Functional aluminum current collector with high tensile strength and preparation process thereof

Abstract

The invention relates to the technical field of batteries, in particular to a functional aluminum current collector with high tensile strength and a preparation process thereof. The nano ceramic particles are prepared by taking nano aluminum oxide particles, nano magnesium oxide particles and nano silicon dioxide particles as raw materials. Taking the organic silicon modified polyester resin, diethylene glycol, acetaldehyde and flame-retardant nano ceramic particles as raw materials to obtain a current collector base film; and fixing the base film of the current collector, and obtaining the functional aluminum current collector by winding, unwinding, penetrating the film, adjusting tension and evaporating metal aluminum. The current collector prepared by the invention has good high cycle performance, flame retardance and wear resistance, so that the current collector has a wide application prospect in the technical field of batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and specifically to a functional aluminum current collector with high tensile strength and a preparation process thereof. Background Art

[0002] A current collector is a material composed of a three-layer structure of metal-polymer material-metal. It uses polymer materials such as PET / PP as the intermediate base film, and stacks double-layer copper / aluminum conductive layers on both the upper and lower surfaces. Compared with traditional current collectors, the new functional current collector has the advantages of cost reduction and safety. The thinning of traditional current collectors faces bottlenecks. The new functional current collector adopts a structure of "polymer substrate + thin and light conductive layer", which can effectively prevent battery thermal runaway, reduce the metal usage, achieve cost reduction and weight reduction, and thus improve the battery energy density. At the same time, the new functional current collector can also effectively avoid the problem of battery thermal runaway because the burrs generated when it is punctured are small, and because the polymer material layer will have an open circuit effect, the short-circuit current can be controlled not to increase, thereby effectively controlling battery thermal runaway and even explosion and fire. The new functional current collector material is the next-generation current collector material: due to the limitations of traditional current collectors, it has promoted the development of the current collector material industry, and the current collector is the most alternative new current collector material at present. The new functional current collector material is beneficial to reducing the risk of internal short circuit in lithium batteries. The new functional current collector material can also effectively absorb deformation stress and reduce the burrs generated by collision. At the same time, the new functional current collector material has great flexibility, which can make lithium ions deposit more evenly on the surface, inhibit the growth of lithium dendrites, and thus reduce the internal short circuit of the battery. Therefore, the new functional current collector material can provide higher safety guarantee for lithium batteries.

[0003] However, since the structure of the novel functional current collector material is directly combined by a polymer layer (such as PET, with a coefficient of thermal expansion of 50 - 70 ppm / °C) and a metal layer (such as aluminum, with a coefficient of thermal expansion of 22.2 ppm / °C), the difference in the coefficients of thermal expansion of these two materials is relatively large. During the battery charging process, the electrochemical reaction is not completely efficient, and part of the electrical energy will be converted into heat energy, resulting in an increase in the battery temperature, which in turn causes the current collector to expand. Due to the different coefficients of thermal expansion of the polymer layer and the metal layer, after cooling, polymer materials such as PET with a larger coefficient of thermal expansion retract to a greater extent, resulting in the formation of gaps between the polymer layer and the metal layer or the peeling of the metal layer. This phenomenon will accelerate the aging of the battery and seriously affect the cycle life and performance of the battery. In addition, during the use of lithium batteries, due to reasons such as overcharging, short - circuiting, and impact, thermal runaway may be triggered, leading to a sharp rise in temperature, and even fire or explosion. The polymer layer in the current collector, such as PET, although having good insulation and mechanical properties, may be easily decomposed at high temperatures, releasing combustible gases and increasing safety hazards. Therefore, improving the flame - retardant performance of the current collector can significantly reduce the risks of the battery under extreme conditions and ensure the safety of users. During the manufacturing and use of lithium batteries, the current collector needs to undergo multiple processing steps such as winding and slitting, and also withstand the friction of electrode materials inside the battery. If the wear - resistant performance of the current collector is not good, problems such as wear and scratches are likely to occur during processing and use. This will not only lead to a decrease in the mechanical strength of the material but may also cause discontinuity in the electron transmission path, affecting the electrochemical performance of the battery, and in severe cases, internal short - circuiting and safety problems will be caused.

[0004] In order to overcome the defects of the prior art, the present invention provides a functional aluminum current collector with high tensile strength and its preparation process. Summary of the Invention

[0005] The purpose of the present invention is to provide a functional aluminum current collector with high tensile strength and its preparation process to solve the problems in the prior art.

[0006] To solve the above - mentioned technical problems, the present invention provides the following technical solutions:

[0007] A preparation process of a functional aluminum current collector with high tensile strength includes the following steps:

[0008] Step 1: Sufficiently mix 70 - 80 wt% of nano - alumina particles, 10 - 20 wt% of nano - magnesia particles, and 10 - 20 wt% of nano - silica particles to obtain a mixed material; successively subject the mixed material to embryo pressing, hot - press sintering, cutting, and ball - milling to obtain nano - ceramic particles;

[0009] Step 2: Thoroughly mix 80 - 90 wt% of polyethylene terephthalate resin, 5 - 10 wt% of diethylene glycol, 5 - 10 wt% of acetaldehyde, and 10 - 15 wt% of nano-ceramic particles to obtain a preform; subject the preform to heating and melting, extrusion into a film, curing and forming, and mechanical traction to obtain a current collector base film; fix the current collector base film, and through film threading with rewinding and unwinding, tension adjustment, and aluminum evaporation coating, obtain a functional aluminum current collector.

[0010] More optimally, in Step 1, the diameters of the nano-aluminum oxide particles, nano-magnesium oxide particles, and nano-silicon dioxide particles are 10 - 20 nm; the hot pressing and sintering parameters: the sintering pressure is 500 - 600 atm, and the sintering temperature is 2000 - 2200 °C; the ball milling parameters: the self-rotation speed is 700 - 800 r / min, the revolution speed is 350 - 400 r / min, and the ball milling time is 8 - 10 h.

[0011] More optimally, in Step 2, the thickness of the current collector base film is 4 - 6 μm; the tension adjustment is such that the film unwinding end is 120 - 130 N and the winding end is 80 - 100 N; the process of aluminum evaporation coating: After pushing the winding trolley fixing the current collector base film into the evaporation chamber, evacuate to 4.5×10 -3 -5.0×10 -3 Pa, the temperature of the cooling roller is -20 ~ -20 °C, then start the winding trolley, control the speed at 8 - 10 m / min, simultaneously heat the evaporation boat and feed aluminum wire, and the wire feeding speed is 400 - 450 mm / min until the production is completed to obtain a functional aluminum current collector.

[0012] More optimally, in Step 2, modify the polyethylene terephthalate resin to obtain an organosilicon-modified polyester resin. Specifically: Step S1: Add dimethyldimethoxysilane, methyltrimethoxysilane, a catalyst hydrochloric acid solution, and a silane coupling agent KH560 to a solvent, stir and react at 75 - 85 °C for 7 - 9 h. After the reaction ends, wash, dehydrate, perform rotary evaporation, and remove impurities by oil bath to obtain an organosilicon resin;

[0013] Step S2: Add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenylphosphine, and the organosilicon resin to toluene, and react in a water bath at 55 - 75 °C for 4 - 6 h to obtain a phosphorus-modified organosilicon resin; dissolve the phosphorus-modified organosilicon resin in absolute ethanol, dissolve 4-aminopyridine in absolute ethanol, then fully mix the two solutions, and stir and react at 65 - 75 °C for 7 - 8 h. After the reaction ends, cool, filter by suction, wash, and dry under vacuum to obtain a flame-retardant organosilicon resin;

[0014] Step S3: Heat and melt the polyethylene terephthalate resin at 270 - 300 °C, then add the flame-retardant silicone resin and stir and blend for 25 - 30 min to obtain the silicone-modified polyester resin.

[0015] More optimally, in step S1, the solvent is obtained by mixing toluene and ethanol, and the mixing volume ratio is 1:1; the reaction mass ratio of dimethyldimethoxysilane, methyltrimethoxysilane, and silane coupling agent KH560 is 0.15:1:(2.0 - 2.5); the catalyst hydrochloric acid solution is 2.0 - 2.5 wt% of the total mass of the reactants.

[0016] More optimally, in step S2, when preparing the phosphorus-modified silicone resin, the reaction mass ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenylphosphine, and silicone resin is (5 - 7):1:25; when preparing the flame-retardant silicone resin, the reaction mass ratio of the modified silicone resin and 4-aminopyridine is 25:(4 - 6).

[0017] More optimally, in step S3, the blending mass ratio of the polyethylene terephthalate resin and the flame-retardant silicone resin is 5:(0.8 - 1.0).

[0018] More optimally, in step two, the nano-ceramic particles are subjected to a modification and dispersion treatment to obtain a flame-retardant nano-ceramic particle, specifically: the nano-ceramic particles are ultrasonically dispersed in anhydrous ethanol, and silane coupling agent KH550 is added dropwise under a nitrogen atmosphere, and the mixture is stirred and reacted at 85 - 90 °C for 25 - 30 h. After the reaction is completed, it is filtered, washed, and vacuum dried to obtain amino-functionalized nano-ceramic particles; the amino-functionalized nano-ceramic particles and 4-formylphenylboronic acid are dissolved in anhydrous methanol, and the mixture is stirred and reacted at 25 - 30 °C for 50 - 60 h. After the reaction is completed, it is centrifuged, washed, and vacuum dried to obtain the flame-retardant nano-ceramic particles.

[0019] More optimally, when preparing the amino-functionalized nano-ceramic particles, the mass-volume ratio of the nano-ceramic particles and silane coupling agent KH550 is 1:(10 - 12); when preparing the flame-retardant nano-ceramic particles, the reaction mass ratio of the amino-functionalized nano-ceramic particles and 4-formylphenylboronic acid is (0.2 - 0.3):0.6.

[0020] The beneficial effects of the present invention:

[0021] The characteristics of the present invention lie in providing a preparation process for a functional aluminum current collector with high tensile strength, which has the following specific advantages: (1) In the present invention, sintered nano-ceramic particles are introduced into the polymer material layer to reduce the thermal expansion coefficient of the polymer material. Due to their own thermal stability, the ceramic particles expand much less than the polymer material when heated, reducing the thermal expansion of the overall material like "anchor points". When the current collector is heated, the polymer layer and the metal layer can expand uniformly, avoiding the peeling of the metal layer and the polymer layer, improving the service life of the functional aluminum current collector and increasing the number of battery cycles.

[0022] (2) The aluminum current collector of the present invention has a relatively high tensile strength. During the rolling process of preparing the battery electrode sheet, the current collector is not prone to deformation, improving the cycle life of the battery. The current collector of the lithium metal battery needs to have good stability to withstand the pressure and temperature changes inside the battery. During the charge and discharge process, lithium is continuously deintercalated and intercalated on the surface of the lithium metal electrode, and a current collector with a relatively high tensile strength is required to automatically adjust the volume change of the battery.

[0023] (3) The heat resistance of the current collector base film in the present invention is improved, and it is not prone to deformation during the evaporation coating process, improving the physical properties of the current collector product and at the same time improving the production efficiency.

[0024] Furthermore, the characteristics of the present invention lie in modifying polyethylene terephthalate resin to obtain an organosilicon-modified polyester resin: In step S1, by adding dimethyldimethoxysilane, methyltrimethoxysilane, and silane coupling agent KH560 as main raw materials, an organosilicon resin containing a large amount of epoxy groups is prepared. In step S2, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenylphosphine, and the organosilicon resin are added to toluene, and after a water bath reaction, a phosphorus-modified organosilicon resin is obtained; in this step, the active P-H bond and the epoxy group in the organosilicon resin undergo a ring-opening reaction to introduce a phosphorus-containing flame-retardant structure into the organosilicon resin, obtaining a phosphorus-modified organosilicon resin; when preparing the phosphorus-modified organosilicon resin, by setting the reaction mass ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenylphosphine, and the organosilicon resin to (5-7):1:25, a certain amount of epoxy groups in the organosilicon resin will remain, and the remaining epoxy groups can be used for the next reaction introduction. Furthermore, using the phosphorus-modified organosilicon resin and 4-aminopyridine as main raw materials, a flame-retardant organosilicon resin is obtained by stirring and reacting; in this step, 4-aminopyridine and the remaining epoxy groups in the phosphorus-modified organosilicon resin undergo a ring-opening reaction to introduce a nitrogen-containing flame-retardant structure into the phosphorus-modified organosilicon resin, obtaining a flame-retardant organosilicon resin. In step S3, the polyethylene terephthalate resin and the flame-retardant organosilicon resin are melt-blended to obtain an organosilicon-modified polyester resin; the organosilicon-modified polyester resin has good flame-retardant performance and wear resistance by introducing various flame-retardant elements and organosilicon components.

[0025] In addition, the present invention uses nano-aluminum oxide particles, nano-magnesium oxide particles, and nano-silica particles as raw materials to prepare nano-ceramic particles; then the nano-ceramic particles are subjected to modified dispersion treatment to obtain a flame-retardant nano-ceramic particle, specifically: the nano-ceramic particles are modified by adding a silane coupling agent KH550 to obtain amino-functionalized nano-ceramic particles; the amino-functionalized nano-ceramic particles and 4-formylphenylboronic acid are dissolved in anhydrous methanol, and a flame-retardant nano-ceramic particle is obtained through stirring reaction. In this step, amino groups are introduced by modification with a silane coupling agent, and at the same time, the dispersion performance of the nano-ceramic particles is improved. Furthermore, a Schiff base reaction occurs by adding 4-formylphenylboronic acid to introduce a boron compound to obtain a flame-retardant nano-ceramic particle.

[0026] Finally, the present invention uses an organosilicon-modified polyester resin, diethylene glycol, acetaldehyde, and flame-retardant nano-ceramic particles as raw materials to obtain a current collector base film; the surfaces of the organosilicon-modified polyester resin, diethylene glycol, and flame-retardant nano-ceramic particles all contain a large number of active hydroxyl groups. Therefore, hydrogen bonds can be formed between the hydroxyl groups among various raw materials, thereby significantly improving the interfacial compatibility between the two. In addition, during the process of evaporating metal aluminum, the hydroxyl groups on the surface of the current collector base film can form chemical bonds or hydrogen bonds with the surface of the metal aluminum, thereby enhancing the bonding strength between the metal aluminum layer and the current collector base film. Therefore, the current collector prepared with this current collector base film has good flame retardancy, wear resistance, and high cycle performance, and thus has broad application prospects in the field of battery technology. Specific Embodiments

[0027] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0028] Source of raw materials:

[0029] The polyethylene terephthalate resin is provided by Wuhan Kangqiong Biomedical Technology Co., Ltd., and the model is kq-051.

[0030] Example 1: Step 1: Thoroughly mix 75 wt% of nano-alumina particles, 15 wt% of nano-magnesia particles, and 10 wt% of nano-silica particles to obtain a mixture; sequentially subject the mixture to compacting, hot press sintering, cutting, and ball milling to obtain nano-ceramic particles; the diameters of the nano-alumina particles, nano-magnesia particles, and nano-silica particles are 10 nm; hot press sintering parameters: sintering pressure is 500 atm, and sintering temperature is 2000 °C; ball milling parameters: rotation speed is 800 r / min, revolution speed is 400 r / min, and ball milling time is 10 h;

[0031] Step 2: Thoroughly mix 80 wt% of polyethylene terephthalate resin, 5 wt% of diethylene glycol, 5 wt% of acetaldehyde, and 10 wt% of nano-ceramic particles to obtain a preform; subject the preform to heating and melting, extrusion into a film, curing and forming, and mechanical traction to obtain a current collector base film; fix the current collector base film, and through unwinding and threading the film, tension adjustment, and aluminum evaporation coating, obtain a functional aluminum current collector; the thickness of the current collector base film is 6 μm; the tension adjustment is 130 N at the film unwinding end and 100 N at the winding end; the process of aluminum evaporation coating: after pushing the winding cart fixing the current collector base film into the evaporation chamber, evacuate to 5×10 -3 Pa, the temperature of the cooling roller is -20 °C, then start the winding cart, control the speed at 10 m / min, simultaneously heat the evaporation boat and feed aluminum wire, the wire feeding speed is 450 mm / min, until the production is completed to obtain a functional aluminum current collector.

[0032] Example 2: It is basically the same as Example 1, the difference lies in: 60 - 70 wt% of nano-alumina particles, 20 - 30 wt% of nano-magnesia particles, 10 - 20 wt% of nano-silica particles

[0033] Step 1: Thoroughly mix 65 wt% of nano-alumina particles, 25 wt% of nano-magnesia particles, and 10 wt% of nano-silica particles to obtain a mixture; sequentially subject the mixture to compacting, hot press sintering, cutting, and ball milling to obtain nano-ceramic particles; the diameters of the nano-alumina particles, nano-magnesia particles, and nano-silica particles are 10 nm; hot press sintering parameters: sintering pressure is 500 atm, and sintering temperature is 2000 °C; ball milling parameters: rotation speed is 800 r / min, revolution speed is 400 r / min, and ball milling time is 10 h;

[0034] Step 2: Thoroughly mix 80 wt% of polyethylene terephthalate resin, 5 wt% of diethylene glycol, 5 wt% of acetaldehyde, and 10 wt% of nano-ceramic particles to obtain a preform; subject the preform to heating and melting, extrusion into a film, curing and forming, and mechanical traction to obtain a current collector base film; fix the current collector base film, and through unwinding and threading, tension adjustment, and aluminum evaporation coating, obtain a functional aluminum current collector; the thickness of the current collector base film is 6 μm; the tension is adjusted to 130 N at the film unwinding end and 100 N at the winding end; the process of aluminum evaporation coating: After pushing the winding trolley fixing the current collector base film into the evaporation chamber, evacuate to 5×10 -3 Pa, the temperature of the cooling roller is -20°C, then start the winding trolley, control the speed at 10 m / min, simultaneously heat the evaporation boat and feed aluminum wire, and the wire feeding speed is 450 mm / min until production is completed to obtain a functional aluminum current collector.

[0035] Example 3: Basically the same as Example 1, the differences are: 80 - 90 wt% of nano-aluminum oxide particles, 5 - 10 wt% of nano-magnesium oxide particles, 5 - 10 wt% of nano-silicon dioxide particles

[0036] Step 1: Thoroughly mix 85 wt% of nano-aluminum oxide particles, 7.5 wt% of nano-magnesium oxide particles, and 7.5 wt% of nano-silicon dioxide particles to obtain a mixture; sequentially subject the mixture to blank pressing, hot pressing sintering, cutting, and ball milling to obtain nano-ceramic particles; the diameters of the nano-aluminum oxide particles, nano-magnesium oxide particles, and nano-silicon dioxide particles are 10 nm; the hot pressing sintering parameters: the sintering pressure is 500 atm, and the sintering temperature is 2000°C; the ball milling parameters: the self-rotation speed is 800 r / min, the revolution speed is 400 r / min, and the ball milling time is 10 h;

[0037] Step 2: Thoroughly mix 80 wt% of polyethylene terephthalate resin, 5 wt% of diethylene glycol, 5 wt% of acetaldehyde, and 10 wt% of nano-ceramic particles to obtain a preform; subject the preform to heating and melting, extrusion into a film, curing and forming, and mechanical traction to obtain a current collector base film; fix the current collector base film, and through unwinding and threading, tension adjustment, and aluminum evaporation coating, obtain a functional aluminum current collector; the thickness of the current collector base film is 6 μm; the tension is adjusted to 130 N at the film unwinding end and 100 N at the winding end; the process of aluminum evaporation coating: After pushing the winding trolley fixing the current collector base film into the evaporation chamber, evacuate to 5×10 -3 Pa, the temperature of the cooling roller is -20°C, then start the winding trolley, control the speed at 10 m / min, simultaneously heat the evaporation boat and feed aluminum wire, and the wire feeding speed is 450 mm / min until production is completed to obtain a functional aluminum current collector.

[0038] Example 4: Basically the same as Example 1, the difference is that the ball milling time of the nano-ceramic particles is 5 h

[0039] Step 1: Thoroughly mix 75 wt% of nano-aluminum oxide particles, 15 wt% of nano-magnesium oxide particles, and 10 wt% of nano-silicon dioxide particles to obtain a mixed material; sequentially subject the mixed material to embryo pressing, hot press sintering, cutting, and ball milling to obtain nano-ceramic particles; the diameters of the nano-aluminum oxide particles, nano-magnesium oxide particles, and nano-silicon dioxide particles are 10 nm; hot press sintering parameters: sintering pressure is 500 atm, sintering temperature is 2000 °C; ball milling parameters: rotation speed is 800 r / min, revolution speed is 400 r / min, and ball milling time is 5 h;

[0040] Step 2: Thoroughly mix 80 wt% of polyethylene terephthalate resin, 5 wt% of diethylene glycol, 5 wt% of acetaldehyde, and 10 wt% of nano-ceramic particles to obtain a preform; subject the preform to heating and melting, extrusion into a film, curing and forming, and mechanical traction to obtain a current collector base film; fix the current collector base film, and through unwinding and threading the film, tension adjustment, and aluminum evaporation coating, obtain a functional aluminum current collector; the thickness of the current collector base film is 6 μm; the tension adjustment is 130 N at the film unwinding end and 100 N at the winding end; the process of aluminum evaporation coating: After pushing the winding trolley fixing the current collector base film into the evaporation chamber, evacuate to 5×10 -3 Pa, the temperature of the cooling roller is -20 °C, then start the winding trolley, control the speed at 10 m / min, simultaneously heat the evaporation boat and feed aluminum wire, and the wire feeding speed is 450 mm / min until the production is completed to obtain a functional aluminum current collector.

[0041] Example 5: Basically the same as Example 1, the difference is that the ball milling time of the nano-ceramic particles is 15 h

[0042] Step 1: Thoroughly mix 75 wt% of nano-aluminum oxide particles, 15 wt% of nano-magnesium oxide particles, and 10 wt% of nano-silicon dioxide particles to obtain a mixed material; sequentially subject the mixed material to embryo pressing, hot press sintering, cutting, and ball milling to obtain nano-ceramic particles; the diameters of the nano-aluminum oxide particles, nano-magnesium oxide particles, and nano-silicon dioxide particles are 10 nm; hot press sintering parameters: sintering pressure is 500 atm, sintering temperature is 2000 °C; ball milling parameters: rotation speed is 800 r / min, revolution speed is 400 r / min, and ball milling time is 15 h;

[0043] Step 2: Thoroughly mix 80 wt% of polyethylene terephthalate resin, 5 wt% of diethylene glycol, 5 wt% of acetaldehyde, and 10 wt% of nano-ceramic particles to obtain a preform; subject the preform to heating and melting, extrusion into a film, curing and forming, and mechanical traction to obtain a current collector base film; fix the current collector base film, and through film threading with pay-off and rewind, tension adjustment, and aluminum evaporation coating, obtain a functional aluminum current collector; the thickness of the current collector base film is 6 μm; the tension is adjusted to 130 N at the film pay-off end and 100 N at the winding end; the process of aluminum evaporation coating: After pushing the winding trolley fixing the current collector base film into the evaporation chamber, evacuate to 5×10 -3 Pa, the temperature of the cooling roller is -20°C, then start the winding trolley, control the speed at 10 m / min, simultaneously heat the evaporation boat and feed aluminum wire, and the wire feeding speed is 450 mm / min until production is completed to obtain a functional aluminum current collector.

[0044] Example 6: Basically the same as Example 1, the difference is that the preparation process of the nano-ceramic particles is removed.

[0045] Step 1: Thoroughly mix 85 wt% of polyethylene terephthalate resin, 7.5 wt% of diethylene glycol, and 7.5 wt% of acetaldehyde to obtain a preform; subject the preform to heating and melting, extrusion into a film, curing and forming, and mechanical traction to obtain a current collector base film; fix the current collector base film, and through film threading with pay-off and rewind, tension adjustment, and aluminum evaporation coating, obtain a functional aluminum current collector; the thickness of the current collector base film is 6 μm; the tension is adjusted to 130 N at the film pay-off end and 100 N at the winding end; the process of aluminum evaporation coating: After pushing the winding trolley fixing the current collector base film into the evaporation chamber, evacuate to 5×10 -3 Pa, the temperature of the cooling roller is -20°C, then start the winding trolley, control the speed at 10 m / min, simultaneously heat the evaporation boat and feed aluminum wire, and the wire feeding speed is 450 mm / min until production is completed to obtain a functional aluminum current collector.

[0046] Example 7: Basically the same as Example 1, the difference is that the polyethylene terephthalate resin is modified to obtain an organosilicon-modified polyester resin; the nano-ceramic particles are subjected to a modification and dispersion treatment to obtain a flame-retardant nano-ceramic particle.

[0047] Step 1: Thoroughly mix 75 wt% of nano-aluminum oxide particles, 15 wt% of nano-magnesium oxide particles, and 10 wt% of nano-silicon dioxide particles to obtain a mixture; subject the mixture to embryo pressing, hot pressing sintering, cutting, and ball milling in sequence to obtain nano-ceramic particles; the diameters of the nano-aluminum oxide particles, nano-magnesium oxide particles, and nano-silicon dioxide particles are 10 nm; the hot pressing sintering parameters: the sintering pressure is 500 atm, and the sintering temperature is 2000°C; the ball milling parameters: the self-rotation speed is 800 r / min, the revolution speed is 400 r / min, and the ball milling time is 10 h.

[0048] Step 2: Add dimethyldimethoxysilane, methyltrimethoxysilane, catalyst hydrochloric acid solution, and silane coupling agent KH560 to a solvent, and stir and react at 80 °C for 8 h. After the reaction is completed, wash, dehydrate, rotary evaporate, and remove impurities by oil bath to obtain an organosilicon resin; the solvent is obtained by mixing toluene and ethanol, and the mixing volume ratio is 1:1; the reaction mass ratio of dimethyldimethoxysilane, methyltrimethoxysilane, and silane coupling agent KH560 is 0.15:1:2.3; the catalyst hydrochloric acid solution is 2.2 wt% of the total mass of the reactants;

[0049] Add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenylphosphine, and the organosilicon resin to toluene, and react in a water bath at 60 °C for 5 h to obtain a phosphorus-modified organosilicon resin; dissolve the phosphorus-modified organosilicon resin in absolute ethanol, dissolve 4-aminopyridine in absolute ethanol, and then fully mix the two solutions and stir and react at 70 °C for 7.5 h. After the reaction is completed, cool, filter, wash, and vacuum dry to obtain a flame-retardant organosilicon resin; when preparing the phosphorus-modified organosilicon resin, the reaction mass ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenylphosphine, and the organosilicon resin is 6:1:25; when preparing the flame-retardant organosilicon resin, the reaction mass ratio of the modified organosilicon resin and 4-aminopyridine is 5:1;

[0050] Heat and melt the polyethylene terephthalate resin at 280 °C, then add the flame-retardant organosilicon resin and stir and blend for 27 min to obtain an organosilicon-modified polyester resin; the blending mass ratio of the polyethylene terephthalate resin and the flame-retardant organosilicon resin is 5:0.9;

[0051] Ultrasonically disperse the nano-ceramic particles in absolute ethanol, dropwise add silane coupling agent KH550 under a nitrogen atmosphere, and stir and react at 87 °C for 27 h. After the reaction is completed, filter, wash, and vacuum dry to obtain amino-functionalized nano-ceramic particles; dissolve the amino-functionalized nano-ceramic particles and 4-formylphenylboronic acid in absolute methanol, and stir and react at 27 °C for 55 h. After the reaction is completed, centrifuge, wash, and vacuum dry to obtain flame-retardant nano-ceramic particles; when preparing the amino-functionalized nano-ceramic particles, the mass-volume ratio of the nano-ceramic particles and silane coupling agent KH550 is 1:11; when preparing the flame-retardant nano-ceramic particles, the reaction mass ratio of the amino-functionalized nano-ceramic particles and 4-formylphenylboronic acid is 0.1:0.3;

[0052] Mix 80 wt% of silicone-modified polyester resin, 5 wt% of diethylene glycol, 5 wt% of acetaldehyde, and 10 wt% of flame-retardant nano-ceramic particles thoroughly to obtain a preform; subject the preform to heating and melting, extrusion into a film, curing and shaping, and mechanical traction to obtain a current collector base film; fix the current collector base film, and through film threading with rewinding and unwinding, tension adjustment, and aluminum evaporation plating, obtain a functional aluminum current collector; the thickness of the current collector base film is 6 μm; the tension is adjusted such that the film unwinding end is 130 N and the winding end is 100 N; the process of aluminum evaporation plating: After pushing the winding cart fixing the current collector base film into the evaporation chamber, evacuate to 5×10 -3 Pa, the temperature of the cooling roll is -20°C, then start the winding cart, control the speed at 10 m / min, simultaneously heat the evaporation boat and feed aluminum wire, with the wire feeding speed at 450 mm / min, until the production is completed to obtain a functional aluminum current collector.

[0053] Comparative Example 1: Remove the modification treatment of polyethylene terephthalate resin, and the rest is the same as in Example 7. The specific steps are as follows: Step 1: Thoroughly mix 75 wt% of nano-aluminum oxide particles, 15 wt% of nano-magnesium oxide particles, and 10 wt% of nano-silicon dioxide particles to obtain a mixture; subject the mixture to embryo pressing, hot pressing sintering, cutting, and ball milling in sequence to obtain nano-ceramic particles; the diameters of the nano-aluminum oxide particles, nano-magnesium oxide particles, and nano-silicon dioxide particles are 10 nm; the hot pressing sintering parameters: sintering pressure is 500 atm, sintering temperature is 2000°C; the ball milling parameters: rotation speed is 800 r / min, revolution speed is 400 r / min, and the ball milling time is 10 h;

[0054] Step 2: Ultrasonically disperse the nano-ceramic particles in absolute ethanol, add silane coupling agent KH550 dropwise under a nitrogen environment, stir and react at 87°C for 27 h. After the reaction ends, perform suction filtration, washing, and vacuum drying to obtain amino-functionalized nano-ceramic particles; dissolve the amino-functionalized nano-ceramic particles and 4-formylphenylboronic acid in absolute methanol, stir and react at 27°C for 55 h. After the reaction ends, perform centrifugation, washing, and vacuum drying to obtain flame-retardant nano-ceramic particles; when preparing the amino-functionalized nano-ceramic particles, the mass-volume ratio of the nano-ceramic particles to the silane coupling agent KH550 is 1:11; when preparing the flame-retardant nano-ceramic particles, the reaction mass ratio of the amino-functionalized nano-ceramic particles to 4-formylphenylboronic acid is 0.1:0.3;

[0055] 80 wt% of polyethylene terephthalate resin, 5 wt% of diethylene glycol, 5 wt% of acetaldehyde, and 10 wt% of flame-retardant nano-ceramic particles are fully mixed to obtain a preform; the preform is heated and melted, extruded into a film, cured and formed, and mechanically drawn to obtain a current collector base film; the current collector base film is fixed, passed through the film with winding and unwinding, the tension is adjusted, and aluminum metal is evaporated to obtain a functional aluminum current collector; the thickness of the current collector base film is 6 μm; the tension is adjusted to 130 N at the film unwinding end and 100 N at the winding end; the process of evaporating aluminum metal: after the winding trolley fixing the current collector base film is pushed into the evaporation chamber, the vacuum is pumped to 5×10 -3 Pa, the temperature of the cooling roller is -20°C, then the winding trolley is started, the speed is controlled at 10 m / min, and at the same time the evaporation boat is heated and aluminum wire is fed, the wire feeding speed is 450 mm / min, until the production is completed to obtain a functional aluminum current collector.

[0056] Comparative Example 2: Remove the modification and dispersion treatment of nano-ceramic particles, and the rest is the same as in Example 7. The specific steps are as follows: Step 1: 75 wt% of nano-aluminum oxide particles, 15 wt% of nano-magnesium oxide particles, and 10 wt% of nano-silicon dioxide particles are fully mixed to obtain a mixture; the mixture is successively subjected to embryo pressing, hot pressing sintering, cutting, and ball milling to obtain nano-ceramic particles; the diameters of the nano-aluminum oxide particles, nano-magnesium oxide particles, and nano-silicon dioxide particles are 10 nm; the hot pressing sintering parameters: the sintering pressure is 500 atm, and the sintering temperature is 2000°C; the ball milling parameters: the self-rotation speed is 800 r / min, the revolution speed is 400 r / min, and the ball milling time is 10 h;

[0057] Step 2: Dimethyldimethoxysilane, methyltrimethoxysilane, catalyst hydrochloric acid solution, and silane coupling agent KH560 are added to the solvent, and stirred and reacted at 80°C for 8 h. After the reaction is completed, it is washed, dehydrated, rotary evaporated, and the impurities are removed by oil bath to obtain an organosilicon resin; the solvent is obtained by mixing toluene and ethanol, and the mixing volume ratio is 1:1; the reaction mass ratio of dimethyldimethoxysilane, methyltrimethoxysilane, and silane coupling agent KH560 is 0.15:1:2.3; the catalyst hydrochloric acid solution is 2.2 wt% of the total mass of the reactants;

[0058] 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenylphosphine, and organosilicon resin were added to toluene, and the reaction was carried out in a water bath at 60 °C for 5 h to obtain phosphorus-modified organosilicon resin; the phosphorus-modified organosilicon resin was dissolved in absolute ethanol, 4-aminopyridine was dissolved in absolute ethanol, and then the two solutions were fully mixed and stirred at 70 °C for 7.5 h. After the reaction, it was cooled, filtered by suction, washed, and dried in vacuo to obtain flame-retardant organosilicon resin; when preparing the phosphorus-modified organosilicon resin, the reaction mass ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenylphosphine, and organosilicon resin was 6:1:25; when preparing the flame-retardant organosilicon resin, the reaction mass ratio of the modified organosilicon resin and 4-aminopyridine was 5:1;

[0059] The polyethylene terephthalate resin was heated and melted at 280 °C, and then the flame-retardant organosilicon resin was added and stirred and blended for 27 min to obtain organosilicon-modified polyester resin; the blending mass ratio of the polyethylene terephthalate resin and the flame-retardant organosilicon resin was 5:0.9;

[0060] 80 wt% of the organosilicon-modified polyester resin, 5 wt% of diethylene glycol, 5 wt% of acetaldehyde, and 10 wt% of nano-ceramic particles were fully mixed to obtain a preform; the preform was heated and melted, extruded into a film, cured and formed, and mechanically drawn to obtain a current collector base film; the current collector base film was fixed, passed through the film by winding and unwinding, the tension was adjusted, and aluminum metal was evaporated to obtain a functional aluminum current collector; the thickness of the current collector base film was 6 μm; the tension was adjusted to 130 N at the film unwinding end and 100 N at the winding end; the process of evaporating aluminum metal: after the winding cart fixing the current collector base film was pushed into the evaporation chamber, the vacuum was pumped to 5×10 -3 Pa, the temperature of the cooling roller was -20 °C, then the winding cart was started, the speed was controlled at 10 m / min, and at the same time the evaporation boat was heated and aluminum wire was fed, the wire feeding speed was 450 mm / min, until the production was completed to obtain a functional aluminum current collector.

[0061] Detection test:

[0062] Tensile strength test: The functional aluminum current collector prepared by the present invention was cut into small strips of 100*15 mm; the two ends of the small strip of the functional aluminum current collector were clamped by a tensile machine; the tensile machine moved at a constant speed, and when the functional aluminum current collector broke, the tensile strength and elongation at break were recorded; the room temperature tensile strength and elongation at break of the aluminum foil were measured by an electronic universal material testing machine under the test conditions of a gauge length of 10 mm, a tensile speed of 100 mm / min, a width of 15 mm, and other requirements were determined according to the method specified in GB / T 1040.3-2006.

[0063] Coating peeling force test: Cut the functional aluminum current collector to obtain a test sample with dimensions of 15 mm × 100 mm. Stick the 3M-9080A-15 mm tape on the stainless steel plate, then evenly stick the measurement sample on the double-sided tape, roll it back and forth 2 times with a 2 kg standard small roller, and then stick the 3M-9080A-14 mm tape on the surface of the test sample, and roll it back and forth 2 times with a 2 kg standard small roller; then place the pressed sample on the tensile machine and perform peeling at a 180° stretch, with a speed of 100 mm / min, a width of 14 mm, and the peeling strength result taking the maximum value.

[0064] Sheet resistance test: Turn on the power of the sheet resistance meter, press the probe on the surface of the functional aluminum current collector, and the sheet resistance can be measured.

[0065] 30-minute thermal expansion test of the current collector base film: First, cut a 100*15 mm base film and mark a 30*15 mm area in the middle, and calculate the elongation rate based on the change in this area. Fix the current collector base film on the oven carrier plate with tape, and fix it with a certain mass (100 g) of metal below to ensure uniform stress. Place the fixed aluminum foil / base film in the oven, start timing after the temperature reaches the set value (150 °C), take out the original film after baking for 30 minutes, measure the marked area, and compare the change in elongation rate before and after.

[0066] Electrolyte peeling test of the current collector: Cut the functional aluminum current collector prepared by the present invention into a test sample with dimensions of 15 mm × 100 mm, then vacuum-seal the test sample with an aluminum-plastic film, inject electrolyte with a syringe, heat the oven temperature to the set temperature, place the packaged test sample in the oven and bake for 30 minutes, then take it out and cool it to room temperature, and repeat the heating and cooling steps of the test sample 10 times. Then clean the surface of the test sample soaked in electrolyte with 99.9% alcohol, place it in an oven at 25 °C for surface drying, and after drying, stick the 3M-9080A-15 mm tape on the stainless steel plate, then evenly stick the test sample on the double-sided tape, roll it back and forth 2 times with a 2 kg standard small roller, and then stick the 3M-9080A-14 mm tape on the surface of the test sample, and roll it back and forth 2 times with a 2 kg standard small roller. Place the pressed test sample on the tensile machine and perform peeling at a 180° stretch, with a speed of 100 mm / min, a width set at 14 mm, and the peeling strength result taking the maximum value.

[0067] Wear resistance test: A CFT-I friction and wear test system was used to conduct friction and wear tests at room temperature. A linear reciprocating friction and wear method with spherical contact was adopted. The size of the specimen was 10*10 mm. The counter ball used was a Si3N4 ball with a diameter of 6 mm. The load was 5 N, the reciprocating distance was 5 mm, the reciprocating speed was 1 m / min, and the test time was 30 min. During the friction and wear test, the surface profile curve of the wear scar was measured using the built-in profilometer. Five positions were evenly selected on the wear scar with a length of 5 mm for measurement. The average wear scar cross-sectional area was calculated, and then the wear scar volume was obtained by multiplying the average wear scar cross-sectional area by the wear scar length, which was recorded as the wear amount. Finally, the average wear rate was obtained by dividing the wear amount by the product of the load and the sliding distance.

[0068] Flame retardancy test: The limiting oxygen index test was carried out on the current collector base film prepared by the present invention according to the standard JIS-K7201-3-2008. The larger the limiting oxygen index value, the better the flame retardancy performance. The results are shown in the following table:

[0069] Table 1 Physical test data of the functional aluminum current collector

[0070]

[0071] Table 2 30-minute thermal expansion test data of the current collector base film

[0072] 140℃ 150℃ 160℃ 170℃ 180℃ Example 1 0 0.05 0.19 0.34 0.57 Example 2 0 0.12 0.36 0.63 0.96 Example 3 0 0.11 0.31 0.56 1.13 Example 4 0 0.17 0.48 0.77 1.31 Example 5 0 0.08 0.22 0.41 0.74 Example 6 0.15 0.54 1.16 1.74 3.21 Example 7 0 0.07 0.23 0.45 0.75 Comparative Example 1 0 0.09 0.28 0.56 0.73 Comparative Example 2 0 0.11 0.32 0.65 0.82

[0073] Table 3 Current collector electrolyte stripping test data

[0074] 30℃ 40℃ 50℃ 60℃ Example 1 1534 1416 1253 1052 Example 2 1428 1294 1192 984 Example 3 1286 1149 1006 788 Example 4 1477 1302 1085 893 Example 5 1503 1396 1181 876 Example 6 1175 861 403 NG Example 7 1435 1325 1225 997 Comparative Example 1 1456 1359 1025 1022 Comparative Example 2 1465 1385 1048 1035

[0075] Note: NG means that the metal coating of the aluminum current collector directly falls off.

[0076] Table 4 Flame retardancy and wear resistance test data

[0077]

[0078] It can be seen from the analysis of Tables 1-4 that: on the premise of meeting the physical and appearance properties of the aluminum current collector, the present invention provides an aluminum current collector with a small difference in thermal expansion coefficient between the metal layer and the polymer layer. By reducing the thermal expansion coefficient of the polymer layer of the aluminum current collector, the difference in thermal expansion coefficient between the polymer layer and the metal layer is reduced, so that during the use of the current collector in the battery, the polymer layer and the metal layer are not easily peeled off, the service life of the current collector is extended, and the battery cycle life is improved. In addition, the present invention modifies polyethylene terephthalate resin to obtain an organosilicon-modified polyester resin; the nano-ceramic particles are modified and dispersed to obtain a flame-retardant nano-ceramic particle. The functional aluminum current collector prepared by adding these two raw materials has good flame retardancy (the oxygen index can reach 37%) and wear resistance (the average wear rate can reach 3.5×10-4 mm 3 m -1 N -1 )。

[0079] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0080] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A process for preparing a functional aluminum current collector with high tensile strength, characterized in that: The following steps are involved: Step 1: fully mix 70-80wt% of nano-alumina particles, 10-20wt% of nano-magnesium oxide particles, and 10-20wt% of nano-silicon dioxide particles to obtain a mixture; and sequentially perform embryo pressing, hot pressing sintering, cutting, and ball milling on the mixture to obtain nano-ceramic particles; Step 2: 80-90wt% of polyethylene terephthalate resin, 5-10wt% of diethylene glycol, 5-10wt% of acetaldehyde, and 10-15wt% of nano-ceramic particles are fully mixed to obtain a prefabricated material; the prefabricated material is heated and melted, extruded into a film, cured and formed, and mechanically pulled to obtain a current collector base film; The current collector base film is fixed, and a functional aluminum current collector is obtained by retracting and releasing the film, adjusting the tension, and evaporating metal aluminum.

2. The process for preparing a functional aluminum current collector with high tensile strength according to claim 1, characterized in that: In step 1, the diameters of the nano-alumina particles, nano-magnesium oxide particles, and nano-silicon dioxide particles are 10-20 nm; the hot pressing sintering parameters are: sintering pressure is 500-600 atm, sintering temperature is 2000-2200° C.; ball milling parameters are: rotation 700-800 r / min, revolution 350-400 r / min, and ball milling time is 8-10 h.

3. The process for preparing a functional aluminum current collector with high tensile strength according to claim 1, characterized in that: In step 2, the thickness of the current collector base film is 4-6 μm; the tension is adjusted to 120-130 N at the film unwinding end and 80-100 N at the winding end; during the evaporation of aluminum: the winding trolley with the current collector base film fixed is pushed into the evaporation chamber and then vacuumed to 4.5×10 -3 -5.0×10 -3 Pa, the temperature of the cooling roller is -20~-20℃, then the winding trolley is turned on, the speed is controlled at 8-10m / min, and at the same time, the evaporation boat is heated and the aluminum wire is fed, the wire feeding speed is 400-450mm / min, until the production is completed, and a functional aluminum current collector is obtained.

4. The process for preparing a functional aluminum current collector with high tensile strength according to claim 1, characterized in that: In step 2, the polyethylene terephthalate resin is modified to obtain an organosilicon-modified polyester resin, specifically: step S1: adding dimethyldimethoxysilane, methyltrimethoxysilane, catalyst hydrochloric acid solution, and silane coupling agent KH560 to a solvent, stirring and reacting at 75-85° C. for 7-9 hours, and after the reaction is completed, washing, dehydration, rotary evaporation, and oil bath decontamination are performed to obtain an organosilicon resin; Step S2: adding 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenylphosphine and silicone resin to toluene, reacting in a water bath at 55-75° C. for 4-6 hours to obtain a phosphorus-modified silicone resin; dissolving the phosphorus-modified silicone resin in anhydrous ethanol, dissolving 4-aminopyridine in anhydrous ethanol, and then fully mixing the two solutions, stirring and reacting at 65-75° C. for 7-8 hours, and cooling, filtering, washing and vacuum drying after the reaction to obtain a flame-retardant silicone resin; Step S3: heating and melting the polyethylene terephthalate resin at 270-300° C., adding the flame retardant silicone resin, and stirring and blending for 25-30 minutes to obtain the silicone-modified polyester resin.

5. The process for preparing a functional aluminum current collector with high tensile strength according to claim 4, characterized in that: In step S1, the solvent is obtained by mixing toluene and ethanol, and the mixing volume ratio is 1:1; the reaction mass ratio of dimethyldimethoxysilane, methyltrimethoxysilane, and silane coupling agent KH560 is 0.15:1:(2.0-2.5); The catalyst hydrochloric acid solution is 2.0-2.5wt% of the total mass of the reactants.

6. The process for preparing a functional aluminum current collector with high tensile strength according to claim 4, characterized in that: In step S2, when preparing the phosphorus-modified silicone resin, the reaction mass ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenylphosphine, and silicone resin is (5-7):1:25; when preparing the flame-retardant silicone resin, the reaction mass ratio of the modified silicone resin and 4-aminopyridine is 25:(4-6).

7. The process for preparing a functional aluminum current collector with high tensile strength according to claim 4, characterized in that: In step S3, the blending mass ratio of polyethylene terephthalate resin and flame retardant silicone resin is 5:(0.8-1.0).

8. The process for preparing a functional aluminum current collector with high tensile strength according to claim 1, characterized in that: In step 2, the nano-ceramic particles are modified and dispersed to obtain flame-retardant nano-ceramic particles, specifically: the nano-ceramic particles are ultrasonically dispersed in anhydrous ethanol, silane coupling agent KH550 is added dropwise under a nitrogen environment, and the reaction is stirred at 85-90° C. for 25-30 hours. After the reaction is completed, the particles are filtered, washed, and vacuum-dried to obtain amino-type nano-ceramic particles; the amino-type nano-ceramic particles and 4-formylphenylboric acid are dissolved in anhydrous methanol, and the reaction is stirred at 25-30° C. for 50-60 hours. After the reaction is completed, the particles are centrifuged, washed, and vacuum-dried to obtain flame-retardant nano-ceramic particles.

9. The process for preparing a functional aluminum current collector with high tensile strength according to claim 8, characterized in that: When preparing the aminated nano-ceramic particles, the mass volume ratio of the nano-ceramic particles and the silane coupling agent KH550 is 1:(10-12); when preparing the flame-retardant nano-ceramic particles, the reaction mass ratio of the aminated nano-ceramic particles and 4-formylphenylboric acid is (0.2-0.3):0.

6.

10. A functional aluminum current collector with high tensile strength, characterized in that: Prepared according to the preparation process according to any one of claims 1 to 9.

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