Preparation method and application of functionalized current collector for lithium iron phosphate battery

Abstract

The invention relates to the field of lithium iron phosphate batteries, and particularly discloses a preparation method and application of a functionalized current collector for a lithium iron phosphate battery, the preparation method of the functionalized current collector for the lithium iron phosphate battery comprises the following steps: S1, cleaning an aluminum foil, then carrying out plasma etching, then carrying out magnetron sputtering on the surface of the aluminum foil to form an aluminum-doped zinc oxide thin film, and carrying out vacuum drying on the aluminum foil to obtain the functionalized current collector for the lithium iron phosphate battery; carrying out nano dry etching and post-treatment to obtain a coated aluminum foil; and S2, uniformly coating the lithium iron phosphate composite slurry on the surface of the coated aluminum foil, drying and tabletting to obtain a finished product, the method has the advantages of high ion transmission efficiency and good transmission stability.

Description

TECHNICAL FIELD

[0001] The application relates to the field of lithium iron phosphate batteries, in particular to a functionalized current collector for a lithium iron phosphate battery and a preparation method and application thereof. BACKGROUND

[0002] The lithium iron phosphate battery is widely used in the new energy vehicle field due to its high safety, long cycle life and relatively low cost, and particularly in the commercial vehicle (such as a passenger vehicle and a logistics vehicle) market, the lithium iron phosphate battery occupies a dominant position. In the energy storage field, the lithium iron phosphate is also widely used in various scale energy storage projects, including household energy storage, industrial and commercial energy storage and large-scale power grid energy storage, due to its moderate energy density, long cycle life and good safety. In the power or energy storage field, the rate requirement for the lithium iron phosphate battery is also higher and higher, and the aluminum foil current collector, as a key part of the lithium iron phosphate battery, especially the functionalized current collector, can obviously improve the rate performance of the lithium iron phosphate battery.

[0003] At present, the lithium iron phosphate is an inorganic compound and has a high surface energy; the light aluminum foil has a smooth surface and is made of metal and has a relatively low surface energy. The surface energy difference between the two is large, so it is difficult to form a stable interface, and the contact area between the light aluminum foil and the lithium iron phosphate surface is very small, which cannot form a large-area adhesion, limits the interface transmission of ions and is not conducive to the improvement of the rate of the battery.

[0004] Therefore, it is an urgent problem to be solved to prepare a functionalized current collector for a lithium iron phosphate battery, which has a high ion transmission efficiency and good transmission stability and can ensure the rate of the battery. SUMMARY

[0005] In order to prepare a functionalized current collector for a lithium iron phosphate battery, which has a high ion transmission efficiency and good transmission stability and can ensure the rate of the battery, the application provides a preparation method and application of a functionalized current collector for a lithium iron phosphate battery.

[0006] In a first aspect, the application provides a preparation method of a functionalized current collector for a lithium iron phosphate battery, which adopts the following technical scheme: A preparation method of a functionalized current collector for a lithium iron phosphate battery, comprising the following steps: S1, the aluminum foil is subjected to cleaning treatment, then is subjected to plasma etching, then is subjected to surface magnetron sputtering of an aluminum-doped zinc oxide film, is subjected to nano dry etching, is subjected to post-treatment and a film-coated aluminum foil is obtained; S2, the film-coated aluminum foil is uniformly coated with a lithium iron phosphate composite slurry, is subjected to drying and tabletting and a finished product is obtained.

[0007] By adopting the above technical solution, the aluminum foil surface is cleaned to remove impurities and grease contamination. Then, plasma etching is used to form nanoscale etched pores on the aluminum foil surface, improving the surface roughness. Next, an aluminum-doped zinc oxide film is magnetron sputtered onto the aluminum foil surface, followed by subsequent nano-dry etching, resulting in a coated aluminum foil surface with good roughness and strong interfacial adhesion to the lithium iron phosphate slurry. The high conductivity and nanocrystalline structure of the aluminum-doped zinc oxide film, combined with its doping structure, introduces oxygen or zinc vacancies as lithium-ion transport channels, reducing the interfacial diffusion barrier and promoting lithium-ion transport. Furthermore, the high specific surface area and interfacial crystal network of the aluminum-doped zinc oxide film expand the contact area between the aluminum foil and lithium iron phosphate while improving conductivity, further promoting lithium-ion transport. Moreover, the aluminum-doped zinc oxide film exhibits high stability on the aluminum foil surface, ensuring the structural stability of the channels during lithium-ion migration and preventing channel collapse. Therefore, the finished product has the advantages of high ion transport efficiency and good transport stability.

[0008] Preferably, the specific steps of the aluminum foil cleaning process in S1 are as follows: first, clean with sodium hydroxide solution, then wash with water and dry.

[0009] By adopting the above technical solution, sodium hydroxide solution treatment of aluminum foil can remove oil and oxide films from the surface of aluminum foil, improve the surface cleanliness of aluminum foil, and alkaline washing can form micro-corrosion pits. Combined with subsequent plasma etching, it can further improve the surface roughness of aluminum foil, thereby improving the adhesion stability of magnetron sputtering film on the aluminum foil surface. Combined with the high stability of magnetron sputtering film material, lithium iron phosphate ion transport has high stability, and it is not easy to have pore collapse and blockage of transport, thus extending the service life of the finished product.

[0010] Preferably, the plasma etching specifically employs argon ion bombardment, with an average etching depth of 40-100 nm.

[0011] By adopting the above technical solution, argon ion bombardment can generate a nanoscale uneven structure on the surface of aluminum foil, enhance the bonding effect of the magnetron sputtering film, limit the etching depth, and ensure that the aluminum foil surface has nanoscale pores. At the same time, it can be combined with the micro-nano network of the magnetron sputtering film to further improve the transport effect of lithium iron phosphate ions, and also ensure the structural stability of the transport channel and extend the service life of the finished product.

[0012] Preferably, the aluminum-doped zinc oxide thin film in S1 is prepared using an aluminum-doped zinc oxide target. The preparation method of the aluminum-doped zinc oxide target is as follows: aluminum oxide and zinc oxide are mixed at a mass ratio of 1:2-5 to obtain a composite material, and the composite material is mixed with a polyethylene glycol solution at a mass ratio of 10:4-8. The mixture is then ball-milled, dried, and sintered to obtain the target material.

[0013] By adopting the above technical solution, alumina and zinc oxide are combined, and a target material is prepared using polyethylene glycol binder. The target material is sputtered onto the surface of aluminum foil to form a polycrystalline nano-network structure. The doping of alumina ensures the conductivity of the transport channel network, providing a fast channel for lithium-ion transport in lithium iron phosphate. Furthermore, the grain structure and orientation of the aluminum-doped zinc oxide film, combined with the oxygen vacancies introduced by the alumina doping, further promotes lithium-ion diffusion and transport. At the same time, the polycrystalline nano-network in the aluminum-doped zinc oxide, supported by zinc oxide, gives the ion transport channel good structural stability, making it less prone to channel collapse during transport, thus ensuring both transport efficiency and transport stability.

[0014] Preferably, the magnetron sputtering frequency of the S1 magnetron sputtering aluminum-doped zinc oxide thin film is 100-120W, and the sputtering gas pressure is 0.5-0.6Pa.

[0015] By adopting the above technical solution and limiting the frequency and gas pressure, the aluminum-doped zinc oxide thin film has a micro-nano porous network, which ensures the transport and migration of lithium ions. The network structure has good stability and is not prone to channel collapse during the migration process, thus ensuring the service life of the finished product.

[0016] Preferably, the post-processing steps are as follows: after nano-dry etching, a polyethylene glycol composite solution is uniformly sprayed onto the surface of the aluminum foil. The polyethylene glycol composite solution is composed of a polyethylene glycol ethanol solution, carbon nanotubes, and ammonium bicarbonate particles in a mass ratio of 10:0.5-1:1-1.5.

[0017] Preferably, the average particle size of the ammonium bicarbonate microparticles is 20-60 nm, and the average diameter of the carbon nanotubes is 2-8 nm.

[0018] By adopting the above technical solution, ammonium bicarbonate particles are insoluble in ethanol and are uniformly distributed on the surface of the coated aluminum foil. Carbon nanotubes utilize their length to form a bridging effect on the nanopores of the coated aluminum foil surface. However, the small diameter of the carbon nanotubes will not completely block the nanochannels on the surface of the coated aluminum foil. The nanochannels supply the migration and transport of lithium ions in lithium iron phosphate. Combined with the conductivity of carbon nanotubes and the conductivity of aluminum-doped zinc oxide film, the contact resistance between the current collector and the active material is reduced, and the electron transport efficiency is improved. Furthermore, the support of carbon nanotubes combined with the support of aluminum-doped zinc oxide further improves the structural stability of the transport channel, making it less prone to the problem of transport channel collapse and extending the service life of the finished product.

[0019] Polyethylene glycol ethanol solution can bond coated aluminum foil and lithium iron phosphate composite slurry. Ammonium bicarbonate can gradually decompose thermally during the subsequent drying process, realizing the permeability of the transport channels between graphite and aluminum foil in the lithium iron phosphate composite slurry, ensuring the efficient transport of lithium ions in lithium iron phosphate. When the position occupied by ammonium bicarbonate on the surface of the coated aluminum foil comes into contact with the lithium iron phosphate composite slurry, it can increase the contact area and improve the interfacial bonding force. During the drying process, the lithium iron phosphate composite slurry is prone to shrinkage, which can lead to the collapse of micropores. The presence of ammonium bicarbonate buffers the shrinkage while ensuring the existence of micropores, thereby further ensuring the transport efficiency and stability.

[0020] Preferably, the lithium iron phosphate composite slurry is made from lithium iron phosphate, conductive graphite, and polyvinylidene fluoride, with a mass ratio of lithium iron phosphate, conductive graphite, and polyvinylidene fluoride of 96-98:1-2:1-2.

[0021] By adopting the above technical solution, lithium iron phosphate, conductive graphite, and polyvinylidene fluoride are compounded to form a three-dimensional conductive network, which reduces the internal resistance of the electrode and improves the electron transport efficiency. Polyvinylidene fluoride acts as a binder to improve the interfacial bonding force, thereby further ensuring the lithium ion transport effect. Conductive graphite and aluminum foil surface construct lithium ion transport channels and transport routes to ensure the lithium ion transport and diffusion effect, thereby improving the ion transport efficiency of the finished product.

[0022] Preferably, the drying temperature is 100-120°C.

[0023] By adopting the above technical solution and limiting the drying temperature, not only can the drying of polyvinylidene fluoride be guaranteed, but also the thermal decomposition of ammonium bicarbonate can be guaranteed, ensuring the lithium-ion transport efficiency and the stability of the transport route, thus extending the service life of the finished product.

[0024] Secondly, this application provides an application of a functionalized current collector for lithium iron phosphate batteries, employing the following technical solution: An application of a functionalized current collector for lithium iron phosphate batteries, and a finished product prepared using a method for preparing a functionalized current collector for lithium iron phosphate batteries.

[0025] By adopting the above technical solutions, lithium iron phosphate batteries can improve battery conductivity and extend battery life by leveraging the high efficiency of lithium ion transport and the high stability of the transport channel.

[0026] In summary, this application has the following beneficial effects: 1. The aluminum foil surface is plasma etched, followed by magnetron sputtering of an aluminum-doped zinc oxide film. This is combined with subsequent nano-dry etching. Utilizing the high conductivity and nanocrystalline structure of the aluminum-doped zinc oxide film, and its doping structure which can introduce oxygen or zinc vacancies, it serves as a lithium-ion transport channel, reducing the interfacial diffusion barrier and promoting lithium-ion transport. Furthermore, the high specific surface area and interfacial crystal network of the aluminum-doped zinc oxide film expand the contact area between the aluminum foil and lithium iron phosphate while improving conductivity, further promoting lithium-ion transport. Moreover, the aluminum-doped zinc oxide film exhibits high stability on the aluminum foil surface. The migration of lithium ions in the transport channel ensures the structural stability of the channel, making it less prone to channel collapse. As a result, the finished product has the advantages of high ion transport efficiency and good transport stability.

[0027] 2. Alumina and zinc oxide are combined, and a target material is prepared using polyethylene glycol as a binder. The target material is sputtered onto the surface of aluminum foil to form a polycrystalline nano-network structure. The doping of alumina ensures the conductivity of the transport channel network, providing a fast channel for lithium-ion transport in lithium iron phosphate. Furthermore, the grain structure and orientation of the aluminum-doped zinc oxide film, combined with the oxygen vacancies introduced by the alumina doping, further promotes lithium-ion diffusion and transport. At the same time, the polycrystalline nano-network in the aluminum-doped zinc oxide, supported by zinc oxide, gives the ion transport channel good structural stability, making it less prone to channel collapse during transport, thus ensuring both transport efficiency and stability.

[0028] 3. In the polyethylene glycol composite solution, the polyethylene glycol ethanol solution can bond the coated aluminum foil and the lithium iron phosphate composite slurry. Ammonium bicarbonate gradually decomposes during the subsequent drying process, ensuring the permeability of the transport channels between the graphite and aluminum foil in the lithium iron phosphate composite slurry, thus guaranteeing efficient lithium ion transport. When the ammonium bicarbonate on the surface of the coated aluminum foil comes into contact with the lithium iron phosphate composite slurry, it increases the contact area and improves the interfacial bonding. During the drying process, the lithium iron phosphate composite slurry is prone to shrinkage, leading to micropore collapse. The ammonium bicarbonate's occupancy buffers this shrinkage while preserving the micropores, further ensuring transport efficiency and stability. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the embodiments.

[0030] Preparation example of aluminum-doped zinc oxide target All of the following ingredients are commercially available.

[0031] Preparation Example 1: Aluminum-doped zinc oxide target material was prepared using the following method: Alumina with a purity of 99.99% and zinc oxide with a purity of 99.99% were mixed evenly at a mass ratio of 1:4 to obtain a composite material. Then, the composite material was mixed with a polyethylene glycol solution at a mass ratio of 10:6. After ball milling for 5 hours and drying, the mixture was vacuum hot-pressed and sintered at 1300℃ to obtain the target material. The polyethylene glycol solution was a 5% (w / w) aqueous solution of polyethylene glycol, and the polyethylene glycol was polyethylene glycol 8000.

[0032] Preparation Example 2: The difference between this preparation example and Preparation Example 1 is that: Alumina with a purity of 99.99% and zinc oxide with a purity of 99.99% were mixed evenly at a mass ratio of 1:2 to obtain a composite material. Then, the composite material was mixed with polyethylene glycol solution at a mass ratio of 10:4. After ball milling for 5 hours and drying, the mixture was vacuum hot-pressed and sintered at 1300℃ to obtain the target material.

[0033] Preparation Example 3: The difference between this preparation example and Preparation Example 1 is that: Alumina with a purity of 99.99% and zinc oxide with a purity of 99.99% were mixed evenly at a mass ratio of 1:5 to obtain a composite material. Then, the composite material was mixed with polyethylene glycol solution at a mass ratio of 10:8. After ball milling for 5 hours and drying, the mixture was vacuum hot-pressed and sintered at 1300℃ to obtain the target material.

[0034] Example of preparation of lithium iron phosphate composite slurry All of the following ingredients are commercially available.

[0035] Preparation Example 4: Lithium iron phosphate composite slurry was prepared using the following method: Polyvinylidene fluoride was placed in NMP solvent and mechanically stirred for 5 hours until completely dissolved, resulting in a polyvinylidene fluoride solution with a solid content of 10%. Lithium iron phosphate and conductive graphite were added to a polyvinylidene fluoride solution and mixed evenly, wherein lithium iron phosphate accounted for 97%, conductive graphite for 1.5%, and polyvinylidene fluoride for 1.5%, to obtain the finished slurry.

[0036] Preparation Example 5: The difference between this preparation example and Preparation Example 4 is that: Polyvinylidene fluoride was placed in NMP solvent and mechanically stirred for 5 hours until completely dissolved, resulting in a polyvinylidene fluoride solution with a solid content of 10%. Lithium iron phosphate and conductive graphite were added to a polyvinylidene fluoride solution and mixed evenly, wherein the composition was 96% lithium iron phosphate, 2% conductive graphite, and 2% polyvinylidene fluoride, to obtain the finished slurry.

[0037] Preparation Example 6: The difference between this preparation example and Preparation Example 4 is that: Polyvinylidene fluoride was placed in NMP solvent and mechanically stirred for 5 hours until completely dissolved, resulting in a polyvinylidene fluoride solution with a solid content of 10%. Lithium iron phosphate and conductive graphite were added to a polyvinylidene fluoride solution and mixed evenly, wherein the composition was 98% lithium iron phosphate, 1% conductive graphite, and 1% polyvinylidene fluoride, to obtain the finished slurry.

[0038] Preparation example of polyethylene glycol composite liquid All of the following ingredients are commercially available.

[0039] Preparation Example 7: The polyethylene glycol composite liquid was prepared by the following method: 10 kg of polyethylene glycol ethanol solution, 0.8 kg of carbon nanotubes and 1.2 kg of ammonium bicarbonate microparticles were mixed and stirred evenly to obtain a polyethylene glycol composite solution; the mass fraction of the polyethylene glycol ethanol solution was 5%, the polyethylene glycol was polyethylene glycol 800, the average diameter of the carbon nanotubes was 5 nm, and the average particle size of the ammonium bicarbonate microparticles was 40 nm.

[0040] Preparation Example 8: The difference between this preparation example and Preparation Example 7 is that: 10 kg of polyethylene glycol ethanol solution, 0.5 kg of carbon nanotubes and 1 kg of ammonium bicarbonate microparticles were mixed and stirred evenly to obtain a polyethylene glycol composite solution. The average diameter of the carbon nanotubes was 2 nm and the average particle size of the ammonium bicarbonate microparticles was 20 nm.

[0041] Preparation Example 9: The difference between this preparation example and Preparation Example 7 is that: 10 kg of polyethylene glycol ethanol solution, 1 kg of carbon nanotubes and 1.5 kg of ammonium bicarbonate microparticles were mixed and stirred evenly to obtain a polyethylene glycol composite solution. The average particle size of the carbon nanotubes was 8 nm and the average particle size of the ammonium bicarbonate microparticles was 60 nm. Example

[0042] All of the following ingredients are commercially available.

[0043] Example 1: A method for preparing a functionalized current collector for lithium iron phosphate batteries: S1. The aluminum foil was cleaned with a 5% sodium hydroxide solution for 2 minutes, then washed twice with water, dried, and then subjected to plasma etching using argon ion bombardment, with an average etching depth of 80 nm. Aluminum-doped zinc oxide film was then magnetron sputtered onto the surface. The target material used in Preparation Example 1 was aluminum-doped zinc oxide. The magnetron sputtering frequency was 110 W, the sputtering gas was argon, and the sputtering pressure was 0.5 Pa. The average thickness of the aluminum-doped zinc oxide film was 50 nm. Nano-dry etching was then performed, with an average etching depth of 5 nm. After nano-dry etching, the surface of the aluminum foil was uniformly sprayed with polyethylene glycol composite solution prepared in Preparation Example 7, using 20 mL of polyethylene glycol composite solution per square meter of aluminum foil surface. This post-treatment yielded a coated aluminum foil. S2. Coating the surface of the coated aluminum foil with the lithium iron phosphate composite slurry prepared in Example 4, with a coating amount of 240 g / m². 2The product is dried at 110℃ for 20 minutes and then compressed into tablets to obtain the finished product.

[0044] Example 2: The difference between this example and Example 1 is that: S1. The aluminum foil was cleaned with a 5% sodium hydroxide solution for 2 minutes, then washed twice with water, dried, and then subjected to plasma etching by argon ion bombardment, with an average etching depth of 40 nm. Then, an aluminum-doped zinc oxide film was sputtered onto the surface using the aluminum-doped zinc oxide target prepared in Preparation Example 2. The magnetron sputtering frequency was 100 W, the sputtering gas was argon, and the sputtering pressure was 0.6 Pa. The average thickness of the aluminum-doped zinc oxide film was 20 nm. After nano-dry etching, the average depth of the nano-dry etching was 5 nm. After nano-dry etching, the surface of the aluminum foil was uniformly sprayed with polyethylene glycol composite liquid prepared in Preparation Example 8, with 20 mL of polyethylene glycol composite liquid per square meter of aluminum foil surface. After post-treatment, the coated aluminum foil was obtained. S2. Coating the surface of the coated aluminum foil with the lithium iron phosphate composite slurry prepared in Example 5, with a coating amount of 240 g / m². 2 The product is dried at 100℃ for 30 minutes and then compressed into tablets to obtain the finished product.

[0045] Example 3: The difference between this example and Example 1 is that: S1. The aluminum foil was cleaned with a 5% sodium hydroxide solution for 2 minutes, then washed twice with water, dried, and then subjected to plasma etching by argon ion bombardment, with an average etching depth of 100 nm. Then, an aluminum-doped zinc oxide film was sputtered onto the surface using the aluminum-doped zinc oxide target prepared in Preparation Example 3. The magnetron sputtering frequency was 120 W, the sputtering gas was argon, the sputtering pressure was 0.5 A, and the average thickness of the aluminum-doped zinc oxide film was 60 nm. After nano-dry etching, the average depth of the nano-dry etching was 8 nm. After nano-dry etching, the surface of the aluminum foil was uniformly sprayed with polyethylene glycol composite liquid prepared in Preparation Example 9, with 20 mL of polyethylene glycol composite liquid per square meter of aluminum foil surface. After post-treatment, the coated aluminum foil was obtained. S2. Coating the surface of the coated aluminum foil with the lithium iron phosphate composite slurry prepared in Example 6, with a coating amount of 240 g / m². 2 The product is dried at 120℃ for 20 minutes and then compressed into tablets to obtain the finished product.

[0046] Example 4: The difference between this example and Example 1 is that: In the post-processing, the ammonium bicarbonate particles were replaced with an equal mass of polyethylene glycol ethanol solution.

[0047] Example 5: The difference between this example and Example 1 is that: In the post-processing, the carbon nanotubes were replaced with an equal mass of polyethylene glycol ethanol solution.

[0048] Application examples Application Examples 1-5: Application of a functionalized current collector for lithium iron phosphate batteries: The application of the finished functional current collectors from any of Examples 1-5 is described.

[0049] Comparative Example Comparative Example 1: The difference between this comparative example and Example 1 is that: In S1, the magnetron sputtered zinc oxide film replaces the magnetron sputtered aluminum-doped zinc oxide film; the target material preparation method for the zinc oxide film is as follows: 10 kg of zinc oxide with a purity of 99.99% is mixed with 8 kg of polyethylene glycol solution, ball-milled for 5 h, dried, and then vacuum hot-pressed and sintered at 1300℃ to obtain the target material; the polyethylene glycol solution is a 5% (w / w) polyethylene glycol aqueous solution, and the polyethylene glycol is polyethylene glycol 8000.

[0050] Comparative Example 2: This comparative example differs from Example 1 in that: The aluminum foil surface was not coated with an aluminum-doped zinc oxide film by magnetron sputtering.

[0051] Comparative Example 3: This comparative example differs from Example 1 in that: S1 was not subjected to nano-dry etching.

[0052] Performance testing 1. Transmission efficiency detection Finished current collectors were prepared using the methods of Examples 1-5 and Comparative Examples 1-3, respectively. The 1C capacity was tested and the data was recorded. The 50% internal resistance data of the AC internal resistance was also tested. Resistance and power were measured under discharge conditions of -50% SOC - 10C 2.0-3.65V, and under charge-discharge conditions of -50% SOC - 10C 2.0-3.65V, and the data were recorded.

[0053] 2. Transmission stability detection Finished current collectors were prepared using the methods of Examples 1-5 and Comparative Examples 1-3, respectively. Under the initial condition of 1C capacity, the current collectors were rotated 0.5 times per hour, and the capacity retention data were recorded after 400 rotations. The novel current collector structure was prepared using Example 1, and commercially available carbon-coated aluminum foil (purchased from Guangzhou Nano New Material Technology Co., Ltd.) was used as a control group. The capacity retention data under room temperature cycling were recorded.

[0054] Performance Test Table Combining Examples 1-3 and the control group with Table 1, it can be seen that the novel current collector prepared in this application has a higher 1C capacity and lower internal resistance compared to commercially available carbon-coated aluminum foil. It exhibits lower resistance and higher power during charging and discharging, indicating that the battery requires a higher current during charging and discharging to promote the rapid migration of lithium ions in the lithium iron phosphate crystal structure. Combined with the electron conductivity of the aluminum foil surface, this reduces resistance and increases conductivity, giving the finished current collector the advantage of high ion transport efficiency. Furthermore, the capacity retention rate of Example 1 is higher than that of commercially available carbon-coated aluminum foil, indicating that it still has high transport efficiency after long-term operation. The transport channel structure on the finished current collector has good stability and is less prone to pore collapse, thus extending the service life of the current collector.

[0055] Combining Examples 1 and 4-5 with Table 1, it can be seen that in the post-processing of Example 4, when the ammonium bicarbonate microparticles were replaced with the same mass of polyethylene glycol ethanol solution, the current collector prepared in Example 4 had a lower 1C capacity, higher internal resistance, higher charging and discharging resistance, lower charging and discharging power, and lower capacity retention rate compared to Example 1. This indicates that the ammonium bicarbonate microparticles decompose and produce gas during drying, and the ammonium bicarbonate microparticles, while acting as a buffer for the shrinkage of lithium iron phosphate, ensure the existence of microporous channels on the current collector, thereby further guaranteeing transmission efficiency and transmission stability.

[0056] In the post-processing of Example 5, carbon nanotubes were replaced with an equal mass of polyethylene glycol ethanol solution. Compared to Example 1, the current collector prepared in Example 5 had a lower 1C capacity, higher internal resistance, higher charging and discharging resistance, lower charging and discharging power, and lower capacity retention rate. This indicates that carbon nanotubes utilize their length to form a bridge support effect on the nanoporous surface of the coated aluminum foil. However, the small diameter of the carbon nanotubes does not completely block the nanochannels on the surface of the coated aluminum foil. The nanochannels supply the migration and transport of lithium ions in lithium iron phosphate. Combined with the conductivity of carbon nanotubes and the conductivity of the aluminum-doped zinc oxide film, the contact resistance between the current collector and the active material is reduced, improving electron transport efficiency. Furthermore, the support of carbon nanotubes and aluminum-doped zinc oxide further improves the structural stability of the transport channels, making it less prone to collapse and extending the service life of the finished product.

[0057] Combining Example 1 and Comparative Examples 1-3 with Table 1, it can be seen that, compared to Example 1, when the magnetron sputtered zinc oxide film replaced the magnetron sputtered aluminum-doped zinc oxide film, the current collector 1C capacity prepared in Comparative Example 1 was lower than that of Example 1, the internal resistance was higher, the charging and discharging resistance was higher, the charging and discharging power was lower, and the capacity retention rate was lower. This indicates that aluminum doping can improve the conductivity of the zinc oxide film, and the doping structure can introduce oxygen vacancies or zinc vacancies as lithium-ion transport channels, reduce the interface diffusion barrier, promote lithium-ion transport, and maintain the stability of the transport structure.

[0058] In Comparative Example 2, the aluminum foil surface was not coated with an aluminum-doped zinc oxide film by magnetron sputtering. Compared to Example 1, the current collector prepared in Comparative Example 2 had a lower 1C capacity, higher internal resistance, higher resistance during charging and discharging, lower power during charging and discharging, and lower capacity retention rate. This indicates that the high specific surface area and interfacial crystal network of the aluminum-doped zinc oxide film expand the contact area between the aluminum foil and lithium iron phosphate while improving conductivity, further promoting lithium-ion transport. Furthermore, the aluminum-doped zinc oxide film exhibits high stability on the aluminum foil surface, ensuring the structural stability of the transport channels during lithium-ion migration and preventing channel collapse. As a result, the finished product has the advantages of high ion transport efficiency and good transport stability.

[0059] Compared to Example 1, Comparative Example 3S1, which did not undergo nano-dry etching, had a lower current collector capacity, higher internal resistance, higher charging / discharging resistance, lower charging / discharging power, and lower capacity retention rate than Example 1. This indicates that nano-dry etching gives the coated aluminum foil a better surface roughness, enabling it to have better interfacial bonding with the lithium iron phosphate slurry. Furthermore, the pore channels promote lithium-ion transport, resulting in a new structure current collector with high ion transport efficiency and good transport stability.

[0060] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a functionalized current collector for lithium iron phosphate batteries, characterized in that, Includes the following steps: S1. The aluminum foil is cleaned, then plasma etched, and then an aluminum-doped zinc oxide film is sputtered onto the surface by magnetron sputtering. After nano-dry etching and post-treatment, a coated aluminum foil is obtained. S2. The surface of the coated aluminum foil is uniformly coated with lithium iron phosphate composite slurry, and after drying and pressing, the finished product is obtained.

2. The method for preparing a functionalized current collector for lithium iron phosphate batteries according to claim 1, characterized in that: The specific steps for cleaning the aluminum foil in S1 are as follows: first, clean with sodium hydroxide solution, then wash with water and dry.

3. The method for preparing a functionalized current collector for lithium iron phosphate batteries according to claim 1, characterized in that: The plasma etching specifically employs argon ion bombardment, with an average etching depth of 40-100 nm.

4. The method for preparing a functionalized current collector for lithium iron phosphate batteries according to claim 1, characterized in that, The aluminum-doped zinc oxide thin film in S1 is prepared using an aluminum-doped zinc oxide target. The preparation method of the aluminum-doped zinc oxide target is as follows: aluminum oxide and zinc oxide are mixed at a mass ratio of 1:2-5 to obtain a composite material. The composite material is then mixed with a polyethylene glycol solution at a mass ratio of 10:4-8, followed by ball milling, drying, and sintering to obtain the target material.

5. The method for preparing a functionalized current collector for lithium iron phosphate batteries according to claim 1, characterized in that, The magnetron sputtering frequency of the S1 aluminum-doped zinc oxide thin film is 100-120W, and the sputtering pressure is 0.5-0.6Pa.

6. The method for preparing a functionalized current collector for lithium iron phosphate batteries according to claim 1, characterized in that: The specific post-processing steps are as follows: After nano-dry etching, a polyethylene glycol composite solution is uniformly sprayed onto the surface of the aluminum foil. The polyethylene glycol composite solution is composed of a polyethylene glycol ethanol solution, carbon nanotubes, and ammonium bicarbonate particles in a mass ratio of 10:0.5-1:1-1.

5.

7. The method for preparing a functionalized current collector for a lithium iron phosphate battery according to claim 6, characterized in that: The average particle size of the ammonium bicarbonate microparticles is 20-60 nm, and the average diameter of the carbon nanotubes is 2-8 nm.

8. The method for preparing a functionalized current collector for lithium iron phosphate batteries according to claim 1, characterized in that, The lithium iron phosphate composite slurry is made from lithium iron phosphate, conductive graphite, and polyvinylidene fluoride, with a mass ratio of lithium iron phosphate, conductive graphite, and polyvinylidene fluoride of 96-98:1-2:1-2.

9. The method for preparing a functionalized current collector for a lithium iron phosphate battery according to claim 1, characterized in that, The drying temperature is 100-120℃.

10. An application of a functionalized current collector for lithium iron phosphate batteries, characterized in that, The finished product is prepared by any one of the functionalized current collectors for lithium iron phosphate batteries according to any one of claims 1-9.

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