain the electrode assembly; the electrode assembly is placed in the battery casing, dried and injected with electrolyte, and then processed by formation, standing and other processes to obtain lithium-ion battery 1, as Example 1.

[0185] [Examples 2-17, Comparative Examples 1-2]

[0186] The secondary batteries of Examples 2-17 and Comparative Examples 1-2 are prepared in a similar manner to the secondary battery of Example 1, except that different positive electrode plates are used (positive electrode plate 3-19 is used in Examples 1-17, and positive electrode plate 1-2 is used in Comparative Examples 1-2), as detailed in Table 1.

[0187] [Example 18]

[0188] The preparation method of the secondary battery in Example 18 is similar to that of the secondary battery in Example 1, except that different positive and negative electrode plates are used (wherein, the positive electrode plate 3 and the negative electrode plate 1 are used in Example 1, and the positive electrode plate 1 and the negative electrode plate 3 are used in Example 18), as detailed in Table 1.

[0189] [Example 19]

[0190] The preparation method of the secondary battery in Example 19 is similar to that of the secondary battery in Example 1, except that different negative electrode plates are used (among which, negative electrode plate 1 is used in Example 1 and negative electrode plate 3 is used in Example 19), as detailed in Table 1.

[0191] [Comparative Example 3]

[0192] The preparation method of the secondary battery in Comparative Example 3 is similar to that of the secondary battery in Example 18, except that different negative electrode plates are used (among which, negative electrode plate 3 is used in Example 18 and negative electrode plate 2 is used in Comparative Example 3), as detailed in Table 1.

[0193] 3. Battery performance test

[0194] (1) Battery capacity retention test

[0195] At 45°C, a lithium-ion secondary battery is charged at a constant current of 1C to 4.2V, then charged at a constant voltage of 4.2V until the current is less than 0.05C, and then discharged at a constant current of 1C to 2.8V. This constitutes one charge-discharge cycle. This charging and discharging process is repeated, and the capacity retention rate of the lithium-ion secondary battery after 500 cycles is calculated.

[0196] Among them, the capacity retention rate (%) of lithium-ion secondary battery after 500 cycles at 45℃ = (discharge capacity of the 500th cycle / discharge capacity of the first cycle) × 100%.

[0197] Please refer to Table 1 for the product parameters of different embodiments and comparative examples, as well as the test results of battery performance tests conducted on comparative examples 1-3 and examples 1-19 prepared according to the above method.

[0198] Table 1: Product parameters and test results for comparative examples and different embodiments

[0199]

[0200]

[0201] A comparison of the results of Comparative Examples 1-3 and Examples 1-19 shows that the coating of the electrode sheet contains an ion trap, which significantly improves the cycle performance of the corresponding lithium manganese oxide battery.

[0202] The results of Examples 1-5 and 10 show that when the coating thickness is set within a suitable range, the corresponding lithium manganese oxide battery exhibits better cycle performance improvement. In the embodiments of this application, under the same conditions, the lithium manganese oxide battery exhibits better cycle performance when the coating thickness is in the range of 0.01μm to 20μm.

[0203] The results of Examples 1, 6-9, and 11 show that when the insulation layer thickness is set within a suitable range, the cycle performance of the corresponding lithium manganese oxide battery is improved. In the examples of this application, under the same conditions, the cycle performance of the lithium manganese oxide battery is better when the insulation layer thickness is in the range of 0.01μm to 20μm.

[0204] A comparison of the results of Comparative Examples 1-2 with Examples 1, 12-17 shows that the ion scavenger Li7Ti5O provided in the embodiments of this application... 12 Metallic Li (powdered), Li 1 / 6 C. n-Butyllithium When added separately to lithium manganese oxide batteries, the cycle performance of the lithium manganese oxide batteries is significantly improved.

[0205] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electrode sheet, comprising: current collector; An active material layer is disposed on at least one surface of the current collector; An insulating layer is disposed on the active material layer; A coating is disposed on the insulating layer, and the coating includes an ion trapping agent having a reduction potential of 0~2V relative to lithium metal; The ion scavenger includes Li7Ti5O 12 or Na7Ti5O 12 At least one of them.

2. The electrode sheet according to claim 1, wherein, The ion trapping agent accounts for 50% to 99% of the mass of the coating.

3. The electrode sheet according to claim 1, wherein, The ion trapping agent accounts for 80% to 98% of the mass of the coating.

4. The electrode sheet according to any one of claims 1 to 3, wherein, The thickness d1 of the coating is 0.01µm to 20µm.

5. The electrode sheet according to any one of claims 1 to 3, wherein, The thickness d1 of the coating is 0.1µm to 10µm.

6. The electrode sheet according to any one of claims 1 to 3, wherein, The thickness d2 of the insulating layer is 0.01µm to 20µm.

7. The electrode sheet according to any one of claims 1 to 3, wherein, The thickness d2 of the insulating layer is 0.1µm to 10µm.

8. The electrode sheet according to any one of claims 1 to 3, wherein, The coating further includes an adhesive; the adhesive includes at least one of polyacrylate, polyacrylic acid, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-trichloroethylene copolymer, polyvinylpyrrolidone, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, cellulose acetate, cellulose propionate acetate, cellulose acetate butyrate, polyacrylonitrile, polyvinyl alcohol, polyethylene, polypropylene, and starch.

9. The electrode sheet according to any one of claims 1 to 3, wherein, The coating further includes a filler; the filler includes at least one of inorganic particles, organic particles, or an organometallic framework material.

10. The electrode sheet according to claim 9, wherein, The inorganic particles include at least one of inorganic particles having a dielectric constant of 5 or higher or inorganic particles having ion conductivity but not storing ions. The organic particles include at least one of polycarbonate, polythiophene, polypyridine, polystyrene, polyethylene, polypropylene, cellulose, cellulose modifier, melamine resin, phenolic resin, polyester, silicone resin, polyimide, polyamide-imide, polyarylamide, polyphenylene sulfide, polysulfone, polyethersulfone, polyaryletherketone, or a copolymer of butyl acrylate and ethyl methacrylate. The organometallic framework material includes at least one of nitrogen-containing heterocyclic ligand structures, organic carboxylic acid ligand structures, and nitrogen-oxygen mixed ligand structures.

11. The electrode sheet according to any one of claims 1 to 3, wherein, The insulating layer comprises at least one of inorganic particles, organic particles, or an organic-metal framework material.

12. The electrode sheet according to claim 11, wherein, The inorganic particles include at least one of inorganic particles having a dielectric constant of 5 or higher or inorganic particles having ion conductivity but not storing ions. The organic particles include at least one of polycarbonate, polythiophene, polypyridine, polystyrene, polyethylene, polypropylene, cellulose, cellulose modifier, melamine resin, phenolic resin, polyester, silicone resin, polyimide, polyamide-imide, polyarylamide, polyphenylene sulfide, polysulfone, polyethersulfone, polyaryletherketone, or a copolymer of butyl acrylate and ethyl methacrylate. The organometallic framework material includes at least one of nitrogen-containing heterocyclic ligand structures, organic carboxylic acid ligand structures, and nitrogen-oxygen mixed ligand structures.

13. A method for preparing an electrode sheet, comprising: Provide current collectors; An active material slurry is provided, and the active material slurry is coated on at least one surface of the current collector to form an active material layer; An insulating slurry is provided, and the insulating slurry is coated onto the active material layer to form an insulating layer; A coating slurry is provided, the coating slurry comprising an ion scavenger having a reduction potential of 0-2V relative to lithium metal, the ion scavenger comprising Li7Ti5O. 12 or Na7Ti5O 12 At least one of the following is used to coat the insulating layer with the coating slurry to obtain an electrode sheet.

14. A secondary battery comprising electrode plates according to any one of claims 1 to 12.

15. An electrical device comprising a secondary battery according to claim 14.

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