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

Abstract

The application relates to the technical field of batteries, in particular to a preparation method of a special-shaped high-voltage high-rate battery. The preparation method comprises 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 through the preparation method are wound in a winding mode with the tab facing the special end, are matched with electrolyte which is resistant to high-pressure oxidative decomposition, and finally are prepared into a special-shaped soft-pack lithium ion battery. The electric performance can satisfy maximum 15C discharging, supports 2C charging and 10C discharging for 400 cycles, and can be applied to the battery of an electronic cigarette. The battery can solve the problem that the existing battery cannot satisfy the working mode of the electronic cigarette, and can improve the energy density and the cycle stability of high-rate charging and discharging.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of batteries, in particular to a preparation method of a special-shaped high-voltage high-rate battery. BACKGROUND

[0002] With the continuous improvement of the terminal consumer's requirements for the number of puffs and taste of electronic cigarette smoking, it is not only required that the lithium ion battery has greater capacity and rate performance, but also higher requirements for its energy density. Increasing the charge upper limit voltage of the electronic cigarette battery system and developing a high specific capacity battery material system are effective methods to improve the energy density of the battery. At present, the commercial market of mobile phones mainly uses 4.45V type battery system to prepare 1Ah capacity batteries, which cannot discharge the capacity at 10C continuous discharge and do not support rate discharge cycle; the working mode of the electronic cigarette battery is not met. Since the electronic cigarette has requirements for taste, it needs to meet the continuous discharge within 10-15A. When the battery is charged to 4.45V, a series of problems such as surface oxygen radical release of the positive electrode, transition metal ion dissolution, and lattice structure collapse easily occur, and after multiple cycles of large-rate discharge, the battery electrolyte interface will be damaged, the battery capacity will be accelerated to decay and swell, and in severe cases, thermal runaway will occur, which limits the further application of the 4.45V battery system in electronic cigarette portable products. SUMMARY

[0003] In order to solve the above technical problems, the application provides a preparation method of a special-shaped high-voltage high-rate battery, which comprises the following steps:

[0004] S1, preparation of a positive electrode sheet: mixing positive electrode active material, conductive agent and binder according to a mass ratio of (96-98):(1-2):(1-2), preparing a slurry through a high-speed dispersion device, coating, roller compaction, slitting, and then preparing a positive electrode sheet with a corresponding length, welding an aluminum-nickel plated tab at the middle position of the positive electrode sheet, and then preparing a positive electrode sheet after gluing;

[0005] S2, preparation of a negative electrode sheet: mixing artificial graphite, conductive agent, thickening agent and binder according to a mass ratio of (95-96):(1-1.5):(1.3-1.5):(1.7-2), preparing a slurry through a high-speed dispersion device, coating, roller compaction, slitting, and then preparing a negative electrode sheet with a corresponding length, welding a copper-nickel plated tab at the middle position of the negative electrode sheet, and then preparing a negative electrode sheet after gluing;

[0006] S3, preparation of a separator, the separator comprising a base material, a bonding layer coated on at least one surface of the base material, and a ceramic layer coated on the bonding layer;

[0007] S4, winding the positive electrode sheet, the negative electrode sheet and the separator with a winding machine, the positive and negative tabs are placed towards the opposite end, to obtain a winding core, and then sequentially through the core pressing, packaging, baking, liquid injection, aging, formation, two sealing, containerization and packaging processes to make the soft pack irregular lithium ion battery;

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

[0009] Preferably, in step S1, the lithium cobaltate has a 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 compacted density of 3.7-4 g / cm3.

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

[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 thickening agent and the binder have a mass ratio of 96:1:1.3:1.7.

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

[0014] As can be seen from the above, by applying the preparation method provided in the present application, the following beneficial effects can be obtained: the positive electrode sheet, the negative electrode sheet and the separator obtained by the preparation method of the present application are wound in a way that the tabs are towards the opposite end, and are matched with electrolyte that is resistant to high-pressure oxidative decomposition, to finally prepare an irregular soft pack lithium ion battery, the electrical performance of which can meet the maximum 15C discharge and support 2C charging and 10C discharging for 400 cycles, which can improve the energy density while taking into account the rate charge-discharge performance, and can be applied to the battery of an electronic cigarette, solving the problem that the existing battery cannot meet the working mode of the electronic cigarette, and improving the energy density and the cycle stability of large-rate charge-discharge of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the present application or the prior art. Obviously, the drawings in the following description are only part of the embodiments of the present application, and other drawings can also be obtained by those of ordinary skill in the art without any creative labor on the basis of these drawings.

[0016] Figure 1 The preparation method flow chart of the special-shaped high-voltage high-rate battery of the present application is shown in the figure.

[0017] Figure 2 The rate discharge curve of each embodiment of the present application is shown in the figure.

[0018] Figure 3 The 2C charge 10C discharge cycle curve comparison figure of each embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to 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 the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative labor are within the scope of protection of the present application.

[0020] Embodiment 1

[0021] In order to solve the above technical problems, the present embodiment provides a preparation method of a special-shaped high-voltage high-rate battery, as shown in the figure, comprising the following steps: Figure 1

[0022] S1, preparation of positive electrode sheet: mix positive active material, conductive agent and binder according to mass ratio (96-98):(1-2):(1-2), prepare slurry through high-speed dispersion equipment, coat, roll compact, and cut to form positive electrode sheet with corresponding length, weld aluminum-nickel lug at the middle position of the positive electrode sheet and paste glue, wherein the positive active material is lithium cobaltate, the lug width is 4-6mm, preferably 6mm;

[0023] In this step S1, the lithium cobaltate has a capacity≥180mAh / g, a particle size D50 of 5.6-6um, a specific surface area of 0.39-0.4m 2 / g, and a compact density of 3.7-4g / cm3. Preferably, the particle size D50 is 5.6um, the specific surface area is 0.39m2 / g, and the compact density is 3.7g / cm3. The high-voltage high-rate lithium cobaltate coated with doped transition metal is used to prepare the positive electrode sheet, and the lithium cobaltate with high compact density and high capacity is used to improve the high-rate performance of the battery.

[0024] ​S2, preparation of the negative electrode sheet: the artificial graphite, conductive agent, thickening agent, binder are mixed according to the mass ratio (95-96):(1-1.5):(1.3-1.5):(1.7-2), prepared into slurry by high-speed dispersion equipment, coated, roll compacted, cut into corresponding length of negative electrode sheet, the copper-plated nickel tab is welded at the middle position of the negative electrode sheet and glued, the tab width is 4-6mm, preferably 6mm;

[0025] S3, preparation of the separator, the separator includes a substrate, a bonding layer is coated on at least one surface of the substrate, and a ceramic layer is coated on the bonding layer; wherein the thickness of the substrate is 7-9μm, and the thickness of the coating layer is 3-6μm. The capacity of the battery can be maximized while ensuring the performance of the battery; the adverse phenomena such as core extraction or increased self-discharge are avoided; coating the ceramic and the bonding layer on the substrate is conducive to improving the safety performance of the lithium ion battery under the condition of high voltage of 4.45V and increasing the hardness of the lithium ion battery.

[0026] S4, the above positive electrode sheet, negative electrode sheet and separator are wound by a winding machine, the positive tab and the negative tab are placed towards the different ends, a winding core is obtained, and then the winding core is sequentially subjected to core pressing, packaging, baking, liquid injection, aging, formation, second sealing, capacity grading and packaging processes to prepare 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 tab and the negative tab respectively extend towards two ends. When the positive tab and the negative tab extend towards the same end, the width of the positive tab and the negative tab will be limited. In the embodiment 1, the tab structure of the battery is adjusted to be different end tab, and the width of the positive tab and the negative tab is wider than that of the same end tab, which can support larger overcurrent capacity. Compared with the laminated type, the process is simpler and the manufacturing cost is lower.

[0028] In the liquid injection process, the electrolyte is lithium salt with a concentration of 1.2-1.3mol / L; the mass parts of the components of the electrolyte include lithium hexafluorophosphate 15-20 parts, ethylene carbonate 16-20 parts, dimethyl carbonate 25-30 parts, propylene carbonate 8-10 parts, ethyl propionate 18-24 parts, fluoroethylene carbonate 8-10 parts, polystyrene 0.5-2.5 parts, vinylene carbonate 0.5-1 part, ammonium dinitramide 1-2 parts, vinyl sulfate 0.8-1 part, lithium bisoxalate borate 0.5-1.5 parts, forming an electrolyte resistant to high-pressure oxidative decomposition,

[0029] Preferably, in step S1 of the 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 artificial graphite, the conductive agent, the thickening agent and the binder are mixed according to the mass ratio 96:1:1.3:1.7.

[0030] Preferably, the electrolyte concentration is 1.2 mol / L, and the electrolyte includes 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 bisoxalate borate.

[0031] Example 2

[0032] The present example provides a preparation method of a special-shaped high-voltage high-rate battery, and the specific steps are the same as those of Example 1.

[0033] Different from Example 1, in step S4 of the present example, the electrolyte includes 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 bisoxalate borate.

[0034] Example 3

[0035] The present example provides a preparation method of a special-shaped high-voltage high-rate battery, and the specific steps are the same as those of Example 1.

[0036] Different from Example 1, in step S4 of the present example, the electrolyte includes 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 bisoxalate borate.

[0037] Comparative Example 1

[0038] The present example provides a preparation method of a special-shaped high-voltage high-rate battery, and the specific steps are the same as those of Example 1.

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

[0040] Comparative Example 2

[0041] The present example provides a preparation method of a special-shaped high-voltage high-rate battery, and different from Example 1, in step S1 of the present example, the lithium cobaltate has a capacity of ≥180 mAh / g, a particle size D50 of 6.3 um, a specific surface area of 0.41 m 2 / g, compacted density 3.7 g / cm 3 .

[0042] Meanwhile, the S4 step of the present comparative example 2 is to wind the positive electrode sheet, the negative electrode sheet and the separator with a winding machine, the positive electrode tab and the negative electrode tab are placed towards the same end, the width of the positive electrode tab and the negative electrode tab is 4 mm, to obtain the winding core, and then sequentially go through the core pressing, packaging, baking, liquid injection, aging, formation, second sealing, capacity distribution and packaging processes, to make the soft package special-shaped lithium ion battery. In the step S4, the positive electrode sheet, the negative electrode sheet and the separator are wound by the winding machine, and the positive electrode tab and the negative electrode tab are stretched out towards the same end. The remaining steps are the same as example 1.

[0043]

[0044] Table 1

[0045] As shown in Table 1, it is a comparison table of different temperature discharge rates of each example. As can be seen from Table 1, the 4.45V special-shaped lithium ion batteries prepared by examples 1-3 have high discharge rates at temperatures of-10℃ and-20℃. Therefore, the lithium ion batteries prepared by the formula and process steps of examples 1-3 have good discharge performance in low temperature environment; at normal temperature 25℃ as the benchmark, 60℃ discharges at 0.5C and can discharge more than 99%, -10℃ discharges at 0.5C current and can discharge more than 85%, -20℃ discharges at 0.5C current and can discharge more than 70%, and the battery working temperature window is wide. At the same time, as can be seen from examples 1-3 and comparative examples 1-2, the low temperature discharge rate of lithium cobaltate with the particle size and specific surface area described in examples 1-3 is better than that of lithium cobaltate used in comparative examples 1-2.

[0046]

[0047]

[0048] Table 2

[0049] Table 2 is a comparison table of different rate discharge rates of each example battery, Figure 2 is a comparison chart of the rate discharge curves of each example battery. As can be seen from Table 2 and Figure 2It can be seen that the special-shaped 4.45V high-voltage high-rate lithium ion battery prepared in Example 1 has a higher discharge platform at 8C, 10C and 15C rates and no reverse peak exists, proving that the temperature rise is smaller during rate discharge, and the rate performance of the electrolyte of Example 1 is good. Examples 1-3 differ in the ratio of the components of the electrolyte. The electrolyte components of Comparative Examples 1-2 are the same as those of Example 1. Among the ratios 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. Therefore, by designing the appropriate content of the electrolyte formula, 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 the cycle capacity retention rate of the battery of each example, Figure 3 The cycle curve comparison chart of the battery of each example is shown in Table 3 and Figure 3 It can be seen that the special-shaped 4.45V high-voltage high-rate lithium ion battery prepared in Example 1 has excellent 2C fast charging and 10C fast discharging performance at room temperature, and the cycle capacity retention rate can still be maintained at more than 87% after 400 cycles, proving that it has good cycle stability at 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 component ratio. Therefore, the component ratio of the above electrolyte plays a key role in the performance of the battery, and the use of the electrolyte of Example 1 can ensure that the cycle capacity retention rate can be maintained at a high level after 400 cycles.

[0054] From the above Tables 1-3, it can be seen that the positive and negative tabs of the battery in Comparative Example 2 extend to the same end, and the positive and negative tabs of the battery in Example 1 extend to different ends. When the positive and negative tabs extend to the same end, the width of the positive and negative tabs will be limited, while in Example 1, the tab structure of the battery is adjusted to be different end tab, and the width of the positive and negative tabs is wider than that of the same end tab, which can support larger overcurrent capacity. Therefore, the fast charging and fast discharging performance is more excellent.

[0055] The positive plate, the negative plate and the separator obtained by the preparation method of the scheme are wound in a winding mode with the tabs facing the opposite ends, are matched with electrolyte resistant to high-pressure oxidative decomposition, and are finally prepared into a special-shaped soft package lithium ion battery, the electrical performance of which can meet maximum 15C discharge, supports 2C charging and 10C discharging for 400 cycles, and can be applied to the battery of an electronic cigarette, solves the problem that the existing battery cannot meet the working mode of the electronic cigarette, and improves the energy density and the cycle stability of high-rate charging and discharging of the battery.

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

Claims

1. A preparation method of a special-shaped high-voltage high-rate battery, characterized in that: Comprising the following steps: S1, preparation of the positive electrode sheet: the positive electrode active material, conductive agent and binder are mixed in a mass ratio of (96-98):(1-2):(1-2), and a slurry is prepared by a high-speed dispersion device, and then the slurry is coated, roll-pressed and cut to form a positive electrode sheet with a corresponding length, and an aluminum-nickel tab is welded at the middle position of the positive electrode sheet and then glued, wherein the positive electrode active material is lithium cobaltate, the lithium cobaltate has a 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, and a compacted density of 3.7-4 g / cm 3 ; S2, preparation of negative plate: mixing artificial graphite, conductive agent, thickening agent, binder according to mass ratio (95-96): (1-1.5): (1.3-1.5): (1.7-2), preparing slurry through high-speed dispersion equipment, after coating, roll compaction, slitting, negative plate of corresponding length is prepared, and a copper-plated nickel tab is welded at the middle position of the negative plate and is pasted with adhesive; S3, preparation of diaphragm, the diaphragm comprises a base material, a bonding layer is coated on at least one surface of the base material, and a ceramic layer is coated on the bonding layer; S4, winding the above-mentioned positive plate, negative plate and diaphragm with a winding machine, the positive tab and the negative tab are placed towards different ends, a winding core is obtained, and then the winding core is sequentially subjected to core pressing, packaging, baking, liquid injection, aging, formation, second sealing, capacity grading and packaging processes, so that a soft package special-shaped lithium ion battery is prepared; In the liquid injection process, the electrolyte is a lithium salt with a concentration of 1.2-1.3 mol / L; the mass parts of 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 part of vinylene carbonate, 1-2 parts of ammonium dinitramide, 0.8-1 part of vinyl sulfate and 0.5-1.5 parts of lithium bisoxalate borate.

2. The preparation method of the shaped high-voltage high-rate battery according to claim 1, characterized in that: In step S3, the thickness of the base material is 7-9 μm, and the thickness of the coating layer is 3-6 μm.

3. The method of claim 1, wherein the method further comprises: forming a plurality of high voltage battery cells in a plurality of different shapes. In step S1, the mass ratio of the positive electrode active material, the conductive agent and the binder is 96.5:2:1.

5.

4. The method of claim 1, wherein the method further comprises: forming a plurality of high voltage battery cells in a plurality of different shapes. In step S2, the artificial graphite, the conductive agent, the thickening agent and the binder are mixed according to the mass ratio 96:1:1.3:1.

7.

5. The method of claim 1, wherein the method further comprises: forming a plurality of high voltage battery cells in a plurality of different shapes. The mass parts of components of the electrolyte 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 bisoxalate borate.

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