WO2022100280A1

WO2022100280A1 - Composite current collector, composite pole piece, battery, and electronic device

Info

Publication number: WO2022100280A1
Application number: PCT/CN2021/119083
Authority: WO
Inventors: 谢红斌
Original assignee: Oppo广东移动通信有限公司
Priority date: 2020-11-16
Filing date: 2021-09-17
Publication date: 2022-05-19
Also published as: CN114512677A

Abstract

Provided in the present application are a composite current collector, a composite pole piece, a battery, and an electronic device. The composite current collector comprises a current collecting body and a protective layer. The current collecting body is provided on the current collecting body. The protective layer comprises a plurality of protective portions. A hollow portion is formed between two adjacent protection portions. The elongation rate of the protection portion is greater than the elongation rate of the current collecting body. The composite current collector and the composite pole piece provided in the present application can prevent short circuits between positive and negative pole pieces and increase the safety performance of a battery.

Description

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

technical field

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

Background technique

Rechargeable batteries, such as lithium batteries, are widely used in electric vehicles and consumer electronics due to their advantages of high energy density, high output power, long cycle life, and low environmental pollution. However, when the rechargeable battery is squeezed, collided or punctured, it is easy to cause a short circuit between the positive and negative plates, which will cause the thermal runaway of the cell to fail, and it is likely to catch fire and 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 to be solved.

SUMMARY OF THE INVENTION

The present application provides a composite current collector, a composite pole piece, a battery and an electronic device that prevent the short-circuit between the positive and negative electrodes and improve the safety performance of the battery.

In a first aspect, an embodiment of the present application provides a composite current collector, including:

collector body; and

A protective layer is arranged on the current collecting body, the protective layer includes a plurality of protective parts, a hollow part is formed between two adjacent protective parts, and the elongation rate of the protective parts is greater than that of the current collecting body elongation.

In a second aspect, an embodiment of the present application provides a composite pole piece, which includes an active material layer and the composite current collector, and the active material layer is disposed on one side or opposite sides of the composite current collector.

In a third aspect, an embodiment of the present application provides a battery including a plurality of the composite pole pieces.

In a fourth aspect, an embodiment of the present application provides an electronic device, including the battery.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present application more clearly, the following briefly introduces the accompanying drawings used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

1 is a schematic structural diagram of an electronic device provided by an embodiment of the present application;

Fig. 2 is the structural exploded schematic diagram of a kind of electronic equipment provided by Fig. 1;

3 is a circuit block diagram of a battery electrically connected to an external power supply provided by an embodiment of the present application;

Figure 4 is a perspective view of the battery provided in Figure 2;

5 is a cross-sectional view of the battery provided in FIG. 2;

Fig. 6 is the first partial cross-sectional view of the cell in the battery provided in Fig. 5;

Fig. 7 is the sectional view of the first kind of first composite pole piece that Fig. 6 provides;

Fig. 8 is the sectional view of the second kind of first composite pole piece that Fig. 6 provides;

Fig. 9 is the sectional view of the third kind of first composite pole piece that Fig. 6 provides;

Fig. 10 is the sectional view of the 4th kind of first composite pole piece that Fig. 6 provides;

Fig. 11 is the sectional view of the 5th kind of first composite pole piece that Fig. 6 provides;

Fig. 12 is the sectional view of the sixth kind of first composite pole piece that Fig. 6 provides;

Fig. 13 is the sectional view of the seventh kind of first composite pole piece that Fig. 6 provides;

Fig. 14 is the sectional view of the eighth kind of first composite pole piece that Fig. 6 provides;

Fig. 15 is the sectional view of the ninth kind of first composite pole piece that Fig. 6 provides;

Fig. 16 is the sectional view of the tenth kind of first composite pole piece that Fig. 6 provides;

Fig. 17 is the sectional view of the eleventh kind of first composite pole piece that Fig. 6 provides;

Figure 18 is a cross-sectional view of the twelfth first composite pole piece provided by Figure 6;

Fig. 19 is the sectional view of the thirteenth kind of first composite pole piece that Fig. 6 provides;

FIG. 20 is a second cross-sectional view of the cell in the battery provided in FIG. 5;

Figure 21 is a third cross-sectional view of the cell in the battery provided in Figure 5;

Figure 22 is a fourth cross-sectional view of the cell in the battery provided in Figure 5;

Figure 23 is a top view of the first protective layer provided in Figure 6;

Figure 24 is a top view of the second type of protective layer provided in Figure 6;

Figure 25 is a top view of the third protective layer provided in Figure 6;

Figure 26 is a top view of the fourth protective layer provided in Figure 6;

Figure 27 is a cross-sectional view of the fourteenth first composite pole piece provided by Figure 6;

Figure 28 is a sectional view of the first protection part provided in Figure 7;

Figure 29 is a top view of the second type of protection part provided in Figure 7;

Figure 30 is a sectional view of the third protection part provided in Figure 7;

Figure 31 is a sectional view of the fourth protection part provided in Figure 7;

Figure 32 is a sectional view of the fifth protection part provided in Figure 7;

Figure 33 is a sectional view of the fifth protective layer provided in Figure 6;

FIG. 34 is a cross-sectional view of the sixth protective layer provided in FIG. 6 .

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments. The embodiments listed in this application can be appropriately combined with each other.

Please refer to FIG. 1 , which is a schematic structural diagram of an electronic device according to an embodiment of the present application. The 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, and the like. Referring to FIG. 1 , in this application, the electronic device 100 is a mobile phone as an example for description. For ease of description, the electronic device 100 is defined with reference to the 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.

Referring to FIG. 2 , the electronic device 100 includes a battery 10 . In this embodiment, the electronic device 100 is a mobile phone. The electronic device 100 further 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 provided in the middle frame 30 . The battery 10 is used to supply power to the display screen 20 and the main board 60 disposed on the middle frame 30 and other devices.

The battery 10 includes, but is not limited to, 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, All solid-state batteries such as nickel-metal hydride batteries, lithium-ion batteries, iron batteries, nano batteries, etc. The embodiments of the present application are described by taking the battery 10 as a lithium ion battery as an example.

The present application does not specifically limit the shape of the battery 10 . The battery 10 can be in the form of a column, a bag, an arc, a soft-packed square, a cylinder, a diamond column, a special shape, or the like. Classified according to the charging method, the battery 10 described in this application includes but is not limited to a wired rechargeable battery and a wireless rechargeable battery. The embodiments of the present application are described by taking the battery 20 as an example of a wired rechargeable battery.

Referring to FIG. 2 , the electronic device 100 further includes a charging interface 50 and a charging control unit 70 .

Referring to FIG. 2 , the charging interface 50 is disposed on the middle frame 30 , so that the charging interface 50 is connected to an external power source 200 (hereinafter referred to as the power source 200 ). Specifically, the charging interface 50 may be connected to the power source 200 through a charging cable. The types of the charging interface 50 include, but are not limited to, the Micro USB interface, the USB Type C interface of mobile phones with Android and Windows phone systems, and the Lightning interface of mobile phones with IOS system.

Referring to FIG. 3 , the charging control unit 70 is connected to the charging interface 50 and the battery 10 . The charging control unit 70 may be a packaged integrated chip. The charging control unit 70 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 for the battery 10 .

Referring to FIG. 3 , the conductive terminals of the power supply 200 include a first power supply terminal 210 and a second power supply terminal 220 . The first power supply terminal 210 is the positive terminal of the power supply 200 , and the second power supply terminal 220 is the negative terminal of the power supply 200 ; or, the first power supply terminal 210 is the negative terminal of the power supply 200 , and the second power supply terminal 220 is the positive terminal of the power supply 200 . extreme. In this embodiment, the first power terminal 210 is the positive terminal, and the second power terminal 220 is the negative terminal. The charging interface 50 includes a first charging terminal 501 and a second charging terminal 502 . When the charging interface 50 is electrically connected to the power supply 200, the first charging terminal 501 is connected to the first power terminal 210, and the second charging terminal 502 is connected to the second power terminal 220. At this time, the current flows from the first power terminal 210 to the first charging terminal in sequence. The terminal 501 , the charging control unit 70 , the positive pole 101 of the battery 10 , the negative pole 102 of the battery 10 , and the second charging terminal 502 flow to the second power terminal 220 , and the battery 10 is in a charging state.

The specific structure of the battery 10 provided in the embodiments of the present application will be described below with reference to the accompanying drawings.

Referring to FIG. 4 , the battery 10 includes a battery cell 1 , a protection plate 2 and a packaging case 3 . The protection board 2 is electrically connected to the battery cell 1 for protecting the battery cell 1 from overvoltage, undervoltage, overcurrent, short circuit, and overtemperature states and prolonging the service life of the battery 10 . The encapsulation case 3 is used to encapsulate the battery cell 1 and the protection board 2 . The packaging case 3 includes, but is not limited to, an aluminum case, a steel case, an aluminum-plastic film, and the like. In this embodiment, the packaging case 3 is an aluminum-plastic film.

Referring to FIG. 5 , the battery core 1 includes a first composite pole piece 11 , a second composite pole piece 12 , an electrolyte 13 and a separator 14 . The first composite pole piece 11 is a positive pole piece, and the second composite pole piece 12 is a negative pole piece; or, the first composite pole piece 11 is a negative pole piece, and the second composite pole piece 12 is a positive pole piece. In this embodiment, the first composite pole piece 11 is a positive electrode piece, and the second composite pole piece 12 is a negative electrode piece.

Referring to FIG. 6 , the first composite pole piece 11 includes a first composite current collector 111 and a first active material layer 112 disposed on the first composite current collector 111 .

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

The number of the first active material layers 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 first composite current collector The ability of 111 to absorb or generate electrons in an electrochemical reaction increases the energy density of the battery 10 . In other embodiments, the first active material layer 112 is provided 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, such as lithium iron phosphate, lithium iron manganese phosphate, with high electrode potential and stable structure with lithium intercalation capability. , at least one of lithium vanadium phosphate, lithium vanadium phosphate, lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate, lithium-rich manganese-based materials, lithium nickel cobalt aluminate, and the like.

Referring to FIG. 6 , the second composite pole piece 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 layers 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 second composite current collector The ability of 121 to generate or absorb electrons increases the energy density of the battery 10 . In other embodiments, the second active material layer 122 is provided on one surface of the second composite current collector 121 .

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

Referring to FIG. 6 , the first composite pole piece 11 , the diaphragm 14 and the second composite pole piece 12 are all 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 and the second composite pole piece 12 from directly contacting. 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 conducting, the battery 10 is short-circuited, and the current inside the battery 10 increases instantaneously and sharply, causing the internal The temperature rises sharply, and the active material layer and the electrolyte 13 inside the battery 10 are prone to safety problems such as explosion under high temperature. The diaphragm 14 is a specially shaped polymer film. The diaphragm 14 has a microporous structure, which allows lithium ions to pass freely, but electrons cannot pass through, so that the gap between the first composite pole piece 11 and the second composite pole piece 12 can be passed. The electrochemical reaction is carried out, 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.

Optionally, the number of the first composite pole piece 11 and the second composite pole piece 12 is one, and a first composite pole piece 11 , one or more diaphragms 14 , and a second composite pole piece 12 are stacked in sequence and then wound. The wound cell 1 is formed.

Optionally, the number of the first composite pole piece 11 , the second composite pole piece 12 , and the diaphragm 14 is all plural. The first composite pole piece 11 , the separator 14 , the second composite pole piece 12 , the separator 14 , the first composite pole piece 11 , and the separator 14 are stacked in sequence to form a laminated cell 1 .

Please refer to FIG. 5 , optionally, the electrolyte 13 can be an organic solvent in which an electrolyte lithium salt is dissolved to provide lithium ions. The electrolyte lithium salt includes LiPF6, LiClO4, LiBF4, etc., and the organic solvent is mainly composed of diethyl carbonate (DEC ), propylene carbonate (PC), ethylene carbonate (EC), dimethyl ester (DMC), etc. One or more of them are mixed. The first composite pole piece 11, the second composite pole piece 12 and the diaphragm 14 are packaged in the encapsulation shell 3, and the electrolyte 13 is injected into the encapsulation shell 3, so that the first composite pole piece 11 and the second composite pole piece 12 are soaked in into the electrolyte 13 , and encapsulate the protective plate 2 in the encapsulation case 3 to form the battery 10 .

During the charging and discharging process of the battery 10 , Li+ is intercalated and deintercalated back and forth between the first composite pole piece 11 and the second composite pole piece 12 . During charging, Li+ is deintercalated from the first composite pole piece 11 (positive electrode), and inserted into the second composite pole piece 12 (negative electrode) through the electrolyte, and the second composite pole piece 12 is in a lithium-rich state. The opposite is true when discharging.

Further, please refer to FIG. 5 , the battery cell 1 further includes a first tab 16 and a second tab 17 . The first tab 16 is electrically connected to the first composite pole piece 11 , and the second tab 17 is electrically connected to the second composite pole piece 12 . One end of the first tab 16 away from the first composite pole piece 11 is electrically connected to the protection plate 2 , and one end of the second tab 17 away from the second composite pole piece 12 is electrically connected to the protection plate 2 , so that the protection plate 2 is electrically connected to the protection plate 2 for the cell 1 . Charge and discharge are managed.

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

Generally speaking, the battery 10 is prone to short-circuit of the positive and negative electrodes under abnormal conditions such as collision, extrusion, puncture, etc., thereby causing a safety problem 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 a short circuit of the battery 10 when the battery 10 is punctured by the steel needle. The lower the probability of short circuit of the battery 10 in the case of acupuncture with a steel needle, the higher the pass rate of the battery 10 for mechanical tests such as acupuncture 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 likely to occur in a low temperature environment, and the lithium crystallization is likely to pierce the pole pieces inside the battery 10 and cause the battery 10 to short-circuit. The puncture described in the present application includes, but is not limited to, the steel needle in the puncture test and the lithium crystallization produced by the electrochemical reaction inside the battery 10, and the like.

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 electrode The piece 11 and the second composite pole piece 12 have strong puncture stability, and have a high pass rate under 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 under abnormal conditions such as puncture and impact, thereby reducing the occurrence of battery 10. The probability of short circuit can effectively improve the safety of the battery 10 .

The structure of the first composite current collector 111 is exemplified 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 .

Referring to FIG. 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 this 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 of the first protective layer 114 and the first current collecting body 113 . Specifically, the first protective layer 114 can be formed with the first current collecting body 113 by at least one of coating, calendering, rolling, bonding, evaporation, vapor deposition, chemical deposition, magnetron sputtering, and electroless plating. compound. Further, this application does not specifically limit the specific position where the first protective layer 114 is provided on the first current collecting body 113 . In other words, the first protective layer 114 can be provided on the surface of the first current collecting body 113 , or can be in the first collector body 113 .

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

The elongation of the first protective layer 114 is greater than that of the first current collector body 113 . Elongation is an index describing the plastic properties of a material. The elongation is the percentage of the ratio of the total deformation ΔL of the gauge length section to the original gauge length L after tensile fracture of the sample: δ=ΔL/L×100%. The greater the elongation, the greater the deformation of the material after tensile fracture, in other words, the less likely the material to break. That is, the fracture resistance of the first protective layer 114 is greater than the fracture resistance of the first current collector body 113 . When the puncture pierces the first composite pole piece 11, since the first protective layer 114 has a large elongation rate, the first protective layer 114 can effectively block the puncture effect through deformation, so as to prevent the puncture from penetrating the first composite pole piece 11. In this way, the pole piece 11 can prevent the first composite pole piece 11 and the second composite pole piece 12 from being punctured and conducted, thereby causing the positive and negative pole pieces of the battery 10 to be short-circuited.

The material of the first protective layer 114 includes, but is not limited to, adhesives, porous stretchable structures, and the like. Among them, the binder includes but is not limited to polyvinylidene fluoride, vinylidene fluoride-fluorinated olefin copolymer, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, fluorinated rubber, poly At least one of vinyl alcohol, polyvinylidene fluoride, polyamide and the like. Porous stretchable structures include, but are not limited to, nano-stretchable structures, cellular foam structures, and fibrous cellular structures.

In one embodiment, the material of the first protective layer 114 is an insulating material, for example, the first protective layer 114 is an adhesive layer. When the first protective layer 114 is a whole-layer design, and the first protective layer 114 is disposed in the first current collecting body 113 , the first protective layer 114 blocks the first current collecting body 113 on opposite sides of the first protective layer 114 from conducting electrical conduction . When the first protective layer 114 is a whole-layer design, and the first protective layer 114 is disposed between the first current collector body 113 and the first active material layer 112 , the first protective layer 114 blocks the first protective layer 114 on the opposite sides of the first protective layer 114 . The current collector body 113 is electrically connected to the first active material layer 112 , and thus, the electrical conductivity of the first current collector body 113 is weakened.

In this embodiment, please refer to FIG. 7 , the first protection layer 114 includes a plurality of first protection portions 115 , and a first hollow portion 116 is formed between two adjacent first protection portions 115 . The elongation of the first protection portion 115 is greater than that of the first current collecting body 113 . The first protection part 115 protects the first composite current collector 111 to prevent the first composite current collector 111 from being punctured by puncture. The first hollow parts 116 are disposed between two adjacent first protection parts 115, so that the first current collecting bodies 113 on opposite sides (in the Z-axis direction) of the first protection layer 114 can contact each other and Conduction, so that the first current collector body 113 on opposite sides (in the Z-axis direction) of the first protective layer 114 will not be insulated, thereby improving the electrical conductivity of the first composite current collector 111 .

In this embodiment, the first protective layer 114 has a patterned structure relative to the first current collector body 113 . Optionally, the first hollow portion 116 in the first protective layer 114 is used to accommodate a part of the first current collecting body 113, so that the electrical conduction inside the first current collecting body 113 is good, so as to avoid the first protective layer. 114 separates the first current collecting body 113 into two mutually insulated conductive parts, so as to realize good electrical conduction inside the first current collecting body 113; The problem that the first current collector body 113 cannot achieve electrical conduction between the first tab 16 and the first active material layer 112 due to the isolation of the active material layer 112 improves the performance of the first current collector body 113 and the first active material layer. Conductivity between 112.

The first composite current collector 111 provided in this embodiment includes a plurality of first protection parts 115 by arranging the first protection layer 114 , and a first hollow part 116 is formed between two adjacent first protection parts 115 . A protection portion 115 can provide a higher elongation rate to effectively resist puncture penetrating the first composite pole piece 11 , thereby improving the resistance of the battery 10 to puncture, thereby improving the safety of the battery 10 ; in addition, the first hollow portion 116 The first protective layer 114 is reserved for conductive channels on both sides of the first protective layer 114, so that the first current collector bodies 113 on the opposite sides of the first protective layer 114 can be electrically conducted well, or, the first protective layer 114 can be relatively The first current collector body 113 and the first active material layer 112 on the side can be electrically connected to realize the electrical conductivity of the first current collector body 113, so that the battery 10 can be charged and discharged normally; in addition, on the first composite current collector 111 Providing the patterned first protective layer 114 can reduce the material of the first protective layer 114 , save costs and reduce the overall weight of the battery 10 .

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 to prevent puncture, and the first hollow portion 116 of the first protective layer 114 is a conductive channel on the first composite current collector 111 In this way, the first protective layer 114 can not only effectively protect the puncture, but also ensure that the first composite current collector 111 has high conductivity.

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

In this embodiment, the present application does not limit the number, arrangement and shape of the first protection portions 115 .

Please refer to FIG. 7 and FIG. 8 , the first protective layer 114 disposed on the first current collecting body 113 includes, but is not limited to, at least part of the first protective layer 114 is embedded in the first current collecting body 113 ; and/or, At least part of the first protective layer 114 is disposed on the outer surface of the first current collecting body 113 .

Specifically, this embodiment does not specifically limit the number of the first protective layers 114 . In one embodiment, please refer to FIG. 8 , the number of the first protective layer 114 is one, and all the first protective layers 114 are disposed on the outer surface of the first current collector body 113 ; or, please refer to FIG. 9 , the first protective layer 114 is A part of 114 is disposed on the outer surface of the first current collecting body 113 , and the other part is embedded in the first current collecting body 113 ; or, please refer to FIG. 7 , the first protective layer 114 is entirely disposed in the first current collecting body 113 . In another possible implementation manner, the number of the first protective layers 114 is two or more. For example, the number of the first protective layers 114 is two. Please refer to FIGS. 10 to 12 , the two first protective layers 114 are respectively disposed on the first surface 113 a and the second surface 113 b of the first current collector body 113 opposite to each other, and the two first protective layers 114 are in the Z-axis direction. Alternatively, please refer to FIG. 13 to FIG. 15 , one first protective layer 114 is disposed on the first surface 113 a or the second surface 113 b of the first current collecting body 113 , and the other The first protective layer 114 is disposed in the first current collecting body 113 , and the two first protective layers 114 can be arranged in the Z-axis direction facing each other, partially staggered or completely staggered; or, please refer to FIGS. 16 to 18 , two Each of the first protective layers 114 is completely disposed in the first current collector body 113 , and the two first protective layers 114 can be disposed in the Z-axis direction facing each other, partially staggered, or completely staggered.

Optionally, please refer to FIG. 9 and FIG. 10 , when at least part of the first protective layer 114 is disposed on the outer surface of the first current collecting body 113 , at least part of the first hollow part 116 is used to accommodate the first active part of the part. Material layer 112 . In other words, at least part 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 , so as to realize Good electrical conduction can be achieved between the first tab 16 , the first current collector body 113 and the first active material layer 112 .

Optionally, please refer to FIG. 8 , the first protective layer 114 is disposed on the surface of the first current collector 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 protection portion 115 and the first hollow portion 116 . Further, the first active material layer 112 may be disposed in the first hollow portion 116 .

Optionally, please refer to 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 protection portion 115 are located on the same layer. In other words, the first active material layer 112 may fill the entire first hollow portion 116 . The first active material layer 112 and the first protection 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; It has higher protection capability, thereby improving the safety performance of the battery 10 .

Optionally, please refer to FIG. 7 and FIG. 9 , when at least part of the first protective layer 114 is embedded in the first current collecting body 113 , at least part of the first hollow part 116 is used to accommodate a part of the first current collecting body body 113 . In other words, at least a part of the first current collecting body 113 is disposed in the first hollow portion 116 , on the one hand, the first current collecting body 113 is covered on the first protective layer 114 , and the distance between the first current collecting body 113 and the first protective layer 114 is improved. This reduces the overall volume of the first composite current collector 111 , and on the other hand enables the first current collector body 113 to have better conductivity even if the first protective layer 114 is embedded.

The above is an example of the specific structure of the first composite current collector 111. The structure of the second composite current collector 121 in the present application is roughly similar to that of the first composite current collector 111. Please refer to FIGS. 20 to 22. The current collector 121 includes a second current collecting body 123 and a second protective layer 124 disposed on the second current collecting body 123. The second protective layer 124 includes a plurality of second protective parts 125, and two adjacent second protective parts A second hollow portion 126 is formed between 125 . The second protection portion 125 and the first protection portion 115 are completely opposite to each other in the Z-axis direction, partially offset, or completely offset. The positional relationship between the second protective layer 124 and the second current collecting body 123 may refer to the positional relationship between the first protective layer 114 and the first current collecting body 113 . The materials of the first protective layer 114 and the second protective layer 124 are the same, and the materials of the first current collecting body 113 and the second current collecting body 123 are different. For example, the first current collecting body 113 is aluminum foil, and the second current collecting body 123 is copper foil. The shapes of the second protection portion 125 and the first protection portion 115 may be the same or different, and the shapes of the first hollow portion 116 and the second hollow portion 126 may be the same or different.

It can be understood that the first composite current collector 111 and the second composite current collector 121 above can be used for the wound cell 1 structure and the laminated cell 1 structure. When the first composite current collector 111 and the second composite current collector 121 When the current collector 121 is applied to the laminated cell 1 structure, some of the pole pieces in the laminated cell 1 structure may be composite pole pieces, or it may be all the pole pieces in the laminated cell 1 structure. The plates are all composite pole pieces to improve the safety of the battery 10 .

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

In a possible embodiment, please refer to 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. The plurality of first protection portions 115 and the plurality of 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 are both along the X The axial direction, the Y-axis direction, or the direction inclined with respect to the X-axis direction and the Y-axis direction extends. In other embodiments, the first protection portion 115 and the first hollow portion 116 may also be in the shape of a triangular strip, a diamond strip, a wavy strip, and the like. The present application does not specifically limit the number and size of the first protection portion 115 .

In a possible embodiment, please refer to 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, and the like. The plurality of first protection portions 115 may be arranged in multiple rows and columns, or may be arranged in a staggered manner.

In a possible embodiment, please refer to 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.

In one embodiment, please refer to FIG. 27 , the number of the first protective layers 114 is plural. The plurality of first protective layers 114 are stacked in sequence along the thickness direction of the first current collector body 113 (ie, the Z-axis direction) and are arranged at intervals. The first protection portions 115 in the two adjacent first protection layers 114 are arranged at least partially staggered in the direction perpendicular to the thickness. The first protection portions 115 in the two adjacent layers of the first protection layers 114 are completely or partially staggered in the X-axis direction and/or the Y-axis direction. For example, two adjacent first protective layers 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 middle. In this way, on the X-Y plane, the blocking area formed by the first protection portion 115 is relatively large, which can resist more punctures at different positions, and further improve the safety of the battery 10; The protective layer 114, the multi-layer first protective layer 114 can block the puncture from the opposite sides of the first current collecting body 113, and then protect from the opposite sides of the first current collecting body 113, further improving the protection efficiency; Each of the first protective layers 114 is provided with a first hollow portion 116 , so even if the first composite current collector 111 is provided with multiple layers of the first protective layers 114 , it can still have good electrical conductivity.

Further, referring to FIG. 27 , the orthographic projection of the first protective portion 115 of the first sub-protective layer 114 a on the second sub-protective layer 114 b in the thickness direction of the first current collector body 113 completely covers or partially covers the second sub-protective layer 114 . The first hollow portion 116 of the protective layer 114b; and/or, the orthographic projection of the first protective portion 115 of the second sub-protective layer 114b in the thickness direction of the first current collector body 113 completely covers or partially covers the first sub-protective layer The first hollow portion 116 of 114a.

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 collector body 113 completely covers the first hollow portion 116 of the second sub-protective layer 114b; and the second sub-protective layer 114b. The orthographic projection of the first protective portion 115 of the 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 parts 115 of the two protective layers 114a and 114b are staggered to form a larger blocking area. In this way, the protective parts 115 of the first sub-protective layer 114a and the second sub-protective layer 114b can A full coverage is formed in the X-Y plane of a composite pole piece 11 to block punctures at various positions in the X-Y plane of the first composite pole piece 11, thereby further improving the safety of the battery 10; at the same time, on the first sub-protective layer 114a The first hollow portion 116 and the second hollow portion 126 on the second sub-protective layer 114b both form conductive channels, so that the entire first current collector body 113 has better electrical conductivity.

Further, the first sub-protective layer 114a is provided on the first surface 113a of the first current collecting body 113 ; and/or the second sub-protective layer 114b is provided on the second surface 113b of the first current collecting body 113 . In this embodiment, the first sub-protective layer 114a is disposed on the first surface 113a of the first current collector body 113 , and the second sub-protective layer 114b is disposed on the second surface 113b of the first current collector body 113 .

Generally speaking, disposing the first protective layer 114 in the first current collecting body 113 can prevent the puncture from penetrating through the first composite pole piece 11. However, one end of the puncture contacts the second active material layer 122 of the second composite pole piece 12, and the puncture The other end of the electrode pierces the first active material layer 112 of the first composite pole piece 11 and then contacts the first current collector body 113. At this time, the puncturing may still cause the first composite pole piece 11 and the second composite pole piece 12 to short-circuit.

Based on the above problems, in this embodiment of the present application, the first sub-protective layer 114a and the second sub-protective layer 114b are respectively disposed on two opposite outer surfaces of the first current collector body 113, so that the first sub-protective layer 114a and the second sub-protective layer 114b to protect from opposite sides of the first current collecting body 113, respectively. When one end of the puncture contacts the second active material layer 122 of the second composite pole piece 12, and the other end of the puncture pierces the first active material layer 112 of the first composite pole piece 11, the first sub-protective layer 114a blocks the The other end of the puncture is elongated and the other end that blocks the puncture contacts the first current collecting body 113, so that the puncture can effectively prevent the two adjacent pole pieces from being conducted.

Further, in the plurality of first composite pole pieces 11 , a first sub-protective layer 114 a and a second sub-protective layer 114 b are respectively provided on opposite sides of some of the first current collecting bodies 113 , or, all the first current collecting bodies A first sub-protection layer 114a and a second sub-protection layer 114b are provided on opposite sides of the 113 . Further, among the plurality of second composite pole pieces 12 , two layers of second protective layers 124 are respectively provided on opposite sides of some second current collector bodies 123 , or, on opposite sides of all second current collector bodies 123 . The second protective layers 124 on both sides are respectively provided.

By disposing at least double-layer patterned first protective layers 114 in the first composite pole piece 11 , and placing the first protective portions 115 in the double-layered first protective layers 114 in a direction perpendicular to the thickness of the first current collector body 113 The upper part is at least partially staggered, and the double-layer first protective layer 114 is arranged on the two opposite surfaces of the first current collector body 113, on the one hand, it increases the first protective part 115 in the first composite pole piece 11. The blocking area makes up for the deficiency that the first hollow part 116 in the single-layer first protective layer 114 does not have the first protective part 115; The patterned first protective layer 114 effectively protects the upper and lower sides of the first current collector body 113, further reduces the risk of short circuit of the battery 10, and improves the safety of the battery 10; on the other hand, the first protective layer The patterned arrangement of 114 can also enable effective electrical conduction between the first active material layers 122 on the upper and lower layers of the first current collector body 113 and the first current collector body 113 in the middle.

Referring to 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 the 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 the 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 collecting body 113 covers the second hollow portion 126 in the second protective layer 124 , and the second composite pole piece 12 The orthographic projection of the second protective layer 124 in the thickness direction of the second current collecting 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 X-Y plane of the pole piece in the battery 10 to block the omnidirectional puncture of the pole piece in the X-Y plane.

The 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, and the like. In the present application, the specific structure of the first protection part 115 is specifically illustrated by the following embodiments. For the material and structure of the second protection portion 125 , reference may be made 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 .

In the first possible implementation manner of the first protection portion 115 , please refer to FIG. 28 , the first protection portion 115 includes a protection body 151 and a conductive portion 152 .

The conductive portion 152 is disposed on the surface or inside of the protective body 151 . The conductive portion 152 is used for electrical conduction with the first current collector body 111 . The specific structure of the conductive portion 152 is not specifically limited in the present application, and the conductive portion 152 includes at least one of several conductive particles, conductive posts, conductive wires, conductive meshes, conductive sheets, and conductive rods. The material of the conductive portion 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 aluminum, copper, nickel, copper , at least one of cobalt, tungsten, tin, lead, iron, silver, gold, platinum or alloys thereof.

Optionally, the protective body 151 can be an adhesive, so as to connect the conductive part 152 to the first current collecting body 113 and have a good elongation rate, so that the first protective part 115 has a good elongation rate at the same time and higher conductivity. The material of the protection body 151 includes, but is not limited to, vinylidene fluoride, vinylidene fluoride-fluorinated olefin copolymer, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, fluorinated rubber, polyethylene At least one of alcohol, polyvinylidene fluoride, and polyamide.

The specific structure of the conductive portion 152 will be illustrated below with reference to the accompanying drawings.

In the first possible implementation of the conductive portion 152, please refer to FIG. 28, the conductive portion 152 is a plurality of conductive pillars 152a. The plurality of conductive pillars 152a may be arranged at intervals or connected. At least some of the conductive pillars 152a of the plurality of conductive pillars 152a completely penetrate the protective body 151 .

Optionally, each conductive post 152a completely penetrates the protective body 151 . Please also refer to FIG. 7 , when the first protective layer 114 is disposed in the first current collecting body 113 , opposite ends of each conductive column 152 a directly contact the first current collecting body 113 , so that the first current collecting body 113 Internal conduction. 8, when the first protective layer 114 is disposed on the surface of the first current collector body 113, the opposite ends of each conductive column 152a directly contact the first current collector body 113 and the first active material layer 112, so that the The first current collector body 113 and the first active material layer 112 are turned on.

Optionally, a part of the conductive pillars 152a completely penetrate the protective body 151, and another part of the conductive pillars 152a is disposed in the protective body 151 and does not completely penetrate the protective body 151, and the conductive pillars 152a that do not completely penetrate the protective body 151 can be electrically connected to the protective body 151. The conductive pillars 152a of the body 151 are protected, so as to realize the electrical conduction between the conductive pillars 152a to the inside of the first current collector body 113 or between the first current collector body 113 and the first active material layer 112, and further increase the first current collector Conductivity of the body 113 .

By arranging a plurality of conductive pillars 152a, it is possible to realize electrical conduction within the first current collecting body 113 or between the first current collecting body 113 and the first active material layer 112, and further increase the first current collecting body 113 The electrical conductivity can also increase the structural strength of the first composite current collector 111 .

In the second possible implementation of the conductive portion 152, please refer to FIG. 29, the conductive portion 152 is a conductive mesh. The protective body 151 is an adhesive filled in the gaps of the conductive meshes. The conductive part 152 in this embodiment has a simple structure, and the conductive mesh structure makes the first protection part 115 have a certain toughness. Combined with the adhesive filled in the conductive mesh, the first protection part 115 has high toughness and deformation ability , in order to resist the puncture of the puncture, effectively prevent the puncture from shorting the adjacent positive and negative plates, and improve the safety of the battery 10 .

In a third possible embodiment of the conductive portion 152, please refer to FIG. 30, the conductive portion 152 is conductive particles, and the protective body 151 is an adhesive layer. The conductive portion 152 is mixed in the protective body 151 to form a conductive adhesive layer. In this way, the prepared first protective portion 115 has good extensibility. Good electrical conductivity of the first protection portion 115 is achieved, and the puncture resistance of the first composite current collector 111 is improved, and the conductivity of the first composite current collector 111 can also be improved.

By arranging conductive particles on the first protection part 115, the current collecting performance of the first composite current collector 111 can be improved; The composite current collector 111 is pierced by the puncture.

In the fourth possible implementation of the conductive portion 152 , the conductive portion 152 and the protective body 151 are located on the same layer and have complementary pattern structures, so that the conductive portion 152 and the protective body 151 are formed to have both electrical conductivity and puncture resistance. The first protection part 115 .

In the second possible implementation of the first protection part 115 , please refer to FIG. 31 , the first protection part 115 includes a protection body 151 and an active material part 153 .

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

The active material part 153 is provided on the surface or inside of the protective body 151 . The active material portion 153 is used for electrochemical reaction with the electrolytic solution 13 . The material of the active material portion 153 includes, but is not limited to, lithium iron phosphate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, lithium cobalt oxide, lithium manganate, lithium nickelate, lithium nickel cobalt manganate, lithium rich manganese At least one of base materials, nickel cobalt lithium aluminate, and the like.

By disposing the 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, and the function of the active material is the same as that of the first active material layer 112, and both are used for Reacts with the electrolyte 13 to form more lithium ions, thereby increasing the energy density of the battery 10 .

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

Optionally, please refer to 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 disposing the first active material layer 112 thereon. The first current collecting body 113 further includes at least one through hole 113d. One end of the through hole 113d is opened on the bearing surface 113c. The opening of the other end of the through hole 113d faces the first protection portion 115 . A portion of the first active material layer 112 is filled in the through hole 113d.

Specifically, for the embodiment in which the first protective layer 114 is embedded in the first current collector body 113 , the active material portion 153 in the first protective portion 115 cannot contact the electrolyte 13 . In this embodiment, a through hole 113d is formed on the first current collecting body 113, and the through hole 113d communicates with the first active material layer 112 and the first protection part 115, so that the active material part 153 in the first protection part 115 can pass through The through hole 113 d is in contact with the electrolyte 13 , 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 .

Further, the number of the through holes 113d is plural. A plurality of through holes 113d are provided on one side or opposite sides of the first protection portion 115 . When the first active material layers 112 are provided on opposite sides of the first current collector body 113 , through holes 113 d are provided on opposite sides of the first protection portion 115 , so that the active materials in the first protection portion 115 The first active material layer 112 can be contacted from the through holes 113d on both sides to increase the concentration and speed of lithium ion generation, further increase the energy density of the battery 10 and improve the utilization rate of the active material portion 153 in the first protection portion 115 .

In a third possible implementation manner of the first protection portion 115 , please refer to 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 arranged in the porous structure 154 and can move in the holes of the porous structure 154 .

Specifically, the porous structure 154 includes, but is not limited to, at least one of nanoporous materials, fibrous porous materials, and foamed porous materials. The particle size of the magnetic particles 155 is smaller than the pore diameter 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 may be a conductive material or a non-conductive material.

During the puncture test of the battery 10 , the battery 10 is subjected to the puncture test using steel. When the tip of the steel needle enters the first protection part 115, the magnetic particles 155 in the first protection part 115 are adsorbed on the surface of the tip of the steel needle under the attractive force of the steel needle, and a large number of magnetic particles 155 are adsorbed on the tip of the steel needle , so that the puncture tip becomes no longer sharp, thereby reducing the puncture force of the needle tip of the steel needle on the first protection part 115, thereby increasing the further penetration of the steel needle through the first protection part 115, and improving the passing rate of the puncture test of the battery 10, In this way, the safety of the battery 10 is improved.

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.

By arranging the magnetic particles 155 capable of conducting electricity in the first protection part 115, on the one hand, the magnetic particles 155 can be adsorbed on the surface of the puncture thorn when the puncture thorn enters the first protection part 115, so that the puncture thorn is passivated, so that the Block the puncture from further piercing the first protection part 115, thereby preventing the first composite pole piece 11 from being penetrated, and improving the safety performance of the battery 10; on the other hand, the magnetic particles 155 can improve the electrical conductivity of the first protection part 115, thereby The conductivity of the first composite current collector 111 is improved.

Optionally, please refer to 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 particles 155 have magnetism, so as to prevent the steel needle from penetrating further on the surface of the steel needle tip when the steel needle tip pierces the first protection part 115 . The insulating coating layer 158 includes, but is not limited to, an insulating glue layer. The insulating coating layer 158 coats the magnetic core 157 so that the surface of the magnetic particles 155 has insulating properties.

When the steel needle pierces the first protection part 115, the magnetic particles 155 can be adsorbed on the surface of the piercing thorn tip when the piercing thorn tip enters the first protection part 115, so that the piercing thorn tip is blunt, so as to prevent the puncture from further piercing the first protection part 115. A protection part 115, thereby preventing the first composite pole piece 11 from being penetrated, and improving the safety performance of the battery 10; at the same time, the surface of the magnetic particles 155 is an insulating material, the magnetic particles 155 are adsorbed on the surface of the steel needle, and the magnetic particles 155 make the steel The needle is insulated from the first composite pole piece 11 , and even if the steel needle penetrates two adjacent pole pieces, the steel needle cannot short-circuit the two pole pieces, thereby effectively improving the safety of the battery 10 .

In other words, the magnetic particles 155 whose surface is an insulating material can be adsorbed on the surface of the steel needle when the steel needle pierces the first protection part 115 , so that the steel needle is insulated from the first composite pole piece 11 , so that even when the steel needle penetrates the first protective part 115 In the case of passing through the first composite pole piece 11 and the second composite pole piece 12, the first composite pole piece 11 and the second composite pole piece 12 cannot be electrically connected, thereby effectively avoiding the short circuit of the battery 10 and improving the battery 10. safety.

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 ), and the protection part (the protection part) dispersed in the composite current collector of the battery 10 is provided. part refers to the first protection part and/or the second protection part), when the battery 10 encounters physical damage, the protection part can use its own good ductility to protect the positive and negative electrodes from direct contact, so as to protect the battery 10 from appearing Overheating causes a fire; at the same time, due to the scattered protection parts, the amount of protection parts can be reduced, on the one hand, the production cost can be reduced, and the weight of the battery 10 can also be reduced.

The above are some embodiments of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the principles of the present application, several improvements and modifications can be made, and these improvements and modifications may also be regarded as The protection scope of this application.

Claims

A composite current collector, comprising:

collector body; and

A protective layer is arranged on the current collecting body, the protective layer includes a plurality of protective parts, a hollow part is formed between two adjacent protective parts, and the elongation rate of the protective parts is greater than that of the current collecting body elongation.
The composite current collector according to claim 1, wherein at least part of the protective layer is provided on the surface of the current collector body, and at least part of the hollow part is used to accommodate a part of the active material layer; and/or , at least a part of the protective layer is embedded in the current collecting body, and at least a part of the hollow part is used for receiving a part of the current collecting body.
The composite current collector according to claim 1, wherein the number of the protective layers is plural, and a plurality of the protective layers are sequentially stacked along the thickness direction of the current collector body and arranged at intervals, and two adjacent layers The protective parts in the protective layer are arranged at least partially staggered in the vertical direction and the thickness direction.
The composite current collector according to claim 3, wherein two adjacent protective layers comprise a first sub-protective layer and a second sub-protective layer, and the protective portion of the first sub-protective layer is located in the collector. The orthographic projection of the current collecting body in the thickness direction covers the hollow portion of the second sub-protective layer; and/or, the orthographic projection of the protective portion of the second sub-protective layer in the thickness direction of the current collecting body covers all Describe the hollow part of the first sub-protective layer.
The composite current collector according to claim 4, wherein the current collecting body has a first surface and a second surface disposed opposite to each other, and 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.
The composite current collector according to any one of claims 1 to 5, wherein the protection part comprises a protection body and a conductive part, the conductive part is provided on the surface or inside of the protection body, and the conductive part for being electrically connected with the current collecting body.
The composite current collector of claim 6, wherein the conductive portion comprises at least one of a plurality of conductive particles, conductive pillars, conductive wires, conductive meshes, conductive sheets, and conductive rods.
The composite current collector according to any one of claims 1 to 5, wherein the protection part comprises a protection body and an active material part, the active material part is provided on the surface or inside of the protection body, the protection body The active material portion is used for electrochemical reaction with the electrolyte.
The composite current collector according to claim 8, wherein the protective layer is embedded in the current collecting body, and the current collecting body has at least one bearing surface for arranging the active material layer; the The current collecting body further includes at least one through hole, one end of the through hole is opened on the bearing surface; the other end of the through hole is opened to face the protective layer, and the through hole is used to fill part of the active material layer.
The composite current collector according to claim 9, wherein the number of the through holes is plural, and a plurality of the through holes are arranged on one side or opposite sides of the protective layer.
The composite current collector according to any one of claims 1 to 5, wherein the protection part comprises a porous structure and a plurality of magnetic particles arranged in the porous structure.
The composite current collector according to claim 11, wherein the material of the magnetic particles is a conductive material.
The composite current collector of claim 11, wherein the magnetic particles comprise a magnetic core and an insulating coating layer covering the magnetic core.
The composite current collector of claim 11, wherein the material of the porous structure comprises at least one of a nanoporous material, a fibrous porous material, and a foamed porous material.
The composite current collector according to any one of claims 1 to 5, wherein 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 The hollow part is in the shape of a grid; or, the protection part is in the shape of a grid, and the hollow part is in the shape of a block.
A composite pole piece, characterized in that it comprises an active material layer and the composite current collector according to any one of claims 1 to 15, wherein the active material layer is arranged on one side or opposite sides of the composite current collector .
The composite pole piece according to claim 16, wherein the protective layer is provided on the surface of the current collector body layer, and the active material layer covers the protective portion and the hollow portion; or, the The active material layer covers the protection portion and fills the hollow portion; or, the active material layer and the protection portion are located in the same layer and disposed in the hollow portion.
A battery, characterized by comprising a plurality of composite pole pieces as claimed in claim 16 or 17.
The battery of claim 18, wherein the plurality of composite pole pieces comprises a first composite pole piece and a second composite pole piece, the battery further comprises a separator, and the separator is disposed on the first composite pole piece Between the pole piece and the second composite pole piece, the protective layer of the first composite pole piece and the protective layer of the second composite pole piece are at least partially perpendicular to the thickness direction of the first composite pole piece Stagger settings.
An electronic device, characterized by comprising the battery according to claim 18 or 19.