Composite current collector, composite pole piece, battery and electronic equipment

Abstract

The present application provides a composite current collector, a composite pole piece, a battery and an electronic device, wherein the composite current collector comprises a current collector body and a protective layer, wherein the current collector body is arranged on the current collector body, wherein the protective layer comprises a plurality of protective portions, wherein a hollow portion is formed between two adjacent protective portions, and wherein the elongation of the protective portion is greater than the elongation of the current collector body. The composite current collector and composite pole piece provided by the present application can prevent short circuit between positive and negative pole pieces, thereby improving the safety performance of the battery.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and in particular to a composite current collector, a composite pole piece, a battery and an electronic device. Background Art

[0002] Rechargeable batteries, such as lithium batteries, are widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life and low environmental pollution. However, when rechargeable batteries are squeezed, collided or punctured, it is easy to cause a short circuit between the positive and negative electrodes, which in turn causes the battery cell to fail due to thermal runaway, and it is easy to catch fire or explode, causing serious harm. Therefore, how to improve the safety performance of the battery and prevent the short circuit between the positive and negative electrodes has become a technical problem that needs to be solved. Summary of the invention

[0003] The present application provides a composite current collector, a composite electrode, a battery and an electronic device that prevent short circuits between positive and negative electrode sheets and improve the safety performance of the battery.

[0004] In a first aspect, an embodiment of the present application provides a composite current collector, comprising:

[0005] the current collecting body; and

[0006] A protective layer is provided on the current collecting body, wherein the protective layer comprises a plurality of protective portions, a hollow portion is formed between two adjacent protective portions, and an elongation of the protective portion is greater than an elongation of the current collecting body.

[0007] In a second aspect, an embodiment of the present application provides a composite electrode, comprising an active material layer and the composite current collector, wherein the active material layer is disposed on one side or two opposite sides of the composite current collector.

[0008] In a third aspect, an embodiment of the present application provides a battery comprising a plurality of the above-mentioned composite pole pieces.

[0009] In a fourth aspect, an embodiment of the present application provides an electronic device, comprising the battery.

[0010] The composite current collector provided in the embodiment of the present application is provided with a protective layer, the protective layer having a plurality of protective parts, the elongation of the protective part being greater than the elongation of the current collector body, the protective part having a stronger tensile strength than the current collector body, so that the protective part has a stronger resistance to puncture than the current collector body, effectively preventing puncture from piercing the protective part, and improving the resistance of the composite current collector to puncture; the hollow part between the protective parts is used to make the conductive materials on the opposite sides of the protective layer conductive, so as to realize the conductive function of the current collector body.

[0011] The composite electrode provided in the embodiment of the present application includes the above-mentioned composite current collector, so that it has stronger resistance to puncture.

[0012] The battery provided in the embodiment of the present application includes a plurality of the above-mentioned composite pole pieces. Since a protective layer capable of effectively resisting puncture is provided inside the composite pole piece, the battery has a strong resistance to punctures or other punctures generated by internal electrochemical reactions, thereby effectively preventing the punctures from simultaneously piercing the positive and negative pole pieces and forming a short circuit between the positive and negative pole pieces, avoiding safety problems caused by rapid heating of the battery after the positive and negative pole pieces are short-circuited, and improving the safety of the battery.

[0013] The electronic device provided in the embodiment of the present application includes the above-mentioned battery. By improving the internal structure of the battery, the battery has higher safety, and therefore the electronic device also has higher safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 It is a structural schematic diagram of an electronic device provided in an embodiment of the present application;

[0016] Figure 2 yes Figure 1 A schematic diagram of the structure of an electronic device is provided;

[0017] Figure 3 is a circuit block diagram of a battery provided in an embodiment of the present application electrically connected to an external power source;

[0018] Figure 4 yes Figure 2 A perspective view of a battery is provided;

[0019] Figure 5 yes Figure 2 A cross-sectional view of the battery provided;

[0020] Figure 6 yes Figure 5 A first partial cross-sectional view of a cell in a provided battery;

[0021] Figure 7 yes Figure 6 A cross-sectional view of a first composite pole piece of the first type provided;

[0022] Figure 8 yes Figure 6A cross-sectional view of a second first composite pole piece provided;

[0023] Fig. 9 yes Figure 6 A cross-sectional view of a third first composite pole piece provided;

[0024] Fig.10 yes Figure 6 A cross-sectional view of a fourth first composite pole piece provided;

[0025] Fig.11 yes Figure 6 A cross-sectional view of a fifth first composite pole piece provided;

[0026] Fig.12 yes Figure 6 A cross-sectional view of a sixth first composite pole piece provided;

[0027] Fig.13 yes Figure 6 A cross-sectional view of a seventh first composite pole piece provided;

[0028] Fig.14 yes Figure 6 A cross-sectional view of an eighth first composite pole piece provided;

[0029] Fig.15 yes Figure 6 A cross-sectional view of a ninth first composite pole piece provided;

[0030] Fig.16 yes Figure 6 A cross-sectional view of a tenth first composite pole piece provided;

[0031] Fig.17 yes Figure 6 A cross-sectional view of an eleventh first composite pole piece provided;

[0032] Fig.18 yes Figure 6 A cross-sectional view of a twelfth first composite pole piece provided;

[0033] Fig.19 yes Figure 6 A cross-sectional view of a thirteenth first composite pole piece provided;

[0034] Fig. 20 yes Figure 5 A second cross-sectional view of a cell in a provided battery;

[0035] Fig.21 yes Figure 5 A third cross-sectional view of a cell in a provided battery;

[0036] Fig. 22 yes Figure 5 A fourth cross-sectional view of a cell in a battery is provided;

[0037] Fig.23 yes Figure 6 A top view of a first protective layer is provided;

[0038] Fig.24 yes Figure 6 A top view of a second protective layer is provided;

[0039] Fig.25 yes Figure 6 A top view of a third protective layer is provided;

[0040] Fig.26 yes Figure 6 A top view of a fourth protective layer is provided;

[0041] Fig. 27 yes Figure 6 A cross-sectional view of a fourteenth first composite pole piece provided;

[0042] Fig.28 yes Figure 7 A cross-sectional view of a first protective portion is provided;

[0043] Fig.29 yes Figure 7 A top view of a second protective portion provided;

[0044] Fig.30 yes Figure 7 A cross-sectional view of a third type of protection portion is provided;

[0045] Fig.31 yes Figure 7 A cross-sectional view of a fourth type of protection portion is provided;

[0046] Fig.32 yes Figure 7 A cross-sectional view of a fifth type of protection portion is provided;

[0047] Fig.33 yes Figure 6 A cross-sectional view of a fifth protective layer provided;

[0048] Fig.34 yes Figure 6 A cross-sectional view of the sixth protective layer provided. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. The embodiments listed in the present application can be appropriately combined with each other.

[0050] Please refer to Figure 1 , Figure 1The electronic device 100 may be a rechargeable device such as a telephone, a television, a tablet computer, a mobile phone, a camera, a personal computer, a notebook computer, a wearable device, an electric vehicle, an airplane, etc. Figure 1 In this application, the electronic device 100 is described as a mobile phone. For the convenience of description, the electronic device 100 is defined as a first viewing angle, the width direction of the electronic device 100 is defined as the X direction, the length direction of the electronic device 100 is defined as the Y direction, and the thickness direction of the electronic device 100 is defined as the Z direction.

[0051] Please refer to Figure 2 , the electronic device 100 includes a battery 10. In this embodiment, the electronic device 100 is a mobile phone. The electronic device 100 also includes a display screen 20, a middle frame 30 and a back cover 40. The display screen 20, the middle frame 30 and the back cover 40 are fixedly connected in sequence. The battery 10 is arranged in the middle frame 30. The battery 10 is used to power the display screen 20 and the mainboard 60 arranged on the middle frame 30 and other devices.

[0052] The battery 10 includes, but is not limited to, all solid-state batteries such as lithium-ion batteries, lithium metal batteries, lithium-polymer batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-manganese-cobalt batteries, lithium-sulfur batteries, lithium-air batteries, nickel-hydrogen batteries, lithium-ion batteries, iron batteries, nano batteries, etc. The present application embodiment takes the battery 10 as a lithium-ion battery as an example for description.

[0053] The present application does not specifically limit the shape of the battery 10. The battery 10 may be in a columnar form, a bag form, an arc form, a soft-pack square form, a cylindrical form, a prism form, or a special shape. According to the charging method classification, the battery 10 described in the present application includes but is not limited to a wired charging battery and a wireless charging battery. The present application embodiment takes the battery 20 as a wired charging battery as an example for explanation.

[0054] Please refer to Figure 2 The electronic device 100 also includes a charging interface 50 and a charging control unit 70 .

[0055] Please refer to Figure 2 The charging interface 50 is provided on the middle frame 30 so that the charging interface 50 is connected to the external power source 200 (hereinafter referred to as the power source 200). Specifically, the charging interface 50 can be connected to the power source 200 via a charging cable. The types of the charging interface 50 include but are not limited to the Micro USB interface of Android and Windows phone system phones, the USB Type C interface, and the Lightning interface of the IOS system phone.

[0056] Please refer to Figure 3, the charging control unit 70 connects the charging interface 50 and the battery 10. The charging control unit 70 may be a packaged integrated chip, which is disposed on the main board 60 or the small board and is used to control the charging time and charging current of the battery 10. The charging interface 50 is connected to the charging control unit 700 through a flexible circuit board. The power supply 200, the charging interface 50, the charging control unit 70, and the battery 10 form a charging circuit of the battery 10.

[0057] Please refer to Figure 3 , the conductive end of the power supply 200 includes a first power supply end 210 and a second power supply end 220. The first power supply end 210 is the positive end of the power supply 200, and the second power supply end 220 is the negative end of the power supply 200; or, the first power supply end 210 is the negative end of the power supply 200, and the second power supply end 220 is the positive end of the power supply 200. In this embodiment, the first power supply end 210 is the positive end, and the second power supply end 220 is the negative end. The charging interface 50 includes a first charging end 501 and a second charging end 502. When the charging interface 50 is electrically connected to the power supply 200, the first charging end 501 is connected to the first power supply end 210, and the second charging end 502 is connected to the second power supply end 220. At this time, the current flows from the first power supply end 210, through the first charging end 501, the charging control unit 70, the positive electrode 101 of the battery 10, the negative electrode 102 of the battery 10, and the second charging end 502, to the second power supply end 220, and the battery 10 is in a charging state.

[0058] The specific structure of the battery 10 provided in the embodiment of the present application is described below with reference to the accompanying drawings.

[0059] Please refer to Figure 4 The battery 10 includes a battery cell 1, a protection board 2 and a packaging shell 3. The protection board 2 is electrically connected to the battery cell 1, and is used to protect the battery cell 1 from overvoltage, undervoltage, overcurrent, short circuit, and overtemperature, and to extend the service life of the battery 10. The packaging shell 3 is used to package the battery cell 1 and the protection board 2. The packaging shell 3 includes but is not limited to an aluminum shell, a steel shell, an aluminum-plastic film, etc. In this embodiment, the packaging shell 3 is an aluminum-plastic film.

[0060] Please refer to Figure 5 The battery cell 1 includes a first composite electrode sheet 11, a second composite electrode sheet 12, an electrolyte 13 and a separator 14. The first composite electrode sheet 11 is a positive electrode sheet, and the second composite electrode sheet 12 is a negative electrode sheet; or, the first composite electrode sheet 11 is a negative electrode sheet, and the second composite electrode sheet 12 is a positive electrode sheet. In this embodiment, the first composite electrode sheet 11 is a positive electrode sheet, and the second composite electrode sheet 12 is a negative electrode sheet.

[0061] Please refer to Figure 6 The first composite electrode sheet 11 includes a first composite current collector 111 and a first active material layer 112 disposed on the first composite current collector 111 .

[0062] Specifically, the first composite current collector 111 is a conductive sheet.

[0063] The number of the first active material layer 112 is at least one layer. In this embodiment, the first active material layer 112 is disposed on two opposite surfaces of the first composite current collector 111 to increase the area of ​​the first active material layer 112 under a limited volume, thereby increasing the ability of the first composite current collector 111 to absorb or generate electrons in the electrochemical reaction, and improving the energy density of the battery 10. In other embodiments, the first active material layer 112 is disposed on one surface of the first composite current collector 111. Specifically, the first active material layer 112 includes a layered or spinel structured transition metal oxide or polyanionic compound with a high electrode potential and a stable structure and lithium insertion ability, such as at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials, and lithium nickel cobalt aluminum oxide.

[0064] Please refer to Figure 6 The second composite electrode sheet 12 includes a second composite current collector 121 and a second active material layer 122 disposed on the second composite current collector 121. The second composite current collector 121 is a conductive sheet. The number of the second active material layer 122 is at least one layer. In this embodiment, the second active material layer 122 is disposed on two opposite surfaces of the second composite current collector 121 to increase the area of ​​the second active material layer 122 under a limited volume, thereby increasing the ability of the second composite current collector 121 to generate or absorb electrons, thereby improving the energy density of the battery 10. In other embodiments, the second active material layer 122 is disposed on one surface of the second composite current collector 121.

[0065] The second active material layer 122 may be layered graphite, metal element, or metal oxide, such as graphite, carbon fiber, graphene, lithium titanate, etc., which has a potential as close to the lithium potential as possible, a stable structure, and can store a large amount of lithium.

[0066] Please refer to Figure 6, the first composite pole piece 11, the diaphragm 14 and the second composite pole piece 12 are all in the form of thin sheets. The diaphragm 14 is disposed between the first composite pole piece 11 and the second composite pole piece 12 to prevent the first composite pole piece 11 from directly contacting the second composite pole piece 12. Because when the first composite current collector 111 of the first composite pole piece 11 and the second composite current collector 121 of the second composite pole piece 12 are turned on, the battery 10 is short-circuited, and the current inside the battery 10 increases sharply instantly, causing the temperature inside the battery 10 to rise sharply, and the active material layer and the electrolyte 13 inside the battery 10 are prone to explosion and other safety problems at high temperatures. The diaphragm 14 is a specially formed polymer film, and the diaphragm 14 has a microporous structure that allows lithium ions to pass freely, but electrons cannot pass, so that the first composite pole piece 11 and the second composite pole piece 12 can undergo an electrochemical reaction, but the first composite pole piece 11 and the second composite pole piece 12 are in an insulating state. The material of the diaphragm 14 includes but is not limited to polyethylene (PE), polypropylene (PP) or their composite films. The composite membrane is, for example, a PP / PE / PP three-layer membrane.

[0067] Optionally, the number of the first composite electrode sheet 11 and the number of the second composite electrode sheet 12 are both one, and a first composite electrode sheet 11, one or more separators 14, and a second composite electrode sheet 12 are sequentially stacked and then wound to form a wound battery cell 1.

[0068] Optionally, the number of the first composite electrode sheet 11, the second composite electrode sheet 12, and the diaphragm 14 are all multiple. The first composite electrode sheet 11, the diaphragm 14, the second composite electrode sheet 12, the diaphragm 14, the first composite electrode sheet 11, and the diaphragm 14 are stacked in sequence to form a laminated battery cell 1.

[0069] Please refer to Figure 5 Optionally, the electrolyte 13 can be an organic solvent containing electrolyte lithium salt, which is used to provide lithium ions. The electrolyte lithium salt includes LiPF6, LiClO4, LiBF4, etc. The organic solvent is mainly composed of one or a mixture of diethyl carbonate (DEC), propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), etc. The first composite pole piece 11, the second composite pole piece 12 and the diaphragm 14 are packaged in the packaging shell 3, and the electrolyte 13 is injected into the packaging shell 3 so that the first composite pole piece 11 and the second composite pole piece 12 are immersed in the electrolyte 13, and the protection plate 2 is packaged in the packaging shell 3 to form a battery 10.

[0070] During the charge and discharge process of the battery 10, Li+ is intercalated and deintercalated between the first composite electrode sheet 11 and the second composite electrode sheet 12. During charging, Li+ is deintercalated from the first composite electrode sheet 11 (positive electrode) and intercalated into the second composite electrode sheet 12 (negative electrode) through the electrolyte, and the second composite electrode sheet 12 is in a lithium-rich state. The opposite is true during discharge.

[0071] For further information, please refer to Figure 5 The battery cell 1 further includes a first pole ear 16 and a second pole ear 17. The first pole ear 16 is electrically connected to the first composite pole sheet 11, and the second pole ear 17 is electrically connected to the second composite pole sheet 12. One end of the first pole ear 16 away from the first composite pole sheet 11 is electrically connected to the protection board 2, and one end of the second pole ear 17 away from the second composite pole sheet 12 is electrically connected to the protection board 2, so that the protection board 2 manages the charging and discharging of the battery cell 1.

[0072] The first composite pole piece 11, the first pole ear 16, the protection plate 2, the charging control unit 70, the load, the protection plate 2, the second pole ear 17, and the second composite pole piece 12 form a discharge circuit. The first composite pole piece 11, the first pole ear 16, the protection plate 2, the charging control unit 70, the external power supply 200, the protection plate 2, the second pole ear 17, and the second composite pole piece 12 form a charging circuit.

[0073] Generally speaking, the battery 10 is prone to short circuit of the positive and negative electrodes in abnormal situations such as collision, extrusion, and puncture, which leads to safety problems of the battery 10. Before the battery 10 leaves the factory, it is necessary to evaluate the safety of the battery 10 by reproducing the penetration phenomenon of the battery 10 to quantitatively evaluate the degree of danger. The puncture test is a very effective risk assessment method for the safety assessment of the battery 10. Specifically, the battery 10 is punctured by a steel needle to test the probability of the battery 10 short-circuiting under the puncture of the steel needle. The smaller the probability of the battery 10 short-circuiting under the puncture of the steel needle, the higher the pass rate of the battery 10 for mechanical tests such as puncture and impact, and the higher the safety and puncture stability of the battery 10. On the other hand, during the electrochemical reaction inside the battery 10, lithium crystallization is easily generated in a low temperature environment. The lithium crystallization is very likely to pierce the electrode inside the battery 10 and cause the battery 10 to short-circuit. The puncture described in this application includes but is not limited to lithium crystallization generated by the steel needle in the puncture test and the electrochemical reaction inside the battery 10.

[0074] The embodiment of the present application provides a first composite current collector 111 and a second composite current collector 121 that can improve the safety of the battery 10 during collision, extrusion, and puncture, and reduce the short circuit of the battery 10, so that the first composite pole piece 11 and the second composite pole piece 12 have strong puncture stability, and have a high pass rate for abnormal conditions such as puncture and impact. In this way, the battery 10 formed by the first composite pole piece 11 and the second composite pole piece 12 also has strong puncture stability, and has a high pass rate for abnormal conditions such as puncture and impact, thereby reducing the probability of short circuit of the battery 10 and effectively improving the safety of the battery 10.

[0075] The structure of the first composite current collector 111 is described below with reference to the accompanying drawings. The structure of the second composite current collector 121 may refer to the structure of the first composite current collector 111 .

[0076] See also Figure 7 , the first composite current collector 111 includes a first current collector body 113 and a first protective layer 114 disposed on the first current collector body 113. In the present embodiment, the first protective layer 114 and the first current collector body 113 together form the first composite current collector 111. The present application does not specifically limit the specific combination method of the first protective layer 114 and the first current collector body 113. Specifically, the first protective layer 114 can be composited with the first current collector body 113 by at least one of coating, calendering, rolling, bonding, evaporation, vapor deposition, chemical deposition, magnetron sputtering, and chemical plating. Furthermore, the present application does not specifically limit the specific position of the first protective layer 114 on the first current collector body 113. In other words, the first protective layer 114 can be disposed on the surface of the first current collector body 113, or it can be disposed in the first current collector body 113.

[0077] Specifically, the first current collector body 113 is a conductive material. In this embodiment, the first composite current collector 111 is a positive electrode current collector. Further, the first current collector body 113 is an aluminum foil.

[0078] The elongation of the first protective layer 114 is greater than the elongation of the first current collector 113. Elongation is an indicator that describes the plastic properties of a material. The elongation is the percentage of the total deformation ΔL of the gauge section after the tensile fracture of the specimen to the original gauge length L: δ = ΔL / L×100%. The greater the elongation, the greater the deformation of the material after the tensile fracture. In other words, the material is less likely to break. In other words, the fracture resistance of the first protective layer 114 is greater than the fracture resistance of the first current collector 113. When the puncture pierces the first composite electrode sheet 11, since the first protective layer 114 has a large elongation, the first protective layer 114 can effectively block the puncture by deformation to prevent the puncture from penetrating the first composite electrode sheet 11. In this way, it is possible to prevent the puncture from connecting the first composite electrode sheet 11 and the second composite electrode sheet 12, thereby preventing the positive and negative electrodes of the battery 10 from short-circuiting.

[0079] The material of the first protective layer 114 includes but is not limited to adhesives, porous retractable structures, etc. The adhesive includes but is not limited to at least one of polyvinylidene fluoride, copolymer of vinylidene fluoride-fluorinated olefin, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, fluorinated rubber, polyvinyl alcohol, polyvinylidene fluoride, polyamide, etc. The porous retractable structure includes but is not limited to nano-retractable structures, porous foam structures, and fiber porous structures.

[0080] In one embodiment, the material of the first protective layer 114 is an insulating material, for example, the first protective layer 114 is a glue layer. When the first protective layer 114 is a whole layer design, and the first protective layer 114 is disposed in the first current collector 113, the first protective layer 114 blocks the electrical conduction of the first current collector 113 on opposite sides thereof. When the first protective layer 114 is a whole layer design, and the first protective layer 114 is disposed between the first current collector 113 and the first active material layer 112, the first protective layer 114 blocks the electrical conduction of the first current collector 113 and the first active material layer 112 on opposite sides thereof, thus weakening the electrical conductivity of the first current collector 113.

[0081] In this embodiment, please refer to Figure 7 , the first protective layer 114 includes a plurality of first protective portions 115, and a first hollow portion 116 is formed between two adjacent first protective portions 115. The elongation of the first protective portion 115 is greater than the elongation of the first current collector body 113. The first protective portion 115 protects the first composite current collector 111 to prevent puncture of the first composite current collector 111. The first hollow portion 116 is provided between two adjacent first protective portions 115 so that the first current collector bodies 113 on opposite sides (along the Z-axis direction) of the first protective layer 114 can contact and conduct with each other, thereby preventing the first current collector bodies 113 on opposite sides (along the Z-axis direction) of the first protective layer 114 from being insulated, thereby improving the conductivity of the first composite current collector 111.

[0082] In this embodiment, the first protective layer 114 is a patterned structure relative to the first current collector 113. Optionally, the first hollow portion 116 in the first protective layer 114 is used to accommodate part of the first current collector 113, so that the electrical conductivity inside the first current collector 113 is good, so as to avoid the first protective layer 114 isolating the first current collector 113 into two mutually insulated conductive parts, so as to achieve good electrical conductivity inside the first current collector 113; or, to avoid the first protective layer 114 isolating the first current collector 113 from the first active material layer 112, so as to avoid the problem that the first current collector 113 cannot achieve electrical conductivity between the first electrode 16 and the first active material layer 112, so as to improve the electrical conductivity between the first current collector 113 and the first active material layer 112.

[0083] The first composite current collector 111 provided in the present embodiment includes a plurality of first protection portions 115 by providing a first protection layer 114, and a first hollow portion 116 is formed between two adjacent first protection portions 115, wherein the first protection portion 115 can provide a higher elongation to effectively resist puncturing and penetrating the first composite electrode sheet 11, thereby improving the resistance of the battery 10 to puncture, and further improving the safety of the battery 10; in addition, the first hollow portion 116 is used as a conductive channel reserved for the first protective layer 114 on both sides thereof, so that the first current collector body 113 on the opposite sides of the first protective layer 114 can be well electrically conductive, or the first current collector body 113 and the first active material layer 112 on the opposite sides of the first protective layer 114 can be electrically conductive, thereby achieving the conductive performance of the first current collector body 113, and enabling the battery 10 to charge and discharge normally; in addition, a patterned first protection layer 114 is provided on the first composite current collector 111, so that the material of the first protection layer 114 can be reduced, cost can be saved, and the overall weight of the battery 10 can be reduced.

[0084] In other words, the first protective portion 115 of the first protective layer 114 is a protective portion on the first composite current collector 111 that prevents puncture, and the first hollow portion 116 of the first protective layer 114 is a conductive path on the first composite current collector 111. In this way, the first protective layer 114 can not only effectively protect against puncture, but also ensure that the first composite current collector 111 has a higher conductivity.

[0085] Optionally, the thickness of the first protection portion 115 in the Z-axis direction is 1-40 μm.

[0086] In this embodiment, the present application does not limit the number, arrangement and shape of the first protection portion 115 .

[0087] See also Figure 7 and Figure 8 The first protective layer 114 is disposed on the first current collecting body 113, including but not limited to at least a portion of the first protective layer 114 being embedded in the first current collecting body 113; and / or at least a portion of the first protective layer 114 is disposed on the outer surface of the first current collecting body 113.

[0088] Specifically, this embodiment does not specifically limit the number of the first protective layer 114. Figure 8 , the number of the first protective layer 114 is one, and the first protective layer 114 is entirely disposed on the outer surface of the first current collecting body 113; or, refer to Fig. 9 , a portion of the first protective layer 114 is disposed on the outer surface of the first current collecting body 113, and another portion is embedded in the first current collecting body 113; or, refer to Figure 7, the first protective layer 114 is entirely disposed in the first current collecting body 113. In another possible implementation, the number of the first protective layers 114 is two or more. For example, the number of the first protective layers 114 is two. Figures 10 to 12 The two first protective layers 114 are respectively disposed on the first surface 113a and the second surface 113b of the first current collecting body 113, which are disposed opposite to each other. The two first protective layers 114 can be disposed opposite to each other, partially staggered, or completely staggered in the Z-axis direction; or, refer to Figures 13 to 15 , one first protective layer 114 is disposed on the first surface 113a or the second surface 113b of the first current collecting body 113, and another first protective layer 114 is disposed inside the first current collecting body 113. The two first protective layers 114 can be disposed opposite to each other, partially staggered, or completely staggered in the Z-axis direction; or, refer to Figures 16 to 18 The two first protective layers 114 are both completely disposed in the first current collecting body 113 , and the two first protective layers 114 can be disposed opposite each other, partially staggered, or completely staggered in the Z-axis direction.

[0089] Optional, see Fig. 9 and Fig.10 When at least a portion of the first protective layer 114 is disposed on the outer surface of the first current collecting body 113, at least a portion of the first hollow portion 116 is used to accommodate a portion of the first active material layer 112. In other words, at least a portion of the first active material layer 112 disposed on the outer surface of the first current collecting body 113 is disposed in the first hollow portion 116, so that the first active material layer 112 is in contact with the first current collecting body 113, and good electrical conduction can be achieved between the first electrode tab 16, the first current collecting body 113, and the first active material layer 112.

[0090] Optional, see Figure 8 , the first protective layer 114 is disposed on the surface of the first current collecting body 113, and the first active material layer 112 covers the first protective layer 114. In other words, the first active material layer 112 covers the first protective portion 115 and the first hollow portion 116. Further, the first active material layer 112 can be disposed in the first hollow portion 116.

[0091] Optional, see Fig.19, the first active material layer 112 is disposed in the first hollow portion 116. The first active material layer 112 and the first protective portion 115 are located in the same layer. In other words, the first active material layer 112 can fill the entire first hollow portion 116. The first active material layer 112 and the first protective portion 115 are complementary patterns. In this way, the first active material layer 112 and the first protective layer 114 are the same layer, so that the overall thickness of the entire first composite pole piece 11 is small; at the same time, the first composite pole piece 11 has a high protection capability against puncture, collision and other tests and harsh environments, thereby improving the safety performance of the battery 10.

[0092] Optional, see Figure 7 and Fig. 9 , when at least part of the first protective layer 114 is embedded in the first current collector body 113, at least part of the first hollow portion 116 is used to accommodate part of the first current collector body 113. In other words, the first current collector body 113 is at least partially disposed in the first hollow portion 116, which, on the one hand, allows the first current collector body 113 to be coated with the first protective layer 114, thereby improving the integration between the first current collector body 113 and the first protective layer 114 and reducing the overall volume of the first composite current collector 111, and on the other hand, allows the first current collector body 113 to have good conductivity even if the first protective layer 114 is embedded.

[0093] The above is an embodiment of the specific structure of the first composite current collector 111. The structure of the second composite current collector 121 in this application is roughly similar to that of the first composite current collector 111. Figure 20 to Figure 22 , the second composite current collector 121 includes a second current collector body 123 and a second protective layer 124 disposed on the second current collector body 123, the second protective layer 124 includes a plurality of second protective portions 125, and a second hollow portion 126 is formed between two adjacent second protective portions 125. The second protective portion 125 and the first protective portion 115 are completely opposite, partially staggered, or completely staggered in the Z-axis direction. The positional relationship between the second protective layer 124 and the second current collector body 123 can refer to the positional relationship between the first protective layer 114 and the first current collector body 113. Among them, the first protective layer 114 and the second protective layer 124 are made of the same material, and the first current collector body 113 and the second current collector body 123 are made of different materials, for example, the first current collector body 113 is aluminum foil, and the second current collector body 123 is copper foil. The shape of the second protective portion 125 and the first protective portion 115 may be the same or different, and the shape of the first hollow portion 116 and the second hollow portion 126 may be the same or different.

[0094] It can be understood that the above-mentioned first composite current collector 111 and second composite current collector 121 can be used for the wound battery cell 1 structure and the stacked battery cell 1 structure. When the first composite current collector 111 and the second composite current collector 121 are applied to the stacked battery cell 1 structure, some of the pole pieces in the stacked battery cell 1 structure can be composite pole pieces, or all of the pole pieces in the stacked battery cell 1 structure can be composite pole pieces, so as to improve the safety of the battery 10.

[0095] Optionally, the present application does not specifically limit the specific shapes of the first protective portion 115 and the first hollow portion 116. The first protective portion 115 and the first hollow portion 116 are complementary pattern structures or non-complementary pattern structures. In this embodiment, the first protective portion 115 and the first hollow portion 116 are complementary pattern structures. The first protective portion 115 and the first hollow portion 116 cover the entire first current collecting body 113. The specific shapes of the first protective portion 115 and the first hollow portion 116 include but are not limited to the following embodiments.

[0096] In one possible implementation, see Fig.23 , the first protection portion 115 is in the shape of a strip and the first hollow portion 116 is in the shape of a strip. Multiple first protection portions 115 and multiple first hollow portions 116 are arranged alternately in sequence. The first protection portion 115 and the first hollow portion 116 are both rectangular strips, and the extension directions of the first protection portion 115 and the first hollow portion 116 are the same. Specifically, the first protection portion 115 and the first hollow portion 116 both extend along the X-axis direction, the Y-axis direction, or in a direction inclined relative to the X-axis direction and the Y-axis direction. In other embodiments, the first protection portion 115 and the first hollow portion 116 can also be triangular strips, diamond strips, wavy strips, etc. This application does not specifically limit the number and size of the first protection portion 115.

[0097] In one possible implementation, see Fig.24 and Fig.25 , the first protection portion 115 is block-shaped and the first hollow portion 116 is grid-shaped. The first protection portion 115 and the first hollow portion 116 have complementary pattern structures. The shape of the first protection portion 115 includes but is not limited to a circle, a triangle, a square, a rectangle, a diamond, etc. The multiple first protection portions 115 can be arranged in multiple rows and columns, or in a staggered arrangement.

[0098] In one possible implementation, see Fig.26 The first protection portion 115 is in a grid shape and the first hollow portion 116 is in a block shape. The first protection portion 115 and the first hollow portion 116 have complementary pattern structures. The shape of the first hollow portion 116 includes but is not limited to a circle, a triangle, a square, a rectangle, a diamond, and the like.

[0099] In one embodiment, see Fig. 27 , the number of the first protective layer 114 is multiple. Multiple first protective layers 114 are stacked in sequence and spaced apart along the thickness direction (i.e., the Z-axis direction) of the first current collector body 113. The first protective portions 115 in two adjacent layers of the first protective layer 114 are at least partially staggered perpendicular to the thickness direction. The first protective portions 115 in two adjacent layers of the first protective layer 114 are completely staggered or partially staggered perpendicular to the X-axis direction and / or the Y-axis direction. For example, two adjacent layers of the first protective layer 114 include a first sub-protective layer 114a and a second sub-protective layer 114b. At least part of the orthographic projection of the first protective portion 115 of the first sub-protective layer 114a in the Z-axis direction (in the thickness direction of the first current collector body 113) is provided in the first hollow portion 116 of the second sub-protective layer 114b. In this way, on the XY plane, the blocking area formed by the first protective portion 115 is relatively large, which can resist punctures at more different positions, further improving the safety of the battery 10; and, the multiple layers of first protective layers 114 are arranged at intervals in the Z-axis direction, and the multiple layers of first protective layers 114 can block punctures from the opposite sides of the first current collector 113, and then provide protection from the opposite sides of the first current collector 113, further improving the protection efficiency; and, each layer of the first protective layer 114 is provided with a first hollow portion 116, so even after multiple layers of first protective layers 114 are arranged in the first composite current collector 111, it can still have good conductive properties.

[0100] For further information, see Fig. 27 , the first protective portion 115 of the first sub-protective layer 114a completely or partially covers the first hollow portion 116 of the second sub-protective layer 114b in the thickness direction of the first current collecting body 113 as an orthographic projection on the second sub-protective layer 114b; and / or, the first protective portion 115 of the second sub-protective layer 114b completely or partially covers the first hollow portion 116 of the first sub-protective layer 114a in the thickness direction of the first current collecting body 113 as an orthographic projection.

[0101] In this embodiment, the orthographic projection of the first protective portion 115 of the first sub-protective layer 114a in the thickness direction of the first current collecting body 113 completely covers the first hollow portion 116 of the second sub-protective layer 114b; and the orthographic projection of the first protective portion 115 of the second sub-protective layer 114b in the thickness direction of the first current collecting body 113 completely covers the first hollow portion 116 of the first sub-protective layer 114a. In other words, the first protective portions 115 of the two protective layers 114a and 114b are staggered to form a larger blocking area, so that the protective portions 115 of the first sub-protective layer 114a and the second sub-protective layer 114b can form full coverage in the XY plane of the first composite pole piece 11 to block punctures at various positions in the XY plane of the first composite pole piece 11, thereby further improving the safety of the battery 10; at the same time, the first hollow portion 116 on the first sub-protective layer 114a and the second hollow portion 126 on the second sub-protective layer 114b both form a conductive channel, so that the entire first current collecting body 113 has better conductive properties.

[0102] Further, the first subprotective layer 114a is disposed on the first surface 113a of the first current collecting body 113; and / or, the second subprotective layer 114b is disposed on the second surface 113b of the first current collecting body 113. In this embodiment, the first subprotective layer 114a is disposed on the first surface 113a of the first current collecting body 113, and the second subprotective layer 114b is disposed on the second surface 113b of the first current collecting body 113.

[0103] Generally speaking, a first protective layer 114 is provided in the first current collecting body 113 to prevent puncture through the first composite electrode sheet 11. However, one end of the puncture contacts the second active material layer 122 of the second composite electrode sheet 12, and the other end of the puncture contacts the first active material layer 112 of the first composite electrode sheet 11 and then contacts the first current collecting body 113. At this time, the puncture may still cause a short circuit between the first composite electrode sheet 11 and the second composite electrode sheet 12.

[0104] Based on the above problems, the embodiment of the present application provides the first sub-protective layer 114a and the second sub-protective layer 114b on two opposite outer surfaces of the first current collector 113, so that the first sub-protective layer 114a and the second sub-protective layer 114b respectively protect the first current collector 113 from opposite sides. When one end of the puncture contacts the second active material layer 122 of the second composite electrode 12, and the other end of the puncture pierces the first active material layer 112 of the first composite electrode 11, the first sub-protective layer 114a blocks the extension of the other end of the puncture and blocks the other end of the puncture from contacting the first current collector 113, so that the puncture can effectively prevent the two adjacent electrodes from being turned on.

[0105] Further, among the plurality of first composite pole pieces 11, the first sub-protective layer 114a and the second sub-protective layer 114b are respectively disposed on opposite sides of some first current collecting bodies 113, or the first sub-protective layer 114a and the second sub-protective layer 114b are disposed on opposite sides of all first current collecting bodies 113. Further, among the plurality of second composite pole pieces 12, two layers of second protective layers 124 are respectively disposed on opposite sides of some second current collecting bodies 123, or the second protective layers 124 are respectively disposed on opposite sides of all second current collecting bodies 123.

[0106] By providing at least a double-layer patterned first protective layer 114 in the first composite pole piece 11, and at least partially staggering the first protective portion 115 in the double-layer first protective layer 114 in a thickness direction perpendicular to the first current collecting body 113, and providing the double-layer first protective layer 114 on two opposite surfaces of the first current collecting body 113, on the one hand, the blocking area formed by the first protective portion 115 in the first composite pole piece 11 is increased, making up for the deficiency that the first hollow portion 116 in the single-layer first protective layer 114 is not provided with the first protective portion 115; on the other hand, by providing the double-layer patterned first protective layer 114 on the opposite surfaces of the first current collecting body 113, the upper and lower sides of the first current collecting body 113 are effectively protected, further reducing the risk of short circuit of the battery 10 and improving the safety of the battery 10; on the other hand, the patterned arrangement of the first protective layer 114 can also enable effective electrical conduction between the first active material layers 122 of the upper and lower layers of the first current collecting body 113 and the first current collecting body 113 in the middle.

[0107] See also Fig.14 , the first protective layer 114 of the first composite pole piece 11 and the second protective layer 124 of the second composite pole piece 12 are at least partially staggered in a direction perpendicular to the Z axis. Specifically, the first protective layer 114 of the first composite pole piece 11 and the second protective layer 124 of the second composite pole piece 12 are at least partially staggered in an X axis or Y axis direction. Further, the orthographic projection of the first protective layer 114 of the first composite pole piece 11 in the thickness direction of the first current collector body 113 covers the second hollow portion 126 in the second protective layer 124, and the orthographic projection of the second protective layer 124 of the second composite pole piece 12 in the thickness direction of the second current collector body 123 covers the first hollow portion 116 in the first protective layer 114. In this way, the blocking surface formed by the protective layers of the first composite pole piece 11 and the second composite pole piece 12 can fully cover the XY plane of the pole piece in the battery 10 to block the omnidirectional puncture of the pole piece in the XY plane.

[0108] The present application does not specifically limit the specific material and structure of the first protection portion 115. Optionally, the first protection portion 115 includes but is not limited to an insulating protection portion, a conductive protection portion, etc. The present application specifically illustrates the specific structure of the first protection portion 115 through the following implementation. The material and structure of the second protection portion 125 can refer to the material and structure of the first protection portion 115, and the present application does not further limit the material and structure of the second protection portion 125.

[0109] In a first possible implementation of the first protection portion 115, see Fig.28 The first protection portion 115 includes a protection body 151 and a conductive portion 152 .

[0110] The conductive part 152 is arranged on the surface or inside of the protective body 151. The conductive part 152 is used to electrically conduct with the first current collecting body 111. The present application does not specifically limit the specific structure of the conductive part 152. The conductive part 152 includes at least one of a plurality of conductive particles, conductive columns, conductive wires, conductive meshes, conductive sheets, and conductive rods. The material of the conductive part 152 includes but is not limited to at least one of carbon nanotubes, graphene, conductive graphite, carbon black, carbon fiber, graphite, conductive ceramic powder, and composite conductive materials; it can also be at least one of aluminum, copper, nickel, copper, cobalt, tungsten, tin, lead, iron, silver, gold, platinum or their alloys.

[0111] Optionally, the protective body 151 can be an adhesive to connect the conductive part 152 to the first current collecting body 113, and also has good elongation, so that the first protective part 115 has good elongation and high conductivity. The material of the protective body 151 includes but is not limited to at least one of vinylidene fluoride, vinylidene fluoride-fluorinated olefin copolymer, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, fluorinated rubber, polyvinyl alcohol, polyvinylidene fluoride, and polyamide.

[0112] The specific structure of the conductive portion 152 is described below with reference to the accompanying drawings.

[0113] For a first possible implementation of the conductive portion 152, please refer to Fig.28 The conductive portion 152 is a plurality of conductive pillars 152 a. The plurality of conductive pillars 152 a can be arranged at intervals or connected. At least some of the plurality of conductive pillars 152 a completely penetrate the protection body 151 .

[0114] Optionally, each conductive column 152a completely penetrates the protection body 151. Figure 7 When the first protective layer 114 is disposed in the first current collecting body 113, the opposite ends of each conductive column 152a directly contact the first current collecting body 113 to conduct electricity inside the first current collecting body 113. Figure 8 When the first protective layer 114 is disposed on the surface of the first current collecting body 113 , opposite ends of each conductive column 152 a directly contact the first current collecting body 113 and the first active material layer 112 to conduct electricity between the first current collecting body 113 and the first active material layer 112 .

[0115] Optionally, a portion of the conductive column 152a completely penetrates the protective body 151, and another portion of the conductive column 152a is arranged inside the protective body 151 and does not completely penetrate the protective body 151. The conductive column 152a that does not completely penetrate the protective body 151 can be electrically connected to the conductive column 152a that completely penetrates the protective body 151, so as to achieve electrical conduction of the conductive column 152a to the interior of the first current collecting body 113 or between the first current collecting body 113 and the first active material layer 112, thereby further increasing the conductive performance of the first current collecting body 113.

[0116] By providing a plurality of conductive pillars 152 a , electrical conduction can be achieved inside the first current collector 113 or between the first current collector 113 and the first active material layer 112 , further improving the conductivity of the first current collector 113 , and increasing the structural strength of the first composite current collector 111 .

[0117] For a second possible implementation of the conductive portion 152, please refer to Fig.29 , the conductive part 152 is a conductive mesh. The protective body 151 is an adhesive filled in the gaps of the conductive mesh. In this embodiment, the conductive part 152 has a simple structure. The conductive mesh structure makes the first protective part 115 have a certain toughness. Combined with the adhesive filled in the conductive mesh, the first protective part 115 has high toughness and deformation ability to resist puncture penetration, effectively prevent puncture short-circuiting adjacent positive and negative electrodes, and improve the safety of the battery 10.

[0118] For a third possible implementation of the conductive portion 152, please refer to Fig.30 , the conductive part 152 is conductive particles, and the protective body 151 is a glue layer. The conductive part 152 is mixed in the protective body 151 to form a glue layer with conductive ability. In this way, the first protective part 115 has good extensibility. At the same time, a certain concentration of conductive particles is evenly arranged in the glue layer, which realizes good conductivity of the first protective part 115, improves the anti-puncture ability of the first composite current collector 111, and can also improve the conductivity of the first composite current collector 111.

[0119] By providing conductive particles on the first protection portion 115 , the current collecting performance of the first composite current collector 111 can be improved. By providing an adhesive layer on the first protection portion 115 , the adhesive layer has viscosity and good elongation performance, which can prevent the first composite current collector 111 from being punctured.

[0120] In a fourth possible implementation of the conductive portion 152 , the conductive portion 152 and the protective body 151 are located in the same layer and have complementary pattern structures, so that the conductive portion 152 and the protective body 151 form a first protective portion 115 that has both conductive properties and puncture resistance.

[0121] In a second possible implementation of the first protection portion 115, see Fig.31 The first protection portion 115 includes a protection body 151 and an active material portion 153 .

[0122] Optionally, the protective body 151 is an adhesive, and the material of the protective body 151 includes but is not limited to at least one of vinylidene fluoride, vinylidene fluoride-fluorinated olefin copolymer, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, fluorinated rubber, polyvinyl alcohol, polyvinylidene fluoride, and polyamide.

[0123] The active material part 153 is disposed on the surface or inside of the protective body 151. The active material part 153 is used to generate an electrochemical reaction with the electrolyte 13. The material of the active material part 153 includes but is not limited to at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based material, and lithium nickel cobalt aluminum oxide.

[0124] By setting an active material portion 153 in the first protection portion 115, the material of the active material can be the same as the material of the first active material layer 112. The function of the active material is the same as that of the first active material layer 112, and both are used to react with the electrolyte 13 to form more lithium ions, thereby increasing the energy density of the battery 10.

[0125] For the second composite current collector 121, the structure of the second protection portion 125 can refer to the structure of the first protection portion 115. The material of the active material portion 153 of the second protection portion 125 is but not limited to graphite, carbon fiber, graphene, lithium titanate, etc. The active material portion 153 of the second protection portion 125 is used to react with the electrolyte 13 to generate more electrons, thereby improving the energy density of the battery 10.

[0126] Optional, see Fig.32 , the first protective layer 114 is embedded in the first current collecting body 113. The first current collecting body 113 has at least one bearing surface 113c for setting the first active material layer 112. The first current collecting body 113 also includes at least one through hole 113d. One end of the through hole 113d is opened on the bearing surface 113c. The other end of the through hole 113d is opened directly opposite to the first protective portion 115. The through hole 113d is used to fill part of the first active material layer 112.

[0127] Specifically, for the embodiment in which the first protection layer 114 is embedded in the first current collector 113, the active material portion 153 in the first protection portion 115 cannot contact the electrolyte 13. In this embodiment, a through hole 113d is provided on the first current collector 113, and the through hole 113d connects the first active material layer 112 and the first protection portion 115, so that the active material portion 153 in the first protection portion 115 can contact the electrolyte 13 through the through hole 113d, thereby promoting the generation of lithium ions, and improving the energy density of the battery 10 while achieving puncture and collision protection for the battery 10.

[0128] Furthermore, the number of through holes 113d is multiple. Multiple through holes 113d are provided on one side or two opposite sides of the first protection portion 115. When the first active material layer 112 is provided on both opposite sides of the first current collector 113, by providing through holes 113d on both opposite sides of the first protection portion 115, the active material in the first protection portion 115 can contact the first active material layer 112 from the through holes 113d on both sides, thereby increasing the concentration and speed of lithium ion generation, further increasing the energy density of the battery 10 and improving the utilization rate of the active material portion 153 in the first protection portion 115.

[0129] In a third possible implementation of the first protection portion 115, see Fig.33 The first protection portion 115 includes a porous structure 154 and a plurality of magnetic particles 155 disposed in the porous structure 154 . The magnetic particles 155 are disposed in the porous structure 154 and are capable of moving in the holes of the porous structure 154 .

[0130] Specifically, the porous structure 154 includes but is not limited to at least one of nanoporous material, fiber porous material, and foam porous material. The particle size of the magnetic particles 155 is smaller than the pore size inside the porous structure 154, so that the magnetic particles 155 can move in the porous structure 154. In this embodiment, the porous structure 154 can be a conductive material or a non-conductive material.

[0131] During the puncture test of the battery 10, a steel needle is used to perform the puncture test on the battery 10. When the tip of the steel needle enters the first protection portion 115, the magnetic particles 155 in the first protection portion 115 are adsorbed on the surface of the tip of the steel needle under the attraction of the steel needle. A large number of magnetic particles 155 are adsorbed on the tip of the steel needle, making the puncture tip no longer sharp, thereby reducing the puncture force of the tip of the steel needle on the first protection portion 115, thereby increasing the steel needle's ability to further penetrate the first protection portion 115, and increasing the pass rate of the puncture test of the battery 10, thereby improving the safety of the battery 10.

[0132] Optionally, the material of the magnetic particles 155 is a conductive material. For example, the material of the magnetic particles 155 includes but is not limited to at least one of iron, cobalt, and nickel.

[0133] By arranging conductive magnetic particles 155 in the first protective portion 115, on the one hand, the magnetic particles 155 can be adsorbed on the surface of the puncture tip when the puncture tip enters the first protective portion 115, so that the puncture tip is passivated to prevent the puncture tip from further piercing the first protective portion 115, thereby preventing the first composite pole piece 11 from being penetrated, thereby improving the safety performance of the battery 10; on the other hand, the magnetic particles 155 can improve the conductivity of the first protective portion 115, thereby improving the conductivity of the first composite current collector 111.

[0134] Optional, see Fig.34 , the magnetic particle 155 includes a magnetic core 157 and an insulating coating layer 158 covering the magnetic core 157. The magnetic core 157 includes but is not limited to at least one of iron, cobalt, and nickel particles. The magnetic core 157 is used to make the magnetic particle 155 magnetic, so as to prevent the steel needle from further penetrating on the surface of the steel needle tip when the steel needle tip pierces the first protective portion 115. The insulating coating layer 158 includes but is not limited to an insulating rubber layer, and the insulating coating layer 158 is coated on the magnetic core 157 to make the surface of the magnetic particle 155 insulating.

[0135] When the steel needle pierces the first protective portion 115, the magnetic particles 155 can be adsorbed on the surface of the puncture tip when the puncture tip enters the first protective portion 115, so that the puncture tip is passivated to prevent the puncture tip from further piercing the first protective portion 115, thereby preventing the first composite pole piece 11 from being penetrated, thereby improving the safety performance of the battery 10; at the same time, the surface of the magnetic particles 155 is an insulating material, and the magnetic particles 155 are adsorbed on the surface of the steel needle. The magnetic particles 155 insulate the steel needle from the first composite pole piece 11. Even if the steel needle penetrates two adjacent pole pieces, the steel needle cannot cause a short circuit between the two pole pieces, thereby effectively improving the safety of the battery 10.

[0136] In other words, the magnetic particles 155 with an insulating surface can be adsorbed on the surface of the steel needle when the steel needle pierces the first protective portion 115, thereby insulating the steel needle from the first composite pole piece 11. As a result, even if the steel needle penetrates the first composite pole piece 11 and the second composite pole piece 12, it is impossible to electrically conduct the first composite pole piece 11 and the second composite pole piece 12, thereby effectively avoiding a short circuit in the battery 10 and improving the safety of the battery 10.

[0137] The embodiment of the present application provides a composite current collector (the composite current collector refers to the first composite current collector 111 and / or the second composite current collector 112). By means of a protective portion (the protective portion refers to the first protective portion and / or the second protective portion) dispersedly distributed in the composite current collector of the battery 10, when the battery 10 encounters physical damage, the protective portion can utilize its own good ductility to protect the positive and negative electrode sheets from direct contact, thereby protecting the battery 10 from overheating and fire; at the same time, because of the dispersed distribution of the protective portion, the amount of the protective portion can be reduced, which can reduce the production cost on the one hand, and also reduce the weight of the battery 10.

[0138] The above is part of the implementation methods of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A composite current collector, characterized in that: include: Current collection body; and A protective layer is arranged on the current collecting body, the protective layer includes multiple protective parts, a hollow part is formed between two adjacent protective parts, the hollow part is used to form a conductive channel, and the elongation of the protective part is greater than the elongation of the current collecting body; the number of the protective layers is multiple, and the multiple protective layers are stacked in sequence and arranged at intervals along the thickness direction of the current collecting body, and the protective parts in two adjacent layers of the protective layers are at least partially staggered perpendicular to the thickness direction.

2. The composite current collector according to claim 1, characterized in that: At least part of the protective layer is disposed on the surface of the current collecting body, and at least part of the hollow portion is used to accommodate part of the active material layer; and / or at least part of the protective layer is embedded in the current collecting body, and at least part of the hollow portion is used to accommodate part of the current collecting body.

3. The composite current collector according to claim 1, characterized in that: The two adjacent protective layers include a first sub-protective layer and a second sub-protective layer, wherein the protective portion of the first sub-protective layer has an orthographic projection in the thickness direction of the current collecting body covering the hollow portion of the second sub-protective layer; and / or the protective portion of the second sub-protective layer has an orthographic projection in the thickness direction of the current collecting body covering the hollow portion of the first sub-protective layer.

4. The composite current collector according to claim 3, characterized in that: The current collecting body has a first surface and a second surface disposed opposite to each other, the first sub-protective layer is disposed on the first surface of the current collecting body; and / or the second sub-protective layer is disposed on the second surface of the current collecting body.

5. The composite current collector according to any one of claims 1 to 4, characterized in that: The protection part includes a protection body and a conductive part. The conductive part is arranged on the surface or inside of the protection body, and the conductive part is used for electrically conducting with the current collecting body.

6. The composite current collector according to claim 5, characterized in that: The conductive part includes at least one of a plurality of conductive particles, conductive columns, conductive wires, conductive meshes, conductive sheets, and conductive rods.

7. The composite current collector according to any one of claims 1 to 4, characterized in that: The protection part includes a protection body and an active material part. The active material part is arranged on the surface or inside of the protection body. The active material part is used to generate an electrochemical reaction with an electrolyte.

8. The composite current collector according to claim 7, characterized in that: The protective layer is embedded in the current collecting body, and the current collecting body has at least one bearing surface for setting the active material layer; the current collecting body also includes at least one through hole, one end of the through hole is opened and arranged on the bearing surface; the other end of the through hole is opened facing the protective layer, and the through hole is used to fill part of the active material layer.

9. The composite current collector according to claim 8, characterized in that: There are multiple through holes, and the multiple through holes are arranged on one side or two opposite sides of the protection layer.

10. The composite current collector according to any one of claims 1 to 4, characterized in that: The protection part includes a porous structure and a plurality of magnetic particles arranged in the porous structure.

11. The composite current collector according to claim 10, characterized in that: The material of the magnetic particles is conductive material.

12. The composite current collector according to claim 10, characterized in that: The magnetic particle includes a magnetic core and an insulating coating layer coating the magnetic core.

13. The composite current collector according to claim 10, characterized in that: The material of the porous structure includes at least one of a nanoporous material, a fiber porous material, and a foam porous material.

14. The composite current collector according to any one of claims 1 to 4, characterized in that: The protection portion is in a strip shape, and the hollow portion is in a strip shape; or, the protection portion is in a block shape, and the hollow portion is in a grid shape; or, the protection portion is in a grid shape, and the hollow portion is in a block shape.

15. A composite pole piece, characterized in that: The composite current collector comprises an active material layer and the composite current collector according to any one of claims 1 to 14, wherein the active material layer is arranged on one side or two opposite sides of the composite current collector.

16. The composite pole piece according to claim 15, characterized in that: The protective layer is arranged on the surface of the current collecting body layer, and the active material layer covers the protective portion and the hollow portion; or, the active material layer covers the protective portion and fills the hollow portion; or, the active material layer and the protective portion are located in the same layer and are arranged in the hollow portion.

17. A battery, characterized in that: Comprising a plurality of composite pole pieces as claimed in claim 15 or 16.

18. The battery according to claim 17, characterized in that The multiple composite pole pieces include a first composite pole piece and a second composite pole piece, and the battery also includes a diaphragm, which is arranged between the first composite pole piece and the second composite pole piece, and the protective layer of the first composite pole piece and the protective layer of the second composite pole piece are at least partially staggered in a direction perpendicular to the thickness direction of the first composite pole piece.

19. An electronic device, characterized in that: Comprising a battery as claimed in claim 17 or 18.

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