A battery seal cover assembly and a method of manufacturing the same

Abstract

This invention relates to a battery sealing cap assembly and its preparation method, characterized in that: (1) glass mixture a and mixture b are melted in a high-temperature furnace to obtain glass liquid a and glass liquid b respectively; (2) glass liquid a and glass liquid b are quenched in water, dried, ground, and sieved to obtain powder a and powder b respectively; (3) powder a and powder b are mixed with water, binder and coupling agent respectively to form a slurry, granulated into balls, and sieved to obtain glass powder a and glass powder b; (4) glass powder a and glass powder b are shaped to obtain green blank a and green blank b, and after complete glue removal at room temperature to 300°C, the temperature is raised to 370 to 500°C and kept warm to form sealing glass blank I and sealing glass blank II; (5) the metal aluminum shell to be sealed, copper core column and sealing glass blank I and sealing glass blank II are assembled together to form a component to be sealed, and sealed at 490 to 540°C and annealed. Advantages of this invention: The sealing glass prepared has a coefficient of thermal expansion > 160 × 10⁻⁶ at 300°C. ‑7 / ℃, water resistance rating of level 3 or above, sealing temperature <550℃.

Description

Technical Field

[0001] This invention belongs to the field of glass powder preparation technology, specifically the field of electronic glass powder, and relates to a battery sealing cap assembly and its preparation method. Background Technology

[0002] The new energy vehicle industry is currently in a phase of rapid development. The packaging materials for power lithium batteries used in new energy vehicles are closely related to the battery's energy density and have a significant impact on its safety performance. Unlike ordinary lithium batteries, power lithium batteries operate in extremely harsh environments, thus requiring very high-level packaging technology. Besides optimizing the structural design of the sealing components, the key to power lithium battery electrode packaging technology is selecting suitable packaging materials.

[0003] Currently, the encapsulation materials between the terminals and the metal casing of power lithium batteries mainly include plastic sealing rings, ceramic metallized materials, and sealing glass powder. The advantage of using glass powder encapsulation is that the sealing glass and the oxide film on the metal surface can form chemical bonds after encapsulation, which is beneficial for achieving hermetic sealing and excellent electrical insulation. Currently, the composition system of sealing glass powder used in power lithium batteries mainly includes low-melting-point glass systems such as phosphates, vanadates, and bismuthates. However, the main problems and difficulties lie in the fact that the battery terminals and the metal casing are copper and aluminum, respectively, with different and much higher coefficients of thermal expansion than ordinary sealing glass. Therefore, during the sealing process, there are issues such as a mismatch between the thermal expansion coefficients of the sealing glass and those of the casing and terminals, and immature encapsulation technology, which affect the encapsulation effect and limit the practical application of sealing glass powder in the field of power lithium batteries. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of mismatch between the thermal expansion coefficient of the existing sealing glass and the thermal expansion coefficient of the outer shell and the terminal post, and the immature packaging process, and to provide a battery sealing cover assembly and its preparation method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A battery sealing cover assembly, comprising an aluminum shell and a copper core, characterized in that sealing glass blank I and sealing glass blank II are made from raw materials in the following molar ratios: P2O5: 23~24.5, Al2O3: 15.5~16.9, B2O3: 9~10, NaF: 18.5~19.5, Li2O: 0.1~1, Na2O: 11.5~12.5, K2O: 11~11.8, TiO2: 2.5~3, SiO2: 4.5~5, SrO: 0.1~0.5, BaO: 0.1~0.5.

[0007] Furthermore, the battery sealing cover assembly is characterized in that the sealing glass blank I and the sealing glass blank II are made from raw materials in the following molar ratios: P2O5: 23~24, Al2O3: 15.8~16.5, B2O3: 9.5~10, NaF: 18.8~19.2, Li2O: 0.1~0.5, Na2O: 11.5~12.2, K2O: 11~11.5, TiO2: 2.5~2.8, SiO2: 4.5~4.8, SrO: 0.1~0.3, BaO: 0.1~0.3.

[0008] A method for preparing a battery sealing cover assembly, characterized by comprising the following steps:

[0009] (1) Weigh two groups of materials according to the following molar ratios: P2O5: 23~24.5, Al2O3: 15.5~16.9, B2O3: 9~10, NaF: 18.5~19.5, Li2O: 0.1~1, Na2O: 11.5~12.5, K2O: 11~11.8, TiO2: 2.5~3, SiO2: 4.5~5, SrO: 0.1~0.5, BaO: 0.1~0.5, and mix them evenly to obtain mixture a and mixture b;

[0010] (2) Melt the mixture a in a high-temperature electric furnace, raise the temperature to 1000~1300℃ according to the step temperature system, and hold for 60~180min to obtain clear glass liquid a; obtain glass liquid b by the same steps;

[0011] (3) After quenching the molten glass liquid a and glass liquid b in deionized water, take them out, dry them, grind them, and pass them through a 500-mesh sieve to obtain powder a and powder b.

[0012] (4) Mix powder a with water, binder and coupling agent in a weight ratio of 52~56:42~46:3.1~4:0.4~0.6 to prepare a slurry, and finally granulate it into balls in a spray granulator. Screen the particles with a particle size distribution D50 of 80~120μm to obtain the desired glass powder a; mix powder b with water, binder and coupling agent in a weight ratio of 52~56:42~46:3.1~4:0.4~0.6 to prepare a slurry, and obtain glass powder b by the same steps;

[0013] (5) Glass powder a and glass powder b are used to prepare green blanks a and b by a servo powder molding machine. After complete debinding at room temperature to 300°C, the temperature is raised to 370 to 500°C and held for 10 to 30 minutes to make sealing glass blank I and sealing glass blank II of glass blanks.

[0014] (6) Assemble the aluminum shell to be sealed, the copper core column, and the sealing glass blanks I and II obtained in step (5) into a sealing assembly. Then, slowly heat the furnace to 490~540℃ and hold for 15~30 minutes to seal the assembly. Anneal the assembly in the furnace for 2~3 hours to room temperature to obtain the battery sealing cover assembly.

[0015] Furthermore, in step (1), the mixing is carried out by mixing with zirconium balls for 1-3 hours.

[0016] Furthermore, in step (4), the binder is a combination of two or more of hydroxypropyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol; the coupling agent is a combination of one or more of γ-aminopropyltriethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, and vinyltriethoxysilane.

[0017] Furthermore, in step (5), the pressure of the molding machine during molding is 10~12MPa, and the porosity of the glass blank is 33-38%.

[0018] Furthermore, in step (5), the sintering shrinkage rate of sealing glass blank I and sealing glass blank II relative to the glass body is 10-11%.

[0019] Furthermore, in step (5), the ratio of the thermal expansion coefficient of sealing glass blank I to that of sealing glass blank II is 1 to 1.4.

[0020] Furthermore, in step (5), the ratio of the thermal expansion coefficient of sealing glass blank I to that of sealing glass blank II is 1.1 to 1.3.

[0021] Furthermore, in step (5), the ratio of the outer diameter of glass blank II after sintering to the inner diameter of glass blank I is 0.9~1.

[0022] Furthermore, in step (5), the ratio of the outer diameter of glass blank II after sintering to the inner diameter of glass blank I is 0.95~1.

[0023] P2O5 is a glass-forming oxide that forms the structural network of phosphate glass with phosphorus-oxygen tetrahedra [PO4]. However, it reduces the chemical stability of the glass, and pure phosphate glass is easily hydrolyzed. In this invention, the suitable range of P2O5 is 23-24.5%. Al2O3 is an intermediate oxide in the glass network and plays a special role in phosphate glass. Aluminum can form aluminum-oxygen tetrahedra with oxygen with double bonds in phosphorus-oxygen glass, which can improve and strengthen the structure of phosphate glass. After introduction, it can reduce the tendency of glass precipitation and improve a series of glass properties. However, if too much is introduced, it will cause the viscosity of the glass melt to increase rapidly and make melting difficult. In this invention, the suitable range of Al2O3 is 15.5-16.9%. In this invention, Al2O3 is introduced with Al(OH)3 because Al(OH)3 can be dehydrated at a low temperature of 140-150℃ to obtain γ-alumina, which is more likely to react with low-melting-point glass batches and enter the glass network structure. B2O3 is a glass network-forming oxide that can improve a range of glass properties, such as reducing the coefficient of thermal expansion and high-temperature viscosity. It also acts as a flux, accelerating glass melting and refining agent. However, excessive amounts can lead to phase separation or crystallization and reduce the glass's chemical stability. In this invention, the suitable range for B2O3 is 9-10%. NaF can reduce the viscosity and surface tension of molten glass, promote its refining and homogenization, effectively lower the softening point, and increase the coefficient of thermal expansion. However, excessive amounts can worsen its water resistance. In this invention, the suitable range for NaF is 18.5-19.5%. SiO2 is a glass network-forming agent. Appropriate amounts introduced into phosphate glass are beneficial for repairing the glass network structure and improving its water resistance. However, excessive amounts can increase the viscosity and softening point of the molten glass, hindering sealing. In this invention, the suitable range for SiO2 is 4.5-5%.

[0024] Alkali metal oxides Li₂O, Na₂O, and K₂O do not participate in the network structure; they are network exogenous oxides that increase the thermal expansion coefficient and lower the softening temperature of glass. However, this compromises the chemical stability of the glass. By controlling the molar percentage of Li₂O, Na₂O, and K₂O, the chemical stability of the glass can be improved using alkali metal ions (Li₂O, Na₂O, and K₂O). + Na + K +The difference in radius creates a mixed alkali effect, which is beneficial for glass melting and glass formation, and significantly improves the chemical stability of the glass. In this invention, the suitable ranges for Li₂O are 0.1–1%, Na₂O is 11.5–12.5%, and K₂O is 11–11.8%. TiO₂ is an oxide on the glass network, characterized by its ability to significantly improve the chemical stability and sealing life of the glass. However, excessive introduction will increase the high-temperature viscosity and crystallization tendency of the glass. In this invention, the suitable range for TiO₂ is 2.5–3%. Alkaline earth metal oxides SrO and BaO are beneficial for lowering the softening point of the glass, improving its fluidity in the low-temperature region, thereby lowering the sealing temperature of the glass powder, improving the glass production conditions and crystallization properties, and enhancing the hardness and corrosion resistance of the glass. However, excessive content will increase the crystallization tendency of the glass. In this invention, the suitable ranges for SrO and BaO are 0.1–0.5%.

[0025] The raw material for introducing P2O5 is a mixture of NH4H2PO4 and P2O5. NH4H2PO4 is beneficial for forming PN bonds in the glass network, strengthening the network structure and improving water resistance. However, excessive introduction can lead to severe volatilization of the raw material. Therefore, introducing an appropriate amount of P2O5 to form a mixture of NH4H2PO4 and P2O5 can effectively reduce phosphorus volatilization. In this invention, the molar ratio of NH4H2PO4 / P2O5 is 1.8~2.5. The raw material for introducing B2O3 is a mixture of B2O3 and H3BO3. Simultaneous introduction can improve the compactness of the glass network structure and help reduce boron volatilization, thereby enhancing the stability of the glass structure. In this invention, the molar ratio of B2O3 / H3BO3 is 5~6. The sum of P2O5 and NaF is 41.5~43.5, which helps to lower the glass softening point and increase the glass thermal expansion coefficient. At the same time, the combined use of P2O5 and NaF helps to improve the water resistance of the glass. In this invention, the molar ratio of P2O5 / NaF is 1.1~1.4. Introducing a sum of Al2O3 and B2O3 of 25~26.5 is beneficial for simultaneously improving the water resistance stability and thermal expansion coefficient of glass. The combined use can reduce the impact on the softening point. In this invention, the molar ratio of Al2O3 / B2O3 is 1.5~2.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. The glass formulation optimizes the network structure by adjusting the ratio of oxides such as P2O5, Al2O3, B2O3, NaF, and R2O, while improving the thermal expansion coefficient and water resistance stability of phosphate glass and resulting in a low sealing temperature.

[0028] 2. The glass powder prepared using this method has a controllable coefficient of thermal expansion. Sealing glass blanks I and II achieve different coefficients of thermal expansion by adjusting their oxide compositions. Combined gradient sealing is more beneficial for sealing copper and aluminum metals in power lithium battery electrodes, resulting in high thermal expansion matching. In other words, the sealing glass blank prepared by this invention has a high coefficient of thermal expansion (coefficient of thermal expansion at 300℃ > 160 × 10⁻⁶). -7 It has good water resistance (water resistance level 3 or above), low sealing temperature (sealing temperature < 550℃), high thermal expansion matching with sealing metal, and significantly improved sealing effect, meeting the performance requirements of copper and aluminum metals for sealing glass in power lithium battery electrodes. Attached Figure Description

[0029] Figure 1 A top view of a battery sealing cover assembly;

[0030] Figure 2 A cross-sectional view of a battery sealing cover assembly;

[0031] Figure 3 This is a test diagram of the sealing temperature in Example 1;

[0032] Figure 4 SEM image of the sintered surface in Example 1;

[0033] Figure 5 This is a SEM image of the sealing interface between the sealing glass and the aluminum shell in Example 1. Detailed Implementation

[0034] A method for preparing a battery sealing cover assembly, the specific embodiment of which uses the following operation steps:

[0035] (1) Prepare the ingredients according to Table 1 below, and mix each ingredient thoroughly in a mixer with zirconium balls for 2 hours to prepare mixture a and mixture b;

[0036] (2) Melt the mixture a in a high-temperature electric furnace, raise the temperature to 1200℃ according to the step temperature regime, and hold for 120 min to obtain clear glass liquid a; obtain glass liquid b by the same steps;

[0037] (3) After quenching the molten glass liquid a and glass liquid b in deionized water, take them out, dry them, grind them, and pass them through a 500-mesh sieve to obtain powder a and powder b.

[0038] (4) Mix 1000g of powder a with 810g of water, 66g of binder and 9.5g of coupling agent to make a slurry, and finally granulate it into balls in a spray granulator. Screen the glass powder a with a particle size distribution D50 of (100~110)μm; mix 1000g of powder a with 810g of water, 65g of binder (40g of carboxymethyl cellulose and 25g of polyvinyl alcohol) and 9.5g of coupling agent (γ-aminopropyltriethoxysilane) to make a slurry, and obtain glass powder b by the same steps;

[0039] (5) Glass powder a and glass powder b are used to prepare green blanks a and b by a servo powder molding machine. The molding pressure is 11 MPa. After complete debinding at room temperature, the temperature is raised to 450°C and held for 20 min to make sealed glass blanks I and II of the glass blanks.

[0040] (6) Assemble the aluminum shell to be sealed, the copper core column, and the sealing glass blanks I and II obtained in step (5) into a sealing assembly. Then, slowly heat the assembly to 530°C and hold it for 22 minutes in the furnace to seal it. The sealed assembly is then annealed in the furnace for 2.5 hours to room temperature to obtain the battery sealing cover assembly.

[0041] The coefficient of thermal expansion, softening point, and water resistance of the sealed glass blank were tested separately. After gradient sealing, the sealing temperature, sealing airtightness, and number of thermal cycles were tested. The coefficient of thermal expansion and softening point of the glass were tested according to GB 16920-2015 "Determination of the Average Linear Thermal Expansion Coefficient of Glass", the water resistance was tested according to GB / T 6582-1997 "Particle Test Method and Classification of Water Resistance of Glass at 98℃", the sealing temperature was tested according to GB / T 41742-2022 "Low Temperature Sealing Glass for Optoelectronic Devices", and the sealing airtightness and number of thermal cycles were tested according to GJB 360B-2009 "Test Methods for Electronic and Electrical Components".

[0042] As can be seen from the embodiments, the overall performance of the glass powder of the present invention is significantly better than that of traditional phosphate glass powder, especially in terms of thermal expansion coefficient, water resistance stability and sealing temperature. The sealing interface after the glass blank is gradient-sealed with the aluminum shell and copper core is free of defects such as cracks and bubbles, and exhibits excellent performance in terms of sealing airtightness and number of cold and hot cycles.

[0043]

Claims

1. A battery sealing cover assembly, comprising an aluminum casing and a copper core post, characterized in that... Sealing glass blank I and sealing glass blank II are made from raw materials in the following molar ratios: P2O5: 23~24.5%, Al2O3: 15.5~16.9%, B2O3: 9~10%, NaF: 18.5~19.5%, Li2O: 0.1~1%, Na2O: 11.5~12.5%, K2O: 11~11.8%, TiO2: 2.5~3%, SiO2: 4.5~5%, SrO: 0.1~0.5%, BaO: 0.1~0.5%; wherein the ratio of the thermal expansion coefficient of sealing glass blank I to that of sealing glass blank II is 1~1.4 and not 1.

2. The battery sealing cover assembly according to claim 1, characterized in that... Sealing glass blank I and sealing glass blank II are made from the following raw materials in the following molar ratios: P2O5: 23~24%, Al2O3: 15.8~16.5%, B2O3: 9.5~10%, NaF: 18.8~19.2%, Li2O: 0.1~0.5%, Na2O: 11.5~12.2%, K2O: 11~11.5%, TiO2: 2.5~2.8%, SiO2: 4.5~4.8%, SrO: 0.1~0.3%, BaO: 0.1~0.3%.

3. A method for preparing a battery sealing cover assembly, characterized in that... Includes the following steps: (1) Weigh two groups of materials according to the following molar ratios: P2O5: 23~24.5%, Al2O3: 15.5~16.9%, B2O3: 9~10%, NaF: 18.5~19.5%, Li2O: 0.1~1%, Na2O: 11.5~12.5%, K2O: 11~11.8%, TiO2: 2.5~3%, SiO2: 4.5~5%, SrO: 0.1~0.5%, BaO: 0.1~0.5%, and mix them evenly to obtain mixture a and mixture b; (2) Melt the mixture a in a high-temperature electric furnace, raise the temperature to 1000~1300℃ according to the step temperature system, and hold for 60~180min to obtain clear glass liquid a; obtain glass liquid b by the same steps; (3) After quenching the molten glass liquid a and glass liquid b in deionized water, take them out, dry them, grind them, and pass them through a 500-mesh sieve to obtain powder a and powder b. (4) Mix powder a with water, binder and coupling agent in a weight ratio of 52~56:42~46:3.1~4:0.4~0.6 to prepare a slurry, and finally granulate it into balls in a spray granulator. Screen the particles with a particle size distribution D50 of 80~120μm to obtain the desired glass powder a; mix powder b with water, binder and coupling agent in a weight ratio of 52~56:42~46:3.1~4:0.4~0.6 to prepare a slurry, and obtain glass powder b by the same steps; (5) Glass powder a and glass powder b are used to prepare green blanks a and b by a servo powder molding machine. After complete debinding at room temperature to 300°C, the temperature is raised to 370 to 500°C and held for 10 to 30 minutes to make sealing glass blank I and sealing glass blank II of glass blanks. (6) Assemble the aluminum shell to be sealed, the copper core column, and the sealing glass blanks I and II obtained in step (5) into a sealing assembly. Then, slowly heat the furnace to 490~540℃ and hold for 15~30 minutes to seal the assembly. Anneal the assembly in the furnace for 2~3 hours to room temperature to obtain the battery sealing cover assembly.

4. The method for preparing a battery sealing cover assembly according to claim 3, characterized in that: The mixing in step (1) is carried out using a mixer with added zirconium balls for 1-3 hours.

5. The method for preparing a battery sealing cover assembly according to claim 3, characterized in that: In step (5), the pressure of the pressing machine during the forming process is 10-12 MPa, and the porosity of the glass green body is 33-38%.

6. The method for preparing a battery sealing cover assembly according to claim 3, characterized in that: In step (5), the sintering shrinkage rate of sealing glass blank I and sealing glass blank II relative to the glass body is 10-11%.

7. The method for preparing a battery sealing cover assembly according to claim 3, characterized in that: In step (5), the ratio of the thermal expansion coefficient of sealing glass blank I to that of sealing glass blank II is 1 to 1.4 and is not 1.

8. The method for preparing a battery sealing cover assembly according to claim 3, characterized in that: In step (5), the ratio of the thermal expansion coefficient of sealing glass blank I to that of sealing glass blank II is 1.1 to 1.

3.

9. The method for preparing a battery sealing cover assembly according to claim 3, characterized in that: In step (5), the ratio of the outer diameter of the sealed glass blank II to the inner diameter of the sealed glass blank I after sintering is 0.9~1.

10. The method for preparing a battery sealing cap assembly according to claim 3, characterized in that: In step (5), the ratio of the outer diameter of the sealed glass blank II to the inner diameter of the sealed glass blank I after sintering is 0.95~1.

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