Quasi-solid electrolyte composition and battery

Abstract

The present disclosure provides a quasi-solid electrolyte composition comprising: an electrolytic solution that contains an alkali metal salt and an organic solvent; and a porous material. In a quasi-solid electrolyte, the content of the alkali metal salt is 11 mol% or more based on the sum of substance amounts of the alkali metal salt and the organic solvent. The pore size of the porous material is 7-13 Å. The content of the porous material is 20-33 mass% with respect to the total amount of the quasi-solid electrolyte composition.

Description

Quasi-solid electrolyte composition and battery

[0001] The present disclosure relates to quasi-solid electrolyte compositions and batteries.

[0002] Batteries such as lithium ion batteries, which charge and discharge through the transfer of metal ions between a positive electrode and a negative electrode, have been the subject of vigorous research due to their high capacity. While solutions of lithium salts containing organic solvents or ionic liquids are known as electrolytes for lithium ion batteries and the like, research into solid electrolytes, polymer electrolytes, and the like is also underway from the perspectives of safety and processability (Patent Document 1, Non-Patent Documents 1 and 2). In addition to lithium ion batteries, research is also underway into batteries using other alkali ions, such as sodium and potassium, which are more abundant than lithium.

[0003] International Publication No. 2022 / 113487

[0004] Zhiyu Ding et al., Chemical Engineering Journal, 2022, 433, part2,133522, article DOI: 10.1016 / j.cej.2021.133522.Lei Han et al., Journal of Materials Chemistry A, 2018, 43, 2200865, article DOI: 10.1039 / C8TA08875F.

[0005] In some battery manufacturing processes, a laminate including a positive electrode, an electrolyte, and a negative electrode in this order is constrained by a restraining device under external pressure to suppress battery swelling and improve durability. The battery is then maintained in a pressurized state even after the external pressure is removed. However, in such cases, the battery has a restraining device, which poses problems in terms of weight and space saving. Therefore, it is desirable to provide a battery that exhibits excellent cycle capacity retention even when the restraining pressure is low or no restraining pressure is applied.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a quasi-solid electrolyte composition that can be used to produce a battery with excellent cycle capacity retention even in a state where no confining pressure is applied, and a battery including such a quasi-solid electrolyte composition.

[0007] To maintain a high cycle capacity retention rate even when no confining pressure is applied, it is desirable to improve the performance of the electrolyte itself. For example, it is desirable to improve the adhesion between the electrolyte and the electrodes even when no confining pressure is applied, to reduce the deterioration of charge / discharge efficiency between the positive and negative electrodes and the decrease in charge capacity (decrease in Coulombic efficiency) due to the formation of long dendrites (e.g., lithium dendrites) during battery charging, and to prevent side reactions caused by electrolyte decomposition residues during SEI formation. To achieve this, it is possible to incorporate a porous material into the electrolyte solution to quasi-solidify it. However, in this case, when tiny dendrites growing from the counter electrode reach the positive electrode, they self-discharge. However, since the amount of dendrites reaching the positive electrode gradually increases with each cycle, the retention rate decreases, which may lead to a decrease in the cycle capacity retention rate. According to the inventors' studies, it has been found that by using a quasi-solid electrolyte composition containing an electrolyte solution and a porous material, in which a predetermined amount of porous material with a relatively large pore size is incorporated, it is possible to suppress the causes of cycle capacity reduction while maintaining appropriate adhesion to the electrodes. The present disclosure has been made based on this finding.

[0008] The present disclosure includes the following exemplary embodiments. [1] A quasi-solid electrolyte composition comprising: an electrolyte solution containing an alkali metal salt and an organic solvent; and a porous material; wherein the content of the alkali metal salt is 11 mol % or more based on the total amount of the alkali metal salt and the organic solvent; the pore diameter of the porous material is 7 to 13 Å; and the content of the porous material is 20 to 33 mass % with respect to the total amount of the quasi-solid electrolyte composition. [2] The quasi-solid electrolyte composition according to [1], wherein the average particle diameter of a single particle of the porous material is 1000 nm or less. [3] The quasi-solid electrolyte composition according to [1] or [2], wherein the porous material is a zeolite. [4] The quasi-solid electrolyte composition according to [1] or [2], wherein the porous material is an FAU-X type zeolite. [5] A battery comprising the quasi-solid electrolyte composition according to any one of [1] to [4]. [6] The battery according to [5], wherein the positive electrode is a dry positive electrode. [7] The battery of [5] or [6] to which no restraining pressure is applied.

[0009] According to the present disclosure, it is possible to provide a quasi-solid electrolyte composition that can produce a battery with excellent cycle capacity retention even in a state where no confining pressure is applied, and a battery including such a quasi-solid electrolyte composition.

[0010] Fig. 1 is a graph showing the relationship between the capacity retention rate and the number of cycles for each half-cell of Example 1, Comparative Example 1, and Comparative Example 2. Fig. 2 is a graph showing the relationship between the reversible capacity and the number of cycles for each half-cell of Example 1, Comparative Example 1, and Comparative Example 2.

[0011] Hereinafter, embodiments of the present disclosure will be described. However, the following embodiments are merely examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents.

[0012] The quasi-solid electrolyte composition according to the present disclosure is a quasi-solidified electrolyte composition obtained by blending a porous material with an electrolyte solution containing an alkali metal salt to increase viscosity and form a quasi-solid. The concentration of the alkali metal salt in the electrolyte solution may be 1.0 M or more. The porous material may be a powder containing porous particles.

[0013] The quasi-solid electrolyte composition of this embodiment contains an electrolyte solution containing an alkali metal salt and an organic solvent, and a porous material. In the quasi-solid electrolyte composition, the content of the alkali metal salt is 11 mol % or more based on the total amount of the alkali metal salt and the organic solvent, the pore diameter of the porous material is 7 to 13 Å, and the content of the porous material is 20 to 33 mass % relative to the total amount of the quasi-solid electrolyte composition. The quasi-solid electrolyte composition, which contains a predetermined amount of porous material having a predetermined pore diameter, can exhibit a certain degree of flexibility, thereby ensuring sufficient contact between the electrode and the electrolyte compared to compositions that do not contain the porous material. This allows the production of batteries with excellent cycle capacity retention, even in the absence of confining pressure. Furthermore, the resulting quasi-solid electrolyte can exhibit an excellent transport number, thereby suppressing decomposition of anions on the negative electrode and maintaining a high capacity retention.

[0014] <Electrolyte Solution> The electrolyte solution is a solution containing an alkali metal salt as an electrolyte and an organic solvent. The content of the alkali metal salt in the electrolyte solution may be, for example, 15 mol% or more, 20 mol% or more, 25 mol% or more, 30 mol% or more, 35 mol% or more, or 38 mol% or more, based on the total amount of substance of the alkali metal salt and the organic solvent. The upper limit of the concentration of the alkali metal salt in the electrolyte solution is not particularly limited, but may be, for example, the saturated concentration at 25°C. The content of the alkali metal salt may be, for example, 50 mol% or less, 45 mol% or less, or 43 mol% or less, based on the total amount of substance of the alkali metal salt and the organic solvent. The content of the alkali metal salt may be adjusted within the above-mentioned range and may be, for example, 11 to 45 mol% or 30 to 43 mol%, based on the total amount of substance of the alkali metal salt and the organic solvent.

[0015] Examples of alkali metal salts include MF, MCl, MBr, MI, and MNO, where M is an alkali metal. ３ , MClO ４ , MPF ６ , MBF ４ , M ２ SO ４, M[(C ｈ F ２ｈ＋１ ) SO ３ ] (h is 0 to 3), M[(C ｈ F ２ｈ＋１ ) SO ２ ] ２ N (h is 0 to 3), M{[(C ｈ F ２ｈ＋１ ) SO ２ ]N[(C ｉ F ２ｉ＋１ ) SO ２ ]} (h and i are 0 to 3), and MBOB (BOB is bis(oxalatoborate). Among these, examples of alkali metal salts include M[(FSO ２ ) ２ N] and M[(CF ３ SO ２ ) ２ N], and M[(FSO ２ ) ２ As the electrolyte solution in the present disclosure, one type may be used alone, or multiple types of alkali metal salts may be used in combination. M[(FSO ２ ) ２ Examples of N] include lithium bis(fluorosulfonyl)imide (LiFSI).

[0016] The above M in the alkali metal salt is not particularly limited as long as it is an alkali metal, but may contain lithium, sodium, or potassium, or may contain lithium or sodium, or may contain lithium.

[0017] The solvent contained in the electrolytic solution may be an organic solvent. Examples of the organic solvent include aprotic solvents. The organic solvent may include, for example, one or more solvents selected from the group consisting of carbonate-based solvents, ether-based solvents, fluorine-based solvents, nitrile-based solvents, phosphate-based solvents, and sulfone-based solvents, and may include a carbonate-based solvent.

[0018] Examples of carbonate solvents include chain carbonates such as dimethyl carbonate (DMC), diethyl carbonate, and ethyl methyl carbonate; and cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate. The organic solvent may be a mixed solvent containing two or more carbonate solvents, such as a mixed solvent containing one or more cyclic carbonate solvents and one or more chain carbonate solvents, or a mixed solvent containing two or more cyclic carbonate solvents.

[0019] Examples of ether solvents include cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, and 1,3-dioxolane; and chain ethers such as 1,2-diethoxyethane and ethoxymethoxyethane.

[0020] Examples of fluorine-based solvents include hydrofluorocarbons such as perfluorooctane; hydrofluoroethers such as methyl nonafluorobutyl ether and ethyl nonafluorobutyl ether; hydrofluoroolefins such as 1,3,3,3-tetrafluoropropene; and 2,2,2-trifluoro-N,N-dimethylacetamide.

[0021] Examples of phosphate esters include trimethyl phosphate (TMP), triethyl phosphate (TEP), and tris(2,2,2-trifluoroethyl) phosphate (TFEP).

[0022] Examples of the nitrile solvent include acetonitrile, succinonitrile, etc. Examples of the lactone solvent include γ-butyrolactone, etc.

[0023] Other examples of organic solvents include sulfone solvents such as sulfolane and 3-methylsulfolane, solvents having a sulfonyl group such as dimethyl sulfoxide (DMSO), amide solvents such as dimethylformamide (DMF) and dimethylacetamide (DMA), organic solvents having a carbonyl group (-C(=O)-) such as acetone (referring to carbonyl compounds other than amide compounds such as esters, ketones, and aldehydes), and nitrogen-containing aromatic compounds such as pyridine (compounds containing nitrogen as a ring member of the aromatic ring, which may be either monocyclic or fused ring systems). The organic solvent may be used alone or as a mixed solvent containing two or more organic solvents.

[0024] The upper limit of the content of the organic solvent in the quasi-solid electrolyte composition may be, for example, 8 mol or less, 7 mol or less, 6 mol or less, 5 mol or less, 4.5 mol or less, or 4 mol or less, relative to 1 mol of alkali metal ions contained in the alkali metal salt. The lower limit of the content of the organic solvent in the quasi-solid electrolyte composition may be, for example, more than 1 mol, 1.1 mol or more, 1.2 mol or more, 1.3 mol or more, or 1.4 mol or more, relative to 1 mol of alkali metal ions contained in the alkali metal salt. The content of the organic solvent in the quasi-solid electrolyte composition may be adjusted within the above-mentioned range, and may be, for example, 1 to 8 mol, 1.3 to 7 mol, 1.3 to 6 mol, 1.3 to 5 mol, or 1.3 to 4 mol, relative to 1 mol of alkali metal ions contained in the alkali metal salt.

[0025] <Porous Material> The porous material contained in the quasi-solid electrolyte composition has a pore diameter of 7 to 13 Å. By using a material having a pore diameter as described above as the porous material, it is possible to ensure a path for ion conduction through the pores and inhibit the long growth of lithium dendrites during use of the battery. Note that if a porous material with no pores or a small pore diameter is used, it can inhibit the long growth of lithium dendrites, but it also inhibits ion conduction itself, and therefore is not suitable as a porous material to be used in the quasi-solid electrolyte composition according to this embodiment.

[0026] The lower limit of the pore diameter of the porous material may be, for example, 8 Å or more, 9 Å or more, 10 Å or more, 11 Å or more, or 12 Å or more. When the lower limit of the pore diameter is within the above range, ion conduction through the pores of the porous material can be facilitated. The pore diameter of the porous material may be adjusted within the above range, and may be, for example, 9 to 13 Å or 10 to 13 Å.

[0027] The pore size of the porous material in this specification means the pore size at the position where the pore volume is maximum in a pore distribution created based on the SF method of micropore evaluation from the results of water vapor adsorption / desorption isotherm measurement.

[0028] The porous material has a large specific surface area, which can further improve its affinity with the electrolyte solution, suppress phase separation with the electrolyte solution, and further improve the stability of the quasi-solid electrolyte composition. The lower limit of the BET specific surface area of ​​the porous material is, for example, 500 m ２ / g or more, 600m ２ / g or more, 700m ２ / g or more, 800m ２ / g or more, or 820m ２ The upper limit of the BET specific surface area of ​​the porous material may be, for example, 900 m ２ / g or less, 850m ２ / g or less, 840m ２ / g or less, or 830m ２ / g or less. When the upper limit of the BET specific surface area is within the above range, phase separation can be further suppressed, and a more stable quasi-solid electrolyte composition can be obtained. The BET specific surface area of ​​the porous material may be adjusted within the above range, for example, 500 to 900 m ２ / g, or 800 to 840 m ２ / g.

[0029] The BET specific surface area in this specification refers to a value measured in accordance with JIS Z 8830:2013 "Method for measuring specific surface area of ​​powder (solid) by gas adsorption." More specifically, the BET specific surface area is determined by performing nitrogen adsorption measurement at 25°C and analyzing the obtained results by the BET multipoint method.

[0030] It is preferable that the porous material has a relatively small particle size. By using a porous material with a small particle size, the thickening effect when mixed with the electrolyte solution is enhanced, and phase separation in the quasi-solid electrolyte composition can be further suppressed. The upper limit of the average particle size of the single particles (primary particles) of the porous material may be 1000 nm or less, 800 nm or less, 600 nm or less, 400 nm or less, 300 nm or less, 150 nm or less, 130 nm or less, or 100 nm or less. The lower limit of the average particle size of the single particles of the porous material may be 60 nm or more, 80 nm or more, or 90 nm or more. The average particle size of the single particles of the porous material may be adjusted within the above-mentioned range, and may be, for example, 60 to 1000 nm, 80 to 600 nm, or 100 to 300 nm.

[0031] Examples of porous materials contained in the quasi-solid electrolyte composition include zeolite. The zeolite may contain an alkali metal element. The alkali metal element contained in the zeolite may contain the same element as the alkali metal element contained in the alkali metal salt of the electrolyte. For example, when the quasi-solid electrolyte composition is used in a lithium ion battery, the zeolite may contain lithium.

[0032] The primary particle size of the zeolite may be, for example, 1000 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, or 180 nm or less. When the primary particle size of the zeolite is within the above range, semi-solidification becomes easier, making it easier to produce a quasi-solid electrolyte. When the primary particle size of the zeolite is within the above range, the viscosity of the resulting quasi-solid electrolyte composition can be made more appropriate. The lower limit of the primary particle size of the zeolite is not particularly limited, but may be, for example, 90 nm or more or 100 nm or more. The average particle size of the primary particles of the zeolite may be adjusted within the above range, and may be, for example, 90 to 1000 nm, 90 to 500 nm, or 100 to 300 nm.

[0033] In this specification, the average particle size of a single particle of a porous material and the primary particle size of a zeolite refer to the value of the 50% cumulative diameter (average particle size, D50) on a volume basis measured at 25°C by dynamic light scattering (DLS) using a dynamic scattering analyzer.

[0034] Examples of zeolites include faujasite-type (FAU-type) zeolite, etc. The faujasite-type zeolite may be either X-type zeolite (FAU-X-type) or Y-type zeolite (FAU-Y-type), but may be FAU-X-type zeolite because it is capable of forming relatively large pore diameters.

[0035] The content of the porous material is 20 to 33% by mass relative to the total amount of the quasi-solid electrolyte composition. The lower limit of the content of the porous material may be, for example, 21% by mass or more, 22% by mass or more, or 23% by mass or more. When the lower limit of the content of the porous material is within the above range, the viscosity of the quasi-solid electrolyte composition can be further increased, and the growth of lithium dendrites during use of the battery and the migration of electrolyte decomposition residues can be more sufficiently inhibited. The upper limit of the content of the porous material may be, for example, 30% by mass or less, 28% by mass or less, or 26% by mass or less. When the upper limit of the content of the porous material is within the above range, the quasi-solid electrolyte composition can be made more uniform, phase separation can be more effectively inhibited, and a decrease in flexibility can be more effectively inhibited.

[0036] The quasi-solid electrolyte composition may contain components (other components) other than the electrolyte solution and the porous material. Examples of the other components include an anion receptor, a coating-forming additive, etc. Examples of the electrolyte solution include a solution in which lithium bis(fluorosulfonyl)imide (LiFSI) is dissolved in dimethyl carbonate (DMC).

[0037] The total amount of the electrolytic solution and the porous material in the quasi-solid electrolyte composition may be 80% by mass or more, 90% by mass or more, or 95% by mass or more, based on the total amount of the quasi-solid electrolyte. The total amount of the electrolytic solution and the porous material in the quasi-solid electrolyte composition may be 100% by mass, or may be less than 100% by mass, or 98% by mass or less, based on the total amount of the quasi-solid electrolyte.

[0038] The method for producing the quasi-solid electrolyte composition is not particularly limited, but it may be prepared by mixing an electrolytic solution with a porous material.

[0039] The quasi-solid electrolyte composition of this embodiment can be used as a composition for forming an electrolyte for a battery. That is, the electrolyte of the battery or the like of this embodiment may contain the quasi-solid electrolyte composition. Examples of the battery include batteries that perform charging and discharging by the movement of alkali metal ions, such as lithium ion batteries and sodium ion batteries. The battery may be a primary battery, a secondary battery, or a quasi-solid battery.

[0040] The battery of this embodiment includes a positive electrode, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode. The positive electrode may be a layer containing a positive electrode material formed on a current collector. The negative electrode may be a layer containing a negative electrode material formed on a current collector. The following description will be given taking a lithium-ion battery as an example.

[0041] The negative electrode of the lithium ion battery is not particularly limited, and may contain a negative electrode active material and, if necessary, a conductive additive, a binder, etc.

[0042] Examples of the negative electrode active material include simple substances of elements such as Li, C, Si, P, Sn, Si—Mn, Si—Co, Si—Ni, In, and Au, alloys or composites containing these elements, carbon materials such as graphite, substances in which lithium ions are inserted between layers of the carbon materials, and oxides containing titanium.

[0043] The positive electrode of the lithium ion battery is not particularly limited, and may contain a positive electrode active material and, if necessary, a conductive additive, a binder, etc.

[0044] The positive electrode active material is not particularly limited, and examples thereof include lithium composite metal oxides containing lithium and a transition metal element. The transition metal element in the lithium composite metal oxide may be at least one selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, and Al, and may include Ni.

[0045] Examples of lithium composite metal oxides include LiCoO ２ , LiNiO ２ , LiMn ２ O ４ , LiNi ０．５ Mn １．５ O ４ , Li ２ MnO ３ , LiNi ｘ Mn ｙ Co １－ｘ－ｙ O ２ [0<x+y<1]), LiNi ｘ Co ｙ Al １－ｘ－ｙ O ２ [0<x+y<1]), LiCr ０．５ Mn ０．５ O ２ , LiFePO ４ , Li ２ FeP ２ O ７ , LiMnPO ４ , LiFeBO ３ , Li ３ V ２ (P.O. ４ ) ３ , Li ２ CuO ２ , Li ２ FeSiO ４ , Li ２ MnSiO ４ When the positive electrode active material contains an alkali metal element other than Li, specific examples thereof include those in which Li in the above specific examples is replaced with another alkali metal.

[0046] The positive electrode of the battery may be a dry positive electrode. A dry positive electrode is a positive electrode produced without using an organic solvent in the production process of the positive electrode. A dry positive electrode is preferred because it does not suffer from problems such as changes in the chemical composition of the positive electrode and thermal history that occur when the organic solvent is dried from a slurry containing a positive electrode material.

[0047] The negative electrode (negative electrode material) and the positive electrode (positive electrode material) of this embodiment may further contain a solid electrolyte material, a binding resin (binder), a conductive assistant, and the like.

[0048] The electrolyte in the battery of this embodiment is provided by forming a layer of a quasi-solid electrolyte composition on the positive electrode or the negative electrode. The method for forming the layer of the quasi-solid electrolyte composition is not particularly limited, and examples thereof include a method of applying the quasi-solid electrolyte composition to the positive electrode or the negative electrode.

[0049] The battery may have a separator. The separator may be made of a porous material. The porous material may be made of a resin. Specific examples of the porous material include a porous polyolefin membrane and a porous ceramic membrane.

[0050] The battery of this embodiment may be in a state where no restraining pressure is applied (non-pressurized state). That is, the battery of this embodiment may be in a state where no pressure is applied by a restraining means such as a restraining device. Therefore, the restraining device may be omitted. In other words, the battery of this embodiment does not need to have a restraining device. Note that the battery of this embodiment can be used even when a restraining pressure is applied.

[0051] Although several embodiments have been described above, the present disclosure is not limited to the above embodiments. Furthermore, the descriptions of the above embodiments can be applied to each other.

[0052] The present disclosure will be described in more detail below with reference to examples and comparative examples, although the present disclosure is not limited to the following examples.

[0053] Example 1: 1 mol of lithium bis(fluorosulfonyl)imide (LiFSI) was dissolved in 1.5 mol of dimethyl carbonate (DMC) to prepare a 40 mol% electrolyte solution. The molar ratio of LiFSI to DMC was 1:1.5. The electrolyte solution contained lithium-containing FAU-X zeolite (manufactured by Nakamura Choukou Co., Ltd., nano-sized zeolite, product name: Zeoal FAU-X, primary particle diameter: 100 nm, BET specific surface area: 828.6 m). ２ / g) to obtain a quasi-solid electrolyte composition. The FAU-X zeolite had a pore diameter of 13 Å. The content of the FAU-X zeolite in the quasi-solid electrolyte composition was 25 mass %.

[0054] Comparative Example 1 Instead of the FAU-X type zeolite, ZSM-5 zeolite (manufactured by Nakamura Choukou Co., Ltd., nano-sized zeolite, trade name: Zeoal ZSM-5, primary particle diameter: 99 nm, BET specific surface area: 538.6 m) was used. ２ A quasi-solid electrolyte composition was obtained in the same manner as in Example 1, except that ZSM-5 zeolite (ZSM-5 zeolite 10 ...

[0055] Comparative Example 2 The electrolytic solution prepared in Example 1 was used as it was as the electrolyte.

[0056] <Measurement of Lithium Ion Transference Number> An evaluation cell of a coin-type battery CR2032 was assembled in a glove box under a dry argon atmosphere. Specifically, each layer was laminated in the evaluation cell in the following order to prepare a test laminate.

[0057] That is, the materials were laminated so that the layer structure inside the evaluation cell was: lithium layer / electrolyte layer / lithium layer. In Example 1 and Comparative Example 1, the electrolyte layer was formed by applying each quasi-solid electrolyte composition to a lithium electrode. In Comparative Example 2, the electrolyte layer was formed by sandwiching the electrolyte solution between two lithium electrodes.

[0058] The lithium ion transport number measurement method is introduced in Polymer, 28, 2324 (1987). That is, 10 mV is applied to the test laminate at room temperature (25° C.), and the initial current value (I ０ ) and steady-state current value (I ｓｓ ) was measured, and the interface resistance measured value R ０ and the measured interface resistance R after voltage application ＳＳ The lithium ion transport number (t Ｌｉ＋ ) was calculated. V in the formula is the applied voltage. The results are shown in Table 1. Ｌｉ＋ =I ｓｓ (VI ０ R ０ ) / I ０ (VI ＳＳ R ＳＳ )

[0059] <Charge-Discharge Test Using Half Cell> An evaluation cell of coin-type battery CR2032 was assembled in a glove box under a dry argon atmosphere. Specifically, each layer was laminated in the evaluation cell in the following order to prepare a test laminate.

[0060] That is, the materials were laminated so that the layer structure inside the evaluation cell was: lithium layer / electrolyte layer / positive electrode layer. The positive electrode contained LiFePO as a positive electrode active material. ４ The cathode material was obtained by mixing, in a dry powder state, acetylene black as a conductive additive and polytetrafluoroethylene as a binder resin in a mass ratio of 70:25:5, and then pressing the resulting cathode material onto mesh-shaped aluminum using a hydraulic press and welding the aluminum to prevent it from coming off. In other words, the cathode is a dry type cathode.

[0061] In Example 1 and Comparative Example 1, the electrolyte layer was formed by applying each quasi-solid electrolyte composition to a lithium electrode. In Comparative Example 2, the electrolyte layer was formed by sandwiching the electrolyte solution between a lithium electrode and a positive electrode. These are the half-cells of Example 1, Comparative Example 1, and Comparative Example 2, respectively. Note that each half-cell was in a state where no confining pressure was applied.

[0062] Using the above evaluation cell, 2.5-4.0 V (vs. Li / Li ＋ ) and 50 charge / discharge cycles were measured. The capacity retention rate after 50 cycles is shown in Table 1. The cycle capacity retention rate is the ratio of the discharge capacity after 50 cycles to the initial discharge capacity. FIG. 1 shows the relationship between the capacity retention rate and the number of cycles for the half cells of Example 1, Comparative Example 1, and Comparative Example 2. FIG. 2 shows the relationship between the reversible capacity and the number of cycles for the half cells of Example 1, Comparative Example 1, and Comparative Example 2.

[0063]

Claims

1. A quasi-solid electrolyte composition comprising: an electrolyte solution containing an alkali metal salt and an organic solvent; and a porous material; wherein the content of the alkali metal salt is 11 mol% or more based on the total amount of the alkali metal salt and the organic solvent; the pore diameter of the porous material is 7 to 13 Å; and the content of the porous material is 20 to 33 mass% with respect to the total amount of the quasi-solid electrolyte composition.

2. The quasi-solid electrolyte composition according to claim 1, wherein the average particle size of the porous material is 1000 nm or less.

3. The quasi-solid electrolyte composition according to claim 1 or 2, wherein the porous material is a zeolite.

4. The quasi-solid electrolyte composition according to claim 1 or 2, wherein the porous material is FAU-X type zeolite.

5. A battery comprising the quasi-solid electrolyte composition according to claim 1 or 2.

6. The battery according to claim 5, wherein the positive electrode is a dry type positive electrode.

7. The battery of claim 5, wherein no confining pressure is applied.

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