Device for high-voltage battery as well as preparation method and application of device

Abstract

The invention relates to the technical field of devices for high-voltage batteries, in particular to a device for a high-voltage battery and a preparation method and application thereof.The device for the high-voltage battery comprises a base membrane and a modified porous ceramic coating, at least one surface of the base membrane is coated with the modified porous ceramic coating, and the modified porous ceramic coating comprises porous ceramic, an oxygen absorption functional material and a binder; the inner surfaces of pores of the porous ceramic and the outer surface of the porous ceramic are coated with the oxygen absorption functional material; the device for the high-voltage battery has high ionic conductivity, high mechanical strength and good thermal stability and electrochemical stability, and can efficiently absorb oxygen at a high speed when being used for a high-voltage system, effectively capture and absorb free oxygen in electrolyte, prevent the free oxygen from penetrating to a negative electrode side, effectively inhibit gas production and circulation attenuation caused by oxygen evolution of the high-voltage lithium battery, and improve the service life of the high-voltage lithium battery. And the cycling stability and safety of the high-voltage lithium battery are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of high-voltage battery devices, and in particular to a high-voltage battery device, its preparation method, and its application. Background Technology

[0002] The demand for high-energy-density lithium-ion batteries primarily comes from three sectors: electric vehicles, energy storage systems, and consumer electronics. Electric vehicles are the biggest driver, with domestic demand for high-energy-density batteries for new energy vehicles projected to reach 800 GWh by 2030. Demand in the energy storage sector is also growing rapidly, projected to reach 300 GWh by 2030. While the growth rate in consumer electronics is slower, the demand for high-energy-density batteries in high-end products remains strong. Therefore, improving the energy density of lithium-ion batteries has become a core research and development direction for the lithium-ion battery industry.

[0003] Traditional ceramic separators, when used in high-energy-density lithium-ion batteries, cannot block free oxygen in the electrolyte. This free oxygen penetrates to the negative electrode side and triggers the oxidation and decomposition of the SEI film, leading to severe battery degradation. Current technologies utilize an oxygen-absorbing coating on the surface of the traditional ceramic separator. This coating, being easily oxidized, preferentially reacts with free oxygen to consume it. While this improvement does consume free oxygen, the chemical oxidation reaction is exothermic, and the oxygen-absorbing coating reduces the ionic conductivity of the separator. Therefore, it severely impacts the battery's cycle performance and safety, making it unsuitable for high-voltage lithium-ion batteries. There is an urgent need for a separator specifically designed for high-voltage batteries.

[0004] Therefore, this application is submitted. Summary of the Invention

[0005] Based on the background technology, this invention provides a high-voltage battery device, its preparation method, and its application. The aim is to propose a high-voltage battery device that can effectively capture and absorb free oxygen in the electrolyte to prevent free oxygen from penetrating to the negative electrode side and causing SEI film decomposition and deterioration of battery performance, while not adversely affecting the cycle stability and safety of lithium batteries.

[0006] To achieve the above objectives, the main technical solutions adopted by the present invention are as follows.

[0007] Firstly, this invention proposes a device for high-voltage batteries, specifically a modified porous ceramic separator, comprising a base film and a modified porous ceramic coating coated on at least one surface of the base film. The modified porous ceramic coating comprises porous ceramic, an oxygen-absorbing functional material, and a binder. The oxygen-absorbing functional material coats the inner surface of the pores of the porous ceramic and the outer surface of the porous ceramic. The oxygen-absorbing functional material has an RP-phase layered perovskite structure and the chemical formula A2BO4, wherein: A is selected from at least one of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Mg, Ca, Sr, and Ba, and B is at least one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Cd, and Ta.

[0008] In this invention, the oxygen-absorbing functional material, due to its typical oxygen non-stoichiometry, can autonomously adsorb free oxygen from the electrolyte into the interstitial positions of its crystal lattice, forming lattice oxygen. The porous ceramic first physically adsorbs free oxygen; due to the oxygen concentration gradient, the free oxygen autonomously enters the interstitial positions of the oxygen-absorbing functional material and transforms into lattice oxygen. The oxygen-absorbing functional material coats the inner and outer surfaces of the porous ceramic. The high specific surface area and porosity of the porous ceramic form a supporting framework and "microreactor" for the oxygen-absorbing functional material, significantly increasing the contact area between the oxygen-absorbing functional material and free oxygen, thus improving oxygen absorption efficiency and rate. The high-voltage battery device proposed in this invention can not only consume free oxygen efficiently and at a high rate but also does not cause heat generation and has no adverse effects on the battery's cycle performance and safety performance.

[0009] In addition, due to the good ionic conductivity of the oxygen-absorbing material and the high voltage resistance, structural stability, and electrochemical stability of the porous ceramic itself, this high-voltage battery device also has high ionic conductivity, high mechanical strength, good thermal stability, and electrochemical stability.

[0010] Furthermore, the oxygen-absorbing functional material is La2CuO4 or / and La2NiO4, and its adsorption of free oxygen is shown in the following reaction equation: .

[0011] The ionic radius of the lanthanum ion has a high degree of matching with that of the oxygen ion, and is similar to that of O. 2- The formation of strong ionic bonds provides a robust structural support; transition metal ions Cu 2+ Ni 2+ / Ni 3+ The unique electronic configuration achieves maximum synergy in oxygen vacancy formation, electronic conductivity, and crystal structure stability. Therefore, La2CuO4 and La2NiO4 can achieve efficient and rapid oxygen capture, maintain long-term stability in the harsh electrochemical environment of high-voltage batteries, and are also low in cost.

[0012] Furthermore, the oxygen-absorbing functional material accounts for 1%-5% of the mass of the porous ceramic.

[0013] In this technical solution, if the mass percentage of oxygen-absorbing functional material to porous ceramic is less than 1%, the oxygen absorption capacity of the high-voltage battery device is poor due to the low proportion of oxygen-absorbing functional material, resulting in a poor capture effect of free oxygen in the electrolyte. If the mass percentage of oxygen-absorbing functional material to porous ceramic is higher than 5%, the high proportion of oxygen-absorbing functional material will cause the pores of the porous ceramic to close, reducing the specific surface area, which is detrimental to the oxygen absorption efficiency. Through repeated experiments, this invention found that when the mass percentage of oxygen-absorbing functional material to porous ceramic is 1%-5%, the oxygen absorption effect is better.

[0014] Furthermore, the modified porous ceramic has a particle size of 300-500 nm, a porosity of 50%-60%, and a specific surface area of ​​30-80 m². 2 / g; Preferably, the thickness of the base film is 3-25 μm; Preferably, the base film is selected from at least one of polypropylene film and polyethylene film, such as a polypropylene single-layer film, a polyethylene single-layer film, or a multilayer composite film composed of polypropylene film and polyethylene film. Preferably, the modified porous ceramic is selected from at least one of porous Al2O3, porous SiO2, porous TiO2, porous MgO, and porous boehmite; among which, porous Al2O3 and porous TiO2 are more effective. Preferably, the adhesive is selected from at least one of polyvinylidene fluoride, polyvinyl alcohol, polyacrylate, styrene-butadiene latex, and polyimide; when using the adhesive, it is preferable to first dissolve it in an organic solvent such as NMP to prepare an adhesive solution before use.

[0015] Secondly, the present invention proposes a method for preparing a device for a high-voltage battery. First, a binder solution is prepared, then the modified porous ceramic is uniformly dispersed in it to obtain a coating slurry, and finally the coating slurry is coated on the base film and baked until dry. The preparation process of the modified porous ceramic includes: S1. Weigh the porous ceramic and the oxygen-absorbing functional material accounting for a percentage of the designed mass of the porous ceramic; S2. Based on the mass of the oxygen-absorbing material, calculate the amount of each metal element and weigh out an equal amount of water-soluble salt. Weigh out citric acid, and fully dissolve the water-soluble salt and citric acid in an alcoholic water solvent to form a precursor solution. Adjust the pH of the precursor solution to 4-6 to inhibit La. 3+ Cu 2+The hydrolysis reaction ensures the formation of a stable and homogeneous precursor solution and provides a favorable ionization environment for citric acid, allowing its carboxyl groups to fully and stably react with La. 3+ Cu 2+ Complexation occurs, achieving uniform mixing at the atomic scale; S3. Place the porous ceramic into the precursor solution, stir thoroughly, and place it in a vacuum oven at room temperature and under vacuum for 2-4 hours. S4. Place the mixture obtained in S3 in a vacuum oven at 80°C for at least 12 hours. During this process, citric acid and ethylene glycol undergo esterification to generate a three-dimensional polymer network. Through this three-dimensional polymer network, the metal ions corresponding to the oxygen-absorbing functional material are uniformly anchored on the pore surface and outer surface of the porous ceramic. After filtration and drying, the modified porous ceramic precursor is obtained. S5. The modified porous ceramic precursor is first sintered at 200-300℃ for 2-4 hours, then sintered at 700-1000℃ for 4-8 hours, and then cooled to room temperature to obtain the product.

[0016] Furthermore, in step S2, the aqueous alcohol solvent is a mixed solvent of deionized water and ethylene glycol in a volume ratio of 1:1, wherein the molar ratio of La, M, and citric acid is 2:1:(4-6). Preferably, the concentration of the precursor solution is 0.2-0.8 mol / L; Preferably, the water-soluble salt is a nitrate; Preferably, ammonia is used to adjust the pH value of the precursor solution.

[0017] Furthermore, in step S3, the mixture obtained in S3 is placed in a vacuum oven at 80°C for at least 24 hours.

[0018] Furthermore, the coating method includes gravure coating, blade coating, and anilox roller coating.

[0019] Thirdly, the present invention proposes a lithium-ion battery including the above-mentioned high-voltage battery devices.

[0020] Furthermore, it also includes a positive electrode, a negative electrode, and an electrolyte, wherein the active material on the positive electrode is selected from one of high-voltage lithium cobalt oxide, high-voltage ternary materials, and lithium-rich manganese-based positive electrode materials.

[0021] Compared with the prior art, the porous ceramic in the high-voltage battery device proposed in this invention is coated with an oxygen-absorbing functional material on the inner surface of the porous ceramic and the outer surface of the porous ceramic. This oxygen-absorbing functional material can effectively capture and absorb free oxygen in the electrolyte through electrochemical reaction to prevent free oxygen from penetrating to the negative electrode side and avoid causing SEI film decomposition. The entire capture process is non-heating and does not involve other reactions that are detrimental to the performance of high-voltage lithium batteries. It effectively suppresses gas generation and cycle decay caused by oxygen evolution in high-voltage lithium batteries, and greatly improves the cycle stability and safety of high-voltage lithium batteries. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a comparison chart of the high-temperature cycling capacity retention rates of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 12. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] All chemical raw materials used in the following examples and comparative examples are commercially available, and all apparatus and operations involved are conventional in the art.

[0026] Experimental Example 1 (1) Preparation of modified porous ceramics S1. Weigh 1000g of porous Al2O3 and 10g of La2CuO4 (0.0247mol). The porous Al2O3 has a particle size of approximately 500nm, a porosity of 55%, and a specific surface area of ​​50m². 2 / g; S2. Weigh 21.39g of lanthanum nitrate hexahydrate (0.0494mol), 5.97g of copper nitrate trihydrate (0.0247mol), and 23.73g of citric acid (0.1235mol), i.e., the molar ratio of La to Cu to citric acid is 2:1:5. Dissolve lanthanum nitrate hexahydrate, copper nitrate, and citric acid completely in a water-ethylene glycol solvent with a volume ratio of 1:1 to form a precursor solution with a concentration of 0.5mol / L. Adjust the pH of the precursor solution to 5 using ammonia. S3. Place the porous Al2O3 into the precursor solution, stir thoroughly, and place it in a vacuum oven to stand at room temperature for 2 hours to ensure that the precursor solution fully wets the porous Al2O3. S4. Place the mixture obtained in S3 in a vacuum oven at 80°C for 24 hours to ensure that citric acid and ethylene glycol undergo esterification to form a three-dimensional polymer network. Metal ions are uniformly anchored on the surface and pores of porous Al2O3 through this three-dimensional polymer network. After filtration and drying, a modified porous ceramic precursor is obtained. S5. The modified porous ceramic precursor is sintered at 300°C for 2 hours, then sintered at 900°C for 6 hours, and cooled to room temperature to obtain La2CuO4 modified porous alumina ceramic, wherein La2CuO4 accounts for 1 wt% of porous alumina.

[0027] (2) Fabrication of devices for high-voltage batteries First, polyvinylidene fluoride (PVDF) is dissolved in NMP to form a slurry. Then, La2CuO4-modified porous alumina ceramic is uniformly dispersed in the slurry to form a paste. The mass ratio of La2CuO4-modified porous alumina ceramic to PVDF is 95:5. The paste is then coated on both surfaces of a 9μm thick PE base film, with a single-sided coating thickness of 3μm. After drying, a modified porous alumina coated membrane is obtained.

[0028] (3) Assemble lithium-ion batteries The modified porous alumina coated separator was assembled with lithium-rich positive electrode, graphite negative electrode, and commercial Tinci electrolyte (Guangzhou Tinci Advanced Materials Co., Ltd., model TC-E918L105) into a pouch battery.

[0029] Example 2

[0030] Compared with Example 1, the proportion of La2CuO4 was adjusted from 1 wt% of porous alumina to 3 wt%, and the mass of lanthanum nitrate hexahydrate, copper nitrate trihydrate, and citric acid were adjusted accordingly, while the rest remained the same as in Example 1.

[0031] Example 3

[0032] Compared with Example 1, the proportion of La2CuO4 was adjusted from 1 wt% of porous alumina to 5 wt%, and the mass of lanthanum nitrate hexahydrate, copper nitrate trihydrate, and citric acid were adjusted accordingly, while the rest remained the same as in Example 1.

[0033] Example 4

[0034] Compared to Example 2, copper nitrate trihydrate was replaced with an equal amount of nickel nitrate, while all other aspects remained the same as in Example 1.

[0035] Example 5

[0036] Compared with Example 2, the porosity and specific surface area of ​​the porous Al2O3 used remained unchanged, the particle size was adjusted to about 400 nm, and the rest remained the same as in Example 2.

[0037] Example 6

[0038] Compared with Example 2, the porosity and specific surface area of ​​the porous Al2O3 used remained unchanged, the particle size was adjusted to about 300 nm, and the rest remained the same as in Example 2.

[0039] Example 7

[0040] Compared with Example 2, the particle size and specific surface area of ​​the porous Al2O3 used remained unchanged, the porosity was adjusted from 55% to 50%, and the rest remained the same as in Example 2.

[0041] Example 8

[0042] Compared with Example 2, the particle size and specific surface area of ​​the porous Al2O3 used remained unchanged, the porosity was adjusted from 55% to 60%, and the rest remained the same as in Example 2.

[0043] Example 9

[0044] Compared to Example 2, the particle size and porosity of the porous Al2O3 used remained unchanged, while the specific surface area increased from 50 m² / s². 2 / g adjusted to 30m 2 / g, the rest is consistent with Example 2.

[0045] Example 10

[0046] Compared to Example 2, the particle size and porosity of the porous Al2O3 used remained unchanged, while the specific surface area increased from 50 m² / s². 2 / g adjusted to 80m 2 / g, the rest is consistent with Example 2.

[0047] Example 11

[0048] Compared with Example 2, the mass of citric acid was adjusted so that the ratio of La:Cu:citric acid was changed from 2:1:5 to 2:1:4, while all other ratios remained the same as in Example 2.

[0049] Example 12

[0050] Compared with Example 2, the mass of citric acid was adjusted so that the ratio of La:Cu:citric acid was changed from 2:1:5 to 2:1:6, while all other aspects remained the same as in Example 2.

[0051] Example 13

[0052] Compared with Example 2, the concentration of the precursor solution was adjusted from 0.5 mol / L to 0.2 mol / L, while all other parameters remained the same as in Example 2.

[0053] Example 14

[0054] Compared with Example 2, the concentration of the precursor solution was adjusted from 0.5 mol / L to 0.8 mol / L, while all other parameters remained the same as in Example 2.

[0055] Example 15

[0056] Compared to Example 2, copper nitrate trihydrate was replaced with an equal amount of ferric nitrate, while all other aspects remained the same as in Example 2.

[0057] Example 16

[0058] Compared to Example 2, copper nitrate trihydrate was replaced with an equal amount of cobalt nitrate, while all other aspects remained the same as in Example 2.

[0059] Example 17

[0060] Compared to Example 2, copper nitrate trihydrate was replaced with an equal amount of manganese nitrate, while all other aspects remained the same as in Example 2.

[0061] Example 18

[0062] Compared with Example 2, the porous Al2O3 in operation (1) was changed to porous SiO2 of the same specification, and the PE base film in operation (2) was changed to a PP base film with a thickness of 3μm. All other aspects remained the same as in Example 2.

[0063] Example 19

[0064] Compared with Example 2, the porous Al2O3 in operation (1) was changed to porous TiO2 of the same specification, and the PE base film in operation (2) was changed to a PP / PE / PP three-layer composite base film with a thickness of 25μm. All other aspects remained the same as in Example 2.

[0065] Comparative Example 1 Compared with Example 2, the porous Al2O3 was not modified with La2CuO4, and all other aspects remained the same as in Example 1.

[0066] Comparative Example 2 Compared with Example 2, the proportion of La2CuO4 was adjusted from 3 wt% of porous alumina to 0.3 wt%, and the mass of lanthanum nitrate hexahydrate, copper nitrate, and citric acid was adjusted accordingly, while the rest remained the same as in Example 1.

[0067] Comparative Example 3 Compared with Example 2, the proportion of La2CuO4 was adjusted from 3wt% of porous alumina to 8wt%, and the mass of lanthanum nitrate hexahydrate, copper nitrate, and citric acid were adjusted accordingly, while the rest remained the same as in Example 1.

[0068] Comparative Example 4 Compared with Example 2, the porosity and specific surface area of ​​the porous Al2O3 used remained unchanged, the particle size was adjusted from about 500 nm to about 200 nm, and the rest remained the same as in Example 2.

[0069] Comparative Example 5 Compared with Example 2, the porosity and specific surface area of ​​the porous Al2O3 used remained unchanged, the particle size was adjusted from about 500 nm to about 750 nm, and the rest remained the same as in Example 2.

[0070] Comparative Example 6 Compared to Example 2, the particle size and porosity of the porous Al2O3 used remained unchanged, while the specific surface area increased from 50 m² / s². 2 / g adjusted to 10m 2 / g, the rest is consistent with Example 2.

[0071] Comparative Example 7 Compared to Example 2, the particle size and porosity of the porous Al2O3 used remained unchanged, while the specific surface area increased from 50 m² / s². 2 / g adjusted to 100m 2 / g, the rest is consistent with Example 2.

[0072] Comparative Example 8 Compared with Example 2, the particle size and specific surface area of ​​the porous Al2O3 used remained unchanged, the porosity was adjusted from 55% to 40%, and the rest remained the same as in Example 2.

[0073] Comparative Example 9 Compared with Example 2, the particle size and specific surface area of ​​the porous Al2O3 used remained unchanged, the porosity was adjusted from 55% to 70%, and the rest remained the same as in Example 2.

[0074] Comparative Example 10 Compared with Example 2, the mass of citric acid was adjusted so that the ratio of La:Cu:citric acid was changed from 2:1:5 to 2:1:7, while all other aspects remained the same as in Example 2.

[0075] Comparative Example 11 Compared with Example 2, the concentration of the precursor solution was adjusted from 0.5 mol / L to 1 mol / L, while all other aspects remained the same as in Example 2.

[0076] Comparative Example 12 (1) Preparation of diaphragm First, polyvinylidene fluoride is dissolved in NMP to form a slurry. Then, La2CuO4 particles with a diameter of about 500 nm are uniformly dispersed in the slurry to form a paste. The mass ratio of La2CuO4 to polyvinylidene fluoride is 95:5. The paste is then coated on both surfaces of a PE base film with a thickness of 9 μm, with a single-sided coating thickness of 3 μm. After drying, a separator is obtained.

[0077] (2) Assemble lithium-ion batteries The obtained separator was assembled with lithium-rich positive electrode, graphite negative electrode, and commercial Tinci electrolyte (Guangzhou Tinci Advanced Materials Co., Ltd., model TC-E918L105) into a pouch battery.

[0078] Comparative Example 13 Compared with Example 2, the mass of citric acid was adjusted so that the ratio of La:Cu:citric acid was changed from 2:1:5 to 2:1:3, while all other aspects remained the same as in Example 2.

[0079] Comparative Example 14 Compared with Example 2, the concentration of the precursor solution was adjusted from 0.5 mol / L to 0.1 mol / L, while all other aspects remained the same as in Example 2.

[0080] The key technical parameters of the above embodiments and comparative examples are shown in Table 1.

[0081]

[0082] The high-voltage battery devices prepared in each embodiment and comparative example were subjected to the following tests: (1) Thermal shrinkage test: The separator sample was cut into a size of 50mm*50mm and heated in an electric thermostatic vacuum drying oven at 120℃ for 30min. The dimensional changes of the separator in the transverse direction (TD) and longitudinal direction (MD) were observed. (2) Puncture strength test: The separator sample was cut into a size of 45mm*45mm and punctured with a needle with a diameter of 1mm at a speed of 5mm / min. The maximum force value F was recorded.max Puncture intensity = F max / Separator thickness (unit gf / μm). (3) Separator ionic conductivity test: Cut the separator into a circular piece with a diameter of 1.96cm, immerse the circular piece in the electrolyte in a glove box filled with argon, take it out and place it between two stainless steel electrodes and encapsulate it with a CR2032 button battery shell. Test the conductivity using a Chenhua CH I660E electrochemical workstation at room temperature using a frequency range of 10mHz-1MHz. Calculate the ionic conductivity according to the formula: σ=d / (RS), where: σ is in units of S / cm, d is the thickness of the separator in cm, R is the bulk resistance of the separator in Ω, and S is the effective contact area of ​​the separator in cm². (4) Liquid storage performance test: Take a 10cm*10cm separator and immerse it in an electrolyte at 60℃ for 12h. Weigh the mass before and after immersion. Liquid storage rate % = mass after immersion / mass before immersion * 100%. The final test results are shown in Table 2.

[0083]

[0084] The lithium-ion batteries assembled in each embodiment and comparative example were subjected to the following electrochemical performance tests: In a 45°C constant-temperature explosion-proof chamber, they were charged at a constant current of 1C to 4.65V, then charged at a constant voltage of 4.65V to 0.05C, and allowed to stand for 10 minutes; then discharged at a constant current of 1C to 2.0V, and allowed to stand for 10 minutes; the charge-discharge cycle was repeated 200 times, and the capacity retention, coulombic efficiency, and gas production V were recorded. L Gas production V L The test was conducted using the water displacement method. The battery volume was recorded as V1, and the combined battery and gas volume after cycling was recorded as V2. The gas production from the battery was V. L =V2-V1. The final test results are shown in Table 3.

[0085]

[0086] As shown in Table 1, Table 2, Table 3, Figure 1 As shown in the following: A comparison of the test results from Examples 1-17 with Comparative Example 1 shows that, compared to unmodified porous Al2O3, the present invention modifies the porous Al2O3 by coating its pore surface and the outer surface with a defined proportion of oxygen-absorbing functional material. The resulting separator exhibits high ionic conductivity, high mechanical strength, good thermal stability and electrochemical stability, and excellent electrolyte retention. When applied to high-voltage lithium batteries, the oxygen-absorbing functional material efficiently and rapidly captures and absorbs free oxygen from the electrolyte, resulting in: a 200-cycle capacity retention rate that can be increased from 78.2% to a maximum of 84.2%, an improvement of up to 7.7%; a 200-cycle coulombic efficiency that can be increased from 96.42% to a maximum of 99.48%, an improvement of up to 3.2%; and a gas production rate after 200 cycles that can be reduced from 9.23 ml / Ah to a minimum of 3.35 ml / Ah, a reduction of up to 63.7%. Clearly, the high-voltage battery device proposed in this invention can significantly improve the cycle stability and safety of high-voltage batteries.

[0087] Specifically, such as Figure 1 As shown: Compared with traditional porous Al2O3 ceramic separators (Comparative Example 1) and directly coating La2CuO4 onto the base film to form a separator, the present invention significantly improves the long-cycle stability of high-voltage batteries by coating the inner surface of porous Al2O3 and the outer surface of porous Al2O3 with oxygen-absorbing functional material at a loading of 1%-5%.

[0088] Furthermore, a comparison of the test results from Examples 2 and 4 with Examples 15, 16, and 17 shows that when La2CuO4 or / and La2NiO4 are selected as the oxygen absorption material, the resulting high-voltage battery device has higher ionic conductivity, can more significantly reduce interface impedance, and has higher oxygen absorption efficiency. Therefore, it is more conducive to improving the 200th cycle capacity retention rate and 200th cycle coulombic efficiency, and has a more significant effect on improving the cycle stability and safety of high-voltage lithium batteries.

[0089] A comparison of the test results from Examples 2, 5-10, and Comparative Examples 4-9 shows that, under the same conditions, the particle size, porosity, and specific surface area of ​​porous Al2O3 significantly affect the modification effect. A particle size range of 300-500 nm helps to improve the uniformity of coating and enhance ionic conductivity; a porosity of 50%-60% and a specific surface area of ​​30-80 nm also contribute to the modification effect. 2 A specific surface area of ​​ / g not only provides more anchoring points for the corresponding metal ions in the oxygen-absorbing functional material, but also helps the electrolyte to wet; if any of the particle size, porosity, or specific surface area is outside the technical scope limited by this invention, the performance of the resulting high-voltage battery device will be poor.

[0090] The test results of Examples 1, 2, and 3 are compared with those of Comparative Examples 2 and 3. It can be seen that, under the same conditions, the proportion of oxygen-absorbing material La2CuO4 has a significant impact on the modification effect. When La2CuO4 accounts for 1wt%-5wt% of porous Al2O3, La2CuO4 can uniformly coat the outer surface of porous Al2O3 and the inner surface of the pores of porous Al2O3. This can improve the ionic conductivity of the separator and maintain a high liquid retention rate while effectively capturing and absorbing free oxygen, thus significantly improving the cycle stability and safety of high-voltage batteries. When the proportion of La2CuO4 is less than 1 wt% (such as 0.3 wt% as shown in Comparative Example 2), although the heat shrinkage rate, puncture strength, ionic conductivity and liquid retention rate of the obtained high-voltage battery device are still good, the low concentration of La2CuO4 cannot play an effective role and the capture effect of free oxygen is poor. When the proportion of La2CuO4 is higher than 1 wt% (such as 8 wt% as shown in Comparative Example 3), the ionic conductivity and liquid retention rate of the obtained high-voltage battery device decrease significantly, and the capture effect of free oxygen is also poor. This is because an excessively high proportion of La2CuO4 will cause the pores of porous Al2O3 to close, reduce the specific surface area, and is not conducive to oxygen absorption efficiency.

[0091] A comparison of the test results of Examples 2, 13, and 14 with those of Comparative Examples 11 and 14 shows that, under the same conditions, the concentration of the precursor solution significantly affects the performance of the modified porous ceramics. When the concentration of the precursor solution is 0.2-0.8 mol / L, the resulting high-voltage battery devices exhibit good ionic conductivity and liquid retention. However, when the concentration is below 0.2 mol / L (such as 0.1 mol / L in Comparative Example 14) or above 0.8 mol / L (such as 1 mol / L in Comparative Example 11), the performance of the resulting high-voltage battery devices is poor. The reason for this is that both excessively low and excessively high concentrations of the precursor solution lead to poor wettability of the precursor solution on the porous Al2O3, affecting the anchoring of metal ions on the inner and outer surfaces of the porous Al2O3 pores, ultimately resulting in an unsatisfactory La2CuO4 coating effect.

[0092] A comparison of the test results of Examples 2, 11, and 12 with Comparative Examples 10 and 13 shows that, under the same conditions, the molar ratio of La, Cu(Ni), and citric acid in the precursor has a significant impact on the modification effect. A molar ratio of 2:1:(4-6) for La, Cu(Ni), and citric acid is preferable. If there is too little citric acid (as shown in Comparative Example 13, 2:1:3) or too much citric acid (as shown in Comparative Example 10, 2:1:7), the performance of the resulting high-voltage battery device will be poor. It is speculated that a low citric acid ratio will result in insufficient complexation and cross-linking, leading to uneven metal dispersion, while a high citric acid ratio will result in an overly dense three-dimensional polymer network and increased residual carbon. Both situations will lead to deterioration of the coating effect and performance.

[0093] In summary, this invention achieves excellent coating of the oxygen-absorbing functional material on both the inner and outer surfaces of the porous ceramic by synergistic regulation of the particle size, porosity, and specific surface area of ​​the modified porous ceramic, combined with the control of the proportion of oxygen-absorbing functional material, the concentration of the precursor solution, and the molar ratio of La, Cu(Ni), and citric acid in the precursor solution. The resulting modified porous ceramic, when used in high-voltage battery devices, exhibits high ionic conductivity, high mechanical strength, good thermal stability, and electrochemical stability. When used in high-voltage lithium batteries, it can significantly improve the cycle stability and safety of high-voltage lithium batteries.

[0094] In summary, this invention obtains a modified porous ceramic by coating the inner surface and outer surface of the porous ceramic with an oxygen-absorbing functional material. When this modified porous ceramic is used to make devices for high-voltage batteries and applied to high-voltage lithium batteries, it can effectively capture and absorb free oxygen in the electrolyte to prevent free oxygen from penetrating to the negative electrode side, thus avoiding SEI film decomposition. This effectively suppresses gas generation and cycle degradation caused by oxygen evolution in high-voltage lithium batteries, and greatly improves the cycle stability and safety of high-voltage lithium batteries.

[0095] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions, and variations to the above embodiments within the scope of the present invention. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples.

Claims

1. A device for high voltage batteries, characterized by: The base film and the modified porous ceramic coating coated on at least one surface of the base film, the modified porous ceramic coating comprises porous ceramic, oxygen-absorbing functional material and binder, the oxygen-absorbing functional material is coated on the inner surface of the pores of the porous ceramic and the outer surface of the porous ceramic, the oxygen-absorbing functional material is RP phase layered perovskite structure and the chemical formula is A2BO4, wherein: A is at least one selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Mg, Ca, Sr and Ba, and B is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Cd and Ta.

2. The device for high voltage battery according to claim 1, characterized by: The oxygen-absorbing functional material is La2CuO4 or / and La2NiO4.

3. The device for high voltage battery according to claim 1, characterized by: The mass percentage of the oxygen-absorbing functional material and the porous ceramic is 1%-5%.

4. The device for high voltage battery of claim 1, wherein: The modified porous ceramic has a particle size of 300-500 nm, a porosity of 50-60%, and a specific surface area of 30-80 m 2 / g. Preferably, the thickness of the base film is 3-25μm; Preferably, the base film is at least one selected from polypropylene film and polyethylene film; Preferably, the modified porous ceramic is at least one selected from porous Al2O3, porous SiO2, porous TiO2, porous MgO and porous boehmite; Preferably, the binder is at least one selected from polyvinylidene fluoride, polyvinyl alcohol, polyacrylate, butyl rubber latex and polyimide.

5. A method of producing a device for high-voltage batteries as claimed in any one of claims 1-4, characterized in that: First, the binder solution is prepared, then the modified porous ceramic is uniformly dispersed in the binder solution to obtain coating slurry, finally the coating slurry is coated on the base film and baked to dryness; The preparation operation of the modified porous ceramic comprises: S1, the porous ceramic and the oxygen-absorbing functional material with the designed mass percentage of the porous ceramic are weighed; S2, according to the mass of the oxygen-absorbing functional material, the amount of substance of each metal element is calculated and the water-soluble salt corresponding to the amount of substance is weighed, citric acid is weighed, the water-soluble salt and citric acid are fully dissolved in the water-alcohol solvent to form a precursor solution, and the pH value of the precursor solution is adjusted to 4-6; S3, the porous ceramic is put into the precursor solution, fully stirred and placed in a vacuum oven at room temperature for 2-4h; S4, the mixed system obtained in S3 is placed in a vacuum oven at 80℃ for at least 12h, filtered and dried to obtain a modified porous ceramic precursor; S5, the modified porous ceramic precursor is first sintered at 200-300℃ for 2-4h, then sintered at 700-1000℃ for 4-8h, and cooled to room temperature.

6. The method of producing a device for high-voltage batteries according to claim 5, characterized in that: In step S2, the water-alcohol solvent is a mixed solvent with a volume ratio of deionized water to ethylene glycol of 1:1, and the molar ratio of La, M and citric acid is 2:1:(4-6); Preferably, the concentration of the precursor solution is 0.2-0.8mol / L; Preferably, the water-soluble salt is nitrate; Preferably, ammonia is used to adjust the pH value of the precursor solution.

7. The method of claim 5, wherein: In step S3, the mixed system obtained in S3 is placed in a vacuum oven at 80℃ for at least 24h.

8. The method of claim 5, wherein: The coating method comprises gravure coating, blade coating and anilox roll coating.

9. A lithium ion battery comprising the device for high voltage battery as claimed in any one of claims 1 to 4 or the device for high voltage battery prepared according to the preparation method as claimed in any one of claims 5 to 8.

10. The lithium-ion battery of claim 9, wherein: Further comprising a positive electrode sheet, a negative electrode sheet and an electrolyte, the active material on the positive electrode sheet is selected from one of high-voltage lithium cobalt oxide, high-voltage ternary material, lithium-rich manganese-based positive electrode material.

Images