Electrode material and preparation method therefor, electrode sheet and preparation method therefor, battery and electric device

Abstract

Provided in the present application are an electrode material and a preparation method therefor, an electrode sheet and a preparation method therefor, a battery and an electric device. The electrode material comprises a base material and a first inorganic lithiation substance layer, which coats at least part of the surface of the base material, wherein the base material comprises a pre-lithiated electrode active material; and the first inorganic lithiation substance layer comprises at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

Description

Electrode material and preparation method thereof, electrode plate and preparation method thereof, battery and electrical device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202310628920.7 filed on May 31, 2023, entitled “Electrode material and preparation method thereof, electrode plate and preparation method thereof, battery and electrical device,” and the entire contents of that application are incorporated herein by reference. Technical Field

[0003] The present application relates to an electrode material and a preparation method thereof, an electrode plate and a preparation method thereof, a battery and an electrical device. Background Art

[0004] Secondary batteries rely on the reciprocating intercalation and deintercalation of active ions between the positive and negative electrodes to charge and discharge. They offer outstanding characteristics such as high energy density, long cycle life, zero pollution, and no memory effect. Consequently, secondary batteries, as a clean energy source, have gradually spread from electronic products to large-scale devices such as electric vehicles, aligning with sustainable environmental and energy development strategies. Consequently, higher requirements are being placed on the energy density and cycle performance of secondary batteries.

[0005] Summary of the Invention

[0006] In order to achieve the above-mentioned objectives, the present application provides an electrode material and a preparation method thereof, an electrode plate and a preparation method thereof, a battery and an electrical device. The electrode material and the electrode plate are applied to secondary batteries to improve the energy density and cycle performance of the battery.

[0007] In a first aspect, an embodiment of the present application provides an electrode material, comprising: a substrate, the substrate comprising a pre-lithiation electrode active material; and a first inorganic lithium compound layer coated on at least a portion of the surface of the substrate, the first inorganic lithium compound layer comprising at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0008] Without intending to be bound by any theory or explanation, the electrode materials of the present embodiments comprise a substrate comprising a pre-lithiated electrode active material. The pre-lithiated electrode active material has been pre-embedded with some active lithium ions. During the initial charge or discharge process, the pre-lithiated electrode active material can release active lithium ions, thereby compensating for the loss of active lithium ions during the battery formation process. Compared to related art solutions that directly incorporate a metallic lithium layer on the surface of the negative electrode, the electrode materials of the present embodiments offer the advantage of more uniform lithium replenishment. Furthermore, the electrode materials of the present embodiments comprise a first inorganic lithium compound layer. This first inorganic lithium compound layer, on the one hand, isolates the substrate from air, enhancing the chemical stability of the substrate and thereby maintaining a high lithium replenishment efficiency for the electrode material. Furthermore, the first inorganic lithium compound layer forms a dense, uniform, and stable protective film on the surface of the electrode. This protective film can function similarly to an SEI film, thereby improving the environmental stability of the electrode, reducing the irreversible loss of active lithium ions, and slowing the capacity decay of the secondary battery. Consequently, the electrode materials of the present embodiments, when applied to secondary batteries, can increase the energy density and extend the cycle life of the secondary battery.

[0009] In any embodiment of the present application, the first inorganic lithiate layer includes at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride or lithium sulfide.

[0010] Optionally, based on the total mass of the first inorganic lithiate layer, the first inorganic lithiate layer includes 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

[0011] More optionally, based on the total mass of the first inorganic lithiation layer, the first inorganic lithiation layer includes 70%-90% of lithium nitride, 0-30% of lithium oxide, and 0-10% of lithium sulfide.

[0012] When the first inorganic lithium compound layer has the aforementioned composition, it helps protect the substrate and inhibits side reactions between the substrate and air, thereby maintaining a high lithium replenishment efficiency for the electrode material. Furthermore, when the first inorganic lithium compound layer has the aforementioned composition, when used in a secondary battery, it helps form a uniform, dense, and stable protective film on the electrode surface, thereby further improving the cycling stability of the secondary battery.

[0013] In any embodiment of the present application, the thickness of the first inorganic lithiation layer is 2 nm-5000 nm, and can be optionally 20 nm-1000 nm.

[0014] The thickness of the first inorganic lithium compound layer falling within the given range not only improves the chemical stability of the substrate but also allows the electrode material to maintain a high substrate content. This significantly increases the lithium replenishment efficiency of the electrode material. Furthermore, the thickness of the first inorganic lithium compound layer falling within the above-mentioned suitable range also helps improve the environmental stability of the electrode. This can suppress the capacity decay of the secondary battery and extend the cycle life of the secondary battery.

[0015] In any embodiment of the present application, the volume distribution particle size Dv50 of the electrode material is 0.6 μm-60 μm, and can be optionally 5 μm-15 μm. This facilitates the release of active lithium ions from the electrode material, improves the lithium replenishment efficiency of the electrode material, and thus helps further delay the capacity decay of the secondary battery and extend the cycle life of the secondary battery.

[0016] In any embodiment of the present application, the electrode material is a positive electrode material, and the lithium supplement content of the positive electrode material is 1%-30%, and can be optionally 5%-20%; the lithium supplement content of the positive electrode material is determined by (C1-C 10 ) / C 10 ×100%, where C1 is the actual gram capacity of the positive electrode material in mAh / g, and C 10 The theoretical gram capacity of the positive electrode active material is expressed in mAh / g. This allows the secondary battery to have both good cycle performance and high reliability.

[0017] In any embodiment of the present application, the electrode material is a negative electrode material, and the lithium supplement content of the negative electrode material is 1%-100%, and can be optionally 30%-50%; the lithium supplement content of the negative electrode material is determined by (C 20 -C2) / C 20 ×100%, where C2 is the actual gram capacity of the negative electrode material in mAh / g, and C 20 The theoretical gram capacity of the negative electrode active material is expressed in mAh / g. This allows the secondary battery to have both good cycle performance and high reliability.

[0018] In a second aspect, an embodiment of the present application provides a method for preparing an electrode material, comprising:

[0019] mixing lithium metal with a complexing agent solution to allow the lithium metal and the complexing agent to react to obtain a liquid-phase lithiating agent;

[0020] contacting a liquid-phase lithiating agent with an electrode active material so that the liquid-phase lithiating agent pre-lithiates the electrode active material to obtain a pre-lithiated electrode active material;

[0021] contacting a pre-lithiated electrode active material with a reactant to form a first inorganic lithiation layer on at least a portion of a surface of the pre-lithiated electrode active material to obtain an electrode material;

[0022] The electrode material includes: a substrate, the substrate includes a pre-lithiation electrode active material; and a first inorganic lithium compound layer coated on at least a portion of the surface of the substrate, the first inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0023] The method provided in the embodiment of the present application is simple to operate, has mild conditions and is easy to control. The substrate of the prepared electrode material has been pre-embedded with some active lithium ions. During the first charge or discharge process, the electrode material can release active lithium ions, thereby compensating for the loss of active lithium ions in the battery formation process. In addition, the electrode material prepared by the method of the embodiment of the present application can also form a dense, uniform and stable protective film on the surface of the electrode pole piece through the first inorganic lithium compound layer. The protective film can play a similar role to the SEI film, thereby improving the environmental stability of the electrode, reducing the irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode material prepared in the embodiment of the present application is applied to secondary batteries, which can improve the energy density of the secondary battery and extend the cycle life of the secondary battery.

[0024] In any embodiment of the present application, the preparation method further comprises:

[0025] Providing a complexing reagent solution includes uniformly mixing the complexing reagent and a solvent to obtain the complexing reagent solution.

[0026] Optionally, the complexing reagent includes at least one of naphthalene and its derivatives, biphenyl and its derivatives, phenanthrene and its derivatives, pyrene and its derivatives, fluorene and its derivatives, indene and its derivatives or aromatic hydrocarbon derivatives containing heteroatom functional groups, and more optionally includes at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene or benzophenone.

[0027] Optionally, the solvent includes at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ether compounds and their derivatives, furan compounds and their derivatives, pyran compounds and their derivatives, or esters and their derivatives, and more optionally includes at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

[0028] The complexing agents selected from the above types can react with lithium metal to form a liquid-phase lithiating agent with a low redox potential. As a result, the liquid-phase lithiating agent can more easily pre-lithiate the electrode active material and embed active lithium ions into the electrode active material, thereby facilitating improved lithium replenishment efficiency of the electrode material. Furthermore, using the above-mentioned solvents to dissolve the complexing agents facilitates further adjustment of the redox potential of the liquid-phase lithiating agent within an appropriate range, thereby further improving the efficiency of pre-lithiation and, in turn, improving the lithium replenishment efficiency of the electrode material.

[0029] In any embodiment of the present application, the redox potential of the liquid-phase lithiating agent is 0.05 V-1.5 V, and may be 0.1 V-0.5 V. This can further improve the efficiency of pre-lithiation, thereby improving the lithium replenishment efficiency of the electrode material.

[0030] In any embodiment of the present application, the molar ratio of lithium metal to the complexing agent is (0.5:1)-(10:1), and can be optionally (1:1)-(4:1).

[0031] In any embodiment of the present application, the molar concentration of lithium element in the liquid-phase lithiating agent is 0.01 mol / L-10 mol / L, and can be optionally 0.01 mol / L-5 mol / L.

[0032] When the molar ratio of lithium metal to the complexing agent is within the above range, it not only helps improve the reaction efficiency of lithium metal and the complexing agent, but also helps adjust the lithium content in the liquid-phase lithiating agent to within an appropriate range. When the lithium content in the liquid-phase lithiating agent is within an appropriate range, the pre-lithiation efficiency of the liquid-phase lithiating agent on the electrode active material can be improved.

[0033] In any embodiment of the present application, the molar ratio of lithium element to electrode active material in the liquid-phase lithiating agent is (0.05:1)-(10:1), and can optionally be (0.1:1)-(5:1). Thus, during the battery formation process, the electrode material can release an appropriate amount of active lithium ions to replenish the active lithium ions lost during the initial charge and discharge cycle.

[0034] In any embodiment of the present application, the volume distribution particle size Dv50 of the electrode active material is 0.5 μm-40 μm. This facilitates the release of active lithium ions from the electrode material, improves the lithium replenishment efficiency of the electrode material, and thus helps to further delay the capacity decay of the secondary battery and extend the cycle life of the secondary battery.

[0035] In any embodiment of the present application, the reactants include at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, nitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide or red phosphorus, and can optionally include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide or red phosphorus.

[0036] By selecting appropriate reactants, the composition of the first inorganic lithiation layer can be regulated. A suitable composition of the first inorganic lithiation layer not only helps suppress side reactions between the substrate and air, maintaining high lithium replenishment efficiency for the electrode material, but also helps regulate the composition of the protective film on the electrode surface, thereby improving the stability of the electrode environment. This helps further improve the cycling stability of the secondary battery and extend its cycle life.

[0037] In a third aspect, an embodiment of the present application provides an electrode plate, comprising a current collector and an electrode film layer located on at least one side of the current collector, wherein the electrode film layer comprises an electrode material; the electrode material comprises: a substrate, the substrate comprises a pre-lithiation electrode active material; and a first inorganic lithium compound layer coated on at least a portion of the surface of the substrate, the first inorganic lithium compound layer comprises at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0038] The electrode plate of the third aspect includes an electrode material, and the base material of the electrode material has been pre-embedded with some active lithium ions. During the first charge or discharge process, the electrode material can release active lithium ions, thereby compensating for the loss of active lithium ions during the battery formation process. In addition, the electrode material can also form a dense, uniform and stable protective film on the surface of the electrode plate through the first inorganic lithium compound layer. The protective film can play a similar role to the SEI film, thereby improving the environmental stability of the electrode, reducing the irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode plate of the embodiment of the present application is applied to the secondary battery, which can improve the energy density of the secondary battery and extend the cycle life of the secondary battery.

[0039] In any embodiment of the present application, the electrode plate further includes a second inorganic lithium compound layer attached to at least a portion of the surface of the electrode film layer, and the second inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0040] When the electrode plate further includes a second inorganic lithium compound layer attached to at least a portion of the surface of the electrode film layer, it is beneficial to further improve the stability of the electrode environment during the charge and discharge cycle, thereby improving the cycle stability of the secondary battery.

[0041] In any embodiment of the present application, the first inorganic lithiate layer includes at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride or lithium sulfide.

[0042] Optionally, based on the total mass of the first inorganic lithiate layer, the first inorganic lithiate layer includes 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

[0043] More optionally, based on the total mass of the first inorganic lithiation layer, the first inorganic lithiation layer includes 70%-90% of lithium nitride, 0-30% of lithium oxide, and 0-10% of lithium sulfide.

[0044] When the first inorganic lithium compound layer has the above composition, it helps protect the substrate and inhibits side reactions between the substrate and air, thereby maintaining a high lithium replenishment efficiency for the electrode material. Furthermore, when the first inorganic lithium compound layer has the above composition, it also helps form a uniform, dense, and stable protective film on the surface of the electrode plate, thereby further improving the cycling stability of the secondary battery.

[0045] In a fourth aspect, an embodiment of the present application provides a method for preparing an electrode plate, including method A or method B.

[0046] Method A:

[0047] mixing lithium metal with a complexing agent solution to allow the lithium metal and the complexing agent to react to obtain a liquid-phase lithiating agent;

[0048] contacting a liquid-phase lithiating agent with an electrode active material so that the liquid-phase lithiating agent pre-lithiates the electrode active material to obtain a pre-lithiated electrode active material;

[0049] contacting a pre-lithiated electrode active material with a reactant to form a first inorganic lithiation layer on at least a portion of a surface of the pre-lithiated electrode active material to obtain an electrode material;

[0050] The electrode material includes: a substrate, the substrate including a pre-lithiated electrode active material; and a first inorganic lithium compound layer coated on at least a portion of the surface of the substrate, the first inorganic lithium compound layer including at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide;

[0051] An electrode sheet including an electrode material is prepared.

[0052] Method B:

[0053] Providing an initial electrode sheet, the initial electrode sheet comprising a current collector and an electrode film layer located on at least one side of the current collector, the electrode film layer comprising an electrode active material;

[0054] mixing lithium metal with a complexing agent solution to allow the lithium metal and the complexing agent to react to obtain a liquid-phase lithiating agent;

[0055] contacting a liquid-phase lithiating agent with the electrode film layer so that the liquid-phase lithiating agent pre-lithiates the electrode active material, thereby obtaining a pole piece including the pre-lithiated electrode active material;

[0056] contacting a pole piece including a pre-lithiated electrode active material with a reactant to form a first inorganic lithiation layer on a surface of the pre-lithiated electrode active material, thereby obtaining an electrode pole piece including the electrode material;

[0057] The electrode material includes: a substrate, the substrate includes a pre-lithiation electrode active material; and a first inorganic lithium compound layer coated on at least a portion of the surface of the substrate, the first inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0058] The electrode plate prepared according to method A or method B includes an electrode material, and the substrate of the electrode material has been pre-embedded with some active lithium ions. During the first charge or discharge process, the electrode material can release active lithium ions, thereby compensating for the loss of active lithium ions during the battery formation process. In addition, the electrode material can also form a dense, uniform and stable protective film on the surface of the electrode plate through the first inorganic lithium compound layer. The protective film can play a similar role to the SEI film, thereby improving the environmental stability of the electrode, reducing the irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode plate prepared in the embodiment of the present application is applied to a secondary battery, which can improve the energy density of the secondary battery and extend the cycle life of the secondary battery.

[0059] In any embodiment of the present application, method A and / or method B further comprises:

[0060] Providing a complexing reagent solution includes uniformly mixing the complexing reagent and a solvent to obtain the complexing reagent solution.

[0061] Optionally, the complexing reagent includes at least one of naphthalene and its derivatives, biphenyl and its derivatives, phenanthrene and its derivatives, pyrene and its derivatives, fluorene and its derivatives, indene and its derivatives or aromatic hydrocarbon derivatives containing heteroatom functional groups, and more optionally includes at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene or benzophenone.

[0062] Optionally, the solvent includes at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ether compounds and their derivatives, furan compounds and their derivatives, pyran compounds and their derivatives, or esters and their derivatives, and more optionally includes at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

[0063] The complexing agents selected from the above types can react with lithium metal to form a liquid-phase lithiating agent with a lower redox potential. As a result, the liquid-phase lithiating agent can more easily pre-lithiate the electrode active material and embed active lithium ions in the electrode active material, thereby facilitating the improvement of the lithium replenishment efficiency of the electrode material. Furthermore, the use of the above-mentioned solvents to dissolve the complexing agents is conducive to further adjusting the redox potential of the liquid-phase lithiating agent within an appropriate range, thereby further improving the efficiency of pre-lithiation and, in turn, improving the lithium replenishment efficiency of the electrode plate.

[0064] In any embodiment of the present application, in method A and / or method B, the redox potential of the liquid-phase lithiating agent is 0.05 V-1.5 V, and may be 0.1 V-0.5 V. This can further improve the efficiency of pre-lithiation, thereby improving the lithium replenishment efficiency of the electrode sheet.

[0065] In any embodiment of the present application, in method A and / or method B, the molar ratio of lithium metal to the coordination reagent is (0.5:1)-(10:1), and can be optionally (1:1)-(4:1).

[0066] In any embodiment of the present application, in method A and / or method B, the molar concentration of lithium element in the liquid-phase lithiating agent is 0.01 mol / L-10 mol / L, and can be optionally 0.01 mol / L-5 mol / L.

[0067] When the molar ratio of lithium metal to the complexing agent is within the above range, it not only helps improve the reaction efficiency of lithium metal and the complexing agent, but also helps adjust the lithium content in the liquid-phase lithiating agent to an appropriate range. When the lithium content in the liquid-phase lithiating agent is within an appropriate range, it can improve the pre-lithiation efficiency of the liquid-phase lithiating agent on the electrode active material, thereby improving the lithium replenishment efficiency of the electrode plate.

[0068] In any embodiment of the present application, in method A and / or method B, the molar ratio of lithium element to electrode active material in the liquid-phase lithiating agent is (0.05:1)-(10:1), and can optionally be (0.1:1)-(5:1). Thus, during the battery formation process, the electrode material can release an appropriate amount of active lithium ions to replenish the active lithium ions lost during the initial charge and discharge cycle.

[0069] In any embodiment of the present application, in method A and / or method B, the volume distribution particle size Dv50 of the electrode active material is 0.5 μm to 40 μm. This facilitates the release of active lithium ions from the electrode material, improves the lithium replenishment efficiency of the electrode sheet, and thus helps further delay the capacity decay of the secondary battery and extend the cycle life of the secondary battery.

[0070] In any embodiment of the present application, in method A and / or method B, the reactants include at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, nitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide or red phosphorus, and can optionally include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide or red phosphorus.

[0071] By selecting appropriate reactants, the composition of the first inorganic lithiation layer can be regulated. A suitable composition of the first inorganic lithiation layer not only helps suppress side reactions between the substrate and air, maintaining high lithium replenishment efficiency for the electrode material, but also helps regulate the composition of the protective film on the electrode surface, thereby improving the stability of the electrode environment. This helps further improve the cycling stability of the secondary battery and extend its cycle life.

[0072] In a fifth aspect, embodiments of the present application provide a battery comprising at least one of the electrode material of the first aspect, the electrode material prepared according to the preparation method of the second aspect, the electrode plate of the third aspect, or the electrode plate prepared according to the preparation method of the fourth aspect. Thus, the battery can achieve both high energy density and long cycle life.

[0073] In a sixth aspect, an embodiment of the present application provides an electrical device comprising the battery according to the fifth aspect.

[0074] The electric device according to the embodiment of the present application includes the battery provided in the embodiment of the present application, and thus has at least the same advantages as the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] FIG1 is a schematic diagram of an embodiment of a battery cell of the present application.

[0076] FIG. 2 is an exploded view of the embodiment of the battery cell of the present application shown in FIG. 1 .

[0077] FIG3 is a schematic diagram of an embodiment of a battery module of the present application.

[0078] FIG4 is a schematic diagram of an embodiment of a battery pack of the present application.

[0079] FIG5 is an exploded view of the embodiment of the battery pack of the present application shown in FIG4 .

[0080] FIG6 is a schematic diagram of an electrical device using an embodiment of the battery of the present application as a power source.

[0081] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell; 51 shell; 52 electrode assembly; 53 cover plate. DETAILED DESCRIPTION

[0082] Below, the electrode material and its preparation method, electrode pole piece and its preparation method, battery and electric device of the present application are described in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0083] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0084] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0085] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0086] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0087] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0088] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: 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).

[0089] Herein, derivatives generally refer to products derived from polymers in which hydrogen atoms or atomic groups are replaced by other atoms or atomic groups.

[0090] With the application and promotion of secondary batteries in various electronic products and new energy vehicles and other industries, higher requirements are placed on the energy density and cycle performance of secondary batteries.

[0091] During the initial charge of a secondary battery, a solid electrolyte interface (SEI) film inevitably forms on the surface of the negative electrode active material, causing irreversible consumption of active ions and, consequently, irreversible capacity loss. Furthermore, during the charge-discharge cycle, the SEI film may rupture due to factors such as the expansion of the negative electrode active material. This requires the continuous consumption of active lithium ions to form a new SEI film, further exacerbating the battery's capacity decay, resulting in a reduction in the battery's energy density and a shortened cycle life.

[0092] To this end, the present application provides an electrode material and a preparation method thereof, which can effectively replenish consumed active lithium ions; the present application also provides an electrode plate containing the electrode material and a preparation method thereof, a battery and an electrical device.

[0093] Electrode materials

[0094] In a first aspect, an embodiment of the present application proposes an electrode material, comprising a substrate and a first inorganic lithium compound layer, wherein the first inorganic lithium compound layer is coated on at least a portion of the surface of the substrate; the substrate comprises a pre-lithiation electrode active material, and the first inorganic lithium compound layer comprises at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0095] Without intending to be bound by any theory or explanation, the electrode materials of the present embodiments comprise a substrate comprising a pre-lithiated electrode active material. The pre-lithiated electrode active material has been pre-embedded with some active lithium ions. During the initial charge or discharge process, the pre-lithiated electrode active material can release active lithium ions, thereby compensating for the loss of active lithium ions during the battery formation process. Compared to related art solutions that directly incorporate a metallic lithium layer on the surface of the negative electrode, the electrode materials of the present embodiments offer the advantage of more uniform lithium replenishment. Furthermore, the electrode materials of the present embodiments comprise a first inorganic lithium compound layer. This first inorganic lithium compound layer, on the one hand, isolates the substrate from air, enhancing the chemical stability of the substrate and thereby maintaining a high lithium replenishment efficiency for the electrode material. Furthermore, the first inorganic lithium compound layer forms a dense, uniform, and stable protective film on the surface of the electrode. This protective film can function similarly to an SEI film, thereby improving the environmental stability of the electrode, reducing the irreversible loss of active lithium ions, and slowing the capacity decay of the secondary battery. Consequently, the electrode materials of the present embodiments, when applied to secondary batteries, can increase the energy density and extend the cycle life of the secondary battery.

[0096] The term "pre-lithiated electrode active material" has a meaning well known in the art, and may refer to an electrode active material pre-embedded with active lithium ions. The electrode active material may include an electrode active material known in the art that has not undergone a pre-lithiated treatment, and this application does not limit the specific type of electrode active material. As an example, the electrode active material may include at least one positive electrode active material known in the art, or at least one negative electrode active material known in the art.

[0097] The type of positive electrode active material is not specifically limited; any positive electrode active material known in the art for use in secondary batteries may be used. For example, the positive electrode active material may include at least one of the following: a lithium transition metal oxide, an olivine-structured lithium-containing phosphate, and their respective modified compounds. Examples of lithium transition metal oxides include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Examples of olivine-structured lithium-containing phosphates include, but are not limited to, at least one of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon, and their respective modified compounds. The embodiments of the present application are not limited to these materials; other conventionally known materials that can be used as positive electrode active materials for secondary batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more.

[0098] Alternatively, in some embodiments, the positive electrode active material may include at least one of the following positive electrode active materials: lithium iron phosphate, nickel-cobalt-manganese ternary material, cobalt-free positive electrode material, lithium manganese iron phosphate, and lithium manganese oxide.

[0099] The type of negative electrode active material is not subject to specific restrictions, and negative electrode active materials for secondary batteries known in the art can be used. As an example, the negative electrode active material may include at least one of the following negative electrode active materials: graphite, soft carbon, hard carbon, mesophase carbon microbeads, silicon-based materials, tin-based materials, lithium titanate. Silicon-based materials may include one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloy materials. Tin-based materials may include one or more of elemental tin, tin oxide, and tin alloy materials. The present application is not limited to these materials, and other conventionally known materials that can be used as negative electrode active materials for secondary batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0100] Alternatively, in some embodiments, the negative electrode active material may include at least one of the following negative electrode active materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, phosphorus-based material, and lithium titanate.

[0101] In some embodiments, based on the total mass of the first inorganic lithiate layer, the first inorganic lithiate layer may include 0-80% lithium oxide, 0-100% lithium carbonate, 0-100% lithium fluoride, 0-45% lithium phosphide, 0-90% lithium nitride, and 0-55% lithium sulfide.

[0102] Alternatively, in some embodiments, based on the total mass of the first inorganic lithiate layer, the first inorganic lithiate layer may include 0-100% lithium fluoride, 0-80% lithium oxide, 0-50% lithium nitride, 0-100% lithium carbonate, and 0-55% lithium sulfide.

[0103] In some embodiments, the first inorganic lithiation layer may include at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, or lithium sulfide.

[0104] Optionally, in some embodiments, based on the total mass of the first inorganic lithiate layer, the first inorganic lithiate layer may include 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

[0105] More optionally, in some embodiments, based on the total mass of the first inorganic lithiation layer, the first inorganic lithiation layer may include 70%-90% lithium nitride, 0-30% lithium oxide, and 0-10% lithium sulfide.

[0106] When the first inorganic lithium compound layer has the aforementioned composition, it helps protect the substrate and inhibits side reactions between the substrate and air, thereby maintaining a high lithium replenishment efficiency for the electrode material. Furthermore, when the first inorganic lithium compound layer has the aforementioned composition, when used in a secondary battery, it helps form a uniform, dense, and stable protective film on the electrode surface, thereby further improving the cycling stability of the secondary battery.

[0107] The composition of the first inorganic lithiation layer can be determined by methods and equipment known in the art. As an example, the content of each element (such as O, N, P, S, F, C, Li and other elements) in the first inorganic lithiation layer can be determined by X-ray photoelectron spectroscopy (XPS). According to the ratio of the content of each element and the chemical formula of the inorganic lithiation, the components included in the first inorganic lithiation layer and the content of each component can be determined. As another example, when sampling from a battery, the composition of the first inorganic lithiation layer can also be determined by the following steps: disassembling the battery and taking out the electrode plate; soaking the electrode plate with an organic solvent to remove the electrolyte and additives in the electrode plate; after drying the electrode plate, randomly selecting an area for cross-section, and determining the position of the first inorganic lithiation layer by scanning electron microscopy (SEM) at a magnification of 3000 times or more (for example, 3000 times, 10000 times, or 100000 times, etc.), and the area with the first inorganic lithiation layer distributed in the field of view is selected. The position of the inorganic lithiation layer is marked as the target area; then, an area of ​​a certain size is selected at a magnification of 500 times or more (for example, 500 times or 1000 times) (for example, when the magnification is 500 times, an area of ​​100 μm*100 μm can be selected; when the magnification is 1000 times, an area of ​​10 μm*10 μm can be selected) and an EDS surface scan is performed for 2 minutes to obtain the element types and contents in the target area. The composition of the first inorganic lithiation layer is determined based on the content ratio of each element and the chemical formula of the inorganic lithiation.

[0108] In some embodiments, the thickness of the first inorganic lithiation layer may be 2 nm to 5000 nm, for example, 2 nm, 5 nm, 10 nm, 50 nm, 100 nm, 300 nm, 500 nm, 1000 nm, 2000 nm, 3000 nm, 4000 nm, 5000 nm, or a range consisting of any two of the above values. For example, the thickness of the first inorganic lithiation layer may be 2 nm to 5000 nm, 2 nm to 4000 nm, 2 nm to 3000 nm, 2 nm to 2000 nm, ...

[0109] 1000nm, 5nm-5000nm, 5nm-3000nm, 5nm-1000nm, 5nm-500nm, 5nm-300nm, 10nm-4000nm, 10nm-2000nm, 10nm-500nm, 50nm-

[0110] 5000nm, 50nm-3000nm, 50nm-1000nm, 50nm-500nm and so on.

[0111] Optionally, in some embodiments, the thickness of the first inorganic lithiation layer may be 20 nm-1000 nm, for example, 20 nm, 50 nm, 100 nm, 300 nm, 500 nm, 800 nm, 1000 nm, or a range consisting of any two of the above values. For example, the thickness of the first inorganic lithiation layer can be 20nm-1000nm, 20nm-800nm, 20nm-500nm, 20nm-300nm, 20nm-100nm, 20nm-50nm, 50nm-1000nm, 50nm-800nm, 50nm-500nm, 50nm-300nm, 50nm-100nm, 100nm-1000nm, 100nm-800nm, 100nm-500nm, 100nm-300nm, 300nm-1000nm, 500nm-1000nm and so on.

[0112] Without intending to be bound by any theory or explanation, the thickness of the first inorganic lithium compound layer is within the above-mentioned suitable range. On the one hand, it can effectively isolate the substrate from direct contact with the air, thereby improving the chemical stability of the substrate. On the other hand, it can enable the electrode material to maintain a high substrate content. Thus, the lithium replenishment efficiency of the electrode material can be significantly improved. In addition, the thickness of the first inorganic lithium compound layer is within the above-mentioned suitable range, which also helps to form a dense, uniform and stable protective film on the surface of the electrode plate, thereby further improving the environmental stability of the electrode. Thus, the capacity decay of the secondary battery can be suppressed and the cycle life of the secondary battery can be extended.

[0113] The thickness of the first inorganic lithiation layer has a meaning well known in the art and can be measured using equipment and methods known in the art. For example, the thickness of the first inorganic lithiation layer on the surface of the lithiated material can be observed using a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

[0114] In some embodiments, the volume distribution particle size Dv50 of the electrode material can be 0.6 μm-60 μm, for example, 0.6 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, or a range consisting of any two of the above values. For example, the volume distribution particle size Dv50 of the electrode material can be 0.6 μm-60 μm, 0.6 μm-30 μm, 0.6 μm-10 μm, 0.6 μm-5 μm, 1 μm-50 μm, 1 μm-40 μm, 1 μm-20 μm, 5 μm-55 μm, 5 μm-45 μm, 5 μm-35 μm, 5 μm-25 μm, 5 μm-15 μm, and the like.

[0115] Optionally, in some embodiments, the volume distribution particle size Dv50 of the electrode material can also be 5μm-15μm, for example, it can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, or a range consisting of any two of the above values.

[0116] Without intending to be bound by any theory or explanation, when the volume distribution particle size Dv50 of the electrode material is within the above-mentioned suitable range, the electrode material not only has a suitable lithium ion transmission path, but also has good electrolyte infiltration performance. This facilitates the release of active lithium ions from the electrode material, improves the lithium replenishment efficiency of the electrode material, and thus helps to further delay the capacity decay of the secondary battery and extend the cycle life of the secondary battery.

[0117] The volume distribution particle size Dv50 of the electrode material has a meaning well known in the art, and may represent the particle size corresponding to the cumulative particle size distribution percentage of the electrode material in the volume-based particle size distribution reaching 50%. The volume distribution particle size Dv50 can be measured using equipment and methods known in the art. For example, it can be measured using a laser particle size analyzer (e.g., Malvern Master Size 3000) in accordance with GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method.

[0118] In some embodiments, the electrode material is a cathode material, which may refer to an electrode material whose substrate includes a pre-lithiated cathode active material.

[0119] The lithium supplement content of the positive electrode material may be 1%-30%, for example, 1%, 5%, 10%, 15%, 20%, 25%, 30%, or a range consisting of any two of the above values.

[0120] Optionally, in some embodiments, the lithium supplement content of the positive electrode material can also be 5%-20%, for example, it can be 5%, 8%, 10%, 12%, 15%, 18%, 20%, or a range consisting of any two of the above values.

[0121] The lithium content of the positive electrode material can be calculated by (C1-C 10 ) / C 10 ×100%, where C1 is the actual gram capacity of the positive electrode material in mAh / g, and C 10 It is the theoretical gram capacity of the positive electrode active material, in mAh / g.

[0122] The actual gram capacity C1 of the positive electrode material has a well-known meaning in the art, which may represent the ratio of the capacitance that the positive electrode material can actually release to the mass of the positive electrode material.

[0123] Theoretical gram capacity C of the positive electrode active material 10 The term "positive electrode active material" has a well-known meaning in the art and may represent the ratio of the theoretically released capacity of the positive electrode active material to the mass of the positive electrode active material. The positive electrode active material corresponds to the positive electrode material. For example, when the positive electrode active material is lithium iron phosphate, the positive electrode material includes pre-lithiated lithium iron phosphate and a first inorganic lithium compound layer coated on at least a portion of the surface of the pre-lithiated lithium iron phosphate. When the positive electrode active material is a nickel-cobalt-manganese ternary material, the positive electrode material includes pre-lithiated nickel-cobalt-manganese ternary material and a first inorganic lithium compound layer coated on at least a portion of the surface of the pre-lithiated nickel-cobalt-manganese ternary material.

[0124] Without intending to be bound by any theory or explanation, when a positive electrode material has an appropriate lithium supplementation content, it can release an appropriate amount of active lithium ions when used in the positive electrode of a secondary battery to replenish the active lithium ions lost during the initial charge and discharge cycles, while reducing the risk of lithium plating caused by excessive lithium supplementation. Therefore, the application of positive electrode materials in secondary batteries can enable the secondary batteries to achieve both good cycle performance and high reliability.

[0125] The lithium supplement content of the positive electrode material can be measured by methods and equipment known in the art. The actual gram capacity C1 of the positive electrode material can be measured by equipment and methods known in the art. Those skilled in the art can determine the theoretical gram capacity C1 of the positive electrode active material based on the type and chemical composition of the positive electrode active material. 10 .

[0126] As an example, C1 can be determined by testing the capacity of lithium that can be extracted from the positive electrode material. Specifically, the positive electrode material can be mixed with an appropriate amount of a conductive agent and a binder in a certain proportion to prepare a single-sided coated positive electrode plate. The lithium half-cell is directly charged to the rated voltage using a button-type lithium half-cell to test the extractable lithium capacity CmAh of the positive electrode plate containing m1g of positive electrode material. The actual gram capacity C1 of the positive electrode material can be calculated using the formula C1=C / m1. The above-mentioned rated voltage has a meaning well known in the art, which can represent the rated voltage corresponding to the substrate of the positive electrode material. For example, when the substrate is pre-lithiated lithium iron phosphate, the rated voltage can be 3.8V; when the substrate is a pre-lithiated nickel-cobalt-manganese ternary material, the rated voltage can be 4.2V-4.4V.

[0127] In some embodiments, the electrode material is a negative electrode material, which may refer to an electrode material whose substrate includes a pre-lithiated negative electrode active material.

[0128] The lithium supplement content of the negative electrode material can be 1%-100%, for example, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 80%, 100% or a range consisting of any two of the above values.

[0129] Optionally, in some embodiments, the lithium supplement content of the negative electrode material can also be 30%-50%, for example, it can be 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, or a range consisting of any two of the above values.

[0130] The lithium content of the negative electrode material can be measured by (C 20 -C2) / C 20 ×100%, where C2 is the actual gram capacity of the negative electrode material in mAh / g, and C 20 It is the theoretical gram capacity of the negative electrode active material, in mAh / g.

[0131] The actual gram capacity C2 of the negative electrode material has a well-known meaning in the art, which may represent the ratio of the capacitance that the negative electrode material can actually release to the mass of the negative electrode material.

[0132] Theoretical gram capacity C of negative electrode active material 20 "Negative electrode active material" has a well-known meaning in the art and may represent the ratio of the theoretically released capacity of the negative electrode active material to the mass of the negative electrode active material. The negative electrode active material corresponds to the negative electrode material. For example, when the negative electrode active material is graphite, the negative electrode material includes pre-lithiated graphite and a first inorganic lithium compound layer coated on at least a portion of the surface of the pre-lithiated graphite. When the negative electrode active material is lithium titanate, the negative electrode material includes pre-lithiated lithium titanate and a first inorganic lithium compound layer coated on at least a portion of the surface of the pre-lithiated lithium titanate.

[0133] Without intending to be bound by any theory or explanation, when a negative electrode material has an appropriate amount of lithium replenishment, it can release an appropriate amount of active lithium ions when used in the negative electrode of a secondary battery to replenish the active lithium ions lost during the initial charge and discharge cycle, while reducing the risk of lithium plating caused by excessive lithium replenishment. Therefore, the application of negative electrode materials in secondary batteries can enable the secondary batteries to achieve both good cycle performance and high reliability.

[0134] The lithium supplement content of the negative electrode material can be measured by methods and equipment known in the art. The actual gram capacity C2 of the negative electrode material can be measured by equipment and methods known in the art. Those skilled in the art can determine the theoretical gram capacity C2 of the negative electrode active material based on the type and chemical composition of the negative electrode active material. 20 .

[0135] As an example, C2 can be determined by testing the intercalable lithium capacity of the negative electrode material. Specifically, the negative electrode material can be mixed with an appropriate amount of a conductive agent and a binder in a certain proportion to prepare a single-sided coated negative electrode plate; a button-type lithium half-cell is used to discharge to a preset voltage to test the intercalable lithium capacity C'mAh of the negative electrode plate containing m2g of negative electrode material; the actual gram capacity C2 of the negative electrode material can be calculated using the formula C2=C' / m2. The above-mentioned preset voltage can represent the discharge voltage required for the negative electrode active material corresponding to the substrate of the negative electrode material to reach a fully intercalated lithium state. As an example, the preset voltage of graphite, soft carbon, hard carbon, mesophase carbon microbeads, silicon-based materials, and tin-based materials can be 0.01V, and the preset voltage of lithium titanate can be 2.0V.

[0136] Preparation method of electrode material

[0137] In a second aspect, an embodiment of the present application provides a method for preparing an electrode material, comprising the following steps S110-S130.

[0138] S110, mixing lithium metal with a complexing agent solution to allow the lithium metal and the complexing agent to react to obtain a liquid-phase lithiating agent.

[0139] In step S110, the lithium metal can be in any form, for example, it can include at least one of a lithium block, lithium foil, and lithium powder, which is not limited here. The coordination reagent can include reagents that can react with lithium metal as known in the art, and those skilled in the art can select them as needed, which is not limited here. In some embodiments, mixing the lithium metal with the coordination reagent solution can include mixing the lithium metal with the coordination reagent and stirring them evenly. The stirring temperature and time are not specifically limited, and those skilled in the art can adjust them as needed. As an example, the stirring temperature can be 0°C-60°C, optionally 10°C-40°C, and the stirring time can be 0.1h-12h, optionally 1h-6h.

[0140] S120, contacting a liquid-phase lithiating agent with an electrode active material, so that the liquid-phase lithiating agent pre-lithiates the electrode active material to obtain a pre-lithiated electrode active material.

[0141] In step S120, the contact between the liquid-phase lithiating agent and the electrode active material can be achieved in a variety of ways, which are not limited in this application. In some embodiments, the electrode active material can be impregnated with a liquid-phase lithiating agent so that the liquid-phase lithiating agent pre-lithiates the electrode active material. In step S120, the temperature and time for the liquid-phase lithiating agent to pre-lithiate the electrode active material are not specifically limited, and those skilled in the art can adjust them as needed. As an example, the pre-lithiation temperature can be 0°C-80°C, optionally 10°C-50°C, and the pre-lithiation time can be 1min-6h, optionally 5min-30min.

[0142] S130 , contacting the pre-lithiated electrode active material with a reactant to form a first inorganic lithiation layer on at least a portion of the surface of the pre-lithiated electrode active material to obtain an electrode material.

[0143] In step S130, the reactant can be a substance capable of reacting with a liquid-phase lithiating agent or a pre-lithiated electrode active material to produce at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide, or lithium phosphide. Persons skilled in the art may select the reactant as needed. After the pre-lithiated electrode active material contacts the reactant, the reactant may react with residual liquid-phase lithiating agent on at least a portion of the surface of the pre-lithiated electrode active material to form a first inorganic lithiate layer on at least a portion of the surface of the pre-lithiated electrode active material. Alternatively, the reactant may react with a material in the surface layer of the pre-lithiated electrode active material to form a first inorganic lithiate layer on at least a portion of the surface of the pre-lithiated electrode active material. The reaction temperature and reaction time of step S130 are not specifically limited and may be adjusted by persons skilled in the art as needed. As an example, the reaction temperature of step S130 may be 0°C-80°C, optionally 10°C-50°C, and the reaction time may be 1 minute-60 minutes, optionally 2 minutes-10 minutes.

[0144] The electrode material prepared according to steps S110 to S130 includes a substrate and a first inorganic lithiation layer, wherein the first inorganic lithiation layer is coated on at least a portion of the surface of the substrate. The substrate includes a pre-lithiation electrode active material, and the first inorganic lithiation layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide, or lithium phosphide.

[0145] The method provided in the embodiment of the present application is simple to operate, has mild conditions and is easy to control. The substrate of the prepared electrode material has been pre-embedded with some active lithium ions. During the first charge or discharge process, the electrode material can release active lithium ions, thereby compensating for the loss of active lithium ions in the battery formation process. In addition, the electrode material prepared by the method of the embodiment of the present application can also form a dense, uniform and stable protective film on the surface of the electrode pole piece through the first inorganic lithium compound layer. The protective film can play a similar role to the SEI film, thereby improving the environmental stability of the electrode, reducing the irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode material prepared in the embodiment of the present application is applied to secondary batteries, which can improve the energy density of the secondary battery and extend the cycle life of the secondary battery.

[0146] In some embodiments, the preparation method may further include: providing a complexing reagent solution, including uniformly mixing the complexing reagent with a solvent to obtain the complexing reagent solution.

[0147] In some embodiments, the complexing agent may include at least one of naphthalene and its derivatives, biphenyl and its derivatives, phenanthrene and its derivatives, pyrene and its derivatives, fluorene and its derivatives, indene and its derivatives, and aromatic hydrocarbon derivatives containing heteroatom functional groups. Alternatively, in some embodiments, the complexing agent may include at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, benzophenone, pyridine, and quinoline.

[0148] In some embodiments, the solvent may include at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ether compounds and their derivatives, furan compounds and their derivatives, pyran compounds and their derivatives, and esters and their derivatives. Alternatively, the solvent may include at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

[0149] Without intending to be bound by any theory or explanation, the complexing reagent selected from the above types can react with lithium metal to form a liquid-phase lithiating agent with a lower redox potential. As a result, the liquid-phase lithiating agent can more easily pre-lithiate the electrode active material and embed active lithium ions in the electrode active material, thereby facilitating the improvement of the lithium replenishment efficiency of the electrode material. Furthermore, the use of the above-mentioned type of solvent to dissolve the complexing reagent is conducive to further adjusting the redox potential of the liquid-phase lithiating agent within a suitable range, thereby further improving the efficiency of pre-lithiation and, in turn, improving the lithium replenishment efficiency of the electrode material.

[0150] In some embodiments, the redox potential of the liquid-phase lithiating agent can be 0.05 V to 1.5 V, for example, 0.05 V, 0.10 V, 0.20 V, 0.30 V, 0.40 V, 0.50 V, 0.60 V, 0.70 V, 0.80 V, 0.90 V, 1.0 V, 1.5 V, or a range consisting of any two of the above values.

[0151] Optionally, in some embodiments, the redox potential of the liquid-phase lithiating agent may also be 0.1V-0.5V, 0.1V-0.4V, 0.1V-0.3V, 0.1V-0.2V, 0.2V-0.5V, 0.2V-0.4V, 0.2V-0.3V, 0.3V-0.5V, 0.3V-0.4V, 0.4V-0.5V and the like.

[0152] The redox potential of the liquid-phase lithiating agent is within the above-mentioned suitable range, which can further improve the efficiency of pre-lithiation and thus improve the lithium replenishment efficiency of the electrode material.

[0153] The redox potential of a liquid-phase lithiating agent has a meaning well known in the art and can be measured using equipment and methods known in the art, for example, cyclic voltammetry. Specifically, an electrolytic cell can be formed using Pt as a working electrode, Li as a reference electrode and a counter electrode, and the liquid-phase lithiating agent. The open circuit voltage can be scanned from 0.01 V, followed by three cycles between 0.01 V and 1.5 V to obtain the redox peak of the liquid-phase lithiating agent and measure the redox potential of the liquid-phase lithiating agent.

[0154] In some embodiments, the molar ratio of lithium metal to the complexing agent can be (0.5:1)-(10:1), for example, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or a range consisting of any two of the above ratios. Alternatively, the molar ratio of lithium metal to the complexing agent can be (1:1)-(4:1), (1:1)-(3.5:1), (1:1)-(3:1), (1:1)-(2.5:1), (1:1)-(2:1), (1:1)-(1.5:1), and the like.

[0155] In some embodiments, the content of lithium in the liquid-phase lithiating agent may be 0.01 mol / L-10 mol / L, for example, 0.01 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 5 mol / L, 8 mol / L, 10 mol / L, or a range consisting of any two of the foregoing values. Alternatively, the content of lithium in the liquid-phase lithiating agent may be 0.01 mol / L-5 mol / L, 0.01 mol / L-4 mol / L, 0.01 mol / L-3 mol / L, 0.01 mol / L-2 mol / L, 0.01 mol / L-1 mol / L, 0.5 mol / L-5 mol / L, 0.5 mol / L-3 mol / L, 0.5 mol / L-1 mol / L, 1 mol / L-5 mol / L, 2 mol / L-4 mol / L, and so on.

[0156] Without intending to be bound by any theory or explanation, when the molar ratio of lithium metal to the complexing agent is within the above range, it not only helps improve the reaction efficiency of the lithium metal and the complexing agent, but also helps adjust the lithium content of the liquid-phase lithiating agent to within a suitable range. When the lithium content of the liquid-phase lithiating agent is within a suitable range, the pre-lithiation efficiency of the liquid-phase lithiating agent on the electrode active material can be improved.

[0157] In some embodiments, the molar ratio of lithium element to electrode active material in the liquid-phase lithiating agent may be (0.05:1)-(10:1), and may optionally be (0.1:1)-(5:1).

[0158] Without intending to be bound by any theory or explanation, the molar ratio of lithium in the liquid-phase lithiating agent to the electrode active material is within the aforementioned suitable range, allowing for the embedding of an appropriate amount of active lithium ions into the electrode active material. Consequently, during the battery formation process, the electrode material can release an appropriate amount of active lithium ions to replenish the active lithium ions lost during the initial charge-discharge cycle.

[0159] In some embodiments, the volume distribution particle size Dv50 of the electrode active material can be 0.5μm-40μm, 0.5μm-30μm, 0.5μm-20μm, 0.5μm-15μm, 2.5μm-35μm, 2.5μm-25μm, 2.5μm-15μm, 2.5μm-10μm, 4.5μm-37.5μm, 4.5μm-27.5μm, 4.5μm-17.5μm, 4.5μm-15μm, 4.5μm-12.5μm, and the like.

[0160] Without intending to be bound by any theory or explanation, when the volume distribution particle size Dv50 of the electrode active material is within the above-mentioned suitable range, the prepared electrode material not only has a suitable lithium ion transmission path, but also has good electrolyte infiltration performance. This facilitates the release of active lithium ions from the electrode material, improves the lithium replenishment efficiency of the electrode material, and thus helps to further delay the capacity decay of the secondary battery and extend the cycle life of the secondary battery.

[0161] The volume distribution particle size Dv50 of the electrode active material can be measured by referring to the test method for the volume distribution particle size Dv50 of the electrode material.

[0162] In some embodiments, the reactants may include at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, nitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide, or red phosphorus. Alternatively, the reactants may include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide, or red phosphorus.

[0163] Reactants selected from the aforementioned categories can react with the liquid-phase lithiating agent and / or pre-lithiated electrode active material. By selecting appropriate reactants, the composition of the first inorganic lithiate layer can be regulated. Having a suitable composition for the first inorganic lithiate layer not only helps suppress side reactions between the substrate and air, thereby maintaining a high lithium replenishment efficiency for the electrode material, but also helps regulate the composition of the protective film on the electrode surface, thereby improving the stability of the electrode environment. This helps further enhance the cycle stability of the secondary battery and prolongs its cycle life.

[0164] The contact between the above-mentioned reactants and the pre-lithiation electrode active material can be achieved in a variety of ways, which are not limited in this application. In some embodiments, when the reactant is a gas, the reactant can be directly introduced into the slurry obtained in step S120. In some embodiments, when the reactant is a solid, the reactant can be dissolved in an organic solvent to obtain a reactant solution, and then the reactant solution is mixed evenly with the slurry obtained in step S120. This makes it possible to make the reactants contact the pre-lithiation electrode active material more uniform and more fully, thereby facilitating the smooth progress of the reaction. The above-mentioned organic solvent may include at least one of alkanes, aromatic hydrocarbons, ethers, esters and their halides, for example, may include at least one of benzene, dimethyl carbonate, ethylene carbonate, fluoroethylene carbonate, tetrahydrofuran, dimethyl ether, hydrofluoroether, and 1,1,1,3,3,3-hexafluoroisopropyl methyl ether. In the reactant solution, the mass fraction of the reactant may be 0.1%-20%.

[0165] In some embodiments, the preparation method may further include: drying the electrode material.

[0166] The present application does not limit the dry atmosphere, and the dry atmosphere may include any atmosphere that does not produce side reactions with the electrode material. In some embodiments, the dry atmosphere may include nitrogen, argon, dry air, or a combination thereof. Alternatively, in some embodiments, the dry atmosphere may include nitrogen, argon, or a combination thereof. The present application does not limit the drying temperature and time, and those skilled in the art may adjust them as needed. In some embodiments, the drying temperature may be 0°C-200°C, optionally 20°C-120°C, and the drying time may be 5min-6h. Thus, the stability of the chemical properties of the electrode material can be improved.

[0167] Electrode plate

[0168] In a third aspect, an embodiment of the present application provides an electrode plate, which includes a current collector and an electrode film layer located on at least one side of the current collector, the electrode film layer includes an electrode material; the electrode material includes a substrate and a first inorganic lithium compound layer, the first inorganic lithium compound layer is coated on at least a portion of the surface of the substrate, the substrate includes a pre-lithiation electrode active material, and the first inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0169] The electrode plate of the third aspect includes an electrode material, and the base material of the electrode material has been pre-embedded with some active lithium ions. During the first charge or discharge process, the electrode material can release active lithium ions, thereby compensating for the loss of active lithium ions during the battery formation process. In addition, the electrode material can also form a dense, uniform and stable protective film on the surface of the electrode plate through the first inorganic lithium compound layer. The protective film can play a similar role to the SEI film, thereby improving the environmental stability of the electrode, reducing the irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode plate of the embodiment of the present application is applied to the secondary battery, which can improve the energy density of the secondary battery and extend the cycle life of the secondary battery.

[0170] It should be noted that in the embodiments of the present application, the structure of the electrode material in the electrode film layer can be determined by equipment and methods known in the art. As an example, it can be tested by the following method: obtain the electrode pole piece (when sampling from the battery, the battery can be directly disassembled, the electrode pole piece can be taken out and dried); randomly select an area, perform argon ion cross-section polishing, and take a transmission electron microscope image (TEM image) of the electrode film layer with a magnification of 3000 times or more (for example, it can be 3000 times, 30000 times, 100000 times, or 500000 times, etc.); process the TEM image and adjust the appropriate contrast to observe the substrate of the electrode material and the first inorganic lithiation layer. The thickness of the first inorganic lithiation layer can also be determined by the TEM image.

[0171] It should be noted that in the embodiments of the present application, the volume distribution particle size Dv50 of the electrode material in the electrode film layer can be determined by equipment and methods known in the art. As an example, it can be tested and obtained by the following method: obtain the electrode pole piece (when sampling from the battery, the battery can be directly disassembled, the electrode pole piece can be taken out and dried); randomly select an area, perform argon ion cross-section polishing, and take an electron microscope image (SEM image) of the electrode film layer with a magnification of 500 times or more (for example, it can be 500 times, 1000 times, or 5000 times, etc.); process the SEM image and adjust the appropriate contrast to observe the electrode material. The volume distribution particle size Dv50 of the electrode material can be determined by counting the particle size of the electrode material in the field of view.

[0172] In some embodiments, the electrode plate may further include a second inorganic lithium compound layer attached to at least a portion of the surface of the electrode film layer. The second inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide, or lithium phosphide.

[0173] In this embodiment, the second inorganic lithium compound layer may be a separable layered structure formed separately on at least a portion of the surface of the electrode film layer.

[0174] In some embodiments, the composition of the second inorganic lithiation layer may be the same as that of the first inorganic lithiation layer.

[0175] Without intending to be bound by any theory or explanation, when the electrode plate further includes a second inorganic lithium compound layer attached to at least a portion of the surface of the electrode film layer, it is beneficial to further improve the stability of the electrode environment during the charge and discharge cycle, thereby improving the cycle stability of the secondary battery.

[0176] In some embodiments, based on the total mass of the first inorganic lithiate layer, the first inorganic lithiate layer may include 0-80% lithium oxide, 0-100% lithium carbonate, 0-100% lithium fluoride, 0-45% lithium phosphide, 0-90% lithium nitride, and 0-55% lithium sulfide.

[0177] Optionally, in some embodiments, based on the total mass of the first inorganic lithiate layer, the first inorganic lithiate layer may include 0-100% lithium fluoride, 0-80% lithium oxide, 0-50% lithium nitride, 0-100% lithium carbonate, and 0-55% lithium sulfide.

[0178] In some embodiments, the first inorganic lithiation layer may include at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, or lithium sulfide.

[0179] Optionally, in some embodiments, based on the total mass of the first inorganic lithiate layer, the first inorganic lithiate layer may include 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

[0180] More optionally, in some embodiments, based on the total mass of the first inorganic lithiation layer, the first inorganic lithiation layer may include 70%-90% lithium nitride, 0-30% lithium oxide, and 0-10% lithium sulfide.

[0181] When the first inorganic lithium compound layer has the above composition, it helps protect the substrate and inhibits side reactions between the substrate and air, thereby maintaining a high lithium replenishment efficiency for the electrode material. Furthermore, when the first inorganic lithium compound layer has the above composition, it also helps form a uniform, dense, and stable protective film on the surface of the electrode plate, thereby further improving the cycling stability of the secondary battery.

[0182] In some embodiments, based on the total mass of the second inorganic lithiate layer, the second inorganic lithiate layer may include 0-80% lithium oxide, 0-100% lithium carbonate, 0-100% lithium fluoride, 0-45% lithium phosphide, 0-90% lithium nitride, and 0-55% lithium sulfide.

[0183] Alternatively, in some embodiments, based on the total mass of the second inorganic lithiate layer, the second inorganic lithiate layer may include 0-100% lithium fluoride, 0-80% lithium oxide, 0-50% lithium nitride, 0-100% lithium carbonate, and 0-55% lithium sulfide.

[0184] In some embodiments, the second inorganic lithiation layer may include at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, or lithium sulfide.

[0185] Alternatively, in some embodiments, based on the total mass of the second inorganic lithiate layer, the second inorganic lithiate layer may include 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

[0186] More optionally, in some embodiments, based on the total mass of the second inorganic lithiation layer, the second inorganic lithiation layer may include 70%-90% lithium nitride, 0-30% lithium oxide, and 0-10% lithium sulfide.

[0187] The electrode plate of the embodiment of the present application can be a positive electrode plate or a negative electrode plate. When the electrode plate is a positive electrode plate, the electrode material is a positive electrode material. When the electrode plate is a negative electrode plate, the electrode material is a negative electrode material.

[0188] In some embodiments, the electrode plate is a positive electrode plate, the electrode material is a positive electrode material, and the electrode film layer may further include other positive electrode active materials.

[0189] Optionally, in some embodiments, based on the total mass of the positive electrode film layer, the mass percentage of the positive electrode material is 15wt%-98wt%, optionally 50wt%-98wt%. The mass percentage of other positive electrode active materials is less than or equal to 95wt%,

[0190] In some embodiments, the electrode plate is a negative electrode plate, and the electrode material is a negative electrode material. The electrode film layer may further include other negative electrode active materials.

[0191] Optionally, in some embodiments, based on the total mass of the negative electrode film layer, the mass percentage of the negative electrode material may be 10 wt%-98 wt%, optionally 50 wt%-98 wt%, and the mass percentage of other negative electrode active materials may be less than or equal to 95 wt%.

[0192] When the mass percentage of the electrode material in the electrode film layer is within the above-mentioned appropriate range, an appropriate amount of active lithium ions can be released to replenish the active lithium ions lost during the first cycle of charge and discharge, and reduce the risk of lithium plating caused by excessive lithium replenishment. This allows the secondary battery to achieve both good cycle performance and high reliability.

[0193] The aforementioned other positive electrode active materials may include the same type of positive electrode active materials as the pre-lithiation positive electrode active materials, or may include positive electrode active materials of a different type from the pre-lithiation positive electrode active materials. The other negative electrode active materials may include the same type of negative electrode active materials as the pre-lithiation negative electrode active materials, or may include negative electrode active materials of a different type from the pre-lithiation negative electrode active materials. The embodiments of the electrode active materials have been described and illustrated in detail above and will not be repeated here.

[0194] In some embodiments, the electrode plate is a positive electrode plate, and the lithium supplement content of the positive electrode plate can be 1%-30%.

[0195] The lithium content of the positive electrode can be calculated by (C3-C 30 ) / C 30 ×100%, where C3 is the actual gram capacity of the positive electrode active material contained in the positive electrode sheet, in mAh / g; C 30 The theoretical gram capacity of the non-pre-lithiated positive electrode active material, in mAh / g. The positive electrode active material may include the positive electrode material and other positive electrode active materials contained in the positive electrode sheet.

[0196] The lithium content of the positive electrode sheet can be determined by methods and equipment known in the art. Among them, C3 can be determined by referring to the test method of the actual gram capacity C1 of the positive electrode material, which is not described in detail here. The theoretical gram capacity C of the non-pre-lithiated positive electrode active material is 30 It can be determined according to the type, chemical composition and content of the positive electrode active material. As an example, the positive electrode active material includes m3g of the first positive electrode active material and m4g of the positive electrode material, and the substrate of the positive electrode material is the pre-lithiated second positive electrode active material. The theoretical gram capacity C of the non-pre-lithiated positive electrode active material is 30 =[m3 / (m3+m4)]×C 31 +[m4 / (m3+m4)]×C 32 , where C 31 is the theoretical gram capacity of the first positive electrode active material, in mAh / g; C 32 is the theoretical gram capacity of the second positive electrode active material, in mAh / g.

[0197] In some embodiments, the electrode plate is a negative electrode plate, and the lithium supplement content of the negative electrode plate may be 1%-50%. Optionally, the lithium supplement content of the negative electrode plate may be 30%-50%.

[0198] The lithium content of the negative electrode can be measured by (C 40 -C4) / C 40 ×100%, where C4 is the actual gram capacity of the negative electrode active material contained in the negative electrode sheet, in mAh / g, and C 40 The theoretical gram capacity of the negative electrode active material without pre-lithiation, in mAh / g. The negative electrode active material may include the negative electrode material and other negative electrode active materials contained in the negative electrode sheet.

[0199] The lithium content of the negative electrode sheet can be determined by methods and equipment known in the art. Among them, C4 can be determined by referring to the test method of the actual gram capacity C2 of the negative electrode material, which is not described in detail here. The theoretical capacity C of the negative electrode active material without pre-lithiation 40 It can be determined based on the type, chemical composition and content of the negative electrode active material. 40 The determination process can be compared with C 30 Similar, I will not elaborate here.

[0200] When the lithium content of the electrode plate falls within the given range, it can release an appropriate amount of active lithium ions when used in a secondary battery to replenish the active lithium ions lost during the first cycle of charge and discharge, and reduce the risk of lithium plating caused by excessive lithium replenishment. Therefore, the application of the electrode plate in a secondary battery can enable the secondary battery to have both good cycle performance and high reliability.

[0201] Preparation method of electrode plate

[0202] In a fourth aspect, an embodiment of the present application provides a method for preparing an electrode plate, which may include method A or method B.

[0203] Method A may include the following steps S210 to S240.

[0204] S210, mixing lithium metal with a complexing agent solution to allow the lithium metal and the complexing agent to react to obtain a liquid-phase lithiating agent.

[0205] S220 , contacting a liquid-phase lithiating agent with an electrode active material so that the liquid-phase lithiating agent pre-lithiates the electrode active material to obtain a pre-lithiated electrode active material.

[0206] S230, contacting a pre-lithiated electrode active material with a reactant to form a first inorganic lithiation layer on at least a portion of the surface of the pre-lithiated electrode active material to obtain an electrode material; wherein the electrode material includes: a substrate, the substrate includes the pre-lithiated electrode active material; and a first inorganic lithiation layer coated on at least a portion of the surface of the substrate, the first inorganic lithiation layer including at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0207] S240, preparing an electrode plate including an electrode material.

[0208] The implementation of steps S210 to S230 can be the same as that of steps S110 to S130. The implementation of steps S110 to S130 has been described and explained in detail above and will not be repeated here. Step S240 can be implemented by methods known in the art and is not limited here.

[0209] The electrode plate prepared according to method A includes an electrode material, and the base material of the electrode material has been pre-embedded with some active lithium ions. During the first charge or discharge process, the electrode material can release active lithium ions, thereby compensating for the loss of active lithium ions during the battery formation process. In addition, the electrode material can also form a dense, uniform and stable protective film on the surface of the electrode plate through the first inorganic lithium compound layer. The protective film can play a similar role to the SEI film, thereby improving the environmental stability of the electrode, reducing the irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode plate prepared in the embodiment of the present application is applied to a secondary battery, which can improve the energy density of the secondary battery and extend the cycle life of the secondary battery.

[0210] In some embodiments, method A may further include: providing a complexing reagent solution, including uniformly mixing the complexing reagent with a solvent to obtain the complexing reagent solution.

[0211] In some embodiments, the complexing agent may include at least one of naphthalene and its derivatives, biphenyl and its derivatives, phenanthrene and its derivatives, pyrene and its derivatives, fluorene and its derivatives, indene and its derivatives, and aromatic hydrocarbon derivatives containing heteroatom functional groups. Alternatively, in some embodiments, the complexing agent may include at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, benzophenone, pyridine, and quinoline.

[0212] In some embodiments, the solvent may include at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ether compounds and their derivatives, furan compounds and their derivatives, pyran compounds and their derivatives, and esters and their derivatives. Alternatively, the solvent may include at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

[0213] Without intending to be bound by any theory or explanation, the complexing reagent selected from the above types can react with lithium metal to form a liquid-phase lithiating agent with a lower redox potential. As a result, the liquid-phase lithiating agent can more easily pre-lithiate the electrode active material and embed active lithium ions in the electrode active material, thereby facilitating the improvement of the lithium replenishment efficiency of the electrode material. Furthermore, the use of the above-mentioned type of solvent to dissolve the complexing reagent is conducive to further adjusting the redox potential of the liquid-phase lithiating agent within a suitable range, thereby further improving the efficiency of pre-lithiation and, in turn, improving the lithium replenishment efficiency of the electrode plate.

[0214] In some embodiments, in method A, the redox potential of the liquid-phase lithiating agent can be 0.05 V to 1.5 V, for example, 0.05 V, 0.10 V, 0.20 V, 0.30 V, 0.40 V, 0.50 V, 0.60 V, 0.70 V, 0.80 V, 0.90 V, 1.0 V, 1.5 V, or a range consisting of any two of the above values.

[0215] Optionally, in some embodiments, in method A, the redox potential of the liquid-phase lithiating agent can also be 0.1V-0.5V, 0.1V-0.4V, 0.1V-0.3V, 0.1V-0.2V, 0.2V-0.5V, 0.2V-0.4V, 0.2V-0.3V, 0.3V-0.5V, 0.3V-0.4V, 0.4V-0.5V and the like.

[0216] The redox potential of the liquid-phase lithiating agent is within the above-mentioned appropriate range, which can further improve the efficiency of pre-lithiation, thereby improving the lithium replenishment efficiency of the electrode plate.

[0217] In some embodiments, in method A, the molar ratio of lithium metal to the complexing agent can be (0.5:1)-(10:1), for example, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or a range consisting of any two of the above ratios. Alternatively, the molar ratio of lithium metal to the complexing agent can be (1:1)-(4:1), (1:1)-(3.5:1), (1:1)-(3:1), (1:1)-(2.5:1), (1:1)-(2:1), (1:1)-(1.5:1), and the like.

[0218] In some embodiments, the content of lithium in the liquid-phase lithiating agent may be 0.01 mol / L-10 mol / L, for example, 0.01 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 5 mol / L, 8 mol / L, 10 mol / L, or a range consisting of any two of the foregoing values. Alternatively, the content of lithium in the liquid-phase lithiating agent may be 0.01 mol / L-5 mol / L, 0.01 mol / L-4 mol / L, 0.01 mol / L-3 mol / L, 0.01 mol / L-2 mol / L, 0.01 mol / L-1 mol / L, 0.5 mol / L-5 mol / L, 0.5 mol / L-3 mol / L, 0.5 mol / L-1 mol / L, 1 mol / L-5 mol / L, 2 mol / L-4 mol / L, and so on.

[0219] Without intending to be bound by any theory or explanation, when the molar ratio of lithium metal to the complexing agent is within the above range, it not only helps improve the reaction efficiency of lithium metal and the complexing agent, but also helps adjust the lithium content of the liquid-phase lithiating agent to within a suitable range. When the lithium content of the liquid-phase lithiating agent is within a suitable range, it can improve the pre-lithiation efficiency of the liquid-phase lithiating agent on the electrode active material, thereby improving the lithium replenishment efficiency of the electrode plate.

[0220] In some embodiments, in method A, the molar ratio of lithium element to electrode active material in the liquid-phase lithiating agent may be (0.05:1)-(10:1), and may optionally be (0.1:1)-(5:1).

[0221] Without intending to be bound by any theory or explanation, the molar ratio of lithium in the liquid-phase lithiating agent to the electrode active material is within the aforementioned suitable range, allowing for the embedding of an appropriate amount of active lithium ions into the electrode active material. Consequently, during the battery formation process, the electrode material can release an appropriate amount of active lithium ions to replenish the active lithium ions lost during the initial charge-discharge cycle.

[0222] In some embodiments, in method A, the volume distribution particle size Dv50 of the electrode active material can be 0.5 μm-40 μm, 0.5 μm-30 μm, 0.5 μm-20 μm, 0.5 μm-15 μm, 2.5 μm-35 μm, 2.5 μm-25 μm, 2.5 μm-15 μm, 2.5 μm-10 μm, 4.5 μm-37.5 μm, 4.5 μm-27.5 μm, 4.5 μm-17.5 μm, 4.5 μm-15 μm, 4.5 μm-12.5 μm, and the like.

[0223] Without intending to be bound by any theory or explanation, when the volume distribution particle size Dv50 of the electrode active material is within the above-mentioned suitable range, the prepared electrode material not only has a suitable lithium ion transport pathway but also has good electrolyte wettability. This facilitates the release of active lithium ions from the electrode material, improving the lithium replenishment efficiency of the electrode sheet, thereby further slowing the capacity decay of the secondary battery and extending the cycle life of the secondary battery.

[0224] In some embodiments, in method A, the reactants may include at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, nitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide, or red phosphorus. Alternatively, the reactants may include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide, or red phosphorus.

[0225] Reactants selected from the aforementioned categories can react with the liquid-phase lithiating agent and / or pre-lithiated electrode active material. By selecting appropriate reactants, the composition of the first inorganic lithiate layer can be regulated. Having a suitable composition for the first inorganic lithiate layer not only helps suppress side reactions between the substrate and air, thereby maintaining a high lithium replenishment efficiency for the electrode material, but also helps regulate the composition of the protective film on the electrode surface, thereby improving the stability of the electrode environment. This helps further enhance the cycle stability of the secondary battery and prolongs its cycle life.

[0226] The contact between the above-mentioned reactants and the pre-lithiation electrode active material can be achieved in a variety of ways, which are not limited in this application. In some embodiments, when the reactant is a gas, the reactant can be directly introduced into the slurry obtained in step S220. In some embodiments, when the reactant is a solid, the reactant can be dissolved in an organic solvent to obtain a reactant solution, and then the reactant solution is mixed evenly with the slurry obtained in step S220. This can make the reactant contact with the pre-lithiation electrode active material more uniform and more sufficient, which is conducive to the smooth progress of the reaction. The above-mentioned organic solvent may include at least one of alkanes, aromatic hydrocarbons, ethers, esters and their halides, for example, it may include at least one of benzene, dimethyl carbonate, ethylene carbonate, fluoroethylene carbonate, tetrahydrofuran, dimethyl ether, hydrofluoroether, and 1,1,1,3,3,3-hexafluoroisopropyl methyl ether. In the reactant solution, the mass fraction of the reactant can be 0.1%-20%.

[0227] In some embodiments, method A may further include drying the electrode material.

[0228] The present application does not limit the dry atmosphere, and the dry atmosphere may include any atmosphere that does not produce side reactions with the electrode material. In some embodiments, the dry atmosphere may include nitrogen, argon, dry air, or a combination thereof. Alternatively, in some embodiments, the dry atmosphere may include nitrogen, argon, or a combination thereof. The present application does not limit the drying temperature and time, and those skilled in the art may adjust them as needed. In some embodiments, the drying temperature may be 0°C-200°C, optionally 20°C-120°C, and the drying time may be 5min-6h. In this way, the stability of the chemical properties of the electrode material can be improved, thereby improving the stability of the chemical properties of the electrode sheet.

[0229] In some embodiments, step S240 may include the following steps (1)-(2).

[0230] (1) The electrode material, optional other electrode active materials, and optional additives are uniformly mixed in an aprotic solvent to obtain an electrode slurry, wherein the other electrode active materials include other positive electrode active materials known in the art or other negative electrode active materials known in the art.

[0231] (2) Applying the electrode slurry to at least one side of the current collector, drying, and cold pressing to obtain an electrode sheet.

[0232] In some embodiments, step S240 may include the following steps (3)-(4).

[0233] (3) Evenly mixing the electrode material, optional other electrode active materials, and optional additives to obtain electrode powder, wherein the other electrode active materials include other positive electrode active materials known in the art or other negative electrode active materials known in the art.

[0234] (4) Extruding and rolling the electrode powder into an electrode film, and pressing the electrode film and the current collector together to obtain an electrode plate.

[0235] Method B may include the following steps S310 to S340.

[0236] S310 , providing an initial electrode sheet, the initial electrode sheet including a current collector and an electrode film layer located on at least one side of the current collector, the electrode film layer including an electrode active material.

[0237] S320, mixing lithium metal with a complexing agent solution to allow the lithium metal and the complexing agent to react to obtain a liquid-phase lithiating agent.

[0238] In step S320, the lithium metal can be in any form, for example, it can include at least one of a lithium block, lithium foil, and lithium powder, which is not limited here. The coordination reagent may include a reagent that can react with lithium metal as known in the art, and those skilled in the art can select it as needed, which is not limited here. In some embodiments, mixing the lithium metal with the coordination reagent solution may include mixing the lithium metal with the coordination reagent and stirring it evenly. The stirring temperature and time are not specifically limited, and those skilled in the art can adjust it as needed. As an example, the stirring temperature can be 0°C-60°C, optionally 10°C-40°C, and the stirring time can be 0.1h-12h, optionally 1h-6h.

[0239] S330 , bringing a liquid-phase lithiating agent into contact with the electrode film layer, so that the liquid-phase lithiating agent pre-lithiates the electrode active material, thereby obtaining a pole piece including the pre-lithiated electrode active material.

[0240] In step S330, the contact between the liquid-phase lithiating agent and the electrode film layer can be achieved in a variety of ways, which are not limited in this application. In some embodiments, the electrode film layer can be impregnated with a liquid-phase lithiating agent, or the liquid-phase lithiating agent can be coated on the surface of the electrode film layer so that the liquid-phase lithiating agent pre-lithiates the electrode active material in the electrode film layer. The coating method can be brushing, curtain coating, roller coating, nitrogen spraying, air spraying, electrostatic spraying, electrophoretic spraying, high-pressure airless spraying, etc., which are not limited here. In step S330, the temperature and time for the liquid-phase lithiating agent to pre-lithiate the electrode active material are not specifically limited, and those skilled in the art can adjust them as needed. As an example, the pre-lithiation temperature can be 0°C-80°C, optionally 10°C-50°C, and the pre-lithiation time can be 1min-6h, optionally 5min-30min.

[0241] S340, bringing an electrode plate including a pre-lithiation electrode active material into contact with a reactant to form a first inorganic lithiation layer on at least a portion of the surface of the pre-lithiation electrode active material, thereby obtaining an electrode plate including an electrode material; wherein the electrode material includes: a substrate, the substrate includes the pre-lithiation electrode active material; and a first inorganic lithiation layer coated on at least a portion of the surface of the substrate, the first inorganic lithiation layer including at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0242] In step S340, the reactant can be a substance that can react with a liquid-phase lithiating agent or a pre-lithiated electrode active material to produce at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide, and lithium phosphide. Those skilled in the art can select the reactant as needed. In step S340, after the electrode sheet including the pre-lithiated electrode active material contacts the reactant, the reactant can react with the liquid-phase lithiating agent remaining on at least a portion of the surface of the pre-lithiated electrode active material or the material on the surface of the pre-lithiated electrode active material to form a first inorganic lithiate layer on at least a portion of the surface of the pre-lithiated electrode active material, thereby obtaining an electrode sheet including the electrode material.

[0243] In some embodiments, the reactant may also react with the liquid-phase lithiating agent remaining on the surface of the electrode film layer to form a second inorganic lithiation layer on at least a portion of the surface of the electrode film layer. The implementation of the second inorganic lithiation layer has been described and illustrated in detail above and will not be repeated here. The reaction temperature and reaction time of step S340 are not specifically limited and may be adjusted as needed by those skilled in the art. As an example, the reaction temperature of step S340 may be 0°C-80°C, optionally 10°C-50°C, and the reaction time may be 1min-60min, optionally 2min-10min.

[0244] The electrode plate prepared according to method B includes an electrode material, and the base material of the electrode material has been pre-embedded with some active lithium ions. During the first charge or discharge process, the electrode material can release active lithium ions, thereby compensating for the loss of active lithium ions during the battery formation process. In addition, the electrode material can also form a dense, uniform and stable protective film on the surface of the electrode plate through the first inorganic lithium compound layer. The protective film can play a similar role to the SEI film, thereby improving the environmental stability of the electrode, reducing the irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode plate prepared in the embodiment of the present application is applied to a secondary battery, which can improve the energy density of the secondary battery and extend the cycle life of the secondary battery.

[0245] It should be noted that by regulating the above steps S310 to S340, the composition of the electrode film layer in the electrode plate can be regulated. As an example, by regulating the reaction raw materials and reaction conditions of step S330, part of the electrode active material can be pre-lithiated, or all of the electrode active material can be pre-lithiated. By regulating the reaction raw materials and reaction conditions of step S330, the degree of pre-lithiation of the electrode active material can also be regulated to regulate the lithium replenishment content of the electrode plate. As an example, by regulating the reaction raw materials and reaction conditions of step S340, a first inorganic lithium compound layer can be formed on the surface of part of the pre-lithiated electrode active material, or a first inorganic lithium compound layer can be formed on the surface of all the pre-lithiated electrode active materials. As an example, by regulating the reaction raw materials and reaction conditions of steps S330 and S340, a second inorganic lithium compound layer can also be formed on at least part of the surface of the electrode plate. Those skilled in the art will understand that no matter what composition the electrode film layer in the electrode plate has, as long as it contains the above-mentioned electrode material, it falls within the scope of this application.

[0246] In some embodiments, method B may further include: providing a complexing reagent solution, including uniformly mixing the complexing reagent with a solvent to obtain the complexing reagent solution.

[0247] In some embodiments, the complexing agent may include at least one of naphthalene and its derivatives, biphenyl and its derivatives, phenanthrene and its derivatives, pyrene and its derivatives, fluorene and its derivatives, indene and its derivatives, and aromatic hydrocarbon derivatives containing heteroatom functional groups. Alternatively, in some embodiments, the complexing agent may include at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, benzophenone, pyridine, and quinoline.

[0248] In some embodiments, the solvent may include at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ether compounds and their derivatives, furan compounds and their derivatives, pyran compounds and their derivatives, and esters and their derivatives. Alternatively, the solvent may include at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

[0249] Without intending to be bound by any theory or explanation, the complexing reagent selected from the above types can react with lithium metal to form a liquid-phase lithiating agent with a lower redox potential. As a result, the liquid-phase lithiating agent can more easily pre-lithiate the electrode active material and embed active lithium ions in the electrode active material, thereby facilitating the improvement of the lithium replenishment efficiency of the electrode plate. Furthermore, the use of the above-mentioned type of solvent to dissolve the complexing reagent is conducive to further adjusting the redox potential of the liquid-phase lithiating agent within a suitable range, thereby further improving the efficiency of pre-lithiation and, in turn, improving the lithium replenishment efficiency of the electrode plate.

[0250] In some embodiments, in method B, the redox potential of the liquid-phase lithiating agent can be 0.05 V to 1.5 V, for example, 0.05 V, 0.10 V, 0.20 V, 0.30 V, 0.40 V, 0.50 V, 0.60 V, 0.70 V, 0.80 V, 0.90 V, 1.0 V, 1.5 V, or a range consisting of any two of the above values.

[0251] Optionally, in some embodiments, in method B, the redox potential of the liquid-phase lithiating agent can also be 0.1V-0.5V, 0.1V-0.4V, 0.1V-0.3V, 0.1V-0.2V, 0.2V-0.5V, 0.2V-0.4V, 0.2V-0.3V, 0.3V-0.5V, 0.3V-0.4V, 0.4V-0.5V and the like.

[0252] The redox potential of the liquid-phase lithiating agent is within the above-mentioned appropriate range, which can further improve the efficiency of pre-lithiation, thereby improving the lithium replenishment efficiency of the electrode plate.

[0253] In some embodiments, in method B, the molar ratio of lithium metal to the complexing agent can be (0.5:1)-(10:1), for example, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or a range consisting of any two of the above ratios. Alternatively, the molar ratio of lithium metal to the complexing agent can be (1:1)-(4:1), (1:1)-(3.5:1), (1:1)-(3:1), (1:1)-(2.5:1), (1:1)-(2:1), (1:1)-(1.5:1), and the like. In some embodiments, the content of lithium in the liquid-phase lithiating agent may be 0.01 mol / L-10 mol / L, for example, 0.01 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 5 mol / L, 8 mol / L, 10 mol / L, or a range consisting of any two of the foregoing values. Alternatively, the content of lithium in the liquid-phase lithiating agent may be 0.01 mol / L-5 mol / L, 0.01 mol / L-4 mol / L, 0.01 mol / L-3 mol / L, 0.01 mol / L-2 mol / L, 0.01 mol / L-1 mol / L, 0.5 mol / L-5 mol / L, 0.5 mol / L-3 mol / L, 0.5 mol / L-1 mol / L, 1 mol / L-5 mol / L, 2 mol / L-4 mol / L, and so on.

[0254] Without intending to be bound by any theory or explanation, when the molar ratio of lithium metal to the complexing agent is within the above range, it not only helps improve the reaction efficiency of lithium metal and the complexing agent, but also helps adjust the lithium content of the liquid-phase lithiating agent to within a suitable range. When the lithium content of the liquid-phase lithiating agent is within a suitable range, it can improve the pre-lithiation efficiency of the liquid-phase lithiating agent on the electrode active material, thereby improving the lithium replenishment efficiency of the electrode plate.

[0255] In some embodiments, in method B, the molar ratio of lithium element to electrode active material in the liquid-phase lithiating agent may be (0.05:1)-(10:1), and may optionally be (0.1:1)-(5:1).

[0256] Without intending to be bound by any theory or explanation, the molar ratio of lithium in the liquid-phase lithiating agent to the electrode active material is within the aforementioned suitable range, allowing for the embedding of an appropriate amount of active lithium ions into the electrode active material. Consequently, during the battery formation process, the electrode material can release an appropriate amount of active lithium ions to replenish the active lithium ions lost during the initial charge-discharge cycle.

[0257] In some embodiments, in method B, the volume distribution particle size Dv50 of the electrode active material can be 0.5 μm-40 μm, 0.5 μm-30 μm, 0.5 μm-20 μm, 0.5 μm-15 μm, 2.5 μm-35 μm, 2.5 μm-25 μm, 2.5 μm-15 μm, 2.5 μm-10 μm, 4.5 μm-37.5 μm, 4.5 μm-27.5 μm, 4.5 μm-17.5 μm, 4.5 μm-15 μm, 4.5 μm-12.5 μm, and the like.

[0258] Without intending to be bound by any theory or explanation, when the volume distribution particle size Dv50 of the electrode active material is within the above-mentioned suitable range, the prepared electrode material not only has a suitable lithium ion transmission path, but also has good electrolyte wettability. This facilitates the release of active lithium ions from the electrode material, improves the lithium replenishment efficiency of the electrode sheet, and thus helps further delay the capacity decay of the secondary battery and extend the cycle life of the secondary battery.

[0259] In some embodiments, in method B, the reactants may include at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, nitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide, or red phosphorus. Alternatively, the reactants may include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide, or red phosphorus.

[0260] Reactants selected from the aforementioned categories can react with the pre-lithiated electrode active material. By selecting appropriate reactants, the composition of the first inorganic lithiation layer can be regulated. A suitable composition of the first inorganic lithiation layer not only helps suppress side reactions between the substrate and air, thereby maintaining high lithium replenishment efficiency for the electrode sheet, but also helps regulate the composition of the protective film on the electrode surface, thereby improving the stability of the electrode environment. This helps further enhance the cycling stability of the secondary battery and prolongs its cycle life.

[0261] The contact between the above-mentioned reactants and the pole piece including the pre-lithiation electrode active material can be achieved in a variety of ways, which are not limited in this application. In some embodiments, when the reactant is a gas, the surface of the pole piece is directly purged with the reactant gas. In some embodiments, when the reactant is a solid, the reactant can be dissolved in an organic solvent to obtain a reactant solution, and then the reactant solution is applied to the surface of the pole piece. The coating method can be brushing, shower coating, roller coating, nitrogen spraying, air spraying, electrostatic spraying, electrophoretic spraying, high-pressure airless spraying, etc., which are not limited here. In this way, the reactant can be more evenly and fully in contact with the pole piece surface, which is conducive to the smooth progress of the reaction. When the reactant contacts the pole piece in the form of a reactant solution, the reactant solution can also infiltrate into the pores of the electrode film layer, and react with the pre-lithiation electrode active material inside the electrode film layer, thereby further improving the efficiency of the reaction. The organic solvent may include at least one of alkanes, aromatic hydrocarbons, ethers, esters, and halogenated derivatives thereof. For example, the organic solvent may include at least one of benzene, dimethyl carbonate, ethylene carbonate, fluoroethylene carbonate, tetrahydrofuran, dimethyl ether, hydrofluoroether, and 1,1,1,3,3,3-hexafluoroisopropyl methyl ether. The mass fraction of the reactants in the reactant solution may be 0.1% to 20%.

[0262] In some embodiments, method B may further include: drying the electrode plate.

[0263] The present application does not limit the dry atmosphere, and the dry atmosphere may include any atmosphere that does not produce side reactions with the electrode plate. In some embodiments, the dry atmosphere may include nitrogen, argon, dry air, or a combination thereof. Optionally, in some embodiments, the dry atmosphere may include nitrogen, argon, or a combination thereof. The present application does not limit the drying temperature and time, and those skilled in the art may adjust them as needed. In some embodiments, the drying temperature may be 0°C-200°C, optionally 20°C-120°C, and the drying time may be 5min-6h. In this way, the stability of the chemical properties of the electrode plate can be improved.

[0264] Battery

[0265] In a fifth aspect, embodiments of the present application provide a battery. The battery described in the embodiments of the present application may include one or more battery cells to provide a single physical module with higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or hybrid via a busbar.

[0266] The battery cell may be a secondary battery, also known as a rechargeable battery or storage battery. This refers to a battery cell that can be recharged to activate the active material after discharge and continue to be used. The present application does not specifically limit the type of secondary battery. For example, the secondary battery may be a lithium-ion battery, a lithium metal battery, etc. In particular, the secondary battery may be a lithium-ion battery.

[0267] Typically, a battery cell consists of an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is placed between the positive and negative electrode sheets, primarily to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0268] The battery cell of the embodiment of the present application includes at least one of the electrode material of the first aspect, the electrode material prepared according to the preparation method of the second aspect, the electrode plate of the third aspect, or the electrode plate prepared according to the preparation method of the fourth aspect.

[0269] [Positive electrode]

[0270] In the battery cell of the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector and comprising a positive electrode active material. For example, the positive electrode current collector has two opposing surfaces in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on either or both of the two opposing surfaces of the positive electrode current collector.

[0271] In some embodiments, the positive electrode sheet includes the electrode material of the first aspect, which is a positive electrode material. The embodiments of the electrode material have been described and illustrated in detail above and will not be repeated here. It will be understood that the battery of the present application can achieve the beneficial effects of any of the above-described embodiments of the electrode material of the present application.

[0272] In some embodiments, the positive electrode sheet includes an electrode material prepared according to the method of the second aspect, where the electrode material is a positive electrode material. The embodiments of the electrode material preparation method have been described and illustrated in detail above and will not be repeated here. It will be understood that the battery of the present application can achieve the beneficial effects of any of the aforementioned embodiments of the electrode material preparation method of the present application.

[0273] In some embodiments, the positive electrode plate includes the electrode plate of the third aspect. The embodiments of the electrode plate have been described and illustrated in detail above and will not be repeated here. It is understood that the battery of the present application can achieve the beneficial effects of any of the above-mentioned embodiments of the electrode plate of the present application.

[0274] In some embodiments, the positive electrode sheet comprises an electrode sheet produced according to the preparation method of the fourth aspect. The embodiments of the preparation method of the electrode sheet have been described and illustrated in detail above and will not be repeated here. It is understood that the battery of the present application can achieve the beneficial effects of any of the above-described embodiments of the preparation method of the electrode sheet of the present application.

[0275] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may 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.).

[0276] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0277] In some embodiments, the positive electrode film layer may further include a conductive agent and an optional dispersant. As an 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.

[0278] [Negative electrode]

[0279] In the battery cell of the present application, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and comprising a negative electrode active material. For example, the negative electrode current collector has two opposing surfaces in the thickness direction of the negative electrode current collector, and the negative electrode film layer is disposed on either or both of the two opposing surfaces of the negative electrode current collector.

[0280] In some embodiments, the negative electrode plate includes the electrode material of the first aspect, which is a negative electrode material. The embodiments of the electrode material have been described and illustrated in detail above and will not be repeated here. It will be understood that the battery of the present application can achieve the beneficial effects of any of the above-described embodiments of the electrode material of the present application.

[0281] In some embodiments, the negative electrode sheet includes an electrode material prepared according to the method of the second aspect, and the electrode material is a negative electrode material. The embodiments of the electrode material preparation method have been described and illustrated in detail above and will not be repeated here. It will be understood that the battery of the present application can achieve the beneficial effects of any of the above-described embodiments of the electrode material preparation method of the present application.

[0282] In some embodiments, the negative electrode plate includes the electrode plate of the third aspect. The embodiments of the electrode plate have been described and illustrated in detail above and will not be repeated here. It is understood that the battery of the present application can achieve the beneficial effects of any of the above-mentioned embodiments of the electrode plate of the present application.

[0283] In some embodiments, the negative electrode sheet comprises an electrode sheet produced according to the preparation method of the fourth aspect. The embodiments of the preparation method of the electrode sheet have been described and illustrated in detail above and will not be repeated here. It is understood that the battery of the present application can achieve the beneficial effects of any of the above-described embodiments of the preparation method of the electrode sheet of the present application.

[0284] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil or aluminum foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0285] In some embodiments, the negative electrode film layer may further include a binder. The binder 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).

[0286] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0287] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0288] In addition, the negative electrode plate of the present application does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode plate described in the present application may further include a conductive primer layer (e.g., composed of a conductive agent and a binder) disposed between the negative electrode current collector and the negative electrode film layer. In other embodiments, the negative electrode plate described in the present application may further include a protective layer covering the surface of the negative electrode film layer.

[0289] [Isolation film]

[0290] The separator is provided between the positive electrode and the negative electrode to serve as an isolation. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0291] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0292] [Electrolytes]

[0293] Generally speaking, battery cells also contain an electrolyte, which conducts ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte; it can be selected based on needs. For example, the electrolyte can be liquid, gel, or solid.

[0294] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0295] 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 difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0296] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl 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, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0297] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0298] In some embodiments, the battery cell housing may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the battery cell housing may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0299] The present application has no particular limitation on the shape of the battery cell, which can be cylindrical, square, or any other shape. For example, FIG1 shows a battery cell 5 with a square structure as an example.

[0300] In some embodiments, referring to Figure 2, the housing may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0301] The preparation method of the battery cell of the present application is well known. In some embodiments, the electrode assembly can be placed in a housing, dried, injected with electrolyte, and then vacuum packaged, allowed to stand, formed, and shaped to obtain a battery cell.

[0302] In some embodiments, the battery referred to herein may be a battery module or battery pack. A battery module or battery pack generally includes a housing for enclosing one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0303] In some embodiments, a battery module or battery pack may contain multiple battery cells, which may be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections. Multiple battery cells may be directly connected in series, in parallel, or in a hybrid configuration, and then the entire battery cell structure is housed within a housing. Alternatively, multiple battery cells may be first connected in series, in parallel, or in a hybrid configuration to form a battery module, and then the battery modules may be further connected in series, in parallel, or in a hybrid configuration to form a single unit, which is then housed within a housing.

[0304] FIG3 is a schematic diagram of an example battery module 4. As shown in FIG3 , there are multiple battery cells 5, which are first connected in series, in parallel, or in a mixed series to form a battery module 4. The multiple battery cells 5 in the battery module 4 can be electrically connected via a busbar component to achieve the series, parallel, or mixed series connection of the multiple battery cells 5 in the battery module 4. In the battery module 4, the multiple battery cells 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other manner. The multiple battery cells 5 can further be fixed by fasteners.

[0305] In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0306] Figures 4 and 5 are schematic diagrams of an example battery pack 1. As shown in Figures 4 and 5, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The multiple battery modules 4 within the battery pack 1 may be electrically connected via a busbar assembly to enable series, parallel, or mixed connection of the multiple battery modules 4 within the battery pack 1. The housing includes an upper housing 2 and a lower housing 3. The upper housing 2 is used to cover the lower housing 3 and form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 may be arranged in any manner within the battery box.

[0307] Electrical devices

[0308] The present application also provides an electrical device, which includes a battery provided by the present application, and the battery is used to provide electrical energy. The battery can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as 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., but is not limited thereto.

[0309] As the electrical device, a battery cell, a battery module including a plurality of battery cells, or a battery pack can be selected according to its usage requirements.

[0310] Figure 6 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of this device, a battery pack or battery module can be used.

[0311] As another example, an electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be light and thin, and may use a battery cell as a power source.

[0312] Example

[0313] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0314] Example 1

[0315] Preparation of electrode materials

[0316] Step a: Dissolve 1 mol of the complexing reagent 2-methylbiphenyl in 1 L of tetrahydrofuran solvent, then add 1 mol of lithium flakes, and stir at room temperature 25°C for 4 hours to obtain a liquid phase lithiating agent 1 mol / L lithium-[2-methylbiphenyl]-tetrahydrofuran.

[0317] Step b: Volume distribution particle size Dv 1 The electrode active material silicon oxide with a size of 10 μm is added to the liquid-phase lithiating agent obtained in step a, and stirred under the first reaction conditions to obtain a lithiated electrode slurry, wherein the molar ratio M of the lithium element in the liquid-phase lithiating agent to the electrode active material is 5, and the first reaction conditions are: reaction temperature 25° C., reaction time 6 h.

[0318] Step c: The reactants (a mixed gas of 2% HF, 2% CO2, 20% O2 and 76% N2) are introduced into the lithiated electrode slurry at a flow rate of 0.5 L / min, and the reaction is continued under the second reaction conditions, which are: reaction temperature 25°C, reaction time 10 min.

[0319] Step d: The slurry after the reaction in step c is filtered under reduced pressure and dried at 120°C under normal pressure for 1 hour to obtain an electrode material. The electrode material includes a substrate (pre-lithiated silicon oxide) and a first inorganic lithium compound layer coated on the surface of the substrate. The volume distribution volume Dv of the electrode material is 250 is 15 μm, the thickness d of the first inorganic lithiation layer is 1 μm, and the first inorganic lithiation layer comprises 40% by weight of Li2O, 30% by weight of Li3N, 2% by weight of Li2CO3, and 28% by weight of LiF. The lithium supplement content of the electrode material was measured using the method described in the specification of this application and was found to be 50%.

[0320] Preparation of positive electrode

[0321] The positive electrode active material LiFePO4, the conductive agent carbon black and the binder PVDF are mixed in a ratio of 84:8:8, the solvent NMP is added, and the mixture is stirred evenly to obtain a positive electrode slurry; the positive electrode slurry is coated on a carbon-coated aluminum foil, and the positive electrode sheets are obtained after drying, cold pressing and slitting.

[0322] Preparation of negative electrode sheet

[0323] The negative electrode active material artificial graphite, electrode material, conductive agent carbon black, binder SBR, and thickener CMC-Na are mixed in a mass ratio of 87:10:0.5:1.25:1.25, solvent NMP is added, and the mixture is stirred evenly to obtain a negative electrode slurry; the negative electrode slurry is coated on copper foil, and the negative electrode sheets are obtained after drying, cold pressing, and slitting.

[0324] Isolation film

[0325] Polypropylene film is used as the isolation film.

[0326] Preparation of electrolyte

[0327] LiPF6 was dissolved in a solvent prepared by ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate in a volume ratio of 1:1:1 to obtain an electrolyte with a LiPF6 concentration of 1 mol / L.

[0328] Preparation of secondary batteries

[0329] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain an electrode assembly; the electrode assembly is placed in a packaging shell, dried, and then injected with electrolyte. After vacuum packaging, standing, formation, shaping and other processes, a secondary battery is obtained.

[0330] Example 2-15

[0331] Based on the preparation process of the electrode material in Example 1, the preparation parameters of the electrode material were adjusted as shown in Table 1 to prepare the electrode materials of Examples 2-15. The preparation of the positive electrode sheet, negative electrode sheet, separator, electrolyte, and secondary battery of Examples 2-15 was the same as that of Example 1.

[0332] Example 16

[0333] Preparation of electrode materials

[0334] Step a: 0.05 mol of the complexing agent naphthalene was dissolved in 1 L of the solvent 2-methylfuran, and then 0.05 mol of lithium flakes was added. The mixture was stirred at room temperature of 25° C. for 4 h to obtain 0.05 mol / L of the liquid phase lithiating agent lithium-naphthalene-[2-methylfuran].

[0335] Step b: Volume distribution particle size Dv 1 The electrode active material LiFePO4 with a particle size of 10 μm is added to the liquid-phase lithiating agent obtained in step a, and stirred under the first reaction conditions to obtain a lithiated electrode slurry, wherein the molar ratio M of the lithium element in the liquid-phase lithiating agent to the electrode active material is 1, and the first reaction conditions are: reaction temperature 25° C., reaction time 5 min.

[0336] Step c: The reactant (a mixed gas of 80% O2 and 20% N2) is introduced into the lithiated electrode slurry at a flow rate of 0.1 L / min, and the reaction is continued under the second reaction conditions, which are: reaction temperature 25°C, reaction time 2 minutes.

[0337] Step d: The slurry after the reaction in step c is filtered under reduced pressure and dried at 120°C under normal pressure for 1 hour to obtain an electrode material. The electrode material includes a substrate (pre-lithiated LiFePO4) and a first inorganic lithium compound layer coated on the surface of the substrate. The volume distribution volume Dv of the electrode material is 2 50 is 10 μm, the thickness d of the first inorganic lithiation layer is 80 nm, and the first inorganic lithiation layer comprises 30% by mass of Li2O and 70% by mass of Li3N. The lithium supplement content of the electrode material is measured by the method described in the specification of this application, and the measured value is 30%.

[0338] Preparation of positive electrode

[0339] The electrode material, positive electrode active material LiFePO4, conductive agent carbon black and binder PVDF are mixed in a ratio of 15:69:8:8, solvent NMP is added, and stirred evenly to obtain positive electrode slurry; the positive electrode slurry is coated on carbon-coated aluminum foil, and the positive electrode sheets are obtained after drying, cold pressing and slitting.

[0340] Preparation of negative electrode sheet

[0341] The negative electrode active material artificial graphite, the negative electrode active material silicon oxide, the conductive agent carbon black, the binder SBR, and the thickener CMC-Na are mixed in a mass ratio of 67:30:0.5:1.25:1.25, the solvent NMP is added, and the mixture is stirred evenly to obtain a negative electrode slurry; the negative electrode slurry is coated on a copper foil, and the negative electrode sheet is obtained after drying, cold pressing, and slitting.

[0342] Isolation film

[0343] Polypropylene film is used as the isolation film.

[0344] Preparation of electrolyte

[0345] LiPF6 was dissolved in a solvent prepared by ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate in a volume ratio of 1:1:1 to obtain an electrolyte with a LiPF6 concentration of 1 mol / L.

[0346] Preparation of secondary batteries

[0347] The positive electrode sheet, separator, and negative electrode sheet are stacked in order to obtain an electrode assembly; the electrode assembly is placed in a packaging shell, dried, and then injected with electrolyte. After vacuum packaging, standing, formation, shaping and other processes, a secondary battery is obtained.

[0348] Examples 17-18

[0349] Based on the preparation process of the electrode material in Example 16, the preparation parameters of the electrode material were adjusted as shown in Table 2 to prepare the electrode materials of Examples 17-18. The preparation of the positive electrode sheet, negative electrode sheet, separator, electrolyte, and secondary battery of Examples 17-18 was the same as that of Example 16.

[0350] Example 19

[0351] Preparation of negative electrode sheet

[0352] The negative electrode active material (artificial graphite and silicon oxide are mixed in a mass ratio of 95:5), the conductive agent carbon black, the binder SBR, and the thickener CMC-Na are mixed in a mass ratio of 97:0.5:1.25:1.25, the solvent NMP is added, and the mixture is stirred evenly to obtain a negative electrode slurry; the negative electrode slurry is coated on a copper foil, and the initial negative electrode sheet is obtained after drying, cold pressing, and slitting.

[0353] 1 mol of the complexing reagent 2-methylbiphenyl was dissolved in 1 L of tetrahydrofuran solvent, and then 1 mol of lithium flakes was added. The mixture was stirred at room temperature at 25°C for 4 h to obtain 1 mol / L of the liquid phase lithiating agent lithium-[2-methylbiphenyl]-tetrahydrofuran.

[0354] The initial negative electrode sheet is immersed in a liquid-phase lithiating agent, and the liquid-phase lithiating agent and the negative electrode active material are reacted under first reaction conditions to obtain a sheet containing pre-lithiated negative electrode active material. The molar ratio M of lithium in the liquid-phase lithiating agent to the negative electrode active material in the initial negative electrode sheet is 0.3, and the first reaction conditions are: reaction temperature 40°C, reaction time 20 minutes.

[0355] The electrode sheet including the pre-lithiated negative electrode active material is placed in the reactant gas flow, and the reactant (a mixture of 25% H2S and 75% N2) is continuously introduced at a flow rate of 0.22L / min, and the reaction is continued under the second reaction conditions, which are: reaction temperature 25°C, reaction time 10min. Subsequently, it is dried at normal pressure at 120°C for 1h to obtain the negative electrode sheet. The negative electrode sheet includes an electrode material, which includes a substrate and a first inorganic lithium compound layer coated on the surface of the substrate. The thickness d of the first inorganic lithium compound layer is 800nm, and the first inorganic lithium compound layer includes 10% Li2S and 90% Li3N by mass. The lithium supplement content of the negative electrode sheet is 50% as measured by the method described in the specification of this application.

[0356] The preparation process of the positive electrode sheet, separator, electrolyte and secondary battery of Example 19 is the same as that of Example 1.

[0357] Examples 20-32

[0358] Based on the preparation process of the negative electrode sheet in Example 19, the preparation parameters of the negative electrode sheet were adjusted as shown in Table 3 to prepare the negative electrode sheets of Examples 20-32. The preparation of the positive electrode sheets, separators, electrolytes, and secondary batteries of Examples 20-32 was the same as that of Example 19.

[0359] Example 33

[0360] Preparation of positive electrode

[0361] The positive electrode active material LiFePO4, the conductive agent carbon black and the binder PVDF are mixed in a ratio of 84:8:8, the solvent NMP is added, and the mixture is stirred evenly to obtain a positive electrode slurry; the positive electrode slurry is coated on a carbon-coated aluminum foil, and the initial positive electrode sheet is obtained after drying, cold pressing and cutting.

[0362] 0.05 mol of the coordination reagent naphthalene was dissolved in 1 L of the solvent 2-methylfuran, and then 0.05 mol of lithium flakes was added and stirred at room temperature at 25°C for 4 h to obtain 0.05 mol / L of the liquid phase lithiating agent lithium-naphthalene-[2-methylfuran].

[0363] The initial positive electrode sheet is immersed in a liquid-phase lithiating agent, and the liquid-phase lithiating agent and the positive electrode active material are reacted under first reaction conditions to obtain a sheet comprising a pre-lithiated positive electrode active material. The molar ratio M of the lithium element in the liquid-phase lithiating agent to the positive electrode active material in the initial positive electrode sheet is 1, and the first reaction conditions are: a reaction temperature of 25°C and a reaction time of 15 minutes.

[0364] The electrode sheet including the pre-lithiated positive electrode active material is placed in the reactant gas flow, and the reactant (a mixed gas of 80% O2 and 20% N2) is continuously introduced at a flow rate of 1 L / min, and the reaction is continued under the second reaction conditions, which are: reaction temperature 25°C, reaction time 10 min. Subsequently, it is dried at normal pressure at 120°C for 1 hour to obtain a positive electrode sheet. The positive electrode sheet includes an electrode material, which includes a substrate (pre-lithiated LiFePO4) and a first inorganic lithium compound layer coated on the surface of the substrate. The thickness d of the first inorganic lithium compound layer is 100 nm, and the first inorganic lithium compound layer includes 30% Li2O and 70% Li3N by mass. The lithium supplement content of the positive electrode sheet is determined to be 30% by the method described in the specification of this application.

[0365] The preparation of the negative electrode sheet, separator, electrolyte and secondary battery of Example 33 is the same as that of Example 16.

[0366] Examples 34-35

[0367] Based on the preparation process of the positive electrode sheet in Example 33, the preparation parameters of the positive electrode sheet were adjusted as shown in Table 4 to prepare the positive electrode sheets of Examples 34-35. The preparation of the negative electrode sheet, separator, electrolyte, and secondary battery of Examples 34-35 was the same as that of Example 33.

[0368] Comparative Examples 1-3

[0369] The preparation process of the positive electrode sheet, negative electrode sheet, separator, electrolyte and secondary battery of Comparative Examples 1-3 is the same as that of Example 1, except that the electrode material is replaced with an equal mass of electrode active material, as shown in Table 1 for details.

[0370] Comparative Example 4

[0371] Based on the preparation process of the electrode material in Example 1, the preparation parameters of the electrode material were adjusted as shown in Table 1 to prepare the electrode material of Comparative Example 4. The preparation of the positive electrode sheet, negative electrode sheet, separator, electrolyte, and secondary battery of Comparative Example 4 was the same as that of Example 1.

[0372] Comparative Example 5

[0373] The preparation process of the positive electrode sheet, negative electrode sheet, separator, electrolyte and secondary battery of Comparative Example 5 is the same as that of Example 16, except that the electrode material is replaced with an equal mass of electrode active material, as shown in Table 2 for details.

[0374] Comparative Example 6

[0375] Based on the preparation process of the electrode material in Example 16, the preparation parameters of the electrode material were adjusted as shown in Table 2 to prepare the electrode material of Comparative Example 6. The preparation of the positive electrode sheet, negative electrode sheet, separator, electrolyte, and secondary battery of Comparative Example 6 was the same as that of Example 16.

[0376] Comparative Example 7

[0377] The preparation process of the positive electrode plate, separator, electrolyte and secondary battery of Comparative Example 7 is the same as that of Example 19, except that the negative electrode plate is replaced with the initial negative electrode plate to prepare the secondary battery of Comparative Example 7.

[0378] Comparative Example 8

[0379] Based on the preparation process of the negative electrode sheet in Example 19, the preparation parameters of the negative electrode sheet were adjusted as shown in Table 3 to prepare the negative electrode sheet of Comparative Example 8. The preparation of the positive electrode sheet, separator, electrolyte, and secondary battery of Comparative Example 8 was the same as that of Example 19.

[0380] Comparative Example 9

[0381] The preparation process of the negative electrode plate, isolation membrane, electrolyte and secondary battery of Comparative Example 9 is the same as that of Example 33, except that the positive electrode plate is replaced with the initial positive electrode plate to prepare the secondary battery of Comparative Example 9.

[0382] Comparative Example 10

[0383] Based on the preparation process of the positive electrode sheet in Example 33, the preparation parameters of the positive electrode sheet were adjusted as shown in Table 4 to prepare the positive electrode sheet of Comparative Example 10. The preparation of the negative electrode sheet, separator, electrolyte, and secondary battery of Comparative Example 10 was the same as that of Example 33.

[0384] The following tests were performed on Examples 1-35 and Comparative Examples 1-10, and the test results are shown in Tables 1 to 4, respectively.

[0385] Characterization of materials

[0386] (1)Dv 1 Representation of 50

[0387] The volume distribution particle size Dv of the electrode active material was determined using a laser particle size analyzer (Malvern Master Size 3000) according to the particle size distribution laser diffraction method in accordance with GB / T 19077-2016. 1 50.

[0388] (2)Dv 2 Representation of 50

[0389] The volume distribution particle size Dv of the electrode material was determined using a laser particle size analyzer (Malvern Master Size 3000) according to the particle size distribution laser diffraction method in accordance with GB / T 19077-2016. 2 50.

[0390] (3) Characterization of the thickness d of the first inorganic lithiation layer

[0391] Example 1-18: The prepared electrode material was dispersed in an ethanol solvent and dropped onto a microgate support film. The thickness d of the first inorganic lithiation layer in the electrode material was measured using a high-resolution transmission electron microscope (magnification of 10,000-300,000 times).

[0392] Example 19-32: Take the prepared negative electrode plate; randomly select an area, perform argon ion cross-section polishing, and take a transmission electron microscope image (TEM image) with a magnification of 30,000 times; process the TEM image, adjust the appropriate contrast, and measure the thickness d of the first inorganic lithiation layer.

[0393] Examples 33-35: Take the prepared positive electrode sheet; randomly select an area, perform argon ion cross-section polishing, and take a transmission electron microscope image (TEM image) with a magnification of 10,000 times; process the TEM image, adjust the appropriate contrast, and measure the thickness d of the first inorganic lithiation layer.

[0394] (4) Characterization of the composition of the first inorganic lithium compound layer

[0395] Example 1-18: The types and contents of elements on the surface of the electrode material were measured by X-ray photoelectron spectroscopy (XPS), and the composition of the first inorganic lithiation layer was determined based on the content ratio of each element and the chemical formula of the inorganic lithiation.

[0396] Examples 19-32: Take the prepared negative electrode plate, randomly select an area for cross-section, determine the position of the first inorganic lithiation layer by scanning electron microscopy (SEM) at a magnification of 10,000 times, and mark the position where the first inorganic lithiation layer is distributed in the field of view as the target area; then select a 10μm*10μm area at a magnification of 1000 times for EDS surface scanning for 2 minutes to obtain the element types and contents in the target area, and determine the composition of the first inorganic lithiation layer according to the content ratio of each element and the chemical formula of the inorganic lithiation.

[0397] Examples 33-35: Take the prepared positive electrode sheet, randomly select an area for cross-section, determine the position of the first inorganic lithiation layer by scanning electron microscopy (SEM) at a magnification of 10,000 times, and mark the position where the first inorganic lithiation layer is distributed in the field of view as the target area; then select a 10μm*10μm area at a magnification of 1000 times for EDS surface scanning for 2 minutes to obtain the element types and contents in the target area, and determine the composition of the first inorganic lithiation layer according to the content ratio of each element and the chemical formula of the inorganic lithiation.

[0398] Battery performance test

[0399] (1) First week Coulomb efficiency test

[0400] At 25°C, charge the secondary battery at a constant current of 0.1C to 3.65V, then charge at a constant voltage until the current is less than or equal to 0.05C. After 5 minutes of rest, record the charge capacity as the initial charge capacity (C0) (mAh / g). Then, discharge the battery at a constant current of 0.2C to 2.5V. Record the discharge capacity as the initial discharge capacity (D0) (mAh / g). First cycle coulombic efficiency = D0 / C0 × 100%.

[0401] (2) Normal temperature cycle performance test

[0402] At 25°C, the formed secondary battery was charged at a constant current of 0.2C to 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C, left for 5 minutes, and then discharged at 0.5C to 2.5V. The resulting capacity was recorded as the initial capacity C 初始 Repeat the above steps for the same battery and record the discharge capacity C of the battery after the 300th cycle. 300 , calculate the battery capacity retention rate P 300 (%) = C 300 / C 初始 ×100%.

[0403] (3) Discharge capacity test

[0404] At 25°C, charge the formed secondary battery at a constant current of 0.2C to 3.65V, then charge it at a constant voltage of 3.65V to a current of 0.05C, let it sit for 5 minutes, and then discharge it at 0.5C to 2.5V. Repeat the above steps for the same battery and record the discharge capacity C of the battery after the 100th cycle. 100 , calculate the battery's discharge capacity in grams = C 100 / (mass of positive electrode active material + mass of electrode material).

[0405]

[0406]

[0407]

[0408]

[0409]

[0410]

[0411]

[0412] In Tables 1 to 4, the percentage of a gaseous component in the reactants refers to the volume fraction of that component in the gas mixture. For example, "25% H2S + 75% N2" refers to a mixture of H2S and N2 in a 25:75 volume ratio. The percentage of a solute in the reactant solution refers to the mass percentage concentration of that solute in the solution. For example, "[5% S + 5% P] / THF mixed solution" refers to a mixed solution of S and P in THF with a mass percentage concentration of 5% S and a mass percentage concentration of 5% P.

[0413] It can be seen from Tables 1 to 4 above that the electrode materials and electrode plates provided in the embodiments of the present application are applied to secondary batteries, which can effectively compensate for the loss of active lithium ions in the secondary batteries, thereby improving the cycle performance of the batteries.

[0414] From Examples 1-7, it can be seen that by regulating the composition of the first inorganic lithiation layer, the lithium replenishment efficiency of the electrode material can be controlled, thereby regulating the cycle performance of the battery. From Examples 3, 8-10, it can be seen that, when other conditions are the same, as the lithium replenishment content of the electrode material increases, the first-cycle coulombic efficiency and cycle performance of the battery are improved. From Examples 3, 11-13, it can be seen that, when other conditions remain unchanged, regulating the thickness of the first inorganic lithiation layer within an appropriate range can improve the lithium replenishment efficiency of the electrode material while improving the cycle performance of the battery.

[0415] In contrast, Comparative Example 1, in which the electrode material is replaced with an equal mass of silicon oxide, exhibits inferior first-cycle coulombic efficiency and cycle performance compared to Examples 1-13. Comparative Examples 2 and 3, in which the electrode material is replaced with an equal mass of tin and phosphorus, also exhibit inferior first-cycle coulombic efficiency and cycle performance compared to corresponding Examples 14 and 15. Although Comparative Example 4 utilizes pre-lithiated silicon oxide, it lacks a first inorganic lithiation layer on the surface of the pre-lithiated silicon oxide. Consequently, the lithium replenishment efficiency of the pre-lithiated silicon oxide is reduced, and the battery's cycle performance is also unsatisfactory.

[0416] The test results of Examples 16-18 in Table 2 show that pre-lithiation of the positive electrode active material and coating its surface with a first inorganic lithium compound layer can effectively replenish the active lithium ions lost by the secondary battery. As a result, the secondary battery can maintain a high discharge capacity after 100 charge-discharge cycles.

[0417] In contrast, Comparative Example 5, which replaces the electrode material with an equal mass of LiFePO4, exhibits significantly inferior discharge capacity and cycle performance to Examples 16-18. Although Comparative Example 6 uses pre-lithiated LiFePO4, it lacks a first inorganic lithiation layer on the surface of the pre-lithiated LiFePO4. Consequently, the lithium replenishment efficiency of the pre-lithiated LiFePO4 is reduced, resulting in not only a lower discharge capacity than Example 17, but also inferior cycle performance to Examples 16-18.

[0418] From the test results in Table 3, it can be seen that pre-lithiation of the negative electrode active material in the negative electrode plate and treatment of the negative electrode plate with reactants so that the negative electrode plate contains electrode materials can effectively improve the first-cycle coulombic efficiency and cycle performance of the battery.

[0419] In contrast, the negative electrode plate of Comparative Example 7 was not pre-lithiated, and the battery's first-cycle coulombic efficiency and cycle performance were much lower than those of Examples 19-32. Although the negative electrode active material in Comparative Example 8 was pre-lithiated, no first inorganic lithium layer was formed on the surface of the pre-lithiated negative electrode active material. As a result, the battery's first-cycle coulombic efficiency was lower than that of Examples 19-25 and Examples 29-32, and its cycle performance was also lower than that of Examples 19-32.

[0420] The test results in Table 4 show that pre-lithiation of the positive electrode active material in the positive electrode sheet and treatment of the positive electrode sheet with reactants, so that the positive electrode sheet contains electrode material, can effectively replenish the active lithium ions lost by the secondary battery. As a result, the secondary battery can still maintain a high discharge capacity after 100 charge and discharge cycles.

[0421] In contrast, the positive electrode sheet of Comparative Example 9 was not pre-lithiated, and its discharge capacity per gram and cycle performance after 100 charge-discharge cycles were much lower than those of Examples 33-35. Although the positive active material in the positive electrode sheet of Comparative Example 10 was pre-lithiated, no first inorganic lithium layer was formed on the surface of the pre-lithiated positive active material. Consequently, its discharge capacity per gram after 100 charge-discharge cycles was lower than that of Example 33, and its cycle performance was also lower than that of Example 33.

[0422] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. An electrode material comprising: a substrate comprising a pre-lithiated electrode active material; as well as A first inorganic lithium compound layer is coated on at least a portion of the surface of the substrate, wherein the first inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

2. The electrode material according to claim 1, wherein The first inorganic lithium compound layer includes at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride or lithium sulfide; Optionally, based on the total mass of the first inorganic lithium compound layer, the first inorganic lithium compound layer comprises 18%-90% of lithium nitride, 0-28% of lithium fluoride, 0-80% of lithium oxide, 0-2% of lithium carbonate, and 0-20% of lithium sulfide; More optionally, based on the total mass of the first inorganic lithiation layer, the first inorganic lithiation layer includes 70%-90% of lithium nitride, 0-30% of lithium oxide, and 0-10% of lithium sulfide.

3. The electrode material according to claim 1 or 2, wherein The thickness of the first inorganic lithium compound layer is 2nm-5000nm, and can be optionally 20nm-1000nm.

4. The electrode material according to any one of claims 1 to 3, wherein The volume distribution particle size Dv50 of the electrode material is 0.6 μm-60 μm, and can be optionally 5 μm-15 μm.

5. The electrode material according to any one of claims 1 to 4, wherein The electrode material is a positive electrode material, and the lithium supplement content of the positive electrode material is 1%-30%, and can be optionally 5%-20%; The lithium supplement content of the positive electrode material is determined by (C1-C 10 ) / C 10 ×100%, where C1 is the actual gram capacity of the positive electrode material in mAh / g, C 10 It is the theoretical gram capacity of the positive electrode active material, in mAh / g.

6. The electrode material according to any one of claims 1 to 4, wherein The electrode material is a negative electrode material, and the lithium supplement content of the negative electrode material is 1%-100%, and can be optionally 30%-50%; The lithium supplement content of the negative electrode material is (C 20 -C2) / C 20 ×100%, where C2 is the actual gram capacity of the negative electrode material in mAh / g, and C 20 It is the theoretical gram capacity of the negative electrode active material, in mAh / g.

7. A method for preparing an electrode material, comprising: Mixing lithium metal with a complexing agent solution so that the lithium metal reacts with the complexing agent to obtain a liquid-phase lithiating agent; contacting the liquid-phase lithiating agent with an electrode active material so that the liquid-phase lithiating agent pre-lithiates the electrode active material to obtain a pre-lithiated electrode active material; contacting the pre-lithiation electrode active material with a reactant to form a first inorganic lithiation layer on at least a portion of the surface of the pre-lithiation electrode active material to obtain an electrode material; Among them, the electrode material includes: a substrate, the substrate includes the pre-lithiation electrode active material; and the first inorganic lithium compound layer coated on at least a portion of the surface of the substrate, the first inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

8. The preparation method according to claim 7, wherein: The preparation method further comprises: Providing the complexing reagent solution, including uniformly mixing the complexing reagent with a solvent to obtain the complexing reagent solution; Optionally, the complexing agent includes at least one of naphthalene and its derivatives, biphenyl and its derivatives, phenanthrene and its derivatives, pyrene and its derivatives, fluorene and its derivatives, indene and its derivatives, or aromatic hydrocarbon derivatives containing heteroatom functional groups, and more preferably includes at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, or benzophenone; Optionally, the solvent includes at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ether compounds and their derivatives, furan compounds and their derivatives, pyran compounds and their derivatives, or esters and their derivatives, and more optionally includes at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran or fluoroethylene carbonate.

9. The preparation method according to claim 7 or 8, wherein: The redox potential of the liquid-phase lithiating agent is 0.05V-1.5V, and can be optionally 0.1V-0.5V.

10. The preparation method according to any one of claims 7 to 9, wherein The molar ratio of the lithium metal to the complexing agent is (0.5:1)-(10:1), and can be optionally (1:1)-(4:1); And / or, the molar concentration of lithium element in the liquid-phase lithiating agent is 0.01 mol / L-10 mol / L, and can be optionally 0.01 mol / L-5 mol / L; And / or, the molar ratio of lithium element in the liquid-phase lithiating agent to the electrode active material is (0.05:1)-(10:1), and can be optionally (0.1:1)-(5:1); And / or, the volume distribution particle size Dv50 of the electrode active material is 0.5 μm-40 μm.

11. The preparation method according to any one of claims 7 to 10, wherein: The reactants include at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, nitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide or red phosphorus, and can optionally include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide or red phosphorus.

12. An electrode plate, comprising a current collector and an electrode film layer located on at least one side of the current collector, wherein: The electrode film layer includes an electrode material; The electrode material comprises: a substrate comprising a pre-lithiated electrode active material; and A first inorganic lithium compound layer is coated on at least a portion of the surface of the substrate, wherein the first inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

13. The electrode plate according to claim 12, wherein: The electrode plate also includes a second inorganic lithium compound layer attached to at least a portion of the surface of the electrode film layer, and the second inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

14. The electrode plate according to claim 12 or 13, wherein: The first inorganic lithium compound layer includes at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride or lithium sulfide; Optionally, based on the total mass of the first inorganic lithium compound layer, the first inorganic lithium compound layer comprises 18%-90% of lithium nitride, 0-28% of lithium fluoride, 0-80% of lithium oxide, 0-2% of lithium carbonate, and 0-20% of lithium sulfide; More optionally, based on the total mass of the first inorganic lithiation layer, the first inorganic lithiation layer includes 70%-90% of lithium nitride, 0-30% of lithium oxide, and 0-10% of lithium sulfide.

15. A method for preparing an electrode sheet, comprising: Method A: Mixing lithium metal with a complexing agent solution so that the lithium metal reacts with the complexing agent to obtain a liquid-phase lithiating agent; contacting the liquid-phase lithiating agent with an electrode active material so that the liquid-phase lithiating agent pre-lithiates the electrode active material to obtain a pre-lithiated electrode active material; contacting the pre-lithiation electrode active material with a reactant to form a first inorganic lithiation layer on at least a portion of the surface of the pre-lithiation electrode active material to obtain an electrode material; The electrode material comprises: a substrate, the substrate comprising the pre-lithiation electrode active material; and a first inorganic lithium compound layer coated on at least a portion of the surface of the substrate, the first inorganic lithium compound layer comprising at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide; Preparing an electrode sheet comprising the electrode material; Or method B: Providing an initial pole piece, the initial pole piece comprising a current collector and an electrode film layer located on at least one side of the current collector, the electrode film layer comprising an electrode active material; Mixing lithium metal with a complexing agent solution so that the lithium metal reacts with the complexing agent to obtain a liquid-phase lithiating agent; The liquid-phase lithiating agent is brought into contact with the electrode film layer, so that the liquid-phase lithiating agent pre-lithiates the electrode active material to obtain a pole piece including the pre-lithiated electrode active material; The electrode sheet including the pre-lithiation electrode active material is brought into contact with a reactant to form a first inorganic lithiation layer on the surface of the pre-lithiation electrode active material, thereby obtaining an electrode sheet including the electrode material; Among them, the electrode material includes: a substrate, the substrate includes the pre-lithiation electrode active material; and the first inorganic lithium compound layer coated on at least a portion of the surface of the substrate, the first inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

16. The preparation method according to claim 15, wherein: The method A and / or method B further comprises: Providing the complexing reagent solution, including uniformly mixing the complexing reagent with a solvent to obtain the complexing reagent solution; Optionally, the complexing agent includes at least one of naphthalene and its derivatives, biphenyl and its derivatives, phenanthrene and its derivatives, pyrene and its derivatives, fluorene and its derivatives, indene and its derivatives, or aromatic hydrocarbon derivatives containing heteroatom functional groups, and more preferably includes at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, or benzophenone; Optionally, the solvent includes at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ether compounds and their derivatives, furan compounds and their derivatives, pyran compounds and their derivatives, or esters and their derivatives, and more optionally includes at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran or fluoroethylene carbonate.

17. The preparation method according to claim 15 or 16, wherein: In the method A and / or the method B, the redox potential of the liquid-phase lithiating agent is 0.05V-1.5V, and can be optionally 0.1V-0.5V.

18. The preparation method according to any one of claims 15 to 17, wherein: In the method A and / or method B, The molar ratio of the lithium metal to the complexing agent is (0.5:1)-(10:1), and can be optionally (1:1)-(4:1); And / or, the molar concentration of lithium element in the liquid-phase lithiating agent is 0.01 mol / L-10 mol / L, and can be optionally 0.01 mol / L-5 mol / L; And / or, the molar ratio of lithium element in the liquid-phase lithiating agent to the electrode active material is (0.05:1)-(10:1), and can be optionally (0.1:1)-(5:1); And / or, the volume distribution particle size Dv50 of the electrode active material is 0.5 μm-40 μm.

19. The preparation method according to any one of claims 15 to 18, wherein In the method A and / or method B, The reactants include at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, nitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide or red phosphorus, and can optionally include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide or red phosphorus.

20. A battery, comprising at least one of the electrode material according to any one of claims 1 to 6, the electrode material prepared according to the preparation method according to any one of claims 7 to 11, the electrode plate according to any one of claims 12 to 14, or the electrode plate prepared according to the preparation method according to any one of claims 15 to 19.

21. An electrical device comprising the battery according to claim 20.

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