CN113285122A - Formation method of power lithium ion battery - Google Patents

Formation method of power lithium ion battery Download PDF

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Publication number
CN113285122A
CN113285122A CN202110523830.2A CN202110523830A CN113285122A CN 113285122 A CN113285122 A CN 113285122A CN 202110523830 A CN202110523830 A CN 202110523830A CN 113285122 A CN113285122 A CN 113285122A
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electrolyte
voltage
battery
charging
current
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袁永华
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Suzhou Fanjie Electric Appliance Technology Co ltd
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Suzhou Fanjie Electric Appliance 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
    • H01M10/058—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
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • 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

Abstract

The invention provides a formation method of a power lithium ion battery, which comprises the following steps: providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, injecting a first electrolyte, vacuumizing, exhausting, standing, and enabling the electrolyte to infiltrate into an electrode; charging the battery at constant current to a first preset voltage, and charging the battery at constant voltage by the first preset voltage until the charging current is lower than the cut-off current; injecting a second electrolyte, vacuumizing, exhausting, standing, and performing charge-discharge cycle between a first preset voltage and a discharge cut-off voltage for several times; and then charging the battery at a constant current of a predetermined current to a second predetermined voltage and at a constant voltage of the second predetermined voltage until the charging current is lower than the cutoff current. The battery obtained by the formation method provided by the invention has the advantages that the cycle life of the battery is long, the working temperature value of the battery is close to that of the battery, the consistency of the electrochemical performance and the heating condition among the single batteries is higher after the battery pack is formed, and the unified management of the battery pack is facilitated.

Description

Formation method of power lithium ion battery
Technical Field
The invention relates to a formation method of a power lithium ion battery.
Background
The power lithium ion battery has the advantages of high multiplying power, high power density, low memory effect, environmental protection and the like. And the active material is LiNi0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2The cathode obtained by mixing the materials according to a specific mass ratio has excellent rate performance and cycle performance, but the material has higher reactivity of an electrode active material to carbonic ester in electrolyte under a high-temperature environment, so that the decomposition phenomenon of the electrolyte of the battery is obvious and the service life performance of the battery is influenced when the material is exposed to the high-temperature environment for a long time.
Disclosure of Invention
The invention provides a formation method of a power lithium ion battery, which comprises the following steps: providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, injecting a first electrolyte, vacuumizing, exhausting, standing, and enabling the electrolyte to infiltrate into an electrode; charging the battery at constant current to a first preset voltage, and charging the battery at constant voltage by the first preset voltage until the charging current is lower than the cut-off current; injecting a second electrolyte, vacuumizing, exhausting, standing, and performing charge-discharge cycle between a first preset voltage and a discharge cut-off voltage for several times; and then charging the battery to a second preset voltage at a constant current of a preset current, measuring the temperature of the battery as T1, performing constant voltage charging at a second preset voltage until the charging current is lower than a cut-off current, measuring the temperature of the battery again as T2, injecting a first electrolyte if the temperature of the battery is higher than a preset value T2-T1, otherwise, injecting a second electrolyte, and sealing the opening to obtain the power lithium ion battery. The battery obtained by the formation method provided by the invention has the advantages that the cycle life of the battery is long, the working temperature value of the battery is close to that of the battery, the consistency of the electrochemical performance and the heating condition among the single batteries is higher after the battery pack is formed, and the unified management of the battery pack is facilitated.
The specific scheme is as follows:
a formation method of a power lithium ion battery comprises the following steps:
1) providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a first electrolyte, wherein the first electrolyte accounts for 65-70% of the total volume of the electrolyte; the first electrolyte contains a first additive;
2) vacuumizing, exhausting and standing;
3) charging to a first preset voltage by constant current;
4) charging at a first predetermined voltage at a constant voltage until the charging current is lower than the cutoff current;
5) injecting a second electrolyte, wherein the second electrolyte accounts for 20-25% of the total volume of the electrolyte; the second electrolyte contains a second additive;
6) vacuumizing, exhausting and standing;
7) performing a charge-discharge cycle between a first predetermined voltage and a discharge cutoff voltage for a plurality of times;
8) charging the battery to a second preset voltage at a constant current of a preset current, and recording the measured battery temperature as T1;
9) charging at a second preset voltage with constant voltage until the charging current is lower than the cut-off current, and measuring the temperature of the battery again to be recorded as T2;
10) if T2-T1 is higher than a preset value, injecting a first electrolyte, and if not, injecting a second electrolyte; and sealing to obtain the power lithium ion battery.
Further wherein the first additive is a combination of 1-methyl-2-piperidone and alpha-methylene-gamma-valerolactone in a volume ratio of 1:1.5, wherein in the first electrolyte, the concentration of the 1-methyl-2-piperidone is 1.4-1.6 volume percent and the alpha-methylene-gamma-valerolactone is 2.1-2.4 volume percent.
Further, the first predetermined voltage is a discharge cut-off voltage + r ═ 1-methyl-2-piperidone volume concentration, where r is 35.6 to 36.0, and the discharge cut-off voltage is 2.70V.
Further, the second additive is alpha-methylene-gamma-valerolactone, and the alpha-methylene-gamma-valerolactone is 2.1-2.4 volume percent.
Further, the second predetermined voltage is the first predetermined voltage + V1, where V1 is 0.24-0.26V.
Further, the predetermined value in the step 10 is 0.5 ℃.
Further, the cathode active material of the lithium ion battery is LiNi0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2Wherein LiNi is0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2The mass ratio of (A) to (B) is 35:65-38: 62.
Further, the power lithium ion battery is characterized by being obtained by the method.
The invention has the following beneficial effects:
1) the inventors have found that LiNi is an active material0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2The cathode obtained by mixing the materials according to a specific mass ratio has excellent rate performance and cycle performance, but the material has higher reactivity of the electrode active material to carbonic ester in electrolyte under a high-temperature environment, so that the decomposition phenomenon of the electrolyte of the battery is obvious when the material is exposed to the high-temperature environment for a long time, and the service life performance of the battery is influenced;
2) in view of the above circumstances, the inventors have found through a large number of experiments for a long time that when the additive uses a combination of 1-methyl-2-piperidone and α -methylene- γ -valerolactone, it is more obvious to inhibit decomposition of the electrolyte in a high temperature environment, however, when the ratio of 1-methyl-2-piperidone to alpha-methylene-gamma-valerolactone is relatively large, the internal resistance of the battery is obviously increased, the temperature of the battery is easily abnormally increased under high multiplying power, but when the ratio of 1-methyl-2-piperidone/α -methylene- γ -valerolactone is small, the high temperature stability is lowered, and therefore, the ratio of 1-methyl-2-piperidone/α -methylene- γ -valerolactone needs to be adjusted according to the formation of the battery;
3) aiming at the situation, the invention provides step-by-step liquid injection, wherein first electrolyte with a larger ratio of 1-methyl-2-piperidone/alpha-methylene-gamma-valerolactone is injected, then second electrolyte only containing alpha-methylene-gamma-valerolactone is injected to adjust the ratio of 1-methyl-2-piperidone/alpha-methylene-gamma-valerolactone, and finally fine adjustment is carried out according to the calorific value of the battery;
4) the inventors have found through studies that, when the charge and discharge cycles are performed at or below the first predetermined voltage, the increase in the internal resistance of the battery can be prevented, probably because the decomposition rate of 1-methyl-2-piperidone can be controlled and the formation of the SEI film is relatively slow and smooth at or below the first predetermined voltage;
5) under a second preset voltage higher than the first preset voltage, the ratio of the 1-methyl-2-piperidone/alpha-methylene-gamma-valerolactone in the electrolyte is finely adjusted according to the heating condition of the battery, so that the power lithium ion battery with stable cycle life and consistent internal resistance is obtained.
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 cathode active material of the lithium ion battery used in the present invention is LiNi0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2Wherein LiNi is0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2The mass ratio of (A) to (B) is 36:65-38: 62. The anode active material is artificial graphite; the organic solvent of the electrolyte is a mixture of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 2:1: 1.
Example 1
Cathode active material LiNi of lithium ion battery0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2The mass ratio of (A) to (B) is 36: 65:
1) providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a first electrolyte, wherein the first electrolyte accounts for 65% of the total volume of the electrolyte; the first electrolyte contains a first additive; the first additive is a combination of 1-methyl-2-piperidone and alpha-methylene-gamma-valerolactone in a volume ratio of 1:1.5, wherein in the first electrolyte, the concentration of the 1-methyl-2-piperidone is 1.6 volume percent, and the alpha-methylene-gamma-valerolactone is 2.4 volume percent.
2) Vacuumizing, exhausting and standing for 1 h;
3) charging to a first predetermined voltage at a constant current of 0.1C, the first predetermined voltage being a discharge cutoff voltage +36.0 x 1-methyl-2-piperidone volume concentration of 3.28V, the discharge cutoff voltage being 2.70V;
4) charging at a first preset voltage and constant voltage until the charging current is lower than the cut-off current by 0.01C;
5) injecting a second electrolyte, wherein the second electrolyte accounts for 25% of the total volume of the electrolytes; the second electrolyte contains a second additive; the second additive is alpha-methylene-gamma-valerolactone, the alpha-methylene-gamma-valerolactone being 2.1 volume percent;
6) vacuumizing, exhausting and standing for 1 h;
7) performing a charge-discharge cycle at 0.05C between a first predetermined voltage and a discharge cutoff voltage for 4 times;
8) constant current charging to a second predetermined voltage of 3.52V at 0.05C, first predetermined voltage + V1, where V1 is 0.24V; measuring the battery temperature as T1;
9) charging at a second preset voltage until the charging current is lower than the cut-off current by 0.02C, and measuring the temperature of the battery again to be recorded as T2;
10) if T2-T1 is higher than 0.5 ℃, injecting a first electrolyte, and if not, injecting a second electrolyte; and sealing to obtain the power lithium ion battery.
Example 2
Cathode active material LiNi of lithium ion battery0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2Is 38: 62:
1) providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a first electrolyte, wherein the first electrolyte accounts for 70% of the total volume of the electrolyte; the first electrolyte contains a first additive; the first additive is a combination of 1-methyl-2-piperidone and alpha-methylene-gamma-valerolactone in a volume ratio of 1:1.5, wherein in the first electrolyte, the concentration of the 1-methyl-2-piperidone is 1.4 volume percent, and the alpha-methylene-gamma-valerolactone is 2.1 volume percent.
2) Vacuumizing, exhausting and standing for 1 h;
3) charging to a first predetermined voltage with a constant current of 0.1C, the first predetermined voltage being a discharge cutoff voltage + 3.20V for a volume concentration of 35.6 × 1-methyl-2-piperidone, the discharge cutoff voltage being 2.70V;
4) charging at a first preset voltage and constant voltage until the charging current is lower than the cut-off current by 0.01C;
5) injecting a second electrolyte, wherein the second electrolyte accounts for 20% of the total volume of the electrolytes; the second electrolyte contains a second additive; the second additive is alpha-methylene-gamma-valerolactone, the alpha-methylene-gamma-valerolactone being 2.4 volume percent;
6) vacuumizing, exhausting and standing for 1 h;
7) performing a charge-discharge cycle at 0.05C between a first predetermined voltage and a discharge cutoff voltage for 4 times;
8) constant current charging to a second predetermined voltage of 3.46V at 0.05C, first predetermined voltage + V1, where V1 is 0.26V; measuring the battery temperature as T1;
9) charging at a second preset voltage until the charging current is lower than the cut-off current by 0.02C, and measuring the temperature of the battery again to be recorded as T2;
10) if T2-T1 is higher than 0.5 ℃, injecting a first electrolyte, and if not, injecting a second electrolyte; and sealing to obtain the power lithium ion battery.
Example 3
Cathode active material LiNi of lithium ion battery0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2The mass ratio of (1) to (4) is 37: 63:
1) providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a first electrolyte, wherein the first electrolyte accounts for 68 of the total volume of the electrolyte; the first electrolyte contains a first additive; the first additive is a combination of 1-methyl-2-piperidone and alpha-methylene-gamma-valerolactone in a volume ratio of 1:1.5, wherein in the first electrolyte, the concentration of the 1-methyl-2-piperidone is 1.5 volume percent, and the alpha-methylene-gamma-valerolactone is 2.25 volume percent.
2) Vacuumizing, exhausting and standing for 1 h;
3) charging to a first predetermined voltage with a constant current of 0.1C, the first predetermined voltage being a discharge cutoff voltage + 3.24V for a volume concentration of 35.8 × 1-methyl-2-piperidone, the discharge cutoff voltage being 2.70V;
4) charging at a first preset voltage and constant voltage until the charging current is lower than the cut-off current by 0.01C;
5) injecting a second electrolyte, wherein the second electrolyte accounts for 22% of the total volume of the electrolytes; the second electrolyte contains a second additive; the second additive is alpha-methylene-gamma-valerolactone, the alpha-methylene-gamma-valerolactone being 2.2 volume percent;
6) vacuumizing, exhausting and standing for 1 h;
7) performing a charge-discharge cycle at 0.05C between a first predetermined voltage and a discharge cutoff voltage for 4 times;
8) constant current charging to a second predetermined voltage of 3.49V at 0.05C, first predetermined voltage + V1, where V1 is 0.25V; measuring the battery temperature as T1;
9) charging at a second preset voltage until the charging current is lower than the cut-off current by 0.02C, and measuring the temperature of the battery again to be recorded as T2;
10) if T2-T1 is higher than 0.5 ℃, injecting a first electrolyte, and if not, injecting a second electrolyte; and sealing to obtain the power lithium ion battery.
Comparative example 1
1) Providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a first electrolyte, wherein the first electrolyte accounts for 75% of the total volume of the electrolyte; the first electrolyte contains a first additive; the first additive is a combination of 1-methyl-2-piperidone and alpha-methylene-gamma-valerolactone in a volume ratio of 1:1.5, wherein in the first electrolyte, the concentration of the 1-methyl-2-piperidone is 1.6 volume percent, and the alpha-methylene-gamma-valerolactone is 2.4 volume percent.
2) Vacuumizing, exhausting and standing for 1 h;
3) charging to a first predetermined voltage at a constant current of 0.1C, the first predetermined voltage being a discharge cutoff voltage +36.0 x 1-methyl-2-piperidone volume concentration of 3.28V, the discharge cutoff voltage being 2.70V;
4) charging at a first preset voltage and constant voltage until the charging current is lower than the cut-off current by 0.01C;
5) injecting a second electrolyte, wherein the second electrolyte accounts for 25% of the total volume of the electrolytes; the second electrolyte contains a second additive; the second additive is alpha-methylene-gamma-valerolactone, the alpha-methylene-gamma-valerolactone being 2.1 volume percent;
6) vacuumizing, exhausting and standing for 1 h;
7) and carrying out charge-discharge circulation for 4 times at 0.05 ℃ between the first preset voltage and the discharge cut-off voltage, and sealing to obtain the power lithium ion battery.
Comparative example 2
1) Providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a first electrolyte, wherein the first electrolyte accounts for 65% of the total volume of the electrolyte; the first electrolyte contains a first additive; the first additive is a combination of 1-methyl-2-piperidone and alpha-methylene-gamma-valerolactone in a volume ratio of 1:1.5, wherein in the first electrolyte, the concentration of the 1-methyl-2-piperidone is 1.6 volume percent, and the alpha-methylene-gamma-valerolactone is 2.4 volume percent.
2) Vacuumizing, exhausting and standing for 1 h;
3) charging to a first predetermined voltage at a constant current of 0.1C, the first predetermined voltage being a discharge cutoff voltage +36.0 x 1-methyl-2-piperidone volume concentration of 3.28V, the discharge cutoff voltage being 2.70V;
4) charging at a first preset voltage and constant voltage until the charging current is lower than the cut-off current by 0.01C;
5) injecting a second electrolyte, wherein the second electrolyte accounts for 35% of the total volume of the electrolytes; the second electrolyte contains a second additive; the second additive is alpha-methylene-gamma-valerolactone, the alpha-methylene-gamma-valerolactone being 2.1 volume percent;
6) vacuumizing, exhausting and standing for 1 h;
7) performing a charge-discharge cycle at 0.05C between a first predetermined voltage and a discharge cutoff voltage for 4 times; and sealing to obtain the power lithium ion battery.
Comparative example 3
1) Providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a first electrolyte, wherein the first electrolyte accounts for 65% of the total volume of the electrolyte; the first electrolyte contains a first additive; the first additive is a combination of 1-methyl-2-piperidone and alpha-methylene-gamma-valerolactone in a volume ratio of 1:1.5, wherein in the first electrolyte, the concentration of the 1-methyl-2-piperidone is 1.4 vol% and the alpha-methylene-gamma-valerolactone is 2.4 vol%.
2) Vacuumizing, exhausting and standing for 1 h;
3) charging to a first predetermined voltage with a constant current of 0.1C, wherein the first predetermined voltage is 3.28V, and the discharge cutoff voltage is 2.70V;
4) charging at a first preset voltage and constant voltage until the charging current is lower than the cut-off current by 0.01C;
5) injecting a second electrolyte, wherein the second electrolyte accounts for 25% of the total volume of the electrolytes; the second electrolyte contains a second additive; the second additive is alpha-methylene-gamma-valerolactone, the alpha-methylene-gamma-valerolactone being 2.1 volume percent;
6) vacuumizing, exhausting and standing for 1 h;
7) performing a charge-discharge cycle at 0.05C between a first predetermined voltage and a discharge cutoff voltage for 4 times;
8) charging the battery to a second preset voltage with a constant current of 0.05C, wherein the second preset voltage is 3.52V, and the measured battery temperature is recorded as T1;
9) charging at a second preset voltage until the charging current is lower than the cut-off current by 0.02C, and measuring the temperature of the battery again to be recorded as T2;
10) if T2-T1 is higher than 0.5 ℃, injecting a first electrolyte, and if not, injecting a second electrolyte; and sealing to obtain the power lithium ion battery.
Comparative example 4
1) Providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a first electrolyte, wherein the first electrolyte accounts for 65% of the total volume of the electrolyte; the first electrolyte contains a first additive; the first additive is a combination of 1-methyl-2-piperidone and alpha-methylene-gamma-valerolactone in a volume ratio of 1:1.5, wherein in the first electrolyte, the concentration of the 1-methyl-2-piperidone is 1.6 volume percent, and the alpha-methylene-gamma-valerolactone is 2.1 volume percent.
2) Vacuumizing, exhausting and standing for 1 h;
3) charging to a first predetermined voltage at a constant current of 0.1C, the first predetermined voltage being a discharge cutoff voltage +36.0 x 1-methyl-2-piperidone volume concentration of 3.28V, the discharge cutoff voltage being 2.70V;
4) charging at a first preset voltage and constant voltage until the charging current is lower than the cut-off current by 0.01C;
5) injecting a second electrolyte, wherein the second electrolyte accounts for 25% of the total volume of the electrolytes; the second electrolyte contains a second additive; the second additive is alpha-methylene-gamma-valerolactone, the alpha-methylene-gamma-valerolactone being 2.1 volume percent;
6) vacuumizing, exhausting and standing for 1 h;
7) performing a charge-discharge cycle at 0.05C between a first predetermined voltage and a discharge cutoff voltage for 4 times;
8) constant current charging to a second predetermined voltage of 3.52V at 0.05C, first predetermined voltage + V1, where V1 is 0.24V; measuring the battery temperature as T1;
9) charging at a second preset voltage until the charging current is lower than the cut-off current by 0.02C, and measuring the temperature of the battery again to be recorded as T2;
10) if T2-T1 is higher than 0.5 ℃, injecting a first electrolyte, and if not, injecting a second electrolyte; and sealing to obtain the power lithium ion battery.
Comparative example 5
1) Providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a first electrolyte, wherein the first electrolyte contains a first additive; the first additive is a combination of 1-methyl-2-piperidone and alpha-methylene-gamma-valerolactone in a volume ratio of 1:1.5, wherein in the first electrolyte, the concentration of the 1-methyl-2-piperidone is 1.6 volume percent, and the alpha-methylene-gamma-valerolactone is 2.4 volume percent.
2) Vacuumizing, exhausting and standing for 1 h;
3) charging to a first predetermined voltage with a constant current of 0.1C, wherein the first predetermined voltage is 3.28V, and the discharge cutoff voltage is 2.70V;
4) charging at a first preset voltage and constant voltage until the charging current is lower than the cut-off current by 0.01C;
5) vacuumizing, exhausting and standing for 1 h;
6) performing a charge-discharge cycle at 0.05C between a first predetermined voltage and a discharge cutoff voltage for 4 times; and sealing to obtain the power lithium ion battery.
Comparative example 6
1) Providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a second electrolyte, wherein the second electrolyte accounts for 25% of the total volume of the electrolyte; the second electrolyte contains a second additive; the second additive is alpha-methylene-gamma-valerolactone, the alpha-methylene-gamma-valerolactone being 2.1 volume percent;
2) vacuumizing, exhausting and standing for 1 h;
3) charging to a first preset voltage by a constant current of 0.1C, wherein the first preset voltage is 3.28V, and the discharge cutoff voltage is 2.70V;
4) charging at a first preset voltage and constant voltage until the charging current is lower than the cut-off current by 0.01C;
5) vacuumizing, exhausting and standing for 1 h;
6) performing a charge-discharge cycle at 0.05C between a first predetermined voltage and a discharge cutoff voltage for 4 times; and sealing to obtain the power lithium ion battery.
Test and results
100 cells were formed in examples 1 to 3 and comparative examples 1 to 6, respectively, and the formed cells were measured and charged and discharged 400 times at 50 degrees celsius and 1C rate, and the average capacity retention rate of the cells and the difference between the maximum capacity retention rate and the minimum capacity retention rate of the single cells were measured, and the results are shown in table 1.
TABLE 1
Figure BDA0003065059480000091
Figure BDA0003065059480000101
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 (8)

1. A formation method of a power lithium ion battery comprises the following steps:
1) providing an assembled power lithium ion battery, heating the lithium ion battery to be more than 55 ℃, and injecting a first electrolyte, wherein the first electrolyte accounts for 65-70% of the total volume of the electrolyte; the first electrolyte contains a first additive;
2) vacuumizing, exhausting and standing;
3) charging to a first preset voltage by constant current;
4) charging at a first predetermined voltage at a constant voltage until the charging current is lower than the cutoff current;
5) injecting a second electrolyte, wherein the second electrolyte accounts for 20-25% of the total volume of the electrolyte; the second electrolyte contains a second additive;
6) vacuumizing, exhausting and standing;
7) performing a charge-discharge cycle between a first predetermined voltage and a discharge cutoff voltage for a plurality of times;
8) charging the battery to a second preset voltage at a constant current of a preset current, and recording the measured battery temperature as T1;
9) charging at a second preset voltage with constant voltage until the charging current is lower than the cut-off current, and measuring the temperature of the battery again to be recorded as T2;
10) if T2-T1 is higher than a preset value, injecting a first electrolyte, and if not, injecting a second electrolyte; and sealing to obtain the power lithium ion battery.
2. The method of the preceding claim, wherein the first additive is a combination of 1-methyl-2-piperidone and α -methylene- γ -valerolactone in a 1:1.5 volume ratio, wherein in the first electrolyte, the concentration of the 1-methyl-2-piperidone is 1.4 to 1.6 volume percent and the α -methylene- γ -valerolactone is 2.1 to 2.4 volume percent.
3. The method according to the preceding claim, wherein the first predetermined voltage is discharge cut-off + r ═ 1-methyl-2-piperidone volume concentration, where r ═ 35.6 to 36.0, and the discharge cut-off voltage is 2.70V.
4. The method of the preceding claim, wherein the second additive is α -methylene- γ -valerolactone, and the α -methylene- γ -valerolactone is from 2.1 to 2.4% by volume.
5. The method of the preceding claim, wherein the second predetermined voltage is first predetermined voltage + V1, where V1 is 0.24-0.26V.
6. The method of the preceding claim, wherein the predetermined current of step 8 is 0.05C and the predetermined value of step 10 is 0.5 degrees Celsius.
7. The method as set forth in the preceding claim,the cathode active material of the lithium ion battery is LiNi0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2Wherein LiNi is0.55Mn0.42Al0.02Ca0.01O2And LiMn0.68Co0.28Nb0.02Mg0.02O2The mass ratio of (A) to (B) is 35:65-38: 62.
8. A power lithium ion battery, characterized in that it is obtained by the process according to any one of claims 1 to 7.
CN202110523830.2A 2021-05-13 2021-05-13 Formation method of power lithium ion battery Withdrawn CN113285122A (en)

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