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CN111009692A - Manufacturing method of lithium ion battery and lithium ion battery - Google Patents

Manufacturing method of lithium ion battery and lithium ion battery Download PDF

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Publication number
CN111009692A
CN111009692A CN201911366812.7A CN201911366812A CN111009692A CN 111009692 A CN111009692 A CN 111009692A CN 201911366812 A CN201911366812 A CN 201911366812A CN 111009692 A CN111009692 A CN 111009692A
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negative
lithium ion
positive
negative plate
manufacturing
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吴长伟
杨斌
张子龙
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Huizhou Highpower Technology Co Ltd
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Huizhou Highpower Technology Co Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/058Construction or manufacture
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/04Processes of manufacture in general
    • H01M4/0471Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/13Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139Processes of manufacture
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention belongs to the technical field of new energy, and particularly relates to a lithium ion battery and a manufacturing method thereof, wherein the manufacturing method of the lithium ion battery comprises the steps of manufacturing a negative plate and a positive plate, and baking the negative plate for 12-24 hours at 240-320 ℃ under the protection of nitrogen after the plates are divided; assembling the positive plate, the baked negative plate and the diaphragm into a battery cell, putting the battery cell into a shell, then injecting electrolyte and sealing to form the lithium ion battery. In the manufacturing method of the lithium ion battery provided by the embodiment of the invention, the baking temperature of the negative plate is set to be 240-320 ℃ in the nitrogen protection atmosphere, so that the thickening agent in the negative plate is cracked, the influence of the thickening agent on the dynamic internal resistance of the battery after the pole piece is formed is avoided, the cycle performance of the battery under high rate is improved, and the high rate battery can discharge smoothly.

Description

Manufacturing method of lithium ion battery and lithium ion battery
Technical Field
The invention belongs to the technical field of new energy, and particularly relates to a manufacturing method of a lithium ion battery and the lithium ion battery.
Background
The lithium ion battery has the characteristics of high working voltage, long service life, no memory effect, cleanness, no pollution and the like, and becomes one of the ways of replacing fossil fuels such as petroleum and the like to provide energy. Recently, with the addition of policies and the advancement of technologies, the new energy automobile industry using lithium ion batteries as a power source has been developed greatly, and with a series of european restrictive policies on fuel vehicles, lithium ion batteries have a great application prospect in power supply systems for new energy automobiles, but the use environment of power batteries sometimes requires that the batteries have high-rate discharge capability, and at the same time, the lithium ion batteries have higher requirements on safety performance. Under such a trend, further improvement of the charge and discharge performance of the lithium ion battery at high rate is becoming a hot point in the field.
The problems that the maximum temperature of the prior cylindrical battery with partial models reaches above 60 ℃ or the battery can not discharge electricity and the like exist when the prior cylindrical battery is charged and discharged at high multiplying power, and the problems need to be improved.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the problems of high temperature and no discharge of electricity during high-rate discharge of the existing battery, a manufacturing method of a high-rate lithium ion battery and the lithium ion battery are provided.
In order to solve the above technical problem, an embodiment of the present invention provides a method for manufacturing a lithium ion battery, including the following steps:
preparing a negative plate, namely mixing a negative active substance, a negative conductive agent, a thickening agent and a binder, dissolving the mixture in a solvent, uniformly stirring to obtain negative slurry, and coating the negative slurry on a negative current collector to obtain the negative plate;
preparing a positive plate, namely mixing a positive active substance, a positive conductive agent and a binder, dissolving the mixture in a solvent, uniformly stirring to obtain positive slurry, and coating the positive slurry on a positive current collector to obtain the positive plate;
after the negative plate is sliced, baking the negative plate for 12-24 hours at 240-320 ℃ under the protection of nitrogen;
and (3) manufacturing the battery, namely assembling the positive plate, the baked negative plate and the diaphragm into a battery core, packaging the battery core into a shell, injecting electrolyte and sealing to form the lithium ion battery.
Optionally, in the step of manufacturing the negative electrode sheet, 94.8-95.8% of a negative electrode active material, 1.0-2.0% of conductive carbon black, 1.4-1.8% of sodium carboxymethyl cellulose, and 1.8-2.2% of styrene butadiene rubber are mixed according to weight percentage, and a solvent is added to the mixture and stirred uniformly to obtain a negative electrode slurry.
Optionally, in the manufacturing step of the positive plate, 94.0-95.0% of positive active material, 1.5-2.5% of conductive carbon black, 0.8-1.2% of conductive graphite and 1.8-2.2% of polyvinylidene fluoride are mixed according to weight percentage, and a solvent is added to the mixture and the mixture is stirred uniformly to obtain positive slurry.
Optionally, the negative active material includes one or more of artificial graphite, natural graphite, hard carbon, soft carbon, elemental silicon, a silicon-carbon composite, and silicon oxide.
Optionally, the positive electrode active material includes one or more of a nickel cobalt manganese lithium composite oxide, a nickel cobalt aluminum lithium composite oxide, and a nickel manganese aluminum lithium composite oxide.
In another aspect, the present invention provides a lithium ion battery, including a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode and the negative electrode are obtained by the above method for manufacturing a lithium ion battery.
In the manufacturing method of the lithium ion battery provided by the embodiment of the invention, the baking temperature of the negative plate is set to be 240-320 ℃ in the nitrogen protection atmosphere, so that the thickening agent in the negative plate is cracked, the influence of the thickening agent on the dynamic internal resistance of the battery after the pole piece is formed is avoided, the cycle performance of the battery under high rate is improved, and the high rate battery can discharge smoothly.
Drawings
Fig. 1 is a graph of capacity retention rate of 12C discharge provided in an embodiment of the present invention.
Fig. 2 is a dynamic internal resistance diagram according to an embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The manufacturing method of the lithium ion battery provided by the embodiment of the invention comprises the following steps:
preparing a negative plate, namely mixing a negative active substance, a negative conductive agent, a thickening agent and a binder, dissolving the mixture in a solvent, uniformly stirring to obtain negative slurry, and coating the negative slurry on a negative current collector to obtain the negative plate;
preparing a positive plate, namely mixing a positive active substance, a positive conductive agent and a binder, dissolving the mixture in a solvent, uniformly stirring to obtain positive slurry, and coating the positive slurry on a positive current collector to obtain the positive plate;
after the negative plate is sliced, baking the negative plate for 12-24 hours at 240-320 ℃ under the protection of nitrogen;
and (3) manufacturing the battery, namely assembling the positive plate, the baked negative plate and the diaphragm into a battery core, packaging the battery core into a shell, injecting electrolyte and sealing to form the lithium ion battery.
In the manufacturing process of the negative plate, the negative conductive agent constructs an electronic conductive network to provide a quick channel for electron transmission; the thickening agent has the effects of preventing the thickening and sedimentation of the negative electrode slurry, can disperse the negative electrode active material and the conductive agent, improves the dispersion stability of the water-insoluble material in the solution, and improves the fluidity of the water-insoluble material in the solution; the adhesive can enhance the contact among the active material, the conductive agent and the current collector, and keep the stable structure of the pole piece in the charging and discharging process.
The inventor discovers through a large number of experimental analyses that some lithium ion batteries have higher dynamic internal resistance and poorer cycle performance under high multiplying power when charged and discharged at high multiplying power in the using process. The thickener mainly plays a role in the negative pole slurry homogenizing and pulping stages, after a pole piece is coated and formed, the corresponding effect disappears, the thickener used in the manufacturing process of the lithium ion battery is non-conductive, and can influence the dynamic internal resistance of the negative pole piece under high-rate charging and discharging so as to influence the dynamic internal resistance of the battery, thereby causing the condition of poor high-rate cycle performance or incapability of discharging under higher rate. Starting from 220 ℃, the thickening agent can crack, preferably, under the condition of ensuring that the binder is not aged or decomposed, the baking temperature of the negative plate is set to be 240-320 ℃, the coated negative plate is baked for 12-24 hours under the protection atmosphere of nitrogen, so that the thickening agent in the negative plate cracks, the influence of the thickening agent on the dynamic internal resistance of the battery after the plate is formed is avoided, the effect of the binder cannot be influenced, and the problems of material falling and chip breakage of the negative plate cannot occur.
Specifically, the baking temperature may be 240 ℃, 250 ℃, 255 ℃, 260 ℃, 270 ℃, 275 ℃, 280 ℃, 290 ℃, 295 ℃, 300 ℃, 310 ℃, 315 ℃ and 320 ℃. The baking time can be 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h and 24 h.
In one embodiment, the negative electrode conductive agent is Super-P (conductive carbon black), the thickener is CMC (sodium carboxymethylcellulose), the binder is SBR (styrene butadiene rubber), and in the manufacturing step of the negative electrode sheet, 94.8-95.8% of negative electrode active material, 1.0-2.0% of Super-P, 1.4-1.8% of CMC and 1.8-2.2% of SBR are mixed according to weight percentage, added with deionized water and stirred uniformly to obtain negative electrode slurry.
In the negative electrode, the cracking temperature of CMC is above 220 ℃, the cracking starting temperature of SBR is 340 ℃, the graphitization temperature of SP is above 1200 ℃, the graphitization temperature of graphite is above 2200 ℃, the temperature of the oven is set to be 240-320 ℃ according to the cracking temperature of the selected substances, and the coated negative plate is baked for 12-24 hours under the protection atmosphere of nitrogen, so that CMC is cracked, the dynamic internal resistance of the battery is improved, and the high-rate cycle performance of the battery is improved.
In the present invention, the negative electrode current collector is not particularly limited as long as it has conductivity, and preferably contains a metal element that is easily diffused into active material particles, the negative electrode current collector is preferably a copper foil or a metal foil formed of an alloy containing copper, the negative electrode slurry is coated on the negative electrode current collector by a coater to obtain a negative electrode sheet, and the negative electrode sheet is separated to obtain a sheet having a width suitable for a lithium ion battery.
In one embodiment, the positive electrode conductive agent is Super-P (conductive carbon black) and KS6 (conductive graphite), the binder is PVDF (polyvinylidene fluoride), and in the manufacturing step of the positive electrode sheet, 94.0-95.0% of positive electrode active material, 1.5-2.5% of Super-P, 0.8-1.2% of KS6 and 1.8-2.2% of PVDF are mixed according to weight percentage, and N-methyl-2-pyrrolidone (NMP) is added and stirred uniformly to obtain positive electrode slurry.
In the present invention, the negative electrode current collector is not particularly limited as long as it has conductivity, and preferably, the positive electrode slurry is coated on the positive electrode current collector by using an aluminum foil through a coating machine to obtain a positive electrode sheet, and the positive electrode sheet is separated to obtain a sheet having a width suitable for a lithium ion battery.
There is no particular limitation on the negative electrode active material to be encountered as long as lithium ions can be intercalated and deintercalated.
In one embodiment, the negative active material includes one or more of artificial graphite, natural graphite, hard carbon, soft carbon, elemental silicon, a silicon-carbon composite, and a silicon oxide. Or the negative active material can be one or more selected from petroleum coke, organic cracking carbon, mesocarbon microbeads, silicon alloy, elemental germanium, elemental tin, tin oxide, transition metal oxide and lithium titanate. In order to obtain more electrochemical performance of the battery, the negative active material is preferably natural graphite or artificial graphite.
In one embodiment, the positive active material includes one or more of a nickel cobalt manganese lithium composite oxide, a nickel cobalt aluminum lithium composite oxide, and a nickel manganese aluminum lithium composite oxide.
Another embodiment of the present invention provides a lithium ion battery, including a positive electrode, a negative electrode and an electrolyte, where the positive electrode and the negative electrode are obtained by the above method for manufacturing a lithium ion battery.
The electrolyte comprises electrolyte, solvent and additive, and as is conventional, the electrolyte, solvent and additive are not particularly limited in the present invention.
The electrolyte may be selected from LiPF6、LiBF4、LiBOB、LiDFOB、LiSbF6、LiAsF6、LiN(SO2CF3)2、LiN(SO2C2F5)2、LiC(SO2CF3)3、LiN(SO2F)2、LiPO2F2、LiP(C2O4)2F2、LiPC2O4F4One or more of (a).
The solvent may be selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate.
The above compounds are part of the claimed invention, but are not limited thereto and should not be construed as limiting the invention.
Preferably, the electrolyte in the present invention is LiPF6The solvent is a mixture of Ethylene Carbonate (EC), dimethyl carbonate (DMC) and Ethyl Methyl Carbonate (EMC), and the additive comprises Propylene Sulfite (PS), fluoroethylene carbonate (FEC), Vinylene Carbonate (VC), Cyclohexylbenzene (CHB) and lithium bis (fluorosulfonyl) imide (LiFSI).
The invention is further described below by way of examples, which take 14650-1000 lithium ion batteries as examples.
Example 1
1) Preparation of negative plate
According to the weight percentage of the negative electrode, 94.8-95.8% of negative electrode active material graphite, 1.0-2.0% of conductive carbon black Super-P, 1.4-1.8% of carboxymethyl cellulose (CMC) and 1.8-2.2% of Styrene Butadiene Rubber (SBR) are mixed, and then dispersed in deionized water to obtain negative electrode slurry.
Coating the negative electrode slurry on two surfaces of a copper foil, rolling, slicing, putting into an oven, heating to 280 ℃, filling nitrogen, baking for 20 hours, taking out the negative electrode plate, and welding a nickel lead wire by using an ultrasonic welding machine to obtain the negative electrode plate.
2) Preparation of Positive plate
According to the weight percentage of the anode, 94.0-95.0% of ternary anode active substance, 1.5-2.5% of conductive carbon black Super-P, 0.8-1.2% of conductive graphite KS6 and 1.8-2.2% of adhesive polyvinylidene fluoride (PVDF) are mixed, and then the mixture is mixed and dispersed in N-methyl-2-pyrrolidone (NMP) to obtain anode slurry. And uniformly coating the anode slurry on two surfaces of the aluminum foil, rolling, slicing, and welding an aluminum outgoing line by using an ultrasonic welding machine to obtain the anode sheet.
3) Preparation of the electrolyte
23.36% Ethylene Carbonate (EC), 31.15% dimethyl carbonate (DMC), and 23.36% Ethyl Methyl Carbonate (EMC) were mixed in percentage by weight of the electrolyte, and then 13.13% lithium hexafluorophosphate (LiPF) was added6) And then adding additives. The additive included 0.5% Propylene Sulfite (PS), 3% fluoroethylene carbonate (FEC), 1% Vinylene Carbonate (VC), 4% Cyclohexylbenzene (CHB), and 0.5% lithium bis-fluorosulfonylimide (LiFSI).
4) Preparation of cell
Placing a three-layer isolating membrane with the thickness of 20 mu m between a positive plate and a negative plate, then winding a sandwich structure consisting of the positive plate, the negative plate and a diaphragm to obtain an electric core, and then carrying out rolling groove on the electric core in a steel shell, and carrying out vacuum baking for 24h at 85 ℃ to obtain the electric core to be injected with liquid.
5) Liquid injection and formation of battery core
And injecting the prepared electrolyte into a battery cell in an environment with the dew point controlled below-40 ℃, sealing, aging at the temperature of sealing, and forming to obtain the lithium ion battery.
Example 2
The same process as in example 1, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and split into pieces and then placed into an oven, the temperature is heated to 260 ℃, nitrogen is filled, and the negative plate is taken out after being baked for 24 hours.
Example 3
The same process as in example 1, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and split into pieces and then placed into an oven, the temperature is increased to 320 ℃, nitrogen is filled, and the negative plate is taken out after being baked for 13H.
Example 4
The same process as in example 1, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and split into pieces and then placed into an oven, the temperature is increased to 240 ℃, nitrogen is filled, and the negative plate is taken out after being baked for 27 hours.
Example 5
The same process as in example 1, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and split into pieces and then placed into an oven, the temperature is heated to 275 ℃, nitrogen is filled, and the negative plate is taken out after being baked for 21H.
Example 6
The same process as in example 1, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and split into pieces and then placed into an oven, the temperature is increased to 300 ℃, nitrogen is filled, and the negative plate is taken out after being baked for 16H.
Example 7
The same process as in example 1, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and split into pieces and then placed into an oven, the temperature is raised to 255 ℃, nitrogen is filled, and the negative plate is taken out after being baked for 24 hours.
Example 8
The same process as in example 1, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and split, then is put into an oven, is heated to 290 ℃, is filled with nitrogen, and is taken out after being baked for 18 hours.
Example 9
The same process as in example 1, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and split into pieces and then placed into an oven, the temperature is increased to 310 ℃, nitrogen is filled, and the negative plate is taken out after being baked for 14H.
Example 10
The same process as in example 1, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and split, then is put into an oven, is heated to 315 ℃, is filled with nitrogen, and is taken out after being baked for 13 hours.
Comparative example 1
The same process as in example 1, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and separated, and then is not baked, and a nickel outgoing line is directly welded on the negative plate by an ultrasonic welding machine.
Comparative example 2
The same process as in example 2, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and separated, and then is not baked, and a nickel outgoing line is directly welded on the negative plate by an ultrasonic welding machine.
Comparative example 3
The same procedure as in example 3, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and separated, and then is not baked, and a nickel outgoing line is directly welded on the negative plate by an ultrasonic welding machine.
Comparative example 4
The same procedure as in example 4, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and separated, and then is not baked, and a nickel outgoing line is directly welded on the negative plate by an ultrasonic welding machine.
Comparative example 5
The same procedure as in example 5, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and separated, and then is not baked, and a nickel outgoing line is directly welded on the negative plate by an ultrasonic welding machine.
Comparative example 6
The same procedure as in example 6, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and separated, and then is not baked, and a nickel outgoing line is directly welded on the negative plate by an ultrasonic welding machine.
Comparative example 7
The same procedure as in example 7, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and separated, and then is not baked, and a nickel outgoing line is directly welded on the negative plate by an ultrasonic welding machine.
Comparative example 8
The same procedure as in example 8, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and separated, and then is not baked, and a nickel outgoing line is directly welded on the negative plate by an ultrasonic welding machine.
Comparative example 9
The same procedure as in example 9, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and separated, and then is not baked, and a nickel outgoing line is directly welded on the negative plate by an ultrasonic welding machine.
Comparative example 10
The same procedure as in example 10, except that:
in the preparation step of the negative plate, the coated negative plate is rolled and separated, and then is not baked, and a nickel outgoing line is directly welded on the negative plate by an ultrasonic welding machine.
Performance testing
The batteries of examples 1 to 10 and comparative examples 1 to 10 thus obtained were subjected to 5C/10C/12C rate cycle charge and discharge test and 15C discharge test.
The cyclic process of 5C/10C/12C multiplying power cyclic charge and discharge comprises the following steps:
step 1: constant-current constant-voltage charging, 2C current charging for 120min, upper limit voltage of 4.2V and cutoff current of 0.01C;
step 2: standing for 5 min;
and step 3: constant current discharge, 5C/10C/12C discharge for 30min, lower limit voltage 3.0V;
and 4, step 4: standing for 5 min;
and 5: the steps 1 to 4 are circulated for 500 times.
The 15C discharge process comprises the following steps:
step 1: constant-current constant-voltage charging, 2C current charging for 120min, upper limit voltage of 4.2V and cutoff current of 0.01C;
step 2: standing for 5 min;
and step 3: constant current discharge, 15C discharge for 30min, and lower limit voltage of 3.0V;
and 4, step 4: standing for 5 min;
the discharge capacity obtained by the test and the temperature data measured during the cycle are filled in table 1.
TABLE 1
Figure BDA0002338631860000101
Figure BDA0002338631860000111
For the battery examples 1-10 and the comparative examples 1-10 manufactured as above, it can be seen from the data in table 1 that after the manufacturing steps of the lithium battery are changed, the discharge capacity and the temperature of the examples 1-10 are slightly better than those of the comparative examples 1-10 during 5C discharge, and the influence on the discharge capacity and the temperature is not great, and as the discharge rate is increased, the increased capacity value and the decreased temperature value of the examples 1-10 relative to the comparative examples 1-10 tend to increase, which shows that as the rate is increased during high-rate charge and discharge, the thickener CMC has a greater influence on the dynamic internal resistance of the battery, and has a greater influence on the cycle performance of the battery.
As a result of testing the dynamic internal resistances of the batteries of examples 2, 4 and 8 and comparative examples 2, 4 and 8 at 70 ℃ and 50% S0C (Stage of Charge state), as shown in fig. 2, the black line represents the dynamic internal resistance of the batteries of examples, and the gray line represents the dynamic internal resistance of the batteries of comparative examples.
When 12C is discharged, the discharge capacity is obviously improved, the temperature is obviously reduced, after the 12C multiplying power is circularly charged and discharged for 500 circles, the capacity retention rate is shown as figure 1, a gray line in figure 1 is a capacity retention rate curve of an embodiment, and a black line can be seen as a capacity retention rate curve of a comparative example.
When 15C is discharged, the discharge capacity of the comparative examples 1-10 is very low, and the discharge cannot be realized, while the discharge capacity is greatly improved and the discharge temperature is obviously reduced in the examples 1-10, so that the manufacturing method of the lithium ion battery provided by the invention has the advantages that after the CMC is cracked, the discharge capacity of the battery is improved at a high rate of 15C, the battery can smoothly discharge, and the problem that the existing battery 15C cannot discharge is solved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (6)

1. A manufacturing method of a lithium ion battery is characterized by comprising the following steps:
preparing a negative plate, namely mixing a negative active substance, a negative conductive agent, a thickening agent and a binder, dissolving the mixture in a solvent, uniformly stirring to obtain negative slurry, and coating the negative slurry on a negative current collector to obtain the negative plate;
preparing a positive plate, namely mixing a positive active substance, a positive conductive agent and a binder, dissolving the mixture in a solvent, uniformly stirring to obtain positive slurry, and coating the positive slurry on a positive current collector to obtain the positive plate;
after the negative plate is sliced, baking the negative plate for 12-24 hours at 240-320 ℃ under the protection of nitrogen;
and (3) manufacturing the battery, namely assembling the positive plate, the baked negative plate and the diaphragm into a battery core, packaging the battery core into a shell, injecting electrolyte and sealing to form the lithium ion battery.
2. The method for manufacturing a lithium ion battery according to claim 1, wherein in the step of manufacturing the negative electrode sheet, 94.8 to 95.8 weight percent of negative electrode active material, 1.0 to 2.0 weight percent of conductive carbon black, 1.4 to 1.8 weight percent of sodium carboxymethyl cellulose and 1.8 to 2.2 weight percent of styrene butadiene rubber are mixed, added with a solvent and stirred uniformly to obtain negative electrode slurry.
3. The method for manufacturing a lithium ion battery according to claim 1, wherein in the step of manufacturing the positive electrode sheet, 94.0 to 95.0 percent of positive electrode active material, 1.5 to 2.5 percent of conductive carbon black, 0.8 to 1.2 percent of conductive graphite and 1.8 to 2.2 percent of polyvinylidene fluoride are mixed according to weight percentage, and a solvent is added and stirred uniformly to obtain positive electrode slurry.
4. The method of claim 1, wherein the negative active material comprises one or more of artificial graphite, natural graphite, hard carbon, soft carbon, elemental silicon, silicon-carbon composite, and silicon oxide.
5. The method of claim 1, wherein the positive electrode active material comprises one or more of a nickel-cobalt-manganese lithium composite oxide, a nickel-cobalt-aluminum lithium composite oxide, and a nickel-manganese-aluminum lithium composite oxide.
6. A lithium ion battery comprises a positive electrode, a negative electrode and an electrolyte, and is characterized in that the positive electrode and the negative electrode are obtained by the manufacturing method of the lithium ion battery according to any one of claims 1-5.
CN201911366812.7A 2019-12-26 2019-12-26 Manufacturing method of lithium ion battery and lithium ion battery Pending CN111009692A (en)

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WO2023082248A1 (en) * 2021-11-15 2023-05-19 宁德新能源科技有限公司 Electrode and fabricating method therefor, electrochemical device, and electronic device

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Application publication date: 20200414