Composite lithium supplementing negative electrode sheet and preparation method and application thereof

Abstract

The application provides a composite lithium supplementing negative electrode sheet and a preparation method and application thereof. The preparation method comprises the following steps: laminating and rolling a negative electrode film sheet and a functional layer film sheet to obtain a composite film sheet; the composite film sheet comprises a negative electrode active material layer and a functional layer; a current collector is arranged on one side of the negative electrode active material layer of the composite film sheet, a lithium foil is arranged on one side of the functional layer of the composite film sheet, and then the composite is obtained to obtain the composite lithium supplementing negative electrode sheet. The preparation method can separate the negative electrode and the lithium foil through the functional layer by means of co-rolling of the functional layer and the negative electrode film sheet, can avoid the problems of safety reduction caused by heat generation of lithium supplementing and lithium dendrite, can also avoid the situation of curling and breaking of the electrode sheet caused by direct coating of the functional layer on the negative electrode sheet, and improves the production quality and production efficiency of the negative electrode.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a composite lithium-added anode sheet, its preparation method and application. Background Technology

[0002] During the initial charging of a lithium-ion battery, the electrolyte reacts on the surface of the negative electrode to form an SEI film, simultaneously consuming lithium ions from the positive electrode. Furthermore, as the SEI film is continuously damaged and repaired during subsequent use, it continues to consume a significant amount of lithium ions from the positive electrode, resulting in irreversible lithium loss at the negative electrode. Using lithium foil for lithium replenishment is an easily mass-producible and relatively safe method for replenishing lithium to the negative electrode, which can improve the battery's initial efficiency, capacity, energy density, and cycle performance.

[0003] Traditional lithium foil replenishment methods involve directly combining lithium foil and the negative electrode to form a short circuit, enabling the reaction between lithium and the negative electrode. For example, CN 112786971A discloses a method for preparing a pre-lithiated lithium-ion battery with a negative electrode and the battery itself. The preparation method includes the following steps: preparing a negative electrode sheet, a positive electrode sheet, and a separator; combining metallic lithium onto at least one surface of the negative electrode sheet to obtain a composite negative electrode sheet; assembling the composite negative electrode sheet, the positive electrode sheet, and the separator into a bare cell, injecting electrolyte to obtain a lithium-ion cell; subjecting the lithium-ion cell to a short-circuit test with both positive and negative electrodes, followed by applying a bidirectional pulsed current to accelerate the rapid and uniform diffusion of lithium ions and the formation of the negative electrode SEI film during pre-lithiation; and finally obtaining a pre-lithiated lithium-ion battery.

[0004] However, the lithium replenishment method that directly combines lithium foil with the negative electrode has poor consistency in lithium replenishment, generates a lot of heat during the lithium replenishment process, and has certain safety risks. Moreover, it has high requirements for the incoming materials of the negative electrode and lithium foil. If the surface density of the incoming materials is not well controlled, over-lithiation can easily occur, resulting in lithium dendrites, causing battery short circuits and reduced safety.

[0005] Based on the above research, there is a need to provide a method for preparing a composite lithium-added anode sheet. The composite lithium-added anode sheet prepared by the method has high safety and can improve the production quality and efficiency of the anode. Summary of the Invention

[0006] The purpose of this invention is to provide a composite lithium-supplemented anode sheet, its preparation method, and its application. The preparation method uses a method of rolling the functional layer and the anode film together, which not only separates the anode and lithium foil through the functional layer, avoiding the safety degradation and lithium dendrite problems caused by the heat generated during lithium supplementation, but also avoids the problem of electrode curling and breakage caused by directly coating the functional layer on the anode sheet, thus improving the production quality and efficiency of the anode.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a composite lithium-supplemented anode sheet, the method comprising the following steps:

[0009] (1) The negative electrode film and the functional layer film are stacked and rolled to obtain a composite film;

[0010] The composite membrane includes a negative electrode active material layer and a functional layer;

[0011] (2) The current collector is placed on one side of the negative electrode active material layer of the composite film in step (1), and the lithium foil is placed on one side of the functional layer of the composite film in step (1). Then the composite is performed to obtain the composite lithium-added negative electrode sheet.

[0012] Preferably, the thickness of the negative electrode film in step (1) is above 800 μm, and more preferably 1000-3000 μm.

[0013] Preferably, the thickness of the functional layer film in step (1) is less than 300 μm, and more preferably less than 100 μm.

[0014] Preferably, the thickness ratio of the negative electrode film to the functional layer film in step (1) is ≥5, and more preferably 10-20.

[0015] Preferably, the compaction density of the negative electrode film in step (1) is 0.05 g / cm³. 3 and below.

[0016] Preferably, the compaction density of the functional layer membrane in step (1) is 0.03 g / cm³. 3 and below.

[0017] Preferably, the thickness of the composite film in step (1) is <500μm, and more preferably <300μm.

[0018] Preferably, the thickness of the functional layer in step (1) is ≤20μm, and more preferably ≤10μm.

[0019] Preferably, the negative electrode film in step (1) is prepared by a dry method, including the following steps:

[0020] The negative electrode active material, the first conductive agent and the first binder are mixed and fiberized, and then pre-pressed to obtain the negative electrode film.

[0021] Preferably, the functional layer film in step (1) is prepared by a dry method, including the following steps:

[0022] Solid electrolyte powder is mixed and fiberized, and then pre-pressed to obtain the functional layer membrane; the solid electrolyte powder contains a solid electrolyte, a second conductive agent, and a second binder.

[0023] Preferably, the solid electrolyte powder further includes additives, the amount of which accounts for 1-30 wt% of the weight of the second binder.

[0024] Preferably, the additive includes any one or a combination of at least two of sodium carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose.

[0025] Preferably, the fiberization method includes any one or a combination of at least two of air jet milling, high-speed mixing, mechanical fusion, or twin-screw extrusion.

[0026] Preferably, the negative electrode active material includes any one or a combination of at least two of the following: graphite, silicon, silicon-graphene, silicon-aluminum alloy, tin-based materials, graphene, pitch carbon microspheres, activated carbon, carbon fiber, graphene, carbon nanotubes, carbon aerogel, transition metal oxides, conductive polymers, lithium-containing compounds, hard carbon materials, or soft carbon materials.

[0027] Preferably, the solid electrolyte includes any one or a combination of at least two of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, hydride solid electrolytes, boride solid electrolytes, or nitride solid electrolytes.

[0028] Preferably, the first conductive agent and the second conductive agent independently comprise any one or a combination of at least two of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0029] Preferably, the first adhesive and the second adhesive each independently comprise any one or a combination of at least two of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyvinyl chloride, polystyrene, polyoxymethylene, polycarbonate, polyamide, acrylic plastics, polysulfone, polyphenylene ether, or carboxymethyl cellulose.

[0030] Preferably, the conductivity of the functional layer in step (1) is 0.001-0.01 mS / cm.

[0031] Preferably, the ionic conductivity of the functional layer after being impregnated with electrolyte in step (1) is >0.1 mS / cm.

[0032] Preferably, the electronic conductivity of the functional layer after being impregnated with electrolyte in step (1) is >0.1 mS / cm.

[0033] In a second aspect, the present invention provides a composite lithium-replenishing anode sheet, which is prepared by the preparation method described in the first aspect.

[0034] Thirdly, the present invention provides a battery comprising a composite lithium-filled anode sheet as described in the second aspect.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention produces a negative electrode film and a functional layer film respectively, and then stacks the two together and rolls them together to make them thinner at the same time, which simplifies the manufacturing process and improves production efficiency.

[0037] (2) Both the negative electrode film and the functional layer film of the present invention are obtained by dry method, and after the fabrication is completed, the two are rolled together to combine them, which can avoid the phenomenon of electrode curling and breakage caused by coating the functional layer slurry on the negative electrode, thereby helping to ensure the quality of the negative electrode.

[0038] (3) The present invention separates the negative electrode and the lithium foil through a functional layer, which reduces the heat generation rate during the lithium replenishment process, avoids the electrode from generating a large amount of heat during the lithium replenishment process, and improves the safety performance of the battery lithium replenishment.

[0039] (4) The composite lithium-replenishing negative electrode sheet prepared by the present invention, when lithium replenishment is excessive, the excess lithium will be deposited between the negative electrode active material and the functional layer, and randomly overlap with the fibrous binder to form a binder network with abundant pores; when lithium dendrites are generated, the lithium dendrites extend into the gaps of the binder network of the functional layer, and the binder network can control the generation direction of lithium dendrites, avoiding lithium dendrites piercing the separator and causing a short circuit between the positive and negative electrode sheets inside the battery, thereby improving the safety performance and effectiveness of lithium replenishment in the battery.

[0040] (5) The properties and contents of electrolyte particles and conductive agent particles in the functional layer film are different from those of active material particles in the negative electrode film. Electrolyte and conductive agent particles are relatively soft and have a lower content in the functional layer film, exhibiting better extensibility. When rolled together with the negative electrode film, the functional layer film can be thinned more significantly than the negative electrode film. At the same time, under the mechanical strength support of the negative electrode film, the functional layer film can be thinned to a thickness that is difficult to achieve by rolling alone while maintaining the integrity of the film. When applied to batteries, this not only achieves better safety and lithium replenishment effects, but also achieves higher energy density. Detailed Implementation

[0041] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0042] In a first aspect, the present invention provides a method for preparing a composite lithium-supplemented anode sheet, the method comprising the following steps:

[0043] (1) The negative electrode film and the functional layer film are stacked and rolled to obtain a composite film;

[0044] The composite membrane includes a negative electrode active material layer and a functional layer;

[0045] (2) The current collector is placed on one side of the negative electrode active material layer of the composite film in step (1), and the lithium foil is placed on one side of the functional layer of the composite film in step (1). Then the composite is performed to obtain the composite lithium-added negative electrode sheet.

[0046] In one aspect, before preparing the negative electrode sheet, the negative electrode film and the functional layer film are rolled together to composite them and reduce their thickness together. Compared with directly coating the functional layer slurry on the negative electrode sheet, this not only avoids the problems of electrode curling and cracking, but also produces a thinner composite film compared with rolling alone, thereby increasing the volumetric energy density of the battery. In another aspect, the present invention places the lithium foil on one side of the functional layer, separating the negative electrode sheet and the lithium foil with the functional layer, effectively avoiding the problems of heat generation during lithium replenishment and lithium dendrite piercing the separator.

[0047] The active material layer of the present invention is obtained by rolling a negative electrode film, and the functional layer is obtained by rolling a functional layer film; the negative electrode film of the present invention does not contain a current collector.

[0048] In some specific embodiments, the thickness of the negative electrode film in step (1) is above 800 μm, for example, it can be 900 μm, 1000 μm, 1500 μm, 2000 μm, 2500 μm or 3000 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1000-3000 μm.

[0049] In some specific embodiments, the thickness of the functional layer film in step (1) is less than 300 μm, for example, it can be 200 μm, 100 μm, 80 μm, 60 μm or 40 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably less than 100 μm.

[0050] In order to ensure the extensibility of the film during co-rolling and obtain a thinner composite film, the present invention preferably uses a thicker negative electrode film and a functional layer film of a specific thickness to simultaneously ensure a thinner composite film with better mechanical properties. However, in order to take into account the energy density of the battery, the functional layer film should not be too thick.

[0051] In some specific embodiments, the thickness ratio of the negative electrode film to the functional layer film in step (1) is ≥5, for example, it can be 5, 6, 7, 8, 9, 10 or 20, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 10-20.

[0052] The present invention preferably has a large thickness ratio between the negative electrode film and the functional layer film to achieve joint thinning and avoid curling and cracking.

[0053] In some specific embodiments, the compaction density of the negative electrode film in step (1) is 0.05 g / cm³. 3 and below, for example, 0.05 g / cm³ 3 0.01g / cm 3 0.005g / cm 3 0.0025g / cm 3 0.001g / cm 3 Or 0.0005g / cm 3 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0054] In some specific embodiments, the compaction density of the functional layer membrane in step (1) is 0.03 g / cm³. 3 and below, for example, 0.03 g / cm³ 3 0.01g / cm 3 0.005g / cm 3 0.0025g / cm 3 0.001g / cm 3 Or 0.0005g / cm 3 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0055] In order to ensure effective thinning and obtain a thinner composite membrane, the present invention preferably has a compaction density of the negative electrode membrane and the functional layer membrane within a small range to ensure that the membrane is hydrophobic and easy to thin. However, the compaction density should not be too small. If it is too small, there will be uneven thickness after rolling and changes in the thickness ratio of the negative electrode membrane and the functional layer membrane.

[0056] In some specific embodiments, the thickness of the composite film in step (1) is <500μm, for example, it can be 400μm, 300μm, 200μm, 100μm or 50μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably ≤300μm.

[0057] With the combination of the above-mentioned thickness and compaction density, the present invention can reduce the thickness of the millimeter-level membrane to ≤300μm and can effectively combine the negative electrode membrane and the functional layer membrane.

[0058] Preferably, the thickness of the functional layer in step (1) is ≤20μm, for example, it can be 20μm, 18μm, 16μm, 14μm, 12μm, 10μm, 8μm, 6μm, 4μm or 2μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably ≤10μm.

[0059] After co-rolling, the functional layer of the present invention can be effectively thinned, so that the thickness of the functional layer in the composite film is ≤20μm.

[0060] In some specific embodiments, the negative electrode film in step (1) is prepared by a dry method, including the following steps:

[0061] The negative electrode active material, the first conductive agent and the first binder are mixed and fiberized, and then pre-pressed to obtain the negative electrode film.

[0062] In some specific embodiments, the functional layer film in step (1) is prepared by a dry method, including the following steps:

[0063] Solid electrolyte powder is mixed and fiberized, and then pre-pressed to obtain the functional layer membrane; the solid electrolyte powder contains a solid electrolyte, a second conductive agent, and a second binder.

[0064] In some specific embodiments, the solid electrolyte powder further includes additives, the amount of which accounts for 1-30 wt% of the weight of the second binder, for example, 5 wt%, 10 wt%, 20 wt% or 30 wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0065] The present invention also adds additives to the electrolyte powder, which can increase the plasticity of the functional layer film, improve its ductility, and provide tensile support along the film surface direction, thereby reducing the risk of breakage of the functional layer film during calendering.

[0066] In some specific embodiments, the additive includes any one or a combination of at least two of sodium carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose.

[0067] In some specific embodiments, the fiberization method includes any one or a combination of at least two of air jet milling, high-speed mixing, mechanical fusion, or twin-screw extrusion.

[0068] This invention does not impose any particular limitation on the type of negative electrode active material. Any known negative electrode active material can be used in this invention without departing from the inventive concept.

[0069] In some specific embodiments, the negative electrode active material includes any one or a combination of at least two of the following: graphite, silicon, silicon-graphene, silicon-aluminum alloy, tin-based materials, graphene, pitch carbon microspheres, activated carbon, carbon fiber, graphene, carbon nanotubes, carbon aerogel, transition metal oxides, conductive polymers, lithium-containing compounds, hard carbon materials, or soft carbon materials. Typical but non-limiting combinations include a combination of graphite and silicon, or a combination of pitch carbon microspheres and activated carbon.

[0070] This invention does not specifically limit the solid electrolyte; any known solid electrolyte can be used in this invention.

[0071] In some specific embodiments, the solid electrolyte includes any one or a combination of at least two of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, hydride solid electrolytes, boride solid electrolytes, or nitride solid electrolytes. Typical but non-limiting combinations include combinations of oxide solid electrolytes and sulfide solid electrolytes, or combinations of halide solid electrolytes and hydride solid electrolytes.

[0072] In some specific embodiments, the first conductive agent and the second conductive agent each independently include any one or a combination of at least two of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene or carbon nanofibers. Typical but not limited combinations include a combination of superconducting carbon and acetylene black, or a combination of carbon black and Ketjen black.

[0073] In some specific embodiments, the first adhesive and the second adhesive each independently comprise any one or a combination of at least two of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyvinyl chloride, polystyrene, polyoxymethylene, polycarbonate, polyamide, acrylic plastics, polysulfone, polyphenylene ether, or carboxymethyl cellulose. Typical but non-limiting combinations include combinations of polytetrafluoroethylene and polyvinylidene fluoride, or combinations of polypropylene and polyvinyl chloride.

[0074] In some specific embodiments, the conductivity of the functional layer in step (1) is 0.001-0.01 mS / cm, for example, it can be 0.002 mS / cm, 0.004 mS / cm, 0.006 mS / cm or 0.008 mS / cm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0075] In some specific embodiments, the ionic conductivity of the functional layer after being wetted with electrolyte in step (1) is >0.1 mS / cm, for example, it can be 0.2 mS / cm, 0.4 mS / cm, 0.6 mS / cm, 0.8 mS / cm or 1 mS / cm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0076] In some specific embodiments, the electronic conductivity of the functional layer after being wetted with electrolyte in step (1) is >0.1 mS / cm, for example, it can be 0.2 mS / cm, 0.4 mS / cm, 0.6 mS / cm, 0.8 mS / cm or 1 mS / cm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0077] In a second aspect, the present invention provides a composite lithium-replenishing anode sheet, which is prepared by the preparation method described in the first aspect.

[0078] Thirdly, the present invention provides a battery comprising a composite lithium-filled anode sheet as described in the second aspect.

[0079] Example 1

[0080] This embodiment provides a method for preparing a composite lithium-supplemented anode sheet, the method comprising the following steps:

[0081] (1) The negative electrode active material, conductive agent, and fiberizable binder are dry-mixed, then placed in an air jet mill and fiberized at a speed of 55 m / s for 10 min. The mixture is then pre-pressed at 100°C using a four-roll calender to obtain a negative electrode film. The thickness of the negative electrode film is 1000 μm, and the compaction density is 0.05 g / cm³. 3 ;

[0082] Solid electrolyte, conductive agent, and fiberizable binder are dry-mixed, then placed in an air jet mill and fiberized at 55 m / s for 10 min. The mixture is then pre-pressed at 100°C using a four-roll calender to obtain a functional layer membrane with a thickness of 200 μm and a compaction density of 0.03 g / cm³. 3 ;

[0083] The negative electrode active material is graphite, the solid electrolyte includes oxide solid electrolyte LLZO, the conductive agent is carbon nanotubes, and the fiberizable binder is carboxymethyl cellulose.

[0084] (2) Stack the negative electrode film described in step (1) and the functional layer film described in step (1) together, and then roll them together to obtain a composite film;

[0085] (3) A current collector copper foil is placed on one side of the negative electrode active material layer of the composite membrane described in step (2), and a lithium foil is placed on one side of the functional layer of the composite membrane described in step (2), wherein the thickness of the lithium foil is 5 μm and the areal density is 0.26 mg / cm³. 2Then, thermal bonding is performed to obtain the composite lithium-replenishing anode sheet, wherein the thickness of the composite lithium-replenishing anode sheet is 150 μm, and the thickness of the functional layer in the composite lithium-replenishing anode sheet is 16 μm.

[0086] Example 2

[0087] This embodiment provides a method for preparing a composite lithium-supplemented negative electrode sheet. Except for step (1), where the thickness of the negative electrode film is 2800 μm and the thickness of the functional layer film is 280 μm, so that the thickness of the functional layer changes accordingly after rolling, the rest of the preparation method is the same as in embodiment 1.

[0088] Example 3

[0089] This embodiment provides a method for preparing a composite lithium-supplemented negative electrode sheet. Except for step (1), where the thickness of the negative electrode film is 1500 μm and the thickness of the functional layer film is 100 μm, so that the thickness of the functional layer changes accordingly after rolling, the preparation method is the same as in embodiment 1.

[0090] Example 4

[0091] This embodiment provides a method for preparing a composite lithium-supplemented negative electrode sheet. Except for step (1), where the thickness of the negative electrode film is 1600 μm and the thickness of the functional layer film is 80 μm, so that the thickness of the functional layer changes accordingly after rolling, the preparation method is the same as in embodiment 1.

[0092] Example 5

[0093] This embodiment provides a method for preparing a composite lithium-supplemented negative electrode sheet, wherein the preparation method, except that the negative electrode film in step (1) has a compaction density of 0.02 g / cm³, is provided. 3 The compaction density of the functional layer membrane is 0.01 g / cm³. 3 Except for the change in the thickness of the functional layer after rolling, everything else is the same as in Example 1.

[0094] Example 6

[0095] This embodiment provides a method for preparing a composite lithium-supplemented negative electrode sheet. Except for step (1) when preparing the functional layer film, an additive (hydroxyethyl cellulose) accounting for 10 wt% of the weight of the fiberizable binder in the functional layer film is added to make the thickness of the functional layer change accordingly after rolling. The rest of the preparation method is the same as in Example 1.

[0096] Comparative Example 1

[0097] This comparative example provides a method for preparing a composite lithium-supplemented negative electrode sheet. The preparation method is the same as that in Example 1, except that it includes rolling (non-pre-rolling) according to step (1) of Example 1 to obtain a negative electrode film with a thickness of 130 μm and a functional layer film with a thickness of 50 μm, so that the thickness of the functional layer changes accordingly after rolling.

[0098] Comparative Example 2

[0099] This comparative example provides a method for preparing a composite lithium-supplemented negative electrode sheet. Except for step (1), where the thickness of the negative electrode film is 400 μm and the thickness of the functional layer film is 1380 μm, so that the thickness of the functional layer changes accordingly after rolling, the preparation method is the same as in Example 1.

[0100] The thickness ratio of the negative electrode film and the functional layer film before rolling, the thickness of the negative electrode film, the thickness of the functional layer film, and the thickness of the functional layer after rolling are shown in Table 1 in the above embodiments and comparative examples.

[0101] Table 1

[0102]

[0103]

[0104] As can be seen from the table above:

[0105] The common rolling process of this invention ensures effective thinning of the functional layer after rolling, indicating a high rolling effect. Furthermore, this invention also yields a flat, crack-free, and relatively thin negative electrode sheet. As shown in Examples 1, 2-6, and Comparative Examples 1-2, the thickness of the negative electrode film and the thickness of the functional layer affect the rolling effect. As shown in Examples 1 and 5, the preferred compaction density of the negative electrode film in this invention is 0.05 g / cm³. 3 The compaction density of the functional layer membrane is below 0.03 g / cm³. 3 As can be seen from Examples 1 and 6, adding a one-dimensional additive to the electrolyte powder can improve the plasticity of the functional layer film and enhance its ductility.

[0106] In summary, this invention provides a composite lithium-supplemented anode sheet, its preparation method, and its application. The preparation method, by rolling the functional layer and the anode film together, not only separates the anode and lithium foil through the functional layer, avoiding the safety degradation and lithium dendrite problems caused by lithium supplementation heat generation, but also avoids the electrode curling and breakage caused by directly coating the functional layer on the anode sheet, thus improving the production quality and efficiency of the anode.

[0107] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A preparation method of a composite lithium supplementing negative electrode sheet, characterized by comprising the following steps: 3 1. A preparation method of a composite lithium supplementing negative electrode sheet, characterized by comprising the following steps: 3 (1) laminating and rolling the negative electrode film and the functional layer film to obtain a composite film; The thickness of the negative electrode film is 1000-3000 μm, and the thickness of the functional layer film is 80-300 μm; The thickness ratio of the negative electrode film to the functional layer film is 10-20; The composite film comprises a negative electrode active material layer and a functional layer, and the thickness of the functional layer is ≤16 μm; The compacted density of the negative electrode film is 0.05 g / cm 3 and the following; The functional layer film has a compacted density of 0.03 g / cm 3 and the following; The functional layer film is prepared by a dry method, comprising the following steps: mixing and fiberizing solid electrolyte powder, and then pre-pressing to obtain the functional layer film; the solid electrolyte powder comprises a solid electrolyte, a second conductive agent and a second binder; The negative electrode film is prepared by a dry method, comprising the following steps: mixing and fiberizing negative electrode active material, a first conductive agent and a first binder, and then pre-pressing to obtain the negative electrode film; (2) arranging a current collector on one side of the negative electrode active material layer of the composite film in step (1), arranging a lithium foil on one side of the functional layer of the composite film in step (1), and then compounding to obtain the composite lithium supplementing negative electrode sheet.

2. The production method according to claim 1, characterized by, The thickness of the functional layer film in step (1) is below 100 μm.

3. The preparation method according to claim 1, characterized in that, The thickness of the composite film in step (1) is <500 μm.

4. The production method according to claim 3, characterized by, The thickness of the composite film in step (1) is <300 μm.

5. The preparation method according to claim 1, characterized in that, The thickness of the functional layer in step (1) is ≤10 μm.

6. The method of claim 1, wherein, The solid electrolyte powder further comprises an additive, and the additive is added in an amount of 1-30 wt% of the weight of the second binder.

7. The production method according to claim 6, wherein The additive comprises any one or a combination of at least two of sodium carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl methyl cellulose.

8. The method of claim 1, wherein, The first conductive agent and the second conductive agent each independently comprise any one or a combination of at least two of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene or carbon nanofibers.

9. The method of claim 1, wherein, The first binder and the second binder each independently comprise any one or a combination of at least two of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyvinyl chloride, polystyrene, polyformaldehyde, polycarbonate, polyamide, acrylic plastic, polysulfone, polyphenyl ether or carboxymethyl cellulose.

10. The method of claim 1, wherein, The conductivity of the functional layer in step (1) is 0.001-0.01 mS / cm.

11. The method of claim 1, wherein, The ionic conductivity of the functional layer after being infiltrated with electrolyte in step (1) is >0.1 mS / cm.

12. The method of claim 1, wherein, The electronic conductivity of the functional layer after being infiltrated with electrolyte in step (1) is >0.1 mS / cm.

13. A composite lithium-added anode sheet, characterized in that, The composite lithium supplementing negative electrode sheet is prepared by the preparation method in any one of claims 1-12.

14. A battery, characterized by The battery comprises the composite lithium supplementing negative electrode sheet in claim 13.

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