CN112349968A - Preparation method of lithium ion battery - Google Patents

Preparation method of lithium ion battery Download PDF

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Publication number
CN112349968A
CN112349968A CN202011256623.7A CN202011256623A CN112349968A CN 112349968 A CN112349968 A CN 112349968A CN 202011256623 A CN202011256623 A CN 202011256623A CN 112349968 A CN112349968 A CN 112349968A
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active material
electrolyte
anode
uniformly stirring
cathode
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陈来宾
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Suzhou Electric Information Technology Co ltd
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Suzhou Electric Information 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • 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
    • 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • 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
    • 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
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • Y—GENERAL 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
    • 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
    • Y—GENERAL 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides a preparation method of a lithium ion battery, which comprises the steps of preparing a cathode and an anode of the lithium ion battery, wherein the cathode comprises a first active material and a second active material which are mixed in a preset mass ratio, and the anode comprises graphite as an active material; and placing the anode in a pretreatment electrolyte for pretreatment, wherein an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, assembling the pretreated electrolyte and the cathode into a lithium ion battery, and injecting the lithium ion battery into the electrolyte, wherein the additive in the electrolyte is fluoroethylene carbonate for formation, so that the lithium ion battery is obtained, and the lithium ion battery has good high-rate cycle performance at low temperature.

Description

Preparation method of lithium ion battery
Technical Field
The invention relates to a preparation method of a lithium ion battery.
Background
Lithium ion batteries have been used in numerous civil and military applications, such as mobile phones, notebook computers, video cameras, digital cameras, and the like. Lithium ion batteries are considered to be a new type of power source that meets the increasing energy demands of portable electronic devices, electric and hybrid vehicles. However, in a low-temperature environment, the interface migration resistance increases due to the increase in the viscosity of the electrolyte, and the high-rate charge and discharge performance is poor in the low-temperature environment.
Disclosure of Invention
The invention provides a preparation method of a lithium ion battery, which comprises the steps of preparing a cathode and an anode of the lithium ion battery, wherein the cathode comprises a first active material and a second active material which are mixed in a preset mass ratio, and the anode comprises graphite as an active material; and placing the anode in a pretreatment electrolyte for pretreatment, wherein an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, assembling the pretreated electrolyte and the cathode into a lithium ion battery, and injecting the lithium ion battery into the electrolyte, wherein the additive in the electrolyte is fluoroethylene carbonate for formation, so that the lithium ion battery is obtained, and the lithium ion battery has good high-rate cycle performance at low temperature.
The specific scheme is as follows:
a method of making a lithium ion battery, the method comprising:
1) providing a first active material and a second active material, wherein the average particle size of the first active material is D50, and the average particle size of the second active material is D50';
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: 0.85-k (D50/D50') 2, wherein k is 0.58;
3) coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, and a counter electrode is a lithium sheet;
7) performing charge-discharge cycle between 0.02-0.25V, adjusting voltage to 0.22-0.25V, taking out anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting electrolyte, wherein an additive in the electrolyte is fluoroethylene carbonate;
10) charging to a first preset voltage, and then charging at a constant voltage of the first preset voltage until the charging current is lower than the charging cut-off current;
11) and carrying out charge-discharge circulation for a plurality of times between the charge cut-off voltage and the discharge cut-off voltage to obtain the lithium ion battery.
Further, the first active material is spinel lithium manganate, and the average particle size D50 is 1.4-1.5 microns; the second active material is a ternary material having an average particle size D50' of 2.0-2.2 microns.
Further, in the cathode slurry, the mass ratio of active material: adhesive: the conductive agent is 100:4.2: 4.
Further, the graphite material has an average particle size D50 of 1.8 to 1.9 μm, and in the anode slurry, the mass ratio of active material: adhesive: the conductive agent is 100:4.5: 4.
Further, in the pretreatment electrolyte, the 1-ethyl-2-piperidone accounts for 3.2-3.5 vol%, and the 1, 3-propane sultone accounts for 6.4-6.6 vol%, wherein the total content of the 1-ethyl-2-piperidone and the 1, 3-propane sultone is less than 10 vol%.
Further, in the electrolyte, the linear dimethyl carbonate accounts for more than 70 volume percent of the total volume of the electrolyte, and the volume content of the fluoroethylene carbonate is 2.5-2.7 volume percent.
Further, the first predetermined voltage is 3.46-m volume content (V) of fluoroethylene carbonate, wherein m is 2.6.
The invention has the following beneficial effects:
1) the first active material and the second active material are mixed according to a specific mass ratio, so that the stability of the slurry and the structural stability of the active layer can be improved, and the circulation stability of the material can be improved.
2) The electrolyte contains 1-ethyl-2-piperidone and 1, 3-propane sultone, a low-resistance SEI film can be formed on the surface of the graphite cathode, the circulation stability under high multiplying power can be improved, but when the 1-ethyl-2-piperidone and the 1, 3-propane sultone are in the electrolyte, the low-temperature performance of the battery is negatively influenced, so that the 1-ethyl-2-piperidone and the 1, 3-propane sultone are placed in the pretreated electrolyte, only the graphite cathode is pretreated, and the multiplying power performance can be improved while the low-temperature performance is not influenced.
3) And fluoroethylene carbonate is added into the electrolyte, so that the low-temperature performance of the battery is improved.
4) And setting a specific first preset voltage according to the concentration of the fluoroethylene carbonate, so as to be beneficial to the film forming reaction of the fluoroethylene carbonate.
Detailed Description
The present invention will be described in more detail below with reference to specific examples, but the scope of the present invention is not limited to these examples. The first active material of the cathode is LiMn1.98Mg0.02O4And the second active material is LiNi0.2Co0.4Mn0.4O2. In the cathode slurry, the mass ratio of active substances: adhesive: the conductive agent is 100:4.2:4, the cathode solvent is NMP, the conductive agent is conductive carbon black, and the binder is PVDF. The anode active material is a graphite material, the average particle size D50 of the graphite material is 1.8 microns, and in the anode slurry, the mass ratio of active materials: adhesive: the conductive agent is 100:4.5:4, the anode solvent is deionized water, the conductive agent is conductive carbon black, and the binder is SBR.
Example 1
1) Providing a first active material and a second active material, wherein the average particle size of the first active material is D50 ═ 1.4 micrometers, and the average particle size of the second active material is D50 ═ 2.0 micrometers;
2) in a stirred tankAdding an organic solvent, adding a binder into the solvent to obtain a glue solution, adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 0.85-0.58 ═ 1.4/2.02＝56.6:100；
3) Coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein a counter electrode is a lithium sheet, an organic solvent of the pretreatment electrolyte is ethylene carbonate, an electrolyte salt is 1M lithium hexafluorophosphate, an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, 1-ethyl-2-piperidone in the pretreatment electrolyte accounts for 3.2 volume percent, and 1, 3-propane sultone accounts for 6.6 volume percent;
7) performing charge-discharge cycle at 0.02-0.25V for 3 times at 0.2C, adjusting voltage to 0.22V, taking out the anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, an additive in the electrolyte is fluoroethylene carbonate, and the volume content of the fluoroethylene carbonate is 2.5% by volume;
10) charging to a first predetermined voltage of 3.46-2.6 x 0.025 x 3.40(V) and then charging at a first predetermined voltage at a constant voltage until the charging current is below 0.01C;
11) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Example 2
1) Providing a first active material having an average particle size of D50 ═ 1.5 micrometers and a second active material having an average particle size of D50 ═ 2.2 micrometers;
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 0.85-0.58 ═ 1.5/2.2)2＝58:100；
3) Coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein a counter electrode is a lithium sheet, an organic solvent of the pretreatment electrolyte is ethylene carbonate, an electrolyte salt is 1M lithium hexafluorophosphate, an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, 1-ethyl-2-piperidone in the pretreatment electrolyte accounts for 3.5 volume percent, and 1, 3-propane sultone accounts for 6.4 volume percent;
7) performing charge-discharge cycle at 0.02-0.25V for 3 times at 0.2C, adjusting voltage to 0.25V, taking out the anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, an additive in the electrolyte is fluoroethylene carbonate, and the volume content of the fluoroethylene carbonate is 2.7% by volume;
10) charging to a first predetermined voltage of 3.46-2.6 x 0.027-3.39 (V), and then charging at a first predetermined voltage at a constant voltage until the charging current is below 0.01C;
11) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Example 3
1) Providing a first active material and a second active material, wherein the first active material has an average particle size of D50 ═ 1.4 micrometers and the second active material has an average particle size of D50 ═ 2.1 micrometers;
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 0.85-0.58 ═ 1.4/2.12＝59.2:100；
3) Coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein a counter electrode is a lithium sheet, an organic solvent of the pretreatment electrolyte is ethylene carbonate, an electrolyte salt is 1M lithium hexafluorophosphate, an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, 1-ethyl-2-piperidone in the pretreatment electrolyte accounts for 3.4 volume percent, and 1, 3-propane sultone accounts for 6.5 volume percent;
7) performing charge-discharge cycle at 0.02-0.25V for 3 times at 0.2C, adjusting voltage to 0.24V, taking out the anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, an additive in the electrolyte is fluoroethylene carbonate, and the volume content of the fluoroethylene carbonate is 2.6% by volume;
10) charging to a first predetermined voltage of 3.46-2.6 x 0.026 x 3.39(V), and then charging at a first predetermined voltage at a constant voltage until the charging current is less than 0.01C;
11) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Comparative example 1
1) Providing a first active material and a second active material, wherein the first active material has an average particle size of D50 ═ 1.4 micrometers and the second active material has an average particle size of D50 ═ 2.1 micrometers;
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 59.2: 100;
3) coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) the anode and the cathode are assembled into a lithium ion battery;
7) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, an additive in the electrolyte is fluoroethylene carbonate, and the volume content of the fluoroethylene carbonate is 2.6% by volume;
8) charging to a first predetermined voltage of 3.39(V) and then constant voltage charging at the first predetermined voltage until the charging current is below 0.01C;
9) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Comparative example 2
1) Providing a first active material and a second active material, wherein the first active material has an average particle size of D50 ═ 1.4 micrometers and the second active material has an average particle size of D50 ═ 2.1 micrometers;
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 50: 100;
3) coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein a counter electrode is a lithium sheet, an organic solvent of the pretreatment electrolyte is ethylene carbonate, an electrolyte salt is 1M lithium hexafluorophosphate, an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, 1-ethyl-2-piperidone in the pretreatment electrolyte accounts for 3.4 volume percent, and 1, 3-propane sultone accounts for 6.5 volume percent;
7) performing charge-discharge cycle at 0.02-0.25V for 3 times at 0.2C, adjusting voltage to 0.24V, taking out the anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, an additive in the electrolyte is fluoroethylene carbonate, and the volume content of the fluoroethylene carbonate is 2.6% by volume;
10) charging to a first predetermined voltage of 3.39(V) and then constant voltage charging at the first predetermined voltage until the charging current is below 0.01C;
11) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Comparative example 3
1) Providing a first active material and a second active material, wherein the first active material has an average particle size of D50 ═ 1.4 micrometers and the second active material has an average particle size of D50 ═ 2.1 micrometers;
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 59.2: 100;
3) coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein the counter electrode is a lithium sheet, the organic solvent of the pretreatment electrolyte is ethylene carbonate, the electrolyte salt is 1M lithium hexafluorophosphate, the additive in the pretreatment electrolyte is 1-ethyl-2-piperidone, and the volume of the 1-ethyl-2-piperidone in the pretreatment electrolyte is 3.4%;
7) performing charge-discharge cycle at 0.02-0.25V for 3 times at 0.2C, adjusting voltage to 0.24V, taking out the anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, an additive in the electrolyte is fluoroethylene carbonate, and the volume content of the fluoroethylene carbonate is 2.6% by volume;
10) charging to a first predetermined voltage of 3.39(V) and then constant voltage charging at the first predetermined voltage until the charging current is below 0.01C;
11) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Comparative example 4
1) Providing a first active material and a second active material, wherein the first active material has an average particle size of D50 ═ 1.4 micrometers and the second active material has an average particle size of D50 ═ 2.1 micrometers;
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 59.2: 100;
3) coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein a counter electrode is a lithium sheet, an organic solvent of the pretreatment electrolyte is ethylene carbonate, an electrolyte salt is 1M lithium hexafluorophosphate, an additive in the pretreatment electrolyte is 1, 3-propane sultone, and the 1, 3-propane sultone in the pretreatment electrolyte is 6.5% by volume;
7) performing charge-discharge cycle at 0.02-0.25V for 3 times at 0.2C, adjusting voltage to 0.24V, taking out the anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, an additive in the electrolyte is fluoroethylene carbonate, and the volume content of the fluoroethylene carbonate is 2.6% by volume;
10) charging to a first predetermined voltage of 3.39(V) and then constant voltage charging at the first predetermined voltage until the charging current is below 0.01C;
11) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Comparative example 5
1) Providing a first active material and a second active material, wherein the first active material has an average particle size of D50 ═ 1.4 micrometers and the second active material has an average particle size of D50 ═ 2.1 micrometers;
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 59.2: 100;
3) coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) assembling an anode and the cathode into a lithium ion battery;
7) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, additives in the electrolyte comprise 3.4% of 1-ethyl-2-piperidone, 6.5% of 1, 3-propane sulfonic acid lactone and 2.6% of fluoroethylene carbonate by volume;
8) charging to a first predetermined voltage of 3.39(V) and then constant voltage charging at the first predetermined voltage until the charging current is below 0.01C;
9) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Comparative example 6
1) Providing a first active material and a second active material, wherein the first active material has an average particle size of D50 ═ 1.4 micrometers and the second active material has an average particle size of D50 ═ 2.1 micrometers;
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 59.2: 100;
3) coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein a counter electrode is a lithium sheet, an organic solvent of the pretreatment electrolyte is ethylene carbonate, an electrolyte salt is 1M lithium hexafluorophosphate, an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, 1-ethyl-2-piperidone in the pretreatment electrolyte accounts for 3.4 volume percent, and 1, 3-propane sultone accounts for 6.5 volume percent;
7) performing charge-discharge cycle at 0.02-0.25V for 3 times at 0.2C, adjusting voltage to 0.24V, taking out the anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, an additive in the electrolyte is fluoroethylene carbonate, and the volume content of the fluoroethylene carbonate is 2.6% by volume;
10) charging to a first predetermined voltage of 3.30(V), and then charging at a constant voltage until the charging current is lower than 0.01C;
11) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Comparative example 7
1) Providing a first active material and a second active material, wherein the first active material has an average particle size of D50 ═ 1.4 micrometers and the second active material has an average particle size of D50 ═ 2.1 micrometers;
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 59.2: 100;
3) coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein a counter electrode is a lithium sheet, an organic solvent of the pretreatment electrolyte is ethylene carbonate, an electrolyte salt is 1M lithium hexafluorophosphate, an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, 1-ethyl-2-piperidone in the pretreatment electrolyte accounts for 3.4 volume percent, and 1, 3-propane sultone accounts for 6.5 volume percent;
7) performing charge-discharge cycle at 0.02-0.25V for 3 times at 0.2C, adjusting voltage to 0.24V, taking out the anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, an additive in the electrolyte is fluoroethylene carbonate, and the volume content of the fluoroethylene carbonate is 2.6% by volume;
10) charging to a first predetermined voltage of 3.50(V), and then charging at a constant voltage until the charging current is lower than 0.01C;
11) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Comparative example 8
1) Providing a first active material and a second active material, wherein the first active material has an average particle size of D50 ═ 1.4 micrometers and the second active material has an average particle size of D50 ═ 2.1 micrometers;
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 59.2: 100;
3) coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein a counter electrode is a lithium sheet, an organic solvent of the pretreatment electrolyte is ethylene carbonate, an electrolyte salt is 1M lithium hexafluorophosphate, an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, 1-ethyl-2-piperidone in the pretreatment electrolyte accounts for 4.5 volume percent, and 1, 3-propane sultone accounts for 6.4 volume percent;
7) performing charge-discharge cycle at 0.02-0.25V for 3 times at 0.2C, adjusting voltage to 0.24V, taking out the anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting an electrolyte, wherein dimethyl carbonate accounts for 70% of the total volume of the electrolyte, ethylene carbonate accounts for 30%, electrolyte salt is 1M lithium hexafluorophosphate, an additive in the electrolyte is fluoroethylene carbonate, and the volume content of the fluoroethylene carbonate is 2.6% by volume;
10) charging to a first predetermined voltage of 3.39(V) and then constant voltage charging at the first predetermined voltage until the charging current is below 0.01C;
11) and (3) carrying out charge-discharge circulation at 0.2 ℃ between 4.25V and 2.85V for 3 times to obtain the lithium ion battery.
Test and results
The batteries of examples 1 to 3 and comparative examples 1 to 8 were tested, and the cycle capacity retention ratio of the batteries was measured by performing charge and discharge cycles 200 times at-5 ℃ using a current of 2C in a voltage interval of 4.25V and 2.85V, and the results are shown in Table 1. As can be seen from table 1, the mixing of the first active material and the second active material in a specific mass ratio can improve the cycle stability of the material. The pretreatment electrolyte contains 1-ethyl-2-piperidone and 1, 3-propane sultone, which can improve the circulation stability under high rate, but when the 1-ethyl-2-piperidone and the 1, 3-propane sultone are in the electrolyte, the low-temperature performance of the battery is negatively influenced; the specific first preset voltage is set according to the concentration of the fluoroethylene carbonate, so that the film forming reaction of the fluoroethylene carbonate is facilitated, and the cycle performance is improved.
TABLE 1
Figure BDA0002773321800000111
Figure BDA0002773321800000121
While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention.

Claims (7)

1. A method of making a lithium ion battery, the method comprising:
1) providing a first active material and a second active material, wherein the average particle size of the first active material is D50, and the average particle size of the second active material is D50';
2) adding an organic solvent into a stirring kettle, adding a binder into the solvent for dispersion to obtain a glue solution, then adding part of the second active substance, uniformly stirring, adding the first active substance, uniformly stirring, adding the rest second active substance, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain cathode slurry; wherein the mass ratio of the first active material to the second active material in the slurry satisfies the following relational expression: first/second active 0.85-k ═ D50/D50')2Wherein k is 0.58;
3) coating the cathode slurry on the surface of a current collector, drying and hot-pressing to obtain a cathode;
4) providing a graphite material, adding deionized water into a stirring kettle, adding a binder into a solvent for dispersion to obtain a glue solution, then adding graphite, uniformly stirring, adding a conductive agent, and uniformly stirring to obtain anode slurry;
5) coating the anode slurry on the surface of a current collector, drying and hot-pressing to obtain an anode;
6) placing the anode in a pretreatment electrolyte, wherein an additive in the pretreatment electrolyte consists of 1-ethyl-2-piperidone and 1, 3-propane sultone, and a counter electrode is a lithium sheet;
7) performing charge-discharge cycle between 0.02-0.25V, adjusting voltage to 0.22-0.25V, taking out anode, and drying;
8) assembling the anode obtained in the step 7 and the cathode into a lithium ion battery;
9) injecting electrolyte, wherein an additive in the electrolyte is fluoroethylene carbonate;
10) charging to a first preset voltage, and then charging at a constant voltage of the first preset voltage until the charging current is lower than the charging cut-off current;
11) and carrying out charge-discharge circulation for a plurality of times between the charge cut-off voltage and the discharge cut-off voltage to obtain the lithium ion battery.
2. The method of the preceding claim, wherein the first active material is spinel lithium manganate having an average particle size D50 of 1.4 to 1.5 microns; the second active material is a ternary material having an average particle size D50' of 2.0-2.2 microns.
3. The method of the preceding claim, wherein, in the cathode slurry, the mass ratio of active material: adhesive: the conductive agent is 100:4.2: 4.
4. The method as claimed in the preceding claim, wherein the graphite material has an average particle size D50 of 1.8-1.9 μm, and the anode slurry contains, in mass ratio, active material: adhesive: the conductive agent is 100:4.5: 4.
5. The method of claim, wherein the preconditioning electrolyte comprises 3.2 to 3.5 volume percent 1-ethyl-2-piperidone and 6.4 to 6.6 volume percent 1, 3-propanesultone, and wherein the total content of 1-ethyl-2-piperidone and 1, 3-propanesultone is less than 10 volume percent.
6. The method of the preceding claim, wherein the linear dimethyl carbonate is present in an amount of greater than 70% by volume of the total electrolyte volume and the fluoroethylene carbonate is present in an amount of 2.5 to 2.7% by volume.
7. The method of the preceding claim, wherein the first predetermined voltage is 3.46-m volume content (V) of fluoroethylene carbonate, wherein m is 2.6.
CN202011256623.7A 2020-11-11 2020-11-11 Preparation method of lithium ion battery Withdrawn CN112349968A (en)

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