JP2019057425A - Gel electrolyte, hard gel electrolyte, and electrochemical device - Google Patents

Abstract

To provide a gel electrolyte capable of improving efficiency in manufacture of an electrochemical device and realizing an excellent device performance in the obtained electrochemical device.SOLUTION: A gel electrolyte is a gel body consisting of at least a matrix material and an electrolyte and contains a cross-linkable reactive group and is hardened by performing a crosslinking reaction of the reactive group, thereby being used as an electrolyte that an electrochemical device includes. The electrolyte consists of at least an ionic material and an electrolyte solvent. A mass of the reactive group contained in the gel body ranges from 0.03 mass% or more to 6.5 mass% or less with respect to a mass of the electrolyte solvent and in a state where the reactive group is non-reactive, a shear elastic modulus of the gel body is 1 MPa or more.SELECTED DRAWING: None

Description

  The present invention relates to a gel-like body containing a crosslinkable reactive group, a gel electrolyte that can be used as an electrolyte provided in an electrochemical device by crosslinking and curing the reactive group, and the gel electrolyte. The present invention relates to a cured hard gel electrolyte and an electrochemical device including the hard gel electrolyte.

  As an electrochemical device using an electrochemical reaction, for example, various batteries, a part of a solar battery, a capacitor (capacitor), and the like are known. Conventionally, liquids (electrolytic solutions) have been used as electrolytes used in these electrochemical devices. However, if the electrolyte is a common electrolyte, the possibility of electrolyte leakage from the electrochemical device cannot be denied. Therefore, in recent years, for example, a configuration using a gel electrolyte obtained by gelling an electrolytic solution has been proposed, such as an electrochemical cell disclosed in Patent Document 1 and a manufacturing method thereof.

Special table 2011-519116 gazette

  Here, in the structure using a gel electrolyte as the electrolyte of the electrochemical device, a step of injecting an electrolytic solution (electrolytic solution injection step) is required. Moreover, in order to gelatinize electrolyte solution, a prepolymer is generally used. The prepolymer is dissolved in advance in the electrolytic solution. Such an electrolytic solution (prepolymer electrolytic solution) has a higher viscosity than a normal electrolytic solution.

  Therefore, in the electrolytic solution pouring step, it is necessary to inject a high-viscosity prepolymer electrolytic solution into the electrochemical device, so that the time required for the electrolytic solution pouring step may be prolonged. Therefore, there is a possibility that the manufacturing process of the electrochemical device cannot be made sufficiently efficient.

  For example, when the electrochemical device is large, the amount of the prepolymer electrolyte solution injected in the electrolyte solution injection step becomes large. Therefore, there is a possibility that insufficient infusion of the prepolymer electrolyte is likely to occur. When insufficient injection of the prepolymer electrolyte solution occurs, there is a possibility that sufficient device performance cannot be realized in an electrochemical device.

  The present invention has been made to solve such problems, and it is possible to improve the efficiency of the production of electrochemical devices and to realize good device performance in the obtained electrochemical devices. An object of the present invention is to provide a gel electrolyte that can be used.

  In order to solve the above-mentioned problems, the gel electrolyte according to the present invention is a gel-like body composed of at least a matrix material and an electrolytic solution, and contains a crosslinkable reactive group, and causes the reactive group to undergo a crosslinking reaction. The electrolyte solution is used as an electrolyte provided in an electrochemical device by being cured, and the electrolyte solution is composed of at least an ionic substance and an electrolyte solution solvent, and the mass of the reactive group contained in the gel is determined by the electrolyte solution. The range is from 0.03 mass% to 6.5 mass% with respect to the mass of the solvent, and the shear elastic modulus of the gel-like body in the unreacted state of the reactive group is 1 MPa or more.

  According to the above configuration, the uncured gel electrolyte contains an appropriate amount of reactive groups. Therefore, even when the gel electrolyte (hard gel electrolyte) in which the crosslinking reaction of the reactive groups has sufficiently progressed, the hard gel electrolyte can hold a sufficient amount of the electrolytic solution. It is also possible to leak a part of the electrolyte from the matrix material as the crosslinking reaction proceeds. Therefore, if an electrochemical device is produced using a gel electrolyte that is not sufficiently cured (uncured) and then the crosslinking reaction proceeds, the contact surface of the electrode provided in the electrochemical device In addition, the leaked electrolyte can be satisfactorily contacted. This makes it possible to realize a favorable electrochemical reaction in the electrochemical device.

  Moreover, since the shear modulus of the gel electrolyte is 1 MPa or more even in an uncured state, the gel electrolyte has a good strength. Therefore, good handling properties can be realized in the gel electrolyte, so that inefficiency in the production of the electrochemical device can be suppressed. In addition, as described above, the cross-linking reaction may be advanced after the electrochemical device is produced using the uncured gel electrolyte, so that a liquid injection step is not necessary in the production process of the electrochemical device. Therefore, it is possible to avoid the possibility of insufficient liquid injection or the risk of performance degradation due to insufficient liquid injection.

  As a result, it is possible to increase the efficiency of manufacturing the electrochemical device, and it is possible to realize good device performance in the obtained electrochemical device.

  In the gel electrolyte having the above-described configuration, the gel-like body may further include a post-curing agent having the reactive group in addition to the matrix material and the electrolytic solution.

  Moreover, in the gel electrolyte of the said structure, the structure which is the range of 20 mass% or more and 80 mass% or less with respect to the total mass of the said gel-like body may be sufficient.

  Moreover, in the gel electrolyte of the said structure, the structure which is the range of 1.0 mass% or more and 10 mass% or less with respect to the total mass of the said gel-like body may be sufficient.

  In the gel electrolyte having the above-described configuration, the gel-like body contains a diluting solvent that is a component different from the electrolyte solvent and is removed before the crosslinking reaction of the reactive group. The structure prescribed | regulated with respect to the total mass of the said gel-like body except the said dilution solvent may be sufficient as the mass range or the mass range of the said matrix material.

  In the gel electrolyte having the above-described configuration, the gel-like body may have a sheet shape.

  Moreover, in the gel electrolyte of the said structure, the structure whose thickness of the said gel-like body is 5 micrometers or more and 100 micrometers or less may be sufficient.

  The hard gel electrolyte according to the present disclosure has a configuration in which the reactive group in the gel electrolyte having the above configuration is subjected to a crosslinking reaction to increase its hardness.

  The hard gel electrolyte having the above configuration may have a configuration satisfying at least one of an ionic conductivity of 0.8 mS / cm or more and a shear modulus of 6 MPa or more.

  In addition, the electrochemical device according to the present disclosure may have a configuration including the hard gel electrolyte having the above configuration.

  In the present invention, it is possible to provide a gel electrolyte capable of improving the efficiency of manufacturing an electrochemical device and realizing good device performance in the obtained electrochemical device by the above configuration. There is an effect that it is possible.

It is a typical sectional view showing an example of composition of a lithium ion battery which is an example of an electrochemical device concerning an embodiment of this indication.

  The gel electrolyte according to the present disclosure is a gel-like body composed of at least a matrix material and an electrolytic solution, and includes a crosslinkable reactive group, and is cured by crosslinking the reactive group. It is used as an electrolyte provided in an electrochemical device. The electrolytic solution is composed of at least an ionic substance and an electrolytic solution solvent. In the gel electrolyte according to the present disclosure, the mass of the reactive group contained in the gel electrolyte (gel-like body) is equal to the mass of the electrolytic solution solvent. On the other hand, the gel electrolyte (gel-like body) in the range of 0.03% by mass to 6.5% by mass and in which the reactive group is unreacted has a shear modulus of 1 MPa or more. Yes.

  Hereinafter, a typical configuration example of the gel electrolyte according to the present disclosure will be specifically described. In addition, since the gel electrolyte which concerns on this indication contains the unreacted reactive group as above-mentioned, the hardening degree of gel electrolyte rises because the crosslinking reaction of this reactive group advances. In the following description, a gel electrolyte whose degree of cure has increased due to the progress of the crosslinking reaction is referred to as a “hard gel electrolyte”. Further, when simply referred to as “gel electrolyte”, it means a gel electrolyte before the degree of cure is increased.

[Composition of gel electrolyte (gel-like body)]
As described above, the gel electrolyte according to the present disclosure is a gel-like body including a matrix material and an electrolytic solution as main components, and the gel-like body includes an unreacted reactive group. The reactive group may be included in the matrix material or may be included in the electrolytic solution, or both of the matrix material and the electrolytic solution may include a reactive group, or the matrix material and the electrolytic solution. Components other than the liquid may have a reactive group. As will be described later, the gel-like body (gel electrolyte) may contain components other than the matrix material and the electrolytic solution. A typical other component includes a post-curing agent having a reactive group.

  The matrix material constituting the gel-like body is not particularly limited as long as the gel-like body can be formed in a state containing the electrolytic solution. The matrix material may be a physical gel that forms a three-dimensional structure by noncovalent bonds such as hydrogen bonds, or may be a chemical gel that forms a three-dimensional structure by covalent bonds. In the present disclosure, since the gel-like body only needs to have a reactive group capable of crosslinking reaction, the matrix material may have an unreacted reactive group.

  That is, in the present disclosure, for example, a matrix material is a compound that forms a physical gel (for convenience, a physical gel compound), and a gel-like body (non-covalently bonded by adding an electrolytic solution to the matrix material) A configuration in which a gel electrolyte) is formed and the gel-like body has an unreacted reactive group can be given. Alternatively, in the present disclosure, the matrix material is a compound that forms a chemical gel (referred to as a chemical gel compound for the sake of convenience). A gel-like body (gel electrolyte) is formed, and the semi-cured gel-like body may have a structure in which unreacted reactive groups remain.

  At this time, the mass ratio of the reactive groups that the gel-like body has (or remains) may be in the range of 0.03% by mass to 6.5% by mass with respect to the mass of the electrolyte solvent as described above. (First condition of gel electrolyte described later). As described above, the reactive group may be included in at least one of the matrix material and the electrolytic solution, or may be included in other components. Therefore, the mass ratio of the reactive group can be calculated using the ratio of the molecular weight of the reactive group to the molecular weight of one molecule of the component having the reactive group (molecular weight ratio), as exemplified in the examples described later.

  Here, it can be said that the gel electrolyte having an unreacted reactive group is in a state where curing has not sufficiently progressed, but this state is referred to as an “uncured state” for convenience. In addition, if the hardness of the gel electrolyte in the uncured state is increased due to the progress of the crosslinking reaction of the reactive groups, the state is referred to as “cured state” for convenience. The above-mentioned “semi-cured state” means a state where a part of all reactive groups of the compound is reacted when the matrix material is a chemical gel compound.

  Therefore, when most of all reactive groups of the chemical gel compound are unreacted, the chemical gel compound does not form a gel. In addition, a state in which a part of the reactive groups of the chemical gel compound is cross-linked is a “semi-cured state”, and the chemical gel compound is gelled. In this semi-cured chemical gel compound, the reactive group remains within the range of 0.03 to 6.5% by mass with respect to the mass of the electrolyte solvent, so the gel electrolyte according to the present disclosure (gel-like body) ). Therefore, it can be said that the semi-cured chemical gel compound (that is, the gel electrolyte) is in an “uncured state”. And if the crosslinking reaction of the reactive group which remains in a semi-hardened chemical gel compound advances and hardness increases, the said chemical gel compound will become a hard gel electrolyte of a hardened state.

  The specific configuration of the matrix material is not particularly limited. In general, the matrix material can be a polymer material. A suitable matrix material can be appropriately selected according to the use of the gel electrolyte according to the present disclosure, that is, the type of electrochemical device produced (manufactured) using the gel electrolyte according to the present disclosure. For example, in the examples described later, a lithium ion battery is illustrated as an example of an electrochemical device. In this case, a polymer material, an inorganic material, or a low molecular weight material is preferably used as the matrix material. it can.

  Examples of the polymer system include fluoride polymers such as polyvinylidene fluoride (PDVF) and vinylidene fluoride-hexafluoropropylene copolymer (PDVF-HFP); acrylic resins such as polyacrylonitrile (PAN) or methacrylic resins And the like are not particularly limited. Examples of the inorganic material include, but are not particularly limited to, silica particles, alumina particles, silica / alumina mixed particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles. Examples of the low molecular weight system include, but are not particularly limited to, fatty acid ester derivatives, cyclohexane derivatives, amino acid derivatives, cyclic peptide derivatives, alkyl hydrazide derivatives, and the like.

  Only one type of these matrix materials may be used, or two or more types may be appropriately selected and used in combination. For example, a plurality of polymer matrix materials may be used in combination, or one or more polymer matrix materials and inorganic matrix materials may be used in combination. Alternatively, one or more of a polymer system, an inorganic system, and a low molecular system may be selected and used in combination.

  As described above, the gel-like body may contain a post-curing agent having a reactive group. This post-curing agent can be regarded as a component different from the matrix material when the reactive group is unreacted. However, if the crosslinking reaction by the reactive group proceeds sufficiently, it constitutes a part of the matrix material. Become. Therefore, the post-curing agent can be handled as a part of the matrix material depending on the composition of the gel-like body.

  The specific configuration of the post-curing agent is not particularly limited, and a suitable reactive compound can be selected according to the composition of the gel electrolyte according to the present disclosure or the type of use (electrochemical device). For example, in the examples described later, a lithium ion battery is illustrated as an example of an electrochemical device, and the polymer system or inorganic system described above is illustrated as a matrix material. In this case, as a post-curing agent, And acrylate-based or oxetane-based reactive compounds.

  Specific examples of the acrylate compound include tetrafunctional polyether acrylate, bifunctional polyether acrylate, other AO addition acrylate, and polyethylene glycol diacrylate, but are not particularly limited. Further, examples of the oxetane compound include methyl methacrylate-oxetanyl methacrylate copolymer, but are not particularly limited. These post-curing agents may be used alone or in combination of two or more.

  When the matrix material is, for example, a chemical gel compound having an unreacted reactive group as described above, a partially cured gel-like body (gel electrolyte) is obtained by cross-linking some reactive groups first. ) May be used in the same or different type of post-curing agent. In this case, the curing agent used in advance for realizing the semi-cured state is referred to as “pre-curing agent” in comparison with the post-curing agent.

  The reactive group contained in the gel electrolyte increases the degree of cure of the gel electrolyte by crosslinking. The specific type of the reactive group is not particularly limited, and a suitable reactive group can be selected according to the composition of the gel electrolyte or the type of use (electrochemical device). For example, in the examples described later, a lithium ion battery is illustrated as an example of an electrochemical device, and the polymer system or inorganic system described above is illustrated as a matrix material. In this case, reactive groups as exemplified below can be preferably used.

  Specific reactive groups include (meth) acrylic groups (acrylic and methacrylic groups), double bond functional groups such as allyl groups; oxirane functional groups such as epoxy groups, oxetane groups; thiol groups; amino groups And combinations of functional groups of condensation reaction systems such as carboxy groups (amide bonds), hydroxy groups and carboxy groups (ester bonds); isocyanates such as isocyanate groups and hydroxy groups (urethane bonds), isocyanate groups and amino groups (urea bonds) A combination of functional groups of the system reaction; and the like. One type of these functional groups (or combinations of functional groups) may be included in the gel electrolyte (gel-like body), or two or more types may be included. When the matrix material is a chemical gel compound having an unreacted reactive group, the compound may have at least one of these functional groups (or combinations thereof).

  The electrolyte solution which comprises a gel electrolyte should just be what can exhibit an electrochemical reaction in an electrochemical device. The specific configuration of the electrolytic solution is not specifically limited in the same manner as the matrix material, the composition of gel electrolyte or the type of use (electrochemical device), the type of matrix material that constitutes the gel electrolyte together with the electrolytic solution, etc. Accordingly, an electrolytic solution having a suitable composition can be suitably used.

  As described above, the electrolytic solution in the present disclosure may be a composition composed of at least an ionic substance and an electrolytic solution solvent. In the present embodiment, the electrolytic solution solvent means a solvent constituting the electrolytic solution of the electrochemical device. Various salts can be used as the ionic substance. For example, in the examples described later, a lithium ion battery is illustrated as an example of an electrochemical device. Therefore, in this embodiment, a lithium salt can be used as the ionic substance.

Typical lithium salts include lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium hexafluorophosphate (LiPF ₆ ), lithium bis (fluorosulfonyl) imide (LiFSI), lithium perchlorate (LiClO _4). ), Lithium tetraborate (LiBF ₄ ) and the like, but are not particularly limited.

  When the electrochemical device is a lithium ion battery, examples of the electrolyte solvent include, but are not particularly limited to, carbonate solvents, ionic liquids, nitrile solvents, ether solvents, and the like.

  As a typical electrolyte solution solvent, a mixed solvent of a cyclic carbonate and a chain carbonate can be exemplified. The cyclic carbonate typically includes ethylene carbonate (EC) or propylene carbonate (PC), and the chain carbonate typically includes dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl. Although carbonate (EMC) etc. are mentioned, it is not specifically limited.

  Moreover, an ionic liquid can be mentioned as another typical electrolyte solution solvent. Specifically, for example, 1,2-ethylmethylimidazolium bis (fluorosulfonyl) imide, 1,2-ethylmethylimidazolium bis (trifluoromethanesulfonyl) imide, 1-ethyl-3-methylimidazolium bis (fluoro Sulfonyl) imide (abbreviation: EMImFSI), N-methylpropylpyrrolidinium bis (fluorosulfonyl) imide, N-methylpropylpyrrolidinium bis (trifluoromethanesulfonyl) imide, diethylmethylmethoxyethylammonium bis (trifluoromethanesulfonyl) imide , Cyethylammonium bis (fluorosulfonyl) imide, diallyldimethylammonium (trifluoromethanesulfonyl) imide, diallyldimethylammonium (fluorosulfonyl) imide, etc. Including but not limited.

  In addition to the matrix material and the electrolyte solution, the gel electrolyte before the degree of cure may contain other components (other components). Examples of the other components include the above-described post-curing agent, but other than these, for example, various additives can be exemplified. Specific examples of the additive include an initiator used for promoting a crosslinking reaction of an uncrosslinked reactive group contained in the matrix material. For example, in the examples described later, 2,2'-azobis (2,4-dimethylvaleronitrile) is used as an initiator.

[Configuration of gel electrolyte and hard gel electrolyte]
In the gel electrolyte according to the present disclosure, the mass of the reactive group contained in the gel electrolyte (gel body) may be in the range of 0.03 to 6.5% by mass with respect to the mass of the electrolyte solvent. . Moreover, in the gel electrolyte which concerns on this indication, the shear elastic modulus should just be 1 Mpa or more. That is, in the gel electrolyte according to the present disclosure, the “first condition” in which the mass ratio of unreacted reactive groups is limited to a predetermined range, and the lower limit of the shear modulus in a state in which reactive groups are unreacted are set to a predetermined value. It satisfies both the “second condition” of limiting.

  As described above, the mass ratio of the reactive group to the electrolyte solution solvent, which is the first condition of the gel electrolyte, can be calculated using the ratio of the molecular weight of the reactive group to the molecular weight of one molecule of the component having the reactive group (molecular weight ratio). Good. For example, in the examples described later, the gel electrolyte has a reactive group in the post-curing agent, but calculates the ratio of the molecular weight of the reactive group to the molecular weight of the post-curing agent, and based on this molecular weight ratio, post-curing The mass of the reactive group is calculated from the compounding amount of the agent. The mass of this reactive group should just be in the range of 0.03-6.5 mass% with respect to the mass of the electrolyte solution solvent contained in a gel electrolyte.

  When the gel electrolyte satisfies the first condition, the uncured gel electrolyte contains an appropriate amount of unreacted reactive groups. Therefore, even if the cross-linking reaction of the reactive group proceeds to become a hard gel electrolyte, the hard gel electrolyte can hold a sufficient amount of electrolyte. It is also possible to leak a part of the electrolyte from the matrix material as the crosslinking reaction proceeds. Therefore, if an electrochemical device is produced using an uncured gel electrolyte and then the crosslinking reaction proceeds, the leaked electrolyte can be satisfactorily brought into contact with the electrode contact surface of the electrochemical device. it can. This makes it possible to realize a favorable electrochemical reaction in the electrochemical device.

  The shear modulus of the gel electrolyte in an uncured state, which is the second condition of the gel electrolyte, may be measured or evaluated by a known measurement method or evaluation method. In the examples described later, for the uncured gel electrolyte obtained in each example or comparative example, a desktop precision universal testing machine (product name: Autograph AGS-X) manufactured by Shimadzu Corporation is used. After mounting the indentation jig and applying a 0.05N preload, an indentation test was carried out at a speed of 0.05 mm / min, and the shear modulus was measured from the result of the indentation test according to the following formula (1). (Unit: MPa).

Shear modulus (G) = 0.36Fg [(D−h) / h] ^3/2 / R ² (1)
Where F is the load (test force) of the indentation test, g is the gravitational acceleration, D is the thickness (film thickness) of the gel electrolyte (gel-like body), and h is the load. The thickness (film thickness) change due to, and R is the sphere radius of the spherical indenter in the indentation test. In addition, in the calculation of the shear modulus according to the above equation (1), Reference 1: DJ Taylor and AM Kragh, “Determination of the rigidity modulus of thin soft coatings by indentation measurements” Journal of Physics D: Applied Physics, United Kingdom, IOP Publishing, January 1970, Volume 3, Number 1, 29 was used as a reference.

  When the gel electrolyte satisfies the second condition, and even if it is in an uncured state, the gel electrolyte has a shear elastic modulus of 1 MPa or more, and therefore the gel electrolyte has good strength. Therefore, good handling properties can be realized in the gel electrolyte, so that inefficiency in the production of the electrochemical device can be suppressed. Furthermore, as described above, since an electrochemical device is produced using an uncured gel electrolyte and then the crosslinking reaction is allowed to proceed, a liquid injection step is not required in the production process of the electrochemical device. Therefore, it is possible to avoid the possibility of insufficient liquid injection or the risk of performance degradation due to insufficient liquid injection.

  Here, the lower limit of the mass ratio of the reactive group, which is the first condition of the gel electrolyte, may be 0.03% by mass or more with respect to the mass of the electrolyte solvent, but may be 0.04% by mass or more. Preferably, it is 0.05 mass% or more. If the mass of the reactive group is less than 0.03% by mass of the electrolyte solvent mass, the amount of the reactive group contained in the gel electrolyte will be less than the appropriate amount, and good strength can be realized in the hard gel electrolyte in the cured state. There is a risk of short circuit and the like. In addition, the amount of leakage of the electrolytic solution accompanying the progress of the crosslinking reaction is reduced, and the electrolytic solution cannot be satisfactorily brought into contact with the contact surface of the electrode of the electrochemical device, and there is a possibility that sufficient performance cannot be realized in the electrochemical device.

  Moreover, the upper limit of the mass ratio of the reactive group may be 6.5% by mass or less with respect to the mass of the electrolyte solvent, but is preferably 6.3% by mass or less, and is 6.0% by mass or less. More preferably. If the mass of the reactive group exceeds 6.5% by mass of the electrolyte solvent mass, the amount of the reactive group contained in the gel electrolyte becomes excessive, and the ionic conductivity of the hard gel electrolyte decreases, which is sufficient for an electrochemical device. There is a risk that it will not be possible to achieve the correct performance. In addition, the leakage amount of the electrolytic solution accompanying the progress of the crosslinking reaction increases, and there is a possibility that a sufficient amount of the electrolytic solution cannot be retained in the cured state (hard gel electrolyte).

  The lower limit of the uncured shear modulus, which is the second condition of the gel electrolyte, may be 1 MPa or more, preferably 2 MPa or more, and more preferably 5 MPa or more. If the shear modulus is less than 1 MPa, the strength of the uncured gel electrolyte is lowered, so that the handleability is also lowered, and the production (production) of the electrochemical device may be inefficient. The upper limit of the shear modulus is not particularly limited as long as a sufficient electrolytic solution can be retained in the hard gel electrolyte in a cured state.

  In the gel electrolyte according to the present disclosure, in addition to the first condition and the second condition described above, as a third condition, the mass of the electrolyte solvent is 20 mass relative to the total mass of the gel electrolyte (gel-like body). The third condition is in the range of not less than 80% and not more than 80% by mass, and the mass of the matrix material is in the range of not less than 1.0% by mass and not more than 10% by mass with respect to the total mass of the gel electrolyte (gel-like body) It is preferable to satisfy any one of the fourth conditions, and it is more preferable to satisfy both the third condition and the fourth condition.

  When the gel electrolyte satisfies the third condition, a more appropriate amount of the electrolytic solution is held in both the gel electrolyte and the hard gel electrolyte. Therefore, good ionic conductivity can be realized in the electrochemical device, and the performance of the electrochemical device can be further improved. However, even if the gel electrolyte does not satisfy the third condition, a sufficiently practical electrochemical device can be manufactured by satisfying both the first condition and the second condition.

  Further, when the gel electrolyte satisfies the fourth condition, both the gel electrolyte and the hard gel electrolyte contain a more appropriate amount of the matrix material. Therefore, good strength can be realized in the hard gel electrolyte, and the performance of the electrochemical device can be further improved. However, even if the gel electrolyte does not satisfy the fourth condition, a sufficiently practical electrochemical device can be manufactured by satisfying both the first condition and the second condition.

  The specific shape of the gel electrolyte is not particularly limited, and a suitable shape can be formed according to various conditions such as the type or use of the electrochemical device. In particular, in the present disclosure, since the gel electrolyte is in a gel form, it can be easily formed into a desired shape. For example, in the examples described later, a lithium ion battery is illustrated as an example of an electrochemical device, and thus the shape of the gel electrolyte can include a sheet shape.

  When the gel electrolyte is in the form of a sheet, the thickness (the film thickness of the gel electrolyte) is not particularly limited, but in general, a range of 5 μm to 100 μm can be mentioned. If the thickness of the sheet-like gel electrolyte is out of this range, sufficient battery performance (or other electrical properties) may occur depending on various conditions such as the type, size, and specific shape of the lithium ion battery (or other electrochemical device). Chemical device performance) may not be achieved.

  The hard gel electrolyte is obtained by increasing the hardness by a cross-linking reaction of the reactive group of the gel electrolyte, but the specific configuration of the hard gel electrolyte is not particularly limited. However, the hard gel electrolyte preferably satisfies either the first condition that the ionic conductivity is 0.8 mS / cm or more, or the second condition that the shear modulus is 6 MPa or more. It is more preferable to satisfy both the one condition and the second condition.

  If the ionic conductivity of the hard gel electrolyte is 0.8 mS / cm or more, preferably 1.0 mS or more, a good electrochemical reaction can be realized, so that sufficient performance can be exhibited in an electrochemical device. it can. On the other hand, if the ionic conductivity is less than 0.8 mS / cm, depending on the type of electrochemical device, there is a possibility that a good electrochemical reaction may not be realized, so that sufficient performance may not be exhibited. There is.

  Moreover, if the shear elastic modulus in a hard gel electrolyte is 6 Mpa or more, since the electrolyte layer in an electrochemical device can be hold | maintained favorably, sufficient performance can be exhibited. On the other hand, if the shear modulus of the hard gel electrolyte is less than 6 MPa, depending on the type of electrochemical device, the electrolyte layer may not be satisfactorily retained, so that sufficient performance may not be exhibited. is there.

  As described above, if the hardness of the gel electrolyte in an uncured state is increased by increasing the hardness of the reactive group, a hard gel electrolyte in the cured state can be obtained. An example of the shear modulus of the electrolyte is 6 MPa. Of course, the hardness of the gel electrolyte may be measured by a known measurement method, and the cured state may be determined based on the numerical value of the hardness or the ratio of the increase in hardness. However, in the present disclosure, the uncured gel electrolyte and Since the strength of the hard gel electrolyte is evaluated by the shear elastic modulus, if the shear elastic modulus of the gel electrolyte with increased hardness is 6 MPa or more, it can be determined that the hard gel electrolyte is formed.

[Method for producing gel electrolyte]
The production method of the gel electrolyte according to the present disclosure is not particularly limited, but as a typical production method, a first method using two types of dilution solvents, a second method using one type of dilution solvent, and a dilution solvent A third method without using can be mentioned. This diluted solvent is a component different from the electrolyte solution solvent, and is a component that is removed before the reactive group contained in the gel-like body (gel electrolyte) undergoes a crosslinking reaction. Therefore, the gel electrolyte according to the present disclosure may contain a diluent solvent as a component other than the matrix material and the electrolytic solution.

  The third and fourth conditions in the uncured gel electrolyte described above, that is, the mass range of the electrolyte solvent in the gel electrolyte and the mass range of the matrix material in the gel electrolyte are the total mass of the gel electrolyte excluding the dilution solvent. It is prescribed for. This is because, as described above, the diluting solvent is removed before the crosslinking reaction of the reactive groups. In other words, the hard gel electrolyte in the cured state does not substantially contain the diluting solvent. It is.

  The specific type of the dilution solvent is not particularly limited, and can be appropriately selected according to various conditions such as the type of electrochemical device, the type of matrix material, and the components of the electrolytic solution. For example, in the examples described later, a lithium ion battery is illustrated as an example of an electrochemical device, and therefore, the following solvent can be suitably used as the dilution solvent.

  Specifically, examples of the diluent solvent that can be contained in the gel electrolyte include ketone solvents such as acetone, methyl ethyl ketone (MEK), and cyclohexanone; ether solvents such as 1,2-dimethoxyethane (DME); acetonitrile (ACN ) Nitrile solvents such as N-methylpyrrolidone (NMP), etc .; lactone solvents such as γ-butyrolactone (GBL); ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), And carbonate solvents such as diethyl carbonate (DEC) and ethyl methyl carbonate (EMC). One type of these solvents may be used as a dilution solvent in the present disclosure, or two or more types may be appropriately selected and used. Moreover, when using these 2 or more types of solvents, each solvent may be used for the purpose of a different dilution, and may be used as a mixed solvent which mixed 2 or more types of solvents.

  The first method using two types of dilution solvents among the representative manufacturing methods of the gel electrolyte according to the present disclosure will be described.

  In the first method, first, a matrix material and a first dilution solvent are mixed to form a gel-like body (non-electrolyte gel-like body) that does not contain an electrolytic solution (non-electrolyte gel-like body forming step). The method of mixing the matrix material and the first dilution solvent is not particularly limited, but typically, a method of dissolving the matrix material in the first dilution solvent by heating the matrix material and the first dilution solvent is mentioned. It is done. After dissolution, for example, a non-electrolyte gel can be obtained by cooling to room temperature. In addition, this 1st dilution solvent can be called the dilution solvent for gels used in order to form a nonelectrolyte gel-like body.

  Next, in the first method, an electrolyte component (an ionic substance such as a lithium salt), an electrolyte solution solvent and other components (post-curing agent, initiator, etc.) are dissolved in a second dilution solvent, Prepare diluted solution. For convenience of explanation, this diluted solution is referred to as a replacement solution (replacement solution preparation step). The method for preparing the replacement solution is not particularly limited, and a known mixer or the like may be used. Then, this replacement solution is added to the non-electrolyte gel (substitution solution addition step). The method for adding the replacement solution is not particularly limited, and examples thereof include application or accumulation of the replacement solution on the non-electrolyte gel. Since the added replacement solution is absorbed by the non-electrolyte gel, a diluted solvent-containing gel is obtained.

  In the first method, the diluted solvent is then removed from the diluted solvent-containing gel-like body (diluted solvent removal step). The method for removing the diluted solvent is not particularly limited. For example, the diluted solvent may be distilled off under reduced pressure or high temperature. In this step, both the gel dilution solvent and the substitution dilution solvent are removed. However, if attention is paid to the first nonelectrolyte gel-like body, the gel dilution solvent contained in the nonelectrolyte gel-like body is electrolyzed. It will be replaced with liquid. The gel electrolyte according to the present disclosure may be a diluted solvent-containing gel-like body or a gel-like body from which the diluent solvent has been removed. That is, the removal of the diluted solvent may be performed immediately before manufacturing (manufacturing) the electrochemical device, or the diluted solvent may be removed in advance.

  Next, a second method using one type of diluent solvent among the representative methods for producing a gel electrolyte according to the present disclosure will be described.

  In the second method, as in the first method, a matrix material and a diluting solvent are mixed to prepare a diluted solution of the matrix material. For convenience of explanation, the diluted solution of the matrix material is referred to as “liquid A” (liquid A preparation step). Next, an electrolyte component (ionic substance such as a lithium salt), an electrolyte solution solvent and other components (post-curing agent, initiator, etc.) are dissolved in the same type of diluent solvent as the solution A, and a diluted solution such as an electrolyte solution is obtained. To prepare. For convenience of explanation, this diluted solution such as an electrolytic solution is referred to as “B solution” (B solution preparation step).

  Next, in the second method, the prepared liquid A and liquid B are mixed, and the resulting liquid mixture is molded into a predetermined shape (mixed molding step). The method for forming the mixed liquid is not particularly limited, and a forming die or a support according to the shape of the gel electrolyte to be obtained may be used. For example, in the examples described later, a lithium ion battery is illustrated as an example of an electrochemical device. Therefore, the liquid mixture is applied to the surface of the positive electrode using the positive electrode of the lithium ion battery as a support. Thereby, a diluted solvent containing gel-like object is formed. Thereafter, as in the first method, the diluted solvent is removed from the diluted solvent-containing gel-like body (diluted solvent removal step).

  Next, among the representative methods for producing a gel electrolyte according to the present disclosure, a second method that does not use a diluting solvent will be described. In the third method, instead of using a diluent solvent that dissolves the matrix material or the electrolyte, an electrolyte solvent is used.

  In the third method, an electrolyte solution solution of the matrix material is prepared by mixing the matrix material and the electrolyte solution solvent. For convenience of explanation, this matrix material solution is referred to as “liquid A” as in the second method (liquid A preparation step). Next, an electrolyte component (an ionic substance such as a lithium salt) and other components (post-curing agent, initiator, etc.) are dissolved in the same or different electrolyte solution solvent as the solution A, and an electrolyte solution solvent such as an electrolyte solution Prepare the solution. For convenience of explanation, the solution such as the electrolytic solution is referred to as “solution B” as in the second method (solution B preparation step). And the prepared A liquid and B liquid are mixed and the obtained liquid mixture is shape | molded by the predetermined shape (mixing shaping | molding process). Thereby, the gel-like body containing electrolyte solution etc., ie, gel electrolyte, is obtained.

  Since each of the first method, the second method, and the third method has unique advantages in production, it cannot be determined that any of the methods is particularly preferable. For example, in the first method, as described above, a replacement solution is prepared using a diluting solvent, and the liquid component of the non-electrolyte gel is replaced with the electrolytic solution using the replacement solution. Therefore, various variations of the obtained gel electrolyte can be easily produced by appropriately changing the composition of the replacement solution.

  In the second method, when a lithium ion battery is produced, a mixed liquid can be applied to the positive electrode or the negative electrode using the positive electrode or the negative electrode as a support. Therefore, an increase in the manufacturing process of the lithium ion battery can be avoided as compared with the first method, so that the manufacturing method of the lithium ion battery can be simplified. Furthermore, in the third method, an electrolyte solution solvent is used without using a diluting solvent. Thereby, since gel electrolyte is obtained only by shape | molding a liquid mixture in a predetermined shape, the process of removing a dilution solvent becomes unnecessary compared with a 1st method or a 2nd method. Therefore, the manufacturing method of the electrochemical device can be simplified.

[Electrochemical devices]
Next, a representative example of the electrochemical device according to the present disclosure manufactured using the gel electrolyte having the above-described configuration will be specifically described. The electrochemical device according to the present disclosure is not particularly limited as long as it uses an electrochemical reaction (that can convert chemical energy and electrical energy), but a representative configuration includes a pair of electrodes and And an electrolyte positioned between them.

  Although the specific structure of a pair of electrode with which an electrochemical device is provided is not specifically limited, Typically, a pair of electrode is each comprised as a positive electrode and a negative electrode. Specific configurations of the positive electrode and the negative electrode are not particularly limited. In order to increase the contact area with the electrolyte contained in the electrolyte, for example, the contact surface (surface facing the electrolyte) is porous. Is preferred. Such a porous contact surface may be included only in the positive electrode, only in the negative electrode, or both in the positive electrode and the negative electrode. Note that the more specific configuration of the pair of electrodes (positive electrode, negative electrode) is not particularly limited, and various materials, shapes, dimensions, and the like are preferably used depending on the type or application of the electrochemical device. it can.

  The method for forming the porous contact surface is not particularly limited, but a typical example is a method in which the electrode material (active material) powder (or particles) is formed in layers on the surface of the electrode substrate. As a method of forming such a powder material in layers, the electrode material (active material) powder is mixed with an organic vehicle (solvent and / or binder resin, etc.) to form a paste, and this is applied to the surface of the electrode substrate. And a method of drying, curing, firing, or the like.

  Although the electrolyte included in the electrochemical device is interposed between the pair of electrodes, in the present disclosure, as described above, the electrolyte is a cured state in which the degree of curing of the uncured gel electrolyte is increased. Any hard gel electrolyte may be used.

  Further, as described above, a typical configuration of the electrochemical device according to the present disclosure is a configuration including a pair of electrodes and a hard gel electrolyte, but the configuration of the electrochemical device in the present disclosure is not limited to this. A component or member other than the pair of electrodes and the gel electrolyte or the hard gel electrolyte may be provided. The specific configuration of such other components or other members is not particularly limited, and various components or components depending on the specific type of electrochemical device can be used.

  Specific examples of the electrochemical device according to the present disclosure include a lithium ion battery, a dye-sensitized solar cell, an electric double layer capacitor, and a gel actuator. A specific configuration of a lithium ion battery, which is a representative example of the electrochemical device in the present disclosure, will be specifically described with reference to FIG.

  As shown in FIG. 1, a lithium ion battery 10 that is a type of electrochemical device includes a positive electrode 12 and a negative electrode 13 as a pair of electrodes, and a hard gel electrolyte 14 is held between the positive electrode 12 and the negative electrode 13. have. A structure in which the positive electrode 12, the hard gel electrolyte 14 and the negative electrode 13 are laminated (a structure in which the hard gel electrolyte 14 is held on the positive electrode 12 and the negative electrode 13) is referred to as a laminated structure 11 for convenience. The lithium ion battery 10 has a configuration in which the laminated structure 11 is sealed with a sealing material 15.

  As shown in FIG. 1, the positive electrode 12 has a configuration in which a positive electrode active material layer 22 is formed on the surface of a positive electrode base material 21 (a surface facing the negative electrode 13 and a surface in contact with the hard gel electrolyte 14). ing. Similarly, the negative electrode 13 has a configuration in which a negative electrode active material layer 32 is formed on the surface of the negative electrode substrate 31 (the surface facing the positive electrode 12 and in contact with the hard gel electrolyte 14).

  The positive electrode base material 21 and the negative electrode base material 31 function as a current collector that collects electrons generated by the electrochemical reaction of the positive electrode active material layer 22 and the negative electrode active material layer 32. The specific structure of the positive electrode base material 21 and the negative electrode base material 31 is not specifically limited, What is necessary is just to use a well-known metal plate or metal foil. In examples described later, an aluminum foil is used as the positive electrode base material 21. As the negative electrode base material 31, a copper foil is typically used.

  A typical example of the positive electrode active material used for the positive electrode active material layer 22 is a lithium salt of a transition metal oxide, but is not particularly limited. In examples described later, Li—Ni—Co—Mn oxide (NCM), which is a ternary lithium salt, is used as the positive electrode active material. As the negative electrode active material used for the negative electrode active material layer 32, a lithium metal foil or a carbon material is typically used. In the examples described later, lithium metal foil is used as the negative electrode active material. Further, the positive electrode active material layer 22 may be composed of only the positive electrode active material, and the negative electrode active material layer 32 may be composed of only the negative electrode active material, but may be configured as a layer containing other components. .

  For example, when the positive electrode active material layer 22 and the negative electrode active material layer 32 are formed by coating with a coating solution containing an active material, a known binder resin such as polyvinylidene fluoride (PVDF), carbon black, and the like The known conductive assistant may be included. Moreover, the coating liquid should just contain the solvent (dispersion medium) other than an active material, binder resin, and a conductive support agent. Further, from the viewpoint of improving the frequency of contact with the positive electrode active material layer 22 or the negative electrode active material layer 32, the coating solution has a degree of cure that is the same as that of the gel electrolyte before increasing the degree of cure or the hard gel electrolyte 14. May contain a gel electrolyte (hard gel electrolyte component).

  The positive electrode active material layer 22 constitutes a facing surface facing the negative electrode 13 in the positive electrode 12 and a contact surface with respect to the hard gel electrolyte 14. Similarly, the negative electrode active material layer 32 constitutes a facing surface facing the positive electrode 12 in the negative electrode 13 and also constitutes a contact surface with respect to the hard gel electrolyte 14. Therefore, as described above, it is preferable that at least one of the positive electrode active material layer 22 and the negative electrode active material layer 32 is formed in a porous shape.

  A method for forming the active material layers 22 and 32 in a porous shape is not particularly limited, and various known methods can be used. Typically, as described above, a method of applying and drying a paste containing an active material can be given. Further, either one of the active material layers 22 and 32 may not be porous. In the examples described later, the positive electrode active material layer 22 is formed in a porous shape, but the negative electrode active material layer 32 is formed only from a lithium foil.

  In addition, since lithium foil serves as a collector (negative electrode base material 31) with a negative electrode active material, in the Example mentioned later, the negative electrode 13 is comprised only with lithium foil. Therefore, at least the positive electrode 12 and the negative electrode 13 do not need to be composed of the active material layers 22 and 32 and the base materials 21 and 31 that support them, as illustrated in FIG.

  As described above, the hard gel electrolyte 14 is formed by reacting a reactive group contained in an uncured gel electrolyte and advancing a crosslinking reaction to increase the degree of cure of the gel electrolyte.

  The sealing material 15 will not be specifically limited if it can seal the laminated structure 11 comprised by the positive electrode 12, the negative electrode 13, and the hard gel electrolyte 14. FIG. If the electrochemical device is the lithium ion battery 10, the sealing material 15 typically includes a known laminated film, a known metal can, or the like. Typical examples of the laminated film include, but are not particularly limited to, a laminate of a resin film such as polypropylene (PP) on a metal foil such as an aluminum foil or a stainless steel foil. Further, when the electrochemical device is a dye-sensitized solar cell, examples of the sealing material 15 include known sealing agents such as thermoplastic ionomer resins.

  Note that the lithium ion battery 10 shown in FIG. 1 does not include a separator. This is because the hard gel electrolyte 14 held by the positive electrode 12 and the negative electrode 13 can function in the same manner as the separator. In addition, the lithium ion battery 10 may include a separate separator, or may include a member other than the positive electrode 12, the negative electrode 13, and the hard gel electrolyte 14.

  As described above, according to the present disclosure, the uncured gel electrolyte contains an appropriate amount of reactive groups. Therefore, even when the gel electrolyte (hard gel electrolyte) in which the crosslinking reaction of the reactive groups has sufficiently progressed, the hard gel electrolyte can hold a sufficient amount of the electrolytic solution. It is also possible to leak a part of the electrolyte from the matrix material as the crosslinking reaction proceeds. Therefore, if an electrochemical device is produced using a gel electrolyte that is not sufficiently cured (uncured) and then the crosslinking reaction proceeds, the contact surface of the electrode provided in the electrochemical device In addition, the leaked electrolyte can be satisfactorily contacted. This makes it possible to realize a favorable electrochemical reaction in the electrochemical device.

  Moreover, since the shear modulus of the gel electrolyte is 1 MPa or more even in an uncured state, the gel electrolyte has a good strength. Therefore, good handling properties can be realized in the gel electrolyte, so that inefficiency in the production of the electrochemical device can be suppressed. In addition, as described above, the cross-linking reaction may be advanced after the electrochemical device is produced using the uncured gel electrolyte, so that a liquid injection step is not necessary in the production process of the electrochemical device. Therefore, it is possible to avoid the possibility of insufficient liquid injection or the risk of performance degradation due to insufficient liquid injection.

  As a result, according to the present disclosure, it is possible to improve the efficiency of manufacturing an electrochemical device, and it is possible to realize good device performance in the obtained electrochemical device.

  The present disclosure will be described more specifically based on examples and comparative examples, but the present invention is not limited thereto. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention. In addition, measurement / evaluation of various synthesis reactions and physical properties in the following examples were performed as follows.

(Measurement of shear modulus of gel electrolyte)
The shear elastic modulus of the gel electrolyte obtained in each Example or each Comparative Example was measured using a tabletop precision universal testing machine (product name: Autograph AGS-X) manufactured by Shimadzu Corporation and equipped with a 5 mmφ indentation jig. Then, after applying a 0.05 N preload, an indentation test was carried out at a speed of 0.05 mm / min. From the results of the indentation test, the shear elasticity was calculated by the following formula (1) with reference to the above-mentioned reference 1. The rate was measured (unit: MPa).

Shear modulus (G) = 0.36Fg [(D−h) / h] ^3/2 / R ² (1)
(F: Indentation test load (test force), g: Gravitational acceleration, D: Gel electrolyte (gel-like body) thickness (film thickness), h: Thickness (film thickness) change due to load, R: Indentation test Sphere radius of spherical indenter)
(Measurement of ionic conductivity of gel electrolyte)
About the gel electrolyte obtained by each Example or each comparative example, the thickness (film thickness) was measured. Further, the gel electrolyte sandwiched between stainless steel foils was allowed to stand for 12 hours in a thermostatic bath at 80 ° C. to allow the crosslinking reaction to proceed to room temperature, and the gel electrolyte was used as a hard gel electrolyte. Using this as a sample for ionic conductivity measurement, this sample was subjected to electrochemical under conditions of a frequency of 1 MHz to 0.1 Hz using an impedance analyzer (product name: SP-150) manufactured by Bio-Logic SAS. The bulk resistance value of the gel electrolyte was obtained by measuring the impedance (EIS). The ion conductivity at 30 ° C. was calculated by dividing the film thickness of the gel electrolyte by the bulk resistance value (unit: mS / cm).

(Battery performance evaluation of electrochemical devices)
About the coin cell for evaluation (electrochemical device according to the present disclosure) obtained in each example or each comparative example, using a charge / discharge test apparatus (product name: TOSCAT3100, manufactured by Toyo System Co., Ltd.) Then, charging is performed at a 0.1C time rate, and discharging is performed under conditions of a 0.1C to 1C time rate. evaluated.

  If the capacity coercivity is 90% or more, it is evaluated as “◯” (good), if the capacity coercivity is 70% or more, it is evaluated as “Δ” (normal), and if the capacity coercivity is less than 70%. It evaluated as "x" (unsuitable).

(Element stability evaluation of electrochemical devices)
In each example or each comparative example, a total of 10 coin cells for evaluation (electrochemical device according to the present disclosure) were produced, and the charge / discharge test apparatus (product name: TOSCAT3100) manufactured by Toyo System Co., Ltd. was used for these evaluation coin cells. The device stability test was performed by performing charging at a 1C time rate under conditions of 25 ° C. and discharging 100 times at a 1C time rate condition. If the occurrence of a short circuit is 1 or less among the 10 evaluation coin cells produced, it is evaluated as “◯” (good), and if the occurrence of a short circuit is less than 5, it is evaluated as “△” (normal). If the number of short circuits was 5 or more, it was evaluated as “x” (unsuitable).

Example 1
The following operations were performed in a dry air atmosphere with a dew point of -50 ° C or lower. As shown in Table 1, 1.8 parts by mass of polyvinylidene fluoride (PVDF, manufactured by Kureha Co., Ltd., product name: KF Polymer # 7200), which is a matrix material, is added to acetone (Wako Pure Chemical Industries, Ltd.) as a gel dilution solvent. Manufactured) A PVDF / acetone gel (non-electrolyte gel) was prepared by heating and dissolving at 33 ° C. at 80 ° C. and allowing to stand at room temperature.

  Moreover, as shown in Table 1, 10 parts by mass of lithium bis (fluorosulfonyl) imide (LiFSI, manufactured by Kishida Chemical Co., Ltd., lithium battery grade (LBG)), which is a lithium salt, is an ionic liquid electrolyte solvent. 49 parts by mass of 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide (EMImFSI, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Elexel IL-110), tetrafunctional polyether acrylate (post-curing agent) Daiichi Kogyo Seiyaku Co., Ltd., product name: Elexel TA-210), 1.3 parts by mass, 2,2′-azobis (2,4-dimethylvaleronitrile), an azo initiator (Wako Pure Chemical Industries, Ltd.) 0.49 part by mass of product name; V-65) manufactured by company, and 3.8 parts by mass of acetonitrile (ACN) which is a dilution solvent for substitution Combined and mixed to prepare a replacement solution.

  This substitution solution is added onto PVDF / acetone gel, and acetone (dilution solvent for gel) and acetonitrile (dilution solvent for substitution) are distilled off under normal temperature and vacuum conditions to produce the gel electrolyte according to Example 1. (Manufacturing).

  Here, in the gel electrolyte according to Example 1, the crosslinkable reactive group is an acrylate group contained in a tetrafunctional polyether acrylate (product name: Elexel TA-210) which is a post-curing agent. Since the used tetrafunctional polyether acrylate has a weight average molecular weight of 11000 and the molecular weight of four acrylate groups contained in one molecule is 220, the mass of acrylate groups contained in 1 g of the tetrafunctional polyether acrylate is 0. 0.02 g.

  As described above, in Example 1, the compounding amount of the tetrafunctional polyether acrylate that is the post-curing agent is 1.3 parts by mass. Therefore, the mass of the reactive group (acrylate group) contained in the gel electrolyte according to Example 1 is 0.025 parts by mass. Moreover, as above-mentioned, in the present Example 1, the compounding quantity of EMImFSI which is an electrolyte solution solvent is 49 mass parts. Therefore, as shown in Table 1, in the gel electrolyte according to Example 1, the mass ratio of the reactive group to the mass of the electrolyte solvent is 0.050% by mass, and is in the range of 0.03 to 6.5% by mass. Inside.

  Moreover, as shown in Table 1, in the gel electrolyte which concerns on Example 1, the mass ratio of the electrolyte solution solvent with respect to the total mass is 78 mass%, and it has entered into the range of 20-80 mass%, and the total mass. The mass ratio of the matrix material to 2.9 is 2.9% by mass and falls within the range of 1.0 to 10% by mass.

100 g of LiNi _1/3 Mn _1/3 Co _1/3 O ₂ which is a positive electrode active material, 7.8 g of acetylene black (manufactured by Denka Corporation, product name: Denka Black HS-100) as a conductive assistant, binder resin As a dispersion medium, polyvinylidene fluoride (PVDF, manufactured by Kureha Co., Ltd., weight average molecular weight Mw: about 300,000) is weighed, and 38.4 g of N-methyl-2-pyrrolidone (NMP) is weighed as a dispersion medium. It mixed with the mixer and the coating liquid of the positive electrode active material layer of 51% of solid content was prepared. The coating liquid is coated on an aluminum foil (positive electrode base material) having a thickness of 15 μm with a coating apparatus, dried at 130 ° C., and then subjected to a roll press treatment to have a positive electrode active material layer of 2.3 mg / cm ^2. Got.

  This positive electrode, the gel electrolyte according to Example 1, and the lithium foil as the negative electrode were overlapped to form a laminate. This laminated body was punched into a circular shape having a diameter of 14 mm, and sealed in a coin cell jig to prepare a sealed body. After allowing the sealing body to stand in a thermostat at 80 ° C. for 12 hours, the crosslinking reaction of the reactive group contained in the gel electrolyte is sufficiently advanced (the gel electrolyte is cured to obtain a hard gel electrolyte). , Returned to room temperature. In this way, an evaluation coin cell (lithium ion battery), which is an electrochemical device according to Example 1, was produced (manufactured).

  About the obtained gel electrolyte which concerns on Example 1, while measuring or evaluating a shear elasticity modulus, a film thickness, and ionic conductivity as above-mentioned, battery performance and element stability (short circuit) about the obtained coin cell for evaluation Evaluated. The results are shown in Table 1.

(Examples 2 and 3)
The gel electrolyte according to Example 2 or the gel electrolyte according to Example 3 in the same manner as in Example 1 except that the amount of electrolyte solvent and the amount of post-curing agent were changed as shown in Table 1. The coin cell for evaluation which is the electrochemical device which concerns on Example 2, or the electrochemical device which concerns on Example 3 was produced.

  As shown in Table 1, in the gel electrolyte according to Example 2 or the gel electrolyte according to Example 3, the mass ratio of the reactive group to the mass of the electrolyte solvent is 0.03 to 6.5 mass. %, The mass ratio of the electrolyte solvent to the total mass is in the range of 20 to 80 mass%, and the mass ratio of the matrix material to the total mass is in the range of 1.0 to 10 mass%. Inside.

  About the obtained gel electrolyte which concerns on Example 2 or 3, as above-mentioned, while measuring or evaluating a shear elasticity modulus, a film thickness, and an ionic conductivity, about the obtained coin cell for evaluation, battery performance and element stability ( Short circuit). The results are shown in Table 1.

Example 4
The following operations were performed in a dry air atmosphere with a dew point of −50 ° C. or lower, as in Examples 1 to 3. As shown in Table 2, a vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP, manufactured by Kureha Co., Ltd., product name: KF polymer # 8500, which is a matrix material, “PVDF-HFP [1] 2.9 parts by mass was dissolved by heating at 80 ° C. with respect to 29.5 parts by mass of dimethyl ether (DME, manufactured by Wako Pure Chemical Industries, Ltd.) as a diluent solvent. Thereby, A liquid which is a DME diluted solution of PVDF-HFP was prepared.

  Further, as shown in Table 2, 9.3 parts by mass of LiFSI (see Example 1) which is a lithium salt, 28 parts by mass of EMImFSI (see Example 1) which is an ionic liquid electrolyte solution solvent, and post-curing 0.90 parts by mass of tetrafunctional polyether acrylate (see Example 1) as an agent, 0.12 parts by mass of azo initiator (see Example 1) as an initiator, and 29 of DME as a diluent solvent .5 parts by mass was mixed and mixed to prepare solution B, which is a DME dilution solution such as an electrolytic solution.

  The obtained liquid A and liquid B were mixed, this mixed solution was applied to the surface of the positive electrode described above, and DME (diluting solvent) was distilled off under normal temperature and vacuum conditions, whereby the gel according to Example 4 was obtained. A laminate of the electrolyte and the positive electrode was produced (manufactured).

  As shown in Table 2, in the gel electrolyte according to Example 4, as the post-curing agent, tetrafunctional polyether acrylate is blended in the same manner as in Examples 1 to 3, and in the same manner as in Example 1. The mass ratio of reactive groups is derived. As shown in Table 2, the mass ratio of the reactive group to the mass of the electrolyte solvent is in the range of 0.03 to 6.5% by mass (0.063% by mass). Moreover, as shown in Table 2, in the gel electrolyte which concerns on Example 4, the mass ratio of the electrolyte solution solvent with respect to the total mass is in the range of 20-80 mass% (68 mass%), and is with respect to the total mass. The mass ratio of the matrix material is in the range of 1.0 to 10% by mass (7.0% by mass).

  Further, this gel electrolyte / positive electrode laminate was punched into a circular shape with a diameter of 14 mm, and a lithium foil with a diameter of 14 mm as a negative electrode was bonded to the gel electrolyte side of the obtained punched body into a bipolar cell (Tom cell). I set it. In this way, an evaluation coin cell (lithium ion battery), which is an electrochemical device according to Example 4, was produced (manufactured).

  Regarding the obtained gel electrolyte (gel electrolyte / positive electrode laminate) according to Example 4, as described above, the shear modulus, film thickness, and ionic conductivity were measured or evaluated, and the obtained coin cell for evaluation was obtained. Battery performance and device stability (short circuit) were evaluated. The results are shown in Table 2.

(Examples 5 to 13)
Whether the blending amount of the electrolyte solvent and the blending amount of the post-curing agent are changed as shown in Table 2 (Examples 5 and 6), or a bifunctional polyether acrylate (Daiichi Kogyo Seiyaku Co., Ltd., product) Name: MP-150) or the amount of the electrolyte solvent is appropriately changed as shown in Table 2 or 3 (Examples 7 to 9), or polyethylene glycol diacrylate (Daiichi Kogyo Seiyaku Co., Ltd.) as a post-curing agent. The product amount of the electrolytic solution solvent is changed as shown in Table 3 using a product manufactured by company (product name: Elexel EG2500) (Example 10), or methyl methacrylate-oxetanyl methacrylate copolymer (No. 1) as a post-curing agent The amount of the electrolyte solvent is changed as shown in Table 3 using a product name manufactured by Ichi Kogyo Seiyaku Co., Ltd., product name: Elekcel ACG-127) (Examples 11 to 13). Outside, in the same manner as in Example 4, to prepare a gel electrolyte according to Example 5-13. Moreover, the coin cell for evaluation which is an electrochemical device which concerns on Examples 5-13 was produced using these gel electrolytes.

  Here, in the gel electrolyte which concerns on Examples 7-9, the reactive group which can be bridge | crosslinked is an acrylate group contained in the bifunctional polyether acrylate (product name: MP-150) which is a postcure agent. Since the used bifunctional polyether acrylate has a weight average molecular weight of 11000 and the molecular weight of two acrylate groups contained in one molecule is 110, the mass of acrylate groups contained in 1 g of the bifunctional polyether acrylate is 0. .010 g.

  For example, in Example 7, as shown in Table 2, the compounding quantity of the bifunctional polyether acrylate which is a post-curing agent is 1.4 mass parts. Therefore, the mass of the reactive group (acrylate group) contained in the gel electrolyte according to Example 7 is 0.0138 parts by mass. Moreover, in Example 7, as shown in Table 2, the compounding quantity of EMImFSI which is an electrolyte solution solvent is 28 mass parts. Therefore, as shown in Table 2, in the gel electrolyte according to Example 7, the mass ratio of the reactive group to the mass of the electrolyte solvent is 0.050% by mass, and is in the range of 0.03 to 6.5% by mass. Inside.

  Similarly, as shown in Table 2 or Table 3, also in the gel electrolyte according to Example 8 or Example 9, the same bifunctional polyether acrylate as Example 7 was blended as a post-curing agent. Similarly, the mass ratio of the reactive groups is derived. As shown in Table 2, in Examples 8 and 9, the mass ratio of the reactive group to the mass of the electrolyte solvent is 0.44% by mass (Example 8) or 2.5% by mass (Example 9). And both are within the range of 0.03 to 6.5% by mass.

  In the gel electrolyte according to Example 10, the crosslinkable reactive group is an acrylate group contained in polyethylene glycol diacrylate (product name: Elexel EG2500) which is a post-curing agent. Since the used polyethylene glycol diacrylate has a weight average molecular weight of 2500 and the molecular weight of acrylate groups contained in one molecule is 83, the mass of acrylate groups contained in 1 g of the polyethylene glycol diacrylate is 0.033 g.

  In Example 10, as shown in Table 3, the compounding amount of polyethylene glycol diacrylate as a post-curing agent is 6.7 parts by mass. Therefore, the mass of the reactive group (acrylate group) contained in the gel electrolyte according to Example 10 is 0.221 parts by mass. Moreover, in Example 10, as shown in Table 3, the compounding quantity of EMImFSI which is an electrolyte solution solvent is 28 mass parts. Therefore, in the gel electrolyte according to Example 10, the mass ratio of the reactive group to the mass of the electrolyte solvent is 1.0 mass%, which is in the range of 0.03 to 6.5 mass%.

  Moreover, in the gel electrolyte which concerns on Examples 11-13, the reactive group which can be bridge | crosslinked is an oxetane part contained in the methylmethacrylate-oxetanyl methacrylate copolymer (product name: Elexel ACG-127) which is a postcure agent. . Since the used methyl methacrylate-oxetanyl methacrylate copolymer has a weight average molecular weight of 300,000 and the molecular weight of one oxetane part is 56, the mass of the oxetane part contained in 1 g of the methyl methacrylate-oxetanyl methacrylate copolymer. Is 0.13 g.

  For example, in Example 11, as shown in Table 3, the compounding amount of the methyl methacrylate-oxetanyl methacrylate copolymer as the post-curing agent is 0.12 parts by mass. Therefore, the mass of the reactive group (oxetane part) contained in the gel electrolyte according to Example 11 is 0.015 part by mass. Moreover, in Example 11, as shown in Table 3, the compounding quantity of EMImFSI which is an electrolyte solution solvent is 29 mass parts. Therefore, as shown in Table 2, in the gel electrolyte according to Example 11, the mass ratio of the reactive group to the mass of the electrolyte solvent is 0.050% by mass, in the range of 0.03-6.5% by mass. Inside.

  Similarly, as shown in Table 3, also in the gel electrolyte according to Example 12 or Example 13, the same methyl methacrylate-oxetanyl methacrylate copolymer as Example 11 was blended as a post-curing agent. Similarly, the mass ratio of the reactive groups is derived. As shown in Table 3, in these Examples 11 and 12, the mass ratio of the reactive group to the mass of the electrolyte solvent was 1.2 mass% (Example 12) or 5.6 mass% (Example 13), both of which fall within the range of 0.03 to 6.5% by mass.

  As shown in Table 2, in the gel electrolytes according to Examples 5 and 6, as the post-curing agent, tetrafunctional polyether acrylate was blended in the same manner as in Examples 1-4. Similarly, the mass ratio of reactive groups is derived. As shown in Table 2, also in Examples 5 and 6, the mass ratio of the reactive group to the mass of the electrolyte solvent is in the range of 0.03 to 6.5% by mass (see Example 1). ).

  Furthermore, as shown in Table 2 or Table 3, in the gel electrolytes according to Examples 5 to 13, the mass ratio of the electrolyte solvent to the total mass is in the range of 20 to 80% by mass, The mass ratio of the matrix material to the total mass is in the range of 1.0 to 10% by mass.

  As described above, for each of the obtained gel electrolytes according to Examples 5 to 13, the shear modulus, film thickness, and ionic conductivity were measured or evaluated, and the battery performance and device stability were obtained for each of the obtained coin cells for evaluation. (Short circuit) was evaluated. The results are shown in Table 2 or Table 3.

(Examples 14 to 16)
As shown in Table 4, as a matrix material, PVDF-HFP of a different type from Examples 4 to 13 (manufactured by Kureha Co., Ltd., product name: KF polymer # 9300, in Table 4, “PVDF-HFP [2]” for convenience) (Invention 14) or silica particles (manufactured by Nippon Aerosil Co., Ltd., product name: Aerosil 200, described as “silica” in Table 4) as the matrix material (Example 15). ) Or silica / alumina mixed particles (manufactured by Nippon Aerosil Co., Ltd., product name: Aerosil COK84, expressed as “silica / alumina” in Table 4) as the matrix material (Example 16) Gel electrolytes according to Examples 14 to 16 were produced in the same manner as in Example 4 except that the amounts of the liquid solvent and the post-curing agent were changed. Moreover, the coin cell for evaluation which is an electrochemical device which concerns on Examples 14-16 was produced using these gel electrolytes.

  As shown in Table 4, in the gel electrolytes according to Examples 14 to 16, the mass ratio of the reactive group to the mass of the electrolyte solvent is within the range of 0.03 to 6.5% by mass. The mass ratio of the electrolyte solvent to the total mass is in the range of 20 to 80% by mass, and the mass ratio of the matrix material to the total mass is in the range of 1.0 to 10% by mass.

  For each of the obtained gel electrolytes according to Examples 14 to 16, as described above, the shear modulus, film thickness, and ionic conductivity were measured or evaluated, and the battery performance and device stability of each of the obtained evaluation coin cells were measured. (Short circuit) was evaluated. The results are shown in Table 4.

(Example 17)
The following operations were performed in a dry air atmosphere having a dew point of −50 ° C. or lower, as in Examples 1 to 16. As shown in Table 5, 1.0 part by mass of PVDF-HFP [2] (manufactured by Kureha Co., Ltd., product name: KF polymer # 9300) as a matrix material as a matrix material is a carbonate-based electrolyte solvent. 39.5 parts by mass of a mixture (mixed electrolyte solvent) of 55 parts by mass of dimethyl carbonate (DMC, manufactured by Kishida Chemical Co., Ltd., LBG) and 5.3 parts by mass of ethylene carbonate (EC, manufactured by Kishida Chemical Co., Ltd., LBG) And dissolved at 80 ° C. Thereby, A liquid which is a DMC diluted solution of PVDF-HFP was prepared.

Further, as shown in Table 5, 14 parts by mass of lithium hexafluorophosphate (LiPF ₆ , manufactured by Kishida Chemical Co., Ltd., LBG) which is a lithium salt, and 39.5% of the mixed electrolyte solvent of the above DMC and EC were used. 0.90 parts by mass of tetrafunctional polyether acrylate (see Example 1) as a post-curing agent and 0.30 parts by mass of azo initiator (see Example 1) as an initiator are mixed and mixed. And solution B was prepared. In addition, as shown in Table 5, in this example, no dilution solvent is used.

  The obtained liquid A and liquid B were mixed, and this mixed solution was applied to the surface of the positive electrode described above, thereby producing (manufacturing) a gel electrolyte and positive electrode laminate according to Example 17.

  As shown in Table 5, in the gel electrolyte according to Example 17, the mass ratio of the reactive group to the mass of the electrolyte solvent is in the range of 0.03 to 6.5 mass% (0.013 The mass ratio of the electrolyte solvent to the total mass is in the range of 20 to 80 mass% (79 mass%), and the mass ratio of the matrix material to the total mass is in the range of 1.0 to 10 mass%. (1.0% by mass).

  Further, this gel electrolyte / positive electrode laminate was punched into a circular shape with a diameter of 14 mm, and a lithium foil with a diameter of 14 mm as a negative electrode was bonded to the gel electrolyte side of the obtained punched body into a bipolar cell (Tom cell). I set it. In this way, an evaluation coin cell (lithium ion battery), which is an electrochemical device according to Example 17, was produced (manufactured).

  Regarding the obtained gel electrolyte (gel electrolyte / positive electrode laminate) according to Example 17, as described above, the shear modulus, film thickness, and ionic conductivity were measured or evaluated, and the obtained coin cell for evaluation was obtained. Battery performance and device stability (short circuit) were evaluated. The results are shown in Table 5.

(Examples 18 to 20)
As shown in Table 5, the carbonate electrolyte solution solvent used for preparing the liquid A was ethyl methyl carbonate (EMC, manufactured by Kishida Chemical Co., Ltd., LBG, Example 18), diethyl carbonate (DEC, manufactured by Kishida Chemical Co., Ltd.) In the case of changing to LBG, Example 19) or propylene carbonate (PC, manufactured by Kishida Chemical Co., Ltd., LBG, Example 20) and using PC, the blending amounts of PC and EC were changed (Example 20). Except for), gel electrolytes according to Examples 18 to 20 were produced in the same manner as in Example 17. Moreover, the coin cell for evaluation which is an electrochemical device which concerns on Examples 18-20 was produced using these gel electrolytes.

  As shown in Table 5, in each of the gel electrolytes according to Examples 18 to 20, the mass ratio of the reactive group to the mass of the electrolyte solvent falls within the range of 0.03 to 6.5% by mass. The mass ratio of the electrolyte solvent to the total mass is in the range of 20 to 80% by mass, and the mass ratio of the matrix material to the total mass is in the range of 1.0 to 10% by mass.

  For each of the obtained gel electrolytes according to Examples 18 to 20, the shear modulus, film thickness, and ionic conductivity were measured or evaluated as described above, and the battery performance and device stability were obtained for each of the obtained coin cells for evaluation. (Short circuit) was evaluated. The results are shown in Table 5.

(Examples 21 to 26)
As shown in Table 6, although the mass ratio of the reactive group to the electrolyte solvent in the gel electrolyte falls within the range of 0.03 to 6.5 mass%, the mass ratio of the electrolyte solvent to the total mass in the gel electrolyte is 20 Or less than 80% by mass (Example 22), or less than 0.8 mS / cm (Example 23), or the matrix material relative to the total mass in the gel electrolyte. The mass ratio is less than 1.0 mass% (Example 24), the mass ratio exceeds 10 mass% (Example 25), and the film thickness of the gel electrolyte is increased to 100 μm or more, and the blending amount of each component is changed. Examples 21 to 26 were the same as Example 4 described above (Examples 21, 23 to 26) or the same as Example 17 (Example 22, except that only one type of EC solvent was used as the electrolyte solvent), except for the above. In The gel electrolyte was fabricated that. Moreover, the coin cell for evaluation which is an electrochemical device which concerns on Examples 21-26 was produced using these gel electrolytes.

  For each of the obtained gel electrolytes according to Examples 21 to 26, as described above, the shear modulus, film thickness, and ionic conductivity were measured or evaluated, and battery performance and device stability were obtained for each of the obtained evaluation coin cells. (Short circuit) was evaluated. The results are shown in Table 6.

(Comparative Examples 1 and 2)
As shown in Table 7, while the mass ratio of the reactive group to the electrolyte solvent in the gel electrolyte is less than 0.03% by mass (Comparative Example 1) or exceeds 6.5% by mass (Comparative Example 2), A gel electrolyte according to Comparative Example 1 or a gel electrolyte according to Comparative Example 2 was prepared in the same manner as in Example 4 described above except that the blending amount of the components was changed, and the electrochemical device according to Comparative Example 1 or An evaluation coin cell, which is an electrochemical device according to Comparative Example 2, was produced.

  About the obtained gel electrolyte which concerns on the comparative example 1 or 2, as above-mentioned, while measuring or evaluating a shear elasticity modulus, a film thickness, and an ionic conductivity, about the obtained coin cell for evaluation, battery performance and element stability ( Short circuit). The results are shown in Table 7.

(Contrast of Examples and Comparative Examples)
As is clear from the comparison between Examples 1 to 26 and Comparative Examples 1 and 2, in the gel electrolyte according to the present disclosure, an electrochemical device having good performance by satisfying the first condition and the second condition ( Lithium ion battery) can be manufactured. On the other hand, it is understood that the performance of the electrochemical device cannot be sufficiently obtained particularly when the first condition is not satisfied.

  Further, as is clear from the comparison between Examples 4 to 13 and Examples 17 to 20 and Examples 21 to 26, in the gel electrolyte according to the present disclosure, in addition to the first condition and the second condition, the third condition By satisfying at least one of the condition and the fourth condition, an electrochemical device (lithium ion battery) having even better performance can be manufactured.

  Further, as is clear from the comparison of Examples 1 to 3, Examples 4 to 16, and Examples 17 to 20, in the gel electrolyte according to the present disclosure, the first method, the second method, or the third Even if it is the gel electrolyte manufactured in any of these methods, the electrochemical device (lithium ion battery) of a favorable performance can be manufactured.

  It should be noted that the present invention is not limited to the description of the above-described embodiment, and various modifications are possible within the scope shown in the scope of the claims, and are disclosed in different embodiments and a plurality of modifications. Embodiments obtained by appropriately combining the technical means are also included in the technical scope of the present invention.

  The present invention can be suitably used widely in the field of electrochemical devices using a gel electrolyte such as a lithium ion battery, a dye-sensitized solar cell, an electric double layer capacitor, or a gel actuator.

10: lithium ion battery 11: laminated structure 12: positive electrode 13: negative electrode 14: hard gel electrolyte 15: sealing material 21: positive electrode base material 22: positive electrode active material layer 31: negative electrode base material 32: negative electrode active material layer

Claims (10)

It is a gel-like body composed of at least a matrix material and an electrolytic solution, and includes a crosslinkable reactive group,
By crosslinking and curing the reactive group, it is used as an electrolyte provided in an electrochemical device,
The electrolytic solution is composed of at least an ionic substance and an electrolytic solution solvent,
The mass of the reactive group contained in the gel is in the range of 0.03% by mass to 6.5% by mass with respect to the mass of the electrolyte solvent,
The shear elastic modulus of the gel-like body in the unreacted state of the reactive group is 1 MPa or more,
Gel electrolyte. In addition to the matrix material and the electrolytic solution, the gel-like body further contains a post-curing agent having the reactive group,
The gel electrolyte according to claim 1. The mass of the electrolyte solvent is in the range of 20% by mass to 80% by mass with respect to the total mass of the gel-like body,
The gel electrolyte according to claim 1 or 2. The mass of the matrix material is in a range of 1.0% by mass to 10% by mass with respect to the total mass of the gel-like body,
The gel electrolyte according to any one of claims 1 to 3. The gel-like body contains a diluting solvent that is a component different from the electrolyte solvent and removed before the crosslinking reaction of the reactive group,
The mass range of the electrolyte solvent or the mass range of the matrix material is defined with respect to the total mass of the gel-like body excluding the dilution solvent,
The gel electrolyte according to claim 3 or 4. The gel-like body is a sheet shape,
The gel electrolyte according to any one of claims 1 to 5. The gel-like body has a thickness of 5 μm or more and 100 μm or less,
The gel electrolyte according to claim 6. The gel electrolyte according to any one of claims 1 to 7, wherein the reactive group in the gel electrolyte is subjected to a crosslinking reaction to increase its hardness,
Hard gel electrolyte. The ion conductivity is 0.8 mS / cm or more, and the shear modulus is at least one of 6 MPa or more, characterized in that,
The hard gel electrolyte according to claim 8. A hard gel electrolyte according to claim 8 or 9 is provided.
Electrochemical device.

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