Electrolyte, and battery comprising 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

Electrolyte and battery containing the electrolyte

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

[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-SO ２ -N-SO ２ -R'] － (R and R' represent a fluorine atom or a fluoroalkyl group) and a metal cation (e.g., Li ＋ , Na ＋ , or Mg ２＋ ) and an ion-conductive composite (electrolyte) comprising the same.

[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 an MOF slurry electrolyte, where MOFs are a class of crystalline porous solids constructed from metal cluster nodes and organic linkers, and are capable of binding anions, removing ion pairs, and enhancing cation transport upon activation and impregnation with the liquid electrolyte.

[0005] Patent No. 6222635 Special Publication No. 2020-508542

[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.

[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] An electrolyte according to one embodiment of the present disclosure comprises a porous insulator having pores, a medium having two nitrile groups disposed in the pores, and a metal salt, wherein the metal salt is 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 or more and 4.0 or less.

[0010] Moreover, a battery according to an embodiment of the present disclosure includes the above-described electrolyte.

[0011] The present disclosure can provide an electrolyte with superior ionic conductivity.

[0012] Fig. 1 is a conceptual diagram showing an example of a battery according to a second embodiment of the present disclosure. Fig. 2 is a graph showing the relationship between the molar ratio (SN / LiFSI) and the ionic conductivity at room temperature. Fig. 3 shows the ionic conductivity at 2220 to 2320 cm of the electrolytes of Examples 2 and 3, Examples 5 to 7, and Comparative Example 1. －１ This is the Raman spectrum at

[0013] The "electrolyte" and the "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, for example, by using terms such as "less than," "smaller," or "greater than." In other words, 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, the expression "a target component is substantially composed of a specific material" or "a target component is made 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, when mesoporous silica is silica (SiO ２ The term "essentially composed of mesoporous silica" means that the mesoporous silica is composed of silica (SiO ) in a proportion of 95% by mass or more, 97% by mass or more, 99% by mass or more, or 100% by mass. ２ ) is included.

[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 that can extract 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 ionic conductivity is a value on the order of S / cm or more. The method for measuring the ionic conductivity will be described in detail in the Examples.

[0022] The electrolyte according to the first embodiment comprises a porous insulator having pores, a medium (medium molecule) having two nitrile groups (cyano groups; -CN groups) arranged in the pores, and a metal salt, wherein the metal salt is 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 or more but less than 0.8 and 0.8 or more but 4.0 or less (i.e., 0.1 or more but 4.0 or less).

[0023] [Mechanism of Action] The electrolyte according to this embodiment has superior ionic conductivity. Without 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 arranged alternately. 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) In the bridge structure, the medium and the positive ions (metal ions) constituting the metal salt are arranged alternately, and some of the metal ions are missing. [Chemical Formula 1] 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 ＋ The following electrolytes are listed: succinonitrile-Li ＋ In the electrolyte of this system, the bridge structure is formed by the nitrile group (nitrogen atom) of succinonitrile being connected to Li ＋ coordinates to succinonitrile and Li ＋ and are arranged alternately in one dimension, and in some parts Li ＋ It has a defect where Li is missing (the dashed circle in [Chemical Formula 1]). ＋ When the bridge structure is viewed from the viewpoint of the ＋ is bridged by succinonitrile. ＋ Since there is a defect, adjacent Li ＋ can move to the defect. ＋can move sequentially within the bridge structure, which is thought to contribute to the efficient transport of metal ions within the electrolyte and achieve better ionic conductivity.

[0025] In the bridge structure, the one-dimensional arrangement means, for example, a structure in which 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] (Method for Confirming 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 metal ions forming a coordinate bond with 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 such bridge structures, their presence can be confirmed by using microscopic Raman spectroscopy to confirm that "in the Raman spectrum, the peak (Raman scattering peak) derived from the C-N stretching vibration of the nitrile group of the medium is shifted to a higher wavenumber." This peak is attributed to the C-N stretching vibration of the nitrile group in a state coordinated to a metal ion, but can be confirmed by the peak being shifted to a higher wavenumber compared to the peak (known peak) attributed to the C-N stretching vibration of the nitrile group in a state not coordinated to a metal ion. The method for confirming the bridge structure will be described in detail in the Examples.

[0028] (Motivation behind the Invention of the Present Disclosure) When a porous insulator is impregnated with an electrolyte solution used in lithium-ion batteries, the ionic conductivity is still low. The present inventors have intensively studied concepts for improving this ionic conductivity. As a result, they have found that by forming a bridge structure within the pores and allowing metal ions to propagate through the bridge structure within the pores, the ionic conductivity is higher than when the metal ions propagate within the pores in a solvated state. This led the present inventors to conceive of an 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] (Molar 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 from the amounts of the medium and metal salt (molar ratio in the raw material state) that constitute the electrolyte according to this embodiment. Alternatively, 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 a medium having two nitrile groups and a metal salt disposed within its pores. This makes it easier for the electrolyte according to the first embodiment to form a bridge structure that contributes to superior ionic 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 a 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 ionized by carriers (positive ions of metal salts; more specifically, Li ＋ It is believed that the protons (H etc.) of the silanol groups function as hopping sites. ＋ 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 pulverized to a size that allows measurement, and placed in a nuclear magnetic resonance spectrometer ("ECA400 FT-NMR spectrometer" manufactured by JEOL Ltd.). The magnetic field strength is 9.2 T and the nuclide is: ２９ The NMR spectrum is obtained by measuring under the Si measurement conditions. 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, for example, "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, for example, "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 the metal salt in the electrolyte. The medium is a medium having two nitrile groups (nitrile-based medium). Examples of nitrile-based media include 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 likely to form a bridge structure with the metal ions that make up the metal salt in the electrolyte. Therefore, in such cases, the ionic conductivity of the electrolyte according to this embodiment is higher.

[0041] (Metal Salt) 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), and lithium tetrafluoroborate (LiBF ４ ), and lithium perchlorate (LiClO ４ Among these, preferred lithium salts are LiFSI and LiTFSI, and more preferred is LiFSI. Examples of alkali metal ions constituting alkali metal salts 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 is preferably at least one selected from the group consisting of a bis(fluorosulfonyl)imide ion and a bis(trifluoromethanesulfonyl)imide ion (TFSI ion).

[0042] (Method for Producing Electrolyte) An example of a method for producing the electrolyte according to the first embodiment will be described. 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 Solution Preparation Step - In the electrolyte solution preparation step, an electrolyte solution containing a metal salt and a medium is prepared. - Impregnation Step - In the impregnation step, a porous insulator having pores is impregnated with the electrolyte solution. As a result, the pores of the porous insulator are filled with the electrolyte solution. If the prepared electrolyte solution 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 solution 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 includes a material constituting the positive electrode (more specifically, a positive electrode active material, etc.). The negative electrode includes 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 includes, 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, etc., 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 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 typically a motor. A control device (controller) that processes information related to vehicle control includes a control device that displays the remaining battery charge based on information about the remaining battery charge. 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 power generation, 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.

[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. Raw Materials) 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 "HSZ-360HUA" (crystal system: Y-type, Si / Al ratio = 15, cation species: H) "HSZ-385HUA" manufactured by Tosoh Corporation (crystal system: Y-type, Si / Al ratio = 100, cation species: H) "HSZ-640HOA" manufactured by Tosoh Corporation (crystal system: mordenite, Si / Al ratio = 18, cation species: H) "HSZ-840HOA" manufactured by Tosoh Corporation (crystal system: ZSM-5, Si / Al ratio = 40, cation species: H) "HSZ-890HOA" manufactured by Tosoh Corporation (crystal system: ZSM-5, Si / Al ratio = 1500, cation species: H) "HSZ-980HOA" manufactured by Tosoh Corporation (crystal system: beta, Si / Al ratio = 500, cation species: H) -Porous insulator: mesoporous silica- "MCM-41" manufactured by Sigma-Aldrich "MCM-48" manufactured by Sigma-Aldrich・Sigma-Aldrich "SBA-15" ・Sigma-Aldrich "SBA-16" These four mesoporous silicas do not contain artificial Al, so they are silica (SiO ２ ) is essentially composed of. Therefore, it is considered that the Si / Al ratio of these mesoporous silicas is 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 "LiBF ４ " or "LiBF4") Lithium perchlorate (manufactured by Kishida Chemical Co., Ltd. (for LBG); hereinafter referred to as "LiClO ４ " 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 at a molar ratio (medium / metal salt) of 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 solid electrolyte was prepared 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 weft with upper and lower punches was used as the press mold for pressing. Specifically, the PET resin weft 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 weft, with the tip faces (surfaces perpendicular to the insertion direction) of the upper and lower punches facing each other. The powdered solid electrolyte was set in the through-hole of the weft 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 provided on the PET resin weft 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 Method and Evaluation Method] (2-1. Morphology of Electrolyte Solution) The appearance of the electrolyte solution (electrolyte solution consisting of a metal salt and a 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 solid mixed in, and when a cylindrical container containing the electrolyte is tilted so that the bottom of the container forms an angle of 30° with the horizontal, the liquid surface of the electrolyte becomes parallel to the horizontal in less than 1 second after tilting. Sherbet-like: The electrolyte has a liquid and solid appearance mixed in, and when a cylindrical container containing the electrolyte is tilted so that the bottom of the container forms an angle of 30° with the horizontal, the liquid surface of the electrolyte becomes parallel to the horizontal in 1 to 60 seconds after tilting. Starch syrup-like: The electrolyte has a highly viscous liquid appearance, and when a cylindrical container containing the electrolyte is tilted so that the bottom of the container forms an angle of 30° with the horizontal, the shape of the liquid surface of the electrolyte changes but the liquid surface of the electrolyte does not become parallel to the horizontal in 1 to 60 seconds after tilting. 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 Ion Conductivity) - Preparation of Measurement Sample - The measurement cell prepared in (1-3. Preparation of Measurement Cell) was enclosed in a laminate with a tab electrode to prepare an ion conductivity measurement cell 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 The results are shown in Table 1, along with the results of the appearance observation of the electrolyte solution described above. 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 and 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 FIG. 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 2280 cm －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 method) In Examples 11 to 19 described later, the Si / Al ratio of zeolite or mesoporous silica was determined. Specifically, the zeolite or mesoporous silica was pulverized to a degree that allowed measurement. The pulverized zeolite or mesoporous silica was placed in a nuclear magnetic resonance apparatus ("ECA400 FT-NMR apparatus" manufactured by JEOL Ltd.). The magnetic field strength was 9.2 T and the nuclide: ２９ Measured under Si measurement conditions ２９ A Si NMR spectrum was 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 An electrolyte was prepared and its 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 ratio shown in Table 1. The appearance of the electrolyte solution obtained in the electrolyte preparation step was also observed. These results are shown in Table 1. Note that when the concentration of the metal salt in the electrolyte solution consisting of the metal salt and the medium is relatively high (i.e., when the concentration of the medium is relatively low), the electrolyte may become a solid or a liquid with a solid precipitated at room temperature (25°C). In such cases, the prepared electrolyte solution was heated (for example, to 90°C) until the solid in the electrolyte solution was completely dissolved, and the liquid was then impregnated. In Example 6, the electrolyte of Example 6 and a negative electrode containing Li ４ Ti ５ O １２ and LiFePO as the positive electrode. ４ A lithium ion secondary battery comprising the above was fabricated. Charging and discharging were carried out at a current of 0.1 C (coulomb). The charging and discharging potential was about 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]

[0064] In the SN-LiFSI electrolyte, as shown in FIG. 2, 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 constant 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 that both were below the lower limit of measurement (or below the measurement limit; more specifically, about 10－７ This value corresponds to the ionic conductivity of the insulator.

[0065] (Bridge Structure) In the SN-LiFSI electrolyte, as shown in FIG. 3, the peak (Raman scattering peak) derived from 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) is decreased from 0.3 to 0.8 and from 1.5 to 2.0, the peak temperature rises to 2254 cm －１ The intensity of the peak located near 2280 cm decreases, and the peak located near 2280 cm －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 CN stretching vibration shifted to the high wavenumber side compared to the electrolyte of Comparative Example 1. From these results, it can be seen that in the electrolytes of Examples 2 and 3 and Examples 5 to 7, the peak derived from the Li ＋ It is believed that the SN and the SN serving as a 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 that fell within the scope of the invention according to claim 1.

[0067] The ionic conductivity of the electrolytes of Examples 1 to 8 was 4.1 × 10 at room temperature. －４ ~85 x 10 －４ The viscosity 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 molar ratio of the medium to the metal salt (medium / metal salt) of the electrolytes of Comparative Examples 1 and 2 exceeded 4.0. The ionic conductivity of the electrolytes of Comparative Examples 1 and 2 was 1.5 × 10 at room temperature. －４ ~2.0 x 10 －４ The viscosity 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 fall outside 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) Electrolytes were prepared and batteries were fabricated in the same manner as in Example 1, except that the HS-690 porous insulator and the molar ratio were changed to the porous insulator (zeolite) and molar ratio shown in Table 2. Ion conductivity was also measured in the same manner as in Example 1. The results are shown in Table 2.

[0071]

[0072] The electrolytes of Examples 11 to 19 comprised 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, wherein 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 x 10 －４S / cm, which increased with increasing Si / Al ratio. This trend suggests that the larger the Si / Al ratio, the more silanol groups are present on the inner walls of the pores of the porous insulator (zeolite), resulting in the carrier (Li ＋ ) hopping sites will increase.

[0074] Examples 31 to 36: Metal Salt and Medium Electrolytes were prepared and batteries were 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. Ion conductivity was also measured in the same manner as in Example 1. The results are shown in Table 3.

[0075]

[0076] The electrolytes of Examples 31 to 36 consisted of 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 LiTFSI, LiPF as a metal salt. ６ , LiBF ４ , LiClO ４ and LiFSI, 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 that fell within the scope of the invention according to claim 1.

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

[0078]

[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] The electrolyte and battery according to the present disclosure include the following aspects: <1> An electrolyte comprising a porous insulator having pores, a medium having two nitrile groups arranged in the pores, and a metal salt, wherein the metal salt is 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 or more and 4.0 or less. <2> The electrolyte according to <1>, wherein the medium is at least one selected from the group consisting of succinonitrile, glutaronitrile, and adiponitrile. <3> The electrolyte according to <1> or <2>, wherein the metal salt is a lithium salt. <4> The electrolyte according to any one of <1> to <3>, 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＋The electrolyte according to any one of <1> to <4>, wherein the anion constituting the metal salt is at least one selected from the group consisting of bis(fluorosulfonyl)imide ion and TFSI ion. <6> The electrolyte according to any one of <1> to <5>, wherein the anion constituting the metal salt is at least one selected from the group consisting of bis(fluorosulfonyl)imide ion and TFSI ion. <7> The electrolyte according to any one of <1> to <6>, wherein the electrolyte is a solid electrolyte. <8> The electrolyte according to any one of <1> to <7>, wherein the medium is at least one nitrile medium selected from the group consisting of succinonitrile, glutaronitrile, and adiponitrile, and wherein a peak derived from the C-N stretching vibration of the nitrile group in the Raman spectrum shifts to a higher wavenumber. <9> The electrolyte according to any one of <1> to <8>, wherein the porous insulator is at least one selected from the group consisting of zeolite and mesoporous silica, and wherein the Si / Al ratio of the zeolite and the mesoporous silica is 5 or more. <10> A battery comprising the electrolyte according to any one of <1> to <9>.

[0081] Batteries including the electrolyte according to the present disclosure can be used in a variety of fields where electricity storage is anticipated. Although merely illustrative, batteries (particularly secondary batteries) including the electrolyte according to the present disclosure can be used in the fields of electricity, information, and communications where electric and electronic devices are used (for example, electric and electronic devices or mobile devices including mobile phones, smartphones, laptops, digital cameras, activity meters, arm computers, electronic paper, wearable devices, RFID tags, card-type electronic money, smart watches, and other small electronic devices), 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 port 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 installation-type power storage systems), medical applications (medical devices such as earphones and hearing aids), pharmaceutical applications (medical management systems), and the IoT field. Space and deep-sea applications (for example, space probes, submersible research vessels, and the like) can also be used.

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 said medium to said 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. 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 ion constituting the metal salt is Li ＋ , K ＋ , Na ＋ , or Mg ２＋ 2. The electrolyte of claim 1 ,

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, The electrolyte of claim 1 , wherein the zeolite and the mesoporous silica have a Si / Al ratio of 5 or more.

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

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