Lithium-ion rechargeable battery

Abstract

A positive electrode active material for lithium-ion secondary batteries that offers high capacity and excellent charge-discharge cycle characteristics. provide. [Solution] A device containing lithium, cobalt, magnesium, oxygen, and fluorine, C Rietveld analysis was performed on the patterns obtained by powder X-ray diffraction using uKα1 rays. When this occurs, the crystal structure has a space group of R-3m, and the lattice constant of the a-axis is 2.814. Greater than ×10⁻¹⁰ m and less than 2.817 × 10⁻¹⁰ m, and c-axis The lattice constant is greater than 14.05 × 10⁻¹⁰ m, which is 14.07 × 10⁻¹⁰. When m is smaller and analyzed by X-ray photoelectron spectroscopy, the magnesium concentration when the cobalt concentration is set to 1 is... The positive electrode active material has a relative um concentration of 1.6 to 6.0.

Description

Technical Field

[0001] One aspect of the present invention relates to an object, a method, or a manufacturing method. Or, one aspect of the present invention is related to a process, a machine, a manufacture, or a composition of matter It relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device or an electronic device, or a manufacturing method thereof. In particular, it relates to a positive electrode active material, a secondary battery, and an electronic device having the secondary battery that can be used in a secondary battery.

[0002] In addition, in this specification, the power storage device refers to an element and a device having a power storage function in general. For example, it includes a storage battery (also referred to as a secondary battery) such as a lithium-ion secondary battery, a lithium-ion capacitor, and an electric double layer capacitor.

[0003] In addition, in this specification, the electronic device refers to a device having a power storage device in general, and an electro-optical device having a power storage device, an information terminal device having a power storage device, etc. are all electronic devices.

Background Art

[0004] In recent years, various power storage devices such as lithium-ion secondary batteries, lithium-ion capacitors, and air batteries have been actively developed. In particular, lithium-ion secondary batteries with high output and high energy density are rapidly expanding in demand along with the development of the semiconductor industry, for mobile information terminals such as mobile phones, smartphones, tablets, or notebook computers, portable music players, digital cameras, medical devices, next-generation clean energy automobiles (hybrid vehicles (HEV), electric vehicles (EV), plug-in hybrid vehicles (PHEV), etc.), etc., and are rechargeable ​​​​​It has become an essential energy source in the modern information society without energy supply.

[0005] As the characteristics required for lithium-ion secondary batteries, there are further improvements in energy density, improvement of cycle characteristics, safety in various operating environments, and improvement of long-term reliability.

[0006] Therefore, the improvement of the cycle characteristics and high capacity of lithium-ion secondary batteries has been aimed at, and the improvement of the positive electrode active material has been studied (Patent Document 1 and Patent Document 2). In addition, research on the crystal structure of the positive electrode active material has also been conducted (Non-Patent Documents 1 to 3).

[0007] X-ray diffraction (XRD) is one of the methods used for analyzing the crystal structure of the positive electrode active material. By using the ICSD (Inorganic Crystal Structure Database) introduced in Non-Patent Document 5, the XRD data can be analyzed.

[0008]

[0009]

Prior Art Documents

Patent Documents

Patent Document 1

Patent Document 2

[0010]

Patent Document 3

Non-Patent Documents

Non-Patent Document 1

[0011] One aspect of the present invention relates to a lithium-ion secondary battery with high capacity and excellent charge-discharge cycle characteristics. One of the objectives is to provide a positive electrode active material and a method for producing the same. Alternatively, to improve productivity. One objective is to provide a method for producing a positive electrode active material. Alternatively, one aspect of the present invention is: When used in lithium-ion secondary batteries, the decrease in capacity during charge-discharge cycles is suppressed. One objective of the present invention is to provide a positive electrode active material that has high capacity. Alternatively, one aspect of the present invention provides a high capacity two One objective is to provide a next-generation battery. Alternatively, one aspect of the present invention provides a battery with excellent charge-discharge characteristics. One of the objectives is to provide a secondary battery that can maintain a high-voltage charged state for a long period of time. The objective is to provide a positive electrode active material in which the elution of transition metals such as cobalt is suppressed even when the material is held. This is one aspect of the present invention. Alternatively, one aspect of the present invention provides a safe or reliable secondary battery. This will be one of the challenges.

[0012] Alternatively, one aspect of the present invention relates to a novel substance, active material particles, energy storage device, or a method for producing the same. One of our objectives is to provide legal frameworks.

[0013] Furthermore, the description of these problems does not preclude the existence of other problems. One embodiment does not need to solve all of these problems. It is possible to extract other problems from the description of the claims. [Means for solving the problem]

[0014] One aspect of the present invention is a collection of lithium, cobalt, magnesium, oxygen, and fluorine. The Rietveld solution is used to determine the pattern obtained by powder X-ray diffraction using CuKα1 rays. When analyzed, it was found to have a crystal structure with an R-3m space group, and 2.814 × 10⁻⁶ - 10 Larger than m, 2.817 × 10 -10 It is less than m, and the lattice constant of the c axis is 14.0 5 x 10 -10 Larger than m, 14.07 × 10 -10 Smaller than m, and can be determined by X-ray photoelectron spectroscopy. When analyzed, the relative value of the magnesium concentration when the cobalt concentration is set to 1 is between 1.6 and 6. The positive electrode active material has a value of 0 or less.

[0015] Alternatively, one aspect of the present invention comprises lithium, cobalt, magnesium, oxygen, and fluorine. A positive electrode active material having the above characteristics, wherein the positive electrode active material is used as the positive electrode and lithium metal is used as the negative electrode. In lithium-ion secondary batteries, until the battery voltage reaches 4.7V in a 25°C environment. After constant current charging, and then constant voltage charging until the current value becomes 0.01C, the positive electrode is treated with CuKα When analyzed by single-line powder X-ray diffraction, 2θ is between 19.10° and 19.50°. The first diffraction peak and the second diffraction peak where 2θ is between 45.50° and 45.60° It is a positive electrode active material that has a 'k' and a 'k'.

[0016] Furthermore, in any of the above configurations, the positive electrode active material is used as the positive electrode and lithium metal is used as the negative electrode. In the lithium-ion secondary battery used, the battery voltage was 4.7V at a 25°C environment. Constant current charging is performed until the current value reaches 0.01C, then constant voltage charging is performed until the current value reaches 0.01C, and then the positive terminal is turned C When analyzed by powder X-ray diffraction using uKα1 rays, 2θ is between 19.10° and 19.50°. The first diffraction peak is below, and the second peak is where 2θ is between 45.50° and 45.60°. It is preferable to have a folded peak.

[0017] Furthermore, in any of the above configurations, the magnesium measured by X-ray photoelectron spectroscopy The concentration is preferably between 1.6 and 6.0, with the cobalt concentration being set to 1.

[0018] Furthermore, any of the above configurations may include nickel, aluminum, and phosphorus. This is preferable.

[0019] Alternatively, in one aspect of the present invention, a lithium source, a fluorine source, and a magnesium source are mixed. A first step of preparing a first mixture, comprising lithium, cobalt, and oxygen. A second step involves mixing a composite oxide with a first mixture to produce a second mixture, and A third step involves heating the mixture of two to produce a third mixture, and then adding the third mixture and A The fourth step is to mix the aluminum source with the fourth mixture to make a fourth mixture, and then heat the fourth mixture. The method for producing a positive electrode active material comprises a fifth step of producing a fifth mixture, In the fourth step, the number of aluminum atoms in the aluminum source is equal to the third mixture. A method for producing a positive electrode active material having a cobalt atom number between 0.001 and 0.02 times the number of cobalt atoms present. It is the law.

[0020] Furthermore, in the above configuration, the magnesium source in the first step The number of atoms is 0.005 times or more the number of cobalt atoms in the composite oxide from the second step. It is preferable that the ratio is 0.5 times or less. [Effects of the Invention]

[0021] According to one aspect of the present invention, a lithium-ion secondary battery with high capacity and excellent charge-discharge cycle characteristics is provided. This invention provides a positive electrode active material for ponds and a method for producing the same. Furthermore, it provides a positive electrode with high productivity. We can provide a method for producing active materials. Furthermore, we can provide a method for use in lithium-ion secondary batteries. Therefore, it is possible to provide a positive electrode active material in which the decrease in capacity during charge-discharge cycles is suppressed. Furthermore, it can provide high-capacity secondary batteries. It can also provide secondary batteries with excellent charge / discharge characteristics. It can provide this. Also, even when the high-voltage charge state is maintained for a long time, cobal This provides a positive electrode active material in which the elution of transition metals such as t is suppressed. Furthermore, it is safe and This can provide highly reliable secondary batteries. Furthermore, it can utilize novel materials, active material particles, and energy storage solutions. We can provide apparatus or methods for manufacturing them. [Brief explanation of the drawing]

[0022] [Figure 1] Figure 1 illustrates the charge depth and crystal structure of the positive electrode active material. [Figure 2] Figure 2 illustrates the charge depth and crystal structure of the positive electrode active material. [Figure 3] Figure 3 shows the XRD pattern calculated from the crystal structure. [Figure 4] Figure 4(A) shows the lattice constants calculated from XRD. Figure 4(B) shows the lattice constants calculated from XRD. Figure 4(C) shows the lattice constants calculated from XRD. [Figure 5] Figure 5(A) shows the lattice constants calculated from XRD. Figure 5(B) shows the lattice constants calculated from XRD. Figure 5(C) shows the lattice constants calculated from XRD. [Figure 6] Figure 6 illustrates an example of a method for producing a positive electrode active material according to one aspect of the present invention. [Figure 7] Figure 7 illustrates an example of a method for producing a positive electrode active material according to one aspect of the present invention. [Figure 8] Figure 8 illustrates an example of a method for producing a positive electrode active material according to one aspect of the present invention. [Figure 9]Figure 9 illustrates an example of a method for producing a positive electrode active material according to one aspect of the present invention. [Figure 10] Figure 10(A) is a cross-sectional view of the active material layer when a graphene compound is used as a conductive additive. Figure 10(B) is a cross-sectional view of the active material layer when a graphene compound is used as a conductive additive. [Figure 11] Figure 11(A) is a diagram illustrating the charging method of a secondary battery. Figure 11(B) is a diagram illustrating the charging method of a secondary battery. Figure 11(C) is a diagram illustrating the charging method of a secondary battery. [Figure 12] Figure 12(A) is a diagram illustrating the charging method of a secondary battery. Figure 12(B) is a diagram illustrating the charging method of a secondary battery. Figure 12(C) is a diagram illustrating the charging method of a secondary battery. [Figure 13] Figure 13(A) is a diagram illustrating the charging method of a secondary battery. Figure 13(B) is a diagram illustrating the discharging method of a secondary battery. [Figure 14] Figure 14(A) is a diagram illustrating a coin-type rechargeable battery. Figure 14(B) is a diagram illustrating a coin-type rechargeable battery. Figure 14(C) is a diagram illustrating current and electrons during charging. [Figure 15] Figure 15(A) is a diagram illustrating a cylindrical secondary battery. Figure 15(B) is a diagram illustrating a cylindrical secondary battery. Figure 15(C) is a diagram illustrating multiple cylindrical secondary batteries. Figure 15(D) is a diagram illustrating multiple cylindrical secondary batteries. [Figure 16] Figure 16(A) is a diagram illustrating an example of a battery pack. Figure 16(B) is a diagram illustrating an example of a battery pack. [Figure 17] Figure 17(A1) is a diagram illustrating an example of a secondary battery. Figure 17(A2) is a diagram illustrating an example of a secondary battery. Figure 17(B1) is a diagram illustrating an example of a secondary battery. Figure 17(B2) is a diagram illustrating an example of a secondary battery. [Figure 18] Figure 18(A) is a diagram illustrating an example of a secondary battery. Figure 18(B) is a diagram illustrating an example of a secondary battery. [Figure 19] Figure 19 illustrates an example of a secondary battery. [Figure 20] Figure 20(A) is a diagram illustrating a laminated rechargeable battery. Figure 20(B) is a diagram illustrating a laminated rechargeable battery. Figure 20(C) is a diagram illustrating a laminated rechargeable battery. [Figure 21] Figure 21(A) is a diagram illustrating a laminated rechargeable battery. Figure 21(B) is a diagram illustrating a laminated rechargeable battery. [Figure 22] Figure 22 shows the external appearance of a secondary battery. [Figure 23] Figure 23 shows the external appearance of a secondary battery. [Figure 24] Figure 24(A) is a diagram illustrating the method for manufacturing a secondary battery. Figure 24(B) is a diagram illustrating the method for manufacturing a secondary battery. Figure 24(C) is a diagram illustrating the method for manufacturing a secondary battery. [Figure 25] Figure 25(A) is a diagram illustrating a bendable secondary battery. Figure 25(B1) is a diagram illustrating a bendable secondary battery. Figure 25(B2) is a diagram illustrating a bendable secondary battery. Figure 25(C) is a diagram illustrating a bendable secondary battery. Figure 25(D) is a diagram illustrating a bendable secondary battery. [Figure 26] Figure 26(A) is a diagram illustrating a bendable secondary battery. Figure 26(B) is a diagram illustrating a bendable secondary battery. [Figure 27] Figure 27(A) is a diagram illustrating an example of an electronic device. Figure 27(B) is a diagram illustrating an example of an electronic device. Figure 27(C) is a diagram illustrating an example of an electronic device. Figure 27(D) is a diagram illustrating an example of an electronic device. Figure 27(E) is a diagram illustrating an example of an electronic device. Figure 27(F) is a diagram illustrating an example of an electronic device. Figure 27(G) is a diagram illustrating an example of an electronic device. Figure 27(H) is a diagram illustrating an example of an electronic device. [Figure 28] Figure 28(A) is a diagram illustrating an example of an electronic device. Figure 28(B) is a diagram illustrating an example of an electronic device. Figure 28(C) is a diagram illustrating an example of an electronic device. [Figure 29] Figure 29 is a diagram illustrating an example of an electronic device. [Figure 30] Figure 30(A) is a diagram illustrating an example of a vehicle. Figure 30(B) is a diagram illustrating an example of a vehicle. Figure 30(C) is a diagram illustrating an example of a vehicle. [Figure 31] Figure 31(A) shows the continuous charge endurance of the secondary battery. Figure 31(B) shows the continuous charge endurance of the secondary battery. [Figure 32] Figure 32(A) shows the continuous charge endurance of the secondary battery. Figure 32(B) shows the continuous charge endurance of the secondary battery. [Figure 33] Figure 33(A) shows the cycle characteristics of a secondary battery. Figure 33(B) shows the cycle characteristics of a secondary battery. [Figure 34] Figure 34(A) shows the XRD evaluation results for the positive electrode. Figure 34(B) shows the XRD evaluation results for the positive electrode. [Figure 35] Figure 35(A) shows the XRD evaluation results for the positive electrode. Figure 35(B) shows the XRD evaluation results for the positive electrode. [Figure 36] Figure 36(A) shows the continuous charge endurance of the secondary battery. Figure 36(B) shows the continuous charge endurance of the secondary battery. [Figure 37] Figure 37 shows the cycle characteristics of a secondary battery. [Figure 38] Figure 38(A) shows the charge and discharge curve of a secondary battery. Figure 38(B) shows the charge and discharge curve of a secondary battery. Figure 38(C) shows the charge and discharge curve of a secondary battery. [Figure 39] Figure 39(A) shows the TEM observation results of the positive electrode active material. Figure 39(B) shows the EDX analysis results of the positive electrode active material. [Figure 40] Figure 40(A) shows the XRD evaluation results for the positive electrode. Figure 40(B) shows the XRD evaluation results for the positive electrode. [Modes for carrying out the invention]

[0023] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention This is not limited to the description below, and its form and details can be changed in various ways, as is the case for those skilled in the art. This will be easily understood. Furthermore, the present invention shall be interpreted as being limited to the contents of the embodiments described below. It is not something that should be done.

[0024] Furthermore, in this specification, crystal planes and directions are indicated by Miller indices. In crystallography, numbers are represented with a superscript bar, but in this specification, due to limitations on patent application notation, the numbers are represented as follows: Sometimes, instead of placing a bar above a letter, a minus sign (-) is placed before the number to represent it. Furthermore, the individual orientations indicating directions within a crystal are [ ], and the collective orientation showing all equivalent directions is < > represents individual crystal planes ( ), and sets of planes with equivalent symmetry are {}. They express each other.

[0025] In this specification, segregation refers to the process of a solid composed of multiple elements (e.g., A, B, C). This refers to the phenomenon in which a certain element (for example, B) is distributed non-uniformly in space.

[0026] In this specification, the surface layer of particles such as active materials refers to the region from the surface up to approximately 10 nm. This refers to the surface. Surfaces created by cracks or fissures can also be called the surface. Furthermore, the area deeper than the surface layer is also called the surface. , internally.

[0027] In this specification, etc., layered rock salt-type crystals of composite oxides containing lithium and transition metals The structure has a rock salt-type ionic arrangement in which cations and anions are arranged alternately, and transition metals Because lithium is arranged in a regular pattern to form a two-dimensional plane, two-dimensional diffusion of lithium is possible. This refers to a crystal structure. It may also have defects such as vacancies in cations or anions. Strictly speaking, a layered rock salt crystal structure is a structure in which the lattice of rock salt crystals is distorted. There is.

[0028] Furthermore, in this specification and elsewhere, a rock salt-type crystal structure is defined as a structure in which cations and anions are arranged alternately. This refers to a structure that is characterized by the presence of a cation or anion. A deficiency in either a cation or anion is also acceptable.

[0029] Furthermore, in this specification, etc., the pseudo-spinel type of composite oxide containing lithium and a transition metal The crystal structure of cobalt is space group R-3m, and although it is not a spinel-type crystal structure, it is cobalt Magnesium and other ions occupy the 6-coordinate position of oxygen, and the arrangement of cations is similar to that of a spinel. This refers to a crystal structure that possesses symmetry. Note that pseudo-spinel crystal structures are found in light elements such as lithium. The element may occupy the oxygen 4-coordinate position, and in this case as well, the ion arrangement is similar to that of the spinel type. It has symmetry.

[0030] Furthermore, the pseudo-spinel type crystal structure, although having Li randomly between layers, is a CdCl2 type. It can also be said that it is a crystal structure similar to the crystal structure. The crystal structure is when lithium nickelate is charged to a depth of charge of 0.94 (Li 0.06 Ni It has a crystal structure similar to that of O2, but is pure lithium cobaltate or a layered structure containing a large amount of cobalt. It is known that rock salt-type cathode active materials do not usually adopt this crystal structure.

[0031] Layered rock salt crystals, and the anions of rock salt crystals, have a cubic close-packed structure (face-centered cubic lattice structure). ) takes this form. It is also presumed that pseudo-spinel crystals adopt a cubic close-packed structure for anions. When they come into contact, there exists a crystal plane in which the orientation of the cubic close-packed structure composed of anions is aligned. However, the space group of layered rock salt crystals and pseudo-spinel crystals is R-3m, and rock salt The space groups of type crystals are Fm-3m (the space group of a typical rock salt type crystal) and Fd-3m (the simplest). Because it is different from the space group of rock salt crystals that have symmetry, the crystal planes that satisfy the above conditions The Lars index differs between layered rock salt crystals, pseudo-spinel crystals, and rock salt crystals. In layered rock salt crystals, pseudo-spinel crystals, and rock salt crystals, anions When the orientations of the cubic close-packed structures that are formed are aligned, we say that the crystal orientations are roughly the same. There is.

[0032] The approximate agreement of the crystal orientation in the two regions can be seen in TEM (transmission electron microscope) images and STE (spherical spectroscopy) images. M (Scanning Transmission Electron Microscope) image, HAADF-STEM (High-angle scattering annular dark-field scanning transmission electron microscope) image. The determination should be made based on images from a microscope, ABF-STEM (annular bright-field scanning transmission electron microscope), etc. This can be done. X-ray diffraction (XRD), electron diffraction, neutron diffraction, etc. can also be used as criteria for judgment. Yes, it is possible. In TEM images, the arrangement of cations and anions can be observed as a repetition of bright and dark lines. It can be inferred. When the orientation of the cubic close-packed structure is aligned in layered rock salt crystals and rock salt crystals, the crystal In between, the angle between the repetition of bright and dark lines is 5 degrees or less, more preferably 2.5 degrees or less. The condition can be observed. Furthermore, light elements such as oxygen and fluorine are clearly visible in TEM images, etc. In some cases, it may not be possible to discern this, but in such cases, the alignment of the metal elements can be determined by their arrangement. ru.

[0033] Furthermore, in this specification, the theoretical capacity of the positive electrode active material refers to the insertion and removal capacity of the positive electrode active material. This refers to the amount of electricity that would be generated if all the lithium were to be desorbed. For example, the theoretical capacity of LiCoO2 is 27 The theoretical capacity of LiNiO2 is 274mAh / g, and the theoretical capacity of LiMn2O4 is 4mAh / g. The capacity is 148mAh / g.

[0034] Furthermore, in this specification, etc., the charging depth when all insertable and removable lithium is inserted. The degree is 0, and the charge depth when all the insertable and detachable lithium in the positive electrode active material has been detached is 1. Let's assume that's the case.

[0035] Furthermore, in this specification, charging means moving lithium ions from the positive electrode to the negative electrode within the battery. This refers to the movement of electrons, specifically from the negative electrode to the positive electrode in an external circuit. Therefore, the process of releasing lithium ions is called charging. Also, the charging depth is 0.7 or higher. Positive electrode active materials with a voltage of 0.9 or less are sometimes referred to as positive electrode active materials charged with high voltage.

[0036] Similarly, discharge is the movement of lithium ions from the negative electrode to the positive electrode within a battery, and externally... This refers to the movement of electrons from the positive electrode to the negative electrode in a circuit. The positive electrode active material is lithium. The insertion of ions is called discharge. Also, the positive electrode active material has a charge depth of 0.06 or less, The positive electrode active material, which has been discharged to more than 90% of its charge capacity from a state of being charged at high voltage, This refers to the positive electrode active material that has been discharged for a certain amount of time.

[0037] Furthermore, in this specification, a non-equilibrium phase change refers to a phenomenon that causes a nonlinear change in a physical quantity. Let's assume that this is the case. For example, it can be obtained by differentiating capacitance (Q) with respect to voltage (V) (dQ / dV). Around the peaks in the dQ / dV curve, non-equilibrium phase transitions occur, and the crystal structure changes significantly. It is thought that they understand.

[0038] (Embodiment 1) This embodiment describes a positive electrode active material according to one aspect of the present invention.

[0039] [Structure of the positive electrode active material] Materials with a layered rock salt-type crystalline structure, such as lithium cobalt oxide (LiCoO2), emit It is known to have high electrical capacity and is excellent as a positive electrode active material for secondary batteries. Examples of materials having a crystalline structure include composite oxides represented by LiMO2. One or more examples of element M can be selected from Co or Ni. And one or more selected from Co and Ni, plus one or more selected from Al and Mn It can be listed.

[0040] The Jahn-Teller effect in transition metal compounds depends on the number of electrons in the d orbitals of the transition metal. It is known that the strength of their effects varies.

[0041] In nickel-containing compounds, distortion is likely to occur due to the Jahn-Teller effect. Therefore, when charging and discharging LiNiO2 at high voltage, distortion occurs. There is a concern that this will lead to a breakdown of the crystal structure. In LiCoO2, the Jahn-Teller effect The impact is suggested to be small, and it may be preferable as it may have better resistance to charging and discharging at high voltages. It's nice.

[0042] The positive electrode active material will be explained using Figures 1 and 2. This section describes the case where cobalt is used as the transition metal in a material.

[0043] <Cathode active material 1> The positive electrode active material 100C shown in Figure 2 is prepared by the following method using halogen and magnesium. This is lithium cobalt oxide (LiCoO2) without added substances. The lithium cobalt oxide shown in Figure 2 As described in Non-Patent Documents 1 and 2, etc., Um is determined by the charging depth. The crystal structure changes.

[0044] As shown in Figure 1, lithium cobalt oxide at charge depth 0 (discharge state) has space group R- It has a region with a 3m crystal structure, and there are three CoO2 layers in the unit cell. Therefore, this crystal structure is sometimes called the O3 type crystal structure. Note that the CoO2 layer is cobalt This refers to an octahedral structure in which oxygen atoms are coordinated in six positions, and which is continuous on a plane in a state of shared edges. .

[0045] Furthermore, when the charging depth is 1, it has a crystal structure of space group P-3m1, and the unit cell contains Co One O2 layer is present. Therefore, this crystal structure is sometimes called an O1 type crystal structure.

[0046] Furthermore, lithium cobalt oxide at a charge depth of approximately 0.88 has a crystal structure of space group R-3m. It has a structure. This structure has a CoO2 structure like P-3m1(O1) and R-3m(O 3) It can also be described as a structure in which LiCoO2 structures like this are alternately stacked. The crystal structure is sometimes called the H1-3 type crystal structure. In this structure, the number of cobalt atoms per unit cell is twice that of other structures. However, Figure 1 In this specification, and in order to facilitate comparison with other structures, the c-axis of the H1-3 type crystal structure is defined as follows: This will be shown as a diagram that is half the size of a knit cell.

[0047] As an example, the H1-3 type crystal structure is described in Non-Patent Document 3, where the unit cell The coordinates of cobalt and oxygen are given as follows: Co(0, 0, 0.42150±0.00016), O 1(0, 0, 0.27671±0.00045), O2(0, 0, 0.11535±0. It can be represented as 00045). O1 and O2 are oxygen atoms, respectively. The H1-3 type crystal structure is formed by a unit cell consisting of one cobalt and two oxygen atoms. This is expressed. On the other hand, as will be described later, the pseudo-spinel type crystal structure of one aspect of the present invention is preferred. It is represented by a unit cell using one cobalt and one oxygen. This is a pseudo The symmetry between cobalt and oxygen differs between the spinel structure and the H1-3 type structure. The pseudo-spinel structure shows less variation from the O3 structure compared to the H1-3 type structure. This shows the crystal structure of the positive electrode active material. It is preferable to represent the crystal structure using any of the unit cells. The choice of , for example, in Rietveld analysis of XRD, GOF (good of You should choose the option that makes the fitness value smaller.

[0048] High-voltage charging such that the charging voltage is 4.6V or higher based on the oxidation-reduction potential of lithium metal. If you repeatedly charge to a deep depth of 0.8 or more, and then discharge the battery, Lithium cobalt oxide has an H1-3 type crystal structure and a R-3m(O3) structure in its discharged state. During this process, the crystal structure undergoes repeated changes (i.e., non-equilibrium phase transitions).

[0049] However, these two crystal structures have a large displacement of the CoO2 layer. (See dotted line in Figure 1) As indicated by the arrows, in the H1-3 type crystal structure, the CoO2 layer is large from R-3m(O3) It is collapsing. Such dynamic structural changes negatively affect the stability of the crystal structure. Eur.

[0050] Furthermore, the volume difference is also large. When comparing per the same number of cobalt atoms, H1-3 type crystal The difference in volume between the structure and the O3-type crystal structure in the discharged state is 3.0% or more.

[0051] In addition, the H1-3 type crystal structure has a continuous CoO2 layer, such as P-3m1(O1). The resulting structure is likely to be unstable.

[0052] Therefore, repeated high-voltage charging and discharging causes the crystalline structure of lithium cobalt oxide to break down. The breakdown of the crystal structure causes a deterioration in cycle properties. This reduces the number of sites where lithium can exist stably, and also makes lithium insertion and removal more difficult. This is likely the reason.

[0053] <Cathode active material 2> ≪Inside≫ In one aspect of the present invention, the positive electrode active material undergoes repeated high-voltage charging and discharging, and the CoO2 layer This can be made smaller. Furthermore, the change in volume can be made smaller. Therefore, A positive electrode active material according to one aspect of the present invention can achieve excellent cycle characteristics. A positive electrode active material according to one aspect of the invention can adopt a stable crystalline structure in a high-voltage charged state. In one embodiment of the present invention, the positive electrode active material maintains a high-voltage charge state, In some cases, a reaction may be less likely to occur. In such cases, safety is further improved, which is preferable. .

[0054] In one embodiment of the present invention, the positive electrode active material is in a fully discharged state and a high-voltage charged state. In this case, the difference in volume when comparing the change in crystal structure and the same number of transition metal atoms is small.

[0055] Figure 2 shows the crystal structure of the positive electrode active material 100A before and after charging and discharging. The positive electrode active material 100A is It is a composite oxide containing thium, cobalt, and oxygen. In addition to the above, magnesium It is preferable that it has [a certain characteristic]. It is also preferable that it has a halogen such as fluorine or chlorine.

[0056] The crystal structure of the charge depth 0 (discharge state) in Figure 2 is R-3m(O3), the same as in Figure 1. On the other hand, the positive electrode active material 100A, when fully charged to a sufficient depth of charge, has an H1-3 type crystal structure. It has crystals with different structures. This structure has a space group R-3m, and in the spinel-type crystal structure... Although not present, ions such as cobalt and magnesium occupy the 6-coordinate position of oxygen, and the cations The rows have symmetry similar to that of a spinel. Therefore, this structure is referred to as a pseudo-spinel type in this specification. This is called the crystal structure. Note that in the diagram of the pseudo-spinel type crystal structure shown in Figure 2, cobalt To explain the symmetry of atoms and the symmetry of oxygen atoms, the representation of lithium has been omitted. However, in reality, lithium exists between the CoO2 layers at a concentration of, for example, less than 20 atoms relative to cobalt. In addition, in both the O3 type crystal structure and the pseudo-spinel type crystal structure, CoO2 It is preferable that a dilute amount of magnesium is present between the layers, i.e., at the lithium sites. It is preferable that halogens such as fluorine are present randomly and dilutely at the oxygen sites.

[0057] Furthermore, in pseudo-spinel crystal structures, light elements such as lithium occupy the oxygen 4-coordinate position. In this case as well, the arrangement of ions has a symmetry similar to that of the spinel type.

[0058] Furthermore, the pseudo-spinel type crystal structure, although having Li randomly between layers, is a CdCl2 type. It can also be said that it is a crystal structure similar to the crystal structure. The crystal structure is when lithium nickelate is charged to a depth of charge of 0.94 (Li0.06 Ni It has a crystal structure similar to that of O2, but is pure lithium cobaltate or a layered structure containing a large amount of cobalt. It is known that rock salt-type cathode active materials do not usually adopt this crystal structure.

[0059] Layered rock salt crystals, and the anions of rock salt crystals, have a cubic close-packed structure (face-centered cubic lattice structure). ) takes this form. It is also presumed that pseudo-spinel crystals adopt a cubic close-packed structure for anions. When they come into contact, there exists a crystal plane in which the orientation of the cubic close-packed structure composed of anions is aligned. However, the space group of layered rock salt crystals and pseudo-spinel crystals is R-3m, and rock salt The space groups of type crystals are Fm-3m (the space group of a typical rock salt type crystal) and Fd-3m (the simplest). Because it is different from the space group of rock salt crystals that have symmetry, the crystal planes that satisfy the above conditions The Lars index differs between layered rock salt crystals, pseudo-spinel crystals, and rock salt crystals. In layered rock salt crystals, pseudo-spinel crystals, and rock salt crystals, anions When the orientations of the cubic close-packed structures that are formed are aligned, we say that the crystal orientations are roughly the same. There is.

[0060] In positive electrode active material 100A, the crystal structure when a large amount of lithium is released during high-voltage charging is observed. The change is more suppressed than in the positive electrode active material 100C. For example, as shown by the dotted line in Figure 2. Furthermore, in these crystal structures, there is almost no displacement of the CoO2 layer.

[0061] To explain in more detail, the positive electrode active material 100A maintains structural stability even at high charging voltages. The value is high. For example, in positive electrode active material 100C, the charging voltage at which the H1-3 type crystal structure is formed is, for example For example, even at a voltage of about 4.6V with the potential of lithium metal as the reference, the positive electrode active material 100 In A, there exists a charging voltage region in which the R-3m(O3) crystal structure can be maintained, and further charging In the increased pressure range, for example, with the potential of lithium metal as the reference, approximately 4.65V to 4.7V Even at high voltages, there are regions where a pseudo-spinel type crystal structure can be adopted. Furthermore, if the charging voltage is increased... In some cases, H1-3 type crystals can finally be observed. For example, in secondary batteries... If graphite is used as the negative electrode active material, for example, if the voltage of the secondary battery is 4.3V or higher, Even below V, there exists a charging voltage range in which the R-3m(O3) crystal structure can be maintained. Furthermore, in the region where the charging voltage is increased, for example, 4.35V or higher relative to the potential of lithium metal. Even below 55V, there is a region where a pseudo-spinel type crystal structure can be adopted.

[0062] Therefore, in the positive electrode active material 100A, even when repeatedly charged and discharged at high voltage, the crystal structure remains unchanged. It's resistant to crumbling.

[0063] In the pseudo-spinel type crystal structure, the coordinates of cobalt and oxygen in the unit cell are Co It can be shown that the coordinates are (0,0,0.5), O(0,0,x), and within the range 0.20≦x≦0.25. can.

[0064] Magnesium, which is randomly and dilutely present between the CoO2 layers, that is, at the lithium sites, It has the effect of suppressing the displacement of the CoO2 layer. Therefore, magnesium is present between the CoO2 layers. This makes it easy to form a pseudo-spinel type crystal structure. Therefore, magnesium is a positive electrode active material. It is preferable that magnesium is distributed throughout the entire particle. Therefore, it is preferable to perform a heat treatment in the manufacturing process of the positive electrode active material 100A.

[0065] However, if the heat treatment temperature is too high, cation mixing occurs and magnesium The likelihood of magnesium entering the cobalt site increases. Furthermore, if the heat treatment temperature is too high, the effect of maintaining the structure of R-3m will be lost. There are concerns about adverse effects such as the reduction of cobalt to its divalent state and the evaporation of lithium. It can be done.

[0066] Therefore, prior to the heat treatment to distribute magnesium throughout the particles, cobalt acid It is preferable to add halogen compounds such as fluorine compounds to lithium. Adding a substance causes a decrease in the melting point of lithium cobalt oxide. By lowering the melting point, the At temperatures where on-mixing is unlikely to occur, it is easy to distribute magnesium throughout the particles. It is. Furthermore, if a fluorine compound is present, it provides corrosion resistance to hydrofluoric acid produced by the decomposition of the electrolyte. It can be expected that this will improve.

[0067] Furthermore, increasing the magnesium concentration beyond the desired value reduces its effect on stabilizing the crystal structure. In some cases, this can occur. Magnesium, in addition to lithium sites, also contains cobalt sites. This is thought to be because it will also be able to enter the to The number of um atoms is preferably 0.001 times or more and 0.1 times or less the number of cobalt atoms, and 0.0 A ratio greater than 1x and less than 0.04x is more preferable, and around 0.02x is even more preferable. The magnesium concentration shown is, for example, the total magnesium concentration of the positive electrode active material particles as measured using ICP-MS. The values ​​may be those obtained from elementary analysis, or the values ​​of the raw material composition during the process of manufacturing the positive electrode active material. It may be based on this.

[0068] Lithium cobalt oxide can be used with a metal other than cobalt (hereinafter referred to as metal Z), for example, nickel. One or more metals selected from aluminum, manganese, titanium, vanadium, and chromium It may be added, and it is particularly preferable to add one or more nickel and aluminum. Manganese, titanium, vanadium, and chromium can sometimes be stable in the tetravalent state, and structure In some cases, it contributes significantly to stability. By adding metal Z, the positive electrode activity of one aspect of the present invention In materials, for example, the crystal structure may become more stable under high-voltage charging conditions. In this embodiment of the present invention, in a positive electrode active material, metal Z is the crystalline property of lithium cobalt oxide. It is preferable to add it at a concentration that does not change significantly. For example, the aforementioned Yarn Terra - It is preferable that the amount is such that it does not produce any effect.

[0069] As the magnesium concentration of the positive electrode active material in one aspect of the present invention increases, the volume of the positive electrode active material The amount may decrease. One possible reason for this is the entry of magnesium into the lithium site. This could potentially reduce the amount of lithium that contributes to charging and discharging. In some cases, magnesium may produce magnesium compounds that do not contribute to charging and discharging. (This invention) In one embodiment, the positive electrode active material contains nickel as metal Z in addition to magnesium. Furthermore, it may be possible to increase the capacity per unit weight and per unit volume. In one embodiment, the positive electrode active material has aluminum as the metal Z in addition to magnesium. In some cases, the capacity per unit weight and per unit volume can be increased. One embodiment of the positive electrode active material has nickel and aluminum in addition to magnesium. This can sometimes increase the capacity per unit weight and per unit volume.

[0070] The concentrations of elements such as magnesium and metal Z in the positive electrode active material according to one embodiment of the present invention are as follows: This is expressed using the number of atoms.

[0071] The number of nickel atoms in the positive electrode active material according to one aspect of the present invention is 7.5 times the number of cobalt atoms. A percentage of % or less is preferable, 0.05% to 4% is more preferable, and 0.1% to 2% is preferable. Furthermore, it is preferable. The nickel concentration shown here is determined by, for example, using ICP-MS or the like to determine the positive electrode active material This could be the value obtained from elemental analysis of the entire particle, or the original value obtained during the process of manufacturing the positive electrode active material. It may also be based on the values ​​of the ingredient proportions.

[0072] The number of aluminum atoms in the positive electrode active material according to one aspect of the present invention is equal to the number of cobalt atoms. A is preferably between 0.05% and 4%, and more preferably between 0.1% and 2%. Hereinafter, A The luminium concentration can be determined, for example, by elemental analysis of the entire particle of the positive electrode active material using ICP-MS. It may be a value obtained by the process, or it may be based on the values ​​of the raw material composition during the manufacturing process of the positive electrode active material. That's good too.

[0073] The positive electrode active material in one aspect of the present invention preferably has element X, and as element X is phosphorus. It is preferable to use it. Furthermore, the positive electrode active material in one aspect of the present invention is a compound containing phosphorus and oxygen. It is more preferable to have it.

[0074] In one embodiment of the present invention, the positive electrode active material has a compound containing element X, thereby enabling high-voltage charging When the state is maintained, short circuits are less likely to occur.

[0075] In one embodiment of the present invention, when the positive electrode active material has phosphorus as element X, the decomposition of the electrolyte occurs The hydrogen fluoride generated may react with phosphorus, potentially lowering the concentration of hydrogen fluoride in the electrolyte. ru.

[0076] If the electrolyte contains LiPF6, hydrolysis may generate hydrogen fluoride. Furthermore, hydrogen fluoride is produced by the reaction of PVDF, which is used as a component of the positive electrode, with alkali. This can also occur. A decrease in the hydrogen fluoride concentration in the electrolyte can lead to corrosion of the current collector. In some cases, this can suppress peeling of the coating. Also, the adhesion of PVDF due to gelation or insolubilization can be improved. In some cases, the decline can be suppressed.

[0077] In one embodiment of the present invention, when the positive electrode active material contains magnesium in addition to element X, high voltage charging It has extremely high stability in the electrical state. If element X is phosphorus, the number of phosphorus atoms is equal to the number of cobalt atoms. Preferably, the amount of atoms is 1% to 20%, more preferably 2% to 10%, and 3% More preferably, the amount is 8% or less, and in addition, the number of magnesium atoms is 0 times the number of cobalt atoms. Preferably between 0.1% and 10%, more preferably between 0.5% and 5%, and 0.7% or more. A concentration of 4% or less is more preferable. The phosphorus and magnesium concentrations shown here are, for example, ICP- The values ​​may be those obtained by elemental analysis of the entire particle of the positive electrode active material using MS, etc. The quality may also be based on the values ​​of the raw material composition during the manufacturing process.

[0078] If the positive electrode active material has cracks, phosphorus, more specifically phosphorus and acid may be present inside. The presence of compounds containing certain elements can sometimes inhibit the progression of cracks.

[0079] ≪Surface layer≫ It is preferable that magnesium is distributed throughout the particles of the positive electrode active material 100A, however In addition, it is preferable that the magnesium concentration in the surface layer of the particle is higher than the average concentration of the entire particle. For example, the magnesium concentration in the particle surface layer, measured by XPS, etc., is measured by ICP-MS, etc. It is preferable that the magnesium concentration is higher than the average magnesium concentration of all particles being treated.

[0080] Furthermore, the positive electrode active material 100A may contain elements other than cobalt, such as nickel, aluminum, and ma. In the case where there is one or more metals selected from gan, iron and chromium, the particles of the metal It is preferable that the concentration in the surface layer is higher than the average concentration of the entire particle. For example, by XPS, etc. The concentration of elements other than cobalt in the surface layer of the particles being measured is the same as the concentration of elements measured by ICP-MS, etc. It is preferable that the concentration of the element is higher than the overall average concentration.

[0081] The surface of each particle is, in a sense, entirely composed of crystal defects, and lithium leaks from the surface during charging. Because of this, the lithium concentration tends to be lower in this area than in the interior. Therefore, it becomes unstable. This is a region where the crystal structure is easily broken down. If the magnesium concentration in the surface layer is high, the crystal Structural changes can be suppressed more effectively. Also, the magnesium concentration in the surface layer is high. Furthermore, it can be expected that the corrosion resistance to hydrofluoric acid produced by the decomposition of the electrolyte will improve.

[0082] Furthermore, the concentration of halogens such as fluorine in the surface layer of the positive electrode active material 100A is greater than the average concentration of the entire particle. It is preferable that the halogen is present in the surface layer, which is the region in contact with the electrolyte. This effectively improves corrosion resistance to hydrofluoric acid.

[0083] Thus, the surface layer of the positive electrode active material 100A has a higher concentration of magnesium and fluorine than the interior. It is preferable that the composition is high and different from the internal composition. Furthermore, the composition should be stable at room temperature. It is preferable to have a crystalline structure. Therefore, even if the surface layer has a different crystalline structure from the interior, Good. For example, at least a portion of the surface layer of the positive electrode active material 100A has a rock salt-type crystalline structure. It is also permissible to do so. Furthermore, if the surface and interior have different crystal structures, the crystals of the surface and interior may differ. It is preferable that the orientations of the elements are roughly consistent.

[0084] However, if the surface layer consists only of MgO, or only of a solid solution of MgO and CoO(II), The insertion and removal of lithium becomes difficult. Therefore, the surface layer contains at least cobalt. In the discharge state, it also contains lithium and must have a path for lithium insertion and removal. Furthermore, it is preferable that the concentration of cobalt is higher than that of magnesium.

[0085] Furthermore, it is preferable that element X is located near the surface of the particles of the positive electrode active material 100A. The positive electrode active material 100A may be covered with a coating having element X.

[0086] ≪Grain boundary≫ The magnesium or halogen contained in the positive electrode active material 100A is randomly and dilutely distributed inside. While their presence is acceptable, it is more preferable that some of them are segregated at the grain boundaries.

[0087] In other words, the magnesium concentration at and near the grain boundaries of the positive electrode active material 100A is also within It is preferable that the halogen concentration is higher than in other areas of the region. Also, the halogen concentration at and near the grain boundaries is also It is preferable that it be higher than other areas inside.

[0088] Similar to particle surfaces, grain boundaries are also surface defects. Therefore, they are prone to instability and can alter the crystal structure. Cementation is likely to begin. Therefore, if the magnesium concentration is high at and near the grain boundaries, This allows for more effective suppression of changes in crystal structure.

[0089] Furthermore, if the magnesium and halogen concentrations at and near the grain boundaries are high, the positive electrode activity Even if a crack occurs along the grain boundary of the particles of material 100A, the crack will cause Magnesium and halogen concentrations increase near the surface. This causes cracks to form. This also improves the corrosion resistance to hydrofluoric acid in the subsequent cathode active material.

[0090] In this specification, the vicinity of a grain boundary refers to the region extending approximately 10 nm from the grain boundary. Let's do that.

[0091] ≪Particle size≫ The particle size of the positive electrode active material 100A is important because if it is too large, lithium diffusion becomes difficult. There are problems such as the surface of the active material layer becoming too rough when processed. On the other hand, if it is too small, Problems include difficulty in supporting the active material layer during coating of the current collector, and excessive reaction with the electrolyte. Spots also occur. Therefore, the average particle diameter (D50: also called the median diameter) is 1 μm or larger. Preferably 100 μm or less, more preferably 2 μm to 40 μm, and 5 μm A thickness of 30 μm or less is even more preferable.

[0092] <Analysis method> One of the present inventions describes a positive electrode active material that exhibits a pseudo-spinel-type crystal structure when charged at a high voltage. Whether or not the positive electrode active material 100A is of the type can be determined by testing the positive electrode, which has been charged with a high voltage, using XRD and electron beam. Analysis is performed using diffraction, neutron diffraction, electron spin resonance (ESR), nuclear magnetic resonance (NMR), etc. This can be determined by the following. In particular, XRD can determine the symmetry of transition metals such as cobalt in the positive electrode active material. It can analyze properties with high resolution, compare crystallinity and crystal orientation, and analyze the periodicity of the lattice. This method allows for the analysis of stress and crystallite size, and directly measures the positive electrode obtained by disassembling a secondary battery. It is preferable in that it can achieve sufficient accuracy even when done this way.

[0093] In one aspect of the present invention, the positive electrode active material 100A is in a state where it is charged at a high voltage as described above. A key feature is that the crystal structure changes little when charged at high voltage and when discharged. Materials in which crystal structures exhibiting large changes in electrical state account for more than 50 wt% are resistant to high-voltage charging and discharging. It is undesirable because it cannot be obtained. Furthermore, simply adding impurity elements will not result in the desired crystal structure. It is important to note that this may not always be the case. For example, a compound containing magnesium and fluorine. Although they share the common characteristic of being lithium baltate, when charged at high voltage, they exhibit a pseudo-spinel type When the crystalline structure accounts for 60 wt% or more, and when the H1-3 type crystalline structure accounts for 50 wt% or more, There are cases where this occurs. Also, at a given voltage, the pseudo-spinel type crystal structure is almost 100 wt%. Furthermore, if the specified voltage is increased, an H1-3 type crystal structure may be formed. Therefore, in order to determine whether or not it is a positive electrode active material 100A according to one aspect of the present invention, XRD and other methods are used. Analysis of the crystal structure is necessary.

[0094] However, when the positive electrode active material is in a high-voltage charged or discharged state, its crystalline structure changes when exposed to the air. Changes in structure can occur. For example, from a pseudo-spinel type crystal structure to an H1-3 type crystal structure. It may change. Therefore, all samples should be kept in an inert atmosphere such as an argon atmosphere. It is preferable to lent it.

[0095] ≪Charging method≫ To determine whether a certain composite oxide is the positive electrode active material 100A of one aspect of the present invention High-voltage charging is used, for example, with a lithium counter electrode coin cell (CR2032 type, 20mm in diameter). It can be made (with a height of 3.2 mm) and charged.

[0096] More specifically, the positive electrode consists of a slurry mixed with positive electrode active material, a conductive additive, and a binder. A positive electrode current collector made of aluminum foil can be used, coated with this material.

[0097] Lithium metal can be used as the counter electrode. However, if a material other than lithium metal is used as the counter electrode... When this occurs, the potential of the secondary battery and the potential of the positive electrode are different. Voltage and potential in this specification, etc. Unless otherwise specified, this represents the potential of the positive electrode.

[0098] The electrolyte in the electrolyte solution contains 1 mol / L lithium hexafluoride phosphate (LiPF6). The electrolyte used is ethylene carbonate (EC) and diethyl carbonate (DEC). EC:DEC = 3:7 (volume ratio), vinylene carbonate (VC) is mixed at 2 wt%. You can use the one that you have.

[0099] Polypropylene with a thickness of 25 μm can be used for the separator.

[0100] The positive electrode and negative electrode cans can be made of stainless steel (SUS). Cut.

[0101] The coin cell manufactured under the above conditions was charged with a constant current of 4.6V and 0.5C, and then the current value was measured. Charge at a constant voltage until the current reaches 0.01C. Here, 1C is defined as 137mA / g. The temperature should be set to 25°C. After charging in this manner, the coin cell is subjected to an argon atmosphere glow. By disassembling the device in a box and removing the positive electrode, a positive electrode active material charged with high voltage can be obtained. To suppress reactions with external components when performing various analyses afterward, the area is sealed under an argon atmosphere. It is preferable to do so. For example, XRD can be performed by sealing the sample in a sealed container under an argon atmosphere. can.

[0102] ≪XRD≫ CuKα1 calculated from the pseudo-spinel type crystal structure and the H1-3 type crystal structure model. Figure 3 shows an ideal powder XRD pattern using lines. For comparison, a LiC with a charge depth of 0 is also shown. The ideal X calculated from the crystal structures of oO2(O3) and CoO2(O1) at a charge depth of 1 The RD pattern is also shown. Note that the patterns for LiCoO2(O3) and CoO2(O1) are as follows: ICSD(Inorganic Crystal Structure Database) e) From the crystal structure information obtained from (see Non-Patent Document 5), Materials Stud Reflex Powder Dif, one of the modules in io (BIOVIA) It was created using fraction. The range of 2θ was set to 15° to 75°, and Step s ize=0.01, wavelength λ1=1.540562×10 -10 m, λ2 not set, Mo The nochromator was set to single. The H1-3 type crystal structure pattern is unpatented. It was similarly created from the crystal structure information described in Reference 3. The pattern of the pseudo-spinel type crystal structure is The crystal structure of the positive electrode active material according to one embodiment of the present invention is estimated from the XRD pattern, and TOPAS ve The structure was fitted using r.3 (Bruker's crystal structure analysis software), and compared with others. Similarly, an XRD pattern was created.

[0103] As shown in Figure 3, in the pseudo-spinel type crystal structure, 2θ = 19.30 ± 0.20° (1 9.10° to 19.50°, and 2θ = 45.55 ± 0.10° (45.45 Diffraction peaks appear between 45.65° and 2θ. More specifically, 2θ = 19. 30±0.10° (19.20° to 19.40°), and 2θ = 45.55±0 A sharp diffraction peak appears at 0.05° (between 45.50° and 45.60°). However, H1 Peaks appear at these positions in the -3 crystal structure and CoO2(P-3m1,O1). No. Therefore, when charged at high voltage, 2θ = 19.30 ± 0.20°, and 2θ The appearance of a peak of =45.55±0.10° indicates that the positive electrode active material 10 in one embodiment of the present invention This can be considered a characteristic of 0A.

[0104] This shows the crystal structure at a charging depth of 0 and the crystal structure when charged at high voltage, and the XRD diffraction peak It can also be said that the locations where the peaks appear are close together. More specifically, the main diffraction peaks of both. In two or more of these, more preferably three or more, the difference in the position where the peak appears is 2θ It can be said that 2θ = 0.7 or less, and more preferably 2θ = 0.5 or less.

[0105] Furthermore, in one embodiment of the present invention, the positive electrode active material 100A, when charged with high voltage, forms a pseudo-spinel type bond. Although it has a crystal structure, not all particles have to have a pseudo-spinel type crystal structure. It may contain a structure, or part of it may be amorphous. However, regarding the XRD pattern... When Rietveld analysis is performed, the pseudo-spinel type crystal structure is present in 50 wt% or more of the case. Preferably, it is 60 wt% or more, more preferably 66 wt% or more. is also preferable. If the spinel-like crystal structure is 50 wt% or more, more preferably 60 wt% or more, and even more preferably 66 wt% or more, a cathode active material with excellent cycle characteristics can be obtained.

[0106] Also, even after 100 cycles or more of charge-discharge from the start of measurement, when Rietveld analysis is performed, the spinel-like crystal structure is preferably 35 wt% or more, more preferably 40 wt% or more, and even more preferably 43 wt% or more.

[0107] Moreover, the crystallite size of the spinel-like crystal structure possessed by the particles of the cathode active material decreases only up to about 1 / 10 of that of LiCoO2(O3) in the discharged state. Therefore, even under the same XRD measurement conditions as those of the cathode before charge-discharge, a clear peak of the spinel-like crystal structure can be confirmed after high-voltage charging. On the other hand, in simple LiCoO2, even if a part can have a structure similar to the spinel-like crystal structure, the crystallite size becomes small and the peak becomes broad and small. The crystallite size can be determined from the half-width of the XRD peak.

[0108] In the cathode active material of one embodiment of the present invention, as described above, it is preferable that the influence of the Jahn-Teller effect is small. The cathode active material of one embodiment of the present invention preferably has a layered rock salt-type crystal structure and mainly has cobalt as a transition metal. Also, in the cathode active material of one embodiment of the present invention, within a range where the influence of the Jahn-Teller effect is small, in addition to cobalt, the above-described metal Z may be included.

[0109] Regarding the cathode active material, the range of lattice constants that is presumed to have a small influence of the Jahn-Teller effect is considered using XRD analysis. ​

[0110] Figures 4(A) and (B) show that the positive electrode active material of one embodiment of the present invention has a layered rock salt type crystalline structure. Furthermore, in the case of cobalt and nickel, the lattice determination of the a-axis and c-axis is performed using XRD. The results of the number estimation are shown. Figure 4(A) shows the results for the a-axis, and Figure 4(B) shows the results for the c-axis. The XRD used to calculate the lattice constants shown in Figures 4(A) and (B) is used in the synthesis of the positive electrode active material. This is the powder after processing, before being incorporated into the positive electrode. The nickel concentration on the horizontal axis is the same as the cobalt concentration. This shows the nickel concentration when the sum of the number of nickel atoms is taken as 100%. The positive electrode active material is It is manufactured using steps S21 to S25 described later, and in step S21, A balt source and a nickel source were used. The nickel concentration was determined in step S21 by cobalt This shows the nickel concentration when the sum of the number of atoms of t and nickel is taken as 100%.

[0111] Figures 5(A) and (B) show a positive electrode active material according to one embodiment of the present invention having a layered rock salt type crystal structure. In the case where it contains cobalt and manganese, the a-axis and c-axis grid are measured using XRD. The results of estimating the constants are shown. Figure 5(A) shows the results for the a-axis, and Figure 5(B) shows the results for the c-axis. The XRD used to calculate the lattice constants shown in Figures 5(A) and (B) was used for the synthesis of the positive electrode active material. This is the powder after the process, before it is incorporated into the positive electrode. The manganese concentration on the horizontal axis is cobalt. This indicates the manganese concentration when the sum of the number of atoms of nitrate and manganese is taken as 100%. The positive electrode active material is The following steps S21 to S25 are used to manufacture the product, and in step S21 Cobalt and manganese sources were used. The manganese concentration was determined in step S21. This shows the concentration of manganese when the sum of the number of atoms of lute and manganese is taken as 100%.

[0112] Figure 4(C) shows the results for the lattice constants of the positive electrode active material, as shown in Figures 4(A) and (B). This shows the value obtained by dividing the lattice constant of the a-axis by the lattice constant of the c-axis (a-axis / c-axis). Figure 5(C) shows For the positive electrode active material whose lattice constant results are shown in Figures 5(A) and (B), the lattice constant of the a-axis This shows the value obtained by dividing the number by the lattice constant of the c-axis (a-axis / c-axis).

[0113] Figure 4(C) shows a significant change in the a / c axis between nickel concentrations of 5% and 7.5%. This is observed, suggesting that the a-axis distortion is large. This distortion is called Jahn-Teller distortion. This is possible. At nickel concentrations below 7.5%, Jahn-Teller distortion is small. This suggests that a superior cathode active material can be obtained.

[0114] Next, from Figure 5(A), when the manganese concentration is 5% or higher, the behavior of the change in the lattice constant is This suggests that it does not follow Vegard's rule. Therefore, if the manganese concentration is 5% or higher, This suggests that the crystal structure is different. Therefore, a manganese concentration of, for example, 4% or less is preferred. It's nice.

[0115] Furthermore, the above ranges for nickel and manganese concentrations are always within the surface layer of the particles. This is not applicable. In other words, the concentration in the surface layer of the particle may be higher than the above-mentioned concentration. There are cases where this is the case.

[0116] Based on the above considerations regarding the preferred range of lattice constants, one aspect of the present invention is correct In the highly active material, the state in which no charging or discharging occurs, or discharge, can be estimated from the XRD pattern. In the layered rock salt-type crystal structure of the positive electrode active material particles in the electrostatic state, the lattice constant of the a-axis is 2 .814×10-10 Greater than m and less than 2.817×10 -10 Less than m and having a lattice constant of the c-axis of 14.05×10 Greater than m and less than 14.07×10 -10 m was found to be preferable. The state of not performing charge and discharge may be, for example, the powder state before producing the positive electrode of the secondary battery. -10 Or, in the state of not performing charge and discharge, or in the layered rock salt-type crystal structure of the particles of the positive electrode active material in the discharged state, the value obtained by dividing the lattice constant of the a-axis by the lattice constant of the c-axis (a-axis / c-axis) Is preferably greater than 0.20000 and less than 0.20049. Or, in the state of not performing charge and discharge, or in the layered rock salt-type crystal structure of the particles of the positive electrode active material in the discharged state, when XRD analysis is performed, the first peak is observed at 2θ of 18.50° or more and 19.30

[0117] ° or less, and the second peak may be observed at 2θ of 38.00° or more and 38.80° or less.

[0118]

[0119] ≪XPS≫ In X-ray photoelectron spectroscopy (XPS), since analysis of a region from the surface to a depth of about 2 to 8 nm (usually about 5 nm) is possible, for about half of the surface layer region, the concentration of each element can be quantitatively analyzed.

[0120]

[0121] When XPS analysis is performed on 100A of the positive electrode active material, when the concentration of cobalt is set to 1

[0120] The relative concentration of magnesium is preferably 1.6 to 6.0, and preferably 1.8 to 4.0. A full concentration is preferable. Furthermore, the relative concentration of halogens such as fluorine is preferably between 0.2 and 6.0. Furthermore, a value between 1.2 and 4.0 is more preferable.

[0121] For example, when performing XPS analysis, monochromatic aluminum can be used as the X-ray source. It can be done. Also, the extraction angle can be set to, for example, 45°.

[0122] Furthermore, when XPS analysis was performed on the positive electrode active material 100A, the bond energy between fluorine and other elements was found to be The peak indicating energy is preferably between 682 eV and 685 eV, and is 684.3 It is even more preferable that it be around eV. This is the binding energy of lithium fluoride. Both 685 eV and the bond energy of magnesium fluoride, 686 eV, are The values ​​are different. In other words, if the positive electrode active material 100A contains fluorine, lithium fluoride... It is preferable that the bond is something other than magnesium fluoride.

[0123] Furthermore, when XPS analysis was performed on the positive electrode active material 100A, magnesium and other elements were found to be... The peak indicating the binding energy is preferably between 1302 eV and 1304 eV. Furthermore, it is even more preferable that the voltage be around 1303 eV. This is due to the bonding of magnesium fluoride. This value is different from the energy of 1305 eV, and is related to the bond energy of magnesium oxide. The values ​​are close. In other words, if the positive electrode active material 100A contains magnesium, then magnesium fluoride It is preferable that the bond is not made of sium.

[0124] ≪EDX≫ EDX measurement is a method of measuring while scanning within a region and evaluating that region in two dimensions. This is sometimes called DX surface analysis. Furthermore, data from linear regions can be extracted from EDX surface analysis. The process of evaluating the distribution of atomic concentrations within positive electrode active material particles is sometimes called line analysis.

[0125] EDX surface analysis (e.g., elemental mapping) can be used to analyze the interior, surface, and vicinity of grain boundaries. Furthermore, the concentrations of magnesium and fluorine can be quantitatively analyzed. Also, EDX Linear analysis allows for the analysis of peak concentrations of magnesium and fluorine.

[0126] When EDX radiation analysis was performed on the positive electrode active material 100A, the magnesium concentration in the surface layer was The marks are present in the positive electrode active material 100A from the surface toward the center to a depth of 3 nm. Preferably, they are present up to a depth of 1 nm, more preferably up to a depth of 0.5 nm. It is even more preferable to do so.

[0127] Furthermore, the distribution of fluorine in the positive electrode active material 100A superimposes the distribution of magnesium. This is preferable. Therefore, when EDX radiation analysis is performed, the peak of fluorine concentration in the surface layer is positive electrode active Preferably, it exists from the surface of material 100A to a depth of 3 nm towards the center, and the depth It is more preferable that it be present up to 1 nm, and even more preferable that it be present up to a depth of 0.5 nm. preferable.

[0128] ≪dQ / dVvsV curve≫ Furthermore, the positive electrode active material according to one aspect of the present invention, after being charged at a high voltage, is subjected to, for example, a low voltage of 0.2C or less. When discharging at a high rate, a characteristic voltage change may appear near the end of the discharge. The voltage range is 3.5V to 3.9V in the dQ / dV vs V curve obtained from the discharge curve. This can be clearly confirmed by the presence of at least one peak.

[0129] [Method for preparing positive electrode active material 1] Next, using Figures 6 and 7, an example of a method for producing a positive electrode active material according to one embodiment of the present invention will be described. I will explain. Figures 8 and 9 also show another example of a specific manufacturing method.

[0130] <Step S11> As shown in step S11 of Figure 6, first, as materials for mixture 902, a fluorine source and chlorine Prepare halogen and magnesium sources. It is also preferable to prepare a lithium source. It seems so.

[0131] For example, lithium fluoride and magnesium fluoride can be used as fluorine sources. In particular, lithium fluoride has a relatively low melting point of 848°C, and in the annealing process described later... It is preferable because it melts easily. Examples of chlorine sources include lithium chloride and magnesium chloride. Magnesium sources can be used, for example, magnesium fluoride, magnesium oxide. Lithium, magnesium hydroxide, magnesium carbonate, etc. can be used. For example, lithium fluoride and lithium carbonate can be used. Lithium can be used as both a lithium source and a fluorine source. Cium can be used as both a fluorine source and a magnesium source.

[0132] In this embodiment, lithium fluoride (LiF) is prepared as the fluorine source and lithium source. Magnesium fluoride (MgF2) will be prepared as the fluorine source and magnesium source. (As a specific example in Figure 6, see step S11 in Figure 8). Lithium fluoride (LiF) and magnesium fluoride When Cium MgF2 is mixed in a molar ratio of approximately LiF:MgF2=65:35, its melting point is lowered. The effect is highest when the amount of lithium fluoride increases (Non-Patent Literature 4). On the other hand, when the amount of lithium fluoride increases, There are concerns that excessive fluoride will worsen the cycle characteristics. Therefore, lithium fluoride Li The molar ratio of F to magnesium fluoride (MgF2) is LiF:MgF2=x:1 (0≦x≦1). 9) is preferable, and LiF:MgF2=x:1 (0.1≦x≦0.5) is more preferable. Furthermore, LiF:MgF2=x:1 (near x=0.33) is even more preferable. In writing and other documents, "neighborhood" refers to a value greater than 0.9 times the value and less than 1.1 times the value.

[0133] Furthermore, if the following mixing and grinding steps are to be performed wet, a solvent will be prepared. The solvent will be A Ketones such as cetone, alcohols such as ethanol and isopropanol, ethers, and dio Xane, acetonitrile, N-methyl-2-pyrrolidone (NMP), etc. can be used. It is more preferable to use an aprotic solvent that does not react easily with lithium. In this embodiment, acetone is used (see step S11 in Figure 8).

[0134] <Step S12> Next, the materials of the above mixture 902 are mixed and ground (step S in Figures 6 and 8). 12) Mixing can be done dry or wet, but wet mixing allows for finer grinding. This is preferable because it allows for mixing. For example, a ball mill, bead mill, etc., can be used. When using a ball mill, it is preferable to use zirconia balls as the media, for example. It is preferable to thoroughly perform this mixing and grinding process to finely pulverize the mixture 902. .

[0135] <Step S13, Step S14> The mixed and ground materials described above are collected (step S13 in Figures 6 and 8), and the mixture 90 Obtain 2 (step S14 in Figures 6 and 8).

[0136] The mixture 902 preferably has a D50 of 600 nm or more and 20 μm or less, It is more preferable that the particle size is between 1 μm and 10 μm. The mixture 90 is thus finely powdered. If 2, then when mixed with a composite oxide containing lithium, a transition metal, and oxygen in a later step... This makes it easier to uniformly adhere mixture 902 to the surface of the composite oxide particles. If the mixture 902 is uniformly attached to the surface, after heating, leakage will occur to the surface layer of the composite oxide particles. It is preferable because it is easy to distribute halogens and magnesium in the surface layer. If there is a region that does not contain magnesium, the aforementioned pseudo-spinel type crystal will form in the charged state. It may be difficult to form a structure.

[0137] Next, through steps S21 to S25, lithium, transition metal and oxygen are obtained. A composite oxide is obtained.

[0138] <Step S21> First, as shown in step S21 of Figure 6, a composite having lithium, a transition metal and oxygen A lithium source and a transition metal source are prepared as materials for the composite oxide.

[0139] For example, lithium carbonate, lithium fluoride, etc., can be used as lithium sources.

[0140] For example, at least one of cobalt, manganese, and nickel can be used as the transition metal. It is possible.

[0141] When using a layered rock salt crystal structure as the positive electrode active material, the ratio of the materials is as follows: The mixture ratio of cobalt, manganese, and nickel should be appropriate. Also, the layered rock salt crystal structure is suitable. Aluminum may be added to these transition metals to the extent that it is possible.

[0142] As the transition metal source, oxides, hydroxides, etc. of the above-mentioned transition metals can be used. As a source of oxal, for example, cobalt oxide, cobalt hydroxide, etc. can be used. As a nickel source, manganese oxide, manganese hydroxide, etc. can be used. For example, nickel oxide, nickel hydroxide, etc. can be used as an aluminum source. Aluminum oxide, aluminum hydroxide, etc., can be used.

[0143] <Step S22> Next, the lithium source and transition metal source are mixed (step S22 in Figure 6). This can be done dry or wet. For mixing, for example, a ball mill, bead mill, etc. can be used. It is possible to use a ball mill, for example, zirconia balls as the media. It is preferable to use it.

[0144] <Step S23> Next, the mixture of ingredients described above is heated. This step is called baking to distinguish it from the subsequent heating step. This may be referred to as the first heating stage. Heating should be carried out at a temperature between 800°C and 1100°C. Preferably, the process is carried out at 900°C to 1000°C, more preferably at around 950°C. This is preferable. If the temperature is too low, the decomposition and melting of the starting material may be insufficient. On the other hand, if the temperature is too high, it can lead to excessive reduction of transition metals and evaporation of lithium. This could lead to defects. For example, a defect where cobalt becomes divalent could occur.

[0145] The heating time is preferably between 2 hours and 20 hours. The firing process involves using dry air or other moisture-free materials. This process should be carried out in an atmosphere with low humidity (for example, a dew point of -50°C or lower, more preferably -100°C or lower). Preferably, heating at 1000°C for 10 hours, with the temperature increase at 200°C / h, and drying The atmosphere flow rate is preferably 10 L / min. After that, the heated material is cooled to room temperature. It can be rejected. For example, if the cooling time from the specified temperature to room temperature is 10 hours or more and 50 hours or more It is preferable to place it at the bottom.

[0146] However, cooling to room temperature in step S23 is not mandatory. 24. There is a problem in performing steps S25 and S31 to S34. If not available, cooling may be limited to a temperature higher than room temperature.

[0147] Furthermore, regarding the metal contained in the positive electrode active material, the above steps S22 and S2 It may be introduced in step 3, and for some of the metals, steps S41 to S described later may be used. It can also be introduced in step S46. More specifically, in step S22 and S In step S23, metal M1 (M1 is cobalt, manganese, nickel, and aluminum) Introduce one or more selected from M, and in steps S41 to S46, metal M2 (M2 is, for example, one or more selected from manganese, nickel, and aluminum) In this way, by separating the process of introducing metal M1 and metal M2, each metal It may be possible to change the profile of the genus in the depth direction. For example, the relative of the inside of the particle The concentration of metal M2 can be increased in the surface layer. Also, the number of atoms of metal M1 is used as a reference. The ratio of the number of metal M2 atoms to the standard is made higher in the surface layer than in the interior. It is possible.

[0148] In one embodiment of the present invention, in a positive electrode active material, cobalt is preferably selected as the metal M1. Nickel and aluminum are selected as metal M2.

[0149] <Step S24, Step S25> The material fired as described above is recovered (step S24 in Figure 6) and used as the positive electrode active material 100C. A composite oxide containing lithium, a transition metal, and oxygen is obtained (step S25 in Figure 6). Physically, lithium cobaltate, lithium manganeseate, lithium nickelate, cobalt Lithium cobalt oxide partially substituted with manganese, or nickel-manganese-cobalt Obtain lithium oxide.

[0150] Furthermore, step S25 includes pre-synthesized lithium, transition metals, and oxygen. A composite oxide may be used (see Figure 8). In this case, steps S21 to S 24 can be omitted.

[0151] When using a pre-synthesized composite oxide containing lithium, a transition metal, and oxygen. It is preferable to use materials with few impurities. In this specification, lithium, transition metals, The composite oxide containing oxygen, and the positive electrode active material, have lithium, cobalt, as the main components. The main components are nickel, manganese, aluminum, and oxygen, with elements other than those listed above considered impurities. For example, when analyzed by glow discharge mass spectrometry, the total impurity concentration is 10,000 p. It is preferable that it is 5000 ppm wt or less, and more preferably 5000 ppm wt or less. The combined impurity concentrations of titanium and transition metals such as arsenic are 3000 ppm wt or less. It is preferable that the concentration be 1500 ppm wt or less.

[0152] For example, as pre-synthesized lithium cobalt oxide, manufactured by Nippon Chemical Industrial Co., Ltd. Lithium cobalt oxide particles (product name: Cellseed C-10N) can be used. The average particle size (D50) is approximately 12 μm, and by glow discharge mass spectrometry (GD-MS)... In the impurity analysis, the magnesium concentration and fluorine concentration were 50 ppm wt or less. Calcium, aluminum, and silicon concentrations are 100 ppm wt or less, nickel Sulfur concentration is 150 ppm wt or less, sulfur concentration is 500 ppm wt or less, arsenic concentration is 11 00 ppm wt or less, and the concentration of other elements other than lithium, cobalt, and oxygen is 150 This is lithium cobalt oxide with a concentration of less than ppm wt.

[0153] Alternatively, lithium cobalt oxide particles manufactured by Nippon Chemical Industrial Co., Ltd. (product name: Cellseed C- 5H) can also be used. This has an average particle size (D50) of approximately 6.5 μm, and GD -In impurity analysis by MS, the concentrations of elements other than lithium, cobalt, and oxygen were C- This is lithium cobalt oxide, equivalent to or less than 10N.

[0154] In this embodiment, cobalt is used as the transition metal, and pre-synthesized cobalt acid We will use lithium particles (Cellseed C-10N manufactured by Nippon Chemical Industrial Co., Ltd.) (Figure) See 8).

[0155] The composite oxide having lithium, transition metal, and oxygen in step S25 has defects and strain. It is preferable to have a layered rock salt type crystal structure with few impurities. It is preferable that it be a composite oxide. A composite oxide having lithium, a transition metal and oxygen is preferable. A high concentration of pure substances increases the likelihood of a crystal structure with many defects or distortions.

[0156] In this case, the positive electrode active material 100C may have cracks. Cracks are, for example, st It occurs in any or more of the processes from step S21 to step S25. This occurs during the firing process in step S23. The firing temperature, the heating or cooling of the firing process. The number of cracks that occur may vary depending on conditions such as the speed of the process. Also, for example, It can also occur during processes such as mixing and grinding.

[0157] <Step S31> Next, the mixture 902 is mixed with a composite oxide having lithium, a transition metal, and oxygen. (Step S31 in Figures 6 and 8). Composite having lithium, transition metal and oxygen. The number of atoms TM of the transition metal in the oxide and the number of atoms MgM of magnesium in mixture 902. The ratio with ix1 is TM:MgMix1 = 1:y (0.005 ≤ y ≤ 0.05). It is preferable that TM:MgMix1 = 1:y (0.007 ≤ y ≤ 0.04). Preferably, TM:MgMix1 = 1:0.02 is even more preferable.

[0158] The mixing in step S31 is performed in order to avoid destroying the composite oxide particles, as is the case with the mixing in step S12. It is preferable to use milder conditions. For example, a higher rotational speed than the mixing in step S12. It is preferable to have conditions with less or shorter duration. Also, dry processing is gentler than wet processing. It can be said that these are favorable conditions. For mixing, for example, a ball mill or bead mill can be used. To do so. When using a ball mill, for example, zirconia balls can be used as the media. It is preferable.

[0159] <Step S32, Step S33> The materials mixed above are collected (step S32 in Figures 6 and 8) to obtain mixture 903. (Step S33 in Figures 6 and 8).

[0160] In this embodiment, the mixture of lithium fluoride and magnesium fluoride is treated as an impurity. Although a method of adding to lithium cobalt oxide with low concentration is described, one aspect of the present invention is This is not the only option. Instead of mixture 903 in step S33, lithium cobalt oxide is used as the starting material. You may also use materials that have been calcined with added magnesium and fluorine sources. This includes the processes of steps S11 to S14 and steps S21 to S25. Because there is no need to separate the processes, it is simple and highly productive.

[0161] Alternatively, lithium cobalt oxide with pre-added magnesium and fluorine can be used. It may also be used. If lithium cobalt oxide with magnesium and fluorine added is used, Steps up to S32 can be omitted, making the process simpler.

[0162] Furthermore, lithium cobalt oxide, which has magnesium and fluorine added to it beforehand, Furthermore, a magnesium source and a fluorine source may be added.

[0163] <Step S34> Next, the mixture 903 is heated. This step is annealed to distinguish it from the previous heating step. Alternatively, it may involve a second heating process.

[0164] Annealing is preferably carried out at an appropriate temperature and time. The particle size of the composite oxide having lithium, transition metal and oxygen in step S25 It varies depending on conditions such as composition. If the particles are small, a lower temperature or Shorter durations may be preferable in some cases.

[0165] For example, if the average particle size (D50) of the particles in step S25 is about 12 μm, annealing The temperature is preferably between 600°C and 950°C. The annealing time is, for example, 3 hours or more. Preferably, 10 hours or more is preferred, more preferably 60 hours or more.

[0166] On the other hand, if the average particle size (D50) of the particles in step S25 is about 5 μm, the annealing temperature The temperature is preferably between 600°C and 950°C. The annealing time is, for example, between 1 hour and 10 hours. Less than 1 hour is preferable, and around 2 hours is more preferable.

[0167] The cooling time after annealing is preferably, for example, 10 hours or more and 50 hours or less.

[0168] When mixture 903 is annealed, first the material with the lower melting point from mixture 902 (for example, fluorine) It is thought that lithium oxide (melting point 848°C) melts and is distributed on the surface of the composite oxide particles. Next, the presence of this molten material causes a decrease in the melting point of other materials, which in turn causes the other materials to melt. It is presumed that, for example, magnesium fluoride (melting point 1263°C) melts and becomes a composite oxide. It is thought to be distributed on the surface layer of the particles.

[0169] The elements present in the mixture 902 distributed on the surface are lithium, transition metals, and oxygen. It is thought to form a solid solution in the composite oxide containing [the specified element].

[0170] The elemental diffusion of this mixture 902 occurs more in the surface and within the composite oxide particles than within them. The reaction is faster near grain boundaries. Therefore, magnesium and halogens are concentrated in the surface layer and near grain boundaries. As described later, the magnesium concentration in the surface layer and near the grain boundaries is higher than in the interior. When the value is high, changes in the crystal structure can be suppressed more effectively.

[0171] <Step S35, Step S36> The annealed material is recovered as described above (step S35 in Figures 6 and 8), and the positive electrode active material 10 Obtain 0A_1 (step S36 in Figures 6 and 8).

[0172] [Method for preparing positive electrode active material 2] The positive electrode active material 100A_1 obtained in step S36 may be subjected to further processing. Here, a process is carried out to add metal Z. This process is performed after step S25. By doing so, the concentration of metal Z in the particle surface layer of the positive electrode active material is made higher than in the interior. This is possible in some cases, which is preferable.

[0173] Furthermore, the addition of metal Z is, for example, in step S31, metal Z together with the mixture 902, etc. This may be done by mixing materials having the same properties. In this case, the number of steps can be reduced and the process can be simplified. It is preferable for this reason.

[0174] Alternatively, as will be explained below, after steps S31 to S35, the metal Z is added. Additional steps may be taken. In this case, for example, the formation of a compound between magnesium and metal Z may be suppressed. It can be controlled in some cases.

[0175] The positive electrode active material of one embodiment of the present invention is obtained through the following steps S41 to S53. Next, metal Z is added. The addition of metal Z can be done, for example, by liquid-phase methods such as the sol-gel method. Solid-state method, sputtering method, vapor deposition method, CVD (chemical vapor deposition), PLD (pulsed laser) Methods such as the deposition method can be applied. The addition of metal M2 mentioned earlier is, for example, This can be done using the metal Z addition process described below.

[0176] <Step S41> As shown in Figure 7, first in step S41, the metal source is prepared. When applying the method, prepare the solvent to be used in the sol-gel method. As the metal source, use metallic aluminum. Coxides, metal hydroxides, metal oxides, etc. can be used. Metal Z is aluminum. In this case, for example, the number of cobalt atoms in lithium cobalt oxide is set to 1, and the metal source is The concentration of aluminum should be between 0.001 and 0.02 times. In the case of Kell, for example, the number of cobalt atoms in lithium cobalt oxide is set to 1, and the metal source The nickel concentration should be between 0.001 and 0.02 times. In the case of titanium and nickel, for example, the cobalt atoms in lithium cobalt oxide With the number set to 1, the concentration of aluminum in the metal source is between 0.001 and 0.02 times, or Furthermore, the nickel concentration in the metal source should be between 0.001 times and 0.02 times.

[0177] Here, as an example, the sol-gel method is applied, and aluminum isopropoxy is used as the metal source. The example shown uses isopropanol as the solvent (Step S41 in Figure 9).

[0178] <Step S42> Next, the aluminum alkoxide is dissolved in alcohol, and then lithium cobaltate is added. The particles are mixed (step S42 in Figures 7 and 9).

[0179] The required amount of metal alkoxide varies depending on the particle size of lithium cobalt oxide. For example, When using luminium isopropoxide, the particle size (D50) of lithium cobaltate is 20 For particles of approximately μm size, the number of cobalt atoms in lithium cobalt oxide is considered to be 1, and aluminum The aluminum concentration in the isopropoxide is between 0.001 times and 0.02 times. It is preferable to add it.

[0180] Next, a mixture of an alcoholic solution of metal alkoxide and lithium cobalt oxide particles is added to water. Stir in a steam-containing atmosphere. Stirring can be done, for example, with a magnetic stirrer. The stirring time is necessary to allow the water in the atmosphere and the metal alkoxide to undergo hydrolysis and polycondensation reactions. Any sufficient amount of time is fine, for example, 4 hours at 25°C and 90% RH humidity (Relative It can be performed under conditions of humidity (relative humidity). Also, humidity control, In an atmosphere where temperature control is not available, for example, in the atmospheric environment inside a fume hood You may then stir the mixture. In such cases, it is preferable to increase the stirring time. For example, you could leave it at room temperature for 12 hours or more.

[0181] By reacting water vapor in the atmosphere with metal alkoxides, it is possible to achieve a higher rate than when adding liquid water. This also allows the sol-gel reaction to proceed slowly. Furthermore, metal alkoxides and water can be reacted at room temperature. By doing so, for example, when heating at a temperature exceeding the boiling point of the solvent alcohol, The sol-gel reaction can be carried out slowly. This allows for the formation of a high-quality coating layer with uniform thickness.

[0182] <Step S43, Step S44> After the above processing is complete, the precipitate is recovered from the mixture (step S43 in Figures 7 and 9). Recovery methods include filtration, centrifugation, and evaporation to dryness. The precipitate is gold. The alkoxide can be washed with the same alcohol used to dissolve it. When applying the drying method, it is not necessary to separate the solvent and precipitate in this step. For example, in the drying process of the next step (step S44), the precipitate can be recovered. stomach.

[0183] Next, the recovered residue is dried to obtain mixture 904 (step S44 in Figures 7 and 9). The drying process can be, for example, vacuum or forced-air drying at 80°C for 1 to 4 hours. Cut.

[0184] <Step S45> Next, the resulting mixture 904 is calcined (step S45 in Figures 7 and 9).

[0185] The baking time should preferably be between 1 hour and 50 hours within the specified temperature range. Ideally, the baking time should be between 2 and 20 hours. If the baking time is too short, the surface layer will be formed. Compounds containing metal Z may have low crystallinity. Alternatively, the diffusion of metal Z may be insufficient. This can happen. Or organic matter may remain on the surface. However, if the firing time is long If too much diffusion occurs, there is a risk that the concentration of metal Z will become low in the surface layer and near the grain boundaries. Furthermore, productivity will decline.

[0186] The specified temperature is preferably between 500°C and 1200°C, and between 700°C and 920°C. More preferably, 800°C to 900°C is preferred. If the specified temperature is too low, the table will not display The crystallinity of the compound containing metal Z formed in the layer may be low. Alternatively, the metal Z Insufficient diffusion may occur, or organic matter may remain on the surface.

[0187] Furthermore, firing is preferably carried out in an oxygen-containing atmosphere. When the oxygen partial pressure is low, the firing temperature If the level is not lowered further, there is a risk of Co being reduced.

[0188] In this embodiment, the specified temperature is set to 850°C and maintained for 2 hours, and the temperature rise is 200 The temperature is set to °C / h, and the oxygen flow rate is 10 L / min.

[0189] For cooling after firing, a longer cooling time is preferable as it helps stabilize the crystal structure. If so, it is preferable that the cooling time from the specified temperature to room temperature be between 10 hours and 50 hours. Here, the firing temperature in step S45 is higher than the firing temperature in step S34. A low value is preferable.

[0190] <Step S46, Step S47> Next, the cooled particles are collected (step S46 in Figures 7 and 9). Furthermore, the particles are Sifting is preferable. In the above process, the positive electrode active material 100A_ according to one embodiment of the present invention Item 2 can be produced (step S47 in Figures 7 and 9).

[0191] Furthermore, after step S47, the process is repeated from step S41 to step S46. You may do so. The number of repetitions can be once or two or more times.

[0192] Furthermore, when processing multiple times, the type of metal source used may be the same or different. It is acceptable. If different materials are used, for example, if an aluminum source is used in the first process, A nickel source can be used in the second processing step.

[0193] <Step S51> Next, a compound containing element X is prepared as the first raw material 901 (see Figures 7 and 9). Step S51).

[0194] In step S51, the first raw material 901 may be crushed. For example, a ball may be used for crushing. Mills, bead mills, etc., can be used. The powder obtained after grinding is separated using a sieve. You can give it a grade.

[0195] The first raw material 901 is a compound containing element X, and phosphorus can be used as element X. It is possible. Furthermore, the first raw material 901 is preferably a compound having a bond between element X and oxygen. It's nice.

[0196] For example, a phosphate compound can be used as the first raw material 901. A phosphoric acid compound having element D can be used. Element D is lithium, sodium , selected from potassium, magnesium, zinc, cobalt, iron, manganese and aluminum It is one or more elements. In addition, a phosphoric acid compound containing hydrogen in addition to element D can be used. Yes, it is possible. Also, ammonium phosphate and ammonia containing element D are used as phosphate compounds. Salt can be used.

[0197] Examples of phosphate compounds include lithium phosphate, sodium phosphate, potassium phosphate, and magnesium phosphate. Nesium, zinc phosphate, aluminum phosphate, ammonium phosphate, lithium dihydrogen phosphate Examples include magnesium monohydrogen phosphate, lithium cobalt phosphate, etc. (Positive electrode active material) In particular, lithium phosphate and magnesium phosphate are preferred.

[0198] In this embodiment, lithium phosphate is used as the first raw material 901 (as shown in Figures 7 and 9). Step S51).

[0199] <Step S52> Next, the first raw material 901 obtained in step S51 and the positive electrode obtained in step S47 are used. Mix with the active material 100A_2 (step S52 in Figures 7 and 9). First raw material 901 This is because the positive electrode active material 100A_2 obtained in step S25 is 0.01 m per 1 mol. 0.1 mol or more, more preferably 0.02 mol or more and 0.08 mol or less It is preferable to mix the quantities. For mixing, for example, a ball mill, bead mill, etc. can be used. Yes, it is possible. The powder obtained after mixing may be classified using a sieve.

[0200] <Step S53> Next, the materials mixed above are heated (step S53 in Figures 7 and 9). Positive electrode active material In the preparation of this product, this step may not be necessary. If heating is required, 3 It is preferable to carry out the process at a temperature between 0°C and 1200°C, and between 550°C and 950°C. More preferably, around 750°C is preferable. If the temperature is too low, the starting material will decompose. This may result in insufficient melting. On the other hand, if the temperature is too high, the transition metal may be excessively reduced. Defects may occur due to reasons such as lithium evaporation.

[0201] Heating may generate a reaction product between the positive electrode active material 100A_2 and the first raw material 901. ru.

[0202] The heating time is preferably between 2 hours and 60 hours. The firing process involves using dry air or other water-based methods. This process should be carried out in an atmosphere with low humidity (for example, a dew point of -50°C or lower, more preferably -100°C or lower). Preferably, heating at 1000°C for 10 hours, with the temperature increase at 200°C / h, and drying The atmosphere flow rate is preferably 10 L / min. After that, the heated material is cooled to room temperature. It can be rejected. For example, if the cooling time from the specified temperature to room temperature is 10 hours or more and 50 hours or more It is preferable to place it at the bottom.

[0203] However, cooling to room temperature in step S53 is not mandatory. If there are no problems performing step 54, cooling may be limited to a temperature higher than room temperature.

[0204] <Step S54> The material fired as described above is recovered (step S54 in Figures 7 and 9), and a positive electrode containing element D is formed. Obtain the active material 100A_3.

[0205] Regarding positive electrode active material 100A_1, positive electrode active material 100A_2, and positive electrode active material 100A_3 You can refer to the description of the positive electrode active material 100A shown in Figure 2, etc.

[0206] (Embodiment 2) In this embodiment, a secondary battery having the positive electrode active material 100 described in the previous embodiment is used Examples of materials that can be used will be described. In this embodiment, the positive electrode, negative electrode and electrolytic Let's take a secondary battery, in which the liquid is enclosed in an outer casing, as an example.

[0207] [Positive electrode] The positive electrode comprises a positive electrode active material layer and a positive electrode current collector.

[0208] <Positive electrode active material layer> The positive electrode active material layer has at least a positive electrode active material. Further, the positive electrode active material layer may contain other substances such as a film on the surface of the active material, a conductive aid, or a binder in addition to the positive electrode active material.

[0209] As the positive electrode active material, the positive electrode active material 100 described in the previous embodiment can be used. By using the positive electrode active material 100 described in the previous embodiment, a secondary battery with high capacity and excellent cycle characteristics can be obtained.

[0210] As the conductive aid, a carbon material, a metal material, a conductive ceramic material, or the like can be used. Further, a fibrous material may be used as the conductive aid. The content of the conductive aid with respect to the total amount of the active material layer is preferably 1 wt% or more and 10 wt% or less, and more preferably 1 wt% or more and 5 wt% or less.

[0211] The conductive aid can form an electric conduction network in the active material layer. The conductive aid can maintain the electric conduction path between the positive electrode active materials. By adding a conductive aid to the active material layer, an active material layer having high electric conductivity can be realized.

[0212] As the conductive aid, for example, natural graphite, artificial graphite such as mesocarbon microbeads, carbon fibers, or the like can be used. As the carbon fibers, for example, carbon fibers such as mesophase pitch-based carbon fibers and isotropic pitch-based carbon fibers can be used. Further, as the carbon fibers, carbon nanofibers, carbon nanotubes, or the like can be used. The carbon nanotubes can be produced by, for example, a vapor phase growth method. Further, as the conductive aid, For example, carbon black (acetylene black (AB), etc.), graphite particles. Carbon materials such as ions, graphene, and fullerenes can be used. Also, for example, copper, Metal powders and fibers such as nickel, aluminum, silver, and gold, and conductive ceramic materials, etc. You can use it.

[0213] Furthermore, graphene compounds may be used as conductive additives.

[0214] Graphene compounds possess excellent electrical properties, including high conductivity, and high flexibility. It may possess excellent physical properties such as high mechanical strength. The compound has a planar shape. The graphene compound enables surface contact with low contact resistance. Furthermore, even thin materials can have very high conductivity, allowing for efficient use within the active material layer in small quantities. A conductive path can be formed. Therefore, graphene compounds are used as conductive additives. This is preferable because it increases the contact area between the active material and the conductive additive. By using a plate-drying device, the entire surface of the active material is covered with graphene, which is a conductive additive. It is preferable to form the compound as a coating. Furthermore, it may be possible to reduce electrical resistance. Therefore, it is preferable. Here, as graphene compounds, for example, graphene, multigraphene , or it is particularly preferable to use RGO. Here, RGO is, for example, graphene oxide ( This refers to compounds obtained by reducing graphene oxide (GO).

[0215] When using active materials with small particle sizes, for example, active materials with a particle size of 1 μm or less, the specific surface area of ​​the active material The coefficient of conductivity is large, requiring more conductive paths to connect the active materials. Therefore, the amount of conductive additive is large. This tends to happen, and relatively, the amount of active material carried decreases. If the amount decreases, the capacity of the secondary battery will decrease. In such cases, a conductive additive is used. When graphene compounds are used, even small amounts of graphene compounds efficiently form conductive paths. This is particularly preferable because it does not require reducing the amount of active material supported.

[0216] In the following example, a graphene compound is used as a conductive additive in the active material layer 200. An example of a cross-sectional configuration of the joint will be explained.

[0217] Figure 10(A) shows a longitudinal cross-sectional view of the active material layer 200. The active material layer 200 is made up of granular positive electrode active Substance 100, graphene compound 201 as a conductive additive, and a binder (not shown), Includes, where graphene compound 201 is, for example, graphene or multigraphene. It is preferable to use n. Here, the graphene compound 201 has a sheet-like shape. It seems so. Also, graphene compound 201 is a multigraphene, or (and) Multiple layers of graphene may partially overlap to form a sheet.

[0218] In the longitudinal section of the active material layer 200, as shown in Figure 10(B), within the active material layer 200 In the area, the sheet-like graphene compound 201 is dispersed in a generally uniform manner. (See Figure 10(B)) In the diagram, graphene compound 201 is schematically represented by a thick line, but in reality, it is a single layer of carbon molecules. Alternatively, it is a thin film with multiple layers of thickness. Multiple graphene compounds 201 are multiple granular positive The material is applied so as to partially cover the electrode active material 100, or on the surface of multiple granular positive electrode active materials 100. Because they are formed to adhere to each other, they are in surface contact with one another.

[0219] Here, multiple graphene compounds bond together to form a network of graphene compounds. Forming a material sheet (hereinafter referred to as graphene compound net or graphene net) This is possible. When the active material is covered with a graphene net, the graphene net interacts with the active material. It can also function as a binder to combine them. Therefore, the amount of binder can be reduced. Because it is possible or not to use the active material in relation to the electrode volume and electrode weight The ratio can be improved. In other words, the capacity of the secondary battery can be increased.

[0220] Here, graphene oxide is used as graphene compound 201 and mixed with the active material to produce the active material It is preferable to form a layer that will become the 200th layer and then reduce it. Formation of graphene compound 201 Furthermore, by using graphene oxide, which has extremely high dispersibility in polar solvents, graphene Compound 201 can be dispersed approximately uniformly within the active material layer 200. The solvent is volatilized and removed from the dispersion medium containing dispersed graphene oxide, and the graphene oxide is returned. Therefore, the graphene compound 201 remaining in the active material layer 200 partially overlaps, By being dispersed to the extent that they are in surface contact with each other, a three-dimensional conductive path can be formed. Furthermore, the reduction of graphene oxide may be carried out, for example, by heat treatment, or by using a reducing agent. You may go.

[0221] Therefore, unlike granular conductive additives such as acetylene black that make point contact with the active material, the graph Since compound 201 enables surface contact with low contact resistance, it is not a typical conductive additive. This method improves the electrical conductivity between granular positive electrode active material 100 and graphene compound 201 using a smaller amount. This can be done. Therefore, the ratio of positive electrode active material 100 in the active material layer 200 can be increased. This allows for an increase in the discharge capacity of the secondary battery.

[0222] Furthermore, by using a spray drying device beforehand, the entire surface of the active material is covered with a conductive additive. A graphene compound is formed as a coating, and the spaces between the active materials are further separated by the graphene compound. It is also possible to form conductive paths.

[0223] Examples of binders include styrene-butadiene rubber (SBR) and styrene-isopropyl alcohol. Lenyl-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene- It is preferable to use a rubber material such as a propylene-diene copolymer as a binder. Therefore, fluororubber can be used.

[0224] Furthermore, it is preferable to use a water-soluble polymer as the binder. As molecules, for example, polysaccharides can be used. As for polysaccharides, carboxymethyl Cholecellulose (CMC), methylcellulose, ethylcellulose, hydroxypropyl Cellulose derivatives such as cellulose, diacetylcellulose, and regenerated cellulose, and starch These can be used. In addition, these water-soluble polymers can be used in combination with the aforementioned rubber material. It is even preferable if used.

[0225] Alternatively, the binder could be polystyrene, methyl polyacrylate, or polymethacrylic acid. Methyl (polymethyl methacrylate, PMMA), sodium polyacrylate, polyvinyl Polyalcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, Polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene Polyethylene, polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), ethylene propylene diene polymer It is preferable to use materials such as polyvinyl acetate and nitrocellulose.

[0226] You may use a combination of several of the binders mentioned above.

[0227] For example, a material with particularly excellent viscosity-modifying properties may be used in combination with other materials. For example, rubber materials have excellent adhesive and elastic properties, but when mixed with a solvent, it is difficult to adjust their viscosity. In such cases, for example, mixing with a material that has particularly excellent viscosity-modifying effects may be necessary. This is preferable. As a material with particularly excellent viscosity adjustment effect, for example, a water-soluble polymer can be used. Good. Also, as water-soluble polymers that are particularly excellent in viscosity adjustment, the aforementioned polysaccharides, for example, Boxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydrox Cellulose inducers such as cypropylcellulose, diacetylcellulose, and regenerated cellulose Conductors and starch can be used.

[0228] Furthermore, cellulose derivatives such as carboxymethylcellulose are, for example, carboxymethyl Solubility increases when cellulose is converted into salts such as sodium salts or ammonium salts. This makes it easier for the viscosity modifier to exert its effect. The increased solubility makes it easier for the electrode slurry to When preparing the Lee, it is also possible to improve the dispersibility of the active material and other components. In this case, the cellulose and cellulose derivatives used as electrode binders are: These salts shall also be included.

[0229] Water-soluble polymers stabilize viscosity by dissolving in water, and also act as active materials and binders. Other materials to be combined with them, such as styrene-butadiene rubber, are stable in aqueous solution. It can be dispersed. Furthermore, because it has functional groups, it is easily and stably adsorbed onto the surface of the active material. It is expected that this will happen. Also, cellulose derivatives such as carboxymethylcellulose are For example, many materials have functional groups such as hydroxyl groups and carboxyl groups, and because they have functional groups It is expected that the polymers will interact with each other and exist to broadly cover the surface of the active material.

[0230] When a binder covering or in contact with the surface of the active material forms a film, a passivation film and It is also expected to play a role in suppressing the decomposition of the electrolyte. Here, the passive membrane is, A film that does not conduct electricity, or has extremely low electrical conductivity, for example, on the surface of an active material. When a passivation film is formed, it suppresses the decomposition of the electrolyte at the battery reaction potential. Yes, it is possible. Furthermore, the passivation film suppresses electrical conductivity, while lithium ions can conduct electricity. That would be even better.

[0231] <Positive electrode current collector> As the positive electrode current collector, metals such as stainless steel, gold, platinum, aluminum, and titanium, and Highly conductive materials such as these alloys can be used. Also, materials used for the positive electrode current collector It is preferable that the material does not dissolve at the positive electrode potential. Also, silicon, titanium, neodymium, and Aluminum alloys to which elements that improve heat resistance, such as candium and molybdenum, have been added. It can be used. Furthermore, it can be formed with a metallic element that reacts with silicon to form a silicide. It may also be the case that, as a metallic element that reacts with silicon to form a silicide, zirconium, Titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten Examples include cellulose, cobalt, and nickel. Current collectors come in foil, plate (sheet), mesh, and perforated forms. Shapes such as metal-like or expanded metal-like can be used as appropriate. The current collector has a thickness It is best to use particles that are between 5 μm and 30 μm in size.

[0232] [Negative electrode] The negative electrode has a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer also contains a conductive additive. It may have a binder.

[0233] <Negative electrode active material> For example, alloy materials or carbon-based materials can be used as the negative electrode active material.

[0234] As a negative electrode active material, the charge-discharge reaction is carried out by alloying and dealloying reactions with lithium. Any possible element can be used. For example, silicon, tin, gallium, aluminum, Germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. Materials containing at least one of these elements can be used. Such elements have a capacity compared to carbon. Larger, and especially silicon, has a high theoretical capacity of 4200 mAh / g. Therefore, the negative electrode active material Silicon is preferred. Compounds containing these elements may also be used. For example, SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag 3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, Examples include InSb and SbSn. Here, charging and discharging occur through alloying and dealloying reactions with lithium. In some cases, elements capable of carrying out reactions, and compounds containing such elements, are referred to as alloying materials. be.

[0235] In this specification, SiO refers to silicon monoxide, for example. Alternatively, SiO refers to Si O x It can also be expressed as follows. Here, it is preferable that x has one neighboring value. For example, x is A value of 0.2 to 1.5 is preferred, and a value of 0.3 to 1.2 is more preferred.

[0236] Examples of carbon-based materials include graphite, easily graphitizable carbon (soft carbon), and poorly graphitizable carbon (hard carbon). Using carbon fiber, carbon nanotubes, graphene, carbon black, etc. stomach.

[0237] Examples of graphite include artificial graphite and natural graphite. For example, meso Examples include carbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite. Here, spheroidal graphite, which has a spherical shape, can be used as artificial graphite. For example, MCMB may have a spherical shape, which is preferable. Also, the surface of MCMB Reducing the product is relatively easy and sometimes preferable. Examples of natural graphite include Examples include flaky graphite and spheroidized natural graphite.

[0238] Graphite is formed when lithium ions are inserted into it (during the formation of lithium-graphite intercalation compounds). ) exhibits a potential as low as lithium metal (0.05V to 0.3V vs. Li / Li + This allows lithium-ion rechargeable batteries to exhibit a high operating voltage. Furthermore, graphite has a relatively high capacity per unit volume, relatively small volume expansion, and is inexpensive. It is preferable because it has advantages such as higher safety compared to lithium metal.

[0239] Furthermore, titanium dioxide (TiO2) and lithium titanium oxide (Li4) are used as negative electrode active materials. Ti5O 12 ), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5) ), use oxides such as tungsten oxide (WO2) and molybdenum oxide (MoO2). It is possible.

[0240] Furthermore, as the negative electrode active material, a Li3N type structure, which is a lithium and transition metal binitride, is also used. TsuLi 3-x M x N (M = Co, Ni, Cu) can be used. For example, Li 2. 6Co 0.4 The N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm²). 3 )of This is preferable.

[0241] When using a lithium-transition metal binitride, lithium ions are included in the negative electrode active material. In combination with materials such as V2O5 and Cr3O8 that do not contain lithium ions as the positive electrode active material. It is preferable that this be done. Furthermore, when using a material containing lithium ions as the positive electrode active material, Also, by pre-desorbing the lithium ions contained in the positive electrode active material, the negative electrode active material and Therefore, a lithium-transition metal composite can be used.

[0242] Furthermore, materials that undergo a conversion reaction can also be used as the negative electrode active material. For example For example, lithium, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO). Transition metal oxides that do not form alloys with mu may be used as the negative electrode active material. Conversion reaction Materials that produce this include Fe2O3, CuO, Cu2O, RuO2, and Cr2O3. Oxides such as CoS 0.89 , sulfides such as NiS and CuS, Zn3N2, Cu3N, Ge Nitrides such as 3N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3, etc. This also occurs with fluorides.

[0243] The conductive additives and binders that the negative electrode active material layer may have are, for example, the positive electrode active material layer Materials similar to those used for conductive additives and binders can be used.

[0244] <Negative electrode current collector> The negative electrode current collector can be made of the same material as the positive electrode current collector. It is preferable to use a material that does not alloy with carrier ions such as lithium.

[0245] [Electrolyte] An electrolyte solution contains a solvent and an electrolyte. A non-protic organic solvent is preferred as the solvent for the electrolyte solution. For example, ethylene carbonate (EC), propylene carbonate (PC), br Tylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyro Lactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate Tyl, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-Dioxane, 1,4-Dioxane, Dimethoxyethane (DME), Dimethyl Sulfane Hoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetra One of the following, or two or more of these: trahydrofuran, sulfolane, sultone, etc. It can be used in combinations and ratios.

[0246] Furthermore, as the solvent for the electrolyte, an ionic liquid (a room-temperature molten salt) that is flame-retardant and non-volatile is used. By using one or more of these devices, the internal temperature of the secondary battery may rise due to internal short circuits or overcharging. However, this can prevent secondary batteries from rupturing or catching fire. Ionic liquids are composed of cations and anions. It consists of and contains organic cations and anions. As organic cations used in the electrolyte, four quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations Aliphatic onium cations such as imidazolium cations and pyridinium cations, etc. Aromatic cations are an example. In addition, monovalent amides are used as anions in the electrolyte. Anions, monovalent methide anions, fluorosulfonate anions, perfluoroalkyl Anions of tetrafluoroborate, perfluoroalkyl volate Toanions, hexafluorophosphate anions, or perfluoroalkyl phosphates Examples include ether anions.

[0247] Furthermore, examples of electrolytes to be dissolved in the above solvent include LiPF6, LiClO4, and L. iAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO 4. Li2B 10 Cl 10 Li2B 12 Cl 12 LiCF3SO3, LiC4F9S O3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2 LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, etc. Using one type of thium salt, or two or more of these in any combination and ratio. It is possible.

[0248] The electrolyte used in secondary batteries contains particulate matter and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as " It is preferable to use a highly purified electrolyte with a low content of impurities (also called "foulings"). Specifically, the weight ratio of impurities to the electrolyte is 1% or less, preferably 0.1% or less. Preferably, the amount is 0.01% or less.

[0249] Furthermore, the electrolyte contains vinylene carbonate, propanesultone (PS), and tert-butyl. Benzene (TBB), fluoroethylene carbonate (FEC), lithium bis(oxa) LiBOB (Lithium-Borate), as well as dinitriles such as succinonitrile and adiponitrile. Additives such as solvent compounds may be added. The concentration of the added material should be, for example, relative to the total solvent. The concentration should be between 0.1 wt% and 5 wt%.

[0250] Alternatively, a polymer gel electrolyte, obtained by swelling a polymer with an electrolyte solution, may be used.

[0251] Using polymer gel electrolytes enhances safety against leakage and other issues. The pond can be made thinner and lighter.

[0252] Examples of polymers that can be gelled include silicone gel, acrylic gel, and acrylonitrile gel. Polyethylene oxide gel, polypropylene oxide gel, fluorine polymer Gels and the like can be used.

[0253] Examples of polymers include polyalkylene oxides such as polyethylene oxide (PEO). Polymers having a side structure, PVDF, polyacrylonitrile, etc., and those Copolymers containing the above can be used. For example, PVDF and hexafluoropropylene ( PVDF-HFP, a copolymer of HFP, can be used. The rimer may have a porous structure.

[0254] In addition, instead of an electrolyte, a solid electrolyte containing inorganic materials such as sulfide-based or oxide-based materials may be used. Solid electrolytes containing polymer materials such as PEO (polyethylene oxide) can be used. It is possible. When using a solid electrolyte, the installation of separators and spacers becomes unnecessary. Also, Because the entire battery can be made solid, the risk of leakage is eliminated, dramatically improving safety.

[0255] [Separator] Furthermore, it is preferable that the secondary battery has a separator. Examples of separators include: Paper, nonwoven fabric, glass fiber, ceramics, or nylon (polyamide), vinylon (poly (vinyl alcohol-based fibers), polyester, acrylic, polyolefin, polyurethane A separator made of synthetic fibers or the like can be used. It is preferable to process it into a shape and arrange it so as to enclose either the positive or negative electrode.

[0256] The separator may have a multilayer structure. For example, an organic material such as polypropylene or polyethylene. The material film contains ceramic-based materials, fluorine-based materials, polyamide-based materials, or a combination thereof. Mixtures and other materials can be coated onto it. Examples of ceramic materials include aluminum oxide. Aluminum particles, silicon oxide particles, etc. can be used. Examples of fluorine-based materials include PVDF, polytetrafluoroethylene, etc. can be used. Polyamide materials and For example, nylon, aramid (meta-aramid, para-aramid), etc. can be used. It is possible.

[0257] Coating with ceramic materials improves oxidation resistance, thus preventing separation during high-voltage charging and discharging. This can suppress the degradation of the data and improve the reliability of secondary batteries. Furthermore, fluorine-based materials... Coating the electrode makes it easier for the separator and electrode to adhere to each other, which can improve the output characteristics. Coating with polyamide materials, especially aramid, improves heat resistance, thus improving the heat resistance of secondary batteries. Safety can be improved.

[0258] For example, a mixture of aluminum oxide and aramid material is applied to both sides of a polypropylene film. It may also be done by applying aluminum oxide to the surface of the polypropylene film that is in contact with the positive electrode. A mixed material of um and aramid may be coated, and a fluorine-based material may be coated on the surface in contact with the negative electrode. .

[0259] Using a multilayer separator ensures the safety of secondary batteries even with a thin overall separator. Because this can be maintained, the capacity per unit volume of the secondary battery can be increased.

[0260] [Exterior] For the casing of a secondary battery, metal materials such as aluminum or resin materials are used. It is possible to have it. Also, a film-like outer covering can be used. For example, polyethylene, polypropylene, polycarbonate, ionomer, polyamide On a film made of materials such as aluminum, stainless steel, copper, nickel, etc., which have excellent flexibility A thin metal film is provided, and on the thin metal film, a polyamide resin, polyester resin, etc. are used as the outer surface of the exterior body. A three-layer film with an insulating synthetic resin film, such as a tellate resin, can be used.

[0261] [Charge / discharge method] The charging and discharging of a secondary battery can be performed, for example, as follows.

[0262] ≪CC charging≫ First, let's explain CC (constant current) charging as one of the charging methods. CC charging is a charging method. A constant current is supplied to the secondary battery throughout the entire period, and charging stops when a predetermined voltage is reached. This is the charging method. The secondary battery is charged as shown in Figure 11(A) with respect to its internal resistance R and secondary battery capacity C. Assume an equivalent circuit. In this case, the secondary battery voltage V B This is the voltage V across the internal resistance R. R and two Next, the voltage V across the battery capacity C. C It is the sum of.

[0263] While CC charging is in progress, the switch turns on, as shown in Figure 11(A), and remains constant. A current I flows through the secondary battery. During this time, since the current I is constant, V R = R × I Ohm According to the law, the voltage V across the internal resistance R R It is also constant. On the other hand, the secondary battery capacity C is Voltage V C The voltage increases over time. Therefore, the secondary battery voltage V B is, over time It rises with the surplus.

[0264] And the secondary battery voltage V B When the voltage reaches a predetermined level, for example 4.3V, charging stops. When CC charging is stopped, the switch turns off as shown in Figure 11(B), and the current I = 0. Therefore, the voltage V across the internal resistance R.R The voltage becomes 0V. Therefore, the secondary battery Voltage V B It will decline.

[0265] The secondary battery voltage V during CC charging and after CC charging has stopped. B and charging current An example is shown in Figure 11(C). The secondary battery voltage V was rising while CC charging was being performed. B but The data shows a slight decrease after CC charging is stopped.

[0266] ≪CCCV charging≫ Next, we will explain CCCV charging, which is a different charging method from the one described above. CCCV charging is, First, the battery is charged to a predetermined voltage using CC charging, and then the current flows through CV (constant voltage) charging. This charging method continues until the current level decreases, specifically until it reaches the cutoff current value.

[0267] While CC charging is in progress, the constant current power supply switch is turned on, as shown in Figure 12(A). The constant voltage power supply is switched off, and a constant current I flows to the secondary battery. During this time, Since I is constant, V R According to Ohm's law, =R × I, the voltage V across the internal resistance R is... R It is also constant. On the other hand, the voltage V across the secondary battery capacity C C It increases over time. Therefore, the secondary battery voltage V B It increases over time.

[0268] And the secondary battery voltage V B When the voltage reaches a predetermined level, for example 4.3V, CC charging stops Switch to CV charging. While CV charging is in progress, a constant voltage is applied as shown in Figure 12(B). The power switch is turned on, the constant current power supply switch is turned off, and the secondary battery voltage V B constant Yes. On the other hand, the voltage V across the secondary battery capacity C. C It increases over time. B = V R +V C Therefore, the voltage V across the internal resistance R R It decreases over time. The voltage V across the internal resistance R. R As V decreases, R According to Ohm's law, =R × I Therefore, the current I flowing through the secondary battery also decreases.

[0269] And when the current I flowing through the secondary battery becomes a predetermined current, for example, a current equivalent to 0.01C... Then, stop charging. When CCCV charging is stopped, as shown in Figure 12(C), all S The switch turns off, and the current I becomes 0. Therefore, the voltage V across the internal resistance R is lost. R is 0V This is the result. However, the voltage V across the internal resistance R due to CV charging R It has become sufficiently small Therefore, even if the voltage drop across the internal resistance R disappears, the secondary battery voltage V B It hardly descends. .

[0270] The secondary battery voltage V during CCCV charging and after CCCV charging has stopped. B and An example of the charging current is shown in Figure 13(A). Even when CCCV charging is stopped, the secondary battery voltage V B Gaho It is shown that they hardly descend at all.

[0271] ≪CC discharge≫ Next, we will explain CC discharge, one of the discharge methods. CC discharge is a discharge method that is used throughout the entire discharge period. A constant current is drawn from the secondary battery, and the secondary battery voltage V B when the voltage reaches a predetermined voltage, for example, 2.5V This is a discharge method that stops the discharge when it reaches a certain point.

[0272] The secondary battery voltage V during CC discharge B An example of discharge current is shown in Figure 13(B). As the charge progresses, the secondary battery voltage V B The image shows it descending.

[0273] Next, we will explain the discharge rate and charge rate. The discharge rate is the rate at which the battery capacity is charged relative to the battery capacity. This is the relative ratio of the current during discharge, and is expressed in units of C. In this case, the current equivalent to 1C is X(A). If discharged with a current of 2X(A), then 2 If the discharge was performed with a current of C, and the discharge was performed with a current of X / 5(A), then the discharge was performed with 0.2C. That is to say. Also, the charging rate is the same; if charged with a current of 2X(A), then 2C. If you say you charged it, and you charged it with a current of X / 5(A), then you can say you charged it at 0.2C. cormorant.

[0274] (Embodiment 3) In this embodiment, the form of a secondary battery having the positive electrode active material 100 described in the previous embodiment Let me explain an example of the shape. The material used in the secondary battery described in this embodiment is the same as in the previous embodiment. The description of the form can be taken into consideration.

[0275] [Coin-type rechargeable battery] First, let's explain an example of a coin-type rechargeable battery. Figure 14(A) shows a coin-type (single-layer flattened) battery. Figure 14(B) is an external view of a secondary battery of type (X), and is a cross-sectional view thereof.

[0276] The coin-type rechargeable battery 300 consists of a positive electrode casing 301 which also serves as the positive electrode terminal and a negative electrode casing which also serves as the negative electrode terminal. The can 302 is insulated and sealed with a gasket 303 made of polypropylene or the like. The positive electrode 304 consists of a positive electrode current collector 305 and a positive electrode active material layer 30 provided in contact with it. It is formed by 6. The negative electrode 307 is provided with the negative electrode current collector 308 and is set to be in contact with it. It is formed by the kerned negative electrode active material layer 309.

[0277] Furthermore, the positive electrode 304 and negative electrode 307 used in the coin-type secondary battery 300 are each active The material layer only needs to be formed on one side.

[0278] The positive electrode can 301 and negative electrode can 302 contain nickel and aluminum, which are corrosion-resistant to the electrolyte. Metals such as titanium, or alloys of these or alloys of these with other metals (for example, stainless steel) Steel, etc. can be used. In addition, nickel or aluminum can be used to prevent corrosion by the electrolyte. It is preferable to coat with aluminum or the like. Positive electrode can 301 is positive electrode 304, and negative electrode can 302 is negative electrode 3 Connect each of them electrically to 07.

[0279] These negative electrode 307, positive electrode 304, and separator 310 are impregnated with the electrolyte, as shown in Figure 14. As shown in B), with the positive electrode can 301 at the bottom, the positive electrode 304, separator 310, and negative electrode 307... The negative electrode can 302 is stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are connected by a gasket 303. A coin-type secondary battery 300 is manufactured by crimping it through a connector.

[0280] By using the positive electrode active material described in the previous embodiment for the positive electrode 304, high capacity cycling is achieved. This allows for the creation of a coin-type secondary battery 300 with excellent performance characteristics.

[0281] Here, we will use Figure 14(C) to explain the current flow during the charging of a secondary battery. Lithium is used. When a secondary battery is considered as a closed circuit, the movement of lithium ions and the flow of current are in the same direction. I'm curious about that. Also, in lithium-ion secondary batteries, the anode and cathode are used during charging and discharging. The cathode is swapped, and the oxidation and reduction reactions are reversed, so the reaction electricity The electrode with the higher potential is called the positive electrode, and the electrode with the lower reaction potential is called the negative electrode. Therefore, in this specification In this case, whether charging, discharging, or applying a reverse pulse current, Even when charging current is flowing, the positive terminal is called the "positive terminal" or "+ terminal (positive pole)," and the negative terminal is called the "positive terminal." The electrode will be called the "negative electrode" or "- electrode (minus electrode)". Using the terms anode and cathode in conjunction, during charging and discharging... This could be reversed and cause confusion. Therefore, the anode and cathode The term "cathode" will not be used in this specification. When using terms such as electrode or cathode, specify whether it is during charging or discharging. We will also indicate whether it corresponds to the positive (or negative) pole.

[0282] The charger is connected to the two terminals shown in Figure 14(C), and the secondary battery 300 is charged. As the secondary battery 300 charges, the potential difference between the electrodes increases.

[0283] [Cylindrical rechargeable battery] Next, refer to Figures 15(A), (B), (C), and (D) for examples of cylindrical rechargeable batteries. Let me explain. Figure 15(A) shows the external view of the cylindrical secondary battery 600. Figure 15(B) is This is a schematic diagram showing a cross-section of a cylindrical secondary battery 600. As shown in Figure 15(B) The cylindrical secondary battery 600 has a positive electrode cap (battery cover) 601 on its top surface, and the sides and The bottom surface has a battery can (outer casing) 602. These positive electrode cap and battery can (outer casing) 602 is insulated by gasket (insulating packing) 610.

[0284] Inside the hollow cylindrical battery can 602, there is a separator between the strip-shaped positive electrode 604 and the negative electrode 606. A battery element is provided, wound with a 605 in between. Although not shown in the diagram, the battery element is It is wound around the center pin. The battery can 602 is closed at one end and open at the other end. The battery can 602 contains nickel, aluminum, and titanium, which are corrosion-resistant to the electrolyte. Metals such as these, or alloys thereof, or alloys of these with other metals (for example, stainless steel, etc.) It can be used. In addition, nickel, aluminum, etc. can be used to prevent corrosion by the electrolyte. It is preferable to cover the battery can 602. Inside the battery can 602, the positive electrode, the negative electrode and The battery element, around which the separator is wound, is sandwiched between a pair of opposing insulating plates 608 and 609. Furthermore, the inside of the battery can 602, which is equipped with the battery element, contains a non-aqueous electrolyte (not shown). It is injected. The non-aqueous electrolyte can be the same as that used in coin-type rechargeable batteries. ru.

[0285] Since the positive and negative electrodes used in cylindrical storage batteries are wound, active material is formed on both sides of the current collector. It is preferable to do so. The positive electrode 604 is connected to the positive electrode terminal (positive electrode current collector lead) 603, and the negative The negative terminal (negative current collector lead) 607 is connected to pole 606. The positive terminal 603 and the negative Both electrode terminals 607 can be made of metal materials such as aluminum. Positive electrode terminal 6 Terminal 03 is resistance-welded to the safety valve mechanism 612, and the negative terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 uses a PTC element (Positive Temperature C It is electrically connected to the positive electrode cap 601 via the efficient)611. The safety valve mechanism 612 activates the positive electrode cap 601 when the internal pressure of the battery rises above a predetermined threshold. This disconnects the electrical connection between the positive electrode 604 and the positive electrode 611. Also, the PTC element 611 is at a certain temperature. This is a thermal resistance element whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current. This prevents abnormal heat generation. The PTC element uses barium titanate (BaTiO3) Semiconductor ceramics and the like can be used.

[0286] Furthermore, as shown in Figure 15(C), multiple secondary batteries 600 are connected to conductive plate 613 and conductive plate 61 Module 615 may be configured by sandwiching it between 4. Multiple secondary batteries 600 are connected in parallel. They may be connected in series, or they may be connected in parallel and then further connected in series. It may be continued. By configuring a module 615 having multiple secondary batteries 600 It can extract a large amount of power.

[0287] Figure 15(D) is a top view of module 615. Conductive plate 613 is shown in the diagram for clarity. This is shown by a dotted line. As shown in Figure 15(D), module 615 has multiple secondary batteries 600 It may have a conductive wire 616 that electrically connects them. A conductive plate may be superimposed on the conductive wire 616. It is possible to do so. Also, even if there is a temperature control device 617 between multiple secondary batteries 600 Good. When the secondary battery 600 overheats, the temperature control device 617 cools it down, and the secondary battery When 600 is too cold, it can be heated by the temperature control device 617. The performance of module 615 becomes less affected by ambient temperature. The temperature control device 617 has The heat transfer medium preferably has insulating and non-flammable properties.

[0288] By using the positive electrode active material described in the previous embodiment for the positive electrode 604, high capacity cycling is achieved. This allows for the creation of a cylindrical secondary battery 600 with excellent performance characteristics.

[0289] [Example of a secondary battery structure] Another example of a secondary battery structure will be explained using Figures 16(A) to 20(C).

[0290] Figures 16(A) and 16(B) show the external view of the battery pack. It has a circuit board 900 and a secondary battery 913. The secondary battery 913 also has a label 9 A 10 is attached. Furthermore, as shown in Figure 16(B), the secondary battery 913 has terminal 95 It has terminal 952.

[0291] The circuit board 900 has a circuit 912. Terminal 911 is connected to the circuit board 900. It is connected to the child 951, terminal 952, antenna 914, and circuit 912. Note that terminal 91 Multiple units 1 are provided, and each of the multiple terminals 911 is designated as a control signal input terminal, a power supply terminal, etc. That's fine.

[0292] Circuit 912 may be provided on the back surface of circuit board 900. Note that antenna 914 It is not limited to a coil shape, but may also be linear, plate-shaped, etc. Also, planar antenna, open Antennas such as surface antennas, traveling wave antennas, EH antennas, magnetic field antennas, dielectric antennas, etc. You may use a tenor.

[0293] Alternatively, antenna 914 may be a flat conductor. This flat conductor is for electric field coupling. It can function as one of the conductors. That is, of the two conductors that a capacitor has Antenna 914 may function as one of the conductors. This allows for electromagnetic and magnetic fields. Furthermore, it is also possible to exchange power using an electric field.

[0294] The battery pack has a layer 916 between the antenna 914 and the secondary battery 913. Layer 6 has the function of shielding electromagnetic fields, for example, from secondary batteries 913. For example, a magnetic material can be used as the sixth element.

[0295] Note that the structure of the secondary battery is not limited to those shown in Figures 16(A) and (B).

[0296] For example, as shown in Figures 17(A1) and 17(A2), Figures 16(A) and 16( In the secondary battery 913 shown in B), antennas may be provided on each of the opposing pair of surfaces. Figure 17(A1) is an external view showing one of the pair of surfaces mentioned above, and Figure 17(A2) is This is an external view showing the other side of the pair of faces described above. Note that Figures 16(A) and 16(B) are shown below. For parts that are the same as those of a secondary battery, see the explanation of the secondary battery shown in Figures 16(A) and 16(B). It can be used as appropriate.

[0297] As shown in Figure 17(A1), a layer 916 is sandwiched between one of the pair of surfaces of the secondary battery 913. An incubator 914 is provided, and as shown in Figure 17(A2), the other two sides of the secondary battery 913 An antenna 918 is provided on one side, with layer 917 in between. Layer 917 is, for example, a secondary battery 913 It has the function of shielding electromagnetic fields. For layer 917, for example, a magnetic material It can be used.

[0298] By adopting the above structure, the size of both antenna 914 and antenna 918 can be increased. It can be done. Antenna 918 can, for example, perform data communication with external devices. It has the ability to do so. Antenna 918 has a shape that can be applied to, for example, antenna 914. An antenna can be applied. Communication method between the secondary battery and other devices via antenna 918. In terms of the formula, it is used between a rechargeable battery and other devices, such as NFC (Near Field Communication). A variety of response methods can be applied.

[0299] Alternatively, as shown in Figure 17(B1), the secondary battery 9 shown in Figures 16(A) and 16(B) A display device 920 may be provided at 13. The display device 920 is electrically connected to terminal 911. It is not necessary to provide a label 910 in the area where the display device 920 is provided. For the same parts as the secondary battery shown in Figures 16(A) and 16(B), see Figure 16(A) and The explanation of secondary batteries shown in Figure 16(B) can be used as appropriate.

[0300] The display device 920 may display, for example, an image indicating whether or not it is charging, an image indicating the amount of stored power, etc. It may be displayed. The display device 920 may be, for example, electronic paper, liquid crystal display device, etc. A trollescent (also known as EL) display device can be used. For example, an electronic paper By using a supercharger, the power consumption of the display device 920 can be reduced.

[0301] Alternatively, as shown in Figure 17(B2), the secondary battery 9 shown in Figures 16(A) and 16(B) A sensor 921 may be provided at 13. The sensor 921 is connected to terminal 911 via terminal 922. It is electrically connected. Note that it is located in the same part as the secondary battery shown in Figures 16(A) and 16(B). Accordingly, the explanation of secondary batteries shown in Figures 16(A) and 16(B) can be appropriately referenced.

[0302] Sensor 921 can measure, for example, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, Light, liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, electric current, voltage, power, radiation, It should have the ability to measure flow rate, humidity, gradient, vibration, odor, or infrared radiation. i. By providing the sensor 921, for example, data indicating the environment in which the secondary battery is placed can be obtained. It can also detect parameters (such as temperature) and store them in the memory within circuit 912.

[0303] Furthermore, an example of the structure of the secondary battery 913 is explained using Figures 18(A), (B), and 19. I will reveal it.

[0304] The secondary battery 913 shown in Figure 18(A) has terminals 951 and 952 inside the housing 930. It has a wound body 950 provided. The wound body 950 is impregnated with an electrolyte inside the housing 930. Terminal 952 is in contact with the housing 930, and terminal 951 is in contact with the housing 930 by using an insulating material. It is not in contact with the housing 930. Note that in Figure 18(A), the housing 930 is separated for convenience. Although it is shown in the diagram, in reality the wound body 950 is covered by the housing 930, and terminals 951 and 9 52 extends outside the casing 930. The casing 930 is made of a metal material (e.g., aluminum). Aluminum (such as um) or resin materials can be used.

[0305] Furthermore, as shown in Figure 18(B), the housing 930 shown in Figure 18(A) is made of multiple materials. They may be formed as follows. For example, the secondary battery 913 shown in Figure 18(B) is formed as a housing 930a and housing 930b is bonded together, and the area enclosed by housing 930a and housing 930b is wound up 950 is provided.

[0306] For the enclosure 930a, insulating materials such as organic resins can be used. In particular, the antenna By using a material such as organic resin on the surface where the na is formed, the electric field produced by the secondary battery 913 is created. This can suppress shielding. If the shielding of the electric field by the housing 930a is small, the housing 930a Antennas such as antenna 914 and antenna 918 may be installed inside the enclosure 930b. For example, metal materials can be used.

[0307] Furthermore, the structure of the wound body 950 is shown in Figure 19. The wound body 950 consists of a negative electrode 931 and It has a positive electrode 932 and a separator 933. The wound body 950 sandwiches the separator 933. Then the negative electrode 931 and the positive electrode 932 are stacked on top of each other, and the stacked sheet is wound up. It is a body. Furthermore, the stacking of the negative electrode 931, the positive electrode 932, and the separator 933 is further Multiple layers can be stacked.

[0308] The negative electrode 931 is connected to Figures 16(A) and (B) via either terminal 951 or terminal 952. The positive terminal 932 is connected to terminal 951 and the other terminal 952. It is connected to terminal 911 shown in Figures 16(A) and (B).

[0309] By using the positive electrode active material described in the previous embodiment for the positive electrode 932, high capacity cycling is achieved. This allows for the creation of a secondary battery 913 with excellent performance characteristics.

[0310] [Laminated rechargeable battery] Next, for an example of a laminated secondary battery, please refer to Figures 20(A) to 26(B). Let me explain. A laminate-type secondary battery, if it has a flexible structure, will have flexibility. If implemented in an electronic device that has at least a part of it, the secondary battery will adapt to the deformation of the electronic device. It can also be bent.

[0311] Using Figures 20(A), (B), and (C), we will discuss the laminated secondary battery 980. Let me explain. The laminated secondary battery 980 has a wound body 993 as shown in Figure 20(A). The wound body 993 has a negative electrode 994, a positive electrode 995, and a separator 996. Body 993, similar to the wound body 950 explained in Figure 19, has a separator 996 in between and a negative electrode 9 94 and the positive electrode 995 are stacked on top of each other, and the stacked sheet is then rolled up.

[0312] The number of layers in the stack consisting of the negative electrode 994, positive electrode 995, and separator 996 is required. The design should be appropriate depending on the capacitance and element volume. The negative electrode 994 is connected to the lead electrode 997 and One end of electrode 998 is connected to a negative electrode current collector (not shown), and positive electrode 995 is connected to a lead The electrode 997 and the other lead electrode 998 are connected to a positive electrode current collector (not shown). .

[0313] As shown in Figure 20(B), there is a film 981 which will be the outer casing and a film 9 having a recess The aforementioned wound body 993 is housed in the space formed by bonding 82 and the other by heat pressing or the like. By doing so, a secondary battery 980 can be manufactured as shown in Figure 20(C). 93 has lead electrodes 997 and 998, and a film 981 and a recess The film 982 is impregnated with an electrolyte solution inside it.

[0314] Film 981 and film 982 having a recess are made of a metal material such as aluminum. Materials and resins can be used. Film 981 and film 982 having recesses If a resin material is used as the material, when an external force is applied, the film 981 and the recess will be affected. The film 982 having the property can be deformed, and a flexible storage battery can be manufactured. It is possible.

[0315] Furthermore, Figures 20(B) and 20(C) show examples where two films are used. By folding a single film, a space is formed, and the aforementioned wound body 9 is placed in that space. You may store 93.

[0316] By using the positive electrode active material described in the previous embodiment for the positive electrode 995, high capacity cycling is achieved. This allows for the creation of a secondary battery 980 with excellent performance characteristics.

[0317] Furthermore, in Figures 20(B) and (C), the film is wound around the space formed by the outer casing. An example of a secondary battery 980 having a body has been described, for example, Figures 21(A) and (B) As shown, multiple strip-shaped positive electrodes, separates, are placed in the space formed by the outer film. It may also be a secondary battery having a terminal and a negative electrode.

[0318] The laminated secondary battery 500 shown in Figure 21(A) consists of a positive electrode current collector 501 and a positive electrode active The positive electrode 503 has a material layer 502, and the negative electrode has a current collector 504 and a negative electrode active material layer 505. It has a negative electrode 506, a separator 507, an electrolyte 508, and an outer casing 509. A separator 507 is installed between the positive electrode 503 and the negative electrode 506 located within the housing 509. Furthermore, the inside of the outer casing 509 is filled with electrolyte 508. The electrolyte 508 contains, The electrolyte shown in Embodiment 2 can be used.

[0319] In the laminate-type secondary battery 500 shown in Figure 21(A), the positive electrode current collector 501 and The negative electrode current collector 504 also serves as a terminal for obtaining electrical contact with the outside. Therefore, Parts of the polar current collector 501 and the negative polar current collector 504 are exposed to the outside from the outer casing 509. They may also be placed in the casing 509. Furthermore, without exposing them to the outside, lead electrodes are used to connect the lead electrodes to the positive electrode current collector 501, or the negative electrode. The lead electrodes may be exposed to the outside by ultrasonic bonding with the current collector 504.

[0320] In the laminated secondary battery 500, the outer casing 509 is made of, for example, polyethylene, On a film made of materials such as polypropylene, polycarbonate, ionomer, and polyamide, A thin film of a highly flexible metal such as aluminum, stainless steel, copper, or nickel is provided, and further, An insulating synthetic material such as polyamide resin or polyester resin is used as the outer surface of the exterior body on a thin metal film. A three-layer laminate film with a resin film can be used.

[0321] Furthermore, an example of the cross-sectional structure of the laminate-type secondary battery 500 is shown in Figure 21(B). Figure 21 (A) shows an example consisting of two current collectors for simplicity, but in reality, Figure 21(B) As shown in (), it is composed of multiple electrode layers.

[0322] In Figure 21(B), the number of electrode layers is set to 16 as an example. However, the secondary battery 500 is flexible. In Figure 21(B), the negative electrode current collector 504 has 8 layers. The positive electrode current collector 501 has a total of 16 layers, consisting of 8 layers. Figure 21(B) shows the negative electrode. This shows a cross-section of the extraction section, where eight layers of negative electrode current collectors 504 are ultrasonically bonded. In theory, the number of electrode layers is not limited to 16; it can be more or fewer. In combination, it can be made into a secondary battery with a larger capacity. Also, the number of electrode layers is small. In some cases, this allows for a thinner design and a rechargeable battery with excellent flexibility.

[0323] Here, an example of the external view of the laminate-type secondary battery 500 is shown in Figures 22 and 23. Figures 22 and 23 show the positive electrode 503, negative electrode 506, separator 507, casing 509, and positive electrode ri It has a lead electrode 510 and a negative lead electrode 511.

[0324] Figure 24(A) shows the external view of the positive electrode 503 and the negative electrode 506. The positive electrode 503 is the positive electrode current collector 5 It has 01, and the positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501. Pole 503 has a region (hereinafter referred to as the tab region) in which the positive electrode current collector 501 is partially exposed. The electrode 506 has a negative electrode current collector 504, and the negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. This has been done. Also, the negative electrode 506 is the region where the negative electrode current collector 504 is partially exposed, i.e., the tab. It has a region. The area and shape of the tab regions of the positive and negative electrodes are as shown in the example in Figure 24(A). It's not limited.

[0325] [Method for manufacturing laminated rechargeable batteries] Here, an example of a method for manufacturing a laminate-type secondary battery, whose external view is shown in Figure 22, is shown in Figure 2. This will be explained using 4(B) and (C).

[0326] First, the negative electrode 506, separator 507, and positive electrode 503 are stacked. (See Figure 24(B) for stacking.) The negative electrode 506, separator 507, and positive electrode 503 are shown. Here, there are 5 sets of negative electrodes and positive electrodes. An example using four sets is shown. Next, the joining of the tab regions of the positive electrode 503 and the tab of the outermost positive electrode. The positive lead electrode 510 is joined to the b region. For joining, for example, ultrasonic welding is used. Similarly, the joining of the tab regions of the negative electrode 506 and the negative electrode to the tab region of the outermost negative electrode The lead electrodes 511 are joined.

[0327] Next, the negative electrode 506, separator 507, and positive electrode 503 are placed on the outer casing 509.

[0328] Next, as shown in Figure 24(C), fold the outer casing 509 along the dashed line. After that, the outer periphery of the exterior body 509 is joined. For joining, for example, heat compression bonding may be used. At that time, a part (or one side) of the outer casing 509 was made so that the electrolyte 508 could be added later. A region that is not connected to the main structure (hereinafter referred to as the inlet) is provided.

[0329] Next, the electrolyte 508 (not shown) is introduced through the inlet provided in the outer casing 509. Introduce into the inside of 509. Introduce electrolyte 508 under reduced pressure or inert atmosphere. It is preferable to do so. And finally, the inlet is joined. In this way, the laminate It is possible to manufacture a secondary battery of type 500.

[0330] By using the positive electrode active material described in the previous embodiment for the positive electrode 503, high capacity cycling is achieved. This allows for the creation of a secondary battery 500 with excellent performance characteristics.

[0331] [Bendable rechargeable battery] Next, Figures 25(A), (B1), and (B2) show examples of rechargeable batteries that can be bent. (C), (D), and Figures 26(A) and (B) will be explained with reference.

[0332] Figure 25(A) shows a schematic top view of a bendable secondary battery 250. Figure 25(B 1), (B2), and (C) correspond to the cutting lines C1-C2 and C3 in Figure 25(A), respectively. -C4 is a schematic cross-sectional view at the cutting line A1-A2. The secondary battery 250 is enclosed in the casing 251. It has a positive electrode 211a and a negative electrode 211b housed inside the outer casing 251. Lead 212a is electrically connected to 11a, and lead 212a is electrically connected to the negative electrode 211b. Lead 212b extends to the outside of the outer casing 251. Also, the area enclosed by the outer casing 251 In addition to the positive electrode 211a and the negative electrode 211b, an electrolyte (not shown) is sealed in the region. ru.

[0333] Regarding the positive electrode 211a and negative electrode 211b of the secondary battery 250, see Figure 26(A) and Let's explain using (B). Figure 26(A) shows the positive electrode 211a, the negative electrode 211b, and the separator. This is a perspective view illustrating the stacking order of electrode 214. Figure 26(B) shows the positive electrode 211a and the negative electrode 2 This is a perspective view showing leads 212a and 212b in addition to lead 11b.

[0334] As shown in Figure 26(A), the secondary battery 250 has multiple strip-shaped positive electrodes 211a, multiple It has a strip-shaped negative electrode 211b and a plurality of separators 214. Positive electrode 211a and negative electrode Each of the 211b has a protruding tab portion and a portion other than the tab. One of the positive electrodes 211a A positive electrode active material layer is formed on the part of the surface other than the tab, and on one side of the negative electrode 211b other than the tab. A negative electrode active material layer is formed in that area.

[0335] The sides of the positive electrode 211a that do not have a positive electrode active material layer formed on them, and the negative electrode active The positive electrode 211a and the negative electrode 211b are stacked so that their surfaces, which do not have any material formed on them, are in contact with each other. It will be done.

[0336] Furthermore, the surface on which the positive electrode active material of the positive electrode 211a is formed and the surface on which the negative electrode active material of the negative electrode 211b is formed A separator 214 is provided between the surfaces. In Figure 26(A), for clarity, Parator 214 is shown by a dotted line.

[0337] Also, as shown in Figure 26(B), the multiple positive electrodes 211a and leads 212a are connected at the joint 21 They are electrically connected at 5a. Also, multiple negative electrodes 211b and leads 212b are connected at the joint. It is electrically connected at 215b.

[0338] Next, the exterior body 251 will be explained using Figures 25(B1), (B2), (C), and (D). do.

[0339] The outer casing 251 has a film-like shape and sandwiches the positive electrode 211a and the negative electrode 211b. It is folded in half. The outer casing 251 has a folded portion 261 and a pair of sealing portions It has a 262 and a sealing portion 263. The pair of sealing portions 262 are positive electrode 211a and It is provided on either side of the negative electrode 211b and can also be called a side seal. Also, seal portion 2 Section 63 has a portion that overlaps with leads 212a and 212b, and is also called the top seal. It is possible.

[0340] The outer casing 251 has ridges 271 and valleys in the portion that overlaps with the positive electrode 211a and the negative electrode 211b. It is preferable that the 272 have a wave shape arranged alternately. Also, the sealing portion 2 of the outer casing 251 It is preferable that 62 and the sealing portion 263 are flat.

[0341] Figure 25(B1) is a cross-section cut at the point where it overlaps with ridge line 271, and Figure 25(B2) is This is a cross-section taken at the point where it overlaps with valley line 272. Figures 25(B1) and (B2) both show two This corresponds to the cross-section in the width direction of the next battery 250 and the positive electrode 211a and negative electrode 211b.

[0342] Here, the ends in the width direction of the positive electrode 211a and the negative electrode 211b, that is, the positive electrode 211a and The distance La is defined as the distance between the end of the negative electrode 211b and the seal portion 262. Secondary battery 25 When deformation such as bending is applied, the positive electrode 211a and the negative electrode 211b are as described later. They deform so that they are offset from each other in the longitudinal direction. In this case, if the distance La is too short, the outer casing 251 In some cases, the positive electrode 211a and the negative electrode 211b rub strongly against each other, causing damage to the outer casing 251. Yes. In particular, when the metal film of the outer casing 251 is exposed, the metal film is affected by the electrolyte. There is a risk of corrosion. Therefore, it is preferable to set the distance La as long as possible. That's true. On the other hand, if the distance La is made too large, the volume of the secondary battery 250 will increase. .

[0343] Furthermore, the thicker the combined thickness of the stacked positive electrode 211a and negative electrode 211b, the greater the positive electrode 21 It is preferable to increase the distance La between 1a and the negative electrode 211b and the seal portion 262. stomach.

[0344] More specifically, stacked positive electrode 211a and negative electrode 211b and (not shown) separate When the total thickness of 214 is t, the distance La is between 0.8 and 3.0 times the thickness t. Preferably, the ratio is 0.9 times or more and 2.5 times or less, more preferably 1.0 times or more and 2.0 times or less. It is preferable that the distance La is within this range, making it compact and resistant to bending. This enables the creation of highly reliable batteries.

[0345] Furthermore, when the distance between the pair of sealing portions 262 is denoted as distance Lb, distance Lb is set to the positive electrode 211 Make it sufficiently larger than the width of a and the negative electrode 211b (here, the width Wb of the negative electrode 211b). This is preferable. This allows the secondary battery 250 to be subjected to repeated bending or other deformations. Even if the positive electrode 211a and the negative electrode 211b come into contact with the outer casing 251, the positive electrode 211a and Because a portion of the negative electrode 211b can be shifted in the width direction, the positive electrode 211a and the negative electrode 211 This effectively prevents friction between b and the outer casing 251.

[0346] For example, the difference between the distance Lb between the pair of sealing portions 262 and the width Wb of the negative electrode 211b is positive. The thickness t of electrode 211a and negative electrode 211b is 1.6 times or more and 6.0 times or less, preferably 1.8 It is preferable that the ratio be between 2.0 and 4.0 times, and more preferably between 2.0 and 4.0 times. stomach.

[0347] In other words, it is desirable that the distance Lb, width Wb, and thickness t satisfy the relationship shown in Equation 1 below. It seems so.

[0348]

number

[0349] Here, a is 0.8 or more and 3.0 or less, preferably 0.9 or more and 2.5 or less, more preferably The value of 'k' satisfies 1.0 or greater and 2.0 or less.

[0350] Furthermore, Figure 25(C) shows a cross-section including lead 212a, secondary battery 250, positive electrode 211 This corresponds to the longitudinal cross-section of a and the negative electrode 211b. As shown in Figure 25(C), it is folded. In the ridge portion 261, the longitudinal ends of the positive electrode 211a and the negative electrode 211b, and the outer casing 25 It is preferable to have a space 273 between 1 and 1.

[0351] Figure 25(D) shows a schematic cross-sectional view of the secondary battery 250 when it is bent. ) corresponds to the cross-section at the cutting line B1-B2 in Figure 25(A).

[0352] When the secondary battery 250 is bent, a portion of the outer casing 251 located on the outside of the bend stretches inwards. Other parts located there deform to shrink. More specifically, the parts located on the outside of the outer casing 251 The part deforms so that the wave amplitude is small and the wave period is large. On the other hand, the outer body The portion located inside 251 is modified so that the wave amplitude is large and the wave period is small. Shape. In this way, the outer casing 251 deforms, and as it bends, the outer casing 251 Because the stress is relieved, the material that makes up the exterior 251 does not need to expand or contract. As a result, the outer casing 251 does not get damaged, and the secondary battery 250 can be bent with a small force. can.

[0353] Furthermore, as shown in Figure 25(D), when the secondary battery 250 is bent, the positive electrode 211a and the negative electrode The poles 211b and 211a are each shifted relative to each other. At this time, the multiple stacked positive electrodes 211a and Since one end of the negative electrode 211b on the sealing portion 263 side is fixed by the fixing member 217, Each part is shifted such that the amount of displacement increases the closer it is to the bent portion 261. The stress on pole 211a and negative pole 211b is relieved, and the positive pole 211a and negative pole 211 b itself does not need to expand or contract. As a result, the positive electrode 211a and the negative electrode 211b are not damaged. It can easily bend a 250-cell secondary battery.

[0354] Furthermore, there is a space 273 between the positive electrode 211a and the negative electrode 211b and the outer casing 251. By doing so, the positive electrode 211a and negative electrode 211b, which are located on the inside when bent, are positioned within the outer casing 25 It can shift relative to point 1 without making contact.

[0355] Examples are shown in Figures 25(A), (B1), (B2), (C), (D), and Figures 26(A) and (B). The secondary battery 250 shown can withstand repeated bending and straightening without damage to its casing, and the positive electrode 211a Furthermore, it is a battery that is less prone to damage to the negative electrode 211b and less likely to degrade in battery characteristics. The positive electrode 211a of the battery 250 is made using the positive electrode active material described in the previous embodiment. This allows for the creation of batteries with even better cycle characteristics.

[0356] (Embodiment 4) This embodiment describes an example of mounting a secondary battery, which is one aspect of the present invention, into an electronic device. I will reveal it.

[0357] First, as explained in part of Embodiment 3, a bendable secondary battery is mounted in an electronic device. Examples are shown in Figures 27(A) to 27(G). Examples of sub-devices include television equipment (also called televisions or television receivers). Monitors for computers, digital cameras, digital video cameras, digital cameras Mobile phone, mobile phone (also called mobile phone device), portable game console, portable information Examples include information terminals, sound playback devices, and large game machines such as pachinko machines.

[0358] Furthermore, rechargeable batteries with flexible shapes can be attached to the interior or exterior walls of houses and buildings, or to automatic It can also be integrated to conform to the curved surfaces of the car's interior or exterior.

[0359] Figure 27(A) shows an example of a mobile phone. The mobile phone 7400 has a housing 740 In addition to the display unit 7402 incorporated into 1, there are also operation buttons 7403, an external connection port 7404, It is equipped with speaker 7405, microphone 7406, etc. Note that mobile phone 7400 has two It has a secondary battery 7407. The secondary battery 7407 of the present invention is used in the above secondary battery 7407. This allows us to provide lightweight and long-lasting mobile phones.

[0360] Figure 27(B) shows the mobile phone 7400 in a curved state. When 00 is deformed by an external force and the whole thing is bent, the secondary electric charge located inside it The battery 7407 is also bent. Figure 27 shows the state of the bent secondary battery 7407 at that time. As shown in C), the secondary battery 7407 is a thin storage battery. The secondary battery 7407 is bent. It is fixed in place. The secondary battery 7407 has lead electrodes electrically connected to the current collector. It has a copper foil, which is partially alloyed with gallium and contacts the current collector. This improves adhesion with the active material layer, resulting in higher reliability of the 7407 secondary battery even when bent. It is structured as follows.

[0361] Figure 27(D) shows an example of a bangle-type display device. The portable display device 7100 is It comprises a housing 7101, a display unit 7102, operation buttons 7103, and a secondary battery 7104. Figure 27(E) also shows the state of the bent secondary battery 7104. The secondary battery 7104 is When worn on the user's arm in a bent state, the casing deforms, causing part of the secondary battery 7104 to be damaged. The curvature of the curve changes across the entire curve. Note that the degree of curvature at any point in the curve is the radius of the corresponding circle. The value expressed as is called the radius of curvature, and the reciprocal of the radius of curvature is called the curvature. Specifically, the half of the radius of curvature A portion of the main surface of the housing or secondary battery 7104, within a diameter range of 40 mm to 150 mm. Or the whole thing changes. The radius of curvature on the main surface of secondary battery 7104 is 40 mm or more 15 High reliability can be maintained within a range of 0 mm or less. The present invention applies to the secondary battery 7104 described above. By using a secondary battery of one form, a lightweight and long-lasting portable display device can be provided.

[0362] Figure 27(F) shows an example of a wristwatch-type personal information terminal. Personal information terminal 7200 The components are: housing 7201, display unit 7202, band 7203, buckle 7204, and operation button 7 It is equipped with terminals 205 and input / output terminals 7206, etc.

[0363] The 7200 mobile information terminal offers mobile phone calls, email, document viewing and creation, music playback, and more. It can run various applications such as internet communication and computer games. Cut.

[0364] The display unit 7202 has a curved display surface, and displays information along the curved surface. It is possible to do so. In addition, the display unit 7202 is equipped with a touch sensor, and the screen can be touched with a finger or stylus. It can be operated by touching it. For example, icon 7 displayed on the display unit 7202 Touching 207 will launch the application.

[0365] The 7205 control button is used for time setting, as well as power on / off, wireless communication on, and more. Various functions such as operation, activation and deactivation of silent mode, and activation and deactivation of power saving mode. It can be made to hold. For example, the operating system built into the personal digital assistant 7200 The system also allows you to freely configure the function of the control button 7205.

[0366] Furthermore, the 7200 portable information terminal is capable of performing standardized short-range wireless communication. For example, by communicating with a wireless headset, hands-free operation is possible. You can also make calls.

[0367] Furthermore, the portable information terminal 7200 is equipped with an input / output terminal 7206, and can connect to other information terminals. Data can be exchanged directly via this. Also, charging is possible via input / output terminal 7206. It can also perform electrical operations. Note that charging is done wirelessly without using input / output terminal 7206. You may go.

[0368] The display unit 7202 of the portable information terminal 7200 has a secondary battery according to one aspect of the present invention. By using a secondary battery according to one aspect of the present invention, a lightweight and long-lasting portable information terminal can be provided. For example, the secondary battery 7104 shown in Figure 27(E) is placed inside the housing 7201 in a curved shape. It can be incorporated either in its original state or in a flexible state within the band 7203.

[0369] The personal information terminal 7200 preferably has a sensor. For example, a fingerprint sensor. Human body sensors such as pulse sensors and body temperature sensors, as well as touch sensors, pressure sensors, and accelerometers. It is preferable that sensors, etc., be installed.

[0370] Figure 27(G) shows an example of an armband-type display device. The display device 7300 is a display unit The present invention has a secondary battery having 7304. Furthermore, the display device 7300 is The display unit 7304 can also be equipped with a touch sensor, and it can also function as a portable information terminal. It is also possible to do so.

[0371] The display unit 7304 has a curved display surface, and displays are performed along the curved display surface. This is possible. In addition, the display device 7300 can display information via standardized short-range wireless communication. The situation can be changed.

[0372] Furthermore, the display device 7300 is equipped with input / output terminals and can be directly connected to other information terminals via connectors. It can exchange data. It can also be charged via its input / output terminals. Furthermore, charging may be performed wirelessly without using input / output terminals.

[0373] By using a secondary battery according to one aspect of the present invention as the secondary battery of the display device 7300, We can provide lightweight and long-lasting display devices.

[0374] Furthermore, an example of mounting the secondary battery with good cycle characteristics shown in the previous embodiment into an electronic device is provided. This will be explained using Figures 27(H), 28(A), (B), (C), and 29.

[0375] By using a secondary battery according to one aspect of the present invention as a secondary battery in everyday electronic devices, a lightweight and long-lasting battery can be achieved. We can provide essential products. For example, everyday electronic devices such as electric toothbrushes and electric shavers. Examples include electric beauty devices, and the rechargeable batteries for these products are designed to be easy for the user to hold. The idea is to create a rechargeable battery that is small, lightweight, and high-capacity, with a stick-like shape.

[0376] Figure 27(H) is a perspective view of a device also known as a tobacco-containing smoking device (electronic cigarette). In Figure 27(H), the e-cigarette 7500 includes an atomizer 7501 containing a heating element, and The car includes a 7504 secondary battery that supplies power to the atomizer, and a liquid supply bottle and sensors. It consists of a 7502 cartridge. To enhance safety, overcharging of the secondary battery 7504 is prevented. A protection circuit to prevent over-discharge may be electrically connected to the secondary battery 7504. (See Figure 27(H)) The rechargeable battery 7504 has external terminals so that it can be connected to a charging device. The 7504 is the tip when held, so its overall length is shorter and its weight is lighter. It is desirable that the secondary battery according to one aspect of the present invention has high capacity and good cycle characteristics. The 7500 is a small and lightweight e-cigarette that can be used for extended periods of time. We can provide it.

[0377] Next, Figures 28(A) and 28(B) show an example of a foldable tablet device. As shown in Figures 28(A) and 28(B), the tablet terminal 9600 has a housing 963 0a, housing 9630b, movable part 9640 connecting housing 9630a and housing 9630b, front Display unit 9631 having display section 9631a and display section 9631b, switch 9625 to switch It has a latch 9627, a fastener 9629, and an operating switch 9628. The display unit 9631 has By using a flexible panel, a tablet terminal with a larger display area can be created. This is possible. Figure 28(A) shows the tablet terminal 9600 in an open state, and Figure 28 (B) shows the tablet device 9600 in the closed position.

[0378] Furthermore, the tablet terminal 9600 stores inside the housings 9630a and 9630b. It has an electric body 9635. The electric body 9635 passes through the movable part 9640 and the housing 9630a and the housing It is provided across body 9630b.

[0379] The display unit 9631 can have all or part of its area designated as a touch panel area, and By touching the image, text, input form, etc., including the icon displayed in that area, data can be collected. Input can be made. For example, keys can be placed on the entire surface of the display unit 9631a on the housing 9630a. The board buttons are displayed, and information such as text and images is shown on the display unit 9631b on the chassis 9630b. It may also be used to display information.

[0380] Furthermore, the keyboard is displayed on the display unit 9631b on the chassis 9630b side, and the chassis 9630 The display unit 9631a on side a may be used to display information such as characters and images. The touch panel keyboard display switching button is displayed in section 9631, By touching the button with a finger or stylus, the keyboard will be displayed on the display unit 9631. You can do that.

[0381] Furthermore, the touch panel area of ​​the display unit 9631a on the housing 9630a side and the housing 9630b side It is also possible to simultaneously input touch input to the touch panel area of ​​the display unit 9631b.

[0382] Furthermore, switches 9625 to 9627 are used to operate the tablet terminal 9600. It not only provides an interface for doing so, but also an interface that allows switching between various functions. It may also be used as a surface. For example, at least switch 9625 to switch 9627 It also functions as a switch to turn the tablet device 9600 on and off. It is also permissible to do so. Furthermore, for example, at least one of switches 9625 to 9627 may be A function to switch the display orientation, such as portrait or landscape, or to switch between black and white and color display. It may have a function to change. Also, for example, a small number of switches 9625 to 9627 At the very least, one may have a function to adjust the brightness of the display unit 9631. Also, the display unit 96 The brightness level of 31 is detected by the light sensor built into the tablet device 9600 during use. The optimal setting can be determined according to the amount of ambient light. Note that the tablet device uses a light sensor. In addition, it incorporates other detection devices such as gyroscopes, accelerometers, and other sensors that detect tilt. It's okay to store it.

[0383] Furthermore, Figure 28(A) shows the display unit 9631a on the housing 9630a side and the display on the housing 9630b side. The example shows that the display area of ​​the display unit 9631b is almost the same as that of the display unit 9631a and the display unit The display area of ​​each 9631b is not particularly limited, and one size can be different from the other. It is acceptable for them to have different display qualities. For example, one display may have a higher resolution than the other. It may also be used as a display panel capable of showing information.

[0384] Figure 28(B) shows the tablet terminal 9600 in a folded state. The T-type terminal 9600 consists of a housing 9630, a solar cell 9633, and a DC-DC converter 9636. It includes a charge / discharge control circuit 9634. Furthermore, as the energy storage body 9635, in one aspect of the present invention The aforementioned energy storage device is used.

[0385] As mentioned above, the 9600 tablet can be folded in half, so when not in use... The casings 9630a and 9630b can be folded so that they overlap. By folding it, the display unit 9631 can be protected, thus improving the durability of the tablet terminal 9600. Durability can be improved. Furthermore, the energy storage body 9635 using a secondary battery according to one aspect of the present invention is Due to its high capacity and good cycle characteristics, this tablet can be used for extended periods of time. We can provide the 9600 type terminal.

[0386] In addition, there is the tablet terminal 9600 shown in Figures 28(A) and 28(B). It has functions to display various information (still images, videos, text images, etc.), a calendar, and a date display. Alternatively, a function to display the time or other information on the display unit, or the information displayed on the display unit can be operated by touch input or edited. Touch input functionality, functions that control processing through various software (programs), It may have the following:

[0387] The solar cell 9633 attached to the surface of the tablet device 9600 provides power to the tablet. It can be supplied to the control panel, display unit, or video signal processing unit, etc. Note that the solar cell 96 33 can be provided on one or both sides of the housing 9630, and efficiently charges the energy storage unit 9635. This configuration can be implemented in a specific way. Note that the energy storage unit 9635 is a lithium-ion battery. Using it offers advantages such as enabling miniaturization.

[0388] Furthermore, the configuration and operation of the charge / discharge control circuit 9634 shown in Figure 28(B) are shown in Figure 28. (C) shows a block diagram and provides an explanation. Figure 28(C) shows a solar cell 9633 and a power storage unit 96 35. DC-DC converter 9636, converter 9637, switch SW1 to SW3, The display unit 9631 is shown, along with the energy storage unit 9635, the DC-DC converter 9636, and Converter 9637, switches SW1 to SW3, and the charge / discharge control circuit 9 shown in Figure 28(B) This corresponds to section 634.

[0389] First, let's explain an example of how the solar cell 9633 operates when generating electricity using ambient light. The electricity generated by the solar cells is converted into a DC-DC converter to provide the voltage necessary to charge the 9635 energy storage unit. The converter 9636 performs voltage boosting or bucking. Then, the solar power is used to control the operation of the display unit 9631. When power from pond 9633 is used, switch SW1 is turned ON, and converter 963 In step 7, the voltage is increased or decreased to the required voltage for the display unit 9631. Also, the display unit 963 If you do not want to display in step 1, turn SW1 off and turn SW2 on to enable the storage unit 9635. The configuration should include charging capabilities.

[0390] While solar cell 9633 is shown as an example of a power generation method, it is not particularly limited to this method. Storage using other power generation methods such as piezoelectric elements (piezo elements) and thermoelectric elements (Peltier elements) The configuration may also involve charging the battery 9635. For example, power may be transmitted and received wirelessly (contactlessly). This includes contactless power transmission modules that charge via this method, as well as configurations that combine this with other charging methods. You may do so.

[0391] Figure 29 shows an example of another electronic device. In Figure 29, the display device 8000 is the present invention. This is an example of an electronic device using a secondary battery 8004 according to one embodiment. Specifically, the display device 80 00 corresponds to a display device for receiving TV broadcasts, and consists of a housing 8001, a display unit 8002, and a speaker. It has a part 8003, a secondary battery 8004, etc. A secondary battery 8004 according to one aspect of the present invention is It is located inside the enclosure 8001. The display device 8000 receives power from the commercial power supply. You can receive power from it, or you can use the power stored in the secondary battery 8004. Therefore, even when power cannot be supplied from the commercial power source due to a power outage or the like, according to one aspect of the present invention By using the secondary battery 8004 as an uninterruptible power supply, the display device 8000 can be used. Yes.

[0392] The display unit 8002 has light-emitting elements such as liquid crystal display devices and organic EL elements in each pixel. Optical devices, electrophoresis display devices, DMDs (Digital Micromirror Dev ice), PDP (Plasma Display Panel), FED (Field Semiconductor display devices such as Emission Displays can be used.

[0393] In addition to being used for receiving TV broadcasts, the display devices are also used for personal computers and for displaying advertisements. This includes all information display devices.

[0394] In Figure 29, the fixed lighting device 8100 is a secondary battery 8 according to one aspect of the present invention. This is an example of an electronic device using 103. Specifically, the lighting device 8100 has a housing 8101, It has a light source 8102, a secondary battery 8103, etc. In Figure 29, the secondary battery 8103 is located in the housing 8 For example, consider the case where 101 and the light source 8102 are installed inside the ceiling 8104. Although shown, the secondary battery 8103 may also be located inside the housing 8101. The device 8100 can receive power from a commercial power source, or from a secondary battery 8103. It is also possible to use stored power. Therefore, in the event of a power outage, etc., power supply from commercial power source Even when it is not possible to receive a power supply, the secondary battery 8103 according to one aspect of the present invention can be used as an uninterruptible power supply. This makes it possible to use the lighting device 8100.

[0395] Figure 29 illustrates a fixed lighting device 8100 installed on the ceiling 8104. However, in one aspect of the present invention, the secondary battery is located on the side wall 8105, floor, and other surfaces besides the ceiling 8104. It can also be used in fixed lighting devices installed in windows such as 8106 and 8107, and also in tables It can also be used in overhead lighting fixtures and other applications.

[0396] Furthermore, the light source 8102 can use an artificial light source that artificially obtains light using electricity. Yes, it is possible. Specifically, this includes discharge lamps such as incandescent light bulbs and fluorescent lamps, and LEDs and organic EL elements. Optical elements are an example of the artificial light sources mentioned above.

[0397] In Figure 29, the air conditioner having an indoor unit 8200 and an outdoor unit 8204 is This is an example of an electronic device using a secondary battery 8203 according to one aspect of the present invention. Specifically, the room The internal unit 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, etc. (Figure 29) The example given is that the secondary battery 8203 is installed in the indoor unit 8200, but The next battery 8203 may be located in the outdoor unit 8204. Alternatively, it may be located in the indoor unit 8200 and the room The secondary battery 8203 may be provided on both sides of the outdoor unit 8204. - It can also receive power from the commercial power supply, or stored in the secondary battery 8203 Electricity can also be used. In particular, both the indoor unit 8200 and the outdoor unit 8204 can use secondary batteries 8 If 203 is installed, when power cannot be supplied from the commercial power source due to a power outage, etc. However, by using the secondary battery 8203 according to one aspect of the present invention as an uninterruptible power supply, Conditioner can be used.

[0398] Figure 29 shows a separate-type air conditioner consisting of an indoor unit and an outdoor unit. The example shown is an integrated air conditioner that has both the indoor and outdoor unit functions in a single housing. A secondary battery according to one aspect of the present invention can also be used in the conditioner.

[0399] In Figure 29, the electric refrigerator 8300 is a secondary battery 8304 according to one aspect of the present invention. This is an example of an electronic device using [a specific component]. Specifically, the electric refrigerator 8300 has a casing 8301, It has a refrigerator door 8302, a freezer door 8303, a secondary battery 8304, etc. In Figure 29, The secondary battery 8304 is located inside the casing 8301. The electric refrigerator 8300 is It can also receive power from the commercial power supply, or power stored in the secondary battery 8304 It is also possible to use this. Therefore, if power cannot be supplied from the commercial power source due to a power outage, etc. Even at times, by using the secondary battery 8304 according to one aspect of the present invention as an uninterruptible power supply, The 8300 refrigerator / freezer will become available for use.

[0400] Of the electronic devices mentioned above, high-frequency heating devices such as microwave ovens and electric rice cookers are included. Sub-devices require high power for short periods. Therefore, they need to supplement the power that cannot be supplied by the commercial power supply. By using a secondary battery according to one aspect of the present invention as an auxiliary power source to assist, electronic devices This prevents the commercial power circuit breaker from tripping when using it.

[0401] Furthermore, during periods when electronic devices are not in use, especially the total amount of electricity that can be supplied by the commercial power source... Of these, during the time periods when the proportion of electricity actually used (called the electricity usage rate) is low, By storing power in the secondary battery, the rate of power consumption outside of the above-mentioned time period is suppressed. It is possible. For example, in the case of the electric refrigerator 8300, when the temperature is low, the refrigerator door 83 02. At night when the freezer door 8303 is not opened or closed, power is supplied to the secondary battery 8304. Store. Then, as the temperature rises, the refrigerator door 8302 and the freezer door 8303 are opened and closed. During the daytime, by using the secondary battery 8304 as an auxiliary power source, daytime electricity usage The rate can be kept low.

[0402] According to one aspect of the present invention, the cycle characteristics of a secondary battery are improved, thereby enhancing reliability. This can be done. Furthermore, according to one aspect of the present invention, a high-capacity secondary battery can be made, and thus This improves the characteristics of secondary batteries, and therefore makes the secondary batteries themselves smaller and lighter. Therefore, a secondary battery, which is one aspect of the present invention, can be used in the electronic device described in this embodiment. By incorporating this technology, it becomes possible to create electronic devices with a longer lifespan and lighter weight. This configuration can be implemented in appropriate combination with other embodiments.

[0403] (Embodiment 5) This embodiment shows an example in which a secondary battery according to one aspect of the present invention is mounted on a vehicle.

[0404] When a secondary battery is installed in a vehicle, it can become a hybrid electric vehicle (HEV), an electric vehicle (EV), or This enables the realization of next-generation clean energy vehicles such as plug-in hybrid vehicles (PHEVs). ru.

[0405] Figures 30(A), (B), and (C) show a secondary battery that is one embodiment of the present invention. Let's look at an example of a vehicle. The automobile 8400 shown in Figure 30(A) uses electricity as its power source for driving. It is an electric vehicle that uses a motor. Or, it is an electric vehicle that uses an electric motor as a power source for driving. This is a hybrid vehicle in which the engine can be appropriately selected and used. One aspect of the present invention By using this, it is possible to realize a vehicle with a long driving range. In addition, the automobile 8400 is It has a secondary battery. The secondary battery is located on the floor portion inside the vehicle, as shown in Figures 15(C) and 15(D) The secondary battery modules shown in ) can be used in a row. Also, Figure 18(A) and ( A battery pack consisting of multiple secondary batteries as shown in B) may be installed on the floor of the vehicle. The secondary battery not only powers the electric motor 8406, but also the headlights 8401 and the lights. It can supply power to light-emitting devices such as home lights (not shown).

[0406] Furthermore, the secondary battery is used in the speedometer, tachometer, and other displays of the 8400 automobile. It can supply power to the display device. Furthermore, the secondary battery powers the navigation system of the 8400 automobile. It can supply power to semiconductor devices such as gate systems.

[0407] The automobile 8500 shown in Figure 30(B) plugs into the secondary battery of the automobile 8500. It can be charged by receiving power from an external charging facility using methods such as contactless power supply. It can be done. Figure 30(B) shows the ground-mounted charging device 8021 being mounted on the automobile 8500. This shows the state in which the secondary battery 8024 is being charged via cable 8022. Therefore, charging methods and connector specifications are subject to the standards of CHAdeMO (registered trademark) and Combo, etc. This can be done as appropriate. The charging device 8021 is a charging station installed in a commercial facility. However, it is also fine to use a household power supply. For example, plug-in technology allows external power to be supplied. The power supply can be used to charge the secondary battery 8024 installed in the 8500 vehicle. Charging is performed by converting AC power to DC power via a conversion device such as an AC / DC converter. It is possible.

[0408] Although not shown in the diagram, a power receiving device is mounted on the vehicle, and power is supplied wirelessly from a ground-based power transmission device. It can also be charged by supplying power. In this contactless power supply method, the power transmission equipment is installed on the road or exterior wall. By incorporating this, charging can be performed not only when the vehicle is stopped but also while it is in motion. The electric system may be used to transmit and receive power between vehicles. Furthermore, the exterior of the vehicle Solar panels may be installed to charge the secondary battery while the vehicle is stopped or in motion. Electromagnetic induction and magnetic resonance methods can be used to supply power in this environment.

[0409] Furthermore, Figure 30(C) shows an example of a motorcycle using a secondary battery according to one embodiment of the present invention. The scooter 8600 shown in 0(C) includes a secondary battery 8602, side mirrors 8601, and a directional indicator. It is equipped with an indicator light 8603. The secondary battery 8602 supplies power to the turn signal light 8603. It is possible.

[0410] Furthermore, the scooter 8600 shown in Figure 30(C) has a secondary battery 86 in the under-seat storage 8604. It can store 02. The secondary battery 8602 is small and the under-seat storage 8604 is small. It can also be stored in the under-seat storage compartment 8604. The secondary battery 8602 is removable. The 8602 secondary battery is carried indoors for charging and stored before driving. Just put it in.

[0411] According to one aspect of the present invention, the cycle characteristics of the secondary battery are improved, and the capacity of the secondary battery is increased. This allows for miniaturization and weight reduction of the secondary battery itself. Secondary battery Making the unit itself smaller and lighter would contribute to reducing the vehicle's weight, thus improving its range. Yes, it is possible. Furthermore, the secondary battery installed in the vehicle can also be used as a power source for purposes other than the vehicle itself. In this case, for example, it is possible to avoid using commercial power during peak electricity demand. Therefore, if we can avoid using commercial power during peak electricity demand, we can save energy and It can contribute to reducing carbon dioxide emissions. Also, if the cycle characteristics are good, two Because the next battery can be used for a long period of time, the amount of rare metals used, including cobalt, can be reduced. It is possible.

[0412] This embodiment can be implemented in appropriate combination with other embodiments. [Examples]

[0413] In this example, a positive electrode active material having magnesium, fluorine, and phosphorus is prepared, and the positive electrode We fabricated a secondary battery having a positive electrode made of an active material, and improved the continuous charge endurance and cycle life of the secondary battery. The characteristics were evaluated.

[0414] <Fabrication of positive electrode active material> The positive electrode active material was prepared by referring to the flowcharts in Figures 8 and 9. Alternatively, step S47 was not performed.

[0415] First, a mixture 902 containing magnesium and fluorine was prepared (as shown in Figure 8). Steps S11 to S14). The molar ratio of LiF to MgF2 is LiF:MgF2=1: The mixture was weighed to a value of 3, acetone was added as a solvent, and the mixture was mixed and ground using a wet process. The grinding was performed using a ball mill with zirconia balls at 150 rpm for 1 hour. The processed material was recovered and designated as mixture 902.

[0416] Next, a positive electrode active material containing cobalt was prepared (step S25). Here, As the synthesized lithium cobalt oxide, Cellseed C-10 manufactured by Nippon Chemical Industrial Co., Ltd. N was used. Cellseed C-10N is cobalt with a D50 of about 12 μm and low impurity content. It is lithium oxide.

[0417] Next, mixture 902 and lithium cobalt oxide were mixed (step S31). The amount of cobalt in lithium trioxide is relative to the amount of magnesium in mixture 902. The atomic weight conditions were varied. The values ​​for the condition variation were approximately 0.5%, 1.0%, 2.0%, and 3%. The materials were weighed to be 0.0% and 6.0%. The atomic weights of cium are shown in Tables 1 and 2 below. Mixing was performed using a dry method. Mixing was performed using a ball mill with zirconia balls at 150 rpm for 1 hour.

[0418] Next, the processed material was recovered to obtain mixture 903 (steps S32 and S32). 3).

[0419] Next, the mixture 903 is placed in an alumina crucible and heated in an oxygen atmosphere muffle furnace at 850°C, 6 The material was annealed for 0 hours (step S34). During annealing, the alumina crucible was covered. The oxygen flow rate was set to 10 L / min. The heating rate was set to 200°C / hr, and the cooling rate was set to 10 hours or more. The process was carried out. The material after heat treatment was collected (step S35), sieved, and magnesium The positive electrode active material (positive electrode active material 100A_1 shown in Figure 8) with the specified amount of um added was used. Obtained (Step S36). Below, magnesium concentrations of 0.5%, 1.0%, 2.0%, and 3% are used. Samples of positive electrode active material 100A_1 with concentrations of 0.0% and 6.0% were provided. 11. Sample 12. Sample 13. Samp These are called sample 14 and sample 15. The positive electrode will be described later. For the preparation, the positive electrode active material 100A_1 obtained in this step, and after this step, as described below... Both the positive electrode active material that underwent steps S51 to S54 described above and the positive electrode active material were used.

[0420] Subsequently, metal addition is not performed according to steps S42 to S47 shown in Figure 9. I advanced to the S51 class.

[0421] Next, lithium phosphate was prepared (step S51). Then, lithium phosphate and the cathode active Material 100A_1 was mixed (step S52). The amount of lithium phosphate mixed was the positive electrode The amount of active material 100A_1 was equivalent to 0.06 mol per 1 mol. The mixing was done by The process was carried out using a ball mill with luconia balls at 150 rpm for 1 hour. After mixing, 30 The mixture was then sieved through a 0 μm diameter sieve. After that, the resulting mixture was placed in an alumina crucible and covered. Then, it was annealed at 750°C for 20 hours in an oxygen atmosphere (Step S53). After that, 53μ The powder was recovered by sieving through an mφ sieve (Step S54). After the above process, phosphorus was obtained. A positive electrode active material to which a compound is added, and the amount of magnesium added is specified. The following are positive results for magnesium concentrations of 0.5%, 1.0%, 2.0%, 3.0%, and 6.0%. The most active materials are Sample 21 and Sample 2, respectively. 2. Sample 23, Sample 24 and Samp We obtained sample 25 (let's call it le).

[0422] <Manufacturing of secondary batteries> Each positive electrode was fabricated using the positive electrode active material obtained above. (Positive electrode active material, AB) A slurry made by mixing active material AB:PVDF = 95:3:2 (by weight) A current collector coated with the material was used. NMP was used as the solvent for the slurry.

[0423] After coating the current collector with slurry, the solvent was evaporated. Then, pressurization was applied at 210 kN / m. After that, further pressurization was applied at 1467 kN / m. Through the above process, the positive electrode was obtained. The load on the electrode is approximately 20 mg / cm³. 2 That's what I decided.

[0424] Using the fabricated positive electrode, a CR2032 type (20mm diameter, 3.2mm height) coin was used. A rechargeable battery of type [type] was manufactured.

[0425] Lithium metal was used for the counter electrode.

[0426] The electrolyte in the electrolyte solution contains 1 mol / L lithium hexafluoride phosphate (LiPF6). The electrolyte used is ethylene carbonate (EC) and diethyl carbonate (DEC). A mixture with an EC:DEC ratio of 3:7 (by volume) was used. The cycle characteristics were evaluated. For the secondary batteries that underwent this procedure, 2 wt% vinylene carbonate (VC) was added to the electrolyte. Ta.

[0427] A 25 μm thick polypropylene was used for the separator.

[0428] The positive electrode and negative electrode cans were made of stainless steel (SUS).

[0429] <Continuous charging endurance> Next, we evaluated the continuous charging endurance of each secondary battery using each of the fabricated positive electrode active materials. The evaluation was performed. First, the charge was set to CCCV (0.05C, 4.5V or 4.6V, termination current 0). (0.005C), discharged at CC (0.05C, 2.5V) for 2 cycles at 25°C. It was decided.

[0430] Subsequently, charging was performed at 60°C using CCCV (0.05C). The upper voltage limit was 4.55V. Alternatively, the voltage can be set to 4.65V, and the termination condition is when the secondary battery voltage is 0.01V less than the upper limit voltage. The time it took for the voltage to drop below (4.54V if it was 4.55V) was measured. If the voltage falls below the upper limit voltage, it may indicate a problem such as a short circuit. 1C was defined as 200mA / g.

[0431] The measured times for each secondary battery are shown in Tables 1 and 2. Table 1 is step The results shown are for the positive electrode active material obtained in S36, and Table 2 further shows the results for steps S51 to S Positive electrode active material produced via step S54, i.e., positive electrode active material to which phosphorus compounds have been added. This is the result of using quality.

[0432] [Table 1]

[0433] [Table 2]

[0434] Furthermore, regarding the results using the positive electrode active material obtained in step S36, the charging voltage was set to 4.5 Figure 31(A) shows the time-current characteristics when the voltage is 5V, and when the charging voltage is 4.65V. The time-current characteristics are shown in Figure 31(B).

[0435] Furthermore, the positive electrode active material produced through steps S51 to S54, namely phosphorus, For the results using a positive electrode active material with added compounds, the charging voltage was set to 4.55V. Figure 32(A) shows the time-current characteristics when the charging voltage is 4.65V. The characteristics are shown in Figure 32(B).

[0436] By adding phosphorus compounds, the time until a voltage drop occurs is extended, and continuous charging is possible. This suggested improved resistance. Furthermore, under conditions where the amount of Mg added was 2%, continuous charging This suggests a significant improvement in electrical resistance.

[0437] <Cycle Characteristics> Next, the cycle characteristics of the secondary batteries using each of the fabricated positive electrode active materials were evaluated. First, charge using CCCV (0.05C, 4.6V, cutoff current 0.005C), then discharge. The measurement was taken over two cycles at 25°C with CC (0.05C, 2.5V). After that, 25 At °C, charging is performed using CCCV (0.2C, 4.6V, cutoff current 0.02C), and discharging is performed using CC. The cycle characteristics were evaluated by repeatedly charging and discharging the device at (0.2C, 2.5V).

[0438] In Figures 33(A) and (B), the horizontal axis represents the cycle and the vertical axis represents the discharge capacity. Figure 33(A) is The results shown are for using the positive electrode active material obtained in step S36, and Figure 33(B) shows further steps The positive electrode active material prepared through steps S51 to S54, i.e., the addition of a phosphorus compound, These are the results obtained using the positive electrode active material.

[0439] Focusing on the rate of decrease in volume relative to the number of cycles, a significant difference can be observed depending on the magnesium concentration. No difference can be observed. On the other hand, the higher the magnesium addition concentration, the lower the initial volume. This was particularly noticeable. This is because the proportion of phosphorus compounds in the weight of the active material increased, and relatively This is thought to be because the proportion of cobalt decreases, and consequently, the proportion of substances contributing to the charge-discharge reaction decreases. . [Examples]

[0440] In this embodiment, the material has magnesium, fluorine, cobalt, and other metals besides cobalt. A positive electrode active material is fabricated, and a secondary battery having a positive electrode using the positive electrode active material is fabricated. Evaluate the XRD of the positive electrode after charging, the continuous charge endurance of the secondary battery, and the cycle characteristics of the secondary battery. did.

[0441] <Fabrication of positive electrode active material> Refer to the flows in Figures 8 and 9, and the positive electrode active material is Sample 30. Sample 35 was prepared. S54 was not performed.

[0442] First, regarding Sample 30 through Sample 35... A mixture 902 containing magnesium and fluorine was prepared (steps S11 to S11). (S14). Weigh the LiF and MgF2 so that the molar ratio is LiF:MgF2=1:3. Then, acetone was added as a solvent and the mixture was mixed and ground in a wet process. The mixing and grinding were carried out using zirconium. The process was carried out using a ball mill with near balls at 150 rpm for 1 hour. The processed material was then rotated. The mixture was harvested and prepared as mixture 902.

[0443] Next, regarding Sample 30 to Sample 35... As a positive electrode active material containing cobalt, Cellseed C-10N manufactured by Nippon Chemical Industrial Co., Ltd. Prepared (Step S25).

[0444] Next, regarding Sample 30 to Sample 35... Mixture 902 and lithium cobaltate were mixed (step S31). The atomic weight of magnesium in mixture 902 relative to the atomic weight of cobalt in thium. The mixture was weighed to a concentration of 2.0%. The mixing was done by dry mixing. The mixture consisted of zirconia balls. The process was performed using a ball mill at 150 rpm for 1 hour.

[0445] Next, regarding Sample 30 to Sample 35... The processed material was recovered to obtain mixture 903 (steps S32 and S33). .

[0446] Next, regarding Sample 30 to Sample 35... The mixture 903 was placed in an alumina crucible and heated in a muffle furnace under an oxygen atmosphere at 850°C for 60 hours. Annealing was performed (step S34). During annealing, the alumina crucible was covered. Oxygen The flow rate was set to 10 L / min. The heating rate was set to 200°C / hr, and the cooling rate was set to 10 hours or more. The process was carried out. The material after heat treatment was collected and sieved (step S35), and the positive electrode active material 10 0A_1 was obtained (step S36).

[0447] Next, regarding Sample 31 through Sample 35 Then, the processing in steps S41 to S46 was performed. In step 30, the addition of the metal source in steps S41 to S46 was not performed. Regarding Sample 31 to Sample 35, Using step S41, the positive electrode active material 100A_1 and the metal source were mixed. Also, depending on the circumstances, The solvent was also added and mixed in.

[0448] <<Aluminum Addition>> For Sample 31 and Sample 32, A coating layer containing aluminum was formed on the positive electrode active material 100A_1 using the sol-gel method. Al isopropoxide was used as the raw material, and 2-propanol was used as the solvent. In Sample 31, the atomic weight of aluminum is compared to that of cobalt and aluminum. Sample 32 uses KOBA so that it is 0.1% of the sum of the atomic weights. Each of the atoms was treated so that its atomic weight was 0.5% of the sum of the atomic weights of ruth and aluminum. Then, the resulting mixture is placed in an alumina crucible, covered, and heated in an oxygen atmosphere at 850°C. The powder was then annealed for 2 hours (step S45). After that, it was sieved through a 53 μm diameter sieve. The samples were recovered (step S46) and used as positive electrode active materials. Sample 31 and S We obtained ample (sample) 32.

[0449] <<Nickel Addition>> For Sample 33 and Sample 34, Nickel hydroxide, which is the metal source, and the positive electrode active material 100A_1 were mixed. In Sample 33, the atomic weight is calculated relative to the sum of the atomic weights of cobalt and nickel. To achieve a concentration of 0.1%, Sample 34 contains cobalt and nickel atoms. Each component was mixed to a concentration of 0.5% of the total volume. Zirconia balls were used for mixing. The process was carried out using a ball mill at 150 rpm for 1 hour. After mixing, the mixture was sieved through a 300 μm diameter sieve. Then, the resulting mixture was placed in an alumina crucible, covered, and left in an oxygen atmosphere for 8 minutes. Annealed at 50°C for 2 hours (Step S45). Then, sieved through a 53 μm diameter sieve. The powder is recovered (step S46), and Sample 33 is used as the positive electrode active material. Sample 34 was obtained.

[0450] <<Addition of aluminum and nickel>> For Sample 35, the metal source is nickel hydroxide, and the positive electrode activity The substance 100A_1 was ball-milled, and then aluminum was extracted by the sol-gel method. A coating layer containing the metal was formed. Al isopropoxide was used as the metal source, and 2 was used as the solvent. -Propanol was used. The atomic weights of nickel and aluminum were respectively... Mix so that the sum of the atomic weights of balt, nickel, and aluminum is 0.5%. Then, the resulting mixture was placed in an alumina crucible, covered, and heated in an oxygen atmosphere at 850°C. The powder was annealed at ℃ for 2 hours (Step S45). Then, it was sieved through a 53 μmφ sieve. The sample was recovered (step S46) and Sample 35 was obtained as the positive electrode active material. .

[0451] <Manufacturing of secondary batteries> Sample 30 to Sample 35 obtained above Each of these was used as the positive electrode active material to fabricate a positive electrode. Positive electrode active material, AB and PVD A slurry of F mixed with active material:AB:PVDF = 95:3:2 (by weight) is applied to the current collector. The processed material was used. NMP was used as the solvent for the slurry.

[0452] After coating the current collector with slurry, the solvent was evaporated. Then, pressurization was applied at 210 kN / m. After that, further pressurization was applied at 1467 kN / m. Through the above process, the positive electrode was obtained. The load on the electrode is approximately 20 mg / cm³. 2 That's what I decided.

[0453] Using the fabricated positive electrode, a CR2032 type (20mm diameter, 3.2mm height) coin was used. A rechargeable battery of type [type] was manufactured.

[0454] Lithium metal was used for the counter electrode.

[0455] The electrolyte in the electrolyte solution contains 1 mol / L lithium hexafluoride phosphate (LiPF6). The electrolyte used is ethylene carbonate (EC) and diethyl carbonate (DEC). A mixture with an EC:DEC ratio of 3:7 (by volume) was used. The cycle characteristics were evaluated as follows: For the rated secondary batteries, 2 wt% vinylene carbonate (VC) was added to the electrolyte. did.

[0456] A 25 μm thick polypropylene was used for the separator.

[0457] The positive electrode and negative electrode cans were made of stainless steel (SUS).

[0458] <XRD of the positive electrode> First, the XRD of the positive electrode was evaluated before charging and discharging. Figures 34(A) and (B) show... This shows the XRD of the positive electrode before charging and discharging. 2θ = 18.89° and 2θ = 38.3 A significant peak was observed at 5°. The horizontal axis of the graphs shown in Figures 34(A) and (B) is 2θ. The vertical axis represents Intensity.

[0459] <XRD of the positive electrode after charging> Next, we measured each of the fabricated secondary batteries at 4.55V, 4.6V, 4.65V, and 4.7V. CCCV charging was performed by selecting one condition from V for each. Specifically, at 25°C, each voltage was increased to 0 After constant current charging at 0.2C, constant voltage charging was performed until the current value became 0.02C. The value was set to 1C = 191mA / g. The rechargeable battery was then placed in an argon atmosphere under a globe. The positive electrode is removed from the box and cleaned with DMC (dimethyl carbonate) before electrolysis. The liquid was removed. The sample was then sealed in a sealed container under an argon atmosphere, and XRD analysis was performed.

[0460] Figures 35(A) and (B) show the details for Sample 35, respectively. The XRD corresponding to the charging voltage conditions is shown. The horizontal axis of the graphs shown in Figures 35(A) and (B) The vertical axis is 2θ, and the vertical axis is Intensity.

[0461] Figure 35(A) shows the peak observed when 2θ is in the range of 18° to 20°. Charging voltage The peak observed under the 4.55V condition is thought to be due to the O3 type crystal structure. As the voltage increases, the peak position shifts to the higher angle side. In this case, in addition to the peak near 18.9°, a peak was also observed near 19.2°. In a two-phase mixed state having two crystal structures: an O3-type crystal structure and a pseudo-spinel-type crystal structure. This suggests that the 19.3° interval observed under the condition of a charging voltage of 4.7V is The peak is thought to be due to a pseudo-spinel crystal structure.

[0462] Figure 35(B) shows the peak observed when 2θ is in the range of 40° to 50°. Charging voltage As the voltage is increased, at 4.7V, a peak suggesting an H1-3 type crystal structure appears near 43.9°. The signal becomes weakly observable.

[0463] Based on the above, in the positive electrode active material according to one embodiment of the present invention, as the charging voltage is increased, 4.6 At 5V, it is thought that a region occurs where the crystal structure changes from an O3 type to a pseudo-spinel type. Furthermore, even when the voltage is increased to 4.7V, although H1-3 type crystal structures are present, it is mainly pseudo-S It is thought to have a Pinel-type crystal structure, and the positive electrode active material according to one aspect of the present invention has a high charging voltage This also suggested high stability.

[0464] <Continuous charging endurance> Next, we evaluated the continuous charging endurance of the secondary battery. First, Sample 3 Secondary batteries using 0 to Sample 35 as the positive electrode active material, Charging is done via CCCV (0.05C, 4.5V or 4.6V, cutoff current 0.005C), discharging is done via CCCV. The measurement was performed over two cycles at 25°C with CC (0.05C, 2.5V).

[0465] Subsequently, charging was performed at 60°C using CCCV (0.05C). The upper voltage limit was 4.55V. Alternatively, the voltage can be set to 4.65V, and the termination condition is when the secondary battery voltage is 0.01V less than the upper limit voltage. The time it took for the voltage to drop below (4.54V if it was 4.55V) was measured. If the voltage falls below the upper limit voltage, it may indicate a problem such as a short circuit. 1C was defined as 200mA / g.

[0466] Table 3 shows the time measured for each secondary battery. Note that each condition is for secondary Two batteries were prepared. Table 3 shows the average of the two results.

[0467] [Table 3]

[0468] Also, Sample 30, Sample 32, Sample Regarding the results using e(sample) 34 and Sample(sample) 35, Figure 36(A) shows the time-current characteristics when the charging voltage is 4.55V, and when the charging voltage is 4.65V. The time-current characteristics for V are shown in Figure 36(B).

[0469] By adding aluminum, the time until voltage drop occurs is extended, allowing for continuous charging. It was suggested that the resistance of the nickel was improved. Also, compared to when nickel alone is added, By adding aluminum, a significant improvement in resistance to continuous charging was observed. Ta.

[0470] <Cycle Characteristics> Next, Sample 30, Sample 32, Samp Regarding secondary batteries using le (sample) 34 and Sample (sample) 35 The cycle characteristics were evaluated. First, charging was performed using CCCV (0.05C, 4.6V, termination voltage). Current (0.005C), discharge as CC (0.05C, 2.5V) at 25°C for 2 cycles The voltage was measured. Subsequently, charging was performed at 25°C using CCCV (0.2C, 4.6V, termination current). The battery was repeatedly charged and discharged at CC (0.2C, 2.5V) and the cycle characteristics were determined. Sex was evaluated.

[0471] The cycle characteristics are shown in Figure 37. In Figure 37, the horizontal axis represents the cycle cycle and the vertical axis represents the discharge capacity. Also, Figure 38(A) shows Sample 32, and Figure 38(B) shows Sample Sample 34, Figure 38(C) shows the initial loading of Sample 35. The discharge curve is shown. An improvement in initial capacity was observed with the addition of nickel. (Sample(S) (Simple) 34). In addition, by adding nickel and aluminum, the cycle This suggests that the reduction in volume is suppressed, especially under conditions where nickel and aluminum are added. Better results were obtained in (Sample 35). [Examples]

[0472] In this embodiment, the positive electrode was evaluated by measuring its DC resistance.

[0473] <Manufacturing of secondary batteries> A positive electrode was fabricated using Sample 11 shown in Example 1 as the positive electrode active material. The cathode active material consisted of carbon black and PVDF. Active material: carbon black: PVDF A slurry mixed in a ratio of DF=90:5:5 (by weight) was applied to the current collector. NMP was used as the solvent for the rally.

[0474] After coating the current collector with slurry, the solvent was evaporated. Then, pressurization was applied at 210 kN / m. After that, further pressurization was applied at 1467 kN / m. Through the above process, the positive electrode was obtained. The load on the electrode is approximately 20 mg / cm³. 2 That's what I decided.

[0475] Using the fabricated positive electrode, a CR2032 type (20mm diameter, 3.2mm height) coin was used. A rechargeable battery of type [type] was manufactured.

[0476] Lithium metal was used for the counter electrode.

[0477] The electrolyte in the electrolyte solution contains 1 mol / L lithium hexafluoride phosphate (LiPF6). The electrolyte used is ethylene carbonate (EC) and diethyl carbonate (DEC). A mixture with an EC:DEC ratio of 3:7 (by volume) was used. The cycle characteristics were evaluated. For the secondary batteries that underwent this procedure, 2 wt% vinylene carbonate (VC) was added to the electrolyte. Ta.

[0478] A 25 μm thick polypropylene was used for the separator.

[0479] The positive electrode and negative electrode cans were made of stainless steel (SUS).

[0480] <Charge-discharge cycle test> DC resistance was measured before the charge / discharge cycle test and again after 50 charge / discharge cycles. Measurements were taken after the procedure. The charge-discharge cycle test followed the conditions shown in Example 1.

[0481] <DC resistance measurement> Next, DC resistance measurements were performed using the fabricated secondary battery. The measurement device was an electrochemical measurement system. The TEM used was the HJ1001SM8A model from Hokuto Denko Co., Ltd.

[0482] First, the battery was charged to 4.5V at 25°C using CCCV, and then left to rest for 20 minutes. Next After CC discharge to 3.0V, a 20-minute pause was performed. The discharge capacity obtained from the measurement was... As a baseline, DC resistance measurements were performed under varying SOC conditions as follows.

[0483] First, the battery was charged to 4.5V using CCCV at 25°C. Next, it was discharged, S DC resistance measurements were taken in each of the three states where OC was 70%, 20%, and 10%. went.

[0484] In each state of charge (SOC), after the discharge capacity reaches a predetermined SOC, current is flowed for a certain period of time. The DC resistance was then calculated. The obtained DC resistances are shown in Table 4.

[0485]

Table 4

[0486] The smaller the SOC, the greater the tendency for the DC resistance to increase. Also, after performing a cycle test, the DC resistance was found to increase by about 1.3 to 1.4 times.

Example

[0487] In this example, cross-sectional TEM-EDX analysis of the particles of the positive electrode active material of one aspect of the present invention was performed.

[0488] After thinning each sample with a FIB (Focused Ion Beam System: focused ion beam processing observation device), a TEM image was observed. FIG. 39(A) shows the cross-sectional TEM image of Sample 35 prepared in Example 2.

[0489] <TEM-EDX Analysis> In FIG. 39(A), TEM-EDX analysis was performed on the portion surrounded by the broken line. The analysis was performed linearly from the surface to the inside of the particle. The line was made approximately perpendicular to the surface. FIG. 39(B) shows the results of line analysis by EDX. In the vicinity of the surface, relatively, the concentration of aluminum was high and the concentration of cobalt was low. Also, an increase in the concentration of magnesium was suggested near the surface. From this, in the particles of the positive electrode active material, it is possible that aluminum, magnesium, etc. contribute to the stabilization of the structure on the particle surface.

Example

[0490] ​In this embodiment, a secondary battery having a positive electrode using a positive electrode active material according to one aspect of the present invention is fabricated. The XRD of the positive electrode of a rechargeable battery after charging was evaluated.

[0491] Sample 30 and Sample prepared in Example 2 Using 35, a positive electrode was fabricated, and a secondary battery was then fabricated using each of these positive electrodes. The positive electrode and the secondary battery were fabricated using the fabrication methods shown in Example 2.

[0492] <XRD of the positive electrode after charging> Next, select either 4.6V or 4.65V for each of the rechargeable batteries you have prepared and set it to C CCV charging was performed. Specifically, at 45°C, constant current charging at 0.2C was performed until each voltage was reached, The battery was charged at a constant voltage until the current reached 0.02C. Here, 1C is defined as 191mA / g. Then, the recharged secondary battery was disassembled in a glove box under an argon atmosphere, and the positive electrode was removed. It was removed and washed with DMC (dimethyl carbonate) to remove the electrolyte. Then Al The samples were sealed in a GON atmosphere and subjected to XRD analysis.

[0493] Figures 40(A) and (B) show the XRD results. At high charging voltages, Sample (Sample) In sample 30, in addition to a peak suggesting an H1-3 type crystal structure, there is also a peak near 20.9°. And a prominent peak is observed near 36.8°. Near 20.9° and near 36.8° The adjacent peak is suggested to be due to CoO2, raising concerns that lithium has been desorbed and the crystal structure has collapsed. It is thought to be in a stable state. In contrast, Sample 35 is pseudo The Pinel structure was suggested, indicating stability even at high charging voltages. [Explanation of symbols]

[0494] 100: Positive electrode active material, 100A: Positive electrode active material, 100A_1: Positive electrode active material, 100A_2 : Positive electrode active material, 100A_3: Positive electrode active material, 100C: Positive electrode active material, 200: Active material layer, 201: Graphene compound, 211a: Positive electrode, 211b: Negative electrode, 212a: Lead, 21 2b: Lead, 214: Separator, 215a: Joint, 215b: Joint, 217: Fixing Fixed component, 250: secondary battery, 251: outer casing, 261: folding part, 262: sealing part, 263: Seal part, 271: Ridge line, 272: Valley line, 273: Space, 300: Secondary battery, 3 01: Positive electrode can, 302: Negative electrode can, 303: Gasket, 304: Positive electrode, 305: Positive electrode current collector body, 306: positive electrode active material layer, 307: negative electrode, 308: negative electrode current collector, 309: negative electrode active material layer 310: Separator, 500: Secondary battery, 501: Positive electrode current collector, 502: Positive electrode active material layer , 503: positive electrode, 504: negative electrode current collector, 505: negative electrode active material layer, 506: negative electrode, 507: Separator, 508: Electrolyte, 509: Outer casing, 510: Positive lead electrode, 511: Negative electrode Lead electrode, 600: secondary battery, 601: positive electrode cap, 602: battery casing, 603: positive electrode Terminals, 604: Positive, 605: Separator, 606: Negative, 607: Negative terminal, 608: Insulating plate, 609: Insulating plate, 611: PTC element, 612: Safety valve mechanism, 613: Conductive plate, 614: Conductive plate, 615: Module, 616: Conductor, 617: Temperature control device, 900: circuit board, 901: raw material, 902: mixture, 903: mixture, 904: mixture, 910: Labels, 911: Terminals, 912: Circuits, 913: Secondary batteries, 914: Antennas, 916: Layer, 917: Layer, 918: Antenna, 920: Display device, 921: Sensor, 922: Terminal ,930: enclosure, 930a: enclosure, 930b: enclosure, 931: negative electrode, 932: positive electrode, 93 3: Separator, 950: Winding body, 951: Terminal, 952: Terminal, 980: Secondary battery, 9 81: Film, 982: Film, 993: Winding body, 994: Negative electrode, 995: Positive electrode, 9 96: Separator, 997: Lead electrode, 998: Lead electrode, 7100: Portable display device 7101: Housing, 7102: Display unit, 7103: Operation buttons, 7104: Rechargeable battery, 7 200: Portable information terminal, 7201: Housing, 7202: Display unit, 7203: Band, 720 4: Buckle, 7205: Operation button, 7206: Input / Output terminal, 7207: Icon, 7 300: Display device, 7304: Display unit, 7400: Mobile phone, 7401: Housing, 740 2: Display unit, 7403: Operation buttons, 7404: External connection port, 7405: Speaker, 7406: Microphone, 7407: Rechargeable battery, 7500: Electronic cigarette, 7501: Atomizer 7502: Cartridge, 7504: Rechargeable battery, 8000: Display device, 8001: Enclosure 8002: Display unit, 8003: Speaker unit, 8004: Rechargeable battery, 8021: Charging device , 8022: Cable, 8024: Rechargeable battery, 8100: Lighting device, 8101: Enclosure, 8 102: Light source, 8103: Secondary battery, 8104: Ceiling, 8105: Side wall, 8106: Floor, 8107: Window, 8200: Indoor unit, 8201: Enclosure, 8202: Air outlet, 8203: Secondary Battery, 8204: Outdoor unit, 8300: Electric refrigerator / freezer, 8301: Enclosure, 8302: Refrigerator Room door, 8303: Freezer room door, 8304: Secondary battery, 8400: Automobile, 8401: He Headlight, 8406: Electric motor, 8500: Automobile, 8600: Scooter, 860 1: Side mirror, 8602: Rechargeable battery, 8603: Turn signal light, 8604: Under-seat storage , 9600: Tablet device, 9625: Switch, 9627: Switch, 9628: Operating switch, 9629: fastener, 9630: housing, 9630a: housing, 9630b: enclosure Body, 9631:Display, 9631a:Display, 9631b:Display, 9633:Solar cell , 9634: Charge / discharge control circuit, 9635: Energy storage unit, 9636: DC-DC converter, 96 37: Converter, 9640: Movable part

Claims

1. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material comprising cobalt, oxygen, magnesium, nickel, and aluminum. The positive electrode active material, when measured by ICP-MS, has a nickel atom count of 0.05% to 4% of the cobalt atom count, and an aluminum atom count of 0.05% to 4% of the cobalt atom count. Lithium-ion rechargeable battery.

2. The positive electrode active material, when measured by ICP-MS, has a nickel atom count of 0.1% to 2% of the cobalt atom count. The lithium-ion secondary battery according to claim 1.

3. The positive electrode active material has a nickel concentration in its surface layer that is higher than the nickel concentration measured by ICP-MS. A lithium-ion secondary battery according to claim 1 or 2.

4. The aforementioned positive electrode active material has a nickel concentration that is higher when measured by XPS than when measured by ICP-MS. A lithium-ion secondary battery according to any one of claims 1 to 3.

5. The positive electrode active material, when measured by ICP-MS, has an aluminum atom count of 0.1% to 2% of the cobalt atom count. A lithium-ion secondary battery according to any one of claims 1 to 4.

6. The positive electrode active material has a higher aluminum concentration in its surface layer than the aluminum concentration measured by ICP-MS. A lithium-ion secondary battery according to any one of claims 1 to 5.

7. The positive electrode active material has an aluminum concentration that is higher when measured by XPS than when measured by ICP-MS. A lithium-ion secondary battery according to any one of claims 1 to 6.

8. The positive electrode active material, when measured by ICP-MS, has a magnesium atom count of 0.001 times or more and 0.1 times or less than the cobalt atom count. A lithium-ion secondary battery according to any one of claims 1 to 7.

9. The positive electrode active material has a magnesium concentration in its surface layer that is higher than the magnesium concentration measured by ICP-MS. A lithium-ion secondary battery according to any one of claims 1 to 8.

10. The aforementioned positive electrode active material has a magnesium concentration that is higher when measured by XPS than when measured by ICP-MS. A lithium-ion secondary battery according to any one of claims 1 to 9.

11. When the positive electrode active material was thinned using FIB and then subjected to EDX radiation analysis, a nickel concentration distribution was observed even within the material. A lithium-ion secondary battery according to any one of claims 1 to 10.

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