KR102618538B1 - Lithium metal battery including lithium metal anode, method of protecting the lithium metal anode, and protective layer prepared according to the method - Google Patents

Abstract

Lithium metal cathode; A protective film disposed on the lithium metal anode and comprising at least one selected from i) a polymer, ii) a metal salt containing a Group 1 or Group 2 element, and a nitrogen-containing additive; anode; and a liquid electrolyte interposed between the protective film and the anode, wherein at least one selected from metal salts containing the Group 1 or Group 2 elements and nitrogen-containing additives is insoluble in the organic solvent of the liquid electrolyte. .

Description

Lithium metal battery including lithium metal anode, method of protecting the lithium metal anode, and protective layer prepared according to the method }

A lithium metal battery including a lithium metal anode, a method for protecting the lithium metal anode, and a protective film manufactured according to the method are presented.

Lithium secondary batteries are high-performance secondary batteries with the highest energy density among currently commercialized secondary batteries and can be used in various fields, such as electric vehicles.

A lithium metal thin film can be used as the negative electrode of a lithium secondary battery. When such a lithium metal thin film is used as a negative electrode, it has high reactivity with the liquid electrolyte during charging and discharging due to the high reactivity of lithium. Alternatively, dendrites may be formed on the lithium negative electrode thin film, which may reduce the lifespan and stability of lithium secondary batteries using lithium metal thin films, so improvements are required.

One aspect is to provide a lithium metal battery in which the formation of lithium dendrites is suppressed on the surface of a lithium metal anode.

Another aspect provides a method of protecting the lithium metal cathode of the lithium metal battery.

Another aspect provides a protective film prepared according to the method described above.

according to one side

Lithium metal cathode;

A protective film disposed on the lithium metal anode and comprising at least one selected from i) a polymer, ii) a metal salt containing a Group 1 or Group 2 element, and a nitrogen-containing additive;

anode; and

It includes a liquid electrolyte interposed between the protective film and the anode,

A lithium metal battery is provided in which at least one selected from metal salts containing the Group 1 or Group 2 elements and nitrogen-containing additives is insoluble in the organic solvent of the liquid electrolyte.

According to another aspect, obtaining a composition for forming a protective film by mixing i) a polymer and ii) one or more selected from the group consisting of a metal salt containing a group 1 or group 2 element and a nitrogen-containing additive;

Supplying the composition for forming a protective film to a lithium metal anode; and

A method of protecting the above-described lithium metal anode is provided, including the step of drying the resultant to form a protective film.

According to another aspect, a protective film manufactured according to the above-described method is provided.

The lithium metal battery according to one embodiment effectively suppresses the growth of lithium dendrites on the surface of the lithium metal anode, increases the lithium electrodeposition density, reduces the interfacial resistance between the lithium metal anode and the protective film, and increases lithium ion mobility. do. As a result, it is possible to produce a lithium metal battery with improved rate performance and lifespan.

Figure 1 schematically shows the structure of a lithium metal battery according to an embodiment.
Figure 2 schematically shows the structure of a lithium metal battery according to another embodiment.
Figures 3a and 3b are scanning electron micrographs showing the surface of the lithium metal anode after charging at 0.1 C in the lithium metal battery manufactured according to Example 2 and Comparative Example 1, respectively.
Figures 4a and 4b are scanning electron micrographs showing the cross-section of the lithium metal anode after charging at 0.1 C in the lithium metal battery manufactured according to Example 2 and Comparative Example 1, respectively.
Figure 5 shows the results of impedance analysis for the lithium metal battery manufactured according to Example 2 and the lithium metal battery manufactured according to Comparative Example 1.
Figure 6 shows the change in discharge capacity according to the number of cycles in the lithium metal batteries manufactured according to Example 1, Comparative Example 1, and Comparative Example 4.
Figure 7 shows the change in Coulomb efficiency according to the number of cycles in lithium metal batteries manufactured according to Example 1 and Comparative Examples 1 and 4.
Figure 8 shows a stress-strain curve of the protective film manufactured according to Example 1.
Figure 9 shows the rate performance of the lithium metal battery manufactured according to Example 2 and Comparative Example 1.
Figure 10 shows the change in cell voltage for a symmetric cell using the protective film of Example 2 and the lithium metal thin film of Comparative Example 1.

Referring to the attached drawings, an exemplary lithium metal battery, a manufacturing method thereof, a method for protecting a lithium metal anode of the lithium metal battery, and a protective film manufactured according to the method will be described in more detail below.

Lithium metal cathode; A protective film disposed on the lithium metal anode, i) a polymer, ii) a metal salt containing a group 1 or group 2 element, and a nitrogen-containing additive; anode; and a liquid electrolyte interposed between the protective film and the anode, wherein at least one selected from metal salts containing the Group 1 or Group 2 elements and nitrogen-containing additives is insoluble in the organic solvent of the liquid electrolyte. .

The metal salt containing the Group 1 or Group 2 element is a metal salt containing one or more elements selected from Cs, Rb, K, Ba, Sr, Ca, Na, and Mg. Examples of such metal salts include Cs bis(trifluoromethylsulfonyl)imide {CsTFSI: Cs(bis(trifluoromethylsulfonyl)imide)}, CsNO ₃ , CsPF ₆ , Cs bis(fluorosulfonyl)imide {CsFSI: Cs (bis(fluorosulfonyl)imide)}, CsAsF ₆ , CsClO ₄ , CsBF ₄ , RbTFSI, RbNO ₃ , RbPF ₆ , RbFSI, RbAsF ₆ , RbClO ₄ , RbBF ₄ , KTFSI, KNO ₃ , KPF ₆ , KFSI, KAsF ₆ , KClO ₄ , KBF ₄ , NaTFSI, NaNO ₃ , NaPF ₆ , NaFSI, NaAsF ₆ , NaClO ₄ , NaBF ₄ , Ba(TFSI) ₂ , Ba(NO ₃ ) ₂ , Ba(PF ₆ )2, Ba(FSI) ₂ , Ba(AsF ₆ ) ₂ , Ba(ClO ₄ ) ₂ , Ba(BF ₄ ) ₂ , Sr(TFSI) ₂ , Sr(NO ₃ ) ₂ , Sr(PF ₆ )2, Sr(FSI) ₂ , Sr( AsF ₆ ) ₂ , Sr(ClO ₄ ) ₂ , Sr(BF ₄ ) ₂ , Ca(TFSI) ₂ , Ca(NO ₃ ) ₂ , Ca(PF ₆ )2, Ca(FSI) ₂ , Ca(AsF ₆ ) ₂ , Ca(ClO ₄ ) ₂ , Ca(BF ₄ ) ₂ , Mg(TFSI) ₂ , Mg(NO ₃ ) ₂ , Mg(PF ₆ )2, Mg(FSI) ₂ , Mg(AsF ₆ ) ₂ , Mg It is at least one selected from the group consisting of (ClO ₄ ) ₂ and Mg(BF ₄ ) ₂ . Here, TFSI represents bis(trifluoromethanesulfonyl)imide, and FSI represents bisfluorosulfonylimide.

TFSI FSI

Meaning that one or more of the metal salts containing a Group 1 element or a Group 2 element and the nitrogen-containing additive are insoluble in the organic solvent of the liquid electrolyte, for example, "the solubility of the nitrogen-containing additive in the organic solvent of the liquid electrolyte at 25° C. is This means that it is less than 100 parts per million (ppm) per liter of organic solvent in the electrolyte.

Lithium metal anodes have a large electrical capacity per unit weight, making it possible to create high-capacity batteries using them. However, in the case of a lithium metal anode, a dendrite structure is formed and grows during the deposition/dissolution process of lithium ions, which may cause a short circuit between the anode and the cathode. Additionally, the lithium metal anode has high reactivity to the electrolyte, which may cause side reactions with the electrolyte, which may reduce the cycle life of the battery. In addition, as the charging and discharging of a lithium metal battery is repeated, changes in battery volume and thickness occur, and these changes cause lithium desorption from the anode. To compensate for this, a protective film that can complement the surface of the lithium metal anode is required.

In a lithium metal battery with a lithium metal cathode, a method of adding an additive such as cesium salt to the liquid electrolyte or using a polymer electrolyte as a cathode protective film has been proposed to suppress the growth of lithium dendrites.

However, when additives such as cesium salt are added to the liquid electrolyte, the cesium salt does not dissolve in the liquid electrolyte, making it difficult to apply it to an actual battery system. Cesium salts impede the movement of lithium ions or participate in electrochemical reactions at the anode, thereby reducing cell performance.

Additionally, when a lithium metal cathode protective film is used, the interfacial resistance between the protective film and the lithium anode increases due to the polymer electrolyte, which may deteriorate the cell performance of the lithium metal battery.

Accordingly, in order to solve the above-mentioned problem, the present inventors, after much research, placed a protective film containing at least one selected from i) a polymer and ii) a metal salt containing a group 1 or 2 element and a nitrogen-containing additive on the surface of a lithium metal anode. Provides a lithium metal battery.

At least one selected from the metal salt containing the Group 1 or Group 2 element and the nitrogen-containing additive is insoluble in the organic solvent of the liquid electrolyte. For example, at 25°C, the solubility of the nitrogen-containing additive in the organic solvent of the liquid electrolyte is less than 100 parts per million per liter (ppm/L) per liter of the organic solvent of the liquid electrolyte, for example, less than 75 ppm/L, specifically 50 ppm. It is /L.

Due to these solubility characteristics, it is limited to the surface of the lithium metal cathode and exists stably, and the mobility of one or more selected from metal salts and nitrogen-containing additives containing the Group 1 or 2 elements is limited, so when a protective film containing them is adopted, lithium ions between electrodes does not impede the movement of

In addition, the metal salt containing the Group 1 or 2 element has a larger atomic size than lithium, so when it is included in the protective film, lithium dendrites are formed on the surface of the lithium metal cathode due to the steric hindrance effect of the metal. can inhibit growth. In addition, the metal cation (e.g., Cs or rubidium ion) of the metal salt has an effective reduction potential that is smaller than that of lithium ions, so the metal salt is reduced or applied during the lithium deposition process. Without processing, metal cations form a positive electrostatic shield around the initial growth tips of protuberances on the surface of the lithium metal cathode. When this positive electrostatic shield is formed, the growth of lithium dendrites on the surface of the lithium metal cathode can be effectively suppressed. As described above, the content of the metal salt is important for the metal salt to have an effective reduction potential that is smaller than that of lithium. The content of the metal salt is controlled in the range of 0.1 to 100 parts by weight based on 100 parts by weight of the polymer of the protective film.

In addition, the protective film has excellent mechanical strength and flexibility, so it is very effective in suppressing the formation of lithium dendrites and forms an ion conductive film with high ion conductivity between the lithium metal anode and the protective film. The ion conductive film reduces the interfacial resistance between the lithium metal anode and the protective film by increasing the ionic conductivity and lithium ion mobility of the protective film. The ion-conducting coating contains, for example, lithium nitride (Li ₃ N).

In addition, the protective film improves the electrodeposition morphology of the lithium metal anode compared to the case of forming a conventional protective film by chemically improving the lithium deposition/desorption process, thereby increasing the electrodeposition density on the surface of the lithium metal anode. Improves ion mobility. And, as described above, at least one selected from the metal salt and nitrogen-containing additive is present to be confined to the protective film on the surface of the lithium metal negative electrode, so that the one or more selected from the metal salt and nitrogen-containing additive is dispersed in the liquid electrolyte or approaches the anode to form a contact with the anode. It can block the reaction from occurring. As a result, a lithium metal battery with improved rate performance and lifespan can be manufactured.

Nitrogen-containing additives contained in the protective film include, but are not limited to, inorganic nitrate, organic nitrate, inorganic nitrite, organic nitrite, organic nitro compound, and organic nitrate. One or more selected from the group consisting of nitroso compounds (organic nitroso compounds), NO compounds, and lithium nitride (Li ₃ N).

The inorganic nitrate is, for example, one or more selected from the group consisting of lithium nitrate, potassium nitrate, cesium nitrate, barium nitrate, and ammonium nitrate, and the organic nitrate is, for example, a C1 to C20 dialkyl nitrate. It is one or more selected from the group consisting of dazolium nitrate, guanidine nitrate, ethyl nitrite, propyl nitrite, butyl nitrite, pentyl nitrite, and octyl nitrite. And the organic nitrite is, for example, one or more selected from the group consisting of ethyl nitrite, propyl nitrite, butyl nitrite, pentyl nitrite, and octyl nitrite.

The organic nitro compound may include, for example, one or more selected from the group consisting of nitromethane, nitropropane, nitrobutane, nitrobenzene, dinitrobenzene, nitrotoluene, dinitrotoluene, and nitropyridine. And the N-O compound is, for example, one or more selected from the group consisting of pyridine N-oxide, C1 to C20 alkylpyridine N-oxide, and tetramethyl piperidine N-oxyl (TEMPO).

In the protective film according to another embodiment, the nitrogen-containing additive is at least one selected from LiNO ₃ and Li ₃ N, and the metal salt containing the Group 1 or 2 element is cesium bistrifluoromethylsulfonylimide (CsTFSI), It may be one or more selected from CsNO ₃ , CsPF ₆ , CsFSI, CsAsF ₆ , CsClO ₄ , and CsBF ₄ , for example, CsTFSI.

In the protective film, the content of at least one selected from a metal salt containing a group 1 or 2 element and a nitrogen-containing additive is 0.1 to 100 parts by weight, for example, 0.1 to 30 parts by weight, based on 100 parts by weight of the polymer. When the content of one or more selected from metal salts containing Group 1 or 2 elements and nitrogen-containing additives is within the above range, the effect of suppressing the growth of lithium dendrite, the interfacial resistance of the surface of the lithium metal cathode and the protective film is reduced, and the ion mobility of lithium is reduced. An improved lithium metal battery can be produced.

According to one embodiment, the protective film may include only a metal salt containing a Group 1 or Group 2 element. At this time, the content of the metal salt containing a group 1 or 2 element is 0.1 to 100 parts by weight, for example, 0.1 to 30 parts by weight, based on 100 parts by weight of the polymer.

According to another embodiment, the protective film may contain only nitrogen-containing additives. At this time, the content of the nitrogen-containing additive is 0.1 to 100 parts by weight, for example, 0.1 to 30 parts by weight, specifically 1 to 30 parts by weight, based on 100 parts by weight of the polymer.

The protective film may contain, for example, both a metal salt containing a Group 1 or Group 2 element and a nitrogen-containing additive. At this time, the content of the metal salt containing a Group 1 or Group 2 element is 0.01 to 99.99 parts by weight, for example, 0.1 to 30 parts by weight, for example, 1 to 30 parts by weight, based on 100 parts by weight of the polymer, and contains nitrogen. The content of the additive is 0.01 to 99.99 parts by weight, for example, 0.1 to 30 parts by weight, specifically 1 to 30 parts by weight, based on 100 parts by weight of the polymer.

In the protective film according to one embodiment, the mixing weight ratio of the metal salt containing a group 1 or 2 element and the nitrogen-containing additive is 1:9 to 9:1, for example, 1:2 to 2:1, specifically 1:1. . When the mixing weight ratio of the metal salt containing a group 1 or 2 element and the nitrogen-containing additive is in the above range, the electrodeposition density on the surface of the lithium metal anode and the lithium ion mobility characteristics in the electrolyte are excellent, resulting in the rate performance and lifespan characteristics of the lithium metal battery. This is improved.

The protective film contains polymers. The polymer may include one or more polymers selected from homopolymers, block copolymers, and graft copolymers, or mixtures thereof. For example, the polymer may have the characteristic of being insoluble in the organic solvent of the liquid electrolyte. Using a polymer with these characteristics provides excellent chemical resistance to liquid electrolytes containing carbonate-based organic solvents, unlike conventional polyethylene-based protective films. In addition, the effect of suppressing short circuits inside the battery due to cracks in the protective film is very excellent.

The polymers include polyvinyl alcohol, polymethyl methacrylate, polymethyl acrylate, polyethyl methacrylate, polyethyl acrylate, polypropyl methacrylate, polypropyl acrylate, polybutyl acrylate, and polybutyl methacrylate. , polypentyl methacrylate, polypentyl acrylate, polycyclohexyl methacrylate, polycyclohexyl acrylate, polyhexyl methacrylate, polyhexyl acrylate, polyglycidyl acrylate, polyglycidyl methacrylate and polyacrylonitrile.

The polymer contained in the protective film is a block copolymer containing a first polymer block and a second polymer block. The first polymer block is polystyrene, hydrogenated polystyrene, polymethacrylate, poly(methyl methacrylate), polyvinylpyridine, polyvinylcyclohexane, polyimide, polyamide, polyethylene, polybutylene, polypropylene, poly( 4-methyl-1-pentene), poly(butylene terephthalate), poly(isobutyl methacrylate), poly(ethylene terephthalate), polydimethylsiloxane, polyacrylonitrile, polymaleic acid, polymaleic anhydride , polymethacrylic acid, poly(tertbutyl vinyl ether), poly(cyclohexyl methacrylate), poly(cyclohexyl vinyl ether), polyvinylidene fluoride, polydivinylbenzene, or one or more of the above-mentioned polymers. It is a polymer that contains two or more types of repeating units.

The second polymer block is polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyethyl methacrylate, polydimethylsiloxane, polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polyethyl acrylate, poly 2-ethyl Hexyl acrylate, polybutyl methacrylate, poly2-ethylhexyl methacrylate, polydecyl acrylate and polyethylene vinyl acetate, polyimide, polyamine, polyamide, poly(C1-C20 alkylcarbonate), polynitrile, polyphosphide. It may be one or more selected from the group consisting of polyphosphazines, polyolefins, polydienes, polyisoprene, polybutadiene, polychloroprene, polyurethane, polyethylene, polybutylene, polyisobutylene, and polypropylene. First The polymer block is the region related to the mechanical properties of block copolymers. The second polymer block is the region associated with the ionic conductivity, strength, and/or ductility of the block copolymer.

The block copolymer has i) a structural domain; and ii) a block copolymer containing one or more selected from the group consisting of an ion conductive domain, a rubber domain, and a hard domain. This block copolymer has excellent strength and flexibility, and has an excellent ability to physically inhibit the growth of lithium dendrites on the surface of the lithium metal anode. In this specification, “structural domain” is a region related to the mechanical properties of a block copolymer. And in this specification, the “ion conductive domain” is a region related to the ionic conductivity of the block copolymer, and the “hard domain” is a region that contributes to the block copolymer exhibiting high mechanical strength, has hydrophobicity and crystallinity, and is a liquid electrolyte. It can support the protective film and retains the characteristics of a separator. And the “rubber domain” simultaneously secures the excellent strength, ductility, and elasticity of the block copolymer and has excellent stability against liquid electrolytes containing carbonate-based organic solvents.

In the block copolymer, the structural domain includes a first polymer block of the block copolymer, and at least one selected from an ion conductive domain, a rubber domain, and a hard domain is i) an ion conductive block, and ii) a rubber phase of the block copolymer. block and iii) one or more second polymer blocks selected from hard blocks. And the first polymer block includes a plurality of structural repeating units, and the second polymer block includes one or more selected from a plurality of ion conductive repeating units, a plurality of rubber-like repeating units, and a plurality of olefinic repeating units. The ion conductive block is polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyethyl methacrylate, polydimethylsiloxane, polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polyethyl acrylate, poly 2-ethyl Hexyl acrylate, polybutyl methacrylate, poly2-ethylhexyl methacrylate, polydecyl acrylate and polyethylene vinyl acetate, polyimide, polyamine, polyamide, poly(C1-C20 alkylcarbonate), polynitrile, and poly It may be one or more selected from the group consisting of phosphazines.

In the block copolymer according to one embodiment, the rubber block is at least one selected from the group consisting of polyisoprene, polybutadiene, polychloroprene, polyisobutylene, and polyurethane, and the hard block is polyethylene, polybutylene, and polyisobutyl. It is at least one selected from the group consisting of lene and polypropylene.

The weight average molecular weight of the first polymer block of the block copolymer according to one embodiment is 10,000 Daltons or more, for example, 10,000 to 500,000 Daltons, specifically 15,000 to 400,000 Daltons. And the weight average molecular weight of the second polymer block is 10,000 Daltons or more, for example, 10,000 to 500,000 Daltons, specifically 15,000 to 400,000 Daltons. By using a block copolymer containing a first polymer block and a second polymer block having such a weight average molecular weight, a protective film with excellent ductility, elasticity, and strength can be obtained.

The content of the first polymer block in the block copolymer is 20 to 50 parts by weight, for example, 22 to 30 parts by weight, specifically 25 to 30 parts by weight, based on 100 parts by weight of the total weight of the block copolymer. Using this first polymer block, a protective film with excellent mechanical properties such as strength can be obtained.

The block copolymer according to one embodiment is at least one selected from a diblock copolymer (A-B) and a triblock copolymer (A-B-A' or B-A-B'), and the blocks A and A' are a plurality of blocks constituting the structural domain. It is the first polymer block, and blocks B and B' are the second polymer blocks.

When the polymer contained in the protective film is a block copolymer, for example, i) a first block of polystyrene and ii) a block copolymer containing at least one second block selected from polyisoprene and polybutadiene, i) a first block of polystyrene and ii) ) a block copolymer comprising at least one second block selected from polyisoprene and polybutadiene and iii) a third block of polystyrene; i) a block copolymer comprising at least one first block selected from polystyrene and polymethyl methacrylate and ii) at least one second block selected from polyethylene and polybutylene, i) one selected from polystyrene and polymethyl methacrylate A block copolymer comprising the above first block, ii) at least one second block selected from polyethylene and polybutylene, and iii) at least one third block selected from polystyrene and polymethyl methacrylate; A block copolymer containing i) a first polystyrene block and ii) (a second block containing polyethylene oxide and a reaction product selected from polyethylene glycol diacrylate and polyethylene glycol dimethacrylate); A block containing i) a first block of polystyrene, ii) (a second block comprising polyethylene oxide and a reaction product selected from polyethylene glycol diacrylate and polyethylene glycol dimethacrylate) and iii) a third block of polystyrene. coalescence; A block copolymer containing i) a first block of polystyrene and ii) (a second block containing polyethylene oxide and a reaction product selected from trimethylolpropane triacrylate and trimethylolpropane trimethacrylate); Containing i) a first polystyrene block and ii) (a second block containing polyethylene oxide and a reaction product selected from trimethylolpropane triacrylate and trimethylolpropane trimethacrylate) and iii) a third polystyrene block. block copolymer; Contains i) a first polystyrene block and ii) (a second block containing polyethylene oxide and a reaction product of one selected from polyethylene glycol diacrylate and polyethylene glycol dimethacrylate and POSS (polyhedral oligomeric silsesquioxane) having an acrylic group) A block copolymer comprising: i) a first polystyrene block and ii) (a second block containing a reaction product of one selected from polyethylene glycol diacrylate and polyethylene glycol dimethacrylate with POSS having an acrylic group and polyethylene oxide) and iii) ) Block copolymer containing polystyrene third block; A block containing i) a first block of polystyrene and ii) (a second block containing a reaction product of one selected from trimethylolpropane triacrylate and trimethylolpropane trimethacrylate with POSS having an acrylic group and polyethylene oxide). coalescence; or i) a first polystyrene block and ii) (a second block containing a reaction product of one selected from trimethylolpropane triacrylate and trimethylolpropane trimethacrylate with POSS having an acrylic group and polyethylene oxide) and iii) polystyrene. It includes a block copolymer containing a third block.

In the block copolymer containing the above-described first block, second block, and third block, the total content of the first block and third block is 20 to 35 parts by weight, for example, based on 100 parts by weight of the total weight of the block copolymer. For example, 22 to 30 parts by weight, specifically 25 to 30 parts by weight, and the content of the second block is 65 to 80 parts by weight, for example, 70 to 78 parts by weight, specifically 72 to 72 parts by weight, based on 100 parts by weight of the block copolymer. It is 75 parts by weight. In the above-described block copolymer, the mixing weight ratio of the first polymer block and the second polymer block is 1:1 to 1:9, for example, 1:1 to 1:7, specifically 1:1 to 1:4. When the mixing ratio is in the above range, the mechanical properties of the protective film are excellent without deteriorating the ductility and tensile modulus of the protective film, and lithium dendrite growth can be effectively suppressed.

According to another embodiment, the block copolymer includes one or more first blocks selected from polystyrene, polymethyl methacrylate, and polyacrylonitrile, and one or more second blocks selected from polyisoprene, polyethylene, and polybutylene.

According to another embodiment, the block copolymer includes at least one first block selected from polystyrene, polymethyl methacrylate, and polyacrylonitrile, and at least one second block selected from polyethylene oxide and polysiloxane.

Block copolymers include, for example, polystyrene-b-polyisoprene-polystyrene block copolymers.

The weight average molecular weight of the block copolymer contained in the protective film according to one embodiment may range from 10,000 to 500,000 daltons.

In a lithium metal battery according to one embodiment, the liquid electrolyte contains lithium salt and an organic solvent. Here, the organic solvent includes carbonate-based compounds, glyme-based compounds, and dioxolane-based compounds. Carbonate-based compounds include ethylene carbonate, propylene carbonate, dimethyl carbonate, fluoroethylene carbonate, diethyl carbonate, or ethylmethyl carbonate. The glyme-based compounds include poly(ethylene glycol) dimethyl ether, tetra(ethylene glycol) dimethyl ether, tri(ethylene glycol) dimethyl ether, poly(ethylene glycol) dilaurate, poly(ethylene glycol) monoacrylate, and poly(ethylene). There is at least one type selected from glycol) diacrylate.

Examples of dioxolane compounds include 3-dioxolane, 4,5-diethyl-dioxolane, 4,5-dimethyl-dioxolane, 4-methyl-1,3-dioxolane, and 4-ethyl There is at least one selected from the group consisting of -1,3-dioxolane. The organic solvent is, for example, 2,2-dimethoxy-2-phenylacetophenone, 1,2-dimethoxyethane (DME), 1,2-diethoxyethane, tetrahydrofuran, gammabutyrolactone, and 1 ,1,2,2-Tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (1,1,2,2-Tetrafluoroethyl 2,2,3,3-tetrafluoropropyl There is one or more selected from ether).

Organic solvents of the liquid electrolyte include, for example, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, fluoroethylene carbonate, 1,2-dimethoxy ethane, 1,2-diethoxyethane, dimethylene glycol dimethyl ether, Trimethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, succinonitrile, sulfolane, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, adiponitrile, and 1, It includes one or more selected from 1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether. The polymer contained in the protective film according to one embodiment is insoluble in the above-mentioned organic solvent.

Lithium salts are for example LiSCN, LiN(CN) ₂ , LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , LiC(CF ₃ SO ₂ ) ₃ , LiN(SO ₂ C ₂ F ₅ ) ₂ , LiN(SO ₂ CF ₃ ) ₂ , LiN(SO ₂ F) ₂ , LiAlO ₂ , LiAlCl ₄ , LiCl, LiI, LiSbF ₆ , LiPF ₃ (CF ₂ CF ₃ ) ₃ , LiPF ₃ (CF ₃ ) ₃ , and One or more selected from LiB(C ₂ O ₄ ) ₂ may be mentioned. The content of lithium salt in the liquid electrolyte may be, for example, 0.01 to 2.0 M.

The protective film may further include one or more selected from inorganic particles, ionic liquid, polymer ionic liquid, and oligomer.

The protective film may further include a lithium salt. The content of the lithium salt is 10 to 70 parts by weight, for example, 15 to 60 parts by weight, specifically 20 to 50 parts by weight, based on 100 parts by weight of the polymer of the protective film. When the lithium salt content is within the above range, the ionic conductivity of the protective film is very excellent.

The elongation of the protective film according to one embodiment is 500% or more, for example, 600% or more, specifically 1000 to 1500% at 25°C. A protective film that satisfies this elongation has excellent ductility and can suppress the growth of dendrites on the surface of lithium metal and efficiently suppress changes in the volume of the lithium metal anode.

As inorganic particles, one or more types selected from SiO ₂ , cage-structured silsesquioxane, TiO ₂ , ZnO, Al ₂ O ₃ , BaTiO ₃ , and metal-organic framework (MOF) can be used. there is. In this way, by further including inorganic particles, a protective film with improved mechanical properties can be manufactured. The average particle diameter of the inorganic particles may be 1 μm or less, for example, 1 to 500 nm, specifically 1 to 100 nm or less. For example, the particle size of the inorganic particles may be 1 nm to 100 nm, for example, 10 nm to 100 nm, specifically 30 nm to 70 nm. When the particle size of the inorganic particles is within the above range, a protective film with excellent film forming properties and excellent mechanical properties can be manufactured without reducing ionic conductivity.

The cage-structured silsesquioxane may be, for example, polyhedral oligomeric silsesquioxane (POSS). In this POSS, there are no more than 8 pieces of silicon, for example, 6 or 8 pieces. Cage-structured silsesquioxane may be a compound represented by the following formula (1).

[Formula 1]

Si _k O _1.5k (R ¹ ) _a (R ² _{) b (} R ³ ) _c

In Formula 1 above, R ¹ , R ² , and R ³ are independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, or a substituted or unsubstituted C2-C30 alkyl group. Alkenyl group, substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted C2 It may be a -C30 heteroaryl group, a substituted or unsubstituted C4-C30 carbon ring group, or a silicon-containing functional group.

In Formula 1, 0<a<20, 0<b<20, 0<c<20, k=a+b+c, provided that a, b, and c are selected to be in the range of 6≤k≤20.

Cage-structured silsesquioxane may be a compound represented by Formula 2 below or a compound represented by Formula 3 below.

[Formula 2]

In Formula 2, R _1- R ₈ are independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, or a substituted or unsubstituted C2-C30 alkenyl group, substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted It may be a C2-C30 heteroaryl group, a substituted or unsubstituted C4-C30 carbon ring group, or a silicon-containing functional group.

[Formula 3]

In Formula 3, R ₁ -R ₆ are independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, or a substituted or unsubstituted C2-C30 alkenyl group, substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted It may be a C2-C30 heteroaryl group, a substituted or unsubstituted C4-C30 carbon ring group, or a silicon-containing functional group.

According to one embodiment, R _1- R ₈ in Formula 2 and R _1- R ₆ in Formula 3 are isobutyl groups. For example, the cage-structured silsesquioxane may be, for example, octisobutyl-t8-silsesquioxane.

When the protective film contains inorganic particles, the content of the inorganic particles is 1 to 40 parts by weight, for example, 3 to 30 parts by weight, specifically 5 to 20 parts by weight, based on 100 parts by weight of the polymer. When the content of inorganic particles is within the above range, a protective film with excellent mechanical properties and ionic conductivity can be manufactured.

The metal-organic framework structure is a porous crystalline compound formed by chemical bonds between group 2 to 15 metal ions or group 2 to 15 metal ion clusters with organic ligands. Organic ligand refers to an organic group capable of chemical bonding such as a coordination bond, ionic bond, or covalent bond. For example, an organic group that has two or more sites that can bind to the metal ion described above is stable by combining with a metal ion. A structure can be formed.

The Group 2 to Group 15 metal ions include cobalt (Co), nickel (Ni), molybdenum (Mo), tungsten (W), ruthenium (Ru), osmium (Os), cadmium (Cd), beryllium (Be), Calcium (Ca), Barium (Ba), Strondium (Sr), Iron (Fe), Manganese (Mn), Chromium (Cr), Vanadium (V), Aluminum (Al), Titanium (Ti), Zirconium (Zr) ), copper (Cu), zinc (Zn), magnesium (Mg), hafnium (Hf), Nb, tantalum (Ta), Re, rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt) , silver (Ag), scandium (Sc), yttrium (Y), indium (In), thallium (Tl), silicon (Si), Ge, tin (Sn), lead (Pb), arsenic (As), antimony ( Sb), at least one selected from bismuth (Bi), and the organic ligand is aromatic dicarboxylic acid, aromatic tricarboxylic acid, imidazole-based compound, tetrazole-based compound, 1,2,3-triazole, 1,2, 4-triazole, pyrazole, aromatic sulfonic acid, aromatic phosphoric acid, aromatic sulfinic acid, aromatic phosphinic acid, bipyridine, amino group, imino group, amide group, dithi It is a group derived from one or more compounds having one or more functional groups selected from the group consisting of ocarboxylic acid group (-CS ₂ H), dithiocarboxylate (-CS ₂ ^- ), pyridine group, and pyrazine group.

Examples of the above-mentioned aromatic dicarboxylic acid or aromatic tricarboxylic acid include benzenedicarboxylic acid, benzenedicarboxylic acid, biphenyldicarboxylic acid, and terphenyldicarboxylic acid.

The above-mentioned organic ligand may be a group derived from a compound specifically represented by the following formula (4).

[Formula 4]

Metal-organic framework structures are, for example, Ti ₈ O ₈ (OH) ₄ [O ₂ CC ₆ H ₄ -CO ₂ ] _6, Cu (bpy)(H ₂ O) ₂ (BF ₄ ) ₂ (bpy){bpy = 4, 4'-bipyridine}, Zn ₄ O(O ₂ CC ₆ H ₄ -CO ₂ ) ₃ (Zn-terephthalic acid-MOF, Zn-MOF) or Al(OH){O ₂ CC ₆ H ₄ -CO ₂ } can be mentioned.

The ionic liquid refers to a salt in a liquid state at room temperature or a room temperature molten salt that has a melting point below room temperature and consists only of ions. Ionic liquids include i) ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, and triazolium-based At least one cation selected from the triazolium system and mixtures thereof, ii) BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , ClO ₄ ^- , CH ₃ SO ₃ ^- , CF ₃ CO ₂ ^- , Cl ^- , Br ^- , I ^- , SO ₄ ^2- , CF ₃ SO ₃ ^- , (FSO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ )(CF ₃ SO ₂ )N ^- , and (CF ₃ SO ₂ ) ₂ N ^- It is one selected from compounds containing one or more anions selected from among.

Inorganic particles can have various forms. Inorganic particles may have, for example, spherical, oval, cubic, cubic, tetrahedral, pyramidal, octahedral, cylindrical, or polygonal shapes. polygonal pillar-like shape, conical shape, columnar shape, tubular shape, helical shape, funnel shape, dendrite shape, etc. It can have a variety of common regular shapes or irregular shapes.

Ionic liquids include, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide, N-butyl-N-methyl Pyrrolidium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-ethyl-3-methylimidazolium bis. It is at least one selected from the group consisting of (trifluoromethylsulfonyl)imide. The content of the ionic liquid is 5 to 40 parts by weight, for example, 7 to 30 parts by weight, specifically 10 to 20 parts by weight, based on 100 parts by weight of the polymer contained in the protective film. When the content of the ionic liquid is within the above range, a protective film with excellent ionic conductivity and mechanical properties can be obtained.

When the protective film contains an ionic liquid and a lithium salt, the molar ratio of ionic liquid (IL)/lithium ion (Li) (IL/Li) is 0.1 to 2.0, for example 0.2 to 1.8, specifically 0.4 to 1.5 days. You can. A protective film having such a molar ratio not only has excellent lithium ion mobility and ion conductivity, but also has excellent mechanical properties and can effectively suppress lithium dendrite growth on the surface of the lithium metal anode.

The polymer ionic liquid can be obtained by polymerizing ionic liquid monomers, or a compound obtained in polymer form can be used. These polymer ionic liquids have high solubility in organic solvents and have the advantage of further improving ionic conductivity when added to electrolytes.

When obtaining a high-molecular ionic liquid by polymerizing the above-mentioned ionic liquid monomer, the polymerization reaction product is washed and dried, and then manufactured to have an appropriate anion that can provide solubility in an organic solvent through an anion substitution reaction. do.

The polymer ionic liquid according to one embodiment is i) ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phospho At least one cation selected from nium-based, sulfonium-based, triazolium-based and mixtures thereof, and ii) BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , ClO ₄ ^- , CH ₃ SO ₃ ^- , CF ₃ CO ₂ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (FSO ₂ ) ₂ N ^- , Cl ^- , Br ^- , I ^- , CF ₃ SO ₃ ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ )(CF ₃ SO ₂ )N ^- , NO ₃ ^- , Al ₂ Cl ₇ ^- , (CF ₃ SO ₂ ) ₃ C ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , SF ₅ CF ₂ SO ₃ ^- , SF ₅ CHFCF ₂ SO ₃ ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , (O(CF ₃ ) ₂ C ₂ (CF ₃ ) ₂ O) ₂ PO ^- It may contain a repeating unit containing one or more anions selected from among.

According to another embodiment, the ionic liquid monomer has a polymerizable functional group such as a vinyl group, an allyl group, an acrylate group, a methacrylate group, etc., and an ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, It may have one or more cations selected from imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, triazolium-based and mixtures thereof, and the anions described above.

Examples of the ionic liquid monomer include 1-vinyl-3-ethylimidazolium bromide and compounds represented by the following formula (5) or (6).

[Formula 5]

[Formula 6]

Examples of the above-mentioned polymer ionic liquid include a compound represented by the following formula (7) or a compound represented by the formula (8).

[Formula 7]

In Formula 7, R ₁ and R ₃ are independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, or a substituted or unsubstituted C2-C30 An alkynyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C2-C30 heteroaryl group, or a substituted or unsubstituted C4-C30 carbocyclic group. In Formula 10, R ₂ simply represents a chemical bond or a C1-C3 alkylene group, a C6-C30 arylene group, a C2-C30 heteroarylene group, or a C4-C30 carbon ring group,

X ^- represents the anion of the ionic liquid,

n is 500 to 2800.

[Formula 8]

In Formula 8, Y ^- is defined the same as X ^- in Formula 7,

n is 500 to 2800.

Y ^- in Formula 8 is, for example, bis(trifluoromethylsulfonyl)imide (TFSI), bis(fluorosulfonyl)imide, BF ₄ , or CF ₃ SO ₃ .

Polymeric ionic liquids include, for example, poly(1-vinyl-3-alkylimidazolium), where alkyl is a C1-C20 alkyl group, poly(1-allyl-3-alkylimidazolium), poly(1 - A cation selected from poly(1-methacryloyloxy-3-alkylimidazolium), CH ₃ COO ^- , CF ₃ COO ^- , CH ₃ SO ₃ ^- , CF ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (FSO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₃ C ^- , (CF ₃ CF ₂ SO ₂ ) ₂ N ^- , C ₄ F ₉ SO ₃ ^- , It includes an anion selected from C ₃ F ₇ COO ^- and (CF ₃ SO ₂ )(CF ₃ CO)N ^- .

The compound represented by Formula 8 includes polydiallyldimethylammonium bis(trifluoromethylsulfonyl)imide.

According to another embodiment, the polymer ionic liquid may include a low molecular weight polymer, a thermally stable ionic liquid, and a lithium salt. Low molecular weight polymers may have ethylene oxide chains. Low molecular weight polymers may be glymes. Here, the glyme includes, for example, polyethylene glycol dimethyl ether (polyglyme), tetraethylene glycol dimethyl ether (tetraglyme), and triethylene glycol dimethyl ether (triglyme).

The weight average molecular weight of the low molecular weight polymer is 75 to 2000, for example 250 to 500. And the thermally stable ionic liquid is as defined in the above-mentioned ionic liquid.

The oligomer is at least one selected from the group consisting of polyethylene glycol dimethyl ether and polyethylene glycol diethyl ether. The weight average molecular weight of the oligomer is 200 to 2,000, and the content of the oligomer is 5 to 50 parts by weight, for example, 3 to 30 parts by weight, specifically 5 to 25 parts by weight, based on 100 parts by weight of the polymer. When oligomers are added in this way, the protective film has better film forming properties, mechanical properties, and ionic conductivity properties.

^{The ionic} conductivity of the protective film ^may be 1 The tensile modulus of the protective film is 10 MPa or more, for example, 10 to 80 MPa, specifically 10 to 50 MPa at about 25°C. And the elongation of the protective film is 500% or more, for example, 600% or more, specifically 1200% or more or 1300% at about 25°C. The protective film can simultaneously secure mechanical properties such as ductility and elasticity necessary for battery performance and ionic conductivity even at 25°C. When the elongation of the protective film is within the above range, the function of suppressing the volume change of the lithium metal anode is excellent. If the elongation of the protective film is less than the above range, there is a high possibility that the area attacked by the dendrites formed on the surface of the lithium metal anode will break and form a short. The protective film according to one embodiment has the above-described tensile modulus and ductility, thereby suppressing changes in cathode volume and thereby effectively suppressing dendrite growth.

The protective film according to one embodiment has a tensile strength of 2.0 at 25°C.

It is more than MPa. And the interfacial resistance between lithium metal and the protective film derived from the Nyquist plot obtained from impedance measurement decreases by more than 10% at 25 ° C. compared to bare lithium metal. In this way, when the protective film according to one embodiment is used, the interfacial resistance is reduced compared to the case of lithium metal alone, and the interfacial characteristics are excellent. Additionally, the protective film has an oxidation current or reduction current of 0.05 mA/cm ² or less in a voltage range of 0.0 Volts (V) to 6.0 V compared to lithium metal.

In a lithium metal battery according to one embodiment, the lithium deposition density on the surface of the lithium metal anode is 0.2 to 0.4 grams per cubic centimeter (g/cc), for example, 0.26 to 0.32 g/cc.

Figures 1 and 2 show the structure of a lithium metal battery according to an embodiment.

Referring to FIG. 1, a protective film 11 according to one embodiment is formed on the lithium metal anode 10, and a liquid electrolyte 12 is disposed between the protective film 11 and the anode 13. It contains at least one (14) selected from a metal salt containing a Group 1 or Group 2 element contained in the protective film (11) and a nitrogen-containing additive, and this material has the property of being insoluble in the organic solvent of the liquid electrolyte (12). One or more (14) selected from metal salts containing Group 1 or Group 2 elements and nitrogen-containing additives may be present in the area adjacent to the lithium metal anode 10 in the protective film 11, as shown in FIG. 1. According to another embodiment, at least one (14) selected from metal salts containing Group 1 or Group 2 elements and nitrogen-containing additives is distributed throughout the protective film, and its content increases toward the area close to the lithium metal anode (10). You can. In Figure 1, one or more (14) selected from metal salts containing Group 1 or Group 2 elements and nitrogen-containing additives are shown to be present in a position adjacent to the lithium metal anode (10), but this means that it is limited to only these positions. That is not the case.

Referring to FIG. 2, a protective film 21 is formed on the lithium metal anode 20. The upper part of the protective film 21 may have a two-layer structure in which a liquid electrolyte (22a) and a solid electrolyte (22b) are sequentially stacked. The liquid electrolyte 22a may be disposed adjacent to the protective film 21 as shown in FIG. 2, but the stacking order of the liquid electrolyte and the solid electrolyte may be changed. And an anode 23 is disposed on top of the solid electrolyte 22b. The electrolyte 22 consists of a liquid electrolyte 22a and a solid electrolyte 22b.

A gel electrolyte may be used instead of the solid electrolyte 22b in FIG. 2.

The lithium metal battery according to one embodiment may further include a separator. The separator may be polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof, such as a polyethylene/polypropylene two-layer separator, a polyethylene/polypropylene/polyethylene three-layer separator, or a polypropylene/polyethylene/polypropylene separator. A mixed multilayer film such as a three-layer separator may be used. An electrolyte containing lithium salt and an organic solvent may be further added to the separator.

The anodes 13 and 23 in FIGS. 1 and 2 may be porous anodes. A porous anode also includes an anode that contains pores or does not intentionally exclude the formation of an anode and thus allows a liquid electrolyte to penetrate into the anode due to capillary action or the like.

For example, a porous positive electrode includes a positive electrode obtained by coating and drying a positive electrode active material composition including a positive electrode active material, a conductive agent, a binder, and a solvent. The positive electrode obtained in this way may contain pores existing between positive electrode active material particles. This porous anode may be impregnated with a liquid electrolyte.

According to another embodiment, the positive electrode may further include a liquid electrolyte, a gel electrolyte, or a solid electrolyte. Liquid electrolytes, gel electrolytes, and solid electrolytes can be used as electrolytes for lithium metal batteries in the art, as long as they do not react with the positive electrode active material and deteriorate it during the charging and discharging process.

The protective film according to one embodiment is suitable as a protective film for a high-voltage lithium metal battery.

Here, “high voltage” refers to the case where the charging voltage is in the range of 4.0V to 5.5V.

Hereinafter, we will look at a manufacturing method of a lithium metal battery according to an embodiment.

A composition for forming a protective film is obtained by mixing a polymer, a metal salt containing a Group 1 or Group 2 element, at least one selected from nitrogen-containing additives, and an organic solvent. Next, the composition for forming a protective film is applied to the top of the lithium metal anode and dried to form a protective film on the lithium metal surface. Here, drying can be performed at, for example, 25 to 60°C.

The organic solvent may be any solvent commonly used in the art. For example, tetrahydrofuran, N-methylpyrrolidone, acetonitrile, benzonitrile, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N, N-dimethyl Formamide, N, N-dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, One or more selected from dimethyl ether may be used. The content of the organic solvent is, for example, 100 to 4,000 parts by weight, for example, 500 to 2,000 parts by weight, based on 100 parts by weight of the polymer.

One or more selected from inorganic particles, ionic liquid, polymer ionic liquid, and oligomer may be further added to the composition for forming a protective film.

Any method of applying the composition for forming a protective film described above can be used as long as it is a commonly used method for forming a protective film. For example, methods such as spin coating, roll coating, curtain coating, extrusion, casting, screen printing, inkjet printing, and doctor blade may be used.

The protective film prepared according to the above process may be electrochemically stable for lithium in a voltage range of 0V to 6.0V, for example, 2.0 to 5.0V, specifically 4.0V to 5.0V. The protective film according to one embodiment can be applied to an electrochemical device operating at high voltage by having a wide voltage window that is electrochemically stable.

The protective film has a current density of 0.05 mA/cm ² or less due to side reactions other than attachment/desorption of lithium near 0V, for example, 0.001 to 0.02 mA/cm ² , specifically 0.001 to 0.01 mA/cm ² day. You can. For example, the protective film has a current density due to oxidation reaction near 5.0V for lithium of 0.05 mA/cm ² or less, for example, 0.001 to 0.02 mA/cm ² mA/cm ² , for example, 0.001 to 0.04. mA/cm ² , specifically, may be 0.001 to 0.02 mA/cm ² .

The lithium metal battery according to one embodiment may be a mixed electrolyte type, further comprising at least one selected from a solid electrolyte, a gel electrolyte, and a polymer ionic liquid in addition to the liquid electrolyte. The lithium metal battery may further include a separator. As described above, if one or more selected from solid electrolytes and gel electrolytes are further included, the conductivity and mechanical properties of the protective film can be further improved.

The gel electrolyte is an electrolyte in a gel form and can be used as long as it is well known in the art. Gel electrolytes may contain, for example, polymers and polymeric ionic liquids. The polymer here may be, for example, a solid graft (block) copolymer electrolyte.

The solid electrolyte may be an organic solid electrolyte or an inorganic solid electrolyte.

Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociation groups, etc. can be used

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ - Li ₂ S-SiS ₂ , Cu ₃ N, LiPON, Li ₂ S.GeS ₂ .Ga ₂ S ₃ , Li ₂ O.11Al ₂ O ₃ , (Na,Li) _1+x Ti _2-x Al _x (PO ₄ ) ₃ (0.1≤x≤0.9), Li _{1 + x} Hf _{2 - x} Al _x (PO ₄ ) ₃ (0.1≤x≤0.9), Na ₃ Zr ₂ Si ₂ PO ₁₂ , Li ₃ Zr ₂ Si ₂ PO ₁₂ , Na ₅ ZrP ₃ O ₁₂ , Na ₅ TiP ₃ O ₁₂ , Na ₃ Fe ₂ P ₃ O ₁₂ , Na ₄ NbP ₃ O ₁₂ , Na-Silicates, Li _{0 . 3} La _{0 . 5} TiO ₃ , Na ₅ MSi ₄ O ₁₂ (M is a rare earth element such as Nd, Gd, Dy, etc.) Li ₅ ZrP ₃ O ₁₂ , Li ₅ TiP ₃ O ₁₂ , Li ₃ Fe ₂ P ₃ O ₁₂ , Li ₄ NbP ₃ O ₁₂ , Li _{1 + x} (M, Al,Ga) _x (Ge _1-y Ti _y ) _{2 -x} (PO ₄ ) ₃ (X≤0.8, 0≤Y≤1.0, M is Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), Li _{1 +x+ y} Q _x Ti _{2 - x} Si _y P _{3 - y} O ₁₂ (0<x≤0.4, 0<y≤0.6, Q is Al or Ga), Li ₆ BaLa ₂ Ta ₂ O ₁₂ , Li ₇ La ₃ Zr ₂ O ₁₂ , Li ₅ La ₃ Nb ₂ O ₁₂ , Li ₅ La ₃ M ₂ O ₁₂ (M is Nb, Ta), Li _{7 + x} A _x La _{3 - x} Zr ₂ O ₁₂ (0<x<3, A is Zn), etc. can be used.

The lithium metal negative electrode is a lithium metal thin film electrode or a lithium metal alloy electrode.

Lithium metal alloy refers to lithium, metals/metalloids that can be alloyed with lithium, alloys thereof, or metalloids capable of alloying with lithium.

It may contain oxides. For example, the metal/metalloid that can be alloyed with lithium, its alloy, or its oxide is Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y alloy (where Y is an alkali metal, alkaline earth metal, group 13 to Group 16 elements, transition metals, rare earth elements, or a combination thereof, but not Si), Sn-Y alloy (Y is an alkali metal, an alkaline earth metal, a Group 13 to Group 16 element, a transition metal, a rare earth element, or these It may be a combination element of , but not Sn), etc. The element Y includes Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, It may be Se, Te, Po, or a combination thereof.

The positive electrode active material for manufacturing the positive electrode may include, but is not necessarily limited to, one or more selected from the group consisting of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese oxide. All positive electrode active materials available in the art can be used.

For example, Li _a A _{1 - b} B _b D ₂ (in the above formula, 0.90≤a≤1.8, and 0≤b≤0.5); Li _a E _{1 -b B b} O _{2 -c} D _c (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiE _{2 - b} B _b O _{4 - c} D _c (in the above formula, 0≤b≤0.5, 0≤c≤0.05); Li _a Ni _{1 -b- c} Co _b B _c D _α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li _a Ni _{1 -b- c} Co _b B _c O _{2 - α} F _α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li _a Ni _{1 -b- c} Mn _b B _c D _α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - α} F _α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li _a Ni _b E _c G _d O ₂ (In the above formula, 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤ 0.1); Li _a Ni _b Co _c Mn _d GeO ₂ (In the above formula, 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1); Li _a NiG _b O ₂ (In the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li _a CoG _b O ₂ (In the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li _a MnG _b O ₂ (in the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li _a Mn ₂ G _b O ₄ (in the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); QO ₂ ; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiIO ₂ ; LiNiVO ₄ ; Li _(3-f) J ₂ (PO ₄ ) ₃ (0≤f≤2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0≤f≤2); A compound represented by any of the chemical formulas of LiFePO ₄ can be used.

In the above formula, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

For example, the positive electrode active material may be a compound represented by the following Chemical Formula 9, a compound represented by the following Chemical Formula 10, or a compound represented by the Chemical Formula 11.

[Formula 9]

Li _a Ni _b Co _c Mn _d O ₂

In Formula 9, 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5.

[Formula 10]

Li ₂ MnO ₃

[Formula 11]

LiMO ₂

In Formula 11, M is Mn, Fe, Co, or Ni.

An anode is prepared according to the following method.

A positive electrode active material composition is prepared by mixing a positive electrode active material, a binder, and a solvent.

A conductive agent may be further added to the positive electrode active material composition.

A positive electrode plate is manufactured by coating and drying the positive electrode active material composition directly on a metal current collector. Alternatively, the positive electrode active material composition may be cast on a separate support, and then the film peeled from the support may be laminated on a metal current collector to produce a positive electrode plate.

Current collectors include nickel, aluminum, titanium, copper, gold, silver, platinum, aluminum alloy or stainless steel, films obtained by plasma spraying or arc spraying of carbon-based materials, activated carbon fiber, nickel, aluminum, zinc, copper, A conductive film obtained by dispersing tin, lead, their alloys, or conductive materials in a resin or rubber such as styrene-ethylene-butylene-styrene copolymer (SEBS) is used. The current collector is, for example, aluminum, nickel, or stainless steel. Aluminum is suitable as a current collector because it is easy to manufacture into a thin film and is inexpensive. The shape of the current collector is not limited, and may be a flat plate shape, mesh shape, net shape, punch shape, embossed shape, or a combination thereof, for example, a mesh shape flat plate. For example, the current collector may have a non-flat surface formed by etching.

The binder is a component that assists the bonding of the active material and the conductive agent and the bonding to the current collector, and is added in an amount of 1 to 50 parts by weight based on 100 parts by weight of the total weight of the positive electrode active material. Non-limiting examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, and tetrafluoride. Examples include ethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluorine rubber, and various copolymers. The content is 2 to 5 parts by weight based on 100 parts by weight of the total weight of the positive electrode active material. When the binder content is within the above range, the binding force of the active material layer to the current collector is good.

The conductive agent is not particularly limited as long as it has conductivity without causing chemical changes in the battery. For example, graphite such as natural graphite or artificial graphite; Carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The content of the conductive agent is 1 to 10 parts by weight, for example, 2 to 5 parts by weight, based on 100 parts by weight of the total weight of the positive electrode active material. When the content of the conductive agent is within the above range, the conductivity characteristics of the finally obtained positive electrode are excellent.

As a non-limiting example of the solvent, N-methylpyrrolidone and the like are used.

The content of the solvent is 100 to 2000 parts by weight based on 100 parts by weight of the positive electrode active material. When the solvent content is within the above range, it is easy to form an active material layer.

The lithium metal battery according to one embodiment has excellent capacity and lifespan characteristics, so it can be used not only in battery cells used as power sources for small devices, but also in medium-to-large battery packs containing a number of battery cells used as power sources for medium-to-large devices. It can also be used as a unit cell in a battery module. In addition, lithium metal batteries according to one embodiment have high voltage, capacity, and energy density, so they are widely used in fields such as mobile phones, laptop computers, storage batteries for power generation facilities such as wind or solar power, electric vehicles, uninterruptible power supplies, and household storage batteries. It is becoming.

Examples of the medium-to-large devices include electric vehicles (electric vehicles), including electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and electric bicycles ( Examples include, but are not limited to, power storage devices for electric two-wheeled vehicles (e-bikes), electric scooters (E-scooters), power tools, etc.

According to another aspect, obtaining a composition for forming a protective film by mixing i) a polymer and ii) one or more selected from the group consisting of a metal salt containing a group 1 or group 2 element and a nitrogen-containing additive; Supplying the composition for forming a protective film to a lithium metal anode; A method of protecting a lithium metal anode of a lithium metal battery according to one embodiment is provided, including the step of drying the resulting product to form a protective film.

According to another aspect, a protective film manufactured according to the above-described method is provided.

Alkyl as used herein refers to a fully saturated branched or unbranched (or straight-chain or linear) hydrocarbon.

Non-limiting examples of “alkyl” include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, neopentyl, iso-amyl, n-hexyl, 3 -Methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl, etc.

Among “alkyl”, at least one hydrogen atom is a halogen atom, a C1-C20 alkyl group substituted with a halogen atom (e.g. CCF ₃ , CHCF ₂ , CH ₂ F, CCl _3, etc.), C1-C20 alkoxy, C2-C20 alkoxy Alkyl, hydroxy group, nitro group, cyano group, amino group, amidino group, hydrazine group, hydrazone group, carboxyl group or its salt, sulfonyl group, sulfamoyl group, sulfonic acid group or its salt, phosphoric acid or its salt, or C1- C20 alkyl group, C2-C20 alkenyl group, C2-C20 alkynyl group, C1-C20 heteroalkyl group, C6-C20 aryl group, C6-C20 arylalkyl group, C6-C20 heteroaryl group, C7-C20 hetero It may be substituted with an arylalkyl group, a C6-C20 heteroaryloxy group, a C6-C20 heteroaryloxyalkyl group, or a C7-C20 heteroarylalkyl group.

The term “halogen atom” includes fluorine, bromine, chlorine, iodine, etc.

“Alkenyl” refers to a branched or unbranched hydrocarbon having at least one carbon-carbon double bond. Non-limiting examples of alkenyl groups include vinyl, allyl, butenyl, isopropenyl, and isobutenyl, and at least one hydrogen atom of the alkenyl group may be substituted with the same substituent as in the case of the alkyl group described above. .

“Alkynyl” refers to a branched or unbranched hydrocarbon having at least one carbon-carbon triple bond. Non-limiting examples of “alkynyl” include ethynyl, butynyl, isobutynyl, propynyl, etc.

One or more hydrogen atoms of “alkynyl” may be substituted with the same substituent as in the case of the alkyl group described above.

“Aryl” also includes groups in which an aromatic ring is fused to one or more carbon rings. Non-limiting examples of “aryl” include phenyl, naphthyl, tetrahydronaphthyl, etc.

Additionally, one or more hydrogen atoms in the “aryl” group may be replaced with the same substituent as in the case of the alkyl group described above.

“Heteroaryl” refers to a monocyclic or bicyclic organic compound containing one or more heteroatoms selected from N, O, P or S, and the remaining ring atoms are carbon. The heteroaryl group may include, for example, 1-5 heteroatoms and 5-10 ring members. The S or N may be oxidized and have various oxidation states.

Examples of heteroaryl include thienyl, furyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, 1,2 ,5-oxadiazolyl, 1,3,4-oxadiazolyl group, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1, 3,4-thiadiazolyl, isothiazol-3-yl, isothiazol-4-yl, isothiazol-5-yl, oxazol-2-yl, oxazol-4-yl, oxazol-5 -yl, isoxazol-3-yl, isoxazol-4-yl, isoxazol-5-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-5 -yl, 1,2,3-triazol-4-yl, 1,2,3-triazol-5-yl, tetrazolyl, pyridyl-2-yl, pyridyl-3-yl, pyrazine-2-yl , pyrazin-4-yl, pyrazin-5-yl, pyrimidin-2-yl, pyrimidin-4-yl, or pyrimidin-5-yl.

The term “heteroaryl” includes instances where a heteroaromatic ring is fused to one or more aryl, cycloaliphatic, or heterocycles.

The “carbon ring” group used in chemical formulas refers to a saturated or partially unsaturated, non-aromatic monocyclic, bicyclic or tricyclic hydrocarbon group.

Examples of monocyclic hydrocarbons include cyclopentyl, cyclopentenyl, cyclohexyl, and cyclohexenyl. Examples of bicyclic hydrocarbons include bornyl, decahydronaphthyl, bicyclo[2.1.1]hexyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.1]heptenyl, or bicyclo[2.2.2]octyl. And examples of tricyclic hydrocarbons include adamantyl and the like.

A “heterocycle” is a ring containing at least one heteroatom and may contain 5 to 20 carbon atoms, for example 5 to 10 carbon atoms. Here, the heteroatom is one selected from sulfur, nitrogen, oxygen, and boron.

For example, the term “substituted C1-C30 alkyl” refers to a C1-C30 alkyl group substituted with a C6-C30 aryl group, where the total number of carbon atoms in the substituted alkyl group is C7-C60.

Alkoxy, aryloxy, and heteroaryloxy herein refer to alkyl, aryl, and heteroaryl bonded to an oxygen atom, respectively.

This is explained in more detail through the following examples and comparative examples. However, the examples are for illustrative purposes only and are not limited to these.

Example 1: Manufacturing of lithium metal battery

Polystyrene-b-polyisoprene-b-polystyrene block copolymer (available from Polymer Source) was added to anhydrous tetrahydrofuran to obtain a mixture containing 5% by weight of block copolymer. In the block copolymer, the mixed weight ratio of polystyrene block, polyisoprene block, and polystyrene block was about 11:78:11, and the weight average molecular weight of the block copolymer was about 100,000 Daltons.

A composition for forming a protective film was obtained by adding 5% by weight of Li ₃ N, 5% by weight of CsTFSI, and 200% by weight of Al ₂ O ₃ (average particle diameter: about 10 nm) to the mixture containing the block copolymer. Here, the content of Li3N was about 5 parts by weight based on 100 parts by weight of the block copolymer, and the content of CsTFSI was about 5 parts by weight based on 100 parts by weight of the block copolymer.

The composition for forming a protective film was coated with a doctor blade to a thickness of about 3 μm on a lithium metal thin film (thickness: about 20 μm). The coated result was dried at about 25°C to prepare a lithium metal anode with a protective film (thickness: about 3㎛) formed on the lithium metal anode.

Separately, a positive electrode composition was obtained by mixing LiCoO ₂ , a conductive agent (Super-P; Timcal Ltd.), polyvinylidene fluoride (PVdF), and N-methylpyrrolidone. The mixing weight ratio of LiCoO ₂ , conductive agent, and polyvinylidene fluoride (PVDF) in the positive electrode composition was 97:1.5:1.5.

The positive electrode composition was coated on aluminum foil (thickness: about 15㎛) and dried at 25°C, and the dried result was dried in a vacuum at about 110°C to prepare a positive electrode. The discharge capacity per unit area of the positive electrode was about 3.5 mAh/cm ² .

A lithium metal battery (coin cell) was manufactured by interposing a polyethylene separator (porosity: about 48%) between the positive electrode obtained according to the above process and the lithium metal negative electrode (thickness: about 20㎛). Here, a liquid electrolyte was added between the positive electrode and the lithium metal negative electrode. Liquid electrolytes include 1.2-dimethoxyethane (DME) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (1,1,2) in a 2:8 volume ratio. An electrolyte solution containing 1.0M LiN(SO ₂ F) ₂ (hereinafter referred to as LiFSI) dissolved in a mixed solvent of ,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) was used.

Example 2: Manufacturing of lithium metal battery

A lithium metal battery was manufactured in the same manner as in Example 1, except that LiNO ₃ was used instead of Li ₃ N when preparing the composition for forming a protective film.

Example 3: Manufacturing of lithium metal battery

When preparing the composition for forming a protective film, a lithium metal battery was manufactured in the same manner as in Example 1, except that the contents of Li ₃ N and CsTFSI were 0.05 parts by weight and 0.05 parts by weight, respectively, based on 100 parts by weight of the block copolymer. Manufactured.

Example 4: Manufacturing of lithium metal battery

When preparing the composition for forming a protective film, a lithium metal battery was manufactured in the same manner as in Example 1, except that the contents of Li ₃ N and CsTFSI were 50 parts by weight and 50 parts by weight, respectively, based on 100 parts by weight of the block copolymer. Manufactured.

Example 5: Manufacturing of lithium metal battery

A lithium metal battery was manufactured in the same manner as in Example 2, except that when preparing the composition for forming a protective film, the contents of LiNO ₃ and CsTFSI were 0.05 parts by weight and 0.05 parts by weight, respectively, based on 100 parts by weight of the block copolymer. did.

Example 6: Manufacturing of lithium metal battery

A lithium metal battery was manufactured in the same manner as in the Example, except that when preparing the composition for forming a protective film, the contents of LiNO ₃ and CsTFSI were 50 parts by weight and 50 parts by weight, respectively, based on 100 parts by weight of the block copolymer. .

Example 7: Manufacturing of lithium metal battery

A lithium metal battery was manufactured in the same manner as in Example 1, except that when preparing the composition for forming a protective film, the content of CsTFSI was increased and the mixing weight ratio of Li ₃ N and CsTFSI was changed to 1:2.

Example 8: Manufacturing of lithium metal battery

A lithium metal battery was manufactured in the same manner as in Example 2, except that the mixing weight ratio of LiNO ₃ and CsTFSI was changed to 1:2 when preparing the composition for forming a protective film.

Example 9-10: Manufacturing of lithium metal batteries

A lithium metal battery was manufactured in the same manner as in Example 1, except that ethyl nitrate and nitromethane were used instead of Li ₃ N when preparing the composition for forming a protective film.

Example 11: Manufacturing of lithium metal batteries

A lithium metal battery was manufactured in the same manner as in Example 1, except that Li ₃ N was not added when preparing the composition for forming a protective film.

Example 12: Manufacturing of lithium metal batteries

A lithium metal battery was manufactured in the same manner as in Example 1, except that CsTFSI was not added and LiNO ₃ was used instead of Li ₃ N when preparing the composition for forming a protective film.

Example 13: Manufacturing of lithium metal batteries

A lithium metal battery was manufactured in the same manner as in Example 1, except that polyvinyl alcohol was used instead of polystyrene-b-polyisoprene-b-polystyrene block copolymer when preparing the composition for forming a protective film.

Example 14: Manufacturing of lithium metal batteries

A lithium metal battery was manufactured in the same manner as in Example 2, except that SiO ₂ was used instead of Al ₂ O ₃ when preparing the composition for forming a protective film.

Example 15: Manufacturing of lithium metal batteries

A lithium metal battery was manufactured in the same manner as in Example 1, except that pyridine N-oxide was used instead of Li ₃ N when preparing the composition for forming a protective film.

Example 16: Manufacturing of lithium metal batteries

A lithium metal battery was manufactured in the same manner as in Example 2, except that NaTFSI was used instead of CsTFSI when preparing the composition for forming a protective film.

Example 17: Manufacturing of lithium metal batteries

A lithium metal battery was manufactured in the same manner as in Example 2, except that Mg(TFSI) ₂ was used instead of CsTFSI when preparing the composition for forming a protective film.

Comparative example 1: Manufacturing of lithium metal battery

A positive electrode composition was obtained by mixing LiCoO ₂ , a conductive agent (Super-P; Timcal Ltd.), polyvinylidene fluoride (PVdF), and N-methylpyrrolidone. The mixing weight ratio of LiCoO ₂ , conductive agent, and PVDF in the positive electrode composition was 97:1.5:1.5.

The positive electrode composition was coated on aluminum foil (thickness: about 15㎛) and dried at 25°C, and the dried result was dried in a vacuum at about 110°C to prepare a positive electrode.

A lithium metal battery was manufactured by using a polypropylene separator (thickness: 12㎛, porosity: 48%) as a separator between the positive electrode obtained according to the above process and a lithium metal thin film (thickness: about 20㎛), and using it as a liquid electrolyte. did. The liquid electrolyte is a mixed solvent of 1.2-dimethoxyethane (DME) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) at a volume ratio of 2:8. 1M LiFSI dissolved was used.

Comparative example 2: Manufacturing of lithium metal battery

A polymer electrolyte (thickness: 200 μm) was prepared by mixing 20 mol of polyethylene oxide, 1 mol of lithium bistrifluoromethylsulfonylimide (LiTFSI), and 1 mol of CsTFSI.

A lithium metal anode was manufactured by stacking the polymer electrolyte on top of a lithium metal thin film (thickness: about 20㎛).

Separately, a positive electrode composition was obtained by mixing LiCoO ₂ , a conductive agent (Super-P; Timcal Ltd.), polyvinylidene fluoride (PVdF), and N-methylpyrrolidone. The mixing weight ratio of LiCoO ₂ , conductive agent, and PVDF in the positive electrode composition was 97:1.5:1.5.

The positive electrode composition was coated on aluminum foil (thickness: about 15㎛) and dried at 25°C, and the dried result was dried in a vacuum at about 110°C to prepare a positive electrode.

A lithium metal battery (coin cell) was manufactured by interposing a polyethylene/polypropylene separator between the positive electrode obtained according to the above process and the lithium metal negative electrode. Here, a liquid electrolyte was added between the positive electrode and the lithium metal negative electrode. The liquid electrolyte is a mixture of 1,2-dimethoxyethane (DME) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) in a 2:8 volume ratio. An electrolyte solution containing 1M LiFSI dissolved in a solvent was used.

When the charging and discharging process was performed on the lithium metal battery manufactured according to Comparative Example 2, the effect of suppressing the formation of lithium dendrites was minimal, and the interfacial resistance between the protective film and the lithium metal negative electrode surface increased. And because the lithium ion mobility was very small, the cell capacity was not realized under the evaluation example conditions.

Comparative example 3: Manufacturing of lithium metal battery

An electrolyte solution obtained by adding Li ₃ N and CsTFSI to a liquid electrolyte and adding 1.3M LiPF ₆ dissolved in a lithium salt mixed solvent of ethylene carbonate, diethyl carbonate, and fluoroethylene carbonate at a volume ratio of 2:6:2 as the liquid electrolyte. A lithium metal battery was manufactured according to the same method as Comparative Example 1, except that . Here, the contents of Li ₃ N and CsTFSI were each about 5 parts by weight based on 100 parts by weight of the total weight of the liquid electrolyte.

When Li ₃ N and CsTFSI were added to the liquid electrolyte according to Comparative Example 3, Li ₃ N and CsTFSI did not dissolve well in the carbonate-based organic solvent of the liquid electrolyte. As a result, the lithium metal battery manufactured according to Comparative Example 3 was not even initially charged properly, making it impossible to obtain a lifespan graph.

Comparative example 4: Manufacturing of lithium metal battery

Polystyrene-b-polyisoprene-b-polystyrene block copolymer (available from Polymer Source) was added to anhydrous tetrahydrofuran to obtain a mixture containing 5% by weight of block copolymer. In the block copolymer, the mixed weight ratio of polystyrene block, polyisoprene block, and polystyrene block was about 11:78:11, and the weight average molecular weight of the block copolymer was about 100,000 Daltons.

200% by weight of Al ₂ O ₃ (average particle diameter: about 10 nm) was added to the block copolymer-containing mixture, coated on top of a lithium metal thin film (thickness: about 20 μm) with a doctor blade, and dried at about 25°C to form lithium metal. A lithium metal anode with a protective film (thickness: about 3㎛) formed on the thin film was manufactured.

Separately, a positive electrode composition was obtained by mixing LiCoO ₂ , a conductive agent (Super-P; Timcal Ltd.), polyvinylidene fluoride (PVdF), and N-methylpyrrolidone. The mixing weight ratio of LiCoO ₂ , conductive agent, and PVDF in the positive electrode composition was 97:1.5:1.5. The positive electrode composition was coated on aluminum foil (thickness: about 15㎛) and dried at 25°C, and the dried result was dried in a vacuum at about 110°C to prepare a positive electrode. The discharge capacity per unit area of the positive electrode was about 3.5 mAh/cm ² .

A lithium metal battery was manufactured by interposing a polyethylene separator (thickness: 12um, porosity: 48%) between the positive electrode obtained according to the above process and the lithium metal negative electrode. Here, a liquid electrolyte was added between the anode and the cathode. The liquid electrolyte is a mixed solvent of 1.2-dimethoxyethane (DME) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) at a volume ratio of 2:8. An electrolyte solution containing 1M LiFSI was used.

Evaluation example 1: Scanning electron microscope

The lithium metal battery manufactured according to Example 2 and Comparative Example 1 was subjected to constant current charging at a current of 0.1C rate at 25°C until the voltage reached 4.40 Volts (V) (vs. Li), and then the lithium metal negative electrode surface The condition was analyzed using a scanning electron microscope (SEM).

The results of the above-described scanning electron microscope analysis are shown in Figures 3A and 3B. Figure 3a shows the surface of a lithium metal anode in a lithium metal battery manufactured according to Example 2, and Figure 3b shows the surface of a lithium metal anode in a lithium metal battery manufactured according to Comparative Example 1.

Referring to this, it was confirmed that the lithium metal battery manufactured according to Example 2 had reduced lithium dendrite formation on the lithium metal surface compared to the lithium metal battery of Comparative Example 1.

In addition, the lithium metal battery manufactured according to Example 2 and Comparative Example 1 was subjected to constant current charging at 25°C at a current of 0.1C rate (0.38mA/cm ² ) until the voltage reached 4.40V (vs. Li). After this, the current was cut off at a rate of 0.05C while maintaining 4.40V in constant voltage mode. After one charge, the cross-sectional state of the surface of the lithium metal anode was analyzed using SEM.

The analysis results are shown in Figures 4A and 4B. Figure 4a shows a cross-section of a lithium metal anode in a lithium metal battery manufactured according to Example 2, and Figure 4b shows a cross-section of a lithium metal anode in a lithium metal battery manufactured according to Comparative Example 1.

Referring to this, the thickness of the lithium metal anode after charging in the lithium metal battery manufactured according to Comparative Example 1 is about 58.9㎛, whereas the thickness of the lithium metal anode after charging in the lithium metal battery manufactured according to Example 2 is about 29.1㎛. It was greatly reduced to ㎛. In this way, the volume change of the lithium metal battery of Example 2 during charging and discharging was smaller than that of the lithium metal battery of Comparative Example 1.

Evaluation example 2: Lithium electrodeposition density

For the lithium metal batteries manufactured according to Examples 2, 11, 12, 16, and 17 and Comparative Examples 1 and 4, the voltage was 4.40V (vs. Li) with a current of 0.1C rate (0.38mA/cm ² ) at 25°C. ), and then cut-off at a current of 0.05C rate while maintaining 4.40V in constant voltage mode. After one charge, the electrodeposition density on the surface of the lithium metal anode was examined.

The electrodeposition density evaluation results are shown in Table 1 below.

division Lithium electrodeposition density (g/cc) Example 2 0.31-0.32 Example 11 0.27-0.30 Example 12 0.26-0.28 Example 16 0.26-0.27 Example 17 0.27-0.29 Comparative Example 1 0.18-0.19 Comparative Example 4 0.24-0.25

Referring to Table 1, the electrodeposition density in the lithium metal batteries manufactured according to Examples 2, 11, 12, 16, and 17 was increased compared to Comparative Examples 1 and 4. From this, it was found that the lithium metal batteries manufactured according to Examples 2, 11, 12, 16, and 17 had a better lithium dendrite suppression function than those of Comparative Examples 1 and 4.

Evaluation example 3: Impedance measurement

The lithium metal battery manufactured according to Example 2 and the lithium metal battery manufactured according to Comparative Example 1 were analyzed at 25°C according to the 2-probe method using an impedance analyzer (Solartron 1260A Impedance/Gain-Phase Analyzer). Resistance was measured. The amplitude was ±10 mV and the frequency range was 0.1 Hz to 1 MHz.

A Nyguist plot for the impedance measurement results when the elapsed time after manufacturing the lithium metal battery manufactured according to Example 2 and Comparative Example 1 was 24 hours is shown in FIG. 5. In Figure 5, the interfacial resistance of the electrode is determined by the position and size of the semicircle. The difference between the left x-axis intercept and the right x-axis intercept of the semicircle represents the interfacial resistance at the electrode.

As shown in Figure 5, the interfacial resistance of the lithium metal battery manufactured according to Example 2 was found to be slightly reduced compared to the interfacial resistance of the lithium metal battery manufactured according to Comparative Example 1.

Evaluation example 4: charge/discharge Characteristics (discharge capacity)

1) Examples 1, 14, 15 and Comparative Examples 1 and 4

For the lithium metal batteries manufactured according to Examples 1, 14, and 15 and the lithium metal batteries manufactured according to Comparative Examples 1 and 4, the voltage was 4.40V ( vs. Li), and then cut-off at a current of 0.05C rate while maintaining 4.40V in constant voltage mode. Subsequently, the discharge was performed at a constant current of 0.1C rate until the voltage reached 3.0V (vs. Li) (formation stage, 1 ^st cycle). This charging and discharging process was performed two more times to complete the chemical conversion process.

The lithium metal battery that has undergone the above chemical conversion step is charged at room temperature (25°C) with a constant current of 0.7C in a voltage range of 4.4V relative to lithium metal, and then reaches a cut-off voltage of 3.0V at 0.5C. Constant current discharge was performed at a rate of 0.5 until discharge occurred. The charging and discharging process described above was performed repeatedly a total of 100 times. The capacity maintenance rate is calculated from Equation 1 below.

[Equation 1]

Capacity maintenance rate (%) = (100th cycle discharge capacity/1st cycle discharge capacity) × 100

The results of evaluating the charge and discharge characteristics of the lithium metal battery manufactured according to Example 1, Comparative Example 1 and Comparative Example 4 are as follows. The discharge capacity change and Coulomb efficiency during the 100 cycle repetitions are shown in Figures. As shown in 6 and 7.

From Figures 6 and 7, it was found that the capacity retention rate of the lithium metal battery manufactured according to Example 1 was improved compared to the lithium metal battery manufactured according to Comparative Examples 1 and 4.

In addition, the lithium metal batteries manufactured according to Examples 14 and 15 were performed according to the same method as the capacity retention rate of the lithium metal batteries manufactured according to Example 1 and the lithium metal batteries manufactured according to Comparative Examples 1 and 4 to determine the capacity. Retention rate was evaluated.

As a result of the evaluation, the lithium metal batteries manufactured according to Examples 14 and 15 showed almost the same level as the lithium metal batteries manufactured according to Example 1.

Evaluation example 5: Tensile modulus and elongation

The composition for forming a protective film prepared according to Example 1 was casted on a substrate, tetrahydrofuran (THF) from the casting result was slowly evaporated at about 25°C over 24 hours in an argon glove box, and evaporated under vacuum at 25°C. A protective film in the form of a film was prepared by drying for 24 hours. At this time, the thickness of the protective film was about 50㎛.

The tensile modulus of the protective film was measured using DMA800 (TA Instruments), and protective film specimens were prepared using ASTM standard D412 (Type V specimens). Tensile modulus is also called Young’s modulus.

The change in strain against stress of the protective film was measured at a rate of 5 mm per minute at 25 ^o C and a relative humidity of about 30%. The measurement results are shown in Figure 8. The tensile modulus was obtained from the slope of the stress-strain curve, and the elongation was obtained from the strain value.

As a result of the evaluation, the protective film prepared according to Example 1 had tensile modulus and elongation characteristics

I could see that this was excellent. Therefore, by using the protective film prepared according to Example 1 having these characteristics, the volume change of the lithium metal anode and the growth of lithium dendrite can be effectively suppressed.

Evaluation example 6: charge/discharge characteristic( rate Performance)

1) Example 2 and Comparative Example 1

The lithium metal batteries manufactured in Example 2 and Comparative Example 1 were charged at a constant current of 0.1C rate at 25°C until the voltage reached 4.4V (vs. Li), and then maintained at 4.4V in constant voltage mode. While doing so, a cut-off was made at a current of 0.05C rate. Subsequently, the discharge was performed at a constant current of 0.1C rate until the voltage reached 3.0V (vs. Li). This charging and discharging process was performed two more times to complete the chemical conversion process.

Next, it was charged under constant current (A1) and constant voltage (4.4V, 0.05C cut-off) conditions according to the conditions in Table 2 below, and then rested for 10 minutes. Subsequently, it was discharged until 3.0V under constant current (A2) conditions according to the conditions in Table 2 below. In this way, charging and discharging were performed under different current conditions to evaluate the rate capability of the lithium metal battery.

Condition 1 Condition 2 Condition 3 Condition 4 Condition 5 Condition 6 Current A1(C) 0.2 0.7 0.7 0.7 0.7 0.7 Current A2 (C) 0.2 0.2 0.5 1.0 1.5 2.0

The rate performance of the lithium metal battery manufactured according to Example 2 and Comparative Example 1 is shown in Figure 9.

Referring to FIG. 9, it was found that the rate performance of the lithium metal battery manufactured according to Example 2 was improved when compared to the lithium metal battery manufactured according to Comparative Example 1.

2) Examples 2, 11, 12, Comparative Example 1, Comparative Example 4

Lithium metal batteries manufactured according to Examples 2, 11, and 12 and Comparative Examples 1 and 4

A lithium metal battery is charged at a constant current of 0.1C rate at 25°C until the voltage reaches 4.4V (vs. Li), then maintained at 4.4V in constant voltage mode and cut off at a current of 0.05C rate. -off). Subsequently, the discharge was performed at a constant current of 0.1C rate until the voltage reached 3.0V (vs. Li). This charging and discharging process was performed two more times to complete the chemical conversion process. Next, it was charged under constant current (0.7C) and full voltage (4.4V, 0.05C cut-off) conditions and rested for 10 minutes. Then, it was discharged to 3.0V under constant current (0.2C or 1.5C) conditions. That is, the rate capability of the lithium metal battery was evaluated by changing the discharge rate to 0.2C and 1.5C, respectively. The results are shown in Table 2 below. C-rate is the discharge rate of the cell, which is a value obtained by dividing the total capacity of the cell by the total discharge time. In Table 3 below, the rate performance is calculated by Equation 2 below.

[Equation 2]

Rate performance (%) = [(discharge capacity at 1.5C)/(discharge capacity at 0.2C)]×00

division Rate performance (%) (1.5C/0.2C) Example 2 94.25 Example 11 92 Example 12 94.25 Comparative Example 1 91 Comparative Example 4 91

As shown in Table 3, it was found that the rate performance of the lithium metal batteries manufactured according to Examples 2, 11, and 12 was improved compared to the lithium metal batteries of Comparative Examples 1 and 4.

Evaluation example 7: Lithium ion delivery a constant

1) Examples 2, 11, 12, Comparative Examples 1 and 4

Li/Li symmetric cells were manufactured by interposing the protective film used in Examples 2, 11, and 12 between lithium metal thin films and adding an electrolyte. The liquid electrolyte includes 1,2-dimethoxyethane DME) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) at a volume ratio of 2:8. ) An electrolyte solution containing 1.0M LiFSI dissolved in a mixed solvent was used.

For comparison with the symmetric cell, the lithium metal thin film of Comparative Example 1 and the lithium metal anode of Comparative Example 4 were used and assembled together with an electrolyte to manufacture a symmetric cell.

The lithium ion transference number (t _Li+ ) of the symmetric cell was measured at 25°C, and some of the results are shown in Table 4 below.

The lithium ion transfer constant can be calculated by Equation 2 below. The values needed to calculate the lithium ion transfer constant were used by measuring the current decay over time with respect to the impedance and input voltage for the lithium symmetric cell (Electrochimica Acta 93 (2013) 254).

[Equation 3]

In equation 3, i _o is the initial current, iss is the steady state current, R ⁰ is the initial resistance, R ^ss is the steady state resistance, and △V is the voltage difference.

division Lithium ion transfer constant (t _{Li +} ) Example 2 0.75-0.80 Example 11 0.67-0.70 Example 12 0.74-0.76 Comparative Example 1 0.56-0.58 Comparative Example 4 0.62-0.65

Referring to Table 4, it was found that the lithium ion transfer constant of the protective films of Examples 2, 11, and 12 was increased compared to Comparative Examples 1 and 4, indicating that the lithium ion transfer rate was improved.

Evaluation example 8: Cell voltage

Li/Li symmetric cells were manufactured by interposing the protective film prepared according to Example 2 between lithium metal thin films and adding an electrolyte. The electrolyte is a mixture of 1,2-dimethoxyethane (DME) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) at a volume ratio of 2:8. An electrolyte solution containing 1.0M LiFSI dissolved in a solvent was used.

For comparison with the symmetric cell, a symmetric cell was manufactured by assembling the lithium metal thin film and electrolyte used in Comparative Example 1.

For each symmetric cell above Since it is a lithium-lithium cell, charging and discharging was performed at a constant current of 1C/1C. At this time, the voltage range was -1 to 1 V.

The cell voltage change over time of the symmetric cell was investigated and shown in FIG. 10.

As shown in Figure 10, it can be seen that the symmetrical cell employing the protective film manufactured according to Example 2 has a small decrease in cell voltage change over time compared to the symmetrical cell using the lithium metal thin film of Comparative Example 1. there was.

In the above, an embodiment has been described with reference to the drawings and examples, but this is merely an example, and those skilled in the art will understand that various modifications and other equivalent embodiments are possible. will be. Therefore, the scope of protection of the present invention should be determined by the appended claims.

10, 20: lithium metal cathode 11, 21: protective film
12, 22a: liquid electrolyte 22b: solid electrolyte
22: electrolyte 13, 23: anode

Claims (23)

Lithium metal cathode;
a protective film disposed on the lithium metal anode and including a polymer, a metal salt containing a Group 1 or Group 2 element, and a nitrogen-containing additive;
anode; and
It includes a liquid electrolyte interposed between the protective film and the anode,
The metal salt and nitrogen-containing additive containing the Group 1 element or Group 2 element are insoluble in the organic solvent of the liquid electrolyte,
A lithium metal battery, wherein the metal salt containing the Group 1 element or the Group 2 element is a metal salt containing one or more selected from Cs, Rb, K, Ba, Sr, Ca, Na, and Mg. delete According to paragraph 1,
The metal salt containing the Group 1 element or the Group 2 element is Cs bis(trifluoromethylsulfonyl)imide {CsTFSI: Cs(bis(trifluoromethylsulfonyl)imide)}, CsNO ₃ , CsPF ₆ , Cs bis(fluorosulfonyl)imide Ponyl) imide {CsFSI: Cs(bis(fluorosulfonyl)imide)}, CsAsF ₆ , CsClO ₄ , CsBF ₄ , RbTFSI, RbNO ₃ , RbPF ₆ , RbFSI, RbAsF ₆ , RbClO ₄ , RbBF ₄ , KTFSI, KNO ₃ , KPF ₆ , KFSI, KAsF ₆ , KClO ₄ , KBF ₄ , NaTFSI, NaNO ₃ , NaPF ₆ , NaFSI, NaAsF ₆ , NaClO 4 , NaBF _{4 ,} Ba(TFSI) ₂ , Ba(NO ₃ ) ₂ , Ba(PF ₆ )2, Ba(FSI) ₂ , Ba(AsF ₆ ) ₂ , Ba(ClO ₄ ) ₂ , Ba(BF ₄ ) ₂ , Sr(TFSI) ₂ , Sr(NO ₃ ) ₂ , Sr(PF ₆ )2, Sr(FSI) ₂ , Sr(AsF ₆ ) ₂ , Sr(ClO ₄ ) ₂ , Sr(BF ₄ ) ₂ , Ca(TFSI) ₂ , Ca(NO ₃ ) ₂ , Ca(PF ₆ )2, Ca(FSI) ) ₂ , Ca(AsF ₆ ) ₂ , Ca(ClO ₄ ) ₂ , Ca(BF ₄ ) ₂ , Mg(TFSI) ₂ , Mg(NO ₃ ) ₂ , Mg(PF ₆ )2, Mg(FSI) ₂ , At least one selected from the group consisting of Mg(AsF ₆ ) ₂ , Mg(ClO ₄ ) ₂ and Mg(BF ₄ ) ₂ , TFSI represents bistrifluoromethylsulfonylimide, and FSI represents bisfluorosulfonyl Lithium metal battery representing imide. According to paragraph 1,
The nitrogen-containing additive includes inorganic nitrate, organic nitrate, inorganic nitrite, organic nitrite, organic nitro compound, organic nitroso compound, NO compound and nitride. At least one lithium metal battery selected from the group consisting of lithium (Li ₃ N). According to paragraph 4,
The inorganic nitrate is at least one selected from the group consisting of lithium nitrate, potassium nitrate, cesium nitrate, barium nitrate, and ammonium nitrate,
The organic nitrate is at least one selected from the group consisting of C1 to C20 dialkyl imidazolium nitrate, guanidine nitrate, ethyl nitrite, propyl nitrite, butyl nitrite, pentyl nitrite, and octyl nitrite,
The organic nitrite is one or more selected from the group consisting of ethyl nitrite, propyl nitrite, butyl nitrite, pentyl nitrite, and octyl nitrite,
The organic nitro compound is at least one selected from the group consisting of nitromethane, nitropropane, nitrobutane, nitrobenzene, dinitrobenzene, nitrotoluene, dinitrotoluene, and nitropyridine,
A lithium metal battery wherein the NO compound is at least one selected from the group consisting of pyridine N-oxide, C1 to C20 alkylpyridine N-oxide, and tetramethyl piperidine N-oxyl (TEMPO). According to paragraph 1,
A lithium metal battery in which the content of a metal salt containing a group 1 or 2 element and a nitrogen-containing additive in the protective film is 0.1 to 100 parts by weight based on 100 parts by weight of the polymer. According to paragraph 1,
The content of the metal salt containing the Group 1 or Group 2 element in the protective film is 0.01 to 99.99 parts by weight based on 100 parts by weight of the polymer,
A lithium metal battery in which the content of the nitrogen-containing additive is 0.01 to 99.99 parts by weight based on 100 parts by weight of the polymer. According to paragraph 1,
A lithium metal battery in which the mixing weight ratio of the metal salt containing a Group 1 or Group 2 element and the nitrogen-containing additive in the protective film is 1:9 to 9:1. According to paragraph 1,
A lithium metal battery wherein the polymer is one or more polymers selected from homopolymers, block copolymers, and graft copolymers, or a mixture thereof. According to clause 9,
The homopolymer is polyvinyl alcohol, polymethyl methacrylate, polymethyl acrylate, polyethyl methacrylate, polyethyl acrylate, polypropyl methacrylate, polypropyl acrylate, polybutyl acrylate, and polybutyl methacrylate. rate, polypentyl methacrylate, polypentyl acrylate, polycyclohexyl methacrylate, polycyclohexyl acrylate, polyhexyl methacrylate, polyhexyl acrylate, polyglycidyl acrylate, polyglycidyl methacrylate A lithium metal battery comprising at least one selected from polyacrylonitrile and polyacrylonitrile. According to paragraph 1,
The polymer is a block copolymer containing a first polymer block and a second polymer block,
The first polymer block is polystyrene, hydrogenated polystyrene, polymethacrylate, poly(methyl methacrylate), polyvinylpyridine, polyvinylcyclohexane, polyimide, polyamide, polyethylene, polybutylene, polypropylene, poly (4-methyl-1-pentene), poly(butylene terephthalate), poly(isobutyl methacrylate), poly(ethylene terephthalate), polydimethylsiloxane, polyacrylonitrile, polymaleic acid, polymaleic acid Anhydride, polymethacrylic acid, poly(tertbutyl vinyl ether), poly(cyclohexyl methacrylate), poly(cyclohexyl vinyl ether), polyvinylidene fluoride, polydivinylbenzene, or one or more of the above-mentioned It is a polymer that contains two or more types of repeating units that make up the polymer,
The second polymer block is polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyethyl methacrylate, polydimethylsiloxane, polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polyethyl acrylate, poly 2- Ethylhexyl acrylate, polybutyl methacrylate, poly2-ethylhexyl methacrylate, polydecyl acrylate, polyethylene vinyl acetate, polyimide, polyamine, polyamide, poly(C1-C20 alkyl carbonate), polynitrile, poly. A lithium metal battery comprising at least one selected from the group consisting of polyphosphazines, polyolefins, polydienes, polyisoprene, polybutadiene, polychloroprene, polyisobutylene, polyurethane, polyethylene, polybutylene, and polypropylene. According to paragraph 1,
A lithium metal battery further comprising an ion conductive film between the lithium metal negative electrode and the protective film. According to paragraph 1,
A lithium metal battery in which the content of a metal salt containing a group 1 or 2 element and a nitrogen-containing additive in the protective film increases from the liquid electrolyte to the area adjacent to the lithium metal negative electrode. According to paragraph 1,
A lithium metal battery wherein the protective film further includes at least one selected from inorganic particles, ionic liquid, polymer ionic liquid, and oligomer. According to clause 14,
The inorganic particles are one or more selected from SiO ₂ , TiO ₂ , ZnO, Al ₂ O ₃ , BaTiO ₃ , cage-structured silsesquioxane, and a metal-organic framework (MOF). Lithium metal battery. According to clause 14,
A lithium metal battery in which the content of the inorganic particles is 1 to 40 parts by weight based on 100 parts by weight of the polymer. According to clause 14,
The ionic liquid is i) ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based and At least one cation selected from the triazolium system,
ii)BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , ClO ₄ ^- , CH ₃ SO _{3 - , CF 3 CO 2} ^- _{, Cl} ^{- ,} Br ^- , I ^- , SO ₄ ^2- , PF ₆ ^- , CF ₃ SO ₃ ^- , (FSO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ )(CF ₃ SO ₂ ) A lithium metal battery comprising at least one compound containing at least one anion selected from N ^- , (CF ₃ SO ₂ ⁾ ₂ N - . According to paragraph 1,
The liquid electrolyte contains lithium salt and an organic solvent,
The organic solvent is ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, fluoroethylene carbonate, 1,2-dimethoxy ethane, 1,2-diethoxyethane, dimethylene glycol dimethyl ether, and trimethylene glycol dimethyl ether. , triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, succinonitrile, sulfolane, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, adiponitrile, and 1,1,2,2 -A lithium metal battery containing at least one selected from tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether. According to paragraph 1,
A lithium metal battery wherein the protective film has a thickness of 1 to 20 μm. According to paragraph 1,
The nitrogen-containing additive is at least one selected from LiNO ₃ and Li ₃ N,
A lithium metal battery in which the metal salt containing the Group 1 or Group 2 element is at least one selected from cesium bistrifluoromethylsulfonylimide (CsTFSI), CsNO ₃ , CsPF ₆ , CsFSI, CsAsF ₆ , CsClO ₄ , and CsBF ₄ . According to paragraph 1,
A lithium metal battery wherein the lithium metal battery further includes one or more selected from a separator, a solid electrolyte, a gel electrolyte, and a polymer ionic liquid. Obtaining a composition for forming a protective film by mixing a polymer, a metal salt containing a group 1 or 2 element, and a nitrogen-containing additive;
supplying the composition for forming a protective film to a lithium metal anode to obtain a lithium metal anode supplied with the composition for forming a protective film; and
A method of protecting a lithium metal anode of a lithium metal battery according to any one of claims 1, 3 to 21, comprising the step of drying the lithium metal anode supplied with the composition for forming a protective film to form a protective film. A protective film manufactured according to the method of claim 22.