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. Furthermore, the present invention relates to an anode-free metal battery cell containing an electrolyte. [Background technology]

[0002] Lithium metal batteries, magnesium metal batteries, aluminum metal batteries, sodium metal batteries Based on alkali metals, alkaline earth metals, or metals of Group IIIa of the periodic table, like a pond. Some time has passed since metal batteries like this first appeared. For example, lithium metal secondary batteries Yes. In terms of energy density, cost, and safety, optimizing this battery technology will allow... This resulted in a configuration where the anode is essentially free. Typically, it consists only of a bare current collector, such as a copper current collector. In particular, it is typically used on copper current collectors. Graphite coatings are not used.

[0003] The charge / discharge mechanism in an anode-free battery follows the classical concept / composition of the anode. Because it lacks an anode, it differs from traditional rechargeable batteries. Battery cells also use alkali metals, alkaline earth metals, or metals from the periodic table III as electrolytes. Even in group A metals, it does not contain an excess amount. However, despite the absence of an anode, 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 the charge This is because metal ions accumulate on the anode current collector in the current. It forms deposited lithium together with a solid electrolyte interphase (SEI). This deposited lithium is the only lithium available for the discharge of the battery cell, i.e., there is no active lithium source on the anode side. This significantly reduces the safety risks that may occur in lithium metal batteries. As a result, the consumption of the electrolyte and the formation of unusable alkali metals or alkaline earth metals lead to capacity loss and performance degradation of the battery cell. Therefore, for the system to function efficiently, it is necessary that all cell components are perfectly adjusted to each other. This remains a challenge at present. The electrolyte is an important component in any battery cell. The electrolyte acts as a carrier for ions of alkali metals or alkaline earth metals. Also, the electrolyte is the main contact medium between interfaces. International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt.

[0004] As a result, the consumption of the electrolyte and the formation of unusable alkali metals or alkaline earth metals lead to capacity loss and performance degradation of the battery cell. Therefore, for the system to function efficiently, it is necessary that all cell components are perfectly adjusted to each other. This remains a challenge at present. The electrolyte is an important component in any battery cell. The electrolyte acts as a carrier for ions of alkali metals or alkaline earth metals. Also, the electrolyte is the main contact medium between interfaces. International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt. As a result, the consumption of the electrolyte and the formation of unusable alkali metals or alkaline earth metals lead to capacity loss and performance degradation of the battery cell. Therefore, for the system to function efficiently, it is necessary that all cell components are perfectly adjusted to each other. This remains a challenge at present.

[0005] The electrolyte is an important component in any battery cell. The electrolyte acts as a carrier for ions of alkali metals or alkaline earth metals. Also, the electrolyte is the main contact medium between interfaces. International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt. As a result, the consumption of the electrolyte and the formation of unusable alkali metals or alkaline earth metals lead to capacity loss and performance degradation of the battery cell. Therefore, for the system to function efficiently, it is necessary that all cell components are perfectly adjusted to each other. This remains a challenge at present.

[0006] International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt. International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt. International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt. International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt. International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt. International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt. International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt. International Patent Application WO2021213743 discloses a cathode-free lithium-ion battery comprising a cathode including a current collector, a current collector as an anode, a liquid electrolyte between the current collectors of the anode and the cathode, and a separator. This liquid electrolyte contains at least one type of lithium salt and a solvent mixture of at least 70% by volume based on the total volume of the electrolyte composition. This solvent mixture contains at least one type of fluorinated ether compound and at least one type of non-fluorinated ether compound. However, while the addition of the fluorinated ether compound makes it possible to reduce the overall concentration of the lithium salt, the fluorinated ether compound is known to be hardly or not at all soluble in the lithium salt. Therefore, the local concentration of lithium salts in unfluorinated ether compounds is high. As a result, despite the low overall concentration of lithium salts, the solvent mixture remains mixed. This mixture can cause undesirable precipitation of lithium salts.

[0007] Electrolytes known to be used in anode-free metal battery cells are, so to speak These are high-concentration electrolytes (HCEs) or ultra-high-concentration electrolytes. Typically, such electrolytes are , metal salts with concentrations greater than 3M, often 4M or more, and even 5.5M, That is, it contains alkali metal salts or alkaline earth metal salts. An example is dimethyl carbonate with 5.5 M lithium bis(fluorosulfonyl)imide. (LiFSI) is included, which is stable, has a high cathode voltage, and uses an aluminum current collector. To prevent corrosion. 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 during MC improves the Coulomb efficiency of lithium metal anodes to 99.2%. It is disclosed that it is possible to make it happen.

[0008] The salts used often contain fluorine. Thanks to the high anion concentration of the salt, the anode A SEI with a high concentration of fluorine is formed in both the cathode and the surrounding atmosphere. As a result, Reduces or suppresses the formation of dendritic crystals on metal surfaces, and prevents plating / stripping (charging / discharging) of battery cells. ) Coulomb efficiency increases.

[0009] Another concept of electrolytes is localized hyperconcentration electrolytes (LHCE) or localized ultra-high concentration electrolytes. Yes, these are salt-solvent cavities that form between the electrolyte solvent and the salt when the salt dissolves in the solvent. To reduce the overall salt concentration in the final electrolyte composition while maintaining the concentration of the raster. Although a diluent is necessary, the concentration remains higher than 3M. The diluent is highly concentrated. It is inert to electrolytes, and salts are little to no soluble. Also, diluents are soluble. It readily mixes with the mediating solvent and prevents phase separation. Furthermore, the diluent is present in the formed electrolyte. It is necessary to maintain high concentrations of salt-solvent clusters. In other words, the diluent is HCE The local coordination environment is maintained, that is, the coordination of Li with the solvating solvent. + Aeon's distribution Li + It has low solvation ability for ions. The diluent is a Li salt. It surrounds the solvation solvent of the nion and HCE.

[0010] International patent application WO2020106762 relates to local ultra-high concentration electrolytes (LSEs) (local High-concentration electrolytes (also called LHCEs) and implementations of devices containing such LSEs The state is disclosed. LSE is a rechargeable alkaline battery containing anode-free battery cells. Used in metal and alkaline ion batteries. The electrolyte consists of an activated salt and a substance in which the activated salt is soluble. The solvent comprises a solvent and a diluent in which the activated salt is insoluble or poorly soluble. The diluent is a fluorinated oil. It is a formate salt. The salt can be dissolved at concentrations greater than 3M, such as greater than 3M and up to 10M. It is present in the medium. Due to the low solubility of the salt in the diluent, the concentration of the salt becomes locally high. As a result, undesirable precipitation of the salt occurs in the solvent mixture. This is especially evident in elephants during storage.

[0011] A disadvantage of such high-concentration or ultra-high-concentration electrolytes is that the salt must be highly soluble in the solvent. There are times when this is necessary. Another disadvantage is that locally high salt concentrations can lead to a decrease in the desired salt content in the electrolyte. Undesirable precipitates may form. Also, the dissociation constants of the salt are HCE and L. It must be high in HCE. Therefore, several types of salts are commonly used. It cannot be used. Also, the amount of diluent added to the electrolyte increases considerably. There are some drawbacks. Since diluents are often very expensive, electrolytes become costly as well. [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] The present invention aims to overcome one or more of the above-mentioned problems. One of the objectives of the present invention is This is an electrolyte composition for anode-free metal battery cells, which has the risk of salt precipitation. The objective is to provide something that significantly reduces the amount of salt used. The present invention further uses a wide range of commercially available salts. The objective is to provide an electrolyte composition that can be used. The present invention further relates to known The objective is to provide electrolytes that are cheaper than conventional electrolytes.

[0013] Furthermore, this invention enables the formation of stable SEI, and also has a high power density and is fully charged. A metal battery cell with an anode free that exhibits good stability against repeated discharge The aim is to provide. The present invention further provides a longer lifespan, i.e., known A an anode that can charge and discharge more than a free metal battery cell. The objective is to provide a metal battery cell that is free of [unclear]. The present invention further provides an inexpensive [unclear]. The objective is to provide a metal battery cell that is free of carbon dioxide.

[0014] In relation to the present 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 described in the appended claims. The present invention relates to an electrolyte composition for which the first solvent, a metal salt, and an additive The electrolyte composition may further contain a second solvent, if desired. ru.

[0016] The aforementioned metal salt is an alkali metal, alkaline earth metal, or a metal of Group IIIa of the periodic table. It contains or is substantially composed of salts. Preferably, the metal is lithium, magnesium It is um, sodium, or aluminum, 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 can be dissolved in the first solvent. Preferably, the electrolyte If the composition contains 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 1M, more preferably 2M-3M.

[0018] Preferably, the solvent in the first step is a carbonate, ether, nitrile, sulfone, or sulfo Selected from the group consisting of oxides, esters, and alkyl esters of ionic liquids. For example If the first solvent contains or is substantially contained in 1,2-dimethoxyethane (DME) It is possible to become.

[0019] Ionic liquids are non-molecular compounds consisting only of ions, i.e., anions and cations. It is included in the category. In relation to the present invention, the first solvent in the electrolyte composition is preferred. Suitable ionic liquids are preferably pyrrolidinium, piperidinium, and cyclic saturated ammonia. Contains cations containing or substantially derived from nium, or combinations thereof. Interestingly, the aforementioned anion is bis(fluorosulfonyl)imide (FSI), bis( Trifluoromethanesulfonyl)imide (TFSI) or combinations thereof It will essentially become that from now on.

[0020] The additive is a perfluorinated organic compound further comprising at least one halogen atom. Yes. The halogen is chlorine (Cl), bromine (Br), or iodine (I). Preferred In particular, the additive can be dissolved in the first solvent. Preferably, the additive The additive can be dissolved in the second solvent.

[0021] The aforementioned additive is given by formula (I), XCF2-(CF2) x -CF 3-y Y y (I) It can be a perfluoroalkyl halide according to the formula, where X is Cl, Br or I is , Y is Cl, Br or I, and x is 0 to 10, preferably 1 to 8, more preferably The value of y is between 2 and 6, and y is between 0 and 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 perfluoroalkyl iodide. Examples of perfluoroalkyl iodides include 1-iodoperfluorobutane ( that is, X is I, x is 2, y is 0, and since y is 0, Y can be either I, Cl, or Br), 1,4-diiodoperfluorobutane (that is, X is I , Y is I, x is 2, y is 1), 1-iodoperfluorohexane (that is, 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 (that is, X is I, Y is I, x is 4, y is 1), 1,8-diiodoperfluorooctane (that is, X is I, Y is I, x is 6 , y is 1). However, it is not limited thereto. When the first solvent is an ionic liquid, the additive according to formula (I), particularly perfluoroalkyl iodide, is particularly preferred. Such additives have high solubility in ionic liquids, that is, in solutions with high ionic strength.

[0023] The additive can be an aromatic compound according to formula (II), where Z is Cl, Br, I, or C F

[0024] Q C6F 6-q Z q (II) where Z is Cl, Br, I, or C a F 2a+1-b Q b where Q is Cl, Br, or I, q is 1 to 5, preferably 1 to 4, more preferably 1 to 3, and a is 1 to 10, preferably 1 to 6, more preferably 1 to 4, and b is a value such that 2a + 1 - b is 1 or more.

[0025] Preferably, Z is I. Examples of suitable additives following formula (II) include 1,4 -Diiodo-2,3,5,6-tetrafluorobenzene (i.e., Z is I, q is 2), 1-Iodo-2,3,4,5,6-pentafluorobenzene (i.e., Z is I, q is 1) ) are some examples. However, this is not limited to these.

[0026] Preferably, the electrolyte composition is measured based on the total weight of the electrolyte composition. The additive should be 0.01 to 20% by weight, preferably 0.05 to 15% by weight, more preferably 0. Contains 1-10% by weight.

[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, including or substantially You can become that target from now on.

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

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

[0030] Preferably, the metal of the metal salt and the metal of the battery cell with the anode free are the same. Yes. Preferably, the metal salt is a lithium salt or a magnesium salt, and the battery Each cell is either an anode-free lithium metal battery cell or an anode-free magnesium This is a nesium metal battery cell.

[0031] Preferably, the anode of the battery cell with a free anode includes a bare current collector. A bare current collector, in relation to the present invention, is a current collector that does not have a layer such as a graphite layer deposited on top of it. It means an electric body.

[0032] The electrolyte composition according to the present invention is an anode-free metal electrode that allows for stable SEI formation. This makes it possible to obtain a battery cell. Furthermore, the electrolyte according to the present invention is suitable for repeated charging and discharging. This makes it possible to obtain a higher specific discharge capacity. In other words, the electrolyte according to the present invention is charged This makes it possible to improve the stability of battery cells when repeatedly charging and discharging them.

[0033] Furthermore, a wide range of commercially available metal salts can be used in the electrolyte composition according to the present invention. This makes it possible to obtain battery cells that have the properties necessary for the intended application. It has the advantage of reducing metal loss, so-called "dead metals". This avoids the occurrence of "etal" and thereby increases the lifespan and power density of the battery cells. Yes, it is possible. This desirable effect is further reduced anion mobility in the electrolyte according to the present invention. The strength increases as the number of metal ions that can move increases.

[0034] Furthermore, the presence of a second solvent, such as a diluent, is not a mandatory condition for electrolytes; it is present when necessary. In some cases, a small amount is sufficient, which is an advantage. However, the diluent is known to be expensive. The electrolyte according to the present invention is less expensive than electrolytes known in the art. can.

[0035] Several aspects of the present invention will be described in detail with reference to the attached drawings. On a plane, the same reference numeral represents the same object. [Brief explanation of the drawing]

[0036] [Figure 1] This diagram schematically shows the configuration of a metal two-electrode cell with an anode-free design. [Figure 2] Figure 1 shows the specific capacity of the two-electrode cell, and the electrolytes do not contain additives (reference battery cell) or perfluoroalkyl iodide additives (battery cell according to the present invention). [Modes for carrying out the invention]

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

[0038] The aforementioned metal salt is a salt of an alkali metal, an alkaline earth metal, or a metal from Group IIIa of the periodic table. It includes or substantially consists of alkali metals. Preferred examples of alkali metals are lithium (Li), na These are thorium (Na) and potassium (K). Preferred examples of alkaline earth metals include magnesium. These are magnesium (Mg) and calcium (Ca). Preferred examples of Group IIIa metals are A It is luminium (Al). Preferably, the metal is substantially lithium, magnesium. It consists of sium, aluminum, or sodium, preferably lithium or magnesium. .

[0039] The electrolyte composition may contain a combination of two or more metal salts. If the above metal salts exist, these metal salts may contain the same metal, in particular, all These salts can be lithium salts, or these metal salts can contain different metals. This is possible, and in particular, it can contain lithium salts and magnesium salts.

[0040] An example of a lithium salt that can be used in the electrolyte composition according to the present invention is Hexafull Lithium orophosphate (LiPF6), lithium perchlorate (LiClO4), hexafluoro Lithium arsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), bis(o Lithium borate (LiBOB), difluoro(oxalato) lithium borate ( LiDFOB), lithium trifluoromethanesulfonate (LiTf), lithium bis( Trifluoromethanesulfonyl)imide (LiTFSI), Lithium bis(fluorosulfonyl)imide Examples include honylimide (LiFSI) and its derivatives. However, it is not limited to these. I can't.

[0041] Preferably, the derivatives of LiFSI and LiTFSI are lithium bis(R-s (R)imide and lithium (R 1 ,R 2 Examples include sulfonyl)imide salts. This is not limited to this. Here, R, R 1 , R 2is an alkyl group that is at least partially fluorinated. For example , R 1 and R 2 These are fluoromethyl, trifluoromethyl, and pentafluoroethyl, independently of each other. It can be nonafluorobutyl. An example of such a derivative is lithium ( Fluorosulfonyl)(trifluoromethanesulfonyl)imide, and lithium (penta Examples include fluoroethanesulfonyl (trifluoromethanesulfonyl)imides.

[0042] Examples of magnesium salts include magnesium perchlorate (Mg(ClO4)2), magnesium Umbis(trifluoromethanesulfonimide)(Mg(TFSI)2), and formula, Mg(((R 3 R 4 R 5 R 6 )B)2 Examples include magnesium (fluoroalkoxy) borate. However, it is not limited to this. stomach. Here, R 3 , R 4 , R 5 and R 6 is a fluorinated alkoxy group, at least partially. R 3 ~R 6 Two or more of these can be the same, or R 3 ~R 6 They are different from each other It is possible. R 3 ~R 6 One or more of them may be completely fluorinated. In particular, R 3 ~R 6 This can be a monodentate ligand or a bidentate ligand. Such magnesium salt Examples are as follows:

[0043] JPEG0007853459000001.jpg31161

[0044] Examples of sodium salts include sodium perchlorate (NaClO4) and hexafluorocarbons. Sodium hexafluoroarsenate (NaPF6), sodium hexafluoroarsenate (NaAsF6), tetra Sodium fluoroborate (NaBF4), sodium trifluoromethanesulfonate ( NaTf), sodium bis(trifluoromethanesulfone)imide (NaTFSI), And sodium bis(fluorosulfonyl)imide (NaFSI) is another example. This is not limited to these.

[0045] Preferably, the derivatives of NaFSI and NaTFSI are sodium bis(R- Sulfonyl)imides, and sodium (R 1 ,R 2 Examples include sulfonyl)imide salts. However, this is not limited to this. Here, R, R 1 , R 2 is an alkyl group that is at least partially fluorinated. For example , R 1 and R 2 These are fluoromethyl, trifluoromethyl, and pentafluoroethyl, independently of each other. It can be nonafluorobutyl. An example of such a derivative is sodium (Fluorosulfonyl)(trifluoromethanesulfonyl)imide, and sodium (pe Examples include trifluoromethanesulfonyl (trifluoromethanesulfonyl)imide. .

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

[0047] The inventors found that at these appropriate salt concentrations, the solubility of the metal salt in the first solvent is We found that a high dissociation constant is not necessary. Therefore, a wide range of commercially available gold... The salt can be used in the electrolyte composition according to the present invention.

[0048] The inventors further discovered, surprisingly, that at such a moderate salt concentration, the gold in the solvent... Formation of a stable SEI layer with an appropriately high concentration of fluoride ions without impairing the solubility of the group salt. We found that it is possible to obtain fluorine in SEI, as is known in this field. The presence of ions results in the formation of inactive metals (i.e., separated and electrically isolated metals). As the amount decreases significantly, the overall metal loss tends to be suppressed. It prevents the decomposition of electrolytes. As a result, efficiency loss is reduced, and even prevented, and Coulomb Efficiency may improve. Therefore, the presence of fluoride ions in the SEI layer is beneficial for battery cells. This contributes to improving its performance.

[0049] The electrolyte composition according to the present invention further comprises a first solvent. Preferably, the electrolytic The quality is determined based on the total weight of the electrolyte composition, with the first solvent being 2-40% by weight, preferably 5%. Including 30% by weight, more preferably 7-20% by weight, for example 10-15% by weight.

[0050] The first solvent is an alkyl ester of carbonate, ether, nitrile, sulfone, or sulfopropyl carbonate. containing organic solvents such as sides, esters, or any two or more combinations thereof In practical terms, it's something that can be achieved from now on.

[0051] Examples of organic solvents include 1,2-dimethoxyethane (DME) and dimethyl carbonate. ethylene carbonate, ethyl methyl carbonate, dimethyl ether, dimethoxyethyl ether Tan, tetrahydrofuran, dioxane, 1,3-dioxolane, tetraethylene glyco Dimethyl ether, acetonitrile, succinonitrile, adiponitrile, sulfol Examples include dimethyl sulfoxide, methyl acetate, and methyl propionate. This is not limited to these.

[0052] Alternatively, and / or additionally, the first solvent may include or be substantially an ionic liquid. Ionic liquids can be composed of ions, i.e., anions and cations, only. These are included in the category of non-molecular compounds. They have negligible vapor pressure and high thermal stability at room temperature. It is known to have this property, and as a result, it can be used instead of or instead of traditional (organic) solvents. In addition, it is suitable for use in other applications.

[0053] In relation to the present invention, a suitable ionic liquid as the first solvent in the electrolyte composition is a preferred ionic liquid. In particular, pyrrolidinium, piperidinium, imidazolium, and cyclic saturated ammonium cations containing or substantially derived from ammonium or combinations thereof. It includes. Cyclic saturated ammonium can be expressed according to the following formula (III): where X is It is either CH2 or O, and n is 1 to 3.

[0054] JPEG0007853459000002.jpg21158

[0055] In relation to the present invention, a suitable ionic liquid as the first solvent in the electrolyte composition is preferred. In particular, bis(fluorosulfonyl)imide (FSI), bis(trifluoromethanesulfonyl) Honylimide (TFSI), hexafluorophosphate, dicyanamide, tetrachlorophosphate Anions comprising luminates, or combinations thereof, or substantially derived therefrom. Preferred examples of anions are bis(fluorosulfonyl)imide (FSI) and bis( It is called tetrafluoromethanesulfonylimide (TFSI).

[0056] The additive to the electrolyte composition according to the present invention contains at least one further halogen atom It is a perfluorinated organic compound. Preferably, the halogen is chlorine (Cl) or bromine. The additive is (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, this compound They discovered that halogen atoms in substances bond with anions in metal salts. Salt anions and additives The interaction of halogen bonds between halogen atoms is similar to the interaction between the anion and cation of a metal salt. It was found to be strong enough to destroy the interaction. Therefore, such halogen bonds The compound allows the metal ions of the metal salt to move freely. Also, halides and anions The halogen bond between the anions reduces the mobility of the anions. As a result, the alkali in the electrolyte This can increase the number of ions that can move between metallic or alkaline earth metals.

[0058] The number of moves is, in this case, the alkali metal or alkaline earth metal cation relative to the total current. It is defined as the ratio of currents derived from a certain cation. When the number of moves is large, the charging station This reduces the concentration imbalance of the electrolyte during the top and discharge steps, and therefore, power density is reduced. It is known that the degree can be increased.

[0059] Therefore, perfluorinated organic compounds are used as additives in the electrolyte composition according to the present invention. By using this additive, a battery with a higher power density can be produced compared to a battery cell without this additive. Cells can be obtained. Furthermore, the inventors have found that by using the additive according to the present invention, Furthermore, it was found that all parasitic reactions with the battery were also reduced. This reduction is due to the battery cells Its lifespan will increase.

[0060] The halogen bond is strongest when the halogen is iodine (I), and also strongest when the halogen is bromine (Br) and chlorine. (Cl) follows. Therefore, the halogen is preferably iodine(I).

[0061] The additive is given by formula (I), XCF2-(CF2) x -CF 3-y Y y (I) It can be a perfluoroalkyl halide according to the following: where X is Cl, Br or x is I, Y is Cl, Br or I, x is 0 to 10, preferably 1 to 8, more Preferably, y is 2 to 6, and y is 0 to 3, preferably 0 or 1.

[0062] Perfluoroalkyl halides according to formula (I) can be linear, and also fractional It can be branched or in a chain-like structure.

[0063] Preferably, at least X is I. Preferably, X and Y are I. The perfluoroalkyl halide additive is preferably a perfluoroalkyl halide. It is a perfluoroalkyliodide. A suitable example of a perfluoroalkyliodide is 1-iodoperfluor. Lobutan (that is, X is I, x is 2, y is 0, and since y is 0, Y is I, Cl or (which can be either Br), 1,4-diiodoperfluorobutane (that is, (where X is I, Y is I, x is 2, y is 1), 1-iodoperfluorohexane (that is, X is I, x is 4, y is 0, and since y is 0, Y is either I, Cl or Br. (can be), 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 Examples include (I, x = 6, y = 1). However, this is not limited to these examples.

[0064] Alternatively, X and Y can be Cl. That is, the additive is preferable. These are perfluoroalkyl chlorides. Examples of suitable perfluoroalkyl chlorides include So, 1-chloroperfluorobutane (that is, X is Cl, x is 2, y is 0, y Since it is 0, Y can be I, Cl or Br), 1,4-dichloro Perperfluorobutane (i.e., X is Cl, Y is I, x is 2, y is 1), 1,6-dichloromethyl One example is loloperfluorohexane (i.e., X is Cl, Y is I, x is 4, y is 1). This is not limited to the above.

[0065] Alternatively, X and Y can be Br. That is, the additive is preferable. , a perfluoroalkyl bromide. Examples of suitable perfluoroalkyl bromides include So, 1-bromoperfluorobutane (that is, X is Br, x is 2, y is 0, y Since Y is 0, Y can be I, Cl, or Br), 1,4-dibro Moperfluorobutane (i.e., X is Br, Y is I, x is 2, y is 1), 1,6-dibutane One example is romoperfluorohexane (i.e., X is Br, Y is I, x is 4, y is 1). This is not limited to the above.

[0066] Additives according to formula (I), in particular perfluoroalkyl iodides as described above, are first This is particularly preferable when the solvent is an ionic liquid. Such molecules in an ionic liquid In other words, it is known to have high solubility in solutions with high ionic strength.

[0067] The additive can be an aromatic compound following formula (II). C6F 6-q Z q (II) Here, Z is Cl, Br, I, or C a F 2a+1-b Q b And Q is Cl, Br or I Yes, q is 1 to 5, preferably 1 to 4, more preferably 1 to 3, and 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 selected so that it is 1 or greater.

[0068] Preferably, Z is I. Examples of suitable additives following formula (II) include 1,4 -Diiodo-2,3,5,6-tetrafluorobenzene (i.e., Z is I, q is 2), 1-Iodo-2,3,4,5,6-pentafluorobenzene (i.e., Z is I, q is 1) ) are some examples. However, this is not limited to these.

[0069] Instead, Z is C a F 2a+1-b Q b Therefore, Z is C a F 2a+1 -b Q b In this case, it is linear. It can be branched, and it can also be branched (it is branched only when C is 3 or more). (This is possible). For example, the additive is 1-[difluoro(iodo)methyl]-2,3 ,4,5,6-pentafluorobenzene (that is, Q is I, q is 1, a is 1, b is 1, Therefore, Z can be CF2I).

[0070] Preferably, the electrolyte composition contains additives based on the total weight of the electrolyte, in a ratio of 0.0 1-20% by weight, preferably 0.05-15% by weight, more preferably 0.1-10% by weight ,include.

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

[0072] Preferably, if the electrolyte contains a second solvent, the total weight of the electrolyte composition is based on Then, add the second solvent in an amount of 2-40% by weight, preferably 5-30% by weight, more preferably 7% by weight. Including 20% ​​by weight, for example, 10-15% by weight.

[0073] The second solvent is hydrofluoroether, partially fluorinated alkylether, Or may include or substantially consist of a combination thereof. For example, the melt The medium is one or more types of hydrofluoroethers and / or one or more types of partially fluorinated It may contain bis(2) alkyl ethers. An example of a second solvent is bis(2) ,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl Roethyl-2,2,3,3-tetrafluoropropyl ether (TTE) is one example. However, this is not limited to these examples.

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

[0075] In a second aspect of the present invention, an anode-free metal battery containing the electrolyte according to the present invention A cell is provided. Preferably, a battery cell with an anode free is a secondary battery cell. ru.

[0076] Figure 1 shows an exemplary embodiment of a metal battery cell 1 with an anode free. Cell 1 is It can have a stacked structure. Battery cell 1 includes an anode 5 and a cathode 2. The pond cell 1 further contains the electrolyte composition 3 according to the present invention.

[0077] Preferably, cathode 2 is an alkali metal, an alkaline earth metal, or a metal from the periodic table II. Includes metals of Group Ia. A preferred example of an alkali metal is lithium (Li) (in this case, a metal). The battery cell is a lithium metal battery cell, and contains sodium (Na) and potassium (K). Yes. 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). Group IIIa metal A preferred example of the genus is aluminum. Preferably, the metal is an alkali metal or an a It is a rutile earth metal. Preferably, the metal is lithium, magnesium, or aluminum. It is either nium or sodium. Examples of suitable cathode compositions include lithium iron phosphate. LiFePO4 (often abbreviated as LFP), lithium nickel manganese cobalt acid Monsters (abbreviated as NMC, for example, NMC-type NMC622 and NMC811), high Voltage Spinel Lithium Manganese Nickel Oxide (often abbreviated as LNMO LiNi) 0.5 Mn 1.5 Examples include O4 and lithium iron manganese phosphate (LiMnFePO4).

[0078] Preferably, the anode 5 includes a bare current collector. A bare current collector is a component related to the present invention. This refers to a current collector that does not have a layer like a graphite layer deposited on top. The current collector is made of copper. containing or substantially containing one or more of nickel, nickel-plated copper, titanium, and stainless steel. You can become that target from now on.

[0079] The stacked battery cell 1 optionally includes a battery separator film 4 between the anode 5 and the cathode 2. It is possible to do so. The battery separator membrane has at least one layer of porous separator membrane It can include. For example, the battery separator film can be a single-layer film, and also, It may include two or more layers, for example three, that adhere to each other. (Battery separator film) Each layer is made of known materials: polypropylene, polyethylene (PE), aromatic polyamide (A). Lamid, or polyvinylidene fluoride (PVDF) or polytetrafluoroethylene It may contain or be substantially derived from fluorinated compounds such as (PTFE). These can be loaded with ceramics as desired. For example, battery separators The tar can include a PE layer sandwiched between two layers of ceramic load PVDF. Preferably, at least one of the separator materials is chemically inert. However, while it is preferable for the porous separator to absorb the liquid electrolyte, chemically it is not Active materials are often not easily wetted. For this reason, when spraying a film material, Surface treatments such as coating, dip coating, or plasma coating (atmospheric pressure plasma or low-pressure plasma) Alternatively, the battery separator film can be coated. It can be a material.

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

[0081] example Creating anode-free battery cells and charging anode-free lithium metal battery cells The properties of electricity and cycle life were evaluated. To reduce the risk of contamination during manufacturing, - Two electrode cells were fabricated in a drying chamber with a dew point of 60°C.

[0082] The electrolyte is as described in 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-tetrafluoro Ethyl-2,2,3,3-tetrafluoropropyl ether (second solvent), and 0.1 The additive is 1,4-diiodoperfluorobutane, and the two electrodes are connected according to Figure 1. I made a pond cell.

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

[0084] In both battery cells, the cathode is an LFP cathode, and the anode is a bare current collector. The copper foil is 15 μm thick, and the battery separator consists of two ceramic load PV It was a three-layer film including a PE layer sandwiched between DF layers. Both battery cells contained 60 μl of electrolyte. These battery cells were vacuum sealed.

[0085] The thin-film battery cell and reference thin-film battery cell obtained according to the present invention are subjected to a first charge-discharge procedure. -The charging sequence was performed, and then repeated charge / discharge cycles were carried out at 25°C. During the initial charge of the sequence, 3.6V (0.13mA / cm²) was achieved at 1mA. 2 )to The battery cell was charged. During the discharge sequence described above, 2.8V (1m) was obtained at 7.56mA. A / cm 2 The battery cells were discharged to ). In the second charge of the above sequence, 1. 3.6V at 52mA (0.2mA / cm²) 2 The battery cells were charged up to this point.

[0086] The specific discharge capacity was measured for each charge-discharge cycle, and the results are shown in Figure 2. Figure 2 shows the present invention. Regarding the battery cell (10) and reference battery cell (20) related to this, up to 155 charge cycles The results for the specific discharge capacity according to the number of battery cycles are shown in Figure 2. The specific discharge capacity of cell (10) is always greater than or equal to the capacity of the reference battery cell (20), and almost It is clear that at all times it is greater than that. [Explanation of symbols]

[0087] 1 battery cell 2 Cathodes 3 Electrolytes 4 Separators 5 Anodes 10 Profile of a battery cell containing the electrolyte composition according to the present invention 20 Battery cell profiles containing electrolyte compositions for reference

Claims

1. An electrolyte composition for an anode-free metal battery cell, The aforementioned metal is an alkali metal, an alkaline earth metal, or a metal of Group IIIa of the periodic table. The electrolyte composition is The first solvent and Alkali metals, alkaline earth metals, or salts of metals in Group IIIa of the periodic table, Includes additives, The salt can be soluble in the first solvent. The concentration of the salt in the electrolyte composition is 2 M to 3 M. The additive is a perfluorinated organic compound that, in addition to fluorine, contains at least one halogen atom having a strong interaction with the anion of the metal salt to the extent that it breaks the bond between the anion and the cation and bonds with the anion, thereby increasing the number of metal ions that can move in the electrolyte. The halogen is chlorine, bromine, or iodine. The aforementioned additive is of formula (I), XCF 2 -(CF 2 ) x -CF 3-y Y y (I) It is a perfluoroalkyl halide that conforms to the following rules. Here, X is Cl, Br, or I. Y is Cl, Br, or I. x is between 0 and 10. y is between 0 and 3. An electrolyte composition characterized by the following features.

2. The aforementioned metal is lithium (Li) or magnesium (Mg), and for each of these, The salt is a lithium salt or a magnesium salt. The battery cell is either a lithium metal battery cell or a magnesium metal battery cell. The electrolyte composition according to claim 1.

3. X and Y are I, The aforementioned additive is a perfluoroalkyl iodide. The electrolyte composition according to claim 1 or claim 2, which references claim 1.

4. The additive is selected from the group consisting of 1-iodoperfluorobutane, 1-iodoperfluorohexane, 1,6-diiodoperfluorohexane, and 1,8-diiodoperfluorooctane. The electrolyte composition according to claim 3.

5. The additive is contained in an amount of 0.01 to 20% by weight, based on the total weight of the electrolyte composition. The electrolyte composition according to claim 1.

6. The first solvent is selected from the group consisting of carbonate esters, ethers, nitriles, sulfones, sulfoxides, esters, and ionic liquids. The electrolyte composition according to claim 1.

7. The first solvent is an ionic liquid, The aforementioned ionic liquid contains cations and anions, The aforementioned cation includes or substantially consists of pyrrolidinium, piperidinium, imidazolium, cyclic saturated ammonium, or combinations thereof. The anion includes or is substantially derived from bis(fluorosulfonyl)imide (FSI), bis(trifluoromethanesulfonyl)imide (TFSI), or a combination thereof. The electrolyte composition according to claim 6.

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

9. A metal battery cell (1) with a free anode, The electrolyte composition (3) according to claim 1 comprises, The battery cell is characterized in that the aforementioned metal is an alkali metal, an alkaline earth metal, or a metal of Group IIIa of the periodic table.

10. The battery cell is either a lithium metal battery cell or a magnesium metal battery cell. The battery cell according to feature 9.

11. It is a secondary battery cell. The battery cell according to feature 9.

12. The anode (5) includes a bare current collector. The battery cell according to feature 9.

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