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

Abstract

The application provides an electrode material and a preparation method thereof, an electrode sheet and a preparation method thereof, a battery and a power utilization device. The electrode material comprises a substrate and a first inorganic lithium compound layer coated on at least part of the surface of the substrate, wherein the substrate comprises a pre-lithiated 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.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrode material and a preparation method thereof, an electrode tab and a preparation method thereof, a battery and a power utilization device. BACKGROUND

[0002] Secondary batteries rely on active ions to reciprocally deintercalate between positive and negative electrodes for charging and discharging, and have the outstanding features of high energy density, long cycle life, and no pollution, no memory effect, etc. Therefore, as a clean energy, secondary batteries have gradually been popularized from electronic products to large device fields such as electric vehicles to adapt to the sustainable development strategy of the environment and energy. As a result, higher requirements are put forward for the energy density and cycle performance of secondary batteries. SUMMARY

[0003] In order to achieve the above-mentioned purpose, the present application provides an electrode material and a preparation method thereof, an electrode tab and a preparation method thereof, a battery and a power utilization device, which can improve the energy density and cycle performance of the battery.

[0004] In a first aspect, an embodiment of the present application provides an electrode material, comprising: a substrate, the substrate comprising a pre-lithiated electrode active material; and a first inorganic lithiated layer coated on at least part of a surface of the substrate, the first inorganic lithiated layer comprising at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0005] Without being limited by any theory or explanation, the substrate of the electrode material of the present application comprises a pre-lithiated electrode active material, which has pre-embedded part of active lithium ions, and the pre-lithiated electrode active material can release active lithium ions during the first charging or discharging process, thereby compensating for the loss of active lithium ions during the formation process of the battery. Compared with the technical solution of directly compounding a metal lithium layer on the surface of the negative electrode tab in the related art, the electrode material of the present application has the advantage of more uniform lithium compensation. In addition, the electrode material of the present application comprises a first inorganic lithiated layer, which can on the one hand isolate the substrate from the air, improve the stability of the chemical properties of the substrate, so that the electrode material maintains a high lithium compensation efficiency; on the other hand, the first inorganic lithiated layer can form a dense, uniform and stable protective film on the surface of the electrode tab, which 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 of the present application applied to the secondary battery can improve the energy density of the secondary battery and prolong the cycle life of the secondary battery.

[0006] In any embodiment of the present application, the first inorganic lithium compound layer comprises at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride or lithium sulfide.

[0007] Optionally, 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, based on the total mass of the first inorganic lithium compound layer.

[0008] More optionally, the first inorganic lithium compound layer comprises 70%-90% of lithium nitride, 0-30% of lithium oxide and 0-10% of lithium sulfide, based on the total mass of the first inorganic lithium compound layer.

[0009] When the first inorganic lithium compound layer has the above composition, it is beneficial to protect the substrate and inhibit the side reaction of the substrate with air, so that the electrode material maintains a high lithium supplement efficiency. In addition, when the first inorganic lithium compound layer has the above composition, it is beneficial to form a uniform, dense and stable protective film on the surface of the electrode tab when applied to a secondary battery, thereby further improving the cycle stability of the secondary battery.

[0010] In any embodiment of the present application, the thickness of the first inorganic lithium compound layer is 2 nm-5000 nm, and optionally 20 nm-1000 nm.

[0011] The thickness of the first inorganic lithium compound layer meets the given range, which not only improves the stability of the chemical properties of the substrate, but also enables the electrode material to maintain a high substrate content. Thus, the lithium supplement efficiency of the electrode material can be significantly improved. In addition, the thickness of the first inorganic lithium compound layer within the above suitable range also helps to improve the environmental stability of the electrode. Thus, the capacity decay of the secondary battery can be inhibited, and the cycle life of the secondary battery can be prolonged.

[0012] In any embodiment of the present application, the volume distribution particle size Dv50 of the electrode material is 0.6 μm-60 μm, and optionally 5 μm-15 μm. Thus, it is beneficial to facilitate the release of active lithium ions from the electrode material, improve the lithium supplement efficiency of the electrode material, and thus further delay the capacity decay of the secondary battery and prolong the cycle life of the secondary battery.

[0013] 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 optionally 5%-20%; the lithium supplement content of the positive electrode material is characterized by (C1-C 10 ) / C 10 ×100%, wherein C1 is the actual capacity of the positive electrode material, in mAh / g, and C 10is the theoretical gravimetric capacity of the positive active material, in mAh / g. Thus, the secondary battery can have both good cycle performance and high reliability.

[0014] 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% to 100%, and can be 30% to 50%; the lithium supplement content of the negative electrode material is characterized by (C 20 -C2) / C 20 × 100%, wherein C2 is the actual gravimetric capacity of the negative electrode material, in mAh / g, and C 20 is the theoretical gravimetric capacity of the negative active material, in mAh / g. Thus, the secondary battery can have both good cycle performance and high reliability.

[0015] In a second aspect, the embodiments of the present application provide a preparation method of an electrode material, comprising:

[0016] mixing lithium metal and a complexing agent solution to make the lithium metal react with the complexing agent to obtain a liquid-phase lithiation agent;

[0017] contacting the liquid-phase lithiation agent with an electrode active material to pre-lithiate the electrode active material by the liquid-phase lithiation agent to obtain a pre-lithiated electrode active material;

[0018] contacting the pre-lithiated electrode active material with a reactant to form a first inorganic lithium compound layer on at least part of the surface of the pre-lithiated electrode active material to obtain the electrode material;

[0019] The electrode material comprises: a substrate, the substrate comprising the pre-lithiated electrode active material; and a first inorganic lithium compound layer coated on at least part 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.

[0020] The method provided by the embodiments of the present application is simple in operation, mild in conditions and easy to control, and the substrate of the electrode material prepared by the method has been pre-embedded with part of active lithium ions. In the first charging or discharging process, the electrode material can release active lithium ions, thereby compensating for the loss of active lithium ions in the formation process of the battery. In addition, the electrode material prepared by the method of the embodiments of the present application can also form a dense, uniform and stable protective film on the surface of the electrode sheet 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. Thus, the electrode material prepared by the embodiments of the present application applied to the secondary battery can improve the energy density of the secondary battery and prolong the cycle life of the secondary battery.

[0021] In any embodiment of the present application, the preparation method further comprises:

[0022] The complexing agent solution is prepared by mixing the complexing agent with a solvent.

[0023] Optionally, the complexing agent comprises at least one of naphthalene and derivatives thereof, biphenyl and derivatives thereof, phenanthrene and derivatives thereof, pyrene and derivatives thereof, fluorene and derivatives thereof, indene and derivatives thereof, or aromatic hydrocarbon derivatives containing heteroatom functional groups, and more optionally at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, or benzophenone.

[0024] Optionally, the solvent comprises at least one of alkanes and derivatives thereof, aromatic hydrocarbons and derivatives thereof, ether compounds and derivatives thereof, furan compounds and derivatives thereof, pyran compounds and derivatives thereof, or esters and derivatives thereof, and more optionally at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

[0025] The complexing agent selected from the above-mentioned categories can undergo a complexation reaction with lithium metal to generate a liquid-phase lithiating agent with a lower redox potential. Thus, the liquid-phase lithiating agent is more likely to pre-lithiate the electrode active material and embed active lithium ions in the electrode active material, thereby facilitating the improvement of the lithium supplement efficiency of the electrode material. Further, dissolving the complexing agent in the solvent of the above-mentioned category 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 the lithium supplement efficiency of the electrode material.

[0026] In any embodiment of the present application, the redox potential of the liquid-phase lithiating agent is 0.05 V-1.5 V, and more optionally 0.1 V-0.5 V. Thus, the efficiency of pre-lithiation can be further improved, thereby improving the lithium supplement efficiency of the electrode material.

[0027] In any embodiment of the present application, the molar ratio of lithium metal to the complexing agent is (0.5:1)-(10:1), and more optionally (1:1)-(4:1).

[0028] In any embodiment of the present application, the molar concentration of lithium in the liquid-phase lithiating agent is 0.01 mol / L-10 mol / L, and more optionally 0.01 mol / L-5 mol / L.

[0029] When the molar ratio of lithium metal to the complexing agent is within the above-mentioned range, not only the reaction efficiency of lithium metal and the complexing agent is improved, but also the content of lithium in the liquid-phase lithiating agent is adjusted within a suitable range. The content of lithium in the liquid-phase lithiating agent within a suitable range can improve the pre-lithiation efficiency of the liquid-phase lithiating agent on the electrode active material.

[0030] In any embodiment of the present application, the molar ratio of lithium element in the liquid lithiumation agent to the electrode active material is (0.05:1)-(10:1), which can be (0.1:1)-(5:1). In this way, during the battery formation process, the electrode material can release an appropriate amount of active lithium ions to compensate for the loss of active lithium ions during the first charge-discharge cycle.

[0031] In any embodiment of the present application, the volume distribution particle size Dv50 of the electrode active material is 0.5-40 μm. In this way, it is beneficial to release active lithium ions from the electrode material, improve the lithium compensation efficiency of the electrode material, and thus further delay the capacity decay of the secondary battery and prolong the cycle life of the secondary battery.

[0032] In any embodiment of the present application, the reactants include at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, dinitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide, or red phosphorus, which can optionally include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide, or red phosphorus.

[0033] By selecting appropriate reactants, the composition of the first inorganic lithium compound layer can be controlled. The first inorganic lithium compound layer has a suitable composition, which is beneficial to inhibit the side reaction of the substrate with air, so that the electrode material maintains high lithium compensation efficiency, and is also beneficial to control the composition of the protective film on the electrode surface, thereby improving the stability of the electrode environment. In this way, it is helpful to further improve the cycle stability of the secondary battery and prolong the cycle life of the secondary battery.

[0034] In a third aspect, an embodiment of the present application provides an electrode sheet, which includes 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 includes a substrate and a first inorganic lithium compound layer coated on at least part of the surface of the substrate, 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.

[0035] The electrode sheet of the third aspect includes an electrode material, and the substrate of the electrode material has been pre-embedded with part of 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 sheet 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. In this way, the electrode sheet of the embodiment of the present application applied to the secondary battery can improve the energy density of the secondary battery and prolong the cycle life of the secondary battery.

[0036] In any embodiment of the present application, the electrode tab further comprises a second inorganic lithium compound layer attached to at least part of the surface of the electrode film layer, the second inorganic lithium compound layer comprising at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide or lithium phosphide.

[0037] When the electrode tab further comprises a second inorganic lithium compound layer attached to at least part 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. Thus, it is beneficial to improve the cycle stability of the secondary battery.

[0038] In any embodiment of the present application, the first inorganic lithium compound layer comprises at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride or lithium sulfide.

[0039] Alternatively, 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, based on the total mass of the first inorganic lithium compound layer.

[0040] More alternatively, the first inorganic lithium compound layer comprises 70%-90% of lithium nitride, 0-30% of lithium oxide, and 0-10% of lithium sulfide, based on the total mass of the first inorganic lithium compound layer.

[0041] When the first inorganic lithium compound layer has the above composition, it is beneficial to protect the substrate and inhibit the side reaction of the substrate with air, so that the electrode material maintains a high lithium supplement efficiency. In addition, when the first inorganic lithium compound layer has the above composition, it is also beneficial to form a uniform, dense and stable protective film on the surface of the electrode tab, thereby further improving the cycle stability of the secondary battery.

[0042] In a fourth aspect, the embodiments of the present application provide a preparation method of an electrode tab, comprising method A or method B.

[0043] Method A:

[0044] Mixing the lithium metal with the complexing agent solution to make the lithium metal react with the complexing agent to obtain a liquid-phase lithiation agent;

[0045] Contacting the liquid-phase lithiation agent with the electrode active material to pre-lithiate the electrode active material by the liquid-phase lithiation agent to obtain a pre-lithiated electrode active material;

[0046] Contacting the pre-lithiated electrode active material with the reactant to form a first inorganic lithium compound layer on at least part of the surface of the pre-lithiated electrode active material to obtain an electrode material;

[0047] The electrode material comprises a substrate and a first inorganic lithium compound layer covering at least part of the surface of the substrate, wherein the substrate comprises a pre-lithiated 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.

[0048] An electrode tab comprising the electrode material is prepared.

[0049] Method B:

[0050] An initial tab is provided, which comprises a current collector and an electrode film layer on at least one side of the current collector, and the electrode film layer comprises an electrode active material.

[0051] The lithium metal is mixed with the complexing agent solution to react with the complexing agent to obtain a liquid-phase lithiation agent.

[0052] The liquid-phase lithiation agent is contacted with the electrode film layer to pre-lithiate the electrode active material with the liquid-phase lithiation agent to obtain a tab comprising a pre-lithiated electrode active material.

[0053] The tab comprising the pre-lithiated electrode active material is contacted with a reactant to form a first inorganic lithium compound layer on the surface of the pre-lithiated electrode active material to obtain an electrode tab comprising the electrode material.

[0054] The electrode material comprises a substrate and a first inorganic lithium compound layer covering at least part of the surface of the substrate, wherein the substrate comprises a pre-lithiated 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.

[0055] The electrode tab prepared according to Method A or Method B comprises an electrode material, the substrate of which has been pre-embedded with part of active lithium ions, and the electrode material can release active lithium ions during the first charging or discharging process, thereby compensating for the loss of active lithium ions in the formation process of the battery. In addition, the electrode material can also form a dense, uniform and stable protective film on the surface of the electrode tab through the first inorganic lithium compound layer, which 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 tab prepared by the embodiments of the present application applied to the secondary battery can improve the energy density of the secondary battery and prolong the cycle life of the secondary battery.

[0056] In any embodiment of the present application, Method A and / or Method B further comprises:

[0057] The complexing agent solution is prepared by uniformly mixing the complexing agent with a solvent to obtain the complexing agent solution.

[0058] Optionally, the complexing agent comprises at least one of naphthalene and derivatives thereof, biphenyl and derivatives thereof, phenanthrene and derivatives thereof, pyrene and derivatives thereof, fluorene and derivatives thereof, indene and derivatives thereof, or aromatic hydrocarbon derivatives containing heteroatom functional groups, more optionally at least one of 2-methylnaphthalene, 1-naphthalenecarbonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, or benzophenone.

[0059] Optionally, the solvent comprises at least one of alkanes and derivatives thereof, aromatic hydrocarbons and derivatives thereof, ethers and derivatives thereof, furans and derivatives thereof, pyrans and derivatives thereof, or esters and derivatives thereof, more optionally at least one of benzene, toluene, xylene, ethylbenzene, ethyleneglycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

[0060] The complexing agent selected from the above-mentioned categories can undergo complexation reaction with lithium metal to generate a liquid-phase lithiating agent with a lower redox potential. Thus, the liquid-phase lithiating agent is more likely to pre-lithiate the electrode active material and embed active lithium ions in the electrode active material, thereby facilitating the improvement of the lithium supplement efficiency of the electrode material. Further, dissolving the complexing agent in the solvent of the above-mentioned categories 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 the lithium supplement efficiency of the electrode sheet.

[0061] In any embodiment of the present application, in the method A and / or the method B, the redox potential of the liquid-phase lithiating agent is 0.05 V-1.5 V, optionally 0.1 V-0.5 V. Thus, the efficiency of pre-lithiation can be further improved, thereby improving the lithium supplement efficiency of the electrode sheet.

[0062] In any embodiment of the present application, in the method A and / or the method B, the molar ratio of lithium metal to the complexing agent is (0.5:1)-(10:1), optionally (1:1)-(4:1).

[0063] In any embodiment of the present application, in the method A and / or the method B, the molar concentration of lithium in the liquid-phase lithiating agent is 0.01 mol / L-10 mol / L, optionally 0.01 mol / L-5 mol / L.

[0064] When the molar ratio of lithium metal to the complexing agent is within the above-mentioned range, not only the reaction efficiency of lithium metal and the complexing agent is improved, but also the content of lithium in the liquid-phase lithiating agent is adjusted within a suitable range. The content of lithium in the liquid-phase lithiating agent within a suitable range can improve the pre-lithiation efficiency of the liquid-phase lithiating agent on the electrode active material, thereby improving the lithium supplement efficiency of the electrode sheet.

[0065] In any embodiment of the present application, in the method A and / or the method B, the molar ratio of lithium element in the liquid-phase lithiation agent to the electrode active material is (0.05:1)-(10:1), which can be (0.1:1)-(5:1). In this way, during the battery formation process, the electrode material can release an appropriate amount of active lithium ions to supplement the active lithium ions lost during the first charge-discharge cycle.

[0066] In any embodiment of the present application, in the method A and / or the method B, the volume distribution particle size Dv50 of the electrode active material is 0.5-40 μm. In this way, it is beneficial to release active lithium ions from the electrode material, improve the lithium supplement efficiency of the electrode sheet, and thus help to further delay the capacity decay of the secondary battery and prolong the cycle life of the secondary battery.

[0067] In any embodiment of the present application, in the method A and / or the method B, the reactant includes at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, dinitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide, or red phosphorus, which can optionally include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide, or red phosphorus.

[0068] By selecting appropriate reactants, the composition of the first inorganic lithiated layer can be controlled. The first inorganic lithiated layer has a suitable composition, which is beneficial to inhibit the side reaction of the substrate with air, so that the electrode material maintains high lithium supplement efficiency, and is also beneficial to control the composition of the protective film on the electrode surface, thereby improving the stability of the electrode environment. In this way, it is helpful to further improve the cycle stability of the secondary battery and prolong the cycle life of the secondary battery.

[0069] In a fifth aspect, the embodiments of the present application provide a battery including 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 sheet of the third aspect, or the electrode sheet prepared according to the preparation method of the fourth aspect. In this way, high energy density and long cycle life can be achieved.

[0070] In a sixth aspect, the embodiments of the present application provide a power utilization device including the battery of the fifth aspect.

[0071] The power utilization device of the embodiments of the present application includes the battery provided by the embodiments of the present application, and thus at least has the same advantages as the battery. BRIEF DESCRIPTION OF DRAWINGS

[0072] Figure 1 is a schematic view of an embodiment of the battery cell of the present application.

[0073] Figure 2 is Figure 1 is an exploded view of the embodiment of the battery cell of the present application shown in FIG. 1.

[0074] Figure 3 This is a schematic diagram of one embodiment of the battery module of this application.

[0075] Figure 4 This is a schematic diagram of one embodiment of the battery pack of this application.

[0076] Figure 5 yes Figure 4 The diagram shown is an exploded view of an embodiment of the battery pack of this application.

[0077] Figure 6 This is a schematic diagram of an embodiment of the battery of this application used as a power source for an electrical device.

[0078] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Cover plate. Detailed Implementation

[0079] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the electrode materials and their preparation methods, electrode sheets and their preparation methods, and battery and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0080] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0081] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0082] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0083] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0084] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0085] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0086] In this article, derivatives generally refer to products derived from the substitution of hydrogen atoms or groups of atoms in a polymer by other atoms or groups of atoms.

[0087] With the application and promotion of secondary batteries in various electronic products and new energy vehicles, higher requirements have been placed on the energy density and cycle performance of secondary batteries.

[0088] During the initial charging process of a rechargeable 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 resulting in irreversible capacity loss. Furthermore, during charge-discharge cycles, the SEI film may rupture due to factors such as the expansion of the negative electrode active material, requiring the continuous consumption of active lithium ions to form a new SEI film. This further exacerbates the battery's capacity decay, leading to a decrease in energy density and a shortened cycle life.

[0089] Therefore, this application provides an electrode material and a method for preparing the same, which can effectively replenish consumed active lithium ions; this application also provides an electrode sheet containing the electrode material and a method for preparing the same, a battery, and an electrical device.

[0090] Electrode materials

[0091] In a first aspect, embodiments of this application propose an electrode material comprising a substrate and a first inorganic lithium compound layer, wherein the first inorganic lithium compound layer covers at least a portion of the surface of the substrate; the substrate comprises a pre-lithiated 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.

[0092] Not intended to be limited by any theory or interpretation, the electrode material of this application embodiment includes a pre-lithiated electrode active material. This pre-lithiated electrode active material has some active lithium ions pre-embedded. During the first 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 battery formation. Compared to related technologies that directly composite a metallic lithium layer on the surface of the negative electrode, the electrode material of this application embodiment has the advantage of more uniform lithium replenishment. Furthermore, the electrode material of this application embodiment includes a first inorganic lithium compound layer. This first inorganic lithium compound layer, on the one hand, isolates the substrate from air, improving the chemical stability of the substrate and thus maintaining a high lithium replenishment efficiency; on the other hand, it can form a dense, uniform, and stable protective film on the electrode surface. This protective film can function similarly to an SEI film, thereby improving the environmental stability of the electrode, reducing irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode material of this application embodiment, when applied to a secondary battery, can improve the energy density of the secondary battery and extend its cycle life.

[0093] The term "pre-lithiated electrode active material" has a meaning known in the art, referring to an electrode active material pre-intercalated with active lithium ions. The electrode active material may include electrode active materials known in the art that have not undergone pre-lithiation treatment; this application does not limit the specific type of electrode active material. As an example, the electrode active material may include at least one known positive electrode active material, or at least one known negative electrode active material.

[0094] The type of positive electrode active material is not specifically limited, and any positive electrode active material known in the art for use in secondary batteries can be used. For example, the positive electrode active material may include at least one of the following: lithium transition metal oxides, lithium-containing phosphates with an olivine structure, and their respective modified compounds. Examples of lithium transition metal oxides may 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 lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds. The embodiments of this application are not limited to these materials, and 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.

[0095] Optionally, 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 materials, cobalt-free positive electrode materials, lithium manganese iron phosphate, and lithium manganese oxide.

[0096] The type of negative electrode active material is not specifically limited, and any negative electrode active material known in the art for use in secondary batteries can be used. As an example, the negative electrode active material may include at least one of the following: graphite, soft carbon, hard carbon, mesophase carbon microspheres, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxide, and tin alloys. This 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.

[0097] Optionally, 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 materials, tin-based materials, phosphorus-based materials, and lithium titanate.

[0098] In some embodiments, based on the total mass of the first inorganic lithium compound layer, the first inorganic lithium compound 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.

[0099] Optionally, in some embodiments, based on the total mass of the first inorganic lithiide layer, the first inorganic lithiide layer may include 0-100% lithium fluoride, 0-80% lithium oxide, 0-50% lithium nitride, 0-100% lithium carbonate, and 0-55% lithium sulfide.

[0100] In some embodiments, the first inorganic lithium compound layer may include at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, or lithium sulfide.

[0101] Optionally, in some embodiments, based on the total mass of the first inorganic lithiide layer, the first inorganic lithiide layer may include 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

[0102] More alternatively, in some embodiments, based on the total mass of the first inorganic lithiide layer, the first inorganic lithiide layer may include 70%-90% lithium nitride, 0-30% lithium oxide, and 0-10% lithium sulfide.

[0103] When the first inorganic lithium-ion layer has the above-mentioned composition, it is beneficial to protect the substrate and suppress side reactions between the substrate and air, thereby enabling the electrode material to maintain a high lithium replenishment efficiency. Furthermore, when the first inorganic lithium-ion layer has the above-mentioned composition, its application in secondary batteries facilitates the formation of a uniform, dense, and stable protective film on the electrode surface, thereby further improving the cycle stability of the secondary battery.

[0104] The composition of the first inorganic lithium compound layer can be determined using methods and equipment known in the art. As an example, the content of each element (e.g., O, N, P, S, F, C, Li, etc.) in the first inorganic lithium compound layer can be determined using X-ray photoelectron spectroscopy (XPS). Based on the proportion of each element and the chemical formula of the inorganic lithium compound, the components and their content in the first inorganic lithium compound layer can be determined. As another example, when sampling from a battery, the composition of the first inorganic lithium compound layer can also be determined by the following steps: disassembling the battery and removing the electrode plates; soaking the electrode plates in an organic solvent to remove electrolyte and additives; drying the electrode plates, randomly selecting a region as a cross-section, and determining the location of the first inorganic lithium compound layer using a scanning electron microscope (SEM) at a magnification of 3000x or higher (e.g., 3000x, 10000x, or 100000x, etc.). The location of the inorganic lithium compound layer is marked as the target region; then, at a magnification of 500x or higher (e.g., 500x or 1000x), a region of a certain size (e.g., a 100μm*100μm region can be selected when the magnification is 500x; a 10μm*10μm region can be selected when the magnification is 1000x) is selected for EDS surface scanning for 2 min to obtain the element types and contents of the target region. Based on the content ratio of each element and the chemical formula of the inorganic lithium compound, the composition of the first inorganic lithium compound layer is determined.

[0105] In some embodiments, the thickness of the first inorganic lithium compound layer can be 2nm-5000nm, for example, it can be 2nm, 5nm, 10nm, 50nm, 100nm, 300nm, 500nm, 1000nm, 2000nm, 3000nm, 4000nm, 5000nm, or a range of any two of the above values. For example, the thickness of the first inorganic lithium compound layer can be 2nm-5000nm, 2nm-4000nm, 2nm-3000nm, 2nm-2000nm, 2nm-1000nm, 5nm-5000nm, 5nm-3000nm, 5nm-1000nm, 5nm-500nm, 5nm-300nm, 10nm-4000nm, 10nm-2000nm, 10nm-500nm, 50nm-5000nm, 50nm-3000nm, 50nm-1000nm, 50nm-500nm, etc.

[0106] Optionally, in some embodiments, the thickness of the first inorganic lithiumbide layer can also be 20nm-1000nm. For example, it can be 20nm, 50nm, 100nm, 300nm, 500nm, 800nm, 1000nm, or any range of two of the above values. For example, the thickness of the first inorganic lithium compound 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, etc.

[0107] Not intended to be limited by any theory or explanation, the thickness of the first inorganic lithium-ion layer within the aforementioned suitable range can, on the one hand, effectively isolate the substrate from direct contact with air, thereby improving the chemical stability of the substrate; on the other hand, it can maintain a high substrate content in the electrode material. This significantly improves the lithium replenishment efficiency of the electrode material. Furthermore, the thickness of the first inorganic lithium-ion layer within the aforementioned suitable range also helps to form a dense, uniform, and stable protective film on the electrode surface, further enhancing the environmental stability of the electrode. This can suppress capacity decay in the secondary battery and extend its cycle life.

[0108] The thickness of the first inorganic lithium compound layer has a meaning known in the art and can be determined using equipment and methods known in the art. For example, the thickness of the first inorganic lithium compound layer on the surface of the lithium compound material can be observed using a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

[0109] In some embodiments, the volumetric particle size distribution Dv50 of the electrode material can be 0.6 μm-60 μm, for example, it can be 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 any range of two of the above values. For example, the volumetric particle size distribution 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, etc.

[0110] 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 any range of two of the above values.

[0111] This is not intended to be limited by any theory or explanation. When the volume distribution particle size Dv50 of the electrode material is within the aforementioned suitable range, it not only allows the electrode material to have a suitable lithium-ion transport path but also enables it to possess good electrolyte wetting properties. This facilitates the extraction 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 its cycle life.

[0112] The volumetric particle size distribution (Dv50) of an electrode material has a meaning known in the art; it represents the particle size corresponding to the cumulative particle size distribution percentage of the electrode material reaching 50% in a volumetric particle size distribution. The volumetric particle size distribution (Dv50) can be determined using equipment and methods known in the art. For example, it can be determined using a laser particle size analyzer (e.g., Malvern Master Size 3000) according to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method.

[0113] In some embodiments, the electrode material is a positive electrode material. The positive electrode material can refer to an electrode material whose substrate includes a pre-lithiated positive electrode active material.

[0114] The lithium content of the cathode material can be 1%-30%, for example, it can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, or any two of the above values.

[0115] Optionally, in some embodiments, the lithium content of the cathode material can be 5%-20%, for example, 5%, 8%, 10%, 12%, 15%, 18%, 20%, or any combination of two of the above values.

[0116] The lithium content of the cathode material can be supplemented by (C1-C) 10 ) / C 10 ×100% characterization, where C1 is the actual specific capacity of the cathode material, in mAh / g, C 10 This represents the theoretical specific capacity of the positive electrode active material, expressed in mAh / g.

[0117] The actual specific capacity C1 of the cathode material has a well-known meaning in the art, which can represent the ratio of the actual electrical capacity that the cathode material can release to the mass of the cathode material.

[0118] The theoretical specific capacity C of the positive electrode active material 10 With a meaning well-known in the art, it can represent the ratio of the theoretically releasetable capacitance 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.

[0119] This is not intended to be limited by any theory or explanation. When the cathode material has a suitable lithium replenishment content, its application in the cathode of a secondary battery can release an appropriate amount of active lithium ions to replenish the active lithium ions lost during the first charge-discharge cycle and reduce the risk of lithium plating due to excessive lithium replenishment. Therefore, the application of cathode materials in secondary batteries enables them to possess both good cycle performance and high reliability.

[0120] The lithium content of the cathode material can be determined using methods and equipment known in the art. The actual specific capacity C1 of the cathode material can be determined using equipment and methods known in the art. Those skilled in the art can determine the theoretical specific capacity C1 of the cathode active material based on its type and chemical composition. 10 .

[0121] As an example, C1 can be determined by testing the lithium extraction capacity of the cathode material. Specifically, the cathode material can be mixed with an appropriate amount of conductive agent and binder in a certain proportion to prepare a single-sided coated cathode sheet. The lithium extraction capacity CmAh of the cathode sheet containing m1 g of cathode material can be tested by directly charging a coin cell to the rated voltage. The actual specific capacity C1 of the cathode material can then be calculated using the formula C1 = C / m1. The aforementioned rated voltage has a meaning known in the art; it can represent the rated voltage corresponding to the substrate of the cathode material. For example, when the substrate is pre-lithiated lithium iron phosphate, the rated voltage can be 3.8V; when the substrate is pre-lithiated nickel-cobalt-manganese ternary material, the rated voltage can be 4.2V-4.4V.

[0122] In some embodiments, the electrode material is a negative electrode material. The negative electrode material can refer to an electrode material whose substrate includes a pre-lithiated negative electrode active material.

[0123] The lithium content of the negative electrode material can be 1%-100%, for example, it can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 80%, 100%, or any combination of two of the above values.

[0124] Optionally, in some embodiments, the lithium 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 any range of two of the above values.

[0125] The lithium content of the negative electrode material can be supplemented by (C) 20 -C2) / C 20 ×100% characterization, where C2 is the actual specific capacity of the negative electrode material, in mAh / g, C 20 This represents the theoretical specific capacity of the negative electrode active material, expressed in mAh / g.

[0126] The actual specific capacity C2 of the negative electrode material has a well-known meaning in the art, which can represent the ratio of the actual electrical capacity that the negative electrode material can release to the mass of the negative electrode material.

[0127] The theoretical specific capacity C of the negative electrode active material 20 With a meaning well-known in the art, it can represent the ratio of the theoretically releasetable capacitance 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.

[0128] This is not intended to be limited by any theory or explanation. When the negative electrode material has a suitable lithium replenishment capacity, its application in the negative electrode of a secondary battery can release an appropriate amount of active lithium ions to replenish the active lithium ions lost during the first charge-discharge cycle and reduce the risk of lithium plating due to excessive lithium replenishment. Therefore, the application of negative electrode materials in secondary batteries enables them to possess both good cycle performance and high reliability.

[0129] The lithium content of the negative electrode material can be determined using methods and equipment known in the art. The actual specific capacity C2 of the negative electrode material can be determined using equipment and methods known in the art. Those skilled in the art can determine the theoretical specific capacity C of the negative electrode active material based on its type and chemical composition. 20 .

[0130] As an example, C2 can be determined by testing the lithium intercalation capacity of the negative electrode material. Specifically, the negative electrode material can be mixed with an appropriate amount of conductive agent and binder in a certain proportion to prepare a single-sided coated negative electrode sheet; using a coin cell lithium half-cell, it is discharged to a preset voltage, and the lithium intercalation capacity C'mAh of the negative electrode sheet containing m2 g of negative electrode material is tested; the actual specific capacity C2 of the negative electrode material can be calculated using the formula C2=C' / m2. The 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 lithium-intercalated state. As an example, the preset voltage for graphite, soft carbon, hard carbon, mesophase carbon microspheres, silicon-based materials, and tin-based materials can be 0.01V, and the preset voltage for lithium titanate can be 2.0V.

[0131] Electrode material preparation method

[0132] Secondly, embodiments of this application provide a method for preparing an electrode material, comprising the following steps S110-S130.

[0133] S110 involves mixing lithium metal with a complexing reagent solution to allow the lithium metal to react with the complexing reagent, thereby obtaining a liquid-phase lithiating agent.

[0134] In step S110, the lithium metal can be in any form, for example, it can include at least one of lithium blocks, lithium foil, and lithium powder, and is not limited herein. The complexing agent can include reagents known in the art that can undergo a complexing reaction with lithium metal, and those skilled in the art can select them as needed, and are not limited herein. In some embodiments, mixing the lithium metal with the complexing agent solution can include mixing the lithium metal with the complexing agent and stirring until homogeneous. The stirring temperature and time are not specifically limited and can be adjusted as needed by those skilled in the art. As an example, the stirring temperature can be 0℃-60℃, optionally 10℃-40℃, and the stirring time can be 0.1h-12h, optionally 1h-6h.

[0135] S120, the liquid-phase lithiating agent is brought into contact with the electrode active material so that the liquid-phase lithiating agent prelithiates the electrode active material to obtain a prelithiated electrode active material.

[0136] In step S120, the contact between the liquid-phase lithiating agent and the electrode active material can be achieved in various ways, and this application does not limit this method. In some embodiments, the electrode active material can be impregnated with the liquid-phase lithiating agent to pre-lithiate it. In step S120, the temperature and time for pre-lithiation of the electrode active material by the liquid-phase lithiating agent are not specifically limited and can be adjusted as needed by those skilled in the art. As an example, the pre-lithiation temperature can be 0℃-80℃, optionally 10℃-50℃, and the pre-lithiation time can be 1min-6h, optionally 5min-30min.

[0137] S130, the pre-lithiated electrode active material is contacted with the reactants to form a first inorganic lithium layer on at least a portion of the surface of the pre-lithiated electrode active material, thereby obtaining the electrode material.

[0138] 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 generate 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 appropriate reactant as needed. After the pre-lithiated electrode active material comes into contact with the reactant, the reactant can react with the 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 lithide layer on at least a portion of the surface of the pre-lithiated electrode active material; and / or, the reactant can react with the material on the surface of the pre-lithiated electrode active material to form a first inorganic lithide layer on at least a portion of the surface of the pre-lithiated electrode active material. The reaction temperature and reaction time in step S130 are not specifically limited and can be adjusted as needed by those skilled in the art. As an example, the reaction temperature in step S130 can be 0℃-80℃, optionally 10℃-50℃, and the reaction time can be 1min-60min, optionally 2min-10min.

[0139] The electrode material prepared according to steps S110 to S130 above includes a substrate and a first inorganic lithium compound layer, wherein the first inorganic lithium compound layer covers at least a portion of the surface of the substrate. The substrate includes a pre-lithiated 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.

[0140] The method provided in this application is simple to operate, operates under mild conditions, and is easy to control. The substrate of the prepared electrode material has some active lithium ions pre-embedded. 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. Furthermore, the electrode material prepared by the method of this application can also form a dense, uniform, and stable protective film on the electrode surface through a first inorganic lithium compound layer. This protective film can play a similar role to the SEI film, thereby improving the environmental stability of the electrode, reducing irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode material prepared in this application, when applied to a secondary battery, can improve the energy density of the secondary battery and extend its cycle life.

[0141] In some embodiments, the preparation method may further include: providing a complexing reagent solution, including mixing the complexing reagent with a solvent to obtain a complexing reagent solution.

[0142] In some embodiments, the coordinating 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. Optionally, in some embodiments, the coordinating agent may include at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, benzophenone, pyridine, and quinoline.

[0143] In some embodiments, the solvent may include at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ethers and their derivatives, furans and their derivatives, pyrans and their derivatives, and esters and their derivatives. Optionally, the solvent may include at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

[0144] Not intended to be limited to any particular theory or explanation, the complexing reagents selected from the above categories can undergo complexation reactions with lithium metal to generate liquid-phase lithiating agents with lower redox potentials. Therefore, these liquid-phase lithiating agents more easily pre-lithiate electrode active materials, embedding active lithium ions within them, thereby improving the lithium replenishment efficiency of the electrode materials. Furthermore, using the aforementioned solvents to dissolve the complexing reagents allows for further adjustment of the redox potential of the liquid-phase lithiating agent within a suitable range, further enhancing the pre-lithiation efficiency and consequently improving the lithium replenishment efficiency of the electrode materials.

[0145] In some embodiments, the redox potential of the liquid-phase lithiating agent can be 0.05V-1.5V, for example, it can be 0.05V, 0.10V, 0.20V, 0.30V, 0.40V, 0.50V, 0.60V, 0.70V, 0.80V, 0.90V, 1.0V, 1.5V, or any range of two of the above values.

[0146] Optionally, in some embodiments, 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, etc.

[0147] If the redox potential of the liquid-phase lithiation agent is within the above-mentioned suitable range, the pre-lithiation efficiency can be further improved, thereby improving the lithium replenishment efficiency of the electrode material.

[0148] The redox potential of a liquid-phase lithiating agent has a meaning known in the art and can be determined using known equipment and methods, such as cyclic voltammetry. Specifically, Pt can be used as the working electrode, and Li as the reference and counter electrode, forming an electrolytic cell with the liquid-phase lithiating agent. The voltage is scanned from the open-circuit voltage to 0.01V, and then cycled three times from 0.01V to 1.5V to obtain the redox peak of the liquid-phase lithiating agent, thus measuring its redox potential.

[0149] In some embodiments, the molar ratio of lithium metal to the complexing agent can be (0.5:1)-(10:1), for example, it can be 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or any range of two of the above ratios. Optionally, 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), etc.

[0150] In some embodiments, the lithium content in the liquid-phase lithiation agent can be 0.01 mol / L to 10 mol / L, for example, it can be 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 any range of two of the above values. Optionally, the lithium content in the liquid-phase lithiation agent can also be 0.01 mol / L to 5 mol / L, 0.01 mol / L to 4 mol / L, 0.01 mol / L to 3 mol / L, 0.01 mol / L to 2 mol / L, 0.01 mol / L to 1 mol / L, 0.5 mol / L to 5 mol / L, 0.5 mol / L to 3 mol / L, 0.5 mol / L to 1 mol / L, 1 mol / L to 5 mol / L, 2 mol / L to 4 mol / L, etc.

[0151] This is not intended to be limited by any theory or explanation. When the molar ratio of lithium metal to the complexing reagent is within the above range, it not only helps to improve the reaction efficiency of lithium metal and the complexing reagent, but also helps to adjust the lithium content in the liquid-phase lithiation agent to a suitable range. In the liquid-phase lithiation agent, a suitable lithium content can improve the pre-lithiation efficiency of the liquid-phase lithiation agent on the electrode active material.

[0152] In some embodiments, the molar ratio of lithium element to electrode active material in the liquid phase lithiation agent can be (0.05:1)-(10:1), and can be selected as (0.1:1)-(5:1).

[0153] Not intended to be limited by any theory or explanation, when the molar ratio of lithium to electrode active material in the liquid-phase lithiating agent is within the aforementioned suitable range, an appropriate amount of active lithium ions can be embedded in the electrode active material. Therefore, during battery formation, the electrode material can release an appropriate amount of active lithium ions to replenish the active lithium ions lost during the first charge-discharge cycle.

[0154] 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, etc.

[0155] Not intended to be limited by any theory or explanation, when the volume distribution particle size Dv50 of the electrode active material is within the aforementioned suitable range, not only can the prepared electrode material possess a suitable lithium-ion transport path, but it can also exhibit good electrolyte wetting properties. This facilitates the extraction of active lithium ions from the electrode material, improving the lithium replenishment efficiency of the electrode material, thereby helping to further delay the capacity decay of the secondary battery and extend its cycle life.

[0156] The volume distribution particle size Dv50 of the electrode active material can be determined by referring to the test method for the volume distribution particle size Dv50 of the electrode material.

[0157] In some embodiments, the reactants may include at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, dinitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide, or red phosphorus. Optionally, the reactants may include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide, or red phosphorus.

[0158] Reactants selected from the above categories can react with liquid-phase lithiating agents and / or pre-lithiated electrode active materials. By selecting suitable reactants, the composition of the first inorganic lithiide layer can be controlled. A suitable composition of the first inorganic lithiide layer helps to suppress side reactions between the substrate and air, maintaining high lithium replenishment efficiency of the electrode material. Furthermore, it helps to control the composition of the protective film on the electrode surface, thereby improving the stability of the electrode environment. This contributes to further improving the cycle stability of the secondary battery and extending its cycle life.

[0159] The contact between the reactants and the pre-lithiated electrode active material can be achieved in various ways, and this application does not limit this. In some embodiments, when the reactants are gases, they can be directly introduced into the slurry obtained in step S120. In some embodiments, when the reactants are solids, they 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 allows for more uniform and thorough contact between the reactants and the pre-lithiated electrode active material, thereby facilitating the smooth progress of the reaction. The organic solvents mentioned above may include at least one of alkanes, aromatic hydrocarbons, ethers, esters, and their halogenated derivatives, for example, 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%-20%.

[0160] In some embodiments, the preparation method may further include: drying the electrode material.

[0161] This application does not limit the drying atmosphere; the drying atmosphere can include any atmosphere that does not cause side reactions with the electrode material. In some embodiments, the drying atmosphere may include nitrogen, argon, dry air, or a combination thereof. Optionally, in some embodiments, the drying atmosphere may include nitrogen, argon, or a combination thereof. This application does not limit the drying temperature and time, which can be adjusted as needed by those skilled in the art. In some embodiments, the drying temperature can be 0℃-200℃, optionally 20℃-120℃, and the drying time can be 5 min-6 h. This can improve the stability of the chemical properties of the electrode material.

[0162] Electrode plates

[0163] Thirdly, embodiments of this application provide an electrode sheet, 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 covers at least a portion of the surface of the substrate. The substrate includes a pre-lithiated electrode active material. The first inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide, or lithium phosphide.

[0164] The third aspect of the electrode sheet includes an electrode material. The substrate of the electrode material has pre-embedded 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 battery formation. Furthermore, the electrode material can form a dense, uniform, and stable protective film on the surface of the electrode sheet through a first inorganic lithium compound layer. This protective film can function similarly to an SEI film, thereby improving the environmental stability of the electrode, reducing irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode sheet of this embodiment, when applied to a secondary battery, can improve the energy density of the secondary battery and extend its cycle life.

[0165] It should be noted that, in the embodiments of this application, the structure of the electrode material in the electrode film layer can be determined using equipment and methods known in the art. As an example, it can be obtained through the following method: Obtain the electrode sheet (when sampling from the battery, the battery can be directly disassembled, the electrode sheet removed, and dried); randomly select an area, perform argon ion cross-section polishing, and take a transmission electron microscope (TEM) image of the electrode film layer at a magnification of 3000x or higher (e.g., 3000x, 30000x, 100000x, or 500000x, etc.); process the TEM image, adjust the contrast appropriately, and the substrate of the electrode material and the first inorganic lithium compound layer can be observed. The thickness of the first inorganic lithium compound layer can also be determined using the TEM image.

[0166] It should be noted that, in the embodiments of this 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 obtained by the following method: Obtain the electrode sheet (when sampling from the battery, the battery can be directly disassembled, the electrode sheet removed and dried); randomly select an area, perform argon ion cross-section polishing treatment, and take an electron microscope image (SEM image) of the electrode film layer at a magnification of 500x or higher (e.g., 500x, 1000x, or 5000x, etc.); process the SEM image, adjust the appropriate contrast, and the electrode material can be observed. The volume distribution particle size Dv50 of the electrode material can be determined by statistically analyzing the particle size of the electrode material in the field of view.

[0167] In some embodiments, the electrode sheet may further include a second inorganic lithium compound layer attached to at least a portion of the surface of the electrode film. The second inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide, or lithium phosphide.

[0168] In this embodiment, the second inorganic lithium compound layer may be a discrete layered structure formed separately on at least a portion of the surface of the electrode film layer.

[0169] In some embodiments, the composition of the second inorganic lithium layer may be the same as that of the first inorganic lithium layer.

[0170] Not intended to be limited by any theory or explanation, when the electrode sheet also includes a second inorganic lithium compound layer attached to at least a portion of the surface of the electrode film, it is beneficial to further improve the stability of the electrode environment during charge-discharge cycles. This, in turn, helps to improve the cycle stability of the secondary battery.

[0171] In some embodiments, based on the total mass of the first inorganic lithium compound layer, the first inorganic lithium compound 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.

[0172] Optionally, in some embodiments, based on the total mass of the first inorganic lithiide layer, the first inorganic lithiide layer may include 0-100% lithium fluoride, 0-80% lithium oxide, 0-50% lithium nitride, 0-100% lithium carbonate, and 0-55% lithium sulfide.

[0173] In some embodiments, the first inorganic lithium compound layer may include at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, or lithium sulfide.

[0174] Optionally, in some embodiments, based on the total mass of the first inorganic lithiide layer, the first inorganic lithiide layer may include 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

[0175] More alternatively, in some embodiments, based on the total mass of the first inorganic lithiide layer, the first inorganic lithiide layer may include 70%-90% lithium nitride, 0-30% lithium oxide, and 0-10% lithium sulfide.

[0176] When the first inorganic lithium-ion layer has the above-mentioned composition, it is beneficial to protect the substrate and suppress side reactions between the substrate and air, thereby enabling the electrode material to maintain a high lithium replenishment efficiency. In addition, when the first inorganic lithium-ion layer has the above-mentioned composition, it is also beneficial to form a uniform, dense and stable protective film on the surface of the electrode sheet, thereby further improving the cycle stability of the secondary battery.

[0177] In some embodiments, based on the total mass of the second inorganic lithium compound layer, the second inorganic lithium compound 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.

[0178] Optionally, in some embodiments, based on the total mass of the second inorganic lithium compound layer, the second inorganic lithium compound layer may include 0-100% lithium fluoride, 0-80% lithium oxide, 0-50% lithium nitride, 0-100% lithium carbonate, and 0-55% lithium sulfide.

[0179] In some embodiments, the second inorganic lithium compound layer may include at least two of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, or lithium sulfide.

[0180] Optionally, in some embodiments, based on the total mass of the second inorganic lithium compound layer, the second inorganic lithium compound layer may include 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

[0181] More alternatively, in some embodiments, based on the total mass of the second inorganic lithiide layer, the second inorganic lithiide layer may include 70%-90% lithium nitride, 0-30% lithium oxide, and 0-10% lithium sulfide.

[0182] The electrode in this embodiment can be a positive electrode or a negative electrode. When the electrode is a positive electrode, the electrode material is a positive electrode material. When the electrode is a negative electrode, the electrode material is a negative electrode material.

[0183] In some embodiments, the electrode sheet is a positive electrode sheet, and the electrode material is a positive electrode material. The electrode film layer may also include other positive electrode active materials.

[0184] Optionally, in some embodiments, based on the total mass of the positive electrode film, 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%.

[0185] In some embodiments, the electrode sheet is a negative electrode sheet, and the electrode material is a negative electrode material. The electrode film layer may also include other negative electrode active materials.

[0186] Optionally, in some embodiments, the mass percentage of the negative electrode material can be 10wt%-98wt%, or optionally 50wt-98wt%, based on the total mass of the negative electrode film. The mass percentage of other negative electrode active materials can be less than or equal to 95wt%.

[0187] When the mass percentage of electrode material in the electrode film is within the aforementioned suitable range, an appropriate amount of active lithium ions can be released to replenish the active lithium ions lost during the first charge-discharge cycle and reduce the risk of lithium plating due to excessive replenishment. This allows the secondary battery to possess both good cycle performance and high reliability.

[0188] The other positive electrode active materials mentioned above may include positive electrode active materials of the same type as the pre-lithiated positive electrode active material, or they may include positive electrode active materials of a different type. Similarly, the other negative electrode active materials may include negative electrode active materials of the same type as the pre-lithiated negative electrode active material, or they may include negative electrode active materials of a different type. The embodiments of the electrode active materials have been described and illustrated in detail above, and will not be repeated here.

[0189] In some embodiments, the electrode sheet is a positive electrode sheet, and the lithium content of the positive electrode sheet can be 1%-30%.

[0190] The lithium content of the positive electrode can be increased by adjusting the (C3-C) content. 30 ) / C 30 ×100% characterization, where C3 is the actual specific capacity of the positive electrode active material contained in the positive electrode sheet, in mAh / g; C 30 This represents the theoretical specific capacity of the unlithiated positive electrode active material, expressed in mAh / g. The positive electrode active material may include the positive electrode material itself and other positive electrode active materials contained within the positive electrode sheet.

[0191] The lithium content of the positive electrode can be determined using methods and equipment known in the art. C3 can be determined by referring to the testing method for the actual specific capacity C1 of the positive electrode material, which will not be elaborated here. The theoretical specific capacity C of the unlithiated positive electrode active material... 30 The theoretical specific capacity C of the positive electrode active material can be determined based on its type, chemical composition, and content. As an example, if the positive electrode active material comprises m3 g of a first positive electrode active material and m4 g of a positive electrode material, and the substrate of this positive electrode material is a pre-lithiated second positive electrode active material, then the theoretical specific capacity C of the unlithiated positive electrode active material is... 30 = [m3 / (m3+m4)]×C 31 +[m4 / (m3+m4)]×C 32 , where C 31 The theoretical specific capacity of the first positive electrode active material is expressed in mAh / g; C 32 This represents the theoretical specific capacity of the second positive electrode active material, expressed in mAh / g.

[0192] In some embodiments, the electrode sheet is a negative electrode sheet, and the lithium content of the negative electrode sheet can be 1%-50%. Optionally, the lithium content of the negative electrode sheet can be 30%-50%.

[0193] The lithium content of the negative electrode can be adjusted by (C) 40 -C4) / C 40 ×100% characterization, where C4 is the actual specific capacity of the negative electrode active material contained in the negative electrode sheet, in mAh / g, C 40 This represents the theoretical specific capacity of the unlithiated negative electrode active material, expressed in mAh / g. The negative electrode active material may include the negative electrode material itself and other negative electrode active materials contained within the negative electrode sheet.

[0194] The lithium content of the negative electrode sheet can be determined using methods and equipment known in the art. C4 can be determined by referring to the testing method for the actual specific capacity C2 of the negative electrode material, which will not be elaborated here. The theoretical capacity C of the unlithiated negative electrode active material... 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 related to C 30 Similarly, I will not elaborate further here.

[0195] When the lithium content of the electrode sheet meets the given range, its application in a secondary battery allows for the release of an appropriate amount of active lithium ions to replenish those lost during the first charge-discharge cycle, reducing the risk of lithium plating due to excessive replenishment. Therefore, the application of these electrode sheets in secondary batteries enables the batteries to possess both good cycle performance and high reliability.

[0196] Methods for preparing electrode sheets

[0197] Fourthly, embodiments of this application provide a method for preparing an electrode sheet, which may include method A or method B.

[0198] Method A may include the following steps S210 to S240.

[0199] S210 involves mixing lithium metal with a complexing reagent solution to allow the lithium metal to react with the complexing reagent, thereby obtaining a liquid-phase lithiating agent.

[0200] S220 involves contacting a liquid-phase lithiating agent with an electrode active material to pre-lithiate the electrode active material, thereby obtaining a pre-lithiated electrode active material.

[0201] S230, the pre-lithiated electrode active material is contacted with the reactants to form a first inorganic lithium compound layer on at least a portion of the surface of the pre-lithiated electrode active material, thereby obtaining an electrode material; wherein the electrode material includes: a substrate, the substrate including the pre-lithiated electrode active material; and a first inorganic lithium compound layer covering 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.

[0202] S240, preparing an electrode sheet including electrode material.

[0203] The implementation methods of steps S210 to S230 can be the same as those of steps S110 to S130. The implementation methods of steps S110 to S130 have been described in detail above and will not be repeated here. Step S240 can be implemented using methods known in the art, and is not limited thereto.

[0204] The electrode sheet prepared according to method A includes an electrode material. The substrate of the electrode material has pre-embedded 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 battery formation. Furthermore, the electrode material can form a dense, uniform, and stable protective film on the surface of the electrode sheet through a first inorganic lithium oxide layer. This protective film can function similarly to an SEI film, thereby improving the environmental stability of the electrode, reducing irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode sheet prepared according to the embodiments of this application, when applied to a secondary battery, can improve the energy density of the secondary battery and extend its cycle life.

[0205] In some embodiments, method A may further include: providing a complexing reagent solution, including mixing the complexing reagent with a solvent to obtain a complexing reagent solution.

[0206] In some embodiments, the coordinating 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. Optionally, in some embodiments, the coordinating agent may include at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, benzophenone, pyridine, and quinoline.

[0207] In some embodiments, the solvent may include at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ethers and their derivatives, furans and their derivatives, pyrans and their derivatives, and esters and their derivatives. Optionally, the solvent may include at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

[0208] Not intended to be limited to any particular theory or explanation, the complexing reagents selected from the above categories can undergo complexation reactions with lithium metal to generate liquid-phase lithiating agents with lower redox potentials. Therefore, these liquid-phase lithiating agents more easily pre-lithiate electrode active materials, embedding active lithium ions within them, thereby improving the lithium replenishment efficiency of the electrode material. Furthermore, using the aforementioned solvents to dissolve the complexing reagents allows for further adjustment of the redox potential of the liquid-phase lithiating agent within a suitable range, further enhancing the pre-lithiation efficiency and consequently improving the lithium replenishment efficiency of the electrode.

[0209] In some embodiments, in method A, the redox potential of the liquid-phase lithiating agent can be 0.05V-1.5V, for example, it can be 0.05V, 0.10V, 0.20V, 0.30V, 0.40V, 0.50V, 0.60V, 0.70V, 0.80V, 0.90V, 1.0V, 1.5V, or any range of two of the above values.

[0210] 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, etc.

[0211] When the redox potential of the liquid-phase lithiation agent is within the above-mentioned suitable range, the pre-lithiation efficiency can be further improved, thereby improving the lithium replenishment efficiency of the electrode sheet.

[0212] In some embodiments, in method A, the molar ratio of lithium metal to the complexing reagent can be (0.5:1)-(10:1), for example, it can be 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or any range of two of the above ratios. Optionally, the molar ratio of lithium metal to the complexing reagent 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), etc.

[0213] In some embodiments, the lithium content in the liquid-phase lithiation agent can be 0.01 mol / L to 10 mol / L, for example, it can be 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 any range of two of the above values. Optionally, the lithium content in the liquid-phase lithiation agent can also be 0.01 mol / L to 5 mol / L, 0.01 mol / L to 4 mol / L, 0.01 mol / L to 3 mol / L, 0.01 mol / L to 2 mol / L, 0.01 mol / L to 1 mol / L, 0.5 mol / L to 5 mol / L, 0.5 mol / L to 3 mol / L, 0.5 mol / L to 1 mol / L, 1 mol / L to 5 mol / L, 2 mol / L to 4 mol / L, etc.

[0214] This is not intended to be limited by any theory or explanation. When the molar ratio of lithium metal to the complexing reagent is within the above range, it not only helps to improve the reaction efficiency of lithium metal and the complexing reagent, but also helps to adjust the lithium content in the liquid-phase lithiation agent to a suitable range. In the liquid-phase lithiation agent, a suitable lithium content can improve the pre-lithiation efficiency of the liquid-phase lithiation agent on the electrode active material, thereby improving the lithium replenishment efficiency of the electrode sheet.

[0215] In some embodiments, in method A, the molar ratio of lithium element to electrode active material in the liquid phase lithiating agent can be (0.05:1)-(10:1), and can be selected as (0.1:1)-(5:1).

[0216] Not intended to be limited by any theory or explanation, when the molar ratio of lithium to electrode active material in the liquid-phase lithiating agent is within the aforementioned suitable range, an appropriate amount of active lithium ions can be embedded in the electrode active material. Therefore, during battery formation, the electrode material can release an appropriate amount of active lithium ions to replenish the active lithium ions lost during the first charge-discharge cycle.

[0217] In some embodiments, in method A, 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, etc.

[0218] Not intended to be limited by any theory or explanation, when the volume distribution particle size Dv50 of the electrode active material is within the aforementioned suitable range, not only can the prepared electrode material possess a suitable lithium-ion transport path, but it can also exhibit good electrolyte wetting properties. This facilitates the extraction of active lithium ions from the electrode material, improves the lithium replenishment efficiency of the electrode sheet, and thus helps to further delay the capacity decay of the secondary battery and extend its cycle life.

[0219] In some embodiments, in method A, the reactants may include at least one selected from air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, dinitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide, or red phosphorus. Optionally, the reactants may include at least one selected from carbon dioxide, fluorine, nitrogen, sulfur dioxide, or red phosphorus.

[0220] Reactants selected from the above categories can react with liquid-phase lithiating agents and / or pre-lithiated electrode active materials. By selecting suitable reactants, the composition of the first inorganic lithiide layer can be controlled. A suitable composition of the first inorganic lithiide layer helps to suppress side reactions between the substrate and air, maintaining high lithium replenishment efficiency of the electrode material. Furthermore, it helps to control the composition of the protective film on the electrode surface, thereby improving the stability of the electrode environment. This contributes to further improving the cycle stability of the secondary battery and extending its cycle life.

[0221] The contact between the reactants and the pre-lithiated electrode active material can be achieved in various ways, and this application does not limit this. In some embodiments, when the reactants are gases, they can be directly introduced into the slurry obtained in step S220. In some embodiments, when the reactants are solids, they 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 allows for more uniform and thorough contact between the reactants and the pre-lithiated electrode active material, thereby facilitating the smooth progress of the reaction. The organic solvents mentioned above may include at least one of alkanes, aromatic hydrocarbons, ethers, esters, and their halogenated derivatives, for example, 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%-20%.

[0222] In some embodiments, method A may further include: drying electrode material.

[0223] This application does not limit the drying atmosphere; the drying atmosphere can include any atmosphere that does not cause side reactions with the electrode material. In some embodiments, the drying atmosphere may include nitrogen, argon, dry air, or a combination thereof. Optionally, in some embodiments, the drying atmosphere may include nitrogen, argon, or a combination thereof. This application does not limit the drying temperature and time, which can be adjusted as needed by those skilled in the art. In some embodiments, the drying temperature can be 0℃-200℃, optionally 20℃-120℃, and the drying time can be 5min-6h. This can improve the stability of the chemical properties of the electrode material, thereby improving the stability of the chemical properties of the electrode sheet.

[0224] In some embodiments, step S240 may include the following steps (1)-(2).

[0225] (1) The electrode material, optional other electrode active materials, and optional additives are mixed evenly in an aprotic solvent to obtain an electrode slurry, wherein the other electrode active materials include other positive electrode active materials or other negative electrode active materials known in the art.

[0226] (2) The electrode paste is coated on at least one side of the current collector, and then dried and cold-pressed to obtain the electrode sheet.

[0227] In some embodiments, step S240 may include the following steps (3)-(4).

[0228] (3) The electrode material, optional other electrode active materials, and optional additives are mixed evenly to obtain electrode powder, wherein the other electrode active materials include other positive electrode active materials or other negative electrode active materials known in the art.

[0229] (4) The electrode powder is extruded and calendered into an electrode film, and the electrode film and the current collector are pressed together to obtain an electrode sheet.

[0230] Method B may include the following steps S310 to S340.

[0231] S310 provides an initial electrode, the initial electrode 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.

[0232] S320 involves mixing lithium metal with a complexing reagent solution to allow the lithium metal to react with the complexing reagent, thereby obtaining a liquid-phase lithiating agent.

[0233] In step S320, the lithium metal can be in any form, for example, it can include at least one of lithium blocks, lithium foil, and lithium powder, and is not limited herein. The complexing agent can include reagents known in the art that can undergo a complexing reaction with lithium metal, and those skilled in the art can select them as needed, and are not limited herein. In some embodiments, mixing the lithium metal with the complexing agent solution can include mixing the lithium metal with the complexing agent and stirring until homogeneous. The stirring temperature and time are not specifically limited and can be adjusted as needed by those skilled in the art. As an example, the stirring temperature can be 0℃-60℃, optionally 10℃-40℃, and the stirring time can be 0.1h-12h, optionally 1h-6h.

[0234] S330, a liquid-phase lithiating agent is brought into contact with an electrode film layer so that the liquid-phase lithiating agent pre-lithiates the electrode active material, resulting in an electrode sheet including the pre-lithiated electrode active material.

[0235] In step S330, the contact between the liquid-phase lithiating agent and the electrode film can be achieved in various ways, and this application does not limit this method. In some embodiments, the electrode film can be impregnated with the liquid-phase lithiating agent, or the liquid-phase lithiating agent can be coated on the surface of the electrode film to pre-lithiate the electrode active material in the electrode film. The coating method can be brush coating, curtain coating, roller coating, nitrogen spraying, air spraying, electrostatic spraying, electrophoretic spraying, high-pressure airless spraying, etc., and is 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℃-80℃, optionally 10℃-50℃, and the pre-lithiation time can be 1min-6h, optionally 5min-30min.

[0236] S340, an electrode sheet including a pre-lithiated electrode active material is brought into contact with a reactant to form a first inorganic lithium compound layer on at least a portion of the surface of the pre-lithiated electrode active material, thereby obtaining an electrode sheet including an electrode material; wherein the electrode material includes: a substrate, the substrate including the pre-lithiated electrode active material; and a first inorganic lithium compound layer covering 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.

[0237] In step S340, the reactant can be a substance capable of reacting with a liquid-phase lithiating agent or a pre-lithiated electrode active material to generate 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 appropriate substance as needed. In step S340, after the electrode sheet including the pre-lithiated electrode active material comes into contact with the reactant, the reactant can react with at least a portion of the liquid-phase lithiating agent remaining on the surface of the pre-lithiated electrode active material or the material on the surface layer of the pre-lithiated electrode active material to form a first inorganic lithium compound 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.

[0238] In some embodiments, the reactants may also react with the liquid-phase lithiating agent remaining on the surface of the electrode film to form a second inorganic lithiide layer on at least a portion of the surface of the electrode film. The embodiments for the second inorganic lithiide layer have been described in detail above and will not be repeated here. The reaction temperature and reaction time of step S340 are not specifically limited and can be adjusted as needed by those skilled in the art. As an example, the reaction temperature of step S340 can be 0℃-80℃, optionally 10℃-50℃, and the reaction time can be 1min-60min, optionally 2min-10min.

[0239] The electrode sheet prepared according to method B includes an electrode material. The substrate of the electrode material has pre-embedded 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 battery formation. Furthermore, the electrode material can form a dense, uniform, and stable protective film on the surface of the electrode sheet through a first inorganic lithium compound layer. This protective film can function similarly to an SEI film, thereby improving the environmental stability of the electrode, reducing irreversible loss of active lithium ions, and slowing down the capacity decay of the secondary battery. Therefore, the electrode sheet prepared according to the embodiments of this application, when applied to a secondary battery, can improve the energy density of the secondary battery and extend its cycle life.

[0240] It should be noted that the composition of the electrode film in the electrode sheet can be controlled by adjusting steps S310 to S340. For example, by adjusting the reaction materials and reaction conditions in step S330, pre-lithiation of a portion of the electrode active material or pre-lithiation of all the electrode active material can be performed. The degree of pre-lithiation of the electrode active material can also be controlled by adjusting the reaction materials and reaction conditions in step S330, thereby controlling the lithium replenishment content of the electrode sheet. For example, by adjusting the reaction materials and reaction conditions in step S340, a first inorganic lithium compound layer can be formed on the surface of a portion of the pre-lithiated electrode active material or on the surface of all the pre-lithiated electrode active material. For example, by adjusting the reaction materials and reaction conditions in steps S330 and S340, a second inorganic lithium compound layer can also be formed on at least a portion of the surface of the electrode sheet. Those skilled in the art will understand that regardless of the composition of the electrode film in the electrode sheet, as long as it contains the aforementioned electrode materials, it falls within the scope of this application.

[0241] In some embodiments, method B may further include: providing a complexing reagent solution, including mixing the complexing reagent with a solvent to obtain a complexing reagent solution.

[0242] In some embodiments, the coordinating 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. Optionally, in some embodiments, the coordinating agent may include at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, benzophenone, pyridine, and quinoline.

[0243] In some embodiments, the solvent may include at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ethers and their derivatives, furans and their derivatives, pyrans and their derivatives, and esters and their derivatives. Optionally, the solvent may include at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

[0244] Not intended to be limited to any particular theory or explanation, the complexing reagents selected from the above types can undergo complexation reactions with lithium metal to generate liquid-phase lithiating agents with lower redox potentials. Therefore, the liquid-phase lithiating agents more easily pre-lithiate the electrode active materials, embedding active lithium ions within them, thereby improving the lithium replenishment efficiency of the electrode. Furthermore, using the above-mentioned solvents to dissolve the complexing reagents allows for further adjustment of the redox potential of the liquid-phase lithiating agent within a suitable range, thereby further improving the pre-lithiation efficiency and ultimately enhancing the lithium replenishment efficiency of the electrode.

[0245] In some embodiments, in method B, the redox potential of the liquid-phase lithiating agent can be 0.05V-1.5V, for example, it can be 0.05V, 0.10V, 0.20V, 0.30V, 0.40V, 0.50V, 0.60V, 0.70V, 0.80V, 0.90V, 1.0V, 1.5V, or any range of two of the above values.

[0246] 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, etc.

[0247] When the redox potential of the liquid-phase lithiation agent is within the above-mentioned suitable range, the pre-lithiation efficiency can be further improved, thereby improving the lithium replenishment efficiency of the electrode sheet.

[0248] In some embodiments, in method B, the molar ratio of lithium metal to the complexing reagent can be (0.5:1)-(10:1), for example, it can be 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or any range of two of the above ratios. Optionally, the molar ratio of lithium metal to the complexing reagent 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), etc. In some embodiments, the lithium content in the liquid-phase lithiation agent can be 0.01 mol / L to 10 mol / L, for example, it can be 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 any range of two of the above values. Optionally, the lithium content in the liquid-phase lithiation agent can also be 0.01 mol / L to 5 mol / L, 0.01 mol / L to 4 mol / L, 0.01 mol / L to 3 mol / L, 0.01 mol / L to 2 mol / L, 0.01 mol / L to 1 mol / L, 0.5 mol / L to 5 mol / L, 0.5 mol / L to 3 mol / L, 0.5 mol / L to 1 mol / L, 1 mol / L to 5 mol / L, 2 mol / L to 4 mol / L, etc.

[0249] This is not intended to be limited by any theory or explanation. When the molar ratio of lithium metal to the complexing reagent is within the above range, it not only helps to improve the reaction efficiency of lithium metal and the complexing reagent, but also helps to adjust the lithium content in the liquid-phase lithiation agent to a suitable range. In the liquid-phase lithiation agent, a suitable lithium content can improve the pre-lithiation efficiency of the liquid-phase lithiation agent on the electrode active material, thereby improving the lithium replenishment efficiency of the electrode sheet.

[0250] In some embodiments, in method B, the molar ratio of lithium element to electrode active material in liquid phase lithiation agent can be (0.05:1)-(10:1), and can be selected as (0.1:1)-(5:1).

[0251] Not intended to be limited by any theory or explanation, when the molar ratio of lithium to electrode active material in the liquid-phase lithiating agent is within the aforementioned suitable range, an appropriate amount of active lithium ions can be embedded in the electrode active material. Therefore, during battery formation, the electrode material can release an appropriate amount of active lithium ions to replenish the active lithium ions lost during the first charge-discharge cycle.

[0252] In some embodiments, in method B, 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, etc.

[0253] Not intended to be limited by any theory or explanation, when the volume distribution particle size Dv50 of the electrode active material is within the aforementioned suitable range, not only can the prepared electrode material possess a suitable lithium-ion transport path, but it can also exhibit good electrolyte wetting properties. This facilitates the extraction of active lithium ions from the electrode material, improves the lithium replenishment efficiency of the electrode sheet, and thus helps to further delay the capacity decay of the secondary battery and extend its cycle life.

[0254] In some embodiments, in method B, the reactants may include at least one of air, water, oxygen, carbon dioxide, nitrogen, nitric oxide, nitrogen dioxide, dinitrogen pentoxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide, or red phosphorus. Optionally, the reactants may include at least one of carbon dioxide, fluorine, nitrogen, sulfur dioxide, or red phosphorus.

[0255] The reactants selected from the above categories can react with the pre-lithiated electrode active material. By selecting suitable reactants, the composition of the first inorganic lithiide layer can be controlled. A suitable composition of the first inorganic lithiide layer helps to suppress side reactions between the substrate and air, maintaining high lithium replenishment efficiency of the electrode sheet. Furthermore, it helps to control the composition of the protective film on the electrode surface, thereby improving the stability of the electrode environment. This contributes to further improving the cycle stability of the secondary battery and extending its cycle life.

[0256] The contact between the reactants and the electrode, including the pre-lithiated electrode active material, can be achieved in various ways, and this application does not limit the specific methods. In some embodiments, when the reactants are gases, the electrode surface is directly purged with the reactant gas. In some embodiments, when the reactants are solids, they can be dissolved in an organic solvent to obtain a reactant solution, which is then coated onto the electrode surface. The coating method can be brush coating, curtain coating, roller coating, nitrogen spraying, air spraying, electrostatic spraying, electrophoretic spraying, high-pressure airless spraying, etc., and is not limited here. This allows the reactants to contact the electrode surface more uniformly and fully, thereby facilitating the smooth progress of the reaction. When the reactants contact the electrode in the form of a reactant solution, the reactant solution can also penetrate into the pores of the electrode film layer and react with the pre-lithiated electrode active material inside the electrode film layer, thereby further improving the reaction efficiency. The aforementioned organic solvent may include at least one of alkanes, aromatic hydrocarbons, ethers, esters, and their halogenated derivatives, 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. The mass fraction of the reactants in the reactant solution may be 0.1%-20%.

[0257] In some embodiments, method B may further include: drying the electrode plates.

[0258] This application does not limit the drying atmosphere; the drying atmosphere can include any atmosphere that does not cause side reactions with the electrode sheet. In some embodiments, the drying atmosphere may include nitrogen, argon, dry air, or a combination thereof. Optionally, in some embodiments, the drying atmosphere may include nitrogen, argon, or a combination thereof. This application does not limit the drying temperature and time, which can be adjusted as needed by those skilled in the art. In some embodiments, the drying temperature can be 0℃-200℃, optionally 20℃-120℃, and the drying time can be 5 min-6 h. This can improve the stability of the chemical properties of the electrode sheet.

[0259] Battery

[0260] Fifthly, embodiments of this application provide a battery. The battery mentioned in the embodiments of this application may include one or more battery cells as a single physical module to provide higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or mixed via a busbar.

[0261] The battery cell can be a secondary battery, also known as a rechargeable battery or accumulator, which refers to a battery cell that can be recharged after discharge to activate the active materials and continue to be used. This application does not impose any particular limitation on the type of secondary battery; for example, it can be a lithium-ion battery, a lithium metal battery, etc., and specifically, a lithium-ion battery.

[0262] Typically, a battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The separator is placed between the positive and negative electrodes, primarily to prevent short circuits between the positive and negative electrodes, while also allowing active ions to pass through.

[0263] The battery cell of this application embodiment 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 sheet of the third aspect, or the electrode sheet prepared according to the preparation method of the fourth aspect.

[0264] [Positive electrode plate]

[0265] In the battery cell of this application, the positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and comprising a positive electrode active material. For example, the positive current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0266] In some embodiments, the positive electrode 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 is understood that the battery of this application can achieve the beneficial effects of any of the above embodiments of the electrode material of this application.

[0267] In some embodiments, the positive electrode includes an electrode material prepared according to the method of the second aspect, wherein the electrode material is a positive electrode material. The embodiments of the electrode material preparation method have been described and illustrated above, and will not be repeated here. It is understood that the battery of this application can achieve the beneficial effects of any of the above embodiments of the electrode material preparation method of this application.

[0268] In some embodiments, the positive electrode includes an electrode from the third aspect. The embodiments of the electrode have been described and illustrated in detail above, and will not be repeated here. It is understood that the battery of this application can achieve the beneficial effects of any of the above embodiments of the electrode of this application.

[0269] In some embodiments, the positive electrode includes an electrode sheet prepared according to the preparation method of the fourth aspect. The embodiments of the electrode sheet preparation method have been described and illustrated above, and will not be repeated here. It is understood that the battery of this application can achieve the beneficial effects of any of the above embodiments of the electrode sheet preparation method of this application.

[0270] In some embodiments, the positive 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 substrate and a metal layer formed on at least one surface of the polymer substrate. 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 substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0271] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0272] In some embodiments, the positive electrode film may optionally include a conductive agent and an optional dispersant. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0273] [Negative electrode plate]

[0274] In the battery cell of this application, the negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector and comprising a negative electrode active material. For example, the negative current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0275] In some embodiments, the negative electrode sheet 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 is understood that the battery of this application can achieve the beneficial effects of any of the above embodiments of the electrode material of this application.

[0276] In some embodiments, the negative electrode sheet includes an electrode material prepared according to the method of the second aspect, wherein 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 is understood that the battery of this application can achieve the beneficial effects of any of the above embodiments of the electrode material preparation method of this application.

[0277] In some embodiments, the negative electrode includes an electrode from the third aspect. The embodiments of the electrode have been described and illustrated in detail above, and will not be repeated here. It is understood that the battery of this application can achieve the beneficial effects of any of the above embodiments of the electrode of this application.

[0278] In some embodiments, the negative electrode includes an electrode sheet prepared according to the preparation method of the fourth aspect. The embodiments of the electrode sheet preparation method have been described and illustrated above, and will not be repeated here. It is understood that the battery of this application can achieve the beneficial effects of any of the above embodiments of the electrode sheet preparation method of this application.

[0279] 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 material substrate and a metal layer formed on at least one surface of the polymer material substrate. 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 material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0280] In some embodiments, the negative electrode film layer may optionally 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).

[0281] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0282] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0283] Furthermore, the negative electrode sheet of this application does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet of this application may also include a conductive undercoat 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 sheet of this application also includes a protective layer covering the surface of the negative electrode film layer.

[0284] [Isolation membrane]

[0285] The separator is positioned between the positive and negative electrodes to provide isolation. This application does not impose any particular restrictions on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0286] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven 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.

[0287] [Electrolytes]

[0288] Generally, a battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or entirely solid-state.

[0289] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0290] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0291] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0292] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0293] In some embodiments, the casing of the battery cell can be a rigid casing, such as a hard plastic casing, an aluminum casing, or a steel casing. The casing of the battery cell can also be a pouch, such as a pouch-type pouch. The material of the pouch can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0294] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 The example shown is a square-structured battery cell 5.

[0295] In some implementations, refer to Figure 2 The outer casing may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can cover the opening to close the receiving cavity. A positive electrode sheet, a negative electrode sheet, and a separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0296] The method for preparing the battery cell of this application is well known. In some embodiments, the electrode assembly can be placed in a housing, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, the battery cell is obtained.

[0297] In some embodiments, the battery mentioned in this application may be a battery module or a battery pack. A battery module or battery pack generally includes a housing for encapsulating one or more individual battery cells. The housing can prevent liquids or other foreign matter from affecting the charging or discharging of the individual battery cells.

[0298] In some implementations, a battery module or battery pack may contain multiple battery cells, which can be connected in series, parallel, or a combination thereof. A combination thereof means that multiple battery cells are connected in both series and parallel configurations. Multiple battery cells can be directly connected in series, parallel, or a combination thereof, and then the entire assembly of these battery cells is housed within a housing. Alternatively, multiple battery cells can first be connected in series, parallel, or a combination thereof to form a battery module, and then these battery modules can be connected in series, parallel, or a combination thereof to form a whole, which is then housed within a housing.

[0299] Figure 3 This is a schematic diagram of battery module 4 as an example. Figure 3 As shown, there are multiple battery cells 5, which are connected in series, parallel, or a combination thereof to form a battery module 4. The multiple battery cells 5 in the battery module 4 can be electrically connected through a busbar to achieve the series, parallel, or combination connection. 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 arbitrary manner. Furthermore, the multiple battery cells 5 can be fixed in place using fasteners.

[0300] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0301] Figure 4 and Figure 5 This is a schematic diagram of battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The multiple battery modules 4 in the battery pack 1 can be electrically connected via a busbar component to achieve series, parallel, or mixed connection. The housing includes an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery housing.

[0302] Electrical appliances

[0303] This application also provides an electrical device, which includes the battery provided in this application, and the battery is used to provide electrical energy. The battery can be used as a power source for the electrical device, or it can be used as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0304] As the electrical device, a single battery cell, a battery module containing multiple battery cells, or a battery pack can be selected according to its usage requirements.

[0305] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0306] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0307] Example

[0308] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0309] Example 1

[0310] Preparation of electrode material

[0311] Step a: Dissolve 1 mol of the complexing reagent 2-methylbiphenyl in 1 L of the solvent tetrahydrofuran, then add 1 mol of lithium flakes, stir at room temperature (25 °C) for 4 h to obtain a liquid-phase lithium-[2-methylbiphenyl]-tetrahydrofuran with a concentration of 1 mol / L.

[0312] Step b: Measure the volumetric particle size Dv 1 50 is 10μm electrode active material silicon suboxide added to the liquid phase lithiation agent obtained in step a, and stirred under the first reaction conditions to obtain a lithiation electrode slurry. The molar ratio M of lithium element in the liquid phase lithiation agent to electrode active material is 5. The first reaction conditions are: reaction temperature 25℃ and reaction time 6h.

[0313] Step c: The reactants (a mixture of 2% HF, 2% CO2, 20% O2 and 76% N2) are introduced into the lithium electrode slurry at a flow rate of 0.5 L / min, and the reaction continues under the second reaction conditions: reaction temperature 25℃ and reaction time 10 min.

[0314] Step d: The slurry from step c is filtered under reduced pressure and dried at 120°C under normal pressure for 1 hour to obtain the electrode material. This electrode material comprises a substrate (pre-lithiated silicon suboxide) and a first inorganic lithium oxide layer coated on the surface of the substrate. The volume distribution Dv of the electrode material is... 2 The thickness d of the first inorganic lithium-ion layer is 1 μm, and the first inorganic lithium-ion layer comprises 40% Li₂O, 30% Li₃N, 2% Li₂CO₃, and 28% LiF by mass percentage. The lithium content of the electrode material was determined using the method described in this application specification, and the measured value was 50%.

[0315] Preparation of positive electrode sheet

[0316] The positive electrode active material LiFePO4, conductive agent carbon black and binder PVDF are mixed in a ratio of 84:8:8, NMP solvent is added, and the mixture is stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is coated on carbon-coated aluminum foil, and then dried, cold-pressed and slit to obtain a positive electrode sheet.

[0317] Preparation of negative electrode sheet

[0318] Artificial graphite (anode active material), electrode material, carbon black (conductive agent), SBR (binder), and CMC-Na (thickener) are mixed in a mass ratio of 87:10:0.5:1.25:1.25. NMP (solvent) is added, and the mixture is stirred until homogeneous to obtain a cathode slurry. The cathode slurry is coated onto copper foil, dried, cold-pressed, and slit to obtain a cathode sheet.

[0319] Separator film

[0320] Polypropylene film is used as the separator.

[0321] Preparation of electrolyte

[0322] LiPF6 was dissolved in a solvent prepared by mixing ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate in a volume ratio of 1:1:1 to obtain an electrolyte with a LiPF6 concentration of 1 mol / L.

[0323] Preparation of secondary battery

[0324] The positive electrode, separator, and negative electrode are stacked in sequence to obtain the electrode assembly. The electrode assembly is placed in a packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a secondary battery is obtained.

[0325] Example 2-15

[0326] Based on the electrode material preparation process in Example 1, and according to Table 1, the electrode material preparation parameters were adjusted to prepare the electrode materials for Examples 2-15. The preparation of the positive electrode, negative electrode, separator, electrolyte, and secondary battery in Examples 2-15 was the same as in Example 1.

[0327] Example 16

[0328] Preparation of electrode material

[0329] Step a: Dissolve 0.05 mol of the complexing reagent naphthalene in 1 L of solvent 2-methylfuran, then add 0.05 mol of lithium flakes, stir at room temperature (25 °C) for 4 h to obtain a liquid-phase lithium-naphthalene-[2-methylfuran] with a concentration of 0.05 mol / L.

[0330] Step b: Measure the volumetric particle size Dv 1 50 LiFePO4, an electrode active material with a thickness of 10 μm, is added to the liquid-phase lithiation agent obtained in step a and stirred under the first reaction conditions to obtain a lithiated electrode slurry. The molar ratio M of lithium element in the liquid-phase lithiation agent to the electrode active material is 1. The first reaction conditions are: reaction temperature 25℃ and reaction time 5 min.

[0331] Step c: The reactants (a mixture of 80% O2 and 20% N2) are introduced into the lithium electrode slurry at a flow rate of 0.1 L / min, and the reaction continues under the second reaction conditions: reaction temperature 25℃ and reaction time 2 min.

[0332] Step d: The slurry from step c is filtered under reduced pressure and dried at 120°C under normal pressure for 1 hour to obtain the electrode material. This electrode material comprises a substrate (pre-lithiated LiFePO4) and a first inorganic lithium compound layer coated on the surface of the substrate. The volume distribution Dv of the electrode material is... 2 The thickness d of the first inorganic lithium-ion layer is 80 nm, and the first inorganic lithium-ion layer comprises 30% Li₂O and 70% Li₃N by mass. The lithium content of the electrode material was determined using the method described in this application specification, and the measured value was 30%.

[0333] Preparation of positive electrode sheet

[0334] 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 the mixture is stirred evenly to obtain positive electrode slurry; the positive electrode slurry is coated on carbon-coated aluminum foil, and then dried, cold-pressed and slit to obtain positive electrode sheet.

[0335] Preparation of negative electrode sheet

[0336] Artificial graphite (anode active material), silicon suboxide (anode active material), carbon black (conductive agent), SBR (binder), and CMC-Na (thickener) are mixed in a mass ratio of 67:30:0.5:1.25:1.25. NMP solvent is added and the mixture is stirred evenly to obtain anode slurry. The anode slurry is coated on copper foil, dried, cold-pressed, and slit to obtain anode sheets.

[0337] Separator film

[0338] Polypropylene film is used as the separator.

[0339] Preparation of electrolyte

[0340] LiPF6 was dissolved in a solvent prepared by mixing ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate in a volume ratio of 1:1:1 to obtain an electrolyte with a LiPF6 concentration of 1 mol / L.

[0341] Preparation of secondary battery

[0342] The positive electrode, separator, and negative electrode are stacked in sequence to obtain the electrode assembly. The electrode assembly is placed in a packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a secondary battery is obtained.

[0343] Examples 17-18

[0344] Based on the electrode material preparation process in Example 16, and according to Table 2, the electrode material preparation parameters were adjusted to prepare the electrode materials for Examples 17-18. The preparation of the positive electrode, negative electrode, separator, electrolyte, and secondary battery in Examples 17-18 was the same as in Example 16.

[0345] Example 19

[0346] Preparation of negative electrode sheet

[0347] The negative electrode active material (a mixture of artificial graphite and silicon suboxide in a mass ratio of 95:5), conductive agent carbon black, binder SBR, and thickener CMC-Na are mixed in a mass ratio of 97:0.5:1.25:1.25. NMP solvent is added and the mixture is stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is coated on copper foil, dried, cold-pressed, and slit to obtain the initial negative electrode sheet.

[0348] 1 mol of the complexing reagent 2-methylbiphenyl was dissolved in 1 L of the solvent tetrahydrofuran, and then 1 mol of lithium was added. The mixture was stirred at room temperature (25 °C) for 4 h to obtain a 1 mol / L liquid-phase lithium-[2-methylbiphenyl]-tetrahydrofuran.

[0349] The initial negative electrode sheet is immersed in a liquid-phase lithiation agent, and the liquid-phase lithiation agent reacts with the negative electrode active material under the first reaction conditions to obtain an electrode sheet including the pre-lithiated negative electrode active material. The molar ratio M of lithium in the liquid-phase lithiation 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℃ and reaction time 20 min.

[0350] An electrode sheet comprising a pre-lithiated negative electrode active material was placed in a reactant gas stream, and reactants (a mixture of 25% H2S and 75% N2) were continuously introduced at a flow rate of 0.22 L / min. The reaction continued under the second reaction conditions: a reaction temperature of 25°C and a reaction time of 10 min. Subsequently, it was dried at 120°C and atmospheric pressure for 1 h to obtain the negative electrode sheet. This negative electrode sheet comprises an electrode material, which includes a substrate and a first inorganic lithium-ion layer coated on the surface of the substrate. The thickness d of the first inorganic lithium-ion layer is 800 nm, and the first inorganic lithium-ion layer comprises 10% Li2S and 90% Li3N by mass. The lithium content of the negative electrode sheet was determined to be 50% by the method described in this application.

[0351] The preparation process of the positive electrode, separator, electrolyte and secondary battery in Example 19 is the same as that in Example 1.

[0352] Examples 20-32

[0353] Based on the preparation process of the negative electrode sheet in Example 19, and according to Table 3, the preparation parameters of the negative electrode sheet were adjusted to prepare the negative electrode sheets of Examples 20-32. The preparation of the positive electrode sheet, separator, electrolyte, and secondary battery in Examples 20-32 was the same as in Example 19.

[0354] Example 33

[0355] Preparation of positive electrode sheet

[0356] The positive electrode active material LiFePO4, conductive agent carbon black and binder PVDF are mixed in a ratio of 84:8:8, and solvent NMP is added. The mixture is stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is coated on carbon-coated aluminum foil, and after drying, cold pressing and slitting, the initial positive electrode sheet is obtained.

[0357] 0.05 mol of the complexing reagent naphthalene was dissolved in 1 L of solvent 2-methylfuran, and then 0.05 mol of lithium flakes were added. The mixture was stirred at room temperature (25 °C) for 4 h to obtain a 0.05 mol / L liquid-phase lithium-naphthalene-[2-methylfuran].

[0358] The initial positive electrode sheet is immersed in a liquid-phase lithiation agent, and the liquid-phase lithiation agent reacts with the positive electrode active material under the first reaction conditions to obtain an electrode sheet including pre-lithiated positive electrode active material. The molar ratio M of lithium in the liquid-phase lithiation agent to the positive electrode active material in the initial positive electrode sheet is 1, and the first reaction conditions are: reaction temperature 25℃ and reaction time 15min.

[0359] An electrode sheet comprising a pre-lithiated positive electrode active material was placed in a reactant gas stream, and reactants (a mixture of 80% O2 and 20% N2) were continuously introduced at a flow rate of 1 L / min. The reaction continued under the second reaction conditions: a reaction temperature of 25°C and a reaction time of 10 min. Subsequently, it was dried at 120°C and atmospheric pressure for 1 h to obtain the positive electrode sheet. This positive electrode sheet comprises an electrode material, which includes a substrate (pre-lithiated LiFePO4) and a first inorganic lithium-ion layer coated on the surface of the substrate. The thickness d of the first inorganic lithium-ion layer is 100 nm, and the first inorganic lithium-ion layer comprises 30% Li2O and 70% Li3N by mass percentage. The lithium content of the positive electrode sheet was determined to be 30% by the method described in this application.

[0360] The preparation of the negative electrode, separator, electrolyte, and secondary battery in Example 33 is the same as in Example 16.

[0361] Examples 34-35

[0362] Based on the preparation process of the positive electrode sheet in Example 33, and according to Table 4, the preparation parameters of the positive electrode sheet were adjusted to prepare the positive electrode sheets of Examples 34-35. The preparation of the negative electrode sheet, separator, electrolyte, and secondary battery in Examples 34-35 was the same as in Example 33.

[0363] Comparative Examples 1-3

[0364] The preparation process of the positive electrode, negative electrode, separator, electrolyte and secondary battery of Comparative Examples 1-3 is the same as that of Example 1, except that the electrode materials are replaced with electrode active materials of equal mass, as detailed in Table 1.

[0365] Comparative Example 4

[0366] Based on the electrode material preparation process in Example 1, and according to Table 1, the electrode material preparation parameters were adjusted to prepare the electrode material for Comparative Example 4. The preparation of the positive electrode, negative electrode, separator, electrolyte, and secondary battery in Comparative Example 4 was the same as in Example 1.

[0367] Comparative Example 5

[0368] The preparation process of the positive electrode, negative electrode, separator, electrolyte and secondary battery of Comparative Example 5 is the same as that of Example 16, except that the electrode materials are replaced with electrode active materials of equal mass, as detailed in Table 2.

[0369] Comparative Example 6

[0370] Based on the electrode material preparation process in Example 16, and according to Table 2, the electrode material preparation parameters were adjusted to prepare the electrode material of Comparative Example 6. The preparation of the positive electrode, negative electrode, separator, electrolyte, and secondary battery of Comparative Example 6 was the same as that in Example 16.

[0371] Comparative Example 7

[0372] The preparation process of the positive electrode, separator, electrolyte and secondary battery of Comparative Example 7 is the same as that of Example 19, except that the negative electrode is replaced with the original negative electrode to prepare the secondary battery of Comparative Example 7.

[0373] Comparative Example 8

[0374] Based on the preparation process of the negative electrode sheet in Example 19, the preparation parameters of the negative electrode sheet were adjusted according to 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.

[0375] Comparative Example 9

[0376] The preparation process of the negative electrode, separator, electrolyte and secondary battery of Comparative Example 9 is the same as that of Example 33, except that the positive electrode is replaced with the original positive electrode to prepare the secondary battery of Comparative Example 9.

[0377] Comparative Example 10

[0378] Based on the preparation process of the positive electrode in Example 33, the preparation parameters of the positive electrode were adjusted according to Table 4 to prepare the positive electrode of Comparative Example 10. The preparation of the negative electrode, separator, electrolyte, and secondary battery of Comparative Example 10 was the same as that of Example 33.

[0379] 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.

[0380] Characterization of materials

[0381] (1)Dv 1 The characterization of 50

[0382] Referring to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method, the volume distribution particle size Dv of the electrode active material was determined using a laser particle size analyzer (MalvemMaster Size 3000). 1 50.

[0383] (2)Dv 2 The characterization of 50

[0384] Referring to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method, the volume distribution particle size Dv of the electrode material was determined using a laser particle size analyzer (MalvernMaster Size 3000). 2 50.

[0385] (3) Characterization of the thickness d of the first inorganic lithium compound layer

[0386] Examples 1-18: The prepared electrode material was dispersed in ethanol solvent and dropped onto a microgrid support film. The thickness d of the first inorganic lithium compound layer in the electrode material was measured by high-resolution transmission electron microscopy (magnification of 10,000-300,000 times).

[0387] Examples 19-32: Take the prepared negative electrode sheet; randomly select an area, perform argon ion cross-section polishing treatment, and take transmission electron microscope (TEM) images at a magnification of 30,000; process the TEM images, adjust the appropriate contrast, and measure the thickness d of the first inorganic lithium oxide layer.

[0388] Examples 33-35: Take the prepared positive electrode sheet; randomly select an area, perform argon ion cross-section polishing treatment, and take transmission electron microscope (TEM) images at a magnification of 10000x; process the TEM images, adjust the appropriate contrast, and measure the thickness d of the first inorganic lithium oxide layer.

[0389] (4) Characterization of the composition of the first inorganic lithium compound layer

[0390] Examples 1-18: The types and contents of elements on the surface of the electrode material were determined by X-ray photoelectron spectroscopy (XPS). The composition of the first inorganic lithium compound layer was determined based on the content ratio of each element and the chemical formula of the inorganic lithium compound.

[0391] Examples 19-32: Take the prepared negative electrode sheet, randomly select a region as a cross-section, and determine the position of the first inorganic lithium compound layer by scanning electron microscopy (SEM) at 10,000x magnification. Mark the position of the first inorganic lithium compound layer in the field of view as the target area; then select a 10μm*10μm region at 1000x magnification for EDS surface scanning for 2 min to obtain the element types and contents of the target area. Based on the content ratio of each element and the chemical formula of the inorganic lithium compound, determine the composition of the first inorganic lithium compound layer.

[0392] Examples 33-35: Take the prepared positive electrode sheet, randomly select a region as a cross-section, and determine the position of the first inorganic lithium compound layer by scanning electron microscopy (SEM) at 10,000x magnification. Mark the position of the first inorganic lithium compound layer in the field of view as the target area. Then, select a 10μm*10μm region at 1000x magnification and perform EDS surface scanning for 2 min to obtain the element types and contents of the target area. Based on the content ratio of each element and the chemical formula of the inorganic lithium compound, determine the composition of the first inorganic lithium compound layer.

[0393] Battery performance test

[0394] (1) First week Coulomb efficiency test

[0395] At 25°C, the secondary battery was charged at a constant current of 0.1C to 3.65V, then charged at a constant voltage until the current was less than or equal to 0.05C. After resting for 5 minutes, the initial charge capacity was recorded as C0 (mAh / g). Then, it was discharged at a constant current of 0.2C to 2.5V, and the initial discharge capacity was recorded as D0 (mAh / g). The first-week coulombic efficiency = D0 / C0 × 100%.

[0396] (2) Room temperature cycling performance test

[0397] 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. After resting for 5 minutes, it was 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 battery's discharge capacity C after the 300th cycle. 300 Calculate the battery capacity retention rate P. 300 (%) = C 300 / C 初始 ×100%.

[0398] (3) Discharge capacity test

[0399] 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 to rest for 5 minutes, and then discharged at 0.5C to 2.5V. The above steps were repeated for the same battery, and the discharge capacity C of the battery was recorded after the 100th cycle. 100 Calculate the battery's discharge capacity = C 100 / (mass of positive electrode active material + mass of electrode material).

[0400]

[0401]

[0402]

[0403]

[0404]

[0405]

[0406]

[0407] In Tables 1 to 4, the percentage of gaseous components in the reactants refers to the volume percentage of that component in the mixed gas. For example, "25% H2S + 75% N2" means that H2S and N2 are mixed in a volume ratio of 25:75 to form a gas. The percentage of 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" means that in a mixed solution of S and P using THF as the solvent, the mass percentage concentration of S is 5% and the mass percentage concentration of P is 5%.

[0408] As can be seen from Tables 1 to 4 above, the electrode materials and electrode sheets provided in the embodiments of this application, when applied to secondary batteries, can effectively compensate for the loss of active lithium ions in secondary batteries, thereby improving the cycle performance of the batteries.

[0409] As can be seen from Examples 1-7, adjusting the composition of the first inorganic lithiide layer can control the lithium replenishment efficiency of the electrode material, thereby regulating the battery's cycle performance. As can be seen from Examples 3 and 8-10, under the same conditions, increasing the lithium replenishment content of the electrode material improves both the first-cycle coulombic efficiency and cycle performance. As can be seen from Examples 3 and 11-13, under unchanged conditions, adjusting the thickness of the first inorganic lithiide layer within a suitable range can improve both the lithium replenishment efficiency of the electrode material and the battery's cycle performance.

[0410] In contrast, Comparative Example 1, which replaced the electrode material with an equal mass of silicon suboxide, showed lower first-cycle coulombic efficiency and cycle performance compared to Examples 1-13. Comparative Examples 2 and 3, which replaced the electrode material with equal masses of tin and phosphorus, also showed lower first-cycle coulombic efficiency and cycle performance compared to their counterparts in Examples 14 and 15. Although Comparative Example 4 used pre-lithiated silicon suboxide, it did not coat the surface of the pre-lithiated silicon suboxide with a first inorganic lithide layer. Consequently, the lithium replenishment efficiency of the pre-lithiated silicon suboxide was reduced, and the cycle performance of the battery was also unsatisfactory.

[0411] Based on the test results of Examples 16-18 in Table 2, it can be seen 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 in the secondary battery. Therefore, the secondary battery can still maintain a high discharge capacity after 100 charge-discharge cycles.

[0412] In contrast, Comparative Example 5, which replaced the electrode material with an equal mass of LiFePO4, showed significantly lower discharge capacity and cycle performance compared to Examples 16-18. Although Comparative Example 6 used pre-lithiated LiFePO4, it did not coat the surface of the pre-lithiated LiFePO4 with a first inorganic lithiation layer. Consequently, the lithium replenishment efficiency of the pre-lithiated LiFePO4 was reduced, resulting in Comparative Example 6 having lower discharge capacity and cycle performance than Examples 16-18 compared to Example 17.

[0413] The test results in Table 3 show that pre-lithiation of the negative electrode active material in the negative electrode sheet and treatment of the negative electrode sheet with reactants to make the negative electrode sheet contain electrode material can effectively improve the first-cycle coulombic efficiency and cycle performance of the battery.

[0414] In contrast, the negative electrode of Comparative Example 7 was not pre-lithiated, and the battery's first-cycle coulombic efficiency and cycle performance were significantly lower than those of Examples 19-32. Although Comparative Example 8 used pre-lithiated treatment on the negative electrode active material in the negative electrode sheet, a first inorganic lithium oxide layer was not 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.

[0415] The test results in Table 4 show that pre-lithiation of the positive electrode active material and treatment of the positive electrode with reactants, so that the positive electrode contains electrode material, can effectively replenish the active lithium ions lost in the secondary battery. Therefore, the secondary battery can still maintain a high discharge capacity after 100 charge-discharge cycles.

[0416] In contrast, the positive electrode of Comparative Example 9, which was not pre-lithiated, had a discharge capacity and cycle performance far lower than those of Examples 33-35 after 100 charge-discharge cycles. Although Comparative Example 10 pre-lithiated the positive active material in its positive electrode, a first inorganic lithium oxide layer was not formed on the surface of the pre-lithiated positive active material. As a result, its discharge capacity and cycle performance after 100 charge-discharge cycles were lower than those of Example 33.

[0417] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. An electrode material, characterized in that, include: Substrate, the substrate comprising a pre-lithiated electrode active material; as well as The first inorganic lithium compound layer, which covers at least a portion of the surface of the substrate, comprises, based on the total mass of the first inorganic lithium compound layer, 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

2. The electrode material according to claim 1, characterized in that, Based on the total mass of the first inorganic lithium compound layer, the first inorganic lithium compound layer comprises 70%-90% lithium nitride, 0-30% lithium oxide, and 0-10% lithium sulfide.

3. The electrode material according to claim 1 or 2, characterized in that, The thickness of the first inorganic lithium oxide layer is 2nm-5000nm.

4. The electrode material according to claim 3, characterized in that, The thickness of the first inorganic lithium oxide layer is 20nm-1000nm.

5. The electrode material according to any one of claims 1-4, characterized in that, The volumetric particle size distribution (Dv50) of the electrode material is 0.6 μm-60 μm.

6. The electrode material according to claim 5, characterized in that, The volumetric particle size Dv50 of the electrode material is 5μm-15μm.

7. The electrode material according to any one of claims 1-6, characterized in that, The electrode material is a positive electrode material, and the lithium content of the positive electrode material is 1%-30%. The lithium content of the cathode material is determined by (C1-C) 10 ) / C 10 ×100% characterization, where C1 is the actual specific capacity of the cathode material, in mAh / g, C 10 This represents the theoretical specific capacity of the positive electrode active material, expressed in mAh / g.

8. The electrode material according to claim 7, characterized in that, The lithium content of the cathode material is 5%-20%.

9. The electrode material according to any one of claims 1-8, characterized in that, The electrode material is a negative electrode material, and the lithium content of the negative electrode material is 1%-100%. The lithium content of the negative electrode material is determined by (C) 20 -C2) / C 20 ×100% characterization, where C2 is the actual specific capacity of the negative electrode material, in mAh / g, C 20 This represents the theoretical specific capacity of the negative electrode active material, expressed in mAh / g.

10. The electrode material according to claim 9, characterized in that, The electrode material is a negative electrode material, and the lithium content of the negative electrode material is 30%-50%.

11. A method for preparing an electrode material, characterized in that, include: Lithium metal is mixed with a complexing reagent solution to allow the lithium metal to react with the complexing reagent, thereby obtaining a liquid-phase lithiating agent; The liquid-phase lithiating agent is brought into contact with the electrode active material to pre-lithiate the electrode active material, thereby obtaining a pre-lithiated electrode active material. The pre-lithiated electrode active material is contacted with reactants to form a first inorganic lithium compound layer on at least a portion of the surface of the pre-lithiated electrode active material, thereby obtaining an electrode material. The electrode material comprises: a substrate, the substrate including the pre-lithiated electrode active material; and a first inorganic lithium compound layer covering at least a portion of the surface of the substrate, wherein, based on the total mass of the first inorganic lithium compound layer, the first inorganic lithium compound layer comprises 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

12. The preparation method according to claim 11, characterized in that, The preparation method further includes: Providing the complexing reagent solution includes mixing the complexing reagent with a solvent to obtain the complexing reagent solution.

13. The preparation method according to claim 12, characterized in that, The coordinating 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.

14. The preparation method according to claim 12, characterized in that, The coordinating agent includes at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, or benzophenone.

15. The preparation method according to claim 12, characterized in that, The solvent includes at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ethers and their derivatives, furans and their derivatives, pyrans and their derivatives, or esters and their derivatives.

16. The preparation method according to claim 12, characterized in that, The solvent 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 any one of claims 11-16, characterized in that, The redox potential of the liquid-phase lithiating agent is 0.05V-1.5V.

18. The preparation method according to claim 17, characterized in that, The redox potential of the liquid-phase lithiation agent is 0.1V-0.5V.

19. The preparation method according to any one of claims 11-18, characterized in that, The molar ratio of lithium metal to the complexing agent is (0.5:1)-(10:1); And / or, the molar concentration of lithium in the liquid-phase lithiation agent is 0.01 mol / L to 10 mol / L; And / or, the molar ratio of lithium element to electrode active material in the liquid phase lithiation agent is (0.05:1)-(10:1); And / or, the volume distribution particle size Dv50 of the electrode active material is 0.5μm-40μm.

20. The preparation method according to claim 19, characterized in that, The molar ratio of lithium metal to the complexing reagent is (1:1)-(4:1); And / or, the molar concentration of lithium in the liquid-phase lithiation agent is 0.01 mol / L to 5 mol / L; And / or, the molar ratio of lithium element to electrode active material in the liquid phase lithiation agent is (0.1:1)-(5:1).

21. The preparation method according to any one of claims 11-20, characterized in that, The reactants include at least one of nitrogen, nitric oxide, nitrogen dioxide, and dinitrogen pentoxide, and at least one of air, water, oxygen, carbon dioxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide, or red phosphorus.

22. An electrode sheet, characterized in that, It includes 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 includes: Substrate, said substrate comprising a pre-lithiated electrode active material; and The first inorganic lithium compound layer, which covers at least a portion of the surface of the substrate, comprises, based on the total mass of the first inorganic lithium compound layer, 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

23. The electrode sheet according to claim 22, characterized in that, The electrode sheet further includes a second inorganic lithium compound layer attached to at least a portion of the surface of the electrode film layer, wherein the second inorganic lithium compound layer includes at least one of lithium oxide, lithium nitride, lithium carbonate, lithium fluoride, lithium sulfide, or lithium phosphide.

24. The electrode sheet according to claim 22 or 23, characterized in that, Based on the total mass of the first inorganic lithium compound layer, the first inorganic lithium compound layer comprises 70%-90% lithium nitride, 0-30% lithium oxide, and 0-10% lithium sulfide.

25. A method for preparing an electrode sheet, characterized in that, include: Method A: Lithium metal is mixed with a complexing reagent solution to allow the lithium metal to react with the complexing reagent, thereby obtaining a liquid-phase lithiating agent; The liquid-phase lithiating agent is brought into contact with the electrode active material to pre-lithiate the electrode active material, thereby obtaining a pre-lithiated electrode active material. The pre-lithiated electrode active material is contacted with reactants to form a first inorganic lithium compound layer on at least a portion of the surface of the pre-lithiated electrode active material, thereby obtaining an electrode material. The electrode material comprises: a substrate, the substrate including the pre-lithiated electrode active material; and a first inorganic lithium compound layer covering at least a portion of the surface of the substrate, wherein, based on the total mass of the first inorganic lithium compound layer, the first inorganic lithium compound layer comprises 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide; Prepare an electrode sheet comprising the electrode material; Or method B: An initial electrode is provided, the initial electrode 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; Lithium metal is mixed with a complexing reagent solution to allow the lithium metal to react with the complexing reagent, thereby obtaining a liquid-phase lithiating agent; The liquid-phase lithiating agent is brought into contact with the electrode film to pre-lithiate the electrode active material, thereby obtaining an electrode sheet comprising the pre-lithiated electrode active material. The electrode sheet comprising the pre-lithiated electrode active material is brought into contact with the reactants to form a first inorganic lithium compound layer on the surface of the pre-lithiated electrode active material, thereby obtaining an electrode sheet comprising the electrode material. The electrode material comprises: a substrate, the substrate including the pre-lithiated electrode active material; and a first inorganic lithium compound layer covering at least a portion of the surface of the substrate, wherein, based on the total mass of the first inorganic lithium compound layer, the first inorganic lithium compound layer comprises 18%-90% lithium nitride, 0-28% lithium fluoride, 0-80% lithium oxide, 0-2% lithium carbonate, and 0-20% lithium sulfide.

26. The preparation method according to claim 25, characterized in that, The method A and / or method B further include: Providing the complexing reagent solution includes mixing the complexing reagent with a solvent to obtain the complexing reagent solution.

27. The preparation method according to claim 26, characterized in that, The coordinating 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.

28. The preparation method according to claim 26, characterized in that, The coordinating agent includes at least one of 2-methylnaphthalene, 1-naphthonitrile, 2,2-dimethylbiphenyl, 2-ethylindene, 1-methyl-3-ethylpyrene, or benzophenone.

29. The preparation method according to claim 26, characterized in that, The solvent includes at least one of alkanes and their derivatives, aromatic hydrocarbons and their derivatives, ethers and their derivatives, furans and their derivatives, pyrans and their derivatives, or esters and their derivatives.

30. The preparation method according to claim 26, characterized in that, The solvent includes at least one of benzene, toluene, xylene, ethylbenzene, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, pyran, or fluoroethylene carbonate.

31. The preparation method according to any one of claims 25-30, characterized in that, In method A and / or method B, the redox potential of the liquid-phase lithiation agent is 0.05V-1.5V.

32. The preparation method according to claim 31, characterized in that, In method A and / or method B, the redox potential of the liquid-phase lithiation agent is 0.1V-0.5V.

33. The preparation method according to any one of claims 25-32, characterized in that, In method A and / or method B, The molar ratio of lithium metal to the complexing agent is (0.5:1)-(10:1); And / or, the molar concentration of lithium in the liquid-phase lithiation agent is 0.01 mol / L to 10 mol / L; And / or, the molar ratio of lithium element to electrode active material in the liquid phase lithiation agent is (0.05:1)-(10:1); And / or, the volume distribution particle size Dv50 of the electrode active material is 0.5μm-40μm.

34. The preparation method according to claim 33, characterized in that, In method A and / or method B, The molar ratio of lithium metal to the complexing reagent is (1:1)-(4:1); And / or, the molar concentration of lithium in the liquid-phase lithiation agent is 0.01 mol / L to 5 mol / L; And / or, the molar ratio of lithium element to electrode active material in the liquid phase lithiation agent is (0.1:1)-(5:1).

35. The preparation method according to any one of claims 25-34, characterized in that, In method A and / or method B, The reactants include at least one of nitrogen, nitric oxide, nitrogen dioxide, and dinitrogen pentoxide, and at least one of air, water, oxygen, carbon dioxide, hydrogen fluoride, fluorine, sulfur, hydrogen sulfide, sulfur dioxide, sulfur trioxide, or red phosphorus.

36. A battery comprising at least one of the electrode material according to any one of claims 1-10, the electrode material prepared by the preparation method according to any one of claims 11-21, the electrode sheet according to any one of claims 22-24, or the electrode sheet prepared by the preparation method according to any one of claims 25-35.

37. An electrical device comprising the battery of claim 36.

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