Secondary battery and method for manufacturing secondary battery

Abstract

The present invention is provided with: a positive electrode layer (14) having a positive electrode active material (14a); a negative electrode layer (12) having a negative electrode active material (12a); a separator (15) sandwiched between the positive electrode layer and the negative electrode layer; and a polymer electrolyte (16) containing a polymer and an electrolyte salt. A polymerization control material (14b) for suppressing the polymerization reaction of the polymer is provided to at least one of the positive electrode layer and the negative electrode layer. The polymer electrolyte has a first region (16a) present in the electrode layer provided with the polymerization control material, and a second region (16b) present in the separator. The degree of polymerization of the polymer in the first region is lower than that in the second region. The polymerization of the polymer proceeds by a polymerization initiator, and the polymerization control material traps a polymerization initiator component to suppress the polymerization of the polymer.

Description

Secondary battery and method for manufacturing a secondary battery Cross-reference of related applications

[0001] This application is based on Japanese Patent Application No. 2025-8905, filed on January 22, 2025, and its contents are incorporated herein by reference.

[0002] This disclosure relates to a secondary battery and a method for manufacturing a secondary battery.

[0003] Patent documents 1 and 2 disclose the use of a gel polymer electrolyte, which is a mixture of a non-aqueous electrolyte and a polymer, as a solid electrolyte for secondary batteries. In a gel polymer electrolyte, a small amount of gel polymer holds the organic solvent contained in the electrolyte, thus preventing leakage of organic solvent from the secondary battery and enhancing safety.

[0004] Patent No. 7108117, Patent No. 6959885

[0005] The degree of polymerization in a gel polymer electrolyte is determined by the ratio of the polymer species to the polymerization initiator. For example, increasing the ratio of polymerization initiator to polymer species increases the degree of polymerization. Increasing the degree of polymerization is known as a technique to improve battery safety because it can prevent leakage.

[0006] In the configurations described in Patent Documents 1 and 2, it is not possible to control the degree of polymer polymerization at any location in the secondary battery. Therefore, if the degree of polymer polymerization is high near the electrode active material, the interfacial resistance between the electrode active material and the electrolyte increases, leading to an increase in cell resistance. On the other hand, if the amount of initiator is reduced and a polymer with a low degree of polymerization is used, leakage cannot be prevented, resulting in a decrease in safety.

[0007] In view of the above, this disclosure aims to reduce the interfacial resistance between the electrode active material and the electrolyte while preventing leakage in a secondary battery using a polymer electrolyte.

[0008] To achieve the above objective, one aspect of the present disclosure comprises a positive electrode layer having a positive electrode active material, a negative electrode layer having a negative electrode active material, a separator sandwiched between the positive electrode layer and the negative electrode layer, and a polymer electrolyte containing a polymer and an electrolyte salt. A polymerization control material is provided in at least one of the electrode layers, either the positive electrode layer or the negative electrode layer, to suppress the polymerization reaction of the polymer. The polymer electrolyte has a first region present in the electrode layer where the polymerization control material is provided, and a second region present in the separator. The degree of polymerization of the polymer in the first region is lower than that in the second region.

[0009] This allows for a lower degree of polymerization of the polymer electrolyte in the electrode layer, thereby reducing the interfacial resistance between the positive or negative electrode active material and the electrolyte. Furthermore, since the excess liquid that does not penetrate into the separator or electrode layer does not contain polymerization control agents, the degree of polymerization can be controlled to a level sufficient to prevent leakage. As a result, the cell resistance of the secondary battery can be lowered without compromising the leakage prevention effect of the polymer electrolyte, thereby improving the output of the secondary battery.

[0010] This is a cross-sectional view showing the configuration of a secondary battery according to the embodiment of this disclosure. This is a conceptual diagram showing the configuration of the positive electrode layer, separator, and polymer electrolyte. This is a conceptual diagram showing the configuration of the positive electrode layer, separator, and polymer electrolyte. This is a conceptual diagram showing the configuration of the positive electrode layer, separator, and polymer electrolyte. This is a flowchart showing the manufacturing process of a secondary battery. This is a flowchart showing the manufacturing process of a secondary battery. This is a flowchart showing the manufacturing process of a secondary battery. This is a diagram showing the degree of polymer polymerization and cell resistance of the polymer electrolytes of the examples and comparative examples.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The secondary battery 10 of this embodiment is a lithium-ion battery in which lithium ions are conducted as conductive ions.

[0012] As shown in Figure 1, the secondary battery 10 comprises a negative electrode current collector 11, a negative electrode layer 12, a positive electrode current collector 13, a positive electrode layer 14, a separator 15, and a polymer electrolyte 16 as its components. The negative electrode current collector 11, the negative electrode layer 12, the positive electrode current collector 13, the positive electrode layer 14, and the separator 15 form a laminate stacked along a predetermined stacking direction.

[0013] A separator 15 is sandwiched between a pair of electrode layers 12 and 14, which consist of a negative electrode layer 12 and a positive electrode layer 14. The negative electrode layer 12 and the separator 15 are in contact. The positive electrode layer 14 and the separator 15 are in contact. The negative electrode layer 12 and the positive electrode layer 14 are connected via the separator 15. The secondary battery 10 is charged and discharged by lithium ions moving between the negative electrode layer 12 and the positive electrode layer 14 via the separator 15.

[0014] The negative electrode current collector 11 and the positive electrode current collector 13 can be made of any material suitable for use as a current collector in a lithium-ion battery. In this embodiment, Cu is used as the negative electrode current collector 11 and Al is used as the positive electrode current collector 13.

[0015] The negative electrode layer 12 is provided with a negative electrode mixture containing a negative electrode active material 12a. Any material usable as a negative electrode active material 12a for lithium-ion batteries can be used as the negative electrode active material 12a. Examples of negative electrode active materials 12a include carbon-based negative electrode materials such as graphite, amorphous carbon, fullerene, and carbon nanotubes, lithium metal materials, metal-based negative electrode materials such as silicon and tin, and Nb ２ O ５ YaTiO ２ Oxide-based negative electrodes such as those mentioned above, or composites thereof, can be used.

[0016] The negative electrode mixture may contain a conductive additive, a binder, and a polymer. The conductive additive can be a carbon material such as carbon black. As the binder, an aqueous binder such as a mixture of SBR (styrene-butadiene rubber) and CMC (carboxymethylcellulose) can be used.

[0017] The positive electrode layer 14 releases lithium ions when the secondary battery 10 is charged and accepts lithium ions when the secondary battery 10 is discharged. The positive electrode layer 14 is provided with a positive electrode mixture containing a positive electrode active material 14a and a polymerization control material 14b. The polymerization control material 14b is provided to lower the degree of polymerization of the polymer electrolyte 16. The polymerization control material 14b will be described in detail later.

[0018] As the positive electrode active material 14a, any material that can be used for the positive electrode active material 14a of a lithium-ion battery can be used. As the positive electrode active material 14a, for example, a layered rock salt type active material, an olivine type active material, or a spinel type active material can be used. As the layered rock salt type active material, for example, LiNi ｘ Co ｙ Mn ｚ O ２ (NCM), LiNi ｘ Co ｙ Al ｚ O ２ (NCA) and other ternary system positive electrode materials can be used. As the olivine type active material, for example, LiFePO ４ (LFP), LiMn １－ｘ Fe ｘ PO ４ (LMFP), LiMnPO ４ (LMP), LiCoPO ４ (LCP), LiNiPO ４ (LNP) can be used. As the spinel type active material, for example, LiMn ２ O ４ (LMO), LiNi ０．５ Mn １．５ O ４ (LNMO) can be used.

[0019] The positive electrode binder may contain a conductive aid, a binder, and a polymer. As the conductive aid, for example, a carbon material such as carbon black can be used. As the binder, for example, polyvinylidene fluoride (PVdF) can be used.

[0020] The separator 15 is disposed between the negative electrode layer 12 and the positive electrode layer 14 and separates the negative electrode layer 12 and the positive electrode layer 14. The separator 15 is an insulating ion permeable membrane that prevents physical contact between the negative electrode layer 12 and the positive electrode layer 14 and suppresses electrical short circuits, and allows ions to permeate.

[0021] The separator 15 is formed of a porous body such as a resin porous membrane, a woven fabric, or a non-woven fabric. As the material of the separator 15, for example, polyolefin resins such as polypropylene and polyethylene, non-woven fabrics such as cellulose, aramid, and polyester can be used.

[0022] The separator 15 may be surface-coated with a dissimilar material. Examples of dissimilar materials include mixtures of ceramic materials such as alumina, titania, boehmite, magnesium hydroxide, and barium sulfate with binders such as PVDF, PTFE, acrylic copolymers, and PVA, and mixtures of resin materials such as methaluminium and paraaramid with the above-mentioned binders.

[0023] As the polymer electrolyte 16, for example, a dry polymer electrolyte having lithium ion conductivity, or a gel polymer electrolyte composed of a gel polymer having gelling properties and a non-aqueous electrolyte can be used.

[0024] In the case of gel polymer electrolytes, the electrolyte solution contained in the polymer electrolyte 16 is retained by the polymer. Gel polymer electrolytes have moderate plasticity and tackiness, and possess ionic conductivity close to that of non-aqueous electrolytes. On the other hand, dry polymer electrolytes consist of polymer and electrolyte, and the polymer itself acts as the electrolyte solution, so they can be used as an electrolyte material without using an electrolyte solution. Furthermore, dry polymer electrolytes can contain a solvent as needed.

[0025] As shown by the dashed line in Figure 1, the polymer electrolyte 16 is provided extending from the negative electrode layer 12 to the positive electrode layer 14. The polymer electrolyte 16 is provided so as to penetrate into the interior of the negative electrode layer 12, the positive electrode layer 14, and the separator 15.

[0026] The polymer electrolyte material, which is the raw material for the polymer electrolyte 16, contains a monomer or electrolyte that serves as the raw material for a polymer compound having lithium ion conductivity, and a monomer that serves as the raw material for a polymer compound having gelling properties. The electrolyte has lithium ion conductivity and conducts conductive ions between the negative electrode layer 12 and the positive electrode layer 14. The electrolyte contains an electrolyte salt and a solvent that dissolves the electrolyte salt. The electrolyte salt contains conductive ions. In this embodiment, a lithium salt containing lithium is used as the electrolyte salt.

[0027] By injecting polymer electrolyte material into a laminate consisting of a negative electrode current collector 11, a negative electrode layer 12, a separator 15, a positive electrode current collector 13, and a positive electrode layer 14, polymerization is initiated, and the polymerization reaction proceeds to obtain a polymer electrolyte 16. This allows the electrolyte to be constantly maintained inside the negative electrode layer 12, the positive electrode layer 14, and the separator 15, enabling the charge-discharge reaction to proceed smoothly.

[0028] Polymerization of monomers contained in polymer electrolyte materials is initiated by a polymerization initiator. In the secondary battery 10 of this embodiment, the electrolyte salt contained in the polymer electrolyte material functions as a polymerization initiator, and polymer polymerization takes place.

[0029] In this embodiment, the concentration of the electrolyte salt is kept within the range of 0.5 to 5 mol / L. If the electrolyte salt concentration falls below 0.5 mol / L, the lithium ion transport capacity decreases and the cell resistance increases. Furthermore, it becomes difficult to utilize it as a polymerization initiator. On the other hand, if the electrolyte salt concentration exceeds 5 mol / L, the electrolyte salt cannot be sufficiently dissolved in the solvent, and excess electrolyte salt remains in the solvent in a solid state, increasing the cell resistance.

[0030] As an electrolyte salt that functions as a polymerization initiator, LiPF ６ LiBF ４ , LiDFOB, LiBOB, LiFSI, LiTFSI, LiBETI, LiAsF ６ LiClO ４ LiSbF ６ The following can be used. The electrolyte salt may be used alone or in combination of two or more types. In this embodiment, LiPF is used as the electrolyte salt. ６ It uses this.

[0031] As the solvent for the electrolyte, one or more organic solvents can be used, such as cyclic carbonates like ethylene carbonate, propylene carbonate, vinylene carbonate, and butylene carbonate, or chain carbonates like ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and dipropyl carbonate (DPC).

[0032] The monomer contained in the polymer electrolyte material of this embodiment is polymerized using a cationic polymerization initiator, anionic polymerization initiator, or radical polymerization initiator. ６ Electrolyte salts, including the above, can also be used as polymerization initiators. Examples of monomers for dry polymers or gel polymers include 1,3-dioxolane, 1,3,5-trioxane, methyl methacrylate-oxetanyl methacrylate copolymer, a combination of a crosslinkable compound with three or more oxirane rings and a crosslinkable compound with one or two oxirane rings, polyethylene glycol methacrylate and methacrylate monomer, n-butyl acrylate, a copolymer of n-butyl methacrylate, 1,4-butanediol diglycidyl ether, ethylene oxide, vinyl chloride, etc. In this embodiment, 1,3-dioxolane is used as the monomer.

[0033] LiPF as an electrolyte salt ６ When used, the following reaction proceeds and LiPF ６ From H, which is a protonic acid. ＋ (PF ５ OH) － It generates.

[0034] LiPF ６ →Li ＋ +PF ６ － Li ＋ +PF ６ － → LiF + PF ５ PF ５ +H ２ O→H ＋ (PF ５ OH) － LiPF ６ H generated from ＋ (PF ５ OH) － It coordinates to the polymer species, H ＋ (PF ５ OH) － Another polymer nucleophilically attacks the polymer to which one of the molecules is coordinated, and ring-opening polymerization proceeds. LiPF is used as the electrolyte salt. ６ When using LiPF ６ From PF ６－ PF generated via ５ and H ２ Protonate H is produced when O reacts. ＋ (PF ５ OH) － It functions as a polymerization initiator.

[0035] Next, the polymerization control material 14b contained in the positive electrode layer 14 will be described. The polymerization control material 14b has the function of suppressing the polymerization reaction of the polymer electrolyte 16 and lowering the degree of polymer polymerization. LiPF is used as the electrolyte salt. ６ When used, PF is added to the polymerization control material 14b. ６ － Because it coordinates, LiPF ６ From PF ６ － via PF ５ The generation of anions can be suppressed. Polymerization control material 14b converts electrolyte salts to anions PF ６ － By trapping the electrolyte salt, its function as a polymerization initiator can be suppressed, and the polymer polymerization reaction in the region of the polymer electrolyte 16 where the polymerization control material 14b is present is suppressed.

[0036] In this embodiment, the weight ratio of the polymerization control material 14b to the positive electrode active material 14a is set to within the range of 2 to 10 wt%. If the weight ratio of the polymerization control material 14b is less than 2 wt%, a sufficient effect in reducing the degree of polymerization of the polymer electrolyte 16 cannot be obtained. In order to increase the effect of reducing the degree of polymerization of the polymer electrolyte 16, it is desirable to set the weight ratio of the polymerization control material 14b to 3 wt% or more, and more preferably to 5 wt% or more. On the other hand, if the weight ratio of the polymerization control material 14b exceeds 10 wt%, there will be too much polymerization control material 14b, which will hinder contact between the positive electrode active material 14a and the electrolyte, leading to a decrease in ionic conductivity. For this reason, it is desirable that the weight ratio of the polymerization control material 14b to the positive electrode active material 14a be between 2 wt% and 10 wt%. To maximize the effect of the polymerization control material 14b on reducing the interfacial resistance between the positive electrode active material 14a and the electrolyte, the weight ratio of the polymerization control material 14b to the positive electrode active material 14a is more preferably 3 to 10 wt%, and even more preferably 5 to 10 wt%.

[0037] The polymerization control material 14b is a dielectric, and electrostatic attraction acts on the electrolyte salt. As a result, the dissociation of lithium ions from the electrolyte salt is promoted, and PF ６ － can be coordinated to suppress the generation of PF5, and the degree of polymerization of the polymer electrolyte 16 can be lowered.

[0038] As the dielectric constituting the polymerization control material 14b, for example, Al ２ O ３ or an oxide-based inorganic solid electrolyte can be used. Since the inorganic solid electrolyte has a high dielectric constant, the higher the dielectric constant of the polymerization control material 14b, the more the function of the polymerization initiator can be suppressed, and the higher the effect of lowering the degree of polymerization of the polymer electrolyte 16. Therefore, it is desirable to use an inorganic solid electrolyte having a high dielectric constant as the polymerization control material 14b.

[0039] As the inorganic solid electrolyte, for example, dielectrics such as garnet-type solid electrolyte, NASICON-type oxide, and pyrochlore-type solid electrolyte can be used. As the garnet-type solid electrolyte, for example, LLZ (Li ７ La ３ Zr ２ O １２ ) can be used. As the NASICON-type oxide, for example, LATP (Li １＋ｘ Al ｘ Ti ２－ｘ (PO ４ ) ３ ) can be used. As the pyrochlore-type solid electrolyte, for example, LLNOF (Li １．２５ La ０．５８ Nb ２ O ６ F) can be used. LLNOF is an oxyfluoride having a defect structure in at least a part of the cation site.

[0040] The pyrochlore-type oxide has high ionic conductivity and can improve the ionic conductivity of the secondary battery 10. In addition, the pyrochlore-type oxide is a material having a high dielectric constant, and has a high effect of lowering the degree of polymerization of the polymer electrolyte 16.

[0041] The higher the dielectric constant of the polymerization control material 14b, the more effective it is at trapping anions generated from the electrolyte salt, and the more effective it is at suppressing the electrolyte salt from functioning as a polymerization initiator. For this reason, it is desirable that the relative dielectric constant of the polymerization control material 14b be 90 or higher, and it is even more desirable that the relative dielectric constant of the polymerization control material 14b be 200 or higher. Examples of polymerization control materials 14b with a relative dielectric constant of 90 or higher include LATP and LLNOF, and an example of a polymerization control material 14b with a relative dielectric constant of 200 or higher is LLNOF.

[0042] The pyrochlore-type oxide used in this embodiment has the compositional formula "Aa ２－α Ab （１＋α）／３ B ２ O ７－β X γ It has a pyrochlore structure represented by the above compositional formula. In the above compositional formula, O is an oxygen atom, and Aa, Ab, B, and X represent any element or group. Aa, Ab, and B are each different types of cations, and O and X are each different types of anions. Aa is an alkali metal cation. Pyrochlore-type oxides contain multiple cations in their composition, consisting of an alkali metal cation Aa and multiple cations Ab and B other than the alkali metal cation Aa. In other words, pyrochlore-type oxides contain multiple cations in their composition, including the alkali metal cation Aa.

[0043] In the above compositional formula, 0.6 < α < 2.0, 0 < β ≤ 1, and 0 < γ ≤ 1. A change in α alters the compositional ratio of Aa and Ab, and a change in β and γ alters the compositional ratio of O and X.

[0044] Cation Aa is an alkali metal cation. Li, Na, K, Rb, and Cs can be used as the alkali metal represented by Aa. Mg or H, other than alkali metals, may also be used as cation Aa. In other words, cation Aa contains at least one selected from Li, Na, K, Rb, Cs, Mg, and H. In LLNOF, Li is used as Aa. The composition ratio (2-α) of Aa is within the range of 0 < (2-α) < 1.4.

[0045] The cation Ab contains at least one lanthanide. At least one of La, Ce, Nd, or Sm can be used as the lanthanide represented by Ab. In LLNOF, La is used as Ab. The composition ratio of Ab (1+α) / 3 is within the range of 0.53 < (1+α) / 3 < 1.

[0046] The basic structure of the cation Ab consists of lanthanides, and some of the lanthanides constituting Ab may be substituted with alkaline earth metals (Ca, Mg, Sr, etc.). In this embodiment, the pyrochlore-type oxide has a pyrochlore structure where 0.6 < α < 2.0 and 0 < β ≤ 1. It is thought that the inclusion of lanthanides in this pyrochlore structure creates defects in the crystal structure, thereby improving ionic conductivity. In LLNOF, La is used as Ab.

[0047] In this embodiment, the pyrochlore-type oxide has a composite cation in which cation A in the typical pyrochlore structure's composition formula "A2B2O7" is composed of lithium metal and a lanthanide. This is thought to contribute to the improved ionic conductivity of the pyrochlore-type oxide.

[0048] Cation B is a metallic cation distinct from Aa and Ab, and is a transition metal or a metal selected from group 13 to 15 elements. In the crystal, B forms an octahedron surrounded by six oxygen atoms. As the transition metal represented by B, group 4 or group 5 transition metals can be used, and more specifically, at least one of Nb, Ta, Ti, Zr, Hf, or V can be used. As group 13 elements represented by B, Al, Ga, and In can be used; as group 14 elements, Ge and Sn can be used; and as group 15 elements, Sb and Bi can be used. In LLNOF, Nb is used as B.

[0049] Anion X is an anion that can replace the O atom constituting the pyrochlore structure. X has different electronegativity and polarizability from the O atom. As the anion represented by X, at least one of O, F, Cl, Br, I, S, OH, and P can be used. The composition ratio γ of X is within the range of 0 < γ ≤ 1, and at least a part of the O atoms constituting the pyrochlore structure is replaced by X. The pyrochlore-type oxide is preferably an oxyfluoride in which a part of O is replaced by F.

[0050] In the pyrochlore-type oxide of the present embodiment, since a part of the O atoms constituting the pyrochlore structure is replaced by an anion having different electronegativity and polarizability from the O atom, the crystal has a defective structure containing lattice defects. It is considered that the ionic conductivity of the pyrochlore-type oxide of the present embodiment is improved because the defective structure is included in the pyrochlore structure.

[0051] In the pyrochlore-type oxide of the present embodiment, as a defective structure, a part of Aa and Ab is in a defective state. The general compositional formula of the pyrochlore structure is "A ２ B ２ O ７ ", and the composition ratio of the cation A is 2. On the other hand, in the pyrochlore-type oxide of the present embodiment, the composition ratios of Aa and Ab are "2 - α" and "(1 + α) / 3", respectively, and 0.6 < α < 2.0. Therefore, the total of the composition ratios of Aa and Ab is less than 2. That is, in the crystal structure of the pyrochlore-type oxide of the present embodiment, at least a part of Aa and Ab is defective. The composition ratio corresponding to the defective parts of Aa and Ab is (2α - 1) / 3.

[0052] In addition to the deviation of the composition ratio, in the above compositional formula, a defective structure can also be formed by making the sum of the valences of the cation composed of Aa, Ab, and B and the anion composed of O and X negative.

[0053] Further, the pyrochlore-type oxide of the present embodiment is a composite anion compound containing a plurality of anions such as O and X in the pyrochlore structure, and BO ６Because there is an anion represented by X in the octahedron structure, alkali metals Aa are BO ６ Without relying on an octahedron, BO ６ It can be positioned in the center of the space between the octahedron and the surrounding structure. Therefore, it is believed that the pyrochlore-type oxide of this embodiment exhibited high ionic conductivity when used with an electric field such as that of a battery.

[0054] Furthermore, since α, β, and γ in the above compositional formula affect lattice defects and ionic conductivity, it is desirable to use them within an appropriate range. Larger values ​​of α, β, and γ increase the defect concentration in the crystal lattice, but beyond a certain amount, the concentration of alkali metal represented by Aa decreases, and the ionic conductivity declines. For this reason, it is desirable to control α within the range of 0.6 < α < 2.0, β within the range of 0 < β ≤ 1, and γ within the range of 0 < γ ≤ 1.

[0055] The pyrochlore-type oxide of this embodiment is 1 × 10 －３ Ionic conductivity of S / cm or higher has been obtained. The pyrochlore-type oxide of this embodiment exhibits significantly higher ionic conductivity than other oxide-based solid electrolytes such as garnet-type oxides.

[0056] Furthermore, acid fluorides having defect structures in at least some of their cation sites have improved dielectric properties due to lattice defects, which can enhance the anion trapping effect of the polymerization control material 15b on the electrolyte salt. This suppresses the electrolyte salt from functioning as a polymerization initiator, inhibits polymer polymerization of the polymer electrolyte 16, and further reduces the interfacial resistance between the positive electrode active material 15a and the electrolyte.

[0057] Next, the configuration of the polymerization control material 14b in the positive electrode layer 14 will be explained using Figures 2 to 4. Figures 2 to 4 show only the positive electrode current collector 13, the positive electrode layer 14, and the separator 15.

[0058] In the positive electrode layer 14, the positive electrode active material 14a and the polymerization control material 14b can be provided in any configuration. In the examples shown in Figures 2 to 4, the configurations of the positive electrode active material 14a and the polymerization control material 14b in the positive electrode layer 14 are different.

[0059] The polymerization control material 14b reduces the degree of polymerization of the polymer electrolyte 16, thereby reducing the interfacial resistance between the positive electrode active material 14a and the electrolyte contained in the polymer electrolyte 16. For this reason, it is desirable that the polymerization control material 14b be placed as close as possible to the positive electrode active material 14a. It is also desirable that the polymerization control material 14b is in contact with the positive electrode active material 14a in some respects.

[0060] Figure 2 shows an example in which the polymerization control material 14b is provided between the separator 15 and the positive electrode active material 14a. In the example shown in Figure 2, the polymerization control material 14b is provided on the positive electrode side surface of the separator 15. The polymerization control material 14b is coated on the positive electrode side surface of the separator 15, and the positive electrode side surface of the separator 15 is covered with the polymerization control material 14b. In the example shown in Figure 2, the weight ratio of the polymerization control material 14b can be adjusted by adjusting the thickness of the polymerization control material 14b applied to the positive electrode side surface of the separator 15.

[0061] Figure 3 shows an example in which particulate positive electrode active material 14a and particulate polymerization control material 14b are randomly mixed in a random structure within the positive electrode layer 14. The particulate polymerization control material 14b is dispersed within the positive electrode layer 14, and at least a portion of it is in contact with the positive electrode active material 14a. In the example shown in Figure 3, the weight ratio of the polymerization control material 14b can be adjusted by adjusting the mixing ratio of the polymerization control material 14b.

[0062] Figure 4 shows an example in which the surface of the particulate positive electrode active material 14a in the positive electrode layer 14 is covered with a polymerization control material 14b, forming a layered structure. The polymerization control material 14b may cover only a part of the positive electrode active material 14a, or it may cover the entire positive electrode active material 14a. In the example shown in Figure 4, the weight ratio of the polymerization control material 14b can be adjusted by adjusting the thickness and coverage rate of the polymerization control material 14b covering the surface of the positive electrode active material 14a.

[0063] In the configurations shown in Figures 3 and 4, it is desirable to make the particle size of the polymerization control material 14b smaller than that of the positive electrode active material 14a. By making the particle size of the polymerization control material 14b smaller than that of the positive electrode active material 14a, the density of the polymerization control material 14b in the vicinity of the positive electrode active material 14a can be increased. This effectively reduces the degree of polymerization of the polymer electrolyte 16 in the vicinity of the positive electrode active material 14a.

[0064] Furthermore, the smaller the particle size of the polymerization control material 14b, the larger the specific surface area of ​​the polymerization control material 14b, and the higher the dielectric effect of the polymerization control material 14b. This enhances the effect of the polymerization control material 14b in trapping anions generated from the electrolyte salt and suppressing the electrolyte salt from functioning as a polymerization initiator.

[0065] As shown in Figures 2 to 4, the polymer electrolyte 16 has a first region 16a and a second region 16b. The first region 16a is a region located in the positive electrode layer 14 where the polymerization control material 14b in the polymer electrolyte 16 is provided, and is a region in which the polymer electrolyte 16 is impregnated into the positive electrode layer 14. The second region 16b is a region located in the separator 15 where the polymerization control material 14b in the polymer electrolyte 16 is not provided, and is a region in which the polymer electrolyte 16 is impregnated into the separator 15.

[0066] The first region 16a and the second region 16b are at different distances from the polymerization control material 14b. The first region 16a is a region where the polymerization control material 14b and the polymer electrolyte 16 are close together. The second region 16b is a region where the distance between the polymerization control material 14b and the polymer electrolyte 16 is greater than that of the first region 16a.

[0067] As described above, the polymerization control agent 14b lowers the degree of polymerization of the polymer electrolyte 16. Therefore, the degree of polymerization of the polymer electrolyte 16 differs depending on its distance from the polymerization control agent 14b. Specifically, the first region 16a of the polymer electrolyte 16 located near the polymerization control agent 14b has a low degree of polymerization, while the second region 16b of the polymer electrolyte 16 located further away from the polymerization control agent 14b has a high degree of polymerization.

[0068] In the first region 16a, the degree of polymer polymerization is lower than in the second region 16b, which reduces the viscosity of the polymer electrolyte 16. This reduces the interfacial resistance between the positive electrode active material 14a and the electrolyte contained in the first region 16a of the polymer electrolyte 16, thereby reducing the cell resistance of the secondary battery 10. To sufficiently reduce the cell resistance of the secondary battery 10, it is desirable that the degree of polymer polymerization in the first region 16a be 70% or less of the degree of polymer polymerization in the second region 16b. To make the degree of polymer polymerization in the first region 16a 70% or less of the degree of polymer polymerization in the second region 16b, for example, the weight ratio of the polymerization control material 14b to the positive electrode active material 14a should be 3 wt% or more.

[0069] Next, the manufacturing process of the secondary battery 10 of this embodiment will be described. Figure 5 shows the manufacturing process for a configuration in which polymerization control material 14b is provided on the surface of the separator 15. Figure 6 shows the manufacturing process for a configuration in which particles of positive electrode active material 14a and particles of polymerization control material 14b are randomly mixed. Figure 7 shows the manufacturing process for a configuration in which the particle surface of positive electrode active material 14a is coated with polymerization control material 14b.

[0070] A manufacturing process for a configuration in which a polymerization control material 14b is provided on the surface of the separator 15 will be explained with reference to Figure 6.

[0071] First, a coating step S10 is performed in which a polymerization control material 14b is applied to the positive electrode layer side surface of the separator 15. The coating step S10 provides the polymerization control material 14b to the positive electrode layer side surface of the separator 15, and the surface of the separator 15 is covered with the polymerization control material 14b. The polymerization control material 14b provided on the surface of the separator 15 constitutes a part of the positive electrode layer 14.

[0072] Next, a laminate manufacturing step S11 is performed in which a layer of positive electrode active material 14a is laminated on the surface of the separator 15 on which the polymerization control material 14b is provided, and then a negative electrode current collector 11, a negative electrode layer 12, and a positive electrode current collector 13 are laminated to create a laminate.

[0073] Next, an injection step S12 is performed in which the polymer electrolyte material, which is the raw material for the polymer electrolyte 16, is injected into the laminate. After the injection step S12, the polymer electrolyte material is subjected to a polymerization step S13 in which the polymerization reaction is initiated using the electrolyte salt as a polymerization initiator, and polymer polymerization proceeds.

[0074] In polymerization step S13, the polymerization reaction in the first region 16a is suppressed by the polymerization control agent 14b, and the degree of polymer polymerization in the first region 16a becomes lower than that of the second region 16b.

[0075] Next, a manufacturing process for a configuration in which the positive electrode active material 14a and polymerization control material 14b are randomly mixed will be explained using Figure 6. In this configuration, instead of the coating process S11 in Figure 5, a mixing process S14 is performed in which the particles of the positive electrode active material 14a and the particles of the polymerization control material 14b are randomly mixed to produce the positive electrode layer 14. Following the mixing process S14, the laminate production process S11, the injection process S12, and the polymerization process S13 described above are performed in order.

[0076] Next, the manufacturing process for a configuration in which the particle surface of the positive electrode active material 14a is coated with a polymerization control material 14b will be explained using Figure 7. In this configuration, instead of the coating process S11 in Figure 5, a coating process S15 is performed in which the surface of the positive electrode active material 14a is coated with the polymerization control material 14b to produce the positive electrode layer 14. Following the coating process S15, the laminate production process S11, the injection process S12, and the polymerization process S13 described above are performed in order.

[0077] Next, the degree of polymerization of the polymer electrolyte 16 and the cell resistance of the secondary battery 10 will be explained using examples and comparative examples. Figure 8 shows the degree of polymerization of the polymer electrolyte 16 and the cell resistance of the secondary battery 10 when the type and arrangement of the polymerization control material 14b are different.

[0078] In Example 1 and Comparative Examples 1 and 2, aluminum trifluoromethanesulfonate (Al(Otf)) was used as the polymerization initiator. ３ In Comparative Example 2, the separator 15 is impregnated with polymer electrolyte 16 containing a polymerization initiator, and the negative electrode layer 12 and positive electrode layer 14 are impregnated with polymer electrolyte 16 that does not contain a polymerization initiator. In Examples 2 to 12, the electrolyte salt LiPF6 is used as the polymerization initiator.

[0079] In Examples 1 and 2 and Comparative Example 2, Al was used as the polymerization control agent 14b. ２ O ３ Examples use LLZ as polymerization control agent 14b. Examples 4 to 9 use LATP as polymerization control agent 14b. Examples 10 to 12 use LLNOF as polymerization control agent 14b. Comparative Example 1 does not use polymerization control agent 14b. LLNOF used as polymerization control agent 14b in Examples 10 to 12 is an acid fluoride having a defect structure in its crystal.

[0080] The weight ratio of polymerization control material 14b to positive electrode active material 14a was 2.0 wt% for Examples 1 to 4, 3.0 wt% for Examples 5 and 10, 5.0 wt% for Examples 6, 8, 9, and 11, and 10.0 wt% for Examples 7 and 12.

[0081] The relative permittivity of the polymerization control material 14b in Examples 1 to 12 and Comparative Example 2 was calculated by dividing the measured dielectric constant ε' of the polymerization control material 14b by the dielectric constant ε0 of vacuum. The dielectric constant ε0 of vacuum is 8.85 × 10⁻⁶. －１２ The value was set to (F / m). The dielectric constant ε' of the polymerization control material 14b was measured as follows.

[0082] The polymerization control material 14b powder to be measured was pressure-molded to produce pellets. The polymerization control material 14b pellets were sintered at a high temperature. The sintering conditions differed for each type of polymerization control material 14b. For example, LLNOF was wrapped in Pt foil to prevent fluorine volatilization, sealed in an alumina crucible, and heated at 1000°C for 6 hours. The sintered polymerization control material 14b pellets were removed, and electrodes were formed by sputtering Ag onto both sides of the pellets to a thickness of 300 nm to prepare samples for dielectric constant measurement.

[0083] The measurement sample was placed in a 25°C constant temperature bath and connected to a high-frequency impedance measuring device, and the dielectric constant was measured in voltage mode (PEIS). Impedance measurements were performed with a voltage amplitude of 10 mV and a frequency range of 100 MHz to 20 Hz.

[0084] The dielectric constant ε' of the measurement sample was calculated using the impedance measurement value according to the following formula (1).

[0085]

[0086] However, z' = the real part of the impedance, z'' = the imaginary part of the impedance, ω = 2πf, and f = the frequency at which the impedance was measured, specifically 11 MHz. C0 is the capacitance when there is no measurement sample, and was calculated using the following formula (2).

[0087]

[0088] Here, ε0 = permittivity of vacuum, S = area of ​​the electrode, and d = distance between the electrodes.

[0089] Furthermore, the measured dielectric constant may have an error of up to ±10%. This error can be caused by variations in the sintering density of the pellet sample during firing, variations in the contact properties of the Ag electrode in the sample, and other factors. In addition, pyrochlore-type oxides such as LLNOF tend to have larger errors when measuring the dielectric constant because halogens and lithium are desorbed during sintering, causing variations in the content of these elements.

[0090] The Al used in Examples 1 and 2 and Comparative Example 2 ２ O ３ The relative permittivity of is 3. The relative permittivity of LLZ used in Example 3 is 35. The relative permittivity of LATP used in Examples 4-9 is 93. The relative permittivity of LLNOF used in Examples 10-12 is 215.

[0091] In other words, in Examples 4 to 12, the positive electrode layer 14 is provided with a polymerization control material 14b having a high dielectric constant of 93 or more. In particular, in Examples 10 to 12, the positive electrode layer 14 is provided with a polymerization control material 14b having an even higher dielectric constant of 200 or more.

[0092] In Examples 1 to 7, the polymerization control material 14b is provided on the positive electrode side surface of the separator 15. In Examples 8 to 12, the polymerization control material 14b is provided mixed with the positive electrode active material 14a. In Comparative Example 2, the polymerization control material 14b is provided on both the positive electrode side surface and the negative electrode side surface of the separator 15.

[0093] In Examples 8, 10-12, the particle size of the polymerization control material 14b is smaller than the particle size of the positive electrode active material 14a. In Example 9, the particle size of the polymerization control material 14b is larger than the particle size of the positive electrode active material 14a.

[0094] Next, the degree of polymerization and cell resistance of the polymer electrolyte 16 in Examples 1 to 12 and Comparative Examples 1 and 2 will be described. In Figure 8, the degree of polymerization and cell resistance are shown as relative values ​​with Comparative Example 1 set to 100.

[0095] The cell resistance of the secondary battery 10 was measured by placing the battery in a constant temperature bath at 25°C and charging it until the state of charge (SOC) reached 50%, after which AC impedance measurement was performed. The AC impedance measurement was performed with an AC amplitude of 10 mV and a frequency range of 1 MHz to 0.1 Hz. A curve was obtained by fitting the waveform of the arc portion of the Nyquist plot obtained from the AC impedance measurement. The value of the x-axis intercept on the low-frequency side of the obtained curve was defined as the cell resistance.

[0096] Furthermore, the degree of polymerization of the polymer was measured using a Tosoh Corporation HLC-8320 GPC instrument and two Shodex K-G + K-805L columns. The polymer-containing sample was immersed in chloroform solvent to extract the polymer components. After measurement at a concentration of 0.1 wt / vol%, a flow rate of 1.0 mL / min, a temperature of 40°C, and an injection volume of 100 μL, the weight-average molecular weight, calculated from the standard polystyrene calibration curve, was defined as the degree of polymerization.

[0097] In Figure 8, the degree of polymerization of the first region 16a of the polymer electrolyte 16 is a relative value to the degree of polymerization of the second region 16b. In Figure 8, the degree of polymerization of the first region 16a is shown when the degree of polymerization of the second region 16b is set to 100.

[0098] In Comparative Example 1, the degree of polymerization of the first region 16a relative to the second region 16b is 100. In Comparative Example 1, the polymerization control material 14b is not provided in the positive electrode layer 14 corresponding to the first region 16a, and the degree of polymerization of the first region 16a is not reduced relative to the second region 16b.

[0099] In Comparative Example 2, the degree of polymer polymerization of the first region 16a relative to the second region 16b was 103. In Comparative Example 2, the degree of polymer polymerization of the first region 16a is higher than that of the second region 16b. Therefore, in Comparative Example 2, the interfacial resistance between the electrolyte and the positive electrode active material 14a in the first region 16a could not be reduced, and the cell resistance could not be reduced. Furthermore, in Comparative Example 2, the degree of polymer polymerization of the second region 16b is lower than that of the first region 16a. Therefore, in Comparative Example 2, there is a risk of electrolyte leakage in the second region 16b, which reduces the safety of the secondary battery 10.

[0100] In Examples 1 to 12, the degree of polymerization of the first region 16a is less than 100. In other words, in Examples 1 to 12, the degree of polymerization of the first region 16a is lower than that of the second region 16b. As a result, in Examples 1 to 12, the interfacial resistance between the electrolyte and the positive electrode active material 14a in the first region 16a can be reduced, and the cell resistance can be reduced.

[0101] Furthermore, in Examples 4 to 12, which use polymerization control material 14b (LATP, LLNOF) with a relative permittivity of 90 or higher, the degree of polymer polymerization in the first region 16a is 85% or less of that of the second region 16b, and the cell resistance is also low. In particular, in Examples 5 to 12, the weight ratio of polymerization control material 14b to positive electrode active material 14a is 3.0 wt% to 10.0 wt%, and by optimizing the amount of polymerization control material, the degree of polymer polymerization in the first region 16a is 70% or less of that of the second region 16b, and the cell resistance is also sufficiently low. Moreover, in Examples 10 to 12, which use polymerization control material 14b (LLNOF) with a relative permittivity of 200 or higher, the degree of polymer polymerization in the first region 16a is 40% or less of that of the second region 16b, and the cell resistance is also significantly low.

[0102] Furthermore, in Examples 4 to 7, which use the same polymerization control agent 14b (LATP), the higher the content of the polymerization control agent 14b, the greater the effect of lowering the degree of polymer polymerization in the second region 16b, and the greater the effect of lowering cell resistance.

[0103] Similarly, in Examples 10 to 12, which use the same polymerization control agent 14b (LLNOF), the higher the content of the polymerization control agent 14b, the greater the effect of lowering the degree of polymer polymerization in the second region 16b, and the greater the effect of lowering cell resistance.

[0104] Furthermore, in Examples 8 and 9, the same polymerization control material 14b (LATP) was used at the same weight percentage (5.0 wt%). Example 8 (particle size of positive electrode active material 14 > particle size of polymerization inhibitor 14b) was more effective in lowering the degree of polymer polymerization in the second region 16b and thus more effective in lowering cell resistance than Example 9 (particle size of positive electrode active material 14 < particle size of polymerization inhibitor 14b).

[0105] Furthermore, in Comparative Example 2, the degree of polymerization of the second region 16b is lower than that of the first region 16a. Therefore, in Comparative Example 2, there is a risk of electrolyte leakage in the second region 16b, making it less safe than Comparative Example 1. On the other hand, in Examples 1 to 12, the degree of polymerization of the second region 16b is higher than that of the first region 16a. Therefore, in Examples 1 to 12, electrolyte leakage in the second region 16b can be suppressed, resulting in higher safety.

[0106] In the embodiment described above, in a secondary battery 10 equipped with a polymer electrolyte 16, by providing a polymerization control material 14b that suppresses polymer polymerization in the positive electrode layer 14, the degree of polymer polymerization can be controlled at any location where the polymerization control material 14b is provided. As a result, the degree of polymer polymerization of the polymer electrolyte 16 in the positive electrode layer 14 can be lowered, and the interfacial resistance between the positive electrode active material 14a and the electrolyte can be lowered. As a result, the cell resistance of the secondary battery 10 can be lowered, and the output of the secondary battery 10 can be improved.

[0107] Furthermore, in this embodiment, the polymer electrolyte 16 has a first region 16a impregnated in the positive electrode layer 14 and a second region 16b impregnated in the separator 15, and the positive electrode layer 14 is provided with a polymerization control material 14b that suppresses the polymer polymerization reaction of the polymer electrolyte 16. As a result, the degree of polymer polymerization of the first region 16a in the polymer electrolyte 16 can be made lower than that of the second region 16b. As a result, the viscosity of the polymer electrolyte 16 present in the positive electrode layer 14 can be reduced, the contactability between the positive electrode active material 14a and the electrolyte can be improved and the interfacial resistance can be reduced, and the cell resistance of the secondary battery 10 using the polymer electrolyte 16 can be reduced.

[0108] Furthermore, in this embodiment, the polymerization control material 14b is provided in the positive electrode layer 14. In the positive electrode layer 14, the interfacial resistance between the positive electrode active material 14a and the electrolyte tends to be large. By providing the polymerization control material 14b in the positive electrode layer 14, the interfacial resistance between the positive electrode active material 14a and the electrolyte can be reduced, thereby improving the ionic conductivity of the positive electrode layer 14.

[0109] Furthermore, according to this embodiment, by using an inorganic solid electrolyte with a high dielectric constant as the polymerization control material 14b, the effect of suppressing the electrolyte salt from functioning as a polymerization initiator by the polymerization control material 14b can be enhanced.

[0110] Furthermore, according to this embodiment, by making the particle size of the polymerization control material 14b smaller than that of the positive electrode active material 14a, the density of the polymerization control material 14b in the vicinity of the positive electrode active material 14a can be increased. This effectively reduces the degree of polymerization of the polymer electrolyte 16 in the vicinity of the positive electrode active material 14a.

[0111] Furthermore, in this embodiment, a pyrochlore-type solid electrolyte, which is an acid fluoride having a defect structure in at least a portion of its cation sites, is used as the polymerization control material 14b. Such pyrochlore-type solid electrolytes are high dielectric constants, and the effect of suppressing the function of the electrolyte salt as a polymerization initiator by the polymerization control material 14b can be further enhanced.

[0112] Furthermore, in this embodiment, the weight percentage of the polymerization control material 14b in the material constituting the positive electrode layer 14 is set to 2 to 10 wt%, a more desirable weight percentage to 3 to 10 wt%, and an even more desirable weight percentage to 5 to 10 wt%. This provides the effect of reducing the degree of polymerization of the polymer electrolyte 16 by the polymerization control material 14b, and avoids a decrease in ionic conductivity due to an excessive amount of polymerization control material 14b.

[0113] Furthermore, in this embodiment, when LATP or LLNOF with a high dielectric constant are used as the polymerization control material 14b, and the amount of polymerization control material 14b added is optimized, the degree of polymerization of the first region 16a can be reduced to 70% or less of the degree of polymerization of the second region 16b. Optimizing the amount of polymerization control material 14b added can be achieved by, for example, setting the weight ratio of the polymerization control material 14b to the positive electrode active material 14a to 3 wt% or more. This effectively reduces the interfacial resistance between the positive electrode active material 14a and the electrolyte, thereby effectively reducing the cell resistance of the secondary battery 10.

[0114] Furthermore, in this embodiment, the concentration of the electrolyte salt contained in the polymer electrolyte 16 is set to a range of 0.5 to 5 mol / L. This allows the electrolyte salt to function as a polymerization initiator, and prevents an increase in cell resistance due to excess electrolyte salt.

[0115] This disclosure is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit of this disclosure. Furthermore, the means disclosed in each of the embodiments described above may be combined as appropriate to the extent that they are feasible.

[0116] For example, the shape of the secondary battery 10 is not limited to the form described in the above embodiment, and can be used in various forms such as cylindrical, rectangular, or pouch-type (laminated).

[0117] Furthermore, although the above embodiment describes an example in which the polymerization control material 14b is provided in the positive electrode layer 14, the invention is not limited to this, and the polymerization control material 14b may be provided in the negative electrode layer 12, or in both the negative electrode layer 12 and the positive electrode layer 14. When the polymerization control material 14b is provided in the negative electrode layer 12, the first region 16a of the polymer electrolyte 16 becomes the region in which the polymer electrolyte 16 is impregnated in the negative electrode layer 12. When the polymerization control material 14b is provided in both the negative electrode layer 12 and the positive electrode layer 14, the first region 16a of the polymer electrolyte 16 becomes the region in which the polymer electrolyte 16 is impregnated in the negative electrode layer 12 and the region in which it is impregnated in the positive electrode layer 14. When polymerization control material 14b is provided in the negative electrode layer 12, the degree of polymerization of the polymer electrolyte 16 in the negative electrode layer 12 can be lowered, improving the contact between the negative electrode active material 12a and the electrolyte, and reducing the interfacial resistance between the negative electrode active material 12a and the electrolyte.

[0118] Furthermore, in the above embodiment, the polymer electrolyte 16 was configured using an electrolyte solution containing an electrolyte salt and a solvent, but the polymer electrolyte 16 is not limited to this configuration and may be configured without a solvent.

[0119] Furthermore, the secondary battery 10 described in the above embodiment may be configured as a bipolar battery. A bipolar battery has a structure in which multiple battery cells are stacked and connected in series, and adjacent battery cells share a current collector. In other words, the current collector that contacts the positive electrode of one adjacent battery cell contacts the negative electrode of the other adjacent battery cell.

[0120] Furthermore, the secondary battery 10 described in the above embodiment may be configured as an anode-free battery. In an anode-free battery, the negative electrode layer 12 is not formed on the negative electrode current collector 11 in its initial state. During charging, lithium ions move from the positive electrode layer 14, causing lithium metal to deposit on the negative electrode current collector 11 and forming the negative electrode layer 12. The lithium metal constituting the negative electrode layer 12 then moves to the positive electrode layer 14 as lithium ions during discharge.

[0121] Furthermore, the features of the secondary battery disclosed herein are as follows: (Item 1) A secondary battery comprising: a positive electrode layer (14) having a positive electrode active material (14a); a negative electrode layer (12) having a negative electrode active material (12a); a separator (15) sandwiched between the positive electrode layer and the negative electrode layer; and a polymer electrolyte (16) containing a polymer and an electrolyte salt, wherein a polymerization control material (14b) that suppresses the polymerization reaction of the polymer is provided on at least one of the electrode layers of the positive electrode layer or the negative electrode layer; the polymer electrolyte having a first region (16a) present in the electrode layer where the polymerization control material is provided, and a second region (16b) present in the separator, wherein the degree of polymerization of the polymer in the first region is lower than that in the second region. (Item 2) The polymer is polymerized by a polymerization initiator generated from the electrolyte salt, and the polymerization control material suppresses the generation of the polymerization initiator from the electrolyte salt, as described in Item 1. (Item 3) The secondary battery according to Item 1 or 2, wherein the first region is provided in the positive electrode layer. (Item 4) The secondary battery according to any one of Items 1 to 3, wherein the polymerization control material is an inorganic solid electrolyte. (Item 5) The secondary battery according to Item 4, wherein the relative permittivity of the inorganic solid electrolyte is 90 or more. (Item 6) The secondary battery according to Item 4 or 5, wherein the particle size of the inorganic solid electrolyte is smaller than the particle size of the positive electrode active material. (Item 7) The secondary battery according to any one of Items 4 to 6, wherein the inorganic solid electrolyte is an acid fluoride having a defect structure in at least a portion of the cation sites. (Item 8) The secondary battery according to any one of Items 4 to 7, wherein the inorganic solid electrolyte has a pyrochlore structure. (Item 9) The secondary battery according to any one of Items 4 to 8, wherein the weight percentage of the inorganic solid electrolyte in the material constituting the positive electrode layer is in the range of 3 to 10 wt%. (Item 10) The secondary battery according to any one of Items 4 to 9, wherein the degree of polymerization of the polymer in the first region is 70% or less of the degree of polymerization of the polymer in the second region. (Item 11) The secondary battery according to any one of Items 1 to 10, wherein the concentration of the electrolyte salt contained in the polymer electrolyte is in the range of 0.5 to 5 mol / L.(Item 12) A method for manufacturing a secondary battery according to any one of Items 1 to 11, comprising: a coating step (S10) of applying a polymerization control material (14b) that suppresses polymerization of the polymer to at least one surface of the separator; and a lamination step (S11) of laminating the positive electrode layer, the separator, and the negative electrode layer, wherein in the lamination step, the positive electrode layer is laminated on the surface of the separator coated with the polymerization control material. (Item 13) A method for manufacturing a secondary battery according to any one of Items 1 to 11, comprising: a mixing step (S14) of mixing at least the positive electrode active material and a polymerization control material that suppresses polymerization of the polymer to produce the positive electrode layer; and a lamination step (S11) of laminating the positive electrode layer, the negative electrode layer, and the separator. (Item 14) A method for manufacturing a secondary battery according to any one of Items 1 to 11, comprising: a coating step (S15) of coating the surface of the positive electrode active material with a polymerization control material that suppresses polymerization of the polymer; and a lamination step (S11) of laminating the positive electrode layer, the negative electrode layer, and the separator.

[0122] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, while various combinations and forms are shown in this disclosure, other combinations and forms that include one, more, or fewer of those elements also fall within the scope and concept of this disclosure.

Claims

1. A secondary battery comprising: a positive electrode layer (14) having a positive electrode active material (14a); a negative electrode layer (12) having a negative electrode active material (12a); a separator (15) sandwiched between the positive electrode layer and the negative electrode layer; and a polymer electrolyte (16) containing a polymer and an electrolyte salt, wherein a polymerization control material (14b) that suppresses the polymerization reaction of the polymer is provided on at least one of the electrode layers, either the positive electrode layer or the negative electrode layer; the polymer electrolyte having a first region (16a) present in the electrode layer where the polymerization control material is provided, and a second region (16b) present in the separator, wherein the degree of polymerization of the polymer in the first region is lower than that in the second region.

2. The secondary battery according to claim 1, wherein polymerization of the polymer proceeds by a polymerization initiator generated from the electrolyte salt, and the polymerization control material suppresses the generation of the polymerization initiator from the electrolyte salt.

3. The secondary battery according to claim 1, wherein the first region is provided in the positive electrode layer.

4. The secondary battery according to claim 1, wherein the polymerization control material is an inorganic solid electrolyte.

5. The secondary battery according to claim 4, wherein the relative permittivity of the inorganic solid electrolyte is 90 or more.

6. The secondary battery according to claim 4, wherein the particle size of the inorganic solid electrolyte is smaller than the particle size of the positive electrode active material.

7. The secondary battery according to claim 4, wherein the inorganic solid electrolyte is an acid fluoride having a defect structure in at least a portion of the cation sites.

8. The secondary battery according to claim 4, wherein the inorganic solid electrolyte has a pyrochlore structure.

9. The secondary battery according to claim 4, wherein the inorganic solid electrolyte has a weight percentage of 3 to 10 wt% in the material constituting the positive electrode layer.

10. The secondary battery according to claim 4, wherein the degree of polymerization of the polymer in the first region is 70% or less of the degree of polymerization of the polymer in the second region.

11. The secondary battery according to claim 1, wherein the concentration of the electrolyte salt contained in the polymer electrolyte is in the range of 0.5 to 5 mol / L.

12. A method for manufacturing a secondary battery according to any one of claims 1 to 11, comprising: a coating step (S10) of applying a polymerization control material (14b) that suppresses polymerization of the polymer to at least one surface of the separator; and a lamination step (S11) of laminating the positive electrode layer, the separator, and the negative electrode layer, wherein in the lamination step, the positive electrode layer is laminated on the surface of the separator that is covered with the polymerization control material.

13. A method for manufacturing a secondary battery according to any one of claims 1 to 11, comprising: a mixing step (S14) of mixing at least the positive electrode active material with a polymerization control material that suppresses polymerization of the polymer to produce the positive electrode layer; and a lamination step (S11) of laminating the positive electrode layer, the negative electrode layer, and the separator.

14. A method for manufacturing a secondary battery according to any one of claims 1 to 11, comprising: a coating step (S15) of coating the surface of the positive electrode active material with a polymerization control material that suppresses polymerization of the polymer; and a lamination step (S11) of laminating the positive electrode layer, the negative electrode layer, and the separator.

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