Electrolyte and battery containing the electrolyte

Abstract

The present invention is an electrolyte comprising a porous insulator having pores, a medium having two nitrile groups disposed within the pores, and a metal salt, the metal salt being at least one selected from the group consisting of alkali metal salts and alkaline-earth metal salts, and the molar ratio of the medium to the metal salt (medium / metal salt) is 0.1 to 4.0.

Description

[Technical Field]

[0001] The present disclosure relates to electrolytes and batteries comprising the electrolytes. [Background technology]

[0002] Batteries include air batteries, fuel cells, secondary batteries, etc., and are used for a variety of purposes. Batteries include a positive electrode and a negative electrode, and an electrolyte that transports ions between the positive electrode and the negative electrode.

[0003] For example, Patent Document 1 discloses an insulating structure made of a porous coordination polymer having metal salt coordinated unsaturated sites and a [R-SO2-N-SO2-R'] - (R and R' represent fluorine atoms or fluoroalkyl groups) and a metal cation (e.g., Li + , Na + , or Mg 2+ ) and an ion-conductive composite (electrolyte) comprising the same is disclosed.

[0004] Furthermore, Patent Document 2 discloses an electrolyte regulator that can be used in metal batteries, the electrolyte regulator comprising a liquid electrolyte and a metal-organic framework (MOF) material that is incorporated into the liquid electrolyte to form a MOF slurry electrolyte, where MOFs are a class of crystalline porous solids constructed from metal cluster nodes and organic linkers, and that are capable of binding anions, removing ion pairs, and enhancing cation transport upon activation and impregnation with the liquid electrolyte. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6222635 [Patent Document 2] Special Publication No. 2020-508542 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have realized that there are still problems to be overcome with the above electrolytes and have found the need to take measures to solve these problems. Specifically, the present inventors have found that there is room for improvement in the ionic conductivity of the electrolytes.

[0007] The present disclosure has been made in view of the above-mentioned problems. That is, a main object of the present disclosure is to provide an electrolyte having superior ionic conductivity compared to conventional electrolytes. [Means for solving the problem]

[0008] The present inventors attempted to solve the above problems by taking a new approach rather than simply extending the conventional technology, and as a result, they have invented an electrolyte that achieves the above-mentioned main object.

[0009] The electrolyte according to one embodiment of the present disclosure comprises: A porous insulator having pores, a medium having two nitrile groups and a metal salt disposed in the pores, the metal salt is at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts, The molar ratio of the medium to the metal salt (medium / metal salt) is 0.1 or more and 4.0 or less.

[0010] Moreover, the battery according to an embodiment of the present disclosure comprises: The electrolyte is as described above. [Effects of the Invention]

[0011] The present disclosure can provide an electrolyte with superior ionic conductivity. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a conceptual diagram showing an example of a battery according to a second embodiment of the present disclosure. [Figure 2]FIG. 2 is a graph showing the relationship between the molar ratio (SN / LiFSI) and the ionic conductivity at room temperature. [Figure 3] FIG. 3 shows Raman spectra of the electrolytes of Examples 2 to 3, Examples 5 to 7 and Comparative Example 1 in the range of 2220 to 2320 cm −1 . DETAILED DESCRIPTION OF THE INVENTION

[0013] The "electrolyte" and "battery" including the electrolyte of the present disclosure will be described in detail below with reference to the following embodiments. While the description will be made with reference to the drawings as needed, the contents shown in the drawings are merely shown as a schematic example for the purpose of understanding the present disclosure, and the appearance and dimensional ratios may differ from the actual products.

[0014] Numerical ranges mentioned in this specification are intended to include the lower and upper limit values ​​themselves, unless otherwise specified, such as "less than," "smaller," or "greater than." That is, for example, a numerical range such as 1 to 10 is interpreted as including the lower limit of 1 and the upper limit of 10.

[0015] In this specification, "a target component is substantially composed of a specific material" or "a target component consists of a specific material" means that the target component contains the specific material at a ratio of 95% by mass or more, 97% by mass or more, 99% by mass or more, or 100% by mass. For example, "mesoporous silica is substantially composed of silica (SiO2)" means that the mesoporous silica contains silica (SiO2) at a ratio of 95% by mass or more, 97% by mass or more, 99% by mass or more, or 100% by mass.

[0016] In the present disclosure, the term "battery" broadly refers to a device capable of extracting energy using an electrochemical reaction. In a narrower sense, the term "battery" refers to a device that includes a pair of electrodes and an electrolyte, and that is charged and discharged particularly through the movement of ions. By way of example only, examples of batteries include primary batteries and secondary batteries, and more specifically, lithium batteries, magnesium batteries, sodium batteries, and potassium batteries.

[0017] In this disclosure, unless otherwise specified, the term "electrolyte solution" refers to the electrolyte according to the present disclosure excluding the porous insulator, and is composed of a metal salt and a medium.

[0018] <First embodiment: electrolyte> The electrolyte according to the first embodiment of the present disclosure is used in, for example, a battery. That is, the electrolyte described in this specification corresponds to an electrolyte for a device capable of extracting energy by utilizing an electrochemical reaction.

[0019] The electrolyte according to the first embodiment is, as a premise, an electrolyte used in a battery having an electrode composed of lithium, magnesium, sodium, or potassium. In particular, it is an electrolyte for a battery having a lithium electrode as the negative electrode. Therefore, the electrolyte according to the first embodiment can also be said to be an electrolyte for a lithium electrode-based battery (hereinafter, also simply referred to as a "lithium electrode-based electrolyte").

[0020] Here, the term "lithium electrode" as used herein broadly refers to an electrode having lithium (Li) as the active component (i.e., active material). In a narrower sense, "lithium electrode" refers to an electrode comprising lithium, for example, an electrode comprising lithium metal or a lithium alloy, particularly a negative electrode of such lithium. While such a lithium electrode may contain components other than lithium metal or a lithium alloy, in a preferred embodiment it is an electrode made of a lithium metal body (for example, an electrode made of lithium metal with a purity of 90% or more, preferably 95% or more, and more preferably 98% or more).

[0021] The electrolyte according to the first embodiment has Li ion conductivity in the case of a lithium electrode system. The ionic conductivity of the electrolyte according to the first embodiment is, for example, 10 -4 The value is on the order of S / cm or more. The method for measuring ionic conductivity will be explained in detail in the Examples.

[0022] The electrolyte according to the first embodiment is The present invention comprises a porous insulator having pores, a medium (medium molecule) having two nitrile groups (cyano groups; -CN groups) disposed in the pores, and a metal salt; the metal salt is at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts; The molar ratio of the medium to the metal salt (medium / metal salt) is 0.1 or more and less than 0.8 and 0.8 or more and 4.0 or less (i.e., 0.1 or more and 4.0 or less). under )

[0023] [Mechanism of action] The electrolyte according to this embodiment has superior ionic conductivity. While not being bound by any particular theory, the reason for this is presumed to be as follows. In the electrolyte according to this embodiment, a bridge structure can be formed by combining a metal salt and a medium at a specific molar ratio (medium / metal salt = 0.1 to 4.0). Specifically, the electrolyte according to this embodiment can have a bridge structure in which the medium and the positive ions (more specifically, metal ions) constituting the metal salt are alternately arranged. When the bridge structure is disposed within the pores of a porous insulator, it has defects (holes) in which metal ions are missing in some areas, and can therefore serve as a path for efficient transport of metal ions within the electrolyte. Therefore, the formation of the bridge structure in the electrolyte according to this embodiment increases the ionic conductivity of metal ions.

[0024] (bridge structure) The bridge structure is formed by alternating the medium and the positive ions (metal ions) that make up the metal salt, with some of the metal ions missing. [Chemical Formula 1] [ka] The bridge structure will be described in detail with reference to Chemical Formula 1. Chemical Formula 1 shows an example of an electrolyte according to this embodiment, which is a mixture of succinonitrile as a medium and metal ions Li in the pores of a porous insulator. + and an electrolyte containing a metal salt (succinonitrile-Li + Succinonitrile-Li + In the electrolyte of this system, the bridge structure is formed by the nitrogen atom of the nitrile group of succinonitrile. + coordinates to succinonitrile and Li + and are arranged alternately in one dimension, and in some places Li + It has a defect (dashed circle in [Chemical formula 1]) where Li + When we look at the bridge structure from the viewpoint of the + is bridged by succinonitrile. + Because of the presence of the defect, the adjacent Li + can move to the defect.+ Since the metal ions can move sequentially within the bridge structure, the bridge structure is thought to contribute to efficient transport of metal ions within the electrolyte, thereby achieving better ionic conductivity.

[0025] In the bridge structure, the one-dimensional arrangement means, for example, the arrangement of succinonitrile and Li + However, succinonitrile and Li + The arrangement of the compound is not limited to this. For example, the compound + The arrangement may be two-dimensional or three-dimensional, and more specifically, the linear arrangement may be curved or branched.

[0026] (How to check the bridge structure) The bridge structure can be confirmed by structural analysis using Raman spectroscopy. As described above, the bridge structure can be constructed by the coordination of metal ions of a metal salt to a medium. In other words, the bridge structure can be constructed by the formation of a coordinate bond between a metal ion and a specific functional group of the medium. Therefore, the presence of a bridge structure can be confirmed by using microscopic Raman spectroscopy to confirm that "the peak derived from the specific vibration of the functional group forming the coordinate bond is shifted to the higher wavenumber side compared to the peak derived from the specific vibration of the functional group in an uncoordinated state."

[0027] For example, the above succinonitrile (SN)-Li + In the case of electrolytes containing metal ions, the presence of the nitrile group can be confirmed by observing using micro-Raman spectroscopy that the peak (Raman scattering peak) originating from the C-N stretching vibration of the nitrile group of the medium shifts to the higher wavenumber side in the Raman spectrum. peak This can be confirmed by the fact that the peak is shifted to a higher wavenumber compared to the peak (known peak) assigned to the C—N stretching vibration of the nitrile group when not coordinated to a metal ion. B The method for confirming the ridge structure will be described in detail in the Examples.

[0028] (Motivation behind the invention of this disclosure) When a porous insulator is impregnated with an electrolyte used in lithium-ion batteries, the ionic conductivity is still low. The inventors have intensively studied concepts for improving this ionic conductivity. As a result, they have found that forming a bridge structure within the pores and allowing metal ions to propagate through the bridge structure within the pores increases ionic conductivity compared to the mechanism in which metal ions propagate within the pores in a solvated state. This led the inventors to conceive of the electrolyte according to this embodiment, which improves ionic conductivity through a completely new mechanism that is not found in conventional concepts, namely, carrier transport via a bridge structure.

[0029] (Mole ratio (medium / metal salt)) The molar ratio of the medium to the metal salt (medium / metal salt) is 0.1 or more and 4.0 or less. If the molar ratio is less than 0.1 or more than 4.0, the ionic conductivity decreases. From the viewpoint of further improving the ionic conductivity of the electrolyte, the lower limit of the molar ratio is preferably 0.2, more preferably 0.3, and the upper limit of the molar ratio is preferably 2.0, more preferably 1.5, even more preferably 1.2, and particularly preferably 1.0. By arbitrarily selecting and combining from a plurality of suitable numerical ranges, a suitable numerical range of the molar ratio (a numerical range including the upper and lower limits) can be achieved. For example, the molar ratio is preferably 0.2 or more and 2.0 or less.

[0030] In particular, the molar ratio (SN / LiFSI) is preferably 0.2 or more and 2.0 or less, and more preferably 0.4 or more and 1.0 or less.

[0031] -Method for determining the molar ratio (medium / metal salt)- The molar ratio (medium / metal salt) can be determined by the amounts of the medium and metal salt (molar ratio in the raw material state) that constitute the electrolyte according to this embodiment, or the molar ratio (medium / metal salt) can be determined from the electrolyte (as a finished product).

[0032] The electrolyte according to this embodiment may be a solid electrolyte.

[0033] The electrolyte according to this embodiment includes a porous insulator, a medium, and a metal salt. The electrolyte according to this embodiment may further include components other than these components (porous insulator, medium, and metal salt) within the scope of the main effects of the present disclosure. These components constituting the electrolyte are described below.

[0034] (porous insulator) The porous insulator has pores in which a medium having two nitrile groups and a metal salt are arranged. This makes it easier for the electrolyte of the first embodiment to form a bridge structure that contributes to better ion conductivity. The porous insulator has pores. The porous insulator is, for example, at least one selected from the group consisting of zeolite and mesoporous silica.

[0035] From the viewpoint of improving the ionic conductivity of the electrolyte, the porous insulator is preferably zeolite or mesoporous silica. Without being bound by any particular theory, the reason is presumed to be as follows. In the electrolyte according to this embodiment, when the electrolyte is at least one of zeolite and mesoporous silica as a porous insulator (when it contains at least one of them), silanol groups (Si-OH) present on the inner walls of the pores of the zeolite and mesoporous silica are carriers (positive ions of metal salts; more specifically, Li + It is thought that the protons (H + It is believed that the exchange of silanol groups with carriers causes the silanol groups to function as hopping sites for carriers. Therefore, when the electrolyte is made of at least one of zeolite and mesoporous silica as a porous insulator, the ionic conductivity of the electrolyte is further improved.

[0036] In the case of zeolite and mesoporous silica among porous insulators, from the viewpoint of improving the ionic conductivity of the electrolyte, the Si / Al ratio is, for example, 5 or more, preferably 15 or more, more preferably 40 or more, even more preferably 100 or more, particularly preferably 500 or more, and very particularly preferably 1500 or more. The Si / Al ratio is, for example, 10,000 or less. These upper and lower limit values ​​can be arbitrarily combined to form a numerical range (for example, 5 or more and 10,000 or less). In this specification, the Si / Al ratio refers to the molar ratio of Si (silicon atoms) to Al (aluminum atoms) constituting the porous insulator.

[0037] When the Si / Al ratio is 5 or more, the zeolite and mesoporous silica can have more silanol groups on the inner walls of their pores, which is thought to result in more carrier hopping sites on the inner walls of the zeolite and mesoporous silica, further improving the ionic conductivity of the electrolyte.

[0038] The Si / Al ratio of zeolite and mesoporous silica is measured as follows: The zeolite or mesoporous silica is crushed to a size that allows measurement, and placed in a nuclear magnetic resonance apparatus ("ECA400 FT-NMR apparatus" manufactured by JEOL Ltd.). The magnetic field strength is 9.2 T and the nuclide is: 29 NMR spectra are obtained under Si measurement conditions, and the Si / Al ratio is obtained by spectral analysis. The zeolite or mesoporous silica used to measure the Si / Al ratio can be measured not only in the raw material state, but also in a state separated from a finished product (for example, an electrolyte or a battery containing an electrolyte (more specifically, a measurement cell battery described later in the Examples)).

[0039] Commercially available zeolites include "HS-690," "HS-642," and "HS-320" (cation species: H or Na) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., and "HSZ-360HUA," "HSZ-385HUA," "HSZ-640HOA," "HSZ-840HOA," "HSZ-890HOA," and "HSZ-980HOA" manufactured by Tosoh Corporation. Commercially available mesoporous silicas include "MCM-41," "MCM-48," "SBA-15," and "SBA-16" manufactured by Sigma-Aldrich.

[0040] (medium) The medium is an electrically neutral molecule. The medium disperses, dissolves, or forms a solid solution of a metal salt in an electrolyte. The medium is a medium having two nitrile groups (nitrile-based medium). The nitrile-based medium is, for example, at least one selected from the group consisting of succinonitrile (1,2-dicyanoethane), glutaronitrile (1,3-dicyanopropane), and adiponitrile (1,4-dicyanobutane). When the medium is at least one of these, it is easy to form a bridge structure with the metal ions that constitute the metal salt in the electrolyte, and in such a case, the ionic conductivity of the electrolyte according to this embodiment is further increased.

[0041] (metal salts) The metal salt is at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts. Examples of the metal salt include alkali metal salts (more specifically, lithium metal salts, etc.). Examples of the lithium metal salt include lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium tetrafluoroborate (LiBF4), and lithium perchlorate (LiClO4). Among these, preferred lithium salts are LiFSI and LiTFSI, and more preferred is LiFSI. Examples of alkali metal ions constituting the alkali metal salt include Li + , Na + , and K.+ Examples of alkaline earth metal ions constituting the alkaline earth metal salt include Mg 2+ The metal ion (positive ion) constituting the metal salt is preferably Li + , K. + , Na + , or Mg 2+ The negative ion constituting the metal salt is, for example, at least one selected from the group consisting of a bis(fluorosulfonyl)imide ion, a bis(trifluoromethanesulfonyl)imide ion (TFSI ion), a tetrafluoroborate ion, and a perchlorate ion, and preferably at least one selected from the group consisting of a bis(fluorosulfonyl)imide ion and a bis(trifluoromethanesulfonyl)imide ion (TFSI ion).

[0042] (Electrolyte manufacturing method) An example of a method for producing the electrolyte according to the first embodiment will be described below. The method for producing the electrolyte according to the first embodiment includes a step of preparing an electrolyte solution containing a metal salt and a medium (electrolyte solution preparation step), and a step of impregnating a porous insulator having pores with the electrolyte (impregnation step).

[0043] -Electrolyte preparation process- In the electrolyte solution preparation step, an electrolyte solution containing a metal salt and a medium is prepared. -Impregnation process- In the impregnation process, a porous insulator having pores is impregnated with an electrolyte. This fills the pores of the porous insulator with the electrolyte. If the prepared electrolyte is not a liquid at room temperature (25°C) (for example, a solid or quasi-solid (more specifically, a liquid containing a solid)), the electrolyte can be heated to a liquid state and then impregnated into the porous insulator.

[0044] <Second embodiment: battery> The battery according to the second embodiment includes the electrolyte according to the first embodiment. The battery according to the second embodiment can further include a positive electrode and a negative electrode in addition to the electrolyte.

[0045] In the battery according to this embodiment, the positive electrode contains a material constituting the positive electrode (more specifically, a positive electrode active material, etc.). The negative electrode contains an alkali metal (more specifically, Li, Na, K) or an alkaline earth metal (more specifically, Mg) as a material constituting the negative electrode (more specifically, a negative electrode active material). The negative electrode contains, for example, an alkali metal or alkaline earth metal simple substance (more specifically, a plate, foil, or layer) or a compound thereof.

[0046] The battery according to this embodiment can be configured as a secondary battery. A conceptual diagram of this case is shown in FIG. 1. As shown in the figure, during charging, metal ions (M n+ (M represents a metal element, and n represents a positive integer): More specifically, Li + , Na + , K. + and Mg 2+ The metal ions (e.g., ions) move from the positive electrode 10 through the electrolyte 12 to the negative electrode 11, converting electrical energy into chemical energy and storing the electricity. During discharge, the metal ions return from the negative electrode 11 through the electrolyte 12 to the positive electrode 10, generating electrical energy.

[0047] The battery according to the second embodiment can be used as a driving power source or auxiliary power source for, for example, notebook personal computers, PDAs (personal digital assistants), mobile phones, smartphones, cordless phone base units and handset units, video camcorders, digital still cameras, e-books, electronic dictionaries, portable music players, radios, headphones, game consoles, navigation systems, memory cards, cardiac pacemakers, hearing aids, power tools, electric shavers, refrigerators, air conditioners, television receivers, stereos, hot water heaters, microwave ovens, dishwashers, washing machines, dryers, lighting equipment, toys, medical equipment, robots, road conditioners, traffic lights, railroad cars, golf carts, electric carts, and / or electric vehicles (including hybrid vehicles). The battery can also be installed as a power storage power source for buildings such as homes or power generation facilities, or used to supply power to these. In electric vehicles, the converter that converts supplied power into driving force is generally a motor. A control device (control unit) that processes information related to vehicle control includes a control device that displays the remaining battery power based on information about the remaining battery power. The battery can also be used in a power storage device in a so-called smart grid. Such a power storage device can not only supply power but also store power by receiving power from other power sources. Examples of other power sources that can be used include thermal power generation, nuclear power generation, hydroelectric power generation, solar cells, wind power generation, geothermal power generation, and / or fuel cells (including biofuel cells).

[0048] Although the embodiments of the present disclosure have been described above, they are merely typical examples. Therefore, it will be readily understood by those skilled in the art that the present disclosure is not limited thereto and that various modifications are possible within the scope of the present disclosure.

[0049] For example, the electrolyte composition, raw materials used in the production, production method, production conditions, electrolyte properties, and battery configuration or structure are examples, and are not limited to these and can be changed as appropriate. For example, batteries include lithium batteries, magnesium batteries, sodium batteries, and potassium batteries, as well as air batteries and fuel cells. [Example]

[0050] The present disclosure will be explained in more detail below using examples, but the present disclosure is not limited to these examples.

[0051] Example 1 [1. Preparation of electrolyte solution] (1-1. Ingredients) The following raw materials were used: -Porous insulator: Zeolite- Fujifilm Wako Pure Chemical Industries, Ltd. "HS-320" (crystal system: Y-type, Si / Al ratio = 5.5, cation species: H; hereinafter also referred to as "HS-320(H)") Fujifilm Wako Pure Chemical Industries, Ltd. "HS-320" (crystal system: Y-type, Si / Al ratio = 5.5, cation species: Na; hereinafter also referred to as "HS-320(Na)") Fujifilm Wako Pure Chemical Industries, Ltd. "HS-642" (crystal system: mordenite, Si / Al ratio = 18, cation species: Na) Fujifilm Wako Pure Chemical Industries, Ltd. "HS-690" (crystal system: mordenite, Si / Al ratio = 180, cation species: H ) Tosoh Corporation's "HSZ-360HUA" (crystal system: Y-type, Si / Al ratio = 15, cation species: H) Tosoh Corporation's "HSZ-385HUA" (crystal system: Y-type, Si / Al ratio = 100, cation species: H) Tosoh Corporation's "HSZ-640HOA" (crystal system: mordenite, Si / Al ratio = 18, cation species: H) Tosoh Corporation's "HSZ-840HOA" (crystal system: ZSM-5, Si / Al ratio = 40, cation species: H) Tosoh Corporation "HSZ-890HOA" (crystal system: ZSM-5, Si / Al ratio = 1500, cation species: H) Tosoh Corporation's "HSZ-980HOA" (crystal system: beta, Si / Al ratio = 500, cation species: H) -Porous insulator: mesoporous silica- Sigma-Aldrich "MCM-41" Sigma-Aldrich "MCM-48" Sigma-Aldrich "SBA-15" Sigma-Aldrich "SBA-16" These four mesoporous silicas are essentially composed of silica (SiO2) because they do not contain artificially added Al. Therefore, the Si / Al ratio of these mesoporous silicas is thought to be at least greater than 10,000. -Metal salts- Lithium bis(fluorosulfonyl)imide (manufactured by Kishida Chemical Co., Ltd. (for LBG); hereinafter also referred to as "LiFSI") Lithium bis(trifluoromethanesulfonyl)imide (manufactured by Kishida Chemical Co., Ltd. for LBG); hereinafter also referred to as "LiTFSI") Lithium hexafluorophosphate (manufactured by Kishida Chemical Co., Ltd. (for LBG); hereinafter also referred to as "LiPF6" or "LiPF6") Lithium tetrafluoroborate (manufactured by Kishida Chemical Co., Ltd. (for LBG); hereinafter referred to as "LiBF4" or "LiBF4") Lithium perchlorate (manufactured by Kishida Chemical Co., Ltd. (for LBG); hereinafter also referred to as "LiClO4" or "LiClO4") - Medium: Nitrile-based medium - Succinonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.; hereinafter also referred to as "SN") Glutaronitrile (manufactured by Tokyo Chemical Industry Co., Ltd.; hereinafter also referred to as "GLN") Adiponitrile (manufactured by Tokyo Chemical Industry Co., Ltd.; hereinafter also referred to as "AGN")

[0052] (1-2. Preparation of solid electrolyte) An electrolyte solution was prepared by mixing LiFSI as a metal salt and succinonitrile SN as a medium so that the molar ratio (medium / metal salt) was 4.0.

[0053] HS-690, which served as a porous insulator, was dried under vacuum at 300°C. The dried HS-690 was impregnated with the prepared electrolyte solution, and the electrolyte solution was inserted and filled into the pores of the HS-690. This produced a powdered solid electrolyte. This impregnation process was performed by manually mixing the electrolyte solution and the porous insulator using a mortar and pestle. The amount (volume) of the impregnated electrolyte was adjusted to 100% of the micropore volume of the porous insulator (HS-690), which had been measured in advance. The preparation of the solid electrolyte was carried out in a glove box in an argon atmosphere.

[0054] (1-3. Preparation of measurement cell) The prepared powdered solid electrolyte was pressed at 200 MPa using a uniaxial press (Riken Kiki Co., Ltd., "CDM-20PA"). A PET resin mortar with upper and lower punches was used as the press mold. Specifically, the PET resin mortar had a cylindrical shape and a cylindrical through-hole along the central axis. The punch had a cylindrical shape and was inserted and removed from the through-hole of the mortar, with the tip faces (surfaces perpendicular to the insertion direction) of the upper and lower punches facing each other. The powdered solid electrolyte was placed in the through-hole of the mortar so as to be sandwiched between the tip faces of the upper and lower punches. The upper and lower punches were pressed with the uniaxial press to form a solid electrolyte. Furthermore, the upper and lower punches of the PET resin mortar were used as blocking electrodes to form a measurement cell (a cell for measurement). The process of preparing the measurement cell was carried out in a glove box in an argon atmosphere.

[0055] [2. Measurement and evaluation methods] (2-1. Form of electrolyte) The appearance of the electrolyte solution (electrolyte solution consisting of metal salt and medium) obtained in the solid electrolyte preparation process was visually observed. Furthermore, the container containing the electrolyte solution was tilted, and the behavior of the liquid surface changing to become parallel to the horizontal plane was visually observed. Based on these observation results, the evaluation was made according to the following criteria. (Evaluation criteria) Liquid: The electrolyte has a liquid appearance, with no solids mixed in. When a cylindrical container containing the electrolyte is tilted so that the bottom of the container is at an angle of 30° to the horizontal, the liquid surface of the electrolyte becomes parallel to the horizontal within one second of tilting. Sherbet-like: The appearance is a mixture of liquid and solid, and when a cylindrical container containing the electrolyte is tilted so that the bottom of the container is at an angle of 30° to the horizontal, the liquid surface of the electrolyte becomes parallel to the horizontal within 1 to 60 seconds after tilting. Syrup-like: When the appearance of the electrolyte is a highly viscous liquid and the cylindrical container containing the electrolyte is tilted so that the bottom of the container is at an angle of 30° to the horizontal, the shape of the liquid surface of the electrolyte changes within 1 to 60 seconds after tilting, but the liquid surface of the electrolyte does not become parallel to the horizontal. Solid: The appearance is solid, and when a cylindrical container containing electrolyte is tilted so that the bottom of the container is at an angle of 30° to the horizontal, the liquid level of the electrolyte remains unchanged for 10 minutes or more after tilting.

[0056] (2-2. Measurement of ionic conductivity) -Preparation of measurement samples- The measurement cell prepared in (1-3. Preparation of measurement cell) was enclosed in a laminate with a tab electrode to prepare a cell for measuring ionic conductivity as a measurement sample.

[0057] -Measurement of ionic conductivity- The ionic conductivity of the measurement sample was measured using an impedance meter (VMP3 manufactured by Biologic). The ionic conductivity was measured at room temperature (25°C) by an AC impedance method. The solid electrolyte of Example 1 had a molar ratio (SN / LiFSI) of 4.0 and an ionic conductivity of 4.9 × 10 -4(S / cm). The results, along with the results of the appearance observation of the electrolyte solution, are shown in Table 1. Table 1 shows the molar ratio (SN / LiFSI), the state of the electrolyte solution at room temperature, and the ionic conductivity at room temperature.

[0058] (2-3. Structural analysis of electrolytes by Raman spectroscopy) The electrolytes of Examples 2 to 3, 5 to 7 and Comparative Example 1 described below were subjected to structural analysis using Raman spectroscopy. The solid electrolyte formed in (1-3. Preparation of measurement cell) was used as a measurement sample for structural analysis. The obtained measurement sample was placed in a microscopic laser Raman spectrometer ("LabRam HR Evolution" manufactured by Horiba, Ltd.). The surface of the measurement sample was irradiated with infrared laser light (wavelength 1064 nm), and the Raman spectrum was measured using an objective lens with a spot diameter of 7 μm. The Raman spectrum may also be measured by irradiating the infrared laser light onto a cut surface formed by cutting the measurement sample (solid electrolyte) for structural analysis.

[0059] 3 shows the results of the electrolytes of Examples 2 to 3, 5 to 7 and Comparative Example 1 at 2220 to 2320 cm -1 In the Raman spectrum shown in Figure 3, the vertical axis represents the Raman intensity (unit: arbitrary intensity), and the horizontal axis represents the Raman shift (unit: cm -1 ) The Raman spectrum shown in Figure 3 shows the peak at 2254 cm -1 The peaks located nearby and 2280cm -1 and a peak located near 2280 cm -1 The peak located near 2254 cm is due to the C-N stretching vibration of the nitrile group of SN. -1 The peak located nearby was attributed to the peak shifted to the higher wavenumber side.

[0060] (2-4. Determination of Si / Al ratio by nuclear magnetic resonance) In Examples 11 to 19 described below, the Si / Al ratio of the zeolite or mesoporous silica was determined. Specifically, zeolite or mesoporous silica was crushed to a degree that allowed for measurement. The crushed zeolite or mesoporous silica was placed in a nuclear magnetic resonance apparatus (JEOL "ECA400 type FT-NMR apparatus"). The magnetic field strength was 9.2 T and the nuclide was: 29 Measured under Si measurement conditions 29 Si NMR spectra were obtained. 29 The Si / Al ratio was obtained from the peak area intensity ratio of the Si NMR spectrum.

[0061] <Examples 2 to 9 and Comparative Examples 1 and 2: Molar Ratio> The electrolytes were prepared and the ionic conductivity was measured in the same manner as in Example 1, except that the molar ratio (SN / LiFSI) was changed from 4.0 to the molar ratios shown in Table 1. The appearance of the electrolyte solution obtained in the electrolyte preparation process was also observed. The results are shown in Table 1. When the concentration of the metal salt in the electrolytic solution composed of the metal salt and the medium is relatively high (i.e., when the concentration of the medium is relatively low), the electrolytic solution may become a solid or a liquid with a solid precipitated at room temperature (25° C.). In such cases, the electrolytic solution is heated (for example, to 90° C.) until the solid in the prepared electrolytic solution is completely dissolved, and the solution is then liquid, after which the impregnation treatment is carried out. In Example 6, the electrolyte of Example 6 and Li4Ti5O as the negative electrode were used. 12 A lithium ion secondary battery was fabricated using the cathode and LiFePO4. Charging and discharging were carried out at a current of 0.1 C (coulomb). The charge and discharge potential was approximately 1.8 V.

[0062] [Results: Examples 1 to 9 and Comparative Examples 1 and 2: Molar Ratio] (ionic conductivity) Table 1 shows the molar ratio (SN / LiFSI) and the ionic conductivity at room temperature. Figure 2 was created based on Table 1. Figure 2 shows the relationship between the molar ratio (SN / LiFSI) and the ionic conductivity at room temperature. The horizontal axis in Figure 2 shows the molar ratio, and the vertical axis shows the ionic conductivity (unit: S / cm) at room temperature. Note that, for example, 1.0E-03 in the scale of the vertical axis in Figure 2 corresponds to 1.0 x 10 -3 Shows.

[0063] [Table 1]

[0064] As shown in Figure 2, in the SN-LiFSI electrolyte, the ionic conductivity at room temperature simply increased as the molar ratio (SN / LiFSI) increased from 0.1 to 0.5, decreased as the molar ratio (SN / LiFSI) increased from 0.5 to 4.0, and remained almost the same as the molar ratio (SN / LiFSI) increased from 6.0 to 10.0. Furthermore, when the ionic conductivity of the electrolytes composed of SN and LiFSI in Examples 2 and 3 was measured, it was found to be below the lower limit of measurement (or below the measurement limit; more specifically, about 10 -7 This corresponds to the ionic conductivity of an insulator.

[0065] (bridge structure) In the SN-LiFSI electrolyte, as shown in Figure 3, the peak (Raman scattering peak) due to the C-N stretching vibration is at 2254 cm when the molar ratio (SN / LiFSI) is 10.0. -1 When the molar ratio (SN / LiFSI) decreases from 0.3 to 0.8 and from 1.5 to 2.0, the -1 The intensity of the peak located near 2280 cm decreases, and the peak at 2280 cm on the higher wavenumber side -1 A peak appears around 1 / 3, and the peak intensity on the high wavenumber side increases relatively. In the electrolytes of Examples 2 and 3 and Examples 5 to 7, the peak derived from the C-N stretching vibration shifted to the high wavenumber side compared to the electrolyte of Comparative Example 1. From these results, in the electrolytes of Examples 2 to 3 and Examples 5 to 7, Li constituting the metal salt + It is believed that the SN and the SN medium form a bridge structure. The bridge structure is presumed to be due to a specific molar ratio (SN / LiFSI).

[0066] [Comparison of Examples 1 to 9 with Comparative Examples 1 and 2] The electrolytes of Examples 1 to 9 included HS-690 as a porous insulator having pores, SN as a medium having two nitrile groups arranged in the pores, and LiFSI as a metal salt, where the LiFSI as the metal salt was at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts, and the molar ratio of the medium to the metal salt (medium / metal salt) was 0.1 or more and 4.0 or less. In other words, the electrolytes of Examples 1 to 9 were electrolytes encompassed within the scope of the invention according to claim 1.

[0067] The ionic conductivity of the electrolytes in Examples 1 to 8 was 4.1 × 10 at room temperature. -4 ~85×10 -4 It was S / cm.

[0068] The electrolytes of Comparative Examples 1 and 2 were not included in the scope of the invention according to claim 1. Specifically, the electrolytes of Comparative Examples 1 and 2 had a molar ratio of the medium to the metal salt (medium / metal salt) of more than 4.0. The ionic conductivity of the electrolytes of Comparative Examples 1 and 2 was 1.5 × 10 at room temperature. -4 ~2.0×10 -4 It was S / cm.

[0069] Examples 1 to 9, which fall within the scope of the invention according to claim 1, had higher ionic conductivities at room temperature compared to Comparative Examples 1 and 2, which do not fall within the scope of the invention according to claim 1. This demonstrates that the invention according to claim 1 is excellent in ionic conductivity.

[0070] <Examples 11 to 19: Porous insulator (zeolite)> An electrolyte was prepared and a battery was fabricated in the same manner as in Example 1, except that the porous insulator HS-690 and the molar ratio were changed to the porous insulator (zeolite) and molar ratio shown in Table 2. The ionic conductivity was also measured in the same manner as in Example 1. The results are shown in Table 2.

[0071] [Table 2]

[0072] The electrolytes of Examples 11 to 19 were comprised of any one of HS-320(H), HS-320(Na), HSZ-360HUA, HSZ-640HOA, HS-642, HSZ-840HOA, HSZ-385HUA, HSZ-980HOA, and HSZ-890HOA as a porous insulator (zeolite) having pores, SN as a medium having two nitrile groups arranged in the pores, and LiFSI as a metal salt, where the LiFSI as the metal salt was at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts, and the molar ratio of the medium to the metal salt (medium / metal salt) was 0.1 or more and 4.0 or less. In other words, the electrolytes of Examples 11 to 19 were electrolytes encompassed within the scope of the invention according to claim 1.

[0073] The ionic conductivity of the electrolytes of Examples 11 to 19 was 8.0 × 10 at room temperature. -4 ~46×10 -4 S / cm, which increased with increasing Si / Al ratio. This trend suggests the following: the larger the Si / Al ratio, the more silanol groups there are on the pore walls of the porous insulator (zeolite), resulting in the carrier (Li + ) hopping sites will increase.

[0074] <Examples 31 to 36: Metal salts and media> An electrolyte was prepared and a battery was fabricated in the same manner as in Example 1, except that the metal salt LiFSI, the medium SN, and the molar ratio (SN / LiFSI) were changed to the metal salt, medium, and molar ratio (medium / alkali metal salt) shown in Table 3. The ionic conductivity was also measured in the same manner as in Example 1. The results are shown in Table 3.

[0075] [Table 3]

[0076] The electrolytes of Examples 31 to 36 comprised HS-690 as a porous insulator having pores, one of SN, GLN, and ADN as a medium having two nitrile groups arranged in the pores, and one of LiTFSI, LiPF6, LiBF4, LiClO4, and LiFSI as a metal salt, the metal salt being at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts, and the molar ratio of the medium to the metal salt (medium / metal salt) was 0.1 or more and 4.0 or less. In other words, the electrolytes of Examples 31 to 36 were electrolytes encompassed within the scope of the invention according to claim 1.

[0077] <Examples 41 to 48: Porous insulator (mesoporous silica)> An electrolyte was prepared and a battery was fabricated in the same manner as in Example 1, except that the porous insulator HS-690 was changed to a porous insulator (mesoporous silica) shown in Table 4. The ionic conductivity was also measured in the same manner as in Example 1. The results are shown in Table 4.

[0078] [Table 4]

[0079] The electrolytes of Examples 41 to 48 comprised any one of MCM-48, SBA-15, MCM-41, and SBA-16 as a porous insulator having pores, SN as a medium having two nitrile groups arranged in the pores, and LiFSI as a metal salt, the metal salt being at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts, and the molar ratio of the medium to the metal salt (medium / metal salt) was 0.1 or more and 4.0 or less. The electrolytes of Examples 41 to 48 were electrolytes encompassed within the scope of the invention according to claim 1.

[0080] Aspects of the electrolyte and battery according to the present disclosure are as follows. <1> A porous insulator having pores, a medium having two nitrile groups and a metal salt disposed in the pores, the metal salt is at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts, An electrolyte, wherein the molar ratio of the medium to the metal salt (medium / metal salt) is 0.1 or more and 4.0 or less. <2> The medium is at least one selected from the group consisting of succinonitrile, glutaronitrile, and adiponitrile; <1> The electrolyte according to claim 1. <3> The metal salt is a lithium salt. <1> or <2> The electrolyte according to claim 1. <4> The porous insulator is at least one selected from the group consisting of zeolite and mesoporous silica. <1> ~ <3> 10. The electrolyte according to claim 9 . <5> The positive ions constituting the metal salt are Li + , K. + , Na + , or Mg 2+ That is, <1> ~ <4> 10. The electrolyte according to claim 9 . <6> The negative ion constituting the metal salt is at least one selected from the group consisting of a bis(fluorosulfonyl)imide ion and a TFSI ion. <1> ~ <5> 10. The electrolyte according to claim 9 . <7> It is a solid electrolyte, <1> ~ <6> 10. The electrolyte according to claim 9 . <8> the medium is at least one nitrile medium selected from the group consisting of succinonitrile, glutaronitrile, and adiponitrile; In the Raman spectrum, the peak due to the C-N stretching vibration of the nitrile group is shifted to a higher wavenumber side. <1> ~ <7> 10. The electrolyte according to claim 9 . <9> the porous insulator is at least one selected from the group consisting of zeolite and mesoporous silica, The zeolite and the mesoporous silica have an Si / Al ratio of 5 or more. <1> ~ <8> 10. The electrolyte according to claim 9 . <10> <1> ~ <9> A battery comprising the electrolyte according to any one of claims 1 to 5. [Industrial Applicability]

[0081] Batteries including the electrolyte according to the present disclosure can be used in a variety of fields where electricity storage is anticipated. By way of example only, batteries (particularly secondary batteries) including the electrolyte according to the present disclosure can be used in the fields of electricity, information, and communications where electrical and electronic devices are used (for example, the fields of electrical and electronic devices or mobile devices including mobile phones, smartphones, laptop computers, digital cameras, activity monitors, arm computers, electronic paper, wearable devices, and small electronic devices such as RFID tags, card-type electronic money, and smart watches), household and small industrial applications (for example, power tools, golf carts, and household, nursing care, and industrial robots), large industrial applications (for example, forklifts, elevators, and harbor cranes), transportation systems (for example, hybrid cars, electric cars, buses, trains, electrically assisted bicycles, and electric motorcycles), power system applications (for example, various power generation systems, road conditioners, smart grids, and general household-installed power storage systems), medical applications (medical devices such as earphones and hearing aids), pharmaceutical applications (dose management systems), IoT, and space and deep-sea applications (for example, space probes, submersible research vessels, and the like).

Claims

1. A porous insulator having pores, a medium having two nitrile groups and a metal salt disposed in the pores, the metal salt is at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts, An electrolyte, wherein the molar ratio of the medium to the metal salt (medium / metal salt) is 0.1 or more and 4.0 or less.

2. 2. The electrolyte of claim 1, wherein the medium is at least one selected from the group consisting of succinonitrile, glutaronitrile, and adiponitrile.

3. 10. The electrolyte of claim 1, wherein the metal salt is a lithium salt.

4. The electrolyte according to claim 1 , wherein the porous insulator is at least one selected from the group consisting of zeolite and mesoporous silica.

5. The positive ions constituting the metal salt are Li ＋ , K. ＋ , Na ＋ , or Mg ２＋ 2. The electrolyte of claim 1 , wherein:

6. 2. The electrolyte according to claim 1, wherein the negative ion constituting the metal salt is at least one selected from the group consisting of a bis(fluorosulfonyl)imide ion and a bis(trifluoromethanesulfonyl)imide ion.

7. 10. The electrolyte of claim 1 which is a solid electrolyte.

8. the medium is at least one nitrile medium selected from the group consisting of succinonitrile, glutaronitrile, and adiponitrile; 2. The electrolyte according to claim 1, wherein in a Raman spectrum, a peak derived from the C-N stretching vibration of the nitrile group is shifted to a higher wavenumber side.

9. the porous insulator is at least one selected from the group consisting of zeolite and mesoporous silica, 2. The electrolyte of claim 1, wherein the zeolite and the mesoporous silica have a Si / Al ratio of 5 or greater.

10. A battery comprising the electrolyte according to any one of claims 1 to 9.

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