CN112467216A - Electrolyte and lithium ion battery - Google Patents

Electrolyte and lithium ion battery Download PDF

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CN112467216A
CN112467216A CN202011372988.6A CN202011372988A CN112467216A CN 112467216 A CN112467216 A CN 112467216A CN 202011372988 A CN202011372988 A CN 202011372988A CN 112467216 A CN112467216 A CN 112467216A
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carbonate
formula
electrolyte
compound
compound represented
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汪仕华
余乐
王仁和
李轶
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai Co Ltd
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai 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
    • H01M10/056—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
    • H01M10/052—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
    • H01M10/0569—Liquid materials characterised by the solvents
    • 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
    • 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
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0034—Fluorinated solvents
    • 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
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • H01M2300/004—Three solvents
    • 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
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • H01M2300/0042—Four or more solvents
    • 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

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  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
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Abstract

The application discloses electrolyte and lithium ion battery. Herein, the electrolyte includes a non-aqueous solvent, a lithium salt, a compound represented by formula I, and an additive; the non-aqueous solvent comprises a compound represented by a formula II, a compound represented by a formula III and fluoroethylene carbonate, wherein the mass ratio of the compound represented by the formula II, the fluoroethylene carbonate and the compound represented by the formula III is a: b: c; wherein a is (5-40), b is (5-40), and c is (20-90); and a + b + c is 100. The lithium ion battery containing the electrolyte provided by the invention has the advantages of longer high-temperature cycle life, higher high-temperature storage capacity retention rate, higher high-temperature storage capacity recovery rate and lower high-temperature storage volume expansion.

Description

Electrolyte and lithium ion battery
Technical Field
The embodiment of the invention relates to the field of lithium ion batteries, in particular to electrolyte and a lithium ion battery.
Background
The lithium ion battery has been applied to the 3C digital field in the 90 s of the 20 th century as an energy storage device with high energy density, long cycle life, wide working temperature range and no memory effect. With the large-scale popularization of electric automobiles, higher requirements such as long endurance are put forward on lithium ion batteries. In order to solve the problem of mileage anxiety, more and more positive and negative electrode materials with high specific energy are applied to the lithium ion battery. Among them, the silicon negative electrode is a development direction of the next generation high energy density battery.
However, in the meantime, the application of silicon anodes also requires many problems to be solved. The most important problem is the cycle life, and the SEI film on the surface of the negative electrode is continuously broken and reformed due to the large-degree expansion and contraction of the volume of the silicon negative electrode in the charging and discharging processes, so that the cycle life of the battery is greatly shortened. The inventor finds that at least the following problems exist in the prior art: an effective means for improving the cycle of the silicon negative electrode battery is to use electrolyte containing fluoroethylene carbonate, and the electrolyte can form a stable SEI film on the surface of the silicon negative electrode. However, at high temperatures, phosphorus pentafluoride, a decomposition product of lithium hexafluorophosphate, reacts with fluoroethylene carbonate, deteriorating the high temperature performance of the battery.
Disclosure of Invention
The embodiment of the invention aims to provide an electrolyte, so that a lithium ion battery containing the electrolyte provided by the embodiment of the invention has better chemical stability and better high-temperature performance.
In order to solve the above technical problems, embodiments of the present invention provide an electrolyte including a non-aqueous solvent, a lithium salt, a compound represented by formula I, and an additive;
Figure BDA0002807341520000011
wherein R is1、R2、R3、R4、R5And R6Independently selected from C1-4Alkyl radical, C1-4Alkoxy radical, C6-12Aryl or aryl-substituted C7-13An alkyl group;
the non-aqueous solvent comprises a compound represented by a formula II, a compound represented by a formula III and fluoroethylene carbonate,
Figure BDA0002807341520000021
wherein R isa、Rb、RcAnd RdIndependently selected from hydrogen, C1-6Alkyl, halogen substituted C1-6Alkyl radical, C3-6Cycloalkyl radical, C2-6Alkenyl radical, C3-6Alkynyl, C6-12Aryl or aryl-substituted C7-13An alkyl group; reAnd RfIndependently selected from C1-6Alkyl, halogen substituted C1-6Alkyl radical, C3-6Cycloalkyl radical, C2-6Alkenyl radical, C3-6Alkynyl, C6-12Aryl or aryl-substituted C7-13An alkyl group;
the mass ratio of the compound represented by the formula II, the fluoroethylene carbonate and the compound represented by the formula III is a: b: c; wherein a is (5-40), b is (5-40), and c is (20-90); and a + b + c is 100.
In some preferred embodiments, R1、R2、R3、R4、R5And R6Independently selected from C1-4Alkyl or C1-4An alkoxy group; preferably C1-4An alkyl group; said C1-4Alkyl is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl;
Ra、Rb、Rcand RdIndependently selected from hydrogen, C1-6Alkyl, halogen substituted C1-6An alkyl group; said C1-6Alkyl is methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, isopropyl, sec-butyl, 2-pentyl, 3-pentyl, tert-butyl or tert-pentyl; said halogen substituted C1-6Alkyl is methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, isopropyl, sec-butyl, 2-pentyl substituted by fluorine, chlorine, bromine or iodine3-pentyl, tert-butyl or tert-pentyl; preferably, Ra、Rb、Rc、RdIndependently selected from hydrogen, C1-4Alkyl radical, said C1-4Alkyl is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl; more preferably, Ra、Rb、Rc、RdIndependently selected from hydrogen, methyl, ethyl or n-propyl;
Reand RfIndependently selected from C1-6Alkyl or halogen substituted C1-6An alkyl group; when said R iseAnd RfIndependently is C1-6When alkyl, said C1-6The alkyl group may be methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, isopropyl, sec-butyl, 2-pentyl, 3-pentyl, tert-butyl or tert-pentyl; when said R iseAnd RfIndependently halogen substituted C1-6When the alkyl is substituted, the halogen is fluorine, chlorine, bromine or iodine, and the halogen is substituted C1-6Alkyl is fluoro, chloro, bromo or iodo substituted methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, isopropyl, sec-butyl, 2-pentyl, 3-pentyl, tert-butyl or tert-pentyl; preferably, ReAnd RfIndependently selected from C1-4An alkyl group; said C1-4The alkyl group can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl; more preferably, ReAnd RfIndependently selected from methyl, ethyl or n-propyl.
In some preferred embodiments, the compound of formula I is
Figure BDA0002807341520000022
The compound represented by the formula II is ethylene carbonate or propylene carbonate; the compound represented by the formula III is one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate and ethyl propyl carbonate; preferably, the compound represented by the formula III is one or two of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, propyl methyl carbonate and propyl ethyl carbonate.
When the compound represented by the formula III is dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate or ethyl propyl carbonate, the mass ratio of the compound represented by the formula II, fluoroethylene carbonate and the compound represented by the formula III is a: b: c, wherein a is (5-30), b is (5-30) and c is (40-90); and a + b + c is 100. Preferably, the mass ratio of the compound represented by the formula II, the fluoroethylene carbonate and the compound represented by the formula III is 15:15: 70.
When the compound represented by the formula III is two of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate and ethyl propyl carbonate (hereinafter referred to as the compound of the first formula III and the compound of the second formula III), the mass ratio of the compound represented by the formula II, fluoroethylene carbonate, the compound of the first formula III and the compound of the second formula III is as follows: a, b, c, d; wherein a is (5-30), b is (5-30), c is (10-30), and d is (40-60); and a + b + c + d is 100. Preferably, the mass ratio of the compound represented by the formula II, fluoroethylene carbonate, the first compound of the formula III and the second compound of the formula III is: 15:15:30:40, 15:15:20:50 or 15:15:10: 60.
In some preferred embodiments, the compound of formula I is
Figure BDA0002807341520000031
The compound represented by the formula II is ethylene carbonate; the compound represented by the formula III is dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate or ethyl propyl carbonate; preferably, the compound represented by the formula III is methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate or methyl propyl carbonate; more preferably, the compound represented by the formula III is methyl ethyl carbonate. For example: the nonaqueous solvent described in example 1 is composed of ethylene carbonate, fluoroethylene carbonate, and ethyl methyl carbonate.
In some preferred embodiments, the compound of formula I is
Figure BDA0002807341520000032
The compound represented by the formula II is propylene carbonate; the compound represented by the formula III is dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate or ethyl propyl carbonate, and preferably, the compound represented by the formula III is methyl propyl carbonate. For example: the non-aqueous solvent described in example 12 consisted of propylene carbonate, fluoroethylene carbonate and methylpropyl carbonate.
In some preferred embodiments, the compound of formula I is
Figure BDA0002807341520000033
The compound represented by the formula II is ethylene carbonate or propylene carbonate, and the compound represented by the formula III is two of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate and ethyl propyl carbonate; preferably, the compound represented by the formula II is ethylene carbonate, and the compound represented by the formula III is dimethyl carbonate and diethyl carbonate; for example: the non-aqueous solvent consists of ethylene carbonate, fluoroethylene carbonate, dimethyl carbonate and diethyl carbonate.
In some preferred embodiments, the compound of formula I is
Figure BDA0002807341520000041
The non-aqueous solvent comprises a compound represented by a formula II, a compound represented by a formula III, fluoroethylene carbonate and gamma-butyrolactone; the compound represented by the formula II is ethylene carbonate or propylene carbonate, and preferably ethylene carbonate; the compound represented by the formula III is dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate or ethyl propyl carbonate, and preferably methyl ethyl carbonate, methyl propyl carbonate or ethyl propyl carbonate. For example: ethylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate and γ -butyrolactone as described in examples 14 and 17; ethylene carbonate, fluoroethylene carbonate, methylpropyl carbonate and γ -butyrolactone as described in example 18; and ethylene carbonate as described in example 18,Fluoroethylene carbonate, ethylpropyl carbonate and gamma-butyrolactone.
The mass ratio of the compound represented by the formula II, fluoroethylene carbonate, the compound represented by the formula III and gamma-butyrolactone is as follows: a, b, c, d; wherein a is (10-20), b is (10-20), c is (50-70), and d is (1-10); and a + b + c + d is 100. For example: 15:15:62:8.
The lithium salt may be a conventional lithium salt in the art, and is preferably LiPF6、LiBF4、LiClO4、LiAsO4One or more of LiTFSI and LiFSI.
The amount of the lithium salt can be conventional in the art, and preferably, the lithium salt is 5 to 25 percent by mass in the electrolyte. For example 12.5%.
The compound represented by the formula I can be used in the conventional amount of additives in the electrolyte in the field, and preferably, the mass percentage of the compound in the electrolyte is 1.0-9.0%.
The additive is preferably one or more of Vinylene Carbonate (VC), ethylene carbonate (VEC), vinyl sulfate (DTD), vinylene sulfate, 1, 3-Propane Sultone (PS), propenyl sultone and 1, 4-butane sultone, and is more preferably a mixture of vinylene carbonate and 1, 3-propane sultone. In the mixture of vinylene carbonate and 1, 3-propane sultone, the mass ratio of vinylene carbonate to 1, 3-propane sultone is preferably 1: 0.5-1: 2, for example, 1: 1.
The additive can be used in the conventional amount of the additive in the electrolyte in the field, and the mass percentage of the additive in the electrolyte is preferably 1-4%, for example, 2%.
The embodiment of the invention also provides a lithium ion battery, which comprises a positive electrode, a negative electrode, a diaphragm and the electrolyte.
The positive electrode described in the present invention includes a positive electrode active material. As the positive electrode active material of the lithium battery described in the present invention, a lithium-containing composite oxide may be used. Specific examples of the lithium-containing composite oxide include LiMnO2、LiFeO2、LiMn2O4、Li2FeSiO4、LiNi1/3Co1/3Mn1/3O2、LiNi5CO2Mn3O2、LizNi(1-x-y)CoxMyO2(x, y and z are values satisfying 0.01. ltoreq. x.ltoreq.0.20, 0. ltoreq. y.ltoreq.0.20, and 0.97. ltoreq. z.ltoreq.1.20, M represents at least one element selected from Mn, V, Mg, Mo, Nb and Al), LiFePO4And LizCO(1-x)MxO2(x and z are values satisfying 0. ltoreq. x.ltoreq.0.1 and 0.97. ltoreq. z.ltoreq.1.20, M represents at least one element selected from the group consisting of Mn, Ni, V, Mg, Mo, Nb, and Al).
Since the surface of the electrolyte additive of the present embodiment can be effectively covered, the positive electrode active material may be LizNi(1-x-y)CoxMyO2(x, y and z are values satisfying 0.01. ltoreq. x.ltoreq.0.15, 0. ltoreq. y.ltoreq.0.15, and 0.97. ltoreq. z.ltoreq.1.20, M represents at least one element selected from the group consisting of Mn, Ni, V, Mg, Mo, Nb and Al) or LizNi(1-x-y)CoxMyO2(x and z are values satisfying 0. ltoreq. x.ltoreq.0.1 and 0.97. ltoreq. z.ltoreq.1.20, and M represents at least one element selected from Mn, V, Mg, Mo, Nb, and Al). Especially in the use of e.g. LizNi(1-x-y)CoxMyO2In the case of a positive electrode active material having a high Ni content (where x, y, and z are values satisfying 0.01. ltoreq. x.ltoreq.0.15, 0. ltoreq. y.ltoreq.0.15, and 0.97. ltoreq. z.ltoreq.1.20, and M represents at least one element selected from the group consisting of Mn, Ni, V, Mg, Mo, Nb, and Al), gas generation tends to be easily caused, but even in this case, gas generation can be effectively suppressed by the combination of the above electrolyte components.
It should be understood that the electrolyte described in the present invention is not limited to be used in a lithium ion battery with a silicon negative electrode, but can also be used in an electrolyte for a lithium ion battery with other negative electrodes (such as a graphite negative electrode), which has the beneficial effects of capturing acidic byproducts generated at high temperature and providing the electrolyte with higher electrochemical stability at high temperature. As the negative electrode active material of the lithium battery described in the present invention, a material capable of inserting and extracting lithium is used as the negative electrode active material. Including, but not limited to, carbon materials such as crystalline carbon (natural graphite, artificial graphite, and the like), amorphous carbon, carbon-coated graphite, and resin-coated graphite, and oxide materials such as indium oxide, silicon oxide, tin oxide, lithium titanate, zinc oxide, and lithium oxide. The negative electrode active material may also be lithium metal or a metal material that can form an alloy with lithium. Specific examples of metals that can be alloyed with lithium include Cu, Sn, Si, Co, Mn, Fe, Sb, and Ag. Binary or ternary alloys containing these metals and lithium may also be used as the negative electrode active material. These negative electrode active materials may be used alone, or two or more of them may be used in combination. From the viewpoint of high energy density, a carbon material such as graphite and an Si-based active material such as Si, an Si alloy, and an Si oxide may be combined as the negative electrode active material. From the viewpoint of both cycle characteristics and high energy density, graphite and an Si-based active material may be combined as the negative electrode active material. In the combination, the ratio of the mass of the Si-based active material to the total mass of the carbon material and the Si-based active material may be 0.5% to 95%, 1% to 50%, or 2% to 40%.
The battery separator is not particularly limited, and a single-layer or laminated microporous film, woven fabric, nonwoven fabric, or the like of polyolefin such as polypropylene or polyethylene can be used.
On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.
The positive progress effects of the invention are as follows:
1) the electrolyte provided by the first aspect of the invention has higher conductivity, and is beneficial to lithium ion conduction;
2) the lithium ion battery provided by the second aspect of the invention, which comprises the anode, the cathode, the diaphragm and the electrolyte provided by the first aspect of the invention, has the advantages of longer high-temperature cycle life, higher high-temperature storage capacity retention rate, higher high-temperature storage capacity recovery rate and lower high-temperature storage volume expansion.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the following detailed description of the embodiments of the present invention is provided. However, it will be appreciated by those of ordinary skill in the art that numerous technical details are set forth in order to provide a better understanding of the present application in various embodiments of the present invention. However, the technical solution claimed in the present application can be implemented without these technical details and various changes and modifications based on the following embodiments.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now exemplified.
The inventor discovers through research that the lithium ion battery prepared by the electrolyte containing the compound represented by the formula I has better high-temperature performance and high adaptability with a silicon cathode; the present inventors further studied and found that the compound represented by formula I has different effects of improving the high temperature performance of a lithium ion battery under different solvent systems, and based on this, the present inventors screened combinations of a plurality of solvents, and found that a nonaqueous solvent simultaneously contains the compound represented by formula ii, the compound represented by formula iii, and fluoroethylene carbonate, and that the mass ratio of the compound represented by formula ii, fluoroethylene carbonate, and the compound represented by formula iii is a: b: c, wherein a is (5-40), b is (5-40), c is (20-90), and a + b + c is 100, the prepared lithium ion battery has better high temperature performance. Thus, the present invention has been completed.
The present invention will be described in further detail with reference to the following examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Experimental procedures in the following examples, where no detailed conditions are indicated, are generally carried out according to conventional conditions, or according to conditions recommended by the manufacturer. Unless otherwise indicated, percentages and parts are by weight. The test materials and reagents used in the following examples are commercially available without specific reference.
[ PREPARATION EXAMPLES ]
Preparation of electrolyte
Example 1
Mixing Ethylene Carbonate (EC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) according to a mass ratio of 15:15:70 under an inert gas (nitrogen) atmosphere with the water content of less than 5ppm to prepare 1000mL of a non-aqueous solvent, adding lithium hexafluorophosphate into the prepared non-aqueous solvent, adding vinylene carbonate, 1, 3-propane sultone and a compound shown in a formula I after completely dissolving, and uniformly mixing to obtain the electrolyte. In the obtained electrolyte, the mass percent of the vinylene carbonate in the electrolyte is 1%, the mass percent of the 1, 3-propane sultone in the electrolyte is 1%, the mass percent of the compound shown in the formula I in the electrolyte is 0.5%, and the balance is a non-aqueous solvent.
Figure BDA0002807341520000071
Lithium ion battery preparation
Preparation of Positive plate
A positive electrode active material lithium nickel cobalt manganese oxide LiNi was mixed in a mass ratio of 93:4:30.8Co0.1Mn0.1O2Conductive carbon black Super-P and a binder polyvinylidene fluoride (PVDF), and then dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. And uniformly coating the slurry on two sides of the aluminum foil, drying, rolling and vacuum drying, and welding an aluminum outgoing line by using an ultrasonic welding machine to obtain the positive plate, wherein the thickness of the positive plate is 120-150 mu m.
Preparation of negative plate
The negative electrode active material artificial graphite, the silicon oxide (carbon coating), the conductive carbon black Super-P, the binder Styrene Butadiene Rubber (SBR) and the carboxymethyl cellulose (CMC) are mixed according to the mass ratio of 80:14:1:2.5:2.5, and then dispersed in deionized water to obtain negative electrode slurry. Coating the slurry on two sides of a copper foil, drying, rolling and vacuum drying, and welding a nickel outgoing line by using an ultrasonic welding machine to obtain a negative plate, wherein the thickness of the negative plate is 120-150 mu m.
Preparation of cell
And placing three layers of isolating films with the thickness of 20 mu m between the positive plate and the negative plate, then winding the sandwich structure consisting of the positive plate, the negative plate and the diaphragm, flattening the wound body, then placing the wound body into an aluminum foil packaging bag, and baking for 48h at 85 ℃ in vacuum to obtain the battery cell to be injected with liquid.
Liquid injection formation of battery core
And (3) in a glove box with the dew point controlled below-40 ℃, injecting the prepared electrolyte into the battery cell, carrying out vacuum packaging, and standing for 24 hours. Then the first charge is normalized according to the following steps: charging to 3.05V at 0.02C, 3.75V at 0.05C, 4.05V at 0.2C, and vacuum sealing. Then, the mixture was further charged to 4.2V by a constant current of 0.33C, and after standing at room temperature for 24 hours, the mixture was discharged to 3.0V by a constant current of 0.2C.
Comparative example 1
Preparation of the electrolyte
Mixing Ethylene Carbonate (EC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) according to a mass ratio of 15:15:70 under an inert gas (nitrogen) atmosphere with the water content of less than 5ppm to prepare 1000mL of a non-aqueous solvent, adding lithium hexafluorophosphate into the prepared non-aqueous solvent, adding vinylene carbonate and 1, 3-propane sultone after complete dissolution, and uniformly mixing to obtain the electrolyte. In the obtained electrolyte, the mass percent of the vinylene carbonate in the electrolyte is 1%, the mass percent of the 1, 3-propane sultone in the electrolyte is 1%, and the balance is a non-aqueous solvent.
Preparation of lithium ion battery
The method was substantially the same as the method for preparing the lithium ion battery in example 1, except that the electrolyte used in the cell injection formation step was the electrolyte prepared in comparative example 1.
Other examples and comparative examples, electrolytes and lithium ion batteries were prepared in the same manner as in example 1, except that the additives used were different, as specified in table 1 below:
TABLE 1
Figure BDA0002807341520000081
Figure BDA0002807341520000091
[ test examples ]
Electrolyte Performance testing
The electrolytes prepared in the above examples and comparative examples were measured for conductivity, density, chromaticity, and oxidative decomposition potential using a conductivity meter, and the measurement results are shown in table 2 below.
TABLE 2
Figure BDA0002807341520000092
Figure BDA0002807341520000101
Battery performance testing
High temperature cycle life test
The full-charged battery after capacity grading was placed in a 45 ℃ incubator and discharged to 3.0V at 1C, and the initial discharge capacity was recorded as DC (1). Charging to 4.2V at constant current and constant voltage of 1C, stopping current at 0.05C, standing for 5min, discharging to 3.0V at 1C, and recording discharge capacity DC (2). This is cycled through until dc (n) < 80%. And recording the discharge times N, wherein N is the high-temperature cycle life. The results are given in Table 3 below.
High temperature storage capacity retention and recovery test
The full-state battery after capacity separation was discharged to 3.0V at room temperature at 1C, and the initial discharge capacity was recorded as DC (0). The cell was placed in an incubator at 60 ℃ for N days, the cell was taken out and discharged to 3.0V at room temperature, and the discharge capacity DC (N-1) was recorded, and the storage capacity Retention was 100% DC (N-1)/DC (0). Charging to 4.2V at constant current and constant voltage of 1C, stopping current at 0.05C, standing for 5min, and discharging to 3.0V at 1C. The average discharge capacity DC (N-2) was recorded after 3 cycles, and the storage capacity Recovery was 100% DC (N-2)/DC (0). The results are shown in Table 3.
High temperature storage volume expansion test
After the capacity grading, the fully charged battery is soaked in ultrapure water, and the initial volume V (0) is measured by using the Archimedes principle. The cells were then stored in an incubator at 60 ℃ for N days, the cells were removed and cooled to room temperature and the volume V (N) was measured again. The volume expansion rate is 100% ((V (n) -V (0))/V (0)) and the charge is replenished to the full charge state, stored and measured. And the process is circulated. The results are shown in Table 3.
TABLE 3
Figure BDA0002807341520000111
Figure BDA0002807341520000121
Analysis of the various examples and comparative test data leads to the following conclusions:
1) the compound represented by formula I according to the embodiment of the present invention is added to an electrolytic solution, specifically, the compound is added to the electrolytic solution
Figure BDA0002807341520000122
(examples 1 to 22), compared with the lithium ion battery without the additive (comparative example 1), the prepared lithium ion battery has longer high-temperature cycle life, higher high-temperature storage capacity retention and recovery rate in 30 days, and smaller high-temperature storage volume expansion in 45 days;
2) adding a compound represented by a formula I in an embodiment of the invention into an electrolyte, wherein a non-aqueous solvent simultaneously comprises a compound represented by a formula II, fluoroethylene carbonate and a compound represented by a formula III, and the mass ratio of the compound represented by the formula II to the compound represented by the formula III is a: b: c; wherein a is (5-40), b is (5-40), and c is (20-90); when a + b + c is 100, the prepared lithium ion battery has better high-temperature performance;
3) when adding into the electrolyte
Figure BDA0002807341520000123
When the solvent system is the non-aqueous solvent composition described in example 1, example 7, example 8, example 12, example 14, example 17, example 18, example 19, etc., the lithium ion battery prepared has longer high temperature cycle life, higher high temperature storage capacity retention and recovery rate in 30 days, and smaller high temperature storage volume expansion in 45 days.
It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for carrying out the invention, and that various changes in form and details may be made therein without departing from the spirit and scope of the invention in practice.

Claims (12)

1. An electrolyte, characterized by comprising a nonaqueous solvent, a lithium salt, a compound represented by formula I, and an additive;
Figure FDA0002807341510000011
wherein R is1、R2、R3、R4、R5And R6Independently selected from C1-4Alkyl radical, C1-4Alkoxy radical, C6-12Aryl or aryl-substituted C7-13An alkyl group;
the non-aqueous solvent comprises a compound represented by a formula II, a compound represented by a formula III and fluoroethylene carbonate,
Figure FDA0002807341510000012
wherein R isa、Rb、RcAnd RdIndependently selected from hydrogen, C1-6Alkyl, halogen substituted C1-6Alkyl radical, C3-6Cycloalkyl radical, C2-6Alkenyl radical, C3-6Alkynyl, C6-12Aryl or aryl-substituted C7-13An alkyl group; reAnd RfIndependently selected from C1-6Alkyl, halogen substituted C1-6Alkyl radical, C3-6Cycloalkyl radical, C2-6Alkenyl radical, C3-6Alkynyl, C6-12Aryl or aryl-substituted C7-13An alkyl group;
the mass ratio of the compound represented by the formula II, the fluoroethylene carbonate and the compound represented by the formula III is a: b: c; wherein a is (5-40), b is (5-40), and c is (20-90); and a + b + c is 100.
2. The electrolyte of claim 1, wherein R is1、R2、R3、R4、R5And R6Independently selected from C1-4Alkyl or C1-4An alkoxy group;
and/or, Ra、Rb、RcAnd RdIndependently selected from hydrogen, C1-6Alkyl, halogen substituted C1-6Alkyl radical, ReAnd RfIndependently selected from C1-6Alkyl or halogen substituted C1-6An alkyl group.
3. The electrolyte of claim 2, wherein R is1、R2、R3、R4、R5And R6Independently selected from C1-4Alkyl radical, said C1-4Alkyl is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl;
and/or, Ra、Rb、RcAnd RdIndependently selected from hydrogen, C1-4Alkyl radical, ReAnd RfIndependently selected from C1-4Alkyl radical, said C1-4Alkyl is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl.
4. The electrolyte of claim 3, wherein the compound of formula I is
Figure FDA0002807341510000013
And/or the compound represented by the formula II is ethylene carbonate or propylene carbonate, and the compound represented by the formula III is one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate and ethyl propyl carbonate.
5. The electrolyte of claim 4, wherein the compound of formula II is ethylene carbonate or propylene carbonate, and the compound of formula III is dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, or ethyl propyl carbonate.
6. The electrolyte according to claim 5, wherein the mass ratio of the compound represented by the formula II, the fluoroethylene carbonate and the compound represented by the formula III is a: b: c, wherein a is (5-30), b is (5-30) and c is (40-90); and a + b + c is 100.
7. The electrolyte of claim 4, wherein the compound of formula II is ethylene carbonate or propylene carbonate, and the compound of formula III is two of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, and ethyl propyl carbonate.
8. The electrolyte of claim 7, wherein the compound of formula iii comprises a first compound of formula iii and a second compound of formula iii, and the mass ratio of the compound of formula ii to fluoroethylene carbonate to the first compound of formula iii to the second compound of formula iii is: a, b, c, d; wherein a is (5-30), b is (5-30), c is (10-30), and d is (40-60); and a + b + c + d is 100.
9. The electrolyte of any one of claims 1 to 4, wherein the non-aqueous solvent further comprises γ -butyrolactone.
10. The electrolyte of claim 9, wherein the compound of formula ii is ethylene carbonate or propylene carbonate, and the compound of formula iii is dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, or ethyl propyl carbonate.
11. The electrolyte of claim 10, wherein the compound of formula ii, the fluoroethylene carbonate, the compound of formula iii, and the γ -butyrolactone are present in a mass ratio of: a, b, c, d; wherein a is (10-20), b is (10-20), c is (50-70), and d is (1-10); and a + b + c + d is 100.
12. A lithium ion battery, characterized in that the lithium ion battery comprises a positive electrode, a negative electrode, a separator and the electrolyte according to any one of claims 1 to 11.
CN202011372988.6A 2020-11-30 2020-11-30 Electrolyte and lithium ion battery Pending CN112467216A (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140079987A1 (en) * 2011-05-09 2014-03-20 Shin-Kobe Electric Machinery Co., Ltd. Nonaqueous Electrolyte Solution and Lithium Ion Battery
CN105449278A (en) * 2015-12-25 2016-03-30 中南大学 Siloxane derivative electrolyte for lithium-ion battery and high-voltage lithium-ion battery
CN108336406A (en) * 2018-01-16 2018-07-27 河南师范大学 A kind of lithium ion battery Low ESR high voltage additive and nonaqueous electrolytic solution
CN110416606A (en) * 2019-05-30 2019-11-05 贵州兴锂新能源科技有限公司 A kind of electrolyte for silicon-carbon cathode lithium ion battery
CN111048830A (en) * 2018-10-12 2020-04-21 微宏动力系统（湖州）有限公司 Nonaqueous electrolyte solution and lithium ion secondary battery
CN111653827A (en) * 2020-05-28 2020-09-11 远景动力技术(江苏)有限公司 Electrolyte of lithium ion battery and lithium ion battery

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140079987A1 (en) * 2011-05-09 2014-03-20 Shin-Kobe Electric Machinery Co., Ltd. Nonaqueous Electrolyte Solution and Lithium Ion Battery
CN105449278A (en) * 2015-12-25 2016-03-30 中南大学 Siloxane derivative electrolyte for lithium-ion battery and high-voltage lithium-ion battery
CN108336406A (en) * 2018-01-16 2018-07-27 河南师范大学 A kind of lithium ion battery Low ESR high voltage additive and nonaqueous electrolytic solution
CN111048830A (en) * 2018-10-12 2020-04-21 微宏动力系统（湖州）有限公司 Nonaqueous electrolyte solution and lithium ion secondary battery
CN110416606A (en) * 2019-05-30 2019-11-05 贵州兴锂新能源科技有限公司 A kind of electrolyte for silicon-carbon cathode lithium ion battery
CN111653827A (en) * 2020-05-28 2020-09-11 远景动力技术(江苏)有限公司 Electrolyte of lithium ion battery and lithium ion battery

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