WO2018190644A1 - Polymeric solid electrolyte and lithium secondary battery comprising same - Google Patents

Abstract

The present invention relates to a polymeric solid electrolyte having high ion conductivity, heat resistance, and dimensional stability and excellent oxidation stability and voltage stability, and to a lithium secondary battery comprising the same.

Description

Polymer solid electrolyte and lithium secondary battery comprising same

This application claims the benefit of priority based on Korean Patent Application No. 10-2017-0048306 filed on April 14, 2017 and Korean Patent Application No. 10-2018-0042157 filed on April 11, 2018. All content disclosed in the literature is included as part of this specification.

The present invention relates to a polymer solid electrolyte and a lithium secondary battery comprising the same.

Lithium secondary batteries are used in various industries, such as automotive batteries, in small electronic devices such as smartphones and laptop tablet PCs. These developments are being made toward technology miniaturization, light weight, high performance, and high capacity.

The lithium secondary battery includes a negative electrode, a positive electrode and an electrolyte. Lithium, carbon, etc. are used as a negative electrode active material of the lithium secondary battery, a transition metal oxide, a metal chalcogen compound, a conductive polymer, and the like are used as the positive electrode active material, and a liquid electrolyte, a solid electrolyte, and a polymer electrolyte are used as the electrolyte. have.

Among them, the polymer electrolyte is environmentally friendly because there is no problem such as leakage of liquid generated from the liquid electrolyte, and the thin film and the processing of the film form can be processed, and thus the structure of the device can be easily changed to any desired shape.

The polymer electrolyte is a material composed of a polymer, a lithium salt, a non-aqueous organic solvent (optional), and other additives, and exhibits an ionic conductivity of about 10 ^-3 to ^{-10 -8} S / cm at room temperature.

Polyethylene oxide or polypropylene oxide was mainly used as the polymer, and recently, development of a polymer electrolyte using various polymers such as polymethyl methacrylate, polyacrylonitrile, polyvinyl chloride, polyvinylidene fluoride, have.

For example, US Patent Publication No. 2015/015559 discloses a polyphenylene sulfide-based polymer solid electrolyte having excellent chemical resistance and heat resistance. The polymer solid electrolyte has been reported to exhibit excellent ionic conductivity at room temperature.

Such polymer solid electrolytes are required to be electrochemically stable in the battery driving voltage range. This is because when the oxidative stability of the polymer solid electrolyte is deteriorated, oxidation of the polymer easily occurs at the interface with the anode, causing electrolyte degradation. This eventually leads to deterioration of battery performance, a problem that must be solved, but a polymer solid electrolyte having a satisfactory ionic conductivity and oxidative stability has not been developed.

Accordingly, there is a need for the development of a new polymer solid electrolyte capable of securing interfacial stability while exhibiting excellent ionic conductivity at room temperature.

[Preceding technical literature]

[Patent Documents]

(Patent Document 1) United States Patent Application Publication No. 2015/015559, SOLID, IONICALLY CONDUCTING POLYMER MATERIAL, AND METHODS AND APPLICATIONS FOR SAME

In order to solve the above problems, the present inventors have conducted various studies to develop a polymer solid electrolyte having high ionic conductivity, heat resistance, dimensional stability, and oxidative stability.

Accordingly, it is an object of the present invention to provide a polymer solid electrolyte composition having the above effects.

In addition, the present invention is to provide a lithium secondary battery comprising a polymer film made of the polymer solid electrolyte composition.

According to the first aspect of the invention,

A polymer solid electrolyte composition comprising a polyphenylene sulfide and an ion supply compound, wherein the polyphenylene sulfide provides a polymer solid electrolyte composition in which part or all of the phenyl group hydrogen is replaced with fluorine.

In one embodiment of the invention, the polyphenylene sulfide comprises 0.1% to 45.0% by weight of fluorine.

In one embodiment of the present invention, the polyphenylene sulfide has a weight average molecular weight of 200 g / mol to 300,000 g / mol.

In one embodiment of the invention, the ion supply compound is a metal oxide, metal hydrate or metal salt, and the metal is selected from the group consisting of Li, Na, K, Mg, Ca, Zn, Al and combinations thereof.

In one embodiment of the present invention, the metal salt is a lithium salt, the lithium salt is LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , LiSCN , Li (FSO ₂ ) ₂ N LiCF ₃ CO ₂ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC ₄ F ₉ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi, LiOH.H ₂ O, LiB (C ₂ O ₄ ) ₂ , lithium chloroborane, lower aliphatic lithium carbonate, lithium tetraphenyl borate, lithium already And combinations thereof.

In one embodiment of the invention, the polymer solid electrolyte composition comprises 5 to 40% by weight of the ion feed compound.

In one embodiment of the invention, the polymer solid electrolyte composition further comprises a solvent, the solvent is methanol, ethanol, acetone, acetonitrile, tetrahydrofuran, N-methyl-2-pyrrolidone, N, N -Dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphamide, 1,3-dimethyl-2-imidazoldinone (1,3-dimethyl-2 -imidazolidinone, triethylphosphate, gamma-butyrolactone, 1,2-dimethoxyethane, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate ) And combinations thereof.

In one embodiment of the present invention, the polymer solid electrolyte composition has a viscosity at 200 ° C. of 200 to 1,000 cP.

According to a second aspect of the invention,

A polymer solid electrolyte membrane obtained by processing the above-described polymer solid electrolyte composition into a film is provided.

According to a third aspect of the invention,

It provides a lithium secondary battery comprising the above-described polymer solid electrolyte membrane laminated on the positive electrode.

The polymer solid electrolyte according to the present invention exhibits excellent heat resistance and dimensional stability with high ionic conductivity, and oxidative stability is improved to improve voltage stability of a lithium secondary battery.

1 is a graph comparing HOMO energy levels of a polyphenylene oxide oligomer substituted or unsubstituted with a polyethylene oxide oligomer and a fluorine.

2 shows an embodiment of a lithium secondary battery according to the present invention.

In the present invention, after preparing a polymer solid electrolyte composition comprising a polyphenylene sulfide in which part or all of the phenyl group hydrogen is substituted with fluorine, the present invention proposes a technique for applying to a lithium secondary battery.

Polymer Solid Electrolyte Composition

The present invention is a polymer solid electrolyte composition comprising a polyphenylene sulfide and an ion supply compound,

The polyphenylene sulfide provides a polymer solid electrolyte composition in which part or all of a phenyl group hydrogen is substituted with fluorine.

Polyphenylene sulfide (PPS) is one of thermoplastic resins (crystalline polymers) having excellent dimensional stability, and maintains its strength even in high temperature and corrosive environments, and has excellent chemical resistance and heat resistance. Thus, there has been an attempt to utilize the polymer as a basic polymer of a solid electrolyte.

However, pure polyphenylene sulfide in which other elements are not substituted has a problem in that oxidative stability is slightly lowered. Oxidative stability of the electrolyte affects the battery's life characteristics, i.e. capacity retention. If the oxidative stability of the electrolyte is deteriorated, electron transfer from the electrolyte to the anode occurs at the surface of the anode during charging, and oxidation of the electrolyte eventually leads to deterioration of battery life. Therefore, the polymer electrolyte should be free from degradation due to oxidation and reduction in the driving voltage range of the battery.

Oxidative stability of polymer solid electrolytes can be predicted from the highest Occupied Molecular Orbital (HOMO) energy level (Kita et al., J. Power Sources., 2000, 90, 27-32). In other words, the lower the HOMO energy level of the polymer, the more difficult electrons move to the anode. Therefore, when the polymer having the low HOMO energy level is used as the electrolyte, oxidation of the electrolyte occurs at a higher voltage (voltage of the anode during charging). Therefore, when the polymer solid electrolyte is used, the battery can be stably operated even at a relatively high voltage without deterioration of the battery life.

Accordingly, the present inventors have studied a method of improving the oxidative stability by using polyphenylene sulfide as a basic polymer, and as a result, when the phenyl group hydrogen of the polyphenylene sulfide is partially or completely replaced with fluorine, the HOMO energy level of the polymer It was confirmed that the lowering, thereby improving the oxidative stability of the polymer solid electrolyte to improve the voltage stability of the lithium secondary battery.

Polyphenylene sulfide used as the lithium ion conductive polymer in the present invention is to include a repeating unit represented by the following formula (1).

[Formula 1]

In Formula 1, R ₁ to R ₄ are the same as or different from each other, and each H or F, at least one is F, n is an integer of two or more.

In one example, the fluorine-substituted polysulfide used in the composition of the present invention may be composed of one or more repeating units having the following structural formula.

As described above, when a part or all of the polyphenylene sulfide phenyl group hydrogen is replaced with fluorine, the HOMO energy level of the polymer solid electrolyte is lowered and the oxidation stability is improved. In the present invention, the polyphenylene sulfide may include 0.1 to 45 wt%, preferably 5 to 45 wt%, more preferably 10 to 45 wt% of fluorine. When the polyphenylene sulfide contains fluorine in the above-described range, the polyphenylene sulfide has an oxidative stability in a range suitable for use for a polymer solid electrolyte.

The HOMO energy level of the polymer solid electrolyte can be calculated using the Gaussian09 program package (Gaussian 09 Revision C.01, Gaussian Inc., Wallingford, CT, 2009.), from which the oxidation stability of the polymer solid electrolyte can be predicted. have.

Specifically, Density Functional Theory (DFT) calculation is applied to the calculation, and B3PW91 functional and 6-31 + G * basis sets are used ( Phys. Rev. B 2006, 74, 155108. and J. Phys .: Condens Matter 1993, 98, 5648.). For the single molecule of the polymer for which the energy level is to be calculated, the structural optimization of the single molecule is performed in the gas phase, and then the HOMO energy level is calculated through the electronic structure optimization in the optimized molecular structure.

The results of calculating the HOMO energy levels for the following four oligomers by the above calculation method are shown in FIG. 1.

Referring to FIG. 1, in the case of polyphenylene sulfide in which hydrogen of the phenyl group is not substituted at all, the energy level is high, and oxidative stability is expected to be remarkably decreased as compared with polyethylene oxide (PEO) which is commonly used as a polymer solid electrolyte. However, when hydrogen in the phenyl group of the polyphenylene sulfide is replaced with fluorine, the energy level is gradually lowered, and when all hydrogens in the 5 phenyl groups in the repeating unit are replaced with fluorine, the energy level is lowered to a level similar to that of polyethylene oxide. . From these calculation results, it can be expected that the oxidative stability of the polyphenylene sulfide-based polymer solid electrolyte can be improved by substituting hydrogen of the phenyl group with fluorine.

In the present invention, when used as a polymer solid electrolyte, the fluorine-substituted polyphenylene sulfide has a weight average molecular weight in the range of 200 g / mol to 300,000 g / mol. When the weight average molecular weight is less than 200 g / mol, such as mechanical strength (physical properties of the yarn), chemical resistance, heat resistance, and the like is lowered, when it exceeds 300,000 g / mol is not easy to manufacture a film.

The polyphenylene sulfide is a crystalline polymer that is partially crystalline, and has a crystallinity value of 30% to 100% and preferably 50% to 100% for the base polymer and is a crystalline or semi-crystalline polymer. Moreover, glass transition temperature is 80 degreeC or more, Preferably it is 120 degreeC, More preferably, it is 150 degreeC or more, Most preferably, it is 200 degreeC or more. The base polymer has a melting temperature of at least 250 ° C and preferably at least 280 ° C and more preferably at least 320 ° C. Moreover, the polyphenylene sulfide of the said structure contains all three types of linear, bridge | crosslinking type, and semi-crosslinking type according to the connection form of S, and all these structures are included in this invention.

The method for preparing the fluorine-substituted polyphenylene sulfide is not particularly limited in the present invention and may vary. As an example, pure polyphenylenesulfide polymers obtained by polymerization of fluorine-substituted aromatic monomers (e.g., dihalobenzenes such as diiodobenzene, dichlorobenzene) and elemental sulfur or sodium sulfide may be prepared using known halogenation methods. Fluorine substituted polyphenylene sulfide can be prepared by fluorination. As another example, a method of polymerizing an aromatic monomer having one or more fluorine substituents and elemental sulfur or sodium sulfide may be used.

The ion supply compound is for supplying ions in the polymer solid electrolyte composition, and includes a compound containing hydroxyl ions, or a substance that can be chemically converted into a compound containing hydroxyl ions, for example , But are not limited to hydroxides, oxides, salts or mixtures thereof.

According to one embodiment of the invention, the ion supply compound may be a metal oxide or a hydrate or salt. More specifically, Li ₂ O, Na ₂ O, MgO, CaO, ZnO, LiOH, KOH, NaOH, CaCl ₂ , AlCl ₃ , MgCl ₂ and the like can be used, these can be used by mixing at least one or more.

According to one embodiment of the invention, the ion supply compound may be a lithium salt.

Lithium salt simultaneously has the effect of increasing the lithium ion conductivity in addition to the ion supply. Examples of the lithium salt include LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , LiSCN, Li (FSO ₂ ) ₂ N LiCF ₃ CO ₂ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC ₄ F ₉ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi, LiOH.H ₂ O, LiB (C ₂ O ₄ ) ₂ , 1 selected from the group consisting of lithium chloroborane, lower aliphatic carbonate, lithium tetraphenyl borate, lithium imide and combinations thereof Lithium salts of species and the like can be used.

Preferably, the ion supply compound is included in 5 to 40% by weight, preferably 10 to 30% by weight in the total polymer solid electrolyte. If the content of the ion supply compound is less than the above range, it is not easy to secure the lithium ion conductivity, and on the contrary, if it exceeds the above range, there is no significant increase in effect, so it is uneconomical, so it is appropriately selected within the above range.

As a result, the polymer solid electrolyte membrane proposed in the present invention has the effect of improving the physical properties of the film including the same, while increasing the high level of lithium ion conductivity equivalent to the liquid phase even in the form of a solid film at 10 ^-4 S / cm. .

The polymer solid electrolyte composition presented above is prepared in the form of a film through a wet process, and includes a solvent for this purpose.

The solvent may be a solvent capable of dissolving a lithium ion conductive polymer. For example, the organic solvent may be methanol, ethanol, acetone, acetonitrile, tetrahydrofuran, N-methyl-2-pyrrolidone, N, N -Dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphamide, 1,3-dimethyl-2-imidazoldinone (1,3-Dimethyl-2 -imidazolidinone, triethyl phosphate, gamma-butyrolactone, 1,2-dimethoxyethane, dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate At least one selected from the group consisting of) is possible.

The content of the solvent is limited in consideration of the viscosity of the finally obtained polymer solid electrolyte composition. In other words, the higher the content of the solvent, the higher the viscosity of the final composition is obtained, the lower the workability, and the lower the viscosity, the lower the viscosity.

The solution viscosity at 30 ° C of the polymer solid electrolyte composition of the present invention is not particularly limited, but is preferably 200 to 1,000 cP, preferably 300 to 800 cP or less, and more preferably 500 to 700 cP. . This viscosity control allows to secure the viscosity to increase the film processability in producing a polymer solid electrolyte film.

If the viscosity exceeds the above range, the thickness of the transverse direction (TD, Transverse Direction) due to the flatness of the coating liquid becomes uneven and the fluidity is lost, so that uniform coating may be difficult. This can prevent staining due to excessive flow of the coating liquid and cause a problem of uneven thickness of the mechanical direction (MD).

Polymer solids Electrolyte membrane

The polymer solid electrolyte composition may be formed as a polymer solid electrolyte membrane through a film manufacturing process as known in the art. The polymer solid electrolyte membrane of the present invention may be used alone as a polymer solid electrolyte or may be applied only to the anode interface. When the polymer solid electrolyte membrane of the present invention is applied only to the positive electrode interface, the polymer solid electrolyte in contact with the negative electrode interface may be a pure polyphenylene sulfide polymer solid electrolyte without fluorine substitution.

Examples of the above-mentioned film forming method include any suitable film forming method, such as a solution casting method (solution casting method), a melt casting extrusion method, a calendering method, or a compression molding method. Of these film forming methods, a solution cast method (solution casting method) or a melt film extrusion method is preferable.

For example, a solution cast method (solution casting method) may be used for film production.

In the solution casting method, the coating of the polymer solid electrolyte composition is performed on a support, in which the support is coated directly on either the positive electrode or the negative electrode, or coated on a separate substrate and then separated and laminated to the positive electrode and the negative electrode. can do.

In this case, the substrate may be a glass substrate or a plastic substrate. Examples of the plastic substrate include polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene, 3-acetic cellulose, 2-acetic cellulose, poly (meth) acrylic acid alkyl ester, poly (meth) acrylic acid ester copolymer, polyvinyl chloride, poly Various plastic films such as vinyl alcohol, polycarbonate, polystyrene, cellophane, polyvinylidene chloride copolymer, polyamide, polyimide, vinyl chloride / vinyl acetate copolymer, polytetrafluoroethylene, and polytrifluoroethylene Can be mentioned. Moreover, the composite material which consists of these 2 or more types can also be used, The polyethylene terephthalate film excellent in the light transmittance is especially preferable. The thickness of the support is preferably 5 to 150 µm, more preferably 10 to 50 µm.

For example, spin coating, doctor blade coating, dip coating, solvent casting, slot die coating, spray coating. Roll coating, extrusion coating, curtain coating, die coating, wire bar coating or knife coating may be used.

At this time, it is necessary to adjust the parameters in each process in order to produce a uniform polymer solid electrolyte membrane.

For example, a device having a thickness gap of 10 to 200 μm may be used for spin coating and 500 to 4000 rpm for doctor blade coating. In addition, when performing the spray coating can be carried out by spraying with a spraying number of 5 to 100 times through a spray pressure of 0.5 to 20 MPa. The design of these processes and the selection of parameters can be controlled by one of ordinary skill in the art.

Drying is performed after the coating to form a polymer solid electrolyte membrane.

Although drying depends on each component, the kind of organic solvent, and content ratio, it is preferable to carry out for 30 second-15 minutes at 60-100 degreeC.

In this case, the drying may be performed by one of hot air drying, electromagnetic wave drying, vacuum drying, spray drying, drum drying, and freeze drying, and preferably hot air drying.

After the coating and drying are performed, the thickness of the polymer solid electrolyte membrane is finally formed to the thickness of the membrane to be prepared, and if necessary, the coating-drying or coating step is performed at least once.

As another example, melt extrusion may be used for film production.

Examples of the melt-extrusion method include a T-die method and an inflation method. Molding temperature becomes like this. Preferably it is 150-350 degreeC, More preferably, it is 200-300 degreeC.

In the case of forming the film by the T-die method, a T-die is attached to the tip of a known single screw extruder or a twin screw extruder, and the film extruded in a film shape can be rolled to obtain a roll-shaped film.

If desired, the hot melt may be subjected to a first hot melt, a filtration filter, and a second hot melt in sequence. The melt-extruded heat-melted temperature may be 170 ℃ to 320 ℃, preferably 200 ℃ to 300 ℃. After melt extrusion from the T die, it can be cooled and solidified using at least one or more metal drums maintained at 70 ° C to 140 ° C. Thus, when using a drum (casting roll), you may extrude under the above-mentioned temperature conditions or the temperature below.

Lithium secondary battery

The polymer solid electrolyte membrane, as described above, has high lithium ion conductivity of 10 ⁻⁴ S / cm level equivalent to that of the liquid electrolyte, and is excellent in heat resistance and dimensional stability, and thus may be applied to a lithium secondary battery.

In particular, the polymer solid electrolyte membrane includes an ion supply compound and a polyphenylene sulfide partially or wholly substituted with fluorine, thereby exhibiting improved oxidation stability and excellent ion conductivity and physical properties compared to polyphenylene sulfide without fluorine substitution. . In addition, due to heat resistance, durability, chemical resistance and flame retardance, etc., problems caused when driving the lithium secondary battery (heat generation, explosion, film degradation, etc.) can be solved to further increase the voltage stability of the lithium secondary battery.

The polymer solid electrolyte membrane according to the present invention is applied to a lithium secondary battery, and can be preferably used as a polymer solid electrolyte. In this case, the polymer solid electrolyte membrane is preferably used to contact the surface of the positive electrode in order to secure the above-mentioned effect.

1 illustrates an embodiment of a lithium secondary battery according to the present invention.

Referring to FIG. 1, the polymer solid electrolyte membrane of the present invention may be applied only to the anode interface. In this case, a pure polyphenylene sulfide polymer solid electrolyte that is not fluorinated may be used as the electrolyte contacting the cathode interface.

In addition, the polymer solid electrolyte membrane of the present invention may be applied alone as an electrolyte, in which case the polymer solid electrolyte membrane is interposed between the positive electrode and the negative electrode.

As such, when the polymer solid electrolyte membrane of the present invention is used as the polymer solid electrolyte in contact with the positive electrode interface, the phenomenon of oxidizing the electrolyte on the surface of the positive electrode during battery operation is significantly reduced, and thus the battery life characteristics can be improved.

In addition, the electrolyte may further include a material used for this purpose in order to further increase the lithium ion conductivity.

If necessary, the polymer solid electrolyte further includes an inorganic solid electrolyte or an organic solid electrolyte. The inorganic solid electrolyte is a ceramic-based material, a crystalline or amorphous and crystalline materials can be _{used, Thio-LISICON (Li 3.} 25 Ge 0 .25 P 0. 75 S 4), Li 2 S-SiS 2, LiI -Li ₂ S-SiS ₂ , LiI-Li ₂ SP ₂ S ₅ , LiI-Li ₂ SP ₂ O ₅ , LiI-Li ₃ PO ₄ -P ₂ S ₅ , Li ₂ SP ₂ S ₅ , Li ₃ PS ₄ , Li ₇ P ₃ S ₁₁ , Li ₂ OB ₂ O ₃ , Li ₂ OB ₂ O ₃ -P ₂ O ₅ , Li ₂ OV ₂ O ₅ -SiO ₂ , Li ₂ OB ₂ O ₃ , Li ₃ PO ₄ , Li ₂ O-Li ₂ WO ₄ -B ₂ O ₃ , LiPON, LiBON, Li ₂ O-SiO ₂ , LiI, Li ₃ N, Li ₅ La ₃ Ta ₂ O12, Li ₇ La ₃ Zr ₂ O ₁₂ , Li ₆ BaLa ₂ Ta ₂ O ₁₂ , Li ₃ PO _{(4-3 / 2w)} Nw (w is w <1), Li _{3 .} The inorganic solid electrolyte such as a _{6 Si 0 .6 P 0. 4 O} 4 is possible.

Examples of the organic solid electrolyte include polymer-based materials such as polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyedgetion lysine, polyester sulfides, polyvinyl alcohol, and polyvinylidene fluoride. What mixed lithium salt can be used. At this time, these may be used alone or in combination of at least one or more.

The specific application method to the polymer solid electrolyte is not particularly limited in the present invention, and may be selected or selected by a method known by those skilled in the art.

The lithium secondary battery to which the polymer solid electrolyte is applicable is not limited to the positive electrode or the negative electrode, and is particularly applicable to a lithium-air battery, a lithium oxide battery, a lithium-sulfur battery, a lithium metal battery, and an all-solid-state battery that operate at high temperature. .

The positive electrode of a lithium secondary battery may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Formula _{Li 1 + x Mn 2 - x} O 4 (0≤x≤0.33), LiMnO 3, the lithium manganese oxide such as LiMn ₂ O _3, LiMnO _2; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , Cu ₂ V ₂ O ₇ and the like; Ni-site-type lithium nickel oxide represented by the formula LiNi _{1 - x} M _x O ₂ (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga; 0.01 ≦ x ≦ 0.3); Formula LiMn _{2 - x} M _x O ₂ (M = Co, Ni, Fe, Cr, Zn or Ta; 0.01≤x≤0.1) or Li ₂ Mn ₃ MO ₈ (M = Fe, Co, Ni, Cu or Zn Lithium manganese composite oxide represented by; Spinel-structure lithium manganese composite oxides represented by LiNi _x Mn _{2 - x} O ₄ ; LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with alkaline earth metal ions; Disulfide compounds; Chalcogenides such as Fe ₂ (MoO ₄ ) ₃ , Cu ₂ Mo ₆ S ₈ , FeS, CoS and MiS, scandium, ruthenium, titanium, vanadium, molybdenum, chromium, manganese, iron, cobalt, nickel, copper, zinc, etc. Oxides, sulfides or halides may be used, and more specifically, TiS ₂ , ZrS ₂ , RuO ₂ , Co ₃ O ₄ , Mo ₆ S ₈ , V ₂ O _5, etc. may be used, but is not limited thereto. no.

Such a positive electrode active material may be formed on a positive electrode current collector. The positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, carbon, on the surface of aluminum or stainless steel, The surface-treated with nickel, titanium, silver, etc. can be used. In this case, the positive electrode current collector may use various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric having fine irregularities formed on a surface thereof so as to increase the adhesion with the positive electrode active material.

In addition, the negative electrode has a negative electrode mixture layer having a negative electrode active material formed on the negative electrode current collector, or uses a negative electrode mixture layer (for example, lithium foil) alone.

In this case, the type of the negative electrode current collector or the negative electrode mixture layer is not particularly limited in the present invention, and a known material may be used.

In addition, the negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, and for example, carbon on the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel , Surface-treated with nickel, titanium, silver, or the like, aluminum-cadmium alloy, or the like can be used. In addition, the negative electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric having fine irregularities formed on the surface, similar to the positive electrode current collector.

In addition, the negative electrode active material is one selected from the group consisting of crystalline artificial graphite, crystalline natural graphite, amorphous hard carbon, low crystalline soft carbon, carbon black, acetylene black, Ketjen black, super-P, graphene, fibrous carbon Carbon-based material, Si-based material, LixFe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), Sn _x Me _{1 - x} Me ' _y O _z (Me: Mn, Fe Me ': Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 <x≤1;1≤y≤3; 1≤z≤8) Metal composite oxides; Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , Metal oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials; Titanium oxide; Lithium titanium oxide and the like may be included, but are not limited thereto.

In addition, the negative electrode active material is SnxMe _{1 - x} Me ' _y O _z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, group 1, group 2, group 3 elements of the periodic table, Metal composite oxides such as halogen, 0 <x ≦ 1, 1 ≦ y ≦ 3, 1 ≦ z ≦ 8); SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO _{2 2} , Bi ₂ O ₃ , Bi ₂ O ₄ and An oxide such as Bi ₂ O ₅ may be used, and a carbon-based negative active material such as crystalline carbon, amorphous carbon or a carbon composite may be used alone or in combination of two or more thereof.

In this case, the electrode mixture layer may further include a binder resin, a conductive material, a filler and other additives.

The binder resin is used for bonding the electrode active material and the conductive material and the current collector. Examples of such binder resins include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetra Fluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers thereof, and the like.

The said conductive material is used in order to improve the electroconductivity of an electrode active material further. Such a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black and summer black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Polyphenylene derivatives and the like can be used.

The filler is optionally used as a component for inhibiting the expansion of the electrode, and is not particularly limited as long as it is a fibrous material without causing chemical change in the battery. Examples of the filler include olefinic polymers such as polyethylene and polypropylene; Fibrous materials, such as glass fiber and carbon fiber, are used.

The shape of the lithium secondary battery as described above is not particularly limited, and may be, for example, jelly-roll type, stack type, stack-fold type (including stack-Z-fold type), or lamination-stack type. It may be stack-foldable.

After preparing an electrode assembly in which the negative electrode, the polymer solid electrolyte, and the positive electrode are sequentially stacked, the electrode assembly is placed in a battery case, and then sealed by a cap plate and a gasket to fabricate a lithium secondary battery.

At this time, the lithium secondary battery can be classified into various batteries such as lithium-sulfur battery, lithium-air battery, lithium-oxide battery, lithium all-solid battery according to the cathode / cathode material used, and are cylindrical, square and coin type depending on the shape. It can be classified into pouch type, and can be divided into bulk type and thin film type according to the size. Since the structure and manufacturing method of these batteries are well known in the art, detailed description thereof will be omitted.

The lithium secondary battery according to the present invention can be used as a power source for devices requiring high capacity and high rate characteristics. Specific examples of the device include a power tool moving by being driven by an electric motor; Electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like; Electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; Electric golf carts; Power storage systems and the like, but is not limited thereto.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is natural that such variations and modifications fall within the scope of the appended claims.

EXAMPLE

Example  One

A solution was prepared by mixing a fluorine-substituted polyphenylene sulfide having a repeating unit and LiTFSI in a weight ratio of 7: 3 and dissolving it in an NMP solvent.

The resulting solution was coated on a Teflon film with a doctor blade coating to form a poly (phenylene sulfide-phenylene sulfoxide) coating film (coating thickness of 50 μm).

Subsequently, a polymer solid electrolyte membrane was prepared for 24 hours at room temperature and 24 hours in a 60 ° C. vacuum oven.

Example  2

A solution was prepared by mixing a fluorine-substituted polyphenylene sulfide having a repeating unit and LiTFSI in a weight ratio of 7: 3 and dissolving it in an NMP solvent.

The resulting solution was coated on a Teflon film with a doctor blade coating to form a poly (phenylene sulfide-phenylene sulfoxide) coating film (coating thickness of 50 μm).

Subsequently, a polymer solid electrolyte membrane was prepared at room temperature for 24 hours and at 60 ° C. in a vacuum oven for 24 hours.

Comparative example  One

A solution was prepared by mixing pure polyphenylenesulfide unsubstituted with fluorine and LiTFSI in a weight ratio of 7: 3, dissolved in NMP solvent.

The resulting solution was coated on a Teflon film with a doctorblade coating (coating thickness 50 μm). A polymer solid electrolyte membrane was prepared for 24 hours at room temperature and 24 hours in a 60 ° C. vacuum oven.

Experimental Example 1 Measurement of Physical Properties

(1) thickness measurement

As a result of measuring the thicknesses of the polymer solid electrolyte membranes prepared in Examples and Comparative Examples, all were measured to be about 45 μm.

(2) Lithium ion conductivity  Measure

Maker: As a result of measuring the lithium ion conductivity of the polymer solid electrolyte membranes prepared in Examples and Comparative Examples using the impedance measuring device of the VSP model of Bio-Logic SAS, there was almost no lithium ion conductivity in Comparative Example 1. In the case of Examples 1 and 2, the lithium ion conductivity is shown as a high value.

Experimental Example  2: voltage stability measurement

In order to measure the voltage stability of the polymer solid electrolyte membranes prepared in Examples and Comparative Examples, a Li symmetry battery was manufactured, and the film was inserted therein to prepare a lithium secondary battery.

-High temperature evaluation: After charging the manufactured @ battery at 1 C to 4.2V, the temperature was raised to 150 degreeC by the rising rate of 5 degree-C / min, and it left at 150 degreeC for 10 minutes.

Overcharge: The prepared battery was charged to 0.2C up to 12V.

As a result of the evaluation, since the polymer solid electrolyte membranes of Examples 1 and 2 can reduce the HOMO energy levels of 0.28 eV and 1.10 eV, respectively, compared to the polymer solid electrolyte membrane of Comparative Example 1, the oxidation stability is high, and accordingly, It was confirmed that the voltage stability of the lithium secondary batteries of Examples 1 and 2 was superior to the battery.

Although the above has been illustrated and described with respect to the preferred embodiments of the present specification, the present specification is not limited to the above-described specific embodiments, it is usually in the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

Claims (10)

1. A polymer solid electrolyte composition comprising a polyphenylene sulfide and an ion supply compound,

   The polyphenylene sulfide is a part or all of the phenyl group hydrogen is substituted with fluorine, polymer solid electrolyte composition.
2. The method according to claim 1,

   The polyphenylene sulfide is a polymer solid electrolyte composition, characterized in that it comprises 0.1 to 45.0% by weight of fluorine.
3. The method according to claim 1,

   The polyphenylene sulfide has a weight average molecular weight of 200 g / mol to 300,000 g / mol, characterized in that the polymer solid electrolyte composition.
4. The method according to claim 1,

   The ion supply compound is a metal oxide, metal hydrate or metal salt,

   The metal is a solid polymer electrolyte composition, characterized in that selected from the group consisting of Li, Na, K, Mg, Ca, Zn, Al and combinations thereof.
5. The method according to claim 4,

   The metal salt is a lithium salt,

   The lithium salt is LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , LiSCN, Li (FSO ₂ ) ₂ N LiCF ₃ CO ₂ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC ₄ F ₉ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi, LiOH.H ₂ O, LiB (C ₂ O ₄ ) ₂ , chloroborane lithium, lower aliphatic lithium carbonate, lithium tetraphenyl borate, lithium imide and combinations thereof Solid electrolyte compositions.
6. The method according to claim 1,

   The polymer solid electrolyte composition is a polymer solid electrolyte composition, characterized in that it comprises 5 to 40% by weight of the ion supply compound.
7. The method according to claim 1,

   The polymer solid electrolyte composition further comprises a solvent,

   The solvent is methanol, ethanol, acetone, acetonitrile, tetrahydrofuran, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide , Dimethyl sulfoxide, hexamethylphosphamide, 1,3-dimethyl-2-imidazolidinone, triethyl phosphate, gamma-butyrolactone, 1,2-dimethoxyethane (1,2-dimethoxyethane), dimethyl carbonate (dimethyl carbonate), ethylmethyl carbonate (ethylmethyl carbonate), diethyl carbonate (diethyl carbonate), and a polymer solid electrolyte composition, characterized in that selected from the group consisting of these.
8. The method according to claim 1,

   The polymer solid electrolyte composition is a polymer solid electrolyte composition, characterized in that the viscosity at 30 ℃ 200 to 1,000 cP.
9. A polymer solid electrolyte membrane obtained by processing the polymer solid electrolyte composition according to claim 1 into a film.
10. Lithium secondary battery comprising a polymer solid electrolyte membrane according to claim 9 stacked on a positive electrode.

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