Electrode and method of manufacturing energy storage device

Abstract

An electrode includes a current collector, an active material layer formed on a surface of the current collector, and an alkali metal present in a region of the surface of the active material layer that opposes another electrode. The alkali metal is dispersedly distributed in the region. A ratio of a portion of the active material layer covered by the alkali metal in a square of 1 cm on a side set at an arbitrary position in the region is 1% or more and 90% or less at a time when the electrode is just manufactured.

Description

Technical Field

[0001] This disclosure relates to an electrode and a method for manufacturing an energy storage device. Background Technology

[0002] Patent document 1 discloses an electric double-layer capacitor. The electric double-layer capacitor includes a positive electrode and a negative electrode. Both the positive and negative electrodes have a current collector and an active material layer. A lithium metal film is formed on the surface of the active material layer of the negative electrode by thermal spraying. The positive and negative electrodes are contained in a container along with an electrolyte. In the electrolyte, the lithium metal constituting the film is ionized and incorporated into the active material layer of the negative electrode.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-80858 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] The time from the moment the negative electrode comes into contact with the electrolyte until the lithium metal film is completely ionized and doped (hereinafter referred to as the doping time) can sometimes be quite long. In addition, uneven doping can sometimes occur.

[0008] In one aspect of this disclosure, an electrode capable of suppressing doping time and doping inhomogeneity is preferably provided, as well as a method for manufacturing an energy storage device.

[0009] Problem Solving Methods

[0010] One aspect of this disclosure is an electrode comprising: a current collector; an active material layer formed on the surface of the current collector; and an alkali metal present in the surface of the active material layer in a region opposite to other electrodes. The alkali metal is dispersed within the region, in a square with a side length of 1 cm at any location within the region, such that, immediately after the electrode is manufactured, the alkali metal covers more than 1% and less than 90% of the active material layer.

[0011] The electrode, as one embodiment of this disclosure, can suppress doping time and doping inhomogeneity.

[0012] Another aspect of this disclosure is a method for manufacturing an energy storage device, which utilizes electrodes to manufacture the energy storage device. The electrodes comprise: a current collector; an active material layer formed on the surface of the current collector; and an alkali metal present in the surface of the active material layer, in a region opposite to other electrodes. The alkali metal is dispersed within the region, and in a square with a side length of 1 cm set at any location within the region, when the electrode is just manufactured, the percentage of the alkali metal covering the active material layer is more than 1% and less than 90%.

[0013] The method for manufacturing an energy storage device, as another aspect of this disclosure, can suppress doping time and doping inhomogeneity. Attached Figure Description

[0014] Figure 1 This is a side sectional view showing the structure of the negative electrode.

[0015] Figure 2 This is a top view showing the structure of the negative electrode.

[0016] Figure 3 is an explanatory diagram showing the method for measuring coverage.

[0017] Figure 4 This is an explanatory diagram showing the structure of the apparatus for manufacturing the negative electrode.

[0018] Figure 5 This is an explanatory diagram showing the manufacturing method of an energy storage device.

[0019] Explanation of reference numerals in the attached figures

[0020] 1, 1_1~1_19… Negative electrode; 3… Current collector; 5… Negative electrode active material layer;

[0021] 7… Alkali metal; 7A… Particle; 11… Region; 12… Circle; 13… Square;

[0022] 21… Manufacturing apparatus; 23… Unwinding roll; 25… Rewinding roll; 26… Processing chamber;

[0023] 27… Electrode precursor; 31… Roller; 33A, 33B… Spraying unit;

[0024] 35… Melting bath with heater; 37… Nozzle; 39… Spraying material; 41… Energy storage device;

[0025] 43… Electrode unit; 45… Positive electrode; 47… Diaphragm; 49… Housing; 51… Electrolyte Detailed Implementation

[0026] Exemplary embodiments of this disclosure will now be described with reference to the accompanying drawings.

[0027] <First Implementation>

[0028] 1. Structure of negative electrode 1

[0029] Reference Figure 1 and Figure 2 Describe the structure of the negative electrode 1. The negative electrode 1 may have, for example, a long strip-like shape. Figure 1 As shown, the negative electrode 1 includes a current collector 3, a negative electrode active material layer 5, and an alkali metal 7. Furthermore, the negative electrode 1 corresponds to an electrode.

[0030] The current collector 3 has, for example, a long strip shape. Preferably, it is a metal foil such as copper, nickel, or stainless steel. Alternatively, the current collector 3 may have a structure in which a conductive layer primarily composed of carbon material is formed on the metal foil. The thickness of the current collector 3 is, for example, 5 to 50 μm.

[0031] The current collector 3, for example, has through-holes. The through-holes penetrate the current collector 3 along its thickness direction. The current collector 3, for example, has multiple through-holes. When the current collector 3 has through-holes, it is possible to suppress doping time and doping inhomogeneity.

[0032] The negative electrode active material layer 5 is formed, for example, on the main surfaces on both sides of the current collector 3. The negative electrode active material layer 5 can be formed, for example, by coating a slurry containing a negative electrode active material and a binder onto the surface of the current collector 3 and then drying it.

[0033] The negative electrode active material is any electrode active material suitable for use in batteries or capacitors that utilize the insertion and desorption of alkali metal ions, and is not particularly limited thereto. Examples of negative electrode active materials include carbon materials. Examples of carbon materials include graphite, easily graphitized carbon, difficult-to-graphitize carbon, or composite carbon materials formed by coating graphite particles with carbides of pitch or resin. Examples of negative electrode active materials include metals or half-metals such as Si and Sn that can form alloys with lithium, or materials containing oxides of the aforementioned metals or half-metals.

[0034] Specific examples of carbon materials include those described in Japanese Patent Application Publication No. 2013-258392. Specific examples of materials that are metals or semi-metals capable of forming alloys with lithium, or that contain oxides of the aforementioned metals or semi-metals, include those described in Japanese Patent Application Publication Nos. 2005-123175 and 2006-107795.

[0035] Examples of adhesives include rubber adhesives such as styrene-butadiene rubber (SBR) and NBR; fluoropolymers such as polytetrafluoroethylene and polyvinylidene fluoride; polypropylene, polyethylene, and fluorinated (meth)acrylic adhesives such as those disclosed in Japanese Patent Application Publication No. 2009-246137.

[0036] In addition to the negative electrode active material and binder, the slurry may also contain other components. Examples of these other components include conductive agents and thickeners. Examples of conductive agents include carbon black, graphite, vapor-grown carbon fibers, and metal powders. Examples of thickeners include carboxymethyl cellulose, its sodium or ammonium salts, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein.

[0037] The thickness of the negative electrode active material layer 5 is not particularly limited. The thickness of the negative electrode active material layer 5 is, for example, 5 μm or more and 500 μm or less, preferably 10 μm or more and 200 μm or less, and particularly preferably 10 μm or more and 100 μm or less.

[0038] Alkali metal 7 is present in region 11 on the surface of the negative electrode active material layer 5. Region 11 is the portion opposite to the positive electrode 45 when the energy storage device 41 is manufactured using the negative electrode 1. The positive electrode 45 corresponds to other electrodes. Region 11 may be the entire surface of the negative electrode active material layer 5 or only a part of it. Alkali metal 7 may or may not be present in the portion outside region 11.

[0039] Alkali metal 7 is present, for example, on both sides of the negative electrode 1. Figure 2 As shown, alkali metal 7 is dispersed in region 11. Dispersed distribution means that alkali metal 7 is composed of multiple parts, and these multiple parts are in a dispersed state.

[0040] Alkali metal 7 is, for example, a collection of multiple particles 7A. This collection of multiple particles 7A is in a dispersed state. Each particle 7A is separate from each other. Examples of alkali metals 7 include lithium metal and sodium metal.

[0041] like Figure 2 As shown, a square 1cm square 13 is set at any location within region 11. Within square 13, the ratio of alkali metal 7 covering the surface of the negative electrode active material layer 5 (hereinafter referred to as coverage) is between 1% and 90% immediately after the negative electrode 1 is manufactured. "Immediately after the negative electrode 1 is manufactured" means, for example, the moment before the negative electrode 1 comes into contact with the electrolyte 51. The method for measuring coverage is shown below. The measurement is performed in a dry environment with a dew point below -40°C.

[0042] (i) A sample is cut from the newly manufactured negative electrode 1. The sample is square in shape with a side length of 1 cm.

[0043] (ii) Place the cut sample on the stage of the microscope (KEYENCE digital microscope VHX-950F).

[0044] (iii) Set the microscope lens magnification to 200x and adjust the focus. An example of the image captured by the microscope at this time is shown below. Figure 3A As shown. Additionally, although Figure 3A The field of view of the image shown is not a square with a side length of 1cm, but multiple consecutive images are acquired when measuring coverage. The areas of the field of view of these multiple consecutive images are added together, and the sum equals the area of ​​the field of view of a square with a side length of 1cm. The coverage is then measured in these multiple consecutive images.

[0045] (iv) As the measurement mode for the microscope, select "Plane Measurement" and "Area Measurement".

[0046] (v) Set the microscope's brightness range to 20-200 and the brightness tolerance to 20.

[0047] (vi) In the microscope settings, select the "Remove Particles" and "Fill Holes" modes to remove particles from the image. At this stage, a binarized image is displayed on the microscope. Figure 3B An example of a binarized image is shown. Additionally, although... Figure 3B The field of view in the image shown is not a square with sides of 1 cm, but it is treated as a square with sides of 1 cm when measuring coverage. In the binarized image, the black particles are dispersed. The black particles are particles 7A. The areas other than the black particles are those not covered by alkali metal 7.

[0048] (vii) Measure the area S1 of the portion of the binarized image after removing black particles. Save the measurement results file.

[0049] (viii) Adjust the brightness range of the microscope to 0-255 and measure the total area S2 of the binarized image in “Separate Measurement” mode.

[0050] (ix) Calculate the coverage rate (%) according to the following formula (1).

[0051] Formula (1) Coverage rate = (1 - S1 / S2) × 100 (%)

[0052] like Figure 2 As shown, a circle 12 with a radius of 2 mm is set at any position within region 11. Preferably, there is more than one particle 7A inside the circle 12.

[0053] 2. Manufacturing method of negative electrode 1

[0054] Reference Figure 4 This describes the manufacturing method of the negative electrode 1. It can be used... Figure 4 The apparatus 21 shown is used to manufacture the negative electrode 1.

[0055] The manufacturing apparatus 21 includes an unwinding roller 23, a take-up roller 25, and a processing chamber 26. An electrode precursor 27 in the form of a long strip is wound on the unwinding roller 23. The electrode precursor 27 differs from the negative electrode 1 in that it does not contain alkali metal 7, but is otherwise identical. The electrode precursor 27 includes a current collector 3 and a negative electrode active material layer 5.

[0056] The electrode precursor 27, pulled out from the unwinding roller 23, is fed into the processing chamber 26 and conveyed therein. In the processing chamber 26, as described below, the electrode precursor 27 is processed into a negative electrode 1. The resulting negative electrode 1 is then wound onto the take-up roller 25.

[0057] In the processing chamber 26, the moving direction of the electrode precursor 27 and the negative electrode 1 is taken as the conveying direction TR. The manufacturing apparatus 21 includes multiple rollers 31. The multiple rollers 31 guide the electrode precursor 27 in the processing chamber 26.

[0058] Manufacturing apparatus 21 includes a spraying unit 33A. The spraying unit 33A is disposed in processing chamber 26. The spraying unit 33A includes a melting tank 35 with a heater and nozzles 37.

[0059] The molten bath 35 with a heater is capable of holding the spraying material 39. The spraying material 39 is composed of an alkali metal. Examples of alkali metals include lithium metal and sodium metal. The molten bath 35 with a heater is heated by the heater. The spraying material 39 contained in the molten bath 35 with a heater is in a liquid state. For example, the required amount of spraying material 39 can be pre-filled into the molten bath 35 with a heater. Alternatively, the spraying material 39 can be supplied to the molten bath 35 with a heater from the outside.

[0060] The coating material 39 contained in the molten bath 35 with a heater is conveyed to the nozzle 37. The nozzle 37 sprays the liquid coating material 39 onto one side surface of the electrode precursor 27, which moves along the conveying direction TR. The coating material 39 ejected from the nozzle 37 forms an agglomeration of fine droplets and adheres to one side surface of the electrode precursor 27. The agglomeration of fine droplets cools and solidifies on the side surface of the electrode precursor 27, thereby forming an agglomeration of multiple particles 7A.

[0061] The greater the amount of coating material 39 ejected from nozzle 37, the higher the coverage. The slower the delivery speed of electrode precursor 27, the higher the coverage. The smaller the droplet size of the coating material 39 ejected from nozzle 37, the smaller the particle size 7A. The droplet size of the coating material 39 can be controlled by, for example, the shape of nozzle 37, the pressure applied to the coating material 39 in nozzle 37, etc.

[0062] Manufacturing apparatus 21 includes a spraying unit 33B. The spraying unit 33B is disposed in processing chamber 26. The spraying unit 33B has the same structure and function as the spraying unit 33A.

[0063] The nozzle 37 of the spraying unit 33B sprays liquid spraying material 39 onto the surface opposite to the electrode precursor 27, which moves along the transport direction TR. The opposite surface refers to the surface opposite to the surface on which the nozzle 37 of the spraying unit 33A sprays the spraying material 39. On this opposite surface, the collection of fine droplets of the spraying material 39 is cooled and solidified, thereby forming an aggregation of multiple particles 7A.

[0064] The position where the nozzle 37 of the spraying unit 33B sprays the coating material 39 is located downstream of the nozzle 37 of the spraying unit 33A in the conveying direction TR.

[0065] When multiple particles 7A are formed through the spraying unit 33B, the negative electrode 1 is completed. The negative electrode 1 is then wound onto the take-up roller 25.

[0066] 3. Manufacturing method of energy storage device 41

[0067] Reference Figure 5 The manufacturing method of the energy storage device 41 will be described. For example... Figure 5 As shown in C1, electrode unit 43 is fabricated. Electrode unit 43 has a structure formed by alternating layers of negative electrode 1 and positive electrode 45. A diaphragm 47 is disposed between negative electrode 1 and positive electrode 45. An alkali metal 7 is present on the surface of negative electrode 1.

[0068] Next, as Figure 5 As shown in C2, the electrode unit 43 is housed within the housing 49. Then, electrolyte 51 is injected into the housing 49. Inside the housing 49, the electrode unit 43 is in contact with the electrolyte 51. At this time, if the current collector 3 has a through-hole, the electrolyte 51 can penetrate quickly and uniformly; therefore, a through-hole is preferred. After injection, the housing 49 is sealed to complete the assembly of the energy storage device 41. The negative electrode 1 is also in contact with the electrolyte 51. The temperature of the electrolyte 51 inside the housing 49 is maintained, for example, at 60°C.

[0069] After the electrolyte 51 is injected, the alkali metal 7 will gradually ionize and be incorporated into the negative electrode active material layer 5. Ultimately, all of the alkali metal 7 will be incorporated into the negative electrode active material layer 5. Through the above process, the energy storage device 41 is completed.

[0070] The positive electrode 45 has a known structure. The positive electrode 45 includes a positive current collector and a positive active material layer. The current collector of the positive electrode 45 has, for example, the same structure as the current collector 3 of the negative electrode 1. The positive active material layer contains a positive active material. Examples of positive active materials include activated carbon used in capacitors; transition metal oxides such as cobalt oxide, nickel oxide, manganese oxide, and vanadium oxide used in lithium-ion batteries; multi-anion materials such as iron phosphate; and sulfur-based active materials such as elemental sulfur and metal sulfides.

[0071] The material of the diaphragm 47 can be, for example, polyethylene nonwoven fabric. The thickness of the diaphragm 47 is, for example, about 50 μm.

[0072] The electrolyte 51 contains alkali metal ions and a solvent. Alkali metal ions are ions that constitute alkali metal salts. The alkali metal salt is preferably a lithium salt or a sodium salt, more preferably a lithium salt.

[0073] As anionic moiety constituting alkali metal salts, for example, PF6 - PF3 (C2F5)3 - PF3 (CF3) 3 - Phosphine anions with fluorine groups; BF4 － BF2(CF)2 － BF3 (CF3) － B(CN)4 － Boron anions containing fluorine or cyanide groups; N(FSO2)2 － N(CF3SO2)2 － N(C2F5SO2)2 － Sulfonamide anions with fluorine groups; CF3SO3 － Organic sulfonic acid anions with fluorine groups, etc.

[0074] Examples of lithium salts include LiClO4, LiAsF6, LiBF4, LiPF6, LiN(FSO2)2, LiN(C2F5SO2)2, and LiN(CF3SO2)2.

[0075] The concentration of alkali metal salt in electrolyte 51 is preferably 0.1 mol / L or more, and more preferably in the range of 0.5 to 1.5 mol / L.

[0076] The solvent used in the electrolyte 51 may be one or more selected from the group consisting of carbonate solvents, ester solvents, ether solvents, hydrocarbon solvents, nitrile solvents, sulfur-containing solvents, and amide solvents.

[0077] Examples of carbonate solvents include ethylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl ethyl carbonate, ethyl methyl carbonate, propylene carbonate, and butene carbonate.

[0078] Examples of ester solvents include butyl acetate, amyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl 3-ethoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, butyl formate, propyl formate, ethyl lactate, butyl lactate, propyl lactate, γ-butyrolactone, valerate, mevalonate lactone, caprolactone, etc.

[0079] Examples of ether solvents include diethyl ether, isopropyl ether, n-butyl ether, n-hexyl ether, 2-ethylhexyl ether, ethylene oxide, 1,2-epoxypropane, 1,3-dioxopentane, 4-methyl-1,3-dioxopentane, dioxane, dimethyldioxane, tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, etc.

[0080] Examples of hydrocarbon solvents include n-pentane, isopentane, n-hexane, isohexane, n-heptane, isoheptane, 2,2,4-trimethylpentane, n-octane, isooctane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, isopropylbenzene, diethylbenzene, isobutylbenzene, triethylbenzene, diisopropylbenzene, n-pentylnaphthalene, and trimethylbenzene.

[0081] Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, 4-heptanone, 2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, acetone, and methyl isobutyl ketone.

[0082] Examples of nitrile solvents include acetonitrile and propionitrile. Examples of sulfur-containing solvents include sulfolane and dimethyl sulfoxide. Examples of amide solvents include dimethylacetamide, dimethylformamide, and N-methylpyrrolidone.

[0083] Solvents can consist of a single component or be a mixture of two or more components.

[0084] Electrolyte 51 may also contain additives such as vinylene carbonate, ethylene ethylene carbonate, fluoroethylene carbonate, 1-(trifluoromethyl)ethylene carbonate, succinic anhydride, maleic anhydride, propane sulpholactone, and diethyl sulfone.

[0085] The electrolyte 51 may further contain flame retardants such as phosphazene compounds. The amount of flame retardant added relative to 100 parts by weight of the electrolyte 51 is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and even more preferably 5 parts by weight or more. Furthermore, the amount of flame retardant added relative to 100 parts by weight of the electrolyte 51 is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and even more preferably 10 parts by weight or less.

[0086] Examples of energy storage devices 41 include batteries and capacitors. Examples of batteries include lithium-ion rechargeable batteries. Examples of capacitors include lithium-ion capacitors.

[0087] 4. Effects achieved by the manufacturing method of the negative electrode 1 and the energy storage device 41

[0088] (1A) In the negative electrode 1, the coverage is more than 1% and less than 90%. When the negative electrode 1 is used to manufacture the energy storage device 41, the doping time is relatively short. The doping time refers to the time from the moment the electrolyte 51 is injected into the housing 49 containing the negative electrode 1 during the manufacture of the energy storage device 41 until the moment when all the alkali metals 7 are completely ionized and doped into the negative electrode active material layer 5.

[0089] The reason for the shorter doping time can be speculated as follows: Since the coverage is below 90%, the distance between particles 7A is unlikely to become excessively small. Therefore, it is unlikely that undoped particles 7A will remain. Consequently, the doping time can be shortened.

[0090] (1B) When the negative electrode 1 is used to manufacture the energy storage device 41, doping inhomogeneity can be suppressed. Doping inhomogeneity refers to the phenomenon that the degree of predoping at different positions in the negative electrode active material layer 5 is different.

[0091] The reason why doping inhomogeneity can be suppressed can be speculated as follows: Since the coverage is above 1%, it is unlikely that there will be positions where the distance between particles 7A is too large. Therefore, it is unlikely that there will be positions where the pre-doping degree is too low. Thus, doping inhomogeneity is suppressed.

[0092] (1C) In the negative electrode 1, for example, there is one or more particles 7A inside a circle 12 with a radius of 2 mm set at any position within region 11. In this case, it is less likely that positions where the distance between particles 7A is too large will appear. Therefore, it is possible to further suppress doping inhomogeneity.

[0093] (1D) To suppress doping inhomogeneity, it is preferable that the current collector 3 has a through-hole. The reason for this can be inferred as follows: When the current collector 3 has a through-hole, the electrolyte 51 can flow back and forth between the front and back sides of the current collector 3, allowing lithium ions to move and diffuse between the two sides. For example, when the amount of lithium ions on the surface is insufficient, lithium ions will be supplied from the back side, thereby further suppressing doping inhomogeneity.

[0094] <Example>

[0095] 1. Manufacturing of negative electrodes 1_1 to 1_19

[0096] The negative electrodes 1_1 to 1_19 shown in Table 1 were manufactured. The manufacturing process used... Figure 4 Manufacturing apparatus 21 shown.

[0097] [Table 1]

[0098] １＿１ 0.05 S E E １＿２ 0.5 S E E １＿３ 1 A D D １＿４ 2 A C C １＿５ 3 A B B １＿６ 4 A A A １＿７ 5 A S S １＿８ 6 A A A １＿９ 7 A S S １＿１０ 8 A A A １＿１１ 9 A S S １＿１２ 10 A B B １＿１３ 30 A A A １＿１４ 60 A S S １＿１５ 70 B C B １＿１６ 80 C B B １＿１７ 90 D D D １＿１８ 95 E C E １＿１９ 100 E C E

[0099] (i) Common features of negative electrodes 1_1 to 1_19

[0100] Negative electrodes 1_1 to 1_19 share the following characteristics. Negative electrodes 1_1 to 1_19 have... Figure 1 , Figure 2 The structure is shown. The current collector 3 is a copper foil. The thickness of the current collector 3 is 20 μm. The negative electrode active material layer 5 is formed on both sides of the main surface of the current collector 3.

[0101] The negative electrode active material layer 5 contains graphite as the negative electrode active material. The binder in the negative electrode active material layer 5 is styrene-butadiene rubber (SBR). The thickness of the negative electrode active material layer 5 is 50 μm. Alkali metal 7 is dispersed within region 11. Alkali metal 7 is lithium metal. Alkali metal 7 is an aggregate of multiple particles 7A.

[0102] (ii) Differences between negative electrodes 1_1 to 1_19

[0103] The coverage of negative electrodes 1_1 to 1_19 is shown in Table 1. In negative electrodes 1_1 to 1_19, more than one particle 7A exists inside a circle 12 with a radius of 2 mm set at any position within region 11 of negative electrodes 5 to 11, 14 to 16, 18, and 19. In negative electrodes 1_1 to 1_19, less than one particle 7A exists inside a circle 12 with a radius of 2 mm set at any position within region 11 of negative electrodes 1 to 4, 12, 13, and 17. Furthermore, in negative electrodes 1_1 to 1_19, the current collector 3 of negative electrodes 7, 9, 11, 13, 14, and 16 has a through hole. In negative electrodes 1_1 to 1_19, the current collector 3 of negative electrodes 1 to 6, 8, 10, 12, 15, and 17 to 19 does not have a through hole.

[0104] 2. Evaluation of negative electrodes 1_1 to 1_19

[0105] The doping time was measured for the negative electrodes 1_1 to 1_19. The evaluation results of the doping time are shown in Table 1. S represents the shortest doping time. As the doping time increases, the evaluation results change sequentially to A, B, C, D, and E. E represents the longest doping time.

[0106] The doping inhomogeneity of negative electrodes 1_1 to 1_19 was evaluated. The evaluation method involved measuring the potential within a 1cm square and comparing the potential differences within the electrode surface. The evaluation results for doping inhomogeneity are shown in Table 1. S indicates the least doping inhomogeneity. As doping inhomogeneity becomes more significant, the evaluation results change sequentially to A, B, C, D, and E. E indicates the most significant doping inhomogeneity.

[0107] Table 1 shows the results of the comprehensive assessment. S indicates the best comprehensive assessment result. As the comprehensive assessment result worsens, the evaluation results change sequentially to A, B, C, D, and E. E indicates the worst comprehensive assessment result.

[0108] The overall judgment is based on the evaluation results of the doping time and the evaluation results of the doping inhomogeneity.

[0109] When the coverage is above 1% and below 90%, the evaluation results for both doping time and doping inhomogeneity are both D or higher. When the coverage is above 2% and below 80%, the evaluation results for both doping time and doping inhomogeneity are both C or higher.

[0110] When the coverage is above 3% and below 70%, both the evaluation results for doping time and the evaluation results for doping inhomogeneity reach level B or above. When the coverage is above 4% and below 60%, both the evaluation results for doping time and the evaluation results for doping inhomogeneity reach level A.

[0111] <Other Implementation Methods>

[0112] The embodiments of this disclosure have been described above, but this disclosure is not limited to the above embodiments and can be implemented in various modifications.

[0113] (1) A positive electrode 45 having the same alkali metal 7 as the negative electrode 1 in the first embodiment can be manufactured. Alternatively, the energy storage device 41 can also be manufactured using the positive electrode 45 having the alkali metal 7. In addition, the other electrodes are the negative electrode 1, which is the same as the positive electrode 45.

[0114] (2) The functions of one constituent element in the above embodiments can be distributed among multiple constituent elements, or the functions of multiple constituent elements can be integrated into one constituent element. Furthermore, a portion of the configuration of the above embodiments can be omitted. Additionally, at least a portion of the configuration of the above embodiments can be added to the configurations of the other embodiments, or at least a portion of the configuration of the above embodiments can be replaced with the configurations of the other embodiments.

[0115] (3) In addition to the electrodes and energy storage devices mentioned above, this disclosure can also be realized in various forms, such as: an element having electrodes, a system having energy storage devices, a method for manufacturing electrodes, a method for manufacturing energy storage devices, an apparatus for manufacturing electrodes, etc.

Claims

1. An electrode, characterized in that, have: Current collector; An active material layer is formed on the surface of the current collector; and An alkali metal, wherein the alkali metal is present on the surface of the active material layer, in the region opposite to the other electrodes. The alkali metal is dispersed in the region. In a square with a side length of 1 cm set at any location within the region, when the electrode is just manufactured, the percentage of the portion of the active material layer covered by the alkali metal is more than 1% and less than 90%.

2. The electrode according to claim 1, characterized in that, One or more alkali metal particles are present inside a circle with a radius of 2 mm set at any location within the region.

3. The electrode according to claim 1 or 2, characterized in that, The current collector has a through hole.

4. A method for manufacturing an energy storage device, wherein the energy storage device is manufactured using electrodes, the method being characterized in that... The electrode has the following features: Current collector; An active material layer is formed on the surface of the current collector; and An alkali metal, wherein the alkali metal is present on the surface of the active material layer, in the region opposite to the other electrodes. The alkali metal is dispersed in the region. In a square with a side length of 1 cm set at any location within the region, when the electrode is just manufactured, the percentage of the portion of the active material layer covered by the alkali metal is more than 1% and less than 90%.

Images