Composite current collector, preparation method thereof, pole piece, battery and electric device

Abstract

This invention provides a composite current collector, its preparation method, an electrode, a battery, and an electrical device, relating to the field of energy storage battery technology. The composite current collector of this invention comprises an intermediate base film layer, a first metal layer, a variable rate functional layer, and a second metal layer. The first metal layer, the variable rate functional layer, and the second metal layer are sequentially stacked from the inside to the outside on at least one surface of the intermediate base film layer. The variable rate functional layer comprises a conductive variable polymer, a wave-damping material, and a high-temperature resistant polymer. The composite current collector of this invention intrinsically reduces the negative impacts of temperature rise, thereby ensuring that the failure of a single cell does not affect the overall battery function, allowing the composite current collector to be well-suited for energy storage battery applications.

Description

Technical Field

[0001] This invention relates to the technical field of energy storage batteries, and in particular to a composite current collector and its preparation method, electrode, battery and power device. Background Technology

[0002] Large-scale energy storage batteries are currently experiencing rapid development. The industry generally expects that the third generation of large-scale energy storage batteries will undergo key technological iterations, with cell capacities increasing to over 500 Ah to meet the application demands of large-scale, high-power energy storage scenarios. However, the core of whether large-scale energy storage batteries can achieve stable large-scale application and market promotion lies in the reliability and safety of the overall battery pack system performance, namely, achieving a highly fault-tolerant operating mechanism where the failure of a single cell does not affect the normal operation of the entire pack. This goal places extremely stringent requirements on the temperature rise control of individual cells, early failure prevention, thermal runaway suppression, and full life-cycle safety protection, and is also a key direction for technological breakthroughs in the next generation of large-scale energy storage batteries.

[0003] Currently, temperature rise control of individual battery cells remains a significant challenge in large-scale energy storage battery systems. Existing technologies generally lack accurate, real-time, and controllable temperature-rate dynamic response capabilities for individual cells. Furthermore, under high-rate charge-discharge, long-term cycling, and complex operating conditions, cell temperatures are prone to rapid rises and localized overheating. This not only restricts battery performance and lifespan degradation but also fails to meet the intrinsic requirement that individual cell failure does not affect the overall battery operation, becoming a key technological bottleneck hindering the large-scale, high-reliability application of large-scale energy storage batteries.

[0004] Large-capacity energy storage batteries require moderate charge / discharge rates. Within this range, composite current collectors exhibit excellent conductivity, heat dissipation, and structural stability, making them perfectly suited to the operating conditions and meeting the safety, reliability, and long cycle life requirements of large-capacity energy storage cells.

[0005] Furthermore, battery management systems (BMS) are limited by low sampling accuracy and external control levels, making it difficult to detect early anomalies within the cell and to identify, quickly isolate, and effectively intervene in microscopic thermal failures within individual cells. At the same time, existing battery structures and material systems generally lack accurate, real-time, and controllable closed-loop response and active regulation functions for the cell's temperature field, making it difficult to suppress localized thermal runaway at its source and failing to meet the requirements of high-safety energy storage applications.

[0006] Therefore, there is an urgent need in this field to develop a new type of composite current collector that can automatically adjust its response characteristics according to the real-time operating conditions of the battery cell, thereby improving temperature rise control and safety redundancy at the material level and providing more reliable underlying support for large-capacity energy storage batteries.

[0007] In view of this, the present invention is hereby proposed. Summary of the Invention

[0008] The purpose of this invention is to provide a composite current collector and its preparation method, electrode, battery, and power device. This invention aims to solve the problem in the prior art where the failure of a single cell affects the overall battery function. It also addresses technical problems such as the fixed rate performance of current composite current collectors, the inability to adaptively adjust temperature control, and poor adaptability to large-scale battery storage conditions.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a composite current collector, comprising: an intermediate base film layer, a first metal layer, a variable rate functional layer and a second metal layer, wherein the first metal layer, the variable rate functional layer and the second metal layer are sequentially stacked from the inside to the outside on at least one surface of the intermediate base film layer. The variable rate functional layer includes a conductive variable polymer, a wave-damping material, and a high-temperature resistant polymer.

[0010] Furthermore, the conductive variable polymer comprises a compound represented by Formula I:

[0011] Formula I; Wherein, R1 is selected from C4~C12 straight-chain or branched alkyl groups; n is an integer between 500 and 5000.

[0012] Furthermore, the conductive variable polymer includes any one or a combination of at least two of poly(3-hexylthiophene), poly(3-octylthiophene), poly(3-butylthiophene), and poly(3-dodecylthiophene).

[0013] Furthermore, the wave-damping material includes any one or a combination of at least two of boron nitride, silicon nitride, boron carbide, and silicon carbide, preferably hexagonal boron nitride.

[0014] Furthermore, the high-temperature resistant polymer includes any one or a combination of at least two of the following: naphthalene-biphenyl polyetherketone, polytetrafluoroethylene, polybenzimidazole, and polyetherimide.

[0015] Furthermore, the weight-average molecular weight of the high-temperature resistant polymer is 20,000 to 150,000 g / mol.

[0016] Furthermore, the thickness of the variable rate functional layer is 50~300 nm.

[0017] Furthermore, the mass ratio of the conductive variable polymer, the wave-damping material, and the high-temperature resistant polymer is (72~90):(2~8):(8~20).

[0018] Furthermore, the material of the intermediate base film layer includes any one or a combination of at least two of polyethylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, and polyimide.

[0019] Furthermore, the thickness of the intermediate base film layer is 2.0~8.0 μm.

[0020] Furthermore, the materials of the first metal layer and the second metal layer are each independently one or a combination of at least two of copper, copper alloy, aluminum, and aluminum alloy.

[0021] Furthermore, the thickness of the first metal layer is greater than the thickness of the second metal layer, and preferably the thickness of the first metal layer is 2.0 to 5.0 times the thickness of the second metal layer.

[0022] Furthermore, the thickness of the first metal layer is 0.5~1.2 μm; the thickness of the second metal layer is 0.15~0.40 μm.

[0023] In a second aspect, the present invention provides a method for preparing a composite current collector as described in the first aspect, comprising: A first metal layer is prepared on at least one surface of the intermediate base film layer; A variable magnification functional paste is coated on the surface of the first metal layer, and then dried and shaped to obtain the variable magnification functional layer; the variable magnification functional paste includes: a conductive variable polymer, a wave-damping material, and a high-temperature resistant polymer; A second metal layer is prepared on the surface of the variable rate functional layer to obtain the composite current collector.

[0024] Furthermore, the solid content of the variable-rate functional slurry is 2.5~10 wt%.

[0025] Furthermore, the coating is performed using a microgravure coating method; wherein the process parameters of the microgravure coating include: microgravure roller diameter of 30~60 mm; cell line count of 700~1000 LPI; cell depth of 3~8 μm; roller surface linear speed of 60~250 m / min; and substrate running speed of 80~300 m / min.

[0026] Furthermore, the drying temperature is 60~100℃; Furthermore, the shaping is carried out by heat shaping; wherein the process parameters of heat shaping include: speed of 2~5 m / min and heat shaping temperature of 100~140℃.

[0027] Thirdly, the present invention provides an electrode, the electrode comprising the composite current collector described in the first aspect and the composite current collector prepared by the preparation method described in the second aspect.

[0028] Fourthly, the present invention provides a battery comprising the electrode plates as described in the third aspect.

[0029] Fifthly, the present invention provides an electrical device comprising a battery as described in the fourth aspect.

[0030] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention optimizes the electrochemical performance of the current collector by introducing a variable rate functional layer composed of a conductive variable polymer, a wave-blocking material, and a high-temperature resistant polymer between the two metal layers of the composite current collector. The high-temperature resistant polymer C effectively reduces thermal damage to the ultra-thin base film caused by the high-temperature thermosetting process, improving overall stability and reliability. The wave-blocking material B influences the ultrasonic wave transmission path, controlling the welding depth and position, meaning it can only be welded to the second metal layer. The conductive variable polymer A achieves reversible resistance change based on temperature variations. That is, when the battery operating temperature is higher than the response temperature, the conductive variable polymer blocks electron transport. This ensures that electron transport can only occur in the second metal layer, reducing the charge / discharge rate and giving the battery adaptive dynamic rate control capability. The synergistic effect of the conductive variable polymer, wave-blocking material, and high-temperature resistant polymer enables the composite current collector to meet the long-term, safe, and efficient operation requirements of individual energy storage batteries.

[0031] (2) This invention achieves welding depth and position control by combining with a new welding process, avoiding weld penetration, incomplete welding and excessive diffusion of metal layer, so as to ensure the realization of the adaptive dynamic rate control capability of the current collector. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 A schematic diagram of the composite current collector provided by the present invention.

[0034] Among them, 1 is the intermediate base film layer, 2 is the first metal layer, 3 is the variable rate functional layer, and 4 is the second metal layer.

[0035] Figure 2 This is a welding diagram provided for the present invention.

[0036] Among them, 10 is a composite current collector, 20 is an adapter piece, 30 is an ultrasonic welding roller, 40 is a welding point, and 50 is a welding plate. Detailed Implementation

[0037] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In a first aspect, the present invention provides a composite current collector, comprising: an intermediate base film layer, a first metal layer, a variable rate functional layer and a second metal layer, wherein the first metal layer, the variable rate functional layer and the second metal layer are sequentially stacked from the inside to the outside on at least one surface of the intermediate base film layer. The variable rate functional layer includes a conductive variable polymer, a wave-damping material, and a high-temperature resistant polymer.

[0040] It should be noted that this invention physically separates the first metal layer and the second metal layer by designing a variable rate functional layer containing conductive variable polymer, wave-damping material and high-temperature resistant polymer. By using a new double-sided welding process, the variable rate functional layer remains conductive during normal operation, while the resistance of the variable rate functional layer increases rapidly during abnormal temperature rise, and the charge and discharge rate decreases directly. This reduces the negative impact of temperature rise from an intrinsic level, thereby ensuring that the failure of a single cell does not affect the overall battery function. This allows the composite current collector to be well matched for large energy storage battery application scenarios.

[0041] Specifically, the conductive variable polymer A is the core functional component, possessing a temperature threshold-triggered resistance mutation characteristic. When the threshold is exceeded, the resistance increases sharply, and after cooling, the resistance returns to its initial state. This is the core functional material for achieving adaptive dynamic rate control. It should be clarified that without the conductive variable polymer, the battery rate will fluctuate slightly, but this is mainly due to the inherent internal resistance temperature rise effect of the battery, resulting in a limited and uncontrollable decrease, fundamentally different from the adaptive mutation regulation of this invention. The wave-damping material B effectively hinders ultrasonic wave transmission, confining welding energy to the material surface. Simultaneously, the rigid particles form a physical barrier, blocking the diffusion of metal atoms in the welding process and controlling the welding depth and area. The high-temperature resistant polymer C improves the overall heat resistance of the functional layer, effectively resisting thermal damage to the base film during coating curing. The three components A, B, and C work synergistically to form a stable functional layer with welding control and variable rate functions, achieving comprehensive performance of temperature-sensitive dynamic rate regulation of the composite current collector.

[0042] As an optional implementation method, such as Figure 1 As shown, the composite current collector includes: an intermediate base film layer 1, on both sides of the intermediate base film layer, a first metal layer 2, a variable rate functional layer 3, and a second metal layer 4 are sequentially stacked from the inside to the outside.

[0043] As an optional implementation, the conductive variable polymer comprises a compound represented by Formula I:

[0044] Formula I; Wherein, R1 is selected from C4 to C12 (e.g., it can be C4, C5, C6, C7, C8, C9, C10, C11, C12) straight-chain or branched alkyl groups; n is an integer between 500 and 5000 (e.g., it can be 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, etc.).

[0045] It should be noted that the compound shown in Formula I of this invention is selected as a conductive variable polymer. The compound with this structure can flexibly adjust the temperature-sensitive response temperature by controlling the length of the alkyl side chain, thereby achieving reversible resistance change characteristics. At the same time, this type of material is adapted to changes in battery operating temperature and can stably achieve dynamic rate adaptive control.

[0046] As an optional implementation, the conductive variable polymer includes any one or a combination of at least two of poly(3-hexylthiophene) (P3HT), poly(3-octylthiophene) (P3OT), poly(3-butylthiophene) (P3BT), and poly(3-dodecylthiophene) (P3DDT).

[0047] It should be noted that this invention selects four alkyl-substituted thiophene polymers—P3BT, P3HT, P3OT, and P3DDT—as functional matrix materials. These four materials exhibit significant differences in the length of their molecular side chain carbon chains, and the temperature-sensitive variable response temperature of the materials shows a significant correlation with the length of the alkyl side chain, generally exhibiting the characteristic that the longer the side chain, the lower the temperature response threshold. Based on this characteristic, this invention can adjust the temperature response range of the functional layer by selecting thiophene polymers with different side chain lengths, adapting to the operating conditions and requirements of various energy storage batteries.

[0048] As an optional implementation, the wave-damping material includes any one or a combination of at least two of boron nitride (BN), silicon nitride (Si3N4), boron carbide (B4C), and silicon carbide (SiC).

[0049] In a preferred embodiment, the wave-damping material is hexagonal boron nitride (h-BN).

[0050] As an optional implementation, the high-temperature resistant polymer includes any one or a combination of at least two of the following: poly(naphthyl biphenyl) ketone (PPEK), polytetrafluoroethylene (PTFE), polybenzimidazole (PBI), and polyetherimide (PEI).

[0051] As an optional embodiment, the weight-average molecular weight of the high-temperature resistant polymer is 20,000 to 150,000 g / mol, for example, it can be 20,000 g / mol, 30,000 g / mol, 40,000 g / mol, 50,000 g / mol, 60,000 g / mol, 70,000 g / mol, 80,000 g / mol, 90,000 g / mol, 100,000 g / mol, 110,000 g / mol, 120,000 g / mol, 130,000 g / mol, 140,000 g / mol, 150,000 g / mol, etc.

[0052] As an optional implementation, the thickness of the variable rate functional layer is 50~300 nm, for example, it can be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, etc.

[0053] As an optional implementation, the mass ratio of the conductive variable polymer, the wave-damping material, and the high-temperature resistant polymer is (72~90):(2~8):(8~20); Among them, "72~90" can be, for example, 72, 75, 78, 80, 82, 85, 88, 90, etc.; Among them, "2~8" can be, for example, 2, 3, 4, 5, 6, 7, 8, etc.; Among them, "8~20" can be, for example, 8, 9, 10, 12, 14, 15, 16, 18, 20, etc.

[0054] As an optional implementation, the material of the intermediate base film layer includes any one or a combination of at least two of polyethylene terephthalate (PET), polyethylene terephthalate (PEN), polyphenylene sulfide (PPS), and polyimide (PI).

[0055] As an optional implementation, the thickness of the intermediate base film layer is 2.0~8.0 μm, for example, it can be 2.0 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3.0 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, 4.0 μm, 4.2 μm, 4.4 μm, 4.6 μm, 4.8 μm, 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, etc.

[0056] As an optional implementation, the materials of the first metal layer and the second metal layer are each independently any one or a combination of at least two of copper, copper alloy, aluminum, and aluminum alloy.

[0057] As an optional implementation, the thickness of the first metal layer is greater than the thickness of the second metal layer.

[0058] In a preferred embodiment, the thickness of the first metal layer is 2.0 to 5.0 times the thickness of the second metal layer, for example, it can be 2.0 times, 2.2 times, 2.4 times, 2.6 times, 2.8 times, 3.0 times, 3.2 times, 3.4 times, 3.6 times, 3.8 times, 4.0 times, 4.2 times, 4.4 times, 4.6 times, 4.8 times, 5.0 times, etc.

[0059] It should be noted that the reason for setting the thickness of the first metal layer to be greater than that of the second metal layer in this invention is that the outer second metal layer has better conductivity, making it suitable for surface welding operations. The inner first metal layer is thicker, which can withstand the conventional high current conduction requirements. At the same time, the advantage of preferably having a thickness of 2.0 to 5.0 times that of the second metal layer is that the difference in thickness ratio between the two, combined with the synergistic effect of the temperature-sensitive functional layer, allows the battery to automatically reduce the charge and discharge rate when the battery abnormally heats up, achieving adaptive switching of the rate from 5C to 1C, effectively controlling heat generation, and ensuring the safe operation of the battery cell.

[0060] As an optional implementation, the thickness of the first metal layer is 0.5~1.2 μm, for example, it can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, etc.

[0061] As an optional implementation, the thickness of the second metal layer is 0.15~0.40 μm, for example, it can be 0.15 μm, 0.20 μm, 0.25 μm, 0.30 μm, 0.35 μm, 0.40 μm, etc.

[0062] In a second aspect, the present invention provides a method for preparing a composite current collector as described in the first aspect, the method comprising: A first metal layer is prepared on at least one surface of the intermediate base film layer; A variable magnification functional paste is coated on the surface of the first metal layer, and then dried and shaped to obtain the variable magnification functional layer; the variable magnification functional paste includes: a conductive variable polymer, a wave-damping material, and a high-temperature resistant polymer; A second metal layer is prepared on the surface of the variable rate functional layer to obtain the composite current collector.

[0063] As an optional implementation, the process for preparing the first metal layer and the second metal layer is selected from vapor deposition and / or sputtering.

[0064] As an optional implementation method, vapor deposition: a roll-to-roll double-sided evaporation coating equipment is used, employing high-purity aluminum wire (99.90% purity) as the evaporation source. The equipment has a total of 72 evaporation boats, with 36 boats corresponding to each side of the base film. The working vacuum degree is 1.0 × 10⁻⁶. -3 Pa, wire feeding speed 500 mm / min, evaporation power 90%, until the target thickness is achieved.

[0065] As an optional implementation method, sputtering is employed: a roll-to-roll double-sided magnetron sputtering device is used, with a high-purity aluminum target (99.99% purity) as the sputtering target material. The device is equipped with a total of 20 sets of targets, with 10 sets corresponding to each side of the base film. The working vacuum degree is 0.3 Pa, and the target power is 20 kW, until the magnetron sputtering reaches the target thickness.

[0066] It should be noted that the thickness of the vapor-deposited metal layer can be controlled by adjusting the evaporation time and using a crystal oscillator thickness gauge to monitor the deposition amount in real time, matching the deposition time to the target thickness. And / or, the thickness of the sputtered metal layer can be controlled by setting the sputtering time.

[0067] As an optional implementation, the solid content of the variable-ratio functional slurry is 2.5~10 wt%, for example, it can be 2.5 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, etc.

[0068] As an optional implementation, the variable-rate functional slurry also includes an organic solvent.

[0069] As an optional implementation, the organic solvent includes toluene and / or chlorobenzene.

[0070] As an optional implementation, the method for preparing the variable-ratio functional slurry includes: A conductive variable polymer (or a solution containing a conductive variable polymer), a wave-damping material, and a high-temperature resistant polymer are mixed, a solvent is added to adjust the solid content, and a dispersion treatment is performed to obtain the variable rate functional slurry.

[0071] As an optional implementation, the dispersion process includes ultrasonic dispersion and / or mechanical stirring.

[0072] In a preferred embodiment, the dispersion process includes sequential ultrasonic dispersion and mechanical stirring.

[0073] As an optional implementation, the frequency of the single ultrasonic dispersion is 5~30 kHz, for example, 5 kHz, 6 kHz, 8 kHz, 10 kHz, 12 kHz, 14 kHz, 15 kHz, 16 kHz, 18 kHz, 20 kHz, 22 kHz, 24 kHz, 25 kHz, 26 kHz, 28 kHz, 30 kHz, etc., and the power is 100~300 W, for example, 100 W, 120 W, 140 W, 150 W, 160 W, 180 W, 200 W, 220 W, 240 W, 250 W, 260 W, 280 W, 300 W, etc., and the duration of the single ultrasonic dispersion is 0.2~2 h, for example, 0.2 h, 0.4 h, 0.6 h, 0.8 h, 1.0 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2.0 h, etc.

[0074] As an optional implementation, the rotation speed of the mechanical stirring in a single cycle is 200~1000 rpm, for example, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, etc., and the duration of the mechanical stirring in a single cycle is 0.5~2 h, for example, 0.5 h, 0.6 h, 0.8 h, 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, etc.

[0075] As an optional implementation, the dispersion process is repeated at least twice, for example, twice, three times, four times, five times, etc.

[0076] As an optional implementation, the method for preparing the conductive variable polymer includes: Under an inert atmosphere, thiophene monomers with C4-C12 straight-chain or branched alkyl substituted structures are mixed with a catalyst in a polymerization solvent to carry out a polymerization reaction; after precipitation, washing, and drying, the conductive variable polymer is obtained.

[0077] As an optional implementation, the method for preparing the solution containing the conductive variable polymer includes: The conductive variable polymer is dissolved in an organic solvent to prepare a solution containing the conductive variable polymer.

[0078] As an optional implementation, the inert atmosphere includes Ar or N2.

[0079] As an optional implementation, the thiophene monomer has the following structural formula A:

[0080] Formula A; R1 is selected from C4 to C12 (e.g., C4, C5, C6, C7, C8, C9, C10, C11, C12) straight-chain or branched alkyl groups.

[0081] As an optional implementation, the catalyst is ferric chloride.

[0082] As an optional implementation, the molar ratio of the thiophene monomer to the catalyst is 1:(2~2.5), for example, it can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, etc.

[0083] As an optional implementation, the polymerization reaction time is 2 to 6 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, etc.

[0084] As an optional implementation, the concentration of the solution containing the conductive variable polymer is 2 to 20 mg / mL, for example, it can be 2 mg / mL, 4 mg / mL, 6 mg / mL, 8 mg / mL, 10 mg / mL, 12 mg / mL, 14 mg / mL, 16 mg / mL, 18 mg / mL, 20 mg / mL, etc.

[0085] As an optional implementation, the response temperature of the solution containing the conductive variable polymer is 45~75℃, for example, it can be 45℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 120℃, etc.

[0086] As an optional implementation, the method for preparing the hexagonal boron nitride includes: Boron source, nitrogen source and molten salt medium are mixed and ground to obtain mixed powder; the mixed powder is heat-treated, washed and dried to obtain hexagonal boron nitride.

[0087] As an optional implementation, the boron source is boric acid.

[0088] As an optional implementation, the nitrogen source is melamine.

[0089] As an optional implementation, the molten salt medium is potassium chloride and / or sodium chloride.

[0090] As an optional implementation, the molar ratio of nitrogen to boron in the boron source and nitrogen source is 1:2.

[0091] As an optional implementation, the mass ratio of the molten salt medium to the total mass of the boron source and nitrogen source is (1~3):1, for example, it can be 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, etc.

[0092] As an optional implementation, the heating rate of the heat treatment is 3~8℃ / min, for example, it can be 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, etc.

[0093] As an optional implementation, the heat treatment temperature is 950~1050℃, for example, it can be 950℃, 960℃, 970℃, 980℃, 990℃, 1000℃, 1010℃, 1020℃, 1030℃, 1040℃, 1050℃, etc.; the heat treatment time is 8~12 h, for example, it can be 8 h, 8.2 h, 8.4 h, 8.6 h, 8.8 h, 9 h, 9.2 h, 9.4 h, 9.6 h, 9.8 h, 10 h, 10.2 h, 10.4 h, 10.6 h, 10.8 h, 11 h, 11.2 h, 11.4 h, 11.6 h, 11.8 h, 12 h, etc.

[0094] As an optional implementation, the preparation method of the naphthalene-biphenyl polyether ketone includes the following steps: 4-(4-hydroxyphenyl)-2,3-diazanaphthol-1-one, 4,4'-dichlorobenzophenone, and a catalyst were added to a reactor. Then, a solvent was added to the reactor. Under an inert atmosphere, the mixture was first dehydrated until no water was precipitated, and then toluene was distilled off. The system was then heated to carry out the polymerization reaction. When the intrinsic viscosity of the polymer reached 0.5~0.8 dL / g, the reaction was stopped. Finally, the mixture was filtered, washed, and dried to obtain PPEK powder.

[0095] As an optional implementation, the inert atmosphere includes Ar or N2.

[0096] As an optional implementation, the reaction raw material liquid comprises, by mass percentage, 10-20% of 4-(4-hydroxyphenyl)-2,3-diazanaphth-1-one, 15-25% of 4,4'-dichlorobenzophenone, 1-10% of catalyst, and the remainder is reaction solvent.

[0097] As an optional implementation, the catalyst comprises anhydrous potassium carbonate.

[0098] As an optional implementation, the temperature of the dehydration treatment is 150~170℃, and the time of the dehydration treatment is 2~4 h.

[0099] As an optional implementation, the polymerization reaction temperature is 190~210℃, and the polymerization reaction time is 5~7 h.

[0100] As an optional implementation, the coating is performed using a microgravure coating method.

[0101] As an optional implementation, the process parameters for the microgravure coating include: a microgravure roller diameter of 30-60 mm, such as 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, etc.; a cell count of 700-1000 LPI, such as 700 LPI, 750 LPI, 800 LPI, 850 LPI, 900 LPI, 950 LPI, 1000 LPI, etc.; a cell depth of 3-8 μm, such as 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, etc.; and a roller surface linear speed of 60-250 m / min, such as 60 m / min, 80 m / min, 100 m / min, 120 m / min, 140 m / min, 160 m / min, etc. The operating speeds are 180 m / min, 200 m / min, 220 m / min, 240 m / min, 250 m / min, etc.; the substrate operating speed is 80~300 m / min, for example, it can be 80 m / min, 100 m / min, 120 m / min, 140 m / min, 160 m / min, 180 m / min, 200 m / min, 220 m / min, 240 m / min, 260 m / min, 280 m / min, 300 m / min, etc.

[0102] As an optional implementation, the drying temperature is 60~100℃, for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, etc.

[0103] As an optional implementation, the length of the drying zone is 50~70 m, for example, it can be 50 m, 52 m, 54 m, 56 m, 58 m, 60 m, 62 m, 64 m, 66 m, 68 m, 70 m, etc.

[0104] As an optional implementation, the drying time is 10~30 s, for example, it can be 10 s, 12 s, 14 s, 16 s, 18 s, 20 s, 22 s, 24 s, 26 s, 28 s, 30 s, etc.

[0105] As an optional implementation, the shaping is carried out by heat shaping.

[0106] As an optional implementation, the heat setting process parameters include: a speed of 2~5 m / min, such as 2 m / min, 2.5 m / min, 3 m / min, 3.5 m / min, 4 m / min, 4.5 m / min, 5 m / min, etc.; and a heat setting temperature of 100~140℃, such as 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, etc.

[0107] As an optional implementation, the length of the heat-setting oven is 10~30 m, for example, it can be 10 m, 12 m, 14 m, 16 m, 18 m, 20 m, 22 m, 24 m, 26 m, 28 m, 30 m, etc.

[0108] As an optional implementation, the preparation method further includes the following steps: Welding tabs are welded in the welding area of ​​the second metal layer of the composite current collector, which has adaptive dynamic ratio control capability.

[0109] As an optional implementation method, such as Figure 2 As shown, the welding process employs a double ultrasonic roll welding technique.

[0110] It should be noted that in the welding process, a double ultrasonic roll welding process is used to weld it to the second metal layer. This allows the variable rate functional layer to cut off the current when the internal temperature of the battery rises, thus reducing the operating rate.

[0111] As an optional implementation, the structural design of the ultrasonic welding roller and the welding plate presents weld point shapes including triangles, circles, and squares.

[0112] This includes composite current collectors as described in the first aspect and composite current collectors prepared by the preparation method described in the second aspect.

[0113] Fourthly, the present invention provides a battery comprising the electrode plates as described in the third aspect.

[0114] Fifthly, the present invention provides an electrical device comprising a battery as described in the fourth aspect.

[0115] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0116] Example 1 This embodiment provides a composite current collector and its preparation method, the preparation method comprising: S1. Preparation of variable-ratio functional layer coating slurry: Preparation of S1-1, Poly(3-hexylthiophene) (P3HT) solution: Under an inert atmosphere (Ar), using anhydrous chloroform as the polymerization solvent, 3-hexylthiophene monomer (purity ≥99%, 3HT monomer concentration controlled at 0.08 M) was mixed with anhydrous ferric chloride (monomer:FeCl3 molar ratio = 1:2.2) and reacted at room temperature for 4 h. After precipitation with methanol, washing, and drying, poly(3-hexylthiophene) [weight average molecular weight 25000 g / mol] was obtained. The obtained poly(3-hexylthiophene) was dissolved in toluene or chlorobenzene to prepare a poly(3-hexylthiophene) solution, and the Fe element needed to be completely removed.

[0117] S1-2, Preparation of the material hexagonal boron nitride (h-BN): Potassium chloride (98.0% by mass) and sodium chloride (95.5% by mass) were mixed at a mass ratio of 2:1 at room temperature and heated to 700°C in a muffle furnace to form a homogeneous liquid. The mixture was then allowed to cool naturally to room temperature to obtain a KCl-NaCl low-temperature molten salt. Boric acid and melamine were used as raw materials (the molar ratio of nitrogen to boron was 1:2), and KCl-NaCl low-temperature molten salt was used. The molten salt and reactant mass ratio was 2:1. After mixing and grinding, the mixture was heated to 1000℃ at 5℃ / min and held for 10h under an inert atmosphere (N2). After cooling with the furnace, the mixture was washed with water and dried to obtain h-BN nanosheets (product particle size 50 nm).

[0118] S1-3, Preparation of polyetherketone naphthalene biphenyl (PPEK): Bisphenol monomer 4-(4-hydroxyphenyl)-2,3-diazanaphth-1-one (DHPZ) (15% by mass), dihaloaromatic ketone monomer 4,4'-dichlorobenzophenone (DCK) (20% by mass), and anhydrous potassium carbonate (K2CO3) catalyst (7% by mass) were added to a reactor. Then, sulfolane solvent (53% by mass) and toluene dehydrating agent (5% by mass) were added to the reactor. Under a nitrogen atmosphere, the mixture was first heated to 160°C for dehydration treatment for 3 hours. After anhydrous precipitation, toluene was distilled off, and the system was then heated to 200°C for 6 hours. The reaction was stopped when the intrinsic viscosity of the polymer reached 0.5-0.8 dL / g. Finally, the mixture was filtered, washed with methanol, and vacuum dried at 100°C for 12 hours to obtain a white to light yellow PPEK powder.

[0119] S1-4, Preparation of slurry: Material B (h-BN nanosheets, 50 nm) and material C (PPEK pure resin powder) were mixed in NMP solvent and ultrasonically dispersed at 200 W and 20 kHz for 1 h. The dispersed suspension was then added to material A (P3HT solution), and NMP was added to adjust the solid content to 5 wt%. The dry weight ratio of materials A, B, and C was 80:5:15. Subsequently, polyvinylpyrrolidone (PVP) was added as a dispersant, with the amount of PVP added being 5% of the mass of the PPEK pure resin powder. The mixture was mechanically stirred at 500 rpm for 0.5 h, and the ultrasonic-stirring cycle was repeated 4 times to obtain a uniformly dispersed variable-ratio functional layer coating slurry.

[0120] S2. Preparation of composite current collectors for large energy storage batteries with adaptive dynamic rate control: S2-1, Preparation of the first metal layer: A first aluminum layer of 0.75 μm is formed on both sides of the intermediate base film layer by vapor deposition; The intermediate base film layer is a PET film, and the thickness of the intermediate base film layer is 6 μm.

[0121] S2-2, Preparation of the variable rate functional layer: First, the variable magnification functional layer coating slurry is coated on the surface of the first metal aluminum layer formed on both sides of the base film using a micro-gravure coating process to form a wet film. The process parameters for the microgravure coating are as follows:

[0122] Subsequently, preliminary drying is carried out. Drying is performed concurrently with coating at the same speed. The drying temperature is gradually increased from 60℃ to 100℃, with a drying zone length of 60 m (drying time of 20 s). The drying temperature is controlled using a three-stage gradient: the first stage is 24 m long, with a temperature of 60℃ and a residence time of 8 s; the second stage is 21 m long, with a temperature of 80℃ and a residence time of 7 s; and the third stage is 15 m long, with a temperature of 100℃ and a residence time of 5 s.

[0123] Finally, a heat setting process was performed to obtain a 150 nm variable rate functional layer; the heat setting speed was 2 m / min, the heat setting temperature was 120℃, and the length of the heat setting oven was 20 m.

[0124] S2-3, Preparation of the second metal layer: A second aluminum layer of 0.25 μm is formed on the surface of the variable rate functional layer formed on both sides by vapor deposition; The process includes vapor deposition, employing a roll-to-roll double-sided evaporation coating system. High-purity aluminum wire (99.90% purity) is used as the evaporation source. The system comprises 72 evaporation boats, with 36 boats on each side of the base film. The working vacuum level is 1.0 × 10⁻⁶. -3 Pa, wire feeding speed 500mm / min, evaporation power 90%, until the target thickness is achieved.

[0125] S3, Dual ultrasonic roll welding process: Welding sheet is applied to the area to be welded on both sides of the second metal layer of the composite current collector obtained in S2 using a dual ultrasonic roll welding system. The welding sheet is a copper foil with a thickness of 8 μm; The parameters of the dual ultrasonic roll welding process include: welding power of 10W, working air pressure of 2 bar, welding frequency of 20kHz, welding amplitude of 20%, total welding time of 10s, and winding speed of 1m / min.

[0126] Example 2 The only difference from Example 1 is that 3-hexylthiophene is replaced with 3-octylthiophene monomer to prepare poly(3-octylthiophene) [weight average molecular weight of 50,000 g / mol]. The other steps are the same as in Example 1.

[0127] Example 3 The only difference from Example 1 is that 3-hexylthiophene is replaced with 3-dodecylthiophene monomer to prepare poly(3-dodecylthiophene) [weight average molecular weight of 30,000 g / mol]. The other steps are the same as in Example 1.

[0128] Example 4 The only difference from Example 1 is that hexagonal boron nitride is replaced with an equal mass of silicon carbide powder; the other steps are the same as in Example 1.

[0129] Example 5 The only difference from Example 1 is that the naphthalene-biphenyl polyetherketone is replaced with an equal mass of polytetrafluoroethylene; the other steps are the same as in Example 1.

[0130] Example 6 The only difference from Example 1 is that the mass ratio of P3HT, h-BN and PPEK is 72:8:20, and the other steps are the same as in Example 1.

[0131] Example 7 The only difference from Example 1 is that the mass ratio of P3HT, h-BN and PPEK is 90:2:8, and the other steps are the same as in Example 1.

[0132] Example 8 The only difference from Example 1 is that the thickness of the variable rate functional layer is 50 nm, while the other steps are the same as in Example 1.

[0133] Example 9 The only difference from Example 1 is that the thickness of the variable rate functional layer is 300 nm, while the other steps are the same as in Example 1.

[0134] Example 10 The only difference from Example 1 is that the thickness of the first metal layer is 0.5 μm and the thickness of the second metal layer is 0.15 μm. The other steps are the same as in Example 1.

[0135] Example 11 The only difference from Example 1 is that the thickness of the first metal layer is 1.2 μm and the thickness of the second metal layer is 0.40 μm. The other steps are the same as in Example 1.

[0136] Example 12 The only difference from Example 1 is that the thickness of the first metal layer is 0.5 μm and the thickness of the second metal layer is 0.4 μm. The other steps are the same as in Example 1.

[0137] Example 13 The only difference from Example 1 is that the thickness of the first metal layer is 1.2 μm and the thickness of the second metal layer is 0.15 μm. The other steps are the same as in Example 1.

[0138] Comparative Example 1 The only difference from Example 1 is that the variable magnification function layer is not set; the other steps are the same as in Example 1.

[0139] Comparative Example 2 The only difference from Example 1 is that poly(3-hexylthiophene) is no longer added to the variable rate functional layer coating slurry; however, the thickness of the variable rate functional layer is the same as in Example 1, and the other steps are the same as in Example 1.

[0140] Comparative Example 3 The only difference from Example 1 is that hexagonal boron nitride is no longer added to the variable rate functional layer coating slurry; however, the thickness of the variable rate functional layer is the same as in Example 1, and the other steps are the same as in Example 1.

[0141] Comparative Example 4 The only difference from Example 1 is that no naphthalene-biphenyl polyetherketone is added to the variable-rate functional layer coating slurry; however, the thickness of the variable-rate functional layer is the same as in Example 1, and the other steps are the same as in Example 1.

[0142] Comparative Example 5 The only difference from Example 1 is that the first metal layer is not provided, and the variable magnification functional layer is directly provided on both sides of the intermediate base film layer. The other steps are the same as in Example 1.

[0143] Comparative Example 6 The only difference from Example 1 is that a second metal layer is not provided; the other steps are the same as in Example 1.

[0144] Test Example 1 Test samples: Composite current collectors after roll welding provided in Examples 1-13, Composite current collectors after roll welding provided in Comparative Examples 1-6, and batteries assembled from the composite current collectors obtained in the above examples and comparative examples.

[0145] The preparation method for assembling a 50Ah battery includes the following steps: Preparation of the positive electrode: Adding the positive electrode active material LiNi to N-methylpyrrolidone. 0.6 Mn 0.2 Co 0.2O2 (NCM622), conductive carbon black, and binder are mixed evenly and then coated onto the surface of the composite current collector aluminum foil obtained in the above examples and comparative examples. After drying, the foil is cut to obtain the positive electrode sheet. The negative electrode sheet is prepared by adding artificial graphite, conductive carbon black, thickener, and binder to N-methylpyrrolidone, mixing evenly, coating onto a conventional copper foil, drying, and cutting to obtain the negative electrode sheet. The separator is a zirconia-coated polypropylene film (20 μm thick). The electrolyte is a 1 mol / L lithium hexafluorophosphate carbonate solution (where EMC:EC:PC = 1:1:1). The positive electrode sheet, separator, and negative electrode sheet are stacked in a Z-shape, placed in a shell, injected with electrolyte, and sealed to obtain a stacked battery. The battery is placed for 24 h before testing to ensure that the electrode materials are fully wetted by the electrolyte.

[0146] Test method: (1) Welding (roll welding) condition of composite current collector a. Welding depth: The depth to which pure copper foil is embedded in the composite current collector, as determined by X-ray inspection; b. Residue after peeling: The percentage (%) of metal residue in the cells at the metal-embedded solder joints where conventional current collector foil is transferred to the composite current collector after peeling, observed using an optical microscope. Any cell lacking even a trace of conventional foil metal is considered an NG (Not Good). The percentage is calculated as 1 - (NG number / total number of cells). A higher residue rate after peeling is better. c. Weld peel force: Cut the metal foil strip of the ultrasonically rolled electrode sheet into a standard strip 3 mm wide, with the weld teeth centered and the concave side facing upward. Using an electronic peel tester, clamp the top metal foil at a peel angle of 180° and a speed of 300 mm / min, and peel it off from the electrode sheet. Record the average peel force (N) at the weld point.

[0147] (2) Battery internal resistance test: The internal resistance of the battery after 500 charge-discharge cycles was tested using an AC impedance meter.

[0148] (3) Battery temperature rise test and rate performance: The battery was placed in a constant temperature chamber slightly below the response temperature and cycled 200 times in a 5C charge-discharge mode (with a charging cutoff voltage of 4.2V and a discharging cutoff voltage of 3.0V) until the battery temperature reached above the response temperature. The actual rate of change before and after the response was recorded.

[0149] The specific test results are shown in Table 1, where " / " in the test results indicates that the data does not exist: Table 1

[0150] As shown in Table 1, this invention endows the composite current collector with adaptive dynamic rate control capability by setting an adjustable temperature-sensitive variable rate functional layer (i.e., variable rate functional layer). The wave-damping material in the functional layer affects the ultrasonic wave transmission path, controlling the welding depth and position. Combined with the novel double-sided ultrasonic roll welding process, the welding only acts on the surface second metal layer. X-ray inspection shows that the welding depth of this invention is uniform and controllable, the welding strength is excellent, and the peeling residue is neat. The above welding effect ensures that the conductive variable polymer blocks electron transmission to the first metal layer above the response temperature, ultimately achieving a reduction in charge and discharge rate under abnormal conditions. The battery prepared by the composite current collector in this invention can effectively adaptively control the temperature rise, thereby avoiding the problem of single-cell thermal failure and ensuring the overall working stability and safety of the large energy storage battery.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite current collector, characterized in that, include: The intermediate base film layer, the first metal layer, the variable magnification functional layer and the second metal layer are sequentially stacked from the inside to the outside on at least one surface of the intermediate base film layer. The variable rate functional layer includes a conductive variable polymer, a wave-damping material, and a high-temperature resistant polymer.

2. The composite current collector according to claim 1, characterized in that, The conductive variable polymer comprises compounds represented by Formula I: Formula I; Wherein, R1 is selected from C4~C12 straight-chain or branched alkyl groups; n is an integer between 500 and 5000; Preferably, the conductive variable polymer includes any one or a combination of at least two of poly(3-hexylthiophene), poly(3-octylthiophene), poly(3-butylthiophene), and poly(3-dodecylthiophene).

3. The composite current collector according to claim 1, characterized in that, The wave-damping material includes any one or a combination of at least two of boron nitride, silicon nitride, boron carbide, and silicon carbide, preferably hexagonal boron nitride.

4. The composite current collector according to claim 1, characterized in that, The high-temperature resistant polymer includes any one or a combination of at least two of the following: naphthalenebiphenyl polyetherketone, polytetrafluoroethylene, polybenzimidazole, and polyetherimide. Preferably, the weight-average molecular weight of the high-temperature resistant polymer is 20,000 to 150,000 g / mol.

5. The composite current collector according to claim 1, characterized in that, The thickness of the variable rate functional layer is 50~300 nm; Preferably, the mass ratio of the conductive variable polymer, the wave-damping material, and the high-temperature resistant polymer is (72~90):(2~8):(8~20).

6. The composite current collector according to claim 1, characterized in that, The material of the intermediate base film layer includes any one or a combination of at least two of polyethylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, and polyimide; Preferably, the thickness of the intermediate base film layer is 2.0~8.0 μm; Preferably, the materials of the first metal layer and the second metal layer are each independently one or a combination of at least two of copper, copper alloy, aluminum, and aluminum alloy; Preferably, the thickness of the first metal layer is greater than the thickness of the second metal layer, and more preferably, the thickness of the first metal layer is 2.0 to 5.0 times the thickness of the second metal layer; Preferably, the thickness of the first metal layer is 0.5~1.2 μm; and the thickness of the second metal layer is 0.15~0.40 μm.

7. A method for preparing a composite current collector according to any one of claims 1 to 6, characterized in that, include: A first metal layer is prepared on at least one surface of the intermediate base film layer; A variable-rate functional paste is coated on the surface of the first metal layer, and then dried and shaped to obtain the variable-rate functional layer. The variable-rate functional paste includes: a conductive variable polymer, a wave-damping material, and a high-temperature resistant polymer; A second metal layer is prepared on the surface of the variable rate functional layer to obtain the composite current collector.

8. The method for preparing the composite current collector according to claim 7, characterized in that, The solid content of the variable-rate functional slurry is 2.5~10 wt%; Preferably, the coating is performed using a microgravure coating method; wherein the process parameters of the microgravure coating include: microgravure roller diameter of 30~60 mm; cell line count of 700~1000 LPI; cell depth of 3~8 μm; roller surface linear speed of 60~250 m / min; and substrate running speed of 80~300 m / min. Preferably, the drying temperature is 60~100℃; Preferably, the shaping is carried out by heat shaping; wherein the process parameters of heat shaping include: speed of 2~5 m / min and heat shaping temperature of 100~140℃.

9. An electrode sheet, characterized in that, The electrode comprises the composite current collector according to any one of claims 1 to 6 and the composite current collector prepared by the preparation method according to any one of claims 7 to 8.

10. A battery, characterized in that, The battery includes the electrode as described in claim 9.

11. An electrical appliance, characterized in that, The electrical device includes the battery as described in claim 10.

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