Preparation method of special-shaped high-voltage and high-rate battery

Abstract

The invention relates to the technical field of batteries, in particular to a preparation method of a special-shaped high-voltage and high-rate battery. Comprising a preparation step of a positive plate, a preparation step of a negative plate and a preparation step of a diaphragm, the positive plate, the negative plate and the diaphragm obtained by the preparation method of the scheme are wound in a manner that tabs face different ends, and are matched with an electrolyte resistant to high-voltage oxygenolysis to finally prepare the special-shaped soft package lithium ion battery, and the electrical property can meet the maximum 15C discharge; the material can be applied to a battery of an electronic cigarette, the problem that an existing battery cannot meet the working mode of the electronic cigarette is solved, and meanwhile, the energy density of the battery and the cycling stability of high-rate charging and discharging are improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for preparing a special-shaped high-voltage and high-rate battery. Background Art

[0002] As the end consumers' requirements for the number of puffs and taste of e-cigarettes continue to increase, this not only requires lithium-ion batteries to have greater capacity and rate performance, but also continuously puts forward higher requirements for their energy density. Improving the upper limit voltage of the charging of the e-cigarette battery system and developing a high-specific capacity battery material system are effective ways to improve the battery energy density. At present, the commercial market of mobile phones mainly uses a 4.45V battery system to prepare a 1Ah capacity battery. 10C continuous discharge cannot release the capacity and does not support rate discharge cycles; it does not meet the working mode of e-cigarette batteries. Since e-cigarettes have requirements for taste, continuous discharge within 10-15A is required. When the battery is charged to 4.45V, the positive electrode is prone to a series of problems such as surface oxygen free radical release, transition metal ion dissolution, and lattice structure collapse. At this time, multiple cycles of high-rate discharge will destroy the battery electrolyte interface, accelerate battery capacity decay and flatulence, and in severe cases lead to thermal runaway, limiting the further application of the 4.45V battery system in portable e-cigarette products. Summary of the invention

[0003] In order to solve the above technical problems, the present application provides a method for preparing a special-shaped high-voltage and high-rate battery, comprising the following steps:

[0004] S1. Preparation of positive electrode sheet: positive electrode active material, conductive agent and binder are mixed in a mass ratio of (96-98): (1-2): (1-2), and prepared into slurry by high-speed dispersing equipment, and then coated, rolled and slit to prepare positive electrode sheet of corresponding length, and aluminum-to-nickel tab is welded in the middle of the positive electrode sheet, and then glue is applied to obtain the positive electrode sheet, wherein the positive electrode active material is lithium cobalt oxide;

[0005] S2. Preparation of negative electrode sheet: artificial graphite, conductive agent, thickener and binder are mixed in a mass ratio of (95-96): (1-1.5): (1.3-1.5): (1.7-2), and prepared into slurry by high-speed dispersing equipment. After coating, roller compaction and slitting, negative electrode sheets of corresponding length are prepared. A copper-plated nickel tab is welded in the middle of the negative electrode sheet, and then glue is applied to obtain the negative electrode sheet.

[0006] S3, preparing a diaphragm, the diaphragm comprising a substrate, an adhesive layer coated on at least one surface of the substrate, and a ceramic layer coated on the adhesive layer;

[0007] S4, winding the positive electrode sheet, negative electrode sheet and separator by a winding machine, placing the positive electrode ear and the negative electrode ear toward the opposite end, to obtain a winding core, and then sequentially undergoing the steps of core pressing, packaging, baking, liquid injection, aging, formation, secondary sealing, capacity division and packaging to produce a soft-pack special-shaped lithium-ion battery;

[0008] Among them, the electrolyte in the injection process is a lithium salt with a concentration of 1.2-1.3 mol / L; the mass components of the electrolyte include 15-20 parts of lithium hexafluorophosphate, 16-20 parts of ethylene carbonate, 25-30 parts of dimethyl carbonate, 8-10 parts of propylene carbonate, 18-24 parts of ethyl propionate, 8-10 parts of fluoroethylene carbonate, 0.5-2.5 parts of polystyrene, 0.5-1 parts of vinylene carbonate, 1-2 parts of ammonium dinitramide, 0.8-1 parts of vinyl sulfate, and 0.5-1.5 parts of lithium bis(oxalatoborate).

[0009] Preferably, in step S1, the lithium cobalt oxide has a gram capacity of ≥180 mAh / g, a particle size D50 of 5.6-6 um, a specific surface area of ​​0.39-0.4 m2 / g, and a compaction density of 3.7-4 g / cm3.

[0010] Preferably, in step S3, the thickness of the substrate is 7-9 μm, and the thickness of the coating layer is 3-6 μm.

[0011] Preferably, in step S1, the mass ratio of the positive electrode active material, the conductive agent, and the binder is 96.5:2:1.5.

[0012] Preferably, in step S2, the artificial graphite, the conductive agent, the thickener and the binder are in a mass ratio of 96:1:1.3:1.7.

[0013] Preferably, the components of the electrolyte by mass include 15 parts of lithium hexafluorophosphate, 20 parts of ethylene carbonate, 25 parts of dimethyl carbonate, 8 parts of propylene carbonate, 18 parts of ethyl propionate, 10 parts of fluoroethylene carbonate, 2 parts of polystyrene, 1 part of vinylene carbonate, 2 parts of ammonium dinitramide, 1 part of vinyl sulfate, and 1.5 parts of lithium bis(oxalatoborate).

[0014] From the above, it can be seen that the application of the present application can obtain the following beneficial effects: the positive electrode sheet, negative electrode sheet and separator obtained by the preparation method of this scheme are wound in a manner with the pole ears facing the heterodox end, and are matched with an electrolyte that resists high-voltage oxidative decomposition, and finally prepared into a special-shaped soft-pack lithium-ion battery, the electrical performance of which can meet the maximum 15C discharge, support 2C charge and 10C discharge cycles for 400 weeks, and take into account the rate charge and discharge performance while improving the energy density. It can be used in the battery of electronic cigarettes to solve the problem that the existing batteries cannot meet the working mode of electronic cigarettes, while improving the battery energy density and the cycle stability of high-rate charge and discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the description of the embodiments of the present application or the prior art are briefly introduced below. Obviously, the drawings described below are only part of the embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor.

[0016] Figure 1 This is a flow chart of the preparation method of the special-shaped high-voltage and high-rate battery of the present application;

[0017] Figure 2 This is a rate discharge curve diagram of each embodiment of the present application;

[0018] Figure 3 This is a comparison chart of the 2C charge and 10C discharge cycle curves of various embodiments of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] Example 1

[0021] In order to solve the above technical problems, this embodiment provides a method for preparing a special-shaped high-voltage and high-rate battery, such as Figure 1 As shown, the following steps are included:

[0022] S1. Preparation of positive electrode sheet: positive electrode active material, conductive agent and binder are mixed in a mass ratio of (96-98): (1-2): (1-2), and prepared into slurry by high-speed dispersing equipment. After coating, roller compaction and slitting, positive electrode sheet of corresponding length is made, and aluminum-to-nickel tab is welded in the middle of the positive electrode sheet and glued, wherein the positive electrode active material is lithium cobalt oxide, and the tab width is 4-6 mm, preferably 6 mm;

[0023] In step S1, the lithium cobalt oxide has a gram capacity of ≥180 mAh / g, a particle size D50 of 5.6-6 um, and a specific surface area of ​​0.39-0.4 m 2 / g, compaction density 3.7-4g / cm3. Preferably, the particle size D50 is 5.6um, the specific surface area is 0.39m2 / g, and the compaction density is 3.7g / cm3. The positive electrode sheet is made of high-voltage rate lithium cobalt oxide coated with doped transition metals, high compaction density, and high gram capacity lithium cobalt oxide, which is beneficial to improving the high-rate performance of the battery.

[0024] S2. Preparation of negative electrode sheet: artificial graphite, conductive agent, thickener and binder are mixed in a mass ratio of (95-96): (1-1.5): (1.3-1.5): (1.7-2), and prepared into slurry by high-speed dispersing equipment. After coating, roller compaction and slitting, negative electrode sheets of corresponding length are prepared. A copper-plated nickel tab is welded in the middle of the negative electrode sheet and glued. The width of the tab is 4-6 mm, preferably 6 mm.

[0025] S3, preparation of the diaphragm, the diaphragm includes a substrate, an adhesive layer is coated on at least one surface of the substrate, and a ceramic layer is coated on the adhesive layer; wherein the thickness of the substrate is 7-9μm, and the thickness of the coating layer is 3-6μm. It can maximize the capacity of the battery while ensuring the battery performance; avoid the occurrence of core pulling or increased self-discharge and other undesirable phenomena; coating the ceramic and adhesive layers on the substrate is conducive to improving the safety performance of the lithium-ion battery under the condition of 4.45V high voltage and increasing the hardness of the lithium-ion battery.

[0026] S4, winding the positive electrode sheet, negative electrode sheet and separator by a winding machine, placing the positive electrode ear and negative electrode ear toward the opposite end, obtaining a winding core, and then sequentially undergoing the steps of core pressing, packaging, baking, liquid injection, aging, formation, secondary sealing, capacity division and packaging to produce a 4.45V soft-pack special-shaped lithium-ion battery;

[0027] In step S4, the positive electrode sheet, the negative electrode sheet and the separator are wound by a winding machine, and the positive electrode ear and the negative electrode ear are extended toward both ends respectively. When the positive and negative electrode ears are extended toward the same end, the widths of the positive and negative electrode ears will be limited. In Example 1, the electrode ear structure of the battery is adjusted to different-end electrode ears, and the widths of the positive and negative electrode ears are wider than those of the same-end electrode ears, which can support a larger overcurrent capacity. Compared with the stacking type, the process is simpler and the manufacturing cost is lower.

[0028] The electrolyte in the injection process is a lithium salt with a concentration of 1.2-1.3 mol / L; the electrolyte comprises 15-20 parts of lithium hexafluorophosphate, 16-20 parts of ethylene carbonate, 25-30 parts of dimethyl carbonate, 8-10 parts of propylene carbonate, 18-24 parts of ethyl propionate, 8-10 parts of fluoroethylene carbonate, 0.5-2.5 parts of polystyrene, 0.5-1 parts of vinylene carbonate, 1-2 parts of ammonium dinitramide, 0.8-1 parts of vinyl sulfate, and 0.5-1.5 parts of lithium bis(oxalatoborate), so as to form an electrolyte resistant to high-voltage oxidative decomposition.

[0029] Preferably, in step S1 of this embodiment, the mass ratio of the positive electrode active material, the conductive agent, and the binder is 96.5:2:1.5. In step S2, the mass ratio of the artificial graphite, the conductive agent, the thickener, and the binder is 96:1:1.3:1.7.

[0030] Preferably, the electrolyte concentration is 1.2 mol / L, and the electrolyte components by mass include 15 parts of lithium hexafluorophosphate, 20 parts of ethylene carbonate, 25 parts of dimethyl carbonate, 8 parts of propylene carbonate, 18 parts of ethyl propionate, 10 parts of fluoroethylene carbonate, 2 parts of polystyrene, 1 part of vinylene carbonate, 2 parts of ammonium dinitramide, 1 part of vinyl sulfate, and 1.5 parts of lithium bis(oxalatoborate).

[0031] Example 2

[0032] This embodiment provides a method for preparing a special-shaped high-voltage and high-rate battery, and the specific steps are the same as those in Embodiment 1.

[0033] Different from Example 1, in step S4 of this Example 2, the mass components of the electrolyte include 15 parts of lithium hexafluorophosphate, 10 parts of ethylene carbonate, 20 parts of dimethyl carbonate, 8 parts of propylene carbonate, 18 parts of ethyl propionate, 5 parts of fluoroethylene carbonate, 2 parts of polystyrene, 1 part of vinylene carbonate, 2 parts of ammonium dinitramide, 1 part of vinyl sulfate, and 1.5 parts of lithium bis(oxalatoborate).

[0034] Example 3

[0035] This embodiment provides a method for preparing a special-shaped high-voltage and high-rate battery, and the specific steps are the same as those in Embodiment 1.

[0036] Different from Example 1, in step S4 of this Example 3, the mass components of the electrolyte include 15 parts of lithium hexafluorophosphate, 25 parts of ethylene carbonate, 35 parts of dimethyl carbonate, 8 parts of propylene carbonate, 18 parts of ethyl propionate, 15 parts of fluoroethylene carbonate, 2 parts of polystyrene, 1 part of vinylene carbonate, 2 parts of ammonium dinitramide, 1 part of vinyl sulfate, and 1.5 parts of lithium bis(oxalatoborate).

[0037] Comparative Example 1

[0038] This embodiment provides a method for preparing a special-shaped high-voltage and high-rate battery, and the specific steps are the same as those in Embodiment 1.

[0039] Different from Example 1, in step S1, the lithium cobalt oxide has a gram capacity of ≥180 mAh / g, a particle size D50 of 6.3 μm, and a specific surface area of ​​0.41 m 2 / g, compacted density 3.7g / cm 3 .

[0040] Comparative Example 2

[0041] This embodiment provides a method for preparing a special-shaped high-voltage and high-rate battery. The difference from Example 1 is that in step S1 of this comparative example 2, the lithium cobalt oxide gram capacity is ≥180 mAh / g, the particle size D50 is 6.3 um, and the specific surface area is 0.41 m 2 / g, compacted density 3.7g / cm 3 .

[0042] At the same time, step S4 of this comparative example 2 is to wind the above-mentioned positive electrode sheet, negative electrode sheet and separator with a winding machine, with the positive electrode ear and the negative electrode ear facing the same end, and the width of the positive electrode ear and the negative electrode ear is 4mm, to obtain a winding core, and then sequentially undergo the steps of core pressing, packaging, baking, liquid injection, aging, formation, secondary sealing, capacity division, and packaging to produce a soft-pack special-shaped lithium-ion battery. In step S4, the positive electrode sheet, the negative electrode sheet and the separator are wound by a winding machine, and the positive electrode ear and the negative electrode ear extend toward the same end. The remaining steps are the same as those in Example 1.

[0043]

[0044] Table 1

[0045] Table 1 shows a comparison table of discharge rates at different temperatures of various embodiments. As can be seen from Table 1, the 4.45V special-shaped lithium-ion batteries prepared in Examples 1-3 have a high discharge rate at temperatures of -10°C and -20°C. Therefore, the lithium-ion batteries prepared by the formula and process steps of Examples 1-3 of this scheme have good discharge performance in a low temperature environment; based on the normal temperature of 25°C, more than 99% can be discharged at 60°C with a discharge of 0.5C, more than 85% can be discharged at -10°C with a current of 0.5C, and more than 70% can be discharged at -20°C with a current of 0.5C, and the battery operating temperature window is wide. At the same time, it can be seen from Examples 1-3 and Comparative Examples 1-2 that the particle size and specific surface area of ​​the lithium cobalt oxide described in Examples 1-3 have a low-temperature discharge rate that is better than the lithium cobalt oxide used in Comparative Examples 1-2.

[0046]

[0047]

[0048] Table 2

[0049] Table 2 Comparison of different discharge rates of batteries in various embodiments, Figure 2 The figure is a comparison chart of the battery rate discharge curves of each embodiment. Figure 2It can be seen that the special-shaped 4.45V high-voltage and high-rate lithium-ion battery prepared in Example 1 has a higher discharge platform at 8C, 10C, and 15C rates, and no inverted peak exists, which proves that its temperature rise is small during rate discharge, and the rate performance of the electrolyte in Example 1 is good. The difference between Examples 1-3 is that the ratio of the electrolyte components is different, and the electrolyte components of Comparative Examples 1-2 are the same as those of Example 1. Among them, in the ratio of the important components of the electrolyte of Examples 1-3, the content of ethylene carbonate, dimethyl carbonate and fluoroethylene carbonate in Example 2 is lower than that in Example 1, while the content of ethylene carbonate, dimethyl carbonate and fluoroethylene carbonate in Example 3 is higher than that in Example 1. It can be seen that by designing a suitable electrolyte formula content, the discharge capacity retention rate of the battery at different rates can be improved, and the rate performance of the battery can be improved.

[0050]

[0051]

[0052] Table 3

[0053] Table 3 is a comparison table of battery cycle capacity retention rates of various embodiments. Figure 3 The comparison of battery cycle curves of various embodiments is shown in Table 3 and Figure 3 It can be seen that the special-shaped 4.45V high-voltage and high-rate lithium-ion battery prepared in Example 1 has excellent 2C fast charging and 10C fast discharging performance at room temperature, and the 400-week cycle capacity retention rate can still be maintained at more than 87%, proving that it has good cycle stability under high voltage. The cycle capacity retention rate of Example 3 is higher than that of Example 1, and the cycle capacity retention rate of Comparative Example 1 is higher than that of Examples 2 and 3. Comparative Example 1 and Example 1 use the same electrolyte composition ratio. Therefore, the composition ratio of the above electrolyte plays a key role in battery performance, and the use of the electrolyte in Example 1 can ensure that the 400-week cycle capacity retention rate can be maintained at a high level.

[0054] It can be seen from Tables 1-3 above that the positive and negative pole ears of the battery in Comparative Example 2 extend toward the same end, while the positive and negative pole ears of the battery in Example 1 extend toward different ends. When the positive and negative pole ears extend toward the same end, the width of the positive and negative pole ears will be limited, while in Example 1, the pole ear structure of the battery is adjusted to have pole ears at different ends, and the width of the positive and negative pole ears is wider than that of the pole ears at the same end, which can support a larger overcurrent capacity. Therefore, the fast charging and fast discharging performance is even better.

[0055] The positive electrode sheet, negative electrode sheet and separator obtained by the preparation method of this scheme are wound in a manner with the pole ears facing the heterodox end, and are matched with an electrolyte resistant to high-voltage oxidative decomposition, and finally prepared into a special-shaped soft-pack lithium-ion battery. The electrical performance can meet the maximum 15C discharge, support 2C charge and 10C discharge cycles for 400 weeks, and take into account the rate charge and discharge performance while improving the energy density. It can be used in the battery of electronic cigarettes to solve the problem that the existing batteries cannot meet the working mode of electronic cigarettes, and at the same time improve the battery energy density and the cycle stability of large-rate charge and discharge.

[0056] The above-described implementation methods do not constitute a limitation on the protection scope of the technical solution. Any modification, equivalent replacement and improvement made within the spirit and principle of the above-described implementation methods shall be included in the protection scope of the technical solution.

Claims

1. A method for preparing a special-shaped high-voltage high-rate battery, characterized in that: The following steps are involved: S1. Preparation of positive electrode sheet: positive electrode active material, conductive agent and binder are mixed in a mass ratio of (96-98): (1-2): (1-2), and prepared into slurry by high-speed dispersing equipment. After coating, roller compaction and slitting, positive electrode sheet of corresponding length is prepared. An aluminum-to-nickel tab is welded in the middle of the positive electrode sheet and glued. The positive electrode active material is lithium cobalt oxide. S2. Preparation of negative electrode sheet: artificial graphite, conductive agent, thickener and binder are mixed in a mass ratio of (95-96): (1-1.5): (1.3-1.5): (1.7-2), and prepared into slurry by high-speed dispersing equipment. After coating, roller compaction and slitting, negative electrode sheets of corresponding length are prepared. A copper-plated nickel tab is welded in the middle of the negative electrode sheet and glue is applied. S3, preparing a diaphragm, the diaphragm comprising a substrate, an adhesive layer coated on at least one surface of the substrate, and a ceramic layer coated on the adhesive layer; S4, winding the positive electrode sheet, negative electrode sheet and separator by a winding machine, placing the positive electrode ear and the negative electrode ear toward the opposite end, to obtain a winding core, and then sequentially undergoing the steps of core pressing, packaging, baking, liquid injection, aging, formation, secondary sealing, capacity division and packaging to produce a soft-pack special-shaped lithium-ion battery; Among them, the electrolyte in the injection process is a lithium salt with a concentration of 1.2-1.3 mol / L; the mass components of the electrolyte include 15-20 parts of lithium hexafluorophosphate, 16-20 parts of ethylene carbonate, 25-30 parts of dimethyl carbonate, 8-10 parts of propylene carbonate, 18-24 parts of ethyl propionate, 8-10 parts of fluoroethylene carbonate, 0.5-2.5 parts of polystyrene, 0.5-1 parts of vinylene carbonate, 1-2 parts of ammonium dinitramide, 0.8-1 parts of vinyl sulfate, and 0.5-1.5 parts of lithium bis(oxalatoborate).

2. The method for preparing a special-shaped high-voltage and high-rate battery according to claim 1, characterized in that: In step S1, the lithium cobalt oxide has a gram capacity of ≥180 mAh / g, a particle size D50 of 5.6-6 um, and a specific surface area of ​​0.39-0.4 m 2 / g, compacted density 3.7-4g / cm 3 .

3. The method for preparing a special-shaped high-voltage and high-rate battery according to claim 1, characterized in that: In step S3, the thickness of the substrate is 7-9 μm, and the thickness of the coating layer is 3-6 μm.

4. The method for preparing a special-shaped high-voltage and high-rate battery according to claim 1, characterized in that: In step S1 , the mass ratio of the positive electrode active material, the conductive agent, and the binder is 96.5:2:1.

5.

5. The method for preparing a special-shaped high-voltage and high-rate battery according to claim 1, characterized in that: In step S2, artificial graphite, conductive agent, thickener and binder are mixed in a mass ratio of 96:1:1.3:1.

7.

6. The method for preparing a special-shaped high-voltage and high-rate battery according to claim 1, characterized in that: The electrolyte comprises, by weight, 15 parts of lithium hexafluorophosphate, 20 parts of ethylene carbonate, 25 parts of dimethyl carbonate, 8 parts of propylene carbonate, 18 parts of ethyl propionate, 10 parts of fluoroethylene carbonate, 2 parts of polystyrene, 1 part of vinylene carbonate, 2 parts of ammonium dinitramide, 1 part of vinyl sulfate, and 1.5 parts of lithium bis(oxalatoborate).

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