CN117285470A - Novel electropolymerizable ionic liquid, polymer, battery pole piece and preparation method thereof - Google Patents

Novel electropolymerizable ionic liquid, polymer, battery pole piece and preparation method thereof Download PDF

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CN117285470A
CN117285470A CN202311233459.1A CN202311233459A CN117285470A CN 117285470 A CN117285470 A CN 117285470A CN 202311233459 A CN202311233459 A CN 202311233459A CN 117285470 A CN117285470 A CN 117285470A
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ionic liquid
battery
pole piece
electrolyte
novel
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付道松
朱利敏
张帆
请求不公布姓名
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Tianmu Lake Institute of Advanced Energy Storage Technologies Co Ltd
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Tianmu Lake Institute of Advanced Energy Storage Technologies Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
    • C07D233/54—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members
    • C07D233/56—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, attached to ring carbon atoms
    • C07D233/60—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, attached to ring carbon atoms with hydrocarbon radicals, substituted by oxygen or sulfur atoms, attached to ring nitrogen atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
    • C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
    • C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D401/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom
    • C07D401/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings
    • C07D401/06—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings linked by a carbon chain containing only aliphatic carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D403/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00
    • C07D403/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing two hetero rings
    • C07D403/06—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing two hetero rings linked by a carbon chain containing only aliphatic carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D409/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms
    • C07D409/02—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms containing two hetero rings
    • C07D409/06—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms containing two hetero rings linked by a carbon chain containing only aliphatic carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G61/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G61/12—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule
    • C08G61/122—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule derived from five- or six-membered heterocyclic compounds, other than imides
    • C08G61/123—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule derived from five- or six-membered heterocyclic compounds, other than imides derived from five-membered heterocyclic compounds
    • C08G61/124—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule derived from five- or six-membered heterocyclic compounds, other than imides derived from five-membered heterocyclic compounds with a five-membered ring containing one nitrogen atom in the ring
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/02—Polyamines
    • C08G73/026—Wholly aromatic polyamines
    • C08G73/0266—Polyanilines or derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/0605—Polycondensates containing five-membered rings, not condensed with other rings, with nitrogen atoms as the only ring hetero atoms
    • C08G73/0611—Polycondensates containing five-membered rings, not condensed with other rings, with nitrogen atoms as the only ring hetero atoms with only one nitrogen atom in the ring, e.g. polypyrroles
    • 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
    • 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
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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

Abstract

The invention discloses a novel electropolymerizable ionic liquid, which has an X-Y structure, wherein X comprises at least one of anilino, pyrrolyl and thienyl, and Y comprises at least one of imidazole and pyridine. The ionic liquid can enable the monomer material to be subjected to electrochemical polymerization on the surface of the positive electrode through an in-situ formation process, and the positive electrode material is subjected to electrochemical in-situ cladding, so that lithium ions can be effectively transmitted, and meanwhile, the stability of the electrolyte is prevented from being influenced by higher oxidation activity of high-voltage active substances, and therefore, the capacity loss of a battery is avoided.

Description

Novel electropolymerizable ionic liquid, polymer, battery pole piece and preparation method thereof
Technical Field
The invention relates to the technical field of batteries, in particular to a novel electropolymerizable ionic liquid, a polymer, a battery pole piece and a preparation method thereof.
Background
The lithium cobaltate, the lithium manganate, the ternary nickel cobalt lithium aluminate and the like have the advantages of long cycle life, high tap density, high volume energy density, stable product performance and good consistency, and are widely applied to current electronic products. Because of higher cost, the research of high-voltage materials is promoted, and the energy density is continuously improved, so that the electricity cost of the battery is reduced.
The theoretical capacity of lithium cobaltate is 274mAh/g, but a voltage of 5V vs Li is required for complete delithiation. At present, the actual charge cut-off voltage of lithium cobaltate reaches 4.45V, and the reversible discharge specific capacity and volume energy density reach 173mAh g -1 And 2900Wh L -1 . When the charge cut-off voltage of lithium cobaltate is increased to 4.6V, the discharge capacity can reach 220mAh g -1 The volume energy density reaches 3700Wh L -1 . When the charging voltage exceeds 4.5V, the adverse phase change of O3 phase to H1-3 phase occurs, the cell parameters change drastically, and larger residual stress is accumulated in the material, resulting in the formation of microcracks. In addition, as the O2 p orbit and the Co 3d orbit are partially overlapped, lattice oxygen can participate in oxidation-reduction reaction under the high-voltage condition to cause oxygen release and other problems, thereby triggering structural degradation of lithium cobaltate.
The prior art often coats active substances with inorganic solid state electrolytes and polymeric materials, which may be complex and require precise control of various parameters such as temperature, humidity, time, etc. to ensure the effectiveness and uniformity of the coating. Second, some impurities or defects may be introduced during the coating process, affecting the properties of the material. Therefore, a strict purification step is required to ensure the purity and quality of the material. In addition, the thickness and uniformity of the coating are also an important factor affecting the material properties. If the coating is not uniform, it may lead to reduced performance or instability of the material.
Therefore, the stability of lattice oxygen of the positive electrode material is improved, unfavorable phase change is inhibited, and the method has important significance for developing positive electrode materials such as 4.6V high-voltage lithium cobalt oxide, lithium manganate, ternary nickel cobalt lithium aluminate and the like.
Disclosure of Invention
Aiming at the problems in the prior art, the invention discloses a novel electropolymerizable ionic liquid, which can enable a monomer material to electrochemically polymerize on the surface of a positive electrode by an in-situ formation process, and can carry out electrochemical in-situ coating on positive electrode materials such as lithium cobaltate, lithium manganate, ternary nickel cobalt lithium aluminate and the like, so that the stability of electrolyte is prevented from being influenced by higher oxidation activity of high-voltage active substances, and the capacity loss of a battery is avoided.
The invention is realized by the following technical scheme:
a novel electropolymerizable ionic liquid for batteries, which has a structure of formula I,
x contains a structure of formula II, which is divided into anilino, pyrrolyl and thienyl,
wherein R is one or more of C1-C10 straight-chain hydrocarbon group, branched-chain hydrocarbon group, ester group, carbonyl group and ether group;
y comprises the structure of the formula III,
wherein m is selected from 1-10, m is an integer; z is Z - One or more selected from halogen ion, phosphate ion, perchlorate ion, sulfonimide ion, oxalic acid borate ion, sulfonate ion and acetate ion;
R of X and N of Y + And (5) connection.
The X designed by the invention has good conductivity, and has ion transmission capacity after the molecular design is adopted to graft the ionic liquid structure Y.
As a further embodiment, X contains thienyl and Y contains imidazolyl. The polar element contained in the thienyl has more lone pair electrons, and can form more lithium ion transmission channels, so that the performance of the battery is improved. When the ionic liquid group is a pyridine group, it contains fewer polar groups and thus fewer lithium ion transport channels than imidazole groups, and thus the performance of the battery is poor.
As a further aspect, when R is a straight-chain hydrocarbon group, R is C2-C6, preferably C3-C5, and most preferably C4. When the length of the side chain becomes longer, the capacity retention rate of the battery tends to increase and then decrease. When the length of the side chain is increased, the free volume of the polymer is increased, so that the peristaltic movement of the polymer chain segment is improved, the transmission of lithium ions is promoted, and the performance of the battery is improved, but when the side chain is further improved, the longer side chain is wound, the steric hindrance is increased, the peristaltic movement of the chain segment becomes difficult, and the transmission of lithium ions is reduced.
In a second aspect, the present invention provides a novel electropolymerized ionic liquid polymer formed by ionic liquid polymerization, the ionic liquid polymer comprising a structure of formula IV,
wherein R is one or more of C1-C10 straight-chain hydrocarbon group, branched-chain hydrocarbon group, ester group, carbonyl group and ether group;
y comprises the structure of the formula III,
wherein m is selected from 1-10, m is an integer; z is Z - One or more selected from halogen ion, phosphate ion, perchlorate ion, sulfonimide ion, oxalic acid borate ion, sulfonate ion and acetate ion.
As a further scheme, the ionic liquid polymer has the structural formula of
Wherein R is one or more of C1-C10 straight-chain hydrocarbon group, branched-chain hydrocarbon group, ester group, carbonyl group and ether group;
the Y structural formula is
Wherein m is selected from 1-10, m is an integer; z is Z - One or more selected from halogen ion, phosphate ion, perchlorate ion, sulfonimide ion, oxalic acid borate ion, sulfonate ion and acetate ion.
As a further alternative, when R is a straight chain hydrocarbon group, R is C2-C6, preferably C3-C5, most preferably C4.
The third aspect of the invention provides a novel in-situ polymerized polyionic liquid coated battery pole piece, wherein the pole piece adopts the ionic liquid to polymerize on the surface of the pole piece and form a polymer coating or the surface of the pole piece is provided with an ionic liquid polymer.
As a further proposal, the thickness of the polymer coating layer is 0.5 nm-3 μm. When the thickness is small, the anode material cannot be uniformly coated, and when the thickness is too large, the anode reaction kinetics is influenced, and the capacity of the battery is reduced. The thickness of the polymer coating layer is preferably 0.3 μm to 1 μm.
As a further aspect, the polymeric cover layer has at least one of the following features:
a. the room temperature ionic conductivity of the polymer coating layer is 1 multiplied by 10 -5 S/cm to 5X 10 -3 S/cm；
b. The electrochemical window of the polymeric cover layer is greater than 4.6V.
The fourth aspect of the present invention provides a method for preparing a battery pole piece, comprising the steps of:
s1, under the dry gas atmosphere, adding an ionic liquid monomer into an electrolyte, uniformly mixing, assembling a battery electrode group, injecting the electrolyte added with the ionic liquid monomer, sealing, and standing for treatment;
s2, performing formation treatment on the battery, and uniformly forming the battery pole piece coated with the polyion liquid on the surface of the pole piece by using the ionic liquid monomer.
As a further scheme, the gas in the S1 can be air or inert gas, and the ionic liquid monomer accounts for 0.05wt% -10wt%, preferably 0.5wt% -1wt% of the total mass of the electrolyte. When the monomer content is low, the polymer cannot completely cover the lithium cobalt oxide particles, and part of the polymer still contacts the electrolyte to cause capacity attenuation; when the content of the monomer is too high, more monomer can remain in the electrolyte, so that the components of the electrolyte are changed, and the stability of the electrolyte is affected.
As a further scheme, the step S2 includes at least one of a constant current charging phase or a constant voltage charging phase. The polymerization degree and compactness of the polymer can be controlled by changing the voltage and time of constant voltage charge and the current density of constant current charge
As a further scheme, the charging current density of the constant current charging stage is 0.1-20 mA/cm 2 Preferably 5 to 10mA/cm 2 . When the current density is high, the polymerization rate of the monomer is high, but the higher polymerization rate causes poorer consistency of the polymer, and the surface of the electrode cannot be uniformly coated; when the current density is smaller, the polymerization degree of the monomer is low, and the formed polymer coating layer is not compact, so that the coating effect is affected.
As a further scheme, the charging voltage in the constant voltage charging stage is any voltage value in a voltage interval formed by a charging voltage lower limit and a charging voltage upper limit, and the charging voltage upper limit is the maximum value allowed by the charging voltage. For example, in a lithium ion battery, lithium metal is used as a reference electrode, when the voltage interval of the constant voltage charging stage is 3.0 to 4.2V, the charging voltage of the constant voltage charging stage is any value from 3.0 to 4.2V, and may be any one of 3.0V, 3.2V, 3.4V, 3.6V, 3.8V, 4.0V, 4.2V, and the like, and the upper limit of the charging voltage is 4.2V; in the potassium ion battery, potassium metal is used as a reference electrode, and when the voltage interval of the constant voltage charging stage is 0.01-3.0V, the upper limit of the charging voltage is 3.0V; in the sodium ion battery, sodium metal is used as a reference electrode, and when the voltage interval of the constant voltage charging stage is 2.0-3.8V, the upper limit of the charging voltage is 3.8V. As a further scheme, the constant voltage charging stage is 80% -95% of the upper limit of the charging voltage. For the lithium ion battery, the upper limit of the charging voltage is 4.2V, and the charging voltage is preferably 3.4-4.0V according to calculation; for the potassium ion battery, the upper limit of the charging voltage is 3.0V, and the charging voltage is preferably 2.4-2.8V according to calculation; the upper limit of the charging voltage of the potassium ion battery is 3.80V, and it is preferably 3.0 to 3.6V as calculated.
As a further scheme, for a lithium ion battery, when the ionic liquid contains anilino, the voltage interval of the constant voltage charging stage is 3.7-3.9V, and when the voltage is lower, the driving force of aniline polymerization is lower, and the SEI film formed on the surface is uneven; when the voltage is too high, the driving force of aniline polymerization is faster, so that the polymerization degree is high, the formed SEI film is not compact, and the performance of the battery is affected. When the ionic liquid contains a pyrrole group, the voltage interval of the constant voltage charging stage is 3.8-4.0V. When the ionic liquid contains thienyl, the voltage interval of the constant voltage charging stage is 3.6-3.9V.
A fifth aspect of the present invention is to provide a battery or electrochemical device having the novel electropolymerizable ionic liquid.
As a further scheme, the battery is a lithium battery, a sodium battery, a potassium battery, a zinc battery or a magnesium battery, etc. The battery comprises a positive electrode, a negative electrode, a diaphragm, the novel electropolymerizable ionic liquid and the like. Wherein the positive electrode material is selected from lithium cobaltate, lithium manganate, ternary nickel cobalt lithium aluminate and the like. The negative electrode contains an alkali metal, an alkaline earth metal, a carbon material containing carbon as a constituent element, a silicon material containing silicon as a constituent element, a tin material containing tin as a constituent element, a carbon-silicon composite material containing carbon and silicon as constituent elements, a lithium-containing transition metal nitride, and the like. The diaphragm is selected from polyethylene, polypropylene, PP/PE/PP diaphragm, ceramic diaphragm, rubberized diaphragm and the like.
As a further aspect, the electrochemical device may be used in end consumer products, including, but not limited to, such as cell phones, notebook computers, pen-input computers, mobile computers, electronic book players, cellular phones, portable fax machines, portable copiers, portable printers.
As a further scheme, the electrochemical device can be used for electric equipment, the electric equipment comprises large-sized electric equipment and small-sized electric equipment, and the small-sized electric equipment comprises terminal consumer products, wearable electronic equipment or movable electronic equipment; the large-scale electric equipment comprises traffic and transportation electric equipment. Traffic and transportation consumers include, but are not limited to, for example, automobiles, motorcycles, mopeds, buses, subways, high-speed rails, airplanes, boats; wearable or removable electronic devices include, but are not limited to, devices such as headphones, video recorders, liquid crystal televisions, hand-held cleaners, portable CD players, mini-compact discs, transceivers, electronic organizers, calculators, memory cards, portable audio recorders, radios, standby power supplies, drones, motors, lighting fixtures, toys, gaming machines, watches, power tools, flashlights, cameras, home-use large storage batteries, and lithium-ion capacitors.
The invention has the characteristics and beneficial effects that:
(1) According to the ionic liquid disclosed by the invention, the monomer material can be subjected to electrochemical polymerization on the surface of the positive electrode through an in-situ formation process, and the positive electrode material is subjected to electrochemical in-situ coating, so that lithium ions can be effectively transmitted, and meanwhile, the influence of higher oxidation activity of high-voltage active substances on the stability of the electrolyte is avoided, so that the capacity loss of a battery is avoided.
(2) The battery pole piece is prepared by adopting an in-situ formation process, and the preparation method is simple and efficient and is beneficial to mass production.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an equation for the preparation of anilino ionic liquids according to examples 1 to 10 of the present invention.
FIG. 2 shows the structural formula of polyaniline-based ionic liquid according to examples 1 to 10 of the present invention.
FIG. 3 is an equation for the preparation of pyrrole-based ionic liquids according to example 11 of the present invention.
FIG. 4 shows the structural formula of polypyrrole-based ionic liquid in example 11 of the present invention.
Fig. 5 is an equation for the preparation of the pyrrole-based ionic liquid of example 12 of the present invention.
FIG. 6 is a structural formula of polypyrrole-based ionic liquid in example 12 of the present invention.
Fig. 7 is an equation for the preparation of the pyrrolyl-based ionic liquid of example 13 of the present invention.
FIG. 8 is a structural formula of polypyrrole-based ionic liquid in example 13 of the present invention.
Fig. 9 is an equation for the preparation of the thienyl ionic liquid of example 14 of the present invention.
FIG. 10 is a structural formula of a polythiophene-based ionic liquid according to example 14 of the present invention.
FIG. 11 is an equation for the preparation of an aniline-pyridyl ionic liquid according to example 15 of the present invention.
FIG. 12 is a structural formula of a polyaniline-pyridyl ionic liquid according to example 15 of the present invention.
Fig. 13 is an equation for the preparation of pyrrole-pyridyl ionic liquids according to example 16 of the present invention.
FIG. 14 is a structural formula of polypyrrole-pyridyl ionic liquid of example 16 of this invention.
FIG. 15 is an equation for the preparation of thiophene-pyridinyl ionic liquids according to example 17 of the present invention.
FIG. 16 is a structural formula of a polythiophene-pyridyl ionic liquid according to example 17 of the present invention.
FIG. 17 is an equation for the preparation of a quaternary amino ionic liquid according to comparative example 2 of the present invention.
FIG. 18 is a structural formula of a polyquaternary amino ionic liquid according to comparative example 2 of the present invention.
FIG. 19 is a nuclear magnetic resonance hydrogen spectrum of an anilino ionic liquid according to examples 1 to 10 of the present invention.
FIG. 20 is a surface topography of an in situ polymerized polyaniline-based ionic liquid (left) and a commercial electrolyte (right) of comparative example 1 formed according to example 3 of the present invention.
Fig. 21 is a graph of capacity retention at 200 turns for example 3 and comparative example 1 of the present invention.
Fig. 22 is a Cyclic Voltammetry (CV) graph of a lithium cobalt oxide-lithium battery prepared in example 3 of the present invention.
Detailed Description
In order to facilitate an understanding of one of the positive electrode tabs of the present invention, a more complete description of the positive electrode tab of the present invention will be provided below, which examples, however, do not limit the scope of the present invention.
Example 1
(1) Preparation of anilino ionic liquid
24g of 2-bromo-3-nitroacetophenone and 10g N-methylimidazole are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 33g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added for 1 hour, 50mL of deionized water is used for three times after stirring, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and the obtained product is filtered after dissolving in absolute ethyl alcohol, and 20g of black liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), anilino ionic liquid was added in an amount of 0.2wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m-thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, a button cell is assembled, a lithium cobaltate-lithium half cell is assembled, and a reference electrode is a lithium sheet (lithium metal). After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 2
(1) Preparation of anilino ionic liquid
24g of 2-bromo-3-nitroacetophenone and 10g N-methylimidazole are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 33g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added for 1 hour, 50mL of deionized water is used for three times after stirring, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and the obtained product is filtered after dissolving in absolute ethyl alcohol, and 20g of black liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), anilino ionic liquid was added in an amount of 0.5wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 3
(1) Preparation of anilino ionic liquid
24g of 2-bromo-3-nitroacetophenone and 10g N-methylimidazole are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 33g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added for 1 hour, 50mL of deionized water is used for three times after stirring, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and the obtained product is filtered after dissolving in absolute ethyl alcohol, and 20g of black liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), anilino ionic liquid was added in an amount of 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 4
(1) Preparation of anilino ionic liquid
24g of 2-bromo-3-nitroacetophenone and 10g N-methylimidazole are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 33g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added for 1 hour, 50mL of deionized water is used for three times after stirring, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and the obtained product is filtered after dissolving in absolute ethyl alcohol, and 20g of black liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), anilino ionic liquid was added in an amount of 1wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 5
(1) Preparation of anilino ionic liquid
24g of 2-bromo-3-nitroacetophenone and 10g N-methylimidazole are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 33g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added for 1 hour, 50mL of deionized water is used for three times after stirring, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and the obtained product is filtered after dissolving in absolute ethyl alcohol, and 20g of black liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), anilino ionic liquid was added in an amount of 2wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 6
(1) Preparation of anilino ionic liquid
24g of 2-bromo-3-nitroacetophenone and 10g N-methylimidazole are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 33g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added for 1 hour, 50mL of deionized water is used for three times after stirring, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and the obtained product is filtered after dissolving in absolute ethyl alcohol, and 20g of black liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), anilino ionic liquid was added in an amount of 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.4V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 7
(1) Preparation of anilino ionic liquid
24g of 2-bromo-3-nitroacetophenone and 10g N-methylimidazole are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 33g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added for 1 hour, 50mL of deionized water is used for three times after stirring, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and the obtained product is filtered after dissolving in absolute ethyl alcohol, and 20g of black liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), anilino ionic liquid was added in an amount of 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.6V constant voltage charging for 24h. At 25 ℃ andconstant current charge and discharge tests were performed at 0.5C rate in the voltage range of 3V-4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 8
(1) Preparation of anilino ionic liquid
24g of 2-bromo-3-nitroacetophenone and 10g N-methylimidazole are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 33g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added for 1 hour, 50mL of deionized water is used for three times after stirring, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and the obtained product is filtered after dissolving in absolute ethyl alcohol, and 20g of black liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), anilino ionic liquid was added in an amount of 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 4.0V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 9
(1) Preparation of anilino ionic liquid
24g of 2-bromo-3-nitroacetophenone and 10g N-methylimidazole are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 33g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added for 1 hour, 50mL of deionized water is used for three times after stirring, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and the obtained product is filtered after dissolving in absolute ethyl alcohol, and 20g of black liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), anilino ionic liquid was added in an amount of 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 4.2V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 10
(1) Preparation of anilino ionic liquid
24g of 2-bromo-3-nitroacetophenone and 10g N-methylimidazole are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 33g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added for 1 hour, 50mL of deionized water is used for three times after stirring, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and the obtained product is filtered after dissolving in absolute ethyl alcohol, and 20g of black liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), anilino ionic liquid was added in an amount of 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: 6.5mA/cm -2 Constant current charging. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 11
(1) Preparation of pyrrolyl ionic liquid
30g of 1- (2-chloroethyl) -pyrrole, 27-g N-ethylimidazole are dissolved in 50g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added to the upper solution, 50g of LiDFOB (lithium difluorooxalato borate) is added for 1 hour, 50mL of deionized water is used for three times after stirring, and 40g of liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), the addition of pyrrole-based ionic liquid was 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 12
(1) Preparation of pyrrolyl ionic liquid
30g of 1- (2-chlorobutyl) -pyrrole, 27-g N-ethylimidazole are dissolved in 50g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added to the upper solution, 50g of LiDFOB (lithium difluorooxalato borate) is added for 1 hour, and after stirring, 50mL of deionized water is used for three times, 42g of liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), the addition of pyrrole-based ionic liquid was 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge test was performed at 25℃and 0.5C magnification at a voltage ranging from 3V to 4.6V, and calculatedCapacity retention of 200 cycles.
Example 13
(1) Preparation of pyrrolyl ionic liquid
30g of 1- (2-chlorohexyl) -pyrrole, 27g N-ethylimidazole are dissolved in 50g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 50g of LiDFOB (lithium difluorooxalato borate) is added for 1 hour, 50mL of deionized water is used for three times after stirring, and 48g of liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), the addition of pyrrole-based ionic liquid was 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 14
(1) Preparation of thienyl ionic liquid
20g of 3- (2-chloroethyl) thiophene and 16g N-ethylimidazole are dissolved in 30g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 30mL of ethyl acetate is used for three times after stirring, 30g of deionized water is added into the upper solution, 30g of LiFeSI (lithium bis-fluorosulfonyl imide) is added into the upper solution, stirring is carried out for 1 hour, 30mL of deionized water is used for three times, and 30g of liquid product is obtained through rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), thienyl ionic liquid was added in an amount of 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, and a lithium sheet is used as a negative electrode 60 mu L of electrolyte was added to assemble a button cell. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 15
(1) Preparation of aniline-pyridyl ionic liquid
24g of 2-bromo-3-nitroacetophenone, 10g of 4-methylpyridine are dissolved in 200g of ethyl acetate solution, heating and stirring are carried out for 24 hours at 70 ℃, 50mL of ethyl acetate is used for three times after stirring is finished, 50g of deionized water is added into the upper solution, 35g of LiTFSI (lithium bis (trifluoromethanesulfonyl) imide) is added into the upper solution, stirring is carried out for 1 hour, 50mL of deionized water is used for three times, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out for 4 hours at 80 ℃, and then filtration is carried out after dissolving with absolute ethyl alcohol, and 19g of black liquid product is obtained through rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), the aniline-pyridinyl ionic liquid addition was 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 16
(1) Preparation of pyrrole-pyridinyl ionic liquids
30g of 1- (2-chloroethyl) -pyrrole and 23g of 4-ethylpyridine are dissolved in 50g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 50g of LiDFOB (lithium difluorooxalato borate) is added for 1 hour, 50mL of deionized water is used for three times after stirring, and 35g of liquid product is obtained by rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), pyrrole-pyridinyl ionic liquid was added in an amount of 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Example 17
(1) Preparation of thiophene-pyridyl ionic liquid
20g of 3- (2-chloroethyl) thiophene and 18g of 4-ethylpyridine are taken and dissolved in 30g of ethyl acetate solution, heating and stirring are carried out at 70 ℃ for 24 hours, 30mL of ethyl acetate is used for three times after stirring is finished, 30g of deionized water is added into the upper solution, 30g of LiFeSI (lithium bis-fluorosulfonyl imide) is added for stirring for 1 hour, 30mL of deionized water is used for three times, and 28g of liquid product is obtained through rotary evaporation.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), thiophene-pyridinyl ionic liquid was added in an amount of 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Comparative example 1
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio of 8:1:1) is used as a positive electrode material, a 25 mu M thick PP diaphragm is used as a negative electrode, a lithium sheet is used as a negative electrode, and an electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), electrolyte60 μl was added and the coin cell was assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Comparative example 2
(1) Preparation of quaternary amino ionic liquid
24g of 2-bromo-3-nitroacetophenone, 10g of N, N-diethylmethylamine are dissolved in 200g of ethyl acetate solution, heated and stirred at 70 ℃ for 24 hours, 50mL of ethyl acetate is used for three times after stirring, 50g of deionized water is added into the upper solution, 35g of LiTFSI (lithium bis (trifluoromethanesulfonyl imide)) is added into the upper solution, stirring is carried out for 1 hour, 50mL of deionized water is used for three times, the obtained product is dissolved in 20g of concentrated hydrochloric acid, 10g of iron powder is added, stirring is carried out at 80 ℃ for 4 hours, and 15g of yellow liquid product is obtained after filtering and rotary evaporation after dissolving by absolute ethyl alcohol.
(2) Arrangement of electrolyte
The basic electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), the quaternary amino ionic liquid was added in an amount of 0.75wt%.
(3) Battery assembly
Lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio 8:1:1) is used as a positive electrode material, a 25 mu m thick PP diaphragm is used as a negative electrode, 60 mu L of electrolyte is added, and the button cell is assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Comparative example 3
Commercial alumina coated lithium cobalt oxide (LiCoO) 2 ) +carbon black (SP) +polyvinylidene fluoride (HSV 900) (mass ratio of 8:1:1) is used as a positive electrode material, a 25 mu M thick PP diaphragm is used as a negative electrode, a lithium sheet is used as a negative electrode, and an electrolyte is 1M LiPF 6 EC: EMC: DMC (1:1:1), electrolyte was added to 60. Mu.L, and the coin cell was assembled. After the battery is assembled and kept stand for 5 hours, the formation process is as follows: and 3.8V constant voltage charging for 24h. Constant current charge and discharge tests were performed at 25℃and 0.5C rate at a voltage ranging from 3V to 4.6V, and the capacity retention rate was calculated for 200 cycles.
Table 1 constant current charge and discharge test data for examples and comparative examples
The thickness of the polymer layer is obtained by shooting the cross section of the pole piece after the polymer coating through scanning electron microscope analysis. The ionic conductivity of the polymer layer is obtained by preparing a polymer film, assembling a stainless steel-stainless steel symmetrical battery, testing the impedance (R) of the battery, and calculating the impedance (R) through the formula sigma=d/(RS), wherein d is the thickness of the polymer, and S is the effective area of the polymer in the middle of the electrode.
Fig. 19 is a nuclear magnetic resonance hydrogen spectrum of the anilino ionic liquid of examples 1 to 10, and it can be seen from the graph that hydrogen at different positions of the ionic liquid corresponds to chemical shift and peak area in the spectrum one by one, which indicates that the anilino ionic liquid of examples 1 to 10 was successfully prepared. Polyaniline has good conductivity, and can effectively transmit lithium ions after the molecular design is grafted with an ionic liquid structure. And the in-situ prepared artificial positive electrode electrolyte interface can protect the positive electrode material from being corroded by electrolyte, so that the service life of the battery is prolonged, and the cycle performance of the battery is improved. From the observation of the surface morphology of the SEI formed in example 3 and comparative example 1 in FIG. 1, the in-situ polyaniline-based artificial positive electrode electrolyte interface was denser, whereas the SEI formed by commercial electrolyte had obvious cracking and cracking phenomena, and could not achieve good coating effect. Further, from the analysis of the results of examples 1 to 5, the coating effect on lithium cobaltate was improved by controlling the content of the anilino monomer, and the capacity retention rate of the battery was increased and then decreased with the increase of the addition amount. With the increase of the addition amount, the thickness of the formed SEI is gradually increased, and the coating effect is better, but when the thickness is too large, the lithium intercalation and deintercalation dynamics of the positive electrode material are influenced, the reactivity of the positive electrode material is influenced, and the cycle performance of the battery is influenced.
From the analysis of the results of examples 3 and 6 to 9, the polymerization of aniline was affected by controlling the constant voltage at the time of formation of the battery, and the capacity retention rate of the battery tended to increase and then decrease with increasing constant voltage. When the voltage is lower, the driving force of aniline polymerization is lower, and the surface of lithium cobaltate forms a uniform SEI film unevenly; when the voltage is too high, the driving force of aniline polymerization is faster, so that the polymerization degree is high, the formed SEI film is not compact, and the performance of the battery is affected. In addition, by controlling the formation process, the polymerization degree and compactness of the polymer can be controlled by changing the voltage and time of the constant voltage charge and the current density of the constant current charge, and from the results of example 3 and example 10, better polymerization degree and cladding effect can be obtained under the proper parameters of the constant voltage charge or the constant current charge, and the charge and discharge performance of the battery can be improved.
The inventor finds that lithium ions form coordination with polar molecules when being transmitted in the polymer through a great deal of research, and the lithium ions are transmitted through the peristalsis of polymer molecule chain segments, so that the chain segment structure of the polymer can influence the transmission rate of the lithium ions, and further the electrochemical performance of the battery is changed. When X contains thienyl, and Y contains imidazolyl, the battery performance is better: from the analysis of the results of examples 3, 11 and 14, when the polar element contained in the main chain has more lone pair electrons, more lithium ion transmission channels can be formed, so that the performance of the battery is improved, and the thiophene group contains more lone pair electrons, so that the capacity retention rate of the battery is higher; from the results of comparative examples 3 and 15, examples 11 and 16, and examples 14 and 17, when the ionic liquid group is a pyridine group, it contains less polar groups and thus fewer lithium ion transport channels, compared to the imidazole group, and thus the battery performance is poor.
Changing the type of the ionic liquid also changes the performance of the battery, and the comparative example 3 and the comparative example 2 have obvious differences in molecular size between the imidazole-based ionic liquid and the conventional quaternary ammonium ionic liquid, and the imidazole-based ionic liquid has five-membered rings and has larger volume, so that the larger the free volume of the polymer after electropolymerization is, the easier the peristalsis of a molecular chain segment is, the faster the lithium ion transmission speed is, and the better the performance of the prepared battery is.
The inventors have also found through extensive research that changing the chain length of the side chain also affects the performance of the battery, and when the length of the side chain increases, the free volume of the polymer increases, thus improving the creep of the polymer chain segment, thereby promoting the transmission of lithium ions and improving the performance of the battery, but when the side chain further increases, longer side chains are entangled, the steric hindrance increases, so that the creep of the chain segment becomes difficult, and the transmission of lithium ions is reduced. From the results of examples 11 to 13, the capacity retention ratio was high for the cells having a side chain length of 2 to 6, and particularly, the side chain length was highest at 4.
In addition, as can be seen from an analysis of a Cyclic Voltammetry (CV) curve of the lithium cobaltate-lithium battery prepared in example 3 in fig. 22, the prepared battery has only an oxidation peak and a reduction peak when lithium cobaltate material is deintercalated at a voltage of 3V to 4.6V, which indicates that the artificial CEI prepared by the in-situ formation process has excellent high-voltage stability, and the artificial CEI prepared by the in-situ method avoids the influence of higher oxidation activity of high-voltage active materials on the stability of the electrolyte, thereby reducing the capacity loss of the battery in combination with the capacity retention data of the example.
Comparative examples and comparative example 3, batteries prepared from lithium cobalt oxide coated by an in-situ formation process have more excellent effects than conventional commercial alumina-coated lithium cobalt oxide.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A novel electropolymerizable ionic liquid for a battery is characterized in that the ionic liquid has a structure of a formula I,
x contains a structure of the formula II,
wherein R is one or more of C1-C10 straight-chain hydrocarbon group, branched-chain hydrocarbon group, ester group, carbonyl group and ether group;
y comprises the structure of the formula III,
wherein m is selected from 1-10, m is an integer; z is Z - One or more selected from halogen ion, phosphate ion, perchlorate ion, sulfonimide ion, oxalic acid borate ion, sulfonate ion and acetate ion;
r of X and N of Y + And (5) connection.
2. The novel electropolymerizable ionic liquid for a battery of claim 1, wherein X contains thienyl, and Y contains imidazolyl;
preferably, when R is a straight chain hydrocarbyl group, R is C2-C6, preferably C3-C5, most preferably C4.
3. A novel electropolymerized ionic liquid polymer characterized in that the ionic liquid polymer comprises a structure of formula IV,
wherein R is one or more of C1-C10 straight-chain hydrocarbon group, branched-chain hydrocarbon group, ester group, carbonyl group and ether group;
y comprises the structure of the formula III,
wherein m is selected from 1-10, m is an integer; z is Z - Selected from halogen ions, phosphate radicalsOne or more of ions, perchlorate ions, sulfonimide ions, oxalato borate ions, sulfonate ions, and acetate ions.
4. A novel electropolymerized ionic liquid polymer according to claim 3 which is of the formula
Wherein R is one or more of C1-C10 straight-chain hydrocarbon group, branched-chain hydrocarbon group, ester group, carbonyl group and ether group;
the Y structural formula is
Wherein m is selected from 1-10, m is an integer; z is Z - Preferably, when R is a straight-chain hydrocarbon group, R is C2-C6, preferably C3-C5, and most preferably C4.
5. A battery pole piece characterized in that the pole piece adopts the ionic liquid according to any one of claims 1-3 to polymerize on the pole piece surface and form a polymer coating or the pole piece surface is provided with the ionic liquid polymer according to claim 4.
6. The novel in situ polymerized polyionic liquid coated battery pole piece of claim 5, wherein the thickness of the polymer coating layer is 0.5 nm-3 μm, preferably 0.3 μm-1 μm;
the polymeric cover layer has at least one of the following characteristics:
a. the room temperature ionic conductivity of the polymer coating layer is 1 multiplied by 10 -5 S/cm to 5X 10 -3 S/cm；
b. The electrochemical window of the polymeric cover layer is greater than 4.6V.
7. The method for preparing the battery pole piece according to claim 5, comprising the following steps:
s1, under the dry gas atmosphere, adding the ionic liquid as a monomer in the electrolyte, uniformly mixing, assembling a battery pole group, injecting the electrolyte added with the ionic liquid monomer, sealing, and standing for treatment;
s2, performing formation treatment on the battery, and uniformly forming the battery pole piece coated with the polyion liquid on the surface of the pole piece by using the ionic liquid monomer.
8. The method for preparing a battery pole piece according to claim 7, wherein the ionic liquid monomer in S1 accounts for 0.05wt% to 10wt%, preferably 0.5wt% to 1wt% of the total mass of the electrolyte.
9. The method of claim 7, wherein the forming in S2 comprises at least one of a constant current charging phase or a constant voltage charging phase;
The charging current density of the constant current charging stage is 0.1-20 mA/cm 2 Preferably 5 to 10mA/cm 2 ；
The charging voltage in the constant voltage charging stage is any voltage value in a voltage interval formed by the lower charging voltage limit and the upper charging voltage limit of the battery, and is preferably 80% -95% of the upper charging voltage limit.
10. A battery or electrochemical device having a novel electropolymerizable ionic liquid according to any of claims 1-2 or a novel electropolymerizable ionic liquid polymer according to any of claims 3-4, a novel in situ polymerized polyionic liquid coated battery pole piece according to any of claims 5-6 or a battery pole piece obtained by the method of preparation according to any of claims 7-9.
CN202311233459.1A 2023-09-22 2023-09-22 Novel electropolymerizable ionic liquid, polymer, battery pole piece and preparation method thereof Pending CN117285470A (en)

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