WO2023029437A1 - 一种负极极片补锂方法及设备 - Google Patents

一种负极极片补锂方法及设备 Download PDF

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Publication number
WO2023029437A1
WO2023029437A1 PCT/CN2022/081325 CN2022081325W WO2023029437A1 WO 2023029437 A1 WO2023029437 A1 WO 2023029437A1 CN 2022081325 W CN2022081325 W CN 2022081325W WO 2023029437 A1 WO2023029437 A1 WO 2023029437A1
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WIPO (PCT)
Prior art keywords
lithium
negative electrode
lithium foil
electrode sheet
pole piece
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PCT/CN2022/081325
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English (en)
French (fr)
Inventor
李峥
冯玉川
刘京亮
陈凯
何泓材
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苏州清陶新能源科技有限公司
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Publication of WO2023029437A1 publication Critical patent/WO2023029437A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the invention relates to the technical field of batteries, in particular to a method and equipment for replenishing lithium on a negative pole piece.
  • Lithium foil supplementation is an easy-to-mass-produce and high-safety lithium supplementation method for battery negative electrodes. Lithium supplementation with lithium foil can improve battery first efficiency, battery capacity, energy density and cycle performance.
  • the specific implementation of lithium foil lithium supplementation is usually to use a roller press or a composite machine to simultaneously roll the lithium foil and the battery negative electrode, so as to transfer the metallic lithium from the lining film to the battery negative electrode.
  • the outer surface of the roller press or compound machine used for lithium foil lithium supplementation is usually smooth.
  • this roller for roller pressing has some problems: when the pressure applied to the roller Smaller, the metal lithium and the negative electrode of the battery are not tightly combined, and the two are easy to separate; when the pressure applied to the pressure roller is large, the negative electrode of the battery will be stretched and deformed, causing the pole piece to be scrapped. Therefore, the final product qualification rate of the lithium foil lithium replenishment carried out by adopting this smooth pressure roller is relatively low.
  • lithium supplementation can improve the initial efficiency of the battery, it is limited by the current lithium battery equipment.
  • the thickness of commercial lithium supplementary lithium foil is more than 5 ⁇ m, and the surface density is high, which exceeds the actual needs of lithium supplementation. If there are too many lithium ions, there will be lithium residues after the lithium replenishment process is completed, and in severe cases, it may even lead to lithium precipitation at the negative electrode.
  • the invention provides a method for supplementing lithium with a negative pole piece, which can make the lithium foil and the battery pole piece tightly bonded and not easy to separate, and is not easy to cause the battery pole piece to be stretched and deformed to cause the pole piece to be scrapped, thereby improving the lithium foil lithium supplementation method. product pass rate.
  • the present invention provides following scheme:
  • a method for supplementing lithium with a negative pole piece comprising:
  • the lithium foil and the negative pole piece are respectively drawn to the rolling area by the first pulling device and the second pulling device;
  • the rolling area is provided with a rolling device, and the rolling device includes a first pressure roller close to the lithium foil and a second pressure roller close to the negative electrode sheet, at least part of the surface of the first pressure roller is provided with a structure that is convex or concave toward the surface of the lithium foil to be supplemented with lithium;
  • the lithium foil and the negative pole piece are rolled through the gap between the first pressure roller and the second pressure roller, and the lithium foil is located between the first pressure roller and the negative pole piece between;
  • the lithium foil after lithium supplementation and the negative electrode sheet after lithium supplementation are respectively wound up by the first winding device and the second winding device.
  • the lithium foil and the negative electrode sheet are rolled by using the first pressing roller and the second pressing roller of the rolling equipment, wherein the surface of the first pressing roller is provided with a convex or concave structure facing the surface to be supplemented with lithium,
  • the lithium foil and the negative electrode sheet are partly stressed, and the lithium foil discontinuously adheres to the surface of the negative electrode sheet to complete lithium supplementation.
  • the raised structure includes one of a mesh structure or a stripe structure.
  • the area of the convex or concave structure accounts for [20-80%] of the roll surface area of the first pressing roll.
  • the height of the raised structures is [2-1000 ⁇ m].
  • the depth of the recessed structure is [2-1000 ⁇ m].
  • the first pressing roller includes a first limiting band
  • the second pressing roller includes a second limiting band
  • the first limiting band is arranged opposite to the second limiting band
  • the method for supplementing lithium with the negative pole piece also includes:
  • the sum of the thicknesses of the first limiting band and the second limiting band is determined according to the sum of the thicknesses of the negative electrode sheet and the lithium foil.
  • the determining the thickness sum of the first limiting band and the second limiting band according to the thickness sum of the pole piece and the lithium foil includes:
  • the second aspect of the present invention provides a negative pole piece lithium replenishment device for realizing the lithium replenishment method described in the first aspect, comprising:
  • the pulling device includes a first pulling device and a second pulling device, the first pulling device pulls the lithium foil to the rolling area, and the second pulling device pulls the negative electrode sheet to the rolling area;
  • the rolling equipment includes a first pressing roller and a second pressing roller, and at least part of the surface of the first pressing roller is provided with a convex or concave structure facing the second pressing roller.
  • the first pressing roller includes a first limiting band
  • the second pressing roller includes a second limiting band
  • the first limiting band is arranged opposite to the second limiting band
  • the The sum of the thicknesses of the first limiting band and the second limiting band is determined according to the sum of the thicknesses of the pole piece and the lithium foil.
  • the invention discloses the following technical effects:
  • At least part of the surface of the rolling device used in the lithium replenishment method provided by the present invention is provided with a convex or concave structure facing the surface to be replenished with lithium.
  • the convex or concave structure makes The partial contact between the lithium foil and the negative pole piece allows the density of lithium supplementation to be adjusted without causing too much lithium ions.
  • the partial contact between the lithium foil and the negative electrode sheet makes the lithium foil and the negative electrode sheet tightly bonded under a small applied pressure. Cause pole pieces to be scrapped. Therefore, the present invention can solve the problems caused by the smooth pressing roller in the prior art, and improves the qualified rate of products.
  • using the lithium supplementation method provided in this embodiment increases the product qualification rate from less than 50% to greater than 95%.
  • Fig. 1 is a flow chart of a method for replenishing lithium on a pole piece provided by an embodiment of the present invention.
  • Fig. 1 is a flow chart of a method for replenishing lithium on a pole piece provided by an embodiment of the present invention.
  • the invention provides a method for supplementing lithium with a negative pole piece, which is used for supplementing lithium for a lithium battery.
  • the method for supplementing lithium with a negative pole piece generally includes:
  • the lithium foil and the negative electrode sheet are respectively pulled to the rolling area by the first traction equipment and the second traction equipment; the rolling area is provided with a rolling equipment, and the rolling equipment includes a first pressure roller close to the lithium foil and a pole close to the negative pole.
  • the second pressing roller of the sheet, at least a part of the surface of the first pressing roller is provided with a convex or concave structure facing the surface of the lithium foil to be supplemented with lithium;
  • the lithium foil and the negative pole piece are rolled through the gap between the first pressure roller and the second pressure roller, and the lithium foil is located between the first pressure roller and the negative pole piece;
  • the lithium foil after lithium supplementation and the negative electrode sheet after lithium supplementation are respectively wound up by the first winding device and the second winding device.
  • the force applied by the pressure roller to the lithium foil partially acts on the surface of the lithium foil, so that the lithium foil is partially connected to the negative electrode sheet.
  • Contact which makes the lithium foil and the negative pole piece tightly bonded under a small pressure during the rolling process, the two are not easy to separate, and it is not easy to cause the battery pole piece to be stretched and deformed, causing the pole piece to be scrapped .
  • the proportion of depressions and/or protrusions can be adjusted according to the required amount of lithium supplementation.
  • the area of the protrusions or depressions accounts for [20-80%] of the surface area of the first pressure roller.
  • the convex or concave structures are uniformly arranged, so that the lithium foil is discontinuously and uniformly adhered to the negative electrode sheet.
  • the number of protrusions or depressions per inch on the surface of the first pressure roller is [30-1000], and the number of protrusions and/or depressions is 30, 50, 80, 100, 300 , 500, 600, 800 or 1000.
  • the negative electrode sheet is rolled on the unwinding roller, and the unwinding roller is arranged upstream of the above-mentioned first traction device, and correspondingly, downstream of the above-mentioned rolling device is also provided with a device for collecting and replenishing Take-up roll for lithium-finished pole pieces.
  • the unwinding roller, rolling equipment and winding roller work at the same time.
  • At least part of the surface of the rolling equipment used in the lithium replenishment method provided in this embodiment is provided with a convex or concave structure facing the surface to be replenished with lithium.
  • the raised part (when the surface of the first press roller is provided with a raised structure, the raised part is formed as a raised structure; when the surface of the first press roller is provided with a recessed structure, the raised part is formed as a recess The part other than the structure) is in contact with the lithium foil, thereby combining the lithium foil with the surface to be replenished.
  • the convex or concave structure reduces the contact area between the lithium foil and the first pressure roller.
  • the present invention can solve the problems caused by the smooth pressing roller in the prior art, and improves the qualified rate of products.
  • using the lithium supplementation method provided in this embodiment increases the product qualification rate from less than 50% to greater than 95%.
  • the application has no special limitation on the shape of the concave and/or protruding structures. Any common shape can be used in this application without departing from the inventive concept of the application, including but not limited to circle, ellipse, and straight line , one or more of the curves.
  • the raised structure includes one of a textured structure or a striped structure.
  • a textured structure generally refers to a structure formed by intersecting lines with different extending directions
  • a stripe structure generally refers to a structure formed by the arrangement of lines with approximately the same extending direction.
  • the present application has no special requirement on the height or depth of the protrusion and/or the recessed structure, as long as the contact between the lithium foil and the negative electrode sheet can be ensured without violating the inventive concept of the present application.
  • the value of the height and/or depth can be [2-1000 ⁇ m], it can be understood that when a raised structure is used, the height represents the distance from the roll surface of the first pressure roller to the top surface of the raised structure, when When a recessed structure is used, the depth represents the distance from the roll surface of the first press roll to the bottom surface of the recessed structure.
  • the height or depth of the raised and/or depressed structures is 2 ⁇ m, 3 ⁇ m, 5 ⁇ m, 10 ⁇ m, 20 ⁇ m, 50 ⁇ m, 100 ⁇ m, 300 ⁇ m, 500 ⁇ m or 1000 ⁇ m.
  • This application does not specifically limit the type of lithium foil. It can be understood that any known foil covering the negative electrode sheet that can replenish lithium to the negative electrode through a specific lithium replenishment process can be used in this application, including but It is not limited to elemental lithium, lithium-silicon alloy, and the like.
  • the negative electrode of the present application can be applied to a liquid battery, a solid-state battery or a solid-liquid hybrid battery, and the battery also includes a positive pole piece, an electrolyte and/or a solid electrolyte.
  • the negative electrode active material contains one or more of Si-based materials, Sn-based materials, Si/C, SiO/C, Sn/C, Si halides, Sn halides, Si alloys, and Sn alloys.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material.
  • a positive electrode current collector and a positive electrode active material.
  • any known positive electrode active material and positive electrode sheet can be can be used in this application.
  • the specific types of the separator, solid electrolyte, and electrolyte in the battery are not specifically limited, and can be any material used in existing batteries without violating the inventive concept of the present application.
  • the first pressing roller includes a first limiting band
  • the second pressing roller includes a second limiting band
  • the first limiting band is arranged opposite to the second limiting band
  • the negative pole piece complements the second limiting band.
  • Lithium methods also include:
  • the sum of the thicknesses of the first limiting band and the second limiting band is determined according to the sum of the thicknesses of the negative electrode sheet and the lithium foil.
  • both the first limiting band and the second limiting band are arranged at positions corresponding to the battery lugs of the pole pieces.
  • Using the pressure roller in the prior art to replenish lithium is very likely to cause metal lithium to adhere to the tabs of the battery, affecting subsequent welding of the tabs.
  • this embodiment sets the first limit band or the second limit band on the position corresponding to the pressure roller and the tab, so as to avoid the adhesion of metal lithium on the tab, thereby solving the problems in the prior art. The problem.
  • only the first limiting band may be provided, or only the second limiting band may be provided.
  • both the first limiting band and the second limiting band are arranged along the circumferential direction of the pressure roller.
  • determining the thickness sum of the first limiting band and the second limiting band according to the thickness sum of the negative electrode sheet and the lithium foil includes:
  • the difference between the thickness sum of the first limit band and the second limit band and the thickness sum of the negative electrode sheet and the lithium foil is set to be greater than the first preset threshold and smaller than the second preset threshold.
  • the gap size between the first pressing roller and the second pressing roller is smaller than the sum of the thicknesses of the negative electrode sheet and the lithium foil, and the rolling equipment rolls the lithium foil and the negative electrode sheet in a corresponding state, resulting in The lithium foil adhered intermittently to the negative electrode sheet. The rest of the lithium foil is intermittently retained on the lithium foil except that it is intermittently adhered to the negative electrode sheet.
  • the negative electrode sheet includes a current collector and an active material layer. It can be understood that the lithium foil is placed on the side of the active material layer and is in contact with the active material layer. In the lithium supplementation process, due to the existence of potential difference, electrons spontaneously move to the negative electrode, accompanied by the intercalation of Li+ in the negative electrode.
  • the thicknesses of the first limit band and the second limit band are H2 and H3 respectively
  • the first preset threshold is set ⁇ H2+H3-H1 ⁇ the second preset threshold Thresholds are set, wherein the first preset threshold is -200 ⁇ m, and the second preset threshold is 200 ⁇ m. In this way, the qualified rate of the product can be further improved.
  • the negative pole piece lithium replenishing method before S1, the negative pole piece lithium replenishing method also includes:
  • placing the lithium foil on the lithium surface to be replenished of the pole piece includes:
  • the present invention also provides a device specially used to realize the method for replenishing lithium on the negative pole piece described in the above embodiment, including traction equipment, rolling equipment and winding equipment;
  • the pulling device includes a first pulling device and a second pulling device, the first pulling device pulls the lithium foil to the rolling area, and the second pulling device pulls the negative electrode sheet to the rolling area.
  • the rolling equipment includes a first pressing roller and a second pressing roller. At least a part of the surface of the first pressing roller is provided with a convex or concave structure facing the second pressing roller.
  • the setting ratio of depressions and/or protrusions can be adjusted according to the required amount of lithium supplementation.
  • the area of the protrusion/depression structure accounts for [20-80%] of the surface area of the first pressure roller.
  • the present application has no special requirement on the height or depth of the protrusion and/or the recessed structure, as long as the contact between the lithium foil and the negative electrode sheet can be ensured without violating the inventive concept of the present application.
  • the value of height and/or depth can be [2-1000 ⁇ m], it can be understood that when using a raised structure, the height represents the distance from the roll surface of the pressure roller to the top surface of the raised structure, when using a concave In terms of structure, the depth indicates the distance from the roller surface of the pressure roller to the bottom surface of the depression.
  • the height or depth of the raised and/or depressed structures is 2 ⁇ m, 3 ⁇ m, 5 ⁇ m, 10 ⁇ m, 20 ⁇ m, 50 ⁇ m, 100 ⁇ m, 300 ⁇ m, 500 ⁇ m or 1000 ⁇ m.
  • At least part of the surface of the first pressing roller used in the pole piece lithium replenishment equipment provided in this embodiment is provided with a raised structure facing the surface to be replenished with lithium.
  • the raised structure and the lithium The foil is in contact, thereby combining the lithium foil with the surface to be replenished. Therefore, the present invention can solve the problems caused by the smooth pressing roller in the prior art, and improves the qualified rate of products.
  • using the lithium supplementation method provided in this embodiment increases the product qualification rate from less than 50% to greater than 95%.
  • the first pressing roller includes a first limiting band
  • the second pressing roller includes a second limiting band
  • the first limiting band is opposite to the second limiting band
  • the thickness sum of the second limit band is determined according to the thickness sum of the pole piece and the lithium foil.
  • the pole piece lithium replenishment device provided in this embodiment can replenish lithium on both sides of the pole piece at the same time.
  • the rolling device includes a first pressing roller and a second pressing roller, wherein the first pressing The roller is provided with raised structures with a height of 30 ⁇ m or with depressed structures with a depth of 30 ⁇ m;
  • the lithium foil and the negative pole piece pass through the gap between the first pressing roller and the second pressing roller through the action of the first pulling device and the second pulling device to complete rolling, wherein the lithium foil is in contact with the first pressing roller, and the negative electrode
  • the pole piece is in contact with the second pressing roller, and the rolling pressure is 8T.
  • the above-mentioned positive pole piece, the negative pole piece treated in step (3), and the separator are laminated, placed in an aluminum-plastic film, and injected into a liquid to form a lithium-ion battery.
  • Preparation of the battery of the comparative example compared with the preparation method of the embodiment, the difference is only in step (3) that the first pressing roll and the second pressing roll are the same, both are smooth rolls, and the other is the same as the embodiment.
  • the battery is formed with a charge and discharge current of 1C. After the formation is completed, remove the battery cell and observe the formation interface. If there is metal lithium residue on the interface, it means that the amount of lithium supplement is excessive. If there is no metal lithium residue, it means that the amount of lithium supplement is moderate.

Abstract

一种负极极片补锂方法及设备，涉及电池技术领域。负极极片补锂方法包括：S1.通过第一牵引设备、第二牵引设备分别将锂箔、负极极片牵引到辊压区域；辊压区域设置辊压设备，辊压设备包括靠近锂箔的第一压辊和靠近负极极片的第二压辊，第一压辊的表面至少部分区域设有朝向负极极片的待补锂表面的凸起或凹陷结构；S2.锂箔和负极极片经过第一压辊和第二压辊之间的间隙完成辊压，锂箔位于第一压辊与负极极片之间；S3.通过第一收卷设备、第二收卷设备分别将补锂后的锂箔和补锂后的负极极片进行收卷。本发明能够使得锂箔和电池极片结合紧密不容易脱离，且不容易使电池极片发生延展变形而造成极片报废，从而能够提高锂箔补锂的产品合格率。

Description

一种负极极片补锂方法及设备 技术领域
本发明涉及电池技术领域，特别是涉及一种负极极片补锂方法及设备。
背景技术
锂箔补锂是一种容易量产且安全性较高的电池负极补锂方式，通过锂箔补锂可以提升电池首效、电池容量、能量密度和循环性能。锂箔补锂的具体实施方式通常是采用辊压机或复合机对锂箔和电池负极同时进行辊压，从而将金属锂从衬膜上转移至电池负极上。
现有技术中，锂箔补锂所使用的辊压机或复合机的压辊外表面通常都是光面的，使用这个压辊进行辊压，存在一些问题：当施加在压辊上的压力较小，金属锂和电池负极结合不紧密，两者容易脱离；当施加在压辊上的压力较大时，则会使电池负极发生延展变形，造成极片报废。因此，采用这种光面的压辊所进行的锂箔补锂最终的产品合格率较低。
另一方面，虽然补锂能提高电池的首次效率，但受限于目前的锂电设备，商业化的补锂锂箔厚度均在5μm以上，面密度较高，超出了实际补锂的需要，造成锂离子过多，补锂工艺结束后，会有锂残留，严重的时候甚至导致负极析锂。
为了解决该问题，目前的研究方向主要在于超薄锂箔的制备，但这种方法对设备要求过高，当前难以完全产业化。
所以，如何提升锂箔补锂的产品合格率，成为本领域技术人员需要解决的技术问题。
发明内容
本发明提供了一种负极极片补锂方法，能够使得锂箔和电池极片结合紧密 不容易脱离，且不容易使电池极片发生延展变形而造成极片报废，从而能够提高锂箔补锂的产品合格率。
本发明提供了如下方案：
一种负极极片补锂方法，包括：
S1.通过第一牵引设备、第二牵引设备分别将锂箔、负极极片牵引到辊压区域；所述辊压区域设置辊压设备，所述辊压设备包括靠近锂箔的第一压辊和靠近负极极片的第二压辊，所述第一压辊的表面至少部分区域设有朝向所述锂箔的待补锂表面凸起或凹陷的结构；
S2.所述锂箔和所述负极极片经过所述第一压辊和所述第二压辊的间隙完成辊压，所述锂箔位于所述第一压辊与所述负极极片之间；
S3.通过第一收卷设备、第二收卷设备分别将补锂后的锂箔和补锂后的负极极片进行收卷。
利用辊压设备的第一压辊和第二压辊对所述锂箔和所述负极极片进行压延，其中第一压辊的表面设置的朝向待补锂面的凸起或凹陷的结构，使得辊压时，锂箔与负极极片之间部分受力，锂箔不连续地粘附在负极极片表面，完成补锂。
可选地，所述凸起的结构包括网纹结构或条纹结构中的一种。
可选地，所述凸起或凹陷结构的面积占第一压辊的辊面面积的[20-80％]。
可选地，所述凸起的结构的高度为[2-1000μm]。
可选地，所述凹陷的结构的深度为[2-1000μm]。
可选地，所述第一压辊包括第一限位带，所述第二压辊包括第二限位带，所述第一限位带与所述第二限位带相对设置，
可选地，所述负极极片补锂方法还包括：
根据所述负极极片以及所述锂箔的厚度和确定所述第一限位带以及所述第二限位带的厚度和。
可选地，所述根据所述极片以及所述锂箔的厚度和确定所述第一限位带以及所述第二限位带的厚度和包括：
设置所述第一限位带以及所述第二限位带的厚度和与所述极片以及所述 锂箔的厚度和之差大于第一预设阈值，且小于第二预设阈值。
本发明第二方面提供一种用于实现第一方面所述的补锂方法的负极极片补锂设备，包括：
牵引设备、辊压设备和收卷设备；
所述牵引设备包括第一牵引设备和第二牵引设备，所述第一牵引设备将锂箔牵引到辊压区域，所述第二牵引设备将负极极片牵引到辊压区域；
所述辊压设备包括第一压辊和第二压辊，所述第一压辊的表面至少部分区域设有朝向第二压辊的凸起或凹陷结构。
可选地，所述第一压辊包括第一限位带，所述第二压辊包括第二限位带，所述第一限位带与所述第二限位带相对设置，所述第一限位带以及所述第二限位带的厚度和根据所述极片以及所述锂箔的厚度和确定。
根据本发明提供的具体实施例，本发明公开了以下技术效果：
本发明提供的补锂方法中所使用的辊压装置的第一压辊表面至少部分区域设置有朝向待补锂面的凸起或凹陷的结构，在压延过程中，凸起或凹陷的结构使得锂箔与负极极片之间部分接触，使得补锂密度可以调节，不会造成锂离子过多。并且，锂箔与负极极片之间部分接触使得在较小的施加压力下，即可使锂箔与负极极片紧密结合，两者不容易脱离，且不容易使电池极片发生延展变形而造成极片报废。因此，本发明能够解决现有技术中光面压辊带来的问题，提升了产品合格率。在一些优选的情况下，采用本实施例提供的补锂方法使得产品合格率从小于50％提升至大于95％。
当然，本发明的实施例并不一定需要同时达到以上所述的所有优点。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本发明一个实施例提供的极片补锂方法的流程框图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本发明保护的范围。
图1是本发明一个实施例提供的极片补锂方法的流程框图。本发明提供了一种负极极片补锂方法，用于为锂电池补锂，负极极片补锂方法一般性地包括：
S1.通过第一牵引设备、第二牵引设备分别将锂箔、负极极片牵引到辊压区域；辊压区域设置辊压设备，辊压设备包括靠近锂箔的第一压辊和靠近负极极片的第二压辊，第一压辊的表面至少部分区域设有朝向所述锂箔的待补锂表面凸起或凹陷的结构；
S2.锂箔和负极极片经过第一压辊和第二压辊之间的间隙完成辊压，锂箔位于第一压辊与负极极片之间；
S3.通过第一收卷设备、第二收卷设备分别将补锂后的锂箔和补锂后的负极极片进行收卷。
通过在靠近锂箔一侧的第一压辊辊面设置凸起或凹陷结构，使得压辊施加到锂箔上的作用力部分地作用于锂箔表面，进而使得锂箔部分地与负极极片接触，这使得辊压过程中，在较小的施加压力下，即可使锂箔与负极极片紧密结合，两者不容易脱离，且不容易使电池极片发生延展变形而造成极片报废。
凹陷和/或凸起的比例可以根据所需的补锂量进行调整，优选地，凸起或凹陷结构的面积占第一压辊辊面面积的[20-80％]。
作为一种实施方式，所述凸起或凹陷结构均匀设置，使得锂箔非连续地均匀地粘附到负极极片上。
优选地，所述第一压辊表面每英寸长度的凸起或凹陷结构的个数为[30-1000]个，凸起和/或凹陷结构的个数为30、50、80、100、300、500、600、800或1000。
需要特别说明的是，在一些实施例中，负极极片卷在放卷辊上，放卷辊设置在上述第一牵引设备的上游，对应地，上述辊压设备的下游还设置有用于收 集补锂完成的极片的收卷辊。在进行补锂时，放卷辊、辊压设备和收卷辊同时工作。
本实施例提供的补锂方法中所使用的辊压设备的第一压辊表面至少部分区域设置有朝向待补锂面的凸起或凹陷的结构，在压延过程中，凸起的部分(当第一压辊表面设置的为凸起的结构时，该凸起的部分即为凸起的结构形成，当第一压辊表面设置的为凹陷的结构时，该凸起的部分即为凹陷的结构以外的部分)与锂箔接触，从而将锂箔与待补锂面结合。凸起或凹陷的结构减小了锂箔与第一压辊之间的接触面积，对第一压辊施加压力相同的情况下，作用在锂箔上的压强更大，从而能够使得锂箔和电池极片结合紧密不容易脱离，且不容易使电池极片发生延展变形而造成极片报废。因此，本发明能够解决现有技术中光面压辊带来的问题，提升了产品合格率。在一些优选的情况下，采用本实施例提供的补锂方法使得产品合格率从小于50％提升至大于95％。
本申请对凹陷和/或凸出结构的形状没有特别限定，在不违背本申请发明构思的基础上，任何常见的形状均能用于本申请中，包括但不限于圆形、椭圆形、直线、曲线中的一种或几种。
在一个优选的实施例中，凸起的结构包括网纹结构或条纹结构中的一种。网纹结构通常是指由延伸方向不同的线条交叉形成的结构，条纹结构通常是指由延伸方向大致相同的线条排布形成的结构。
本申请对凸起和/或凹陷结构的高度或深度没有特别要求，在不违背本申请发明构思的基础上，能保证锂箔和负极极片部分的接触即可。高度和/或深度的数值可以为[2-1000μm]，可以理解的是，当使用凸起的结构时，高度表示了第一压辊的辊面到凸起的结构的顶面的距离，当使用凹陷的结构时，深度表示了第一压辊的辊面到凹陷的结构的底面的距离。凸起和/或凹陷结构的高度或深度为2μm、3μm、5μm、10μm、20μm、50μm、100μm、300μm、500μm或1000μm。
本申请对锂箔的种类没有特别限定，可以理解的是，任何已知的覆盖在负极极片上经过特定的补锂工序能够对负极进行补锂的箔片均能用于本申请中，包括但不限于单质锂、锂硅合金等。
本申请的负极可以应用于液态电池、固态电池或固液混合电池，电池还包括正极极片、电解液和/或固态电解质。
优选地，负极活性物质包含Si基材料、Sn基材料、Si/C、SiO/C、Sn/C、Si的卤化物、Sn的卤化物、Si合金、Sn合金中的一种或几种。
正极极片包括正极集流体和正极活性物质，作为本申请的实施方式，对应用体系没有特别的限定，在不违背本申请发明构思的基础上，任何已知的正极活性物质、正极极片均能用于本申请中。
电池中的隔膜、固态电解质、电解液的具体种类也不受到具体限制，在不违背本申请发明构思的基础上，可以是现有电池中使用的任何材料。
在一个具体的实施例中，第一压辊包括第一限位带，第二压辊包括第二限位带，第一限位带与所述第二限位带相对设置，负极极片补锂方法还包括：
根据负极极片以及锂箔的厚度和确定第一限位带以及第二限位带的厚度和。
优选地，第一限位带和第二限位带均设置在与极片的电池极耳对应的位置上。采用现有技术中的压辊补锂非常容易造成电池的极耳上粘附金属锂，影响后续极耳的焊接。为了解决这一问题，本实施例在压辊与极耳对应的位置上设置第一限位带或第二限位带，避免了极耳上粘附金属锂，从而解决了现有技术中存在的问题。
更为优选地，在一些实施例中，可以仅设置第一限位带，也可以仅设置第二限位带。具体地，将第一限位带和第二限位带均沿压辊的周向布置。
在一个具体的实施例中，根据负极极片以及锂箔的厚度和确定第一限位带以及第二限位带的厚度和包括：
设置第一限位带以及第二限位带的厚度和与负极极片以及锂箔的厚度和之差大于第一预设阈值，且小于第二预设阈值。
其中，第一压辊和第二压辊之间的间隙尺寸小于负极极片、锂箔的厚度之和，辊压设备将锂箔、负极极片在对应的状态下进行辊压，由此导致锂箔间断性地粘附到负极极片上。而锂箔中除间断性地粘附到负极极片上外的剩余部分间断性地保留在锂箔上。
可以理解的是，在不违背本申请发明构思的基础上，可以在第一压辊、锂箔、负极极片、第二压辊之间设置其他已知的衬膜，衬膜的含义可以理解为不对补锂产生实质性的作用，仅仅是为了辊压工艺更为顺畅而设置的辅助膜。本发明对衬膜的种类没有特别限定，任何已知的衬膜均能用于本申请中。
负极极片包括集流体和活性物质层，可以理解的是，锂箔置于活性物质层一侧，与活性物质层接触。在补锂工序中，由于电势差的存在，电子自发地向负极移动，伴随着Li+在负极的嵌入。
具体地，假定锂箔与极片的厚度和为H1，第一限位带和第二限位带的厚度分别为H2和H3，设置第一预设阈值<H2+H3-H1<第二预设阈值，其中，第一预设阈值为-200μm，第二预设阈值为200μm，如此，能够进一步地提升产品的合格率。
在一个具体的实施例中，S1之前，负极极片补锂方法还包括：
调节第一压辊和第二压辊之间的间隙，以使待补锂面与锂箔贴合，要求第一压辊和第二压辊之间的间隙稍小于极片和锂箔的厚度之和，从而使得待补锂面和锂箔之间具有一定的压力。
在一个具体的实施例中，将锂箔放置于极片的待补锂面上包括：
本发明还提供了一种专门用于实现上述实施例所述的负极极片补锂方法的设备，包括牵引设备、辊压设备和收卷设备；
牵引设备包括第一牵引设备和第二牵引设备，第一牵引设备将锂箔牵引到辊压区域，第二牵引设备将负极极片牵引到辊压区域。辊压设备包括第一压辊和第二压辊，第一压辊的表面至少部分区域设有朝向第二压辊的凸起或凹陷结构。凹陷和/或凸起的设置比例可以根据所需的补锂量进行调整，优选地，凸起/凹陷结构的面积占第一压辊辊面面积的[20-80％]。
本申请对凸起和/或凹陷结构的高度或深度没有特别要求，在不违背本申请发明构思的基础上，能保证锂箔和负极极片部分的接触即可。高度和/或深度的数值可以为[2-1000μm]，可以理解的是，当使用凸起的结构时，高度表示了压辊的辊面到凸起结构的顶面的距离，当使用凹陷的结构时，深度表示了压辊的辊面到凹陷的底面的距离。凸起和/或凹陷的结构的高度或深度为2μ m、3μm、5μm、10μm、20μm、50μm、100μm、300μm、500μm或1000μm。本实施例提供的极片补锂设备中所使用的辊压装置的第一压辊表面至少部分区域设置有朝向待补锂面的凸起的结构，在压延过程中，凸起的结构与锂箔接触，从而将锂箔与待补锂面结合。因此，本发明能够解决现有技术中光面压辊带来的问题，提升了产品合格率。在一些优选的情况下，采用本实施例提供的补锂方法使得产品合格率从小于50％提升至大于95％。
在一个具体的实施例中，第一压辊包括第一限位带，第二压辊包括第二限位带，第一限位带与第二限位带相对设置，第一限位带以及第二限位带的厚度和根据极片以及锂箔的厚度和确定。本实施例提供的极片补锂设备可以同时对极片的两面补锂。
电池的制备
(1)正极制备
将LCO、Super-P、PVDF按96:2:2混合溶解于溶剂NMP中，搅拌均匀后涂布在铝箔上，烘干得到正极极片。
(2)负极极片
将SiO/C(未经预锂化处理的SiO材料)、Super-P、负极粘结剂(SBR+CMC)按95:2:3溶解于溶剂中，搅拌均匀得到负极浆料，然后涂布到铜箔上，烘干得到待补锂的负极极片。
(3)负极补锂
准备8μm厚的锂箔，通过第一牵引设备、第二牵引设备将锂箔、负极极片分别牵引到辊压区域，辊压设备包括第一压辊和第二压辊，其中，第一压辊设置有高度为30μm的凸起的结构或深度为30μm的凹陷的结构；
锂箔和负极极片通过第一牵引设备、第二牵引设备的作用，穿过第一压辊和第二压辊之间的间隙完成辊压，其中，锂箔与第一压辊接触，负极极片与第二压辊接触，辊压压力为8T。
(4)锂离子电池的制备
将上述正极极片、经过步骤(3)处理过的负极极片、隔膜进行叠片，放到铝塑膜中，注液化成得到锂离子电池。
对比例电池的制备：与实施例的制备方法相比，区别仅在步骤(3)第一压辊与第二压辊相同，均为光面辊，其他与实施例相同。
性能测试：
(1)补锂界面观察
以1C充放电电流对电池进行化成，化成完成后拆除电芯观察化成界面，如果界面存在金属锂残留，则说明补锂量过剩，如果没有金属锂残留，则说明补锂量适中。
(2)首次充放电效率
在室温条件下，以1/3C进行充电至终止电压，截止电流0.05C，记录充电容量，静置30min。以1/3C进行放电至终止电压，记录放电容量，用放电容量比充电容量则得首次充放电效率。
(3)500次循环效率
1.室温下，以1C或规定电流进行充电至终止电压，截止电流0.05C，静置30min；
2.以1C进行放电至放电终压，记录放电容量，静置30min；
循环(1)-(2)500次；
3.计算500圈循环性能。
测试结果见下表：
Figure PCTCN2022081325-appb-000001
通过对比实施例1-4和对比例1，可以得出，通过本申请的补锂方法制备 得到的锂电池，大幅度提高了电池的首次充放电效率，也克服了补锂量过剩导致金属锂残留的问题。
以上对本发明所提供的技术方案，进行了详细介绍，本文中应用了具体个例对本发明的结构及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处。综上所述，本说明书内容不应理解为对本发明的限制。

Claims (10)

  1. 一种负极极片补锂方法，其特征在于，包括：
    S1.通过第一牵引设备、第二牵引设备分别将锂箔、负极极片牵引到辊压区域；所述辊压区域设置辊压设备，所述辊压设备包括靠近锂箔的第一压辊和靠近负极极片的第二压辊，所述第一压辊的表面至少部分区域设有朝向所述锂箔的待补锂表面凸起或凹陷的结构；
    S2.所述锂箔和所述负极极片经过所述第一压辊和所述第二压辊之间的间隙完成辊压，所述锂箔位于所述第一压辊与所述负极极片之间；
    S3.通过第一收卷设备、第二收卷设备分别将补锂后的锂箔和补锂后的负极极片进行收卷。
  2. 根据权利要求1所述的负极极片补锂方法，其特征在于，所述凸起的或凹陷结构包括网纹结构或条纹结构中的一种。
  3. 根据权利要求2所述的负极极片补锂方法，其特征在于，所述凸起或凹陷结构的面积占所述第一压辊辊面面积的[20-80％]。
  4. 根据权利要求1至3任一项所述的负极极片补锂方法，其特征在于，所述凸起的结构的高度为[2-1000μm]。
  5. 根据权利要求1至3任一项所述的负极极片补锂方法，其特征在于，所述凹陷的结构的深度为[2-1000μm]。
  6. 根据权利要求1至3任一项所述的负极极片补锂方法，其特征在于，所述第一压辊包括第一限位带，所述第二压辊包括第二限位带，所述第一限位带与所述第二限位带相对设置。
  7. 根据权利要求6所述的负极极片补锂方法，其特征在于，还包括：
    根据所述负极极片以及所述锂箔的厚度和确定所述第一限位带以及所述 第二限位带的厚度和。
  8. 根据权利要求7所述的负极极片补锂方法，其特征在于，所述根据所述负极极片以及所述锂箔的厚度和确定所述第一限位带以及所述第二限位带的厚度和包括：
    设置所述第一限位带以及所述第二限位带的厚度和与所述负极极片以及所述锂箔的厚度和之差大于第一预设阈值，且小于第二预设阈值。
  9. 一种负极极片补锂设备，其特征在于，包括：
    牵引设备、辊压设备和收卷设备；
    所述牵引设备包括第一牵引设备和第二牵引设备，所述第一牵引设备将锂箔牵引到辊压区域，所述第二牵引设备将负极极片牵引到辊压区域；
    所述辊压设备包括第一压辊和第二压辊，所述第一压辊的表面至少部分区域设有朝向第二压辊的凸起或凹陷结构。
  10. 根据权利要求9所述的负极极片补锂设备，其特征在于，所述第一压辊包括第一限位带，所述第二压辊包括第二限位带，所述第一限位带与所述第二限位带相对设置。
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