CN115312977B - Winding battery core, preparation method thereof, battery module, battery pack and electric equipment - Google Patents

Winding battery core, preparation method thereof, battery module, battery pack and electric equipment Download PDF

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Publication number
CN115312977B
CN115312977B CN202211004022.6A CN202211004022A CN115312977B CN 115312977 B CN115312977 B CN 115312977B CN 202211004022 A CN202211004022 A CN 202211004022A CN 115312977 B CN115312977 B CN 115312977B
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sub
winding
adhesive layer
diaphragm
thickness
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CN115312977A (en
Inventor
谢鹏飞
梁金云
黄汉川
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Xiamen Hithium Energy Storage Technology Co Ltd
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Xiamen Hithium Energy Storage Technology Co Ltd
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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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/426—Fluorocarbon polymers
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Cell Separators (AREA)

Abstract

The invention discloses a winding electric core, a preparation method thereof, a battery module, a battery pack and electric equipment. The winding cell comprises a winding body, wherein a winding unit of the winding body comprises a positive plate, a negative plate and two layers of diaphragms, the winding body is limited to a first section of winding body and a second section of winding body, and the second section of winding body is formed by continuously winding on the first section of winding body; at least one layer of diaphragm takes the part in the first section of winding body as a first sub-diaphragm and the part in the second section of winding body as a second sub-diaphragm, wherein one side of the first sub-diaphragm contacted with the negative electrode sheet is provided with a first adhesive layer, and the first adhesive layer comprises a first adhesive layer, a second adhesive layer and a third adhesive layer, wherein the second adhesive layer comprises a first adhesive layer and a second adhesive layer, and the third adhesive layer comprises a third adhesive layer and a fourth adhesive layer which is formed on the third adhesive layer, and the fourth adhesive layer comprises a third adhesive layer and a fourth adhesive layer which is formed on the side of the third adhesive layer: the side of the second sub-diaphragm, which is contacted with the negative electrode plate, is not provided with an adhesive layer; or, a second adhesive layer is arranged on one side of the second sub-separator, which is contacted with the negative electrode plate, and the thickness of the second adhesive layer is smaller than that of the first adhesive layer. The winding battery cell not only can remarkably improve the expansion and fold problems of the negative plate, but also can reduce the cost of the diaphragm and the battery cell.

Description

Winding battery core, preparation method thereof, battery module, battery pack and electric equipment
Technical Field
The invention belongs to the field of batteries, and particularly relates to a winding electric core, a preparation method thereof, a battery module, a battery pack and electric equipment.
Background
The production process of the coiled battery has the advantages of high production speed, good continuity, lower equipment requirement and easier control of the consistency of the battery. However, wound cells have the following disadvantages: the large battery core produced by winding cannot release the expansion force of the inner-layer negative electrode plate after full charge, and the folds are serious, so that the thickness of the battery is obviously increased or swelled; in addition, the lithium risk of the battery cell can be increased due to the fact that the negative electrode plate is folded, the battery cell fails in advance, and electrochemical performance, safety performance and service life of the battery are affected. At present, in order to solve the problem of wrinkling of the negative electrode sheet, a mode of contacting a rubberized diaphragm with the negative electrode sheet is adopted, but compared with a diaphragm without rubberizing, the cost of directly adopting the diaphragm with an adhesive coating is higher, and is usually about 2-3 times of the cost of the diaphragm without rubberizing. Therefore, it is of great importance to provide a wound battery that is low in cost, has good safety, and can effectively solve the problem of wrinkling of the negative electrode sheet.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, an object of the invention is to propose a winding cell and a method for its production, a battery module, a battery pack and an electrical consumer. The winding battery cell not only can remarkably improve the expansion and fold problems of the negative plate, but also can reduce the cost of the diaphragm and the battery cell.
The present application is mainly based on the following problems and findings: in the existing winding battery cell, in order to improve the problem of the wrinkles of the negative electrode sheet, in the adopted separator with the adhesive coating, the adhesive coating is coated on the whole contact surface of the separator and the negative electrode sheet (namely, the full-coating separator), and the inventor finds that the wrinkles of the negative electrode sheet are mainly concentrated on the inner ring of the battery cell.
In view of this, in one aspect of the present application, a winding cell is provided. According to an embodiment of the present application, the winding cell includes: the winding unit of the winding body comprises a positive plate, a negative plate and two layers of diaphragms, the winding body is limited with a first winding body and a second winding body, and the second winding body is formed by continuously winding on the first winding body; at least one layer of separator is characterized in that a part in the first section of winding body is used as a first sub-separator, a part in the second section of winding body is used as a second sub-separator, and a first adhesive layer is arranged on one side of the first sub-separator, which is in contact with the negative electrode sheet, wherein: an adhesive layer is not arranged on one side of the second sub-diaphragm, which is contacted with the negative electrode plate; or, a second adhesive layer is arranged on one side of the second sub-separator, which is contacted with the negative electrode plate, and the thickness of the second adhesive layer is smaller than that of the first adhesive layer. The inventor finds that the expansion force and the folds of the negative electrode plate of the inner ring in the winding battery core in the lithium intercalation process are more obvious, and the folds of the negative electrode plate are mainly concentrated in the inner ring of the battery core. Compared with the existing winding battery core, the application can remarkably improve the expansion and fold problems of the battery core negative electrode sheet, reduce the lithium precipitation risk of the battery core, improve the safety performance of the battery core, be beneficial to preventing the electrochemical performance of the battery core from being reduced or failing in advance, and reduce the cost of the battery core and the battery core by forming the adhesive layer on the separator of the first winding body or making the thickness of the adhesive layer formed on the separator of the second winding body smaller than that of the first winding body.
In addition, the winding cell according to the above embodiment of the present invention may further have the following additional technical features:
in some embodiments of the invention, the ratio of the number of windings of the one-piece winding body to the number of windings of the two-piece winding body is 0.2-2.
In some embodiments of the invention, the ratio of the number of windings of the one-piece winding body to the number of windings of the two-piece winding body is 0.5 to 1.
In some embodiments of the invention, the first adhesive layer and the second adhesive layer each independently comprise a polymeric adhesive.
In some embodiments of the invention, the polymeric binder comprises at least one selected from polyvinylidene fluoride, polyvinyl alcohol, and carboxymethyl cellulose.
In some embodiments of the invention, the first binder layer further has inorganic particles dispersed therein.
In some embodiments of the invention, the second binder layer further has inorganic particles dispersed therein.
In some embodiments of the present invention, the inorganic particles in the first binder layer and the inorganic particles in the second binder layer each independently comprise a material selected from boehmite, alumina, zrO 2 And LLZTO.
In some embodiments of the present invention, in the first binder layer and the second binder layer, the mass ratio of the inorganic particles and the polymer binder is (0.1 to 9.9) independently of each other: (9.9-0.1).
In some embodiments of the invention, the separator is a PE film or a PP film.
In some embodiments of the invention, the first sub-membrane and the second sub-membrane are in a continuous uninterrupted structure in the same layer of the membrane.
In some embodiments of the invention, the first sub-membrane is adhesively attached to the second sub-membrane in the same layer of the membrane.
In some embodiments of the invention, the first sub-membrane is thermally fused to the second sub-membrane; and/or the first sub-diaphragm and the second sub-diaphragm are overlapped and bonded and connected, and the width of the overlapped area is 2-5 mm.
In some embodiments of the invention, the hot melt connection is accomplished by hot pressing the junction of the first sub-membrane and the second sub-membrane at a temperature of 250-300 c at a pressure of 3000-5000 kgf for a time of 5-10 s.
In some embodiments of the invention, the thickness of the overlap region is no greater than 10 μm from the thickness difference of the first sub-membrane and from the thickness difference of the second sub-membrane.
In some embodiments of the invention, in the overlap region, the edges of the first and second sub-diaphragms are each independently linear, zigzag or wavy along the width direction of the diaphragm.
In some embodiments of the invention, the roll includes a planar region and a inflection region, the overlap region being located within the inflection region.
In some embodiments of the invention, at least one of the positive electrode sheet and the negative electrode sheet is provided with a thickness reduction region corresponding to the overlap region on a side facing the separator.
In some embodiments of the present invention, the total reduced thickness of the thickness reduced region is 1 to 1.2 times the thickness of the overlapping region, and the width of the reduced region is not smaller than the width of the overlapping region; and/or the thickness reduction areas are arranged on the positive plate and the negative plate, the thickness reduction thickness of the thickness reduction area positioned on the positive plate is (0.7+/-0.1) times the thickness of the overlapped area, and the thickness reduction thickness of the thickness reduction area positioned on the negative plate is (0.3+/-0.1) times the thickness of the overlapped area.
In some embodiments of the invention, the thickness of the first sub-membrane is equal to the thickness of the second sub-membrane.
In some embodiments of the present invention, an adhesive layer is not provided on a side of the second sub-separator that contacts the negative electrode sheet, and a total thickness of the first sub-separator and the first adhesive layer is equal to a thickness of the second sub-separator.
In some embodiments of the invention, the total thickness of the first sub-membrane and the first adhesive layer is equal to the total thickness of the second sub-membrane and the second adhesive layer.
According to yet another aspect of the invention, a method of making a wound cell is provided. According to an embodiment of the invention, the method comprises: winding by a winding unit to obtain a wound body, wherein: the winding unit comprises a positive plate, a negative plate and two layers of diaphragms, wherein the winding body comprises a first winding body and a second winding body, and the second winding body is formed by continuously winding on the first winding body; at least one layer of separator is characterized in that a part in the first section of winding body is used as a first sub-separator, a part in the second section of winding body is used as a second sub-separator, and a first adhesive layer is arranged on one side of the first sub-separator, which is in contact with the negative electrode sheet, wherein: an adhesive layer is not arranged on one side of the second sub-diaphragm, which is contacted with the negative electrode plate; or, a second adhesive layer is arranged on one side of the second sub-separator, which is contacted with the negative electrode plate, and the thickness of the second adhesive layer is smaller than that of the first adhesive layer. Compared with the prior art, the method has the advantages that the adhesive layer is formed on the separator of the first winding body, or the thickness of the adhesive layer formed on the separator of the second winding body is smaller than that of the separator of the first winding body, so that the problems of expansion and wrinkling of the negative electrode plate of the battery cell can be remarkably improved, the lithium precipitation risk of the battery cell is reduced, the safety performance of the battery cell is improved, the electrochemical performance of the battery cell is prevented from being reduced or failure is prevented in advance, and the cost of the separator and the battery cell can be reduced.
In some embodiments of the invention, before the winding, further comprising: and carrying out hot pressing treatment on the joint of the first sub-diaphragm and the second sub-diaphragm, thereby realizing hot melting connection of the first sub-diaphragm and the second sub-diaphragm.
In some embodiments of the present invention, after the winding is completed, the method further comprises: and (3) performing hot press forming on the winding body, wherein the temperature of the hot press forming is 85-110 ℃, the pressure is 8000-11000 kgf, and the time is not less than 60s.
According to still another aspect of the present invention, a battery module is provided. According to an embodiment of the present invention, the battery module includes the wound cell described above or a wound cell manufactured by the method of manufacturing a wound cell described above. All the features and effects described with respect to the above-described wound cells and the above-described method of manufacturing the wound cells are equally applicable to the battery module, and are not repeated here. In general, the battery module has good volume stability and electrochemical stability, high safety, longer service life and lower cost.
According to yet another aspect of the present invention, a battery pack is provided. According to an embodiment of the present invention, the battery module includes the aforementioned battery module. All the features and effects described for the battery module described above are equally applicable to the battery pack, and are not described here again.
According to yet another aspect of the present invention, a powered device is presented. According to an embodiment of the invention, the electric equipment comprises the battery pack, the battery module, the winding battery core manufactured by the method for manufacturing the winding battery core, or the winding battery core. All the features and effects described for the battery pack, the battery module, the method for preparing the wound battery cell and the wound battery cell described above are equally applicable to the electric device, and are not described here again. Overall, the stability of the consumer in use is better and the safety risk is lower.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
fig. 1 is a schematic view showing the overall structure of a wound body of a wound cell according to an embodiment of the present invention.
Fig. 2 is a schematic view of a winding structure of a winding cell according to an embodiment of the present invention.
Fig. 3 is a schematic structural view of a winding unit in a winding cell according to an embodiment of the present invention.
Fig. 4 is a schematic diagram of adhesive layer comparison structures of a primary winding body and a secondary winding body according to an embodiment of the present invention.
Fig. 5 is a schematic view showing the adhesive layer comparison structure of a primary winding body and a secondary winding body according to still another embodiment of the present invention.
Fig. 6 is a schematic structural view of an overlapping region of a first sub-diaphragm and a second sub-diaphragm according to one embodiment of the present invention.
Fig. 7 is a schematic view of a winding structure of a winding cell according to still another embodiment of the present invention.
Fig. 8 is a schematic view of a structure in which thickness reduction regions are provided on a positive electrode sheet and a negative electrode sheet according to an embodiment of the present invention.
Fig. 9 is a schematic structural view of the overall thickness distribution of the same layer of membrane according to one embodiment of the present invention.
Fig. 10 is a schematic view of the overall thickness distribution of the same layer of membrane according to still another embodiment of the present invention.
Description of the drawings:
100-winding; 10-a length of winding; 20-two-stage winding; 30-planar area; 40-bending region; a-a negative plate; b-a positive plate; c-a separator; c1-a first sub-membrane; c2-a second sub-membrane; d1—a first adhesive layer; d2—a second adhesive layer; width of w-overlap region; s-thickness reduced region.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
In the description of the present invention, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the present invention, unless explicitly specified and limited otherwise, terms such as "mounted," "connected," "secured," and the like are to be construed broadly and may be, for example, fixedly attached, detachably attached, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances. In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium.
In one aspect of the invention, a wound cell is provided. As will be appreciated in connection with fig. 1-5, the wound cell, according to an embodiment of the present invention, comprises: a winding unit (shown in fig. 3) of the winding body 100 includes a negative electrode sheet a, a positive electrode sheet b and two separator layers c, the winding body 100 is defined with a first winding body 10 and a second winding body 20, and the second winding body 20 is formed by continuously winding on the first winding body 10; as will be understood with reference to fig. 4 to 5, in at least one of the separator layers c, a first sub-separator c1 is a portion located in the first-stage wound body 10, and a second sub-separator c2 is a portion located in the second-stage wound body 20, and a first adhesive layer d1 is provided on a side of the first sub-separator c1 contacting the negative electrode sheet a, wherein: the side of the second sub separator c2 contacting the negative electrode sheet a is not provided with an adhesive layer (as shown in fig. 4); alternatively, the second sub separator c2 is provided with a second adhesive layer d2 on a side contacting the negative electrode sheet a, and the thickness of the second adhesive layer d2 is smaller than that of the first adhesive layer d1 (as shown in fig. 5). The inventor finds that the expansion force and the folds of the negative electrode plate of the inner ring in the winding battery core in the lithium intercalation process are more obvious, and the folds of the negative electrode plate are mainly concentrated in the inner ring of the battery core. Compared with the existing winding battery core, the invention can remarkably improve the expansion and fold problems of the battery core negative electrode sheet, reduce the lithium precipitation risk of the battery core, improve the safety performance of the battery core, be beneficial to preventing the electrochemical performance of the battery core from being reduced or failing in advance, and reduce the cost of the battery core and the battery core by forming the adhesive layer on the separator of the first winding body or making the thickness of the adhesive layer formed on the separator of the second winding body smaller than that of the first winding body.
The wound cells according to the above embodiments of the present invention will be described in detail with reference to fig. 1 to 10.
According to an embodiment of the present invention, the ratio of the number of windings of the primary winding body 10 to the number of windings of the secondary winding body 20 may be 0.2 to 2, and may be, for example, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9, etc. The number of windings of the two-stage wound body 20 is the number of windings to be wound continuously on the one-stage wound body 10. The inventor finds that, based on the binding of the winding structure of the battery core and the battery core shell, the expansion force born by the negative electrode plate of the inner ring is larger, the fold is more serious, especially the expansion force and fold problem born by the negative electrode plate of the outer ring are gradually reduced along with the increase of the winding number of the inner ring winding body with the total winding number of 1/3 (especially 1/5), and the expansion and fold problem born by the negative electrode plate of the outer ring is controlled to be 0.2-2, namely, the winding number of the first section of the winding body with the total winding number of 1/5-2 and 1/3-1/2, the first adhesive layer d1 with stronger adhesive capacity is designed for the negative electrode plate of the first section of the winding body with more serious expansion and fold problem (the separator of the inner ring is tightly adhered with the negative electrode plate after hot pressing), and the second section of the negative electrode plate with less obvious expansion and fold problem is not provided with an adhesive layer or the second adhesive layer d2 with smaller adhesive layer thickness is provided, so that the expansion and fold of the negative electrode plate of the battery core can be obviously improved, the lithium-precipitation performance of the battery core can be reduced, the battery core can be prevented from being failed, and the battery core can be prevented from being failed in advance, and the battery core can be prevented from being failed. Preferably, the ratio of the number of windings of the primary winding body 10 to the number of windings of the secondary winding body 20 may be 0.5 to 1, even though the number of windings of the primary winding body is 1/3 to 1/2 of the total number of windings, thereby further improving the problem of expansion and wrinkling of the wound battery cell negative electrode sheet and better considering the costs of the separator and the battery cell.
According to an embodiment of the present invention, the first adhesive layer d1 and the second adhesive layer d2 may each independently include a polymer adhesive, and it is understood that the first adhesive layer d1 and the second adhesive layer d2 may each independently be a pure adhesive layer, i.e., may be formed of only a polymer adhesive, or may each independently be doped with some other component, such as an inorganic (ceramic) material, etc., i.e., the adhesive layers may be composite layers formed of a polymer adhesive and an inorganic material. The kind of the polymer binder is not particularly limited, and may be flexibly selected according to actual needs by those skilled in the art, for example, the polymer binder used for the first binder layer d1 and the second binder layer d2 may each independently include at least one selected from polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and carboxymethyl cellulose (CMC). According to some specific examples of the present invention, the first binder layer d1 may further have inorganic particles dispersed therein; in addition, according to some specific examples of the present invention, inorganic particles may be dispersed in the second binder layer d2, wherein by adding the inorganic particles in the binder layer, it is more advantageous to improve the thermal stability, mechanical strength, and wettability of the separator.
It should be noted that the kinds of the inorganic particles in the first binder layer d1 and the inorganic particles in the second binder layer d2 are not particularly limited, and those skilled in the art can flexibly select according to actual needs, for example, the inorganic particles in the first binder layer d1 and the inorganic particles in the second binder layer d2 may each independently include a material selected from boehmite, alumina, zrO 2 And LLZTO (tantalum doped lithium lanthanum zirconium oxide), wherein selecting inorganic particles of the above kind is more advantageous for improving the thermal stability, mechanical strength and wettability of the separator, especially when boehmite is included in the inorganic particles; when LLZTO is included in the inorganic particles, the ion conductivity of the separator can be further improved, and at the same time, the binder layer can resist higher voltage, and electrochemical corrosion of the separator can be reduced. The particle diameter of the inorganic particles in the present invention may preferably be nano-sized, for example, may be not more than 200nm or 100nm, thereby further contributing to improvement of the flatness of the adhesive layer.
According to some embodiments of the present invention, in the first binder layer d1 and the second binder layer d2, the mass ratio of the inorganic particles and the polymer binder may be (0.1 to 9.9) independently of each other: (9.9 to 0.1), for example, may be 0.1/9.9, 0.5/9.5, 1/9, 1.5/8.5, 2/8, 2.5/7.5, 3/7, 3.5/6.5, 4/6, 4.5/5.5, 5/5, 5.5/4.5, 6/4/6.5/3.5, 7/3, 8/2, 9/1 or 9.9/0.1, etc. independently, respectively, wherein increasing the amount of the polymer binder in the binder layer is more advantageous for solving the problem of swelling and wrinkling of the negative electrode sheet, increasing the amount of the inorganic particles is more advantageous for improving the thermal stability, mechanical strength and wettability of the separator, and considering that an excessive amount of the inorganic particles may affect the bonding strength of the separator to the negative electrode sheet, it may be preferable that the mass ratio of the inorganic particles to the polymer binder is not more than 8/2, for example, and the mass ratio of the inorganic particles to the polymer binder may be (0.1 to 5): (5-9.9), etc. According to a specific example of the present invention, when inorganic particles are dispersed in the first binder layer d1 or the second binder layer d2, the polymer binder layer used in the binder layer may preferably be PVDF, whereby the binding ability of the binder layer can be further ensured, and the effect of improving the expansion and wrinkling of the separator to the anode sheet can be ensured.
According to the embodiment of the invention, the material of the diaphragm c is not particularly limited, and a person skilled in the art can flexibly select the diaphragm according to actual needs, for example, the diaphragm c can be a PE film or a PP film, and the like, so that the diaphragm has better corrosion resistance and mechanical property.
It will be appreciated that, according to an embodiment of the present invention, the positive electrode tab b and the negative electrode tab a in the primary winding body 10 and the secondary winding body 20 are each of a continuous integral structure without cutting. In addition, it is also understood that the thickness of the first adhesive layer d1 and the thickness of the second adhesive layer d2 may be fixed values (as will be understood with reference to fig. 4 and 5) or may be tapered with an increase in the number of winding layers, respectively, and for example, according to a specific example of the present invention, the thickness of the first adhesive layer d1 may be fixed values and the thickness of the second adhesive layer d2 may be tapered with an increase in the number of winding layers, but considering that, on the basis of the determination of the thickness of the separator, a state in which the thickness of the adhesive layer is gradually changed may cause difficulty in winding the case or cause a large remaining space in the case after the winding body is mounted in the case, affecting the processability and electrochemical performance of the battery cell, it may be preferable in the present invention to make the thickness of the first adhesive layer d1 and the thickness of the second adhesive layer d2 be fixed values, respectively, independently. In addition, the first sub-diaphragm c1 and the second sub-diaphragm c2 may preferably be made of the same material, so that the consistency of the whole diaphragm can be further ensured.
According to some embodiments of the present invention, the first sub-separator c1 and the second sub-separator c2 may be continuous and uninterrupted, i.e. not cut, in the same layer of separator c. According to the invention, the continuous winding body and the two-section winding body are formed simultaneously by selecting the diaphragm which is not cut off, so that the continuity and the stability of the whole winding body can be ensured, and the probability that the first sub-diaphragm c1 and the second sub-diaphragm c2 are possibly in a liquid shortage and/or the ion transmission path is prolonged at the junction and the risk that the electrochemical performance of the battery is influenced can be obviously reduced.
According to further embodiments of the present invention, it is understood with reference to fig. 4 that, in the same layer of the separator c, the first sub-separator c1 and the second sub-separator c2 may be bonded together, that is, the same layer of the separator c may be formed by splicing two sections of the sub-separator. Compared with the method that the adhesive layer is arranged on a part of the area on the same diaphragm or two adhesive layers with different thicknesses are arranged on the same diaphragm at the same time, the method is more beneficial to actual operation, reduces preparation process difficulty and can better control the thickness of the adhesive layer and the thickness of the diaphragm in different areas by independently performing (gluing) operation on the two sections of sub-diaphragms and then splicing the sub-diaphragms, so that the problems of expansion and wrinkling of the coiled battery cell negative electrode sheet are more beneficial to be solved in a targeted manner.
According to the embodiment of the present invention, the connection manner of the first sub-separator c1 and the second sub-separator c2 is not particularly limited, and a person skilled in the art can flexibly select the connection manner according to actual needs, for example, the connection manner may be achieved by an adhesive layer or by hot melt connection. The inventors found that the problem of liquid shortage, the problem of lithium precipitation due to lengthening of an ion transmission path or uneven insertion of lithium ions into a pole piece, and the like are easily caused by the increase of the thickness of the separator, and the problem of lithium precipitation is easily caused by the fact that the thickness of the separator is increased.
According to the embodiment of the present invention, as will be understood from fig. 2 and fig. 6, the first sub-separator c1 and the second sub-separator c2 may be overlapped and bonded, and the width w of the overlapped area may be 2-5 mm, for example, 2.5mm, 3mm, 3.5mm, 4mm or 4.5mm, etc., and the inventor finds that if the width of the overlapped area is too small, it is difficult to ensure the bonding strength between the two, and if the width of the overlapped area is too large, the risk that the battery cell lacks liquid, the charging and discharging efficiency is affected due to the lengthening of the ion transmission path, and the problems such as lithium precipitation are significantly increased, and the negative effect is caused by the foregoing, and in the present invention, by controlling the width of the overlapped area to be in the foregoing range, the negative effect that the bonding area may have on the electrochemical performance of the battery can be further reduced on the basis of ensuring the good bonding strength between the first sub-separator and the second sub-separator. Wherein the winding direction shown in fig. 2 is clockwise.
According to some specific embodiments of the present invention, the hot-melt connection between the first sub-diaphragm c1 and the second sub-diaphragm c2 may be completed by performing a hot-press treatment on the connection portion between the first sub-diaphragm c1 and the second sub-diaphragm c2, so that the welding between the first sub-diaphragm c1 and the second sub-diaphragm c2 is facilitated, an integrated bonding effect is achieved, the bonding strength between the first sub-diaphragm and the second sub-diaphragm is ensured, and the flatness of the bonding (overlapping) area between the first sub-diaphragm and the second sub-diaphragm is improved. Further, the temperature of the hot press treatment may be 250 to 300 ℃, for example, 260 ℃, 270 ℃, 280 ℃, 290 ℃ or the like; the pressure of the heat press treatment may be 3000 to 5000kgf, and may be 3200kgf, 3400kgf, 3600kgf, 3800kgf, 4000kgf, 4200kgf, 4400kgf, 4600kgf, 4800kgf, or the like, for example; the time can be 5-10 s, for example, can be 6s or 8s, etc., the melting point of the diaphragm selected in the current battery field is usually not more than 200 ℃, for example, the melting point of PE is about 112 ℃, the melting point of PP is about 165 ℃, the temperature, pressure and time of hot pressing treatment are controlled to be respectively in the ranges, the first sub-diaphragm and the second sub-diaphragm can be ensured to achieve better integrated bonding effect, the bonding area of the first sub-diaphragm and the second sub-diaphragm can be ensured to have better flatness and lower thickness, and the risks of uneven bonding area or obviously increased thickness and further generated battery core liquid shortage, lithium precipitation, etc. caused by warping of the connecting area are avoided.
It will be appreciated that, according to embodiments of the present invention, the wound cell of the present invention may be used as both a cylindrical cell and a prismatic cell, and referring to fig. 1, it is understood that when the wound cell is used as a prismatic cell, the wound body 100 may include a planar region 30 and a bent region 40 (i.e., a corner region), and that in order to further reduce the adverse effect that the thickness and flatness of the overlapped connection region of the first and second sub-separators may have on the cell, it may be preferable to provide the overlapped region where the first and second sub-separators c1 and c2 are connected at the bent region.
According to the embodiment of the present invention, as will be understood from fig. 2 and 6, the thickness difference between the thickness of the overlapped area and the first sub-separator c1 and the thickness difference between the thickness of the overlapped area and the second sub-separator c2 may be not more than 10 μm, and considering that the thickness of the separator is typically 10-13 μm, the thickness of the adhesive layer disposed toward the negative electrode sheet of the separator in the existing wound battery is typically 1-3 μm (after rolling), by controlling the thickness difference between the thickness of the overlapped area and the first sub-separator and the thickness difference between the thickness of the overlapped area and the second sub-separator to be not more than 10 μm, the risk of the problems of cell shortage, the influence of charge and discharge efficiency and lithium precipitation due to the lengthening of the ion transmission path, and the negative influence caused by the foregoing problems may be further reduced, and thus the negative influence of the adhesive area on the electrochemical performance of the battery may be further reduced on the basis of having a good adhesive strength between the two sub-separators.
According to an embodiment of the present application, as understood in conjunction with fig. 2 and 7, in the overlapping region, the edge shape of the first sub-diaphragm c1 and the edge shape of the second sub-diaphragm c2 are not particularly limited, and may be flexibly selected according to actual needs by those skilled in the art, for example, the edge of the first sub-diaphragm c1 and the edge of the second sub-diaphragm c2 may be respectively and independently linear, zigzag, wavy, or the like in the width direction of the diaphragm.
According to an embodiment of the present application, as understood with reference to fig. 8, considering that the overlapping region of the first and second sub-separators c1 and c2 is liable to have a problem of liquid shortage due to an increase in thickness, a problem of lithium precipitation due to an increase in thickness of the separator, or a problem of lithium ion being unable to uniformly intercalate into the electrode sheet, at least one of the positive electrode sheet b and the negative electrode sheet a may be provided with a thickness reduction region S corresponding to the overlapping region on a side facing the separator c, wherein the problem of liquid shortage and the problem of the increase in the ion transmission path may be effectively avoided by providing the thickness reduction region. Further, the total thickness of the thickness reduction region S may be 1 to 1.2 times the thickness of the overlapping region, for example, may be 1.05 times, 1.1 times, 1.15 times, or the like, the width of the thickness reduction region S may be not less than the width w of the overlapping region, preferably 1 to 1.2 times the width of the overlapping region, and the inventors found that if the thicknesses of the active material layers on both sides of the same pole piece are inconsistent, a problem of lithium precipitation may occur during charge and discharge. More preferably, the thickness reducing areas are arranged on the positive plate b and the negative plate a, the thickness of the thickness reducing areas on the positive plate b is 0.7 plus or minus 0.1 times of the thickness of the overlapping area, the thickness of the thickness reducing areas on the negative plate a is 0.3 plus or minus 0.1 times of the thickness of the overlapping area, and the thickness of the positive plate is usually about 1.5 times of the thickness of the negative plate in the conventional battery core.
According to the embodiment of the present invention, the thickness of the first sub-diaphragm c1 and the thickness of the second sub-diaphragm c2 may be equal or unequal. When the thickness of the two materials is equal, only a diaphragm with one specification is needed to be provided.
According to the embodiment of the present invention, as understood with reference to fig. 9, when the adhesive layer is not disposed on the side of the second sub-separator c2 contacting the negative electrode sheet a, the total thickness of the first sub-separator c1 and the first adhesive layer d1 may be equal to the thickness of the second sub-separator c2, and at this time, the thickness of the same separator on the whole may be ensured to be unchanged, so that the problem that the winding body is difficult to be put into the case or the remaining space in the battery cell case after the winding body is put into the case is larger due to the thickness change of the separator can be effectively avoided.
According to the embodiment of the invention, as understood by referring to fig. 10, the total thickness of the first sub-diaphragm c1 and the first adhesive layer d1 may be equal to the total thickness of the second sub-diaphragm c2 and the second adhesive layer d2, at this time, the thickness of the same diaphragm on the whole may be ensured to be unchanged, and the problem that the winding body is difficult to be put into the shell or the residual space in the cell shell after the winding body is put into the shell is larger due to the change of the thickness of the diaphragm can be effectively avoided.
It will be appreciated that, according to embodiments of the present invention, the wound cell may further include a cell housing for accommodating the wound body 100, wherein the specific type of the cell housing is not particularly limited, and those skilled in the art may flexibly select, for example, a square cell housing or the like according to actual needs. In addition, it is understood that the side of the separator facing the positive plate can be provided with an adhesive layer, preferably in a section of winding body, so that the positive plate and the negative plate can be tightly adhered together through the separator after hot pressing, and the expansion and fold problems of the negative plate of the inner ring can be further improved.
Based on the same inventive concept, according to a further aspect of the present invention, a method of preparing a wound cell is presented. As understood in connection with fig. 1-5, the method, according to an embodiment of the present invention, includes: winding with a winding unit to obtain a wound body 100, wherein: the winding unit comprises a positive electrode sheet b, a negative electrode sheet a and two layers of diaphragms c, the winding body 100 comprises a first winding body 10 and a second winding body 20, and the second winding body 20 is formed by continuously winding on the first winding body 10; in the at least one separator c, a first sub-separator c1 is used as a part located in the first-stage winding body 10, a second sub-separator c2 is used as a part located in the second-stage winding body 20, and a first adhesive layer d1 is arranged on one side of the first sub-separator c1, which is contacted with the negative electrode sheet a, wherein: the side of the second sub-separator c2, which is in contact with the negative electrode sheet a, is not provided with an adhesive layer; alternatively, the second sub separator c2 is provided with a second adhesive layer d2 on a side contacting the negative electrode sheet a, and the thickness of the second adhesive layer d2 is smaller than that of the first adhesive layer d 1. Compared with the prior art, the method has the advantages that the adhesive layer is formed on the separator of the first winding body, or the thickness of the adhesive layer formed on the separator of the second winding body is smaller than that of the separator of the first winding body, so that the problems of expansion and wrinkling of the negative electrode plate of the battery cell can be remarkably improved, the lithium precipitation risk of the battery cell is reduced, the safety performance of the battery cell is improved, the electrochemical performance of the battery cell is prevented from being reduced or failure is prevented in advance, and the cost of the separator and the battery cell can be reduced. In addition, it should be further noted that the method for preparing the winding electric core and the winding electric core are provided based on the same inventive concept, and all the features and effects described for the winding electric core are also applicable to the method for preparing the winding electric core, which is not described in detail herein.
According to an embodiment of the present invention, before the winding, it may further include: the hot-pressing treatment is performed on the connection part of the first sub-diaphragm c1 and the second sub-diaphragm c2, so that the hot-melting connection of the first sub-diaphragm and the second sub-diaphragm is realized, wherein the temperature, the pressure and the time of the hot-pressing treatment and the beneficial effects of controlling the corresponding hot-pressing treatment conditions are described in detail in the previous parts, and are not repeated here. In addition, if the width of the overlapping area of the hot-melt connection of the separator after the hot-press treatment becomes larger, the method may further include a cutting treatment, and the width of the separator in the overlapping area is kept consistent with other areas.
According to an embodiment of the present invention, after the winding is completed, the method may further include: the winding body is subjected to hot press molding, so that on one hand, the full contact of the negative plate and the bonding layer can be facilitated, the binding effect of the diaphragm on the negative plate is improved, and the problems of expansion and wrinkling of the negative plate are solved; on the other hand, the roll may be pressed into a desired shape according to actual needs, for example, into the shape shown in fig. 1. Further, the temperature of the hot press molding may be 85 to 110 ℃, for example, 90 ℃, 95 ℃, 100 ℃, 105 ℃, or the like; the pressure may be 8000 to 11000kgf, for example, 8500kgf, 9000kgf, 9500kgf, 10000kgf, 10500kgf, or the like; the time can be not less than 60s, for example, can be 1.5min, 2min or 5min, and the like, and the temperature, the pressure and the time of hot press molding are respectively in the ranges, so that the binding effect of the bonding layer on the expansion and the fold of the anode plate can be further ensured on the basis of not influencing the stability of the diaphragm, the winding body structure with the expected shape can be obtained, and the assembly of the shell is facilitated.
It should be noted that, the method for preparing the winding electric core and the winding electric core are provided based on the same inventive concept, and all the features and effects described for the winding electric core are also applicable to the method for preparing the winding electric core, which is not described in detail herein.
According to still another aspect of the present invention, a battery module is provided. According to an embodiment of the present invention, the battery module includes the wound cell described above or a wound cell manufactured by the method of manufacturing a wound cell described above. It should be noted that all the features and effects described with respect to the above-described winding battery cell and the above-described method for preparing a winding battery cell are also applicable to the battery module, and are not described herein. In general, the battery module has good volume stability and electrochemical stability, high safety, longer service life and lower cost.
According to yet another aspect of the present invention, a battery pack is provided. According to an embodiment of the present invention, the battery module includes the aforementioned battery module. It should be noted that all the features and effects described for the battery module are equally applicable to the battery pack, and are not described herein.
According to yet another aspect of the present invention, a powered device is presented. According to an embodiment of the invention, the electric equipment comprises the battery pack, the battery module, the winding battery core manufactured by the method for manufacturing the winding battery core, or the winding battery core. It should be noted that all the features and effects described for the battery pack, the battery module, the method for preparing the winding electric core and the winding electric core are applicable to the electric device, and are not described herein. Overall, the stability of the consumer in use is better and the safety risk is lower. In addition, it should be noted that the specific type of the electric equipment is not particularly limited, and those skilled in the art can flexibly select according to actual needs, for example, the electric equipment can be a vehicle, an electronic device, a household appliance, or the like.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims (16)

1. A coiled electrical cell, comprising: the winding unit of the winding body comprises a positive plate, a negative plate and two layers of diaphragms, the winding body is limited with a first winding body and a second winding body, the second winding body is formed by continuously winding on the first winding body, and the ratio of the winding number of the first winding body to the winding number of the second winding body is 0.2-2; at least one layer of separator is characterized in that a part in the first section of winding body is used as a first sub-separator, a part in the second section of winding body is used as a second sub-separator, and a first adhesive layer is arranged on one side of the first sub-separator, which is in contact with the negative electrode sheet, wherein:
an adhesive layer is not arranged on one side of the second sub-diaphragm, which is contacted with the negative electrode plate; or, a second adhesive layer is arranged on one side of the second sub-separator, which is in contact with the negative electrode plate, and the thickness of the second adhesive layer is smaller than that of the first adhesive layer;
In the same layer of the diaphragm, the first sub-diaphragm and the second sub-diaphragm are of continuous and uninterrupted structures; alternatively, the first sub-membrane is adhesively connected to the second sub-membrane.
2. The winding cell of claim 1, wherein the ratio of the number of windings of the first winding to the number of windings of the second winding is 0.5-1.
3. The wound cell of claim 1 or 2, wherein the first adhesive layer and the second adhesive layer each independently comprise a polymeric adhesive.
4. A coiled electrical cell according to claim 3, wherein at least one of the following conditions is met:
the polymer binder includes at least one selected from polyvinylidene fluoride, polyvinyl alcohol and carboxymethyl cellulose;
inorganic particles are also dispersed in the first binder layer;
inorganic particles are also dispersed in the second binder layer.
5. The wound cell of claim 4, wherein the inorganic particles in the first binder layer and the inorganic particles in the second binder layer each independently comprise a material selected from boehmite, alumina, zrO 2 And LLZTO; and/or the number of the groups of groups,
in the first binder layer and the second binder layer, the mass ratio of the inorganic particles to the polymer binder is (0.1 to 9.9): (9.9 to 0.1).
6. The wound cell of claim 1 or 5, wherein the separator is a PE film or PP film.
7. The wound cell of claim 1, wherein the first sub-membrane is thermally fused to the second sub-membrane; and/or the number of the groups of groups,
the first sub-diaphragms are connected with the second sub-diaphragms in an overlapping and bonding mode, and the width of an overlapping area is 2-5 mm.
8. The wound cell of claim 7, wherein at least one of the following conditions is satisfied:
the hot melt connection is completed by carrying out hot pressing treatment on the connection part of the first sub-diaphragm and the second sub-diaphragm, wherein the temperature of the hot pressing treatment is 250-300 ℃, the pressure is 3000-5000 kgf, and the time is 5-10 s;
the thickness of the overlapping region is not more than 10 μm from the thickness difference of the first sub-membrane and the thickness difference of the second sub-membrane;
in the overlapping region, the edges of the first sub-membrane and the edges of the second sub-membrane are respectively and independently linear, zigzag or wavy along the width direction of the membrane;
The winding body comprises a plane area and a bending area, and the overlapped area is positioned in the bending area;
at least one of the positive electrode sheet and the negative electrode sheet is provided with a thickness reduction region corresponding to the overlap region on a side facing the separator.
9. The winding cell according to claim 8, wherein a total reduced thickness of the thickness reduced region is 1 to 1.2 times a thickness of the overlap region, a width of the reduced region being not smaller than a width of the overlap region; and/or the number of the groups of groups,
the thickness reduction areas are arranged on the positive plate and the negative plate, the thickness reduction thickness of the thickness reduction area on the positive plate is (0.7 plus or minus 0.1) times the thickness of the overlapping area, and the thickness reduction thickness of the thickness reduction area on the negative plate is (0.3 plus or minus 0.1) times the thickness of the overlapping area.
10. The winding cell according to claim 1 or 9, characterized in that one of the following conditions is fulfilled:
the thickness of the first sub-diaphragm is equal to that of the second sub-diaphragm;
an adhesive layer is not arranged on one side of the second sub-diaphragm, which is in contact with the negative electrode plate, and the total thickness of the first sub-diaphragm and the first adhesive layer is equal to the thickness of the second sub-diaphragm;
The total thickness of the first sub-membrane and the first adhesive layer is equal to the total thickness of the second sub-membrane and the second adhesive layer.
11. A method of making a wound cell comprising: winding by a winding unit to obtain a wound body, wherein:
the winding unit comprises a positive plate, a negative plate and two layers of diaphragms, wherein the winding body comprises a first winding body and a second winding body, the second winding body is formed by continuously winding on the first winding body, and the ratio of the winding number of the first winding body to the winding number of the second winding body is 0.2-2; at least one layer of separator is characterized in that a part in the first section of winding body is used as a first sub-separator, a part in the second section of winding body is used as a second sub-separator, and a first adhesive layer is arranged on one side of the first sub-separator, which is in contact with the negative electrode sheet, wherein:
an adhesive layer is not arranged on one side of the second sub-diaphragm, which is contacted with the negative electrode plate; or, a second adhesive layer is arranged on one side of the second sub-separator, which is in contact with the negative electrode plate, and the thickness of the second adhesive layer is smaller than that of the first adhesive layer;
in the same layer of the diaphragm, the first sub-diaphragm and the second sub-diaphragm are of continuous and uninterrupted structures; alternatively, the first sub-membrane is adhesively connected to the second sub-membrane.
12. The method of claim 11, wherein the first sub-membrane is adhesively attached to the second sub-membrane, further comprising, prior to the winding:
and carrying out hot pressing treatment on the joint of the first sub-diaphragm and the second sub-diaphragm, thereby realizing hot melting connection of the first sub-diaphragm and the second sub-diaphragm.
13. The method according to claim 11 or 12, characterized in that after the winding is completed, it further comprises: and (3) performing hot press forming on the winding body, wherein the temperature of the hot press forming is 85-110 ℃, the pressure is 8000-11000 kgf, and the time is not less than 60s.
14. A battery module comprising a wound cell according to any one of claims 1 to 10 or a wound cell made by the method of any one of claims 11 to 13.
15. A battery pack comprising the battery module of claim 14.
16. An electrical device, comprising the battery pack of claim 15, or the battery module of claim 14, or the wound cell manufactured by the method of any one of claims 11 to 13, or the wound cell of any one of claims 1 to 10.
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CN201345383Y (en) * 2008-08-26 2009-11-11 比亚迪股份有限公司 Lithium ion secondary battery
JP2013045636A (en) * 2011-08-24 2013-03-04 Hitachi Vehicle Energy Ltd Square battery and manufacturing method therefor
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