Electrolyte and secondary battery equipped with an electrolyte

Abstract

To provide an electrolyte with a wider potential window. [Solution] The solution comprises a polymer resin, a porous insulator, a metal salt, and a medium, wherein the metal salt comprises at least one metal salt selected from alkali metal salts, alkaline earth metal salts, and zinc salts, the mass ratio B / A of the polymer resin to the mass A of the porous insulator satisfies 10% ≤ B / A ≤ 50%, and the volume ratio X / Y of the volume X of the metal salt and medium to the pore volume Y of the porous insulator is 0%

Description

Technical Field

[0001] The present disclosure relates to an electrolyte and a secondary battery including the electrolyte.

Background Art

[0002] Patent Document 1 discloses a composite electrolyte membrane. The composite electrolyte membrane includes a porous MOF material that can bind to anions of a liquid electrolyte impregnated in a porous metal organic framework (porous MOF) and increase the cation transport rate, a mechanical support, a flame retardant, and a support matrix that functions as an electron blocking layer, and the porous MOF is incorporated into the support matrix by coating, lamination, physical mixing and pressing, in-situ growth or polymerization.

[0003] Patent Document 2 discloses a solid electrolyte. The solid electrolyte includes porous silica having a plurality of interconnected pores and an electrolyte covering the inner surfaces of the plurality of pores. The electrolyte includes 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide represented by EMI-FSI and a lithium salt dissolved in EMI-FSI, and the molar ratio of EMI-FSI to the porous silica is greater than 1.0 and less than 3.5.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, as a result of intensive studies, the inventor has found that there is still room for improvement in the electrolytes described in Patent Documents 1 and 2 with respect to the width of the potential window.

[0006] The present disclosure has been made in view of the above problems. That is, the main object of the present disclosure is to provide an electrolyte having a wider potential window. Another object of the present disclosure is to provide a secondary battery including such an electrolyte.

Means for Solving the Problems

[0007] To solve the above problems, an electrolyte according to an embodiment of the present disclosure comprises a polymer resin, a porous insulator, a metal salt, and a medium, the metal salt includes at least one metal salt selected from an alkali metal salt, an alkaline earth metal salt, and a zinc salt, a mass ratio B / A of the mass B of the polymer resin to the mass A of the porous insulator satisfies 10% ≤ B / A ≤ 50%, a volume ratio X / Y of the volume X of the metal salt and the medium to the pore volume Y of the porous insulator satisfies a relationship of 0% < X / Y < 185%. Further, a secondary battery according to another embodiment of the present disclosure comprises the above electrolyte, a positive electrode part, and a negative electrode part including a negative electrode active material.

Advantages of the Invention

[0008] The present disclosure can provide an electrolyte having a wider potential window. Further, the present disclosure can provide a secondary battery including such an electrolyte.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 shows a current-potential curve of a secondary battery including the electrolyte of Example 8. [Figure 2] FIG. 2 shows a current-potential curve of a secondary battery including the electrolyte of Comparative Example 1.

Modes for Carrying Out the Invention

[0010] The “electrolyte” and the “secondary battery” equipped with the electrolyte as described herein will be explained in detail below. While drawings will be referenced as necessary, the illustrations are provided for illustrative purposes only to aid in understanding this disclosure, and their appearance and dimensional ratios may differ from those of the actual product.

[0011] The various numerical ranges referred to herein are intended to include the lower and upper numerical values ​​themselves, unless otherwise specified, such as "less than," "smaller than," and "greater than." That is, for example, a numerical range of 1 to 10 is interpreted as including both the lower limit of 1 and the upper limit of 10.

[0012] In this disclosure, "secondary battery" broadly refers to a device equivalent to 1 or 2 that can extract energy using electrochemical reactions. In a narrower sense, "secondary battery" refers to a device comprising a pair of electrodes and an electrolyte, which is charged and discharged in particular by the movement of ions. Examples of secondary batteries, though merely illustrative, include lithium batteries, magnesium batteries, sodium batteries, and potassium batteries.

[0013] In this disclosure, unless otherwise specified, "electrolyte" means the electrolyte relating to this disclosure excluding the porous insulator and polymer resin, and consisting of a metal salt and a medium.

[0014] <First Embodiment: Electrolytes> The electrolyte according to the first embodiment of this disclosure is used, for example, in a battery. In other words, the electrolyte described herein corresponds to an electrolyte for a device that can extract energy using an electrochemical reaction.

[0015] The electrolyte according to the first embodiment is, as a premise, an electrolyte used in a battery equipped with electrodes composed of alkali metal elements (more specifically, lithium, sodium, or potassium), alkaline earth metals (more specifically, magnesium), or zinc (Zn). In particular, it is an electrolyte for a battery equipped with a lithium electrode as the negative electrode. Therefore, the electrolyte according to the first embodiment can also be said to be an electrolyte for lithium electrode-based batteries (hereinafter simply referred to as "lithium electrode-based electrolyte").

[0016] Here, the term "lithium electrode" as used herein broadly refers to an electrode having lithium (Li) as its active component (i.e., active material). In a narrower sense, "lithium electrode" refers to an electrode containing lithium, such as an electrode containing lithium metal or a lithium alloy, and more particularly, a negative electrode of such a lithium electrode. While such a lithium electrode may contain components other than lithium metal or a lithium alloy, in one preferred embodiment, it is an electrode made of a lithium metal body (for example, an electrode made of a pure lithium metal with a purity of 90% or higher, preferably 95% or higher, and more preferably 98% or higher).

[0017] 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 at room temperature (e.g., 25°C). -5 The value is on the order of S / cm or higher. The method for measuring ionic conductivity will be explained in detail in the examples.

[0018] The electrolyte according to the first embodiment is The material comprises a polymer resin, a porous insulator, a metal salt, and a medium. The metal salt comprises at least one metal salt selected from alkali metal salts, alkaline earth metal salts, and zinc salts. The mass ratio B / A of the polymer resin to the mass A of the porous insulator satisfies 10% ≤ B / A ≤ 50%. The volume ratio X / Y of the metal salt and the medium to the pore volume Y of the porous insulator satisfies the relationship 0% < X / Y < 185%. In one aspect, the electrolyte according to the first embodiment is impregnated with an electrolytic solution containing a metal salt and a medium in a support sheet including a porous insulator and a polymer resin.

[0019] [Mechanism of action] The electrolyte according to the first embodiment has a wider potential window. Without being bound by a specific theory, the reason is presumed as follows. When the volume ratio X / Y of the metal salt and the medium to the pore volume Y of the porous insulator satisfies the relationship 0% < X / Y < 185%, in the electrolyte, the medium held by the polymer resin without being filled in the pores of the porous insulator, which is less reduction-resistant than the medium filled in the pores of the porous insulator, becomes less likely to exist. Also, when the mass ratio B / A of the polymer resin to the mass A of the porous insulator satisfies 10% ≤ B / A ≤ 50%, since the polymer resin exists moderately in the electrolyte, in the production of the electrolyte, the medium is likely to be filled in the pores of the porous insulator through the polymer resin. As a result, in the electrolyte, the medium filled in the pores of the porous insulator, which is more reduction-resistant than the medium held by the polymer resin without being filled in the pores of the porous insulator, becomes more likely to exist.

[0020] [The occasion for devising the present disclosure] As a result of earnestly studying the reason why the potential window cannot be sufficiently widened in a battery including the electrolyte described in Patent Document 1, the present inventor has found that the electrolytic solution existing outside the porous insulator and in the polymer resin without being completely filled in the pores of the porous insulator chemically decomposes. In other words, the fact that the electrolytic solution chemically decomposes in the electrolyte of the battery means that the potential window cannot be sufficiently widened and also means that at least a part of the electric charge accumulated in the battery is consumed for the chemical decomposition of the medium.

[0021] Based on such technical knowledge, from the perspective of significantly reducing the unfilled medium in order to improve the reduction resistance of the medium in the electrolyte, the feature I that "the volume ratio X / Y of the metal salt and the medium to the pore volume Y of the porous insulator satisfies the relationship 0% < X / Y < 185%" was conceived. In the present specification, the chemical decomposition of the medium refers to the phenomenon of oxidation of the medium. For example, when the medium is alkylene carbonate (more specifically, ethylene carbonate), carbon dioxide desorbs from the alkylene carbonate (i.e., decarboxylation) and / or carbon monoxide desorbs and the alkylene carbonate decomposes, which is an oxidation phenomenon of the medium.

[0022] Furthermore, as a result of further intensive studies by the present inventor on how to sufficiently fill the pores of the porous insulator with the medium, in the production of the electrolyte, it was found that the pores of the porous insulator can be sufficiently filled with the medium by dropping an electrolytic solution (metal salt and medium) onto a support sheet provided with a porous insulator and a polymer resin and applying pressure. Based on the technical knowledge of temporarily holding the medium in the polymer resin and filling the pores of the porous insulator through the mediation of the polymer resin, it has come to the feature II that "the mass ratio B / A of the polymer resin to the mass A of the porous insulator satisfies 10% ≤ B / A ≤ 50%". In this way, the electrolyte according to the first embodiment of the present disclosure having the features I and II was conceived.

[0023] (Volume ratio X / Y) -Method for determining the volume ratio X / Y- The method for determining the volume ratio X / Y of the volume X of the metal salt and the medium to the pore volume Y of the porous insulator is as follows. The electrolyte (of the finished product) is subjected to a predetermined treatment (for example, solvent substitution with a low-viscosity and low-boiling-point solvent (such as dimethyl carbonate)) and then extracted and separated into the porous insulator, the metal salt, and the medium, respectively. The pore volume Y of the porous insulator is determined using the gas adsorption method. Specifically, a gas molecule (nitrogen molecule) is adsorbed onto the pores of the porous insulator using a pore size distribution measuring device ("BELSORP" manufactured by Microtrac BEL Corporation), and the adsorption / desorption curve is measured. The pore volume Y of the porous insulator is determined from the measured adsorption / desorption curve.

[0024] The method for specifying the volume X of the metal salt and the medium is as follows. The weight of the metal salt and the medium impregnated in the porous insulator was identified from the weight loss rate before and after the above extraction. In addition, the content ratio of the extracted metal salt and the medium was identified using nuclear magnetic resonance (NMR) measurement, and the volume of the metal salt and the medium was determined from the specific gravity of each contained substance.

[0025] -Numerical range- The volume ratio X / Y is more than 0% and less than 185% (i.e., 0% < X / Y < 185%). When the volume ratio X / Y exceeds 0%, the volume of the medium is not too small with respect to the pore volume of the porous insulator, so the medium can be sufficiently filled in the pores of the porous insulator. In the electrolyte, it is more chemically stable to be filled and retained in the pores of the porous insulator than to be present in the polymer resin. Therefore, the medium is less likely to be oxidized, and the electrolyte has excellent reduction resistance. Furthermore, when the volume ratio X / Y exceeds 0%, the medium can be sufficiently filled in the pores of the porous insulator, so it is easy to form the first bridge structure and the second bridge structure described later, thereby further improving the ionic conductivity of the electrolyte.

[0026] On the one hand, when the volume ratio X / Y is less than 185%, the volume of the medium is not too large with respect to the pore volume of the porous insulator. Therefore, the medium present in the polymer resin (i.e., the medium游离 from the pores of the porous insulator) does not become too much or does not exist because it is not filled in the pores of the porous insulator. For this reason, the decrease in the reduction resistance of the electrolyte is suppressed. Thereby, the ionic conductivity of the electrolyte can be further improved. Furthermore, when the volume ratio X / Y is less than 185%, the medium present in the polymer resin does not become too much or does not exist because it is not filled in the pores of the porous insulator. For this reason, most of the medium in the electrolyte constitutes the first bridge structure and the second bridge structure described later, and the contribution degree to other structures (for example, the carrier transport structure by the diffusion (Brownian motion) of the medium) becomes small. Thereby, the ionic conductivity of the electrolyte can be further improved.

[0027] In a preferred embodiment, from the viewpoint of having both more excellent ionic conductivity and a wider potential window, the volume ratio X / Y is more than 20% and less than 150% (that is, 20% < X / Y < 150%), and more than 50% and less than 150% (that is, 50% < X / Y < 150%).

[0028] (Mass ratio A / B) -Method for determining the mass ratio A / B- The method for determining the mass ratio B / A of the mass B of the polymer resin to the mass A of the porous insulator is as follows. By performing a predetermined treatment (for example, thermogravimetric measurement (TG)) on the electrolyte (of the finished product), the mass ratio of the polymer resin contained in the mixture of the porous insulator and the polymer resin is quantified, and the mass ratio B / A of the mass A of the porous insulator and the mass B of the polymer resin is determined.

[0029] -Numerical range- The mass ratio B / A is between 10% and 50% (i.e., 10% ≤ B / A ≤ 50%). When the mass ratio B / A is 10% or more, there is a sufficient amount of polymer resin relative to the porous insulator in the electrolyte. For example, in the manufacture of the electrolyte, when an electrolyte consisting of a metal salt and a medium is dropped onto a support sheet containing a porous insulator and polymer resin, and then pressure is applied to fill the pores of the porous insulator with the electrolyte (metal salt and medium), the electrolyte is temporarily held by the polymer resin, allowing the pores of the porous insulator to be sufficiently impregnated with the electrolyte. As a result, the pores of the porous insulator can be sufficiently filled with the electrolyte. This improves the reduction resistance of the electrolyte. Furthermore, when the mass ratio B / A is 10% or more, the pores of the porous insulator can be sufficiently filled with the electrolyte. As a result, the majority of the medium in the electrolyte constitutes the first bridge structure and the second bridge structure described later, and its contribution to other structures (e.g., carrier transport structure by diffusion (Brownian motion) of the medium) becomes small. This further improves the ionic conductivity of the electrolyte.

[0030] On the other hand, when the mass ratio B / A is 50% or less, the amount of polymer resin relative to the porous insulator in the electrolyte does not become excessive, so there is less of the electrolyte (metal salt and medium) that is not filling the porous insulator. Therefore, the decrease in the reduction resistance of the electrolyte can be suppressed. Furthermore, when the mass ratio B / A is 50% or less, the amount of polymer resin present between the porous insulators does not become excessive, and carrier transport is less likely to be inhibited. Therefore, the decrease in the ionic conductivity of the electrolyte is suppressed.

[0031] In a preferred embodiment, the mass ratio B / A is 10% to 30% (i.e., 10% ≤ B / A ≤ 30%) from the viewpoint of improving the ionic conductivity of the electrolyte.

[0032] (Mass ratio (medium / metal salt)) In a preferred embodiment, the mass ratio of the medium to the metal salt (medium / metal salt) is 0.1 or more and 10 or less. When the mass ratio is 0.1 or more or 10 or less, the ionic conductivity increases. From the viewpoint of further improving the ionic conductivity of the electrolyte, the mass ratio is 0.5 or more and 1 or less.

[0033] (Mass ratio (medium / metal salt)) -Method for determining the mass ratio (medium / metal salt)- The method for determining the mass ratio (medium / metal salt) is as follows: The electrolyte (of the finished product) undergoes a predetermined treatment (for example, the content ratio of metal salt and medium is identified using nuclear magnetic resonance (NMR) measurement).

[0034] This section will explain in detail how to further improve the ionic conductivity of the electrolyte at a specific mass ratio (medium / metal salt). Although not bound by any particular theory, the reason is presumed to be as follows. In the electrolyte according to the first embodiment, the metal salt and the medium can take on a bridge structure at a specific mass ratio (medium / metal salt = 0.1 to 10). Specifically, the electrolyte according to the first embodiment can take on at least one of the following: a bridge structure in which the medium and the positive ions (more specifically, metal ions) constituting the metal salt are arranged alternately (hereinafter also referred to as the "first bridge structure"), and a bridge structure in which the positive ions constituting the metal salt and the negative ions constituting the metal salt are arranged alternately (hereinafter also referred to as the "second bridge structure").

[0035] When the first and second bridge structures are placed within the pores of a porous insulator, they form defects (holes) where metal ions are partially missing, which can serve as pathways for efficient transport of metal ions within the electrolyte. Therefore, in the electrolyte according to this embodiment, the ionic conductivity of metal ions is enhanced by forming the above-mentioned bridge structures within the pores of the porous insulator.

[0036] (First bridge structure) The electrolyte according to this embodiment preferably has a first bridge structure from the viewpoint of further improving ion conductivity. In the first bridge structure, a medium and positive ions constituting a metal salt are alternately arranged, and some of the positive ions (metal ions) are missing. [Chemical formula 1]:

Chemical formula

[0037] In the first bridge structure, arranging linearly means, for example, that ethylene carbonate and Li + are arranged linearly. However, the arrangement mode of ethylene carbonate and Li + is not limited to this. For example, ethylene carbonate and Li +The arrangement may be two-dimensional or three-dimensional, and more specifically, a linear arrangement may be curved or branched.

[0038] (Method for confirming the first bridge structure) The first bridge structure can be confirmed by structural analysis using Raman spectroscopy. As mentioned above, the first bridge structure can be constructed when the metal ions of the metal salt coordinate to the medium. In other words, the first bridge structure can be constructed when the metal ions form coordinate bonds with specific functional groups of the medium. Therefore, the existence of the first bridge structure can be confirmed by observing, using micro-Raman spectroscopy, that "the peak originating from the specific vibration of the coordinating functional group is shifted to a higher wavenumber side compared to the peak originating from the specific vibration of the non-coordinated functional group."

[0039] Ethylene carbonate - Li + The first bridge structure in the system is characterized by "a shift to higher wavenumbers of peaks (Raman scattering peaks) originating from the respiratory oscillations of the heterocycle of the medium (ethylene carbonate)." Its existence can be confirmed by using micro-Raman spectroscopy. This can be confirmed by observing that the peak attributed to the respiratory oscillations of the heterocycle of ethylene carbonate coordinated to a metal ion is shifted to a higher wavenumber side compared to the peak attributed to the respiratory oscillations of the heterocycle of ethylene carbonate not coordinated to a metal ion (a known peak).

[0040] Also, sulfolane-Li + The presence of the first bridge structure in the system can be confirmed by the shift of the peak to the higher wavenumber side, which originates from the SO2 bending vibration of the sulfonyl group of the medium (sulfolane). Furthermore, γ-butyrolactone (GBL)-Li + The presence of the first bridge structure in the system can be confirmed by the shift of the peak to the higher wavenumber side, which originates from the stretching vibration of the heterocycle of the medium (GBL).

[0041] The method for verifying the first bridge structure will be described in the example.

[0042] (Second bridge structure) The electrolyte according to the first embodiment preferably has a second bridge structure from the viewpoint of further improving ionic conductivity. In the second bridge structure, positive ions constituting the metal salt and negative ions constituting the metal salt are arranged alternately. [Chemical Formula 2]: [ka] The second bridge structure will be described in detail with reference to [Chemical Formula 2]. As an example of the electrolyte according to this embodiment, metal ions Li in the pores of a porous insulator + The text also lists electrolytes containing metal salts composed of negative ions such as Li. + -In the FSI system, the second bridge structure is formed when the sulfonyl group (oxygen atom) of the FSI ion is connected to Li + It coordinates with the FSI ion and Li + and are arranged alternately in a one-dimensional manner, and in some parts Li + It has a defect where it is missing (indicated by the dashed circle in [Chemical Formula 2]). + From this perspective, when we look at the second bridge structure, the second bridge structure is adjacent Li + These are bridged by FSI ions. And Li + Because of the defect, adjacent Li ions can be transmitted via FSI ions. + Li can move to the defect. In this way, Li + Because the metal ions can move sequentially within the second bridge structure, the second bridge structure is thought to contribute to the efficient transport of metal ions within the electrolyte, thereby achieving superior ionic conductivity.

[0043] In the second bridge structure, one-dimensional arrangement means, for example, FSI ions and Li + This refers to the arrangement of FSI ions and Li in a linear chain. + The arrangement configuration is not limited to this. For example, FSI ions and Li + The arrangement may be two-dimensional or three-dimensional, and more specifically, a linear arrangement may be curved or branched.

[0044] (Method for confirming the second bridge structure) The second bridge structure can be confirmed by structural analysis using Raman spectroscopy. As mentioned above, the second bridge structure can be constructed when the metal ion of the metal salt coordinates to the negative ion. In other words, the second bridge structure can be constructed when the metal ion forms a coordinate bond with a specific functional group of the negative ion. Therefore, the existence of the second bridge structure can be confirmed by observing, using micro-Raman spectroscopy, that "the peak originating from the specific vibration of the coordinating functional group is shifted to a higher wavenumber side compared to the peak originating from the specific vibration of the non-coordinated functional group."

[0045] For example, in the case of the metal salt LiFSI mentioned above, its existence can be confirmed by observing, using micro-Raman spectroscopy, that "in the Raman spectrum, the peak originating from the SNS stretching vibration of the negative ion constituting the metal salt is shifted to the higher wavenumber side." For example, if the negative ion constituting the metal salt is an FSI ion, this can be confirmed by observing that the peak attributed to the SNS stretching vibration of the sulfonyl group coordinated to the metal ion is shifted to the higher wavenumber side compared to the peak attributed to the SNS stretching vibration of the sulfonyl group not coordinated to the metal ion (a known peak). The method for confirming the second bridge structure will be described in detail in the examples.

[0046] The electrolyte according to this embodiment may be a solid electrolyte.

[0047] The electrolyte according to this embodiment comprises a polymer resin, a porous insulator, a medium, and a metal salt. The electrolyte according to this embodiment may further comprise components other than these components (porous insulator, medium, and metal salt) to the extent that it achieves the main effects of this disclosure. The components constituting the electrolyte will be described below.

[0048] (polymer resin) Polymer resins bind porous insulators. Furthermore, polymer resins can act as an impregnation medium in the process of impregnating porous insulators with electrolytes (metal salts and media) during the electrolyte manufacturing process. In other words, by temporarily holding the electrolyte in the polymer resin and applying pressure to impregnate the support sheet with the electrolyte, it is possible to sufficiently impregnate the pores of the porous insulator with the electrolyte while preventing the polymer resin from retaining excess electrolyte.

[0049] Examples of polymer resins include natural latex resins, polytetrafluoroethylene resins, polyvinylidene fluoride resins (more specifically, polyvinylidene fluoride), alkylene oxide resins (more specifically, polyethylene oxide), styrene-butadiene resins, acrylic resins (more specifically, polyacrylic acid), ester resins, urethane resins, cellulose resins (more specifically, carboxymethylcellulose or hydroxypropylcellulose), polyaramid resins (more specifically, polyaramid), polyimide resins (more specifically, polyimide), polyvinyl alcohol resins (more specifically, polyvinyl alcohol), polyacrylamide resins (more specifically, polyacrylamide), or combinations thereof.

[0050] (Porous insulator) A porous insulator has a medium and a metal salt arranged within its pores. This makes it easier for the electrolyte according to the first embodiment to form a first bridge structure and a second bridge structure that contribute to better ionic conductivity. The porous insulator has pores. The porous insulator is, for example, at least one selected from the group consisting of metal-organic frameworks (MOFs), zeolites, and mesoporous silica.

[0051] From the viewpoint of improving the ionic conductivity of the electrolyte, the porous insulator is preferably zeolite and mesoporous silica. Although not bound by any particular theory, if the electrolyte contains at least one of zeolite and mesoporous silica as a porous insulator, then the silanol groups (Si-OH) present on the inner walls of the pores of the zeolite and mesoporous silica act as carriers (positive ions of metal salts, more specifically, Li + It is thought to function as a hopping site for protons (H) of the silanol group. More specifically, the proton (H) of the silanol group + It is thought that the silanol groups function as carrier hopping sites through exchange between the silanol groups and the carriers. Therefore, the ionic conductivity of the electrolyte is further improved when the electrolyte contains at least one of zeolite and mesoporous silica as a porous insulator.

[0052] In porous insulators, particularly zeolites and mesoporous silica, the Si / Al ratio is, for example, 5 or more, preferably 15 or more, more preferably 30 or more, even more preferably 100 or more, especially preferably 500 or more, and very especially preferably 770 or more, from the viewpoint of improving the ionic conductivity of the electrolyte. In this specification, the Si / Al ratio refers to the molar ratio of Si (silicon atoms) to Al (aluminum atoms) constituting the porous insulator.

[0053] When the Si / Al ratio is 5 or higher, zeolites and mesoporous silica can have more silanol groups on the inner walls of their pores. In such cases, it is thought that more carrier hopping sites can be present on the inner walls of the pores of zeolites and mesoporous silica, further improving the ionic conductivity of the electrolyte.

[0054] The Si / Al ratio of zeolite and mesoporous silica is measured as follows: The zeolite or mesoporous silica is pulverized to a level suitable for measurement and placed in a nuclear magnetic resonance spectrometer (JEOL "ECA400 FT-NMR spectrometer"). Magnetic field strength 9.2T and nuclide: 29The measurement is performed under Si measurement conditions to obtain an NMR spectrum. The Si / Al ratio is obtained by spectral analysis. Furthermore, the zeolite or mesoporous silica used for measuring the Si / Al ratio can be measured not only in its raw material state, but also after being separated from the finished product (for example, the electrolyte or a battery containing the electrolyte (more specifically, the measurement cell battery described later in the examples)).

[0055] Examples of commercially available metal-organic structures include Strem Chemicals' "UiO-67," "HKUST-1," and "F-free MIL-100(Fe)(KRICT(trademark)F100)," as well as MERCK's "ZIF-8(Basolite(registered trademark)(Z1200))" and "MIL-53(Basolite Examples of commercially available zeolites include "HS-690", "HS-642", and "HS-320" from Fujifilm Wako Pure Chemical Corporation, and "HSZ-360HUA", "HSZ-385HUA", "HSZ-390HUA", "HSZ-660HOA", "HSZ-840HOA", "HSZ-890HOA", and "HSZ-980HOA" from Tosoh Corporation. Examples of commercially available mesoporous silica include "MCM-41", "MCM-48", "SBA-15", and "SBA-16" from Sigma-Aldrich.

[0056] (medium) The medium is an electrically neutral molecule. The medium disperses, dissolves, or solid-solves metal salts in an electrolyte. Examples of mediums include carbonate media, cyclic ester media (carboxylic acid ester media), cyclic ester media (lactone media and sulfonic acid ester media), linear ether media, cyclic ether media, ketone media, sulfoxide media, oxazolidine media, and ionic liquids.

[0057] Examples of carbonate-based media include ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), butyl methyl carbonate (BMC), ethyl propyl carbonate (EPC), and dipropyl carbonate (DPC).

[0058] Examples of carboxylic acid ester media include methyl acetate, ethyl acetate, isobutyrylmethyl acetate, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, and diethyl oxalate. Examples of lactone-based media include γ-butyrolactone and γ-valerolactone. Examples of sulfonic acid erate-based media include 1,3-propanesultone.

[0059] Examples of linear ether-based media include 1,2-dimethoxyethane and diethyl ether. Examples of cyclic ether media include tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, and dioxane.

[0060] An example of a ketone-based drug is cyclopentanone. Examples of sulfoxide-based media include dimethyl sulfoxide and sulfolane. Examples of oxazolidine-based media include 3-methyl-1,3-oxazolidine-2-one. If the medium is at least one of these, it is easier to form a first bridge structure with the metal ions constituting the metal salt in the electrolyte. Therefore, in this case, the ionic conductivity of the electrolyte according to the first embodiment becomes higher.

[0061] (Metal salts) The metal salt is at least one selected from the group consisting of alkali metal salts, alkaline earth metal salts, and zinc salts. Examples of alkali metal salts include lithium metal salts, sodium metal salts, or potassium metal salts. In other words, the positive ions constituting the alkali metal salt are Li + , K + kaNa + Examples include magnesium metal salts. In other words, examples of positive ions constituting alkaline earth metal salts include Mg 2+ Examples include: The positive ions that make up zinc salts are, for example, Zn 2+ Examples of counterions (negative ions) that constitute alkali metal salts, alkaline earth metal salts, and zinc salts include hexafluorophosphate ion, hexafluoroarsenate ion, bis(trifluoromethylsulfonylimide) ion (TFSI), bis(trifluorosulfonylimide) ion, trifluoromethanesulfonate ion, fluoroalkylsulfonimide ion, fluoroarylsulfonimide ion, bis(oxalate borate) ion, tris(trifluoromethylsulfonylimide)methide ion, and tetrafluoroborate ion (BF4). - ), perchlorate ion (ClO4 - Examples include tetrachloroaluminate ions or chloride ions.

[0062] Examples of lithium metal salts include lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonylimide) (LiTFSI), lithium bis(trifluorosulfonylimide), lithium trifluoromethanesulfonate, lithium fluoroalkylsulfonimide, lithium fluoroarylsulfonimide, lithium bis(oxalate borate), lithium tris(trifluoromethylsulfonylimide)methide, lithium tetrafluoroborate, lithium perchlorate, lithium tetrachloroaluminate, lithium chloride, or combinations thereof.

[0063] Examples of sodium metal salts include sodium trifluoromethanesulfonate, NaClO4, NaPF6, NaBF4, NaTFSI (sodium(I)bis(trifluoromethanesulfonyl)imide), NaFSI (sodium(I)bis(fluorosulfonyl)imide), or combinations thereof.

[0064] Examples of magnesium metal salts include magnesium trifluoromethanesulfonate, Mg(ClO4)2, Mg(PF6)2, Mg(BF4)2, Mg(TFSI)2 (magnesium(II) bis(trifluoromethanesulfonyl)imide), Mg(FSI)2 (magnesium(II) bis(fluorosulfonyl)imide), or combinations thereof.

[0065] Examples of zinc salts include zinc trifluoromethanesulfonate, Zn(ClO4)2, Zn(PF6)2, Zn(BF4)2, Zn(TFSI)2 (zinc(II) bis(trifluoromethanesulfonyl)imide), Zn(FSI)2 (zinc(II) bis(fluorosulfonyl)imide), or combinations thereof.

[0066] [Method for producing electrolytes] An example of a method for producing an electrolyte according to the first embodiment will be described. The method for producing an electrolyte according to the first embodiment comprises the steps of: preparing an electrolyte solution comprising a metal salt and a medium (electrolyte solution preparation step); producing a support sheet comprising a polymer resin and a porous insulator (support sheet production step); and impregnating the support sheet with the electrolyte solution to produce an electrolyte (impregnation step). Note that the order of the electrolyte solution preparation step and the support sheet production step may be reversed.

[0067] -Electrolyte preparation process- The electrolyte preparation step involves preparing an electrolyte comprising a metal salt and a medium. The medium does not necessarily have to be a liquid at room temperature (25°C) (for example, a solid, a pseudo-solid (more specifically, a solid mixed in a liquid)), in which case the electrolyte may be prepared by heating.

[0068] -Support sheet manufacturing process- The support sheet manufacturing process involves preparing a support sheet containing a polymer resin and a porous insulator. Specifically, first, a slurry is prepared by dispersing and / or dissolving the polymer resin and porous insulator in a solvent. The solvent can be any solvent that disperses and / or disperses the polymer resin and porous insulator and has a certain degree of volatility (i.e., has a boiling point that is not too high), for example, N-methyl-2-pyrrolidone (NMP). Next, the slurry is applied to a substrate to form a coating film, and the coating film is pre-dried. The pre-drying temperature is, for example, 100°C to 150°C. During the drying of the sheet-like coating film, the solvent and water contained in the coating film are removed.

[0069] After pre-drying, pressure (e.g., 10-40 MPa) is applied to the coating film using a press (e.g., a single-screw press) to form it into a sheet. The sheet-like coating film is then dried. In this way, a support sheet is produced. During the pre-drying of the coating film, it is dried to a degree that it can be processed into a sheet. The drying conditions for the coating film depend on the type (boiling point, etc.) and amount of solvent used, as well as the type of polymer resin (affinity with the solvent, etc.). For example, the drying atmosphere may be vacuum or reduced pressure, the drying temperature may be 80°C to 130°C, and the drying time may be half a day to several days. Drying may also be performed in multiple stages.

[0070] -Impregnation process- The impregnation process involves impregnating a support sheet with an electrolyte solution to create the electrolyte. Specifically, the electrolyte solution is first dropped onto the support sheet. If the prepared electrolyte solution is not liquid at room temperature (25°C) (for example, a solid or pseudo-solid (more specifically, a solution with solid particles mixed in)), the electrolyte solution can be heated to a liquid state and then impregnated into the porous insulator.

[0071] Next, pressure is applied to the support sheet onto which the electrolyte has been dropped using a press (for example, a single-screw press) to impregnate the support sheet with the dropped electrolyte. This fills the pores of the porous insulator with the electrolyte, creating an electrolyte. The applied pressure is, for example, 100 to 300 MPa.

[0072] <Second Embodiment: Battery> The battery according to the second embodiment comprises the electrolyte according to the first embodiment. In addition to the electrolyte, the battery according to the second embodiment may further comprise a positive electrode (positive electrode portion) and a negative electrode (for example, a negative electrode portion containing a negative electrode active material).

[0073] In the battery according to the second embodiment, the positive electrode includes materials constituting the positive electrode (more specifically, positive electrode active material, etc.). The negative electrode includes alkali metals (more specifically, Li, Na, K), alkaline earth metals (more specifically, Mg), or zinc as materials constituting the negative electrode (specifically, negative electrode active material). The negative electrode includes, for example, elements of alkali metals or alkaline earth metals (more specifically, plates, foils, and layers) and compounds thereof.

[0074] In the battery according to the second embodiment, since it is equipped with the electrolyte according to the first embodiment which has a relatively wide potential window, the negative electrode active material may include at least one of carbon (C), silicon (Si), and tin (Sn). Examples of forms of carbon (C) as the negative electrode active material include graphite (natural graphite, artificial graphite), hard carbon, soft carbon, or diamond-like carbon. The negative electrode active material may include an oxide or a lithium alloy. Examples of oxides include at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, and lithium oxide. As for the lithium alloy, any metal that can form an alloy with lithium may be used, for example, a binary, ternary, or more-dimensional alloy of lithium with metals such as Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, and La.

[0075] The battery according to the second embodiment can be configured as a secondary battery. During charging, metal ions (M n+ (M represents a metallic element, and n represents a positive integer): More specifically, Li + kaNa + , K + and Mg 2+During discharge, metal ions (such as metal ions) move from the positive electrode through the electrolyte to the negative electrode, converting electrical energy into chemical energy for storage. During discharge, metal ions return from the negative electrode through the electrolyte to the positive electrode, generating electrical energy.

[0076] In a preferred embodiment, the average charging potential of the negative electrode active material is 1.0V vs Li + It is less than / Li. The average charging potential of the negative electrode active material is 1.0V vs Li + It is less than or equal to / Li. Because it is equipped with an electrolyte according to the first embodiment which has a relatively wide potential window, it has excellent reduction resistance, and even with a negative electrode active material with a low average charging potential, side reactions are less likely to occur and a high energy density can be achieved.

[0077] The embodiments of this disclosure have been described above, but these are merely typical examples. Therefore, those skilled in the art will easily understand that this disclosure is not limited thereto, and various embodiments are conceivable without altering the gist of this disclosure.

[0078] For example, the electrolyte composition, raw materials used in manufacturing, manufacturing method, manufacturing conditions, electrolyte characteristics, and battery configuration or structure described above are illustrative examples and are not limited to these, and can be changed as appropriate. Examples of batteries include lithium batteries, magnesium batteries, sodium batteries, and potassium batteries, as well as air batteries and fuel cells. [Examples]

[0079] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to these examples.

[0080] <Example 1> [1. Preparation of electrolytes] (1-1. Ingredients) The following ingredients were used. -Porous insulator: Zeolite- • Tosoh Corporation's "HSZ-390HUA" (Crystal system: Y-type, Si / Al ratio = 500, Cation species: H) -Porous insulator: Mesoporous silica- • Sigma-Aldrich "MCM-48" -Metal salts- • Lithium bis(fluorosulfonyl)imide (manufactured by Kishida Chemical Co., Ltd. (for LBG); hereinafter also referred to as "LiFSI") -Medium: Carbonate-based media- • Ethylene carbonate (manufactured by Kishida Chemical Co., Ltd.; hereinafter also referred to as "EC") • Fluoroethylene carbonate (fluoroethylene carbonate) (manufactured by Kishida Chemical Co., Ltd.; hereinafter also referred to as "FEC") -Polymer resin- • Polyvinylidene fluoride (PVDF) (Solvay's "solef5130") -solvent- • N-methyl-2-pyrrolidone (NMP) (manufactured by Kishida Chemical Co., Ltd.)

[0081] (1-2. Preparation of electrolyte slurry) HSZ-390HUA, used as a porous insulator (zeolite), and polyvinylidene fluoride (PVDF), used as a polymer resin, were dispersed in N-methyl-2-pyrrolidone (NMP) as a solvent, according to the polymer resin ratios shown in Table 1. A slurry was then prepared.

[0082] (1-3. Preparation of support sheets) The obtained slurry was applied to a PET substrate to a desired thickness to form a coating film. The coating film was dried at 130°C. Then, a molded sheet was produced by molding it using a uniaxial press at an applied pressure of 24 MPa. After cutting the produced molded sheet to a desired size, it was vacuum-dried overnight at 100°C to remove any undried solvent (NMP) and moisture. This resulted in obtaining a support sheet.

[0083] (1-4. Preparation of Electrolyte) LiFSI (lithium bis(fluorosulfonyl)imide), as a metal salt, was added to EC (ethylene carbonate) as a medium in the predetermined ratio shown in Table 1 (LiFSI / EC = 1 / 10 (wt / wt)) to obtain a mixture. The electrolyte was prepared by stirring and dissolving the mixture while heating as needed (e.g., 90°C).

[0084] (1-5. Preparation of electrolytes) The electrolyte prepared in 1-4 was dropped onto the support sheet made in 1-3, and the sheet was pressed at 200 MPa using a single-screw press to impregnate the support sheet with the electrolyte (impregnation treatment). The amount of electrolyte dropped was equivalent to the "volume ratio X / Y (%) of the volume of metal salt and medium to the pore volume Y of the porous insulator" shown in Table 1. The impregnation treatment was carried out in a glove box under an argon atmosphere. In this way, the electrolyte of Example 1 (sheet-shaped electrolyte, electrolyte sheet) was obtained.

[0085] [2. Measurement Methods and Evaluation Methods] (2-1. Structural analysis of electrolytes by Raman spectroscopy) The electrolyte from Example 1 was subjected to structural analysis using Raman spectroscopy. The electrolyte sheet prepared in [1. Preparation of Electrolytes] was used as a measurement sample for structural analysis. The obtained measurement sample was placed in a micro-laser Raman spectrometer ("LabRam HR Evolution" manufactured by Horiba, Ltd.). Infrared laser light (wavelength 1064 nm) was irradiated onto the surface of the measurement sample, and the Raman spectrum was measured using an objective lens with a spot diameter of 7 μm. Alternatively, the Raman spectrum may be measured by irradiating the cross-section formed by cutting the measurement sample (electrolyte) for structural analysis with infrared laser light.

[0086] Based on the evaluation criteria below, we determined whether the Raman peaks in the Raman spectrum, which are caused by the characteristic structures (functional groups, etc.) of the metal salts and media constituting the electrolyte, were significantly shifted to higher frequencies compared to the Raman peaks caused by the characteristic structures (functional groups, etc.) of the metal salts and media in isolation (known data).

[0087] (Evaluation criteria for shift towards high frequencies) Shifted to the high-frequency side: Raman peaks caused by the characteristic structure (functional groups, etc.) of the metal salts and medium constituting the electrolyte are shifted by 10 cm compared to Raman peaks caused by the characteristic structure (functional groups, etc.) of the isolated metal salts and medium (known data). -1 In summary, it is shifted to the high-frequency side. Not shifted to the high-frequency side: Raman peaks caused by the characteristic structure (functional groups, etc.) of the metal salt and medium constituting the electrolyte are 10 cm apart from Raman peaks caused by the characteristic structure (functional groups, etc.) of the isolated metal salt and medium (known data). -1 It is shifted to the lower, higher frequency side.

[0088] (2-2. Measurement of Ionic Conductivity) - Preparation of measurement cells - The prepared electrolyte was pressed at 200 MPa using a single-screw press. A PET resin mold with upper and lower punches was used as the press die. Specifically, the PET resin mold had a cylindrical shape with a cylindrical through-opening along its central axis. The punches were cylindrical and were positioned to be insertable and removable from the through-opening of the mold, with the tip surfaces (surfaces perpendicular to the insertion direction) of the upper and lower punches facing each other. Powdered electrolyte was placed in the through-opening of the mold so as to be sandwiched between the tip surfaces of the upper and lower punches. The electrolyte was molded by pressing the upper and lower punches with a single-screw press. Furthermore, the upper and lower punches on the PET resin mold were used as blocking electrodes to create a measurement cell. The measurement cell was sealed in a laminate with tab electrodes to create a cell for measuring ion conductivity as a measurement sample. The preparation of the measurement sample was performed in a glove box under an argon atmosphere.

[0089] -Measurement of ionic conductivity- The ionic conductivity of the sample was measured using an impedance meter (VMP3, manufactured by Biologic). Ionic conductivity was measured using the AC impedance method at room temperature (25°C). The ionic conductivity was calculated by varying the voltage amplitude by 100mV from 1MHz to 0.1Hz, and the measurement result was taken as the intersection point of the measurement result and the real axis in a Cole-Cole plot. Table 1 summarizes the ionic conductivity measurement results. In Table 1, values ​​"E-04," "E-05," and "E-06" represent 10 -4 10 -5 and 10 -6 This indicates.

[0090] (2-3. Measurement method for potential windows) - Preparation of measurement cells - After the ionic conductivity measurement was completed, the ionic conductivity measurement cell was disassembled in a glove box under an argon atmosphere, and the electrolyte sheet was removed. The removed electrolyte sheet was sandwiched between metallic Li (thickness 0.24 mm, Φ8 mm) and Cu foil (thickness 0.01 mm, Φ10 mm) and inserted into a 2032 type coin cell. The cell was then sealed using a crimping machine to create a measurement cell (coin cell for potential window testing).

[0091] -Measurement of potential window- The fabricated coin cell for potential window testing was subjected to potential window testing using an electrochemical characterization device. The potential window measurement test was conducted at 25°C, sweeping the coin cell for potential window measurement at a speed of 10 mV / sec from the open-circuit potential (OCV) to the lower limit voltage of -0.05 V vs Li / Li. + The scan was performed up to this point. This yielded a current-potential curve.

[0092] -Method for evaluating the size of the potential window- In the obtained current-potential curve, from the open-circuit potential (OCV), 0V vs Li / Li + The potential window size was determined based on the current values ​​within the specified range, according to the following evaluation criteria. The results are shown in Table 1. (Evaluation criteria for the size of the potential window) ○ (Broad: Good): Current value is -0.001 mA / cm 2 Not below × (Narrow: Bad): Current value is -0.001mA / cm 2 Below In the evaluation method for the potential window size, the current value is defined in this specification as the open-circuit potential (OCV) of the current-potential curve, 0V vs Li / Li + This refers to the current value in the negative current region within that range.

[0093] <Examples 2-14 and Comparative Example 1> The electrolytes for Examples 2-14 and Comparative Example 1 were prepared in the same manner as in Example 1, except that at least one of the following was changed: the type of porous insulator and medium, the volume ratio of the electrolyte to the pore volume, the mass ratio of the polymer resin, and the mass ratio of the medium to the metal salt. The ionic conductivity and potential window of the electrolytes in Examples 2-14 and Comparative Examples 1-2 were evaluated in the same manner as in Example 1. These results are shown in Table 1. Furthermore, if the concentration of the metal salt in the electrolyte, which consists of a metal salt and a medium, is relatively high (i.e., the concentration of the medium is relatively low), the electrolyte may become a solid or a liquid with precipitated solid at room temperature (25°C). In such cases, the prepared electrolyte was heated until the solid was completely dissolved (e.g., 100°C) to become a liquid before the impregnation treatment was performed.

[0094] <Comparative Example 2> [1. Preparation of electrolytes] (1-1. Preparation of Electrolyte) LiFSI (lithium bis(fluorosulfonyl)imide), as a metal salt, was added to EC (ethylene carbonate) as a medium in the predetermined ratio shown in Table 1 (LiFSI / EC = 1 / 10 (wt / wt)) to obtain a mixture. The electrolyte was prepared by stirring and dissolving the mixture while heating as needed (e.g., 90°C).

[0095] (1-2. Preparation of electrolytes) HSZ-390HUA, used as a porous insulator (zeolite), was dried under vacuum and at 300°C. The dried HSZ-390HUA was impregnated with a prepared electrolyte, filling the pores of the HSZ-390HUA with the electrolyte. This prepared a powdered electrolyte. This impregnation process involved mixing the electrolyte and porous insulator by hand using a mortar and pestle, followed by pressing with a single-screw press at a pressure of 200 MPa. The amount of electrolyte impregnated (volume) was set to 100% of the pore volume of the porous insulator (HSZ-390HUA) as measured beforehand. The electrolyte was prepared in a glove box under an argon atmosphere.

[0096] For the electrolyte of Comparative Example 2, ionic conductivity and potential window measurements were performed in the same manner as in Example 1. These results are shown in Table 1.

[0097] [Table 1]

[0098] [3. Results: Examples 1-14 and Comparative Examples 1-2] (3-1. Potential Window) The electrolytes of Examples 1 to 14, as shown in Table 1, comprised a polymer resin, a porous insulator, a metal salt, and a medium, where the metal salt was an alkali metal salt (Li salt). Furthermore, the mass ratio B / A (mass of polymer resin to mass A of porous insulator) was between 10% and 50%. The volume ratio X / Y (volume X of metal salt and medium to pore volume Y of porous insulator) was greater than 0% and less than 185%. All of the electrolytes of Examples 1 to 14 were included within the scope of the invention as described in Claim 1. As shown in Table 1, all electrolytes in Examples 1 to 14 received a "○" (good) evaluation result for the potential window.

[0099] On the other hand, as shown in Table 1, the electrolyte of Comparative Example 1 had a volume ratio X / Y of the volume of the metal salt and the medium to the pore volume Y of the porous insulator, which was 185%, outside the numerical range of greater than 0% and less than 185%. As shown in Table 1, the electrolyte of Comparative Example 2 had a mass ratio B / A of the mass of the polymer resin to the mass A of the porous insulator, which was 0% (i.e., no polymer resin was present), outside the numerical range of 10% or more and 50% or less. Neither the electrolytes of Comparative Examples 1 nor 2 were included in the scope of the invention according to claim 1. As shown in Table 1, the electrolytes in Comparative Examples 1 and 2 all received a × (poor) evaluation result for their potential window. In Comparative Example 1, the large volume ratio X / Y of the electrolyte resulted in a large amount of free Li salts and media that could not be fully filled into the pores of the porous insulator, which is thought to impair the relatively wide potential window. In Comparative Example 2, the electrolyte did not contain a polymer resin, resulting in insufficient filling of the pores of the porous insulator with the electrolyte (electrolyte consisting of Li salts and media), leading to a large amount of free Li salts and media, which is thought to impair the relatively wide potential window.

[0100] From the above, it is clear that the electrolytes of Examples 1 to 14, which are included in the scope of the invention according to claim 1, have a wider potential window than the electrolytes of Comparative Examples 1 to 2, which are not included in the scope of the invention according to claim 1.

[0101] (3-2. Structural analysis of electrolytes by Raman spectroscopy) The electrolytes of Examples 1-8 and Comparative Examples 1-2 were subjected to structural analysis using Raman spectroscopy.

[0102] -First Bridge Structure- Specific frequency range (870-930 cm⁻¹) of the Raman spectra of Examples 1-8 -1 ) 900~910cm -1 A peak was observed in the vicinity. This peak originates from the ring respiratory oscillation (heterocyclic respiratory oscillation) of ethylene carbonate (EC) in the electrolyte of the EC-LiFSI system at 895 cm⁻¹. -1 The nearby peak was attributed to the peak that had shifted to the higher wavenumber side. On the other hand, the Raman spectra of Comparative Examples 1-2 show a peak with a lower intensity (900-910 cm⁻¹) compared to Examples 1-8. -1 Nearby peaks were observed only slightly or not observed at all.

[0103] Based on the structural analysis of the electrolyte by the above Raman spectroscopy method, in the EC-LiFSI system electrolyte, in the example, the Li constituting the metal salt + In the first comparison, it is thought that the EC, acting as the medium, forms a first bridge structure. On the other hand, in the comparative example, it is thought that the first bridge structure is only slightly formed or not formed at all.

[0104] -Second Bridge Structure- Specific frequency ranges (680-800 cm⁻¹) of the Raman spectra of Examples 1-8 -1 ) 740~760cm -1 A peak was observed in the vicinity. This peak originates from the SNS stretching oscillation of the FSI anion and is 710-740 cm. -1 The nearby peak was attributed to the peak that had shifted to the higher wavenumber side. On the other hand, the Raman spectra of Comparative Examples 1-2 show peaks with lower intensity (710-740 cm⁻¹) compared to Examples 1-8. -1 Nearby peaks were observed only slightly or not observed at all.

[0105] Based on the structural analysis of the electrolyte by the above Raman spectroscopy method, in the EC-LiFSI system electrolyte, in the example, the Li constituting the metal salt + It is thought that a second bridge structure is formed between the FSI anion and the FSI anion. On the other hand, in the comparative example, it is thought that a second bridge structure is formed only slightly or not at all.

[0106] The embodiments of the electrolyte and secondary battery relating to this disclosure are as follows: <1> The material comprises a polymer resin, a porous insulator, a metal salt, and a medium. The metal salt contains at least one metal salt selected from alkali metal salts, alkaline earth metal salts, and zinc salts, The mass ratio B / A of the mass B of the polymer resin to the mass A of the porous insulator satisfies 10% ≤ B / A ≤ 50%, An electrolyte in which the volume ratio X / Y of the volume X of the metal salt and the medium to the pore volume Y of the porous insulator satisfies the relationship 0% < X / Y < 185%. <2> The electrolyte according to <1>, wherein an electrolytic solution containing the metal salt and the medium is impregnated in a support sheet including the porous insulator and the polymer resin. <3> The electrolyte according to <1> or <2>, wherein the mass ratio B / A satisfies 10% ≤ B / A ≤ 30%. <4> The electrolyte according to any one of <1> to <3>, wherein the volume ratio X / Y satisfies 20% ≤ X / Y ≤ 150%. <5> The electrolyte according to any one of <1> to <4>, wherein the volume ratio X / Y satisfies 50% ≤ X / Y ≤ 150%. <6> The electrolyte according to any one of <1> to <5>, wherein the mass ratio (medium / metal salt) of the medium to the metal salt is 0.1 or more and 10 or less. <7> The electrolyte according to any one of <1> to <6>, wherein the porous insulator is at least one selected from the group consisting of a metal-organic framework (MOF), zeolite, and mesoporous silica. <8> A secondary battery including the electrolyte according to any one of <1> to <7>, a positive electrode portion, and a negative electrode portion including a negative electrode active material. <9> The average charging potential of the negative electrode active material is 1.0 V vs Li + / Li or less, and the secondary battery according to <8>. <10> The secondary battery according to <8> or <9>, wherein the negative electrode active material contains at least one of C, Si, and Sn.

Industrial Applicability

[0107] The secondary battery equipped with the electrolyte described herein can be used in various fields where energy storage is anticipated. Although these are merely examples, secondary batteries equipped with the electrolyte described herein can be used in the electrical, information, and communication fields where electrical and electronic equipment is used (for example, the electrical and electronic equipment field or mobile device field, including mobile phones, smartphones, laptops and digital cameras, activity trackers, ARM computers, electronic paper, wearable devices, and small electronic devices such as RFID tags, card-type electronic money, and smartwatches), household and small industrial applications (for example, power tools, golf carts, and household, caregiving, and industrial robots), large industrial applications (for example, forklifts, elevators, and port cranes), transportation systems (for example, hybrid vehicles, electric vehicles, buses, trains, electric assist bicycles, and electric motorcycles), power grid applications (for example, various power generation systems, road conditioners, smart grids, and general household energy storage systems), medical applications (medical equipment such as earphones and hearing aids), pharmaceutical applications (medication management systems, etc.), as well as IoT applications and space and deep-sea applications (for example, space probes and submersible research vessels).

Claims

1. The material comprises a polymer resin, a porous insulator, a metal salt, and a medium. The metal salt comprises at least one metal salt selected from alkali metal salts, alkaline earth metal salts, and zinc salts. The mass ratio B / A of the polymer resin to the mass A of the porous insulator satisfies 10% ≤ B / A ≤ 50%. An electrolyte in which the volume ratio X / Y of the volume of the metal salt and the medium to the pore volume Y of the porous insulator satisfies the relationship 0% < X / Y < 185%.

2. The electrolyte according to claim 1, wherein the support sheet comprising the porous insulator and the polymer resin is impregnated with an electrolyte containing the metal salt and the medium.

3. The electrolyte according to claim 1 or 2, wherein the mass ratio B / A satisfies 10% ≤ B / A ≤ 30%.

4. The electrolyte according to claim 1 or 2, wherein the volume ratio X / Y satisfies 20% ≤ X / Y ≤ 150%.

5. The electrolyte according to claim 1 or 2, wherein the volume ratio X / Y satisfies 50% ≤ X / Y ≤ 150%.

6. The electrolyte according to claim 1 or 2, wherein the mass ratio of the medium to the metal salt (medium / metal salt) is 0.1 or more and 10 or less.

7. The electrolyte according to claim 1 or 2, wherein the porous insulator is at least one selected from the group consisting of metal-organic frameworks (MOFs), zeolites, and mesoporous silica.

8. A secondary battery comprising the electrolyte according to claim 1 or 2, a positive electrode portion, and a negative electrode portion containing a negative electrode active material.

9. The average charging potential of the negative electrode active material is 1.0V vs Li ＋ The secondary battery according to claim 8, wherein the value is less than or equal to / Li.

10. The secondary battery according to claim 8, wherein the negative electrode active material comprises at least one of C, Si, and Sn.

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