An integrally conductive composite current collector film

Abstract

The present invention discloses an integrally conductive composite current collector film, comprising a polymer support layer and conductive coatings located on both sides of the polymer support layer, with a plurality of through holes distributed on the polymer support layer. The through holes are filled with conductive coating material, so that the conductive coatings on both sides are connected, and the filling density of the conductive coating material in the through holes is above 99.8%. The through hole comprises a first surface with an opening located on the upper surface of the polymer support layer, with a large upper opening and a small lower opening, and a third surface connected end to end with the small opening of the first surface, as well as second and fourth surfaces symmetrical to the first and third surfaces relative to the middle surface of the polymer support layer, and the small openings of the third and fourth surfaces are connected to form the throat of the through hole. Before being filled with the conductive coating material, the inner wall of the through hole has a stepped hydrophobic property that gradually increases from the throat of the through hole to the surface of the polymer support layer. The composite current collector film has an electrical conductivity of 2×10 7 ‑5.7×10 7 S / m, and the peel strength between the conductive coating and the polymer support layer is 650-1150N / m.

Description

Technical Field

[0001] The present invention relates to the technical field of battery energy storage, and in particular to an integrally conductive composite current collector film. Background Art

[0002] As energy providers, lithium-ion batteries play an irreplaceable role in mobile communications, wearable electronics, new energy vehicles, and stationary energy storage. Currently, the energy density of lithium-ion batteries has been developed to near its theoretical limit at the electrochemical reaction level. However, there is still room for further improvement in the mass and volume energy densities of battery cells.

[0003] Recently, researchers have tried to use a composite current collector with a thin, insulating polymer support layer in the middle and copper or aluminum conductive coatings on the upper and lower surfaces of the polymer support layer, in order to replace the copper foil and aluminum foil current collectors currently used in industry. However, because the polymer support layer of this composite current collector insulates and isolates the upper and lower surface conductive coatings, it cuts off the electron transmission in the thickness direction of the composite current collector. During charging and discharging, the active materials on the upper and lower surfaces of each composite current collector can only transfer electrons through the conductive coatings on that surface respectively. Therefore, in order to make the electron lateral transmission area of ​​each side meet the conductivity requirements of the battery, the conductive coatings deposited on the upper and lower surfaces of the polymer support layer need to reach a thickness of more than 1μm. To prepare such a thick conductive coating, the thickness of the matching polymer support layer also needs to reach 4-6μm. This causes some problems with this composite current collector. For example, the thicker conductive coating on the one hand puts pressure on the vacuum chamber in the industry. The realization of the coating process has brought pressure, and on the other hand, it has also limited the further lightness and thinness of the current collector. Since the upper and lower surface conductive coatings are not conductive to each other, it is necessary to weld the tabs on the upper and lower surfaces of the composite current collector respectively. The double-sided welding of the tabs reduces the yield rate of the tab welding process. In addition, it also puts pressure on the process and equipment transformation of the single-sided welding of the tabs used in the current copper and aluminum foil current collector industrialization process. In addition, the copper and aluminum conductive coatings are only simply attached to the polymer support layer, and the bonding force is weak. During the battery charge and discharge cycle, the repeated phase change of the electrode can easily lead to problems such as current collector deformation, conductive coating shedding, electrolyte immersion corrosion, etc., resulting in electrode failure and battery safety hazards. The above problems have greatly limited the industrialization and promotion of composite current collectors. Summary of the Invention

[0004] To solve the above problems, the present invention proposes an integrally conductive composite current collector film. The composite current collector film is lighter and thinner, and the conductive coating on the polymer support layer has a higher bonding strength. The application of the composite current collector film is conducive to improving the mass energy density, volume energy density, cycle stability and production efficiency of the battery.

[0005] The overall conductive composite current collector film of the present invention comprises a polymer support layer and conductive coatings located on both sides of the polymer support layer. The polymer support layer is provided with a plurality of through holes, and the porosity of the through holes is 1-10%. The through holes are filled with a conductive coating material so that the conductive coatings on both sides are connected. The filling density of the conductive coating material in the through holes is above 99.8%. The thickness of the conductive coating is 0.1-0.5 μm. The composite current collector film has an electrical conductivity of 2×10 7 -5.7×10 7 S / m; when the composite current collector film is used, only one side of the electrode ear needs to be welded to conduct the active materials on and below the composite current collector film.

[0006] The through hole comprises a first surface with an opening located on the upper surface of the polymer support layer and a second surface with an opening located on the lower surface of the polymer support layer. The first surface is an inverted cone with a larger opening at the upper end and a smaller opening at the lower end. The second surface and the first surface are symmetrical relative to the mid-plane of the polymer support layer in the thickness direction. The diameter of the largest opening of the first surface is less than 3 μm. The through hole also comprises a third surface and a fourth surface, symmetrical relative to the mid-plane of the polymer support layer in the thickness direction. The third surface is an inverted cone that connects end-to-end with the small opening of the first surface. The small openings of the third and fourth surfaces connect to form the throat of the through hole. The throat diameter of the through hole is 0.5-1 μm. The taper angle between the first and second surfaces is in the range of 90-180°, and the taper angle between the third and fourth surfaces is in the range of 35-130°. The taper angle between the third and fourth surfaces is smaller than the taper angle between the first and second surfaces. The junctions between the first and third surfaces and the junctions between the second and fourth surfaces each have an outwardly protruding knee. The hole depth a of the third surface and the thickness h of the polymer support layer satisfy the relationship 2a>0.5h.

[0007] The thickness of the composite current collector film is 0.7-2.5 μm, and the thickness of the polymer support layer is 0.5-1.5 μm.

[0008] Before being filled with the conductive plating material, the inner wall of the through-hole exhibits a stepped hydrophobicity that gradually increases from the throat of the through-hole toward the surface of the polymer support layer, with weaker hydrophobicity near the throat. The oxygen:carbon ratio (b) of the through-hole inner wall is within a range of 10-35%, with this ratio gradually decreasing from the throat toward the surface of the polymer support layer. The b value of the inner wall near the polymer support layer surface is within a range of 10-20%, while the b value of the inner wall at the throat is within a range of 25-35%, and the b value of the inner wall at the throat is 10-20% higher than the b value of the inner wall near the polymer support layer surface.

[0009] The peel strength between the conductive coating and the polymer support layer is 650-1150 N / m.

[0010] The through holes are generated by laser drilling, and the laser wavelength used in the laser drilling is 240-260nm.

[0011] The composition of the polymer support layer comprises at least one or / and derivatives thereof in polyethylene terephthalate (PET), polycarbonate (PC), polyvinyl chloride (PVC), polyacrylonitrile (PAN), butadiene, styrene, polypropylene (PP), polyethylene, phenolic acid, polyurethane, polyimide (PI), polyamide, polyoxymethylene, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyaryletherketone, polytetrafluoroethylene (PTFE), tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, trifluorochloroethylene-ethylene copolymer, polyethylene terephthalate nitrile etc. In a preferred embodiment, the composition of the polymer support layer is polyethylene terephthalate (PET) or polycarbonate (PC). The composition of the conductive coating is one or more selected from copper, aluminum, silver, nickel, molybdenum, titanium, niobium, iron, zinc, stainless steel, graphene, carbon nanotube, ketjen black, acetylene black, graphite powder and carbon fiber. In a preferred embodiment, the composition of the conductive coating is copper or aluminum.

[0012] The present invention has through holes distributed on the polymer support layer, which are filled with conductive coating materials, so that the conductive coatings on both sides are connected, and the upper and lower surface conductive coatings are interconnected to form a conductive whole. This makes the overall conductive composite current collector film in the present invention expand the electron lateral transmission path compared with the composite current collector in the background art. In addition, the porosity of the through holes on the polymer support layer is designed to be 1-10%, and the thickness of the conductive coating is reduced to 0.1-0.5 μm, so that the composite current collector film reaches 2×10 7 -5.7×10 7 The high conductivity of S / m allows the thickness of the composite current collector film to be further reduced to 0.7-2.5μm. The thinning of the current collector, on the one hand, reduces the weight proportion of inactive material components in the battery cell and improves the weight energy density of the battery. On the other hand, it makes the electrode sheet relatively thinner and improves the volume energy density of the battery. In addition, filling the through hole with a conductive coating can tightly connect the polymer support layer and the conductive coating on the upper and lower surfaces into a whole, greatly improving the bonding force between the polymer support layer and the conductive coating. Increasing the bonding force between the polymer support layer and the conductive coating can inhibit the desorption of the conductive coating and the polymer support layer, improve the stability of the electrode sheet in the electrolyte, and extend the cycle life of the battery.

[0013] The present invention finds that although filling the through-holes of the polymer support layer with a conductive coating material can improve the conductivity of the current collector and the bonding strength between the polymer support layer and the conductive coating, thereby improving the energy density and cycle life of the battery using the current collector, the degree of filling of the conductive coating material in the through-holes will affect the degree of improvement in the conductivity of the composite current collector and the performance of the battery, as well as the stability and safety of the battery. If the through-hole is not completely filled with the conductive coating material, but only the conductive coating is formed on the inner wall of the through-hole, the electrolyte will accumulate in the unfilled space of the through-hole due to capillary action, causing the conductive coating to be corroded and cracked, the electrolyte to be unevenly distributed, and the electrode to fail. If the conductive coating is formed on the inner wall of the through-hole and the electrode material is filled in the remaining space of the through-hole, the repeated contraction and expansion of the electrode material in the through-hole during charging and discharging will change the shape of the through-hole, causing the conductive coating in the through-hole to desorb from the polymer support layer under the action of the stress of the electrode material and the corrosion of the electrolyte, causing the electrolyte to penetrate from the inside of the through-hole along the interface between the conductive coating and the polymer support layer, corroding the polymer support layer, causing the polymer support layer to swell, and ultimately causing the electrode to fail. In the composite current collector film of the present invention, the through-hole needs to be completely filled with the conductive coating material.

[0014] When a conductive coating material is used to fill a through-hole, if the conductive coating material filled in the through-hole has filling defects such as pores and looseness, it will cause the composite current collector to have local uneven resistance or a virtual connection of the conductive material inside the through-hole. The present invention has found that the conductive coating prepared by the liquid phase method and the chemical method and the filling of the through-hole will have defects such as bubbles, pores, looseness, and additional elements, and the conductivity is much lower than the theoretical conductivity. This will lead to the need to increase the thickness of the conductive coating, affecting the improvement of the battery energy density. On the other hand, due to the defects, the composite current collector causes the electrode to be corroded by the electrolyte, affecting the safety of the battery. In the present invention, a vacuum coating method is used to prepare the conductive coating and its filling of the through-hole, and the vacuum coating method is selected from one of magnetron sputtering, vacuum evaporation and vacuum ion plating.

[0015] The present invention simulates and studies the filling process of polymer support layer through-holes using vacuum coating. It is found that when the inner wall surface of the through-hole is neutral or hydrophilic, once the vacuum coating material atoms are deposited and attached to the inner wall of the through-hole to form a filling, they will prevent the plating material atoms from further filling the space below the already formed filling area; or the plating material atoms that reach the through-hole wall will tend to attach to the through-hole wall. When the plating material atoms further expand radially to fill the through-hole on this basis, at the microscopic level, the radially expanding plating material atoms will still be subjected to a pulling force toward the inner wall of the through-hole. This pulling between microscopic particles will cause micro defects such as pores in the filling. In the practice of the present invention, the vacuum coating method is used to conduct filling experiments on through-holes with neutral or hydrophilic inner walls. Although the through-holes have been completely filled with conductive coating materials, microstructural analysis of the filling cross-section reveals that a certain proportion of imperceptible defects, such as micropores or micro-bridge defects, exist within the filling. Although this subtle defect occurs in a small proportion, it will still affect the conductivity of the current collector and the bonding strength between the conductive coating and the polymer support layer. During long-term battery charge and discharge cycles, there is a risk of electrolyte penetration, which can easily cause electrode failure, affect the battery's cycle life, and even cause battery safety accidents.

[0016] The present invention overcomes technical prejudices within the industry. Before being filled with a conductive coating material, the inner wall of the through-hole exhibits a stepped hydrophobicity that gradually increases from the throat of the through-hole toward the surface of the polymer support layer, while the inner wall of the through-hole near the throat exhibits weaker hydrophobicity. The degree of stepped hydrophobicity of the through-hole inner wall is controlled by surface modification of the through-hole inner wall to control the oxygen-to-carbon ratio of the inner wall, thereby achieving the outstanding technical effect of completely filling the through-hole with the conductive coating material. The surface modification achieves an oxygen-to-carbon ratio (b) within the through-hole inner wall within a range of 10-35%, with this ratio gradually decreasing from the throat toward the surface of the polymer support layer. The b value of the inner wall near the polymer support layer surface is within a range of 10-20%, while the b value of the inner wall at the throat is within a range of 25-35%, and the b value of the inner wall at the throat is 10-20% higher than the b value of the inner wall near the polymer support layer surface. The hydrophobicity gradient of the through-hole inner wall with this oxygen-carbon element ratio distribution characteristic provides a suitable top-down driving trend for the plating material atoms incident on the surface. In order to cooperate with the stepped hydrophobic structure characteristics of the through-hole inner wall, the through-hole of the present invention is provided with a first surface and a third surface having the aforementioned structural and shape characteristics, a second surface and a fourth surface symmetrical with respect to the center plane of the polymer support layer, and a throat. Since the first and third surfaces and the second and fourth surfaces are symmetrically arranged, the first and third surfaces are used as examples to illustrate the complete filling process of the conductive plating layer in the through-hole. The relatively open first surface allows a large number of plating material atoms to be incident on the inner wall of the first surface or the third surface, and the hydrophobicity gradient of the inner wall provides a top-down driving trend for the plating material atoms incident on the surface, driving them toward the throat instead of staying in place. The plating material atoms with a larger initial velocity at the time of incidence are slightly accelerated by the hydrophobic gradient of the first surface, and have a higher velocity when they reach the knee where the first surface and the third surface meet along the first surface, so that these plating material atoms will break away from the inner wall of the through hole and fly out to the space in the third surface when passing through the knee. Since the initial velocities at the time of incidence are different, the lengths of the micro-acceleration paths along the first surface are also different, so the flight paths and flight distances of these atoms flying out to the space in the third surface are also diversified; the plating material atoms with a smaller initial velocity at the time of incidence are driven by the hydrophobic gradient to reach the knee along the first surface, and have different velocities. It is enough to break away from the inner wall of the through-hole and fly out, and still move toward the throat along the third surface; the plating atoms flying out of the space in the third surface cross-incident, contact each other to form atomic clusters, and in the subsequent flight process, mutual collision and contact occur between atoms and atomic clusters and between atomic clusters, and gradually contact and adhere to form larger atomic clusters in the process of moving toward the throat. The large atomic clusters keep flying or fall on the inner wall of the through-hole and move along the inner wall, and are all moving toward the throat. As the flight speed of the large atomic clusters decreases or as the hydrophobicity of the inner wall of the through-hole gradually weakens, the movement trend of the large atomic clusters also slows down.When large atomic clusters move to the throat, because the throat has the weakest hydrophobicity or is close to neutral, and the throat has the smallest pore size, multiple large atomic clusters stay in the throat and generate support and compression, forming a filling. Subsequently, atoms or atomic clusters moving or flying along the inner wall of the through-hole form a bottom-up layer-by-layer deposition filling based on the throat filling. During the deposition and filling process (including throat filling), because the inner wall of the through-hole at the deposition location is hydrophobic, the inner wall will continuously push the atomic clusters toward the center, then first squeeze and compact them in the middle, and then gradually expand and grow radially outward until a gapless filling is formed between the inner wall. This process allows the conductive plating material to form a dense, gapless and complete filling in the through-hole, with a filling density of more than 99.8%, greatly avoiding the existence of micro-defects such as micropores or micro-bridges during filling. The pore size, taper angle, hole depth and other structural features of the first, second, third and fourth surfaces of the through-hole match the hydrophobicity of the hole wall of each section of the through-hole, together allowing the conductive plating material to form a complete filling in the through-hole.

[0017] In the present invention, the throat aperture is 0.5-1 μm. If the throat aperture is too small, the through-hole connection channel is too narrow, which will limit the smooth and effective connection between the conductive plating layers on the upper and lower surfaces of the polymer support layer. If the throat aperture is too large, it will be difficult for the plating material atomic groups to form a good and complete filling in the throat during the filling process.

[0018] When the through-hole porosity is too low, the area of ​​connection between the conductive coatings on the upper and lower surfaces of the polymer support layer is small, resulting in a smaller conductive area for the current collector and poor battery performance. When the porosity is too high, the strength of the composite current collector film and its industrialization process are compromised. In the present invention, the through-hole porosity is 1%-10%, providing ample connection area between the conductive coatings on the upper and lower surfaces of the polymer support layer. The overall conductive composite current collector film has high conductivity, meeting battery charging and discharging requirements.

[0019] The through-holes in the present invention are created by laser drilling. In a preferred embodiment, the laser used has a wavelength of 240-260 nm. Lasers with wavelengths of 157-353 nm are deep ultraviolet excimer lasers, which have short wavelengths, high frequencies, and large photon counts. The present inventors discovered that using a laser with a wavelength of 240-260 nm to drill holes in the polymer support layer utilizes a non-thermal photochemical reaction, where high-energy photons break chemical bonds in the polymer, separating the target area material from the substrate. On the one hand, this process is different from the thermal etching principle of traditional laser drilling. It will not cause the ablation expansion area based on the designed aperture, affecting the precise preparation of the aperture. On the other hand, the laser drilling process in this wavelength range will not change the chemical composition of the through-hole wall, laying the foundation for the subsequent control of the hole wall surface modification process to construct the stepped hydrophobic characteristics of the through-hole inner wall (the step-by-step hydrophobicity degree of the through-hole inner wall is controlled by controlling the oxygen-carbon element ratio of the inner wall through the surface modification process of the through-hole inner wall). In addition, the polymer support layer after drilling will not produce wrinkles caused by the thermal etching process, thereby ensuring the flatness of the composite current collector film, thereby achieving the stability of the electrode sheet and improving the cycle life of the battery.

[0020] The overall conductive composite current collector film of the present invention has the following beneficial effects:

[0021] (1) The through holes distributed on the polymer support layer are filled with conductive coating materials, so that the conductive coatings on both sides are connected, making the composite current collector film a conductive whole. During the battery charging and discharging process, the active materials on the upper and lower surfaces of the overall conductive composite current collector film can share the conductive coating on the composite current collector film for electron transfer, which improves the ohmic impedance consistency of the battery in practical applications and ensures the consistency of electron transfer of the active materials at the interface of the composite current collector film, thereby promoting the consistency of the active material charge state, avoiding the mismatch and cracking of the active material particles due to shrinkage and expansion, and improving the battery cycle life and safety.

[0022] (2) The present invention has through holes distributed on the polymer support layer, which are filled with conductive coating materials, so that the conductive coatings on both sides are connected, and the upper and lower surface conductive coatings are interconnected to form a conductive whole. This makes the overall conductive composite current collector film in the present invention expand the electron lateral transmission path compared with the composite current collector in the background art. Combined with the porosity of the through holes on the polymer support layer designed to be 1-10%, the thickness of the conductive coating is reduced to 0.1-0.5 μm, so that the composite current collector reaches 2×10 7 -5.7×10 7The high conductivity of 500 S / m allows the thickness of the composite current collector film to be further reduced to 0.7-2.5μm. This thinning of the current collector not only reduces the weight proportion of inactive material components in the battery cell, improving the battery's gravimetric energy density, but also makes the electrode sheet relatively thinner, increasing the battery's volumetric energy density. In addition, the thinning of the conductive coating thickness of the overall conductive composite current collector film significantly reduces the process time for conductive coating preparation, improving the production efficiency of industrial production.

[0023] (3) The conductive coating is densely filled in the through hole with a filling density greater than 99.8%, and the conductive coatings on the upper and lower surfaces of the polymer support layer are tightly connected as a whole. The bonding force between the polymer support layer and the conductive coating is greatly improved, which inhibits the desorption of the conductive coating and the polymer support layer, improves the stability of the electrode sheet in the electrolyte, and extends the cycle life of the battery.

[0024] (4) The conduction of the conductive coatings on the upper and lower surfaces of the polymer support layer allows the conductive coatings on the upper and lower surfaces to share the same tab to transmit electrons. Therefore, the overall conductive composite current collector film of the present invention only needs to weld the tab on one side, which overcomes the problem of low yield of the tab welding process caused by the double-sided welding of the tabs of the composite current collector in the prior art. In addition, the single-sided welding of the tabs of the composite current collector film of the present invention can still use the single-sided welding of the tab process and equipment adopted in the current copper and aluminum foil current collector industrialization process, which is conducive to simplifying the process and matching the existing production line, reducing the failure rate of battery production, improving battery production efficiency, and reducing battery production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the partial cross-sectional structure of the overall conductive composite current collector film of the present invention;

[0026] Figure 2 It is a three-dimensional schematic diagram of a partial cross section of a polymer support layer with through holes in the present invention.

[0027] The accompanying drawings are not drawn to scale and are intended to illustrate the basic principles and basic structure of the present invention. The implementation methods covered by the technical solution of the present invention are not limited to the implementation methods and examples shown in the accompanying drawings. DETAILED DESCRIPTION

[0028] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0029] Figure 1 Schematic diagram of the cross-sectional structure of the overall conductive composite current collector film of the present invention. Figure 1As shown, the overall conductive composite current collector film of the present invention includes a polymer support layer 1 and conductive coating layers 2 and 3 located on both sides of the polymer support layer. A plurality of through holes 4 are distributed on the polymer support layer, and the porosity of the through holes is 1-10%. The through holes are filled with a conductive coating material so that the conductive coating layer 2 and the conductive coating 3 are connected. The filling density of the conductive coating material in the through holes is greater than 99.8%. The thickness of the conductive coating layer 2 and the conductive coating 3 are both 0.1-0.5 μm. The composite current collector film has an electrical conductivity of 2×10 7 -5.7×10 7 S / m; when the composite current collector film is used, only one side of the electrode ear needs to be welded to conduct the active materials on and below the composite current collector film.

[0030] Figure 2 3D schematic cross-sectional view of the polymer support layer with through holes in the present invention. Figure 2 As shown, the through hole 4 in the polymer support layer 1 includes a first surface 5 with an opening located on the upper surface of the polymer support layer and a second surface 8 with an opening located on the lower surface of the polymer support layer. The first surface 5 is an inverted cone with a larger opening at the top and a smaller opening at the bottom. The second surface and the first surface are symmetrical with respect to the mid-plane of the polymer support layer in the thickness direction. The diameter of the largest opening of the first surface 5 is less than 3 μm. The through hole also includes a third surface 6 and a fourth surface 7, which are symmetrical with respect to the mid-plane of the polymer support layer in the thickness direction. The third surface 6 is an inverted cone that connects end-to-end with the small opening of the first surface 5. The small openings of the third surface 6 and the fourth surface 7 connect to form the throat 10 of the through hole. The throat diameter of the through hole is 0.5-1 μm. The taper angle between the first and second surfaces is in the range of 90-180°, and the taper angle between the third and fourth surfaces is in the range of 35-130°. The taper angles of the third and fourth surfaces are smaller than those of the first and second surfaces. The junctions between the first and third surfaces and the junctions between the second and fourth surfaces have outwardly protruding knees 9 and 11, respectively. The pore depth a of the third surface and the thickness h of the polymer support layer satisfy the relationship of 2a>0.5h.

[0031] In one embodiment of the present invention, the thickness of the composite current collector film is 0.7-2.5 μm, and the thickness of the polymer support layer is 0.5-1.5 μm.

[0032] Before being filled with the conductive plating material, the inner wall of the through-hole is surface-modified to control the oxygen-to-carbon ratio of the inner wall, resulting in a stepped hydrophobicity that gradually increases from the throat of the through-hole toward the surface of the polymer support layer, with weaker hydrophobicity near the throat. The surface modification aims to maintain an oxygen-to-carbon ratio (b) within the through-hole wall within a range of 10-35%, with this ratio gradually decreasing from the throat toward the surface of the polymer support layer. The b value of the inner wall near the polymer support layer is within a range of 10-20%, while the b value of the inner wall near the throat is within a range of 25-35%, with the b value of the inner wall near the throat being 10-20% higher than that near the surface of the polymer support layer. This hydrophobic gradient of the through-hole wall, characterized by this oxygen-to-carbon ratio distribution, provides a suitable top-down driving tendency for plating material atoms incident on the surface. In a preferred embodiment, the stepped hydrophobicity of the inner wall of the through hole is achieved by the reaction of the process gas with the inner wall of the through hole, and the process gas can be at least one of common gaseous hydrocarbons such as CO, NO, CH4, H2S, PH3, SiH4, HI, HBr, alkanes, ammonia, etc.

[0033] Filling the through-hole with a conductive coating can tightly connect the polymer support layer and the conductive coatings on the upper and lower surfaces into a whole, thereby greatly improving the bonding force between the polymer support layer and the conductive coating. In the composite current collector film of the present invention, the peel strength between the conductive coating and the polymer support layer is 650-1150 N / m.

[0034] In a preferred embodiment of the present invention, the through holes on the polymer support layer are generated by laser drilling, and the laser wavelength used in the laser drilling is 240-260 nm.

[0035] In the present invention, a vacuum coating method is used to prepare the conductive coating layer and fill the through hole, and the vacuum coating method is selected from one of magnetron sputtering, vacuum evaporation and vacuum ion plating.

[0036] The composition of the polymer support layer of the present invention comprises at least one of polyethylene terephthalate (PET), polycarbonate (PC), polyvinyl chloride (PVC), polyacrylonitrile (PAN), butadiene, styrene, polypropylene (PP), polyethylene, phenolic acid, polyurethane, polyimide (PI), polyamide, polyoxymethylene, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyaryletherketone, polytetrafluoroethylene (PTFE), tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, trifluorochloroethylene-ethylene copolymer, polyethylene terephthalate nitrile etc. or / and its derivatives. In a preferred embodiment, the composition of the polymer support layer is polyethylene terephthalate (PET) or polycarbonate (PC). The composition of the conductive coating is one or more selected from copper, aluminum, silver, nickel, molybdenum, titanium, niobium, iron, zinc, stainless steel, graphene, carbon nanotube, Ketjen black, acetylene black, graphite powder and carbon fiber. In a preferred embodiment, the composition of the conductive coating is copper or aluminum.

[0037] The overall conductive composite current collector film of the present invention has through holes distributed on the polymer support layer, and the through holes are filled with conductive coating materials, so that the conductive coatings on both sides are connected, and the upper and lower surface conductive coatings are interconnected to form a conductive whole. This makes the overall conductive composite current collector film of the present invention expand the electron lateral transmission path compared with the composite current collector in the background art. In combination with the porosity of the through holes on the polymer support layer being designed to be 1-10%, the thickness of the conductive coating is reduced to 0.1-0.5 μm, so that the composite current collector film reaches 2×10 7 -5.7×10 7 The high conductivity of 500 S / m further reduces the thickness of the composite current collector film to 0.7-2.5 μm. However, since the polymer support layer of the composite current collector in the background art does not have a through-hole structure, the polymer support layer insulates and isolates the upper and lower surface conductive coatings, blocking the electron transmission in the thickness direction of the composite current collector. During charging and discharging, the active materials on the upper and lower surfaces of each composite current collector can only transfer electrons through the conductive coatings on the surface respectively. Therefore, in order to make the electron lateral transmission area of ​​each surface meet the conductivity requirements of the battery, the conductive coatings deposited on the upper and lower surfaces of the polymer support layer need to reach a thickness of more than 1 μm, and the overall thickness of this composite current collector will reach 3-5 μm.

[0038] The remarkable effects of the present invention are further illustrated below with reference to the embodiments and comparative examples.

[0039] First, the implementation of the integrally conductive composite current collector film of the present invention as a negative electrode current collector for a battery is discussed.

[0040] Example 1

[0041] (1) Preparation of integrally conductive negative electrode composite current collector film

[0042] This example was prepared as Figure 1 The overall conductive composite current collector film of the structure shown includes a polymer support layer and a conductive coating. The polymer support layer has multiple through-holes distributed therein, which are filled with conductive coating material to connect the conductive coatings on both sides. The overall conductive composite current collector film has a thickness of 2μm. The polymer support layer is made of PET flexible film. The specific preparation steps are as follows:

[0043] (1) Laser drilling is used to drill holes in the thickness direction of 1 μm thick PET with a porosity of 5%. The through holes have the following characteristics: Figure 2 The structure shown, the aperture parameters of each part of the through hole are shown in Table 1, and the laser wavelength is 240-260nm;

[0044] (2) CO gas is introduced into the through-hole to modify the surface of the inner wall of the through-hole, so that the inner wall of the through-hole has a step-wise hydrophobic property that gradually increases from the throat of the through-hole to the surface of the polymer support layer, and the inner wall of the through-hole near the throat has weak hydrophobicity;

[0045] (3) A metallic copper coating layer with a thickness of 0.5 μm and a purity of more than 99.9% was deposited on the upper and lower surfaces of the perforated PET base film by vacuum evaporation to form a 2 μm thick overall conductive composite current collector film; during vacuum evaporation, the background vacuum of the coating chamber was 5×10 -2 Pa, evaporation temperature 1620 ° C, film speed 100m / min. Through cross-sectional microscopic examination of the through-hole filling, it was found that the coating material formed a dense and gapless filling of the through-hole, with a filling density of 99.9%.

[0046] (2) Electrode sheet preparation and battery assembly

[0047] The negative electrode current collector is a monolithically conductive composite current collector film prepared in (1) above, with graphite as the active material. The positive electrode current collector is a 10μm aluminum foil with lithium cobalt oxide as the active material. The electrolyte is a carbonate solution containing 1M LiPF6. The separator is Celgard 2400. The positive and negative electrode current collectors are welded to the tabs on one side to form a 2000mAh soft-pack battery. Because the negative electrode current collector is a monolithically conductive composite current collector film, both the positive and negative electrode current collectors can be welded to the tabs on one side, achieving a high yield of 99% in the tab welding process.

[0048] The battery assembled with the above-mentioned integrally conductive composite current collector film and the corresponding electrode sheets was tested, and the test results are shown in Table 2.

[0049] Comparative Example 1

[0050] Comparative Example 1 also uses Figure 1The composite current collector film of the structure shown includes a polymer support layer and a conductive coating. The polymer support layer has multiple through-holes distributed thereon, which are filled with a conductive coating material, connecting the conductive coatings on both sides. The thickness of the composite current collector film is 2 μm. The preparation steps of this composite current collector film are basically the same as those in Example 1, except that the surface modification of the inner wall of the through-hole makes it hydrophilic, rather than the stepped hydrophobicity in Example 1.

[0051] After vacuum evaporation deposited a 0.5μm thick copper coating with a purity of over 99.9% on both the upper and lower surfaces of the perforated PET, although the through-holes appeared well filled from the outside, cross-sectional microscopic examination of the through-hole filling revealed that the coating material did not completely fill the interior of the through-holes. A certain proportion of imperceptible defects, such as micropores or micro-bridging defects, existed within the filling, and the filling density was only 84.5%.

[0052] The composite current collector film was then used as the negative electrode current collector to prepare electrode sheets and assemble into a 2000 mAh soft pack battery, following the same steps as in Example 1. The battery assembled with the overall conductive composite current collector film and the corresponding electrode sheets was tested, and the test results are shown in Table 2.

[0053] Comparative Example 2

[0054] Comparative Example 2 also uses Figure 1 The composite current collector film of the structure shown includes a polymer support layer and a conductive coating. The polymer support layer has multiple through-holes distributed therein, which are filled with a conductive coating material, connecting the conductive coatings on both sides. The composite current collector film has a thickness of 2 μm. The preparation steps of this composite current collector film are essentially the same as those in Example 1, except that the inner walls of the through-holes are not subjected to specific hydrophobic or hydrophilic surface modification.

[0055] After vacuum evaporation deposited a 0.5μm thick copper coating with a purity of over 99.9% on both the upper and lower surfaces of the perforated PET, although the through-holes appeared well filled from the outside, cross-sectional microscopic examination of the through-hole filling revealed that the coating material did not completely fill the interior of the through-holes. A large proportion of defects, such as micropores or micro-bridging defects, existed within the filling, and the filling density was only 66.4%.

[0056] The composite current collector film was then used as the negative electrode current collector to prepare electrode sheets and assemble into a 2000 mAh soft pack battery, following the same steps as in Example 1. The battery assembled with the overall conductive composite current collector film and the corresponding electrode sheets was tested, and the test results are shown in Table 2.

[0057] Comparative Example 3

[0058] (1) Preparation of negative electrode composite current collector film

[0059] The composite current collector film includes a polymer support layer and a conductive coating. The polymer support layer does not have a through-hole structure. The composite current collector film has a thickness of 2.6 μm. The polymer support layer is made of PET flexible film. The specific preparation steps are as follows:

[0060] A 0.8 μm thick copper layer with a purity of more than 99.9% was deposited on the upper and lower surfaces of a 1 μm thick PET base film by vacuum evaporation to form a 2.6 μm thick composite current collector film. During vacuum evaporation, the background vacuum of the coating chamber was 5×10 -2 Pa, evaporation temperature 1620℃, film speed 100m / min.

[0061] (2) Electrode sheet preparation and battery assembly

[0062] The negative electrode current collector is the composite current collector film prepared in (1) above, with graphite as the active material. The positive electrode current collector is a 10μm aluminum foil with lithium cobalt oxide as the active material. The electrolyte is a carbonate solution containing 1M LiPF6. The separator is Celgard 2400, assembled into a 2000mAh soft-pack battery. The aluminum foil positive electrode current collector has a single-sided tab welded to it. However, because the composite current collector film of the negative electrode current collector is not entirely conductive, the tab welding of this negative electrode current collector requires double-sided tab welding. The yield of the tab welding process is only 93%.

[0063] The battery assembled with the composite current collector film and the corresponding electrode sheets was tested, and the test results are shown in Table 2.

[0064] Table 1. Comparison of characteristics of negative electrode composite current collector film examples and comparative examples

[0065]

[0066] Table 2. Performance comparison of negative electrode composite current collector film and corresponding battery

[0067]

[0068] From the comparison of the data in Table 1 and Table 2, we can see that:

[0069] Because the conductive coating in the through-holes of the polymer support layer of Example 1 connects the conductive coatings on the upper and lower surfaces of the polymer support layer into one, the overall conductive composite current collector film of Example 1 expands the electron lateral transmission path compared to the composite current collector film of Comparative Example 3. In addition, the conductive coating material completely fills the through-holes, with a filling density of 99.9%. Therefore, although the thickness of the conductive coating in Example 1 is only 0.5 μm, which is approximately 63% of the thickness of the conductive coating in Comparative Example 3, the average conductivity of the composite current collector film is significantly higher than that of Comparative Example 3, reaching 5.68×10 7 S / m high conductivity (close to the theoretical conductivity of copper foil), the 4C / 0.5C capacity retention performance associated with the battery in Example 1 is also significantly better than that in Comparative Example 3, and the battery rate performance is significantly improved. Compared with Comparative Example 3, the thickness of the composite current collector film in Example 1 is reduced by about 25%, and the energy density of the battery is also improved. In the composite current collector film of Example 1, the conductive coating material filled in the through-holes tightly connects the polymer support layer and the conductive coatings on the upper and lower surfaces as a whole, which greatly improves the bonding force between the polymer support layer and the conductive coating, and the peel strength reaches 668N / m, which is much higher than that of Comparative Example 3. Therefore, the 1C cycle 1000 cycle capacity retention performance associated with the battery in Example 1 is also much higher than that of Comparative Example 3, and the stability of the electrode sheet in the electrolyte and the cycle life of the battery are significantly improved.

[0070] Although the composite current collector films of Comparative Examples 1 and 2 also have through-holes filled with conductive materials, the inner walls of the through-holes do not have the stepped hydrophobicity of the embodiments, and the filling density is significantly reduced, affecting the connectivity between the upper and lower surface conductive coatings. Therefore, although their electrical conductivity and 4C / 0.5C capacity retention performance are higher than those of Comparative Example 3, they are significantly different from those of Example 1, affecting the improvement of the average internal resistance of the battery and the battery rate performance. Since there are defects of varying degrees of proportion inside the through-hole fillings of Comparative Examples 1 and 2 (micropores or micro-bridging defects, etc.), the bonding force between the polymer support layer and the conductive coating is affected to a certain extent. Therefore, although the related 1C cycle 1000 cycle capacity retention battery performance is higher than that of Comparative Example 3, it is still significantly different from that of Example 1, affecting the stability of the electrode sheet in the electrolyte and the improvement of the cycle life of the battery.

[0071] The following discusses the implementation of the integrally conductive composite current collector film of the present invention as a positive electrode current collector for batteries.

[0072] Example 2

[0073] (1) Preparation of integrally conductive positive electrode composite current collector film

[0074] This example was prepared as Figure 1The overall conductive composite current collector film of the structure shown includes a polymer support layer and a conductive coating. The polymer support layer has multiple through-holes filled with conductive coating material, connecting the conductive coatings on both sides. The overall conductive composite current collector film has a thickness of 2μm. The polymer support layer is made of PET flexible film. The specific preparation steps are as follows:

[0075] (1) Laser drilling is used to drill holes in the thickness direction of 1 μm thick PET with a porosity of 5%. The through holes have the following characteristics: Figure 2 The structure shown, the aperture parameters of each part of the through hole are shown in Table 3, and the laser wavelength is 240-260nm;

[0076] (2) CO gas is introduced into the through-hole to modify the surface of the inner wall of the through-hole, so that the inner wall of the through-hole has a step-wise hydrophobic property that gradually increases from the throat of the through-hole to the surface of the polymer support layer, and the inner wall of the through-hole near the throat has weak hydrophobicity;

[0077] (3) A metal aluminum coating layer with a thickness of 0.5 μm and a purity of more than 99.9% was deposited on the upper and lower surfaces of the perforated PET base film by vacuum evaporation to form a 2 μm thick overall conductive composite current collector film; during vacuum evaporation, the background vacuum degree of the coating chamber was 2×10 -2 Pa, evaporation temperature 1340 ° C, film speed 120m / min. Through cross-sectional microscopic examination of the through-hole filling, it was found that the coating material formed a dense and gapless filling of the through-hole, with a filling density of 99.8%.

[0078] (2) Electrode sheet preparation and battery assembly

[0079] The negative electrode current collector is a 6μm copper foil with graphite as the active material. The positive electrode current collector is a monolithically conductive composite current collector film prepared in this example with lithium cobalt oxide as the active material. The electrolyte is a carbonate solution containing 1M LiPF6. The separator is Celgard 2400. Tabs are welded to both the positive and negative current collectors on one side to form a 2000mAh soft-pack battery. Because the positive electrode current collector is a monolithically conductive composite current collector film, both the positive and negative current collectors can be welded to the tabs on one side, achieving a high yield of 99% in the tab welding process.

[0080] The battery assembled with the above-mentioned integrally conductive composite current collector film and the corresponding electrode sheets was tested, and the test results are shown in Table 4.

[0081] Comparative Example 4

[0082] Comparative Example 4 also uses Figure 1The composite current collector film of the structure shown includes a polymer support layer and a conductive coating. The polymer support layer has multiple through-holes distributed thereon, which are filled with a conductive coating material, connecting the conductive coatings on both sides. The thickness of the composite current collector film is 2 μm. The preparation steps of this composite current collector film are basically the same as those in Example 2, except that the surface modification of the inner wall of the through-hole makes it hydrophilic, rather than the stepped hydrophobicity in Example 2.

[0083] After vacuum evaporation deposited a metal aluminum layer with a thickness of 0.5μm and a purity of more than 99.9% on the upper and lower surfaces of the above-mentioned perforated PET, although the through-holes appeared to be well filled from the outside, cross-sectional microscopic inspection of the through-hole filling situation found that the coating material did not completely fill the interior of the through-holes. There was a certain proportion of imperceptible defects in the filling, such as micropores or micro-bridging defects, and the filling density was only 85.3%.

[0084] The composite current collector film was then used as the positive electrode current collector to prepare electrode sheets and assemble into a 2000 mAh soft pack battery, following the same steps as in Example 2. The battery assembled with the overall conductive composite current collector film and the corresponding electrode sheets was tested, and the test results are shown in Table 4.

[0085] Comparative Example 5

[0086] Comparative Example 5 also uses Figure 1 The composite current collector film of the structure shown includes a polymer support layer and a conductive coating. The polymer support layer has multiple through-holes distributed therein, which are filled with a conductive coating material, connecting the conductive coatings on both sides. The composite current collector film has a thickness of 2 μm. The preparation steps of this composite current collector film are essentially the same as those in Example 2, except that the inner walls of the through-holes are not subjected to specific hydrophobic or hydrophilic surface modification.

[0087] After vacuum evaporation deposited a metal aluminum coating with a thickness of 0.5 μm and a purity of more than 99.9% on the upper and lower surfaces of the above-mentioned perforated PET, although the through-holes appeared to be well filled from the outside, cross-sectional microscopic inspection of the through-hole filling situation revealed that the coating material did not completely fill the interior of the through-holes. There was a large proportion of defects in the filling, such as micropores or micro-bridging defects, and the filling density was only 64.8%.

[0088] The composite current collector film was then used as the positive electrode current collector to prepare electrode sheets and assemble into a 2000 mAh soft pack battery, following the same steps as in Example 2. The battery assembled with the overall conductive composite current collector film and the corresponding electrode sheets was tested, and the test results are shown in Table 4.

[0089] Comparative Example 6

[0090] (1) Preparation of positive electrode composite current collector film

[0091] The composite current collector film includes a polymer support layer and a conductive coating. The polymer support layer does not have a through-hole structure. The composite current collector film has a thickness of 2.6 μm. The polymer support layer is made of PET flexible film. The specific preparation steps are as follows:

[0092] A 0.8 μm thick aluminum layer with a purity of more than 99.9% was deposited on both the upper and lower surfaces of a 1 μm thick PET base film by vacuum evaporation to form a 2.6 μm thick composite current collector film. The background vacuum of the coating chamber was 2×10 -2 Pa, evaporation temperature 1340℃, film speed 120m / min.

[0093] (2) Electrode sheet preparation and battery assembly

[0094] The negative electrode current collector is a 6μm copper foil with graphite as the active material. The positive electrode current collector is a fully conductive composite current collector film prepared in this example with lithium cobalt oxide as the active material. The electrolyte is a carbonate solution containing 1M LiPF6. The separator is Celgard 2400, assembled into a 2000mAh soft-pack battery. The copper foil negative electrode current collector has tabs welded on one side. However, because the composite current collector film of the positive electrode current collector is not fully conductive, the tabs need to be welded on both sides. The yield of the tab welding process is only 94%.

[0095] The battery assembled with the composite current collector film and the corresponding electrode sheets was tested, and the test results are shown in Table 4.

[0096] Table 3. Comparison of characteristics of positive electrode composite current collector film examples and comparative examples

[0097]

[0098]

[0099] Table 4. Performance comparison of positive electrode composite current collector film and corresponding battery

[0100]

[0101] From the comparison of the data in Table 3 and Table 4, we can see that:

[0102] Because the conductive coating in the through-holes of the polymer support layer of Example 2 connects the conductive coatings on the upper and lower surfaces of the polymer support layer into one, the overall conductive composite current collector film of Example 2 expands the electron lateral transmission path compared to the composite current collector film of Comparative Example 6. In addition, the conductive coating material completely fills the through-holes, with a filling density of 99.8%. Therefore, although the thickness of the conductive coating in Example 2 is only 0.5 μm, which is approximately 63% of the thickness of the conductive coating in Comparative Example 6, the average conductivity of the composite current collector film is significantly higher than that of Comparative Example 6, reaching 3.39×10 7 S / m high conductivity (close to the theoretical conductivity of aluminum foil), the 4C / 0.5C capacity retention rate performance associated with the battery in Example 2 is also significantly better than that in Comparative Example 6, and the battery rate performance is significantly improved. Compared with Comparative Example 6, the thickness of the composite current collector film in Example 2 is reduced by about 25%, and the energy density of the battery is also improved. In the composite current collector film in Example 2, the conductive coating material filled in the through-holes tightly connects the polymer support layer and the conductive coatings on the upper and lower surfaces into a whole, which greatly improves the bonding force between the polymer support layer and the conductive coating, and the peel strength reaches 1143N / m (the bonding force between the aluminum coating and PET is better than that between the copper coating, so the peel strength of Example 2 is higher than that of Example 1), which is much higher than that of Comparative Example 6. Therefore, the 1C cycle 1000 cycle capacity retention rate performance associated with the battery in Example 2 is also much higher than that of Comparative Example 6, and the stability of the electrode sheet in the electrolyte and the cycle life of the battery are significantly improved.

[0103] Although the composite current collector films of Comparative Examples 4 and 5 also have through-holes filled with conductive materials, the inner walls of the through-holes do not have the stepped hydrophobicity of the embodiments, and the filling density is significantly reduced, affecting the connectivity between the upper and lower surface conductive coatings. Therefore, although their electrical conductivity and 4C / 0.5C capacity retention performance are higher than those of Comparative Example 6, they are significantly different from those of Example 2, affecting the improvement of the average internal resistance of the battery and the battery rate performance. Since there are defects of varying degrees of proportion inside the through-hole fillings of Comparative Examples 4 and 5 (micropores or micro-bridging defects, etc.), the bonding force between the polymer support layer and the conductive coating is affected to a certain extent. Therefore, although the related 1C cycle 1000 cycle capacity retention battery performance is higher than that of Comparative Example 6, it is still significantly different from that of Example 2, affecting the stability of the electrode sheet in the electrolyte and the improvement of the cycle life of the battery.

[0104] In this specification and claims, the terms "first," "second," "third," "fourth," "upper surface," and "lower surface" are used for convenience to distinguish similar objects and are not necessarily used to describe a specific order, sequence, or upper and lower position. It should be understood that the terms used in this manner are interchangeable under appropriate circumstances.

Claims

1. An integrally conductive composite current collector film, characterized in that: The composite current collector film comprises a polymer support layer and conductive coatings on both sides of the polymer support layer. The polymer support layer is provided with a plurality of through holes, and the porosity of the through holes is 1-10%. The through holes are filled with a conductive coating material, so that the conductive coatings on both sides are connected. The filling density of the conductive coating material in the through holes is above 99.8%. The thickness of the conductive coating is 0.1-0.5 μm. The composite current collector film has an electrical conductivity of 2×10 7 -5.7×10 7 S / m; when the composite current collector film is used, only one side of the electrode tab needs to be welded to conduct the active materials on and below the composite current collector film; The through hole includes a first surface with an opening located on the upper surface of the polymer support layer and a second surface with an opening located on the lower surface of the polymer support layer. The first surface is an inverted conical surface with a larger opening at the upper end and a smaller opening at the lower end. The second surface and the first surface are symmetrical with respect to a midplane in the thickness direction of the polymer support layer. The diameter of the largest opening of the first surface is less than 3 μm. The through hole further includes a third surface and a fourth surface that are symmetrical with respect to a mid-plane in the thickness direction of the polymer support layer. The third surface is an inverted conical surface that is connected end-to-end with the small opening of the first surface. The small openings of the third and fourth surfaces are connected to form a throat of the through hole. The throat of the through hole has an aperture of 0.5-1 μm. The cone angle between the first and second surfaces is within a range of 90-180°, and the cone angle between the third and fourth surfaces is within a range of 35-130°. The cone angles of the third and fourth surfaces are smaller than the cone angles of the first and second surfaces. The connecting point between the first surface and the third surface and the connecting point between the second surface and the fourth surface respectively has a knee portion protruding outward.

2. The integrally conductive composite current collector film according to claim 1, characterized in that: The pore depth a of the third surface and the thickness h of the polymer support layer satisfy the relationship 2a>0.5h.

3. The integrally conductive composite current collector film according to claim 1, characterized in that: The thickness of the composite current collector film is 0.7-2.5 μm, and the thickness of the polymer support layer is 0.5-1.5 μm.

4. The integrally conductive composite current collector film according to claim 1, wherein: Before being filled with the conductive plating material, the inner wall of the through hole has a step-wise hydrophobic property that gradually increases from the throat of the through hole to the surface of the polymer support layer, and the inner wall of the through hole near the throat has weak hydrophobicity.

5. The integrally conductive composite current collector film according to claim 1, characterized in that: The ratio b of oxygen element:carbon element on the inner wall of the through-hole is in the range of 10-35%, and the ratio b gradually decreases from the throat to the surface of the polymer support layer; the b value of the inner wall close to the surface of the polymer support layer is in the range of 10-20%, the b value of the inner wall of the throat is in the range of 25-35%, and the b value of the inner wall of the throat is 10-20% higher than the b value of the inner wall close to the surface of the polymer support layer.

6. The integrally conductive composite current collector film according to claim 1, characterized in that: The peel strength between the conductive coating and the polymer support layer is 650-1150 N / m.

7. The integrally conductive composite current collector film according to claim 1, characterized in that: The through holes are generated by laser drilling, and the laser wavelength used in laser drilling is 240-260nm.

8. The integrally conductive composite current collector film according to claim 1, characterized in that: The component of the polymer support layer is one selected from PET, PP, PI, PC and PVC; the component of the conductive coating layer is one or more selected from copper, aluminum, silver, nickel, molybdenum, titanium, niobium, iron, zinc, stainless steel, graphene, carbon nanotubes, Ketjen black, acetylene black, graphite powder and carbon fiber.

Images