CN113659191A - Power type low-temperature lithium battery and preparation method thereof - Google Patents

Power type low-temperature lithium battery and preparation method thereof Download PDF

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CN113659191A
CN113659191A CN202110945215.0A CN202110945215A CN113659191A CN 113659191 A CN113659191 A CN 113659191A CN 202110945215 A CN202110945215 A CN 202110945215A CN 113659191 A CN113659191 A CN 113659191A
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lithium
lithium battery
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battery
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曹智铭
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Henan Fusen New Energy Technology Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
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    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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Abstract

The invention relates to the technical field of lithium batteries, in particular to a power type low-temperature lithium battery and a preparation method thereof, wherein the lithium battery comprises a positive current collector and a positive plate coated on the positive current collector, and is prepared from the following raw materials in parts by weight: 90-98 parts of lithium cobaltate, 0.4-2 parts of a nanotube conductive agent, 0.4-2 parts of a conductive agent, 6-0.8 part of a binder, 94-97 parts of graphite, 0.4-2 parts of conductive carbon black, 1-5 parts of a polyacrylate binder and 0.5-2 parts of an additive. The invention has the advantages that: the lithium battery can detect that the discharge capacity reaches more than 80% of the initial capacity under the environment condition of 25 ℃ under the environment condition of-40 ℃ by 3C, the power performance under the low-temperature condition is excellent, the safety performance is outstanding, compared with the existing lithium battery, the discharge capacity reaches 70% of the capacity under the environment condition of 25 ℃ under the low-temperature condition by 0.2C, the improvement is large, the application field range is widened, and meanwhile, the safety problem of the lithium battery is relatively solved.

Description

Power type low-temperature lithium battery and preparation method thereof
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a power type low-temperature lithium battery and a preparation method thereof.
Background
Currently, lithium ion batteries are in the leading position with absolute advantages in the 3C (computer, communication, consumer electronics) field compared to nickel-hydrogen and nickel-cadmium batteries; meanwhile, in order to meet the requirements of energy conservation and environmental protection, electric vehicles (including electric bicycles and electric automobiles) have wide market prospects. As a power source of an electric vehicle, a lithium ion battery has a very large competitive power.
However, lithium ion batteries also have their own drawbacks; the battery with excellent cycle performance under the normal temperature condition has obviously reduced service life and safety under the high temperature environment condition; especially under the low temperature condition, the discharge capacity is reduced, the service time is shortened, the working force is weakened, and the dynamic performance is deteriorated; the lithium battery industry reaches 5 months to 8 months every year, and the concentrated outbreak frequency of safety accidents in various fields using the lithium battery is particularly high. The lithium battery which works under the low-temperature condition is disassembled, and the lithium precipitation phenomenon exists on the surface of the negative electrode; the accident frequency is increased along with the change of seasons from working under the low-temperature condition to working under the high-temperature condition, which shows that the lithium precipitation problem generated by the low-temperature charging and discharging of the lithium battery is not only related to the reduction of the actual use capacity, the deterioration of the power performance and the reduction of the safety performance more seriously.
In view of the above, it is desirable to provide a low temperature lithium battery of power type.
Disclosure of Invention
The invention aims to: provides a high-power low-temperature lithium ion battery and positive and negative pole pieces required by manufacturing the same.
The above object of the present invention is achieved by the following technical solutions:
a power type low-temperature lithium battery and a preparation method thereof are provided, the lithium battery comprises a positive current collector and a positive plate coated on the positive current collector, and the lithium battery is prepared from the following raw materials in parts by weight: 90-98 parts of lithium cobaltate, 0.4-2 parts of a nanotube conductive agent, 0.4-2 parts of a conductive agent, 6-0.8 part of a binder, 94-97 parts of graphite, 0.4-2 parts of conductive carbon black, 1-5 parts of a polyacrylate binder and 0.5-2 parts of an additive.
The invention is further configured to: the positive plate comprises a positive active substance, a conductive agent and cohesiveness, wherein the positive active substance is lithium cobaltate, lithium manganate or a mixture of the lithium cobaltate and the lithium manganate. .
The invention is further configured to: lithium cobaltate in the positive active material is of a single-crystal energy type, and the surface of the lithium cobaltate is coated with metal oxides such as Al2O3, TiO2 and Mg.
The invention is further configured to: in the positive electrode active material, the lithium cobaltate is lithium cobaltate D10 ═ 5 μm, D50 ═ 8 μm and D90 ═ 13 μm, the specific surface area is 0.35m2/g, and the tap density is 2.56g/cm 3.
The invention is further configured to: the conductive agent nanotube of the positive plate has the tube diameter of 10-20nm, the tube length of 5-12 μm, and the specific surface area of 200-300m 2/g.
The invention is further configured to: the graphite is a mixture of secondary-particle artificial graphite and natural graphite, and the doping ratio is 2: 8-8: 2.
The invention is further configured to: the adhesive is one of polyacrylic acid, polyacrylic nitrile and a polymer containing acrylic acid monomer/acrylic nitrile monomer.
The invention is further configured to: the lithium battery is prepared by the following steps:
s1: preparing lithium battery anode slurry and an anode plate: (1) preparing a material, wherein a single-particle coated oxide large-particle lithium cobaltate is used as a positive electrode active material, and the weight content (relative to the weight of powder, the same applies below) of the material is 95.5%; polyvinylidene fluoride (PVDF with the molecular weight of 130 ten thousand) is taken as a binder, and the weight content of the polyvinylidene fluoride is 1.0 percent; the carbon nano tube, the conductive carbon black and the conductive graphite are used as conductive agents, and the weight contents of the conductive carbon nano tube, the conductive carbon black and the conductive graphite are respectively 1.5%, 1.0% and 1.0%; (2) mixing and stirring the materials; (3) adding solvent methyl pyrrolidone (NMP) and continuously stirring to prepare anode slurry; (4) uniformly coating the positive electrode slurry on a positive electrode current collector aluminum foil, drying and compacting, cutting, welding a positive electrode lug, and sticking high-temperature adhesive paper to obtain a positive electrode plate;
s2: preparing a negative plate: (1) preparing a material, wherein artificial and natural composite graphite with soft carbon coated on the surface and subjected to secondary granulation is used as a negative electrode active material, and the weight content of the material is 94.5%; taking acrylate LA-133 as a binder, wherein the weight content of the acrylate LA-133 is 3.5%; carbon black (S-P) is used as a conductive agent, and the weight content of the carbon black is 2 percent; (2) mixing and stirring the materials; (3) after uniformly stirring, adding deionized water and an additive (ethylene carbonate) and continuously stirring to prepare cathode slurry; (4) uniformly coating the negative electrode slurry on a copper foil of a negative current collector, drying and compacting, cutting, welding a negative electrode tab, and sticking high-temperature adhesive paper to prepare a negative electrode sheet;
s3: preparing an isolating membrane: coating a base film with the thickness of 14 microns with 2 microns of Al2O3 and a polyethylene microporous film with the porosity of 45 percent as an isolating film;
s4: preparing an electrolyte: lithium hexafluorophosphate is used as lithium salt, a mixture of Ethyl Propylene (EP), Ethyl Acetate (EA), Ethylene Carbonate (EC) and Ethyl Methyl Carbonate (EMC) is used as solvent, and the weight ratio of EA to EP to EMC to 1: 1: 1:1. Dissolving lithium hexafluorophosphate in a mixed solvent (the concentration is 1.2M), and then adding 3% of electrolyte additives of fluoroethylene carbonate (FEC), 0.5% of Vinylene Carbonate (VC), 0.5% of Propylene Sulfite (PS) and 0.5% of lithium difluorophosphate to prepare an electrolyte;
s5: preparing a lithium ion battery: and (4) sequentially stacking the negative plate, the positive plate and the diaphragm prepared in the steps S1-S4, preparing a battery cell through a winding process, transferring the battery cell into a battery steel shell accessory, injecting electrolyte into the battery cell, sealing, forming and the like to obtain the lithium battery.
The invention is further configured to: the separator in the step S5 is a PP or PE separator, and the surface of the separator is coated with 2 to 4 μm al2O3, polyvinylidene fluoride, or the like.
The invention is further configured to: the electrolyte in step S4 contains 1.2molLiPF6, EC/EMC/EA/EP equal to 1: 1: 1:1, 3-5% of FEC, 0.2-1% of PS and 0.2-1% (lithium difluorophosphate, LiFSL, LiODFB and LiBF 4).
In conclusion, the beneficial technical effects of the invention are as follows:
the lithium battery can detect that the discharge capacity reaches more than 80 percent of the initial capacity under the environment condition of 25 ℃ under the environment condition of minus 40 ℃ by 3C, shows excellent power performance under the low temperature condition, shows more outstanding safety performance, and compared with the prior lithium battery, the discharge capacity reaches 70 percent under the environment condition of 25 ℃ under the low temperature condition, the discharge capacity is greatly improved, and widens the application field range, meanwhile, the safety problem of the lithium battery is relatively solved.
The present invention will be described in further detail with reference to comparative examples and examples.
Comparative example
Preparing lithium battery anode slurry and an anode plate: the small-particle power type lithium cobaltate is taken as the positive active material, and the weight content (relative to the weight of the powder, the same is shown below) is 96.4 percent; polyvinylidene fluoride (PVDF with the molecular weight of 130 ten thousand) is taken as a binder, and the weight content of the polyvinylidene fluoride is 1.6 percent; the nano tube and the conductive carbon black are used as conductive agents, and the weight content of the conductive carbon black is 1% and 1.0% respectively. The materials are stirred for 2 hours in a dry mixing mode by adopting a stirring rotating speed of 30HZ and a dispersion speed of 200rpm, a solvent of methyl pyrrolidone (NMP) is added, a circulating water normal-temperature cooling system of a stirrer is opened to set the temperature to be less than or equal to 35 ℃, the materials are stirred for 5 hours by adopting a stirring rotating speed of 40HZ and a dispersion speed of 2000rpm to prepare anode slurry, and the viscosity and the fineness of the slurry are tested after the temperature is reduced to the normal temperature. And uniformly coating the positive slurry on a positive current collector aluminum foil, drying and compacting, cutting, welding a positive lug, and sticking high-temperature adhesive paper to obtain the positive plate.
Preparing a negative plate: artificial graphite is used as a negative active material, and the weight content of the artificial graphite is 94%; sodium carboxymethylcellulose (CMC) is taken as a thickening agent, and the weight content of the CMC is 1.7 percent; carbon black (S-P) is used as a conductive agent, and the weight content of the conductive agent is 2 percent. The materials are uniformly stirred in a dry mixing mode, then deionized water is added for continuous stirring, and after the materials are uniformly stirred, styrene butadiene rubber emulsion (SBR) (the weight content is 2.3 percent) is added for uniform stirring to prepare cathode slurry. And uniformly coating the negative electrode slurry on a copper foil of a negative current collector, drying and compacting, cutting, welding a negative electrode tab, and sticking high-temperature adhesive paper to prepare the negative electrode sheet.
Preparing an isolating membrane: a polyethylene microporous membrane with the thickness of 16 microns and the porosity of 45 percent is taken as an isolating membrane.
Preparing an electrolyte: lithium hexafluorophosphate is used as lithium salt, a mixture of Propylene Carbonate (PC), Ethylene Carbonate (EC) and dimethyl carbonate (DMC) is used as a solvent, and the weight ratio of the propylene carbonate, the ethylene carbonate and the dimethyl carbonate is PC, EC, DMC 1: 1: 1. after lithium hexafluorophosphate was dissolved in the mixed solvent (concentration: 1.2M), 1% of Vinylene Carbonate (VC) as an electrolyte additive was added.
Preparing a lithium ion battery: and (3) sequentially stacking the negative plate, the positive plate and the diaphragm prepared by the process, preparing a battery core by a winding process, transferring the battery core into a battery steel shell accessory, injecting electrolyte into the battery steel shell accessory, sealing, forming and the like to prepare the lithium ion battery of the comparative example.
Example 1
Preparing lithium battery anode slurry and an anode plate: the single-particle coated oxide large-particle lithium cobaltate is used as a positive electrode active substance, and the weight content (relative to the weight of powder, the same is shown below) is 95.5 percent; polyvinylidene fluoride (PVDF with the molecular weight of 130 ten thousand) is taken as a binder, and the weight content of the polyvinylidene fluoride is 1.0 percent; the carbon nano tube, the conductive carbon black and the conductive graphite are used as conductive agents, and the weight contents of the conductive carbon nano tube, the conductive carbon black and the conductive graphite are respectively 1.5%, 1.0% and 1.0%. The materials are stirred for 2 hours in a dry mixing mode by adopting a stirring rotating speed of 30HZ and a dispersion speed of 200rpm, a solvent of methyl pyrrolidone (NMP) is added, a circulating water normal-temperature cooling system of a stirrer is opened to set the temperature to be less than or equal to 35 ℃, the materials are stirred for 5 hours by adopting a stirring rotating speed of 40HZ and a dispersion speed of 2000rpm to prepare anode slurry, and the viscosity and the fineness of the slurry are tested after the temperature is reduced to the normal temperature. And uniformly coating the positive slurry on a positive current collector aluminum foil, drying and compacting, cutting, welding a positive lug, and sticking high-temperature adhesive paper to obtain the positive plate.
Preparing a negative plate: artificial and natural composite graphite with soft carbon coated on the surface and subjected to secondary granulation is taken as a negative active material, and the weight content of the artificial and natural composite graphite is 94.5%; taking acrylate LA-133 as a binder, wherein the weight content of the acrylate LA-133 is 3.5%; carbon black (S-P) is used as a conductive agent, and the weight content of the conductive agent is 2 percent. The materials are uniformly stirred in a dry mixing mode, and then deionized water and an additive (ethylene carbonate) are added for continuous and uniform stirring to prepare cathode slurry. And uniformly coating the negative electrode slurry on a copper foil of a negative current collector, drying and compacting, cutting, welding a negative electrode tab, and sticking high-temperature adhesive paper to prepare the negative electrode sheet.
Preparing an isolating membrane: a base film with the thickness of 14 micrometers is coated with 2 micrometers of Al2O3, and a polyethylene microporous film with the porosity of 45% is used as a separation film.
Preparing an electrolyte: lithium hexafluorophosphate is used as lithium salt, a mixture of Ethyl Propylene (EP), Ethyl Acetate (EA), Ethylene Carbonate (EC) and Ethyl Methyl Carbonate (EMC) is used as solvent, and the weight ratio of EA to EP to EMC to 1: 1: 1:1. After lithium hexafluorophosphate was dissolved in the mixed solvent (concentration: 1.2M), 3% of electrolyte additive fluoroethylene carbonate (FEC), 0.5% of Vinylene Carbonate (VC), 0.5% of Propylene Sulfite (PS), and 0.5% of lithium difluorophosphate were added.
Preparing a lithium ion battery: and (3) sequentially stacking the negative plate, the positive plate and the diaphragm prepared by the process, preparing a battery core by a winding process, transferring the battery core into a battery steel shell accessory, injecting electrolyte into the battery steel shell accessory, sealing, forming and the like to prepare the lithium ion battery of the embodiment I.
Example 2
Preparing lithium battery anode slurry and an anode plate: the single-particle coated oxide large-particle lithium cobaltate is used as a positive electrode active substance, and the weight content (relative to the weight of powder, the same is shown below) of the positive electrode active substance is 95.4 percent; polyvinylidene fluoride (PVDF with the molecular weight of 130 ten thousand) is taken as a binder, and the weight content of the polyvinylidene fluoride is 1.0 percent; the carbon nano tube, the conductive carbon black and the conductive graphite are used as conductive agents, and the weight contents of the conductive carbon nano tube, the conductive carbon black and the conductive graphite are respectively 1.2%, 1.2% and 1.2%. The materials are stirred for 2 hours in a dry mixing mode by adopting a stirring rotating speed of 30HZ and a dispersion speed of 200rpm, a solvent of methyl pyrrolidone (NMP) is added, a circulating water normal-temperature cooling system of a stirrer is opened to set the temperature to be less than or equal to 35 ℃, the materials are stirred for 5 hours by adopting a stirring rotating speed of 40HZ and a dispersion speed of 2000rpm to prepare anode slurry, and the viscosity and the fineness of the slurry are tested after the temperature is reduced to the normal temperature. And uniformly coating the positive slurry on a positive current collector aluminum foil, drying and compacting, cutting, welding a positive lug, and sticking high-temperature adhesive paper to obtain the positive plate.
Preparing a negative plate: artificial graphite is used as a negative active material, and the weight content of the artificial graphite is 94%; polyvinylidene fluoride (PVDF with a molecular weight of 100 ten thousand) is used as a binder, and the weight content of the polyvinylidene fluoride is 4 percent; carbon black (S-P) is used as a conductive agent, and the weight content of the conductive agent is 2 percent. The materials are uniformly stirred in a dry mixing mode, and then the solvent methyl pyrrolidone (NMP) is added, and the materials are continuously and uniformly stirred to prepare the cathode slurry. And uniformly coating the negative electrode slurry on a copper foil of a negative current collector, drying and compacting, cutting, welding a negative electrode tab, and sticking high-temperature adhesive paper to prepare the negative electrode sheet.
Preparing an isolating membrane: a base film with the thickness of 14 micrometers is coated with 2 micrometers of Al2O3, and a polyethylene microporous film with the porosity of 45% is used as a separation film.
Preparing an electrolyte: lithium hexafluorophosphate is used as lithium salt, a mixture of Ethyl Propylene (EP), Ethyl Acetate (EA), Ethylene Carbonate (EC) and Ethyl Methyl Carbonate (EMC) is used as solvent, and the weight ratio of EA to EP to EMC to 1: 1: 1:1. After lithium hexafluorophosphate was dissolved in the mixed solvent (concentration: 1.2M), 3% of electrolyte additive fluoroethylene carbonate (FEC), 0.5% of Vinylene Carbonate (VC), 0.5% of Propylene Sulfite (PS), and 0.5% of lithium difluorophosphate were added.
Preparing a lithium ion battery: and sequentially stacking the negative plate, the positive plate and the diaphragm prepared by the process, preparing a battery core by a winding process, transferring the battery core into a battery steel shell accessory, injecting electrolyte into the battery steel shell accessory, sealing, forming and the like to prepare the lithium ion battery of the second embodiment.
The lithium ion batteries of comparative example, example one and example two were left to stand at 25 ℃ for 48 hours, charged at 25 ℃ for 120 minutes at a constant current of 0.05C, then charged at a constant current of 0.1C for 120 minutes, and then charged at a constant current and constant voltage of 0.5C to 4.2V, cut off at a current of 0.02C, left to stand for 5 minutes, and discharged at a constant current of 0.5C to 2.5V, and left to stand for 5 minutes. After the test is carried out for 2 weeks in such a circulating way, the constant current and the constant voltage of 0.5C are charged to 3.90V, the current is cut off to 0.02C, and the test is placed aside for 168 hours for carrying out related sampling test.
The lithium ion batteries of comparative example, example one and example two were charged at 25 ℃ at a constant current and constant voltage of 0.5C to 4.2V, the current was cut off at 0.02C, left for 5 minutes, and discharged at a constant current of 0.5C to 2.5V, left for 5 minutes. After the test is carried out for 2 weeks in such a circulating way, the battery is charged to 4.2V at a constant current and a constant voltage of 0.5C, the current is cut off at 0.01C, the battery is placed for 24 hours under the environment condition of minus 40 ℃, and the battery is discharged to 2.5V at a constant current of 3C. The ratio of the discharge capacity at-40 ℃ to the discharge capacity at 25 ℃ was calculated. And meanwhile, charging to 4.2V at a constant current and a constant voltage of 0.5C under the environment condition of-10 ℃, stopping the current at 0.02C, standing for 5 minutes, discharging to 2.5V at a constant current of 0.5C, and standing for 5 minutes. After the test is carried out for 2 weeks in the circulation way, the battery is charged to 4.2V by a constant current and a constant voltage of 0.5C, and the current is cut off by 0.01C. And after the test is finished, disassembling the cabinet to observe the lithium precipitation condition on the surface of the negative electrode.
According to the above test method, the results are shown in the following table:
Figure BDA0003216524960000081
the following conclusions were drawn by comparison:
in the comparative example, the discharge capacity ratio of the lithium battery manufactured by the positive and negative pole pieces of the traditional lithium battery under the conditions of-40 ℃ and 0.2C and 25 ℃ is 69.2 percent; the phenomenon of serious lithium precipitation exists on the surface of the cathode of the disassembled battery after charging and discharging at the temperature of minus 10 ℃, which shows that the traditional scheme has low discharge capacity and certain potential safety hazard on subsequent use. Compared with the second example, the ratio of the 3C discharge capacity at the temperature of-40 ℃ to the discharge capacity at the temperature of 25 ℃ in the first example is 7 percentage points higher than that in the second example, the surface of the negative electrode of the disassembled battery after charging and discharging at the temperature of-10 ℃ is good, and the surface of the negative electrode of the second example has slight lithium precipitation. According to the invention, the power characteristics, low temperature and use safety of the lithium battery can be solved in multiple dimensions only by reasonably using the positive electrode material particle coating, the three-dimensional conductive network establishment, the negative electrode sheet graphite modification, the negative electrode binder matching, the coating diaphragm, the electrolyte solvent system and the low temperature additive in the positive electrode sheet and carrying out matching adjustment on the system.
The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.

Claims (10)

1. A power type low temperature lithium battery is characterized in that: the lithium battery comprises a positive current collector and a positive plate coated on the positive current collector, and is prepared from the following raw materials in parts by weight: 90-98 parts of lithium cobaltate, 0.4-2 parts of a nanotube conductive agent, 0.4-2 parts of a conductive agent, 6-0.8 part of a binder, 94-97 parts of graphite, 0.4-2 parts of conductive carbon black, 1-5 parts of a polyacrylate binder and 0.5-2 parts of an additive.
2. The power type low temperature lithium battery of claim 1 and the method of manufacturing the same, wherein: the positive plate comprises a positive active substance, a conductive agent and cohesiveness, wherein the positive active substance is lithium cobaltate, lithium manganate or a mixture of the lithium cobaltate and the lithium manganate.
3. The power type low temperature lithium battery of claim 2 and the method of manufacturing the same, wherein: lithium cobaltate in the positive active material is of a single-crystal energy type, and the surface of the lithium cobaltate is coated with metal oxides such as Al2O3, TiO2 and Mg.
4. The power type low temperature lithium battery of claim 2 and the method of manufacturing the same, wherein: the positive electrode active material contains lithium cobaltate D10 ═ 5 μm, D50 ═ 8 μm, and D90 ═ 13 μm, and has a specific surface area of 0.35m2(g), tap density 2.56g/cm3。
5. The power type low temperature lithium battery of claim 2 and the method of manufacturing the same, wherein: the conductive agent nanotube of the positive plate has a tube diameter of 10-20nm, a tube length of 5-12 μm, and a specific surface area of 200-300m2/g。
6. The power type low temperature lithium battery of claim 1 and the method of manufacturing the same, wherein: the graphite is a mixture of secondary-particle artificial graphite and natural graphite, and the doping ratio is 2: 8-8: 2.
7. The power type low temperature lithium battery of claim 1 and the method of manufacturing the same, wherein: the adhesive is one of polyacrylic acid, polyacrylic nitrile and a polymer containing acrylic acid monomer/acrylic nitrile monomer.
8. The method of claim 1, wherein the step of preparing the power type low temperature lithium battery comprises: the lithium battery is prepared by the following steps:
s1: preparing lithium battery anode slurry and an anode plate: (1) preparing a material, wherein a single-particle coated oxide large-particle lithium cobaltate is used as a positive electrode active material, and the weight content (relative to the weight of powder, the same applies below) of the material is 95.5%; polyvinylidene fluoride (PVDF with the molecular weight of 130 ten thousand) is taken as a binder, and the weight content of the polyvinylidene fluoride is 1.0 percent; the carbon nano tube, the conductive carbon black and the conductive graphite are used as conductive agents, and the weight contents of the conductive carbon nano tube, the conductive carbon black and the conductive graphite are respectively 1.5%, 1.0% and 1.0%; (2) mixing and stirring the materials; (3) adding solvent methyl pyrrolidone (NMP) and continuously stirring to prepare anode slurry; (4) uniformly coating the positive electrode slurry on a positive electrode current collector aluminum foil, drying and compacting, cutting, welding a positive electrode lug, and sticking high-temperature adhesive paper to obtain a positive electrode plate;
s2: preparing a negative plate: (1) preparing a material, wherein artificial and natural composite graphite with soft carbon coated on the surface and subjected to secondary granulation is used as a negative electrode active material, and the weight content of the material is 94.5%; taking acrylate LA-133 as a binder, wherein the weight content of the acrylate LA-133 is 3.5%; carbon black (S-P) is used as a conductive agent, and the weight content of the carbon black is 2 percent; (2) mixing and stirring the materials; (3) after uniformly stirring, adding deionized water and an additive (ethylene carbonate) and continuously stirring to prepare cathode slurry; (4) uniformly coating the negative electrode slurry on a copper foil of a negative current collector, drying and compacting, cutting, welding a negative electrode tab, and sticking high-temperature adhesive paper to prepare a negative electrode sheet;
s3: preparing an isolating membrane: coating a base film with the thickness of 14 microns with 2 microns of Al2O3 and a polyethylene microporous film with the porosity of 45 percent as an isolating film;
s4: preparing an electrolyte: lithium hexafluorophosphate is used as lithium salt, a mixture of Ethyl Propylene (EP), Ethyl Acetate (EA), Ethylene Carbonate (EC) and Ethyl Methyl Carbonate (EMC) is used as solvent, and the weight ratio of EA to EP to EMC to 1: 1: 1:1. Dissolving lithium hexafluorophosphate in a mixed solvent (the concentration is 1.2M), and then adding 3% of electrolyte additives of fluoroethylene carbonate (FEC), 0.5% of Vinylene Carbonate (VC), 0.5% of Propylene Sulfite (PS) and 0.5% of lithium difluorophosphate to prepare an electrolyte;
s5: preparing a lithium ion battery: and (4) sequentially stacking the negative plate, the positive plate and the diaphragm prepared in the steps S1-S4, preparing a battery cell through a winding process, transferring the battery cell into a battery steel shell accessory, injecting electrolyte into the battery cell, sealing, forming and the like to obtain the lithium battery.
9. The power type low temperature lithium battery of claim 8 wherein: the diaphragm in the step S5 is a PP or PE diaphragm, and the surface of the diaphragm is coated with 2-4 mu mAl2O3Polyvinylidene fluoride, and the like.
10. The power type low temperature lithium battery of claim 8 wherein: the electrolyte in step S4 contains 1.2molLiPF6, EC/EMC/EA/EP equal to 1: 1: 1:1, 3-5% of FEC, 0.2-1% of PS and 0.2-1% (lithium difluorophosphate, LiFSL, LiODFB and LiBF 4).
CN202110945215.0A 2021-08-17 2021-08-17 Power type low-temperature lithium battery and preparation method thereof Pending CN113659191A (en)

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Publication number Priority date Publication date Assignee Title
CN103682297A (en) * 2013-11-22 2014-03-26 深圳市迪凯特电池科技有限公司 High-voltage lithium ion secondary battery
CN103779602A (en) * 2014-02-13 2014-05-07 东莞市安德丰电池有限公司 Lithium ion battery and preparation method thereof
CN109698380A (en) * 2018-12-28 2019-04-30 天能电池(芜湖)有限公司 A kind of high-capacity lithium ion power battery and its material preparation process
CN111244393A (en) * 2020-01-20 2020-06-05 珠海冠宇电池有限公司 Pole piece with novel conductive agent distribution structure and lithium ion battery comprising same
CN111969250A (en) * 2020-08-26 2020-11-20 深圳市优帮迪科技有限公司 Electrolyte of lithium ion battery capable of being rapidly charged at low temperature, lithium ion battery and preparation method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103682297A (en) * 2013-11-22 2014-03-26 深圳市迪凯特电池科技有限公司 High-voltage lithium ion secondary battery
CN103779602A (en) * 2014-02-13 2014-05-07 东莞市安德丰电池有限公司 Lithium ion battery and preparation method thereof
CN109698380A (en) * 2018-12-28 2019-04-30 天能电池(芜湖)有限公司 A kind of high-capacity lithium ion power battery and its material preparation process
CN111244393A (en) * 2020-01-20 2020-06-05 珠海冠宇电池有限公司 Pole piece with novel conductive agent distribution structure and lithium ion battery comprising same
CN111969250A (en) * 2020-08-26 2020-11-20 深圳市优帮迪科技有限公司 Electrolyte of lithium ion battery capable of being rapidly charged at low temperature, lithium ion battery and preparation method

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