Cathode active material, cathode active material slurry, cathode, lithium-ion secondary battery and method for manufacturing cathode active material

Abstract

The present invention provides a positive electrode active material for a lithium-ion secondary battery having excellent capacity characteristics and electrode resistance characteristics, a positive electrode active material slurry, a positive electrode, a lithium-ion secondary battery, and a method for manufacturing a positive electrode active material. The positive electrode active material according to the present invention comprises a core containing a lithium transition metal oxide and a coating portion containing iodine and boron, which at least partially covers the surface of the core.

Description

Technology Field

[0001] Embodiments of the present invention relate to a positive electrode active material, a positive electrode active material slurry, a positive electrode, a lithium-ion secondary battery, and a method for manufacturing a positive electrode active material.

[0002] This application claims priority based on Japanese application No. 2021-212767 filed on December 27, 2021, and all contents disclosed in the specification of said application are incorporated into this application. Background Technology

[0003] As technology for mobile devices advances, the demand for rechargeable batteries as an energy source is rapidly increasing. Among these rechargeable batteries, lithium-ion batteries, which possess high energy density and voltage, long cycle life, and low self-discharge rates, are commercially available and widely used. Currently, research aimed at increasing the capacity of such lithium-ion batteries is actively underway.

[0004] In increasing the capacity of lithium-ion secondary batteries, for example, a technique is known to form a film made of boron material on the surface of the electrode active material. Prior art literature

[0005] Patent Document 1: Japanese Patent No. 6284542 Patent Document 2: Japanese Patent Publication No. 2017-152275 Patent Document 3: Japanese Patent Publication No. 2019-175872 The problem to be solved

[0006] However, when such a film is formed, there are cases where sufficient electrode resistance characteristics cannot be obtained. Therefore, it is required to achieve both excellent capacitance characteristics and electrode resistance characteristics.

[0007] The problem that the present invention aims to solve is to provide a positive active material for a lithium-ion secondary battery, a positive active material slurry, a positive, a lithium-ion secondary battery, and a method for manufacturing a positive active material, which have excellent capacity characteristics and electrode resistance characteristics. means of solving the problem

[0008] According to one embodiment of the present invention, a positive electrode active material is provided comprising a core containing a lithium transition metal oxide and a coating portion containing iodine and boron as a coating portion that at least partially covers the surface of the core.

[0009] In this specification, "lithium transition metal oxide" means a compound containing lithium and a transition metal and having transition metal-oxygen bonds, and includes those containing typical metal elements such as aluminum or non-metal elements other than oxygen such as iodine. "To cover" means to cover the surface of an object at least partially, and includes cases where it is chemically bonded to the particle surface or physically covers the particle surface without chemical bonding. For example, if peaks originating from iodine and boron are detected in X-ray photoelectron spectroscopy (XPS) of the surface of an active material particle, it can be said that "a coating containing iodine and boron is formed."

[0010] In the positive active material according to the above form, the coating may contain iodine having an oxidation number of +5 or higher and +7 or lower.

[0011] In the positive electrode active material according to the above form, I3d observed by X-ray photoelectron spectroscopy analysis of the positive electrode active material 5 / 2 The spectrum of may have a peak between 622 eV and 626 eV.

[0012] In the positive electrode active material according to the above form, the iodine content may be 0.001 to 5 parts by mass for 100 parts by mass of lithium transition metal oxide.

[0013] In the positive electrode active material according to the above form, the boron content may be 0.001 to 5 parts by mass for 100 parts by mass of lithium transition metal oxide.

[0014] According to another embodiment of the present invention, a positive electrode active material slurry for a lithium-ion secondary battery is provided, comprising a positive electrode active material according to the above embodiment.

[0015] According to another embodiment of the present invention, a positive electrode for a lithium-ion secondary battery is provided, wherein a positive electrode active material layer comprising a positive electrode active material according to the above embodiment is formed on a current collector.

[0016] In the anode according to the above form, the anode active material layer may further include a conductive material comprising carbon nanotubes.

[0017] According to another embodiment of the present invention, a lithium-ion secondary battery having a positive electrode according to the above embodiment is provided.

[0018] According to another embodiment of the present invention, a method for manufacturing an anode active material is provided, comprising the steps of obtaining a mixture containing a lithium transition metal oxide, iodine, and boron, and calcining the mixture.

[0019] A method for manufacturing a positive electrode active material according to the above form may include the step of adding an iodine material containing iodine as a raw material for a mixture. The iodine material is one selected from the group consisting of elemental iodine (I2), lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI), iodoform (CHI3), carbon tetraiodide (Cl4), ammonium iodide (NH4I), iodic acid (HIO3), lithium iodate (LiIO3), sodium iodate (NaIO3), potassium iodate (KIO3), ammonium iodate (NH4IO3), metaperiodic acid (HIO4), orthoperiodic acid (H5IO6), lithium periodate (LiIO4), sodium periodate (NaIO4), potassium periodate (KIO4), iodine(IV) oxide (I2O4), iodine(V) oxide (I2O5), and iodine(IV, V) oxide (I4O9). It may include the above. In this specification, 'iodine material' means any material containing iodine.

[0020] In the method for manufacturing a positive electrode active material according to the above form, the iodine material may contain iodine (I2).

[0021] A method for manufacturing a positive electrode active material according to the above form may include adding a boron material containing boron as a raw material for a mixture. The boron material may be H3BO3, HBO2, B2O3, C6H5B(OH)2, (C6H5O)3B, [CH3(CH2)3O]3B, C 13 H 19 It may include one or more selected from the group consisting of BO3, C3H9B3O6, and (C3H7O)3B. In this specification, "boron material" means any material containing boron.

[0022] In the method for manufacturing a positive electrode active material according to the above form, the boron material may contain boric acid (H3BO3).

[0023] A method for manufacturing a positive electrode active material according to the above form may include a step of calcining the mixture at a calcination temperature of 150°C or higher and 500°C or lower. Effects of the invention

[0024] According to the present invention, a positive active material for a lithium-ion secondary battery, a positive active material slurry, a positive, a lithium-ion secondary battery, and a method for manufacturing a positive active material can be provided, which have excellent capacity characteristics and electrode resistance characteristics. Brief explanation of the drawing

[0025] Figure 1 shows a portion of the XPS spectra of the positive electrode active materials of Example 1-1, Comparative Example 1-1, Comparative Example 2-1, and Comparative Example 3-1. Figure 2 shows a portion of the XPS spectra of the positive electrode active materials of Example 1-1, Comparative Example 1-1, Comparative Example 2-1, and Comparative Example 3-1. Figure 3 shows the trend of battery capacity change during the 1st to 50th charge-discharge cycles of Example 1-1 and Example 2, and Comparative Example 1-1, Comparative Example 2-1, Comparative Example 3-1, and Comparative Example 4. Figure 4 shows the trend of changes in DC resistance during the 1st to 200th charge-discharge cycles of Example 1-1 and Example 2, and Comparative Example 1-1, Comparative Example 2-1, Comparative Example 3-1, and Comparative Example 4. Figure 5 shows the trend of battery capacity change during the 1st to 50th charge-discharge cycles of Example 1-2, Comparative Example 1-2, Comparative Example 2-2, and Comparative Example 3-2. Figure 6 shows the trend of changes in DC resistance during the 1st to 200th charge-discharge cycles of Example 1-2, Comparative Example 1-2, Comparative Example 2-2, and Comparative Example 3-2. Figure 7 shows a portion of the XPS spectrum of the positive active material of Reference Example 1. Specific details for implementing the invention

[0026] Embodiments of the present invention are described below. However, the present invention is not limited thereto.

[0027] Regarding the problem of electrode resistance characteristics that may arise with the increase in capacity of lithium-ion secondary batteries, a lithium-ion secondary battery utilizing a lithium transition metal oxide with a high nickel content as the cathode material is explained as an example.

[0028] Li as a cathode material for lithium-ion secondary batteries a Ni x Co y Mn zIt is known that in lithium nickel cobalt manganese ternary cathode active materials such as O2, high capacity can be achieved by increasing the amount of nickel in the composition. In fact, as there is always a demand from the market for high capacity in lithium-ion secondary batteries, the development of Ni-rich cathode active materials with high capacity per unit mass in the operating voltage range of 3.0 V to 4.2 V is being actively pursued to replace the conventionally used LiCoO2. However, in lithium nickel cobalt manganese ternary cathode active materials, as the amount of Ni increases, problems such as gas generation at high temperatures and reduced stability during charging occur, which are major challenges in actual battery application.

[0029] In response to these challenges, methods for forming a film on the particle surface of the cathode active material have been proposed to suppress gas generation and achieve stable cycle behavior. However, in Ni-rich cathodes with a high Ni content, the increase in resistance components due to such film treatment is significantly affected, and depending on the treatment, this can lead not only to a decrease in discharge capacity or rate characteristics but also to a deterioration in cycle characteristics. In this regard, as disclosed in Patent Documents 1 and 2, a technique for forming a boron-based film is known, but its effectiveness for Ni-rich cathodes is limited. Meanwhile, as disclosed in Patent Document 3, forming another film in addition to the boron-based film is also being considered. However, the increase in electrode resistance due to the overlapping of films can also be a practical challenge. Thus, the reality is that there are very limited film technologies capable of achieving both excellent capacity characteristics and electrode resistance characteristics for active materials currently in use or under development.

[0030] The inventors have discovered that, in a lithium-ion secondary battery, when using a positive electrode active material containing a lithium transition metal oxide, a lithium-ion secondary battery having excellent capacity characteristics and electrode resistance characteristics can be obtained by forming a coating containing iodine and boron on the surface of a core containing a lithium transition metal oxide, and have reached the completion of the present invention.

[0031] [Cathode active material]

[0032] According to one embodiment, a positive active material is provided comprising a core containing a lithium transition metal oxide and a coating portion containing iodine and boron, which at least partially covers the surface of the core. Preferably, the positive active material is a positive active material for a lithium-ion secondary battery.

[0033] As the positive electrode active material, a lithium transition metal oxide capable of absorbing and releasing lithium, containing iodine and boron, may be used. The positive electrode active material may be in the form of particles having a core-shell structure formed by a core and a coating. The coating may cover the entire core or cover only a part of the outer surface of the core. The coating may be connected as a whole or may have multiple island-shaped portions separated from each other. The coating may cover a single core or cover two or more cores.

[0034] (Core)

[0035] The core of the positive electrode active material contains a lithium transition metal oxide. For example, the core is a particle of lithium transition metal oxide. Meanwhile, the core may contain a material other than a lithium transition metal oxide. The shape of the core is not particularly limited and may be any shape, such as spherical, rectangular, or polygonal, and the particle shape is not limited. For example, the core may be formed as a single particle or as an aggregate, such as a secondary particle formed by the aggregation of primary particles. The size of the core is not particularly limited, but may be, for example, 0.01 μm or more and 30 μm or less, or 0.1 μm or more and 10 μm or less.

[0036] The core of the positive electrode active material may include, for example, a lithium transition metal oxide containing nickel, and preferably may include a lithium transition metal oxide with a high nickel content. Here, "high nickel content" means containing 50 mol% or more of nickel based on the total amount of transition metals. As described above, a high-nickel lithium transition metal oxide containing 50 mol% or more of nickel is desirable in that it suppresses the increase in electrode resistance. Therefore, by using the positive electrode active material according to the present embodiment to improve electrode resistance characteristics (i.e., by lowering the rate of increase in resistance), it becomes possible to achieve both high capacity of the lithium-ion secondary battery and improved electrode resistance characteristics. For example, the core may include a lithium transition metal oxide containing 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more of nickel based on the total amount of transition metals.

[0037] (Lithium transition metal oxide)

[0038] Examples of lithium transition metal oxides include lithium-manganese oxides (e.g., LiMnO2, LiMnO3, LiMn2O3, LiMn2O4, etc.); lithium-cobalt oxides (e.g., LiCoO2, etc.); lithium-nickel oxides (e.g., LiNiO2, etc.); lithium-copper oxides (e.g., Li2CuO2, etc.); lithium-vanadium oxides (e.g., LiV3O8, etc.); and lithium-nickel-manganese oxides (e.g., LiNi 1-z Mn z O2(0<z<1), LiMn 2-z Ni z O4 (0 < z < 2), etc.); lithium-nickel-cobalt oxides (e.g., LiNi 1-y Co y O2 (0 < y < 1), etc.); lithium-manganese-cobalt oxides (e.g., LiCo 1-z Mn z O2(0<z<1), LiMn 2-y Co y O4 (0 < y < 2), etc.); lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni x Co y Mn z )O2(0<x<1, 0<y<1, 0<z<1, x+y+z=1), Li(Ni x Co y Mn z )O4(0<x<2, 0<y<2, 0<z<2, x+y+z=2) etc.); lithium-nickel-cobalt-metal(M) oxide (e.g., Li(Ni x Co y Mn z M w )O2(M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and 0<x<1, 0<y<1, 0<z<1, 0<w<1, x+y+z+w=1), etc.); Li-excess solid solution anode (e.g., pLi2MnO3-(1-p)Li(Ni x Co y Mn zExamples include )O2(0<x<1, 0<y<1, 0<z<1, x+y+z=1, 0<p<1); compounds in which a transition metal element among these compounds is partially substituted with one or more other metal elements. The positive electrode active material layer may include any one or two or more of these compounds, but is not limited to them.

[0039] In particular, as an example of a lithium transition metal oxide with a high nickel content that is effective for increasing the capacity of batteries, Li a NiO2(0.5≤a≤1.5); Li a (Ni x Co y Mn z )O2(0.5≤a≤1.5, 0.5≤x<1, 0<y<0.5, 0<z<0.5, x+y+z=1); Li a (Ni x Co y Mn z )O2(0.7≤x<1, 0<y<0.3, 0<z<0.3, x+y+z=1); Li a (Ni x Co y Mn z )O2(0.8≤x<1, 0<y<0.2, 0<z<0.2, x+y+z=1); Li a (Ni x Co y Mn z )O2(0.9≤x<1, 0<y<0.1, 0<z<0.1, x+y+z=1); Li a Ni 1-y Co y O2(0.5≤a≤1.5, 0<y≤0.5); Li a Ni 1-z Mn z O2(0.5≤a≤1.5, 0<z≤0.5); Li a (Ni x Co y Mn z )O4(0.5≤a≤1.5, 1≤x<2, 0<y<1, 0<z<1, x+y+z=2); Li a( Ni x Co y M w)O2(M is one or more elements selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, Mo, Zr, Zn, Ga, and In, and 0.5≤a≤1.5, 0.5≤x<1, 0<y<0.5, 0<w<0.5, x+y+w=1); Li a (Ni x Co y Mn z M w Examples include )O2(M is one or more elements selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, Mo, Zr, Zn, Ga, and In, and 0.5≤a≤1.5, 0.5≤x<1, 0<y<0.5, 0<z<0.5, 0<w<0.5, x+y+z+w=1); compounds in which a transition metal atom in these compounds is at least partially substituted with one or more other metal elements (e.g., one or more of Al, Fe, V, Cr, Ti, Ta, Mg, Mo, Zr, Zn, Ga, and In); and compounds in which an oxygen atom in these compounds is partially substituted with one or more other non-metal elements (e.g., one or more of P, F, S, and N). The positive electrode active material may include one or more of these, but is not limited to them. In addition, even within the same particle, there may be a distribution of substituted concentrations in the interior and the surface layer. In addition, it may be coated on the surface of the particle. Examples include a surface coated with a metal oxide, a lithium transition metal oxide, a polymer, etc., but are not limited to these.

[0040] In particular, in terms of improving the capacity characteristics and stability of the battery, Li a NiO2, Li a (Ni 0.5 Mn y Co z )O2(y+z=0.5), Li a (Ni 0.6 Mn y Coz )O2(y+z=0.4), Li a (Ni 0.7 Mn y Co z )O2(y+z=0.3), Li a (Ni 0.8 Mn y Co z )O2(y+z=0.2), Li a (Ni 0.8 Co y Mn z Al w )O2(y+z+w=0.2), Li a (Ni 0.85 Co y Mn z )O2(y+z=0.15), Li a (Ni 0.85 Co y Mn z Al w )O2(y+z+w=0.15), Li a (Ni 0.9 Co y Mn z )O2(y+z=0.1), Li a (Ni 0.9 Co y Mn z Al w )O2(y+z+w=0.1), Li a (Ni 0.9 Co y Mn z )O2(y+z=0.1), Li a (Ni 0.95 Co y Mn z Al w )O2(y+z+w=0.05) etc. are preferred. Here, the value of a is, for example, 0.5≤a≤1.5, and preferably 1.0≤a≤1.5.

[0041] More specifically, LiNiO2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni0.7 Mr 0.15 Co 0.15 )O2, Li(Ni 0.8 Mr 0.1 Co 0.1 )O2, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, Li(Ni 0.8 Co 0.1 Mr 0.05 Al 0.05 )O2, Li(Ni 0.85 Co 0.10 Mr 0.05 )O2, Li(Ni 0.85 Co 0.10 Mr 0.03 Al 0.02 )O2, Li(Ni 0.9 Co 0.05 Mr 0.05 )O 2, Li (Ni 0.9 Co 0.05 Al 0.05 )O2, Li(Ni 0.95 Co 0.03 Mr 0.02 )O2, Li(Ni 0.95 Co 0.03 Al 0.02 )O2 is preferable.

[0042] (피복부)

[0043] The coating of the positive electrode active material covers part or all of the core surface. The coating contains iodine and boron. The coating is obtained by mixing and calcining a lithium transition metal oxide, an iodine material, and a boron material. The coating in the positive electrode active material may exist independently of the core containing the lithium transition metal oxide, but may be chemically or physically bonded at least partially to the surface of the lithium transition metal oxide particles forming the core. It is preferable that the coating be in contact at least partially with the lithium transition metal oxide particles. The coating may be included at least partially within the structure of the lithium transition metal oxide. Meanwhile, the material of the coating is not limited to independent chemical species as a compound, and may be any chemical species such as ions, atoms, or atomic groups. The thickness of the coating is not particularly limited, but since the electrical conductivity of the core surface is inhibited when it is completely covered or when the coating layer is thick, a thickness of 0.1 nm or more and 10 nm or less is preferred, and a thickness of 3 nm or more and 5 nm or less is more preferred. In addition, to suppress the decrease in electrical conductivity, it is also effective to use carbon nanotubes that electrically connect particles.

[0044] The content of the coating portion in the positive electrode active material is, for example, 0.001 mass% or more and 10.0 mass% or less, preferably 0.01 mass% or more and 1.0 mass% or less, more preferably 0.02 mass% or more and 0.5 mass% or less, and even more preferably 0.05 mass% or more and 0.2 mass% or less. If the content of the coating portion is 0.001 mass% or more, an improvement in the cycle characteristics or electrode resistance characteristics of the battery is expected.

[0045] (Iodine component)

[0046] The coating portion of the anode active material after calcination contains iodine having a positive oxidation number. The coating portion contains, for example, iodine having an oxidation number of +1 or more and +7 or less, preferably iodine having an oxidation number of +2 or more and +7 or less, more preferably iodine having an oxidation number of +5 or more and +7 or less, and even more preferably iodine having an oxidation number of +7. Iodine having a positive oxidation number often possesses strong oxidizing power. For example, iodine compounds having a positive oxidation number include iodine oxo acids such as iodic acid (HIO3), metaperiodic acid (HIO4), and orthoperiodic acid (H5IO6); Examples include iodine oxosates such as lithium iodate (LiIO3), sodium iodate (NaIO3), potassium iodate (KIO3), ammonium iodate (NH4IO3), lithium periodate (LiIO4), sodium periodate (NaIO4), and potassium periodate (KIO4); and iodine oxides such as iodine(IV) oxide (I2O4), iodine(V) oxide (I2O5), and iodine(IV, V) oxide (I4O9). The coating may contain periodate ions or hydrogen periodate ions. Examples of periodate ions include metaperiodate ions IO4 - , orthoperiodate ion IO6 5- Examples include hydrogen periodate ions such as HIO6 4- , H2IO6 3- , H3IO6 2- , H4IO6 - Examples include the above. In addition, the iodine contained in the coating may be bonded to the constituent elements of the lithium transition metal oxide (lithium, transition metal, oxygen, etc.) or to iodine. For example, the coating may contain iodate ions (IO3) bonded to the metal ions of the lithium transition metal oxide. - Alternatively, it may contain periodate ions. For example, the coating comprises a bond between a metal cation, such as a lithium transition metal oxide, and a periodate ion, for example, a metal cation and a periodate ion IO4 -It may include a combination of

[0047] In the positive electrode active material, the iodine content relative to 100 parts by mass of lithium transition metal oxide is, for example, 0.001 parts by mass to 5 parts by mass. If the iodine content is 0.001 parts by mass or more, an improvement in the electrode resistance characteristics or cycle characteristics of the battery is expected. If the iodine content is 5 parts by mass or less, it is thought that side reactions caused by excessive coating will be suppressed. The iodine content relative to 100 parts by mass of lithium transition metal oxide is preferably 0.005 parts by weight or more and 2 parts by mass or less, more preferably 0.01 parts by mass or more and 1 part by mass or less, and even more preferably 0.05 parts by mass or more and 0.5 parts by mass or less.

[0048] (Boron component)

[0049] The coating portion of the positive electrode active material after calcination contains boron having an oxidation state of +3. Examples of boron compounds contained in the coating portion include boric acid, borates, polyboric acid, polyborates, boron oxide, etc. The boron contained in the coating portion may be bonded to constituent elements of the lithium transition metal oxide (lithium, transition metal, oxygen, etc.) or iodine. For example, the coating portion may contain borate ions bonded to metal ions of the lithium transition metal oxide (in this specification, BO3 3- , HBO3 2- , H2BO3 - It may include (collectively referred to as ‘borate ions’). For example, the coating may include a combination of a metal cation, such as a lithium transition metal oxide, and a borate ion. For example, the coating may include lithium metaborate (LiBO2). Additionally, Patent Document 1 suggests that boric acid reacts with residual lithium to form lithium borate.

[0050] In the positive electrode active material, the boron content relative to 100 parts by mass of lithium transition metal oxide is, for example, 0.001 parts by mass to 5 parts by mass. If the boron content is 0.001 parts by mass or more, an improvement in the capacity characteristics or cycle characteristics of the battery is expected. If the boron content is 5 parts by mass or less, it is thought that side reactions caused by excessive coating will be suppressed. The boron content relative to 100 parts by mass of lithium transition metal oxide is preferably 0.01 parts by weight or more and 3 parts by mass or less, more preferably 0.05 parts by mass or more and 2 parts by mass or less, and even more preferably 0.1 parts by mass or more and 1 part by mass or less.

[0051] (XPS spectrum of positive electrode active material)

[0052] The spectrum observed by X-ray photoelectron spectroscopy (XPS) of the positive electrode active material is I3d of iodine. 5 / 2 It has a peak originating from the electron. -(CH2) n - When charging correction is performed with the energy of the origin C1s peak top set to 284.6 eV, I3d 5 / 2 The spectrum of has a peak at, for example, 622 eV or higher and 626 eV or lower. The position of the peak is preferably at 623 eV or higher and 625 eV or lower, and more preferably at 623.5 eV or higher and 624.5 eV or lower. Here, 'position of the peak' refers to the position (energy) of the peak's maximum value. This peak originates from iodine having a positive oxidation number. This peak originates from, for example, iodine having an oxidation number of +1 or higher and +7 or lower, preferably iodine having an oxidation number of +3 or higher and +7 or lower, more preferably iodine having an oxidation number of +5 or higher and +7 or lower, and even more preferably iodine having an oxidation number of +7.

[0053] The spectrum observed by X-ray photoelectron spectroscopy (XPS) of the cathode active material has a peak originating from the B1s electrons of boron. … -(CH2)n - When charging correction is performed with the energy of the C1s peak top of the source set to 284.6 eV, the spectrum of the B1s electrons of boron has a peak at, for example, between 188.5 eV and 195.0 eV.

[0054] It is presumed that the coating can improve the capacity characteristics and electrode resistance characteristics of the battery and suppress cycle degradation through the following mechanism. However, the following is merely an exemplary conjecture to aid in understanding the invention and does not limit the invention.

[0055] When lithium transition metal oxide, iodine material, and boron material are mixed and calcined, it is believed that, although the details are unclear, the iodine material and boron material undergo chemical reactions on the lithium transition metal oxide, either individually or in combination, to form a coating containing iodine and boron. Although the details regarding the function of the coating within the cathode active material are also unclear, the coating thus produced may contain iodine, which has a positive oxidation state and strong electron-attracting power, as previously mentioned. According to past knowledge, it is known that mixing LiI into a solid electrolyte attracts electrons to I, which has high electronegativity, thereby improving Li ion conductivity. From this, it is presumed that during the charging process, the Li conductivity is enhanced by the coating, thereby promoting the redox reaction of the cathode active material. As a result, side reactions such as the decomposition of the electrolyte during the charging process are suppressed, thereby preventing an increase in electrode resistance on the cathode side and consequently leading to a stable long-term cycle.

[0056] In addition, the generated coating is thought to at least partially cover the surface of the core containing the lithium transition metal oxide. Since this coating inhibits the chemical reaction between the lithium transition metal oxide and the electrolyte, thereby suppressing the formation of by-products, it is presumed that adverse effects, such as inhibition of the battery reaction or an increase in the battery's electrical resistance caused by the formation of by-products on the positive active material during repeated charging and discharging, can be suppressed.

[0057] As explained by the embodiments described below, when a boron-derived film is formed, a tendency for the electrode resistance to increase was observed; however, it was also confirmed that the increase in electrode resistance was suppressed by the inclusion of iodine in the coating. Through this function of iodine, it is possible to suppress the increase in electrode resistance caused by the coating while realizing the effects of improving and stabilizing battery performance by the coating. Meanwhile, it is not certain whether the boron-containing film and the iodine-containing film are formed individually and function independently, or whether there is any interaction between boron and iodine.

[0058] In particular, lithium transition metal oxides with a high nickel content tend to be significantly affected when electrode resistance increases. Generally, metal oxide films made of insulating materials such as Al2O3 are effective for materials like lithium cobalt oxide; however, for Ni-containing layered oxides, such metal oxides often cause surface resistance to rise, leading to increased electrode resistance and consequently, failure to achieve sufficient battery performance. On the other hand, it is known that the effect of boron films on surface resistance is smaller compared to metal oxides and is effective even for Ni-containing layered oxide materials. However, in high-nickel lithium transition metal oxides, even a slight increase in resistance caused by boron can have an impact, resulting in a failure to achieve sufficient battery performance. In this regard, by forming a coating containing boron and iodine as described above, it is possible to achieve both capacity and electrode resistance characteristics even when using high-nickel lithium transition metal oxides, which are susceptible to the influence of electrode resistance. Generally, batteries using high-nickel lithium transition metal oxides tend to have higher capacities, making this advantageous in terms of increasing battery capacity.

[0059] [Method for manufacturing positive electrode active material]

[0060] According to one embodiment, a method for manufacturing an anode active material is provided, comprising the steps of obtaining a mixture containing a lithium transition metal oxide, iodine, and boron, and calcining the obtained mixture.

[0061] (1) Mixing

[0062] In the mixing process, at least one type of lithium transition metal oxide, iodine material, and boron material are mixed. For example, in the mixing process, the lithium transition metal oxide, iodine material, and boron material can all be mixed in a solid state. For example, a powdered mixture can be obtained by mixing powdered lithium transition metal oxide, iodine material, and boron material. Hereinafter, the obtained mixture is referred to as the "pre-calcination mixture." The specific mixing method is not particularly limited and can be carried out using any existing method. The mixing step may be performed in the atmosphere or under other atmospheres, such as an inert atmosphere. In addition, any material other than the lithium transition metal oxide, iodine material, and boron material may be added. By mixing the raw materials in a solid state, the mixing process can be carried out simply, costs are reduced, and it is suitable for mass production.

[0063] (Iodine material)

[0064] Iodine materials are raw materials for introducing iodine into the cathode active material. It is preferable for the iodine material to be solid at room temperature, as this facilitates easy mixing with lithium transition metal oxides. For example, the iodine material comprises one or more selected from the group consisting of elemental iodine (I2), lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI), iodoform (CHI3), carbon tetraiodide (Cl4), ammonium iodide (NH4I), iodic acid (HIO3), lithium iodate (LiIO3), sodium iodate (NaIO3), potassium iodate (KIO3), ammonium iodate (NH4IO3), metaperiodic acid (HIO4), orthoperiodic acid (H5IO6), lithium periodate (LiIO4), sodium periodate (NaIO4), potassium periodate (KIO4), iodine oxide (IV) (I2O4), iodine oxide (V) (I2O5), and iodine oxide (IV, V) (I4O9). In addition to this, any iodine material, such as metal iodides or iodine-containing organic compounds, may be used as long as it does not have a significant adverse effect on battery characteristics. Meanwhile, the valence of iodine in the iodine material is not particularly limited.

[0065] (Boron material)

[0066] Boron materials are raw materials for introducing boron into the cathode active material. It is preferable for boron materials to be solid at room temperature due to the ease of mixing with lithium transition metal oxides. For example, boron materials include H3BO3, HBO2, B2O3, LiBO2, C6H5B(OH)2, (C6H5O)3B, [CH3(CH2)3O]3B, C 13 H 19 It includes one or more selected from the group consisting of BO3, C3H9B3O6, and (C3H7O)3B. In addition, any boron material, such as metal borides, may be used as long as it does not have a significant adverse effect on battery characteristics. Meanwhile, the valence of boron in the boron material is not particularly limited.

[0067] The amount of lithium transition metal oxide added in the mixing process is, for example, 85 parts by mass or more and 99.98 parts by mass or less when the total mass of the mixture before calcination is 100 parts by mass, preferably 90 parts by mass or more and 99.9 parts by mass or less, and more preferably 95 parts by mass or more and 99.5 parts by mass or less.

[0068] The amount of iodine material added is, for example, 0.001 parts by mass or more and 5 parts by mass or less, preferably 0.01 parts by mass or more and 4 parts by mass or less, more preferably 0.05 parts by mass or more and 3 parts by mass or less, and even more preferably 0.1 parts by mass or more and 2 parts by mass or less. If the amount of iodine material added is 0.001 parts by mass or more, an improvement in the electrode resistance characteristics or cycle characteristics of the battery is expected. If the amount of iodine material added is 5 parts by mass or less, it is thought that excessive side reactions will be suppressed.

[0069] The amount of boron material added is, for example, 0.01 parts by mass or more and 5 parts by mass or less, preferably 0.05 parts by mass or more and 4 parts by mass or less, more preferably 0.1 parts by mass or more and 3 parts by mass or less, and even more preferably 0.5 parts by mass or more and 2 parts by mass or less. If the amount of boron material added is 0.01 parts by mass or more, an improvement in the capacity characteristics or cycle characteristics of the battery is expected. If the amount of boron material added is 5 parts by mass or less, it is thought that excessive side reactions will be suppressed.

[0070] (2) Sintering

[0071] In the calcination process, an anode active material is obtained by calcining the pre-calcination mixture obtained from the mixing process. Calcination is preferably performed in the presence of oxygen, and more preferably in the atmosphere, but may be performed in other atmospheres. For example, calcination may be performed in an inert atmosphere, such as a nitrogen atmosphere or a rare gas atmosphere such as argon. If calcination is performed in the atmosphere, the calcination step can be carried out simply, costs are reduced, and it is suitable for mass production.

[0072] The calcination temperature for calcining the mixture is, for example, 150°C or higher and 500°C or lower, preferably 200°C or higher and 450°C or lower, more preferably 250°C or higher and 400°C or lower, and even more preferably 300°C or higher and 350°C or lower. If the calcination temperature is 150°C or higher, it is thought that the reaction between the iodine material and the boron material will be promoted. In addition, if the calcination temperature is 500°C or lower, it is thought that the excessive formation of by-products will be suppressed. Furthermore, the calcination temperature for calcining the mixture is preferably above the melting point of the iodine material and the boron material, and more preferably above the boiling point of the iodine material and the boron material.

[0073] The calcination time during which the mixture is maintained at the calcination temperature is, for example, 1 hour or more and 12 hours or less, preferably 1 hour or more and 9 hours or less, more preferably 1.5 hours or more and 6 hours or less, and even more preferably 2 hours or more and 5 hours or less. If the calcination time is 1 hour or more, it is thought that the iodine material and the boron material can be reacted within the necessary range. In addition, if the calcination time is 12 hours or less, costs can be suppressed by not performing calcination for an excessively long time.

[0074] [Cathode Active Material Slurry]

[0075] According to one embodiment, a positive active material slurry for a lithium-ion secondary battery comprising the aforementioned positive active material is provided. The positive active material slurry comprises, for example, the aforementioned positive active material, a conductive material, a binder, and a solvent.

[0076] The content of the positive active material included in the positive active material layer may be 80 mass% or more and 99.5 mass% or less with respect to the total mass of the positive active material layer. The content of the positive active material may preferably be 85 mass% or more and 98.5 mass% or less. If the content of the positive active material is within the above range, it is possible to realize excellent capacity characteristics. In contrast, if the content of the positive active material is less than the above range, the amount of positive coating increases and the thickness increases, making it possible to achieve sufficient volumetric energy density, and if it exceeds the above range, there is a lack of binder and conductive material, and as a result, the conductivity and adhesion of the electrode become insufficient, making it possible for the performance of the battery to decrease.

[0077] (Challenge)

[0078] The conductive material is not particularly limited as long as it is an electrically conductive material that does not cause chemical changes. Examples of conductive materials include carbon-based materials such as artificial graphite, natural graphite, carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, Farness black, lamp black, carbon nanotubes, and carbon fibers; metal powders or metal fibers such as aluminum, tin, bismuth, silicon, antimony, nickel, copper, titanium, vanadium, chromium, manganese, iron, cobalt, zinc, molybdenum, tungsten, silver, gold, lanthanum, ruthenium, platinum, and iridium; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive polymers such as polyaniline, polythiophene, polyacetylene, polypyrrole, and polyphenylene derivatives. One or more of these may be used, but are not limited to these.

[0079] As shown in the examples described below, using carbon nanotubes as a conductive material can significantly reduce the impedance of the electrode. For this reason, it is preferable for the positive electrode active material slurry to include carbon nanotubes.

[0080] The content of the conductive material may be 0.1 mass% or more and 30 mass% or less based on the total mass of the positive electrode active material layer. The content of the conductive material is preferably 0.5 mass% or more and 15 mass% or less, and more preferably 0.5 mass% or more and 5 mass% or less. When the content of the conductive material satisfies the above range, it is advantageous in that sufficient conductivity can be imparted and battery capacity can be secured because the amount of the positive electrode active material is not reduced.

[0081] (bookbinder)

[0082] A binder is added as a component that promotes the bonding between the active material and the conductive material, or the bonding with the current collector. Examples of binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, and various copolymers thereof, and one or more of these may be used, but are not limited to these.

[0083] The content of the binder may be 0.1 mass% or more and 30 mass% or less based on the total mass of the positive active material layer. The content of the binder is preferably 0.5 mass% or more and 15 mass% or less, and more preferably 0.5 mass% or more and 5 mass% or less. When the content of the binder polymer satisfies the above range, sufficient adhesion within the electrode can be provided while preventing a decrease in the capacity characteristics of the battery.

[0084] (menstruum)

[0085] The solvent used in the cathode active material slurry is not particularly limited as long as it is generally used in the manufacture of the cathode. Examples of solvents include amine-based solvents such as N,N-dimethylaminopropylamine, diethylenetriamine, and N,N-dimethylformamide (DMF); ether-based solvents such as tetrahydrofuran; ketone-based solvents such as methyl ethyl ketone; ester-based solvents such as methyl acetate; amide-based solvents such as dimethylacetamide and 1-methyl-2-pyrrolidone (NMP); dimethyl sulfoxide (DMSO); and water. One or more of these may be used, but are not limited to these.

[0086] The amount of solvent used is sufficient if it has a viscosity that allows for excellent thickness uniformity when coating onto the anode current collector while dissolving or dispersing the anode active material, conductive material, and binder, taking into account the coating thickness or manufacturing yield of the slurry.

[0087] [Method for manufacturing a positive electrode active material slurry]

[0088] The positive electrode active material slurry is obtained by adding and mixing a conductive material, a binder, a solvent, etc., to the aforementioned positive electrode active material. If necessary, other additives such as a dispersant or a thickener may be added.

[0089] [anode]

[0090] According to one embodiment, a positive electrode for a lithium-ion secondary battery is provided, wherein a positive electrode active material layer comprising the aforementioned positive electrode active material is formed on a current collector. That is, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer formed on one or both sides of the positive electrode current collector. The positive electrode active material layer may be formed on the entire surface of the positive electrode current collector or only on a part thereof. For example, the positive electrode is a positive electrode for a lithium-ion secondary battery comprising an electrolyte.

[0091] (Bipolar house whole)

[0092] The anode current collector used in the anode is not particularly limited as long as it can be used electrochemically stably and has conductivity. For example, as an anode current collector, it may be stainless steel; aluminum; nickel; titanium; or an alloy thereof, or a mixture of one or more of these. In addition, it may be sintered carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc.

[0093] The positive current collector may have a thickness of 3 μm or more and 500 μm or less. Fine irregularities may be formed on the surface of the positive current collector to increase adhesion with the positive active material. The positive current collector may have various forms, such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0094] (Positive active material layer)

[0095] The positive active material layer comprises the aforementioned positive active material, conductive material, and binder. The positive active material layer may have a thickness of, for example, 1 nm or more and 100 µm or less, 10 nm or more and 10 µm or less, or 100 nm or more and 1 µm or less. The positive active material layer may be formed directly on the positive current collector or may be formed with another layer in between. Additionally, other layers, such as a protective film, may be further formed on the positive active material layer.

[0096] The positive active material layer may include a conductive material containing carbon nanotubes. Accordingly, the impedance of the electrode can be significantly reduced, thereby improving the electrode resistance characteristics.

[0097] [Method for manufacturing the anode]

[0098] By applying a positive active material slurry to a positive current collector, drying, and rolling, a positive electrode can be manufactured in which a layer of positive active material is formed on the positive current collector.

[0099] Alternatively, for example, the anode may be manufactured by casting the anode active material slurry onto another support and then laminating the film obtained by peeling off from the support onto the anode current collector. In addition, the anode active material layer may be formed on the anode current collector using any other method.

[0100] [Lithium-ion secondary battery]

[0101] According to one embodiment, a lithium-ion secondary battery having the above-described positive electrode is provided. For example, the lithium-ion secondary battery comprises the above-described positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte. Meanwhile, if a solid electrolyte is used as the non-aqueous electrolyte, the separator may be omitted. The lithium-ion secondary battery may optionally include a battery case that accommodates an electrode assembly composed of a positive electrode, a negative electrode, and a separator, and a sealing member that seals the battery case.

[0102] [cathode]

[0103] In a lithium-ion secondary battery according to an embodiment, the negative electrode comprises a negative electrode current collector and a negative electrode active material layer formed on one or both sides of the negative electrode current collector. The negative electrode active material layer may be formed on the entire surface of the negative electrode current collector or only on a part thereof.

[0104] (Cathode current collector)

[0105] The cathode current collector used for the cathode is not particularly limited as long as it is electrochemically stable and conductive. For example, copper; stainless steel; aluminum; nickel; titanium; calcined carbon; copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc.; aluminum-cadmium alloy, etc. may be used as the cathode current collector.

[0106] The negative current collector may have a thickness of 3㎛ or more and 500㎛ or less. Fine irregularities may be formed on the surface of the negative current collector to increase adhesion with the negative active material. The negative current collector may have various forms, such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0107] (Cathode active material layer)

[0108] The negative active material layer comprises a negative active material, a binder, and a conductive material. The negative active material layer may have a thickness of, for example, 1 nm or more and 100 µm or less, 10 nm or more and 10 µm or less, or 100 nm or more and 1 µm or less. The negative active material layer may be formed directly on the negative current collector or may be formed with another layer in between. Additionally, other layers, such as a protective film, may be further formed on the negative active material layer.

[0109] The negative electrode active material layer can be formed, for example, by applying a negative electrode active material slurry, in which a mixture of a negative electrode active material, a binder, and a conductive material is dissolved or dispersed in a solvent, onto a negative electrode current collector, and then drying and rolling. The mixture may further include a dispersant, a filler, or any other additives as needed.

[0110] (Cathode active material)

[0111] As a negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Examples of negative electrode active materials include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; siliconaceous materials such as silicon powder, amorphous silicon, silicon nanofiber, and silicon nanowire; silicon compounds such as silicon alloys, silicon oxides, and silicon oxides doped with alkali metals or alkaline earth metals (such as lithium or magnesium); metallic materials capable of alloying with lithium, such as Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Sn alloys, and Al alloys; and metal oxides capable of doping and dedoping lithium, such as SnO2, vanadium oxide, and lithium vanadium oxide. Examples include composites of silicon-based materials and carbonaceous materials, or composites such as Sn-C composites, and one or more of these may be used, but are not limited to these. Meanwhile, any carbonaceous material, such as low-crystallinity carbon or high-crystallinity carbon, may be used. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fibers, mesocarbon microbeads, mesophase pitch, and high-temperature calcined carbon such as petroleum and coal-based coke.

[0112] The negative electrode active material may be included in an amount of 80 mass% or more and 99 mass% or less based on the total mass of the negative electrode active material layer.

[0113] (Binder and conductive material)

[0114] The types and content of binders and conductive materials used in the cathode active material slurry are the same as those described for the anode.

[0115] (menstruum)

[0116] The solvent used in the cathode active material slurry is not particularly limited as long as it is generally used in the manufacture of the cathode. Examples of solvents include N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), isopropyl alcohol, acetone, water, etc., and one or more of these may be used, but are not limited to these.

[0117] [Method for manufacturing the cathode]

[0118] A method for manufacturing a negative electrode for a lithium-ion secondary battery according to an embodiment may include the step of obtaining a negative electrode active material slurry by dissolving or dispersing a negative electrode active material together with a binder, a conductive material, etc., in a solvent as needed, and the step of obtaining a negative electrode by forming a negative electrode active material layer on a negative electrode current collector, such as by applying the negative electrode active material slurry onto a negative electrode current collector, similar to the method for manufacturing a positive electrode.

[0119] [Separator]

[0120] In a lithium-ion secondary battery according to an embodiment, the separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions; any separator typically used as a separator in a lithium-ion secondary battery may be used without particular limitations. In particular, it is desirable that the separator has low resistance to ion movement of the electrolyte and excellent wettability of the electrolyte. For example, a porous polymer film made from polyolefin-based polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, or ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used as a separator. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber or polyethylene terephthalate fiber, may also be used. Furthermore, to ensure heat resistance or mechanical strength, a separator coated with a ceramic component or a polymer material may be used.

[0121] [Non-aqueous electrolytes]

[0122] In a lithium-ion secondary battery according to an embodiment, the non-aqueous electrolyte may be an organic liquid electrolyte, an inorganic liquid electrolyte, etc., which can be used to manufacture the lithium-ion secondary battery, but is not limited to these. For example, a solid electrolyte may also be used.

[0123] Non-aqueous electrolytes may contain organic solvents and lithium salts, and may further contain electrolyte additives as needed. Hereinafter, liquid electrolytes are also referred to as 'electrolytes'.

[0124] Organic solvents may be used without particular restriction as long as they can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Examples of organic solvents include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether and tetrahydrofuran; ketone-based solvents such as cyclohexanone; aromatic hydrocarbon-based solvents such as benzene and fluorobenzene; carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; and nitrile-based solvents such as R-CN (where R is a C2 to C20 straight-chain, branched, or cyclic hydrocarbon group, and may include double aromatic rings or ether bonds). Examples include amide-based solvents such as dimethylformamide; dioxolan-based solvents such as 1,3-dioxolan; and sulfolane-based solvents. One or more of these may be used, but are not limited to these. In particular, carbonate-based solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, etc.) is more preferred. In this case, excellent electrolyte performance can be exhibited by mixing the cyclic carbonate and the linear carbonate in a volume ratio of about 1:1 to 1:9.

[0125] Lithium salts can be used without particular restriction as long as they are compounds capable of providing lithium ions used in lithium-ion secondary batteries. Examples of lithium salts include LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, and one or more of these may be used, but are not limited to these. The lithium salt may be contained in the electrolyte at a concentration of, for example, 0.1 mol / L or more and 2 mol / L or less. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance, allowing lithium ions to move effectively.

[0126] Electrolyte additives may be used as needed for purposes such as improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity. Examples of electrolyte additives include haloalkylene carbonate compounds such as vinylene carbonate (VC), fluoroethylene carbonate (FEC) or difluoroethylene carbonate (DFEC), pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glycine, triamide hexaphosphate, nitrobenzene derivatives, sulfur, quinoneimine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc., and one or more of these may be used, but are not limited to these. The above electrolyte additive may be contained in an amount of, for example, 0.1 mass% or more and 15 mass% or less with respect to the total mass of the electrolyte.

[0127] [Method for manufacturing lithium-ion secondary batteries]

[0128] A lithium-ion secondary battery according to an embodiment can be manufactured by interposing a separator (e.g., a separator) and an electrolyte between the positive electrode manufactured as described above and the negative electrode manufactured as described above. More specifically, the electrode assembly can be formed by placing a separator between the positive electrode and the negative electrode, placing the electrode assembly into a battery case such as a cylindrical battery case or a prismatic battery case, and then injecting an electrolyte. Alternatively, the electrode assembly can be manufactured by stacking the electrodes, impregnating the resulting product with an electrolyte, placing the product into a battery case, and sealing it.

[0129] The above battery case may be one commonly used in the field. The shape of the battery case may be, for example, a cylindrical shape using a can, a prismatic shape, a pouch shape, or a coin shape.

[0130] A lithium-ion secondary battery according to an embodiment can be used not only as a power source for small devices but also as a unit cell for a medium-to-large battery module comprising a plurality of battery cells. Preferred examples of such medium-to-large devices include electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems, but are not limited thereto.

[0131] Example

[0132] The present invention will be further explained below with reference to examples and comparative examples. However, the present invention is not limited to such examples. Furthermore, the mechanisms described below are merely illustrative conjectures to aid in understanding the invention and do not limit the present invention.

[0133] [Example 1-1]

[0134] (Addition of iodine and boric acid)

[0135] LiNi 0.90 Co 0.07 Mn 0.03To 100 parts by mass of O2 powder (hereinafter also referred to as 'lithium transition metal oxide'), 1.0 parts by mass of elemental iodine (I2; Fujifilm Wako Pure Chemicals product) powder and 0.3 parts by mass of boric acid (H3BO3; Fujifilm Wako Pure Chemicals product) were added and sealed in a plastic bottle. The contents of this plastic bottle were mixed by holding it in the hand and shaking it up and down for about 1 minute to obtain a mixture.

[0136] (Sintering)

[0137] The obtained mixture was heated to 350°C under atmospheric conditions, maintained at 350°C for 5 hours for calcination, and then cooled down to room temperature to obtain a positive electrode active material.

[0138] (Preparation of cathode active material slurry)

[0139] Next, 1.5 parts by mass of carbon black as a conductive material and 2.0 parts by mass of polyvinylidene fluoride (PVDF) as a binder were added to 96.5 parts by mass of the above-mentioned positive active material together with N-methyl-2-pyrrolidone (NMP) as a solvent and mixed to obtain a positive active material slurry.

[0140] (Manufacturing of anode sheets)

[0141] Next, the obtained positive active material slurry was applied to an aluminum foil with a thickness of 20㎛ to a thickness of about 70㎛, and dried at 130℃ to obtain a positive sheet.

[0142] (Preparation of electrolyte)

[0143] Ethylene carbonate, dimethyl carbonate, and diethyl carbonate were mixed in a volume ratio of 1:2:1, and 2.0 mass% of vinylene carbonate (VC) was added while dissolving LiPF6 at a concentration of 1 mol / L to obtain an electrolyte.

[0144] (Manufacturing of coin cell batteries)

[0145] The obtained positive electrode sheet was punched into a circle with a diameter of 13 mm to obtain a positive electrode for a coin cell. Using the obtained positive electrode, a metallic lithium negative electrode with a thickness of 0.3 mm, and the above electrolyte, a CR2016 type coin cell battery was manufactured.

[0146] (Manufacturing of monocell batteries)

[0147] Apart from the coin cell, the positive sheet obtained as described above was punched into a rectangular shape to form a positive electrode for a monocell, graphite of a corresponding size was used as a negative electrode, and a monocell battery was manufactured using the above electrolyte.

[0148] [Examples 1-2]

[0149] Coin cell batteries and mono cell batteries were manufactured in the same manner as in Example 1-1, except that a mixture of 1.5 parts by mass of carbon black and carbon nanotubes was used instead of 1.5 parts by mass of carbon black as a conductive material.

[0150] [Example 2]

[0151] Coin cell batteries and monocell batteries were manufactured in the same manner as in Example 1-1, except that the amount of boric acid added was 0.5 parts by mass.

[0152] [Comparative Example 1-1]

[0153] Coin cell batteries and monocell batteries were manufactured in the same manner as in Example 1-1, except that the process of adding iodine and boric acid and the calcination process were omitted. That is, without adding iodine and boric acid, LiNi 0.90 Co 0.07 Mn 0.03 O2 was used as is as the positive active material.

[0154] [Comparative Example 1-2]

[0155] Coin cell batteries and mono cell batteries were manufactured in the same manner as Comparative Example 1-1, except that a mixture of 1.5 parts by mass of carbon black and carbon nanotubes was used instead of 1.5 parts by mass of carbon black as a conductive material.

[0156] [Comparative Example 2-1]

[0157] Coin cell batteries and mono cell batteries were manufactured in the same manner as in Example 1-1, except that only 1.0 parts by mass of iodine was added and boric acid was not added.

[0158] [Comparative Example 2-2]

[0159] Coin cell batteries and mono cell batteries were manufactured in the same manner as Comparative Example 2-1, except that a mixture of 1.5 parts by mass of carbon black and carbon nanotubes was used instead of 1.5 parts by mass of carbon black as a conductive material.

[0160] [Comparative Example 3-1]

[0161] Coin cell batteries and mono cell batteries were manufactured in the same manner as in Example 1-1, except that only 0.3 parts by mass of boric acid was added and iodine was not added.

[0162] [Comparative Example 3-2]

[0163] Coin cell batteries and mono cell batteries were manufactured in the same manner as Comparative Example 3-1, except that a mixture of 1.5 parts by mass of carbon black and carbon nanotubes was used instead of 1.5 parts by mass of carbon black as a conductive material.

[0164] [Comparative Example 4]

[0165] Coin cell batteries and mono cell batteries were manufactured in the same manner as in Example 1-1, except that only 0.5 parts by mass of boric acid was added and iodine was not added.

[0166] The manufacturing conditions of the above examples and comparative examples are summarized in Table 1. The amounts of the positive active material, conductive material, and binder added are expressed in parts by mass, and for the conductive material and binder, the values ​​in parts by mass relative to 96.5 parts by mass of the positive active material are indicated.

[0167]

[0168] [Evaluation Example 1: Elemental Analysis of Anode Active Material by Fluorescent X-ray Analysis]

[0169] For the cathode active materials obtained in each example and each comparative example, elemental analysis by X-ray fluorescence analysis (XRF) was performed. A scanning X-ray fluorescence analyzer ZSX Primus II (manufactured by Rigaku) ​​was used. The samples subject to X-ray fluorescence analysis were the solid-state cathode active materials before the preparation of the cathode active material slurry. The values ​​obtained by subtracting the values ​​of Example 1-1 and Example 2 from the values ​​of Comparative Example 1-1, which did not undergo coating treatment, as the baseline, are shown in Table 2 below as the iodine and boron content of each sample. Meanwhile, since the sensitivity of boron is generally low in X-ray fluorescence analysis, the boron content values ​​are reference values.

[0170]

[0171] [Evaluation Example 2: X-ray Photoelectron Spectroscopy (XPS) Measurement of Anode Active Material]

[0172] Measurements using X-ray photoelectron spectroscopy (XPS) were performed on the cathode active materials obtained in Example 1-1 and Comparative Example 1-1. The sample subject to analysis is the solid-state cathode active material after calcination and before preparing the cathode active material slurry. -(CH2) n - Charge correction was performed by setting the energy of the C1s peak top of the origin to 284.6 eV.

[0173] Figure 1 is a portion of the XPS spectra of the positive electrode active materials of Example 1-1 (solid line) and Comparative Example 1-1 (dotted line). As shown in Figure 1, in the positive electrode active material of Example 1-1, 3d of iodine having a peak top near 624 eV in the range of 622 eV to 626 eV 5 / 2In contrast to the observation of an electron-derived peak, no peak was observed in the positive electrode active material of Comparative Example 1. This peak position is close to the peak position of sodium iodate (NaIO3) or lithium iodate (LiIO3) containing iodine with an oxidation number of +5, or sodium periodate (NaIO4) or lithium periodate (LiIO4) containing iodine with an oxidation number of +7. Therefore, it is presumed that the positive electrode active material contains iodine having a positive oxidation number at least partially. More specifically, it is presumed that the iodine in the positive electrode active material is at least partially in the form of iodate ions and / or periodate ions. Meanwhile, in Example 1-1, a peak around 618 eV to 620 eV derived from iodine with an oxidation number of 0 or -1 was not observed.

[0174] Regarding boron, as shown in FIG. 2, in the positive electrode active material of Example 1-1, a peak of boron B1s electron origin was observed in the range of 195.0 eV to 188.5 eV, with a peak top near 191.5 eV, whereas no peak was observed in the positive electrode active material of Comparative Example 1. This peak position is close to the peak position of lithium metaborate (LiBO2). Therefore, it is presumed that the positive electrode active material contains at least partially trivalent.

[0175] [Evaluation Example 3-1: Initial Charge / Discharge Characteristics]

[0176] For the coin cell batteries prepared in each example and each comparative example, a charging and discharging process was repeated in a constant temperature bath maintained at 25°C or 45°C with an upper charging voltage limit of 4.25V and a lower discharging voltage limit of 3V, at a charging current rate of 0.3C and a discharging current rate of 0.3C. The charging capacity and discharging capacity during the first charging and discharging process were measured.

[0177] As shown in the following equation, the value obtained by dividing the charge capacity in the first charge-discharge process by the mass of the positive active material powder is defined as the 'initial charge capacity'. The value obtained by dividing the discharge capacity in the first charge-discharge process by the mass of the positive active material powder is defined as the 'initial discharge capacity'. The ratio of the discharge capacity to the charge capacity in the first charge-discharge process is defined as the 'initial efficiency'. From the measured charge capacity and discharge capacity, the initial charge capacity, initial discharge capacity, and initial efficiency at 25°C, and the initial discharge capacity at 45°C were calculated.

[0178]

[0179]

[0180]

[0181] [Evaluation Example 3-2: DC Resistance (DCR) Characteristics]

[0182] For the coin cell batteries manufactured in each example and each comparative example, the value of the Direct Current Resistance (DCR) was measured at the state where the first cycle of charging was completed and at the state where the 30th cycle of charging was completed. Specifically, the value of the Direct Current Resistance was calculated from the slope of a straight line that linearly approximates the discharge curve obtained by acquiring voltage values ​​at predetermined intervals for 60 seconds immediately after the start of discharge following the full charge state where the charging process was completed. The Direct Current Resistance after the completion of the first cycle of charging is defined as the 'Initial Direct Current Resistance'. In addition, the Direct Current Resistance Ratio defined by the following formula was calculated.

[0183]

[0184] (Result when carbon nanotubes were not added)

[0185] For Examples 1-1 and 2, and Comparative Examples 1-1, 2-1, 3-1, and 4, the evaluation results of Evaluation Examples 3-1 and 3-2 are shown in Table 3. Table 3 shows the initial charge capacity, initial discharge capacity, and initial efficiency at 25°C, the initial discharge capacity at 45°C, and the initial DC resistance and DC resistance ratio as evaluation results. However, for comparison purposes, Table 3 lists relative values ​​obtained by dividing the actual values ​​by the corresponding values ​​in Comparative Example 1-1. In the columns 'Iodine' and 'Boric Acid', the values ​​of the mass parts of iodine and boric acid added per 100 mass parts of lithium transition metal oxide are listed, respectively.

[0186]

[0187] As shown in Table 3, regarding the initial discharge capacity and initial efficiency, Comparative Example 2-1, in which only iodine was added, and Comparative Example 3-1, in which only 0.3 parts by mass of boric acid was added, showed no improvement compared to Comparative Example 1-1, in which neither iodine nor boric acid was added. In Comparative Example 4, in which only 0.5 parts by mass of boric acid was added, a slight improvement was shown compared to Comparative Example 1-1. On the other hand, in Examples 1-1 and 2, in which iodine and boric acid were added, the initial discharge capacity and initial efficiency were significantly improved compared to Comparative Example 4.

[0188] As shown in Table 3, regarding the initial DC resistance, while the initial DC resistance increased significantly in Comparative Examples 3-1 and 4, which had boric acid added, the increase in initial DC resistance was suppressed in Examples 1-1 and 2, which had iodine and boric acid added, compared to Comparative Examples 3-1 and 4. In particular, in Example 1-1, the increase in initial DC resistance was suppressed even compared to Comparative Example 2-1, which had only iodine added, and in Example 2, the increase in DC resistance was suppressed to the same extent as in Comparative Example 2-1.

[0189] (Result when carbon nanotubes were added)

[0190] For Examples 1-2, Comparative Examples 1-2, Comparative Example 2-2, and Comparative Example 3-2, the evaluation results of Evaluation Example 3-1 and Evaluation Example 3-2 are shown in Table 4. Table 4 shows the initial charge capacity, initial discharge capacity, and initial efficiency at 25°C, the initial discharge capacity at 45°C, and the initial DC resistance and DC resistance ratio as evaluation results. However, for comparison purposes, Table 4 lists relative values ​​obtained by dividing the actual values ​​by the corresponding values ​​in Comparative Example 1-2. In the columns 'Iodine' and 'Boric Acid', the values ​​of the mass parts of iodine and boric acid added per 100 mass parts of lithium transition metal oxide are listed, respectively.

[0191]

[0192] As shown in Table 4, regarding the initial discharge capacity and initial efficiency, Comparative Example 2-2, in which only iodine was added, and Comparative Example 3-2, in which only boric acid was added, showed a certain improvement compared to Comparative Example 1-1, in which neither iodine nor boric acid was added. On the other hand, in Example 1-2, in which iodine and boric acid were added, the initial discharge capacity and initial efficiency were significantly improved compared to Comparative Example 2-2 and Comparative Example 3-2.

[0193] As shown in Table 4, regarding the initial DC resistance, while the initial DC resistance increased significantly in Comparative Example 3-2, which had boric acid added, the increase in initial DC resistance was suppressed in Example 1-2, which had iodine and boric acid added, compared to Comparative Example 3-2. In addition, the increase in initial DC resistance in Example 1-2 was suppressed even when compared to Comparative Example 2-1, which had only iodine added.

[0194] From the results of Evaluation Examples 3-1 and 3-2, it was observed that adding boric acid tended to increase the initial capacity, initial efficiency, and initial DC resistance, while adding iodine tended not to increase the initial DC resistance to the extent of boric acid. On the other hand, adding both iodine and boric acid allowed for an increase in initial capacity and initial efficiency while suppressing the increase in initial DC resistance. Since the initial DC resistance when iodine and boric acid were added was smaller than the initial DC resistance when only iodine was added, it was suggested that the increase in DC resistance caused by boric acid is not simply suppressed by the addition of iodine. In other words, by adding both iodine and boric acid, a positive electrode active material was obtained that exhibited superior characteristics in both capacitance and resistance characteristics compared to when either iodine or boric acid was used alone.

[0195] [Evaluation Example 4-1: Dose Retention Rate]

[0196] For the monocell batteries prepared in each example and each comparative example, aging was performed at 25°C with a charging rate of 0.1C and a discharging rate of 0.1C. Subsequently, the charging and discharging process was repeated in a constant temperature bath maintained at 45°C with a charging upper limit voltage of 4.2V and a discharging lower limit voltage of 2.5V, at a charging rate of 0.3C and a discharging rate of 0.3C. From the discharge capacity at each cycle of the charging and discharging process, the capacity retention rate in the n-th repeated charging and discharging process, defined by the following formula, was calculated.

[0197]

[0198] [Evaluation Example 4-2: Rate of Increase in Linear Resistance]

[0199] In the same manner as in Evaluation Example 3-2, the value of the DC resistance of the monocell battery was measured at each cycle of the charge-discharge process. From the measured DC resistance value, the linear resistance growth rate during n-th repeated charge-discharge processes was calculated. The linear resistance growth rates for Examples 1-1 and 2, and Comparative Examples 1-1, 2-1, 3-1, and 4 are defined by the following formula. To facilitate comparison of the changes in linear resistance of each example and each comparative example, standardization was performed based on the linear resistance growth rate at the 299th cycle in Comparative Example 1-1.

[0200]

[0201] The linear resistance growth rate for Examples 1-2, Comparative Examples 1-2, Comparative Example 2-2, and Comparative Example 3-2 is defined by the following formula. In order to make it easier to compare the changes in linear resistance of each example and each comparative example, standardization was performed based on the linear resistance growth rate at the 299th cycle in Comparative Example 1-2.

[0202]

[0203] (Result when carbon nanotubes were not added)

[0204] FIG. 3 is a graph showing the trend of battery capacity change during the 1st to 50th charge-discharge cycles by plotting the value of the capacity retention rate defined above against the number of charge-discharge cycles for Example 1-1 and Example 2, and Comparative Example 1-1, Comparative Example 2-1, Comparative Example 3-1, and Comparative Example 4. For each example and each comparative example, the discharge capacity at the first cycle was set to 100%. The degradation of battery capacity was relatively large in Comparative Example 3-1 and Comparative Example 4, and relatively small in Example 1-1, Example 2, and Comparative Example 2-1. In Comparative Example 1-1 and Comparative Example 3-1, oscillations were observed in which the capacity retention rate fluctuated significantly with the number of cycles. FIG. 3 shows magnified views of cycles 1 to 50 to make the appearance of the oscillations easier to understand.

[0205] FIG. 4 is a figure showing the trend of change in linear resistance of the battery during the 1st to 200th charge-discharge cycles, plotting the values ​​of the linear resistance growth rates defined above against the number of charge-discharge cycles for Examples 1-1 and 2, and Comparative Examples 1-1, 2-1, 3-1, and 4. In all examples and comparative examples, the linear resistance value increased as the charge-discharge process was repeated. When comparing the linear resistance growth rates, Example 1-1 showed the smallest linear resistance growth rate, and Example 2 showed the next smallest linear resistance growth rate. Meanwhile, Comparative Example 1-1 showed the largest linear resistance growth rate.

[0206] (Result when carbon nanotubes were added)

[0207] FIG. 5 is a figure showing the trend of battery capacity change during the 1st to 50th charge-discharge cycles by plotting the value of the capacity retention rate defined above against the number of charge-discharge cycles for Example 1-2, Comparative Example 1-2, Comparative Example 2-2, and Comparative Example 3-2. For each example and each comparative example, the discharge capacity at the first cycle was set to 100%. The degradation of battery capacity was relatively large in Comparative Example 1-2 and Comparative Example 3-2, and relatively small in Example 1-2 and Comparative Example 2-2. In Comparative Example 1-2 and Comparative Example 3-2, oscillations were observed in which the capacity retention rate fluctuated significantly with the number of cycles.

[0208] FIG. 6 is a figure showing the trend of change in linear resistance of the battery during the 1st to 200th charge-discharge cycles, plotting the values ​​of the linear resistance growth rates defined above against the number of charge-discharge cycles for Example 1-2, Comparative Example 1-2, Comparative Example 2-2, and Comparative Example 3-2. Similar to FIG. 4, the linear resistance values ​​increased as the charge-discharge process was repeated in all examples and comparative examples. When comparing the linear resistance growth rates, Example 1-2 showed the smallest linear resistance growth rate, and Comparative Example 1-2 showed the largest linear resistance growth rate.

[0209] [Evaluation Example 5: Impedance after repeated charge and discharge]

[0210] For the monocell batteries prepared according to Examples 1-1, 1-2, Comparative Examples 1-1, 1-2, 2-1, 2-2, 3-1, and 3-2, the impedance of the monocell batteries was measured using an impedance analyzer in the charge-discharge cycle test of Evaluation Example 4, at the state where the first cycle of charging was completed and at the state where the 299th cycle of charging was completed. The impedance of the negative electrode side was calculated from the negative electrode side impedance component appearing on the high-frequency side (1,000,000 Hz to 100 Hz) of the obtained Cole-Cole plot. In addition, the impedance of the positive electrode side was calculated from the positive electrode side impedance component appearing on the low-frequency side (100 Hz to 0.01 Hz). The results are shown in Table 5. In Table 5, the impedance was expressed as a relative value (relative impedance) to the impedance value at 1 cycle or 299 cycles of Comparative Example 1-1, as shown in the following equation. Meanwhile, in the column 'Iodine, Boron', 'I' was indicated for the example where only iodine was added, 'B' for the example where only boron was added, 'I, B' for the example where both iodine and boron were added, and '-' for the example where neither iodine nor boron was added.

[0211]

[0212]

[0213] First, we examine Example 1-1, Comparative Example 1-1, Comparative Example 2-1, and Comparative Example 3-1, which do not use carbon nanotubes as a conductive material. When comparing Comparative Example 1-1, which does not add iodine and boron, with Comparative Example 2-1, which adds only iodine, the initial impedance after the first charge does not change significantly due to the addition of iodine, but after repeating charge-discharge cycles, the impedance on the low-frequency side was significantly lowered. On the other hand, when comparing Comparative Example 1-1, which does not add iodine and boron, with Comparative Example 3-1, which adds only boron, the initial impedance after the first charge increases significantly on the low-frequency side due to the addition of boron, but after repeating charge-discharge cycles, the impedance on the high-frequency side is significantly lowered, and the impedance on the low-frequency side is also lowered to a value equivalent to that of Comparative Example 1-1. Thus, it was suggested that adding iodine has the effect of lowering the impedance on the low-frequency side (anode side), and adding boron has the effect of lowering the impedance on the high-frequency side (cathode side). In Example 1-1, in which iodine and boron were added, it was possible to achieve both the effect of lowering the impedance on the low-frequency side (anode side) and the effect of lowering the impedance on the high-frequency side (cathode side). Furthermore, in Example 1-1, it was possible to suppress the large increase in the initial impedance on the low-frequency side caused by the addition of boron.

[0214] Furthermore, when comparing Examples 1-2, Comparative Examples 1-2, 2-2, and 3-2, in which carbon nanotubes were used as a conductive material, the same trend as in the case where carbon nanotubes were not used was confirmed overall. In addition, when comparing Examples 1-1 and 1-2, which differ in the presence or absence of carbon nanotubes, it was confirmed that the use of carbon nanotubes resulted in a decrease in impedance on both the high-frequency and low-frequency sides, both before and after the charge-discharge cycle.

[0215] [Reference Example 1]

[0216] FIG. 7 shows I3d of a calcined product obtained by mixing orthoperiodic acid (H5IO6) as a film raw material with a lithium transition metal oxide and calcining at 350°C for 5 hours. 2 / 5 This is the XPS spectrum. From Fig. 7, it was confirmed that even when H5IO6 is used as the iodine-based film material, the same spectrum as in Example 1-1, which used elemental iodine as the iodine-based film material, is obtained. Meanwhile, orthoperiodic acid (H5IO6) melts at 132°C, dehydration begins, and metaperiodic acid (HIO4) is produced. In addition, iodine oxide (V), such as I2O4 or I2O5, decomposes into oxygen and iodine at 275°C or higher. From these findings, it is presumed that regardless of the valence of iodine in the film raw material (i.e., even when metaperiodic acid (HIO4), I2O4, I2O5, etc. are used as the film raw material), the oxidation state of iodine after mixing with and calcining with lithium transition metal oxide is the same as in Example 1-1, which used elemental iodine.

Claims

Claim 1 A positive electrode active material comprising a core containing a lithium transition metal oxide and a coating portion that at least partially covers the surface of the core, the coating portion containing iodine and boron, wherein the coating portion contains iodine having an oxidation state of +5 or higher and +7 or lower. Claim 2 delete Claim 3 In claim 1, I3d observed by X-ray photoelectron spectroscopy of the positive electrode active material 5 / 2 A positive active material characterized by having a spectrum with a peak at 622 eV or higher and 626 eV or lower. Claim 4 A positive electrode active material according to claim 1, characterized in that the iodine content is 0.001 to 5 parts by mass with respect to 100 parts by mass of the lithium transition metal oxide. Claim 5 A positive electrode active material according to claim 1, characterized in that the boron content is 0.001 to 5 parts by mass with respect to 100 parts by mass of the lithium transition metal oxide. Claim 6 A positive electrode active material slurry for a lithium-ion secondary battery characterized by comprising a positive electrode active material described in any one of claims 1, 3 to 5. Claim 7 A positive electrode for a lithium-ion secondary battery, characterized in that a positive electrode active material layer comprising a positive electrode active material described in any one of claims 1, 3 to 5 is formed on a current collector. Claim 8 A positive electrode for a lithium-ion secondary battery according to claim 7, characterized in that the positive electrode active material layer further comprises a conductive material including carbon nanotubes. Claim 9 A lithium-ion secondary battery characterized by having a positive electrode as described in claim 7. Claim 10 A method for manufacturing a positive electrode active material according to claim 1, characterized by comprising the steps of obtaining a mixture containing a lithium transition metal oxide, iodine, and boron, and calcining the mixture. Claim 11 In claim 10, the invention comprises the step of adding an iodine material containing iodine as a raw material for the mixture, wherein the iodine material comprises elemental iodine (I2), lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI), iodoform (CHI3), carbon tetraiodide (Cl4), ammonium iodide (NH4I), iodic acid (HIO3), lithium iodate (LiIO3), sodium iodate (NaIO3), potassium iodate (KIO3), ammonium iodate (NH4IO3), metaperiodic acid (HIO4), orthoperiodic acid (H5IO6), lithium periodate (LiIO4), sodium periodate (NaIO4), potassium periodate (KIO4), iodine oxide (IV) (I2O4), iodine oxide (V) (I2O5) and oxide A method for manufacturing a positive electrode active material characterized by comprising one or more selected from the group consisting of iodine (IV, V) (I4O9). Claim 12 A method for manufacturing a positive active material according to claim 11, characterized in that the iodine material contains iodine (I2). Claim 13 In claim 10, the step of adding a boron material containing boron as a raw material of the above mixture is included, wherein the boron material is H3BO3, HBO2, B2O3, LiBO2, C6H5B(OH)2, (C6H5O)3B, [CH3(CH2)3O]3B, C 13 H 19 A method for manufacturing a positive electrode active material characterized by comprising one or more selected from the group consisting of BO3, C3H9B3O6 and (C3H7O)3B. Claim 14 A method for manufacturing an anode active material according to claim 13, characterized in that the boron material contains boric acid (H3BO3). Claim 15 A method for manufacturing an anode active material, characterized in that, in any one of claims 10 to 14, the above mixture is calcined at a calcination temperature of 150°C or higher and 500°C or lower.

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