Composite current collector, composite electrode, battery and electronic device

Abstract

The present application provides a composite current collector, a composite electrode, a battery and an electronic device. The composite current collector includes a current collecting body, a first protective layer and a first heating layer. The first protective layer is disposed on the current collecting body, and the elongation rate of the first protective layer is greater than that of the current collecting body; the first heating layer is disposed on the current collecting body for heating the composite current collector. The composite current collector, composite electrode, battery and electronic device provided by the present application can improve safety performance and prevent short circuit between the positive and negative electrodes.

Description

Technical Field

[0001] This application relates to the field of electronic technologies, and particularly to a composite current collector, a composite electrode, a battery, and an electronic device. Background Art

[0002] Rechargeable batteries, such as lithium batteries, are widely used in electric vehicles and consumer electronic products due to their advantages of high energy density, high output power, long cycle life, and low environmental pollution. However, when rechargeable batteries are subjected to abnormal conditions such as extrusion, collision, or puncture, or when lithium crystallization occurs due to internal reactions in the battery, it is easy to cause a short circuit between the positive and negative electrode plates, resulting in thermal runaway failure of the battery cell, and it is very easy to catch fire and explode, thus causing serious hazards. Therefore, how to improve the safety performance of the battery and prevent short-circuiting between the positive and negative electrode plates has become a technical problem to be solved. Summary of the Invention

[0003] This application provides a composite current collector, a composite electrode, a battery, and an electronic device that can improve safety performance and prevent short-circuiting between the positive and negative electrode plates.

[0004] In a first aspect, an embodiment of this application provides a composite current collector, including:

[0005] A current collecting body;

[0006] A first protective layer provided on the current collecting body, and the elongation rate of the first protective layer is greater than that of the current collecting body; and

[0007] A first heating layer provided on the current collecting body for heating the composite current collector.

[0008] In a second aspect, an embodiment of this application provides a composite electrode, including an active material layer and the composite current collector as described above, and the active material layer is provided on one side or opposite sides of the composite current collector.

[0009] In a third aspect, an embodiment of this application provides a battery, including at least one of the composite electrodes as described above.

[0010] In a fourth aspect, an embodiment of this application provides an electronic device, including the battery as described above.

[0011] The composite current collector provided by the embodiment of the present application is provided with a first protective layer and a first heating layer. The elongation rate of the first protective layer is greater than that of the current collector body, and the first protective layer has stronger tensile resistance relative to the current collector body, so that the first protective layer has stronger resistance to puncture relative to the current collector body, effectively preventing the puncture from piercing the composite current collector and improving the resistance of the composite current collector to puncture. By providing the first heating layer, the first heating layer is used to heat the composite current collector, reduce the puncture generated by the electrochemical reaction inside the battery and slow down the growth of the internal puncture, and improve the safety of the battery to which the composite current collector is applied.

[0012] The composite electrode provided by the embodiment of the present application includes the above-mentioned composite current collector, and thus has stronger resistance to puncture.

[0013] The battery provided by the embodiment of the present application includes a plurality of the above-mentioned composite electrodes. Since the protective layer capable of effectively resisting puncture is provided in the composite electrode, the battery has strong resistance to the puncture generated by the internal electrochemical reaction or other punctures. Furthermore, it effectively prevents the puncture from piercing the positive and negative electrodes simultaneously and forming a short circuit point between the positive and negative electrodes, avoids the safety problems caused by the rapid temperature rise of the battery after the short circuit of the positive and negative electrodes, improves the safety of the battery, and can also achieve self-heating at low temperature or other heating required situations, improving the charging rate.

[0014] The electronic device provided by the embodiment of the present application includes the above-mentioned battery. Through the improvement of the internal structure of the battery, the battery has high safety. Therefore, the electronic device also has high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. 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 be obtained based on these drawings without creative efforts.

[0016] Figure 1 It is a schematic structural diagram of an electronic device provided by the embodiment of the present application;

[0017] Figure 2 is Figure 1 a schematic exploded view of an electronic device provided;

[0018] Figure 3 It is a circuit block diagram of the battery provided by the embodiment of the present application electrically connected to an external power source;

[0019] Figure 4 is Figure 2 a perspective view of the battery provided;

[0020] Figure 5 is Figure 2 A sectional view of the provided battery;

[0021] Figure 6 is Figure 5 A first partial sectional view of the battery cell in the provided battery;

[0022] Figure 7 is Figure 6 A sectional view of the provided first first composite electrode;

[0023] Figure 8 is Figure 6 A sectional view of the provided second first composite electrode;

[0024] Figure 9 is Figure 6 A sectional view of the provided third first composite electrode;

[0025] Figure 10 is Figure 8 A top view of the provided first composite electrode;

[0026] Figure 11 is Figure 6 A sectional view of the provided fourth first composite electrode;

[0027] Figure 12 is Figure 6 A sectional view of the provided fifth first composite electrode;

[0028] Figure 13 is Figure 6 A sectional view of the provided sixth first composite electrode;

[0029] Figure 14 is Figure 6 A sectional view of the provided seventh first composite electrode;

[0030] Figure 15 is Figure 6 A sectional view of the provided eighth first composite electrode;

[0031] Figure 16 is Figure 6 A sectional view of the provided ninth first composite electrode;

[0032] Figure 17 is Figure 6 A sectional view of the provided tenth first composite electrode;

[0033] Figure 18 is Figure 6 A sectional view of the provided eleventh first composite electrode;

[0034] Figure 19 is Figure 6 The sectional view of the twelfth first composite pole piece provided;

[0035] Figure 20 is Figure 6 The sectional view of the thirteenth first composite pole piece provided;

[0036] Figure 21 is Figure 6 The sectional view of the fourteenth first composite pole piece provided;

[0037] Figure 22 is Figure 6 The detailed structure diagram of the first composite pole piece, the separator and the second composite pole piece provided;

[0038] Figure 23 is Figure 6 The top view of the first protective layer provided;

[0039] Figure 24 is Figure 6 The top view of the second protective layer provided;

[0040] Figure 25 is Figure 6 The top view of the third protective layer provided;

[0041] Figure 26 is Figure 6 The top view of the fourth protective layer provided;

[0042] Figure 27 is Figure 6 The sectional view of the eighth first composite pole piece provided;

[0043] Figure 28 is Figure 7 The sectional view of the first protection part provided;

[0044] Figure 29 is Figure 7 The top view of the second protection part provided;

[0045] Figure 30 is Figure 7 The sectional view of the third protection part provided;

[0046] Figure 31 is Figure 7 The sectional view of the fourth protection part provided;

[0047] Figure 32 is Figure 7 The sectional view of the fifth protection part provided;

[0048] Figure 33 is Figure 6Cross-sectional view of the fifth protective layer provided;

[0049] Figure 34 is Figure 6 Cross-sectional view of the sixth protective layer provided;

[0050] Figure 35 is Figure 6 Side view of the first composite electrode and the second composite electrode provided;

[0051] Figure 36 is Figure 6 Front view of the first composite electrode provided;

[0052] Figure 37 is Figure 2 Front view of the battery provided;

[0053] Figure 38 is Figure 8 Top view of another first composite electrode provided. Specific embodiments

[0054] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The embodiments listed in the present application can be appropriately combined with each other.

[0055] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of an electronic device provided in an embodiment of the present application. The electronic device 100 can be a rechargeable device such as a telephone, a television, a tablet computer, a mobile phone, a camera, a personal computer, a laptop computer, a wearable device, an electric vehicle, an airplane, etc. Please refer to Figure 1 . In the present application, the electronic device 100 is taken as a mobile phone as an example for illustration. For the convenience of description, it is defined with reference to the first perspective of the electronic device 100. 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.

[0056] 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 further includes a display screen 20, a middle frame 30, and a rear cover 40. The display screen 20, the middle frame 30, and the rear cover 40 are fixedly connected in sequence. The battery 10 is disposed in the middle frame 30. The battery 10 is used to supply power to the display screen 20 and devices such as the main board 60 disposed on the middle frame 30.

[0057] 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, and nano-batteries. In the embodiments of the present application, the battery 10 is taken as an example of a lithium-ion battery for illustration.

[0058] The present application does not make specific limitations on the shape of the battery 10. The battery 10 can be in a columnar form, a bag-like form, an arc-like form, a soft-pack square form, a cylindrical form, a prismatic form, or an irregular shape, etc. Classified according to the charging method, the battery 10 described in the present application includes, but is not limited to, a wired charging battery and a wireless charging battery. In the embodiments of the present application, the battery 20 is taken as an example of a wired charging battery for illustration.

[0059] Please refer to Figure 2 , the electronic device 100 further includes a charging interface 50 and a charging control unit 70.

[0060] 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 an external power supply 200 (hereinafter simply referred to as the power supply 200). Specifically, the charging interface 50 can be connected to the power supply 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 Android and Windows phone system mobile phones, and the Lightning interface of IOS system mobile phones.

[0061] Please refer to Figure 3 , the charging control unit 70 is connected to the charging interface 50 and the battery 10. The charging control unit 70 can be a packaged integrated chip. The charging control unit 70 is provided on the main board 60 or the small board and is used to control the charging time, charging current, etc. 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.

[0062] Please refer to Figure 3, the conductive terminals of the power supply 200 include a first power terminal 210 and a second power terminal 220. The first power terminal 210 is the positive terminal of the power supply 200, and the second power terminal 220 is the negative terminal of the power supply 200; alternatively, the first power terminal 210 is the negative terminal of the power supply 200, and the second power terminal 220 is the positive terminal of the power supply 200. 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, sequentially through the first charging terminal 501, the charging control unit 70, the positive electrode 101 of the battery 10, the negative electrode 102 of the battery 10, the second charging terminal 502, and flows to the second power terminal 220, and the battery 10 is in a charging state.

[0063] The specific structure of the battery 10 provided by the embodiments of the present application will be described below with reference to the accompanying drawings.

[0064] Please refer to Figure 4 , the battery 10 includes a battery cell 1, a protection board 2, and a packaging case 3. The protection board 2 is electrically connected to the battery cell 1 and is used to protect the battery cell 1 against overvoltage, undervoltage, overcurrent, short circuit, and over-temperature states and extend the service life of the battery 10. The packaging case 3 is used to package 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, etc. In this embodiment, the packaging case 3 is an aluminum plastic film.

[0065] Please refer to Figure 5 , the battery cell 1 includes a first composite electrode 11, a second composite electrode 12, an electrolyte 13, and a separator 14. The first composite electrode 11 is a positive electrode, and the second composite electrode 12 is a negative electrode; alternatively, the first composite electrode 11 is a negative electrode, and the second composite electrode 12 is a positive electrode. In this embodiment, the first composite electrode 11 is a positive electrode, and the second composite electrode 12 is a negative electrode.

[0066] Please refer to Figure 6 , the first composite electrode 11 includes a first composite current collector 111 and a first active material layer 112 provided on the first composite current collector 111.

[0067] Specifically, the first composite current collector 111 is a conductive thin sheet.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] Please refer to Figure 6, the first composite electrode 11, the separator 14, and the second composite electrode 12 are all in sheet form. The separator 14 is disposed between the first composite electrode 11 and the second composite electrode 12 to prevent the first composite electrode 11 and the second composite electrode 12 from coming into direct contact. When the first composite current collector 111 of the first composite electrode 11 and the second composite current collector 121 of the second composite electrode 12 are electrically connected, the battery 10 is short-circuited, and the current inside the battery 10 increases sharply instantaneously, causing the internal temperature of the battery 10 to rise sharply. The active material layer and the electrolyte 13 inside the battery 10 are prone to safety problems such as explosion at high temperatures. The separator 14 is a specially formed polymer film. The separator 14 has a microporous structure that allows lithium ions to pass through freely while electrons cannot pass through, enabling an electrochemical reaction between the first composite electrode 11 and the second composite electrode 12, but the first composite electrode 11 and the second composite electrode 12 are in an insulating state. The material of the separator 14 includes but is not limited to polyethylene (PE), polypropylene (PP), or their composite films. The composite film is, for example, a PP / PE / PP three-layer separator.

[0072] Optionally, the number of the first composite electrode 11 and the second composite electrode 12 is one each. One first composite electrode 11, one or more separators 14, and one second composite electrode 12 are stacked in sequence and then wound to form a wound-type battery cell 1.

[0073] Optionally, the number of the first composite electrode 11, the second composite electrode 12, and the separator 14 is multiple. The first composite electrode 11, the separator 14, the second composite electrode 12, the separator 14, the first composite electrode 11, and the separator 14 are stacked in sequence to form a stacked-type battery cell 1.

[0074] Please refer to Figure 5 , optionally, the electrolyte 13 can be an organic solvent dissolved with an electrolyte lithium salt for providing lithium ions. The electrolyte lithium salts include LiPF6, LiClO4, LiBF4, etc. The organic solvent is mainly composed of one or a mixture of several of diethyl carbonate (DEC), propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), etc. The first composite electrode 11, the second composite electrode 12, and the separator 14 are packaged in the encapsulation case 3, and the electrolyte 13 is injected into the encapsulation case 3 so that the first composite electrode 11 and the second composite electrode 12 are immersed in the electrolyte 13, and the protection board 2 is encapsulated in the encapsulation case 3 to form the battery 10.

[0075] During the charge and discharge process of the battery 10, Li+ is embedded and de-embedded back and forth between the first composite electrode 11 and the second composite electrode 12. During charging, Li+ is de-embedded from the first composite electrode 11 (positive electrode) and embedded into the second composite electrode 12 (negative electrode) through the electrolyte, and the second composite electrode 12 is in a lithium-rich state. During discharging, the situation is opposite.

[0076] Further, please refer to Figure 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 electrode plate 11, and the second tab 17 is electrically connected to the second composite electrode plate 12. One end of the first tab 16 away from the first composite electrode plate 11 is electrically connected to the protection board 2, and one end of the second tab 17 away from the second composite electrode plate 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.

[0077] The first composite electrode plate 11, the first tab 16, the protection board 2, the charging control unit 70, the load, the protection board 2, the second tab 17, and the second composite electrode plate 12 form a discharge circuit. The first composite electrode plate 11, the first tab 16, the protection board 2, the charging control unit 70, the external power supply 200, the protection board 2, the second tab 17, and the second composite electrode plate 12 form a charging circuit.

[0078] Generally speaking, in the event of abnormal conditions such as collision, extrusion, and puncture of the battery 10, short circuits of the positive and negative electrode plates are likely to occur, leading 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 evaluating the safety of the battery 10. Specifically, the battery 10 is punctured by a steel needle or the like, and the probability of the battery 10 short-circuiting under the puncture of the steel needle is tested. The smaller the probability of the battery 10 short-circuiting under the puncture of the steel needle, the higher the passing 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, technicians have found that lithium crystallization is likely to occur during the electrochemical reaction process inside the battery 10, and the lithium crystallization is very likely to pierce the electrode plate inside the battery 10, resulting in a short circuit of the battery 10. The puncture described in this application includes, but is not limited to, the steel needle in the puncture test and the lithium crystallization generated by the electrochemical reaction inside the battery 10, etc.

[0079] 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 plate 11 and the second composite electrode plate 12 have strong puncture stability, and have high stability and reliability under abnormal conditions such as puncture and impact. In this way, the battery 10 formed by the first composite electrode plate 11 and the second composite electrode plate 12 also has strong puncture stability, has a high passing rate under abnormal conditions such as puncture and impact, and further reduces the probability of the battery 10 short-circuiting, effectively improving the safety of the battery 10.

[0080] The structure of the first composite current collector 111 will be exemplified below with reference to the drawings. The structure of the second composite current collector 121 can refer to the structure of the first composite current collector 111.

[0081] Please refer to Figure 7 Figure 7 , the first composite current collector 111 includes a first current collector body 113, a first protective layer 114, and a first heating layer 115. In this embodiment, the first protective layer 114, the first heating layer 115, and the first current collector body 113 together form the first composite current collector 111. This application does not specifically limit the specific combination method of the first protective layer 114, the first heating layer 115, and the first current collector body 113. Specifically, the first protective layer 114 and the first heating layer 115 can be combined with the first current collector body 113 by at least one of coating, calendering, roll pressing, bonding, evaporation coating, chemical vapor deposition, chemical deposition, magnetron sputtering, and electroless plating.

[0082] This application does not specifically limit the specific positions of the first protective layer 114 and the first heating layer 115 provided on the first current collector body 113. The first protective layer 114 and the first heating layer 115 provided on the first current collector body 113 include, but are not limited to, at least part of the first protective layer 114 being embedded in the first current collector body 113; and / or, at least part of the first heating layer 115 being embedded in the first protective layer 114; and / or, at least part of the first heating layer 115 being provided on the surface of the first protective layer 114; and / or, at least part of the first heating layer 115 being provided in the first current collector body 113113.

[0083] Specifically, the first current collector body 113 is made of a conductive material. In this embodiment, the first composite current collector 111 is a positive current collector. Further, the first current collector body 113 is an aluminum foil.

[0084] 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 total deformation ΔL of the gauge section after the specimen is stretched and fractured to the original gauge length L: δ = ΔL / L × 100%. The greater the elongation, the greater the deformation of the material after tensile fracture. In other words, the material is less likely to break. That is to say, the anti-fracture ability of the first protective layer 114 is greater than that of the first current collector body 113. When the puncture is directed at the first composite electrode 11, due to the large elongation of the first protective layer 114, the first protective layer 114 can effectively block the effect of the puncture through deformation to prevent the puncture from penetrating the first composite electrode 11. In this way, it is possible to prevent the puncture from conducting between the first composite electrode 11 and the second composite electrode 12 and thus causing a short circuit between the positive and negative electrodes of the battery 10.

[0085] Optionally, the material of the first protective layer 114 includes, but is not limited to, adhesives, porous stretchable structures, etc. Among them, the adhesives include, but are not limited to, at least one of polyvinylidene fluoride, copolymers of vinylidene fluoride and fluorinated olefins, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, fluororubber, polyvinyl alcohol, polyvinylidene fluoride, polyamide, etc. The porous stretchable structures include, but are not limited to, nano-stretchable structures, porous foam structures, and fibrous porous structures.

[0086] The material of the first heating layer 115 includes, but is not limited to, electrothermal materials, magnetocaloric materials, and photothermal materials. In this embodiment, the material of the first heating layer 115 is an electrothermal material. Specifically, the material of the first heating layer 115 is a conductive material. The first heating layer 115 utilizes the Joule effect generated by passing an electric current to convert electrical energy into heat energy to achieve the purpose of heating the first composite current collector 111. Since the first heating layer 115 can be disposed inside or on the outer surface of the first current collector body 113, the heat generated by the first heating layer 115 raises the temperature inside the battery 10. Technicians have found that when the temperature inside the battery 10 rises, the electrochemical reaction inside the battery 10 can be accelerated, the lithium crystallization rate inside the battery 10 can be reduced, thereby slowing down the growth of lithium crystallization, and further reducing the generation or growth of punctures. In addition, in the case of low-temperature charging, by heating the first composite current collector 111 through the first heating layer 115, the temperature inside the battery 10 is raised, and the charging rate of the battery 10 can be increased.

[0087] Specifically, the electrothermal materials include, but are not limited to, one or more of graphite, nickel, aluminum, copper, stainless steel, positive temperature coefficient heating resistors (PTC), alloys, etc.; or the material of the electrothermal materials includes a multi-layer composite material composed of one or more layers of polymer films laminated on the above materials. The form of the first heating layer 115 includes, but is not limited to, coating, film, sheet, plate, wire, filament, grid, etc.

[0088] The first composite current collector 111 provided by the embodiment of the present application is provided with a first protective layer 114 and a first heating layer 115. The elongation rate of the first protective layer 114 is greater than that of the first current collector body 113. The first protective layer 114 has stronger tensile resistance relative to the first current collector body 113, so that the first protective layer 114 has stronger resistance to puncture relative to the first current collector body 113, effectively preventing the puncture from piercing the first composite current collector 111 and improving the puncture resistance of the first composite current collector 111; by providing the first heating layer 115, the first heating layer 115 is used to heat the first composite current collector 111, reduce the puncture generated by the electrochemical reaction inside the battery 10 and slow down the growth of the internal puncture, and improve the safety of the battery 10 to which the first composite current collector 111 is applied.

[0089] It can be understood that the structure of the second composite current collector 121 in the present application can refer to the structure of the first composite current collector 111, and will not be described in detail hereinafter.

[0090] In this embodiment, the first heating layer 115 is made of a conductive material. The first heating layer 115 is provided inside the first current collector body 113 or on the outer surface of the first current collector body 113. The first heating layer 115 is electrically connected to the first current collector body 113. Among them, the first heating layer 115 not only serves as a heating component of the first composite current collector 111, but also serves as a conductive component of the first current collector body 113, increasing the conductivity of the first current collector body 113, realizing the multiple uses of the first heating layer 115, and improving the integration degree of the first composite current collector 111.

[0091] In this embodiment, please refer to Figures 7 to 9, the first protective layer 114 and the first heating layer 115 are provided on the same layer. By arranging the first protective layer 114 and the first heating layer 115 on the same layer, on the one hand, the thickness of the first composite current collector 111 can be made smaller, further reducing the overall thickness of the battery 10; on the other hand, when the material of the first protective layer 114 is an insulating material, the conductive first heating layer 115 is arranged on the layer where the first protective layer 114 is located, so that the layer where the first protective layer 114 is located will not cut off the first current collecting body 113 into two mutually insulated conductive layers. In other words, when the material of the first protective layer 114 is an insulating material, such as an adhesive layer, the first protective layer 114 is designed as a whole layer, and when the first protective layer 114 is arranged within the first current collecting body 113, the first protective layer 114 blocks the electrical conduction of the first current collecting body 113 on its opposite sides. When the first protective layer 114 is designed as a whole layer and the first protective layer 114 is arranged between the first current collecting body 113 and the first active material layer 112, the first protective layer 114 blocks the electrical conduction between the first current collecting body 113 and the first active material layer 112 on its opposite sides. In this way, the conductive ability of the first current collecting body 113 will be weakened. By arranging the first heating layer 115 and the first protective layer 114 on the same layer, the layer where the first protective layer 114 and the first heating layer 115 are located not only has the function of blocking punctures and effectively preventing short circuits between the positive and negative electrode plates, but also has the function of heating the first composite current collector 111 and the battery 10, and also has the function of improving the conductivity inside the first composite current collector 111.

[0092] In other words, the first protective layer 114 is the protective part on the first composite current collector 111 to prevent punctures, and the first heating layer 115 is the conductive channel on the first composite current collector 111. In this way, the first protective layer 114 can not only effectively protect against punctures, but also ensure that the first composite current collector 111 has a high conductivity.

[0093] This application does not specifically limit the specific structure when the first protective layer 114 and the first heating layer 115 are arranged on the same layer. Optionally, please refer to Figure 7 , the first protective layer 114 and the first heating layer 115 are independently arranged as two parts on both sides in the X-Y plane; or, please refer to Figures 8 to 10 , the first protective layer 114 and the first heating layer 115 are arranged in a complementary pattern; or, please refer to Figure 11 , the first heating layer 115 is at least partially embedded in the first protective layer 114; or, please refer to Figure 12 , the first heating layer 115 is coated outside the first protective layer 114, and so on.

[0094] Optionally, the thickness of the first protective layer 114 in the Z-axis direction is 1 to 40 μm.

[0095] Of course, in other embodiments, please refer to Figure 13 and Figure 14 , the first protective layer 114 and the first heating layer 115 may be stacked.

[0096] Optionally, please refer to Figure 13 , the first protective layer 114, the first heating layer 115, and the first current collector body 113 are stacked in sequence. Please refer to Figure 14 , the first protective layer 114 may be a patterned structure to electrically conductively connect the first active material layer 112 with the first heating layer 115 or the first current collector body 113. Further, please refer to Figure 13 , the first active material layer 112 covers the first protective layer 114; or, please refer to Figure 14 , the first active material layer 112 and the first protective layer 114 are in the same layer. Further, the first active material layer 112 and the first protective layer 114 are complementary patterns.

[0097] Optionally, please refer to Figures 15 to 17 , the first heating layer 115, the first protective layer 114, and the first current collector body 113 are stacked in sequence. Please refer to Figure 16 , the first protective layer 114 may be a patterned material to electrically conductively connect the first heating layer 115 with the first current collector body 113. Further, please refer to Figure 16 , the first active material layer 112 covers the first heating layer 115; or, please refer to Figure 17 , the first active material layer 112 and the first heating layer 115 are in the same layer. Further, the first active material layer 112 is also in the voids of the patterned first protective layer 114, and the first active material layer 112 and the first heating layer 115 are complementary patterns.

[0098] Optionally, please refer to Figure 18 , the first heating layer 115 and the first protective layer 114 may be stacked inside the first current collector body 113. Please refer to Figure 19 , the first protective layer 114 may be a patterned structure to penetrate the first current collector body 113 inside the first protective layer 114, thereby increasing the conductivity inside the first composite current collector 111.

[0099] In other embodiments, the first heating layer 115 and the first protective layer 114 may be spaced apart inside the first current collector body 113.

[0100] In other embodiments, please refer to Figure 20 and Figure 21, the first heating layer 115 is disposed within the first current collector body 111, and the first protective layer 114 is disposed outside the first current collector body 111, and the first protective layer 114 is a patterned structure; or, the first heating layer 115 is disposed within the first current collector body 113, and the first protective layer 114 is disposed outside the first current collector body 113, and the first protective layer 114 is a patterned structure.

[0101] Specifically, in this embodiment, the number of the first protective layer 114 and the first heating layer 115 is not specifically limited. The above-described embodiments are all cases where the number of the first protective layer 114 and the first heating layer 115 is one. In other embodiments, the number of the first protective layer 114 and the first heating layer 115 may also be multiple. When the number of the first protective layer 114 and the first heating layer 115 is multiple, the specific positions thereof may refer to the embodiments when the first protective layer 114 and the first heating layer 115 are both one layer.

[0102] In this embodiment, please refer to Figure 22 , the first current collector body 113 includes a first surface 113a and a second surface 113b disposed opposite to each other. Among them, the first protective layer 114 and the first heating layer 115 are disposed on the first surface 113a. Specifically, in the case where the piercing end contacts the second active material layer 122 of the second composite electrode sheet 12, the first protective layer 114 and the first heating layer 115 disposed on the outer surface can effectively block the other end of the piercing from contacting the first current collector body 113, so as to avoid short circuit between the first composite electrode sheet 11 and the second composite electrode sheet 12 and reduce the safety problems in the battery 10. In addition, the first active material layer 112 is disposed on the first protective layer 114 and the first heating layer 115, and the opposite sides of the first heating layer 115 are respectively connected to the first active material layer 112 and the first current collector body 113, so that the first active material layer 112 is electrically conductive with the first current collector body 113.

[0103] Further, please refer to Figure 22 , the first composite current collector 111 further includes a second protective layer 116. The second protective layer 116 is disposed on the second surface 113b or between the first surface 113a and the second surface 113b. In other words, the second protective layer 116 is disposed on the second surface 113b or within the first current collector body 113. The elongation rate of the second protective layer 116 is greater than the elongation rate of the first current collector body 113. The elongation rate of the second protective layer 116 is greater than the elongation rate of the first heating layer 115. The material of the second protective layer 116 may be the same as or different from the material of the first protective layer 114. In this embodiment, the material of the second protective layer 116 is the same as the material of the first protective layer 114.

[0104] The orthographic projection of the second protective layer 116 on the first heating layer 115 covers the first heating layer 115. Specifically, since the first protective layer 114 is not provided at the position where the first heating layer 115 is located, and when the first heating layer 115 is made of a conductive material such as metal, the elongation rate of the first heating layer 115 is relatively low. Thus, the problem that the first composite electrode sheet 11 is pierced through the first heating layer 115 is likely to occur. In response to this, the first composite current collector 111 provided in the embodiment of the present application further includes a second protective layer 116, and the position of the second protective layer 116 is specifically designed such that the second protective layer 116 is designed corresponding to the position where the first heating layer 115 is located. In this way, even if the first composite electrode sheet 11 is pierced through the first heating layer 115, the second protective layer 116 can effectively block the piercing from piercing through the first composite electrode sheet 11, thereby preventing the first composite electrode sheet 11 from being short-circuited with the second composite electrode sheet 12 by the piercing, and further improving the safety of the battery 10. In summary, the first composite electrode sheet 11 provided in this embodiment can not only achieve the blocking of piercing, reduce the conduction between the positive and negative electrode sheets, but also heat the inside of the battery 10 to reduce the formation and growth of piercing, and improve the safety of the battery 10.

[0105] When the first protective layer 114 is complementary to the first heating layer 115 in shape and the second protective layer 116 has the same shape as the first heating layer 115, the shapes of the first protective layer 114 and the second protective layer 116 are complementary. In this way, the blocking area formed by the first protective layer 114 and the second protective layer 116 can cover the area of the X-Y plane of the first composite electrode sheet 11, so as to improve the resistance of the first composite electrode sheet 11 to piercing at various positions in the X-Y plane, and further improve the safety of the battery 10.

[0106] In one embodiment, please refer to Figure 22, the first composite current collector 111 further includes a second heating layer 117. The second heating layer 117 is made of a conductive material. The second heating layer 117 is electrically connected to the first current collecting body 113. The second heating layer 117 is disposed on the second surface 113b or between the first surface 113a and the second surface 113b. In other words, the second heating layer 117 is disposed within the first current collecting body 113 or on the second surface 113b of the first current collecting body 113. The orthographic projection of the second heating layer 117 on the first protective layer 114 covers the first protective layer 114. That is to say, the position of the second heating layer 117 corresponds to the position of the first protective layer 114. Further, the second heating layer 117 and the second protective layer 116 are located on the same layer. Thus, the overall thickness of the first composite electrode 11 can be reduced. The first protective layer 114 and the second protective layer 116 provide full coverage protection for the first composite electrode 11 in the X-Y plane. The first heating layer 115 and the second heating layer 117 can electrically connect the first current collecting body 113 with the first active material layers 112 on its opposite sides, and can also heat the opposite sides of the first current collecting body 113, improving the uniformity and heating efficiency of the internal heating of the battery 10, reducing the formation and growth of punctures inside the battery 10, and increasing the charging rate.

[0107] 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 substantially similar to the structure of the first composite current collector 111. Please refer to Figure 22 , the second composite current collector 121 includes a second current collecting body 123 and a third protective layer 124 and a third heating layer 125 disposed on the second current collecting body 123. The positional relationship between the third protective layer 124 and the second current collecting body 123 can refer to the positional relationship between the first protective layer 114 and the first current collecting body 113. Among them, the materials of the first protective layer 114 and the third 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 materials and structures of the first heating layer 115 and the third heating layer 125 can be the same or different.

[0108] Further, please refer to Figure 22, the second composite electrode sheet 12 further includes a fourth protective layer 126 and a fourth heating layer 127. A first protective layer 114 and a second protective layer 116 are provided on the first composite electrode sheet 11, and a third protective layer 124 and a fourth protective layer 126 are provided on the second composite electrode sheet 12, wherein the second protective layer 116 and the third protective layer 124 are arranged adjacent to each other. Further, the second protective layer 116 and the third protective layer 124 can be arranged staggeredly in the X-Y plane. Specifically, the positions of the first protective layer 114 and the third protective layer 124 are opposite and have the same shape, and the positions of the second protective layer 116 and the fourth protective layer 126 are opposite and have the same shape. In this way, the blocking surfaces formed by the protective layers of the first composite electrode sheet 11 and the second composite electrode sheet 12 can completely cover the X-Y plane in the battery 10 to block the puncture effect in all directions in the X-Y plane.

[0109] It can be understood that the above-mentioned first composite current collector 111 and second composite current collector 121 can be used in 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 electrode sheets in the stacked battery cell 1 structure can be composite electrode sheets, or all of the electrode sheets in the stacked battery cell 1 structure can be composite electrode sheets to improve the safety of the battery 10.

[0110] In this embodiment, the first protective layer 114 and the first heating layer 115 are complementary pattern structures. The first protective layer 114 and the first heating layer 115 cover the entire first current collector body 113. The specific shapes of the first protective layer 114 and the first heating layer 115 include but are not limited to the following embodiments.

[0111] In a possible embodiment, please refer to Figure 23 , the first protective layer 114 is strip-shaped and the first heating layer 115 is strip-shaped. A plurality of first protective layers 114 and a plurality of first heating layers 115 are arranged alternately in sequence. Both the first protective layer 114 and the first heating layer 115 are rectangular strips, and the extending directions of the first protective layer 114 and the first heating layer 115 are the same. Specifically, both the first protective layer 114 and the first heating layer 115 extend along the X-axis direction, the Y-axis direction, or a direction inclined with respect to the X-axis direction and the Y-axis direction. In other embodiments, the first protective layer 114 and the first heating layer 115 can also be triangular strips, diamond strips, wavy strips, etc. The present application does not specifically limit the number and size of the first protective layer 114.

[0112] In a possible embodiment, please refer to Figure 24 and Figure 25, the first protective layer 114 is block-shaped and the first heating layer 115 is grid-shaped. The first protective layer 114 and the first heating layer 115 have complementary pattern structures. The shape of the first protective layer 114 includes but is not limited to a circle, a triangle, a square, a rectangle, a diamond, etc. The multiple first protective layers 114 can be arranged in multiple rows and columns, or in a staggered arrangement.

[0113] In one possible implementation, see Figure 26 The first protective layer 114 is in a grid shape and the first heating layer 115 is in a block shape. The first protective layer 114 and the first heating layer 115 have complementary pattern structures. The shape of the first heating layer 115 includes but is not limited to a circle, a triangle, a square, a rectangle, a diamond, and the like.

[0114] The present application does not specifically limit the specific material and structure of the first protective layer 114. Optionally, the first protective layer 114 includes but is not limited to an insulating protective layer, a conductive protective layer, etc. The present application specifically illustrates the specific structure of the first protective layer 114 through the following embodiments. The material and structure of the second protective layer 116 can refer to the material and structure of the first protective layer 114, and the present application does not further limit the material and structure of the second protective layer 116.

[0115] In a possible implementation of the first protective layer 114, please refer to Figure 27 Optionally, the first protective layer 114 includes a protective body 151 and a functional portion 156. The functional portion 156 is disposed on the surface or inside of the protective body 151. The functional portion 156 is used to electrically conduct with the first current collecting body 113 and / or to conduct the temperature of the first heating layer 115.

[0116] Optionally, the functional portion 156 is a heat-conducting portion. In other words, the material of the functional portion 156 is a heat-conducting material, such as aluminum, copper, heat-conducting silicone, etc., so as to conduct the temperature of the first heating layer 115 and improve the temperature uniformity of the first composite electrode 11.

[0117] Optional, see Figure 28 , the functional part 156 is the conductive part 152, and the functional part 156 is used to be electrically connected with the first current collecting body 113. In addition, by setting the material of the functional part 156 to be a conductive material with high thermal conductivity, the functional part 156 can be electrically connected with the first current collecting body 113 and can also conduct the temperature of the first heating layer 115, so that the first heating layer 115 can be used for multiple purposes, saving space and the number of components.

[0118] The conductive part 152 is provided on the surface or inside of the protection body 151. The conductive part 152 is used for electrically connecting with the first current collector body 113. 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, cobalt, tungsten, tin, lead, iron, silver, gold, platinum, or their alloys.

[0119] Optionally, the protection body 151 can be an adhesive to connect the conductive part 152 to the first current collector body 113, and at the same time has a good elongation rate, so that the first protective layer 114 has both a good elongation rate and a high conductivity. The material of the protection body 151 includes but is not limited to at least one of vinylidene fluoride, copolymer of vinylidene fluoride and fluorinated olefin, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, fluorinated rubber, polyvinyl alcohol, polyvinylidene fluoride, and polyamide.

[0120] The following takes the drawings as an example to illustrate the specific structure of the conductive part 152.

[0121] In the first possible implementation manner of the conductive part 152, please refer to Figure 28 , the conductive part 152 is a plurality of conductive columns 152a. The plurality of conductive columns 152a can be arranged at intervals or connected. At least some of the plurality of conductive columns 152a completely penetrate the protection body 151.

[0122] Optionally, each conductive column 152a completely penetrates the protection body 151. Please refer to Figure 8 together. When the first protective layer 114 is arranged inside the first current collector body 113, the opposite ends of each conductive column 152a directly contact the first current collector body 113 to conduct inside the first current collector body 113. Please refer to Figure 9 together. When the first protective layer 114 is arranged 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 to conduct the first current collector body 113 and the first active material layer 112.

[0123] Optionally, a part of the conductive posts 152a completely penetrate the protection body 151, and another part of the conductive posts 152a are disposed within the protection body 151 and do not completely penetrate the protection body 151. The conductive posts 152a that do not completely penetrate the protection body 151 can be electrically connected to the conductive posts 152a that completely penetrate the protection body 151, so as to achieve electrical conduction between 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 electrical conductivity of the first current collector body 113.

[0124] By providing a plurality of conductive posts 152a, electrical conduction between the inside of the first current collector body 113 or between the first current collector body 113 and the first active material layer 112 can be achieved, further increasing the electrical conductivity of the first current collector body 113, and the structural strength of the first composite current collector 111 can also be increased.

[0125] In the second possible implementation manner of the conductive part 152, please refer to Figure 29 , the conductive part 152 is a conductive mesh. The protection body 151 is an adhesive filled in the gaps of the conductive mesh. In this implementation manner, the structure of the conductive part 152 is simple. The conductive mesh structure enables the first protection layer 114 to have a certain toughness. Combined with the adhesive filled in the conductive mesh, the first protection layer 114 has high toughness and deformation ability to resist the penetration of the puncture, effectively preventing the puncture from short-circuiting adjacent positive and negative electrode plates and improving the safety of the battery 10.

[0126] In the third possible implementation manner of the conductive part 152, please refer to Figure 30 , the conductive part 152 is conductive particles, and the protection body 151 is a glue layer. The conductive part 152 is mixed in the protection body 151 to form a glue layer with conductive ability. In this way, the obtained first protection layer 114 has good extensibility. At the same time, a certain concentration of conductive particles is uniformly provided in the glue layer, realizing good electrical conductivity of the first protection layer 114, improving the puncture resistance of the first composite current collector 111 and also being able to improve the conductivity of the first composite current collector 111.

[0127] By providing conductive particles in the first protection layer 114, the current collection performance of the first composite current collector 111 can be improved. By providing a glue layer in the first protection layer 114, the glue layer has viscosity and good extensibility, and can prevent the first composite current collector 111 from being punctured.

[0128] In the fourth possible implementation manner of the conductive part 152, the conductive part 152 and the protection body 151 are located on the same layer and are complementary pattern structures, so that the conductive part 152 and the protection body 151 form the first protection layer 114 that has both electrical conductivity and puncture resistance.

[0129] In a possible implementation of the second first protective layer 114, please refer to Figure 31 The first protective layer 114 includes a protective body 151 and an active material portion 153.

[0130] 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, copolymer of vinylidene fluoride and fluorinated olefin, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, fluorinated rubber, polyvinyl alcohol, polyvinylidene fluoride, polyamide.

[0131] The active material portion 153 is disposed on the surface or inside of the protective body 151. The active material portion 153 is used to undergo an electrochemical reaction with the electrolyte 13. The material of the active material portion 153 includes but is not limited to at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate, lithium-rich manganese-based material, lithium nickel cobalt aluminate, etc.

[0132] By disposing the active material portion 153 inside the first protective layer 114, the material of the active material can be the same as that 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, both of which are used to react with the electrolyte 13 to form more lithium ions, thereby improving the energy density of the battery 10.

[0133] For the second composite current collector 121, the structure of the second protective layer 116 can refer to the structure of the first protective layer 114. The material of the active material portion 153 of the second protective layer 116 includes but is not limited to graphite, carbon fiber, graphene, lithium titanate, etc. The active material portion 153 of the second protective layer 116 is used to react with the electrolyte 13 to generate more electrons, thereby improving the energy density of the battery 10.

[0134] Optionally, please refer to Figure 32 The first protective layer 114 is embedded in the first current collector body 113. The first current collector body 113 has at least one bearing surface 113c for setting the first active material layer 112. The first current collector 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 other end of the through hole 113d is opened facing the first protective layer 114. The through hole 113d is used to fill a part of the first active material layer 112.

[0135] Specifically, for the embodiment where the first protective layer 114 is embedded in the first current collector body 113, the active material portion 153 within the first protective layer 114 cannot contact the electrolyte 13. In this embodiment, a through hole 113d is formed in the first current collector body 113, and the through hole 113d communicates the first active material layer 112 and the first protective layer 114, so that the active material portion 153 within the first protective layer 114 can contact the electrolyte 13 through the through hole 113d, thereby promoting the generation of lithium ions, while achieving puncture and collision protection for the battery 10 and improving the energy density of the battery 10.

[0136] Furthermore, the number of the through holes 113d is multiple. The multiple through holes 113d are provided on one side or opposite sides of the first protective layer 114. When the first active material layers 112 are provided on opposite sides of the first current collector body 113, the through holes 113d are provided on opposite sides of the first protective layer 114, so that the active material within the first protective layer 114 can contact the first active material layer 112 through the through holes 113d on both sides, improving 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 within the first protective layer 114.

[0137] In a third possible embodiment of the first protective layer 114, please refer to Figure 33 , the first protective layer 114 includes a porous structure 154 and a plurality of magnetic particles 155 provided within the porous structure 154. The magnetic particles 155 are provided within the porous structure 154 and can move within the pores of the porous structure 154.

[0138] Specifically, the porous structure 154 includes but is not limited to at least one of nano-porous materials, fibrous porous materials, and foam 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 within the porous structure 154. In this embodiment, the porous structure 154 can be a conductive material or a non-conductive material.

[0139] During the puncture test of the battery 10, a steel needle is used to perform a puncture test on the battery 10. When the tip of the steel needle enters the first protective layer 114, the magnetic particles 155 within the first protective layer 114 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 protective layer 114, and further improving the penetration of the steel needle through the first protective layer 114, increasing the passing rate of the puncture test of the battery 10, and thus improving the safety of the battery 10.

[0140] Optionally, the magnetic particles 155 are made of 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.

[0141] By disposing the conductive magnetic particles 155 within the first protective layer 114, on the one hand, the magnetic particles 155 can be adsorbed on the surface of the puncturing tip when the puncturing tip enters the first protective layer 114, rendering the puncturing tip blunt, thereby preventing the puncturing from further piercing the first protective layer 114, and further preventing the first composite electrode sheet 11 from being penetrated, improving the safety performance of the battery 10; on the other hand, the magnetic particles 155 can enhance the conductive ability of the first protective layer 114, and thereby improve the conductivity of the first composite current collector 111.

[0142] Optionally, please refer to Figure 34 , the magnetic particles 155 include a magnetic core 157 and an insulating coating layer 158 coating 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 endow the magnetic particles 155 with magnetism to block further penetration on the surface of the steel needle tip when the steel needle tip penetrates the first protective layer 114. The insulating coating layer 158 includes but is not limited to an insulating adhesive layer. The insulating coating layer 158 coats the magnetic core 157 to render the surface of the magnetic particles 155 insulating.

[0143] When the steel needle penetrates the first protective layer 114, the magnetic particles 155 can be adsorbed on the surface of the puncturing tip when the puncturing tip enters the first protective layer 114, rendering the puncturing tip blunt, thereby preventing the puncturing from further piercing the first protective layer 114, and further preventing the first composite electrode sheet 11 from being penetrated, improving the safety performance of the battery 10; meanwhile, the surface of the magnetic particles 155 is made of an insulating material. The magnetic particles 155 are adsorbed on the surface of the steel needle, and the magnetic particles 155 insulate the steel needle from the first composite electrode sheet 11. Even when the steel needle penetrates two adjacent electrode sheets, the steel needle cannot cause the two electrode sheets to short-circuit, and thereby effectively improves the safety of the battery 10.

[0144] 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 layer 114, thereby insulating the steel needle from the first composite electrode sheet 11, and further preventing the steel needle from electrically conducting the first composite electrode sheet 11 and the second composite electrode sheet 12 even when the steel needle penetrates the first composite electrode sheet 11 and the second composite electrode sheet 12, and thereby effectively avoiding short-circuit of the battery 10 and improving the safety of the battery 10.

[0145] Please refer to Figure 35 and Figure 36, the first composite electrode tab 11 includes a first electrode 161, a second electrode 162, and a first sub-tab 163. The first electrode 161 and the second electrode 162 are electrically connected to opposite ends of the first heating layer 115 respectively. The first sub-tabs 163 of multiple first composite electrode tabs 11 are welded to form a first tab 16. The first sub-tab 163 is electrically connected to the first current collector body 113. The first sub-tab 163 is electrically connected to the second electrode 162. The second composite electrode tab 12 includes a second sub-tab 164. The second sub-tab 164 is electrically connected to the second current collector body 123 of the second composite electrode tab 12. The second sub-tab 164 is electrically connected to the first electrode 161 through a heating switch 165. It can be understood that the first composite electrode tab 11 is a positive electrode tab, and the first sub-tab 163 is a positive electrode tab. The second composite electrode tab 12 is a negative electrode tab, and the second sub-tab 164 is a negative electrode tab. The first electrode 161 and the second electrode 162 are opposite poles of the first heating layer 115 respectively. The first electrode 161 of the first heating layer 115 is electrically connected to the first sub-tab 163, specifically by welding. The second electrode 162 of the first heating layer 115 is connected to the second sub-tab 164 through the heating switch 165. Thus, the first heating layer 115 is arranged in parallel with the first sub-tab 163 of the first composite electrode tab 11 and the second sub-tab 164 of the second composite electrode tab 12. In other words, the first heating layer 115 is arranged in parallel with the first sub-tab 163 and the second sub-tab 164 of the battery cell 1. Thus, the first heating layer 115 can share a part of the charging circuit with the battery cell 1. Thus, when the battery cell 1 is connected to an external power source 200, by controlling the heating switch 165 to conduct, the external power source 200 supplies power to the first heating layer 115.

[0146] Please refer to Figure 37 , the battery 10 includes a third surface 103 and a fourth surface (not shown, located on the Figure 36 back side) arranged opposite to each other, and a first side surface 105 and a second side surface 106 arranged opposite to each other and connected between the third surface 103 and the fourth surface. The first heating layer 115 is arranged corresponding to the first side surface 105 and the second side surface 106. The first protective layer 114 is arranged corresponding to the third surface 103 and the fourth surface. It can be understood that the third surface 103 and the fourth surface are the front and back surfaces of the battery 10. Generally speaking, the front and back surfaces of the battery 10 are the positions where puncture tests or lithium crystallization are likely to occur during puncture. By arranging the first protective layer 114 on the third surface 103 and the fourth surface, the puncture of the battery 10 can be protected most effectively. In addition, by arranging the first heating layer 115 on the first side surface 105 and the second side surface 106, the positions of the first heating layer 115 and the first protective layer 114 can be reasonably allocated, and the first heating layer 115 heats the battery 10 from the first side surface 105 and the second side surface 106, and the heat is conducted from both ends of the battery 10 to the middle to improve the temperature uniformity of the battery 10.

[0147] The electronic device 100 further includes a controller (not shown). The battery 10 further includes a temperature sensor (not shown). The temperature sensor can be disposed on the protection board 2 of the battery 10, inside the battery cell 1 or at other positions. The temperature sensor is used to detect the temperature of the battery 10. The controller is configured to control the heating switch 165 to conduct the second sub-tab 164 and the first electrode 161 when the temperature of the battery 10 is less than the minimum value of the preset range or within the preset range. The controller is further configured to control the heating switch 165 to disconnect the second sub-tab 164 from the first electrode 161 when the temperature of the battery 10 is greater than the maximum value of the preset range.

[0148] Further, a resistor may be provided between the first electrode 161 of the first heating layer 115 and the second sub-tab 164, and the resistor may be a variable resistor. The controller adjusts the resistance value of the variable resistor to adjust the current of the first heating layer 115, so as to adjust the heating rate of the first heating layer 115.

[0149] When the temperature detected by the temperature sensor is less than the minimum value (10 °C) of the preset range (the preset range is the normal fast charging range of the battery 10, such as 10 - 60 °C), the battery 10 is affected by low temperature, resulting in a decrease in the internal reaction rate and other reasons, so that fast charging cannot be achieved or lithium crystallization is likely to occur, thus affecting the normal operation of the battery 10 and even bringing safety problems; at this time, the controller controls the heating switch 165 to conduct the second sub-tab 164 and the first electrode 161 under the feedback signal of the temperature sensor, so that the first heating layer 115 is heated, the first composite electrode plate 11 generates Joule heat, and the battery 10 enters the self-heating mode. In this way, heat is generated inside the battery cell, which can quickly increase the temperature inside the battery cell 1, thereby increasing the internal reaction rate of the battery 10, increasing the charging rate of the battery 10, reducing the generation and growth of lithium crystallization, and reducing the safety problems of the battery 10.

[0150] When the temperature detected by the temperature sensor is within the normal charging temperature range of the battery 10 (such as 10 - 60 °C), in the ultra-fast charging mode, the controller can control the heating switch 165 to conduct the second sub-tab 164 and the first electrode 161, so that the first heating layer 115 is heated, and the first composite electrode plate 11 generates Joule heat. In this way, heat is generated inside the battery cell 1, which can effectively increase the charging rate. For example, the normal fast charging rate of the battery cell 1 is 1.5C (C is used to represent the charge and discharge capacity rate of the battery 10). After heating to 50 °C, the charging rate starts at 3C fast charging mode, and the charging speed of the battery 10 can be greatly improved after heating.

[0151] When the temperature detected by the temperature sensor is greater than the maximum value of the preset range (such as 60 °C), the controller can control the heating switch 165 to disconnect the second sub-tab 164 from the first electrode 161, so that the first heating layer 115 stops heating to avoid the temperature of the battery 10 from being too high.

[0152] In the embodiment of the present application, for the battery 10 provided, by disposing the first heating layer 115 on the first current collector body 113, and electrically connecting the first electrode 161 of the first heating layer 115 to the first sub-tab 163 of the first composite electrode 11, and connecting the second electrode 162 of the first heating layer 115 to the tab 164 of the second composite electrode 12 through the heating switch 165, the controller controls the on / off of the heating switch 165 to control the heating and stop heating of the first heating layer 115, which can effectively solve the problem of low internal reaction rate of the battery 10 at low temperatures (lower than the normal charging temperature of the battery 10), and can further increase the charging rate at non-low temperatures. Thus, in the case of extremely small changes in the structure of the battery 10 and extremely small increase in the volume of the battery 10 in the present application, not only can the problem of low charging rate or inability to charge normally at low temperatures be effectively solved, but also the rated charging rate of the battery 10 design can be effectively exceeded, and the charging speed of the battery 10 can be greatly increased.

[0153] Of course, in other embodiments, when the battery 10 is not connected to the external power supply 200, the controller controls the heating switch 165 to conduct the second sub-tab 164 and the first electrode 161. At this time, the first composite electrode 11 and the second composite electrode 12 can supply power to the first heating layer 115 to achieve self-heating of the battery 10.

[0154] In one embodiment, please refer to Figure 38 , each composite electrode includes a first heating layer 115. The first heating layer 115 includes a heating wire 166. The electronic device 100 further includes a detector (not shown). The detector is used to detect the on / off of the heating wire 166 to obtain the position where the battery 10 is punctured. The detector is used to detect whether there is current in the heating circuit of the first heating layer 115 when the heating switch 165 is turned on. When there is current in the heating circuit of the first heating layer 115, it indicates that the structure of the first heating layer 115 is intact. When there is no current in the heating circuit of the first heating layer 115, it indicates that the structure of the first heating layer 115 itself is broken. Thus, it indicates that the puncture may penetrate the first heating layer 115. When each composite electrode is provided with a first heating layer 115, if the detector detects that there is no current in the heating circuit of a certain first heating layer 115 when the heating switch 165 is turned on, it can be determined that there is a puncture at the composite electrode where the first heating layer 115 is located. At this time, other heating layers or all heating layers near the composite electrode can be controlled to heat, so as to slow down the further growth of the puncture and reduce the safety of the battery 10.

[0155] By improving the current collector of the battery 10, without additionally changing the structure of the battery 10, the fast charging problem of the battery 10 at low temperatures can be solved, and at the same time, the safety performance of the battery 10 can be improved. It can be compatible with various types of batteries 10 and is suitable for mass production.

[0156] The above are some embodiments of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present application.

Claims

1. A composite current collector, characterized in that, it includes: a current collection body including a first surface and a second surface arranged opposite to each other; a first protective layer, the elongation rate of the first protective layer being greater than that of the current collection body; the first protective layer includes a protective body and an active material part, the active material part being arranged on the surface or inside the protective body, and the active material part being used for electrochemically reacting with the electrolyte; a first heating layer, the first heating layer being used for heating the composite current collector under energization, the material of the first heating layer being a conductive material, and the first heating layer being electrically connected to the current collection body; the first heating layer and the first protective layer are located on the same layer, and the first heating layer and the first protective layer are arranged on the first surface of the current collection body; or, at least part of the first heating layer and at least part of the first protective layer are embedded in the current collection body. When the first protective layer is embedded in the current collection body, the current collection body has at least one bearing surface for arranging an active material layer; the current collection body further includes at least one through hole, one end opening of the through hole being arranged on the bearing surface; the other end opening of the through hole is directly opposite to the first protective layer, and part of the active material layer is filled in the through hole; and / or, at least part of the first heating layer is embedded in the first protective layer; and / or, at least part of the first heating layer is arranged on the surface of the first protective layer; a second protective layer, the second protective layer being arranged on the second surface or between the first surface and the second surface, the orthographic projection of the second protective layer on the first heating layer covering the first heating layer, and the elongation rate of the second protective layer being greater than that of the current collection body.

2. The composite current collector according to claim 1, characterized in that, the composite current collector further includes a second heating layer, the second heating layer being a conductive material, the second heating layer being electrically connected to the current collection body, the second heating layer being arranged on the second surface or between the first surface and the second surface, and the orthographic projection of the second heating layer on the first protective layer covering the first protective layer.

3. The composite current collector according to any one of claims 1 to 2, characterized in that, the first protective layer includes a protective body and a functional part, the functional part being arranged on the surface or inside the protective body, and the functional part being used for electrically conducting with the current collection body and / or for conducting the temperature of the first heating layer.

4. The composite current collector according to claim 1, characterized in that, the number of the through holes is multiple, and the multiple through holes are arranged on one side or opposite sides of the first protective layer.

5. The composite current collector according to any one of claims 1 to 2, characterized in that, the first protective layer includes a porous structure and a plurality of magnetic particles arranged in the porous structure.

6. The composite current collector according to claim 5, characterized in that, the material of the magnetic particles is a conductive material; or, the magnetic particles include a magnetic core and an insulating coating layer covering the magnetic core.

7. A composite electrode, characterized in that, Comprising an active material layer and the composite current collector according to any one of claims 1 to 6, wherein the active material layer is disposed on one side or opposite sides of the composite current collector.

8. A battery, characterized in that it comprises a plurality of composite electrode sheets according to claim 7.

9. The battery according to claim 8, characterized in that the plurality of composite electrode sheets include a first composite electrode sheet and a second composite electrode sheet arranged adjacent to each other. The first composite electrode sheet includes a first electrode, a second electrode and a first sub-tab. The first electrode and the second electrode are respectively electrically connected to opposite ends of the first heating layer of the first composite electrode sheet; the first sub-tab is electrically connected to the current collecting body of the first composite electrode sheet, and the first sub-tab is electrically connected to the second electrode; the second composite electrode sheet includes a second sub-tab, the second sub-tab is electrically connected to the current collecting body of the second composite electrode sheet, and the second sub-tab is electrically connected to the first electrode through a heating switch.

10. The battery according to claim 9, characterized in that the battery includes a third surface and a fourth surface arranged opposite to each other, and a first side surface and a second side surface arranged opposite to each other and connected between the third surface and the fourth surface. The first heating layer is arranged corresponding to the first side surface and the second side surface, and the first protective layer is arranged corresponding to the third surface and the fourth surface.

11. An electronic device, characterized in that it includes the battery according to claim 9 or 10.

12. The electronic device according to claim 11, characterized in that the electronic device includes a controller, and the battery further includes a temperature sensor for detecting the temperature of the battery. The controller is configured to control the heating switch to conduct the second sub-tab and the first electrode when the temperature of the battery is less than the minimum value of the preset range or within the preset range, and the controller is further configured to control the heating switch to disconnect the second sub-tab and the first electrode when the temperature of the battery is greater than the maximum value of the preset range.

13. The electronic device according to claim 12, characterized in that the first heating layer includes a heating wire, and the electronic device further includes a detector for detecting the on / off of the heating wire to obtain the position where the battery is punctured.

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