Energy storage devices

Abstract

To provide a power storage device arranged so that the short circuit between electrodes can be suppressed.SOLUTION: A power storage device comprises a negative electrode 102, a positive electrode 104, an electrolyte layer 105 provided between the positive electrode 102 and the negative electrode 104, and having a lithium ion-conducting property. In the power storage device, an alloy-forming layer 106 capable of forming an alloy with lithium, and a polymer electrolyte layer 107 having a lithium ion-conducting property are formed on at least a negative electrode-side surface of the electrolyte layer 105. The alloy-forming layer 106 contains metal nitride. The polymer electrolyte layer 106 contains a lithium salt and an ionic liquid of a chain polyether.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a chargeable and dischargeable electricity storage device. [Background technology]

[0002] Lithium-ion batteries, which are known as energy storage devices, are charged and discharged by the movement of lithium ions between a positive electrode and a negative electrode. Repeated charging and discharging of lithium-ion batteries can lead to lithium deposition on the surface of the negative electrode, potentially causing a short circuit between the electrodes. Furthermore, in lithium-ion batteries that use a negative electrode made of metallic lithium and a solid electrolyte layer, the interface between the negative electrode and the solid electrolyte layer acts as a nucleus for lithium deposition, which then grows along the grain boundaries of the solid electrolyte, making them prone to short circuits.

[0003] Patent Document 1 proposes that in a lithium ion battery having a solid electrolyte layer, the solid electrolyte layer be made into two layers in order to suppress short circuits between electrodes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 010043 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional technology only has two solid electrolyte layers in the lithium ion battery, and is not very effective in preventing short circuits between electrodes.

[0006] In view of the above, an object of the present invention is to provide an electricity storage device that can suppress short circuits between electrodes. [Means for solving the problem]

[0007] In order to achieve the above object, claims 1 toThe described energy storage device comprises a negative electrode (102), a positive electrode (104), and an electrolyte layer (105) disposed between the positive and negative electrodes. Lithium ions can move between the negative and positive electrodes. An alloy-forming layer (106) capable of forming an alloy with lithium and a polymer electrolyte layer (107) are formed on at least the negative electrode side of the electrolyte layer. . If The gold layer is placed closer to the electrolyte layer, and the polymer electrolyte layer is placed closer to the negative electrode. The polymer electrolyte layer contains a lithium salt and a chain polyether ionic liquid. 。

[0008] In this way, by providing the alloy-forming layer and the polymer electrolyte layer on at least the negative electrode side surface of the electrolyte layer, a uniform lithium deposition reaction can be generated on the electrode surface, and the occurrence of localized lithium deposition reaction can be suppressed, thereby suppressing the occurrence of short circuits.

[0009] The reference numerals in parentheses for the above components indicate the corresponding relationship with the specific means described in the embodiments to be described later. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of an electricity storage device according to first and second embodiments. [Figure 2] 1 is a table showing the short-circuit current resistance of Examples and Comparative Examples. [Figure 3] 1 is a table showing the ionic conductivities of Examples and Comparative Examples. [Figure 4] FIG. 10 is a cross-sectional view showing the configuration of an electricity storage device according to a third embodiment. [Figure 5] FIG. 10 is a cross-sectional view showing the configuration of an electricity storage device according to a fourth embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing the configuration of an electricity storage device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicated explanations may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination. Of the embodiments described below, the first and second embodiments are embodiments of the present invention, and the third to fifth embodiments are examples shown as reference examples.

[0012] (First embodiment) A first embodiment of the present invention will be described below with reference to the drawings. An electricity storage device 100 of this first embodiment is a secondary battery that can store and use electrical energy, and is a lithium ion battery that is charged and discharged by lithium ions moving between a negative electrode 102 and a positive electrode 104.

[0013] 1, the electricity storage device 100 includes a negative electrode current collector 101, a negative electrode 102, a positive electrode current collector 103, a positive electrode 104, and a solid electrolyte layer 105. The components of the electricity storage device 100, such as the negative electrode current collector 101, are stacked.

[0014] The negative electrode current collector 101 is connected to the negative electrode 102, and the positive electrode current collector 103 is connected to the positive electrode 104. Any material usable as a current collector for a lithium ion battery can be used for the negative electrode current collector 101 and the positive electrode current collector 103. In this embodiment, Cu is used as the negative electrode current collector 101, and Al is used as the positive electrode current collector 103.

[0015] The negative electrode material constituting the negative electrode 102 can be any material that can be used as a negative electrode active material for lithium ion batteries, such as a carbon-based negative electrode material, an oxide-based negative electrode material, a metal-based negative electrode material, etc. In this embodiment, metallic lithium is used as the negative electrode material.

[0016] Any material that can be used as a positive electrode active material for lithium ion batteries can be used as the positive electrode material constituting the positive electrode 104. Examples of materials that can be used as the positive electrode 104 include cobalt-based positive electrode materials (LiCoO2), nickel-based positive electrode materials (LiNiO2), manganese-based positive electrode materials (LiMn2O4), iron phosphate-based positive electrode materials (LiFePO4), and ternary positive electrode materials (NMC) whose main components are nickel, manganese, and cobalt.

[0017] The solid electrolyte layer 105 is made of a solid electrolyte having lithium ion conductivity. Any solid electrolyte that can be used as an electrolyte layer for a lithium ion battery can be used for the solid electrolyte layer 105. For example, an oxide-based solid electrolyte or a sulfide-based solid electrolyte can be used as the solid electrolyte. In this embodiment, the oxide-based solid electrolyte LLZO (Li7La3Zr2O 12 The solid electrolyte layer 105 corresponds to the electrolyte layer of the present invention.

[0018] In the electricity storage device 100, an alloy-forming layer 106 capable of forming a lithium alloy and a polymer electrolyte layer 107 having lithium ion conductivity are provided on the surface of the solid electrolyte layer 105. The alloy-forming layer 106 and the polymer electrolyte layer 107 are provided as buffer layers for suppressing the occurrence of short circuits in the electricity storage device 100. In this embodiment, the alloy-forming layer 106 and the polymer electrolyte layer 107 are provided between the negative electrode 102 and the solid electrolyte layer 105, and between the positive electrode 104 and the solid electrolyte layer 105.

[0019] Since lithium metal is likely to precipitate on the negative electrode side of a lithium ion battery during charge and discharge, it is sufficient that the alloy-forming layer 106 and the polymer electrolyte layer 107 are formed at least on the negative electrode side of the solid electrolyte layer 105. In this embodiment, the alloy-forming layer 106 and the polymer electrolyte layer 107 are provided on both the negative electrode side and the positive electrode side of the solid electrolyte layer 105. The alloy-forming layers 106 provided on the negative electrode side and the positive electrode side have the same configuration, and the polymer electrolyte layers 107 provided on the negative electrode side and the positive electrode side have the same configuration.

[0020] The alloying layer 106 and the polymer electrolyte layer 107 may have a multilayer structure in which each layer is formed separately, or a mixed structure in which each layer is mixed and integrally formed. When the alloying layer 106 and the polymer electrolyte layer 107 have a multilayer structure, the alloying layer 106 may have two or more layers, and the polymer electrolyte layer 107 may have two or more layers. In this embodiment, the alloying layer 106 and the polymer electrolyte layer 107 have a multilayer structure in which one layer each of the alloying layer 106 and the polymer electrolyte layer 107 is formed.

[0021] In this embodiment, of the alloy-forming layer 106 and the polymer electrolyte layer 107, the alloy-forming layer 106 is formed on the side closer to the solid electrolyte layer 105, and the polymer electrolyte layer 107 is formed on the side farther from the solid electrolyte layer 105.

[0022] The positional relationship between the alloy-forming layer 106 and the polymer electrolyte layer 107 is not particularly limited, but in order to maximize the short-circuit suppression effect of each layer, it is desirable that the alloy-forming layer 106 be formed on the side closer to the solid electrolyte layer 105 and the polymer electrolyte layer 107 be formed on the side farther from the solid electrolyte layer 105.

[0023] The alloy-forming layer 106 is a layer capable of forming a lithium alloy and has lithium ion conductivity. The alloy-forming layer 106 interferes with the nucleation of lithium deposition by a lithium alloying reaction.

[0024] The alloy forming layer 106 is made of M X N 1-X (M is a metal element, N is a nitrogen element, and X≦1.0) can be used. Specifically, the alloy-forming layer 106 can be made of metal nitrides such as CuN and TiN, or simple metals such as Ag and Au.

[0025] When a metal nitride is used as the alloy-forming layer 106, lithium and the nitrogen contained in the metal nitride form an alloy, forming LiN. When a metal element is used as the alloy-forming layer 106, the metal element and lithium form an alloy, forming, for example, AgLi. LiN has high ionic conductivity and easily makes the current density uniform, so it has a high short-circuit suppression effect. For this reason, it is desirable to use a metal nitride as the alloy-forming layer 106.

[0026] The alloying layer 106 can be formed by any method, for example, the alloying layer 106 can be formed on the surface of the solid electrolyte layer 105 by atomic layer deposition (ALD) or sputtering.

[0027] The thickness of the alloy forming layer 106 is 600 n It is desirable that the alloy forming layer 106 has a thickness of 600 m or less. n If the thickness of the alloying layer 106 is greater than 200 m, the movement of lithium ions is hindered, and the lithium ion conductivity is reduced. n m or more and It is desirable that the alloy forming layer 106 is 200 n If the thickness is less than m, it becomes difficult to form the alloy-forming layer 106 uniformly on the surface of the solid electrolyte layer 105, and durability is reduced.

[0028] The polymer electrolyte layer 107 has lithium ion conductivity and is mainly composed of an ionic liquid of lithium salt and chain polyether. The chain polyether serves as a solvent. The polymer electrolyte layer 107 is also a low Young's modulus layer.

[0029] Ionic liquids are liquid compounds that are liquid at room temperature and consist only of ions (anions and cations). Ionic liquids have the following properties: they are non-volatile liquids with extremely low vapor pressure and have relatively high ionic conductivity.

[0030] The lithium salt contained in the polymer electrolyte layer 107 can be at least one selected from LiN(SO2F)2, LiFSA, LiFSI, LiTFSI, Li((CF2SO2)2N), and LiBF4. By using these lithium salts, the concentration of lithium salt in the polymer electrolyte layer 107 can be increased.

[0031] The chain polyether contained in polymer electrolyte layer 107 is a polymer having an ether bond (-COC-) in the main chain. Examples of the chain polyether that can be used include DEME (N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium) and glymes. Examples of the glymes that can be used include G3 (tetraglyme) and G4 (triglyme).

[0032] The polymer electrolyte layer 107 can be formed by any method, for example, by applying the mixture of the lithium salt and the chain polyether described above to the surface of the previously formed alloy-forming layer 106.

[0033] By mixing the lithium salt and the chain polyether described above, a solvated ionic liquid is formed in which the chain polyether solvent is coordinated to lithium ions, thereby obtaining a gelled ionic liquid. The higher the concentration of the lithium salt in the polymer electrolyte layer 107, the higher the viscosity of the polymer electrolyte layer 107 can be.

[0034] By using the lithium salt and chain polyether of this embodiment, it is possible to increase the concentration of the lithium salt in the polymer electrolyte layer 107. In this embodiment, the concentration of the lithium salt in the polymer electrolyte layer 107 is set to 3 M (mol / L) or more. While the lithium salt concentration of the electrolyte used in a general lithium ion battery is about 1 to 1.5 M, the lithium salt concentration is increased in the polymer electrolyte layer 107 of this embodiment.

[0035] In the polymer electrolyte layer 107 of this embodiment, by increasing the concentration of lithium salt, it is possible to minimize the amount of free solvent that is not coordinated with lithium ions, thereby improving the electrochemical stability of the polymer electrolyte layer 107 and increasing the ion transport number.

[0036] A solvent such as sulfolane or an ionic liquid such as [EMI][FSI], [EMI][FTI], [EMI][TFSI], or [BMI][TFSI] may be mixed into the polymer electrolyte layer 107. This allows the lithium salt in the polymer electrolyte layer 107 to have a higher concentration.

[0037] Furthermore, additives such as binders or diluents, such as polyvinylidene fluoride (PVDF), may be added to the polymer electrolyte layer 107.

[0038] Here, the results of a short-circuit resistance test performed on the electricity storage device 100 of this embodiment will be described using examples and comparative examples shown in Fig. 2. In Fig. 2, examples 1A to 1C and comparative examples 1A to 1F correspond to this first embodiment. Example 2 corresponds to the second embodiment described later and will be described in the second embodiment.

[0039] In Examples 1A to 1C, electricity storage devices in which an alloy-forming layer 106 and a polymer electrolyte layer 107 are formed are used. In Comparative Examples 1A to 1F, electricity storage devices in which at least one of the alloy-forming layer 106 and the polymer electrolyte layer 107 is not formed are used. In the electricity storage devices of Examples 1A to 1C and Comparative Examples 1A to 1F, metallic lithium is used as the negative electrode 102, and LLZO is used as the solid electrolyte layer 105. The thickness of the solid electrolyte layer 105 is 900 μm.

[0040] In Examples 1A and 1B, the alloy-forming layer 106 was made of 600% Ag. n In Example 1C, the alloy-forming layer 106 was formed by sputtering with TiNx at a thickness of 100 μm. nThe polymer electrolyte layer 107 was formed by ALD to a thickness of 100 μm. In Examples 1A to 1C, a mixture of LiFSI (lithium salt) and G4 (chain polyether) was gelled and used as the polymer electrolyte layer 107. In Examples 1A and 1C, the lithium salt concentration of the polymer electrolyte layer 107 was 4.5 M, and in Example 1B, the lithium salt concentration of the polymer electrolyte layer 107 was 7.0 M.

[0041] In Comparative Example 1A, an electricity storage device in which the alloy-forming layer 106 and the polymer electrolyte layer 107 were not formed was used.

[0042] In Comparative Examples 1B to 1E, an electricity storage device was used in which an alloy-forming layer 106 was formed but no polymer electrolyte layer 107 was formed. In Comparative Example 1B, AlOx was used as the alloy-forming layer 106. n In Comparative Example 1C, the alloy-forming layer 106 was formed by ALD to a thickness of 600 μm. n In Example 1D, the alloy-forming layer 106 was formed by sputtering with TiNx at a thickness of 100 μm. n In Comparative Example 1E, the alloy-forming layer 106 was formed by ALD with a thickness of 300 μm. n The film was formed by ALD to a thickness of 1 m.

[0043] In Comparative Example 1F, an electricity storage device was used in which no alloy-forming layer 106 was formed, but a polymer electrolyte layer 107 was formed. In Comparative Example 1F, a polymer electrolyte gelled by mixing LiFSI (lithium salt) and G4 (chain polyether) was used as the polymer electrolyte layer 107. In Comparative Example 1F, the lithium salt concentration of the polymer electrolyte layer 107 was set to 1.0M.

[0044] In the short-circuit resistance test, the electricity storage devices of the example and comparative example were assembled under a load of 5 kgf using HS cells (sealed bipolar cells) manufactured by Hohsen Co., Ltd. Prior to the short-circuit resistance test, an alternating current was passed through the electricity storage devices of the example and comparative example while they were heated to 60°C to ensure interface stability.

[0045] In the short-circuit resistance test, the electricity storage devices of the examples and comparative examples were charged for 30 minutes at an arbitrary current density and then discharged three times. 2 →0.2mA / cm 2 →0.5mA / cm 2 →1.0mA / cm 2 →1.5mA / cm 2 →2.0mA / cm 2 The current density was increased in the order of ... until a short circuit occurred. The upper limit of the current density at which a short circuit did not occur was defined as the short circuit withstand current.

[0046] As shown in FIG. 2, in Comparative Examples 1A to 1F, the short-circuit withstand current was 0.2 to 1.0 mA / cm 2 In the electricity storage devices of Comparative Examples 1A to 1F, the current density varied, and it is thought that repeated charge and discharge caused localized lithium deposition, resulting in a decrease in short-circuit current resistance.

[0047] As shown in FIG. 2, in Examples 1A to 1C, the short-circuit withstand current was 2.0 to 3.0 mA / cm 2 The electricity storage devices of Examples 1A to 1C in which the alloy-forming layer 106 and the polymer electrolyte layer 107 were formed exhibited a high short-circuit suppression effect.

[0048] In the electricity storage devices of Examples 1A to 1C, the nucleation of lithium deposition was prevented by the lithium alloying reaction in alloy-forming layer 106, and the current density was made uniform by polymer electrolyte layer 107 having high ionic conductivity. This allowed the lithium deposition reaction to occur uniformly during charging and discharging of the electricity storage device, suppressing the occurrence of localized lithium deposition reactions, and improving the short-circuit suppression effect.

[0049] It is believed that the metal nitride or elemental metal that constitutes the alloy-forming layer 106 diffuses into the lithium metal that constitutes the electrode during charge and discharge, forming a mixed ion / electron conductor interface with lithium ion conductivity and electronic conductivity on the lithium metal surface. As a result, it is believed that the lithium deposition reaction can be generated uniformly, improving the short-circuit prevention effect.

[0050] Furthermore, in alloy-forming layer 106, lithium ions are conducted in a direction along the electrode surface due to lithium alloying, and the lithium ions are thought to move uniformly toward the electrode in polymer electrolyte layer 107, which has a high ion transport number. As a result, the lithium deposition reaction can be generated uniformly, which is thought to improve the short-circuit suppression effect.

[0051] In the present embodiment described above, the alloy-forming layer 106 capable of forming a lithium alloy and the polymer electrolyte layer 107 having lithium ion conductivity are provided on the surface of the solid electrolyte layer 105. This allows a uniform lithium deposition reaction to occur on the electrode surface, and suppresses the occurrence of localized lithium deposition reactions, thereby suppressing the occurrence of short circuits.

[0052] Furthermore, the electricity storage device 100 of this embodiment is configured using the negative electrode 102 made of lithium metal and the solid electrolyte layer 105, which makes it prone to short circuits. Therefore, by forming the alloy-forming layer 106 and the polymer electrolyte layer 107 on the surface of the solid electrolyte layer 105, the short circuit suppression effect can be more effectively achieved.

[0053] Furthermore, the alloy-forming layer 106 undergoes volume fluctuations due to an alloying reaction that accompanies charge and discharge. Since the polymer electrolyte layer 107 of this embodiment is a low Young's modulus layer, it can absorb the volume fluctuations of the alloy-forming layer 106. This allows the electricity storage device 100 to be used stably and continuously even when repeatedly charged and discharged.

[0054] In this embodiment, a polymer electrolyte having a lithium salt concentration of 3 M or more is used as the polymer electrolyte layer 107. This can improve the electrochemical stability and the ion transport number.

[0055] Furthermore, since the electricity storage device 100 of this embodiment uses a gel-like polymer electrolyte layer 107, the polymer electrolyte layer 107 is less likely to volatilize. Therefore, the electricity storage device 100 of this embodiment can be suitably used in applications where there are large fluctuations in air pressure, such as eVTOL (electric vertical take-off and landing) aircraft and submarines.

[0056] (Second embodiment) Next, a second embodiment of the present invention will be described, focusing on only the differences from the first embodiment.

[0057] The electricity storage device 100 of the second embodiment has a configuration similar to that of the first embodiment described above with reference to FIG. 1, and includes an anode current collector 101, an anode 102, a cathode current collector 103, a cathode 104, a solid electrolyte layer 105, an alloy-forming layer 106, and a polymer electrolyte layer 107. In the second embodiment, the solvent of the polymer electrolyte constituting the polymer electrolyte layer 107 is different from that of the first embodiment. In the second embodiment, a chain polycarbonate and a cyclic polycarbonate are used as the solvent for the polymer electrolyte. The lithium salt of the polymer electrolyte may be the same material as that of the first embodiment.

[0058] The linear polycarbonate and cyclic polycarbonate are the main components of the polymer electrolyte, accounting for 50% by weight or more of the polymer electrolyte. The polymer electrolyte must contain at least the linear polycarbonate. The polymer electrolyte may also contain additives such as binders and diluents.

[0059] Linear polycarbonates and cyclic polycarbonates can be produced by polymerizing cyclic monomers with a dielectric constant of 80 or higher. Cyclic monomers with a dielectric constant of 80 or higher tend to open during polymerization to produce linear polymers.

[0060] In the second embodiment, vinylene carbonate (VC) is used as a cyclic monomer having a dielectric constant of 80 or more. Therefore, linear polycarbonate and cyclic polycarbonate are obtained as polymers derived from vinylene carbonate. The polymer electrolyte of the second embodiment contains polycarbonate produced by polymerization of vinylene carbonate and decomposition products produced from vinylene carbonate that has not been polymerized. Hereinafter, polymers derived from vinylene carbonate are also referred to as "VC polymers."

[0061] The polymer electrolyte of this second embodiment can be obtained by adding a polymerization initiator to a mixture of lithium salt and vinylene carbonate, followed by heating or ultraviolet irradiation. The polymerization initiator may be any soluble in the solvent, such as azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), or cumene hydroperoxide. Approximately 1 mg of the polymerization initiator may be added per 1 ml of vinylene carbonate.

[0062] When vinylene carbonate is polymerized, a ring-opening reaction of vinylene carbonate occurs, resulting in the production of linear polycarbonate. When vinylene carbonate is polymerized, a portion of the vinylene carbonate does not undergo ring-opening, resulting in the production of cyclic polycarbonate. Therefore, the polymer electrolyte of the second embodiment includes linear polycarbonate and cyclic polycarbonate.

[0063] In the polymer electrolyte of the second embodiment, the chain polycarbonate improves the electrostatic force with the lithium ions, making it possible to increase the concentration of the lithium salt. In the second embodiment, the concentration of the lithium salt in the polymer electrolyte layer 107 is set to 3 M (mol / L) or more.

[0064] Furthermore, the polymer electrolyte of the second embodiment can achieve high ionic conductivity. In general polymer electrolytes, the ionic conductivity in the room temperature range is 10 -5 In contrast, the polymer electrolyte of the second embodiment has an ionic conductivity of 10 -3It is about S / cm.

[0065] The ionic conductivity of the electricity storage device 100 of the second embodiment will now be described with reference to examples and comparative examples shown in Fig. 3. The ionic conductivity in Fig. 3 is a value measured in the room temperature range, and the measured value is shown in logarithm.

[0066] In Examples 2A to 2C, a polymer electrolyte was obtained using LiFSI as the lithium salt and VC polymer as the solvent. In Comparative Example 2A, a polymer electrolyte was obtained using LiClO4 as the lithium salt and polyethylene oxide (PEO) as the solvent. In Comparative Example 2B, a polymer electrolyte was obtained using LiN(CF3CO2)2 as the lithium salt and ethylene oxide (CH2CH2O) as the solvent. n The polymer electrolyte was obtained using

[0067] In Example 2A, the lithium salt concentration was 3 M, in Example 2B, the lithium salt concentration was 7 M, and in Example 2C, the lithium salt concentration was 10 M. In Comparative Examples 2A and 2B, the lithium salt concentration was 1 M. In Examples 2A to 2C, higher lithium salt concentrations were obtained than in Comparative Examples 2A and 2B.

[0068] 3, the ionic conductivity of Comparative Example 2A was -5.2, and the ionic conductivity of Comparative Example 2B was -5.0. In contrast, the ionic conductivity of Example 2A was -4.0, the ionic conductivity of Example 2B was -3.5, and the ionic conductivity of Example 2C was -3.2. The electricity storage devices of Examples 2A to 2C were able to have significantly improved ionic conductivities compared to the electricity storage devices of Comparative Examples 2A and 2B. Furthermore, in the electricity storage devices 100 of Examples 2A to 2C, the higher the lithium salt concentration, the higher the ionic conductivity obtained.

[0069] Next, the results of a short-circuit resistance test performed on the electricity storage device 100 of the second embodiment will be described using Example 2 in Fig. 2. The short-circuit resistance test of Example 2 is the same as the short-circuit resistance test described in the first embodiment using Fig. 2.

[0070] In Example 2, the alloy forming layer 106 was made of 300% Ag. n The polymer electrolyte was formed by sputtering to a thickness of 1.5 m. In Example 2, a mixed solution of LiFSI (lithium salt), vinylene carbonate (solvent), and azobisisobutyronitrile (polymerization initiator) was heated to 60°C to polymerize, thereby obtaining a polymer electrolyte. In Example 2, the lithium salt concentration of the polymer electrolyte was set to 5.0 M. In Example 2, the short-circuit resistance current was 5.0 mA / cm. 2 and higher values ​​were obtained than in Examples 1A to 1C of the first embodiment.

[0071] In the second embodiment described above, the polymer electrolyte layer 107 contains a chain polycarbonate and a cyclic polycarbonate, and the concentration of lithium salt in the polymer electrolyte layer 107 is set to 3M or more. The inclusion of the chain polycarbonate in the polymer electrolyte layer 107 effectively increases the concentration of lithium salt, thereby improving ionic conductivity. This allows a uniform lithium deposition reaction to occur on the electrode surface, and more effectively suppresses the occurrence of short circuits.

[0072] (Third embodiment) Next, a third embodiment of the present invention will be described, focusing only on the differences from the above embodiments.

[0073] 4, the electricity storage device 100 of the third embodiment includes a negative electrode current collector 101, a negative electrode 102, a positive electrode current collector 103, a positive electrode 104, a polymer electrolyte layer 107, and a separator 108. The electricity storage device 100 of the third embodiment does not include a solid electrolyte layer 105 and an alloy-forming layer 106.

[0074] The separator 108 has a porous structure and functions to separate the negative electrode 102 and the positive electrode 104, and also to allow ions to pass through. The separator 108 may be made of, for example, polypropylene, polyethylene, or nonwoven fabric.

[0075] In the third embodiment, similarly to the second embodiment, chain polycarbonate and cyclic polycarbonate are used as the main components of the polymer electrolyte layer 107. Specifically, a VC polymer derived from vinylene carbonate is used.

[0076] 4, for convenience, the separator 108 and the polymer electrolyte layer 107 are shown separately, but in reality, the separator 108 and the polymer electrolyte layer 107 are provided integrally. Specifically, the polymer electrolyte layer 107 is provided by being impregnated into the pores of the separator 108.

[0077] The configuration of the electricity storage device 100 according to the third embodiment described above also makes it possible to generate a uniform lithium deposition reaction on the electrode surface, and to more effectively suppress the occurrence of short circuits.

[0078] In addition, in the third embodiment, the polymer electrolyte layer 107 is provided by impregnating the pores of the separator 108, but this is not limitative, and the polymer electrolyte layer 107 may be provided by applying the polymer electrolyte layer 107 to the surface of the electrode.

[0079] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described, focusing only on the differences from the above embodiments.

[0080] 5, the electricity storage device 100 of the fourth embodiment includes a negative electrode current collector 101, a positive electrode current collector 103, a positive electrode 104, a solid electrolyte layer 105, and a polymer electrolyte layer 107. The electricity storage device 100 of the fourth embodiment does not include a negative electrode 102 and an alloy-forming layer 106.

[0081] In the fourth embodiment, similarly to the second embodiment, chain polycarbonate and cyclic polycarbonate are used as the main components of the polymer electrolyte layer 107. Specifically, a VC polymer derived from vinylene carbonate is used.

[0082] In the fourth embodiment, a polymer electrolyte layer 107 is provided on the negative electrode current collector 101 side of the solid electrolyte layer 105.

[0083] 5, for convenience, the solid electrolyte layer 105 and the polymer electrolyte layer 107 are shown separately, but in reality, the solid electrolyte layer 105 and the polymer electrolyte layer 107 are provided integrally. The solid electrolyte layer 105 is a porous body, and the polymer electrolyte layer 107 is embedded in the pores of the solid electrolyte layer 105 on the negative electrode current collector 101 side.

[0084] The electricity storage device 100 of the fourth embodiment is configured as an anode-free battery in which, in an initial state, the negative electrode 102 is not formed on the negative electrode current collector 101. In an anode-free battery, lithium ions migrate from the positive electrode 104 upon charging to deposit lithium metal on the negative electrode current collector 101, thereby forming the negative electrode 102. The lithium metal that constitutes the negative electrode 102 then migrates to the positive electrode 104 as lithium ions upon discharging.

[0085] The configuration of the electricity storage device 100 according to the fourth embodiment described above also makes it possible to generate a uniform lithium deposition reaction on the electrode surface, and to more effectively suppress the occurrence of short circuits.

[0086] (Fifth embodiment) Next, a fifth embodiment of the present invention will be described, focusing only on the differences from the above embodiments.

[0087] 6, the electricity storage device 100 of the fifth embodiment includes a negative electrode current collector 101, a negative electrode 102, a positive electrode current collector 103, a positive electrode 104, a polymer electrolyte layer 107, and a base film 109. The polymer electrolyte layer 107 is provided so as to cover both sides of the base film 109.

[0088] In the fifth embodiment, similarly to the second embodiment, chain polycarbonate and cyclic polycarbonate are used as the main components of the polymer electrolyte layer 107. Specifically, a VC polymer derived from vinylene carbonate is used.

[0089] The base film 109 is a film-like member. The base film 109 can be formed using at least one of the materials constituting the solid electrolyte layer 105 and the materials constituting the alloy-forming layer 106. The base film 109 can be formed by powdering the materials constituting the solid electrolyte layer 105 and the alloy-forming layer 106 to form a film-like member.

[0090] The configuration of the electricity storage device 100 according to the fifth embodiment described above also makes it possible to generate a uniform lithium deposition reaction on the electrode surface, and to more effectively suppress the occurrence of short circuits.

[0091] (Other embodiments) The present invention is not limited to the above-described embodiments, and various modifications can be made as follows without departing from the spirit of the present invention. Furthermore, the means disclosed in each of the above-described embodiments may be combined as appropriate within the scope of feasibility. [Explanation of symbols]

[0092] 100 Energy storage devices (lithium ion batteries) 102 Negative electrode 104 Positive electrode 105 Solid electrolyte layer (electrolyte layer) 106 Alloy forming layer 107 Polyelectrolyte

Claims

1. The battery comprises a negative electrode (102), a positive electrode (104), and an electrolyte layer (105) disposed between the positive electrode and the negative electrode; Lithium ions can move between the negative electrode and the positive electrode; an alloy-forming layer (106) capable of forming an alloy with lithium and a polymer electrolyte layer (107) are formed on at least the negative electrode side of the electrolyte layer; the alloy-forming layer is disposed closer to the electrolyte layer, and the polymer electrolyte layer is disposed closer to the negative electrode; The polymer electrolyte layer comprises an ionic liquid of a lithium salt and a chain polyether.

2. The electricity storage device according to claim 1 , wherein the alloy-forming layer has a thickness greater than 0 nm and not greater than 600 nm.

3. The electricity storage device according to claim 1 or 2, wherein the alloy-forming layer contains a metal nitride.

4. 4. The electricity storage device according to claim 1, wherein the concentration of the lithium salt in the polymer electrolyte layer is 3M or more.

5. The lithium salt is LiN(SO ２ F) ２ , Li((CF ３ SO ２ ) ２ N) and LiBF ４ The electricity storage device according to claim 1 , wherein the material is at least one selected from the group consisting of:

6. 6. The electricity storage device according to claim 1, wherein the electrolyte layer is made of a solid electrolyte.

7. The electricity storage device according to claim 1 , wherein the negative electrode contains Li metal.

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