CN114267815A - Composite positive electrode for solid-state battery, preparation method of composite positive electrode and solid-state lithium battery - Google Patents
Composite positive electrode for solid-state battery, preparation method of composite positive electrode and solid-state lithium battery Download PDFInfo
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Abstract
本发明属于二次电池领域，具体涉及一种固态电池用复合正极及其制备方法、固态锂电池。该固态电池用复合正极，包括集流体，设置在集流体上的活性物质层，以及设置在活性物质层上的固体电解质层；所述活性物质层含有正极活性物质、导电剂、粘结剂、聚合物添加剂以及锂盐；所述聚合物添加剂在活性物质层中的质量分数为5‑10％，所述锂盐在活性物质层中的质量分数为5‑15％。本发明的固态电池用复合正极，通过向活性物质层中添加聚合物添加剂和锂盐，有效构建了极片内部离子传导网络，改善了极片内部离子传导性，降低了固态电池的交流阻抗，有利于电池高功率、高能量密度、高安全性能的实现。
The invention belongs to the field of secondary batteries, and in particular relates to a composite positive electrode for a solid-state battery, a preparation method thereof, and a solid-state lithium battery. The composite positive electrode for a solid-state battery comprises a current collector, an active material layer arranged on the current collector, and a solid electrolyte layer arranged on the active material layer; the active material layer contains a positive electrode active material, a conductive agent, a binder, A polymer additive and a lithium salt; the mass fraction of the polymer additive in the active material layer is 5-10%, and the mass fraction of the lithium salt in the active material layer is 5-15%. The composite positive electrode for a solid-state battery of the present invention effectively constructs an ion conduction network inside the pole piece by adding polymer additives and lithium salts to the active material layer, improves the ion conductivity inside the pole piece, and reduces the AC impedance of the solid-state battery. It is beneficial to the realization of high power, high energy density and high safety performance of batteries.
Description
Technical Field
The invention belongs to the field of secondary batteries, and particularly relates to a composite positive electrode for a solid-state battery, a preparation method of the composite positive electrode, and the solid-state lithium battery.
Background
The lithium ion battery has the advantages of high energy density, long cycle life, high output voltage, no memory effect, cyclic utilization, environmental friendliness and the like, and is widely applied. In recent years, development in the field of new energy vehicles and the like has put higher demands on lithium ion batteries, and particularly, development of batteries with high power, high energy density and high safety performance is urgently needed. At present, the commercialized lithium ion battery generally adopts highly flammable, explosive and volatile organic electrolyte components, and has extremely high potential safety hazard. The adoption of all-solid electrolyte without any organic liquid instead of electrolyte containing highly flammable organic liquid is an important approach to solve the safety problem of batteries.
Chinese patent application publication No. CN109004265A discloses a solid electrolyte positive electrode and a solid battery including the same, the solid electrolyte positive electrode includes a positive plate formed with a positive active material layer, and a composite solid electrolyte layer (solid electrolyte layer) formed on an outer surface of the positive active material layer, the composite solid electrolyte layer includes an organic polymer, a lithium salt, a nano inorganic solid electrolyte, a binder, etc., the solid electrolyte layer is formed on a surface of the positive active material layer, and can improve interface stability and an electrochemical window of a separator and a positive material, and improve lithium ion cycle performance. The active electrolyte layer generally includes a positive electrode active material, a conductive agent, and a binder.
The conventional solid electrolyte positive electrode has paid attention to the fact that a solid electrolyte layer is adopted to improve interface stability when the positive electrode is combined with other components of a battery, but comprehensively, the internal resistance of a pole piece is high, so that heat release, working voltage, discharge time and the like of the battery are adversely affected.
Disclosure of Invention
The invention aims to provide a composite positive electrode for a solid-state battery, which is used for further reducing the internal resistance of the conventional positive plate.
The second object of the present invention is to provide a method for producing the composite positive electrode for solid-state batteries.
A third object of the present invention is to provide a solid lithium battery using the above composite positive electrode.
In order to achieve the above object, the technical solution of the composite positive electrode for a solid-state battery of the present invention is:
a composite positive electrode for a solid-state battery includes a current collector, an active material layer disposed on the current collector, and a solid electrolyte layer disposed on the active material layer;
the active material layer contains a positive electrode active material, a conductive agent, a binder, a polymer additive, and a lithium salt;
the mass fraction of the polymer additive in the active material layer is 5-10%, and the mass fraction of the lithium salt in the active material layer is 5-15%;
the polymer additive is selected from one or the combination of more than two of polycaprolactone, polymer of unsaturated carbonate monomer, and copolymer of unsaturated carbonate monomer and polyethylene glycol acrylate monomer, the weight average molecular weight of the polymer additive is 500-50000, preferably 1000-5000; the unsaturated carbonate monomer is selected from one or a combination of two of unsaturated cyclic carbonate and ethylene carbonate;
the unsaturated cyclic carbonate has a structure represented by formula (1):
the polyethylene glycol acrylate monomer has a structure shown in a formula (2):
in the formula (1), R1、R1’、R2Each independently selected from alkyl groups of H, C1-C3; r3Is H, a benzene ring orC1-C4 alkyl, and n is an integer of 1-12.
According to the composite positive electrode for the solid-state battery, the polymer additive and the lithium salt are added into the active substance layer, so that an ion conduction network in the pole piece is effectively constructed, the ion conductivity in the pole piece is improved, the alternating current impedance of the solid-state battery is reduced, and the realization of high power, high energy density and high safety performance of the battery is facilitated.
The polymer additive is selected from a copolymer of an unsaturated carbonate monomer and a polyethylene glycol acrylate monomer, and the mass ratio of the unsaturated carbonate monomer to the polyethylene glycol acrylate monomer in copolymerization is 3: 7-7: 3. When the polymer additive is selected from the copolymer of the two monomers, the two materials can exert the synergistic improvement effect on ion conduction. The polymer additive can act synergistically with lithium salt to increase the wettability of the composite positive electrode, and is beneficial to improving the interface problem of the solid-state battery.
In the unsaturated cyclic carbonate represented by the formula (1), R1、R1’Preferably H or methyl, more preferably vinylene carbonate.
The polyethylene glycol acrylate monomer shown in the formula (2) is viscous liquid, and can be one or a combination of a plurality of polyethylene glycol acrylate, polyethylene glycol methacrylate, methoxy polyethylene glycol acrylate, ethoxy polyethylene glycol acrylate, polyethylene glycol phenyl ether acrylate, polyethylene glycol methyl ether methacrylate, polyethylene glycol phenyl ether methacrylate and the like.
In the active material layer, the mass fraction of the positive electrode active material is 64-80%, the mass fraction of the conductive agent is 3-8%, and the mass fraction of the binder is 1-3%.
The selection of the positive electrode active material is not particularly limited, and may be, for example, LiCoO2、LiNiO2、LiMn2O4、Li2Mn4O9、Li4Mn5O12、LiFePO4、LiFexMnyPO4、LiCoPO4、Li2FeSiO4、LiNi1-xCoxO2(0≤x≤1)、LiNixCoyMnzO2(NCM)、LiNixCoyAlzO2(NCA) or the like, preferably LiFePO4、LiFexMnyPO4(LFMP)、LiNixCoyMnzO2(NCM). The above materials are all commercially available products.
The conductive agent can be selected from one or more of carbon black, graphite, ketjen black, acetylene black, carbon nanotubes, carbon fibers, graphene, activated carbon and the like. Preferably carbon black, carbon fiber or a combination thereof.
The binder may be selected from one or more of polyvinylidene fluoride (PVDF), vinylidene fluoride copolymer, Polytetrafluoroethylene (PTFE), polyacrylate, etc. Preferably polyvinylidene fluoride (PVDF).
The positive electrode current collector can be selected from aluminum foil and the like.
The solid electrolyte layer may be prepared with reference to the related art, and preferably, the solid electrolyte layer is mainly composed of a polymer electrolyte and a fast ion conductor and a lithium salt dispersed in the polymer electrolyte. By adopting the solid electrolyte layer in the form, the interface stability of the positive electrode can be improved by utilizing the characteristics of the polymer electrolyte, and the transmission of lithium ions is accelerated by utilizing the fast ion conductor and the lithium salt. Preferably, the mass ratio of the polymer electrolyte to the lithium salt is 7: 3-2: 8, and the fast ion conductor accounts for 5-15% of the total mass of the polymer electrolyte and the lithium salt.
More preferably, the polymer electrolyte is a copolymer of a first monomer and a second monomer, and the mass ratio of the first monomer to the second monomer is 2:8-8: 2; more preferably 4:6 to 6: 4.
The first monomer is one or two of polyethylene glycol acrylate monomers and polyethylene glycol allyl ether monomers shown in formula (2); the second monomer is the unsaturated carbonate monomer;
the polyethylene glycol allyl ether monomer has a structure shown in a formula (3):
in the formula (3), R4Is H, phenyl or C1-C4 alkyl, and m is an integer of 1-12.
The polymer electrolyte in the form of the copolymer has a wider electrochemical window, can resist high voltage of more than 4.5V, can be applied to a high-nickel ternary material system, effectively solves the problems that the polymer electrolyte does not resist high voltage and is unstable to a ternary positive electrode system, and is beneficial to improving the interface stability of a solid-state battery and the energy density of the battery. The weight average molecular weight of the polymer electrolyte is preferably 2000 to 50000.
The polyethylene glycol allyl ether monomer shown in formula (3) is viscous liquid, and can be selected from one or more of polyethylene glycol monoallyl ether, polyethylene glycol allyl methyl ether, polyethylene glycol allyl ethyl ether, polyethylene glycol allyl phenyl ether, polyethylene glycol allyl isopropyl ether, etc.; polyethylene glycol monoallyl ether is preferred.
The fast ion conductor is selected from Li7La3Zr2O12(LLZO)、LixLa2/3-xTiO3(LLTO)(0<x<2/3)、Li1+ xAlxTi2-x(PO4)3(LATP)(0<x<2)、Li1+xAlxGe2-x(PO4)3(LAGP)(0<x<2)、LiAlO2(LAO)、Li7- xLa3Zr2-xTaxO12(LLZTO)(0<x<2)、Li7-xLa3Zr2-xNbxO12(LLZNO)(0<x<2)、Li7+xGexP3-xS11(LGPS)(0<x<3)、xLi2S·(100-x)P2S5(LPS)(0<x<100) And the like. Preferably Li1+ xAlxTi2-x(PO4)3(LATP)(0<x<2)、Li1+xAlxGe2-x(PO4)3(LAGP)(0<x<2). The above materials are all commercially available products.
The lithium salt can be selected from lithium bis (trifluoromethyl) sulfonyl imide, lithium difluoro (oxalato) borate or a combination of the lithium salt and the lithium bis (trifluoromethyl) sulfonyl imide. Lithium bistrifluoromethylsulphonylimide is preferred.
Preferably, the surface density of the active material layer is 40 to 200g/m2The compacted density is 2.0-3.0g/cm3. More preferably, the areal density is from 50 to 120g/m2. The thickness of the solid electrolyte layer is 10-200 μm. More preferably, the thickness is 50 to 150. mu.m.
The preparation method of the composite positive electrode for the solid-state battery adopts the technical scheme that:
a preparation method of a composite positive electrode for a solid-state battery comprises the following steps: mixing a positive active material, a conductive agent, a binder, a polymer additive, a lithium salt and an organic solvent to prepare active material slurry; and coating the active material slurry on a current collector, drying and rolling to form an active material layer on the current collector, and then preparing a solid electrolyte layer on the active material layer.
The organic solvent used in the slurry preparation process can be one selected from N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), and N, N-dimethylacetamide (DMAc).
The preparation method of the composite anode for the solid-state battery is simple in preparation process and suitable for industrial production.
Preferably, the preparing the solid electrolyte layer includes the steps of: prepolymerizing slurry containing a first monomer, a second monomer, lithium salt and an initiator to prepare polymer electrolyte prepolymer slurry, adding a fast ion conductor, uniformly mixing to prepare composite electrolyte slurry, coating the composite electrolyte slurry on a release film or a base material, and polymerizing to prepare a composite electrolyte film; bonding the composite electrolyte membrane with the surface of the active material layer;
the first monomer is one or two of polyethylene glycol acrylate monomers and polyethylene glycol allyl ether monomers shown in formula (2); the second monomer is the unsaturated carbonate monomer;
the polyethylene glycol allyl ether monomer has a structure shown in a formula (3):
in the formula (3), R4Is H, phenyl or C1-C4 alkyl, and m is an integer of 1-12.
The solid electrolyte layer prepared by the process has stable and controllable quality and uniform property, and is more beneficial to the exertion of the electrical property of the battery.
The initiator is an ultraviolet initiator, and the dosage of the ultraviolet initiator is 0.5-5% of the total mass of the first monomer and the second monomer; the prepolymerization time is 30-40s, and the ultraviolet polymerization time is 3-7 min. The system has certain viscosity and activity by pre-polymerization, and the fast ion conductor can be prevented from settling after being added and mixed, so that the uniform dispersion state of the fast ion conductor is maintained. The ultraviolet polymerization method is adopted, the speed is high, and the performance of the obtained solid electrolyte layer (membrane) is good. The amount of uv initiator is more preferably 1-3%.
The UV initiator may be any of the conventional techniques, such as 2,4,6- (trimethylbenzoyl) diphenylphosphine oxide, ethyl 2,4, 6-trimethylbenzoylphosphonate, 2-methyl-1- [ 4-methylthiophenyl ] -2-morpholino-1-propanone, 2-isopropylthioxanthone, ethyl 4-dimethylamino-benzoate, 1-hydroxy-cyclohexylmonophenylketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, methyl o-benzoylbenzoate, 4-chlorobenzophenone, 1' - (methylenebis-4, 1-phenylene) bis [ 2-hydroxy-2-methyl-1-propanone ], (meth) acrylic acid, methacrylic acid, acrylic acid, methacrylic acid, acrylic acid, methacrylic acid, acrylic acid, 2-hydroxy-4 '- (2-hydroxyethoxy) -2-methylpropiophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone, benzophenone, 2-methylbenzophenone, 3-methylbenzophenone, 4-phenylbenzophenone, 2-ethylhexyl 4- (dimethylamino) benzoate, 4' -bis (diethylamino) benzophenone, and the like, and preferably 2-hydroxy-2-methyl-1-phenyl-1-propanone.
The ultraviolet light initiation may be carried out by using a corresponding ultraviolet light source, and may be one of a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, a metal halogen lamp, an electrodeless lamp, a xenon lamp, a UV-LED lamp, etc., preferably a UV-LED lamp.
When the composite electrolyte membrane is polymerized on the release film, the release film is taken down after the composite electrolyte membrane is required to be attached to the surface of the active material layer, and the composite anode is prepared; when a substrate is used as a support, the substrate is a part of the composite electrolyte membrane and is brought into the cell. The base material is selected from one of polyethylene terephthalate (PET) non-woven fabric, Polyimide (PI) non-woven fabric, cellulose membrane and polyolefin membrane, and is preferably polyethylene terephthalate (PET) non-woven fabric. Under the condition of adopting the base material, the slurry can be soaked through the base material (porous) up and down, the composite electrolyte membrane has certain viscosity, and is conveniently and closely attached to electrode material layers such as an active material layer, and an integral structure is formed through a hot pressing process during the subsequent battery manufacturing.
The solid-state lithium battery adopts the technical scheme that:
a solid lithium battery comprises the composite positive electrode for the solid battery and a metallic lithium negative electrode.
The solid-state lithium battery adopting the metal lithium cathode and the composite anode has the characteristics of high power, high energy density and high safety performance, and can meet the requirements of fields such as new energy automobiles and the like on the lithium ion battery.
Preferably, the lithium metal negative electrode comprises a lithium metal matrix and a lithium metal surface protection layer arranged on the lithium metal matrix, the lithium metal matrix is a lithium metal tape or a lithium copper composite tape, the lithium metal surface protection layer comprises a polymer matrix formed by polymerization of polyethylene glycol acrylate monomers of formula (2) and lithium salt dispersed in the polymer matrix, and the mass ratio of the polymer matrix to the lithium salt is 6:4-4: 6.
The metal lithium matrix can be selected from a metal lithium belt, a lithium copper composite belt and the like.
The surface protection layer of the metal lithium can be prepared by the ultraviolet irradiation in-situ curing of polyethylene glycol acrylate monomers, lithium salts and initiators shown in the general formula (2) on the surface of a metal lithium matrix. The specific ultraviolet polymerization condition can refer to the polymerization mode of the solid electrolyte layer, and the time of ultraviolet irradiation is preferably 3-7 min. The dosage of the ultraviolet initiator is 1-3% of the mass of the polyethylene glycol acrylate monomer in the general formula (2). The thickness of the metal lithium surface protection layer is 3-5 μm.
The lithium metal negative electrode adopting the form has a protection function on a lithium metal matrix, can improve the stability of the lithium metal matrix in the air, inhibits the expansion of lithium dendrites and the lithium negative electrode, and is beneficial to the improvement of the cycle life of a solid-state battery.
After the positive electrode and the negative electrode are jointed, the battery is packaged by an aluminum plastic film and is processed by a hot pressing process to form a basic structural unit of the battery, and the battery meeting the requirements can be prepared by connecting the basic structural units in series, in parallel or in a combination mode of the two. The hot pressing temperature is 25-100 ℃, preferably 30-80 ℃; the hot pressing pressure is 0.5-50MPa, preferably 2-10 MPa; the hot pressing time is 30-300s, preferably 60-120 s.
Drawings
Fig. 1 is a schematic structural view of a composite positive electrode for a solid-state battery according to embodiment 1 of the present invention;
fig. 2 is a schematic view of a basic structural unit of a solid-state lithium battery according to embodiment 13 of the present invention;
fig. 3 is an ac impedance diagram of a solid lithium battery according to example 13 of the present invention;
fig. 4 is an ac impedance diagram of the solid lithium battery of comparative example 2;
fig. 5 is a test chart of cycle performance of the solid lithium battery of example 15 of the invention;
fig. 6 is a test chart of cycle performance of a solid lithium battery according to example 16 of the present invention;
fig. 7 is a solid electrolyte layer LSV test chart of example 1 of the present invention;
the lithium ion battery comprises a current collector 1, an active material layer 2, a solid electrolyte layer 3, a composite anode 4, a metal lithium matrix 5 and a protective layer 6.
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings.
First, the embodiment of the composite positive electrode for solid-state battery of the invention and the preparation method thereof
Example 1
The composite positive electrode for a solid-state battery according to the present embodiment, which has a schematic structural view as shown in fig. 1, includes a current collector 1, an active material layer 2 coated on the current collector 1, and a solid electrolyte layer 3 composited on the active material layer 2.
The current collector 1 is an aluminum foil.
The active material layer 2 is composed of a positive electrode active material NCM622, a conductive agent-conductive carbon black, a conductive agent-conductive carbon fiber, a binder PVDF, a polymer additive and a lithium salt LITFSI according to a mass ratio of 76:2:1:1:10: 10. The polymer additive was a polyethylene carbonate (PEC) with a weight average molecular weight of 5000.
The solid electrolyte layer is composed of a polymer electrolyte and a fast ion conductor and a lithium salt dispersed in the polymer electrolyte. The polymer electrolyte is copolymer of methoxy polyethylene glycol acrylate and vinylene carbonate (weight average molecular weight of 50000), the structure of the methoxy polyethylene glycol acrylate is shown as formula (2), and corresponding R2Is H, R3Is methyl, n-9. During copolymerization, the mass ratio of the methoxy polyethylene glycol acrylate to the vinylene carbonate is 6: 4; the lithium salt is LITFSI, and the mass ratio of the lithium salt to the total mass of the methoxypolyethylene glycol acrylate and the vinylene carbonate is 6.67: 10; the fast ion conductor is LAGP, and the mass ratio of the LAGP to the lithium salt LITFSI is 1.67: 6.67.
The composite positive electrode for the solid-state battery of the embodiment is specifically prepared by the following steps:
1) according to the mass ratio of NCM622, conductive carbon black, conductive carbon fiber, PVDF, PEC, LITFSI and NMP of 76:2:1: 10:10:80, uniformly mixing, coating on an aluminum foil, drying, rolling and baking to prepare a positive pole piece; the surface density of the positive pole piece is 50g/m2The compacted density is 2.0g/cm3；
2) Mixing methoxy polyethylene glycol acrylate, vinylene carbonate, LITFSI and HMPP according to the mass ratio of 6:4:6.67:0.1, fully stirring until the LITFSI is fully dissolved, and carrying out prepolymerization for 30s under an ultraviolet lamp to prepare a composite electrolyte prepolymerization solution;
3) adding LAGP powder according to the proportion, and fully stirring until the LAGP is uniformly dispersed to obtain mixed liquid;
4) uniformly coating the mixed solution on a 12-micron-thick PET non-woven fabric fixed on a release film, and irradiating by ultraviolet light for 3min to obtain a composite electrolyte film, wherein the thickness of the composite electrolyte film is 150 microns;
5) and (3) tightly attaching the composite electrolyte membrane to the active substance layer of the positive plate obtained in the step 1) to obtain the composite positive electrode.
Example 2
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
when the positive plate is prepared, the active material layer slurry comprises the following components: NCM 622: conductive carbon black: conductive carbon fiber: PVDF: polymer additive: LITFSI: NMP: 76:2:1:1:10:10: 80. The polymer additive was polypropylene carbonate (PPC) and had a weight average molecular weight of 5000.
The formula of the solid electrolyte layer comprises the following components: methoxy polyethylene glycol acrylate: vinylene carbonate: LITFSI: fast ion conductor: HMPP ═ 6:4:6.67:1.67: 0.1. The fast ion conductor is LATP.
Example 3
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
when the positive plate is prepared, the active material layer slurry comprises the following components: NCM 622: conductive carbon black: conductive carbon fiber: PVDF: polymer additive: LITFSI: NMP: 76:2:1:1:10:10: 80. The polymer additive is a copolymer of methoxy polyethylene glycol acrylate and vinylene carbonate, the mass ratio of the methoxy polyethylene glycol acrylate to the vinylene carbonate is 7:3 during copolymerization, and the weight-average molecular weight of the polymer additive is 5000.
The formula of the solid electrolyte layer comprises the following components: methoxy polyethylene glycol acrylate: vinylene carbonate: LITFSI: LAGP: HMPP-4: 6:6.67:1.67: 0.1.
Example 4
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
when the positive plate is prepared, the active material layer slurry comprises the following components: NCM 622: conductive carbon black: conductive carbon fiber: PVDF: PPC: and (3) PEC: LITFSI: NMP: 76:2:1:1:7:3:10: 80.
The formula of the solid electrolyte layer comprises the following components: methoxy polyethylene glycol acrylate: vinylene carbonate: LITFSI: LATP: HMPP-5: 5:6.67:1.67: 0.1.
Example 5
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
when the positive plate is prepared, the active material layer slurry comprises the following components: NCM 622: conductive carbon black: conductive carbon fiber: PVDF: PPC: LITFSI: NMP: 76:2:1:1:10:10: 80.
The formula of the solid electrolyte layer comprises the following components: methoxy polyethylene glycol acrylate: vinylene carbonate: LITFSI: LATP: HMPP ═ 6:4:10:3: 0.3.
Example 6
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
when the positive plate is prepared, the active material layer slurry comprises the following components: NCM 622: conductive carbon black: conductive carbon fiber: PVDF: PPC: LITFSI: NMP: 76:2:1:1:10:10: 80.
The formula of the solid electrolyte layer comprises the following components: methoxy polyethylene glycol acrylate: vinylene carbonate: LITFSI: LATP: HMPP ═ 6:4:6.67:0.85: 0.2.
Example 7
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
when the positive plate is prepared, the active material layer slurry comprises the following components: LMFP: conductive carbon black: conductive carbon fiber: PVDF: and (3) PEC: LITFSI: NMP: 76:2:1:1:10:10: 80.
The formula of the solid electrolyte layer comprises the following components: methoxy polyethylene glycol acrylate: vinylene carbonate: LITFSI: LAGP: HMPP ═ 6:4:6.67:1.67: 0.1.
Example 8
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
positive electrodeIn the preparation of the tablets, the composition of the active material layer slurry is: LiFePO4: conductive carbon black: conductive carbon fiber: PVDF: and (3) PEC: LITFSI: NMP: 76:2:1:1:10:10: 80.
The formula of the composite electrolyte layer is methoxy polyethylene glycol acrylate: vinylene carbonate: LITFSI: LAGP: HMPP ═ 6:4:6.67:1.67: 0.1.
Example 9
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
when the positive plate is prepared, the active material layer slurry comprises the following components: LiFePO4: conductive carbon black: conductive carbon fiber: PVDF: and (3) PEC: LITFSI: NMP: 76:2:1:1:5:15: 80.
The formula of the composite electrolyte layer is methoxy polyethylene glycol acrylate: vinylene carbonate: LITFSI: LAGP: HMPP ═ 6:4:6.67:1.67: 0.1.
Example 10
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
when the positive plate is prepared, the active material layer slurry comprises the following components: LiFePO4: conductive carbon black: conductive carbon fiber: PVDF: and (3) PEC: LITFSI: NMP: 80:2:1:2:10:5: 80.
The formula of the composite electrolyte layer is methoxy polyethylene glycol acrylate: vinylene carbonate: LITFSI: LAGP: HMPP ═ 6:4:6.67:1.67: 0.1.
Example 11
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
when the positive plate is prepared, the active material layer slurry comprises the following components: LiFePO4: conductive carbon black: conductive carbon fiber: PVDF: polycaprolactone (PCL): LITFSI: NMP: 76:2:1:1:10:10: 80.
The weight average molecular weight of the PCL is 50000.
The formula of the composite electrolyte layer is methoxy polyethylene glycol acrylate: vinylene carbonate: LITFSI: LAGP: HMPP ═ 6:4:6.67:1.67: 0.1.
Example 12
The composite positive electrode for a solid-state battery of the present example has the same structure and the same preparation method as those of example 1, except that:
when the positive plate is prepared, the active material layer slurry comprises the following components: LiFePO4: conductive carbon black: conductive carbon fiber: PVDF: and (3) PEC: LITFSI: NMP: 76:2:1:1:10:10: 80.
The formula of the composite electrolyte layer is polyethylene glycol allyl ether (APEG-500): vinylene carbonate: LITFSI: LAGP: HMPP ═ 6:4:6.67:1.67: 0.1.
Second, the embodiment of the solid lithium battery of the present invention
Example 13
The solid-state lithium battery of this embodiment has a schematic structural diagram as shown in fig. 2, and includes the composite positive electrode 4 and the negative electrode of embodiment 1, where the negative electrode includes a metallic lithium substrate 5 and a protective layer 6 disposed on the surface of the metallic lithium substrate 5, and the protective layer 6 is attached to the solid electrolyte layer of the composite positive electrode 4.
In this example, the lithium metal substrate is a lithium metal tape with a thickness of 50 μm. The protective layer consists of a polymer matrix and lithium salt dispersed in the polymer matrix, the polymer matrix is formed by polymerizing methoxy polyethylene glycol acrylate, the lithium salt is LITFSI, and the mass ratio of the polymer matrix to the lithium salt is 6: 4. The thickness of the protective layer was 5 μm.
The preparation method of the solid-state lithium battery of the embodiment is as follows:
1) according to the formula of methoxy polyethylene glycol acrylate: LITFSI: and (3) blending and uniformly mixing HMPP according to the mass ratio of 6:4:0.06, coating the mixture on the surface of a metal lithium belt, and irradiating the mixture for 3min by ultraviolet light to obtain the metal lithium cathode with the protective layer on the surface, wherein the thickness of the protective layer is 5 microns.
2) And (3) tightly attaching the solid electrolyte layer of the composite positive electrode prepared in the embodiment 1 to the protective layer of the metal lithium negative electrode, and packaging by using an aluminum-plastic film to prepare the solid lithium metal battery cell.
3) And (3) carrying out flat plate pressing on the solid lithium metal battery cell for 60s at the temperature of 30 ℃ and under the pressure of 5 MPa.
Example 14
The structure and the preparation method of the solid-state lithium battery of the embodiment are basically the same as those of the embodiment 13, and the difference is only that:
the metal lithium matrix is a lithium-copper composite tape, and comprises a copper layer serving as a current collector and a lithium layer compounded on the copper layer, wherein the thickness of the lithium layer is 50 mu m.
The formula of the protective layer comprises: methoxy polyethylene glycol acrylate: LITFSI: HMPP is 4:6:0.12, the ultraviolet irradiation time is 7min, and the thickness of the protective layer is 3 mu m.
Example 15
The structure and the preparation method of the solid-state lithium battery of the embodiment are basically the same as those of the embodiment 13, and the difference is only that:
the composite positive electrode of example 7 was used. The solid lithium metal cell is subjected to flat plate pressing at 80 ℃ and under a pressure of 2MPa for 120 s.
Example 16
The structure and the preparation method of the solid-state lithium battery of the embodiment are basically the same as those of the embodiment 13, and the difference is only that:
the composite positive electrode of example 8 was used, and the solid lithium metal cell was subjected to flat pressing at 60 ℃ and 2MPa for 120 seconds.
Third, comparative example
Comparative example 1
The composite positive electrode of comparative example 1 has substantially the same structure and preparation method as those of example 1, except that:
the active substance layer is not added with polymer additive and lithium salt, and the formula of the active substance layer comprises the following components: NCM 622: conductive carbon black: conductive carbon fiber: PVDF: NMP 80:8:2:10: 80.
Comparative example 2
A solid lithium battery of comparative example 2 was fabricated by the method of example 13 using the composite positive electrode of comparative example 1.
Fourth, example of experiment
Experimental example 1
This experimental example examined the ac impedance of the solid lithium batteries of example 13 and comparative example 2. The AC impedance is obtained by testing with an electrochemical workstation, and the frequency range of AC impedance spectrum testing is 106HZ-0.1 HZ. The detection results are shown in fig. 3 and 4, respectively.
As can be seen from fig. 3 and 4, the impedance of the example is significantly reduced compared to the comparative example.
Experimental example 2
The experimental example tests the cycle performance of the solid-state lithium batteries of example 15 and example 16 under the following conditions: the charge-discharge multiplying power is 0.1C/0.1C, and the cut-off multiplying power is 0.05C; the charge cut-off voltage of example 15 was 4.2V and the discharge cut-off voltage was 3.0V, and the charge cut-off voltage of example 16 was 3.8V and the discharge cut-off voltage was 2.5V, and the results are shown in fig. 5 and 6.
As can be seen from fig. 5 and 6, the cycle performance of the solid-state lithium batteries of examples 15 and 16 is relatively good, and the cycle of the battery 50 of example 16 hardly decays.
Experimental example 3
The solid electrolyte layer of example 1 was subjected to the LSV test under the following conditions: stainless steel is used as a working electrode, and metallic lithium is used as a counter electrode and a reference electrode. The linear sweep ranges from open circuit voltage to 6.0V (vs. Li/Li)+) The scan rate was 0.5mV/s, and the results are shown in FIG. 7. As can be seen from fig. 7, the solid electrolyte layer has a wide electrochemical window.
Claims (10)
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| WO2024168818A1 (en) * | 2023-02-17 | 2024-08-22 | 宁德时代新能源科技股份有限公司 | Polymer, electrode sheet, and related battery cell, battery and electric apparatus |
| WO2024168814A1 (en) * | 2023-02-17 | 2024-08-22 | 宁德时代新能源科技股份有限公司 | Ester polymer, electrode sheet, and battery cell, battery and electric device related thereto |
| CN115172653B (en) * | 2022-07-22 | 2026-02-13 | 欣旺达电子股份有限公司 | Composite cathode, solid-state lithium-ion secondary battery and electrical equipment |
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