Electrolyte composition

Abstract

To provide an electrolyte composition for an anode-free metal battery cell, in which an electrolyte has a significantly reduced risk of precipitation of a salt.SOLUTION: The present invention discloses an electrolyte composition for an anode-free metal battery cell. A metal is an alkali metal, an alkaline earth metal, or a metal of Group IIIa of the periodic table. The electrolyte composition includes a first solvent, a salt of an alkali metal, an alkaline earth metal or a metal of Group IIIa of the periodic table, and an additive. The salt is soluble in the first solvent, and the concentration of the salt in the electrolyte composition is 2 M to 3 M. The additive is a perfluorinated organic compound including at least one halogen atom. The halogen is chlorine, bromine or iodine. The present invention also discloses an anode (5)-free metal battery cell (1) including an electrolyte (3).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrolyte composition for anode-free metal battery cells. It further relates to an anode-free metal battery cell containing the electrolyte according to the present invention. [Background technology]

[0002] Lithium metal battery, magnesium metal battery, aluminum metal battery, sodium metal battery Based on alkali metals, alkaline earth metals, or metals from group IIIa of the periodic table, such as It has been some time since the appearance of metal batteries that can be used for this purpose. For example, lithium metal secondary batteries The optimization of this battery technology in terms of energy density, cost, and safety will This resulted in a so-called "anode-free" configuration. In this configuration, the anode is essentially Typically, the current collector is bare, such as a copper current collector. No graphite coating is used.

[0003] The charge / discharge mechanism in anode-free batteries follows the classical concept / composition of the anode. It differs from traditional rechargeable batteries because it has no anode. The battery cell also uses an electrolyte that is made up of alkali metals, alkaline earth metals, or elements of the III Group A metals are not included in excessive amounts. However, even though there is no anode, First, alkali metals such as lithium and sodium, and alkaline earth metals such as magnesium A metal from group IIIa of the periodic table, such as aluminum, is required because This is because metal ions accumulate on the anode current collector during charging. The lithium deposit forms with a solid electrolyte interphase (SEI). This is the only lithium available for discharging the battery cell, i.e., there is no active lithium on the anode side. This eliminates the safety issues that can occur in lithium metal batteries. This significantly reduces the above risks.

[0004] As a result, the consumption of electrolyte and the formation of unavailable alkali metals or alkaline earth metals are This leads to loss of capacity and performance degradation of the battery cells. To function, all cell components must be perfectly coordinated with each other. This is still an issue in the current situation.

[0005] The electrolyte is a key component in any battery cell. The electrolyte acts as a carrier for the ions of the alkali metals and alkaline earth metals. It is an important contact medium.

[0006] International patent application WO2021213743 describes a cathode comprising a current collector and an anode. A current collector of the anode and cathode, a liquid electrolyte between the current collectors of the anode and cathode, and a separator. The paper describes a nodeless lithium-ion battery that uses at least one liquid electrolyte. and at least 70% by volume of a solvent mixture based on the total volume of the electrolyte composition. The solvent mixture comprises at least one fluorinated ether compound and at least one The fluorinated ether compounds are classified into 10 groups. The addition of fluorinated lithium salts makes it possible to reduce the overall concentration of lithium salts. Ether compounds are known to have little or no solubility in lithium salts. Therefore, the local concentration of lithium salts in non-fluorinated ether compounds is high. This allows the solvent mixture to remain in the solution despite the low overall concentration of lithium salt. This can result in undesirable precipitation of lithium salts in the mixture.

[0007] Electrolytes known for use in anode-free metal battery cells are so-called These electrolytes are high concentration electrolytes (HCE) or ultra-high concentration electrolytes. Typically, such electrolytes are salts of metals with concentrations greater than 3M, often greater than 4M or even 5.5M; That is, the alkali metal salts or alkaline earth metal salts. An example is 5.5 M lithium bis(fluorosulfonyl)imide in dimethyl carbonate. (LiFSI), which is stable, has a high cathode voltage, and has an aluminum current collector. For example, see the literature, 'High rate and stable cycling of lithium metal anode ', J. Qian, WA Henderson, et al., Nature Communications, 6, 6362 (2015), D 4M LiFSI in MC increases the coulombic efficiency of lithium metal anode to 99.2% It is disclosed that it is possible to

[0008] The salts used often contain fluorine. Due to the high anion concentration of the salt, the anode A fluorine-rich SEI is formed at both the cathode and the cathode. This results in Reduce or inhibit the formation of dendrites on metal surfaces and improve plating / peeling of battery cells (charging / discharging) ) Coulombic efficiency is increased.

[0009] Another electrolyte concept is locally high concentration electrolyte (LHCE) or locally ultra-high concentration electrolyte. These are salt-solvent cross-links that form between the electrolyte solvent and the salt when the salt dissolves in the solvent. In order to reduce the overall salt concentration in the final electrolyte composition while maintaining the concentration of the cluster, This requires the use of a diluent to keep the concentration above 3M. It is highly inert to electrolytes and has little or no solubility in salts. The diluent is easily miscible with the vatable solvent, preventing phase separation. A high concentration of salt-solvent clusters must be maintained. In other words, the diluent must be The local coordination environment is preserved, i.e., the coordination of the solvating solvent with Li + Ion distribution Li + The diluent has low solvating ability for ions. Surrounding the solvating solvent of the anion and HCE.

[0010] International patent application WO2020106762 describes a method for producing localized ultra-high concentration electrolytes (LSEs) (localized Embodiments of high concentration electrolytes (also called LHCEs) and devices containing such LSEs The LSE discloses a rechargeable alkaline battery that includes an anode-free battery cell. Used in metal and alkali ion batteries. The electrolyte is a mixture of an active salt and an electrolyte in which the active salt is soluble. and a diluent in which the active salt is insoluble or poorly soluble. The salt is soluble in concentrations greater than 3M, such as greater than 3M up to 10M. The low solubility of the salt in the diluent leads to localized high salt concentrations. This leads to the undesirable precipitation of salts in the solvent mixture. Elephants become especially evident during storage.

[0011] The disadvantage of such high and ultra-high concentration electrolytes is that the salt must be highly soluble in the solvent. Another drawback is that high local salt concentrations can reduce the desired salt content in the electrolyte. This can cause undesirable precipitation. The dissociation constants of the salts are HCE and L. Therefore, several types of salts are commonly used. Also, the short-term effect is that the amount of diluent added to the electrolyte increases significantly. The diluents are often very expensive, which makes the electrolytes expensive. Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention aims to overcome one or more of the above problems. The present invention relates to an electrolyte composition for anode-free metal battery cells that reduces the risk of salt precipitation. The present invention further provides a method for the preparation of a salt having a wide range of commercially available salts. The present invention further aims to provide an electrolyte composition which can be used in a known The object is to provide an electrolyte which is cheaper than conventional electrolytes.

[0013] The present invention further enables the formation of a stable SEI and has a high power density and a high reproducibility. To develop anode-free metal battery cell with good stability against repeated discharge. The present invention further aims to provide a method for manufacturing a cellular phone having a longer lifespan, i.e., An anode, such that the node can be charged and discharged more than a free metal battery cell. The present invention also aims to provide a metal battery cell that is free of lead. The objective of the present invention is to provide a metal battery cell that is free of lead.

[0014] In the context of this invention, the terms "battery" and "battery cell" have the same meaning.

[0015] A first aspect of the present invention is an anode-free metal battery cell as claimed in the accompanying claims. The electrolyte composition comprises a first solvent, a metal salt, and an additive. Optionally, the electrolyte composition may further comprise a second solvent. do.

[0016] The salt of the metal may be an alkali metal, an alkaline earth metal, or a metal of Group IIIa of the periodic table. The metal salt is preferably lithium, magnesium, The metal is preferably lithium or magnesium. be. The concentration of the salt in the electrolyte composition is 2M to 3M; The additive is a perfluorinated organic compound containing at least one halogen atom; The halogen is chlorine, bromine or iodine.

[0017] The salt of the metal is soluble in the first solvent. When the composition includes a second solvent, the salt of the metal may also be soluble in the second solvent. The concentration of the salt in the electrolyte is 0.5M to 3.25M, preferably 1M to 3. It is preferably 1M, and more preferably 2M to 3M.

[0018] Preferably, the first solvent is a carbonate, an ether, a nitrile, a sulfone, a sulfo The ionic liquid is selected from the group consisting of oxides, esters, and alkyl esters of ionic liquids. For example, the first solvent comprises or consists essentially of 1,2-dimethoxyethane (DME). It can be.

[0019] Ionic liquids are non-molecular compounds that consist only of ions, i.e., anions and cations. In the present invention, the first solvent in the electrolyte composition is preferably Suitable ionic liquids are preferably pyrrolidinium, piperidinium, cyclic saturated ammonia, The cations include, or consist essentially of, cations such as cations of cation, ... Preferably, the anion is bis(fluorosulfonyl)imide (FSI), bis( trifluoromethanesulfonyl)imide (TFSI) or combinations thereof This is essentially what will happen from now on.

[0020] The additive is a perfluorinated organic compound further containing at least one halogen atom. The halogen is chlorine (Cl), bromine (Br) or iodine (I). In particular, the additive is soluble in the first solvent. The additive may be soluble in said second solvent.

[0021] The additive has the formula (I): XCF2-(CF2) x -CF 3-y Y y (I) where X is Cl, Br or I, Y is Cl, Br or I, and x is 0 to 10, preferably 1 to 8, more preferably Preferably, y is 2 to 6, and y is 0 to 3, preferably 0 or 1.

[0022] Preferably, at least X is I. Preferably, X and Y are I. That is, the additive of the perfluoroalkyl halide is a perfluoroalkyl iodide. An example of a perfluoroalkyl iodide is 1-iodoperfluorobutane ( That is, X is I, x is 2, y is 0, and since y is 0, Y is I, Cl, or Br. 1,4-diiodoperfluorobutane (i.e., X can be either I , Y is I, x is 2, y is 1), 1-iodoperfluorohexane (i.e., X is I, x is 4, y is 0, and since y is 0, Y can be either I, Cl or Br. 1,6-diiodoperfluorohexane (i.e., X is I, Y is I, x is 4, y is 1), 1,8-diiodoperfluorooctane (i.e., X is I, Y is I, x is 6 and y is 1), but is not limited thereto.

[0023] When the first solvent is an ionic liquid, an additive according to formula (I), in particular a perfluoro Alkyl iodides are particularly preferred. Such additives are useful in ionic liquids, i.e. , and has high solubility in solutions with high ionic strength.

[0024] The additive has the formula (II): C6F 6-q Z q (II) where Z is Cl, Br, I or C a F 2a+1-b Q b Q is Cl, Br or I, and q is 1 to 5, preferably 1 to 4, more preferably is preferably 1 to 3, and a is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4. and b is a value such that 2a+1-b is greater than or equal to 1.

[0025] Preferably, Z is I. Examples of suitable additives according to formula (II) include 1,4 -diiodo-2,3,5,6-tetrafluorobenzene (i.e., Z is I and q is 2), 1-Iodo-2,3,4,5,6-pentafluorobenzene (i.e., Z is I and q is 1 ) can be mentioned, but is not limited to these.

[0026] Preferably, the electrolyte composition comprises, based on the total weight of the electrolyte composition, The additive is added in an amount of 0.01 to 20% by weight, preferably 0.05 to 15% by weight, more preferably 0. 1-10% by weight, inclusive.

[0027] Preferably, the electrolyte composition further comprises a second solvent, The second solvent acts as a diluent. The second solvent is a hydrofluoroether. , , partially fluorinated alkyl ethers, or combinations thereof. You can become like that from now on.

[0028] A second aspect of the present invention is a metal electrode comprising an anode free of the electrolyte composition according to the present invention. Preferably, the anode-free metal battery cell is a secondary battery cell. It is.

[0029] Preferably, the metal of the anode-free battery cell is an alkali metal, an alkaline Preferably, the metal is an alkali metal. A preferred example of an alkali metal is lithium (Li). In this case, the anode-free metal battery cell is a lithium metal battery cell with anode-free The preferred alkaline earth metals are sodium (Na) and potassium (K). An example would be magnesium (Mg) (in this case, a metal battery cell with a free anode would have a (Ca) and calcium (Ca). III A preferred example of a Group a metal is aluminum.

[0030] Preferably, the metal of the metal salt and the metal of the anode-free battery cell are the same. Preferably, the metal salt is a lithium salt or a magnesium salt, and the battery Each cell is a free anode lithium metal battery cell or a free anode magnet battery cell. It is a lithium metal battery cell.

[0031] Preferably, the anode of the anode-free battery cell comprises a bare current collector. A bare current collector, in the context of the present invention, is a collector that does not have a layer, such as a graphite layer, deposited thereon. It means an electric body.

[0032] The electrolyte composition according to the present invention is an anode-free metal electrode that can provide stable SEI formation. In addition, the electrolyte according to the present invention is excellent in stability when repeatedly charged and discharged. In other words, the electrolyte according to the present invention makes it possible to obtain a higher specific discharge capacity during charging. This makes it possible to improve the stability of battery cells when repeatedly charging and discharging them.

[0033] In addition, a wide range of commercially available metal salts can be used in the electrolyte composition of the present invention. This makes it possible to obtain battery cells with the properties required for the intended use. The electrolyte according to the present invention has the advantage that it is possible to reduce the loss of metal, the so-called "dead metal". This avoids the occurrence of "electrochemical" discharges, thereby increasing the life and power density of the battery cells. This favorable effect can be further enhanced by the fact that the mobility of anions in the electrolyte according to the present invention is reduced. The effect is strengthened by the increase in the number of metal ions moving.

[0034] The electrolyte may further include, but is not limited to, the presence of a second solvent, such as a diluent. The advantage is that in some cases, a small amount is sufficient. Diluents are known to be expensive, The electrolyte of the present invention is less expensive than electrolytes known in the art. can.

[0035] Certain aspects of the present invention will be described in detail with reference to the accompanying drawings, in which: In the aspects, the same reference symbols represent the same things. [Brief description of the drawings]

[0036] [Figure 1] Schematic diagram of a two-electrode metal cell with a free anode. [Diagram 2] FIG. 1 shows the specific capacity of the two-electrode cells, in which the electrolyte does not contain an additive (reference battery cell) and does not contain a perfluoroalkyl iodide additive (battery cell according to the invention), respectively. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] The electrolyte composition according to the present invention comprises a first solvent, an additive, and a metal salt.

[0038] The metal salt may be a salt of an alkali metal, an alkaline earth metal, or a metal from Group IIIa of the periodic table. Preferred examples of the alkali metal include lithium (Li), sodium (Na), and the like. Thorium (Na) and potassium (K). Preferred examples of alkaline earth metals are magnesium (Al). Preferred examples of Group IIIa metals are magnesium (Mg) and calcium (Ca). Preferably, the metal is substantially lithium, magnesium. Cr, Al or S, preferably Li or Mg. .

[0039] The electrolyte composition may include a combination of two or more metal salts. When the above metal salts are present, they may contain the same metal, and in particular all All of the salts can be lithium salts, or the metal salts can contain different metals. and in particular may include lithium and magnesium salts.

[0040] Examples of lithium salts that can be used in the electrolyte composition according to the present invention include hexafluorosilicate, Lithium perfluorinated oxide (LiPF6), Lithium perchlorate (LiClO4), Hexafluoro Lithium arsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), bis(oxygen) Lithium (xalato)borate (LiBOB), Lithium difluoro(oxalato)borate ( LiDFOB), lithium trifluoromethanesulfonate (LiTf), lithium bis( Trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulf Lithium fluoride imide (LiFSI) and their derivatives, but are not limited to these. I can't.

[0041] The preferred derivatives of LiFSI and LiTFSI are lithium bis(R-s sulfonyl)imide, and lithium (R 1 ,R 2 -sulfonyl)imide salts. , but is not limited to this. Here, R, R 1 , R 2is an at least partially fluorinated alkyl group. For example, , R 1 and R 2 are each independently fluoro, trifluoromethyl, pentafluoroethyl , nonafluorobutyl. Examples of such derivatives include lithium ( Fluorosulfonyl)(trifluoromethanesulfonyl)imide, and lithium(penta Fluoroethanesulfonyl)(trifluoromethanesulfonyl)imide.

[0042] Examples of magnesium salts include magnesium perchlorate (Mg(ClO4)2), magnesium Mg(TFSI)2, and the formula: Mg(((R 3 R 4 R 5 R 6 )B)2 Examples of the magnesium (fluoroalkoxy)borate include, but are not limited to, stomach. Here, R 3 , R 4 , R 5 and R 6 is an at least partially fluorinated alkoxy group. R 3 ~R 6 Two or more of the following may be the same: 3 ~R 6 are different from each other It is possible to do so. 3 ~R 6 may be fully fluorinated. R 3 ~R 6 can be a monodentate or bidentate ligand. Such magnesium salts An example of this is:

[0043] JPEG2025063893000002.jpg31161

[0044] Examples of sodium salts are sodium perchlorate (NaClO4), hexafluorophosphate (H2SO4), Sodium phosphate (NaPF6), sodium hexafluoroarsenate (NaAsF6), tetrafluoroethylene Sodium fluoroborate (NaBF4), sodium trifluoromethanesulfonate ( NaTf), sodium bis(trifluoromethanesulfonate)imide (NaTFSI), and sodium bis(fluorosulfonyl)imide (NaFSI). Not limited to these.

[0045] Preferably, the derivatives of NaFSI and NaTFSI include sodium bis(R- sulfonyl)imide, and sodium (R 1 ,R 2 -sulfonyl)imide salts. However, this is not limited to this. Here, R, R 1 , R 2 is an at least partially fluorinated alkyl group. For example, , R 1 and R 2 are each independently fluoro, trifluoromethyl, pentafluoroethyl , nonafluorobutyl. Examples of such derivatives include sodium (Fluorosulfonyl)(trifluoromethanesulfonyl)imide, and sodium (phenyl)sulfonyl (trifluoroethanesulfonyl)imide .

[0046] The salt of the metal is soluble in the first solvent. The concentration of the salt in the electrolyte is 0.5M. up to 3.25M, for example 1M to 3.1M, preferably 1.5M to 3.05M, more preferably is 2M~3M.

[0047] The inventors found that at these moderate salt concentrations, the metal salt has low solubility in the first solvent. It has been found that a high dissociation constant is not necessary. Metal salts can be used in the electrolyte composition of the present invention.

[0048] The inventors further surprisingly found that at such moderate salt concentrations, the gold in the solvent Formation of a stable SEI layer with a moderately high concentration of fluoride ions without impairing the solubility of metal salts As is known in the art, it has been found that the fluorine in the SEI can be In the presence of ions, inactive metals (i.e., metals that are separated and electrically isolated) are formed. This significantly reduces the amount of metal lost, which tends to reduce overall metal loss. Prevents electrolyte decomposition, thus reducing or even preventing efficiency losses and reducing coulomb Therefore, the presence of fluorine ions in the SEI layer can improve the efficiency of the battery cell. This contributes to improving the performance of the

[0049] The electrolyte composition according to the present invention further comprises a first solvent. The content of the first solvent is 2 to 40% by weight, preferably 5 to 60% by weight, based on the total weight of the electrolyte composition. It contains 30% by weight, more preferably 7 to 20% by weight, for example 10 to 15% by weight.

[0050] The first solvent is an alkyl ester, ether, nitrile, sulfone, or sulfoxy group of carbonate. or containing an organic solvent such as a silyl group, an ester, or a combination of any two or more thereof; It can essentially become this.

[0051] Examples of organic solvents include 1,2-dimethoxyethane (DME) and dimethyl carbonate. , Ethylene carbonate, Ethyl methyl carbonate, Dimethyl ether, Dimethoxy ether Tantalum, tetrahydrofuran, dioxane, 1,3-dioxolane, tetraethylene glycol Dimethyl ether, acetonitrile, succinonitrile, adiponitrile, sulfola Examples of suitable amines include dimethyl sulfoxide, methyl acetate, and methyl propionate. Not limited to these.

[0052] Alternatively and / or additionally, the first solvent comprises or consists essentially of an ionic liquid. Ionic liquids can consist of only ions, i.e., anions and cations. They belong to a class of non-molecular compounds that have negligible vapor pressure and high thermal stability at room temperature. This makes it possible to use them as an alternative or replacement for traditional (organic) solvents. It is suitable for use in addition.

[0053] In the context of the present invention, ionic liquids suitable as the first solvent in the electrolyte composition are preferably In particular, pyrrolidinium, piperidinium, imidazolium, and cyclic saturated ammonium cations, including or consisting essentially of ammonium, ammonium salts ... The cyclic saturated ammonium may conform to the following formula (III): , CH2 or O, and n is 1 to 3.

[0054] JPEG2025063893000003.jpg21158

[0055] In the context of the present invention, ionic liquids suitable as the first solvent in the electrolyte composition are preferably In particular, bis(fluorosulfonyl)imide (FSI), bis(trifluoromethanesulfonyl)imide (FSI), (TFSI), hexafluorophosphate, dicyanamide, tetrachloroa the anion comprises or consists essentially of luminate, luminate, or a combination thereof. Preferred examples of the anion are bis(fluorosulfonyl)imide (FSI) and bis(trifluoromethyl)sulfonyl. Trifluoromethanesulfonylimide (TFSI).

[0056] The additive of the electrolyte composition according to the present invention contains at least one further halogen atom. Preferably, the halogen is chlorine (Cl), bromine (Br), or the like. (Br), or iodine (I). Preferably, the additive is soluble in the first solvent. It is possible.

[0057] The inventors have found that by using a perfluorinated organic compound in the electrolyte composition, It was found that the halogen atoms of the additives bond with the anions of the metal salts. The halogen bond interactions between the halogen atoms of the metal salts are It was found that the halogen bonds were strong enough to destroy the interactions. In this case, the metal ions of the metal salt can move freely. The halogen bonds between the anions reduce the mobility of the anions. The number of ions of alkali metals or alkaline earth metals that can move can be increased.

[0058] The transfer number is the ratio of the total current to the total current, here for alkali metal or alkaline earth metal cations. The transfer number is defined as the ratio of the current drawn from the cations to the charge state. This can reduce the electrolyte concentration bias during the charge and discharge steps, thus improving power density. It is known that the degree of

[0059] Therefore, the electrolyte composition according to the present invention contains a perfluorinated organic compound as an additive. By using this additive, a battery with a higher power density can be obtained compared to a battery cell without this additive. In addition, the inventors have found that by using the additive according to the present invention, They also found that any parasitic reactions with the battery were reduced. will have a longer life.

[0060] The halogen bond is strongest when the halogen is iodine (I), followed by bromine (Br) and chlorine (Cl). (Cl). Thus, the halogen is preferably iodine (I).

[0061] The additive is represented by the formula (I): XCF2-(CF2) x -CF 3-y Y y (I) where X is Cl, Br or is I, Y is Cl, Br or I, and x is 0 to 10, preferably 1 to 8, more preferably Preferably, y is an integer of 2 to 6, and y is an integer of 0 to 3, preferably 0 or 1.

[0062] The perfluoroalkyl halide according to formula (I) can be linear or branched. It can be branched.

[0063] Preferably, at least X is I. Preferably, X and Y are I. That is, That is, the perfluoroalkyl halide additive is preferably a perfluoroalkyl iodide. An example of a suitable perfluoroalkyl iodide is 1-iodoperfluoro. lobutane (i.e., X is I, x is 2, y is 0, and since y is 0, Y is I, Cl or can be either Br), 1,4-diiodoperfluorobutane (i.e. X is I, Y is I, x is 2, y is 1), 1-iodoperfluorohexane (i.e., X is I, x is 4, y is 0, and since y is 0, Y is either I, Cl, or Br. 1,6-diiodoperfluorohexane (i.e., X is I and Y is I , where x is 4 and y is 1), 1,8-diiodoperfluorooctane (i.e., X is I and Y is I, x is 6, and y is 1). However, the present invention is not limited to these.

[0064] Alternatively, X and Y can be Cl. That is, the additive is preferably Examples of suitable perfluoroalkyl chlorides include For example, 1-chloroperfluorobutane (i.e., X is Cl, x is 2, y is 0, and y is 0 so Y can be either I, Cl or Br), 1,4-dichloro perfluorobutane (i.e., X is Cl, Y is I, x is 2, y is 1), 1,6-dichloroperfluorobutane chloroperfluorohexane (i.e., X is Cl, Y is I, x is 4, y is 1) However, the present invention is not limited to this.

[0065] Alternatively, X and Y can be Br. That is, the additive is preferably Examples of suitable perfluoroalkyl bromides include For example, 1-bromoperfluorobutane (i.e., X is Br, x is 2, y is 0, and y is 0 so Y can be either I, Cl or Br), 1,4-dibromo perfluorobutane (i.e., X is Br, Y is I, x is 2, y is 1), 1,6-dibromoperfluorobutane and bromoperfluorohexane (i.e., X is Br, Y is I, x is 4, y is 1). However, the present invention is not limited to this.

[0066] The additive according to formula (I), in particular the perfluoroalkyl iodide as described above, is a first It is particularly preferred when the solvent is an ionic liquid. That is, it is known that it has high solubility in solutions with high ionic strength.

[0067] The additive may be an aromatic compound according to formula (II). C6F 6-q Z q (II) where Z is Cl, Br, I, or C a F 2a+1-b Q b Q is Cl, Br or I. q is 1 to 5, preferably 1 to 4, more preferably 1 to 3; a is 1 to 1 0, preferably 1 to 8, for example, 1 to 6, more preferably 1 to 4, and b is 2a+1 -b is chosen to be 1 or greater.

[0068] Preferably, Z is I. Examples of suitable additives according to formula (II) include 1,4 -diiodo-2,3,5,6-tetrafluorobenzene (i.e., Z is I and q is 2), 1-Iodo-2,3,4,5,6-pentafluorobenzene (i.e., Z is I and q is 1 ) can be mentioned, but is not limited to these.

[0069] Instead, Z is C a F 2a+1-b Q b Z is C a F 2a+1 -b Q b In the case of and can be branched (branched only when C is 3 or more). For example, the additive is 1-[difluoro(iodo)methyl]-2,3 ,4,5,6-pentafluorobenzene (i.e., Q is I, q is 1, a is 1, b is 1, Thus, Z can be CF2I).

[0070] Preferably, the electrolyte composition contains 0.05 to 1.0% by weight of the additive, based on the total weight of the electrolyte. 1 to 20% by weight, preferably 0.05 to 15% by weight, more preferably 0.1 to 10% by weight ,include.

[0071] Optionally, the electrolyte composition further comprises a second solvent. The second solvent acts as a diluent. Preferably, the additive is soluble in the second solvent. Preferably, the metal salt is soluble in the second solvent.

[0072] Preferably, the electrolyte, when including a second solvent, comprises, based on the total weight of the electrolyte composition, The second solvent is preferably 2 to 40% by weight, more preferably 5 to 30% by weight, and even more preferably 7 to 80% by weight. 20% by weight, for example 10-15% by weight.

[0073] The second solvent may be a hydrofluoroether, a partially fluorinated alkyl ether, or a combination thereof. The solvent may be one or more hydrofluoroethers and / or one or more partially fluoroethers. An example of the second solvent is bis(2-fluorophenyl)phenyl. ,2,2-trifluoroethyl)ether (BTFE), 1,1,2,2-tetrafluoro and 2,2,3,3-tetrafluoropropyl ether (TTE). However, this is not limited to these.

[0074] The inventors have surprisingly found that when the electrolyte composition contains the additive according to the present invention, the second The amount of solvent, when included, can be lower than the amount of electrolyte in the art. Therefore, these solvents are the most expensive compounds in the electrolyte. Therefore, the electrolyte according to the present invention and the battery cell containing such an electrolyte can be inexpensive. It is possible.

[0075] In a second aspect of the present invention, there is provided an anode-free metal battery comprising an electrolyte according to the present invention. Preferably, the anode-free battery cell is a secondary battery cell. do.

[0076] FIG. 1 shows an exemplary embodiment of an anode-free metal battery cell 1. Cell 1 is The battery cell 1 includes an anode 5 and a cathode 2. The battery cell 1 further comprises an electrolyte composition 3 according to the present invention.

[0077] Preferably, the cathode 2 is made of an alkali metal, an alkaline earth metal, or a metal of the group II of the periodic table. A preferred example of an alkali metal is lithium (Li), in which case the metal The battery cells are lithium metal (Li), sodium (Na), and potassium (K). A preferred example of an alkaline earth metal is magnesium (Mg) (in this case the battery cell is , magnesium metal battery cells), and calcium (Ca). A preferred example of the metal group is aluminum. Preferably, the metal is an alkali metal or an arsenic metal. Preferably, the metal is lithium, magnesium, aluminum. Examples of suitable cathode compositions include lithium iron phosphate ( LiFePO4, often abbreviated as LFP), Lithium Nickel Manganese Cobalt Oxide Compounds (abbreviated as NMC, for example, NMC622 and NMC811 of NMC type), Voltage spinel Lithium Manganese Nickel Oxide (often abbreviated as LNMO, LiNi 0.5 Mn 1.5 O4), and lithium manganese iron phosphate (LiMnFePO4).

[0078] Preferably, the anode 5 comprises a bare current collector. By "current collector" is meant a current collector that does not have a layer, such as a graphite layer, deposited thereon. The current collector is made of copper, Nickel, nickel-plated copper, titanium, stainless steel, or other You can become like that from now on.

[0079] The stacked battery cell 1 optionally includes a battery separator membrane 4 between the anode 5 and the cathode 2. The battery separator membrane may include at least one layer of a porous separator membrane. For example, the battery separator membrane can be a single layer membrane and can include The battery separator membrane may include two or more layers, such as three, that are adhered to one another. Each layer is made of known materials: polypropylene, polyethylene (PE), aromatic polyamide (A). ramido), or polyvinylidene fluoride (PVDF) or polytetrafluoroethylene It may comprise or consist essentially of a fluorinated compound such as PTFE. These can be loaded with ceramics if desired. For example, battery separators. The converter may contain a layer of PE sandwiched between two layers of ceramic-loaded PVDF. Preferably, at least one of the materials of the separator is chemically inert. However, while it is preferable for the porous separator to absorb the liquid electrolyte, it is chemically incompatible. Active materials often do not wet easily. This can lead to spraying on the membrane material. Surface treatments such as coating, dip coating or plasma coating (atmospheric and low pressure plasma) Alternatively, the battery separator membrane may be made of a ceramic material. It can be a fee.

[0080] Preferably, the metal of the metal salt and the metal of the anode-free battery cell are the same. Preferably, the metal salt is a lithium salt, a magnesium salt, an aluminum salt or is a sodium salt, and the battery cell is a lithium metal battery cell with a free anode, Node-free magnesium metal battery cells, anode-free aluminum metal batteries The cell, or anode, is a free sodium metal battery cell.

[0081] example Creating an anode-free battery cell and charging and discharging an anode-free lithium metal battery cell The electrical and cycle life properties were evaluated. To reduce the risk of contamination during manufacturing, The two electrode cells were prepared in a dry room with a dew point of 60°C.

[0082] The electrolyte is the one according to the present invention, and its composition is 8.00 g of LiFSI (lithium salt). ), 6.00 g of DME (first solvent), 6.00 g of 1,1,2,2-tetrafluoroethylene Ethyl-2,2,3,3-tetrafluoropropyl ether (second solvent), and 0.1 The electric potential of two electrodes according to FIG. 1 was measured using 4 g of the additive 1,4-diiodoperfluorobutane. I made a pond cell.

[0083] The electrolyte composition was 8.00 g of LiFSI (lithium salt), 6.00 g of DME (first solvent), and 6.00 g of 1,1,2,2-tetrafluoroethyl-2,2,3 A reference cell was prepared using 1,3-tetrafluoropropyl ether (second solvent). No perfluorinated compounds containing at least one halogen atom were added as additives. .

[0084] In both cells, the cathode was an LFP cathode and the anode was a bare current collector. The battery separator is a 15μm thick copper foil, and the battery separator is a ceramic road PV Both cells contained 60 μl of electrolyte. The battery cells were vacuum sealed.

[0085] The first charge-discharge test was performed on the obtained thin-film battery cell according to the present invention and the reference thin-film battery cell. -The battery was subjected to a charging sequence and then repeated charge / discharge cycles at 25°C. In the first charge of the above sequence, the output voltage was 3.6 V at 1 mA (0.13 mA / cm 2 )to The battery cell was charged. During the discharge sequence, the battery voltage was 2.8 V (1 mV) at 7.56 mA. A / cm 2 ) The battery cell was discharged until the second charge in the sequence was 1. 3.6 V at 52 mA (0.2 mA / cm 2 ) the battery cells were charged.

[0086] The specific discharge capacity was measured for each charge / discharge cycle, and the results are shown in Figure 2. The battery cell (10) and the reference battery cell (20) were subjected to charge / discharge tests up to 155 cycles. FIG. 2 shows the results of the specific discharge capacity as a function of the number of charge cycles. The specific discharge capacity of the cell (10) is always equal to or greater than the capacity of the reference battery cell (20), and At any given time it is clear that it is greater than that. [Explanation of symbols]

[0087] 1 Battery Cell 2 Cathode 3 Electrolytes 4. Separator 5 Anode 10 Profile of a battery cell containing the electrolyte composition according to the present invention 20 Profiles of battery cells containing reference electrolyte compositions

Claims

1. 1. An electrolyte composition for an anode-free metal battery cell, comprising: The metal is an alkali metal, an alkaline earth metal, or a metal from Group IIIa of the periodic table. 、 The electrolyte composition comprises: A first solvent; a salt of an alkali metal, an alkaline earth metal, or a metal from Group IIIa of the periodic table; and an additive, the salt is soluble in the first solvent; the concentration of the salt in the electrolyte composition is 2M to 3M; The additive is a perfluorinated organic compound containing at least one halogen atom other than fluorine. It is a mixture, The halogen is chlorine, bromine or iodine. Electrolyte composition comprising:

2. The metal is lithium (Li) or magnesium (Mg), whereas R, the salt is a lithium salt or a magnesium salt, The battery cell is a lithium metal battery cell or a magnesium metal battery cell. The electrolyte composition according to claim 1 .

3. The additive has the formula (I): XCF 2 -(CF 2 ) x -CF 3-y Y y (I) is a perfluoroalkyl halide conforming to the formula where X is Cl, Br or I; Y is Cl, Br or I; x is 0 to 10, preferably 2 to 6; y is 0 to 3, preferably 0 or 1. The electrolyte composition according to claim 1 .

4. X and Y are I, The additive is a perfluoroalkyl iodide.

4. The electrolyte composition according to claim 3 .

5. The additives include 1-iodoperfluorobutane and 1,4-diiodoperfluorobutane. , 1-iodoperfluorohexane, 1,6-diiodoperfluorohexane, and 1, 8-diiodoperfluorooctane 5. The electrolyte composition according to claim 4.

6. The additive has the formula (II): C 6 F 6-q Z q (II) is an aromatic compound according to where Z is Cl, Br, I or C a F 2a+1-b Q b and Q is Cl, Br or I; q is 1 to 5, preferably 1 to 3; a is 1 to 10, preferably 1 to 4; b is a value such that 2a+1-b is 1 or greater The electrolyte composition according to claim 1 .

7. The additive is 1,4-diiodo-2,3,5,6-tetrafluorobenzene.

7. The electrolyte composition according to claim 6 .

8. The additive is preferably present in an amount of 0.01 to 20% by weight based on the total weight of the electrolyte composition. or 0.1 to 10% by weight, The electrolyte composition according to claim 1 .

9. The first solvent may be a carbonate, an ether, a nitrile, a sulfone, a sulfoxide, an ester. and alkyl esters of ionic liquids; Preferably, the first solvent is 1,2-dimethoxyethane (DME) or an ionic liquid. is The electrolyte composition according to claim 1 .

10. the first solvent is an ionic liquid; The ionic liquid comprises a cation and an anion, The cation may be pyrrolidinium, piperidinium, imidazolium, cyclic saturated ammonia, arsenic, ... The anion is bis(fluorosulfonyl)imide (FSI), bis(trifluoro methanesulfonyl)imide (TFSI) or combinations thereof Consists of The electrolyte composition according to claim 9 .

11. The electrolyte composition further comprises a second solvent, The second solvent is a hydrofluoroether or a partially fluorinated alkyl ether. Teru The electrolyte composition according to claim 1 .

12. A battery cell (1) with a free anode metal, The electrolyte composition (3) according to claim 1, the metal is an alkali metal, an alkaline earth metal or a metal from Group IIIa of the periodic table; A battery cell characterized by:

13. The battery cell is a lithium metal battery cell or a magnesium metal battery cell. The battery cell according to claim 12 .

14. It is a secondary battery cell The battery cell according to claim 12 .

15. The anode (5) comprises a bare current collector The battery cell according to claim 12 .

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