A method for preparing a flexible fiber-shaped lithium ion battery

Abstract

The present application relates to the field of flexible fiber lithium ion battery preparation process, in particular to a kind of preparation method of flexible fiber lithium ion battery, the method is mainly in the outer layer of the packaging pipe material of traditional flexible fiber lithium ion battery by winding and other measures even winding on a layer of aluminum plastic film packaging with mutual adhesion performance, the aluminum plastic film packaging adopts three-layer structure, outer layer is nylon protective layer, middle layer is metal such as aluminum, inner layer is high molecular material such as polypropylene. Compared with the prior art, the performance of the flexible fiber lithium ion battery prepared by the method of the present application is greatly improved in terms of cycle.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flexible weavable lithium ion battery manufacturing process, in particular to a flexible fiber-shaped lithium ion battery manufacturing method using a new packaging technology. BACKGROUND

[0002] In recent years, flexible wearable devices have been a research hotspot, and their applications are reflected in various aspects of people's lives, such as electronic skin, wearable physiological monitoring and treatment devices, flexible conductive fabric, transparent film flexible circuit, etc. However, the energy supply of flexible wearable devices also needs to meet the requirements of wearability, so flexible fiber-shaped lithium ion batteries have emerged as the times require. Compared with traditional non-flexible batteries and planar flexible batteries, flexible fiber-shaped lithium ion batteries have the advantages of weavability and multi-dimensional flexibility.

[0003] As an important performance indicator of all batteries, including flexible fiber-shaped lithium ion batteries, cycle performance will seriously affect the application of the battery. The packaging of traditional flexible fiber-shaped lithium ion batteries basically uses various polymer materials, but the water vapor transmission rate of polymer materials is high, and the water content has a fatal effect on the performance of the battery, which seriously affects the cycle performance of the battery, making it difficult to meet the application requirements of lithium ion batteries. SUMMARY

[0004] The purpose of the present application is to overcome the problem of high water vapor transmission rate of the polymer packaging material of the existing flexible fiber-shaped lithium ion battery, and to provide a flexible fiber-shaped lithium ion battery manufacturing method using a new packaging technology, which greatly solves the problem of high water vapor transmission rate and greatly improves the cycle performance of the battery, further promoting the application of flexible fiber-shaped lithium ion batteries.

[0005] The purpose of the present application can be achieved by the following technical solution: a flexible fiber-shaped lithium ion battery manufacturing method, comprising the following steps:

[0006] Step 1) removing the surface dirt of commercial aluminum wire and copper wire, and drying to obtain positive and negative current collectors;

[0007] Step 2) mixing the positive material, conductive agent and adhesive to prepare a positive slurry; mixing the negative material, conductive agent and adhesive to prepare a negative slurry;

[0008] Step 3) uniformly coating the positive and negative slurry prepared in step 2) on the aluminum wire and copper wire prepared in step 1) to prepare positive and negative electrodes, and then winding the positive or negative electrode on a layer of separator by winding equipment;

[0009] Step 4) preparing the positive and negative electrodes prepared in step 3) into a core with a mutual winding structure by a twisting device.

[0010] Step 5) The pipe is tightly and uniformly wrapped with an aluminum plastic film by a wrapping device, and then placed in an oven at 80-150℃ for high-temperature standing treatment for 1-2h, to prepare the pipe with the aluminum plastic film;

[0011] Step 6) The prepared battery cell in step 4) and the pipe with the aluminum plastic film obtained in step 5) are combined to prepare the flexible fiber-shaped lithium ion battery.

[0012] Further, the oil removal in step 1) is ultrasonic cleaning in an oil removal solution at 50-80℃ for 10-30min.

[0013] Further, the purity of the aluminum wire and the copper wire in step 1) is above 99%, or other metal wires with corresponding purity are used.

[0014] The positive electrode material in step 2) includes lithium cobalt oxide, lithium iron phosphate or ternary positive electrode material;

[0015] The negative electrode material includes graphite, lithium titanate or silicon-carbon material;

[0016] The conductive agent includes conductive carbon black, conductive graphite, carbon nanotube and graphene;

[0017] The binder includes polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene butadiene rubber or acrylonitrile multi-component copolymer.

[0018] Further, the mass ratio of the positive electrode material, the conductive agent and the binder in step 2) is 90-95:2-4:3-6;

[0019] The mass ratio of the negative electrode material, the conductive agent and the binder is 90-95.5:2-4:2-4.5.

[0020] The positive electrode material in step 2) includes lithium cobalt oxide, lithium iron phosphate or ternary positive electrode material;

[0021] The negative electrode material includes graphite, lithium titanate or silicon-carbon material;

[0022] The conductive agent includes conductive carbon black, conductive graphite, carbon nanotube and graphene;

[0023] The binder includes polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene butadiene rubber or acrylonitrile multi-component copolymer.

[0024] Further, the separator in step 3) uses one of polyethylene or polypropylene separators.

[0025] Further, the pipe material in step 5) is a high polymer pipe material, and one of polypropylene pipe material, polyethylene terephthalate pipe material or polytetrafluoroethylene pipe material is selected. The pipe material can be selected to have high acid and alkali stability, and the inner diameter is generally 0.5-2 mm and the outer diameter is generally 2-4 mm.

[0026] Further, the thickness of the aluminum-plastic film in step 5) is 10-100 μm. The selected aluminum-plastic film is divided into three layers, the outer layer is a wear-resistant nylon material layer, the middle layer is a water-resistant metal layer, and the inner layer is a fusion layer for bonding, and polypropylene or other materials with a melting point of about 200℃ are commonly used. Such materials can fully compensate for the poor water resistance of the internal pipe material, mainly through high-temperature fusion of the inner layer of the aluminum-plastic film and the pipe material itself, and the flexible structure of the pipe material after winding can maintain flexibility without being affected.

[0027] Further, the combination of the electric core and the pipe material with the aluminum-plastic film in step 6) is made into a flexible fiber-shaped lithium ion battery through switching, drying, liquid injection and sealing.

[0028] Further, the switching adopts a spot welding method, and an aluminum wire is used for positive switching, a copper wire is used for negative switching, or other metals are used for switching according to electrochemical stability; the electric core drying temperature is 80-100℃, and the time is 24-48 h.

[0029] Further, the flexible fiber-shaped lithium ion battery prepared by the above method is subjected to relevant electrochemical performance tests. The electrochemical performance test includes a cycle step, and the general charging and discharging is 0.3 / 0.5C, and the step can be adjusted according to the actual situation.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] 1.The present application is based on the traditional high polymer packaging material, and a new type of packaging material is prepared by winding a layer of aluminum plastic film on the basis of the traditional high polymer packaging material through wrapping, wherein the aluminum plastic film is composed of three layers of materials, the outermost layer is nylon, the middle layer is aluminum, and the inner layer is polypropylene or other materials, then the inner layer polypropylene or other materials are melted through high temperature treatment, so that the aluminum plastic film layer, the polymer pipe material matrix and the aluminum plastic film are bonded with each other, thereby preparing a new type of packaging material with flexibility and low water vapor transmission rate; then a flexible fiber lithium ion battery with new packaging technology is prepared by a series of preparation and assembly of flexible fiber lithium ion battery cells, which greatly reduces the water vapor transmission rate of the battery while ensuring the flexibility of the fiber lithium ion battery, and greatly improves the cycle performance of the battery. The existing soft package battery is packaged by using aluminum plastic film, but the existing aluminum plastic film structure cannot meet the packaging of one-dimensional structure of fiber battery, and the present application improves the structure of the aluminum plastic film to meet the structural characteristics and flexibility requirements of fiber battery, and also considers the combination with the internal pipe material, which can effectively meet the performance requirements of fiber battery.

[0032] 2.Compared with the traditional flexible fiber lithium ion battery packaged by high polymer material, the cycle performance of the flexible fiber lithium ion battery prepared by the present application is greatly improved, and the capacity retention rate after 300 cycles is increased by more than 60%, which provides an effective improvement idea for the development of subsequent fiber lithium ion battery. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Schematic diagram of new pipe packaging;

[0034] Figure 2 Comparison of cycle performance of batteries prepared by new and old packaging technologies in atmospheric environment. DETAILED DESCRIPTION

[0035] The present application will be further described in combination with specific embodiments, but the present application is not limited to the following embodiments.

[0036] In the following examples, the test methods are as described, unless otherwise specified, and the reagents and materials can be obtained by commercial means, unless otherwise specified.

[0037] Example 1

[0038] A method for preparing a flexible fiber lithium ion battery with new packaging technology, specifically comprising the following steps:

[0039] Step 1) Using a commercial metal wire cleaner solution to clean aluminum wire and copper wire with a purity of more than 99% at about 50℃ for 30min, and then drying after removing the surface oil for standby use;

[0040] Step 2) Prepare positive electrode slurry by mixing commercial lithium cobalt oxide, conductive agent (conductive carbon black) and binder (polyvinylidene fluoride) in a ratio of 95:2:3 using a slurry preparation device; prepare negative electrode slurry by mixing commercial graphite, conductive agent (conductive carbon black) and binder (sodium carboxymethyl cellulose and butadiene-styrene rubber) in a ratio of 95.5:2:(1:1.5) using a slurry preparation device;

[0041] Step 3) Uniformly coat the positive and negative electrode slurries prepared in (2) on the prepared aluminum and copper wires in (1) using a coating device to prepare positive and negative electrodes, and then uniformly wrap the negative electrode with a layer of separator (e.g. Clegard 2025) using a wrapping device;

[0042] Step 4) Prepare the positive electrode and negative electrode with separator prepared in (3) into a core with a mutual winding structure using a twisting device;

[0043] Step 5) Prepare a tube with an inner diameter of about 1.5 mm and an outer diameter of about 2.0 mm using an extruder and other basic equipment, then tightly and uniformly wrap the prepared tube with an outer layer of aluminum-plastic film with a thickness of about 100 μm using a wrapping device, and then place the prepared tube with aluminum-plastic film in an oven at about 150°C for about 2 hours of high-temperature static treatment to prepare the desired tube with aluminum-plastic film;

[0044] Step 6) Combine the prepared core and tube, and then perform processes such as switching, drying, liquid injection and sealing to prepare a flexible fiber-shaped lithium ion battery using a new packaging technology, and then complete related tests.

[0045] Performance detection:

[0046] 1. Water vapor transmission rate detection of different packaging materials, which uses infrared sensor method, refers to national standard GB / T 26253-2010, and uses MOCON water vapor permeability tester model 3 / 33ML.

[0047] Table 1 Comparison of water vapor transmission rates of different packaging materials

[0048]

[0049] Table 1 above shows a comparison of water vapor transmission rates for different encapsulation materials. Compared to traditional simple polymer encapsulation, the novel encapsulation technology used in this invention significantly reduces water vapor transmission rates, essentially approaching the level of commercial soft-pack battery aluminum-plastic film encapsulation. Commercial soft-pack battery aluminum-plastic film encapsulation is generally designed for three-dimensional structures such as sheet-like batteries. This structure cannot meet the one-dimensional encapsulation requirements of fiber batteries. This invention improves the structure, satisfying the structural characteristics and flexibility needs of fiber batteries, while also considering integration with internal tubing, effectively meeting the performance requirements of fiber batteries.

[0050] The flexible fibrous lithium-ion battery prepared using this invention can achieve a capacity retention of 80% after 240 cycles in an atmospheric environment, which is a significant improvement compared to the approximately 75 cycles achieved by traditional simple polymer encapsulation. This can basically meet the cycle requirements of ordinary 3C products.

[0051] Example 2

[0052] Step 1) Use a commercial metal wire cleaning solution to clean aluminum and copper wires with a purity of over 99% at around 50°C for 30 minutes to remove surface oil and then dry them for later use.

[0053] Step 2) Prepare a positive electrode slurry by mixing commercial lithium cobalt oxide, conductive agent (conductive graphite), and binder (polyvinylidene fluoride) in a ratio of 90:2:3 using a slurry mixing device; prepare a negative electrode slurry by mixing commercial graphite, conductive agent (conductive carbon black), and binder (styrene-butadiene rubber) in a ratio of 90:2:2 using a slurry mixing device.

[0054] Step 3) The positive and negative electrode slurries prepared in (2) are uniformly coated onto the aluminum and copper wires prepared in (1) using a coating device to prepare the positive and negative electrodes. Then, the negative electrode is uniformly wound using a wrapping device.

[0055] Wrap a diaphragm around it (taking Clegard 2025 as an example);

[0056] Step 4) The positive electrode and the negative electrode with a diaphragm prepared in (3) are used to prepare a battery cell with an intertwined structure by twisting equipment;

[0057] Step 5) Polyethylene terephthalate material is used to prepare pipes with an inner diameter of about 1.0 mm and an outer diameter of about 2.0 mm using basic equipment such as an extruder. Then, a strip of aluminum-plastic film with a thickness of about 80 μm is tightly and evenly wrapped around the outer layer of the prepared pipes using a wrapping device. Then, the prepared pipes with aluminum-plastic film are placed in an oven at about 100°C for high-temperature static treatment for about 1.5 hours to produce the desired pipes with aluminum-plastic film.

[0058] Step 6) combine the prepared battery cell and the pipe material, and then prepare a flexible fiber-shaped lithium ion battery using a new packaging technology through the processes of switching, drying, liquid injection, sealing, etc., and then complete the relevant tests.

[0059] The performance of the flexible fiber-shaped lithium ion battery obtained in Example 2 is as follows: water vapor transmission rate <0.005 g / m 2 ·day, and the cycle performance in the atmospheric environment can reach 250 cycles with a capacity retention rate of 80%.

[0060] Example 3

[0061] Step 1) clean the aluminum wire and copper wire with a purity of more than 99% at about 80°C for 10 min using a commercial metal wire cleaner solution, dry after removing the surface oil, and reserve for use;

[0062] Step 2) prepare positive electrode slurry by mixing commercial lithium cobaltate, conductive agent (conductive carbon black), and binder (polyvinylidene fluoride) in a ratio of 95:4:6 through a slurry mixing device; prepare negative electrode slurry by mixing commercial graphite, conductive agent (conductive carbon black), and binder (sodium carboxymethyl cellulose) in a ratio of 95.5:4:4.5 through a slurry mixing device;

[0063] Step 3) uniformly coat the prepared positive and negative electrode slurries in (2) on the prepared aluminum wire and copper wire in (1) through a coating device to prepare positive and negative electrodes, and then uniformly wrap the negative electrode with a layer of separator (for example, Clegard 2025) through a wrapping device;

[0064] Step 4) prepare an electrode cell with a mutual winding structure by twisting the prepared positive electrode in (3) and the negative electrode with a separator in (3) through a twisting device;

[0065] Step 5) prepare a pipe material with an inner diameter of about 1.0 mm and an outer diameter of about 2.0 mm through an extruder and other basic devices, then tightly and uniformly wrap the prepared pipe material with an outer layer of aluminum-plastic film with a thickness of about 80 μm through a wrapping device, and then prepare the pipe material with the aluminum-plastic film by placing it in a high-temperature oven at about 120°C for about 2 h of static treatment.

[0066] Step 6) combine the prepared battery cell and the pipe material, and then prepare a flexible fiber-shaped lithium ion battery using a new packaging technology through the processes of switching, drying, liquid injection, sealing, etc., and then complete the relevant tests.

[0067] The performance of the flexible fiber-shaped lithium ion battery obtained in Example 3 is as follows: water vapor transmission rate <0.005 g / m 2• day, the cycle performance in the atmospheric environment can reach 250 weeks capacity retention rate of 81% level.

Claims

1. A method for producing a flexible fibrous lithium-ion battery, characterized by, Specifically comprising the following steps: Step 1) remove surface oil of commercial aluminum wire and copper wire, and obtain positive and negative current collectors after drying; Step 2) mix positive material, conductive agent and adhesive to prepare positive slurry; mix negative material, conductive agent and adhesive to prepare negative slurry; Step 3) evenly coat the positive and negative slurry prepared in step 2) on the aluminum wire and copper wire prepared in step 1) respectively to prepare positive and negative electrodes, and then evenly wrap a layer of separator on the positive or negative electrode through a wrapping device; Step 4) prepare the positive and negative electrodes prepared in step 3) into a core through a twisting device in a mutual winding structure; Step 5) tightly and evenly wrap a layer of strip-shaped aluminum plastic film on the outer layer of the pipe material through a wrapping device, and then place it in an oven at 120-150 ℃ for high-temperature standing treatment for 1-2 h to prepare a pipe material with aluminum plastic film; the thickness of the strip-shaped aluminum plastic film is 10-100 μm; the pipe material is a polypropylene polymer pipe material, a polyethylene terephthalate polymer pipe material or a polytetrafluoroethylene polymer pipe material; the inner diameter of the pipe material is 0.5-2 mm; The aluminum plastic film is composed of three layers of materials, the outermost layer is nylon, the middle layer is aluminum, and the inner layer is polypropylene material. After the aluminum plastic film is wound on the surface of the pipe material, the inner layer of polypropylene material melts during high-temperature treatment, thereby bonding the aluminum plastic film and the polymer pipe material substrate, and preparing an encapsulation material with flexibility and low water vapor transmission rate; Step 6) combine the core prepared in step 4) and the pipe material with aluminum plastic film obtained in step 5) to prepare a flexible fiber-shaped lithium ion battery.

2. The method for preparing a flexible fibrous lithium-ion battery according to claim 1, characterized in that, Step 1) oil removal is ultrasonic cleaning in an oil removal solution at a temperature of 50-80 ℃ for 10-30 min.

3. The method for preparing a flexible fibrous lithium-ion battery according to claim 1, characterized in that, The purity of the aluminum wire and copper wire in step 1) is above 99%.

4. The method for preparing a flexible fibrous lithium-ion battery according to claim 1, characterized in that, The mass ratio of the positive material, conductive agent and adhesive in step 2) is 90-95:2-4:3-6; The mass ratio of the negative material, conductive agent and adhesive is 90-95.5:2-4:2-4.

5.

5. A method for preparing a flexible fibrous lithium-ion battery according to claim 4, characterized in that, The positive material in step 2) includes lithium cobaltate, lithium iron phosphate or ternary positive material; The negative material includes graphite, lithium titanate or silicon-carbon material; The conductive agent includes conductive carbon black, conductive graphite, carbon nanotube and graphene; The adhesive includes polyvinylidene fluoride, sodium carboxymethyl cellulose, butadiene rubber or polyacrylonitrile multicomponent copolymer.

6. A method for preparing a flexible fibrous lithium-ion battery according to claim 1, characterized in that, The separator in step 3) is polyethylene or polypropylene.

7. A method for preparing a flexible fibrous lithium-ion battery according to claim 1, characterized in that, The core and the pipe material with aluminum plastic film are combined in step 6) to prepare a flexible fiber-shaped lithium ion battery through switching, drying, liquid injection and sealing.

8. A method for preparing a flexible fibrous lithium-ion battery according to claim 7, characterized in that, The switching adopts spot welding, the positive switching aluminum wire and the negative switching copper wire; the core drying temperature is 80-100 ℃, and the time is 24-48 h.

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