Electrode, battery, and method for manufacturing an electrode

Abstract

Improved rate characteristics. [Solution] An electrode comprising a current collector foil and a positive electrode layer, wherein the positive electrode layer is disposed on the surface of the current collector foil, the positive electrode layer comprises a positive electrode active material, the positive electrode active material comprises a plurality of secondary particles, each of the plurality of secondary particles comprises a plurality of primary particles, the secondary particles comprises porous particles having voids, the cross-section of the positive electrode layer comprises a first region and a second region, the first region and the second region are divided by the cross-section of the positive electrode layer being divided into two equal parts in the thickness direction, the first region is disposed between the current collector foil and the second region, the relationship 50% ≤ X is satisfied, where X represents the ratio of porous particles contained in the first region to the porous particles contained in the first region and the second region, and X is calculated for porous particles having a maximum Ferret diameter of 5 μm or more.

Description

[Technical Field]

[0001] This disclosure relates to electrodes, batteries, and methods for manufacturing electrodes. [Background technology]

[0002] International Publication No. 2020 / 261879 (Patent Document 1) discloses a positive electrode active material comprising lithium iron manganese phosphate (LMFP) and a high-nickel layered oxide, wherein the average particle size of the secondary particles of the LMFP is 3 nm or more and 20 nm or less. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2020 / 261879 [Overview of the project] [Problems that the invention aims to solve]

[0004] Various types of positive electrode active materials have been developed to improve battery characteristics. Patent Document 1 provides a positive electrode (battery) that achieves both energy density and safety by mixing a high-nickel layered oxide, which has excellent energy density, with LMFP, which has excellent safety. However, there is still room for improvement in rate characteristics.

[0005] The purpose of this disclosure is to improve rate characteristics. [Means for solving the problem]

[0006] The technical configuration and effects of this disclosure are described below. However, the mechanism of action of this disclosure includes assumptions. The mechanism of action does not limit the technical scope of this disclosure.

[0007] [1] comprising current collector foil and positive electrode layer, The positive electrode layer is arranged on the surface of the current collector foil, The positive electrode layer contains a positive electrode active material, The positive electrode active material includes a plurality of secondary particles, Each of the plurality of secondary particles includes a plurality of primary particles, The secondary particles include porous particles having voids, The cross-section of the positive electrode layer includes a first region and a second region. The first region and the second region are separated by dividing the cross-section of the positive electrode layer into two equal parts in the thickness direction. The first region is located between the current collector foil and the second region, The relationship 50% ≤ X is satisfied, The above X represents the ratio of the porous particles contained in the first region to the porous particles contained in the first and second regions, In the porous particles having a maximum Ferret diameter of 5 μm or more, X is calculated. electrode.

[0008] The secondary particles include porous particles that have voids. Electrodes containing such porous particles are expected to show improved rate characteristics compared to electrodes with higher density. The cross-section of the positive electrode layer includes a first region and a second region. The first region can be rephrased as "deep part" or "deep layer." The first region is located relatively closer to the current collector foil compared to the second region. The second region can be rephrased as "shallow part" or "surface layer." Since the relationship 50% ≤ X is satisfied, electron paths and ion paths are efficiently formed, and thus an improvement in rate characteristics is expected.

[0009] [2] The relationship 60% ≤ X is satisfied, The electrode described in [1].

[0010] The relationship 60% ≤ X is satisfied, which is expected to lead to further improvements in rate characteristics.

[0011] [3] The porous particles include open porous particles in which the pores are open to the outside, The relationship 40% ≤ Y ≤ 95% is satisfied. Y represents the ratio of open-pore particles to the void particles, In the porous particles having a maximum Ferret diameter of 5 μm or more, Y is calculated. The electrode described in [1] or [2].

[0012] Porous particles include open-pore particles, which have open pores that lead to the outside, and closed-pore particles (hollow particles), which have pores that do not lead to the outside. Here, if the electrode has many pores, the electrode active material and electrolyte may react, potentially generating gas. This can occur when closed-pore particles are present in a certain proportion. Therefore, a reduction in gas generation is expected when the relationship 40% ≤ Y ≤ 95% is satisfied.

[0013] [4] The relationship 60% ≤ Y ≤ 80% is satisfied, The electrode described in [3].

[0014] A reduction in gas emissions can be expected if the relationship 60% ≤ Y ≤ 80% is satisfied.

[0015] [5] Each of the plurality of primary particles contains an olivine-type phosphate compound, An electrode as described in any of [1] to [4].

[0016] [6] The olivine-type phosphate compound is lithium iron manganese phosphate. The electrode described in [5].

[0017] [7] The electrode includes one of the electrodes described in any of [1] to 6] battery.

[0018] [8] Having a bipolar structure, The battery described in [7].

[0019] [9] (a) Prepare the positive electrode active material, (b) Contacting at least a portion of the positive electrode active material with the first solvent, (c) Mixing the positive electrode active material after contact with the first solvent with the second solvent to form a slurry. (d) Applying the slurry to the surface of the current collector foil, (e) Forming a positive electrode layer by drying the slurry, The positive electrode active material includes a plurality of secondary particles, The secondary particles include porous particles having voids, The first solvent has a higher boiling point compared to the second solvent. A method for manufacturing electrodes.

[0020] It is expected that the electrode described in [1] above will be manufactured by going through the manufacturing process described in [9] above.

[0021]

[10] In (c) above, the positive electrode active material after contact with the first solvent and the positive electrode active material that has not been contacted with the first solvent are weighed in a mass ratio of 1:0 to 1:2 and mixed with the second solvent. [9] The method for manufacturing electrodes as described above.

[0022]

[11] The first solvent comprises N-methyl-2-pyrrolidone, The second solvent contains water. The method for manufacturing an electrode as described in [9] or

[10] .

[0023] Hereinafter, one embodiment of the present disclosure (which may be abbreviated as "this embodiment") and one example of the present disclosure (which may be abbreviated as "this example") will be described. However, this embodiment and this example will not limit the technical scope of the present disclosure. This embodiment and this example are illustrative in all respects. This embodiment and this example are not restrictive. The technical scope of the present disclosure includes all modifications within the meaning and scope equivalent to the description of the claims. For example, it is intended from the outset that any configuration may be extracted from this embodiment and combined in any way. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic cross-sectional view showing the electrodes in this embodiment. [Figure 2] This is a conceptual diagram showing secondary particles in this embodiment. [Figure 3] This is a schematic flowchart illustrating the method for manufacturing electrodes in this embodiment. [Figure 4] This is a schematic perspective view of the battery in this embodiment. [Figure 5] This is a schematic cross-sectional view along the line VI-VI in Figure 4. [Figure 6] This table shows the manufacturing conditions and experimental results for the positive electrode in the example. [Figure 7] This is the temperature profile during firing. [Modes for carrying out the invention]

[0025] <Terms and phrases> "Equipped with," "includes," "possesses," and variations thereof are open-ended expressions. Configurations expressed in an open-ended manner may or may not include additional elements in addition to the essential elements. The statement "consists of" is a closed expression. However, even configurations expressed in a closed manner may include additional elements that are usually incidental impurities or irrelevant to the subject technology. The statement "substantially consists of..." is a semi-closed expression. In configurations expressed in a semi-closed manner, the addition of elements that do not substantially affect the basic and novel characteristics of the subject technology is permitted.

[0026] Expressions such as "may do" and "may be" are used in a permissive sense, meaning "there is a possibility," rather than in an obligatory sense, meaning "it must be done."

[0027] Unless otherwise specified, the order in which the various steps, actions, and operations included in each method are executed is not limited to the order in which they are described. For example, multiple steps may occur simultaneously. For example, multiple steps may occur one after the other.

[0028] Expressions such as "first," "second," etc., are used solely to distinguish between multiple elements. These expressions do not limit the elements to which they are attached. They are unrelated, for example, to the order or importance of the elements to which they are attached.

[0029] For example, the expression "at least one of A and B" includes both "A or B" and "A and B". "At least one of A and B" can also be written as "A and / or B".

[0030] Geometric terms should not be interpreted strictly. Examples of geometric terms include "parallel," "perpendicular," and "orthogonal." For example, direction, angle, distance, etc., may be relatively distorted within a range where substantially the same or similar function is obtained. Geometric terms may include tolerances, errors, etc., in design, operation, and manufacturing. Dimensional relationships in each figure may not match actual dimensional relationships. Dimensional relationships in each figure may be modified to aid the reader's understanding. For example, length, width, thickness, etc., may be changed. Some components may be omitted.

[0031] Elements described in the singular form may also include plural forms unless otherwise specified. For example, "particle" may refer to multiple particles, a collection of particles, or a granular material.

[0032] Numerical ranges such as "m~n%" include upper and lower limits unless otherwise specified. That is, "m~n%" indicates a numerical range of "m% or more and n% or less". Also, "m% or more and n% or less" includes "greater than m% and less than n%". "Greater than or equal to" and "less than or equal to" are represented by the equals sign inequality signs "≦" and "≧". "Greater than" and "less than" are represented by the equals sign inequality signs "<" and ">". A number arbitrarily selected from within the numerical range may be used as a new upper or lower limit. For example, a new numerical range may be set by arbitrarily combining a number within the numerical range with a number listed in another part of this specification, in a table, in a figure, etc.

[0033] All numerical values ​​are modified by the term "approximately." The term "approximately" can mean, for example, ±5%, ±3%, ±1%, etc. All numerical values ​​may be approximations that can vary depending on the application of the technology in question. All numerical values ​​may be expressed with significant figures. Unless otherwise specified, measured values ​​may be the average of multiple measurements. The number of measurements may be three or more, five or more, or ten or more. Generally, the more measurements taken, the more reliable the average value is expected to be. Measured values ​​may be rounded to the nearest significant figure. Measured values ​​may include errors such as those associated with the detection limits of the measuring device.

[0034] The devices, software, etc., used to measure various values ​​are merely examples. Equivalent devices may be used. If equivalent devices are used, the measurement conditions may be adjusted to suit the device.

[0035] The ratio of vacant particles in the first region to vacant particles in the second region (X), and the ratio of open-pore particles to vacant particles (Y) are measured by the following procedure: The electrode is cut at an arbitrary position. This allows a cross-sectional sample of the positive electrode layer to be taken. The electrode may be a monopolar electrode (positive electrode) or a bipolar electrode, as long as it includes the positive electrode layer. The cross-sectional sample is subjected to, for example, ion milling. The cross-sectional sample is observed using a scanning electron microscope (SEM). The observation magnification may be adjusted, for example, within the range of 5000 to 15000 times (e.g., 10000 times). In multiple fields of view (e.g., about 5 fields of view), vacant particles in the first and second regions, vacant particles in the first region, and open-pore particles in the first and second regions are counted. Among the vacant particles and open-pore particles, those with a maximum Ferret diameter of 5 μm or more are counted. "X" is obtained by dividing the number of porous particles in the first region by the total number of porous particles in the first and second regions combined. "Y" is obtained by dividing the number of open porous particles in the first and second regions by the total number of porous particles in the first and second regions combined.

[0036] The "maximum Ferret diameter" of a particle indicates the length of the longer side of the circumscribing rectangle (rectangle or square) of the particle. If the circumscribing rectangle is a square, the length of the longer side indicates the length of one side. The maximum Ferret diameter of secondary particles can be measured in the SEM images described above. The maximum Ferret diameter of primary particles can be measured, for example, in transmission electron microscopy (TEM) images.

[0037] "D50" indicates the particle size at which the cumulative value in the volume-based particle size distribution (cumulative distribution) reaches 50%. The volume-based particle size distribution is measured using a laser diffraction particle size analyzer.

[0038] The stoichiometric composition formula shows a representative example of a compound. The compound may have a non-stoichiometric composition. For example, "Al2O3" is not limited to compounds with a molar ratio of "Al / O = 2 / 3". Unless otherwise specified, "Al2O3" refers to a compound containing Al and O in any molar ratio. For example, the compound may be doped with trace elements. Some of the Al and O may be substituted with other elements.

[0039] The chemical composition of a compound can be measured by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy). A sample solution is prepared by dissolving 0.1 g of the sample (e.g., positive electrode active material) in a mixed acid (10 ml) of hydrochloric acid and sulfuric acid. The sample solution is diluted to an appropriate concentration in a volumetric flask. After dilution, compositional analysis is performed using an ICP-AES instrument. For example, a product name such as "PS3520 UVDD II (manufactured by Hitachi High-Tech Science Corporation)" may be used.

[0040] A "derivative" refers to a compound in which a part of the parent compound has been modified by at least one of the following chemical reactions: introduction of a functional group, substitution of atoms, oxidation, reduction, and other chemical reactions. The modification may be at one location or multiple locations. The "substituents" may include at least one selected from the group consisting of, for example, alkyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, unsaturated cycloalkyl groups, aromatic groups, heterocyclic groups, halogen atoms (F, Cl, Br, I, etc.), OH groups, SH groups, CN groups, SCN groups, OCN groups, nitro groups, alkoxy groups, unsaturated alkoxy groups, amino groups, alkylamino groups, dialkylamino groups, aryloxy groups, acyl groups, alkoxycarbonyl groups, acyloxy groups, aryloxycarbonyl groups, acylamino groups, alkoxycarbonylamino groups, aryloxycarbonylamino groups, sulfonylamino groups, sulfamoyl groups, carbamoyl groups, alkylthio groups, arylthio groups, sulfonyl groups, sulfinyl groups, ureido groups, phosphate amide groups, sulfo groups, carboxyl groups, hydroxamic acid groups, sulfino groups, hydrazino groups, imino groups, and silyl groups. These substituents may be further substituted. If there are two or more substituents, the substituents may be the same or different. Multiple substituents may be bonded to each other to form a ring.

[0041] <Electrode> Figure 1 is a schematic cross-sectional view showing the electrode in this embodiment. The electrode 110 may be, for example, the positive electrode of a monopolar battery. The cross-section in Figure 1 is parallel to the thickness direction (Z direction) of the electrode 110. The electrode 110 includes a current collector foil 113 and a positive electrode layer 11.

[0042] The current collector foil 113 is a conductor. The current collector foil 113 supports the positive electrode layer 11. The current collector foil 113 may be, for example, in the form of a sheet. The thickness of the current collector foil 113 may be, for example, 1 to 50 μm, 3 to 30 μm, or 5 to 15 μm. The current collector foil 113 is conductive. The current collector foil 113 may contain, for example, a metal foil. The current collector foil 113 may contain, for example, at least one selected from the group consisting of Cu, Ni, Zn, Pb, Al, Ti, Fe, Ag, Au, and conductive resins. The current collector foil 113 may contain, for example, an Al foil, an Al alloy foil, etc. The current collector foil 113 may have, for example, a multilayer structure. For example, the current collector foil 113 may be formed by laminating an Al foil and a Cu foil.

[0043] The positive electrode layer 11 is located on the surface of the current collector foil 113. The positive electrode layer 11 may be located on only one side of the current collector foil 113. The positive electrode layer 11 may be located on both sides of the current collector foil 113. If the electrode 110 is a bipolar battery, the positive electrode layer 11 may be located on one side (front side) of the current collector foil 113, and the negative electrode layer (not shown) may be located on the other side (back side). For example, grooves may be formed in the positive electrode layer 11. The positive electrode layer 11 may be formed in a stripe pattern, for example. The thickness of the positive electrode layer 11 may be, for example, 10 μm or more, 100 μm or more, 200 μm or more, 400 μm or more, 600 μm or more, 800 μm or more, or 1 mm or more. The thickness of the positive electrode layer 11 may be, for example, 1.2 mm or less, 1 mm or less, or 800 μm or less. In bipolar structures, a thick cathode layer 11 of 200 μm or more may be required.

[0044] The positive electrode layer 11 contains a positive electrode active material. That is, the electrode 110 contains a positive electrode active material.

[0045] Figure 2 is a conceptual diagram showing secondary particles in this embodiment. The positive electrode active material contains a plurality of secondary particles 2. The secondary particles 2 are aggregates of primary particles 1. That is, the secondary particles 2 contain a plurality of primary particles 1. The secondary particles 2 include porous particles 2c having voids 3 and non-porous particles 2d not having voids 3. The porous particles 2c include open-pore particles 2a having open pores 3a that lead to the outside, and closed-pore particles 2b (hollow particles) whose voids 3 do not lead to the outside. The voids in closed-pore particles 2b are also called voids 3b. In the SEM image, the non-porous particles 2d may also have voids 3 in positions that are not visible in the SEM image. However, in this embodiment, the presence or absence of voids 3 is determined solely by their appearance in the SEM image.

[0046] In the 30 secondary particles 2, the average value of the maximum Ferret diameter may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more. The average value of the maximum Ferret diameter may be, for example, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less.

[0047] The secondary particle 2 may have a spherical shape. The spherical shape of the secondary particle 2 is expected to improve, for example, packing efficiency. The sphericity of the secondary particle 2 may be 0.85 or higher, 0.90 or higher, or 0.95 or higher. The sphericity of the secondary particle 2 may be, for example, 1 or less, 0.95, or 0.90 or less. "Sphericity" refers to the circularity in the surface SEM image (two-dimensional image). Sphericity (circularity) is calculated using the following formula. ψ = 4πS / L 2 ψ: Sphericity (Circularity) π: Pi S: Cross-sectional area of ​​secondary particle 2 (area of ​​the region enclosed by the contour line of secondary particle 2) L: Circumference of secondary particle 2 (length of the outline of secondary particle 2) Sphericity is expressed as the arithmetic mean of 30 secondary particles.

[0048] In 30 primary particles 1, the average value of the maximum Ferret diameter may be, for example, 10 to 90 nm. That is, the maximum Ferret diameter of primary particle 1 may be, for example, 10 to 90 nm. The maximum Ferret diameter of primary particle 1 may be, for example, 20 nm or more, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, or 80 nm or more. The maximum Ferret diameter of primary particle 1 may be, for example, 80 nm or less, or 60 nm or less.

[0049] A carbon layer 4 may be attached to the surface of the primary particle 1. The carbon layer 4 contains carbon (C). The amount of carbon layer 4 attached may be, for example, 0.1% or more, 0.5% or more, 1% or more, 2% or more, 3% or more, or 4% or more by mass fraction relative to the secondary particle 2. The amount of carbon layer 4 attached may be, for example, 5% or less, 4% or less, or 3% or less by mass fraction relative to the secondary particle 2.

[0050] Each of the multiple primary particles 1 may contain, for example, an olivine-type phosphate compound, a layered lithium metal composite oxide, etc. "Olivine-type" exhibits a crystal structure belonging to the space group Pnma. "Layered type" exhibits a crystal structure belonging to the space group R-3m. The space group is identified by powder X-ray diffraction (XRD) measurement. Primary particles 1 may be, for example, a single-phase compound. Primary particles 1 may further contain, for example, an amorphous phase, etc.

[0051] Olivine-type phosphate compounds may include, for example, lithium iron phosphate (LFP), lithium manganese phosphate (LMP), etc. In LMP, some of the manganese (Mn) may be substituted with iron (Fe). The Fe-substituted form of LMP is also written as LMFP. LMP may have a composition represented by, for example, the following general formula. Li 1-a Mn 1-x Fe x PO4 For example, the relationship -0.5 ≤ a ≤ 0.5 may be satisfied. The Fe substitution amount (x) may be, for example, 0 or greater, 0.05 or greater, 0.1 or greater, 0.2 or greater, 0.3 or greater, 0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.8 or greater, or 0.9 or greater. The Fe substitution amount (x) may be, for example, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less.

[0052] In LMP, elements other than lithium (Li), manganese (Mn), iron (Fe), phosphorus (P), and oxygen (O) may be doped (dopants). The doping amount (molecular fraction relative to the amount of Li) may be, for example, 0.01 to 0.1. Examples of dopants include boron (B), nitrogen (N), halogens, silicon (Si), sodium (Na), magnesium (Mg), aluminum (Al), chromium (Cr), scandium (Sc), titanium (Ti), vanadium (V), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), selenium (Se), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), indium (In), and lead (Pb). It may also contain at least one selected from the group consisting of bismuth (Bi), antimony (Sb), tin (Sn), tungsten (W), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), and actinides.

[0053] The layered lithium metal composite oxide may include, for example, lithium nickel composite oxide (LNO), lithium cobalt composite oxide (LCO), lithium manganese composite oxide (LMO), and the like.

[0054] LNO may have a composition represented by the following general formula, for example. Li 1-a Ni x M 1-x O2 In the formula, the relationships of -0.5 ≤ a ≤ 0.5 and 0 ≤ x ≤ 1 are satisfied. M may include at least one selected from the group consisting of, for example, Co, Mn, and Al. For example, the relationships of 0 < x ≤ 0.1, 0.1 ≤ x ≤ 0.2, 0.2 ≤ x ≤ 0.3, 0.3 ≤ x ≤ 0.4, 0.4 ≤ x ≤ 0.5, 0.5 ≤ x ≤ 0.6, 0.6 ≤ x ≤ 0.7, 0.7 ≤ x ≤ 0.8, 0.8 ≤ x ≤ 0.9, or 0.9 ≤ x ≤ 1 may be satisfied. For example, the relationships of -0.4 ≤ a ≤ 0.4, -0.3 ≤ a ≤ 0.3, -0.2 ≤ a ≤ 0.2, or -0.1 ≤ a ≤ 0.1 may be satisfied.

[0055] LNO may include, for example, LiNi 0.9 Co 0.1 O2, LiNi 0.9 Mn 0.1 O2, and may include at least one selected from the group consisting of LiNiO2.

[0056] LNO may be represented, for example, by the following general formula. The compound represented by the following general formula may also be referred to as "NCM". Li 1-a Ni x Co y Mn z O2 In the formula, the relationships of -0.5 ≤ a ≤ 0.5, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1 are satisfied. For example, the relationship of 0 < x ≤ 0.1, 0.1 ≤ x ≤ 0.2, 0.2 ≤ x ≤ 0.3, 0.3 ≤ x ≤ 0.4, 0.4 ≤ x ≤ 0.5, 0.5 ≤ x ≤ 0.6, 0.6 ≤ x ≤ 0.7, 0.7 ≤ x ≤ 0.8, 0.8 ≤ x ≤ 0.9, or 0.9 ≤ x < 1 may be satisfied. For example, the relationship of 0 < y ≤ 0.1, 0.1 ≤ y ≤ 0.2, 0.2 ≤ y ≤ 0.3, 0.3 ≤ y ≤ 0.4, 0.4 ≤ y ≤ 0.5, 0.5 ≤ y ≤ 0.6, 0.6 ≤ y ≤ 0.7, 0.7 ≤ y ≤ 0.8, 0.8 ≤ y ≤ 0.9, or 0.9 ≤ y < 1 may be satisfied. For example, the relationship of 0 < z ≤ 0.1, 0.1 ≤ z ≤ 0.2, 0.2 ≤ z ≤ 0.3, 0.3 ≤ z ≤ 0.4, 0.4 ≤ z ≤ 0.5, 0.5 ≤ z ≤ 0.6, 0.6 ≤ z ≤ 0.7, 0.7 ≤ z ≤ 0.8, 0.8 ≤ z ≤ 0.9, or 0.9 ≤ z < 1 may be satisfied.

[0057] NCM is, for example, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.4 Co 0.3 Mn 0.3 O2, LiNi 0.3 Co 0.4 Mn 0.3 O2, LiNi 0.3 Co 0.3 Mn 0.4 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.5 Co 0.4 Mn 0.1 O2, LiNi 0.5 Co 0.1 Mn 0.4 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Co 0.3 Mn 0.1 O2, LiNi 0.6 Co 0.1 Mn 0.3O2, LiNi 0.7 Co 0.1 Mn 0.2 O2, LiNi 0.7 Co 0.2 Mn 0.1 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, and LiNi 0.9 Co 0.05 Mn 0.05 It may contain at least one selected from the group consisting of O2.

[0058] LNO may be represented by, for example, the following general formula. The compound represented by the following general formula may also be referred to as "NCA". Li 1-a Ni x Co y Al z O2 In the formula, the relationships -0.5 ≤ a ≤ 0.5, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1 are satisfied. For example, the relationship 0 < x ≤ 0.1, 0.1 ≤ x ≤ 0.2, 0.2 ≤ x ≤ 0.3, 0.3 ≤ x ≤ 0.4, 0.4 ≤ x ≤ 0.5, 0.5 ≤ x ≤ 0.6, 0.6 ≤ x ≤ 0.7, 0.7 ≤ x ≤ 0.8, 0.8 ≤ x ≤ 0.9, or 0.9 ≤ x < 1 may be satisfied. For example, the relationship 0 < y ≤ 0.1, 0.1 ≤ y ≤ 0.2, 0.2 ≤ y ≤ 0.3, 0.3 ≤ y ≤ 0.4, 0.4 ≤ y ≤ 0.5, 0.5 ≤ y ≤ 0.6, 0.6 ≤ y ≤ 0.7, 0.7 ≤ y ≤ 0.8, 0.8 ≤ y ≤ 0.9, or 0.9 ≤ y < 1 may be satisfied. For example, the relationship 0 < z ≤ 0.1, 0.1 ≤ z ≤ 0.2, 0.2 ≤ z ≤ 0.3, 0.3 ≤ z ≤ 0.4, 0.4 ≤ z ≤ 0.5, 0.5 ≤ z ≤ 0.6, 0.6 ≤ z ≤ 0.7, 0.7 ≤ z ≤ 0.8, 0.8 ≤ z ≤ 0.9, or 0.9 ≤ z < 1 may be satisfied.

[0059] NCA is, for example, LiNi 0.7 Co 0.1 Al 0.2 O2, LiNi 0.7 Co 0.2 Al 0.1 O2, LiNi 0.8 Co 0.1Al 0.1 O2, LiLiLi 0.8 Co 0.17 Al 0.03 O2, LiLiLi 0.8 Co 0.15 Al 0.05 O2 and LiNi 0.9 Co 0.05 Al 0.05 It may contain at least one selected from the group consisting of O2.

[0060] The positive electrode active material may contain both an olivine-type phosphate compound and a layered lithium metal composite oxide. The mixing ratio (mass ratio) of the olivine-type phosphate compound and the layered lithium metal composite oxide may be, for example, "olivine-type phosphate compound / layered lithium metal composite oxide = 9 / 1 to 1 / 9", "olivine-type phosphate compound / layered lithium metal composite oxide = 8 / 2 to 2 / 8", "olivine-type phosphate compound / layered lithium metal composite oxide = 7 / 3 to 3 / 7", or "olivine-type phosphate compound / layered lithium metal composite oxide = 6 / 4 to 4 / 6".

[0061] The positive electrode layer 11 includes a first region 111 and a second region 112. The positive electrode layer 11 may consist of a first region 111 and a second region 112. Each region may form a layer. The first region 111 and the second region 112 are separated by dividing the cross-section of the positive electrode layer 11 into two equal parts in the thickness direction. That is, the area fraction of the first region 111 and the second region 112 relative to the entire positive electrode layer 11 is 50% each. The first region 111 is located between the current collector foil 113 and the second region 112. The first region 111 is in direct contact with the current collector foil 113. The first region 111 includes the interface between the current collector foil 113 and the positive electrode layer 11. The second region 112 includes the surface of the positive electrode layer 11. That is, the second region 112 is exposed on the surface of the positive electrode layer 11.

[0062] In the positive electrode layer 11, the relationship expressed by the following equation is satisfied. 50% ≤ X The above X represents the ratio of porous particles 2c contained in the first region 111 to the porous particles 2c contained in the first region 111 and the second region 112. The above X is calculated for porous particles 2c having a maximum Ferret diameter of 5 μm or more.

[0063] Electrodes containing porous particles 2c are expected to show improved rate characteristics compared to electrodes with higher density. Furthermore, because the relationship "50% ≤ X" is satisfied, electron paths and ion paths are formed efficiently, which is expected to improve rate characteristics.

[0064] X may be 55% or more, 60% or more, 65% or more, 70% or more, or 75% or more. X may also be 100% or less, 95% or less, 90% or less, 85% or less, or 80% or less. Satisfying the relationship "60% ≤ X" is expected to further improve rate characteristics.

[0065] In the positive electrode layer 11, the relationship expressed by the following equation may be satisfied. 40% ≤ Y ≤ 95% The above Y represents the ratio of open-pore particles 2a to void particles 2c. The above Y is calculated for void particles 2c having a maximum Ferret diameter of 5 μm or more.

[0066] If the electrode has many voids (3), a reaction may occur between the electrode active material and the electrolyte, potentially generating gas. This can happen when a certain proportion of closed-pore particles are present. Therefore, a reduction in gas generation can be expected when the relationship 40% ≤ Y ≤ 95% is satisfied.

[0067] Y may be 45% or more, 50% or more, 55% or more, 60% or more, or 65% or more. Y may also be 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, or 65% or less. A reduction in gas emissions can be expected if the relationship "60% ≤ Y ≤ 80%" is satisfied.

[0068] The positive electrode layer 11 may further contain, in addition to the positive electrode active material, a conductive material, a binder, a thickener, etc. The amount of conductive material may be, for example, 0.1 to 10 parts by mass per 100 parts by mass of positive electrode active material. The conductive material may contain any components. For example, the conductive material may contain at least one selected from the group consisting of graphite, acetylene black (AB), Ketjenblack (registered trademark), vapor-grown carbon fiber (VGCF), carbon nanotubes (CNT), and graphene flakes (GF).

[0069] The amount of binder may be, for example, 0.1 to 10 parts by mass per 100 parts by mass of positive electrode active material. The binder may contain any components. For example, the binder may contain at least one selected from the group consisting of polyvinylidene fluoride (PVdF), vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC), polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyoxyethylene alkyl ether, and derivatives thereof. SBR, CMC, PAA, and PVP, etc., can also function as thickeners.

[0070] The positive electrode layer 11 may further contain, for example, inorganic fillers, organic fillers, solid electrolytes, surface modifiers, dispersants, lubricants, flame retardants, protective agents, fluxes, coupling agents, adsorbents, etc. The positive electrode layer 11 may also contain, for example, polyoxyethylene allylphenyl ether phosphate, zeolite, silane coupling agents, MoS2, WO3, etc.

[0071] <Method of manufacturing electrodes> Figure 3 is a schematic flowchart showing the method for manufacturing electrodes in this embodiment. Hereinafter, "the method for manufacturing electrodes in this embodiment" may be abbreviated as "this method". This method may include, for example, "(a) preparation step", "(b) contact step", "(c) mixing step", "(d) coating step", and "(e) drying step".

[0072] (a) Preparation process This process involves preparing the positive electrode active material. The following explanation will use the case of manufacturing LMFP as the positive electrode active material as an example. However, the positive electrode active material in this disclosure is not limited to LMFP.

[0073] (a-1) Slurry formation This process may include forming a slurry by mixing a lithium compound, a manganese compound, an iron compound, a phosphate compound, and a solvent. For example, a compound with the composition formula "Li 1-a Mn 1-x Fe x Lithium compounds, manganese compounds, iron compounds, and phosphate compounds may be weighed out to achieve the composition ratio (mole ratio) shown in PO4 (-0.5 ≤ a ≤ 0.5, 0 ≤ x < 1). The lithium compound may include, for example, lithium hydroxide. The manganese compound may include, for example, manganese carbonate. The iron compound may include, for example, ferric phosphate. The phosphate compound may include, for example, lithium dihydrogen phosphate.

[0074] When forming a carbon layer on the surface of primary particles, a carbon raw material is added to the raw material mixture. The carbon raw material may include, for example, sugars, organic acids, etc. The carbon raw material may also include, for example, glucose, sucrose, fructose, citric acid, etc. The amount of carbon raw material added may be, for example, 1 to 20% by mass fraction relative to the raw material mixture.

[0075] The solvent may include, for example, water. The solid content concentration of the slurry may be, for example, 20-40% by mass fraction. The proportion of secondary particles with open pores can be adjusted by adjusting the solid content concentration of the slurry.

[0076] The particle size in the slurry may be adjusted by wet grinding. For example, wet grinding may be performed so that D50 is between 0.10 and 1 μm.

[0077] (a-2) Granulation This process may include granulating secondary particles by drying the slurry. For example, secondary particles may be granulated by spray drying. The size of the secondary particles and the proportion of secondary particles with open pores can be adjusted by adjusting the conditions in the spray dryer. In particular, the intake port temperature can affect the proportion of secondary particles with open pores. The intake port temperature may be, for example, 190°C or higher, 210°C or higher, or 230°C or higher. The intake port temperature may be, for example, 270°C or lower, or 250°C or lower.

[0078] The exhaust port temperature may be, for example, 100 to 130°C. The spray rate may be, for example, 5 to 15 mL / min. The intake pressure may be, for example, about 1.8 to 2.2 MPa. The nozzle pressure of the spray nozzle may be, for example, 0.1 to 0.3 MPa.

[0079] (a-3) Firing This process may include generating a positive electrode active material (LMFP) by heat-treating secondary particles. Any heat treatment furnace (e.g., electric furnace, muffle furnace, etc.) can be used. The heat treatment atmosphere may be, for example, an inert atmosphere. The inert atmosphere may be, for example, a nitrogen atmosphere. The heat treatment temperature may be, for example, 400 to 700°C. The heat treatment time may be, for example, 4 to 6 hours. During the heating process in firing, instead of continuously increasing the temperature, the heating may be stopped at around 200°C and the temperature may be held at 200°C for about 1 hour.

[0080] (b) Contact process This step involves contacting at least a portion of the positive electrode active material obtained in the preparation step (a) above with the first solvent.

[0081] The positive electrode active material obtained in the preparation step (a) above includes porous particles having voids and non-porous particles not having voids. By bringing the positive electrode active material into contact with the first solvent, the voids of the porous particles are filled with the first solvent. Since the porous particles filled with the first solvent have a higher specific gravity than the non-porous particles, it is thought that they will be more abundant on the current collector foil side when applied to the current collector foil in the step described later.

[0082] The positive electrode active material may be washed after contact with the first solvent. This can remove any excess first solvent adhering to the surface of the positive electrode active material. For example, the positive electrode active material may be filtered by suction after contact with the first solvent, followed by solid-liquid separation and then washing with water.

[0083] The first solvent may include, for example, N-methyl-2-pyrrolidone (NMP). The contact time may be, for example, 6 to 24 hours.

[0084] (c) Mixing process This step involves mixing the positive electrode active material after the contact step (b) described above with the second solvent to form a slurry.

[0085] For example, a slurry is formed by dispersing the positive electrode active material after the contact step (b) in the second solvent. A conductive material, a binder, and a thickening agent may be mixed in.

[0086] Furthermore, the positive electrode active material that was not in contact with the first solvent may be mixed. That is, the positive electrode active material obtained in the preparation step (a) above may be mixed in this step without performing the contact step (b) above. The positive electrode active material after the contact step (b) above and the positive electrode active material that was not subjected to the contact step (b) above may be weighed in a mass ratio of 1:0 to 1:2 and mixed with the second solvent. If the proportion of positive electrode active material after the contact step (b) above is large, it is considered that when it is applied to the current collector foil in the step described later, a large amount of positive electrode active material after the contact step (b) above will be present on the current collector foil side.

[0087] The second solvent may contain, for example, water. The first solvent has a higher boiling point than the second solvent. If the boiling point of the first solvent is higher than that of the second solvent, the second solvent will evaporate faster than the first solvent when dried in the process described later. As a result, it is thought that a larger amount of the positive electrode active material filled with the second solvent will be present on the current collector foil side. Note that the boiling point of NMP is 202°C, and the boiling point of water is 100°C.

[0088] (d) Coating process This step involves applying the slurry obtained in step (c) above to the surface of the current collector foil.

[0089] For example, the slurry may be applied to the surface of the current collector foil using a doctor blade or die coater.

[0090] (e) Drying process This step involves drying the slurry after the coating step (d) described above to form the positive electrode layer.

[0091] The drying temperature may be, for example, 100°C or higher. After drying, the positive electrode layer may be compressed. This allows for adjustment of the density of the positive electrode layer.

[0092] <Liquid battery> In some embodiments, the battery is a liquid-based battery. A liquid-based battery contains an electrolyte. In some embodiments, the battery has a monopolar structure. In some embodiments, the battery has a bipolar structure. As an example, a battery having a bipolar structure (a bipolar battery) is described.

[0093] Figure 4 is a schematic perspective view of the battery in this embodiment. Figure 5 is a schematic cross-sectional view along the line VI-VI in Figure 4. Hereinafter, "orthoplane direction" refers to the direction normal to the surface of a sheet-like member (e.g., foil, electrode, etc.). "In-plane direction" refers to any direction perpendicular to the orthoplane direction. In Figure 5, the Z-axis direction corresponds to the orthoplane direction. The X-axis and Y-axis directions are examples of in-plane directions.

[0094] The battery 100 includes an outer casing 90 and a power generation element 50. The outer casing 90 houses the power generation element 50. The outer casing 90 may include, for example, a first current collector plate 91, a first laminate film 92, a second laminate film 93, and a second current collector plate 94. The first laminate film 92 and the second laminate film 93 are joined to each other at their in-plane edges. At the joint between the first laminate film 92 and the second laminate film 93, a sealing material (not shown) may be interposed between the first laminate film 92 and the second laminate film 93.

[0095] The first current collector plate 91 and the second current collector plate 94 are joined to the power generation element 50 at their ends in the stacking direction (Z-axis direction). The first laminate film 92 is joined to the first current collector plate 91. The second laminate film 93 is joined to the second current collector plate 94. A sealing material (not shown) may be interposed between the current collector plate and the laminate film at the joint between the current collector plate and the laminate film.

[0096] The power generation element 50 includes a plurality of bipolar electrodes 10. The plurality of bipolar electrodes 10 are stacked in the direction perpendicular to the plane (Z-axis direction). Each of the plurality of bipolar electrodes 10 includes, in the direction perpendicular to the plane, a positive electrode layer 11, a bipolar current collector foil 13, and a negative electrode layer 12 in that order. In the in-plane direction (for example, in the X-axis direction), the bipolar current collector foil 13 extends outward relative to the positive electrode layer 11 and the negative electrode layer 12. For example, the bipolar current collector foil 13 may extend outward relative to the positive electrode layer 11 and the negative electrode layer 12 over the entire circumference in the in-plane direction. Details of the positive electrode layer 11 are as described above.

[0097] The bipolar current collector foil 13 may include, for example, a metal foil, a conductive resin layer, etc. For example, the bipolar current collector foil 13 may be formed by bonding an Al foil and a Cu foil together. A carbon material may be coated on the surface of the bipolar current collector foil 13. The carbon material may include, for example, carbon black.

[0098] The power generation element 50 includes a sealing material 30. At its in-plane end, the sealing material 30 is joined to the current collector foil 13. The sealing material 30 may, for example, be heat-welded to the bipolar current collector foil 13. For example, the sealing material 30 may be arranged around the entire circumference of the in-plane periphery. The sealing material 30 may include, for example, a resin material. The sealing material 30 seals between adjacent bipolar current collector foils 13 in the perpendicular direction. The sealing material 30 between the bipolar current collector foils 13 partitions the cells 40. A cell 40 is the smallest unit of the power generation element 50. The battery 100 includes a plurality of cells 40 and may therefore also be called a "bipolar module". Each of the plurality of cells 40 is sealed. The plurality of cells 40 are isolated from each other. Each of the plurality of cells 40 includes a positive electrode layer 11, a separator 20, a negative electrode layer 12, and an electrolyte.

[0099] (Negative electrode layer) The negative electrode layer 12 is attached to one side of the bipolar current collector foil 13. The negative electrode layer 12 is located on the back side of the positive electrode layer 11. The negative electrode layer 12 may have a larger area than the positive electrode layer 11. The negative electrode layer 12 contains a negative electrode active material.

[0100] The negative electrode active material may be in the form of parts or sheets, for example. The D50 of the negative electrode active material may be, for example, 1 μm or more, 5 μm or more, or 10 μm or more. The D50 of the negative electrode active material may be, for example, 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less.

[0101] The negative electrode active material may contain any components. For example, the negative electrode active material may include at least one selected from the group consisting of carbon-based active materials, alloy-based active materials, Si-C composite materials, Li metal, Li-based alloys, and lithium titanate. In some embodiments of this invention, the battery may be a Li metal negative electrode battery.

[0102] The carbon-based active material may include, for example, at least one selected from the group consisting of graphite, soft carbon, and hard carbon. "Graphite" is a general term for natural graphite and artificial graphite. Graphite may be a mixture of natural graphite and artificial graphite. The mixing ratio (mass ratio) may be, for example, "natural graphite / artificial graphite = 1 / 9 to 9 / 1", "natural graphite / artificial graphite = 2 / 8 to 8 / 2", or "natural graphite / artificial graphite = 3 / 7 to 7 / 3".

[0103] The surface of the graphite may be coated with, for example, amorphous carbon. The surface of the graphite may be coated with, for example, a different material. The different material may include, for example, at least one selected from the group consisting of P, W, Al, and O. The different material may include, for example, at least one selected from the group consisting of Al(OH)3, AlOOH, Al2O3, WO3, Li2CO3, LiHCO 3、 and at least one selected from the group consisting of Li3PO4.

[0104] The alloy-based active material may include, for example, at least one selected from the group consisting of Si, Li silicate, SiO, Si-based alloy, tin (Sn), SnO, and Sn-based alloy.

[0105] SiO may be represented, for example, by the following general formula. SiO x In the formula, the relationship 0 < x < 2 is satisfied. For example, the relationship 0.5 ≤ x ≤ 1.5 or 0.8 ≤ x ≤ 1.2 may be satisfied.

[0106] "Si-C composite material" refers to a composite material of a carbon-based active material (such as graphite) and an alloy-based active material (such as Si). For example, Si fine particles may be dispersed in carbon particles. For example, Si fine particles may be dispersed in graphite particles. For example, Li silicate particles may be coated with a carbon material (such as amorphous carbon).

[0107] (Separator) The separator 20 can separate the positive electrode layer 11 from the negative electrode layer 12. The separator 20 has electrical insulating properties. The separator 20 may include, for example, at least one selected from the group consisting of a resin film (polymer film), an inorganic particle layer, and an organic particle layer. The separator 20 may include, for example, a resin film and an inorganic particle layer.

[0108] The resin film is porous. The resin film may include, for example, a microporous membrane, a nonwoven fabric, etc. The resin film includes a resin skeleton. The resin skeleton may be continuous, for example, in a mesh-like structure. Pores are formed in the gaps of the resin skeleton. The resin film can permeate the electrolyte. The resin film may have, for example, an average pore diameter of 1 μm or less. The average pore diameter of the resin film may be, for example, 0.01 to 1 μm, or 0.1 to 0.5 μm. The "average pore diameter" can be measured by the mercury intrusion method. The Gaurle value of the resin film is, for example, 50 to 250 s / 100 cm. 3 It may also be the case that the "Gehré value" can be measured by the Gehré test method.

[0109] The resin film may contain at least one selected from the group consisting of, for example, olefin resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, acrylic resins, and polyester resins. The resin film may also contain at least one selected from the group consisting of, for example, polyethylene (PE), polypropylene (PP), polyamide (PA), polyamide-imide (PAI), polyimide (PI), aromatic polyamide (aramid), polyphenylene ether (PPE), and derivatives thereof. The resin film can be formed, for example, by a stretching method, a phase separation method, or the like. The thickness of the resin film may be, for example, 5 to 50 μm or 10 to 25 μm.

[0110] The resin film may have, for example, a single-layer structure. The resin film may consist of, for example, a PE layer. The framework of the PE layer is formed of PE. The PE layer may have a shutdown function. The resin film may have, for example, a multilayer structure. The resin film may include, for example, a PP layer and a PE layer. The framework of the PP layer is formed of PP. The resin film may have, for example, a three-layer structure. The resin film may be formed by laminating a PP layer, a PE layer and a PP layer in this order. The thickness of the PE layer may be, for example, 5 to 20 μm. The thickness of the PP layer may be, for example, 3 to 10 μm.

[0111] The inorganic particle layer may be formed on the surface of the resin film. The inorganic particle layer may be formed on only one side of the resin film or on both sides. The inorganic particle layer may be formed on the surface facing the positive electrode layer 11 or on the surface facing the negative electrode layer 12. The inorganic particle layer may be formed on the surface of the positive electrode layer 11 or on the surface of the negative electrode layer 12.

[0112] The inorganic particle layer is porous. The inorganic particle layer contains inorganic particles. Inorganic particles may also be called "inorganic fillers." Pores are formed in the gaps between the inorganic particles. The thickness of the inorganic particle layer may be, for example, 0.5 to 10 μm or 1 to 5 μm. The inorganic particles may contain, for example, a heat-resistant material. An inorganic particle layer containing a heat-resistant material is also called an "HRL (Heat Resistance Layer)." The inorganic particles may contain at least one selected from the group consisting of boehmite, alumina, zirconia, titania, magnesia, and silica. The inorganic particles may have any shape. For example, the inorganic particles may be spherical, rod-shaped, plate-shaped, fibrous, etc. The D50 of the inorganic particles may be, for example, 0.1 to 10 μm or 0.5 to 3 μm. The inorganic particle layer may further contain a binder. The binder may include, for example, at least one selected from the group consisting of acrylic resins, polyamide resins, fluororesins, aromatic polyether resins, and liquid crystal polyester resins.

[0113] The separator 20 may include, for example, an organic particle layer. The separator 20 may include, for example, an organic particle layer instead of a resin film. The separator 20 may include, for example, an organic particle layer instead of an inorganic particle layer. The separator 20 may include both a resin film and an organic particle layer. The separator 20 may include both an inorganic particle layer and an organic particle layer. The separator 20 may include a resin film, an inorganic particle layer, and an organic particle layer.

[0114] The thickness of the organic particle layer may be, for example, 0.1 to 50 μm, 0.5 to 20 μm, 0.5 to 10 μm, or 1 to 5 μm. The organic particle layer contains organic particles. The organic particles may also be called "organic fillers". The organic particles may contain heat-resistant materials. The organic particles may contain at least one selected from the group consisting of, for example, PE, PP, PTFE, PI, PAI, PA, and aramid. The organic particles may be spherical, rod-shaped, plate-shaped, fibrous, etc. The D50 of the organic particles may be, for example, 0.1 to 10 μm or 0.5 to 3 μm.

[0115] The separator 20 may include, for example, a mixed layer. The mixed layer may contain both inorganic and organic particles.

[0116] (electrolyte) The electrolyte is a liquid electrolyte. The electrolyte contains a solute and a solvent. The concentration of the solute may be, for example, 0.5-1 mole / L, 1-1.5 mole / L, 1.5-2 mole / L, 2-2.5 mole / L, or 2.5-3 mole / L. "mol / L" may also be written as "M". The solute contains a supporting salt (Li salt). The solute may also contain, for example, inorganic acid salts, imide salts, oxalate complexes, halides, etc. The solute may include, for example, at least one selected from the group consisting of LiPF6, LiBF4, LiClO4, LiAsF6, LiSbF6, LiN(SO2F)2 "LiFSI", LiN(SO2CF3)2 "LiTFSI", LiB(C2O4)2 "LiBOB", LiBF2(C2O4) "LiDFOB", LiPF2(C2O4)2 "LiDFOP", LiPO2F2, FSO3Li, LiI, LiBr, and derivatives thereof.

[0117] The electrolyte may contain, for example, a carbonate-based solvent (carbonate ester-based solvent). The solvent may contain, for example, cyclic carbonates, linear carbonates, fluorinated carbonates, etc. The solvent may contain, for example, at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), monofluoroethylene carbonate (FEC), difluoroethylene carbonate, 4,4-difluoroethylene carbonate, trifluoroethylene carbonate, perfluoroethylene carbonate, fluoropropylene carbonate, difluoropropylene carbonate, and derivatives thereof.

[0118] The solvent may contain cyclic carbonates (such as EC, PC, FEC, etc.) and chain carbonates (such as EMC, DMC, DEC, etc.). The mixing ratio (volume ratio) of the cyclic carbonate and the chain carbonate may be, for example, "cyclic carbonate / chain carbonate = 1 / 9 to 4 / 6", "cyclic carbonate / chain carbonate = 2 / 8 to 3 / 7", or "cyclic carbonate / chain carbonate = 3 / 7 to 4 / 6".

[0119] The solvent may contain cyclic carbonates (such as EC, PC, etc.) and fluorinated cyclic carbonates (such as FEC, etc.). The mixing ratio (volume ratio) of the cyclic carbonate and the fluorinated cyclic carbonate may be, for example, "cyclic carbonate / fluorinated cyclic carbonate = 99 / 1 to 90 / 10", "cyclic carbonate / fluorinated cyclic carbonate = 9 / 1 to 1 / 9", "cyclic carbonate / fluorinated cyclic carbonate = 9 / 1 to 7 / 3", or "cyclic carbonate / fluorinated cyclic carbonate = 3 / 7 to 1 / 9".

[0120] The solvent may contain, for example, EC, FEC, EMC, DMC, and DEC. The volume ratio of each component may satisfy, for example, the relationship represented by the following formula. V EC +V FEC +V EMC +V DMC +V DEC =10 In the above formula, V EC 、V FEC 、V EMC 、V DMC 、V DEC respectively represent the volume ratios of EC, FEC, EMC, DMC, and DEC. 1≦V EC ≦4, 0≦V FEC ≦3, V EC +V FEC ≦4, 0≦V EMC ≦9, 0≦V DMC ≦9, 0≦V DEC ≦9, 6≦V EMC +V DMC +V DEC ≦9 The relationship is satisfied. For example, 1 ≤ V EC ≤ 2, or 2 ≤ V EC The condition ≤ 3 may also be satisfied. For example, 1 ≤ V FEC ≤ 2, or 2 ≤ V FEC The condition ≤ 4 may also be satisfied. For example, 3 ≤ V EMC ≤4, or 6 ≤V EMC The condition ≤ 8 may also be satisfied. For example, 3 ≤ V DMC ≤4, or 6 ≤V DMC The condition ≤ 8 may also be satisfied. For example, 3 ≤ V DEC ≤4, or 6 ≤V DEC The condition ≤ 8 may also be satisfied.

[0121] The solvent may have compositions such as "EC / EMC=3 / 7", "EC / DMC=3 / 7", "EC / FEC / DEC=1 / 2 / 7", "EC / DMC / EMC=3 / 4 / 3", "EC / DMC / EMC=3 / 3 / 4", "EC / FEC / DMC / EMC=2 / 1 / 4 / 3", "EC / FEC / DMC / EMC=1 / 2 / 4 / 3", "EC / FEC / DMC / EMC=2 / 1 / 3 / 4", and "EC / FEC / DMC / EMC=1 / 2 / 3 / 4" in volume ratio.

[0122] The electrolyte may contain an ether-based solvent. The electrolyte may contain, for example, at least one selected from the group consisting of tetrahydrofuran (THF), 1,4-dioxane (DOX), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), hydrofluoroether (HFE), ethylglycyle, triglycyle, tetraglycyle, and derivatives thereof.

[0123] The electrolyte may contain any additives. The amount of additive (mass fraction of the total electrolyte) may be, for example, 0.01-5%, 0.05-3%, or 0.1-1%. The additives may include, for example, SEI (Solid Electrolyte Interphase) formation promoters, SEI formation inhibitors, gas generators, overcharge inhibitors, flame retardants, antioxidants, electrode protectants, surfactants, etc.

[0124] Additives include, for example, vinylene carbonate (VC), vinylethylene carbonate (VEC), 1,3-propanesultone (PS), tert-amylbenzene, 1,4-di-tert-butylbenzene, biphenyl (BP), cyclohexylbenzene (CHB), ethylene sulfite (ES), propanesultone (PS), ethylene sulfate (DTD), γ-butyrolactone, phosphazene compounds, carboxylic acid esters [e.g., methyl formate (MF), methyl acetate (MA), methyl propionate (MP), diethyl malonate (DEM), etc.], fluorobenzenes [e.g., monofluorobenzene (FB), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-trifluorobenzene, 1,2,4-trifluorobenzene, 1,3,5-trifluorobenzene, 1,2,3,4-tetrafluorobenzene, 1,2,3,5-tetrafluorobenzene, 1,2,4,5-tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, etc.), fluorotoluene (e.g., 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, 2,3-difluorotoluene, 2,4-difluorotoluene, 2,5-difluorotoluene, 2,6-difluorotoluene, 3,4-difluorotoluene, octafluorotoluene, etc.), benzotrifluorides (e.g., benzotrifluoride, 2-fluorobenzotrifluoride, 3-fluorobenzotrifluoride, 4-fluorobenzotrifluoride, 2-methylbenzotrifluoride, 3-methylbenzotrifluoride, 4-methylbenzotrifluoride, etc.), fluoroxylenes (e.g., 3-fluoro-o-xylene, 4-fluoro-o-xylene, 2-fluoro-m-xylene, 5-fluoro-m-xylene, etc.), sulfur-containing heterocyclic compounds (e.g., benzothiazole, 2-methyl benzothiazole) It may contain at least one selected from the group consisting of (e.g., nzothiazole, tetrathiafulvalene), nitrile compounds (e.g., adiponitrile, succinonitrile), phosphate esters (e.g., trimethyl phosphate, triethyl phosphate), carboxylic acid anhydrides (e.g., acetic anhydride, propionic anhydride, oxalic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, benzoic anhydride), alcohols (e.g., methanol, ethanol, n-propyl alcohol, ethylene glycol, diethylene glycol monomethyl ether), and derivatives thereof.

[0125] The components mentioned above may be used as solutes and solvents, or as trace components (additives). The additives may include, for example, at least one selected from the group consisting of LiBF4, LiFSI, LiTFSI, LiBOB, LiDFOB, LiDFOP, LiPO2F2, FSO3Li, LiI, LiBr, HFE, DOX, PC, FEC, and derivatives thereof.

[0126] The electrolyte may contain an ionic liquid. The ionic liquid may contain, for example, at least one selected from the group consisting of sulfonium salts, ammonium salts, pyridinium salts, piperidinium salts, pyrrolidinium salts, morpholinium salts, phosphonium salts, imidazolium salts, and derivatives thereof.

[0127] In some embodiments of this invention, the battery may include a gel electrolyte; that is, the battery may be a polymer battery. The gel electrolyte may include an electrolyte solution and a polymer material. The polymer material may form a polymer matrix. The polymer material may include, for example, at least one selected from the group consisting of PVdF, PVdF-HFP, polyacrylonitrile (PAN), PVdF-PAN, polyethylene oxide (PEO), polyethylene glycol (PEG), and derivatives thereof.

[0128] <All-solid-state battery> In some embodiments of this invention, the battery is a solid-state battery. The solid-state battery may have a bipolar structure. The solid-state battery includes a solid electrolyte instead of an electrolyte and a separator 20. That is, instead of a separator 20, a solid electrolyte layer separates the negative electrode layer 12 from the positive electrode layer 11. The solid electrolyte layer includes, for example, a solid electrolyte and a binder. The positive electrode layer 11 and the negative electrode layer 12 may also include a solid electrolyte.

[0129] The solid electrolyte may be, for example, a powder. The D50 of the solid electrolyte may be, for example, 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, 0.9 μm or more, or 1 μm or more. The D50 of the solid electrolyte may be 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less.

[0130] The solid electrolyte may include, for example, at least one selected from the group consisting of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, hydride solid electrolytes, and nitride solid electrolytes.

[0131] The sulfide solid electrolyte may contain at least one selected from the group consisting of an amorphous phase, a crystalline phase, and a glass ceramic (crystallized glass) phase. The crystalline phase may be, for example, an argyrodite type or an LGPS type. The sulfide solid electrolyte contains Li and sulfur (S). In addition to Li and S, the sulfide solid electrolyte may further contain any other components.

[0132] Examples of sulfide solid electrolytes include LiI-LiBr-Li3PS4, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2O-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-GeS2-P2S5, Li2S-P2S5, Li 10 GeP2S 12 Li4P2S6, Li7P3S 11 It may include at least one selected from the group consisting of Li3PS4 and Li7PS6.

[0133] For example, "LiI-LiBr-Li3PS4" indicates a sulfide solid electrolyte produced by mixing LiI, LiBr, and Li3PS4 in any molar ratio. For example, the sulfide solid electrolyte may be produced by a mechanochemical method. The mixing ratio may be specified by prefixing each raw material with a number. For example, "10LiI-15LiBr-75Li3PS4" indicates that the mixing ratio is "LiI / LiBr / Li3PS4 = 10 / 15 / 75 (molar ratio)".

[0134] The sulfide solid electrolyte may have a composition represented by the following general formula, for example. xLi2S-(1-x)P2S5 In the formula, x may be, for example, greater than 0, 0.1 or greater, 0.2 or greater, 0.25 or greater, 0.3 or greater, 0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.75 or greater, 0.8 or greater, or 0.9 or greater. x may also be, for example, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.75 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. For example, when x = 0.75, "xLi2S-(1-x)P2S5" may have the composition of Li3PS4.

[0135] The sulfide solid electrolyte may have a composition represented by the following general formula, for example. yLiI-zLiBr-(100-yz)[xLi2S-(1-x)P2S5] In the formula, x may be, for example, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.75 or greater, 0.8 or greater, or 0.9 or greater. x may be, for example, 1 or less, 0.9 or less, 0.8 or less, 0.75 or less, 0.7 or less, or 0.6 or less. y may be, for example, 0 or greater, 5 or greater, 10 or greater, 15 or greater, 20 or greater, or 25 or greater. y may be, for example, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, or 5 or less. z may be, for example, 0 or greater, 5 or greater, 10 or greater, 15 or greater, 20 or greater, or 25 or greater. z may be, for example, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, or 5 or less.

[0136] The sulfide solid electrolyte may have a composition represented by the following general formula, for example. Li 7-x-2y PS 6-x-y X y In the equation, the relationships "0 < 7 - x - 2y", "0 < 6 - xy", "0 ≤ x", and "0 ≤ y" are satisfied. X may include, for example, at least one selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0137] The sulfide solid electrolyte may have a composition represented by the following general formula, for example. Li 4-x M 1-x P x S4 In the formula, x may be, for example, greater than 0, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more. x may be, for example, less than 1, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. M may contain, for example, at least one selected from the group consisting of Al, Zn, In, Ge, Si, Sn, Sb, Ga, and Bi.

[0138] The sulfide solid electrolyte may have, for example, a composition represented by the following general formula. Li 10+x Ge 1+x P 2-x S 12 In the formula, x may be, for example, 0 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, or 0.6 or more. x may be, for example, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. The sulfide solid electrolyte represented by the above general formula may contain, for example, a LGPS-type crystal phase.

[0139] The halide solid electrolyte may have, for example, a composition represented by the following general formula. Li 6-na M a X6 In the formula, n indicates the oxidation number of M. M may contain, for example, an atom having an oxidation number of +3. M may contain, for example, an atom having an oxidation number of +4. M may contain, for example, at least one selected from the group consisting of Y, Al, Ti, Zr, Ca, and Mg. For example, the relationship of "0 < a < 2" may be satisfied. X may contain, for example, at least one selected from the group consisting of F, Cl, Br, and I.

[0140] The halide solid electrolyte may have a composition represented by, for example, the following general formula. Li 3-a Ti a Al 1-a F6 In the formula, a may be, for example, 0 or greater, 0.1 or greater, 0.2 or greater, 0.3 or greater, 0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.8 or greater, or 0.9 or greater. a may also be, for example, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less.

[0141] The halide solid electrolyte may have a composition represented by, for example, the following general formula. Li3YCl a Br b I 6-a-b In the expression, for example, the relationship "0 ≤ a + b ≤ 6" may be satisfied. a may be, for example, 0 or greater, 1 or greater, 2 or greater, 3 or greater, 4 or greater, or 5 or greater. a may be, for example, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, or 1 or less. b may be, for example, 0 or greater, 1 or greater, 2 or greater, 3 or greater, 4 or greater, or 5 or greater. b may be, for example, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, or 1 or less.

[0142] Oxide solid electrolytes include, for example, LiNbO3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, La 2 / 3-x Li 3x TiO3 and Li7La3Zr2O 12 It may contain at least one selected from the group consisting of the following. The hydride solid electrolyte may include, for example, LiBH4. The nitride solid electrolyte may include, for example, Li3N, Li3BN2, etc. [Examples]

[0143] <Manufacturing of positive electrodes> (No.1) (a) Preparation process Compositional formula “Li 1.04 Mn 0.6 Fe 0.4 Lithium hydroxide monohydrate, manganese carbonate, ferric phosphate, and lithium dihydrogen phosphate were weighed to match the composition ratio shown in "PO4". 8% glucose was weighed by mass fraction relative to the total mass of the raw materials. The weighed materials were mixed with water to form a slurry (first slurry). The solid content concentration of the first slurry was as shown in Figure 6. Wet grinding was performed to achieve a D50 of 0.30 μm.

[0144] Secondary particles were formed by spray drying of the first slurry. The target value for the D50 of the secondary particles was 9 ± 1 μm. The intake port temperature was as shown in Figure 6. The exhaust port temperature of the spray dryer was 115 ± 15°C, the spray velocity was 10 mL / min, the intake pressure was 2.0 MPa, and the nozzle pressure of the spray nozzle was 0.2 MPa.

[0145] LMFP was synthesized by calcining secondary particles under a nitrogen atmosphere. Figure 7 shows the temperature profile during calcination. First, the furnace temperature was raised to 200°C at a heating rate of 3°C / min. The furnace temperature was maintained at 200°C for 1 hour. Next, the furnace temperature was raised to 650°C at a heating rate of 5°C / min. The furnace temperature was maintained at 650°C for 5 hours. After that, the furnace temperature was cooled to 400°C at a cooling rate of 2°C / min. The furnace temperature was further cooled to room temperature at a cooling rate of 15°C / min. Note that in No. 1, the (b) contact process was not performed.

[0146] (c) Mixing process The obtained LMFP, conductive material (AB), binder (SBR), and thickener (CMC) were mixed to form a mixture. The mixing ratio (mass ratio) was "LMFP / conductive material / binder / thickener = 96 / 1.5 / 2 / 0.5". A slurry (second slurry) was formed by dispersing the mixture in water.

[0147] (d) Coating process The second slurry was applied to the surface of the aluminum foil.

[0148] (e) Drying process The coated second slurry was dried at 100°C to form the positive electrode layer. The density of the positive electrode layer was reduced to 1.8 g / cm³ by roll pressing. 3 Through this adjustment, a cathode layer (cathode base material) including the first and second regions was formed. The cathode base material was subjected to a vacuum drying treatment at 120°C for 12 hours.

[0149] (Coin cell production) After drying, a disc sample (diameter: 14 mm) was removed from the cathode raw material by punching.

[0150] The coin cell was assembled inside the glove compartment. The cell configuration is as follows: Working electrode: Disc sample (positive electrode) Opposite pole: Li foil Separator: Polymer porous membrane Electrolyte: "EC / DMC=3 / 7 (volume ratio)", LiPF6 (1mol / L)

[0151] (No.2~No.10) As shown in Figure 6, LMFP was manufactured in the same manner as in No. 1, except that the conditions of the manufacturing method were changed.

[0152] (b) Filling process A portion of the obtained LMFP was immersed in NMP for 12 hours. After immersion, the NMP adhering to the surface of the LMFP was removed by suction filtration, solid-liquid separation, and washing with water.

[0153] (c) Mixing process The obtained LMFP (NMP-containing LMFP) and LMFP not immersed in NMP (NMP-free LMFP) were mixed in the mass ratio shown in Figure 6 (NMP-containing LMFP:NMP-free LMFP = A:B). These LMFPs were mixed with a conductive material, binder, and thickener in the same proportions as in No. 1 to obtain a mixture. The mixture was dispersed in water to form a second slurry.

[0154] Subsequently, the positive electrode was manufactured by going through the same (d) coating process and (e) drying process as in No. 1. Also, the coin cell was assembled in the same manner as in No. 1.

[0155] <Rating> (measurement) The values ​​of X and Y for each No. shown in Figure 6 were calculated using the method described above.

[0156] <Rating> (Rate characteristics) The discharge capacity ratio (1C / 0.1C) was measured using the following procedure. A larger discharge capacity ratio (1C / 0.1C) indicates better rate characteristics.

[0157] The rate equivalent to 1C is determined based on the discharge capacity (theoretical capacity) obtained from the coating mass of the positive electrode layer. "C" is a symbol indicating the current rate (time rate). At a rate of 1C, the theoretical capacity is supplied over one hour. The coin cell is charged by constant current-constant voltage (CCCV) charging under the following conditions at a temperature of 25°C. CC charging rate: 0.1C Maximum charging voltage: 4.3V Current cutoff rate during CV charging: 0.01C

[0158] After charging, CC discharge is performed at a rate of 0.1C until the voltage reaches 3.0V, and the discharge capacity (0.1C) (mAh / g) is measured. The coin cell is then charged again by the same CCCV charging process described above. After charging, CC discharge is performed at a rate of 1C until the voltage reaches 3.0V, and the discharge capacity (1C) is measured. The discharge capacity ratio (1C / 0.1C) is obtained by dividing the discharge capacity (1C) by the discharge capacity (0.1C). The results are shown in Figure 6. Note that the rate characteristic values ​​in Figure 6 are relative values ​​when the discharge capacity ratio of No. 1 is set to 100.

[0159] (Gas generation amount) The amount of gas generated was measured using the following procedure.

[0160] CC charge-discharge cycles were performed 100 times at a rate of 0.1C under a temperature environment of 60°C. The charge-discharge conditions were as described above. The volume of the coin cell before the start of charge-discharge and after 100 cycles was measured under a temperature environment of 25°C using the Archimedes method. The amount of gas generated was measured by subtracting the volume before the start of charge-discharge from the volume after 100 cycles. The results are shown in Figure 6. Note that the gas generation values ​​in Figure 6 are relative values ​​with the gas generation amount of No. 5 set to 100.

[0161] <Result> As shown in Figure 6, when the relationship 50% ≤ X is satisfied, there is a tendency for the rate characteristics to improve. Furthermore, when the relationship 60% ≤ X is satisfied, there is a greater tendency for the rate characteristics to improve.

[0162] When the relationship 40% ≤ Y ≤ 95% is satisfied, there is a tendency for gas emissions to decrease. Furthermore, when the relationship 60% ≤ Y ≤ 80% is satisfied, there is a greater tendency for gas emissions to decrease. [Explanation of Symbols]

[0163] 1 Primary particle, 2 Secondary particle, 2a Open-pore particle, 2b Closed-pore particle, 2c Vacant particle, 2d Non-vacant particle, 3 Vacancy, 3a Open pore, 3b Gap, 4 Carbon layer, 10 Bipolar electrode, 11 Cathode layer, 110 Electrode, 111 First region, 112 Second region, 12 Negative electrode layer, 13 Bipolar current collector foil, 113 Current collector foil, 20 Separator, 30 Sealing material, 40 Cell, 50 Power generation element, 90 Outer casing, 91 First current collector plate, 92 First laminate film, 93 Second laminate film, 94 Second current collector plate, 100 Battery.

Claims

1. Including current collector foil and positive electrode layer, The positive electrode layer is arranged on the surface of the current collector foil, The positive electrode layer contains a positive electrode active material, The positive electrode active material includes a plurality of secondary particles, Each of the plurality of secondary particles includes a plurality of primary particles, The secondary particles include porous particles having voids, The cross-section of the positive electrode layer includes a first region and a second region. The first region and the second region are separated by dividing the cross-section of the positive electrode layer into two equal parts in the thickness direction. The first region is located between the current collector foil and the second region, The relationship 50% ≤ X is satisfied, The above X represents the ratio of the porous particles contained in the first region to the porous particles contained in the first region and the porous particles contained in the second region, In the porous particles having a maximum Ferret diameter of 5 μm or more, X is calculated. electrode.

2. The relationship 60% ≤ X is satisfied. The electrode according to claim 1.

3. The porous particles include open porous particles in which the pores are open to the outside. The relationship 40% ≤ Y ≤ 95% is satisfied. Y represents the ratio of open-pore particles to the void particles, In the porous particles having a maximum Ferret diameter of 5 μm or more, Y is calculated. The electrode according to claim 1.

4. The relationship 60% ≤ Y ≤ 80% is satisfied. The electrode according to claim 3.

5. Each of the plurality of primary particles contains an olivine-type phosphate compound. The electrode according to claim 1.

6. The olivine-type phosphate compound is manganese iron lithium phosphate. The electrode according to claim 5.

7. The electrode includes the electrode described in any one of claims 1 to 6, battery.

8. Having a bipolar structure, The battery according to claim 7.

9. (a) Prepare the positive electrode active material. (b) Contacting at least a portion of the positive electrode active material with the first solvent, (c) Mixing the positive electrode active material after contact with the first solvent with the second solvent to form a slurry. (d) Applying the slurry to the surface of the current collector foil, (e) Forming a positive electrode layer by drying the slurry, The positive electrode active material includes a plurality of secondary particles, The secondary particles include porous particles having voids, The first solvent has a higher boiling point compared to the second solvent. A method for manufacturing electrodes.

10. In (c) above, the positive electrode active material after contact with the first solvent and the positive electrode active material that has not been contacted with the first solvent are weighed in a mass ratio of 1:0 to 1:2 and mixed with the second solvent. The method for manufacturing an electrode according to claim 9.

11. The first solvent comprises N-methyl-2-pyrrolidone, The second solvent contains water. A method for manufacturing an electrode according to claim 9 or claim 10.

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