Positive electrode active material powder and lithium secondary battery

Abstract

To provide a positive electrode active material powder capable of improving the capacity retention rate of a lithium secondary battery.SOLUTION: A positive electrode active material powder according to the present disclosure is used in a lithium secondary battery. The positive electrode active material powder is a positive electrode active material powder for a lithium secondary battery that includes a plurality of particles composed of a lithium transition metal oxide having a layered crystal structure. The thickness DTM of the transition metal layer included in the lithium transition metal oxide is 2.06 Å to 2.19 Å. The thickness DTM indicates a value calculated by Rietveld analysis using a synchrotron radiation X-ray diffraction profile of the particles.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a positive electrode active material powder and a lithium secondary battery.

Background Art

[0002] Lithium secondary batteries are used in information and communication technologies (e.g., personal computers, smartphones, etc.), in-vehicle applications, power storage, and the like.

[0003] Patent Document 1 discloses a lithium secondary battery. The lithium secondary battery includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. The positive electrode includes, as a positive electrode active material, a powder of a lithium composite transition metal oxide. The lithium composite transition metal oxide has a layered structure. The nickel content in the entire transition metal of the lithium composite transition metal oxide is 50 atm% to 75 atm%. The change rate of the interlayer distance of the lithium-oxygen layer in the charging interval of 58% to 86% of the state of charge (SOC) of the powder of the lithium composite transition metal oxide is 3% or less.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the lithium composite transition metal oxide disclosed in Patent Document 1, when charging and discharging are performed, lithium ions are inserted and extracted. Therefore, when charging and discharging are repeated, the volume of the lithium composite transition metal oxide is likely to change. As a result, there is a risk of cracks occurring in the positive electrode active material layer. When cracks occur in the positive electrode active material layer, the capacity of the lithium secondary battery decreases.

[0006] The present disclosure has been made in view of the above circumstances. The problem to be solved by one embodiment of the present disclosure is to provide a positive electrode active material powder capable of improving the capacity retention rate of a lithium secondary battery. The problem to be solved by another embodiment of the present disclosure is to provide a lithium secondary battery having an excellent capacity retention rate.

Means for Solving the Problems

[0007] The means for solving the above problems include the following embodiments. <1> A positive electrode active material powder used in a lithium secondary battery, including a plurality of particles composed of a lithium transition metal oxide having a layered crystal structure, the thickness D of the transition metal layer contained in the lithium transition metal oxide TM is 2.06 Å to 2.19 Å, the thickness D TM represents a value calculated by Rietveld analysis using the synchrotron radiation X-ray diffraction profile of the particles, the positive electrode active material powder. <2> The thickness D TM is 2.09 Å to 2.17 Å, the positive electrode active material powder according to <1> above. <3> The lithium transition metal oxide includes at least one of nickel (Ni), manganese (Mn), and cobalt (Co), and an additive element (M), the additive element (M) includes an element having an ionic radius of 0.80 Å to 1.25 Å, the positive electrode active material powder according to <1> or <2> above. <4> The element having the ionic radius includes Sr, the positive electrode active material powder according to <3> above. <5> A lithium secondary battery including a positive electrode containing the positive electrode active material powder according to any one of <1> to <4> above.

Effects of the Invention

[0008] According to the present disclosure, there are provided a positive electrode active material powder capable of improving the capacity retention rate of a lithium secondary battery, and a lithium secondary battery having an excellent capacity retention rate.

Brief Description of the Drawings

[0009]

Figure 1

DETAILED DESCRIPTION OF THE INVENTION

[0010] In the present disclosure, a numerical range indicated using "~" means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other stepwise descriptions. In the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, the amount of each component means the total amount of a plurality of substances when there are a plurality of substances corresponding to each component, unless otherwise specified. In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved.

[0011] (1) Positive electrode active material powder The positive electrode active material powder of the present disclosure is used in a lithium secondary battery. The positive electrode active material powder includes a plurality of particles (hereinafter also referred to as "TM particles") composed of a lithium transition metal oxide having a layered crystal structure. The thickness D of the transition metal layer contained in the lithium transition metal oxide TM is 2.06 Å to 2.19 Å. The thickness D TM represents a value calculated by Rietveld analysis using the synchrotron radiation X-ray diffraction profile of the particles.

[0012] The "lithium transition metal oxide" refers to a compound having lithium and transition metals as cations and oxide ions as anions. The "transition metal" refers to the elements of Groups 3A to 7A, 8, and 1B in the periodic table. The "layered crystal structure" refers to a crystal structure in which a transition metal layer containing lithium and a lithium single layer are alternately stacked via oxide ions, as shown in FIG. 1. In FIG. 1, the symbol "D TM " represents the thickness D TM of the transition metal layer, "TM layer" represents the transition metal layer, and "Li layer" represents the lithium single layer. When the lithium transition metal oxide contains an additive element described later, the additive element is included in the TM layer. The thickness D TM of the transition metal layer is calculated in the same manner as the method described in the examples.

[0013] Since the positive electrode active material powder of the present disclosure has the above configuration, the capacity retention rate of the lithium secondary battery can be improved. This effect is presumed for the following reasons, but is not limited thereto. In the present disclosure, the thickness D TM of the transition metal layer is 2.06 Å to 2.19 Å. Therefore, the volume of the lithium transition metal oxide is unlikely to change even when charge and discharge are repeated. That is, cracks are less likely to occur in the positive electrode active material layer. As a result, it is presumed that the positive electrode active material powder of the present disclosure can improve the capacity retention rate of the lithium secondary battery.

[0014] The lithium transition metal oxide can be obtained, for example, by mixing a transition metal compound, a lithium compound (for example, Li2CO3, LiOH, etc.), and an additive element described later to obtain a mixture, and firing the obtained mixture. The transition metal compound is obtained by subjecting a transition metal raw material (for example, NiSO4, CoSO4, MnSO4, etc.) to hydrothermal synthesis. In hydrothermal synthesis, unlike crystallization, the transition metal raw material is heated under the conditions of 120°C to 220°C, 4 hours to 10 hours, and 0.2 MPa to 1.0 MPa. The transition metal compound (that is, the transition metal layer precursor) obtained by hydrothermal synthesis is more likely to grow crystals than the transition metal compound obtained by crystallization. By using the transition metal compound obtained by hydrothermal synthesis and an additive element having a specific ionic radius (for example, 0.80 Å to 1.25 Å), the thickness D TM of the transition metal layer can be adjusted to 2.06 Å to 2.19 Å.

[0015] (1.1)TM particles The positive electrode active material powder of the present disclosure contains a plurality of TM particles. The TM particles are composed of a lithium transition metal oxide having a layered crystal structure.

[0016] The thickness D of the transition metal layer contained in the lithium transition metal oxide TM is preferably 2.09 Å to 2.17 Å. Thereby, the positive electrode active material powder of the present disclosure can further improve the capacity retention rate of the lithium secondary battery. The thickness D TM may be 2.10 Å or more, and may be 2.13 Å.

[0017] The lithium transition metal oxide contains at least one of nickel (Ni), manganese (Mn), and cobalt (Co) and an additive element (M), and the additive element (M) preferably contains an element having an ionic radius of 0.80 Å to 1.25 Å. Thereby, the positive electrode active material powder of the present disclosure can further improve the capacity retention rate of the lithium secondary battery.

[0018] Examples of the element having an ionic radius of 0.80 Å to 1.25 Å include strontium (Sr), yttrium (Y), lanthanum (La), bismuth (Bi), calcium (Ca), cerium (Ce), gadolinium (Gd), mercury (Hg), holmium (Ho), lutetium (Lu), sodium (Na), neodymium (Nd), lead (Pb), promethium (Pm), strontium (Sr), etc. Among them, the element having the ionic radius preferably contains at least one selected from the group consisting of Y, Sr, and La, and more preferably contains Sr. By the element having the ionic radius containing Sr, the positive electrode active material powder of the present disclosure can further improve the capacity retention rate of the lithium secondary battery.

[0019] The lithium transition metal oxide may be represented by the following formula (I). Formula (I): Li 1+u Ni x Co y Mn z M t O2 In formula (I), the relationships -0.05 ≦ u ≦ 0.50, x + y + z + t = 1, 0.30 ≦ x ≦ 0.90, 0.05 ≦ y ≦ 0.50, 0.05 ≦ z ≦ 0.50, and 0 < t ≦ 0.10 are satisfied. M represents at least one additive element selected from the group consisting of Y, Sr, and La. x may be 0.70 or more. y may be from 0.05 to 0.15. z may be from 0.05 to 0.15. t may be 0 < t ≦ 0.06. M may be Sr.

[0020] The TM particles contained in the positive electrode active material powder may be of one type or at least two types.

[0021] The average particle size of the TM particles may be from 1 μm to 20 μm, or may be from 5 μm to 15 μm. The "average particle size" indicates the particle size (median diameter) corresponding to a cumulative frequency of 50% by volume from the side of fine particles with a small particle size in the volume-based particle size distribution based on the laser diffraction / scattering method.

[0022] The ratio of the TM particles to the total amount of the positive electrode active material powder may be more than 50% by mass, may be 80% by mass or more, or may be 100% by mass.

[0023] (1.2) Other positive electrode active material particles In addition to a plurality of TM particles, the positive electrode active material powder of the present disclosure may also contain a plurality of other positive electrode active material particles. The other positive electrode active material particles may be known positive electrode active material particles different from the TM particles.

[0024] (2) Lithium secondary battery The lithium secondary battery of the present disclosure includes a positive electrode. The positive electrode contains the positive electrode active material powder of the present disclosure. Thereby, the capacity retention rate of the lithium secondary battery of the present disclosure is excellent.

[0025] The lithium secondary battery of the present disclosure generally further includes a negative electrode, an ion conduction medium, in addition to a positive electrode. The ion conduction medium is interposed between the positive electrode and the negative electrode and conducts carrier ions. Examples of the ion conduction medium include non-aqueous electrolytes, non-aqueous gel electrolytes, solid ion conductive polymers, inorganic solid electrolytes, and the like.

[0026] Hereinafter, a lithium secondary battery using a non-aqueous electrolyte (hereinafter also referred to as a "non-aqueous battery") will be described.

[0027] (2.1) Non-aqueous battery The non-aqueous battery includes a negative electrode of the present disclosure, a positive electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte.

[0028] (2.1.1) Positive electrode The positive electrode has a positive electrode composite material layer and may further have a positive electrode current collector (for example, aluminum foil or the like). The positive electrode composite material layer is laminated on at least one main surface of the positive electrode current collector. The positive electrode composite material layer contains the positive electrode active material powder of the present disclosure.

[0029] The positive electrode composite material layer contains the positive electrode active material powder of the present disclosure. The positive electrode active material and the positive electrode composite material layer may further contain a known conductive material (for example, carbon black or the like), lithium phosphate, and a binder (for example, polyvinylidene fluoride or the like).

[0030] (2.1.2) Negative electrode The negative electrode has a negative electrode current collector and may or may not further have a negative electrode composite material layer.

[0031] When the negative electrode does not have a negative electrode composite material layer, the negative electrode current collector includes a main surface on which lithium metal is deposited during charging. Specifically, lithium ions contained in the non-aqueous electrolyte receive electrons on the negative electrode current collector during charging, and lithium metal is deposited. The deposited lithium metal dissolves as lithium ions in the non-aqueous electrolyte during discharge. The lithium ions contained in the non-aqueous electrolyte may be at least one of ions derived from a lithium salt described later and ions supplied from the positive electrode active material during charging.

[0032] When the negative electrode has a negative electrode composite material layer, the negative electrode composite material layer is laminated on at least one main surface of a negative electrode current collector (for example, copper foil or the like). The negative electrode composite material layer contains a negative electrode layer active material (for example, carbon (for example, natural graphite, artificial graphite), a compound capable of alloying with lithium (for example, silicon, tin, etc.)) that can occlude and release charge carriers. The negative electrode composite material layer may further contain a conductive material (for example, acetylene black or the like) for enhancing electron conductivity, a binder (for example, polyvinylidene fluoride or the like), an electrolyte supporting salt (lithium salt) for enhancing ion conductivity, a polymer electrolyte, and an additive (for example, trifluoropropylene carbonate or the like) as necessary. The negative electrode may have a known configuration.

[0033] (2.1.3) Separator The separator maintains the distance between the positive electrode and the negative electrode to prevent the occurrence of a short circuit due to contact and allows lithium ions to pass through. Examples of the separator include a porous resin sheet or a non-woven fabric. Examples of the material of the porous resin sheet include polyolefins (such as polypropylene, polyethylene, etc.). Examples of the material of the non-woven fabric include polypropylene, polyethylene terephthalate, methyl cellulose, etc. The separator may have a known configuration.

[0034] (2.1.4) Non-aqueous electrolyte The non-aqueous electrolyte may contain a non-aqueous solvent and a lithium salt. Examples of the lithium salt include LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, LiN(CF3SO2)2, etc. Examples of the non-aqueous solvent include cyclic carbonates (such as ethylene carbonate, etc.), chain carbonates (such as dimethyl carbonate, ethyl methyl carbonate, etc.), cyclic esters (such as γ-butyrolactone, γ-valerolactone, etc.), chain esters (such as methyl formate, methyl acetate, etc.), ethers (such as dimethoxyethane, ethoxymethoxyethane, etc.), etc. The non-aqueous electrolyte may contain an additive (such as vinylene carbonate, lithium bis(oxalato)borate, etc.).

[0035] (2.1.5) Case Non-aqueous batteries usually have a case. The case houses a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. The case is not particularly limited, and examples include a laminate film (e.g., an aluminum sheet, etc.), a battery can (e.g., cylindrical, rectangular, coin-shaped, etc.).

Examples

[0036] Hereinafter, the present disclosure will be described in more detail with reference to examples, but the invention of the present disclosure is not limited to these examples only.

[0037] [1] Examples 1 to 5, Comparative Example 2, Comparative Example 4, and Comparative Example 5 [1.1] Raw material dissolution Nickel sulfate (NiSO4), cobalt sulfate (CoSO4), and manganese sulfate (MnSO4) were dissolved in ion-exchanged water to obtain an NCM aqueous solution. The molar ratio (Ni:Co:Mn) of Ni, Co, and Mn was 8:1:1. The total concentration of nickel sulfate, cobalt sulfate, and manganese sulfate in the NCM aqueous solution was 0.2 mol%.

[0038] [1.2] Hydrothermal synthesis A certain amount of the NCM aqueous solution and ammonia (NH3) aqueous solution were placed in a reaction vessel, and nitrogen substitution was performed while stirring with a stirrer. Thereby, a mixed aqueous solution was obtained. Sodium hydroxide (NaOH) was added to the reaction vessel to make the pH of the mixed aqueous solution alkaline. While controlling the pH and temperature of the mixed aqueous solution in the reaction vessel to be constant, a precipitation reaction was allowed to proceed to precipitate NCM hydroxide. After the completion of the precipitation reaction, dehydration was carried out under the following temperature and pressure conditions to perform hydrothermal synthesis (precalcination). Thereby, a hydrothermal synthesis product was obtained.

[0039] <Conditions of hydrothermal synthesis> · Temperature: 120°C to 220°C · Time: 4 hours to 10 hours · Pressure: 0.2 MPa to 1.0 MPa

[0040] After cooling the hydrothermal synthesis product, the NCM hydroxide powder was taken out from the hydrothermal synthesis product by filtration, ion-exchanged water was added and dispersed with a spoon, and then washed with water. The washed product was filtered to take out the NCM hydroxide powder. It was dried at 110 °C for 12 hours to evaporate the moisture. Thereby, a dried product of the NCM hydroxide powder was obtained.

[0041] [1.3] Mixing of Li raw materials The additive elements shown in Table 1, the dried product of the NCM hydroxide powder, and the Li raw material (lithium carbonate (Li2CO3)) were mixed in a mortar at the ratios shown in Table 1. It was fired in a firing furnace (muffle furnace) at 800 °C to 1100 °C for 10 hours. It was pulverized in a mortar and crushed to a predetermined particle size. Thereby, a positive electrode active material powder was obtained. The positive electrode active material powder was composed of a plurality of particles made of a lithium transition metal oxide having a layered crystal structure.

[0042] [1.4] Thickness D of the transition metal layer TM Measurement [1.4.1] XRD measurement XRD (X-ray diffraction) measurement was performed on the positive electrode active material powder. Thereby, synchrotron radiation XRD diffraction data was obtained. For the XRD measurement, beamline BL5S2 of the Aichi Synchrotron Light Center was used. Specifically, the positive electrode active material powder was filled into a capillary to prepare a capillary sample. The capillary sample was set in a measuring jig, and the XRD measurement of the positive electrode active material powder was performed under the following measurement conditions.

[0043] [1.4.1.1] Measurement conditions · Measurement energy: 15 keV · Threshold: 7.5 keV to 10 keV · 2θ range: 10° to 90°

[0044] [1.4.2] Thickness D of the transition metal layer TM Rietveld analysis was performed on the synchrotron XRD diffraction data. The general-purpose Rietveld analysis program "Fullprof" was used for the Rietveld analysis. By using "Fullprof", the lattice constant and atomic coordinates of the substance can be calculated. Specifically, when the Chi 2 value takes the minimum value, the c-axis length (C h ) and the z-coordinate of oxygen (Z OXY ) were determined. "Chi 2 " indicates the value of the convergence index obtained by fitting the synchrotron XRD diffraction data using the least squares method. "When the Chi 2 value takes the minimum value" indicates the time when the separation between the synchrotron XRD diffraction data and the profile fitting is minimized.

[0045] According to the following formula (A), the thickness D TM (interlayer distance) of the transition metal layer contained in the lithium transition metal oxide was calculated. The measurement results are shown in Table 1.

[0046] Formula (A): Thickness D of the transition metal layer TM = 2 × [(1 / 3) - Z OXY × C h

[0047] [2] Comparative Example 1 and Comparative Example 3 [2.1] Raw material dissolution In the same manner as in Example 1, an NCM aqueous solution was obtained.

[0048] [2.2] Crystallization A reaction solution with adjusted pH using sulfuric acid and aqueous ammonia was prepared in a reaction vessel. An aqueous sodium hydroxide solution was prepared as a pH adjusting solution. While stirring the reaction solution, the NCM aqueous solution was added to the reaction solution at a predetermined rate and neutralized with the pH adjusting solution. As a result, a crystallized product was obtained. The crystallized product was washed with water, filtered, and dried to obtain composite hydroxide particles (precursor particles).

[0049] [2.3] Li raw material mixing The additive elements shown in Table 1, the obtained precursor particles, and the Li raw material (Li2CO3) were mixed in a mortar at the ratios shown in Table 1. They were fired in a firing furnace (muffle furnace) at 700 °C for 10 hours. Then, they were pulverized in a mortar and crushed to a predetermined particle size. As a result, a positive electrode active material powder was obtained. The positive electrode active material powder was composed of a plurality of particles made of a lithium transition metal oxide having a layered crystal structure.

[0050] [2.4] Thickness D of the transition metal layer TM Measurement In the same manner as in Example 1, the thickness D of the transition metal layer contained in the lithium transition metal oxide TM (interlayer distance) was calculated. The measurement results are shown in Table 1.

[0051] [3] Evaluation A lithium secondary battery was fabricated as follows, and the capacity retention rate was measured.

[0052] [3.1] Lithium secondary battery [3.1.1] Positive electrode The positive electrode active material powder, acetylene black as a conductive material, and a binder-containing solution were mixed to prepare a positive electrode slurry. The "binder-containing solution" refers to a mixed solution of a binder and a solvent. Using a film applicator with a film thickness adjustment function (manufactured by Allgood Co., Ltd.), the positive electrode slurry was applied to a positive electrode current collector to obtain a coated product with the positive electrode current collector. Using a dryer, the coated product with the positive electrode current collector was dried under the conditions of 80 °C for 5 minutes to obtain a positive electrode. The positive electrode was formed by laminating a positive electrode current collector and a positive electrode composite layer in this order.

[0053] [3.1.2] Negative electrode Natural graphite as a negative electrode active material, acetylene black as a conductive material, and a binder-containing solution were mixed to prepare a negative electrode slurry. The negative electrode slurry was applied to a negative electrode current collector to obtain a coated product with the negative electrode current collector. Using a dryer, the coated product with the negative electrode current collector was dried under the conditions of 80 °C for 5 minutes to obtain a negative electrode. The negative electrode was formed by laminating a negative electrode current collector and a negative electrode composite layer in this order.

[0054] [3.1.3] Non-aqueous electrolyte LiPF6 as an electrolyte was added to the mixed solvent to obtain a non-aqueous electrolyte. The mixed solvent consisted of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). The volume ratio of EC:DMC:EMC (volume %) was 3:4:3. The concentration of LiPF6 in the non-aqueous electrolyte was 1.0 M (mol / L).

[0055] [3.1.4] Separator A known separator was prepared as the separator.

[0056] [3.1.5] Battery A lithium secondary battery was fabricated by using a positive electrode and a negative electrode, opposing them through a separator, and sealing them with a laminate together with the non-aqueous electrolyte.

[0057] [3.2] Capacity retention rate For the lithium secondary battery, constant current constant voltage charging (CCCV: Constant Current, Constant Voltage) at 0.3C was performed for 100 cycles. The battery capacity at the first cycle (hereinafter also referred to as "initial capacity") and the battery capacity after 100 cycles (hereinafter also referred to as "capacity after 100 cycles") were measured. The capacity retention rate was calculated from the following formula (B). The results are shown in Table 1. The acceptable range of the capacity retention rate is more than 77%.

[0058] Formula (B): Capacity retention rate (%) = (Capacity after 100 cycles / Initial capacity) × 100

[0059] [4] Results

Table 1

[0060] In Table 1, the ratio of Example 4 indicates the ratio obtained by adding 5 mol% of the additive element to a total of 100 mol% of the molar ratio of Ni:Co:Mn = 8:1:1.

[0061] [4.1] Comparative Examples 1 to 5 In Comparative Examples 1 to 5, the thickness D of the transition metal layer TM was outside the range of 2.06 Å to 2.19 Å. Therefore, the capacity retention rates of Comparative Examples 1 to 5 were not more than 77%. As a result, it was found that the positive electrode active material powders of Comparative Examples 1 to 5 were not "positive electrode active material powders capable of improving the capacity retention rate of a lithium secondary battery."

[0062] [4.2] Examples 1 to 5 In Examples 1 to 5, the thickness D of the transition metal layer TM was within the range of 2.06 Å to 2.19 Å. Therefore, the capacity retention rates of Examples 1 to 5 were more than 77%. As a result, it was found that the positive electrode active material powders of Examples 1 to 5 were "positive electrode active material powders capable of improving the capacity retention rate of a lithium secondary battery."

Claims

1. A positive electrode active material powder used in a lithium secondary battery, comprising a plurality of particles composed of a lithium transition metal oxide having a layered crystal structure, The thickness D of the transition metal layer contained in the lithium transition metal oxide ＴＭ is from 2.06 Å to 2.19 Å, The thickness D ＴＭ is a positive electrode active material powder showing a value calculated by Rietveld analysis using the synchrotron radiation X-ray diffraction profile of the particles.

2. The thickness D ＴＭ The positive electrode active material powder according to claim 1, wherein the thickness is 2.09 Å to 2.17 Å.

3. wherein the lithium transition metal oxide contains at least one of nickel (Ni), manganese (Mn), and cobalt (Co) and an additive element (M), The positive electrode active material powder according to claim 1, wherein the additive element (M) contains an element having an ionic radius of 0.80 Å to 1.25 Å.

4. The positive electrode active material powder according to claim 3, wherein the element having the ionic radius contains Sr.

5. A lithium secondary battery comprising a positive electrode containing the positive electrode active material powder according to any one of claims 1 to 4.

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