Preparation method for positive electrode material, positive electrode material and battery

Abstract

The present application provides a preparation method for a positive electrode material, a positive electrode material and a battery. The preparation method comprises: placing a positive electrode material matrix into a reaction cavity of an atomic layer deposition system, and introducing a low-temperature superconducting nano material precursor into the reaction cavity to perform atomic layer deposition, thereby forming a low-temperature superconducting nano coating layer on the surface of the positive electrode material matrix. In the present application, an atomic layer deposition technology is used to coat the outer surface of a carbon-coated positive electrode material matrix, so as to form a compact nano-superconductive low-temperature superconductive nano coating layer, thereby solving the problem of poor low-temperature performance of an existing positive electrode material.

Description

A method for preparing positive electrode material, positive electrode material and battery

[0001] This application claims priority to an invention patent application filed on September 26, 2023, with application number 202311252438.4, entitled “A method for preparing a positive electrode material, a positive electrode material and a battery”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the technical field of battery preparation, for example, a method for preparing a positive electrode material, a positive electrode material and a battery. Background Art

[0003] Lithium-ion batteries offer advantages such as low cost, stable charge and discharge, environmental friendliness, and high safety. They are widely used in battery-powered electronic devices such as mobile phones, laptops, and electric vehicles. Lithium-ion batteries typically use a carbon material as the negative electrode and a lithium-containing compound as the positive electrode, achieving charge and discharge through the intercalation and deintercalation of lithium ions. As the performance requirements for lithium-ion batteries continue to increase, research on positive electrode materials has become a key factor restricting the overall performance of lithium-ion batteries.

[0004] CN116692819A discloses a high-density cathode material with a nanoporous structure and a preparation method thereof. A phosphorus source, a lithium source, an iron source, a soluble carbon source, and a pore-forming agent are mixed and spray-dried to obtain lithium iron phosphate intermediate mixed particles. The lithium iron phosphate intermediate mixed particles are then sintered in an inert gas to obtain a lithium iron phosphate cathode material. This allows more lithium ions within the particles to be more quickly and effectively embedded and released, thereby improving its electrochemical performance. CN110416506A discloses a method for preparing a modified cathode material. Using electron beam evaporation, a GeSbTe film is grown on a carbon-coated lithium iron phosphate film. After annealing, a modified lithium iron phosphate cathode material, namely a GeSbTe-modified carbon-coated lithium iron phosphate film, is obtained. The modified lithium iron phosphate cathode material exhibits higher electrochemical activity, reduces electrode polarization, and improves the rate performance and high-rate cycling performance of the lithium iron phosphate.

[0005] However, the poor low-temperature performance of lithium-ion batteries has always been a problem that needs to be urgently solved in the industry. Batteries made of lithium iron phosphate have high DCR (DC internal resistance) and low discharge capacity at low temperatures, which in turn affects the use of batteries in winter, especially in northern regions.

[0006] Summary of the Invention

[0007] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0008] The present application provides a method for preparing a positive electrode material, a positive electrode material and a battery, which uses atomic layer deposition technology to coat a dense nano-superconducting low-temperature superconducting nano-coating layer on the outer surface of a carbon-coated positive electrode material substrate, thereby improving the conductivity of the positive electrode material at low temperatures and solving the problem of poor low-temperature performance of existing lithium iron phosphate positive electrode materials.

[0009] In a first aspect, the present application provides a method for preparing a positive electrode material, the preparation method comprising:

[0010] The cathode material substrate is placed in a reaction chamber of an atomic layer deposition system, and a low-temperature superconducting nanomaterial precursor is simultaneously introduced into the reaction chamber for atomic layer deposition to form a low-temperature superconducting nano-coating layer on the surface of the cathode material substrate.

[0011] This application uses atomic layer deposition technology to deposit a low-temperature superconducting nanomaterial precursor on the surface of the positive electrode material matrix to form a dense superconducting network on the outer surface of the positive electrode material matrix, effectively avoiding the problem of conductivity degradation or even loss of conductivity of the material under low temperature conditions, so that the positive electrode material can still maintain a high capacity even at low temperatures, reducing the discharge DCR.

[0012] The low-temperature superconducting nanomaterial precursor described in this application refers to a material with a low critical transition temperature and exhibits properties such as "zero resistance and anti-magnetism" under low temperature conditions. It is usually divided into elemental metal superconducting materials, alloy superconducting materials and compound superconducting materials.

[0013] As an optional technical solution of the present application, the mass ratio of the low-temperature superconducting nanomaterial precursor to the positive electrode material matrix is ​​(0.1~1):100, for example, it can be 0.1:100, 0.15:100, 0.2:100, 0.25:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100 or 1:100, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0014] As an optional technical solution of the present application, the positive electrode material matrix is ​​a carbon-coated positive electrode material matrix.

[0015] In one embodiment, the carbon-coated positive electrode material matrix includes any one of a carbon-coated lithium iron phosphate matrix, a carbon-coated lithium iron vanadium phosphate matrix, a carbon-coated lithium manganese iron phosphate matrix, a carbon-coated lithium ferrous manganese phosphate matrix, and a carbon-coated lithium iron sulfate matrix.

[0016] In one embodiment, the carbon content in the carbon-coated positive electrode material matrix is ​​0.6-1%, for example, it can be 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95% or 1%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0017] In one embodiment, the specific surface area of ​​the carbon-coated positive electrode material matrix is ​​9 to 15 m 2 / g, for example, it can be 9m 2 / g, 9.5m 2 / g、10m 2 / g, 10.6m 2 / g、11m 2 / g, 11.5m 2 / g、12m 2 / g, 12.5m 2 / g、13m 2 / g, 13.5m 2 / g、14m 2 / g, 14.5m 2 / g or 15m 2 / g, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] In one embodiment, the particle size D of the carbon-coated positive electrode material matrix is 50 It is 0.8 to 1.5 μm, for example, it can be 0.8 μm, 0.85 μm, 0.9 μm, 0.95 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.25 μm, 1.3 μm, 1.4 μm, 1.45 μm or 1.5 μm, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] It should be noted that D 50 It refers to the particle size corresponding to when the cumulative particle size distribution percentage of the carbon-coated positive electrode material matrix reaches 50%.

[0020] In one embodiment, the compaction density of the carbon-coated positive electrode material matrix is ​​2.3 to 2.5 g / cm 3 , for example, it can be 2.3g / cm 3 , 2.32g / cm 3 , 2.35g / cm 3 , 2.36g / cm 3 , 2.38g / cm 3 , 2.4g / cm 3 , 2.43g / cm 3 , 2.45g / cm3 , 2.48g / cm 3 or 2.5g / cm 3 , but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] It should be noted that the compaction density described in this application is the compaction density of the sample to be tested measured using a compaction density meter with the pressure unit adjusted to 2 tons.

[0022] The preparation method of the carbon-coated positive electrode material matrix described in this application includes:

[0023] The positive electrode active material, lithium source, solvent and carbon source are mixed and dried, and then calcined under an inert atmosphere to obtain a carbon-coated lithium iron phosphate material.

[0024] It should be noted that the carbon-coated positive electrode material used in this application ensures the conductive performance of the positive electrode material matrix at room temperature. The positive electrode active material includes, but is not limited to, at least one of ferric phosphate, manganese carbonate, vanadium pentoxide, ferrous manganese phosphate, and ferric sulfate; the lithium source includes, but is not limited to, at least one of lithium hydroxide, lithium carbonate, and lithium acetate; and the solvent includes, but is not limited to, at least one of deionized water, ethanol, and ethylene glycol. The carbon source includes, but is not limited to, at least one of citric acid, glucose, and sucrose.

[0025] As an optional technical solution of the present application, the low-temperature superconducting nanomaterial precursor includes at least two metal precursors.

[0026] In one embodiment, at least two metal precursors are introduced into the reaction chamber simultaneously.

[0027] In one embodiment, the metal precursor includes at least one of a niobium metal precursor, a titanium metal precursor, an aluminum metal precursor, a tin metal precursor, a zirconium metal precursor, a vanadium metal precursor, and a gallium metal precursor.

[0028] In the present application, two metal precursors are simultaneously introduced into the reaction chamber for atomic layer deposition, wherein typical but non-limiting combinations are: a combination of a niobium metal precursor and a titanium metal precursor, a combination of a niobium metal precursor and an aluminum metal precursor, a combination of a niobium metal precursor and a tin metal precursor, a combination of a titanium metal precursor and an aluminum metal precursor, a combination of a niobium metal precursor and a zirconium metal precursor, a combination of a niobium metal precursor and a gallium metal precursor, a combination of a titanium metal precursor and a zirconium metal precursor, a combination of an aluminum metal precursor and a zirconium metal precursor, a combination of a niobium metal precursor, a titanium metal precursor and an aluminum metal precursor, or a combination of a niobium metal precursor, a zirconium metal precursor and an aluminum metal precursor, and the like.

[0029] It should be noted that niobium exhibits superconducting properties at low temperatures, which is the highest among all metals with superconducting properties. It also has high stability and corrosion resistance at room temperature and can form alloys with titanium, aluminum, tin, zirconium, vanadium, and gallium at high temperatures. It can be used as one of the metal precursors for preparing low-temperature superconducting nano-coatings, effectively improving the low-temperature performance of the positive electrode material. The molar ratio of the niobium metal precursor to other metal sources in the low-temperature superconducting nano-coating is 1:(1 to 3).

[0030] In one embodiment, the metal precursor includes at least one of pentakis(dimethylamino)niobium, trimethyl(pentamethylcyclopentadienyl)titanium, trimethylaluminum, trimethyl(phenylethynyl)tin, dimethylbis(cyclopentadienyl)zirconium, bis(ethylcyclopentyl)vanadium, and triethylgallium.

[0031] It should be noted that the above-mentioned metal precursor used in the present application not only contains metal elements and can interact with other metal precursors to form a superconducting alloy structure, but can also supplement carbon elements for the positive electrode material.

[0032] As an optional technical solution of the present application, the temperature of the reaction chamber is 300-500°C, for example, it can be 300°C, 320°C, 350°C, 380°C, 400°C, 420°C, 430°C, 450°C, 480°C, 490°C or 500°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0033] By controlling the temperature in the reaction chamber within the above range, the present application can, on the one hand, avoid the increase in carbon loss due to excessively high temperature, thereby reducing the conductivity of the positive electrode material; on the other hand, it can also ensure the reaction between different metals to form an alloy structure to achieve a superconducting effect.

[0034] In one embodiment, the pressure of the reaction chamber is 5 to 8 mbar, for example, 5 mbar, 5.2 mbar, 5.4 mbar, 5.5 mbar, 5.8 mbar, 6 mbar, 6.3 mbar, 6.5 mbar, 6.8 mbar, 7 mbar, 7.2 mbar, 7.5 mbar, 7.6 mbar, 7.8 mbar or 8 mbar, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] As an optional technical solution of the present application, the preparation method further includes: introducing an inert gas into the reaction chamber for flushing.

[0036] In one embodiment, the inert gas and the low-temperature superconducting nanomaterial precursor are simultaneously introduced into the reaction chamber for flushing.

[0037] In the present application, an inert gas is introduced into the reaction chamber to remove unreacted low-temperature superconducting nanomaterial precursors and reaction byproducts in the reaction chamber.

[0038] In one embodiment, the inert gas comprises nitrogen or argon.

[0039] In a second aspect, the present application provides a positive electrode material, which is prepared using the preparation method described in the first aspect. The positive electrode material includes a positive electrode material matrix and a low-temperature superconducting nano-coating layer coated on the outer surface of the positive electrode material matrix.

[0040] As an optional technical solution of the present application, a carbon coating layer is further provided between the positive electrode material matrix and the low-temperature superconducting nano-coating layer.

[0041] In one embodiment, the thickness of the low-temperature superconducting nano-coating layer is 10 to 30 nm, for example, it can be 10 nm, 12 nm, 14 nm, 15 nm, 16 nm, 18 nm, 20 nm, 22 nm, 25 nm, 26 nm, 28 nm or 30 nm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0042] In one embodiment, the low-temperature superconducting nano-cladding layer includes at least one of NbTi, Nb3Al, Nb3Sn, Nb3Zr, NbV and GaNb.

[0043] In a third aspect, the present application provides a battery comprising a positive electrode plate and a negative electrode plate, wherein the positive electrode plate comprises a positive electrode collector, and positive electrode active layers are respectively provided on both side surfaces of the positive electrode collector, and the positive electrode active layers comprise the positive electrode material described in the second aspect.

[0044] As an optional technical solution of this application, the compaction density of the positive electrode sheet is ≥2.55g / cm 3 .

[0045] In one embodiment, the positive electrode active layer further includes a positive electrode conductor, conductive carbon black and a positive electrode binder. The total mass of the positive electrode material, the positive electrode conductor, the conductive carbon black and the positive electrode binder is counted as 100%, and the mass proportion of the positive electrode material is 96-97%, for example, it can be 96%, 96.1%, 96.2%, 96.3%, 96.4%, 96.5%, 96.6%, 96.7%, 96.8%, 96.9% or 97%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] In one embodiment, the positive electrode current collector comprises aluminum foil.

[0047] It should be noted that the present application may also provide a carbon coating between the positive electrode current collector and the positive electrode active layer to improve the conductivity of the material, that is, the aluminum foil of the positive electrode current collector in the present application may also adopt commercially available carbon-coated aluminum foil, and the present application does not make specific limitations on this.

[0048] In one embodiment, the thickness of the positive electrode current collector is 8 to 14 μm, for example, it can be 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm or 14 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] It should be noted that the present application does not specifically limit the positive electrode conductive agent, and any conductive agent known to those skilled in the art for preparing battery positive electrode sheets may be used, such as carbon nanotubes or graphene.

[0050] In one embodiment, the positive electrode binder includes but is not limited to one or a combination of at least one of polyvinylidene fluoride, polyethylene oxide, and polyvinylidene fluoride-hexafluoropropylene.

[0051] In one embodiment, the negative electrode plate includes a negative electrode current collector, and both sides of the negative electrode current collector are coated with a negative electrode active layer.

[0052] In one embodiment, the compaction density of the negative electrode sheet is 1.4 to 1.45 g / cm 3 , for example, it can be 1.4 g / cm 3 , 1.41g / cm 3 , 1.415g / cm 3 , 1.42g / cm 3 , 1.425g / cm 3 , 1.43g / cm 3 , 1.435g / cm 3 , 1.44g / cm 3 , 1.445g / cm 3 or 1.45g / cm 3 , but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] In one embodiment, the negative electrode current collector comprises copper foil.

[0054] In one embodiment, the thickness of the negative electrode current collector is 4 to 8 μm, for example, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm or 8 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] In one embodiment, the negative electrode active layer includes a negative electrode conductive agent, conductive carbon black, sodium carboxymethyl cellulose and a negative electrode binder.

[0056] It should be noted that the present application does not specifically limit the negative electrode conductive agent, and any conductive agent known to those skilled in the art for preparing battery negative electrode sheets may be used, such as carbon nanotubes or graphene.

[0057] In one embodiment, the negative electrode binder includes but is not limited to a styrene-butadiene rubber binder or a polyacrylate aqueous binder.

[0058] In order to help those skilled in the art better understand the overall technical solution and working process of this application, this application exemplarily provides a specific method for preparing a battery, including:

[0059] (1) mixing a lithium iron phosphate positive electrode material, a positive electrode conductive agent, conductive carbon black, a positive electrode binder, and a first solvent in a proportion to obtain a positive electrode slurry; and mixing a negative electrode conductive agent, conductive carbon black, sodium carboxymethyl cellulose, a negative electrode binder, and a second solvent in a proportion to obtain a negative electrode slurry;

[0060] (2) providing a positive electrode current collector, dividing the positive electrode slurry into two parts, coating one part of the positive electrode slurry on one side of the positive electrode current collector and drying it, coating the other part of the positive electrode slurry on the other side of the positive electrode current collector and drying it, and then rolling it to obtain a positive electrode sheet;

[0061] (3) providing a negative electrode current collector, dividing the negative electrode slurry into two parts, coating one part of the negative electrode slurry on one side of the negative electrode current collector and drying it, and then coating the other part of the negative electrode slurry on the other side of the negative electrode current collector and drying it, and then rolling it to obtain a negative electrode sheet;

[0062] (4) The positive electrode sheet and the negative electrode sheet are baked separately, and then stacked in the order of negative electrode sheet, diaphragm, positive electrode sheet, diaphragm, and negative electrode sheet, and then subjected to hot pressing, welding, shell punching, packaging, cell baking and liquid injection in sequence to obtain a battery.

[0063] The present application does not specifically limit the first solvent and the second solvent used in the battery preparation process. Exemplarily, the first solvent and the second solvent independently include at least one of deionized water, ethanol, and ethylene glycol.

[0064] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, this application no longer exhaustively lists the specific point values ​​included in the range.

[0065] Compared with the related art, the beneficial effects of this application are:

[0066] The present application provides a method for preparing a positive electrode material, a positive electrode material, and a battery. A low-temperature superconducting nanomaterial is deposited on the surface of a positive electrode material substrate using atomic layer deposition technology, forming a dense superconducting network on the outer surface of the positive electrode material substrate. This effectively avoids the problem of conductivity degradation or even loss of conductivity of the material under low temperature conditions, allowing the positive electrode material to maintain a high capacity even at low temperatures, thereby reducing the discharge DCR.

[0067] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0069] FIG1 is a schematic diagram of the lithium iron phosphate positive electrode material prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0070] The technical solution of the present application will be further explained below with reference to the accompanying drawings and through specific implementation methods.

[0071] Example 1

[0072] This embodiment provides a positive electrode material and a preparation method thereof. As shown in FIG1 , the positive electrode material includes a carbon-coated lithium iron phosphate substrate and a low-temperature superconducting nano-coating layer coated on the outer surface of the carbon-coated lithium iron phosphate substrate. The low-temperature superconducting nano-coating layer has a thickness of 20 nm. The preparation method includes the following steps:

[0073] (1) Providing a carbon-coated lithium iron phosphate matrix with a specific surface area of ​​10.6 m 2 / g, carbon content 0.8%, particle size volume distribution D 50 The particle size is 1.1 μm and the compacted density is 2.38 g / cm 3 ;

[0074] (2) 500 g of the carbon-coated lithium iron phosphate substrate was placed in a reaction chamber of an atomic layer deposition system, and 2.1 g of trimethyl(pentamethylcyclopentadienyl)titanium, 2.9 g of penta(dimethylamino)niobium and nitrogen were simultaneously introduced into the reaction chamber. Atomic layer deposition was performed at a temperature of 400° C. and a pressure of 7 mbar in the reaction chamber to form a low-temperature superconducting nano-coating layer on the surface of the carbon-coated lithium iron phosphate substrate.

[0075] This embodiment also uses the above-mentioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet includes a carbon-coated aluminum foil, and the positive electrode active coating is provided on both sides of the carbon-coated aluminum foil. The negative electrode sheet includes a copper foil, and the negative electrode active coating is provided on both sides of the copper foil.

[0076] The preparation method of the above battery specifically includes the following steps:

[0077] S1: adding the positive electrode material, carbon nanotubes, conductive carbon black, polyvinylidene fluoride binder and N-methylpyrrolidone in a mass ratio of 96.9:1:0.3:1.8:56 into a homogenization tank and stirring until the viscosity reaches 5500-7500 mPa·s to obtain a positive electrode slurry;

[0078] S2: Divide the positive electrode slurry into two parts. Apply one part of the positive electrode slurry to one side of the carbon-coated aluminum foil and dry it. Apply the other part of the positive electrode slurry to the other side of the carbon-coated aluminum foil and dry it. Make the surface density of both sides of the carbon-coated aluminum foil 18mg / cm 2 , and then the positive electrode sheet was rolled to a compaction density of 2.58g / cm 3 , and then cut into 95.6mm×50.2mm size for later use;

[0079] S3: adding graphite, conductive carbon black, sodium carboxymethyl cellulose, styrene-butadiene rubber binder and deionized water in a mass ratio of 96.1:1:1.2:1.7:92 into a homogenization tank and stirring until the viscosity reaches 2000-4000 mPa·s to obtain a negative electrode slurry;

[0080] S4: Divide the negative electrode slurry into two parts. Apply one part of the negative electrode slurry on one side of the copper foil and dry it. Apply the other part of the negative electrode slurry on the other side of the copper foil and dry it. Make the surface density of both sides of the copper foil 9mg / cm 2 , and then the negative electrode sheet was rolled to a compaction density of 1.43 g / cm 3 , and then cut into 100mm×55mm size for later use;

[0081] S5 bakes the positive electrode sheet at 100°C for 12 hours and the negative electrode sheet at 85°C for 12 hours, and then stacks the sheets in the order of negative electrode sheet, diaphragm, positive electrode sheet, diaphragm, and negative electrode sheet. There are 18 negative electrode sheets and 17 positive electrode sheets. Then, after hot pressing, welding, shell punching, packaging, cell baking and liquid injection, a soft-pack battery is obtained. The liquid injection amount of each cell is 16g, and the electrolyte is lithium hexafluorophosphate electrolyte.

[0082] Example 2

[0083] This embodiment provides a positive electrode material and a preparation method thereof. The positive electrode material includes a carbon-coated lithium iron phosphate substrate and a low-temperature superconducting nano-coating layer coated on the outer surface of the carbon-coated lithium iron phosphate substrate. The low-temperature superconducting nano-coating layer has a thickness of 10 nm. The preparation method includes the following steps:

[0084] (1) Providing a carbon-coated lithium iron phosphate matrix with a specific surface area of ​​9m 2 / g, carbon content 0.6%, particle size volume distribution D 50 The thickness is 0.8 μm and the compacted density is 2.5 g / cm 3 ;

[0085] (2) 500 g of the carbon-coated lithium iron phosphate substrate was placed in a reaction chamber of an atomic layer deposition system, and 1.9 g of trimethyl(pentamethylcyclopentadienyl)titanium, 2.1 g of penta(dimethylamino)niobium and nitrogen were simultaneously introduced into the reaction chamber. Atomic layer deposition was performed at a temperature of 300° C. and a pressure of 5 mbar in the reaction chamber to form a low-temperature superconducting nano-coating layer on the surface of the carbon-coated lithium iron phosphate substrate.

[0086] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0087] Example 3

[0088] This embodiment provides a positive electrode material and a preparation method thereof. The positive electrode material includes a carbon-coated lithium iron vanadium phosphate substrate and a low-temperature superconducting nano-coating layer coated on the outer surface of the carbon-coated lithium iron vanadium phosphate substrate. The low-temperature superconducting nano-coating layer has a thickness of 30 nm. The preparation method includes the following steps:

[0089] (1) Providing a carbon-coated lithium iron vanadium phosphate matrix with a specific surface area of ​​15m 2 / g, carbon content 1%, particle size volume distribution D 50 The particle size is 1.5 μm and the compacted density is 2.3 g / cm 3 ;

[0090] (2) 500 g of the carbon-coated lithium iron vanadium phosphate substrate was placed in a reaction chamber of an atomic layer deposition system, and 1.5 g of trimethyl(pentamethylcyclopentadienyl)titanium, 1.9 g of penta(dimethylamino)niobium and nitrogen were simultaneously introduced into the reaction chamber. Atomic layer deposition was performed at a temperature of 500° C. and a pressure of 8 mbar in the reaction chamber to form a low-temperature superconducting nano-coating layer on the surface of the carbon-coated lithium iron vanadium phosphate substrate.

[0091] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises aluminum foil, with a positive electrode active coating applied to both sides of the aluminum foil. The negative electrode sheet comprises copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0092] Example 4

[0093] This embodiment provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), 4.7 g of penta(dimethylamino)niobium, 0.3 g of trimethylaluminum and nitrogen are simultaneously introduced into the reaction chamber, and the remaining process parameters and operating conditions are the same as those in Example 1.

[0094] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0095] Example 5

[0096] This embodiment provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), 3.9 g of penta(dimethylamino)niobium, 1.1 g of trimethyl(phenylethynyl)tin and nitrogen are simultaneously introduced into the reaction chamber, and the remaining process parameters and operating conditions are the same as those in Example 1.

[0097] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0098] Example 6

[0099] This embodiment provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), 2.1 g of trimethyl (pentamethylcyclopentadienyl) titanium, 2.9 g of trimethyl (phenylethynyl) tin and nitrogen are simultaneously introduced into the reaction chamber, and the remaining process parameters and operating conditions are the same as those in Example 1.

[0100] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0101] Example 7

[0102] This embodiment provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), 2.1 g of trimethyl(pentamethylcyclopentadienyl)titanium, 2.9 g of trimethylaluminum and nitrogen are simultaneously introduced into the reaction chamber, and the remaining process parameters and operating conditions are the same as those in Example 1.

[0103] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0104] Example 8

[0105] This embodiment provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), 1.2 g of trimethyl (pentamethylcyclopentadienyl) titanium, 2.9 g of trimethylaluminum, 0.9 g of trimethylaluminum and nitrogen are simultaneously introduced into the reaction chamber, and the remaining process parameters and operating conditions are the same as those in Example 1.

[0106] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0107] Example 9

[0108] This embodiment provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), the temperature of the reaction chamber is 270° C., and the remaining process parameters and operating conditions are the same as those in Example 1.

[0109] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0110] Example 10

[0111] This embodiment provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), the temperature of the reaction chamber is 540° C., and the remaining process parameters and operating conditions are the same as those in Example 1.

[0112] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0113] Example 11

[0114] This embodiment provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), 0.2 g of trimethyl(pentamethylcyclopentadienyl)titanium, 0.23 g of penta(dimethylamino)niobium and nitrogen are introduced into the reaction chamber, and the remaining process parameters and operating conditions are the same as those in Example 1.

[0115] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0116] Example 12

[0117] This embodiment provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), 3 g of trimethyl(pentamethylcyclopentadienyl)titanium, 3.2 g of penta(dimethylamino)niobium and nitrogen are introduced into the reaction chamber, and the remaining process parameters and operating conditions are the same as those in Example 1.

[0118] This example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0119] Comparative Example 1

[0120] This comparative example provides a lithium iron phosphate positive electrode material, which differs from Example 1 in that the carbon-coated positive electrode material matrix is ​​not coated with a low-temperature superconducting nano-coating layer.

[0121] This comparative example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0122] Comparative Example 2

[0123] This comparative example provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), 5 g of trimethyl (pentamethylcyclopentadienyl) titanium and nitrogen are simultaneously introduced into the reaction chamber, and the remaining process parameters and operating conditions are the same as those in Example 1.

[0124] This comparative example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0125] Comparative Example 3

[0126] This comparative example provides a positive electrode material and a preparation method thereof, which differs from Example 1 in that: in step (2), 5 g of penta(dimethylamino)niobium and nitrogen are simultaneously introduced into the reaction chamber, and the remaining process parameters and operating conditions are the same as those in Example 1.

[0127] This comparative example also uses the aforementioned positive electrode material to prepare a battery, wherein the battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet comprises a carbon-coated aluminum foil, with a positive electrode active coating applied to both sides of the carbon-coated aluminum foil. The negative electrode sheet comprises a copper foil, with a negative electrode active coating applied to both sides of the copper foil. The battery preparation method is the same as that of Example 1.

[0128] The batteries of Examples 1 to 12 and Comparative Examples 1 to 3 were tested for discharge capacity at room temperature and low temperature, respectively. The test conditions were: 1 / 3C charge, cut-off voltage 3.65V, and 1 / 3C discharge, cut-off voltage 2.5V. The test results are shown in Table 1.

[0129] Table 1

[0130] As can be seen from Table 1, the batteries of Examples 1 to 10 have higher capacitance and lower DCR at both room temperature and low temperature. This is mainly because the surface of the positive electrode material used in the batteries of Examples 1 to 10 is coated with a low-temperature superconducting nano-coating layer, which enables the positive electrode material to maintain high conductivity even at low temperatures, thereby improving the capacity retention rate of the material at low temperatures.

[0131] Compared with Example 1, the discharge capacity of the batteries of Example 6 and Example 7 at low temperatures is reduced. This is mainly because the metal precursor used in the positive electrode material of Example 1 includes a niobium metal precursor. Compared with the tin metal precursor used in Example 6 and the aluminum metal precursor used in Example 7, the niobium metal precursor has stronger superconductivity at low temperatures and can maintain high electrical conductivity.

[0132] Comparing Examples 1, 9, and 10, it can be seen that the low-temperature discharge capacity of the battery of Example 9 is lower than that of Example 1. This is primarily due to the excessively low temperature in the reaction chamber during the positive electrode material preparation process in Example 9, which prevents the two metal source precursors from reacting effectively to form a dense, low-temperature superconducting nanocoating layer, leading to reduced low-temperature performance. The discharge capacity of Example 10 at both room temperature and low temperature is lower than that of Example 1. This is primarily due to the excessively high temperature in the reaction chamber in Example 10, which increases carbon loss in the positive electrode material and reduces conductivity.

[0133] Table 1 clearly shows that compared to Example 1, Example 11 exhibits lower discharge capacity and higher discharge DCR at low temperatures. This is primarily due to the low addition of the metal precursor, which prevents the formation of a dense, low-temperature superconducting nanocoating layer, thus reducing the superconducting properties of the cathode material at low temperatures. While Example 12 exhibits similar overall electrical performance at both room and low temperatures to that of Example 1, the use of nitrogen to remove excess metal precursor results in material waste.

[0134] As can be seen from Table 1, the differences in discharge capacity and DCR between Example 1 and Comparative Example 1 at room temperature are small. However, under low temperature conditions, the capacity retention rate and DCR performance of Example 1 are significantly better than those of Comparative Example 1. This is mainly due to the formation of a low-temperature superconducting nano-coating layer of TiNb on the surface of the lithium iron phosphate matrix of the positive electrode material used in Example 1, which enhances the conductivity of the positive electrode material at low temperatures.

[0135] By comparing Example 1, Comparative Example 2, and Comparative Example 3, it is not difficult to see that the difference in discharge capacity and DCR at room temperature is small, but at low temperature, the capacity retention rate and DCR performance of Example 1 are significantly better than those of Comparative Example 2 and Comparative Example 3. This is mainly because the positive electrode materials of Comparative Examples 2 and 3 use only one metal precursor, while Example 1 uses two metal precursors to form an alloy structure with superconducting properties, which enhances the conductive performance of the positive electrode material at low temperature more than using a single metal source.

[0136] The applicant declares that the above is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Technical personnel in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technical personnel in the relevant technical field within the technical scope disclosed in this application fall within the protection scope and disclosure scope of this application.

Claims

1. A method for preparing a positive electrode material, comprising: The positive electrode material substrate is placed in a reaction chamber of an atomic layer deposition system, and a low-temperature superconducting nanomaterial precursor is introduced into the reaction chamber for atomic layer deposition to form a low-temperature superconducting nano coating layer on the surface of the positive electrode material substrate.

2. The preparation method according to claim 1, wherein The mass ratio of the low-temperature superconducting nanomaterial precursor to the positive electrode material matrix is ​​(0.1-1):

100.

3. The preparation method according to claim 1 or 2, wherein The positive electrode material matrix is ​​a carbon-coated positive electrode material matrix.

4. The preparation method according to claim 3, wherein The carbon-coated positive electrode material matrix includes any one of a carbon-coated lithium iron phosphate matrix, a carbon-coated lithium iron vanadium phosphate matrix, a carbon-coated lithium iron manganese phosphate matrix, a carbon-coated lithium ferrous manganese phosphate matrix, and a carbon-coated lithium iron sulfate matrix.

5. The preparation method according to claim 3 or 4, wherein The carbon content in the carbon-coated positive electrode material matrix is ​​0.6-1%; Optionally, the specific surface area of ​​the carbon-coated positive electrode material matrix is ​​9 to 15 m 2 / g; Optionally, the particle size D of the carbon-coated positive electrode material matrix 50 0.8~1.5μm; Optionally, the compaction density of the carbon-coated positive electrode material matrix is ​​2.3 to 2.5 g / cm 3 .

6. The preparation method according to any one of claims 1 to 5, wherein: The low-temperature superconducting nanomaterial precursor comprises at least two metal precursors; Optionally, at least two metal precursors are introduced into the reaction chamber simultaneously; Optionally, the metal precursor includes at least one of a niobium metal precursor, a titanium metal precursor, an aluminum metal precursor, a tin metal precursor, a zirconium metal precursor, a vanadium metal precursor and a gallium metal precursor; Optionally, the metal precursor includes penta(dimethylamino)niobium, trimethyl(pentamethylcyclopentyl)niobium, At least one of dimethyl)titanium, trimethylaluminum, trimethyl(phenylethynyl)tin, dimethylbis(cyclopentadienyl)zirconium, di(ethylcyclopentyl)vanadium and triethylgallium.

7. The preparation method according to any one of claims 1 to 6, wherein: The temperature of the reaction chamber is 300-500°C; Optionally, the pressure of the reaction chamber is 5-8 mbar.

8. The preparation method according to any one of claims 1 to 7, wherein: The preparation method further comprises: introducing an inert gas into the reaction chamber for flushing; Optionally, the inert gas and the low-temperature superconducting nanomaterial precursor are simultaneously introduced into the reaction chamber for flushing; Optionally, the inert gas includes nitrogen or argon.

9. A positive electrode material, wherein: The positive electrode material is prepared by the preparation method according to any one of claims 1 to 8, and the positive electrode material comprises a positive electrode material matrix and a low-temperature superconducting nano-coating layer coated on the outer surface of the positive electrode material matrix.

10. The positive electrode material according to claim 9, wherein A carbon coating layer is also arranged between the positive electrode material matrix and the low-temperature superconducting nano coating layer.

11. The positive electrode material according to claim 9 or 10, wherein The thickness of the low-temperature superconducting nano-coating layer is 10-30 nm.

12. The positive electrode material according to any one of claims 9 to 11, wherein The low-temperature superconducting nano-coating layer includes at least one of NbTi, Nb3Al, Nb3Sn, Nb3Zr, NbV and GaNb.

13. A battery comprising a positive electrode sheet and a negative electrode sheet, wherein: The positive electrode plate comprises a positive electrode current collector, and positive electrode active layers are respectively arranged on both side surfaces of the positive electrode current collector, and the positive electrode active layers comprise the positive electrode material according to any one of claims 9 to 12.

14. The battery according to claim 13, wherein The compaction density of the positive electrode sheet is ≥ 2.55g / cm 3 ; Optionally, the positive electrode active layer further comprises a positive electrode conductive agent, conductive carbon black and a positive electrode binder, the total mass of the positive electrode material, the positive electrode conductive agent, the conductive carbon black and the positive electrode binder is calculated as 100%, and the mass proportion of the positive electrode material is 96-97%; Optionally, the positive electrode current collector comprises aluminum foil; Optionally, the thickness of the positive electrode current collector is 8 to 14 μm; Optionally, the negative electrode plate comprises a negative electrode current collector, and both side surfaces of the negative electrode current collector are respectively coated with a negative electrode active layer; Optionally, the compaction density of the negative electrode plate is 1.4 to 1.45 g / cm 3 ; Optionally, the negative electrode current collector comprises copper foil; Optionally, the thickness of the negative electrode current collector is 4-8 μm.

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