Preparation method of ultrahigh-rate elliptical polymer lithium ion battery for electronic cigarette

Abstract

The invention relates to the technical field of lithium battery production, in particular to a preparation method of an ultrahigh-rate elliptical polymer lithium ion battery for an electronic cigarette, which comprises the following steps: 1) preparation of a positive plate: dispersing a positive active material lithium cobalt oxide, a binder PVDF, a conductive agent and Al2O3 in N-methyl pyrrolidone to obtain uniform positive slurry; a plurality of tabs are bent in a Z shape after being welded and then are welded to a wide lead-out tab, so that external connection and current lead-out of the battery are facilitated, the length of the tabs of the pole piece is designed, the height of tab glue is 5-10mm, after the tabs of the inner ring and the outer ring are bent in the Z shape, the tabs are located in the center of an ellipse, and the vertical height of the tab glue is 3-5mm away from the cross section of a roll core. The risk that the tabs fall off due to vibration or impact is reduced, and the durability and the reliability of the battery are improved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer lithium battery production, and in particular to a method for preparing an ultra-high rate elliptical polymer lithium ion battery for electronic cigarettes. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density and cycle efficiency, low self-discharge, and no memory effect, and are widely used in modern society. With the extensive use of lithium-ion batteries in electronic products, their models, specifications, and usage functions are also constantly diversifying. The requirements of the electronic cigarette market for lithium batteries are also constantly increasing. Batteries with long cycles, high voltages, and low internal resistance are more likely to occupy the market. The larger the amount of smoke experienced by customers, the better the taste, and the longer the discharge, the more popular the electronic cigarette batteries are. According to the law of conservation of energy, batteries with high internal resistance, in addition to the conversion of electrical energy during the battery discharge process, also have a part of the energy converted into heat and lost. However, the elliptical polymer battery used in electronic cigarettes is limited by the shape and the characteristics of the ear glue packaging. The internal structure of the single coil core is difficult to break through the internal resistance constraint, resulting in a bottleneck in the discharge rate. The ear of the traditional lithium battery is welded separately on the aluminum foil or copper foil coated with the positive or negative electrode material, and there is only one positive and negative ear. In the actual charging process, the welding of the single ear has a large resistance, a small discharge current, poor rate performance, and serious battery heating, poor cycle performance, and certain safety hazards.

[0003] The various types of battery designs currently on the market are changing their internal structural designs. For example, the three-core and four-core parallel connection inside aluminum shell batteries; the stacking design of soft-pack batteries; the multi-electrode design of steel shell batteries, etc. However, elliptical polymer batteries for electronic cigarettes have not been able to achieve such designs for the following reasons:

[0004] 1) Polymer batteries cannot be combined according to the aluminum shell, plastic shell, and steel shell battery structure, and multiple tabs cannot be connected to the cap or cover plate using laser welding or riveting technology.

[0005] 2) The heat sealing between the ear glue and the aluminum-plastic film of the polymer soft-pack elliptical battery can only be completed by a single ear. The two overlapping ear glues will leak after being heat-sealed in parallel;

[0006] 3) Elliptical polymer soft-pack batteries cannot adopt stacked and parallel core designs;

[0007] 4) The e-cigarette battery market determines the negative tolerance of battery size design, and there is no extra structural space inside. Summary of the invention

[0008] (I) Purpose of the invention

[0009] In view of this, the purpose of the present invention is to propose a method for preparing an ultra-high rate elliptical polymer lithium-ion battery for electronic cigarettes, which solves the problems raised in the above background.

[0010] (II) Technical solution

[0011] A method for preparing an ultra-high rate elliptical polymer lithium-ion battery for electronic cigarettes comprises the following steps:

[0012] 1) Preparation of positive electrode:

[0013] The positive electrode active material is lithium cobalt oxide, the binder is PVDF, the conductive agent and Al 2 O 3 Dispersed in N-methylpyrrolidone to obtain a uniform positive electrode slurry;

[0014] The positive electrode slurry contains 96.0 wt% of positive electrode active material, 1.5 wt% of PVDF binder, 0.5 wt% of multi-walled carbon nanotubes CNT, 0.5 wt% of super conductive carbon black, and 1.5 wt% of Al 2 O 3 ; The above is an ultra-high ratio ratio;

[0015] The positive electrode slurry is evenly coated on two surfaces of the aluminum foil, dried, and compacted by a roller press to obtain a positive electrode sheet;

[0016] 2) Preparation of negative electrode sheet:

[0017] The negative electrode active material graphite, binder SBR, thickener CMC and conductive carbon black, Al 2 O 3 Mix and disperse in deionized water to obtain negative electrode slurry;

[0018] The solid components of the negative electrode slurry include 94.5 wt% graphite, 1.5 wt% CMC, 1.0 wt% conductive carbon black, 1.5 wt% Al 2 O 3 , 1.5wt% SBR;

[0019] The negative electrode slurry is evenly coated on two surfaces of the copper foil, and then dried and compacted by a roller press to obtain a negative electrode sheet;

[0020] 3) Preparation of battery cells:

[0021] The positive and negative electrodes prepared above were welded to two 6mm aluminum strips and nickel strips respectively, and then the core was obtained by winding the same diaphragm (glue coated + ceramic coated 12+2+2μm). The core was flattened (with the pole ear centered), baked at 85℃ for 4h, and the positive and negative electrodes were respectively equipped with PP spacer gaskets designed according to the dimensions after pressing the core, and then ultrasonically welded with aluminum strips and nickel strips; then, they were welded to 10mm pole ears (positive aluminum to nickel / negative nickel pole ears), protected by glue, folded pole ears, packaged, baked, injected with liquid, hot pressed at high temperature, and divided into different capacities to obtain the battery cell.

[0022] Preferably, the number of pole tabs of the positive electrode sheet and the negative electrode sheet is a double-pole tab design, and a corrosion-resistant polymer PP material gasket is selected under the pole tab to improve the safety of the internal structure of the battery.

[0023] Preferably, the diaphragm is a diaphragm coated with glue and ceramic coating to improve the safety and performance of the battery.

[0024] Preferably, after welding, the plurality of tabs are bent in a "Z-shape" and then welded to a wider lead-out tab to facilitate external connection of the battery and current extraction.

[0025] Preferably, the preparation process of the battery cell also includes liquid injection, high temperature hot pressing and capacity separation steps to ensure the performance and quality of the battery cell.

[0026] Preferably, the overall design of the battery cell further includes using a tab glue to seal between the tab and the aluminum-plastic film to enhance the packaging effect and safety of the battery cell.

[0027] It can be seen from the above technical solutions that the present application has the following beneficial effects:

[0028] The invention reduces the internal resistance by changing the internal structure design, thereby achieving an elliptical polymer lithium-ion battery for electronic cigarettes with a continuous rate of more than 25C or an output current discharge of 40A, which has the following advantages:

[0029] 1. The invention designs the position of the pole piece and the pole lug. After the pole piece is wound into a core and subjected to hot pressing and shaping, the two pole lugs of the positive electrode overlap within a range of 3-5 mm for internal welding, which reduces the error in the welding process and makes the internal connection of the battery more stable, thereby improving the overall performance and safety of the battery.

[0030] 2. The length of the pole piece and the pole ear of the invention is designed, and the pole ear glue is 5-10mm high. After the inner and outer ring pole ears are welded and bent in a "Z" shape, the pole ear is in the center of the ellipse, and the pole ear glue is vertically 3-5mm above the cross-section of the winding core, which reduces the risk of the pole ear falling off due to vibration or impact and improves the durability and reliability of the battery.

[0031] 3. The invention has a short-circuit-proof design, and a PP gasket resistant to electrolyte corrosion is used between the tab and the core. After the tab is sealed and folded, the tab welding position will not break the core diaphragm, causing a short circuit or micro-short circuit inside the battery, which helps to reduce the defective rate in the production process, improve production efficiency, and also help protect the internal structure of the battery and extend the battery life. DETAILED DESCRIPTION

[0032] An embodiment provided by the present invention:

[0033] A method for preparing an ultra-high rate elliptical polymer lithium-ion battery for electronic cigarettes comprises the following steps:

[0034] 1) Preparation of positive electrode:

[0035] The positive electrode active material is lithium cobalt oxide, the binder is PVDF, the conductive agent and Al 2 O 3 Dispersed in N-methylpyrrolidone to obtain a uniform positive electrode slurry;

[0036] The solid content of the positive electrode slurry includes 96.0wt% of positive electrode active material, 1.5wt% of binder PVDF, 0.5wt% of multi-walled carbon nanotubes CNT, 0.5wt% of super conductive carbon black, and 1.5wt% of Al 2 O 3 ; The above is an ultra-high ratio ratio;

[0037] The positive electrode slurry is evenly coated on both sides of the aluminum foil, dried, and compacted by a roller press to obtain a positive electrode sheet;

[0038] 2) Preparation of negative electrode sheet:

[0039] The negative electrode active material graphite, binder SBR, thickener CMC and conductive carbon black, Al 2 O 3 Mix and disperse in deionized water to obtain negative electrode slurry;

[0040] The solid content of the negative electrode slurry includes 94.5wt% graphite, 1.5wt% CMC, 1.0wt% conductive carbon black, 1.5wt% Al 2 O 3 , 1.5wt% SBR;

[0041] The negative electrode slurry is evenly coated on both sides of the copper foil, and after drying and compacting by a roller press, a negative electrode sheet is obtained;

[0042] 3) Preparation of battery cells:

[0043] The positive and negative electrodes prepared above were welded to two 6mm aluminum strips and nickel strips respectively, and then the core was obtained by winding the same diaphragm (glue coated + ceramic coated 12+2+2μm). The core was flattened (with the pole ear centered), baked at 85℃ for 4h, and the positive and negative electrodes were respectively equipped with PP spacer gaskets designed according to the dimensions after pressing the core, and then ultrasonically welded with aluminum strips and nickel strips; then, they were welded to 10mm pole ears (positive aluminum to nickel / negative nickel pole ears), protected by glue, folded pole ears, packaged, baked, injected with liquid, hot pressed at high temperature, and divided into different capacities to obtain the battery cell.

[0044] Furthermore, the number of tabs of the positive and negative electrodes is a dual-pole tab design, and corrosion-resistant polymer PP material gaskets are used under the tabs to improve the safety of the internal structure of the battery.

[0045] Furthermore, the separator is a separator coated with glue and ceramic coating to improve the safety and performance of the battery.

[0046] Furthermore, after welding, a plurality of tabs are bent in a "Z-shape" and then welded to a wider lead-out tab to facilitate external connection of the battery and current extraction.

[0047] Furthermore, the preparation process of the battery cell also includes liquid injection, high temperature hot pressing and capacity division steps to ensure the performance and quality of the battery cell.

[0048] Furthermore, the overall design of the battery cell also includes using tab glue to seal between the tab and the aluminum-plastic film to enhance the packaging effect and safety of the battery cell.

[0049] The following are the test items for verification: capacity, internal resistance, rate performance, cycle performance, 1C6V overcharge, 0℃ charging high temperature short circuit test, and 0℃ charging thermal shock test.

[0050] The following table shows the test data of the embodiments and comparative examples:

[0051] Capacity, internal resistance, rate data

[0052]

[0053]

[0054] Table 1. 11C charge and discharge at 40A for 300 cycles

[0055]

[0056] Table 1.21C6V overcharge test

[0057]

[0058] Table 1. 30℃ charging, 55℃ high temperature short circuit test

[0059]

[0060] Table 1. 40℃ charging, 130℃ thermal shock test

[0061]

[0062] Table 1.5

[0063] From the data in Table 1.1 to Table 1.5, it can be seen that the ultra-high rate ratio, double-coated diaphragm (PVDF+ceramic), high-temperature hot pressing process, and multi-electrode structure design and development of this project can make the rate performance, rate cycle performance and safety performance meet the highest-end needs of e-cigarettes, 40A continuous discharge.

[0064] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing an ultra-high rate elliptical polymer lithium-ion battery for electronic cigarettes, characterized in that: The following steps are involved: 1) Preparation of positive electrode: The positive electrode active material lithium cobalt oxide, the binder PVDF, the conductive agent and Al2O3 are dispersed in N-methylpyrrolidone to obtain a uniform positive electrode slurry; In the positive electrode slurry, the solid components include 96.0wt% of positive electrode active material, 1.5wt% of binder PVDF, 0.5wt% of multi-walled carbon nanotubes CNT, 0.5wt% of super conductive carbon black, and 1.5wt% of Al2O3; the above is an ultra-high ratio ratio; The positive electrode slurry is evenly coated on two surfaces of the aluminum foil, dried, and compacted by a roller press to obtain a positive electrode sheet; 2) Preparation of negative electrode sheet: The negative electrode active material graphite, the binder SBR, the thickener CMC, the conductive carbon black and Al2O3 are mixed and dispersed in deionized water to obtain a negative electrode slurry; In the negative electrode slurry, the solid components include 94.5wt% of graphite, 1.5wt% of CMC, 1.0wt% of conductive carbon black, 1.5wt% of Al2O3, and 1.5wt% of SBR; The negative electrode slurry is evenly coated on both sides of the copper foil, and then dried and compacted by a roller press to obtain a negative electrode sheet; 3) Preparation of battery cells: The positive and negative electrodes prepared above were welded to two 6mm aluminum strips and nickel strips respectively, and then the core was obtained by winding the same diaphragm (glue coated + ceramic coated 12+2+2μm). The core was flattened (with the pole ear centered), baked at 85℃ for 4h, and the positive and negative electrodes were respectively equipped with PP spacer gaskets designed according to the dimensions after pressing the core, and then ultrasonically welded with aluminum strips and nickel strips; then, they were welded to 10mm pole ears (positive aluminum to nickel / negative nickel pole ears), protected by glue, folded pole ears, packaged, baked, injected with liquid, hot pressed at high temperature, and divided into different capacities to obtain the battery cell.

2. The method for preparing the ultra-high rate elliptical polymer lithium-ion battery for electronic cigarettes according to claim 1, characterized in that: The number of pole ears of the positive electrode sheet and the negative electrode sheet is a double-pole ear design, and corrosion-resistant polymer PP material gaskets are selected under the pole ears to improve the safety of the internal structure of the battery.

3. The method for preparing the ultra-high rate elliptical polymer lithium-ion battery for electronic cigarettes according to claim 1, characterized in that: The diaphragm is a diaphragm coated with glue and ceramic coating to improve the safety and performance of the battery.

4. The method for preparing an ultra-high rate elliptical polymer lithium-ion battery for electronic cigarettes according to claim 1, characterized in that: After welding, the plurality of tabs are bent in a "Z-shape" and then welded to a wider lead-out tab to facilitate external connection of the battery and current extraction.

5. The method for preparing an ultra-high rate elliptical polymer lithium-ion battery for electronic cigarettes according to claim 1, characterized in that: The preparation process of the battery core also includes liquid injection, high temperature hot pressing and capacity division steps to ensure the performance and quality of the battery core.

6. The method for preparing the ultra-high rate elliptical polymer lithium-ion battery for electronic cigarettes according to claim 1, characterized in that: The overall design of the battery cell also includes using a tab glue to seal between the tab and the aluminum-plastic film to enhance the packaging effect and safety of the battery cell.

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