Laminated cells, secondary batteries, battery modules, battery packs and electrical devices

Abstract

The present application provides a laminated battery cell, a secondary battery, a battery module, a battery pack and an electrical device, wherein the laminated battery cell comprises a first pole piece, at least one second pole piece, a separation film and an insulating layer. The first pole piece is bent back and forth and stacked to form at least two first pole piece layers. Each second pole piece is arranged between two adjacent first pole piece layers. The separation film is arranged between the first pole piece and the second pole piece to isolate the first pole piece from the second pole piece. The insulating layer is arranged between the current collector surface on the inner side of the bending section of the first pole piece and the end face of the second pole piece close to the inner side of the bending section to prevent the current collector at the bending section of the first pole piece from being electrically connected to the current collector at the bending section of the second pole piece close to the bending section. Among them, one of the first pole piece and the second pole piece is a positive pole piece, and the other is a negative pole piece. The above-mentioned laminated battery cell can effectively improve the safety performance of the battery.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a laminated battery cell, a secondary battery, a battery module, a battery pack and an electrical device. Background Art

[0002] At present, the battery cells are mainly made by lamination and winding processes. Laminated cells have been widely used due to their many advantages, such as high rate and high energy density. However, during the charging and discharging process of the battery, the laminated cells are prone to short circuits, resulting in safety hazards of the battery. Summary of the invention

[0003] The present application provides a laminated battery cell, a secondary battery, a battery module, a battery pack and an electrical device, which can effectively improve the safety performance of the battery.

[0004] In a first aspect, the present application provides a laminated battery cell, comprising:

[0005] A first pole piece, the first pole piece is reciprocatingly bent and stacked to form at least two first pole piece layers;

[0006] At least one second pole piece, each second pole piece is disposed between two adjacent first pole piece layers;

[0007] An isolation film is disposed between the first pole piece and the second pole piece to isolate the first pole piece from the second pole piece;

[0008] The insulating layer is disposed between the current collector surface on the inner side of the bending section of the first pole piece and the end surface of the second pole piece close to the inner side of the bending section to prevent the current collector at the bending section of the first pole piece from being electrically connected to the current collector at the bending section of the second pole piece close to the bending section.

[0009] Among them, one of the first pole piece and the second pole piece is a positive pole piece, and the other is a negative pole piece.

[0010] In the technical solution of the present application, an insulating layer is arranged between the collector surface on the inner side of the bending section of the first pole piece and the end face of the second pole piece close to the inner side of the bending section. The insulating layer can prevent the current collector at the bending section of the first pole piece from contacting the current collector at the bending section of the second pole piece close to the bending section, thereby avoiding the occurrence of battery short circuit and improving the safety performance of the battery. In addition, as the battery charge and discharge cycle proceeds, lithium dendrites connecting the first pole piece collector and the second pole piece collector are easily formed in the area corresponding to the bending section. The lithium dendrites can electrically connect the first pole piece and the second pole piece to form a short circuit, and the provision of the insulating layer can prevent the formed lithium dendrites from electrically connecting the first pole piece collector and the second pole piece collector, thereby improving the safety performance of the battery.

[0011] In some embodiments of the present application, the insulating layer includes a first insulating layer, and the first insulating layer is arranged on the current collector surface inside the bending section of the first pole piece. By arranging the first insulating layer on the current collector surface inside the bending section of the first pole piece, the manufacturing difficulty of the battery cell can be reduced, the production efficiency can be improved, and the manufacturing cost can be reduced.

[0012] In some embodiments of the present application, the insulating layer includes a second insulating layer, and the second insulating layer is arranged on the end face of the second pole piece close to the inner side of the bending section. During the battery charge and discharge cycle, lithium dendrites connecting the first pole piece current collector and the second pole piece current collector are easily formed in the area corresponding to the bending section. The lithium dendrites can electrically connect the first pole piece and the second pole piece to form a short circuit, and the second insulating layer can prevent the formed lithium dendrites from electrically connecting the first pole piece current collector and the second pole piece current collector, thereby avoiding the phenomenon that the first pole piece and the second pole piece are electrically connected to form a short circuit.

[0013] In some embodiments of the present application, the insulating layer includes a third insulating layer, and the third insulating layer is disposed on the surface of the isolation film facing the inner side of the bending section. The third insulating layer can prevent the current collector of the first pole piece and the current collector of the second pole piece from being electrically connected to form a short circuit, and can prevent lithium dendrites from piercing the isolation film.

[0014] In some embodiments of the present application, the insulating layer is a metal oxide layer; optionally, the metal oxide in the metal oxide layer is selected from at least one of aluminum oxide, magnesium oxide and nickel oxide. In the technical solution of the present application, the metal oxide layer can not only play an insulating role, but also prevent the current collector from being damaged, or oxidation, corrosion and the like, significantly improving the long-term reliability and service life of the current collector. In addition, the metal oxide layer is arranged on the surface of the current collector or the isolation membrane and is not easy to fall off, thereby further improving the safety performance of the battery.

[0015] In some embodiments of the present application, the thickness of the insulating layer is 8 μm to 20 μm. The thickness of the insulating layer is set within this range, which is conducive to processing the first pole piece, the isolation film and the second pole piece.

[0016] In some embodiments of the present application, the bending section includes a first bending section having a first bending surface, a second bending section having a second bending surface, and a third bending section having a third bending surface, the two ends of the second bending section are respectively vertically connected to the first bending section and the second bending section, and the first bending surface, the second bending surface, and the third bending surface are connected to form the bending surface of the bending section. By providing the first bending section, the second bending section, and the third bending section, the processing difficulty of the first pole piece can be further reduced.

[0017] In some embodiments of the present application, the total length L of the first bending segment, the second bending segment and the third bending segment satisfies: 0.3mm≤L≤0.7mm.

[0018] In some embodiments of the present application, the length of the second bending section is 0.1 mm to 0.3 mm.

[0019] In a second aspect, the present application provides a secondary battery, which includes the laminated battery cell in any of the above embodiments.

[0020] In the technical solution of the present application, since the secondary battery includes the laminated battery cell in the above embodiment, the secondary battery also has the beneficial effects of the laminated battery cell.

[0021] In a third aspect, the present application provides a battery module, comprising the secondary battery in the above embodiment.

[0022] In the technical solution of the present application, since the battery module includes the secondary battery in the above embodiment, the battery module also has the beneficial effects of the above secondary battery.

[0023] In a fourth aspect, the present application provides a battery pack, including the battery pack in the above-mentioned embodiment.

[0024] In the technical solution of the present application, since the battery pack includes the battery module in the above embodiment, the battery pack also has the beneficial effects of the above battery module.

[0025] In a fifth aspect, the present application provides an electrical device comprising at least one of the secondary battery, battery module, and battery pack in the above-mentioned embodiments.

[0026] In the technical solution of the present application, since the electrical device includes the secondary battery, battery module or battery pack in the above embodiments, the battery pack also has the beneficial effects of the above secondary battery, battery module or battery pack.

[0027] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0029] Figure 1 A schematic diagram of a cross-sectional structure of a battery cell according to some embodiments of the present application;

[0030] Figure 2 A schematic diagram of a cross-sectional structure of a battery cell according to some embodiments of the present application;

[0031] Figure 3 Schematic diagram of the cross-sectional structure of the battery cells of other embodiments of the present application;

[0032] Figure 4 Schematic diagram of the cross-sectional structure of the battery cell in Comparative Example 1;

[0033] Figure 5 Schematic diagram of the cross-sectional structure of the battery cell in Comparative Example 2;

[0034] Figure 6 A three-dimensional diagram of a secondary battery according to some embodiments of the present application;

[0035] Figure 7 A schematic diagram of an exploded structure of a secondary battery according to some embodiments of the present application;

[0036] Figure 8 A schematic diagram of a battery module according to some embodiments of the present application;

[0037] Fig. 9 A schematic diagram of a battery pack according to some embodiments of the present application;

[0038] Fig.10 A schematic diagram of an exploded structure of a battery pack according to some embodiments of the present application;

[0039] Fig.11 Schematic diagram of an electrical device according to some embodiments of the present application.

[0040] The reference numerals in the specific implementation manner are as follows:

[0041] 11-First pole piece

[0042] 111- a first current collector;

[0043] 112- first active layer;

[0044] 12- second pole piece;

[0045] 121- second collector;

[0046] 122- second active layer;

[0047] 13- isolation film;

[0048] 14- insulation layer;

[0049] 15-Lithium dendrites.

[0050] 20- Secondary battery;

[0051] 21-housing;

[0052] 22-electrode assembly;

[0053] 23-cover assembly;

[0054] 30-battery module;

[0055] 40-battery pack;

[0056] 41-first box;

[0057] 42- second box;

[0058] 50- Electric cars. DETAILED DESCRIPTION

[0059] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0061] In the description of this application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0062] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0063] In the description of this application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0064] In the description of this application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).

[0065] In the description of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0066] In the description of this application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0067] The inventors of the present invention have noticed that the stacked cell in the battery may have a problem that the current collector of the first pole piece and the current collector of the second pole piece are in contact at the bending section formed by the reciprocating bending of a pole piece, which is prone to short circuit. In addition, during the charge and discharge cycle of the battery, the area corresponding to the bending section of the stacked cell is prone to produce lithium dendrites. The lithium dendrites have sharp corners and are also conductive, so they can pierce the isolation membrane to electrically connect the current collector of the first pole piece and the current collector of the second pole piece to form a short circuit, which may cause safety risks such as combustion during the use of the battery.

[0068] In order to solve the problem that short circuits are easily formed in the bending section of stacked battery cells, the inventors have designed a battery cell after in-depth research, in which an insulating layer is set in the space area corresponding to the inner side of the bending section of the battery cell, so that no electrical connection can occur on the inner side of the bending section of the battery cell, and thus no short circuit can be formed, thereby achieving the purpose of improving the safety performance of the battery.

[0069] For the convenience of description, the following embodiments are described by taking the laminated battery cell structure of some embodiments of the present application as an example.

[0070] Reference Figure 1 The present application provides a laminated battery cell, comprising a first pole piece 11, at least one second pole piece 12, an isolation film 13 and an insulating layer 14. In the embodiment provided in the present application, the first pole piece 11 is bent and stacked back and forth to form at least two first pole piece layers. Each second pole piece 12 is arranged between two adjacent first pole piece layers. The isolation film 13 is arranged between the first pole piece 11 and the second pole piece 12 to isolate the first pole piece 11 from the second pole piece 12. The insulating layer 14 is arranged between the current collector surface on the inner side of the bending section of the first pole piece 11 and the end face of the second pole piece 12 close to the inner side of the bending section to prevent the current collector at the bending section of the first pole piece 11 from being electrically connected to the current collector at the bending section of the second pole piece 12. Among them, one of the first pole piece 11 and the second pole piece 12 is a positive pole piece, and the other is a negative pole piece. It can be understood that the pole piece includes a current collector and an active layer arranged on the surface of the current collector.

[0071] In the technical solution of the present application, an insulating layer is arranged between the collector surface on the inner side of the bending section of the first pole piece and the end face of the second pole piece close to the inner side of the bending section. The insulating layer can prevent the current collector at the bending section of the first pole piece from contacting the current collector at the bending section of the second pole piece close to the bending section, thereby avoiding the occurrence of battery short circuit and improving the safety performance of the battery. In addition, as the battery charge and discharge cycle proceeds, lithium dendrites connecting the first pole piece collector and the second pole piece collector are easily formed in the area corresponding to the bending section of the first pole piece. The lithium dendrites can electrically connect the first pole piece and the second pole piece to form a short circuit, and the provision of the insulating layer can prevent the formed lithium dendrites from electrically connecting the first pole piece collector and the second pole piece collector, thereby improving the safety performance of the battery.

[0072] Continue to refer to Figure 1 The first pole piece 11 includes a first current collector 111 and a first active layer 112 disposed on the surface of the first current collector 111. In some embodiments of the present application, the first active layer 112 is disposed on both the first surface and the second surface opposite to each other on the first current collector 111. The present application does not impose any special restrictions on the first current collector 111 and the first active layer 112, which may be current collectors and active layers well known to those skilled in the art.

[0073] Specifically, when the first electrode sheet 11 is a negative electrode sheet, the first current collector 111 is a negative electrode current collector, and the first active layer 112 is a negative electrode active layer. The negative electrode current collector may be made of a metal foil or a porous metal plate. For example, the material of the negative electrode current collector may be, but is not limited to, a foil or a porous plate of a metal such as copper, nickel, titanium or iron or an alloy thereof. Further, in some specific embodiments of the present application, the negative electrode current collector is made of copper foil.

[0074] The negative electrode active material in the negative electrode active layer can be, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microbeads, nanocarbon, carbon fiber, elemental silicon, silicon oxide compounds, silicon carbon composites, silicon alloys, elemental tin, tin oxide compounds, tin carbon composites, tin alloys and lithium titanate.

[0075] In some specific embodiments of the present application, the negative electrode active material in the negative electrode active layer includes a carbon-based negative electrode active material. Exemplarily, the carbon-based negative electrode active material may be, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microspheres, nanocarbon and carbon fiber. Further, the above-mentioned negative electrode active material includes one or more of natural graphite and artificial graphite.

[0076] In addition, the negative electrode active layer may also include a conductive agent and a binder. The present application does not specifically limit the types of conductive agents and binders in the negative electrode active layer 2, and can be selected according to actual needs. Exemplarily, the conductive agent may be, but is not limited to, one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers; the binder may be, but is not limited to, one or more of styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), water-based acrylic resin and carboxymethyl cellulose (CMC).

[0077] Furthermore, the negative electrode active layer may further include a thickener, such as carboxymethyl cellulose (CMC).

[0078] Continue to refer to Figure 1 The second pole piece 12 includes a second current collector 121 and a second active layer disposed on the surface of the second current collector 121. In some embodiments of the present application, a second active layer 122 is disposed on both the first surface and the second surface opposite to each other on the second current collector 121. The present application does not impose any special restrictions on the second current collector 121 and the second active layer 122, which may be current collectors and active layers well known to those skilled in the art.

[0079] Specifically, when the first electrode sheet 11 is a negative electrode sheet, the second electrode sheet 12 is a positive electrode sheet. In this case, the second current collector 121 is a positive electrode current collector, and the second active layer 122 is a positive electrode active layer. Among them, the positive electrode current collector can be made of materials such as metal foil or porous metal plate. Exemplarily, the material of the positive electrode current collector can be but is not limited to a foil or porous plate of a metal such as copper, nickel, titanium or silver or an alloy thereof. Further, in some specific embodiments of the present application, the positive electrode current collector is made of aluminum foil.

[0080] In some embodiments of the present application, the positive electrode active material in the positive electrode active layer can be selected from materials that can embed and extract lithium ions. Exemplarily, the positive electrode active material can be a lithium transition metal composite oxide, wherein the transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce and Mg.

[0081] Furthermore, the lithium transition metal composite oxide may be, but is not limited to, LiMn 2 O 4 、LiNiO 2 、LiCoO 2 One or more of .

[0082] In addition, the lithium transition metal composite oxide may be doped with one or more of other transition metals, non-transition metals and non-metals.

[0083] In some embodiments of the present application, the positive electrode active layer may further include a conductive agent and a binder. The present application does not specifically limit the types of the conductive agent and the binder in the positive electrode active layer, and they can be selected according to actual needs.

[0084] Exemplarily, the conductive agent may be, but is not limited to, one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers; the binder may be, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorine-containing acrylic resin and polyvinyl alcohol (PVA).

[0085] In some embodiments of the present application, the first electrode 11 is a negative electrode, and the second electrode 12 is a positive electrode, or the first electrode 11 is a positive electrode, and the second electrode 12 is a negative electrode. The type of electrode can be selected according to actual needs.

[0086] It should be noted here that the first electrode sheet 11 in the laminated battery cell needs to be bent back and forth and stacked, so the active layer is usually not arranged on the inner side of the bending section, that is, the first current collector 111 on the inner side of the bending section is exposed to the outside, so as to prevent the first active layer 112 of the first electrode sheet 11 from falling off during the bending process, and the first electrode sheet 11 and the second electrode sheet 12 are easily electrically connected to form a short circuit, thereby causing safety risks to the battery during use.

[0087] In the embodiments of the present application, there is no particular restriction on the material of the isolation membrane 13, and any known porous structure isolation membrane with electrochemical stability and chemical stability can be selected, such as single-layer or multi-layer films of one or more of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP) and polyvinylidene fluoride (PVDF).

[0088] Continue to refer to Figure 1 In some embodiments of the present application, the insulating layer 14 includes a first insulating layer, which is disposed on the current collector surface inside the bending section of the first pole piece 11. As described above, the current collector surface inside the bending section of the first pole piece 11 is not provided with an active layer. Therefore, the first insulating layer is disposed here, which can better isolate the current collector of the first pole piece 11 from being electrically connected to the current collector of the second pole piece 12. Moreover, by disposing the first insulating layer on the current collector surface inside the bending section of the first pole piece 11, the manufacturing difficulty of the battery cell can be reduced, the production efficiency can be improved, and the manufacturing cost can be reduced.

[0089] Specifically, after the first pole piece 11 is marked, an insulating material is sprayed on the exposed surface of the first current collector 111 to form a first insulating layer.

[0090] In addition, in order to facilitate the reciprocating bending and stacking of the first pole piece 11 , in some embodiments of the present application, the thickness of the first insulating layer is less than the thickness of the first active layer 112 on the first pole piece 11 .

[0091] In some embodiments of the present application, the thickness of the first insulating layer is 8 μm to 20 μm. For example, the thickness of the first insulating layer may be, but is not limited to, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, and 20 μm. The thickness of the first insulating layer is set within this range, which is conducive to bending and other processing of the first pole piece 11.

[0092] In some embodiments of the present application, the first insulating layer is a metal oxide layer. On the one hand, the metal oxide layer can better isolate the current collector on the inner side of the bending section of the first pole piece 11 from being electrically connected to the current collector near the inner side of the bending section in the second pole piece 12. On the other hand, the metal oxide layer can also prevent the current collector from being damaged, or from oxidation, corrosion, and the like, thereby significantly improving the long-term reliability and service life of the current collector. In addition, the metal oxide layer is arranged on the surface of the current collector or the isolation membrane and is not easy to fall off, which can further improve the safety performance of the battery. In addition, the metal oxide layer also has high temperature resistance, thereby further improving the safety performance of the battery.

[0093] Furthermore, in some embodiments of the present application, the metal oxide in the metal oxide layer is selected from at least one of aluminum oxide, magnesium oxide and nickel oxide.

[0094] In some specific embodiments of the present application, the metal oxide in the metal oxide layer is selected from aluminum oxide.

[0095] In addition, the metal oxide layer may further include additives to further improve the adhesion, oxidation resistance or high temperature resistance of the metal oxide layer. Exemplarily, the additives may be binders.

[0096] Reference Figure 2 In some embodiments of the present application, the insulating layer 14 includes a second insulating layer, which is disposed on the end face of the second pole piece 12 close to the inner side of the bending section of the first pole piece 11. During the battery charge and discharge cycle, lithium dendrites 15 connecting the current collector of the first pole piece 11 and the current collector of the second pole piece 12 are easily formed in the area corresponding to the bending section of the first pole piece 11. The lithium dendrites 15 can electrically connect the first pole piece 11 and the second pole piece 12 to form a short circuit, and the second insulating layer can prevent the formed lithium dendrites 15 from electrically connecting the current collector of the first pole piece 11 and the current collector of the second pole piece 12, thereby avoiding the phenomenon that the first pole piece 11 and the second pole piece 12 are electrically connected to form a short circuit.

[0097] Specifically, after the second pole pieces 12 are punched, a plurality of second pole pieces 12 are stacked up, and insulating material is uniformly sprayed on the end surfaces of the second pole pieces 12 to form a second insulating coating to completely cover the end surfaces of the second pole pieces 12 .

[0098] In some embodiments of the present application, the thickness of the second insulating layer is 8μm to 20μm. By way of example, the thickness of the second insulating layer may be, but is not limited to, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, or 20μm.

[0099] In some embodiments of the present application, the width of the second insulating layer is greater than the width of the end surface of the second pole piece 12 close to the inner side of the bending section of the first pole piece 11 .

[0100] In some embodiments of the present application, the second insulating layer is a metal oxide layer. On the one hand, the metal oxide layer can better isolate the current collector on the inner side of the bending section of the first pole piece 11 from being electrically connected to the current collector on the inner side of the bending section in the second pole piece 12. On the other hand, the metal oxide layer can not only play an insulating role, but also prevent the current collector from being damaged, or from oxidation, corrosion and the like, thereby significantly improving the long-term reliability and service life of the current collector. In addition, the metal oxide layer is arranged on the surface of the current collector or the isolation membrane and is not easy to fall off, which can further improve the safety performance of the battery. In addition, the metal oxide layer also has high temperature resistance, thereby further improving the safety performance of the battery.

[0101] Furthermore, in some embodiments of the present application, the metal oxide in the metal oxide layer is selected from at least one of aluminum oxide, magnesium oxide and nickel oxide.

[0102] In some specific embodiments of the present application, the metal oxide in the metal oxide layer is selected from aluminum oxide.

[0103] In addition, the metal oxide layer may further include additives to further improve the adhesion, oxidation resistance or high temperature resistance of the metal oxide layer. Exemplarily, the additives may be binders.

[0104] Reference Figure 3 In some embodiments of the present application, the insulating layer 14 includes a third insulating layer, which is disposed on the surface of the isolation film 13 facing the inner side of the bending section of the first pole piece 11. The third insulating layer can prevent the current collector inside the bending section of the first pole piece 11 and the current collector near the bending section of the second pole piece 12 from being electrically connected to form a short circuit, and can prevent lithium dendrites from piercing the isolation film.

[0105] In other embodiments of the present application, the third insulating layer is disposed on the surface of the isolation film 13 away from the inner side of the bending section of the first pole piece 11, and the width of the third insulating layer is not less than the width of the collector end surface of the second pole piece 12 close to the inner side of the bending section. This can reduce the amount of insulating material used and reduce manufacturing costs.

[0106] Specifically, an insulating material is sprayed onto the surface of the isolation membrane on the inner side of the bending section close to the first pole piece 11 to form a third insulating layer, and the width of the third insulating layer is not less than the width of the collector surface on the inner side of the bending section of the first pole piece 11 or the width of the third insulating layer is not less than the width of the collector end face of the second pole piece 12 close to the inner side of the bending section.

[0107] In some embodiments of the present application, the width of the third insulating layer may be 0.7 mm to 1 mm.

[0108] In some embodiments of the present application, the thickness of the third insulating layer is 8μm-20μm. By way of example, the thickness of the second insulating layer may be, but is not limited to, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, or 20μm.

[0109] In some embodiments of the present application, the third insulating layer is a metal oxide layer. On the one hand, the metal oxide layer can better isolate the current collector on the inner side of the bending section of the first pole piece 11 from being electrically connected to the current collector near the inner side of the bending section in the second pole piece 12. On the other hand, the metal oxide layer can not only play an insulating role, but also prevent the current collector from being damaged, or from oxidation, corrosion and the like, thereby significantly improving the long-term reliability and service life of the current collector. In addition, the metal oxide layer is arranged on the surface of the current collector or the isolation membrane and is not easy to fall off, which can further improve the safety performance of the battery. In addition, the metal oxide layer also has high temperature resistance, thereby further improving the safety performance of the battery.

[0110] Furthermore, in some embodiments of the present application, the metal oxide in the metal oxide layer is selected from at least one of aluminum oxide, magnesium oxide and nickel oxide.

[0111] In some specific embodiments of the present application, the metal oxide in the metal oxide layer is selected from aluminum oxide.

[0112] In addition, the metal oxide layer may further include additives to further improve the adhesion, oxidation resistance or high temperature resistance of the metal oxide layer. Exemplarily, the additives may be binders.

[0113] It should be noted here that an insulating layer can be set on the collector surface on the inner side of the bending section of the first pole piece 11, the surface of the isolation membrane 13 corresponding to the inner side of the bending section, and the collector surface of the second pole piece 12 close to the inner side of the bending section. The thickness, material and width of the insulating layer are the same as those in the above embodiment and will not be repeated here.

[0114] In some embodiments of the present application, the bending section of the first pole piece 11 includes a first bending section having a first bending surface, a second bending section having a second bending surface, and a third bending section having a third bending surface, the two ends of the second bending section are respectively vertically connected to the first bending section and the second bending section, and the first bending surface, the second bending surface, and the third bending surface are connected to form the bending surface of the bending section. By providing the first bending section, the second bending section, and the third bending section, the processing difficulty of the first pole piece 11 can be further reduced.

[0115] In some embodiments of the present application, the total length L of the first bending segment, the second bending segment and the third bending segment satisfies: 0.3 mm ≤ L ≤ 0.7 mm.

[0116] Furthermore, in some embodiments of the present application, the length of the second bending segment is 0.1 mm to 0.3 mm.

[0117] Reference Figure 6 The present application provides a secondary battery, including the laminated battery cell in the above embodiment.

[0118] Specifically, refer to Figure 7 The secondary battery 20 includes a housing 21, an electrode assembly 22 and a cover assembly 23. The housing 21 has a chamber for accommodating the electrode assembly 22, and the cover assembly 23 is used to close the opening of the housing 23. The end cap assembly 23 includes an end cap, which is connected to the housing 40 to form the housing of the secondary battery 20. The electrode assembly 22 is disposed in the housing 21, and the housing 21 is filled with electrolyte. The secondary battery 20 can be square, cylindrical or other shapes.

[0119] According to actual use requirements, the electrode assembly 22 can be configured as a single electrode or multiple electrodes. Figure 7 As shown, at least two independent electrode assemblies 22 may also be provided in the secondary battery 20. The electrode assembly 22 may be formed by stacking the first electrode sheet 11, the second electrode sheet 12, and the separator 13 located between the first electrode sheet 11 and the second electrode sheet 12 together to form a main body, wherein the separator is an insulator between the first electrode sheet 11 and the second electrode sheet 12. In some embodiments of the present application, the first electrode sheet 11 is exemplarily a negative electrode sheet and the second electrode sheet 12 is a positive electrode sheet for illustration. The positive electrode active material is coated on the coating area of ​​the positive electrode sheet to form a positive electrode active layer, and the negative electrode active material is coated on the coating area of ​​the negative electrode sheet to form a negative electrode active layer, and multiple uncoated areas extending from the coating area of ​​the main body are stacked as tabs. The electrode assembly 22 also includes two tabs, namely a positive tab and a negative tab, the positive tab extending from the coating area of ​​the positive electrode sheet, and the negative tab extending from the coating area of ​​the negative electrode sheet.

[0120] Reference Figure 8 The present application provides a battery module, the battery module 30 including a plurality of secondary batteries 20 in the above-mentioned embodiment.

[0121] Reference Fig. 9 The present application provides a battery pack, wherein the battery 40 includes the battery module 30 in the above-mentioned embodiment.

[0122] Specifically, refer to Fig.10 The battery pack 40 includes a first box body 41, a second box body 42 and a battery module 30. The second box body 42 has a chamber for accommodating the battery module 30, and the first box body 41 is used to close the opening of the second box body 42.

[0123] The laminated battery provided in the present application can be used in, but not limited to, electrical devices such as vehicles, ships or aircraft. The laminated battery, battery module 30, battery pack 40, etc. disclosed in the present application can be used to form a power supply system for the electrical device, thereby improving the safety performance of the battery.

[0124] The present application provides an electric device, which includes a secondary battery 20, a battery module 30 or a battery pack 40. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0125] In some embodiments of the present application, the electric device is an electric car 50, such as Fig.11 Next, a method for preparing a laminated battery core provided by the present application is described, and the following laminated battery core can be prepared by adopting the preparation method.

[0126] Example 1

[0127] The present embodiment provides a method for preparing a battery cell, the method comprising the following steps:

[0128] S1: Active slurry is coated on two opposite surfaces of the first current collector 111, and a first active layer is formed after drying and cold pressing. The first active layer 121 in the bending section of the first current collector 111 is removed. After the marking is completed, an insulating material is sprayed on the exposed surface of the first current collector 111 to form a first insulating layer, thereby obtaining a first pole piece 11, which is a negative pole piece;

[0129] S2: coating active slurry on two opposite surfaces of the second current collector 121, drying and cold pressing to form a second active layer 122, thereby obtaining a second electrode sheet 12, which is a positive electrode sheet;

[0130] S3: The first pole piece 11 and the two isolation films are formed into a composite structure by a hot composite roller, and then composited with the second pole piece punched into a sheet, and then stacked under the action of gravity to form a battery cell.

[0131] Comparative Example 1

[0132] The difference between this comparative example and Example 1 is that: the first insulating layer is not provided on the surface of the first current collector 111 inside the bending section of the first pole piece 11, and the surface of the first current collector 111 inside the bending section of the first pole piece 11 is in contact with the end surface of the second current collector 121 of the second pole piece 12 close to the inner side of the bending section, that is, the second current collector 121 of the second pole piece 12 is connected to the exposed surface of the first current collector 111. Figure 4 .

[0133] The laminated cells prepared in Example 1 and Comparative Example 1 were assembled under the same conditions to obtain Battery A and Battery B, respectively. During the formation of Battery A and Battery B, Battery A was successfully formed, while Battery B caught fire.

[0134] Comparative Example 2

[0135] The difference between this comparative example and Example 1 is that the first insulating layer is not provided on the current collector surface inside the bending section of the first pole piece 11, and the overhang between the first pole piece 11 and the second pole piece 12 (overhang refers to the portion of the first pole piece that is longer and wider than the second pole piece) is not greater than 0.5 mm. Figure 5 .

[0136] The laminated cells prepared in Example 1 and Comparative Example 2 were assembled under the same conditions to obtain Battery C and Battery D, respectively. During the long-term charge and discharge cycle of Battery C and Battery D, lithium accumulation gradually formed on the surface of the first current collector 111 inside the bending section of the first pole piece 11, forming lithium dendrites 15. After about 390 cycles of fast charging of Battery D, the lithium dendrites 15 were large enough to pierce the isolation membrane and connect the second current collector 121 of the second pole piece 12 with the exposed surface of the first current collector 111, forming a short circuit and causing the battery to catch fire. However, after about 390 cycles of fast charging of Battery C, no safety accidents occurred.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A laminated battery cell, characterized in that: include: A first pole piece, wherein the first pole piece is reciprocatingly bent and stacked to form at least two first pole piece layers; At least one second pole piece, each of the second pole pieces is disposed between two adjacent first pole piece layers; An isolation film, disposed between the first pole piece and the second pole piece to isolate the first pole piece from the second pole piece; an insulating layer, disposed between the current collector surface on the inner side of the bending section of the first pole piece and the end surface of the second pole piece close to the inner side of the bending section, so as to prevent the current collector at the bending section of the first pole piece from being electrically connected to the current collector at the bending section of the second pole piece close to the bending section, Among them, one of the first pole piece and the second pole piece is a positive pole piece, and the other is a negative pole piece.

2. The laminated battery cell according to claim 1, characterized in that: The insulating layer includes a first insulating layer, and the first insulating layer is arranged on the current collector surface inside the bending section of the first pole piece.

3. The laminated battery cell according to claim 1 or 2, characterized in that: The insulating layer includes a second insulating layer, and the second insulating layer is arranged on an end surface of the second pole piece close to the inner side of the bending section.

4. The laminated battery cell according to claim 1 or 2, characterized in that: The insulating layer includes a third insulating layer, and the third insulating layer is arranged on a surface of the isolation film facing the inner side of the bending section.

5. The laminated battery cell according to claim 1 or 2, characterized in that: The insulating layer is a metal oxide layer.

6. The laminated battery cell according to claim 5, characterized in that: The metal oxide in the metal oxide layer is selected from at least one of aluminum oxide, magnesium oxide and nickel oxide.

7. The laminated battery cell according to claim 1 or 2, characterized in that: The thickness of the insulating layer is 8 μm to 20 μm.

8. The laminated battery cell according to claim 1, characterized in that: The bending section includes a first bending section having a first bending surface, a second bending section having a second bending surface, and a third bending section having a third bending surface. The two ends of the second bending section are respectively vertically connected to the first bending section and the second bending section. The first bending surface, the second bending surface, and the third bending surface are connected to form the bending surface of the bending section.

9. The laminated battery cell according to claim 8, characterized in that: The total length L of the first bending section, the second bending section and the third bending section satisfies: 0.3 mm ≤ L ≤ 0.7 mm.

10. The laminated battery cell according to claim 9, characterized in that: The length of the second bending section is 0.1 mm to 0.3 mm.

11. A secondary battery, characterized in that: The invention comprises the laminated battery core as described in any one of claims 1 to 10.

12. A battery module, characterized in that: The secondary battery according to claim 11 is included.

13. A battery pack, characterized in that: The invention comprises the battery module as claimed in claim 12.

14. An electrical device, characterized in that: The invention comprises at least one of the secondary battery according to claim 11, the battery module according to claim 12 or the battery pack according to claim 13.

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