CN109728339B - Electrolyte composition, all-solid electrolyte membrane and preparation method thereof - Google Patents
Electrolyte composition, all-solid electrolyte membrane and preparation method thereof Download PDFInfo
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Abstract
The invention relates to the field of all-solid-state lithium ion batteries, in particular to an electrolyte composition, an all-solid-state electrolyte membrane, a preparation method of the all-solid-state electrolyte membrane, a positive electrode and an all-solid-state lithium ion battery. The composition comprises a polymer, a lithium salt, an inorganic filler and a coupling agent; the content of the polymer is 20-80 wt%, the content of the lithium salt is 10-30 wt%, the content of the inorganic filler is 1-60 wt%, and the content of the coupling agent is 0.1-15 wt%; the polymer is a random copolymer consisting of a structural unit provided by vinylidene fluoride, a structural unit provided by hexafluoropropylene and a structural unit provided by hydroxyalkyl acrylate; the weight average molecular weight of the polymer was 10,000-9,000,000 g/mol. The composition can obtain an all-solid-state electrolyte membrane with higher ionic conductivity and higher strength, and can obtain an all-solid-state lithium ion battery with higher specific capacity.
Description
Technical Field
The invention relates to the field of all-solid-state lithium ion batteries, in particular to an electrolyte composition, an all-solid-state electrolyte membrane, a preparation method of the all-solid-state electrolyte membrane, a positive electrode and an all-solid-state lithium ion battery.
Background
At present, liquid electrolyte is mostly used as a conductive substance in lithium ion batteries on the market, but in the using process, the liquid electrolyte is volatile, flammable and explosive, so that a plurality of safety problems are caused; and lithium dendrites are easy to grow out, so that the application of the metal lithium as a negative electrode in a battery is limited. Therefore, Solid Polymer Electrolytes (SPE) have been proposed to replace liquid electrolytes. The solid polymer electrolyte membrane not only functions as ion conduction, but also prevents contact between the positive and negative electrodes. And because of its strong plasticity, can make into the film of different shapes according to different demands, the pliability is good, can bear the pressure of electrode in the charge-discharge process, and high temperature stability is good, has greatly improved the security of lithium cell.
CN101183727A discloses an all-solid-state electrolyte made of lithiumThe lithium ion secondary battery consists of salt, polyethylene oxide and superfine powder filler, and solves the problems that the conventional lithium ion secondary battery has the potential safety hazard that liquid electrolyte is easy to volatilize and leak, or the gel polymer electrolyte has poor mechanical property and is difficult to form. However, the electrolyte provided by this application has a low ionic conductivity (room temperature ionic conductivity at 10)-6-10-7S/cm order of magnitude), poor mechanical strength, reduced strength at high temperature, application to batteries, influence on the exertion of battery capacity, and poor battery cycle stability.
Disclosure of Invention
The invention aims to provide an electrolyte composition with higher electrolyte ionic conductivity and higher strength, an all-solid electrolyte membrane, a preparation method of the all-solid electrolyte membrane, a positive electrode and an all-solid lithium ion battery.
In order to achieve the above objects, an aspect of the present invention provides an electrolyte composition comprising a polymer, a lithium salt, an inorganic filler, and a coupling agent; based on the total weight of the composition, the content of the polymer is 20-80 wt%, the content of the lithium salt is 10-30 wt%, the content of the inorganic filler is 1-60 wt%, and the content of the coupling agent is 0.1-15 wt%;
the polymer is a random copolymer consisting of a structural unit provided by vinylidene fluoride, a structural unit provided by hexafluoropropylene and a structural unit provided by hydroxyalkyl acrylate; the weight average molecular weight of the polymer was 10,000-9,000,000 g/mol.
A second aspect of the invention provides an all-solid electrolyte membrane containing the above electrolyte composition.
A third aspect of the present invention provides a method for producing an all-solid electrolyte membrane, the method comprising: an electrolyte slurry containing the electrolyte composition is provided and then dried to form a film.
A fourth aspect of the invention provides an all-solid electrolyte membrane produced by the above method.
A fifth aspect of the invention provides a positive electrode comprising: the positive electrode comprises a positive electrode current collector and a positive electrode active material layer attached to the surface of the positive electrode current collector, wherein the positive electrode active material layer contains a positive electrode active material, the electrolyte composition and a conductive agent.
A sixth aspect of the present invention provides a method for producing a positive electrode, the method including: dispersing the positive active material, the electrolyte slurry and the conductive agent in a dispersing agent to prepare positive slurry; coating the positive electrode slurry on a positive electrode current collector and drying to obtain the positive electrode; wherein the electrolyte slurry is as defined above.
The seventh aspect of the invention provides the positive electrode prepared by the preparation method.
An eighth aspect of the present invention provides an all-solid-state lithium ion battery, which includes a positive electrode, a negative electrode, and an all-solid electrolyte membrane interposed between the positive electrode and the negative electrode;
wherein the all-solid electrolyte membrane is an all-solid electrolyte membrane as defined hereinabove;
the positive electrode is the positive electrode as defined above.
The electrolyte composition provided by the invention can obtain an all-solid-state electrolyte membrane with higher ionic conductivity and higher strength, and can obtain an all-solid-state lithium ion battery with higher specific capacity.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
In one aspect, the present invention provides an electrolyte composition comprising a polymer, a lithium salt, an inorganic filler, and a coupling agent; based on the total weight of the composition, the content of the polymer is 20-80 wt%, the content of the lithium salt is 10-30 wt%, the content of the inorganic filler is 1-60 wt%, and the content of the coupling agent is 0.1-15 wt%;
the polymer is a random copolymer consisting of a structural unit provided by vinylidene fluoride, a structural unit provided by hexafluoropropylene and a structural unit provided by hydroxyalkyl acrylate; the weight average molecular weight of the polymer was 10,000-9,000,000 g/mol.
In the invention, the surface of the inorganic filler is modified by the coupling agent, so that the surface of the inorganic filler is provided with active functional groups such as hydroxyl, carboxyl and the like, and the functional groups can interact with active functional groups such as fluorine and hydroxyl in the polymer adopted by the invention, so that the interaction between the polymer and lithium salt is weakened, and thus, lithium ions in the lithium salt and anions have stronger dissociation effect, the lithium salt is easier to dissociate, the dissociation degree of the lithium salt is greatly improved, and the ion conductivity of the electrolyte is improved. Moreover, the interaction between the filler modified by the coupling agent and the polymer adopted by the invention can also reduce the crystallinity and the glass transition temperature of the polymer, so that the lithium ion mobility is higher, and the ionic conductivity is improved; meanwhile, the inorganic filler particles can not fall off in the charging and discharging processes, the stability is enhanced, and the comprehensive electrochemical performance of the product is improved.
According to the present invention, although the electrolyte composition of the present invention is controlled to have the respective components within the above-mentioned ranges, it is possible to obtain an all-solid electrolyte membrane having higher ionic conductivity and higher strength, and to obtain an all-solid lithium ion battery having higher specific capacity, and more to obtain an all-solid electrolyte membrane and an all-solid lithium ion battery having higher performance, preferably, the polymer is contained in an amount of 30 to 70 wt%, the lithium salt is contained in an amount of 10 to 30 wt%, the inorganic filler is contained in an amount of 10 to 55 wt%, and the coupling agent is contained in an amount of 0.2 to 10 wt%, based on the total weight of the composition. More preferably, the polymer is present in an amount of 30 to 60 wt%, the lithium salt is present in an amount of 12 to 25 wt%, the inorganic filler is present in an amount of 12 to 40 wt%, and the coupling agent is present in an amount of 1 to 6 wt%, based on the total weight of the composition.
According to the invention, the polymer matrix used in the invention is a random copolymer having a certain molecular weight and composed of structural units provided by vinylidene fluoride, structural units provided by hexafluoropropylene and structural units provided by hydroxyalkyl acrylate. Wherein the ratio of each structural unit in the polymer can vary within a wide range, preferably the molar ratio of the structural unit provided by vinylidene fluoride, the structural unit provided by hexafluoropropylene and the structural unit provided by hydroxyalkyl acrylate in the polymer is 1: 0.02-2: 0.02 to 1, preferably 1: 0.05-0.9: 0.05 to 0.9, more preferably 1: 0.1-0.5: 0.1-0.5.
According to the invention, the hydroxyalkyl acrylate can be, for example, a hydroxy C1-C8 alkyl acrylate, the unsaturated carbon-carbon double bond of acrylic acid in the hydroxyalkyl acrylate can also be replaced by a C1-C4 alkyl group, and preferably, the hydroxyalkyl acrylate is one or more of hydroxymethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxymethyl acrylate, hydroxyethyl acrylate and hydroxypropyl acrylate.
According to the present invention, the weight average molecular weight of the polymer is 10,000-9,000,000g/mol, and if the weight average molecular weight of the polymer is less than 10,000g/mol, there is a disadvantage that the mechanical strength of the polymer is low; if the weight average molecular weight of the polymer is more than 9,000,000g/mol, there is a disadvantage that the ionic conductivity is low. Preferably, the weight average molecular weight of the polymer is 50,000-5,000,000g/mol, preferably 100,000-1,000,000g/mol, more preferably 300,000-900,000g/mol, still more preferably 400,000-800,000g/mol, for example 500,000-600,000 g/mol. Wherein, preferably, the molecular weight distribution index of the polymer is 2 to 6, preferably 2 to 4.
According to the present invention, the polymer can be prepared by a method conventional in the art, for example, the method for preparing the polymer comprises:
(1) initiating polymerization of vinylidene fluoride, hexafluoropropylene and hydroxyalkyl acrylate in an organic solvent and in the presence of an organolithium initiator, wherein the initiating polymerization is controlled such that the resulting polymer has a molecular weight of 10,000-9,000,000 g/mol;
(2) the initiated polymerization reaction was terminated, and the solvent was removed by condensation with water vapor, followed by drying to obtain the polymer.
According to the present invention, in the preparation method, the organic lithium initiator is preferably used in an amount of 0.1 to 10 mol%, preferably 0.3 to 2 mol%, based on the total molar amount of the vinylidene fluoride, hexafluoropropylene and hydroxyalkyl acrylate; the organolithium initiator may be, for example, one or more of ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, and isobutyllithium.
The organic solvent may be one or more of toluene, ethylbenzene, xylene, n-hexane, n-pentane, cyclohexane, cyclopentane, etc. The amount of the organic solvent used may vary within wide limits, for example such that the total molar concentration of the vinylidene fluoride, hexafluoropropylene and hydroxyalkyl acrylate is from 0.05 to 100mmol/mL, preferably from 0.1 to 10 mmol/mL.
The conditions for initiating the polymerization reaction may include, for example: the temperature is 50-100 deg.C, and the time is 30-200min (preferably 60-120 min). The initiated polymerization reaction may be conducted, for example, in an inert atmosphere, which may be provided, for example, by one or more of nitrogen, helium, neon, argon, and the like.
According to the present invention, preferably, the lithium salt is LiClO4、LiPF6、LiBF4、LiBOB、LiN(SO2CF3)2、LiCF3SO3And LiN (SO)2CF2CF3)2One or more of (a).
According to the invention, preferably, the coupling agent is a silane coupling agent with hydroxyl and/or carboxyl groups, preferably one or more of bis (2-hydroxyethyl) -3-aminopropyl-methoxysilane, N-hydroxymethyl-N-methylamine-propyltrimethoxysilane, hydroxymethyltriethoxysilane, triethoxysilylcarbinol, N- (3-ethoxypropylsilyl) -4-hydroxybutyramide, N- (3-ethoxypropylsilyl) -glucamide and 2, 2-bis (3-ethoxypropylsilyl-methyl) -butanol.
According to the invention, preferably, the inorganic filler is an inorganic nanofiller, preferably SiO2、MgO、CaO、CeO2、ZnO、SnO2、Al2O3、TiO2、ZrO2、SrO、BaO、B2O3、Ga2O3、In2O3、GeO2、Nb2O5、SiC、MgS、CaS、SrS、BaS、B2S3、Al2S3、Ga2S3、In2S3、SiS2、GeS2、SnS2、CeS2、NbS2、Li7La3Zr2O12、SrBi4Ti4O15And BaSO4One or more of (a). The particle size of the inorganic nanofiller is preferably 10-2000 nm.
A second aspect of the invention provides an all-solid electrolyte membrane containing the above electrolyte composition.
As for the all-solid electrolyte membrane of this aspect, as long as the all-solid electrolyte membrane contains the above-described electrolyte composition of the invention, it can be considered to be within this aspect of the invention.
A third aspect of the present invention provides a method for producing an all-solid electrolyte membrane, the method comprising: an electrolyte slurry containing the electrolyte composition is provided and then dried to form a film.
According to the invention, the concentration of the electrolyte paste may vary within a wide range, preferably the concentration of the electrolyte paste is from 0.1 to 50 wt.%, preferably from 5 to 30 wt.%. The solvent employed in the electrolyte slurry may be, for example, one or more of N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), N-dimethylacetamide, carbon tetrachloride, benzene, toluene, and acetonitrile.
According to the present invention, the preparation process of the electrolyte slurry may include, for example: the polymer, lithium salt and solvent are first mixed (e.g., with stirring), then the inorganic filler is introduced (e.g., with ultrasonic dispersion), and finally the coupling agent is introduced (e.g., with stirring).
Wherein the drying film-forming conditions comprise: the temperature is 60-100 ℃ and the time is 5-48 h.
A fourth aspect of the invention provides an all-solid electrolyte membrane produced by the above method.
According to the present invention, the thickness of the all-solid electrolyte membrane may vary within a wide range, and preferably, the thickness of the all-solid electrolyte membrane is 10 to 900 μm.
The electrolyte composition provided by the invention can obtain an all-solid electrolyte membrane with higher ionic conductivity and higher strength. The ionic conductivity may be, for example, 1X 10-5-9×10-3S/cm, and the tensile strength may be, for example, 1 to 15MPa (preferably 5 to 15MPa, more preferably 7 to 12MPa, for example 9 to 10 MPa).
A fifth aspect of the invention provides a positive electrode comprising: the positive electrode comprises a positive electrode current collector and a positive electrode active material layer attached to the surface of the positive electrode current collector, wherein the positive electrode active material layer contains a positive electrode active material, the electrolyte composition and a conductive agent.
According to the present invention, it is preferable that the content of the positive electrode active material is 9 to 99% by weight, the content of the electrolyte composition is 0.5 to 90% by weight, and the content of the conductive agent is 0.5 to 50% by weight, based on the total weight of the positive electrode active material, the electrolyte composition, and the conductive agent. Preferably, the content of the positive electrode active material is 30 to 95 wt%, the content of the electrolyte composition is 1 to 40 wt%, and the content of the conductive agent is 1 to 30 wt%, based on the total weight of the positive electrode active material, the electrolyte composition, and the conductive agent. More preferably, the content of the positive electrode active material is 55 to 90 wt%, the content of the electrolyte composition is 5 to 35 wt%, and the content of the conductive agent is 1 to 20 wt%, based on the total weight of the positive electrode active material, the electrolyte composition, and the conductive agent.
The specific types of the positive active materials are not particularly limited, and the positive active materials are all conventional raw materials and can be selected according to requirements. For example, the positive active material includes, but is not limited to, lithium cobaltate (LiCoO)2) Manganic acidLithium (LiMn)2O4) Lithium manganate, ternary material (lithium transition metal oxide) and lithium iron phosphate (LiFePO)4) One or more of (a).
For example, the conductive agent may be selected from one or more of superconducting carbon, conductive carbon black, conductive graphite, carbon nanotubes, graphene, and carbon nanofibers.
According to the present invention, the positive electrode may be obtained by coating the positive electrode slurry on a positive electrode current collector and drying (for example, drying at 50 to 70 ℃). The positive electrode slurry may be obtained by dispersing a positive electrode active material, an electrolyte composition (or the electrolyte slurry described above), and a conductive agent in a dispersant, and the dispersant may be one or more of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, tetrahydrofuran, chloroform, dichloromethane, and acetonitrile, for example. The amount of the dispersion solvent may vary within a wide range, and preferably, the amount of the dispersion solvent is 10 to 1000 parts by weight, preferably 20 to 800 parts by weight, more preferably 100-500 parts by weight, for example 200-400 parts by weight, relative to 100 parts by weight of the positive electrode active material, the electrolyte composition and the conductive agent.
A sixth aspect of the present invention provides a method for producing a positive electrode, the method including: dispersing the positive active material, the electrolyte slurry and the conductive agent in a dispersing agent to prepare positive slurry; coating the positive electrode slurry on a positive electrode current collector and drying to obtain the positive electrode; wherein the electrolyte slurry is as defined above.
The types and the use amounts of the positive electrode active material, the electrolyte slurry, the conductive agent and the dispersing agent are defined as above, the positive electrode slurry is also described as above, the invention is not repeated herein, and preferably, the content of the positive electrode active material is 9-99 wt%, the content of the electrolyte composition is 0.5-90 wt% and the content of the conductive agent is 0.5-50 wt% in the positive electrode slurry based on the total weight of the positive electrode active material, the electrolyte composition and the conductive agent. Preferably, the content of the positive electrode active material is 30 to 95 wt%, the content of the electrolyte composition is 1 to 40 wt%, and the content of the conductive agent is 1 to 30 wt%, based on the total weight of the positive electrode active material, the electrolyte composition, and the conductive agent. More preferably, the content of the positive electrode active material is 55 to 90 wt%, the content of the electrolyte composition is 5 to 35 wt%, and the content of the conductive agent is 1 to 20 wt%, based on the total weight of the positive electrode active material, the electrolyte composition, and the conductive agent.
Preferably, the dispersant is used in an amount of 10 to 1000 parts by weight, preferably 20 to 800 parts by weight, more preferably 100 to 500 parts by weight, for example 200 to 400 parts by weight, relative to 100 parts by weight of the positive electrode active material, the electrolyte composition and the conductive agent.
The seventh aspect of the invention provides the positive electrode prepared by the preparation method.
An eighth aspect of the present invention provides an all-solid-state lithium ion battery, which includes a positive electrode, a negative electrode, and an all-solid electrolyte membrane interposed between the positive electrode and the negative electrode;
wherein the all-solid electrolyte membrane is an all-solid electrolyte membrane as defined hereinabove;
the positive electrode is the positive electrode as defined above.
According to the present invention, preferably, the all-solid lithium ion battery includes the above-described all-solid electrolyte membrane, and the above-described positive electrode.
The negative electrode of the all-solid-state lithium ion battery may be a negative electrode conventional in the art, and may be, for example, a negative electrode current collector having metal lithium attached to the surface thereof. The negative electrode collector may be, for example, a copper foil, a copper mesh, or the like.
The all-solid-state lithium ion battery can be constructed in a conventional manner in the field, for example, the two sides of the positive electrode are attached with the all-solid-state electrolyte membrane of the invention and are hot-pressed to improve the bonding strength of the all-solid-state electrolyte membrane and the positive electrode, then the positive electrode and the negative electrode are welded with lugs, are superposed and are placed in an aluminum plastic film for sealing, and then the simple all-solid-state lithium ion battery can be obtained.
The all-solid-state lithium ion battery provided by the invention can obtain higher specific capacity, for example, the specific capacity can be 115-150mAh/g, preferably 120-150mAh/g, more preferably 130-150mAh/g, and still more preferably 135-150 mAh/g.
The present invention will be described in detail below by way of examples.
In the following examples, the molecular weight and the molecular weight distribution were measured by gel permeation chromatography (e2695/2489/2414 type) from Waters; monomers such as vinylidene fluoride, hexafluoropropylene and hydroxyalkyl acrylate, solvents such as NMP and DMF, organolithium initiators such as ethyllithium, N-propyllithium, isopropyllithium, N-butyllithium, sec-butyllithium, tert-butyllithium and isobutyllithium, coupling agents such as bis (2-hydroxyethyl) -3-aminopropyl-methoxysilane and N-hydroxymethyl-N-methylamine-propyltrimethoxysilane, SiO2A filler such as MgO or CaO, a positive electrode material such as lithium cobaltate, and a conductive agent such as carbon nanotubes, and the above raw materials are commercially available from Aldrich.
Preparation example 1
0.1mol of vinylidene fluoride, 0.02mol of hexafluoropropylene and 0.01mol of hydroxyethyl acrylate are mixed in 50mL of cyclohexane, and then 0.001mmol of n-butyllithium (supplied from a 1mol/L n-hexane solution of n-butyllithium) is added at 80 ℃ to initiate polymerization for 120 min; after the reaction is terminated, unreacted monomers and solvent are removed through water vapor condensation, and then the mixture is dried to obtain a polymer P1; the weight average molecular weight was 500,000g/mol, and the molecular weight distribution index was 3.
Preparation example 2
0.1mol of vinylidene fluoride, 0.015mol of hexafluoropropylene and 0.02mol of hydroxyethyl methacrylate are mixed in 50mL of cyclohexane, and then 0.001mmol of n-butyllithium (supplied from a 1mol/L n-hexane solution of n-butyllithium) is added at 90 ℃ to initiate polymerization for 100 min; after the reaction is terminated, unreacted monomers and solvent are removed through water vapor condensation, and then the mixture is dried to obtain a polymer P2; the weight average molecular weight was 600,000g/mol, and the molecular weight distribution index was 3.5.
Preparation example 3
The process as described in preparation example 1, except that hexafluoropropylene was used in an amount of 0.002mol and hydroxyethyl acrylate was used in an amount of 0.001 mol; thus obtaining polymer P3; the weight average molecular weight was 100,000g/mol and the molecular weight distribution index was 2.
Preparation example 4
The process as described in preparation example 1, except that hexafluoropropylene was used in an amount of 0.2mol and hydroxyethyl acrylate was used in an amount of 0.1 mol; thus obtaining polymer P4; the weight average molecular weight was 1,000,000g/mol, and the molecular weight distribution index was 3.6.
Preparation of comparative example 1
The process as described in preparation example 1, except that hexafluoropropylene was used in an amount of 0.001mol, and hydroxyethyl acrylate was used in an amount of 0.001 mol; thus obtaining polymer DP 1; the weight average molecular weight was 8,000g/mol, and the molecular weight distribution index was 1.5.
Preparation of comparative example 2
The process as described in preparation example 1, except that hexafluoropropylene was used in an amount of 0.3mol and hydroxyethyl acrylate was used in an amount of 0.2 mol; thus obtaining polymer DP 2; the weight average molecular weight was 9,500,000g/mol, and the molecular weight distribution index was 3.8.
Preparation of comparative example 3
According to the process described in preparation example 1, except that instead of hydroxyethyl acrylate, vinylidene fluoride was used in an amount of 0.1mol and hexafluoropropylene was used in an amount of 0.03 mol; thus obtaining polymer DP 3; the weight average molecular weight was 510,000g/mol, and the molecular weight distribution index was 3.1.
Example 1
This example serves to illustrate the electrolyte composition, the all-solid electrolyte membrane, the positive electrode, and the all-solid lithium ion battery of the invention.
Preparing an all-solid electrolyte membrane:
the components and the dosage are as follows: polymer (b): polymer P1, 50 g; lithium salt: LiN (CF)3SO2)220 g; filling: nano SiO with 100nm granularity227.3 g; coupling agent: hydroxymethyl triethoxysilane, 2.7 g.
Stirring and mixing a polymer and lithium salt in 1000g of N-methylpyrrolidone for 1h, then adding a filler for ultrasonic dispersion for 15min, finally adding a coupling agent, and stirring to obtain electrolyte slurry A1; the slurry was laid in a polytetrafluoroethylene tank and dried by heating at 80 ℃ to form a film, to obtain an all-solid electrolyte film S1 having a thickness of 200 μm.
Preparing a positive plate:
the components and the dosage are as follows: a positive electrode material: LiFePO43 g; electrolyte slurry: electrolyte slurry A1, 0.3g on a dry weight basis; conductive agent: conductive graphite, 0.15 g.
The positive electrode material, the electrolyte slurry and the conductive agent are dispersed in 12g of N-methyl pyrrolidone to obtain positive electrode slurry, then the positive electrode slurry is coated on the two sides of an aluminum foil (the thickness is 20 microns), and the aluminum foil is dried at the temperature of 60 ℃ to obtain a positive electrode plate, wherein the thickness of the positive electrode material layer formed by the positive electrode slurry is 50 microns (the thickness of the single side).
Assembling the battery:
attaching an all-solid electrolyte membrane to an anode plate, carrying out hot pressing at 60 ℃, then, in a glove box containing high-purity Ar atmosphere, cutting the anode and the lithium-coated copper foil attached with the electrolyte layer into slices (a cathode, the same below), welding a tab by using a spot welding machine, then, placing the anode and cathode lamination in an aluminum-plastic film for sealing, taking out, and carrying out hot pressing at 60 ℃ for 1 h; thus, battery C1 was produced.
Example 2
This example serves to illustrate the electrolyte composition, the all-solid electrolyte membrane, the positive electrode, and the all-solid lithium ion battery of the invention.
Preparing an all-solid electrolyte membrane:
the components and the dosage are as follows: polymer (b): polymer P2, 60 g; lithium salt: LiN (SO)2CF3)224 g; filling: 14.5g of nano ZnO with the granularity of 800 nm; coupling agent: triethoxysilylcarbinol, 1.5 g.
Stirring and mixing a polymer and a lithium salt in a mixed solvent of 1000g of N, N-dimethylformamide for 1h, then adding a filler for ultrasonic dispersion for 15min, finally adding a coupling agent, and stirring to obtain electrolyte slurry A2; the slurry was spread on a glass plate and dried by heating at 80 ℃ to form a film, to obtain an all-solid electrolyte membrane S2 having a thickness of 500 μm.
Preparing a positive plate:
the components and the dosage are as follows: a positive electrode material: LiCoO23 g; electrolyte slurry: electrolyte slurry A2, 1.5g on a dry weight basis; conductive agent: conductive carbon black, 0.15 g.
The positive electrode material, the electrolyte slurry and the conductive agent are dispersed in 12g of N, N-dimethylformamide to obtain positive electrode slurry, then the positive electrode slurry is coated on the two sides of an aluminum foil (the thickness is 20 microns), and the aluminum foil is dried at the temperature of 60 ℃ to obtain a positive electrode plate, wherein the thickness of the positive electrode material layer formed by the positive electrode slurry is 60 microns (the thickness of the single side).
Assembling the battery:
attaching an all-solid electrolyte membrane to an anode plate, carrying out hot pressing at 60 ℃, then, in a glove box containing high-purity Ar atmosphere, cutting the anode and the lithium-coated copper foil attached with the electrolyte layer into slices (a cathode, the same below), welding a tab by using a spot welding machine, then, placing the anode and cathode lamination in an aluminum-plastic film for sealing, taking out, and carrying out hot pressing at 60 ℃ for 1 h; thus, battery C2 was produced.
Example 3
This example serves to illustrate the electrolyte composition, the all-solid electrolyte membrane, the positive electrode, and the all-solid lithium ion battery of the invention.
The process of example 1 was followed except that the components and amounts of the all-solid electrolyte membrane were prepared as follows: polymer (b): polymer P1, 70 g; lithium salt: LiN (CF)3SO2)228 g; filling: nano SiO with 100nm granularity21.8 g; coupling agent: hydroxymethyl triethoxysilane, 0.2 g; thereby obtaining electrolyte slurry a3, and an all-solid electrolyte membrane S3.
The positive plate was prepared by replacing a1 with the electrolyte slurry A3.
Cell C3 was then made.
Example 4
This example serves to illustrate the electrolyte composition, the all-solid electrolyte membrane, the positive electrode, and the all-solid lithium ion battery of the invention.
According to the method described in example 1, except that the constituent components of the all-solid electrolyte membrane were preparedAnd the dosage: polymer (b): polymer P1, 40 g; lithium salt: LiN (CF)3SO2)216 g; filling: nano SiO with 100nm granularity240 g; coupling agent: 4g of hydroxymethyl triethoxysilane; thereby obtaining electrolyte slurry a4, and an all-solid electrolyte membrane S4.
The positive plate was prepared by replacing a1 with the electrolyte slurry a 4.
Cell C4 was then made.
Example 5
This example serves to illustrate the electrolyte composition, the all-solid electrolyte membrane, the positive electrode, and the all-solid lithium ion battery of the invention.
According to the method described in example 1, except that the polymer was replaced with polymer P3 in place of polymer P1, thereby producing electrolyte slurry a5, all-solid electrolyte membrane S5, corresponding positive electrode sheet; cell C5 was then made.
Example 6
This example serves to illustrate the electrolyte composition, the all-solid electrolyte membrane, the positive electrode, and the all-solid lithium ion battery of the invention.
According to the method described in example 1, except that the polymer was replaced with polymer P4 in place of polymer P1, thereby producing electrolyte slurry a6, all-solid electrolyte membrane S6, corresponding positive electrode sheet; cell C6 was then made.
Comparative example 1
According to the method described in example 1, except that the polymer was replaced with polymer DP1 in place of polymer P1, electrolyte slurry DA1, all-solid electrolyte membrane DS1, corresponding positive electrode sheet was prepared; the battery DC1 was then made.
Comparative example 2
According to the method described in example 1, except that the polymer was replaced with polymer DP2 in place of polymer P1, electrolyte slurry DA2, all-solid electrolyte membrane DS2, corresponding positive electrode sheet was prepared; the battery DC2 was then made.
Comparative example 3
According to the method described in example 1, except that the polymer was replaced with polymer DP3 in place of polymer P1, electrolyte slurry DA3, all-solid electrolyte membrane DS3, corresponding positive electrode sheet was prepared; the battery DC3 was then made.
Test example 1
The mechanical strength and ionic conductivity of the all-solid electrolyte membrane obtained as described above were measured, and the results are shown in table 1.
And (3) testing mechanical strength: the mechanical property of the all-solid electrolyte membrane is tested by adopting a universal tester (WDW-0.5, Shenzhen Junrui tester Co., Ltd.), the all-solid electrolyte membrane is punched into a shape required by the test by using a mold in advance, the thickness of a sample is measured, and the sample is kept dry before the test. The samples were tested for tensile strength and puncture strength with the corresponding molds.
And (3) ion conductivity test: the ionic conductivity of the all-solid electrolyte membrane is tested by an alternating current impedance method and a button cell, and the testing temperature range is 30-80 ℃. And cutting the dried all-solid electrolyte membrane into a wafer with the diameter of 19mm by using a die, namely an electrolyte membrane sample, placing the electrolyte membrane sample in a glove box, and standing for 8 hours. Using a stainless steel sheet/electrolyte membrane sample/stainless steel sheet structure in a glove box (O)2<1ppm,H2O<1ppm) was prepared. Impedance test frequency range 105-0.5Hz and an amplitude of 5 mV. Before the impedance test, the sample is kept at the preset temperature for 60 min.
TABLE 1
As can be seen from the data of table 1, the all-solid electrolyte membrane formed using the electrolyte composition of the present invention has high mechanical strength and appropriate ion conductivity.
Test example 2
Specific capacity test: the method adopts a blue battery test system (CT2001C, blue electronic corporation of Wuhan city) to carry out charge and discharge test on the battery, and comprises the following specific processes: performing constant-current charge and discharge mode test on the lithium ion batteries by using a charge and discharge instrument at 60 ℃, wherein the charge cut-off voltage is 4.0V, the discharge cut-off voltage is 3.0V, and the charge and discharge multiplying power is 0.5C, and the first specific capacity and the circulating 20-time specific capacity of each lithium ion battery are obtained through test; the results are shown in Table 2.
TABLE 2
As can be seen from the data in table 2, the all-solid-state lithium ion battery provided by the invention has higher specific capacity and cycle performance.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (32)
1. An electrolyte composition comprising a polymer, a lithium salt, an inorganic filler and a coupling agent; based on the total weight of the composition, the content of the polymer is 20-80 wt%, the content of the lithium salt is 10-30 wt%, the content of the inorganic filler is 1-60 wt%, and the content of the coupling agent is 0.1-15 wt%;
the polymer is a random copolymer consisting of a structural unit provided by vinylidene fluoride, a structural unit provided by hexafluoropropylene and a structural unit provided by hydroxyalkyl acrylate; the weight average molecular weight of the polymer is 10,000-9,000,000 g/mol;
the coupling agent is a silane coupling agent with hydroxyl and/or carboxyl.
2. The electrolyte composition of claim 1, wherein the polymer is present in an amount of 30 to 70 wt.%, the lithium salt is present in an amount of 10 to 30 wt.%, the inorganic filler is present in an amount of 10 to 55 wt.%, and the coupling agent is present in an amount of 0.2 to 10 wt.%, based on the total weight of the composition.
3. The electrolyte composition of claim 1, wherein the polymer is present in an amount of 30 to 60 wt.%, the lithium salt is present in an amount of 12 to 25 wt.%, the inorganic filler is present in an amount of 12 to 40 wt.%, and the coupling agent is present in an amount of 1 to 6 wt.%, based on the total weight of the composition.
4. The electrolyte composition of any of claims 1-3, wherein the molar ratio of structural units derived from vinylidene fluoride, hexafluoropropylene, and hydroxyalkyl acrylate in the polymer is 1: 0.02-2: 0.02-1.
5. The electrolyte composition of any of claims 1-3, wherein the molar ratio of structural units derived from vinylidene fluoride, hexafluoropropylene, and hydroxyalkyl acrylate in the polymer is 1: 0.05-0.9: 0.05-0.9.
6. The electrolyte composition of any of claims 1-3, wherein the molar ratio of structural units derived from vinylidene fluoride, hexafluoropropylene, and hydroxyalkyl acrylate in the polymer is 1: 0.1-0.5: 0.1-0.5.
7. The electrolyte composition of any of claims 1-3, wherein the hydroxyalkyl acrylate is one or more of hydroxymethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxymethyl acrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.
8. The electrolyte composition of any of claims 1-3, wherein the weight average molecular weight of the polymer is 50,000-5,000,000 g/mol.
9. The electrolyte composition of any of claims 1-3, wherein the weight average molecular weight of the polymer is 100,000-1,000,000 g/mol.
10. The electrolyte composition of any of claims 1-3, wherein the weight average molecular weight of the polymer is 300,000-900,000 g/mol.
11. The electrolyte composition of any of claims 1-3, wherein the weight average molecular weight of the polymer is 400,000-800,000 g/mol.
12. The electrolyte composition of any of claims 1-3, wherein the polymer has a molecular weight distribution index of 2-6.
13. The electrolyte composition of any of claims 1-3, wherein the polymer has a molecular weight distribution index of 2-4.
14. The electrolyte composition of any of claims 1-3, wherein the lithium salt is LiClO4、LiPF6、LiBF4、LiBOB、LiN(SO2CF3)2、LiCF3SO3And LiN (SO)2CF2CF3)2One or more of;
the inorganic filler is inorganic nano filler.
15. The electrolyte composition of any one of claims 1-3, wherein the coupling agent is one or more of bis (2-hydroxyethyl) -3-aminopropyl-methoxysilane, N-hydroxymethyl-N-methylamine-propyltrimethoxysilane, hydroxymethyltriethoxysilane, triethoxysilylmethanol, N- (3-ethoxypropylsilyl) -4-hydroxybutyramide, N- (3-ethoxypropylsilyl) -glucamide, and 2, 2-bis (3-ethoxypropylsilyl-methyl) -butanol.
16. The electrolyte composition of claim 14, wherein the inorganic nanofiller is SiO2、MgO、CaO、CeO2、ZnO、SnO2、Al2O3、TiO2、ZrO2、SrO、BaO、B2O3、Ga2O3、In2O3、GeO2、Nb2O5、SiC、MgS、CaS、SrS、BaS、B2S3、Al2S3、Ga2S3、In2S3、SiS2、GeS2、SnS2、CeS2、NbS2、Li7La3Zr2O12、SrBi4Ti4O15And BaSO4One or more of (a).
17. The electrolyte composition of claim 14, wherein the inorganic nanofiller has a particle size of 10-2000 nm.
18. An all-solid electrolyte membrane comprising the electrolyte composition of any one of claims 1 to 17.
19. A method of preparing an all-solid electrolyte membrane, the method comprising: providing an electrolyte slurry comprising the electrolyte composition of any one of claims 1 to 17 and then drying to form a film.
20. The method of claim 19, wherein the concentration of the electrolyte slurry is 0.1-50 wt%.
21. An all-solid electrolyte membrane made by the method of claim 19 or 20.
22. A positive electrode, comprising: a positive electrode current collector and a positive electrode active material layer attached to a surface thereof, the positive electrode active material layer containing a positive electrode active material, the electrolyte composition according to any one of claims 1 to 17, and a conductive agent.
23. The positive electrode according to claim 22, wherein the content of the positive electrode active material is 9 to 99% by weight, the content of the electrolyte composition is 0.5 to 90% by weight, and the content of the conductive agent is 0.5 to 50% by weight, based on the total weight of the positive electrode active material, the electrolyte composition, and the conductive agent.
24. The positive electrode according to claim 22, wherein the content of the positive electrode active material is 30 to 95 wt%, the content of the electrolyte composition is 1 to 40 wt%, and the content of the conductive agent is 1 to 30 wt%, based on the total weight of the positive electrode active material, the electrolyte composition, and the conductive agent.
25. A method of making a positive electrode, the method comprising: dispersing the positive active material, the electrolyte slurry and the conductive agent in a dispersing agent to prepare positive slurry; coating the positive electrode slurry on a positive electrode current collector and drying to obtain the positive electrode;
wherein the electrolyte slurry is as defined in the method of claim 19 or 20.
26. The production method according to claim 25, wherein the positive electrode slurry contains 9 to 99 wt% of the positive electrode active material, 0.5 to 90 wt% of the electrolyte composition, and 0.5 to 50 wt% of the conductive agent, based on the total weight of the positive electrode active material, the electrolyte composition, and the conductive agent.
27. The production method according to claim 25, wherein the positive electrode slurry contains 30 to 95 wt% of the positive electrode active material, 1 to 40 wt% of the electrolyte composition, and 1 to 30 wt% of the conductive agent, based on the total weight of the positive electrode active material, the electrolyte composition, and the conductive agent.
28. The production method according to any one of claims 25 to 27, wherein the dispersant is used in an amount of 10 to 1000 parts by weight, relative to 100 parts by weight of the positive electrode active material, the electrolyte composition, and the conductive agent.
29. The production method according to any one of claims 25 to 27, wherein the dispersant is used in an amount of 20 to 800 parts by weight, relative to 100 parts by weight of the positive electrode active material, the electrolyte composition, and the conductive agent.
30. The production method according to any one of claims 25 to 27, wherein the dispersant is used in an amount of 100 parts by weight and 500 parts by weight, relative to 100 parts by weight of the positive electrode active material, the electrolyte composition and the conductive agent.
31. A positive electrode produced by the production method according to any one of claims 25 to 30.
32. An all-solid-state lithium ion battery includes a positive electrode, a negative electrode, and an all-solid electrolyte membrane interposed between the positive electrode and the negative electrode;
wherein the all-solid electrolyte membrane is the all-solid electrolyte membrane according to claim 18 or 21; the positive electrode according to any one of claims 22 to 24 and 31.
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| CN104039874A (en) * | 2011-11-17 | 2014-09-10 | 索尔维特殊聚合物意大利有限公司 | Method for manufacturing a polymer electrolyte separator and polymer electrolyte separator therefrom |
| CN106103508A (en) * | 2014-03-11 | 2016-11-09 | 株式会社吴羽 | Vinylidene fluoride analog copolymer, its manufacture method, gel electrolyte and non-aqueous class battery |
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| CN103748705A (en) * | 2011-06-23 | 2014-04-23 | 索尔维特殊聚合物意大利有限公司 | Secondary batteries |
| CN104039874A (en) * | 2011-11-17 | 2014-09-10 | 索尔维特殊聚合物意大利有限公司 | Method for manufacturing a polymer electrolyte separator and polymer electrolyte separator therefrom |
| CN106103508A (en) * | 2014-03-11 | 2016-11-09 | 株式会社吴羽 | Vinylidene fluoride analog copolymer, its manufacture method, gel electrolyte and non-aqueous class battery |
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