Aluminum composite film for lithium manganese battery cap

Abstract

The application discloses an aluminum composite film for a lithium manganese battery cap, and particularly relates to the technical field of lithium manganese batteries, and comprises a four-layer structure, the four-layer structure is sequentially provided with a protective layer, an intermediate layer, a composite layer and a heat-sealing layer from outside to inside, the protective layer, the intermediate layer, the composite layer and the heat-sealing layer are respectively a first PET layer, an aluminum foil layer, a second PET layer and a modified PE layer, adjacent structure layers are bonded together through an adhesive, raw materials of the modified PE layer comprise PE particles, EVA particles and PTFE particles, and the adding percentages of the PE particles, the EVA particles and the PTFE particles are 60-80%, 10-20% and 10-20% respectively. A disposable lithium manganese dioxide battery is made of the aluminum composite film of the application and a cap combination, the battery has a long storage life, a low self-discharge rate during long-time storage, and a battery internal resistance that does not increase with the growth of storage time, and the battery has better electrical performance and higher capacity.

Description

Technical Field

[0001] This invention relates to the field of lithium manganese battery technology, and more specifically to an aluminum composite film for lithium manganese battery caps. Background Technology

[0002] Aluminum-plastic film is a multilayer film composed of an outer (protective) nylon or PET layer, an adhesive, an intermediate layer, aluminum foil, and an inner heat-sealing layer. The outermost layer, typically 15-25 μm thick, prevents the intermediate aluminum foil from being scratched. The intermediate aluminum foil layer, typically 35-40 μm thick, prevents oxygen and moisture intrusion. The innermost layer is usually polyethylene, typically 40-80 μm thick. The polyethylene separates the aluminum from the battery cell, providing insulation, resistance to electrolyte corrosion, and encapsulation. Aluminum-plastic film possesses extremely high barrier properties, good heat-sealing performance, resistance to electrolytes and strong acids, and good ductility, flexibility, and mechanical strength.

[0003] Currently, all disposable lithium manganese dioxide batteries are semi-sealed, using an old process material, aluminum-plastic film, to seal the battery. This results in problems such as high internal resistance, low battery capacity, and relatively short storage life after long-term storage. Summary of the Invention

[0004] To overcome the above-mentioned defects of the prior art, the present invention provides an aluminum composite film for the cap of a lithium manganese battery. A disposable lithium manganese dioxide battery with a cap assembly made from the aluminum composite film of the present invention has a long storage life, a low self-discharge rate during long-term storage, and its internal resistance does not increase with the storage time. The battery has better electrical performance and higher capacity.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an aluminum composite film for lithium manganese battery caps, comprising a four-layer structure, wherein the four layers are, from the outside to the inside, a protective layer, an intermediate layer, a composite layer and a heat-sealing layer, wherein the protective layer, intermediate layer, composite layer and heat-sealing layer are respectively a first PET (polyethylene terephthalate) layer, an aluminum foil layer, a second PET layer and a modified PE layer, and adjacent structural layers are bonded together with an adhesive.

[0006] PET has good mechanical properties, high impact strength, good folding resistance, and is resistant to oil, grease, dilute acids, dilute alkalis and most solvents. PET can be used for a long time in the temperature range of 55-60℃ and can withstand high temperature of 65℃ and low temperature of -70℃. It has low gas and water vapor permeability, which means it has excellent barrier properties against gas, water, oil and odor. It is non-toxic, odorless and has good hygiene and safety.

[0007] Aluminum foil is moisture-proof, airtight, light-shielding, and abrasion-resistant, and has shielding properties against water vapor, air, ultraviolet rays, and bacteria.

[0008] The raw materials for the modified PE layer include PE (polyethylene) particles, EVA (ethylene-vinyl acetate copolymer) particles, and PTFE (polytetrafluoroethylene) particles, with the percentages of PE particles, EVA particles, and PTFE particles being 60-80%, 10-20%, and 10-20%, respectively.

[0009] PE is resistant to most acids and alkalis, has low water absorption, maintains its flexibility at low temperatures, and has high electrical insulation.

[0010] EVA has good chemical stability, aging resistance, and ozone resistance.

[0011] PTFE has the advantages of high temperature resistance, low temperature resistance, corrosion resistance, weather resistance, and electrical insulation.

[0012] Preferably, the percentages of PE particles, EVA particles, and PTFE particles added are 60%, 20%, and 20%, respectively.

[0013] Preferably, the percentages of PE particles, EVA particles, and PTFE particles added are 70%, 15%, and 15%, respectively.

[0014] Preferably, the percentages of PE particles, EVA particles, and PTFE particles added are 80%, 10%, and 10%, respectively.

[0015] Preferably, the adhesive is a polyurethane adhesive, which has good resistance to water, oil, solvents, chemicals, ozone, and bacteria, as well as good flexibility, resistance to low and ultra-low temperatures, wear resistance, flexural strength, and bending fatigue resistance.

[0016] Preferably, the outer surface of the protective layer is provided with a protective coating, which is obtained by drying a paint coating.

[0017] By percentage, the raw materials of the coating include 65% waterborne polyurethane, 12% cationic chloroprene latex, 8% mica powder and 15% flame retardant masterbatch.

[0018] Waterborne polyurethane is a waterproof material that is non-toxic and odorless. It has good adhesion and impermeability, strong adhesion, stable chemical properties, high elongation, and good waterproof effect.

[0019] Cationic chloroprene latex is made by mixing high molecular polymers, special cementitious materials, and high-quality aggregates through a special process. It has excellent bonding, crack resistance, freeze resistance, seepage prevention, corrosion resistance, wear resistance, and aging resistance.

[0020] Mica powder has excellent elasticity, toughness, insulation, high temperature resistance, acid and alkali resistance, corrosion resistance, and strong adhesion.

[0021] Flame retardant masterbatch is a white granular substance made from polyester resin as the main raw material, with the addition of various additives through plasticizing, mixing and granulation. It has excellent flame retardant properties and processing flow properties.

[0022] This invention also includes a process for preparing an aluminum composite film for lithium manganese battery caps, the specific steps of which are as follows:

[0023] Step 1: Bond the modified PE layer and the PET layer of the composite layer together with an adhesive. Then, bond the aluminum foil layer of the middle layer to the outer surface of the PET layer with an adhesive. Finally, bond the PET layer of the protective layer to the outer surface of the aluminum foil layer with an adhesive.

[0024] Step 2: Finally, apply a protective coating to the outer surface of the protective layer and let it dry to obtain the aluminum composite film for the lithium manganese battery cap.

[0025] Preferably, the intermediate layer is prepared by heating aluminum metal to molten, then injecting the molten aluminum metal into a continuous casting machine, pressing the aluminum metal into an aluminum plate by the action of rollers, and finally sending the aluminum plate into a rolling mill to be rolled into an aluminum foil layer.

[0026] Preferably, the method for preparing the modified PE layer is as follows:

[0027] S1: Mix PE granules, EVAE granules and PTFEE granules, feed the mixture into an extruder, and heat and melt it to make it into a molten state.

[0028] S2: Use an extruder to extrude the molten mixture into a continuous film.

[0029] S3: The extruded film is rapidly cooled by cooling rollers or cooling fans to solidify it. The solidified film is then stretched and calendered to prepare a modified PE layer.

[0030] Preferably, the protective coating is prepared by adding waterborne polyurethane and cationic chloroprene latex into a stirring vessel, heating to 50-150°C and stirring, then adding mica powder and flame retardant masterbatch, heating to 200-300°C to obtain the protective coating.

[0031] The technical effects and advantages of this invention are as follows:

[0032] The aluminum composite film of the present invention is formed by bonding and fixing a first PET layer, an aluminum foil layer, a second PET layer and a modified PE layer together with an adhesive in one step, thereby improving the high temperature resistance of the aluminum composite film, giving the aluminum composite film barrier properties against electrolyte, water and gas, and improving the stiffness of the aluminum composite film, which is beneficial to the processing and forming of the aluminum composite film.

[0033] The protective coating prepared by this invention has excellent waterproof performance, wear resistance, aging resistance, high temperature resistance, acid and alkali resistance, corrosion resistance, etc., and has strong adhesion, which can be stably attached to the outside of the protective layer and is not easy to fall off. By spraying a protective coating on the outside of the protective layer, the aluminum composite film prepared by this invention has better performance in blocking electrolyte, water and gas.

[0034] The disposable lithium manganese dioxide battery with a cap assembly made from the aluminum composite film of the present invention has a long storage life, low self-discharge rate during long-term storage, and its internal resistance does not increase with storage time. The battery has better electrical performance and higher capacity. Attached Figure Description

[0035] Figure 1 This is a structural diagram of the aluminum composite film of the lithium manganese battery cap of the present invention.

[0036] Figure 2 This is a comparison chart showing the weight loss rate of aluminum-plastic film batteries using the old process and those using the new process, stored at 60℃.

[0037] Figure 3 This is a comparison chart of the internal resistance of aluminum-plastic film batteries using the old process and those using the new process, stored at 60°C.

[0038] The attached diagram is labeled as follows: 1. Protective layer, 2. Intermediate layer, 3. Composite layer, 4. Heat-sealing layer, 5. Protective coating. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0040] like Figure 1 As shown, the present invention provides an aluminum composite film for lithium manganese battery caps, comprising a four-layer structure, wherein the four layers are, from the outside to the inside, a protective layer 1, an intermediate layer 2, a composite layer 3 and a heat-sealing layer 4. The protective layer 1, the intermediate layer 2, the composite layer 3 and the heat-sealing layer 4 are respectively a first PET layer, an aluminum foil layer, a second PET layer and a modified PE layer, and adjacent structural layers are bonded together with an adhesive.

[0041] The raw materials for the modified PE layer include PE particles, EVA particles and PTFE particles, with the percentages of PE particles, EVA particles and PTFE particles being 60%, 20% and 20%, respectively.

[0042] The adhesive is a polyurethane adhesive.

[0043] The outer surface of the protective layer 1 is provided with a protective coating 5, which is obtained by drying a paint.

[0044] By percentage, the raw materials of the coating include 65% waterborne polyurethane, 12% cationic chloroprene latex, 8% mica powder and 15% flame retardant masterbatch.

[0045] The present invention also provides a process for preparing the aluminum composite film for lithium manganese battery caps, the specific steps of which are as follows:

[0046] Step 1: Preparation of the modified PE layer:

[0047] S1: Mix PE granules, EVAE granules and PTFEE granules, feed the mixture into an extruder, and heat and melt it to make it into a molten state.

[0048] S2: Use an extruder to extrude the molten mixture into a continuous film.

[0049] S3: The extruded film is rapidly cooled by cooling rollers or cooling fans to solidify it. The solidified film is then stretched and calendered to prepare a modified PE layer.

[0050] Step 2, Preparation of intermediate layer 2: Heat aluminum metal to melt, then inject the molten aluminum metal into a continuous casting machine. Through the action of rollers, the aluminum metal is pressed into an aluminum plate. Finally, the aluminum plate is sent into a rolling mill to be rolled into an aluminum foil layer.

[0051] Step 3: Preparation of protective coating 5. Waterborne polyurethane and cationic chloroprene latex are added to a mixing tank, heated to 50°C and stirred. Then mica powder and flame retardant masterbatch are added, and the temperature is raised to 200°C to obtain protective coating 5.

[0052] Step 4: Adhere the modified PE layer to the PET layer of composite layer 3 together with an adhesive. Then, adhere the aluminum foil layer of intermediate layer 2 to the outer surface of the PET layer with an adhesive. Finally, adhere the PET layer of protective layer 1 to the outer surface of the aluminum foil layer with an adhesive.

[0053] Step 5: Finally, apply protective coating 5 to the outer surface of protective layer 1 and let it dry to obtain the aluminum composite film of the lithium manganese battery cap. Example 2

[0054] like Figure 1 As shown, the present invention provides an aluminum composite film for lithium manganese battery caps, comprising a four-layer structure, wherein the four layers are, from the outside to the inside, a protective layer 1, an intermediate layer 2, a composite layer 3 and a heat-sealing layer 4. The protective layer 1, the intermediate layer 2, the composite layer 3 and the heat-sealing layer 4 are respectively a first PET layer, an aluminum foil layer, a second PET layer and a modified PE layer, and adjacent structural layers are bonded together with an adhesive.

[0055] The raw materials for the modified PE layer include PE particles, EVA particles and PTFE particles, with the percentages of PE particles, EVA particles and PTFE particles being 70%, 15% and 15%, respectively.

[0056] The adhesive is a polyurethane adhesive.

[0057] The outer surface of the protective layer 1 is provided with a protective coating 5, which is obtained by drying a paint.

[0058] By percentage, the raw materials of the coating include 65% waterborne polyurethane, 12% cationic chloroprene latex, 8% mica powder and 15% flame retardant masterbatch.

[0059] The present invention also provides a process for preparing the aluminum composite film for lithium manganese battery caps, the specific steps of which are as follows:

[0060] Step 1: Preparation of the modified PE layer:

[0061] S1: Mix PE granules, EVAE granules and PTFEE granules, feed the mixture into an extruder, and heat and melt it to make it into a molten state.

[0062] S2: Use an extruder to extrude the molten mixture into a continuous film.

[0063] S3: The extruded film is rapidly cooled by cooling rollers or cooling fans to solidify it. The solidified film is then stretched and calendered to prepare a modified PE layer.

[0064] Step 2, Preparation of intermediate layer 2: Heat aluminum metal to melt, then inject the molten aluminum metal into a continuous casting machine. Through the action of rollers, the aluminum metal is pressed into an aluminum plate. Finally, the aluminum plate is sent into a rolling mill to be rolled into an aluminum foil layer.

[0065] Step 3: Preparation of protective coating 5. Waterborne polyurethane and cationic chloroprene latex are added to a mixing tank, heated to 100°C and stirred. Then mica powder and flame retardant masterbatch are added, and the temperature is raised to 250°C to obtain protective coating 5.

[0066] Step 4: Adhere the modified PE layer to the PET layer of composite layer 3 together with an adhesive. Then, adhere the aluminum foil layer of intermediate layer 2 to the outer surface of the PET layer with an adhesive. Finally, adhere the PET layer of protective layer 1 to the outer surface of the aluminum foil layer with an adhesive.

[0067] Step 5: Finally, apply protective coating 5 to the outer surface of protective layer 1 and let it dry to obtain the aluminum composite film of the lithium manganese battery cap. Example 3

[0068] like Figure 1As shown, the present invention provides an aluminum composite film for lithium manganese battery caps, comprising a four-layer structure, wherein the four layers are, from the outside to the inside, a protective layer 1, an intermediate layer 2, a composite layer 3 and a heat-sealing layer 4. The protective layer 1, the intermediate layer 2, the composite layer 3 and the heat-sealing layer 4 are respectively a first PET layer, an aluminum foil layer, a second PET layer and a modified PE layer, and adjacent structural layers are bonded together with an adhesive.

[0069] The raw materials for the modified PE layer include PE particles, EVA particles and PTFE particles, with the percentages of PE particles, EVA particles and PTFE particles being 80%, 10% and 10%, respectively.

[0070] The adhesive is a polyurethane adhesive.

[0071] The outer surface of the protective layer 1 is provided with a protective coating 5, which is obtained by drying a paint.

[0072] By percentage, the raw materials of the coating include 65% waterborne polyurethane, 12% cationic chloroprene latex, 8% mica powder and 15% flame retardant masterbatch.

[0073] The present invention also provides a process for preparing the aluminum composite film for lithium manganese battery caps, the specific steps of which are as follows:

[0074] Step 1: Preparation of the modified PE layer:

[0075] S1: Mix PE granules, EVAE granules and PTFEE granules, feed the mixture into an extruder, and heat and melt it to make it into a molten state.

[0076] S2: Use an extruder to extrude the molten mixture into a continuous film.

[0077] S3: The extruded film is rapidly cooled by cooling rollers or cooling fans to solidify it. The solidified film is then stretched and calendered to prepare a modified PE layer.

[0078] Step 2, Preparation of intermediate layer 2: Heat aluminum metal to melt, then inject the molten aluminum metal into a continuous casting machine. Through the action of rollers, the aluminum metal is pressed into an aluminum plate. Finally, the aluminum plate is sent into a rolling mill to be rolled into an aluminum foil layer.

[0079] Step 3: Preparation of protective coating 5. Waterborne polyurethane and cationic chloroprene latex are added to a mixing tank, heated to 150°C and stirred. Then mica powder and flame retardant masterbatch are added, and the temperature is raised to 300°C to obtain protective coating 5.

[0080] Step 4: Adhere the modified PE layer to the PET layer of composite layer 3 together with an adhesive. Then, adhere the aluminum foil layer of intermediate layer 2 to the outer surface of the PET layer with an adhesive. Finally, adhere the PET layer of protective layer 1 to the outer surface of the aluminum foil layer with an adhesive.

[0081] Step 5: Finally, apply protective coating 5 to the outer surface of protective layer 1 and let it dry to obtain the aluminum composite film of the lithium manganese battery cap.

[0082] Taking the CR123A battery as an example, the electrical performance and battery sealing tests of CR123A batteries with caps made using the old process material aluminum composite film and those made using the new process material aluminum composite film are as follows:

[0083] (1) Electrical performance testing and battery sealing test of CR123A battery with aluminum composite film from old process materials:

[0084] a. Storage period test (20 samples were taken, and the average value was taken after the test).

[0085] b. Store at a constant temperature of 60℃ for 20 days, which is equivalent to 1 year; discharge capacity is achieved by constant current discharge of 20mA, with a termination voltage of 2.0V;

[0086]

[0087] (2) Electrical performance testing and battery sealing test of CR123A battery with aluminum composite film of new process material:

[0088] c. Storage period test (20 samples were taken, and the average value was taken after the test):

[0089] d. Store at a constant temperature of 60℃ for 20 days, which is equivalent to 1 year; discharge capacity is achieved by constant current discharge of 20mA, with a termination voltage of 2.0V;

[0090]

[0091] like Figure 1 A comparison chart of weight loss rates of aluminum-plastic film batteries using the old process and those using the new process, stored at 60°C. Figure 2 This is a comparison chart of the internal resistance of aluminum-plastic film batteries using the old process and those using the new process, stored at 60°C.

[0092] The storage life of a disposable lithium manganese dioxide battery with a cap assembly made of aluminum composite film using old process materials is generally 3-5 years. The cap assembly made of aluminum composite film using the new process materials of this invention can extend the storage life of the battery to 8-10 years. The internal resistance of the battery made with the new process aluminum composite film does not increase with the storage time, but remains at around 300 milliohms, resulting in better electrical performance and higher capacity.

[0093] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An aluminum composite film for lithium manganese battery caps, characterized in that, It includes a four-layer structure, which consists of a protective layer (1), an intermediate layer (2), a composite layer (3), and a heat-sealing layer (4) from the outside to the inside. The protective layer (1), intermediate layer (2), composite layer (3), and heat-sealing layer (4) are respectively a first PET layer, an aluminum foil layer, a second PET layer, and a modified PE layer. Adjacent structural layers are bonded together with an adhesive. The raw materials for the modified PE layer include PE particles, EVA particles, and PTFE particles, with the percentages of PE particles, EVA particles, and PTFE particles being 60-80%, 10-20%, and 10-20%, respectively. The outer surface of the protective layer (1) is provided with a protective coating (5), which is obtained by drying the coating. The preparation method of the protective coating (5) is as follows: water-based polyurethane and cationic chloroprene latex are added to a stirring tank, heated to 50-150℃ and stirred, then mica powder and flame retardant masterbatch are added, and the temperature is raised to 200-300℃ to obtain the protective coating (5).

2. The aluminum composite film for a lithium manganese battery cap according to claim 1, characterized in that, The percentages of PE particles, EVA particles, and PTFE particles added are 60%, 20%, and 20%, respectively.

3. The aluminum composite film for a lithium manganese battery cap according to claim 1, characterized in that, The percentages of PE particles, EVA particles, and PTFE particles added are 70%, 15%, and 15%, respectively.

4. The aluminum composite film for a lithium manganese battery cap according to claim 1, characterized in that, The percentages of PE particles, EVA particles, and PTFE particles added are 80%, 10%, and 10%, respectively.

5. The aluminum composite film for a lithium manganese battery cap according to claim 1, characterized in that, The adhesive is a polyurethane adhesive.

6. The aluminum composite film for a lithium manganese battery cap according to claim 1, characterized in that, The raw materials of the protective coating (5) by percentage include 65% waterborne polyurethane, 12% cationic chloroprene latex, 8% mica powder and 15% flame retardant masterbatch.

7. A process for preparing an aluminum composite film for a lithium manganese battery cap according to any one of claims 1-6, characterized in that, The specific steps are as follows: Step 1: Bond the modified PE layer and the PET layer of the composite layer (3) together with an adhesive, then bond the aluminum foil layer of the intermediate layer (2) to the outer surface of the PET layer with an adhesive, and then bond the PET layer of the protective layer (1) to the outer surface of the aluminum foil layer with an adhesive. Step 2: Finally, after applying a protective coating (5) to the outer surface of the protective layer (1) and letting it dry, the aluminum composite film of the lithium manganese battery cap is obtained.

8. The preparation process of an aluminum composite film for a lithium manganese battery cap according to claim 7, characterized in that, The preparation method of the intermediate layer (2) is as follows: aluminum metal is heated to melt, and then the molten aluminum metal is injected into a continuous casting machine. Through the action of rollers, the aluminum metal is pressed into an aluminum plate. Finally, the aluminum plate is sent into a rolling mill to be rolled into an aluminum foil layer.

9. The preparation process of an aluminum composite film for a lithium manganese battery cap according to claim 7, characterized in that, The method for preparing the modified PE layer is as follows: S1: Mix PE granules, EVA granules and PTFE granules, feed the mixture into an extruder, and heat and melt it to make it into a molten state; S2: Use an extruder to extrude the molten mixture into a continuous film; S3: The extruded film is rapidly cooled by cooling rollers or cooling fans to solidify it. The solidified film is then stretched and calendered to prepare a modified PE layer.

Images