Lithium-ion secondary battery

Abstract

To provide a positive electrode active material particle that deteriorates less, a power storage device with little deterioration, alternatively, a highly safe power storage device.SOLUTION: A positive electrode active material particle includes a first crystal grain, a second crystal grain, and a grain boundary located between the first crystal grain and the second crystal grain, the first crystal grain and the second crystal grain have lithium, a transition metal, and oxygen, the grain boundary has magnesium and oxygen, and the positive electrode active material particle has a region in which the ratio of the atomic concentration of magnesium at the grain boundary to the atomic concentration of the transition metal in the first crystal grain and the second crystal grain is 0.010 or more and 0.50 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to an article, a method, or a manufacturing method. Process, machine, manufacture, or composition of matter One embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, or a semiconductor device. The present invention relates to a method for manufacturing an electronic device. In particular, the present invention relates to a positive electrode active material that can be used in a secondary battery, a secondary The present invention relates to a battery and an electronic device having a secondary battery.

[0002] In this specification, the term "power storage device" refers to elements and devices in general that have a power storage function. For example, lithium-ion secondary batteries and other storage batteries (also called secondary batteries) This includes silicon ion capacitors and electric double layer capacitors.

[0003] In addition, in this specification, the term "electronic device" refers to a device in general that has a power storage device. Electro-optical devices having a power storage device, and information terminal devices having a power storage device are all electronic devices. [Background technology]

[0004] In recent years, various types of energy storage devices such as lithium-ion secondary batteries, lithium-ion capacitors, and air batteries have become available. The development of high-power, high-capacity lithium-ion secondary batteries is particularly Mobile phones, smartphones, laptop computers, and other portable information terminals, portable music players Players, digital cameras, medical equipment, or hybrid vehicles (HEVs), electric vehicles ( Next-generation clean energy vehicles such as EVs and plug-in hybrid vehicles (PHEVs) Demand for rechargeable energy is rapidly increasing along with the development of the semiconductor industry, including automobiles. It has become an indispensable source of information in today's information society.

[0005] Therefore, in order to improve the cycle characteristics and increase the capacity of lithium-ion secondary batteries, Improvements to the active material have been investigated (Patent Documents 1 and 2).

[0006] In addition, the characteristics required for energy storage devices include safety in various operating environments and long-term reliability. Improvements include: [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-018914 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-076454 Summary of the Invention [Problem to be solved by the invention]

[0008] Lithium ion secondary batteries and the positive electrode active materials used therein have various characteristics, such as capacity, cycle characteristics, Improvements are desired in various aspects, such as charge / discharge characteristics, reliability, safety, and cost.

[0009] In view of the above, one object of one embodiment of the present invention is to provide positive electrode active material particles that are less likely to deteriorate. Another object of one embodiment of the present invention is to provide novel positive electrode active material particles. Another object of one embodiment of the present invention is to provide a power storage device that is less susceptible to deterioration. Another object of one embodiment of the present invention is to provide a highly safe power storage device. Another object of one embodiment of the present invention is to provide a novel power storage device.

[0010] The description of these problems does not preclude the existence of other problems. It is not necessary for the embodiments to solve all of these problems. It is possible to extract other problems from the description of the claim. [Means for solving the problem]

[0011] One aspect of the present invention is a method for manufacturing a crystal grain having a first crystal grain, a second crystal grain, and a crystal grain having a first crystal grain and a second crystal grain. and a grain boundary located therebetween, the first grain and the second grain being in contact with lithium and a transition metal. a positive electrode active material containing a metal and oxygen, and a crystal grain boundary containing magnesium and oxygen; It is a particle.

[0012] In the positive electrode active material particles, the atomic concentration of magnesium relative to the atomic concentration of the transition metal It is preferable that the ratio is in the range of 0.010 or more and 0.50 or less.

[0013] In the above-described positive electrode active material particles, the grain boundaries preferably further contain fluorine.

[0014] In the above-mentioned positive electrode active material particles, the ratio of the atomic concentration of fluorine to the atomic concentration of the transition metal is , preferably in the range of 0.020 or more and 1.00 or less.

[0015] The positive electrode active material particles contain transition metals such as iron, cobalt, nickel, manganese, and chromium. It is preferable that the alloy contains at least one of titanium, vanadium and niobium. [Effects of the Invention]

[0016] According to one embodiment of the present invention, it is possible to provide positive electrode active material particles that are less likely to deteriorate. It is possible to provide material particles. It is also possible to provide a power storage device with little deterioration. It is also possible to provide a highly safe It is possible to provide a power storage device. It is also possible to provide a novel power storage device. [Brief explanation of the drawings]

[0017] [Figure 1] 3A to 3C are diagrams illustrating an example of positive electrode active material particles. [Figure 2] FIG. 4 is a diagram illustrating a concentration distribution in a positive electrode active material particle. [Figure 3] 5A to 5C are diagrams illustrating an example of a method for manufacturing positive electrode active material particles. [Figure 4] FIG. 10 is a cross-sectional view of an active material layer in the case where a graphene compound is used as a conductive additive. [Figure 5] FIG. 2 is a diagram illustrating a coin-type secondary battery. [Figure 6] FIG. 2 is a diagram illustrating a cylindrical secondary battery. [Figure 7] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 8] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 9] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 10] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 11] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 12] FIG. 1 is a diagram illustrating a laminated secondary battery. [Figure 13] FIG. 1 is a diagram illustrating a laminated secondary battery. [Figure 14] FIG. 2 is a diagram showing the appearance of a secondary battery. [Figure 15] FIG. 2 is a diagram showing the appearance of a secondary battery. [Figure 16] 1A to 1C illustrate a method for manufacturing a secondary battery. [Figure 17] 1A and 1B are diagrams illustrating a bendable secondary battery. [Figure 18] 1A and 1B are diagrams illustrating a bendable secondary battery. [Figure 19] 1A to 1C illustrate examples of electronic devices. [Figure 20] 1A to 1C illustrate examples of electronic devices. [Figure 21] 1A to 1C illustrate examples of electronic devices. [Figure 22] 1A to 1C illustrate examples of electronic devices. [Figure 23] 1A and 1B are TEM images and schematic diagrams of cross sections of positive electrode active material particles according to an example. [Figure 24] 1 is a STEM image of a cross section of a positive electrode active material particle according to an example. [Figure 25] 1A and 1B are diagrams illustrating an HAADF-STEM image and an EDX point analysis of a positive electrode active material particle according to an example. [Figure 26] FIG. 2 shows EDX spectra and quantitative results of positive electrode active material particles according to an example. [Figure 27] FIG. 2 shows EDX spectra and quantitative results of positive electrode active material particles according to an example. [Figure 28] FIG. 2 shows EDX spectra and quantitative results of positive electrode active material particles according to an example. [Figure 29] FIG. 2 shows EDX spectra and quantitative results of positive electrode active material particles according to an example. [Figure 30] FIG. 2 shows EDX spectra and quantitative results of positive electrode active material particles according to an example. [Figure 31] 1 is a mapping image obtained by EDX area analysis of positive electrode active material particles according to an example. [Figure 32] 1 is a mapping image obtained by EDX area analysis of positive electrode active material particles according to an example. [Figure 33] FIG. 2 is a diagram illustrating EDX line analysis of positive electrode active material particles according to an example. [Figure 34] FIG. 4 is a diagram showing atomic concentrations in EDX line analysis of positive electrode active material particles according to an example. [Figure 35] FIG. 4 is a diagram showing atomic concentrations in EDX line analysis of positive electrode active material particles according to an example. [Figure 36] FIG. 10 is a diagram showing the ratio of the number of atoms in EDX line analysis of the positive electrode active material particles according to the example. [Figure 37] 1 is a mapping image obtained by EDX area analysis of positive electrode active material particles according to an example. [Figure 38] 1 is a mapping image obtained by EDX area analysis of positive electrode active material particles according to an example. [Figure 39]FIG. 4 is a diagram showing atomic concentrations in EDX line analysis of positive electrode active material particles according to an example. [Figure 40] FIG. 4 is a diagram showing atomic concentrations in EDX line analysis of positive electrode active material particles according to an example. [Figure 41] FIG. 10 is a diagram showing the ratio of the number of atoms in EDX line analysis of the positive electrode active material particles according to the example. [Figure 42] 1A and 1B are TEM images and schematic diagrams of cross sections of positive electrode active material particles according to an example. [Figure 43] 1 is a STEM image of a cross section of a positive electrode active material particle according to an example. [Figure 44] 1 is a mapping image obtained by EDX area analysis of positive electrode active material particles according to an example. [Figure 45] 1 is a mapping image obtained by EDX area analysis of positive electrode active material particles according to an example. [Figure 46] FIG. 2 is a diagram illustrating EDX line analysis of positive electrode active material particles according to an example. [Figure 47] FIG. 4 is a diagram showing atomic concentrations in EDX line analysis of positive electrode active material particles according to an example. [Figure 48] FIG. 4 is a diagram showing atomic concentrations in EDX line analysis of positive electrode active material particles according to an example. [Figure 49] FIG. 10 is a diagram showing the ratio of the number of atoms in EDX line analysis of the positive electrode active material particles according to the example. [Figure 50] 1 is a mapping image obtained by EDX area analysis of positive electrode active material particles according to an example. [Figure 51] 1 is a mapping image obtained by EDX area analysis of positive electrode active material particles according to an example. [Figure 52] FIG. 4 is a diagram showing atomic concentrations in EDX line analysis of positive electrode active material particles according to an example. [Figure 53] FIG. 4 is a diagram showing atomic concentrations in EDX line analysis of positive electrode active material particles according to an example. [Figure 54] FIG. 10 is a diagram showing the ratio of the number of atoms in EDX line analysis of the positive electrode active material particles according to the example. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and various modifications in form and details are possible by those skilled in the art. Furthermore, the present invention should not be construed as being limited to the description of the following embodiments. It is not something that can be done.

[0019] In each drawing described in this specification, the positive electrode, negative electrode, active material layer, separator, outer casing, etc. The size and thickness of each component may be exaggerated for clarity of description. Therefore, each component is not necessarily limited by its size, and the correlation between each component is not necessarily limited by its size. It is not limited to a relative size.

[0020] In addition, in the configuration of the present invention described in this specification, etc., the same parts or parts having similar functions The same reference numerals are used for the components in different drawings, and the repeated explanations will be omitted. When referring to parts with similar functions, the hatch pattern is the same and no special reference numeral is attached. There may not be.

[0021] In addition, crystal planes and directions are indicated by superscript bars in crystallography. The crystal planes and directions in the above are indicated by a bar instead of a number due to limitations in the application notation. , and are expressed by adding a - (minus sign) before the number. Also, individual orientations that indicate directions within the crystal is [ ], collective orientation indicating all equivalent directions is < >, individual faces indicating crystal faces are ( ) and the sets of surfaces with equivalent symmetry are represented by {}.

[0022] In this specification, segregation refers to the phenomenon in a solid containing multiple elements (e.g., A, B, C). This refers to the phenomenon in which the concentration of a certain element (e.g., B) is unevenly distributed.

[0023] (Embodiment 1) [Positive electrode active material structure] A positive electrode active material particle 100 according to one embodiment of the present invention is shown in FIGS. 1(A) to 1(C) and 2. This will be explained using Figures 2(A) to 2(C).

[0024] 1(A) shows the appearance of a positive electrode active material particle 100. The positive electrode active material particle 100 is an amorphous particle. The shape of the positive electrode active material particle 100 shown in FIG. 1(A) is an example. Not limited to.

[0025] The positive electrode active material particle 100 has a plurality of crystal grains 101 and a plurality of crystal grain boundaries 103. (B) shows the crystal grains 101 and the crystal grain boundaries 103 of the positive electrode active material particles 100. In (B), the grain boundary 103 is shown by a broken line. The boundaries between the crystal grains 101 and the crystal grain boundaries 102 shown in FIG. The shape and number of 03 are just an example and are not limited to this.

[0026] The crystal grains 101 are particles with a substantially uniform crystal orientation within the crystal grains. Each grain has a different crystal orientation, and there is a grain boundary 103 between adjacent grains. That is, the positive electrode active material particle 100 has a plurality of crystal grains 101 sandwiching a crystal grain boundary 103. The positive electrode active material particles 100 can also be said to be polycrystalline. It may have a depression 105 or an amorphous region. Crystal defects are bulk defects, plane defects, point defects, or defects where other elements have entered the crystal, which can be observed in a TEM image. It refers to a structure in which crystal grains are embedded. Crystal grains are sometimes called crystallites.

[0027] The crystal grains 101 and the crystal grain boundaries 103 in the positive electrode active material particles 100 were confirmed by X-ray diffraction (XR D: X-ray Diffraction), neutron diffraction, electron diffraction (ED: Ele ctron diffraction), transmission electron microscope (TEM) Scanning Electron Microscope (STE) image M:Scanning Transmission Electron Microsc Fast Fourier transform (FFT) of lattice images obtained from opy, TEM, or STEM images FT (Fast Fourier Transformation) analysis, high-angle scattering High-Angle Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) Circular Dark Field Scanning TEM image, Circular Bright Field Scanning Transmission Electron Annular Bright-Field Scanning Electron Microscope (ABF-STEM) ng TEM image, Raman spectroscopy, electron backscattering Electron Backscatter Diffraction (EBSD) Electron backscatter diffraction (EBSP) is a method for measuring the scattering of electrons. on Backscatter Diffraction Pattern) For example, if the density (brightness) of a TEM image is approximately uniform, it is considered to be a crystalline The orientation is almost constant, meaning that it can be determined to be a single crystal. The density (brightness) of the TEM image differs depending on the grain size, so the area where the density (brightness) changes is determined to be the grain boundary. However, it is not always possible to determine the grain boundaries 101 and 102 by various analyses. It is not necessary to observe a clear boundary of 03.

[0028] The crystal grains 101 and the crystal grain boundaries 103 have different compositions. The grain boundaries 103 contain magnesium and oxygen. The grain boundary 103 preferably further contains fluorine.

[0029] The crystal grains 101 and the crystal grain boundaries 103 were analyzed by energy dispersive X-ray analysis (EDX). Dispersive X-ray Spectroscopy, Time-of-Flight Secondary Imaging Time-of-Flight Secondary Ion Spectroscopy (ToF-SIMS) ion mass spectrometry), X-ray photoelectron spectroscopy (XPS:X-ra y Photoelectron Spectroscopy), Auger Electron Spectroscopy (A ES: Auger Electron Spectroscopy, electron energy loss Electron Energy-Loss Spectrosc (EELS) However, it is not necessarily the case that various analytical methods are used to confirm that the composition is different. Therefore, it is not necessary to observe clear boundaries between the crystal grains 101 and the crystal grain boundaries 103. However, depending on the analytical method, the desired target element may not be detected. Even when the concentration of the target element is extremely low, the target element may not be detected. be.

[0030] <Grain boundary> The grain boundaries 103 of the positive electrode active material particles 100 according to one embodiment of the present invention are formed by magnesium and The grain boundaries 103 contain magnesium oxide and oxygen. It is preferable that magnesium oxide further contains fluorine. Part of the oxygen in magnesium oxide is substituted with fluorine. By partially substituting magnesium oxide with fluorine, for example, The diffusibility of lithium can be increased, and charging and discharging are not hindered. This may make it less soluble in hydrofluoric acid.

[0031] Compared to the grains 101, the grain boundaries 103 have regions with a higher magnesium concentration. It can be said that the grain boundary 103 has a region where magnesium is segregated.

[0032] Compared to the grains 101, the grain boundaries 103 have regions with a higher fluorine concentration. It can be said that 03 has a region where fluorine is segregated.

[0033] The magnesium concentration distribution between the dashed dotted lines A1 and A2 of the positive electrode active material particle 100 shown in FIG. An example of the fabric is shown in Figure 2(B), and an example of the fluorine concentration distribution is shown in Figure 2(C). In (C), the horizontal axis represents the distance between the dashed lines A1 and A2 in FIG. 2(A), and the vertical axis represents the distance between the dashed lines A1 and A2 in FIG. Magnesium concentration (Mg Concentration) and fluorine concentration (F Concentration).

[0034] Compared to the grain 101, the grain boundary 103 and the vicinity of the grain boundary 103 are rich in magnesium and The crystal defects 105 also have a region where the concentration of fluorine is high. In some cases, there are regions with a high concentration of fluorine. Although an example in which the grain boundaries 103 and the crystal defects 105 have the same concentration is shown, this is not limited to this. In addition, the shape of the magnesium and fluorine concentration distribution is similar to that shown in Figure 2(B) and Figure 2(C). It is not limited to the shape shown.

[0035] Here, the number of transition metal atoms in the crystal grain 101 is represented as Tr-Metal. The number of transition metal atoms (Tr-Metal) in 1 is the number of atoms of each transition metal in the crystal grain 101. Refers to the total number of children.

[0036] The positive electrode active material particle 100 has a grain boundary 101 with respect to the number of transition metal atoms in the grain 101. The ratio of the number of magnesium atoms in 03 (Mg / Tr-Metal) is 0.010 or more It is preferable that the positive electrode active material particles 100 have a range of 0.50 or less. It is preferable that / Tr-Metal is in the range of 0.020 or more and 0.30 or less. In the positive electrode active material particles 100, the Mg / Tr-Metal is 0.030 or more and 0.20 or less. By using the above-mentioned Mg / Tr-Metal, the positive electrode active material In other words, deterioration of the power storage device can be suppressed. The device may be a device.

[0037] In this specification and the like, the transition metal refers to an element belonging to Groups 3 to 12 of the periodic table. The above group numbers are based on the International Union of Pure and Applied Chemistry (IUPAC). Union of Pure and Applied Chemistry Based on the periodic table classified into groups 1 to 18 in the revised edition of the Chemical Nomenclature (1989) Made.

[0038] Generally, as the power storage device is repeatedly charged and discharged, the positive electrode active material particles contained in the power storage device lose their charge. Transition metals such as barium and manganese dissolve into the electrolyte, oxygen is released, and the crystal structure becomes unstable. This may cause side reactions such as the deterioration of the positive electrode active material particles. Deterioration of the capacitor may lead to further deterioration such as a decrease in the capacity of the power storage device. In the detailed description, the transition metal of the positive electrode active material particles is dissolved into the electrolyte, oxygen is released, and crystallization occurs. Positive electrode active material particles undergo chemical and structural changes, such as their structure becoming unstable. In this specification and the like, a decrease in the capacity of the power storage device is sometimes referred to as deterioration of the power storage device. This is sometimes called equipment degradation.

[0039] Metals eluted from the positive electrode active material particles are reduced and precipitated at the negative electrode, interfering with the electrode reaction at the negative electrode. Metal deposition on the negative electrode can lead to deterioration such as a decrease in capacity.

[0040] The insertion and desorption of lithium during charging and discharging causes the crystal lattice of the positive electrode active material particles to expand and contract. The volume change and distortion of the crystal lattice may occur. This can cause the positive electrode active material particles to crack, which can lead to deterioration such as a decrease in capacity. Cracks in active material particles may originate from grain boundaries.

[0041] If the temperature inside the energy storage device rises and oxygen is released from the positive electrode active material particles, the safety of the energy storage device will be compromised. In addition, the crystal structure of the positive electrode active material particles may be damaged by the desorption of oxygen. This may cause deterioration such as a decrease in capacity. Oxygen may also be released from the positive electrode active material particles due to the release of oxygen.

[0042] On the other hand, magnesium oxide is a chemically and structurally stable material. In the above-mentioned electric storage device, the magnesium oxide contained in the positive electrode active material particles does not itself It is hardly involved in the reaction. In other words, magnesium oxide makes it difficult for lithium to be inserted or extracted. Therefore, magnesium oxide itself is chemically and structurally stable even after being charged and discharged.

[0043] The positive electrode active material particle 100 according to one embodiment of the present invention has magnesium oxide at the grain boundary 103. This stabilizes the positive electrode active material particles 100 chemically and structurally, and prevents structural changes due to charging and discharging. In other words, the crystal structure of the positive electrode active material particles 100 is more stable. This prevents the crystal structure from changing even after repeated charge and discharge. This can prevent the particles 100 from cracking. In other words, this is preferable because it can prevent deterioration such as a decrease in capacity. When the charge voltage is high and the amount of lithium present in the positive electrode becomes smaller during charging, the crystal structure The crystal structure of the positive electrode active material particle 100 according to one embodiment of the present invention becomes unstable and prone to deterioration. The structure is more stable, and therefore deterioration such as a decrease in capacity can be suppressed, which is particularly preferable.

[0044] The positive electrode active material particles 100 according to one embodiment of the present invention have a stable crystal structure, and therefore, This can prevent transition metals from leaching out of the material particles, which means that deterioration such as capacity loss can be suppressed. Yes, it is preferable.

[0045] Furthermore, when the positive electrode active material particle 100 according to one embodiment of the present invention is cracked along the grain boundary, the crack The surface of the positive electrode active material particles after cracking has magnesium oxide. In terms of the quality, side reactions can be suppressed, and deterioration of the positive electrode active material can be reduced. This can suppress the degradation.

[0046] The positive electrode active material particle 100 according to one embodiment of the present invention has magnesium oxide at the grain boundary 103. This prevents oxygen contained in the positive electrode active material particles 100 from diffusing through the grain boundaries. It is possible to suppress the release of oxygen from the positive electrode active material particles 100. This makes it possible to provide a highly safe power storage device.

[0047] Furthermore, when the crystal defects 105 contain magnesium oxide, the crystal structure of the positive electrode active material particles 100 is stabilized and is preferred.

[0048] The positive electrode active material particle 100 has a grain boundary 101 with respect to the number of transition metal atoms in the grain 101. The ratio of the number of fluorine atoms in 03 (F / Tr-Metal) is 0.020 or more and 1.00 It is preferable that the positive electrode active material particles 100 have the following regions: F / Tr-M It is preferable that the etal is in the range of 0.040 or more and 0.60 or less. The active material particles 100 have an F / Tr-Metal range of 0.060 or more and 0.40 or less. By using the above-mentioned F / Tr-Metal, the grain boundaries and their vicinity are Magnesium can be segregated efficiently, which means that deterioration of the positive electrode active material can be reduced. Deterioration of the device can be suppressed, and a highly safe power storage device can be provided.

[0049] <Crystal grains> The crystal grains 101 of the positive electrode active material particles 100 according to one embodiment of the present invention are composed of lithium, transition metals, and the like. For example, the crystal grain 101 is a complex oxide containing lithium, a transition metal, and oxygen. In addition, transition metals such as iron, cobalt, nickel, manganese, chromium, and titanium are also present. One or more of tungsten, vanadium, niobium, and the like can be used.

[0050] The crystal grains 101 have, for example, a layered rock salt type crystal structure or a spinel type crystal structure. The crystal grains 101 may be made of, for example, a polyanion. A polyanion-based positive electrode material can be used. For example, olivine can be used as a polyanion-based positive electrode material. The crystal grains 101 and 102 are also examples of the material having a crystalline structure of the crystalline grains 101 and 102. For example, a cathode material containing sulfur can be used.

[0051] Various composite oxides can be used as the crystal grains 101. For example, LiFeO2, LiCoO2, LiNiO2, LiMn2O4, Li2MnO3, V2O5, Cr2O5 Compounds such as MnO2 can be used.

[0052] As a material with a layered rock salt type crystal structure, for example, a composite oxide represented by LiMO2 is used. The element M is preferably at least one selected from Co and Ni. LiCoO2 has a large capacity, is stable in air, and is relatively thermally stable. In addition, the element M is preferably selected from Co and Ni. In addition to one or more of these, it may contain one or more selected from Al and Mn.

[0053] For example, LiNi x Mn y Co z O w (x, y, z and w are respectively, for example, x=y=z = 1 / 3 or its vicinity, w = 2 or its vicinity) can be used. , LiNi x Mn y Co z O w (x, y, z and w are respectively, for example, x=0.8 or its vicinity, y=0.1 or its vicinity, z=0.1 or its vicinity, w=2 or its vicinity For example, LiNi x Mn y Co z O w (x, y, z and w are, for example, x=0.5 or its vicinity, y=0.3 or its vicinity, and z=0 .2 or its vicinity, w=2 or its vicinity) can be used. iNi x Mn y Co z O w (x, y, z and w are respectively, for example, x=0.6 or (nearby, y=0.2 or nearby, z=0.2 or nearby, w=2 or nearby) For example, LiNi x Mn y Co z O w (x, y, z and For example, w is x=0.4 or its vicinity, y=0.4 or its vicinity, and z=0.2. or thereabouts, w=2 or thereabouts) can be used.

[0054] The neighborhood is, for example, a value that is greater than 0.9 times and less than 1.1 times the value.

[0055] Some of the transition metals and lithium contained in the crystal grains 101 are replaced with Fe, Co, Ni, Cr, Al, and Mg or a material in which the crystal grains 101 are substituted with one or more elements selected from Fe, Co, Ni, C The crystal grains 101 are made of a material doped with one or more elements selected from the group consisting of r, Al, Mg, etc. It may also be used.

[0056] As an example of a material with a spinel-type crystal structure, a composite oxide represented by LiM2O4 is It is preferable to have Mn as the element M. For example, LiMnO 4 can be used. In addition, by having Ni in addition to Mn as the element M, This is preferable because it may improve the discharge voltage of the secondary battery and improve the energy density. A small amount of lithium-containing material with a spinel-type crystal structure containing manganese, such as iMn2O4, Amount of lithium nickel oxide (LiNiO2 or LiNi 1-x M x O2 (M=Co, Al, etc.) ) is preferably mixed, since it is possible to improve the characteristics of the secondary battery.

[0057] For example, the average particle size of the primary particles of the positive electrode active material is 1 nm or more and 100 μm or less. It is preferable that the thickness is 50 nm or more and 50 μm or less, and more preferable that the thickness is 1 μm or more and 30 μm or less. It is more preferable that the specific surface area is less than 1m. 2 / g or more 20m 2 / g or less The average particle size of the secondary particles is preferably 5 μm or more and 50 μm or less. The average particle size is measured by scanning electron microscope (SEM). Observation using a TEM (Tron Microscope) or laser diffraction / scattering method The specific surface area can be measured by a particle size distribution analyzer or the like. It can be measured.

[0058] A conductive material such as a carbon layer may be provided on the surface of the positive electrode active material. For example, a carbon layer on the positive electrode active material can improve the conductivity of the electrode. The coating is formed by mixing carbohydrates such as glucose when baking the positive electrode active material. In addition, graphene, multi-graphene, and graphene oxide ( GO: Graphene Oxide) or RGO (Reduced Graphene Here, RGO can be, for example, graphene oxide (GO). ) is a compound obtained by reduction.

[0059] A layer containing one or more of an oxide and a fluoride may be provided on the surface of the positive electrode active material. The oxide may have a composition different from that of the crystal grains 101. In addition, the oxide may have the same composition as that of the crystal grains 101. It may have.

[0060] For example, a polyanion-based positive electrode material containing oxygen, element X, metal A, and metal M may be used. The metal M can be Fe, Mn, Co, Ni, Ti, V, or N. b, the metal A is one or more of Li, Na, and Mg, and the element X is S, P, Mo, It is one or more of W, As, and Si.

[0061] Examples of materials having an olivine-type crystal structure include composite materials (general formula LiMPO4 (where M is , Fe(II), Mn(II), Co(II), Ni(II) Representative examples of the general formula LiMPO4 include LiFePO4, LiNiPO4, and Li iCoPO4, LiMnPO4, LiFe a Ni b PO4, LiFe a Co b PO4, L iFe a Mn b PO4, LiNi a Co b PO4, LiNi a Mn b PO4(a+b is 1 Below, 0 <a<1、0<b<1)、LiFe c Ni d Co e PO4, LiFe c Nid M n e PO4, LiNi c Co d Mn e PO4 (where c + d + e is less than or equal to 1, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g Co h Mn i PO4 (where f + g + h + i is less than or equal to 1, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), etc. Lithium compounds can be used for this purpose.

[0062] In particular, LiFePO4 satisfies the requirements for a cathode active material, such as safety, stability, high capacity density, and the presence of lithium ions that can be extracted during initial oxidation (charging), in a well-balanced manner. Therefore it is preferable.

[0063] The cathode active material having an olivine-type crystal structure preferably has an average particle diameter of primary particles of 1 nm or more and 20 μm or less, more preferably 10 nm or more and 5 μm or less and even more preferably 50 nm or more and 2 μm or less. The specific surface area is preferably 1 m 2 / g or more and 20 m 2 / g or less. The average particle diameter of secondary particles is preferably 5 μm or more and 5 0 μm or less.

[0064] In addition, composite materials such as the general formula Li (2-j) MSiO4 (M is one or more of Fe(II), Mn(II), Co(I I), Ni(II), 0 ≤ j ≤ 2), etc. can be used. The general formula Li (2-j) MSiO4 representative examples include Li (2-j) FeSiO4, Li (2- j) NiSiO4, Li (2-j) ​CoSiO4, Li (2-j) MnSiO4, Li ( 2-j) Fe k Ni l SiO4, Li (2-j) Fe k Co l SiO4, Li (2-j) Fe k Mn l SiO4, Li (2-j) Ni k Co l SiO4, Li (2-j) Ni k M n l SiO4 (k + l is 1 or less, 0 < k < 1, 0 < l < 1), Li (2-j) Fe m Ni n Co q SiO4, Li (2-j) Fe m Ni n Mn q SiO4, Li (2-j) Ni m Co n Mn q SiO4 (m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1), Li (2-j) Fe r Ni s Co t Mn u SiO4 (r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. are available.

[0065] Also, A<000009%]]M2(XO4)3 (A = Li, Na, Mg, M = Fe, Mn, Ti, V, Nb , X = S, P, Mo, W, As, Si) can be used with a NASICON-type compound represented by the general formula. Examples of the NASICON-type compound include Fe2(MnO4)3, Fe2(SO4)3, Li3Fe2(PO4)3, etc. Also, as the crystal grains 101, Li2MPO4F, L The compounds represented by the general formula i2MP2O7 and Li5MO4 (M = Fe, Mn) are used. This can be done.

[0066] The crystal grains 101 may be made of perovskite fluorides such as NaFeF3 and FeF3, or T Metal chalcogenides (sulfides, selenides, tellurides) such as iS2 and MoS2, LiM Oxides with an inverse spinel crystal structure such as VO4, vanadium oxides (V2O5, V6 O 13 Materials such as manganese oxides and organic sulfur compounds can be used. Cut.

[0067] The crystal grains 101 are formed of a material having a general formula LiMBO3 (where M is Fe(II), Mn(II), Borate-based positive electrode materials represented by one or more of Co(II) can be used.

[0068] Furthermore, for example, a solid solution of a combination of multiple composite oxides may be used as the crystal grains 101. It is possible. a O2 and Li2M b O3 solid solution (M a , M b are each independently a transition metal (One or more selected from the group consisting of) are sometimes called lithium excess oxides. For example, LiNi x Mn y Co z Crystallize a solid solution of O2 (x, y, z>0, x+y+z=1) and Li2MnO3 It can be used as the grains 101.

[0069] Also, as the crystal grain 101, the composition formula Li a Mn b M c O d Lithium ma The element M can be any element other than lithium or manganese. It is preferable to use a metal element selected from the group consisting of silicon and phosphorus, and nickel is preferred. Furthermore, when measuring the entire particle of the lithium manganese composite oxide, When powered on, 0 <a / (b+c)<2、かつc>0 and 0.26≦(b+c) / d<0.5 In order to realize high capacity, it is preferable to have a crystal structure between the surface layer and the center. The lithium manganese composite oxide has regions with different crystal orientations or oxygen contents. In order to obtain such a lithium manganese composite oxide, it is preferable that, for example, 1.6≦ It is preferable that a≦1.848, 0.19≦c / b≦0.935, and 2.5≦d≦3. Furthermore, Li 1.68 Mn 0.8062 Ni 0.318 The formula is O3 It is particularly preferable to use lithium manganese composite oxide. 1. 68 Mn 0.8062 Ni 0.318 Lithium manganese composite with the formula O3 The oxide is the ratio (molar ratio) of the amount of raw materials, Li2CO3:MnCO3:NiO=0 Lithium manganese composite oxide formed by 0.84:0.8062:0.318 Therefore, the lithium manganese composite oxide has the composition formula Li 1.68 Mn 0.80 62 Ni 0.318 It is expressed as O3, but the composition may deviate from this.

[0070] The composition of metals, silicon, phosphorus, etc. of the entire lithium manganese composite oxide particle is, for example, For example, it can be measured using an ICP-MS (inductively coupled plasma mass spectrometer). ​The oxygen composition of the entire particle of the lithium manganese composite oxide can be measured by, for example, EDX (energy dispersive X-ray diffraction). It can also be measured using ICP-MS analysis in combination with fusion analysis. This can be determined by using degassing analysis and valence evaluation using XAFS (X-ray absorption fine structure) analysis. The lithium manganese composite oxide is a material containing at least lithium and manganese. It refers to oxides of chromium, cobalt, aluminum, nickel, iron, magnesium, molybdenum, etc. Butane, zinc, indium, gallium, copper, titanium, niobium, silicon, and phosphorus, etc. It may contain at least one element selected from the group consisting of:

[0071] In addition, sodium, potassium, and strontium are used as carrier ions instead of lithium. For example, sodium-containing layered oxide may be used. It is possible.

[0072] Examples of materials containing sodium include NaFeO2 and Na 2 / 3 [Fe 1 / 2 Mn1 / 2 ]O2, Na 2 / 3 [Ni 1 / 3 Mn 2 / 3 ]O2, Na2Fe2(SO4)3, N a3V2(PO4)3, Na2FePO4F, NaVPO4F, NaMPO4 (M is F One or more of e(II), Mn(II), Co(II), Ni(II), Na2FePO4 F, sodium-containing oxides such as Na4Co3(PO4)2P2O7 are used as the positive electrode active material. It can be used as such.

[0073] In addition, lithium-containing metal sulfides can be used as the positive electrode active material. 2TiS3, Li3NbS4, etc.

[0074] Up to now, the positive electrode active material particles 100 have been described as having crystal grains 101 and crystal grain boundaries 103. However, one embodiment of the present invention is not limited thereto. The particle of material 100 may have a region 107. The region 107 may be, for example, a grain 101. The region 107 can be provided so as to be in contact with at least a part of the graphene compound. or a decomposition product of lithium or the electrolyte. When the region 107 is a coating containing carbon, the positive electrode active material particles This can increase the conductivity between the positive electrode active material particles 100 and between the positive electrode active material particles 100 and the current collector. If the region 107 is a film containing lithium or a decomposition product of the electrolyte, the electrolyte and This can suppress excessive reaction and improve the cycle characteristics when used in a secondary battery.

[0075] If the particle diameter of the positive electrode active material particles 100 is too large, it becomes difficult for lithium to diffuse. If it is too thick, the bulk density of the electrode will decrease, and the reaction with the electrolyte will proceed excessively. Therefore, the particle size is preferably 1 μm or more and 100 μm or less, and more preferably 10 μm or more and 70 μm or less. Here, the particle size is, for example, the cumulative 50% on a volume basis. This refers to the value (D50).

[0076] [Method for producing positive electrode active material] A method for producing a positive electrode active material particle 100 having crystal grains 101 and crystal grain boundaries 103 is shown in FIG. The crystal grains 101 are made of a composite oxide containing lithium, a transition metal (M), and oxygen. The grain boundary 103 contains magnesium, fluorine, and oxygen.

[0077] First, starting materials are prepared (step S11). Specifically, a lithium source, a transition metal (M The ammonium nitrate source, magnesium source, and fluorine source are each weighed out.

[0078] Examples of lithium sources include lithium carbonate, lithium fluoride, lithium hydroxide, and lithium oxide. A hum or the like can be used.

[0079] As a source of transition metals (M), for example, cobalt compounds, nickel compounds, manganese compounds, iron compounds, vanadium compounds, titanium compounds, molybdenum compounds, zinc compounds, indium Compounds, gallium compounds, copper compounds, niobium compounds, and the like can be used in combination.

[0080] Examples of cobalt compounds include cobalt oxide, cobalt hydroxide, and cobalt oxyhydroxide. One or more of cobalt carbonate, cobalt oxalate, cobalt sulfate, and the like can be used.

[0081] Examples of nickel compounds include nickel oxide, nickel hydroxide, nickel carbonate, and nickel chloride. Nickel, nickel bromide, nickel iodide, nickel sulfate, nickel nitrate, nickel formate, etc. One or more may be used.

[0082] Examples of manganese compounds include manganese oxide, manganese hydroxide, manganese carbonate, and manganese chloride. One or more of manganese, manganese iodide, manganese sulfate, and manganese nitrate may be used.

[0083] Examples of iron compounds include iron fluoride, iron chloride, iron bromide, iron iodide, iron sulfate, iron phosphate, and One or more of iron phosphate, iron acetate, etc. can be used.

[0084] Examples of vanadium compounds include vanadium oxide, vanadium hydroxide, vanadium chloride, One or more vanadium sulfates may be used.

[0085] Examples of titanium compounds include titanium fluoride, titanium chloride, titanium bromide, titanium iodide, and titanium oxide. One or more of titanium dioxide, titanium sulfide, titanium sulfate, etc. can be used.

[0086] Examples of molybdenum compounds include molybdenum oxide, diammonium molybdate, and phosphorus molybdenum. One or more of the above may be used, such as isopropyl alcohol.

[0087] Zinc compounds include, for example, zinc oxide, zinc hydroxide, zinc nitrate, zinc sulfate, zinc chloride, and zinc carbonate. One or more of these can be used, such as zinc.

[0088] Examples of indium compounds include indium chloride, indium sulfate, indium nitrate, and indium acid. Indium oxide, indium hydroxide, and the like can be used.

[0089] As the gallium compound, for example, one or more of gallium chloride, gallium fluoride, etc. may be used. can.

[0090] As the copper compound, for example, one or more of copper sulfate, copper chloride, copper nitrate, etc. can be used.

[0091] Examples of niobium compounds include niobium oxide, niobium chloride, niobium oxide sulfate, and niobium fluoride. One or more of the following can be used.

[0092] Examples of magnesium sources include magnesium oxide, magnesium fluoride, and magnesium hydroxide. One or more of sodium carbonate, magnesium carbonate, etc. can be used.

[0093] As the fluorine source, for example, one or more of lithium fluoride, magnesium fluoride, etc. may be used. In other words, lithium fluoride can be used as both a lithium source and a fluorine source. Magnesium fluoride can be used as both a magnesium source and a fluorine source. can.

[0094] Furthermore, when the crystal grain 101 contains a metal other than the transition metal in addition to the transition metal (M), Weigh out the source of metals other than transition metals. When aluminum is used as the metal other than transition metals, For example, an aluminum compound can be used as the metal source. Aluminum oxide, aluminum hydroxide, aluminum carbonate, aluminum chloride, One or more of aluminum iodide, aluminum sulfate, aluminum nitrate, etc. can be used. Cut.

[0095] The ratio of the number of atoms of the raw transition metal (M) to that of magnesium is explained. The ratio m of the number of atoms of magnesium, Mg(r), to the number of atoms, M(r), is 0.0050. or less than 0.050, that is, the number of transition metal atoms M(r): the number of magnesium atoms Mg(r )=1.0:m, it is preferable that m is 0.0050≦m≦0.050. Furthermore, transition metals The ratio m of the number of magnesium atoms to the number of atoms of By setting the ratio of the number of atoms as described above, it is possible to form a magnetic field at the grain boundary 103. It is possible to efficiently produce a positive electrode active material containing sodium. In this case, the total number of atoms of multiple transition metals is used for the number of atoms of the transition metal, M(r). You can also calculate it using this.

[0096] The neighborhood is, for example, a value that is greater than 0.9 times and less than 1.1 times the value.

[0097] The ratio of the number of magnesium atoms to the number of fluorine atoms in the raw material is explained below. The ratio n of the number of fluorine atoms F(r) to the number Mg(r) is 1.50 or more and 4.0 or less. The number of magnesium atoms Mg(r): the number of fluorine atoms F(r) = 1.0: n, 1 It is preferable that n is 0.50≦n≦4.0. Furthermore, the ratio of the number of fluorine atoms to the number of magnesium atoms is 0.50≦n≦4.0. The ratio of the numbers, n, is 2.0 or close to 2.0, that is, the number of magnesium atoms, Mg(r): the number of fluorine atoms. It is more preferable that the number of atoms F(r) is 1.0:2.0 or close to that. By setting the ratio to 103, it is possible to efficiently segregate magnesium and fluorine at the grain boundary 103. can.

[0098] The atomic ratio of the raw material transition metal, magnesium, and fluorine can be expressed by the following formula 1. Here, m is the ratio of the number of magnesium atoms Mg(r) to the number of transition metal atoms M(r). As mentioned above, 0.0050≦m≦0.050 is preferable, and m=0.0 Preferably, n is the number of fluorine atoms relative to the number of magnesium atoms, Mg(r). As mentioned above, 1.50≦n≦4.0 is preferable, and more preferably, For this, n=2.0 or its vicinity is preferred.

[0099]

number

[0100] An example of the ratio of raw materials when LiCoO2 is produced as the positive electrode active material particles is shown below. The ratio m of the number of magnesium atoms to the number of cobalt atoms is 0.010. The ratio n of the number of fluorine atoms to the number of carbon atoms is set to 2.0. The ratio of the number of atoms of Co, Mg, and fluorine was Co:Mg:F=1.0:0.010 :0.020.

[0101] The atomic ratio of the raw materials and the composition of the positive electrode active material particles 100 obtained by synthesis are the same. This may not be possible.

[0102] The molar ratio of the raw material lithium compound and transition metal (M) compound is determined based on the assumed crystal grain size. In addition, for example, the molar ratio of the lithium compound of the raw material is On the other hand, if the lithium content of the resulting crystal grains is low, the molar ratio of the lithium compound in the raw material may be increased.

[0103] Next, the weighed starting materials are mixed (step S12). A zees mill or the like can be used.

[0104] Next, the material mixed in step S12 is subjected to a first heating (step S13). Heating is preferably carried out at a temperature of 800°C or higher and 1050°C or lower, and more preferably at a temperature of 900°C or higher and 1000°C or lower. The heating time is preferably 2 hours or more and 20 hours or less. The first heating is preferably carried out in an oxygen-containing atmosphere, for example, in a dry air atmosphere. It is preferable to do this with

[0105] The first heating in step S13 removes lithium and transition metal (M) contained in the crystal grains 101. Furthermore, by this first heating, the compound oxides contained in the starting materials can be synthesized. The magnesium and fluorine are partially embedded in the surface layer of a complex oxide containing lithium and a transition metal (M). However, at this point, other parts of magnesium and fluorine are in transition with lithium. It is in a state of being solid-dissolved in a complex oxide containing a metal (M).

[0106] Next, the material heated in step S13 is cooled to room temperature (step S14). By subjecting the synthesized material to a crushing process, the particle diameter of the positive electrode active material particles 100 can be reduced. This is preferable.

[0107] Next, the material cooled in step S14 is subjected to a second heating (step S15). It is preferable to hold the heating at the specified temperature for 100 hours or less, and 1 hour or more and 70 hours It is more preferable to carry out the treatment for 10 minutes or less, and more preferably for 2 hours or more and 50 hours or less, It is more preferable to carry out the treatment for 2 hours or more and 35 hours or less. 00°C or less is preferable, 700°C or more and 1000°C or less is more preferable, and about 800°C or less is even more preferable. It is more preferable that the second heating is carried out in an atmosphere containing oxygen. For example, It is preferable to carry out the treatment in an air atmosphere.

[0108] By performing the second heating in step S15, magnesium and fluorine contained in the starting material are , it can promote segregation to the grain boundaries.

[0109] Finally, the material heated in S15 is cooled to room temperature and collected (step S16) to activate the positive electrode. A substance particle 100 can be obtained.

[0110] As mentioned above, by mixing the magnesium source and the fluorine source as starting materials, the grain boundaries A positive electrode active material having magnesium oxide in 103 can be efficiently produced.

[0111] In addition, by mixing a magnesium source and a fluorine source as starting materials, grain boundaries 10 3. Magnesium may be more likely to segregate.

[0112] The oxygen bonded to magnesium is replaced by fluorine, and the surroundings of the replaced fluorine This may make magnesium more mobile.

[0113] Furthermore, adding magnesium fluoride to magnesium oxide may lower the melting point. The lowering of the melting point makes it easier for atoms to move during heat treatment.

[0114] Also, fluorine has a higher electronegativity than oxygen. Therefore, Even in stable compounds, the addition of fluorine causes a charge imbalance, resulting in the formation of magnesium This may weaken the bond between oxygen and the

[0115] For these reasons, by mixing a magnesium source and a fluorine source as starting materials, , magnesium becomes more mobile, and magnesium becomes more likely to segregate at the grain boundaries 103. There are cases where this happens.

[0116] By using the positive electrode active material particles 100 described in this embodiment, deterioration is reduced and safety is improved. This embodiment mode may be appropriately combined with any of the other embodiments. It can be used.

[0117] (Embodiment 2) In this embodiment, a secondary battery having the positive electrode active material particles 100 described in the previous embodiment is Examples of materials that can be used will be described. In this embodiment, the positive electrode, the negative electrode, and the The following description will be given taking as an example a secondary battery in which the solution is enclosed in an exterior body.

[0118] [Positive electrode] The positive electrode has a positive electrode active material layer and a positive electrode current collector.

[0119] <Cathode active material layer> The positive electrode active material layer contains positive electrode active material particles. The positive electrode active material layer also contains a conductive additive and a biomaterial. The sensor may have a fin.

[0120] The positive electrode active material particles are the positive electrode active material particles 100 described in the previous embodiment. By using the positive electrode active material particles 100 described in the previous embodiment, deterioration is reduced. Therefore, a highly safe secondary battery can be obtained.

[0121] As the conductive additive, a carbon material, a metal material, a conductive ceramic material, or the like can be used. A fibrous material may also be used as the conductive additive. The content of the electrical auxiliary agent is preferably 1 wt% or more and 10 wt% or less, and more preferably 1 wt% or more and 5 wt% or less. is more preferred.

[0122] The conductive additive can form an electrically conductive network in the electrode. This allows the positive electrode active material particles to maintain an electrical conduction path between each other. By adding an electrical auxiliary agent, it is possible to realize an active material layer with high electrical conductivity. .

[0123] Examples of the conductive additive include natural graphite, artificial graphite such as mesocarbon microbeads, and carbon fiber. Examples of carbon fibers that can be used include mesophase pitch carbon fibers. Carbon fibers such as isotropic pitch-based carbon fibers can be used. Carbon nanofibers and carbon nanotubes can be used. The tube can be produced by, for example, vapor phase growth method. For example, carbon black (acetylene black (AB) etc.), graphite particles Carbon materials such as graphene and fullerene can be used. Metal powders and fibers such as nickel, aluminum, silver, and gold, as well as conductive ceramic materials, etc. It can be used.

[0124] A graphene compound may also be used as the conductive additive.

[0125] Graphene compounds have excellent electrical properties, such as high conductivity, as well as high flexibility and high In addition, graphene may have excellent physical properties such as high mechanical strength. The graphene compound has a planar shape, which allows for surface contact with low contact resistance. In addition, even if they are thin, they can have very high conductivity, and even a small amount can be used to efficiently conduct electricity within the active material layer. Therefore, the graphene compound can be used as a conductive additive. This is preferable because it is possible to increase the contact area between the active material and the conductive additive. This is preferable because it may be possible to reduce the electrical resistance. For example, graphene, multi-graphene, or reduced graphene O It is particularly preferred to use RGO oxide. This refers to a compound obtained by reducing graphene (GO: Graphene Oxide).

[0126] When using active material particles with a small particle size, for example, active material particles with a particle size of 1 μm or less, The specific surface area of ​​the active material particles is large, and therefore more conductive paths are required to connect the active material particles together. The amount of conductive additive increases, and the amount of active material carried may decrease relatively. If the amount of the conductive additive decreases, the capacity of the secondary battery will decrease. When graphene compounds are used, they can efficiently form conductive paths even in small amounts. This is particularly preferable because it is possible to avoid reducing the amount of the active material carried.

[0127] As an example, in the case where a graphene compound is used as a conductive additive in the active material layer 200, An example of the cross-sectional structure will be described.

[0128] 4(A) shows a vertical cross-sectional view of the active material layer 200. The active material layer 200 is made of granular positive electrode active material. Particles 100, a graphene compound 201 as a conductive additive, a binder (not shown), Here, the graphene compound 201 includes, for example, graphene or multigraphene. Here, the graphene compound 201 preferably has a sheet shape. Preferably, the graphene compound 201 is a multi-graphene or (and) A plurality of graphenes may be partially overlapped to form a sheet.

[0129] In the vertical cross section of the active material layer 200, as shown in FIG. 4(A), In FIG. 4(A), the sheet-like graphene compound 201 is dispersed almost uniformly. The graphene compound 201 is shown schematically in bold, but in reality it is a single layer or multiple layers of carbon molecules. The graphene compounds 201 are thin films having a thickness of 1000 nm. The positive electrode active material particles 100 are wrapped or covered with the positive electrode active material particles 100. Since they are formed to adhere to the surface, they are in surface contact with each other.

[0130] Here, a plurality of graphene compounds are bonded to each other to form a mesh-like graphene compound. It is possible to form a graphene sheet (hereinafter referred to as a graphene compound net or graphene net). When the active material is covered with a graphene net, the graphene net can connect the active material to each other. It can also function as a binder to bind the particles together. Since it is possible to reduce the ratio of active material to the electrode volume or weight, or it is not necessary to use In other words, the capacity of the power storage device can be increased.

[0131] Here, graphene oxide is used as the graphene compound 201, and is mixed with an active material to form an active material. After forming the layer that will become the layer 200, it is preferable to reduce it. By using graphene oxide, which has extremely high dispersibility in polar solvents, The mixture 201 can be dispersed approximately uniformly inside the active material layer 200. The solvent is evaporated from the dispersion medium containing the dispersed graphene oxide, and the graphene oxide is reduced. Therefore, the graphene compound 201 remaining in the active material layer 200 partially overlaps with each other. By dispersing the particles so that they are in surface contact with each other, a three-dimensional conductive path can be formed. The reduction of graphene oxide may be performed by, for example, heat treatment or by using a reducing agent. It is also possible.

[0132] Therefore, unlike granular conductive additives such as acetylene black, which come into point contact with the active material, graphite Since the compound 201 enables surface contact with low contact resistance, it is more effective than ordinary conductive additives. The amount of the granular positive electrode active material particles 100 and the graphene compound 201 is reduced, and the electrical conductivity between the particles is improved. Therefore, the ratio of the positive electrode active material particles 100 in the active material layer 200 can be increased. This allows the discharge capacity of the power storage device to be increased.

[0133] Examples of binders include styrene-butadiene rubber (SBR) and styrene-isoprene. Acrylonitrile-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene-propylene It is preferable to use a rubber material such as a propylene-diene copolymer. Fluorine rubber can be used.

[0134] As the binder, it is preferable to use, for example, a water-soluble polymer. As the molecule, for example, polysaccharides can be used. cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose Cellulose derivatives such as cellulose, diacetyl cellulose, and regenerated cellulose, as well as starch These water-soluble polymers can be used in combination with the rubber materials described above. It is even better if there is one.

[0135] Alternatively, the binder may be polystyrene, polymethyl acrylate, or polymethyl methacrylate. Polymethylmethacrylate (PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), poly Ethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, Polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, poly Ethylene terephthalate, nylon, polyvinylidene fluoride (PVDF), polyacrylo Nitrile (PAN), Ethylene Propylene Diene Polymer, Polyvinyl Acetate, Nitrocel It is preferable to use a material such as loin.

[0136] The binder may be used in combination with two or more of the above.

[0137] For example, a material having a particularly excellent viscosity adjusting effect may be used in combination with other materials. For example, rubber materials have excellent adhesive strength and elasticity, but it is difficult to adjust the viscosity when mixed with a solvent. In such cases, for example, mixing with a material that has a particularly excellent viscosity adjusting effect can As a material having a particularly excellent viscosity adjusting effect, for example, a water-soluble polymer is preferably used. Furthermore, examples of water-soluble polymers that are particularly effective in adjusting viscosity include the aforementioned polysaccharides, such as carbohydrates. Carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxy Cellulose derivatives such as propyl cellulose, diacetyl cellulose, and regenerated cellulose Carbohydrates and starches can be used.

[0138] The cellulose derivatives such as carboxymethyl cellulose are, for example, By converting cellulose into salts such as sodium salts or ammonium salts, the solubility increases, It is easier to exert its effect as a viscosity adjuster. The increased solubility makes it easier to make electrode slurry. When preparing a substrate, 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 binders for electrodes include These salts are also included.

[0139] Water-soluble polymers stabilize viscosity by dissolving in water, and also act as active materials and binders. Other materials to be combined, such as styrene butadiene rubber, are stably dispersed in aqueous solution. In addition, since it has functional groups, it can be easily and stably adsorbed onto the surface of the active material. It is expected that cellulose derivatives such as carboxymethyl cellulose will For example, many materials have functional groups such as hydroxyl groups and carboxyl groups. It is expected that the polymers will interact with each other and widely cover the surface of the active material.

[0140] When the binder that covers or contacts the surface of the active material forms a film, it is called a passive film. It is expected that the passive film will also play a role in suppressing the decomposition of the electrolyte. It is a film with no electrical conductivity or extremely low electrical conductivity, and is When a dynamic membrane is formed, it is possible to suppress the decomposition of the electrolyte at the battery reaction potential. In addition, the passive film suppresses electrical conductivity while allowing lithium ions to conduct. And even more desirable.

[0141] <Positive electrode current collector> The positive electrode current collector may be made of metals such as stainless steel, gold, platinum, aluminum, titanium, or the like. Highly conductive materials such as alloys of these can be used. It is preferable that silicon, titanium, neodymium, scavenger, etc. are not eluted at the potential of the positive electrode. Aluminum alloys containing elements such as indium and molybdenum that improve heat resistance are used. It can also be formed from a metal element that reacts with silicon to form silicide. Metal elements that react with silicon to form silicide include zirconium, titanium, and Tantalum, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten , cobalt, nickel, etc. Current collectors are available in foil, plate (sheet), mesh, and punched shapes. The current collector may be in the form of a metal, an expanded metal, or the like. It is recommended to use a thickness of 5 μm or more and 30 μm or less.

[0142] [Negative electrode] The negative electrode has a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer contains a conductive additive and and a binder.

[0143] <Negative electrode active material> As the negative electrode active material, for example, an alloy-based material or a carbon-based material can be used.

[0144] As a negative electrode active material, it is possible to carry out charge-discharge reactions by alloying and dealloying reactions with lithium. Any suitable element can be used, such as silicon, tin, gallium, aluminum, Rumanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. Materials containing at least one of these elements can be used. These elements have a large capacity compared to carbon. Silicon has a particularly high theoretical capacity of 4200mAh / g. It is preferable to use silicon. Alternatively, compounds containing these elements may be used. For example, SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V 2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3 Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, I nSb, SbSn, etc. Here, the charge / discharge reaction occurs due to alloying and dealloying reactions with lithium. Elements capable of undergoing a reaction and compounds containing such elements are sometimes called alloy materials. do.

[0145] In this specification, SiO refers to, for example, silicon monoxide. Alternatively, SiO refers to SiO xHere, x preferably has a value of 1 or close to 1. For example, x is preferably 0.2 or more and 1.5 or less, and more preferably 0.3 or more and 1.2 or less.

[0146] Carbon materials include graphite, easily graphitizable carbon (soft carbon), and non-graphitizable carbon (hard carbon). carbon nanotubes, graphene, carbon black, etc. may be used. .

[0147] Examples of graphite include artificial graphite and natural graphite. Examples include carbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite. Here, as the artificial graphite, spherical graphite having a spherical shape can be used. For example, the MCMB may have a spherical shape, which is preferable. It is relatively easy to reduce the particle size, which is sometimes preferable. Examples include flake graphite and spherical natural graphite.

[0148] When lithium ions are inserted into graphite (when lithium-graphite intercalation compounds are formed), It exhibits a low potential similar to that of lithium metal (0.05V to 0.3V vs. Li / L i + This allows the lithium-ion secondary battery to exhibit a high operating voltage. In addition, graphite has a relatively high capacity per unit volume, a relatively small volume expansion, and is inexpensive. It is preferable because it has advantages such as higher safety compared to lithium metal.

[0149] In addition, titanium dioxide (TiO2) and lithium titanium oxide (Li4T i5O 12 ), lithium-graphite intercalation compound (Li xC6), niobium pentoxide (Nb2O5) Oxides such as tungsten oxide (WO2) and molybdenum oxide (MoO2) can be used. can.

[0150] In addition, the negative electrode active material is a composite nitride of lithium and transition metals, which has a Li3N structure. Li 3-x M x N (M=Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3 ) And preferable.

[0151] When a composite nitride of lithium and a transition metal is used, the negative electrode active material contains lithium ions, The positive electrode active material is a combination of materials such as V2O5 and Cr3O8 that do not contain lithium ions. It is preferable that a material containing lithium ions is used as the positive electrode active material. By first removing the lithium ions contained in the positive electrode active material, A complex nitride of lithium and a transition metal can be used.

[0152] In addition, a material that undergoes a conversion reaction can also be used as the negative electrode active material. , cobalt oxide (CoO), nickel oxide (NiO), iron oxide (FeO), etc. A transition metal oxide that does not form an alloy with the metal may be used as the negative electrode active material. Further materials that can be produced include Fe2O3, CuO, Cu2O, RuO2, Cr2O3, etc. oxide, CoS 0.89 , NiS, CuS and other sulfides, Zn3N2, Cu3N, Ge3 Nitrides such as N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3, etc. Fluoride is one example.

[0153] The conductive additive and binder that can be contained in the negative electrode active material layer are the same as those that can be contained in the positive electrode active material layer. The same materials as the conductive additive and binder can be used.

[0154] <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.

[0155] [Electrolyte] The electrolytic solution contains a solvent and an electrolyte. The solvent for the electrolytic solution is preferably an aprotic organic solvent. Preferably, for example, ethylene carbonate (EC), propylene carbonate (PC), Ethylene carbonate, chloroethylene carbonate, vinylene carbonate, gamma-butyro Lactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfone oxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran One of tetrahydrofuran, sulfolane, sultone, etc., or two or more of these can be used in combinations and ratios of:

[0156] Also, a phosphate ester compound having fluorine, which is flame-retardant as a solvent for the electrolyte, or By using a fluorine-containing carbonate ester compound, it is possible to prevent explosions and fires in the storage device. Examples of fluorine-containing phosphate ester compounds include tris(2,2, 2-trifluoroethyl) phosphate (TFEP). Examples of ester compounds include bis(2,2,2-trifluoroethyl) carbonate. (TFEC), etc.

[0157] In addition, by using a polymer material that gels as a solvent for the electrolyte, it is possible to prevent leakage, etc. Safety is improved. In addition, it is possible to make the secondary battery thinner and lighter. Representative examples of such materials include silicone gel, acrylic gel, acrylonitrile gel, and poly Ethylene oxide gel, polypropylene oxide gel, fluorine polymer gel etc.

[0158] In addition, a flame-retardant and non-volatile ionic liquid (room-temperature molten salt) is used as the solvent for the electrolyte. By using one or more, the internal temperature of the storage device can be prevented from rising due to an internal short circuit or overcharging. Even if the battery is damaged, it can prevent the battery from exploding or catching fire. The electrolyte solution is made of tetravalent cations and anions. ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations Aliphatic onium cations such as imidazolium cations and pyridinium cations The following aromatic cations are also used as anions in electrolytes: monovalent amide-based Anions, monovalent methide anions, fluorosulfonate anions, perfluoroalkanes perfluoroalkyl borate anion, tetrafluoroborate anion, perfluoroalkyl bo ... phosphate anion, hexafluorophosphate anion, or perfluoroalkyl phosphate hydrate anions, etc.

[0159] The electrolyte to be dissolved in the solvent is, for example, LiPF6, LiClO4, 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 )2, LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, etc. One or more of these titanium salts may be used in any combination and ratio. This can be done.

[0160] The electrolyte used in the electricity storage device is free from granular waste and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as " It is preferable to use a highly purified electrolyte solution with a low content of impurities. Specifically, the weight ratio of impurities to the electrolyte is 1% or less, preferably 0.1% or less, more preferably 1% or less. It is preferably 0.01% or less.

[0161] In addition, the electrolyte contains vinylene carbonate, propane sultone (PS), and tert-butyl Benzene (TBB), Fluoroethylene carbonate (FEC), Lithium bis(oxa) Lithium borate (LiBOB), as well as dinitriles such as succinonitrile and adiponitrile compounds, triisopropoxyboroxine (TiPBx), sulfolane, hydrofluoric acid Hydroxymethyl ether (HFE), vinyl acetate (VA), etc. may be added. Concentration of added material For example, the amount may be 0.1% by weight or more and 5% by weight or less relative to the total solvent. stomach.

[0162] Alternatively, a polymer gel electrolyte may be used in which a polymer is swollen with an electrolytic solution.

[0163] The use of polymer gel electrolyte increases safety against leakage etc. The pond can be made thinner and lighter.

[0164] Gelled polymers include silicone gel, acrylic gel, and acrylonitrile gel. , polyethylene oxide gel, polypropylene oxide gel, fluorine-based polymer As the polymer, for example, polyethylene oxide (PE Polymers with polyalkylene oxide structure such as PVDF and polyacrylic acid Polyisocyanurite and copolymers containing them can be used, for example, PVDF. PVDF-HFP, a copolymer of hexafluoropropylene (HFP), is used. The polymer formed may also have a porous shape.

[0165] In addition, instead of the electrolytic solution, a solid electrolyte containing an inorganic material such as a sulfide or oxide, It is possible to use a solid electrolyte containing a polyethylene oxide (PEO) polymer material. When a solid electrolyte is used, there is no need to install a separator or spacer. Since the entire battery can be solidified, there is no risk of leakage, dramatically improving safety.

[0166] [Separator] The secondary battery preferably has a separator. The separator may be made of, for example, paper. Cellulose-containing fibers, nonwoven fabrics, glass fibers, ceramics, or nanofibers, including Ilon (polyamide), Vinylon (polyvinyl alcohol fiber), polyester, acrylic Use synthetic fibers such as styrene, polyolefin, and polyurethane. The separator is made into a bag shape and placed so that it encases either the positive or negative electrode. It is preferable to do so.

[0167] The separator may have a multi-layer structure. For example, the separator may be made of an organic material such as polypropylene or polyethylene. The material film is made of ceramic material, fluorine material, polyamide material, or a mixture of these. As a ceramic material, for example, aluminum oxide can be used. Examples of the fluorine-based material include fluorine particles, silicon oxide particles, etc. PVDF, polytetrafluoroethylene, etc. can be used. For example, nylon, aramid (meta-aramid, para-aramid), etc. can be used. can.

[0168] Coating with ceramic materials improves oxidation resistance, making it suitable for separators during high-voltage charging and discharging. This can suppress the deterioration of the battery and improve the reliability of the secondary battery. By coating, the separator and electrodes can be more easily attached to each other, improving output characteristics. Coating polyamide materials, especially aramid, improves heat resistance, which contributes to the safety of secondary batteries. Safety can be improved.

[0169] For example, a polypropylene film is coated on both sides with a mixture of aluminum oxide and aramid. Alternatively, aluminum oxide may be applied to the surface of the polypropylene film that comes into contact with the positive electrode. Alternatively, the surface of the negative electrode that comes into contact with the carbon black may be coated with a mixed material of carbon black and aramid, and then coated with a fluorine-based material.

[0170] By using a multilayer separator, the safety of the secondary battery can be maintained even if the overall thickness of the separator is thin. Since the temperature can be maintained, the capacity per volume of the secondary battery can be increased.

[0171] (Embodiment 3) In this embodiment, a secondary battery having the positive electrode active material particles 100 described in the previous embodiment is An example of the shape will be described. The material used for the secondary battery described in this embodiment is the same as that used in the previous embodiment. The description of the form can be taken into consideration.

[0172] [Coin-type secondary battery] First, an example of a coin-type secondary battery will be described. Figure 5(A) shows a coin-type (single-layer flat type) 5(A) and 5(B) are external views of the secondary battery, and FIG. 5(B) is a cross-sectional view thereof.

[0173] The coin-type secondary battery 300 has a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal. 302 is insulated and sealed by a gasket 303 made of polypropylene or the like. The positive electrode 304 is composed of a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with the positive electrode current collector 305. The negative electrode 307 is formed by a negative electrode current collector 308 and a The negative electrode active material layer 309 is formed by bonding the negative electrode active material layer 309 to the negative electrode active material layer 309 .

[0174] The positive electrode 304 and the negative electrode 307 used in the coin-type secondary battery 300 are each an active material. The barrier layer need only be formed on one side.

[0175] The positive electrode can 301 and the negative electrode can 302 are made of nickel and aluminum, which are corrosion-resistant to the electrolyte. , titanium, or alloys thereof or alloys of these with other metals (e.g. stainless steel) In addition, nickel or aluminum can be used to prevent corrosion by the electrolyte. The positive electrode can 301 is preferably coated with a positive electrode 304, and the negative electrode can 302 is preferably coated with a negative electrode 304. 7 and electrically connect to each other.

[0176] The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated with an electrolyte, and the resultant structure shown in FIG. As shown in FIG. 1, the positive electrode can 301 is placed downward, and the positive electrode 304, separator 310, negative electrode 307, and negative electrode 308 are connected to the positive electrode can 301. The positive electrode can 301 and the negative electrode can 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are connected with a gasket 303 interposed therebetween. Then, the laminate is pressed to form a coin-type secondary battery 300.

[0177] By using the positive electrode active material particles 100 described in the previous embodiment for the positive electrode 304, deterioration is reduced. Therefore, the coin-type secondary battery 300 can be made small and highly safe.

[0178] [Cylindrical secondary battery] An example of a cylindrical secondary battery will be described with reference to FIGS. 6(A) to 6(D). The secondary battery 600 is a cylindrical secondary battery 600 shown in FIG. 6(A) and a cross-sectional view of the secondary battery 600 shown in FIG. 6(B). As shown in the figure, a positive electrode cap (battery lid) 601 is provided on the top surface, and a battery can is provided on the sides and bottom. The positive electrode cap and the battery can (external can) 602 are It is insulated by a gasket (insulating packing) 610.

[0179] Inside a hollow cylindrical battery can 602, a strip-shaped positive electrode 604 and a negative electrode 606 are placed between a separator 6 The battery element is wound around the sensor. The battery can 602 is closed at one end and open at the other. The battery can 602 is made of a material that is resistant to corrosion by the electrolyte, such as nickel, aluminum, or titanium. These metals, or their alloys or alloys of these with other metals (e.g., stainless steel, etc.) are used. In addition, to prevent corrosion by the electrolyte, the electrode is coated with nickel or aluminum. It is preferable to cover the inside of the battery can 602 with the positive electrode, the negative electrode, and the separator. The rotated battery element is sandwiched between a pair of opposing insulating plates 608 and 609. The battery can 602 in which the battery element is provided is filled with a non-aqueous electrolyte (not shown). The non-aqueous electrolyte may be the same as that used in coin-type secondary batteries.

[0180] The positive and negative electrodes used in cylindrical secondary batteries are wound, so active material is formed on both sides of the current collector. A positive electrode terminal (positive electrode current collecting lead) 603 is connected to the positive electrode 604, and a negative A negative electrode terminal (negative electrode current collecting lead) 607 is connected to the positive electrode 603. The positive electrode terminal 607 can be made of a metal material such as aluminum. 603 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 is a PTC (Positive Temperature Coefficient) element. The positive electrode cap 601 is electrically connected to the positive electrode cap 601 via a positive electrode coefficient 611. The safety valve mechanism 612 releases the positive electrode cap 601 when the internal pressure of the battery exceeds a predetermined threshold. The PTC element 611 cuts off the electrical connection between the positive electrode 604 and the positive electrode 604. It is a thermal resistor whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current. It prevents abnormal heat generation. The PTC element is made of barium titanate (BaTiO3) Semiconductor ceramics and the like can be used.

[0181] 6C, a plurality of secondary batteries 600 are mounted on the conductive plate 613 and the conductive plate 614. A module 615 may be formed by sandwiching the secondary batteries 600 between them. They may be connected in series, or may be connected in parallel and then in series. By configuring a module 615 having a plurality of secondary batteries 600, It is possible to extract a large amount of power.

[0182] 6(D) is a top view of the module 615. The conductive plate 613 is dotted for clarity. As shown in FIG. 6(D), the module 615 is a module that electrically connects a plurality of secondary batteries 600. The conductive plate 613 may be placed on the conductive wire 616. In addition, even if a temperature control device 617 is provided between the plurality of secondary batteries 600, When the secondary battery 600 is overheated, the temperature control device 617 cools it down. If 600 is too cold, it can be heated by the temperature control device 617. This makes the performance of the module 615 less susceptible to the outside temperature.

[0183] By using the positive electrode active material particles 100 described in the previous embodiment for the positive electrode 604, deterioration is reduced. Therefore, the cylindrical secondary battery 600 can be made small and highly safe.

[0184] [Structure example of power storage device] Another structural example of the power storage device will be described with reference to FIGS.

[0185] 7(A) and 7(B) are diagrams showing the appearance of the power storage device. 900 and a secondary battery 913. A label 910 is attached to the secondary battery 913. Furthermore, as shown in FIG. 7B, the power storage device has a terminal 951, a terminal 952, and an The antenna 914 and the antenna 915 are included.

[0186] The circuit board 900 has a terminal 911 and a circuit 912. The terminal 911 is connected to a terminal 951. , terminal 952, antenna 914, antenna 915, and circuit 912. A plurality of terminals 911 are provided, and each of the plurality of terminals 911 is used as a control signal input terminal, a power supply terminal, etc. may also be used.

[0187] The circuit 912 may be provided on the back surface of the circuit board 900. The antenna 915 is not limited to a coil shape, but may be, for example, a wire shape or a plate shape. Planar antenna, aperture antenna, traveling wave antenna, EH antenna, magnetic field antenna, dielectric Alternatively, antenna 914 or antenna 915 may be used. The flat conductor may function as one of the conductors for electric field coupling. In other words, the capacitor has two conductors, one of which is an annulus. The antenna 914 or the antenna 915 may be activated. Instead, power can be exchanged using an electric field.

[0188] The line width of antenna 914 is preferably larger than the line width of antenna 915. This allows the amount of power received by the antenna 914 to be increased.

[0189] The power storage device has a layer 916 between the antenna 914 and the secondary battery 913 and an antenna 915. The layer 916 has a function of shielding an electromagnetic field generated by the secondary battery 913, for example. For example, a magnetic material can be used as 16 .

[0190] The structure of the electricity storage device is not limited to that shown in FIG.

[0191] For example, as shown in Figs. 8(A-1) and 8(A-2), In the secondary battery 913 shown in FIG. 8(A-1) is an external view of one side of the pair of surfaces, and FIG. 8(A-2) is an external view of the pair of surfaces. 7(A) and 7(B). For this, the description of the power storage device in FIGS. 7A and 7B can be used as appropriate.

[0192] As shown in FIG. 8(A-1), a layer 916 is sandwiched between one of the two surfaces of a secondary battery 913. 8(A-2), a retainer 914 is provided, and the other of the pair of surfaces of the secondary battery 913 is The antenna 915 is provided on the second electrode 913 with a layer 917 sandwiched therebetween. The layer 917 has a function of shielding the electromagnetic field generated by the magnetic field. Cut.

[0193] By adopting the above structure, the size of both the antenna 914 and the antenna 915 can be increased. It is possible.

[0194] Alternatively, as shown in Figs. 8(B-1) and 8(B-2), A separate antenna may be provided on each of a pair of opposing surfaces of secondary battery 913. FIG. 8(B-1) is an external view of one side of the pair of surfaces, and FIG. 8(B-2) is an external view of the pair of surfaces. 7(A) and 7(B). For details, the description of the power storage device illustrated in FIGS. 7A and 7B can be used as appropriate.

[0195] As shown in FIG. 8(B-1), a layer 916 is sandwiched between one of the two surfaces of a secondary battery 913. 8B-2, a secondary battery 91 An antenna 918 is provided on the other of the pair of surfaces of the substrate 3, sandwiching a layer 917 therebetween. For example, the antenna 918 has a function of performing data communication with an external device. For example, antennas having shapes applicable to the antennas 914 and 915 can be applied. As a communication method between the power storage device and other devices via antenna 918, NFC is available. It is possible to apply a response method that can be used between the power storage device and other devices, such as Cut.

[0196] Alternatively, as shown in FIG. 9A, the secondary battery 913 shown in FIGS. 7A and 7B may be A display device 920 may be provided. The display device 920 is electrically connected to the terminal 911 via the terminal 919. It is not necessary to provide the label 910 in the area where the display device 920 is provided. Note that the same parts as those of the power storage device shown in FIGS. 7(A) and 7(B) are shown in FIG. The description of the power storage device in FIG. 7B can be used as appropriate.

[0197] The display device 920 displays, for example, an image indicating whether charging is in progress or not, an image indicating the amount of stored power, etc. The display device 920 may be, for example, an electronic paper, a liquid crystal display, an electrophotographic display, or the like. For example, an electroluminescence (EL) display device can be used. By using the par, the power consumption of the display device 920 can be reduced.

[0198] Alternatively, as shown in FIG. 9B, the secondary battery 913 shown in FIGS. 7A and 7B may be used. The sensor 921 may be electrically connected to the terminal 911 via a terminal 922. 7A and 7B. The same parts as those in the power storage device shown in FIG. The description of the power storage device in FIGS. 7A and 7B can be used as appropriate.

[0199] The sensor 921 may be, for example, a sensor for detecting displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, etc. , liquid, magnetic, temperature, chemical, sound, time, hardness, electric field, current, voltage, power, radiation, flow It is sufficient if it has the function of measuring volume, humidity, gradient, vibration, odor, or infrared. By providing the sensor 921, for example, data indicating the environment in which the power storage device is placed can be acquired. It is also possible to detect a signal (such as temperature) and store it in memory within the circuit 912.

[0200] Furthermore, an example of the structure of the secondary battery 913 will be described with reference to FIGS.

[0201] The secondary battery 913 shown in FIG. 10(A) has a terminal 951 and a terminal 952 provided inside a housing 930. The winding body 950 is impregnated with an electrolyte inside the housing 930. The terminal 952 is in contact with the housing 930, and the terminal 951 is in contact with the housing by using an insulating material or the like. 10(A), the housing 930 is not in contact with the housing 930. Although the figure shows the winding body 950, in reality, the winding body 950 is covered by the housing 930, and the terminals 951 and 955 are 2 extends outside the housing 930. The housing 930 is made of a metal material (e.g., aluminum Rubber or resin materials can be used.

[0202] As shown in FIG. 10(B), the housing 930 shown in FIG. 10(A) is made of a plurality of materials. For example, the secondary battery 913 shown in FIG. The wound body 930 is located in the area surrounded by the housing 930a and the housing 930b. 50 are provided.

[0203] The housing 930a can be made of an insulating material such as organic resin. By using a material such as organic resin on the surface on which the secondary battery 913 is formed, If the shielding of the electric field by the housing 930a is small, the shielding of the electric field by the housing 930a can be suppressed. Antennas such as antenna 914 and antenna 915 may be provided inside the housing 930b. For example, a metal material can be used.

[0204] Furthermore, the structure of the wound body 950 is shown in Fig. 11. The wound body 950 is made up of a negative electrode 931 and a positive electrode 932. The winding body 950 has a pole 932 and a separator 933. The negative electrode 931 and the positive electrode 932 are stacked one on top of the other, and the laminated sheet is wound to form a wound body. The negative electrode 931, the positive electrode 932, and the separator 933 may be further laminated. You can stack several of them.

[0205] The negative electrode 931 is connected to the terminal 911 shown in FIG. 7 via one of the terminals 951 and 952. The positive electrode 932 is connected to the terminal 911 shown in FIG. 7 via the other of the terminals 951 and 952. Connected.

[0206] By using the positive electrode active material particles 100 described in the previous embodiment for the positive electrode 932, deterioration is reduced. Therefore, the secondary battery 913 can be made small and highly safe.

[0207] [Laminated secondary battery] Next, an example of a laminated secondary battery will be described with reference to FIGS. If the laminated secondary battery is made flexible, it will have at least one flexible portion. If the secondary battery is mounted in an electronic device that also has a battery, it can be bent according to the deformation of the electronic device. can.

[0208] A laminated secondary battery 980 will be described with reference to FIG. The battery 980 has a wound body 993 shown in FIG. 11, a positive electrode 995, and a separator 996. Similar to the wound body 950, a negative electrode 994 and a positive electrode 995 are stacked with a separator 996 sandwiched therebetween. The laminated sheet is then wound up.

[0209] The number of layers of the negative electrode 994, the positive electrode 995, and the separator 996 is determined as required. The negative electrode 994 is connected to the lead electrode 997 and the lead The positive electrode 995 is connected to a negative electrode current collector (not shown) via one of the lead electrodes 998. The positive electrode 997 and the lead electrode 998 are connected to a positive electrode current collector (not shown).

[0210] As shown in FIG. 12(B), a film 981 that serves as an exterior body and a film 98 having a recess are 2 are bonded together by thermocompression or the like, and the above-mentioned wound body 993 is housed in the space formed. In this way, a secondary battery 980 can be fabricated as shown in FIG. 3 has lead electrodes 997 and 998, and is connected to a film 981 and a recessed portion. The inside of the space surrounded by the film 982 is impregnated with an electrolyte.

[0211] The film 981 and the film 982 having the recesses are made of a metal material such as aluminum. The film 981 and the film 982 having the recesses can be made of a material such as a resin. If a resin material is used as the material, when external force is applied, the film 981 and the recessed portion The film 982 can be deformed to produce a flexible secondary battery. can be done.

[0212] In addition, although two films are used in FIGS. 12(B) and 12(C), one film may be used. A space is formed by folding one film, and the above-mentioned wound body 993 is inserted into the space. may be stored.

[0213] By using the positive electrode active material particles 100 described in the previous embodiment for the positive electrode 995, deterioration is reduced. Therefore, the secondary battery 980 can be made low in energy consumption and highly safe.

[0214] 12 shows a secondary battery 9 having a wound body in a space formed by a film that serves as an exterior body. 80 has been explained, but as shown in Figure 13, for example, The space defined by the positive electrode layer may be a secondary battery having a plurality of rectangular positive electrodes, separators, and negative electrodes. stomach.

[0215] The laminated secondary battery 500 shown in FIG. 13(A) includes a positive electrode current collector 501 and a positive electrode active material. a positive electrode 503 having a positive electrode active material layer 502, a negative electrode current collector 504 and a negative electrode active material layer 505 The battery includes a negative electrode 506, a separator 507, an electrolyte 508, and an exterior body 509. A separator 507 is provided between a positive electrode 503 and a negative electrode 506 provided in a body 509. The exterior body 509 is filled with an electrolyte 508. The electrolyte solution shown in the second embodiment can be used.

[0216] In the laminated secondary battery 500 shown in FIG. 13(A), a positive electrode current collector 501 and a negative electrode current collector 502 are The electrode current collector 504 also serves as a terminal for electrical contact with the outside. A part of the current collector 501 and the negative electrode current collector 504 is exposed to the outside from the outer casing 509. In addition, the positive electrode current collector 501 and the negative electrode current collector 504 may be disposed in the outer casing 509. The lead electrode is not exposed to the outside, and the lead electrode is connected to the positive electrode current collector 501 or the negative electrode The lead electrode may be exposed to the outside by ultrasonic bonding to the current collector 504 .

[0217] In the laminated secondary battery 500, the exterior body 509 is made of, for example, polyethylene, poly A film made of propylene, polycarbonate, ionomer, polyamide, etc. is coated with an A thin metal film with excellent flexibility, such as aluminum, stainless steel, copper, or nickel, is applied, and the metal is further On the metallic thin film, an insulating synthetic resin such as polyamide resin or polyester resin is applied as the outer surface of the exterior body. A three-layer laminate film provided with an oil film can be used.

[0218] An example of the cross-sectional structure of a laminated secondary battery 500 is shown in FIG. A) shows an example of a structure consisting of two current collectors for simplicity, but in reality, it is composed of multiple electrode layers. It consists of:

[0219] In FIG. 13(B), as an example, the number of electrode layers is set to 16. However, the secondary battery 500 has flexibility. In FIG. 13(B), the negative electrode current collector 504 has eight layers. The positive electrode current collector 501 has eight layers, making a total of 16 layers. The cross section of the extraction part is shown, and eight layers of negative electrode current collector 504 are ultrasonically bonded. The number of electrode layers is not limited to 16, and may be more or less. In this case, a secondary battery having a larger capacity can be obtained. In this case, a secondary battery can be made thin and highly flexible.

[0220] An example of the external appearance of a laminated secondary battery 500 is shown in FIGS. 14 and 15. 4 and 15 show a positive electrode 503, a negative electrode 506, a separator 507, an outer casing 509, a positive electrode lead The positive electrode 510 and the negative electrode 511 are provided.

[0221] 16(A) shows an external view of the positive electrode 503 and the negative electrode 506. The positive electrode 503 is connected to the positive electrode current collector 50 1, and the positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501. 503 has a region where the positive electrode current collector 501 is partially exposed (hereinafter referred to as the tab region). 506 has a negative electrode current collector 504, and a negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. In addition, the negative electrode 506 has a region where the negative electrode current collector 504 is partially exposed, that is, a tab region. The area and shape of the tab regions of the positive electrode and negative electrode are not limited to the example shown in FIG. I can't.

[0222] [Method for manufacturing laminated secondary batteries] Here, an example of a method for manufacturing the laminated secondary battery shown in FIG. 14 will be described with reference to FIG. This will be explained using FIG. 16(B) and FIG. 16(C).

[0223] First, the negative electrode 506, the separator 507, and the positive electrode 503 are stacked. The figure shows five pairs of negative electrodes 506, separators 507, and positive electrodes 503. Next, the bonding of the tab regions of the positive electrode 503 and the bonding of the tabs of the positive electrode on the outermost surface are shown. The positive electrode lead electrode 510 is bonded to the region. For example, ultrasonic welding or the like can be used for bonding. Similarly, the bonding of the tab regions of the negative electrodes 506 to each other and the bonding of the negative electrode leads to the tab region of the negative electrode on the outermost surface are also preferable. The bonded electrode 511 is then bonded.

[0224] Next, the negative electrode 506 , the separator 507 and the positive electrode 503 are placed on the exterior body 509 .

[0225] Next, as shown in FIG. 16(C), the exterior body 509 is folded at the portion indicated by the broken line. After that, the outer periphery of the exterior body 509 is bonded. For example, thermocompression bonding may be used for bonding. , so that the electrolyte 508 can be poured later, An area that is not bonded (hereinafter referred to as an inlet) is provided.

[0226] Next, the electrolyte 508 is introduced into the inside of the exterior body 509 through an inlet provided in the exterior body 509. The introduction of the electrolytic solution 508 is preferably carried out under a reduced pressure atmosphere or an inert gas atmosphere. Finally, the inlet is joined. In this way, a laminated secondary battery is completed. A secondary battery 500 can be fabricated.

[0227] By using the positive electrode active material particles 100 described in the previous embodiment for the positive electrode 503, deterioration is reduced. Therefore, the secondary battery 500 can be made low in energy consumption and highly safe.

[0228] [Bendable secondary battery] Next, an example of a bendable secondary battery will be described with reference to FIGS.

[0229] Figure 17(A) shows a schematic top view of a bendable battery 250. 17(B2) and 17(C) show the cutting lines C1-C2 and C3 in FIG. 17(A), respectively. 1 is a schematic cross-sectional view taken along line C3-C4 and line A1-A2. 51, and a positive electrode 211a and a negative electrode 211b housed inside the exterior body 251. A lead 212a electrically connected to the negative electrode 211a, and a lead 212b electrically connected to the negative electrode 211b. The lead 212b extends outside the package 251. In the region, an electrolyte (not shown) is sealed in addition to the positive electrode 211a and the negative electrode 211b. are.

[0230] The positive electrode 211a and the negative electrode 211b of the battery 250 will be described with reference to FIG. 18. FIG. 18(A) illustrates the stacking order of the positive electrode 211a, the negative electrode 211b, and the separator 214. FIG. 18(B) shows a perspective view of the positive electrode 211a and the negative electrode 211b, as well as a lead 2 12a and a lead 212b.

[0231] As shown in FIG. 18(A), the battery 250 includes a plurality of rectangular positive electrodes 211a, a plurality of rectangular positive electrodes 211b, a plurality of rectangular positive electrodes 211c, a plurality of rectangular positive electrodes 211d, a plurality of rectangular positive electrodes 211e, a plurality of rectangular positive electrodes 211f, a plurality of rectangular positive electrodes 211g, a plurality of rectangular positive electrodes 211h ... The positive electrode 211a and the negative electrode 211b are connected to each other, and a plurality of separators 214 are connected to each other. Each of the positive electrode 211a and the positive electrode 211b has a protruding tab portion and a portion other than the tab. A positive electrode active material layer is formed on the portion other than the tab, and a negative electrode 211b is formed on the portion other than the tab on one surface of the negative electrode 211b. A negative electrode active material layer is formed.

[0232] The surfaces of the positive electrode 211a on which the positive electrode active material layer is not formed and the surfaces of the negative electrode 211b on which the negative electrode active material layer is not formed are The positive electrode 211a and the negative electrode 211b are stacked so that the surfaces on which the porous layer is not formed are in contact with each other. will be done.

[0233] In addition, the surface on which the positive electrode active material layer of the positive electrode 211a is formed and the surface on which the negative electrode active material layer of the negative electrode 211b is formed are A separator 214 is provided between the formed surfaces. Data 214 is shown by a dotted line.

[0234] As shown in FIG. 18(B), the positive electrodes 211a and the leads 212a are connected to each other at the joints 215. The negative electrodes 211b and the leads 212b are electrically connected at the joints 211a and 212b. Electrical connection is made at 15b.

[0235] Next, regarding the exterior body 251, FIGS. 17(B1), 17(B2), 17(C) and 17 This is explained using (D).

[0236] The exterior body 251 has a film-like shape and is configured to sandwich the positive electrode 211a and the negative electrode 211b. The exterior body 251 is folded in two at the folded portion 261 and a pair of sealing portions 2 The pair of sealing portions 262 are connected to the positive electrode 211a and the negative electrode 211b. The seal portion 26 is provided on either side of the pole 211b and can also be called a side seal. 3 has a portion overlapping with the lead 212a and the lead 212b, and is also called a top seal. This can be done.

[0237] The exterior body 251 has a ridge line 271 and a valley line 272 at the portion overlapping the positive electrode 211a and the negative electrode 211b. It is preferable that the sealing portion 26 of the exterior body 251 has a wave shape in which the grooves 72 are arranged alternately. 2 and the seal portion 263 are preferably flat.

[0238] FIG. 17(B1) is a cross section cut at the part overlapping with the ridge line 271, and FIG. 17(B2) is a cross section cut at the part overlapping with the ridge line 271. The cross section is taken at the part overlapping with the valley line 272. Figure 17(B1) and Figure 17(B2) are both , corresponds to a cross section in the width direction of the battery 250, the positive electrode 211a, and the negative electrode 211b.

[0239] Here, the end of the negative electrode 211b in the width direction, i.e., the end of the negative electrode 211b and the seal portion 262 The distance between the battery 250 and the electrode 251 is defined as La. In this way, the positive electrode 211a and the negative electrode 211b are deformed so as to be displaced from each other in the length direction. In this case, if the distance La is too short, the exterior body 251 will rub strongly against the positive electrode 211a and the negative electrode 211b. In particular, if the metal film of the exterior body 251 is exposed, In this case, the metal film may be corroded by the electrolyte. It is preferable to set the distance La as long as possible. On the other hand, if the distance La is set too large, , the volume of the battery 250 increases.

[0240] In addition, the greater the total thickness of the stacked positive electrode 211a and negative electrode 211b, the greater the It is preferable to increase the distance La between b and the seal portion 262.

[0241] More specifically, the total thickness of the stacked positive electrode 211a and negative electrode 211b is defined as thickness t. When the distance La is 0.8 times or more and 3.0 times or less, preferably 0.9 times or more and 2.0 times or less, of the thickness t, It is preferable that the distance La is 5 times or less, and more preferably 1.0 to 2.0 times. By setting the thickness within this range, a compact battery with high reliability against bending can be realized. .

[0242] In addition, when the distance between the pair of seal portions 262 is a distance Lb, the distance Lb is and is sufficiently larger than the width of the negative electrode 211b (here, the width Wb of the negative electrode 211b). This is preferable because the positive electrode Even if the positive electrode 211a and the negative electrode 211b come into contact with the exterior body 251, Since a part of 11b can be shifted in the width direction, the positive electrode 211a and the negative electrode 211b can be shifted in the width direction. This effectively prevents the attachment body 251 from rubbing against each other.

[0243] For example, the difference between the distance Lb between the pair of seal portions 262 and the width Wb of the negative electrode 211b is 1.6 times or more and 6.0 times or less, preferably 1.8 times, the thickness t of 211a and the negative electrode 211b It is preferably from 2.0 to 5.0 times, more preferably from 2.0 to 4.0 times.

[0244] In other words, it is preferable that the distance Lb, the width Wb, and the thickness t satisfy the relationship of the following formula 2: It's nice.

[0245]

number

[0246] Here, a is 0.8 or more and 3.0 or less, preferably 0.9 or more and 2.5 or less, and more preferably is between 1.0 and 2.0.

[0247] FIG. 17(C) is a cross section including the lead 212a, and shows the battery 250, the positive electrode 211a, and As shown in FIG. 17(C), the bent portion 2 corresponds to a cross section of the negative electrode 211b in the longitudinal direction. 61, the ends of the positive electrode 211a and the negative electrode 211b in the length direction and the outer casing 251 It is preferable to have a space 273 therebetween.

[0248] FIG. 17(D) shows a schematic cross-sectional view of the battery 250 when bent. This corresponds to the cross section taken along the line B1-B2 in FIG. 17(A).

[0249] When the battery 250 is bent, the part of the exterior body 251 located on the outside of the bend stretches, and the part located on the inside More specifically, the part located on the outside of the exterior body 251 is deformed so as to shrink. On the other hand, the outer casing 251 is deformed so that the amplitude of the wave becomes smaller and the period of the wave becomes larger. The part located inside the In this way, the deformation of the exterior body 251 causes the load acting on the exterior body 251 due to bending. Since the stress is relieved, the material that constitutes the exterior body 251 itself does not need to expand or contract. As a result, the battery 250 can be bent with a small force without damaging the exterior body 251.

[0250] Furthermore, as shown in FIG. 17(D), when the battery 250 is bent, the positive electrode 211a and the negative electrode 21 At this time, the plurality of stacked positive electrodes 211a and negative electrodes 1b are displaced relative to each other. Since one end of 211b on the sealing portion 263 side is fixed by the fixing member 217, The amount of deviation increases as the electrode is closer to the positive electrode 21. The stress applied to the positive electrode 211a and the negative electrode 211b is relieved, and the positive electrode 211a and the negative electrode 211b themselves As a result, the positive electrode 211a and the negative electrode 211b do not need to be stretched or contracted. The battery 250 can be bent.

[0251] In addition, a space 273 is provided between the positive electrode 211a and the negative electrode 211b and the exterior body 251. When the battery is bent, the positive electrode 211a and the negative electrode 211b located on the inside are bent by the outer casing 25. It can move relative to 1 without touching it.

[0252] The battery 250 illustrated in FIGS. 17 and 18 does not break the exterior body even when repeatedly bent and stretched. Damage to the positive electrode 211a and the negative electrode 211b is unlikely to occur, and the battery characteristics are unlikely to deteriorate. The battery 250 has a positive electrode 211a containing the positive electrode active material described in the previous embodiment. By using the particles 100, it is possible to make a secondary battery with less deterioration and higher safety. Cut.

[0253] (Fourth embodiment) In this embodiment, an example in which a secondary battery according to one embodiment of the present invention is mounted on an electronic device will be described. do.

[0254] First, as explained in part of the third embodiment, a bendable secondary battery is mounted on an electronic device. An example is shown in Figure 19. An example of an electronic device that uses a bendable secondary battery is a Revision equipment (also called television or television receiver), computer monitors, etc. Digital cameras, digital video cameras, digital photo frames, mobile phones ( Mobile phones, also known as mobile phone devices, portable game machines, portable information terminals, sound reproducing devices, Examples include large game machines such as dick machines.

[0255] In addition, the flexible secondary battery can be mounted on the inner or outer wall of a house or building, or on the inside or outside of a car. It is also possible to incorporate it along the curved surface of the interior or exterior of the vehicle.

[0256] FIG. 19A shows an example of a mobile phone. The mobile phone 7400 has a housing 7401. In addition to the display unit 7402 incorporated in the The mobile phone 7400 is equipped with a speaker 7405, a microphone 7406, etc. It has a battery 7407.

[0257] FIG. 19B shows the mobile phone 7400 in a curved state. When the entire device is deformed by an external force and curved, the secondary battery inside 7407 is also bent. At this time, the state of the bent secondary battery 7407 is shown in FIG. The secondary battery 7407 is a thin secondary battery. The secondary battery 7407 is bent. The secondary battery 7407 is fixed in a state where the lead electrode is electrically connected to the current collector. It has the following characteristics.

[0258] FIG. 19(D) shows an example of a bangle-type display device. The portable display device 7100 includes: The device includes a housing 7101, a display unit 7102, operation buttons 7103, and a secondary battery 7104. 19(E) shows the state of the bent secondary battery 7104. The secondary battery 7104 is bent. When the device is worn on the user's arm with the device attached, the housing may deform and cause damage to part of the secondary battery 7104 or The total curvature changes. The degree of curvature at any point on the curve is expressed as the radius of the corresponding circle. The value expressed is called the radius of curvature, and the reciprocal of the radius of curvature is called the curvature. Specifically, the radius of curvature is The area is within the range of 40 mm to 150 mm, and the area is part of the main surface of the casing or the secondary battery 7104. The radius of curvature of the main surface of the secondary battery 7104 is 40 mm or more and 150 mm or less. High reliability can be maintained if the distance is within the range of mm or less.

[0259] FIG. 19(F) shows an example of a wristwatch-type portable information terminal. The portable information terminal 7200 is , a housing 7201, a display unit 7202, a band 7203, a buckle 7204, and an operation button 72 05, input / output terminal 7206, etc.

[0260] The portable information terminal 7200 is capable of carrying out mobile phone calls, e-mails, viewing and creating documents, playing music, and internet access. - It can run various applications such as internet communication and computer games. do.

[0261] The display surface of the display unit 7202 is curved, and the display is performed along the curved display surface. The display portion 7202 is provided with a touch sensor, and can be touched with a finger or a stylus. For example, the icon 72 displayed on the display unit 7202 can be operated by touching it. You can launch the application by touching 07.

[0262] The operation button 7205 is used to set the time, turn the power on and off, and turn wireless communication on and off. It has various functions such as operation, silent mode activation and deactivation, power saving mode activation and deactivation, etc. For example, an operating system installed in the portable information terminal 7200 can The function of the operation button 7205 can also be freely set using the stem.

[0263] In addition, the mobile information terminal 7200 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.

[0264] The portable information terminal 7200 also has an input / output terminal 7206, and a connector for connecting to other information terminals. Data can be exchanged directly via the input / output terminal 7206. The charging operation can be performed by wireless power supply without going through the input / output terminal 7206. It is also possible.

[0265] The display portion 7202 of the portable information terminal 7200 includes the secondary battery of one embodiment of the present invention. For example, the secondary battery 7104 shown in FIG. 19E is curved inside the housing 7201. Alternatively, it can be incorporated in the band 7203 in a bendable state.

[0266] The mobile information terminal 7200 preferably has a sensor. For example, a fingerprint sensor may be used as the sensor. Human body sensors such as pulse sensors and body temperature sensors, as well as touch sensors, pressure sensors, and acceleration sensors It is preferable that a sensor, etc. be installed.

[0267] FIG. 19G shows an example of a wristband-type display device. The display device 7300 includes a display unit 7 304 and includes the secondary battery of one embodiment of the present invention. The display unit 7304 may be provided with a touch sensor, and may function as a portable information terminal. It is also possible.

[0268] The display surface of the display unit 7304 is curved, and images can be displayed along the curved display surface. The display device 7300 can also communicate with the display device 7300 by short-distance wireless communication according to a communication standard. The situation can be changed.

[0269] The display device 7300 is also equipped with an input / output terminal, and can be directly connected to other information terminals via a connector. It is also possible to charge the device via the input / output terminals. The charging operation may be performed by wireless power supply without using the input / output terminals.

[0270] Next, Fig. 20(A) and Fig. 20(B) show an example of a foldable tablet terminal. The tablet terminal 9600 shown in FIGS. 20A and 20B includes a housing 9630a, a housing 9630b, a movable part 9640 connecting the housings 9630a and 9630b, a display part 9 631, display mode switch 9626, power switch 9627, power saving mode switch The display unit 9 has a changeover switch 9625, a fastener 9629, and an operation switch 9628. The 631 uses a flexible panel, allowing for a tablet with a wider display area. FIG. 20A shows a tablet terminal 9600 in an open state. FIG. 20B shows the tablet terminal 9600 in a closed state.

[0271] The tablet terminal 9600 also includes a battery storage device inside the housing 9630a and the housing 9630b. The power storage unit 9635 is connected to the housing 9630a through the movable portion 9640. It is located across 9630b.

[0272] A part of the display unit 9631 can be used as a touch panel area, and the user can operate the displayed operation keys. You can input data by touching the screen. You can also switch the keyboard display on the touch panel. By touching the area where the replacement button is displayed with your finger or a stylus, the display 9631 Keyboard buttons can be displayed.

[0273] A display mode changeover switch 9626 changes the display orientation between portrait and landscape. You can select between black and white and color display. The touch 9625 detects when in use by the light sensor built into the tablet terminal 9600. The display brightness can be optimized according to the amount of external light. In addition to optical sensors, other sensors such as gyros and acceleration sensors that detect tilt are also available. The device may be built-in.

[0274] FIG. 20B shows the tablet terminal in a closed state, and the tablet terminal includes a housing 9630 and a solar cell 96 33, a charge / discharge control circuit 9634 including a DC / DC converter 9636. As 9635, a secondary battery according to one embodiment of the present invention is used.

[0275] The tablet terminal 9600 can be folded in half, so when not in use, the housing 9630a and The housing 9630b can be folded so that the housing 9630a and the housing 9630b overlap each other. Since the display portion 9631 can be protected, the durability of the tablet terminal 9600 can be improved. Furthermore, the power storage unit 9635 using the secondary battery of one embodiment of the present invention has a high capacity and a good cycle life. Because of its excellent thermal properties, it is possible to provide a tablet device that can be used for a long period of time. do.

[0276] In addition, the tablet terminals shown in Figs. 20(A) and 20(B) can store various information. Functions that display information (still images, videos, text images, etc.), calendars, dates, or times, etc. The function to display the information on the display unit, and to operate or edit the information displayed on the display unit by touch input. , touch input function, function to control processing by various software (programs), etc. It can have:

[0277] The solar cell 9633 attached to the surface of the tablet terminal supplies power to the touch panel, The solar cell 9633 can be supplied to a display unit, a video signal processor, or the like. The structure can be provided on one or both sides of the power storage unit 9630, and can efficiently charge the power storage unit 9635. It can be concluded that

[0278] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 20(B) are shown in FIG. A block diagram is shown in FIG. 20(C) and will be explained. In FIG. 20(C), a solar cell 9633, a power storage unit 963 5, DC-DC converter 9636, converter 9637, switches SW1 to SW3, table The display unit 9631 is shown, and the storage battery 9635, the DC-DC converter 9636, 20B. This corresponds to 34.

[0279] First, an example of operation when power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell is converted into a voltage for charging the storage battery 9635. The voltage is increased or decreased by a inverter 9636. When power is used from the 9633, switch SW1 is turned on and the converter 9637 The voltage is increased or decreased to the voltage required for the display unit 9631. When not displaying the data, turn switch SW1 off and switch SW2 on. The configuration may be such that the electric body 9635 is charged.

[0280] The solar cell 9633 is shown as an example of a power generating means, but is not particularly limited thereto. Power storage using other power generation methods such as piezoelectric elements and thermoelectric conversion elements For example, the power may be transmitted and received wirelessly (contactlessly). It is also possible to combine it with a contactless power transmission module that charges the battery, or other charging means. That's fine.

[0281] Another example of electronic equipment is shown in FIG. 21. In FIG. 21, a display device 8000 is a display device according to one embodiment of the present invention. 8 is an example of an electronic device using a secondary battery 8004 according to an embodiment. 8000 corresponds to a display device for receiving TV broadcasts, and includes a housing 8001, a display unit 8002, and a speaker unit. The secondary battery 8004 according to one embodiment of the present invention includes a housing 8003 and a secondary battery 8004. The display device 8000 is provided inside a body 8001. The display device 8000 receives power from a commercial power source. Alternatively, the power stored in the secondary battery 8004 can be used. Even when power cannot be supplied from a commercial power source due to a power outage or the like, the present invention The display device 8000 can be used by using the secondary battery 8004 as an uninterruptible power supply. do.

[0282] The display unit 8002 includes a liquid crystal display device, an emitting device having a light emitting element such as an organic EL element in each pixel, and Device, electrophoretic display device, DMD (Digital Micromirror Device) ce), PDP (Plasma Display Panel), FED (Field A semiconductor display device such as a reflective LED (emission display) can be used.

[0283] In addition to TV broadcast reception, display devices are also used for personal computers and advertising displays. , including all display devices for displaying information.

[0284] In FIG. 21, a stationary lighting device 8100 includes a secondary battery 81 according to one embodiment of the present invention. 8101, a housing 8102, a light source 8103, and a light source 8104. 21, the secondary battery 8103 is mounted in the housing 81. 8101 and a light source 8102 are installed inside a ceiling 8104. However, the secondary battery 8103 may be provided inside the housing 8101. The device 8100 can receive power from a commercial power source or can store power in a secondary battery 8103. Therefore, if the power supply from the commercial power source is interrupted due to a power outage, etc., Even when the power is not available, the secondary battery 8103 according to one embodiment of the present invention can be used as an uninterruptible power supply. This allows the lighting device 8100 to be used.

[0285] 21 shows an example of a lighting device 8100 that is installed on a ceiling 8104. However, the secondary battery according to one embodiment of the present invention is not limited to the ceiling 8104, but may be installed on other parts such as the side wall 8105 and the floor 8106. 106, it can be used for a fixed lighting device provided in a window 8107, etc., or it can be used for a tabletop lighting device. It can also be used in lighting devices of this type.

[0286] The light source 8102 may be an artificial light source that artificially obtains light using electricity. Specifically, incandescent lamps, discharge lamps such as fluorescent lamps, and light-emitting devices such as LEDs and organic EL elements The element is an example of the artificial light source.

[0287] In FIG. 21, an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is 8 is an example of an electronic device using a secondary battery 8203 according to one embodiment of the present invention. The device 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, and the like. 8 illustrates an example in which the secondary battery 8203 is provided in the indoor unit 8200. The battery 8203 may be provided in the outdoor unit 8204. Both the power supply 8201 and the power supply 8204 may be provided with a secondary battery 8203. The power supply can be supplied from a commercial power source, or the power stored in the secondary battery 8203 can be used. In particular, both the indoor unit 8200 and the outdoor unit 8204 may be equipped with secondary batteries 82 If 03 is installed, when power cannot be supplied from the commercial power source due to a power outage, etc. In addition, by using the secondary battery 8203 of one embodiment of the present invention as an uninterruptible power supply, The conditioner can be used.

[0288] In Figure 21, a separate type air conditioner consisting of an indoor unit and an outdoor unit is shown. As an example, it is an all-in-one air conditioner that has the functions of both the indoor unit and the outdoor unit in a single housing. The secondary battery according to one embodiment of the present invention can also be used in the conditioner.

[0289] In FIG. 21, an electric refrigerator-freezer 8300 includes a secondary battery 8304 according to one embodiment of the present invention. Specifically, an electric refrigerator-freezer 8300 includes a housing 8301, a refrigerator It has a storage compartment door 8302, a freezer compartment door 8303, a secondary battery 8304, etc. A secondary battery 8304 is provided inside the housing 8301. The electric refrigerator-freezer 8300 is It can receive power from a commercial power source, or use the power stored in the secondary battery 8304. Therefore, when power cannot be supplied from the commercial power source due to a power outage, etc. However, by using the secondary battery 8304 of one embodiment of the present invention as an uninterruptible power supply, It will be possible to use the 8300 freezer refrigerator.

[0290] In addition, during times when electronic devices are not in use, especially when the total amount of power that can be supplied by the commercial power supplier is low, During the time period when the ratio of the amount of electricity actually used (called the electricity usage rate) is low, By storing power in the battery, it is possible to prevent power usage rates from increasing outside of the above time periods. For example, in the case of the electric refrigerator-freezer 8300, when the temperature is low and the refrigerator compartment door 830 2. During the night when the freezer door 8303 is not opened or closed, the secondary battery 8304 stores power. Then, as the temperature rises, the refrigerator door 8302 and the freezer door 8303 are opened and closed. By using the secondary battery 8304 as an auxiliary power source during the daytime, the daytime power usage rate can be kept low.

[0291] In addition to the electronic devices described above, the secondary battery according to one embodiment of the present invention can be mounted in various electronic devices. According to one embodiment of the present invention, a secondary battery with little deterioration and high safety can be provided. Therefore, when the secondary battery according to one embodiment of the present invention is installed in the electronic device described in this embodiment, This allows the electronic device to have a longer life and higher safety. The present embodiment can be implemented in appropriate combination with other embodiments.

[0292] (Embodiment 5) In this embodiment, an example in which a secondary battery according to one embodiment of the present invention is mounted on a vehicle will be described.

[0293] When a secondary battery is installed in a vehicle, it becomes a hybrid vehicle (HEV), an electric vehicle (EV), or a powertrain. This will enable the realization of next-generation clean energy vehicles such as plug-in hybrid vehicles (PHEVs). .

[0294] 22A and 22B illustrate an example of a vehicle using a secondary battery according to one embodiment of the present invention. The automobile 8400 shown in FIG. 1 is an electric automobile that uses an electric motor as a power source for driving. Alternatively, an electric motor and an engine can be selected as the power source for driving. The hybrid vehicle can be realized by using the secondary battery according to one embodiment of the present invention. In addition, the automobile 8400 has a secondary battery. The secondary battery not only drives the electric motor 8406 but also powers the headlights 8401 and Power can be supplied to a light emitting device such as a room light (not shown).

[0295] In addition, the secondary battery is used to power the speedometer, tachometer, and other displays of the automobile 8400. The secondary battery can supply power to the navigation device of the automobile 8400. The present invention can provide power to semiconductor devices such as mobile terminals.

[0296] The automobile 8500 shown in FIG. 22(B) has a plug-in secondary battery 8024. Charging is performed by receiving power from an external charging facility using a plug-in method or a wireless power supply method. FIG. 22(B) shows a case where a charging device 8021 is installed on a ground and a charging station 8022 is installed in a vehicle 8500. The secondary battery 8024 is being charged via a cable 8022. When charging, the charging method and connectors must comply with standards such as CHAdeMO (registered trademark) and Combo. The charging device 8021 is a charging station installed in a commercial facility. For example, plug-in technology can be used to The secondary battery 8024 installed in the automobile 8500 can be charged by the power supply. Charging is performed by converting AC power to DC power via a converter such as an AC-DC converter. It is possible.

[0297] Although not shown, a power receiving device is mounted on the vehicle and power is supplied contactlessly from a power transmitting device on the ground. In this case, a power transmission device is installed on the road or exterior wall. By incorporating this technology, charging can be carried out not only when the vehicle is stopped but also while the vehicle is moving. This method may be used to transmit and receive power between vehicles. A solar cell may be provided to charge the secondary battery when the vehicle is stopped or running. The power can be supplied by an electromagnetic induction method or a magnetic resonance method.

[0298] 22C shows an example of a two-wheeled vehicle using the secondary battery of one embodiment of the present invention. The scooter 8600 shown in (C) has a secondary battery 8602, side mirrors 8601, and a turn signal. The secondary battery 8602 can supply electricity to the direction indicator light 8603. can.

[0299] In addition, the scooter 8600 shown in FIG. 22(C) has a secondary battery 860 in the storage space under the seat 8604. 2 can be stored. The secondary battery 8602 can be stored even if the under-seat storage 8604 is small. , and can be stored in the under-seat storage compartment 8604.

[0300] According to one embodiment of the present invention, a secondary battery that is less prone to deterioration and highly safe can be obtained. Therefore, by installing it in a vehicle, it is possible to prevent a decrease in cruising range and acceleration performance. Furthermore, the vehicle can be made highly safe. In this case, for example, during peak power demand, It is possible to avoid using commercial power sources during peak power demand periods. If this can be avoided, it will contribute to energy conservation and reduction of carbon dioxide emissions. In addition, cobalt is used as a secondary battery because it has little deterioration and can be used for a long period of time. This will reduce the amount of rare metals used, including

[0301] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Example]

[0302] In this example, a positive electrode active material having magnesium, fluorine, and oxygen at and near the grain boundaries The active material was prepared and subjected to TEM observation and STEM-EDX analysis to identify the crystal grains and crystallites in the active material. The concentration distribution at the grain boundaries was confirmed. The sample was one of Sample A, which is one embodiment of the present invention. As material A, nickel-containing magnesium, fluorine, and oxygen at and near the grain boundaries was used. Lithium manganese-cobalt oxide was prepared. Lithium nickel-manganese-cobalt oxide The composition is LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2 is assumed. LiNi 1 / 3 Mn 1 / 3Co 1 / 3 O2 has a layered rock salt type crystal structure.

[0303] <Preparation of Sample A> The preparation of sample A will be described.

[0304] As shown in step S11 of the flow in Figure 3, starting materials were prepared. Lithium oxide (Li2CO3), nickel oxide (NiO) as a nickel source, and manganese source manganese dioxide (MnO2) as a cobalt source, tricobalt tetroxide (Co3O4) as a cobalt source, Magnesium oxide (MgO) was used as the magnesium source, and lithium fluoride (LiF) was used as the fluorine source. Specifically, 3.1398 g (42.49 mmol) of Li2CO3 was weighed. , 2.1159 g (28.33 mmol) of NiO, and 2.4627 g (28. 33 mmol), 2.2033 g (9.15 mmol) of Co3O4, 0.03 43 g (0.85 mmol) of ZnO and 0.0441 g (1.70 mmol) of LiF were weighed out. This is the ratio of magnesium atoms to the total number of nickel, manganese, and cobalt atoms. The ratio m of the number of magnesium atoms is 0.010 (1.0%). The amount is such that the ratio of the number of fluorine atoms, n, is 2.0. NiO was manufactured by Kojundo Chemical Research Institute (catalog number: LIH06XB). MnO2 was manufactured by Kojundo Chemical Laboratory Co., Ltd. (catalog number: NIO04PB). Co3O4 was manufactured by Kojundo Chemical Laboratory Co., Ltd. (catalog number: COO09PB). MgO was manufactured by Kojundo Chemical Laboratory Co., Ltd. (catalog number: MGO12 LiF was manufactured by Kojundo Chemical Laboratory Co., Ltd. (catalog number: LIH10XB). there was.

[0305] Next, as shown in step S12, the starting materials weighed in step S11 were mixed. A wet ball mill was used for mixing. Specifically, the balls were 3 mm in diameter and acetone was used as the solvent. The mixture was ground and mixed for 2 hours at a rotation speed of 300 rpm.

[0306] Next, as shown in step S13, the material mixed in step S12 is subjected to a first heating. The first heating was performed using a muffle furnace at a temperature increase rate of 200°C / hr from room temperature for 1000°C. The temperature was raised to 1000 °C and heating was carried out at 1000 °C for 10 hours. The heating was carried out in a dry air atmosphere, and the flow rate of the dry atmosphere was set to 10 L / min.

[0307] By the first heating in step S13, lithium nickel manganese cobalt oxide can be synthesized. At this point, part of the magnesium and fluorine is considered to be in a state of being dissolved in the grain boundaries and crystallites.

[0308] Next, as shown in step S14, the material heated in step S13 was cooled to room temperature, and composite 1 was obtained. After cooling, the obtained composite 1 was crushed to reduce the particle size of composite 1. A 53-μm mesh was used for the crushing process.

[0309] Next, as shown in step S15, the second heating was performed on composite 1 obtained in step S14. The second heating was carried out using a muffler furnace, and the temperature was raised from room temperature to 800 °C at a rate of 200 °C / hr and heated at 800 °C for 2 hours. The heating was carried out in a dry air atmosphere, and the flow rate of the dry atmosphere was set to 10 L / min.

[0310] By performing the second heating in step S15, it is possible to promote the segregation of magnesium and fluorine contained in the starting materials to the grain boundaries of lithium nickel manganese cobalt oxide.

[0311] Next, as shown in step S16, the composite 1 heated in step S15 was cooled to room temperature and recovered to obtain sample A.

[0312] <TEM Observation, STEM Observation, EDX Measurement> Next, sample A was processed by a focused ion beam (FIB). ​​​​The cross section of sample A was sliced ​​and observed by TEM and STEM. The composition was analyzed by X-ray measurement. TEM, STEM observation and EDX measurement were performed using JEOL J The EM-ARM200F was used, the acceleration voltage was 200 kV, and the beam diameter was approximately 0.1 nmφ. .

[0313] For EDX measurements, the elemental analyzer was an energy dispersive X-ray analyzer JED manufactured by JEOL Ltd. The EDX was used for the area analysis. The detection limit was approximately 1 atomic %. It is possible to detect elements from uranium (U) with atomic number 92 to uranium (B). do.

[0314] A TEM image (bright field image) of the cross section of sample A is shown in Figure 23(A). The magnification of Figure 23(A) is 10 In FIG. 23(A), the area where the density (brightness) of the TEM image is approximately uniform is the crystal orientation. The density (brightness) of the TEM image is almost constant, and it is considered to be a single crystal. This is thought to be a grain boundary. A schematic diagram corresponding to FIG. 23(A) is shown in FIG. 23(B). As shown in FIG. 23(B), the positive electrode active material particles have a plurality of crystal grains 1101 and gaps between the crystal grains. It was confirmed that there is a grain boundary 1103 in the

[0315] A STEM image (bright field image) of the cross section of sample A is shown in Figure 24(A), and a HAADF-STE image of the same location is shown. The M image is shown in Figure 24(B). The magnification of Figures 24(A) and 24(B) is 8 million times. In Figures 24(A) and 24(B), crystal lattice images could be confirmed in the crystal grain regions.

[0316] Next, we will explain the EDX spectrum of the cross section of sample A. In EDX measurement, electrons are The energy and number of characteristic X-rays generated by the irradiation are measured, and the EDX scan is performed. The HAADF-STEM image of the cross section of sample A and the EDX measurement points are shown in Figure 25. The EDX measurement points are five points, point 1 to point 5. Point 1 and point 5 are near the grain boundary. The EDX spectrum and quantitative results for point 1 were taken as a position away from the crystal grain, i.e., inside the crystal grain. Figure 26, point 2 in Figure 27, point 3 in Figure 28, point 4 in Figure 29, poi nt5 is shown in Figure 30. In Figures 26 to 30, the horizontal axis represents the characteristic X-ray energy (Ene The vertical axis shows the characteristic X-ray intensity [Counts].

[0317] At points 1 to 5, carbon (C), oxygen (O), fluorine (F), magnesium Mg, Si, P, S, Ca, Manganese (Mn), cobalt (Co), nickel (Ni), electron transition to each K shell The obtained spectrum was separated into each element, and the atomic concentration was calculated. I got a degree.

[0318] Next, we will explain EDX area analysis. Measurements are performed while scanning the area, and the area is analyzed in two dimensions. In this example, the EDX measurement is performed on the area It was done with 256 vertical points and 256 horizontal points.

[0319] FIG. 31(A) shows an HAADF-STEM image of the area of ​​sample A where EDX area analysis was performed. The EDX area analysis was performed in the region including the crystal grains and the crystal grain boundaries. In the EDX area analysis, the carbon mapping image is shown in Figure 31(B), the oxygen mapping image is shown in Figure 31(C), Fluorine is shown in Figure 31(D), magnesium in Figure 31(E), silicon in Figure 31(F), and phosphorus in Figure 31(G). Figure 32(A), sulfur Figure 32(B), calcium Figure 32(C), manganese Figure 32(D) ), cobalt is shown in Figure 32(E), and nickel is shown in Figure 32(F).

[0320] 31(B) to 31(F) and 32(A) to 32(F) show the characteristics obtained by EDX measurement. The map shows the characteristic X-ray intensity, with measurement points with low characteristic X-ray intensity shown in light color (white) and Measurement points with higher X-ray intensity are shown in darker (black) colors. In other words, measurement points with lighter (white) colors are shown in darker (black) colors. The dark (black) measurement points indicate a low atomic concentration, while the dark (black) measurement points indicate a high atomic concentration. 1(B) to 31(F) and 32(A) to 32(F) make it easier to understand the distribution within the region. To make this possible, the scale of the characteristic X-ray intensity is changed for each element.

[0321] As shown in Figures 31(B) to 31(F) and Figures 32(A) to 32(F), the grain boundaries In and around the area, the concentrations of fluorine, magnesium, silicon and calcium are high. It was confirmed that silicon and calcium were contained in the reagents used as raw materials. It is believed that there were

[0322] EDX area analysis shown in Figs. 31(B) to 31(F) and Figs. 32(A) to 32(F) The data of the linear region is extracted from the data, and the distribution of atomic concentration within the positive electrode active material particles is evaluated. In this way, one-dimensional evaluation of a linear region is sometimes called line analysis.

[0323] FIG. 33(A) shows an HAADF-STEM image of the area of ​​sample A where EDX line analysis was performed. In Figure 33(A), the area where EDX line analysis was performed is indicated by an arrow. The analysis was carried out in the crystal grains, the grain boundaries, and the regions spanning the crystal grains.

[0324] The carbon atom concentration in the EDX line analysis of the region shown in FIG. 33(A) is shown in FIG. 34(A). Oxygen is shown in Figure 34(B), fluorine in Figure 34(C), magnesium in Figure 34(D), and silicon in Figure 34(E). Figure 34(E), Phosphorus Figure 34(F), Sulfur Figure 35(A), Calcium Figure 35(B), Manganese is shown in Figure 35(C), cobalt in Figure 35(D), and nickel in Figure 35(E).

[0325] In Figures 34(A) to 34(F) and Figures 35(A) to 35(E), the horizontal axis represents distance ( The vertical axis shows the atomic concentration [atomic %]. The distance is measured from the black circle at one end of the arrow shown in FIG. 34(A) as the starting point (distance = 0 nm) to the other end. The vertical axis shows the atomic concentration of carbon, oxygen, and , fluorine, magnesium, silicon, phosphorus, sulfur, calcium, manganese, cobalt and The number of atoms of each element when the total number of nickel atoms is 100 atomic % The ratio of

[0326] As shown in Figures 33(A), 34(A) to 34(F), and 35(A) to 35(E), As shown, compared with the grain region, the grain boundary and its vicinity are rich in fluorine, magnesium, and silicon. It was also confirmed that the concentrations of ammonium and calcium were high at the grain boundaries and their vicinity. It was found that the vicinity had a region with a width of 1 nm or more and 10 nm or less.

[0327] It was confirmed that the grain boundaries and their vicinity contained oxygen, magnesium, and fluorine. It was found that the grain boundaries and their vicinity contained magnesium oxide. It is believed that some of the oxygen in the silicon is replaced by fluorine.

[0328] On the other hand, in the grain region, fluorine, magnesium, silicon and calcium were detected at the lower detection limit. It was Lu.

[0329] Phosphorus and sulfur were at the lower detection limit in both the grains and the grain boundaries.

[0330] Carbon was detected in the crystal grains and grain boundaries, but the carbon coating film was used as a protective film. The carbon concentration mentioned above is thought to include carbon originating from the carbon coating film. Therefore, the true carbon concentration of the grains and grain boundaries could not be determined.

[0331] Compared to the grains, the grain boundaries and their vicinity are dominated by transition metals such as manganese, cobalt, and nickel. It was confirmed that the atomic concentration of Kel was lower.

[0332] The total atomic concentration of the transition metals nickel, manganese, and cobalt is shown in Figure 35(F). In FIG. 35(F), the horizontal axis indicates distance (nm) and the vertical axis indicates nickel. Total atomic concentration of nickel, manganese and cobalt (Ni+Mn+Co) [atomic%] Specifically, the total atomic concentration of nickel, manganese and cobalt (Ni + Mn + Co ) is the total atomic concentration of nickel, manganese, and cobalt at each EDX measurement point. In sample A, the total atomic concentration of nickel, manganese, and cobalt (Ni+M (n + Co) can be said to be the atomic concentration of the transition metal. It was found that the atomic concentration of transition metals tends to be lower at and near the grain boundaries compared to the region. In addition, in the crystal grain region, there is no large variation in the atomic concentration of the transition metal, and it is approximately It was found to be uniform.

[0333] The ratio of the atomic concentration of magnesium (Mg) to the atomic concentration of transition metals in the grains is shown. In Fig. 36(A), the horizontal axis represents distance (nm). The vertical axis shows the ratio of the atomic concentration of magnesium to the atomic concentration of transition metals in the grains ( Mg / Tr-Metal) (arb. unit).

[0334] The atomic concentration of transition metals in the crystal grains (Tr-Metal) is explained. The atomic concentration of the transition metal in the grains (Tr-Metal) is Specifically, the average value of the concentration of magnesium (Mg) was used. The region was taken as the crystal grain region, and the average atomic concentration of the transition metal in that region was calculated. The area of ​​the crystal grain used in the calculation is indicated by an arrow in FIG. 35(F).

[0335] As shown in FIG. 36(A), the grain boundaries and their vicinity are characterized by the atomic concentration of the transition metal in the grains. The ratio of the atomic concentration of magnesium to the concentration of Tr (Mg / Tr-Metal) is 0.030 or more. It was found that magnesium segregates at and near the grain boundaries. It was found that the grain boundaries and their vicinity are thought to contain magnesium oxide. Sample A, which is one embodiment of the present invention, has magnesium oxide at and near the grain boundaries. The positive electrode active material particles become chemically and structurally stable, and the transition metals dissolve into the electrolyte. This can suppress the deterioration of the positive electrode active material, such as the desorption of the positive electrode group and the instability of the crystal structure. It is possible to prevent the positive electrode active material particles from cracking. It is also possible to prevent oxygen from being released from the positive electrode active material particles. By using such positive electrode active material particles, deterioration of the electricity storage device can be suppressed. In addition, a highly safe power storage device can be obtained. The amount of lithium contained in the positive electrode active material decreases, making it easier for the crystal structure of the positive electrode active material particles to change. Therefore, sample A is particularly preferable as positive electrode active material particles.

[0336] The atomic concentration of fluorine relative to the atomic concentration of transition metals (Tr-Metal) in the crystal grains The ratio is shown in Figure 36(B). In Figure 36(B), the horizontal axis is distance [n m], and the vertical axis represents the ratio of the atomic concentration of fluorine to the atomic concentration of transition metals in the crystal grains ( F / Tr-Metal).

[0337] As shown in FIG. 36(B), the grain boundaries and their vicinity are characterized by the atomic concentration of the transition metal in the grains. The ratio of fluorine atom concentration to fluorine concentration (F / Tr-Metal) is 0.030 or more. It was found that the presence of fluorine at and near the grain boundaries It was found that magnesium could be efficiently segregated in the vicinity of the layer.

[0338] In this specification, the term "atomic concentration ratio" and "atomic number ratio" are synonymous. The ratio of the number of atoms can be replaced with the ratio of the number of atoms. The value of is the ratio of the atomic concentration of magnesium to the atomic concentration of transition metals in the grains. , which is also the ratio of the number of magnesium atoms to the number of transition metal atoms in the grain. I can say.

[0339] The total atomic concentration of nickel, manganese, and cobalt (Ni+Mn+ The ratio of the atomic concentration of magnesium (Mg) to that of Co is shown in Figure 36(C). In C), the horizontal axis indicates the distance (nm) and the vertical axis indicates the EDX measurement point. The ratio of magnesium atoms to the total number of nickel, manganese, and cobalt atoms per The concentration ratio (Mg / (Ni+Mn+Co)) is shown.

[0340] The total atomic concentration of nickel, manganese, and cobalt (Ni+Mn+ Co) is the same as the data shown in Figure 35(F).

[0341] As shown in FIG. 36(C), the grain boundaries and their vicinity are composed of nickel and manganese in the grains. The ratio of the atomic concentration of magnesium to the total atomic concentration of nickel and cobalt (Mg / (Ni+ It was found that there is a region where the ratio of Mn to Co is 0.030 or more. It was found that magnesium was segregated in the vicinity.

[0342] The total atomic concentration of nickel, manganese, and cobalt (Ni+Mn+ The ratio of the atomic concentration of fluorine to that of Co is shown in FIG. 36(D). In FIG. 36(D), The horizontal axis shows the distance [nm], and the vertical axis shows the nickel , the ratio of the atomic concentration of fluorine to the total atomic concentration of manganese and cobalt (F / (Ni +Mn+Co).

[0343] As shown in FIG. 36(D), the grain boundaries and their vicinity are characterized by the atomic concentration of the transition metal in the grains. The ratio of fluorine atomic concentration to the concentration (F / (Ni+Mn+Co)) is 0.030 or more. It was found that the grain boundary and its vicinity have fluorine, which It was found that magnesium can be efficiently segregated in and around the area.

[0344] EDX measurement was similarly carried out on another portion of sample A.

[0345] FIG. 37(A) shows an HAADF-STEM image of the area of ​​sample A where EDX area analysis was performed. The EDX area analysis was performed in the area including the crystal grains and the crystal grain boundaries. In the EDX area analysis, the carbon mapping image is shown in Figure 37(B), the oxygen mapping image is shown in Figure 37(C), Fluorine is shown in Figure 37(D), magnesium in Figure 37(E), silicon in Figure 37(F), and phosphorus in Figure 37(G). Figure 38(A), sulfur Figure 38(B), calcium Figure 38(C), manganese Figure 38(D ), cobalt is shown in Figure 38(E), and nickel is shown in Figure 38(F).

[0346] 37(B) to 37(F) and 38(A) to 38(F) show the characteristics obtained by EDX measurement. The map shows the characteristic X-ray intensity, with measurement points with low characteristic X-ray intensity shown in light color (white) and Measurement points with higher X-ray intensity are shown in darker (black) colors. In other words, measurement points with lighter (white) colors are shown in darker (black) colors. The dark (black) measurement points indicate a low atomic concentration, while the dark (black) measurement points indicate a high atomic concentration. 7(B) to 37(F) and 38(A) to 38(F) show the distribution within the area more clearly. To make this possible, the scale of the characteristic X-ray intensity is changed for each element.

[0347] As shown in Figures 37(B) to 37(F) and Figures 38(A) to 38(F), the grain boundaries In and around the area, the concentrations of fluorine, magnesium, silicon and calcium are high. It was confirmed that silicon and calcium were contained in the reagents used as raw materials. It is believed that there were

[0348] EDX area analysis shown in Figures 37(B) to 37(F) and Figures 38(A) to 38(F) The data of the linear region is extracted from the data, and the distribution of atomic concentration within the positive electrode active material particles is evaluated. Ta.

[0349] FIG. 33(B) shows an HAADF-STEM image of the area of ​​sample A where EDX line analysis was performed. In Figure 33(B), the area where EDX line analysis was performed is indicated by an arrow. The analysis was carried out in the crystal grains, the grain boundaries, and the regions spanning the crystal grains.

[0350] The carbon atom concentration in the EDX line analysis of the region shown in FIG. 33(B) is shown in FIG. 39(A). Oxygen is shown in Figure 39(B), fluorine in Figure 39(C), magnesium in Figure 39(D), and silicon in Figure 39(E). Figure 39(E), Phosphorus Figure 39(F), Sulfur Figure 40(A), Calcium Figure 40(B), Manganese is shown in Figure 40(C), cobalt in Figure 40(D), and nickel in Figure 40(E).

[0351] In Figures 39(A) to 39(F) and Figures 40(A) to 40(E), the horizontal axis represents distance ( The vertical axis shows the atomic concentration [atomic %]. The distance is measured from the black circle at one end of the arrow shown in FIG. 33(B) as the starting point (distance = 0 nm) to the other end. The vertical axis shows the atomic concentration of carbon, oxygen, and , fluorine, magnesium, silicon, phosphorus, sulfur, calcium, manganese, cobalt and The number of atoms of each element when the total number of nickel atoms is 100 atomic % The ratio of

[0352] As shown in Figures 33(B), 39(A) to 39(F), and 40(A) to 40(E), As shown, compared with the grain region, the grain boundary and its vicinity are rich in fluorine, magnesium, and silicon. It was also confirmed that the concentrations of ammonium and calcium were high at the grain boundaries and their vicinity. It was found that the vicinity had a region with a width of 1 nm or more and 10 nm or less.

[0353] It was confirmed that the grain boundaries and their vicinity contained oxygen, magnesium, and fluorine. It was found that the grain boundaries and their vicinity contained magnesium oxide. It is believed that some of the oxygen in the silicon is replaced by fluorine.

[0354] On the other hand, in the grain region, fluorine, magnesium, silicon and calcium were detected at the lower detection limit. It was Lu.

[0355] Phosphorus and sulfur were at the lower detection limit in both the grains and the grain boundaries.

[0356] Carbon was detected in the crystal grains and grain boundaries, but the carbon coating film was used as a protective film. The carbon concentration mentioned above is thought to include carbon originating from the carbon coating film. Therefore, the true carbon concentration of the grains and grain boundaries could not be determined.

[0357] Compared to the grains, the grain boundaries and their vicinity are dominated by transition metals such as manganese, cobalt, and nickel. It was confirmed that the atomic concentration of Kel was lower.

[0358] The total atomic concentration of the transition metals nickel, manganese, and cobalt is shown in Figure 40(F). In FIG. 40(F), the horizontal axis indicates distance (nm) and the vertical axis indicates nickel. Total atomic concentration of nickel, manganese and cobalt (Ni+Mn+Co) [atomic%] In sample A, the total atomic concentration of nickel, manganese, and cobalt (Ni+M (n + Co) can be said to be the atomic concentration of the transition metal. It was found that the atomic concentration of transition metals tends to be lower at and near the grain boundaries compared to the region. In addition, in the crystal grain region, there is no large variation in the atomic concentration of the transition metal, and it is approximately It was found to be uniform.

[0359] The ratio of the atomic concentration of magnesium (Mg) to the atomic concentration of transition metals in the grains is shown. In FIG. 41(A), the horizontal axis represents distance (nm). The vertical axis shows the ratio of the atomic concentration of magnesium to the atomic concentration of transition metals in the grains ( Mg / Tr-Metal).

[0360] The atomic concentration of the transition metal in the grain (Tr-Metal) is The average atomic concentration of the metals was used. The area of ​​the crystal grains used to calculate the average value is shown in Figure 40(F). is indicated by an arrow.

[0361] As shown in FIG. 41(A), the grain boundaries and their vicinity are characterized by the atomic concentration of the transition metal in the grains. The ratio of the atomic concentration of magnesium to the concentration of Tr (Mg / Tr-Metal) is 0.030 or more. It was found that there are regions where magnesium is segregated at and near the grain boundaries. It was found that the grain boundaries and their vicinity are thought to contain magnesium oxide. Sample A, which is one embodiment of the present invention, has magnesium oxide at and near the grain boundaries. The positive electrode active material particles become chemically and structurally stable, and the transition metals dissolve into the electrolyte. This can suppress the deterioration of the positive electrode active material, such as detachment and instability of the crystal structure. It is possible to prevent cracking of the active material particles and also to prevent oxygen from being released from the positive electrode active material particles. By using such positive electrode active material particles, deterioration of the electricity storage device can be suppressed. When the charging voltage is increased, the positive electrode is charged. The amount of lithium contained in the positive electrode active material decreases, which makes it easier for the crystal structure of the positive electrode active material particles to change. For this reason, sample A is particularly preferable as the positive electrode active material particles.

[0362] The atomic concentration of fluorine relative to the atomic concentration of transition metals (Tr-Metal) in the crystal grains The ratio is shown in Figure 41(B). In Figure 41(B), the horizontal axis is distance [n m], and the vertical axis represents the ratio of the atomic concentration of fluorine to the atomic concentration of transition metals in the crystal grains ( F / Tr-Metal).

[0363] As shown in FIG. 41(B), the grain boundaries and their vicinity are characterized by the atomic concentration of the transition metal in the grains. The ratio of fluorine atom concentration to fluorine concentration (F / Tr-Metal) is 0.030 or more. It was found that the presence of fluorine at and near the grain boundaries It was found that magnesium could be efficiently segregated in the vicinity of the layer.

[0364] The total atomic concentration of nickel, manganese, and cobalt (Ni+Mn+ The ratio of the atomic concentration of magnesium (Mg) to that of Co is shown in Figure 41(C). In C), the horizontal axis indicates the distance (nm) and the vertical axis indicates the EDX measurement point. The ratio of magnesium atoms to the total number of nickel, manganese, and cobalt atoms per The concentration ratio (Mg / (Ni+Mn+Co)) is shown.

[0365] The total atomic concentration of nickel, manganese, and cobalt (Ni+Mn+ Co) is the same as the data shown in Figure 40(F).

[0366] As shown in FIG. 41(C), the grain boundaries and their vicinity are composed of nickel and manganese in the grains. The ratio of the atomic concentration of magnesium to the total atomic concentration of nickel and cobalt (Mg / (Ni+ It was found that there is a region where the ratio of Mn to Co is 0.030 or more. It was found that magnesium was segregated in the vicinity.

[0367] The total atomic concentration of nickel, manganese, and cobalt (Ni+Mn+ The ratio of the atomic concentration of fluorine to that of Co is shown in FIG. 41(D). In FIG. 41(D), The horizontal axis shows the distance [nm], and the vertical axis shows the nickel , the ratio of the atomic concentration of fluorine to the total atomic concentration of manganese and cobalt (F / (Ni +Mn+Co).

[0368] As shown in FIG. 41(D), the grain boundaries and their vicinity are characterized by the atomic concentration of the transition metal in the grains. The ratio of fluorine atomic concentration to the concentration (F / (Ni+Mn+Co)) is 0.030 or more. It was found that the grain boundary and its vicinity have fluorine, which It was found that magnesium can be efficiently segregated in and around the area.

[0369] From this example, it was found that adding magnesium and fluorine to the starting material of the positive electrode active material particles It has become clear that magnesium segregates at and near the grain boundaries of the positive electrode active material particles. The positive electrode active material particles according to one embodiment of the present invention have magnesium oxide at the grain boundaries and in the vicinity thereof. By having this, the positive electrode active material particles are chemically and structurally stable, and structural changes caused by charging and discharging are prevented. In other words, the crystal structure of the positive electrode active material particles becomes more stable. This prevents the crystal structure from changing even after repeated charge and discharge. This can prevent cracking, which means that deterioration such as a decrease in capacity can be prevented.

[0370] Since the power storage device containing such positive electrode active material particles is less susceptible to deterioration, it is suitable for portable electronic devices. Furthermore, if applied to automobiles and other vehicles, it will be possible to reduce commercial power consumption during peak power demand periods. This can help save energy and reduce carbon dioxide emissions. Furthermore, the power storage device can be highly safe. [Example]

[0371] In this example, a positive electrode active material having magnesium, fluorine, and oxygen at and near the grain boundaries The active material was prepared and subjected to TEM observation and STEM-EDX analysis to identify the crystal grains and crystallites in the active material. The concentration distribution at the grain boundaries was confirmed. The sample was one of sample B, which is one embodiment of the present invention. As material B, a cobalt oxide having magnesium, fluorine, and oxygen at and near the grain boundaries was used. The lithium cobalt oxide was prepared using the LiCoO2 composition. O2 has a layered rock salt type crystal structure.

[0372] <Preparation of Sample B> The preparation of sample B will be described.

[0373] As shown in step S11 of the flow in Figure 3, starting materials were prepared. Lithium oxide (Li2CO3), tricobalt tetroxide (Co3O4) as a cobalt source, magnesium Magnesium oxide (MgO) as the potassium source, lithium fluoride (LiF) as the fluorine source Specifically, 3.1489 g (42.62 mmol) of Li2CO3 and C 6.7726 g (28.13 mmol) of O3O4 and 0.0344 g (0.85 0.0442 g (1.70 mmol) of LiF was weighed out. The ratio m of the number of magnesium atoms to the number of atoms of magnesium is 0.010 (1.0%). In addition, the ratio of the number of fluorine atoms to the number of magnesium atoms, n, is 2.0. The Li2CO3 used was manufactured by Kojundo Chemical Laboratory Co., Ltd. (catalog number: LIH06XB). The MgO used was manufactured by Kojundo Chemical Laboratory Co., Ltd. (catalog number: MGO12PB). F was manufactured by Kojundo Chemical Laboratory Co., Ltd. (catalog number: LIH10XB).

[0374] Next, as shown in step S12, the starting materials weighed in step S11 were mixed. The details of the mixing can be found in the description of Sample A, so the explanation will be omitted.

[0375] Next, as shown in step S13, the material mixed in step S12 is subjected to a first heating. For details of the first heating, the description of sample A can be referred to, and therefore a detailed description will be omitted.

[0376] Next, as shown in step S14, the material heated in step S13 is cooled to room temperature, Synthetic Product 2 was obtained. After cooling, the obtained synthetic product 2 was subjected to a crushing treatment to reduce the particle size of synthetic product 2. A 53 μm mesh was used for the crushing treatment.

[0377] Next, as shown in step S15, the second heating was performed on the composite 2 obtained in step S14. Since the details of the second heating can be referred to the description of sample A, the description is omitted.

[0378] By performing the second heating in step S15, magnesium and fluorine contained in the starting materials can be promoted to segregate to the grain boundaries of lithium cobalt oxide.

[0379] Next, as shown in step S16, the composite 2 heated in step S15 was cooled to room temperature and recovered to obtain sample B.

[0380] <TEM Observation, STEM Observation, EDX Measurement> Next, sample B was thinned by focused ion beam (FIB), and the cross-section of sample B was observed by TEM and STEM. Also, the cross-section of sample B was subjected to compositional analysis by EDX measurement. Since the details of TEM, STEM observation and EDX measurement can be referred to the description of sample A, the description is omitted.

[0381] The TEM image (bright-field image) of the cross-section of sample B is shown in Fig. 42(A). The magnification of Fig. 42(A) is 10 times. In Fig. 42(A), the region where the density (brightness) of the TEM image is substantially uniform has a substantially constant crystal orientation and is considered to be a single crystal. Also, the region where the density (brightness) of the TEM image changes is considered to be a grain boundary. A schematic diagram corresponding to Fig. 42(A) is shown in Fig. 42(B). As shown in Fig. 42(A) and Fig. 42(B), it was confirmed that the positive electrode active material particles have a plurality of crystal grains 1201 and grain boundaries 1203 between the crystal grains.

[0382] The STEM image (bright-field image) of the cross-section of sample B is shown in Fig. 43(A), and the HAADF-STE at the same location The M image is shown in Figure 43(B). The magnification of Figures 43(A) and 43(B) is 8 million times. In Figures 43(A) and 43(B), crystal lattice images were observed in the crystal grain regions.

[0383] FIG. 44(A) shows an HAADF-STEM image of the area of ​​sample B where EDX area analysis was performed. The EDX area analysis was carried out in a region including crystal grains and crystal grain boundaries. Measurements were taken at 256 vertical and 256 horizontal points within the region.

[0384] Carbon, oxygen, fluorine, magnesium, silicon, phosphorus, sulfur, calcium, manganese, Peaks due to electron transitions to the K shells of barium and nickel were observed. The spectra were separated into individual elements to obtain their atomic concentrations.

[0385] The carbon mapping image in the EDX area analysis of the area shown in Figure 44(A) is shown in Figure 44(B). ), oxygen in Figure 44(C), fluorine in Figure 44(D), magnesium in Figure 44(E), silicon Figure 44(F) shows cations, Figure 45(A) shows phosphorus, Figure 45(B) shows sulfur, Figure 45(C) shows calcium. ), and cobalt is shown in Figure 45(D).

[0386] 44(B) to 44(F) and 45(A) to 45(D) show the characteristics obtained by EDX measurement. The map shows the characteristic X-ray intensity, with measurement points with low characteristic X-ray intensity shown in light color (white) and Measurement points with higher X-ray intensity are shown in darker (black) colors. In other words, measurement points with lighter (white) colors are shown in darker (black) colors. The dark (black) measurement points indicate a low atomic concentration, while the dark (black) measurement points indicate a high atomic concentration. 4(B) to 44(F) and 45(A) to 45(D) show the distribution within the area more clearly. To make this possible, the scale of the characteristic X-ray intensity is changed for each element.

[0387] As shown in Figures 44(B) to 44(F) and Figures 45(A) to 45(D), the grain boundaries It was confirmed that the concentrations of magnesium and calcium were high in and around the area. As for fluorine, it was hardly observed in the area where EDX analysis was performed. This is thought to be because fluorine, a light element, is difficult to detect using EDX. It is believed that the compound was contained in the reagents used as raw materials.

[0388] EDX area analysis shown in Figures 44(B) to 44(F) and Figures 45(A) to 45(D) The data of the linear region is extracted from the data, and the distribution of atomic concentration within the positive electrode active material particles is evaluated. Ta.

[0389] FIG. 46(A) shows an HAADF-STEM image of the area of ​​sample B where EDX line analysis was performed. In Figure 46(A), the area where EDX line analysis was performed is indicated by an arrow. The analysis was carried out in the crystal grains, the grain boundaries, and the regions spanning the crystal grains.

[0390] The carbon atom concentration in the EDX line analysis of the region shown in FIG. 46(A) is shown in FIG. 47(A). Oxygen is shown in Figure 47(B), fluorine in Figure 47(C), magnesium in Figure 47(D), and silicon in Figure 47(E). Figure 47(E), Phosphorus Figure 47(F), Sulfur Figure 48(A), Calcium Figure 48(B), Cobalt is shown in Figure 48(C).

[0391] In Figures 47(A) to 47(F) and Figures 48(A) to 48(C), the horizontal axis represents distance ( The vertical axis shows the atomic concentration [atomic %]. The distance is measured from the black circle at one end of the arrow shown in FIG. 46(A) as the starting point (distance = 0 nm) to the other end. The vertical axis shows the atomic concentration of carbon, oxygen, and , the total number of atoms of fluorine, magnesium, silicon, phosphorus, sulfur, calcium and cobalt The ratio of the number of atoms of each element is shown, assuming that the number of atoms is 100 atomic %.

[0392] As shown in Figures 46(A), 47(A) to 47(F), and 48(A) to 48(C), As shown, compared with the grain region, the grain boundaries and their vicinity are rich in magnesium and calcium. It was confirmed that the concentration was high. In addition, the grain boundaries and their vicinity were thicker than 1 nm in width. It was found that the region was 10 nm or less.

[0393] It was confirmed that the grain boundaries and their vicinity contained oxygen and magnesium. It was found that the surface and its vicinity contained magnesium oxide.

[0394] On the other hand, in the grain region, fluorine, magnesium, silicon and calcium were detected at the lower detection limit. It was Lu.

[0395] Phosphorus and sulfur were at the lower detection limit in both the grains and the grain boundaries.

[0396] Carbon was detected in the crystal grains and grain boundaries, but the carbon coating film was used as a protective film. The carbon concentration mentioned above is thought to include carbon originating from the carbon coating film. Therefore, the true carbon concentration of the grains and grain boundaries could not be determined.

[0397] Compared to the crystal grains, the grain boundaries and their vicinity have a lower atomic concentration of cobalt, a transition metal. We were able to confirm that this was the case.

[0398] In sample B, the atomic concentration of cobalt can also be considered as the atomic concentration of transition metals. (Figure 48(C)) As shown in Fig. 1, the atomic concentration of transition metals at and near the grain boundaries is higher than that in the grain regions. In addition, in the grain region, the atomic concentration of the transition metals is low. It was found that there was no large variation and the results were almost uniform.

[0399] The ratio of the atomic concentration of magnesium (Mg) to the atomic concentration of transition metals in the grains is shown. In Fig. 49(A), the horizontal axis represents distance (nm). The vertical axis shows the ratio of the atomic concentration of magnesium to the atomic concentration of transition metals in the grains ( Mg / Tr-Metal).

[0400] The atomic concentration of the transition metal in the grain (Tr-Metal) is The average value of the atomic concentration of the metals was used. The area of ​​the crystal grains used to calculate the average value is shown in Figure 48(D). is indicated by an arrow.

[0401] As shown in FIG. 49(A), the grain boundaries and their vicinity are characterized by the atomic concentration of the transition metal in the grains. The ratio of the atomic concentration of magnesium to the concentration of Tr (Mg / Tr-Metal) is 0.030 or more. It was found that there are regions where magnesium is segregated at and near the grain boundaries. It was found that the grain boundaries and their vicinity are thought to contain magnesium oxide. Sample B, which is one embodiment of the present invention, has magnesium oxide at and near the grain boundaries. The positive electrode active material particles become chemically and structurally stable, and the transition metals dissolve into the electrolyte. This can suppress the deterioration of the positive electrode active material, such as detachment and instability of the crystal structure. It is possible to prevent cracking of the active material particles and also to prevent oxygen from being released from the positive electrode active material particles. By using such positive electrode active material particles, deterioration of the electricity storage device can be suppressed. When the charging voltage is increased, the positive electrode is charged. The amount of lithium contained in the positive electrode active material decreases, which makes it easier for the crystal structure of the positive electrode active material particles to change. For this reason, sample B is particularly preferable as the positive electrode active material particles.

[0402] The atomic concentration of fluorine relative to the atomic concentration of transition metals (Tr-Metal) in the crystal grains The ratio is shown in Figure 49(B). In Figure 49(B), the horizontal axis is distance [n m], and the vertical axis represents the ratio of the atomic concentration of fluorine to the atomic concentration of transition metals in the crystal grains ( F / Tr-Metal).

[0403] As shown in Figures 47(C) and 49(B), in sample B, the grains and grain boundaries The fluorine concentration was below the detection limit. Fluorine is a light element and is difficult to detect with EDX. It is thought that

[0404] The atomic concentration of magnesium (Mg) relative to the atomic concentration of cobalt (Co) at each EDX measurement point The ratio of the molecular concentrations is shown in Figure 49(C). In Figure 49(C), the horizontal axis is the distance (Distance e) [nm], and the vertical axis shows the ratio of the atomic concentration of cobalt to the atomic concentration of magnetite at each EDX measurement point. The ratio of the atomic concentrations of Mg and Co is shown.

[0405] As shown in Figure 49(C), the grain boundaries and their vicinity are characterized by the cobalt atomic concentration in the grains. The ratio of the atomic concentration of magnesium to the concentration of Co (Mg / Co) is 0.030 or more. It was found that magnesium was segregated at and near the grain boundaries. It was.

[0406] The ratio of the atomic concentration of fluorine to the atomic concentration of cobalt (Co) at each EDX measurement point is shown. In Fig. 49(D), the horizontal axis represents distance (nm). The vertical axis shows the ratio of the atomic concentration of fluorine to the atomic concentration of cobalt at each EDX measurement point. In sample B, the fluorine concentration in the grains and grain boundaries was below the detection limit. It was below.

[0407] Similarly, EDX measurement was carried out on another portion of sample B.

[0408] FIG. 50(A) shows an HAADF-STEM image of the area of ​​sample B where EDX area analysis was performed. The EDX area analysis was performed in the area including the crystal grains and the crystal grain boundaries. In the EDX area analysis, the carbon mapping image is shown in Figure 50(B), the oxygen mapping image is shown in Figure 50(C), Fluorine is shown in Figure 50(D), magnesium in Figure 50(E), silicon in Figure 50(F), and phosphorus in Figure 50(G). Figure 51(A), sulfur Figure 51(B), calcium Figure 51(C), cobalt Figure 51(D) ) shown.

[0409] 50(B) to 50(F) and 51(A) to 51(D) show the characteristics obtained by EDX measurement. The map shows the characteristic X-ray intensity, with measurement points with low characteristic X-ray intensity shown in light color (white) and Measurement points with higher X-ray intensity are shown in darker (black) colors. In other words, measurement points with lighter (white) colors are shown in darker (black) colors. The dark (black) measurement points indicate a low atomic concentration, while the dark (black) measurement points indicate a high atomic concentration. 50(B) to 50(F) and 51(A) to 51(D) make it easier to understand the distribution within the area. To make this possible, the scale of the characteristic X-ray intensity is changed for each element.

[0410] As shown in Figures 50(B) to 50(F) and Figures 51(A) to 51(D), the grain boundaries It was confirmed that the concentrations of magnesium and calcium were high in and around the area. As for fluorine, it was hardly observed in the area where EDX analysis was performed. This is thought to be because fluorine, a light element, is difficult to detect using EDX. It is believed that the compound was contained in the reagents used as raw materials.

[0411] EDX area analysis shown in Figures 50(B) to 50(F) and Figures 51(A) to 51(D) The data of the linear region is extracted from the data, and the distribution of atomic concentration within the positive electrode active material particles is evaluated. Ta.

[0412] FIG. 46(B) shows an HAADF-STEM image of the area of ​​sample B where EDX line analysis was performed. In Figure 46(B), the area where EDX line analysis was performed is indicated by an arrow. The analysis was carried out in the crystal grains, the grain boundaries, and the regions spanning the crystal grains.

[0413] The carbon atom concentration in the EDX line analysis of the region shown in Figure 46(B) is shown in Figure 52(A). Oxygen is shown in Figure 52(B), fluorine in Figure 52(C), magnesium in Figure 52(D), and silicon in Figure 52(E). Figure 52(E), Phosphorus Figure 52(F), Sulfur Figure 53(A), Calcium Figure 53(B), Cobalt is shown in Figure 53(C).

[0414] In Figures 52(A) to 52(F) and Figures 53(A) to 53(C), the horizontal axis represents distance ( The vertical axis shows the atomic concentration [atomic %]. The distance is measured from the black circle at one end of the arrow shown in FIG. 46(B) as the starting point (distance = 0 nm) to the other end. The vertical axis shows the atomic concentration of carbon, oxygen, and , the total number of atoms of fluorine, magnesium, silicon, phosphorus, sulfur, calcium and cobalt The ratio of the number of atoms of each element is shown, assuming that the number of atoms is 100 atomic %.

[0415] As shown in Figure 46(B), Figures 52(A) to 52(F), and Figures 53(A) to 53(C), As shown, the concentration of magnesium is higher at and near the grain boundaries compared to the grain regions. It was also confirmed that the grain boundaries and their vicinity had widths of 1 nm to 10 nm. It was found that the region is

[0416] It was confirmed that the grain boundaries and their vicinity contained oxygen and magnesium. It was found that the surface and its vicinity contained magnesium oxide.

[0417] On the other hand, in the grain region, fluorine, magnesium, silicon and calcium were detected at the lower detection limit. It was Lu.

[0418] Phosphorus and sulfur were at the lower detection limit in both the grains and the grain boundaries.

[0419] Carbon was detected in the crystal grains and grain boundaries, but the carbon coating film was used as a protective film. The carbon concentration mentioned above is thought to include carbon originating from the carbon coating film. Therefore, the true carbon concentration of the grains and grain boundaries could not be determined.

[0420] Compared to the crystal grains, the grain boundaries and their vicinity have a lower atomic concentration of cobalt, a transition metal. We were able to confirm that this was the case.

[0421] In sample B, the atomic concentration of cobalt can also be considered the atomic concentration of transition metals. (Figure 53(C)) As shown in Fig. 1, the atomic concentration of transition metals at and near the grain boundaries is higher than that in the grain regions. In addition, in the grain region, the atomic concentration of the transition metals is low. It was found that there was no large variation and the results were almost uniform.

[0422] The ratio of the atomic concentration of magnesium (Mg) to the atomic concentration of transition metals in the grains is shown. In Fig. 54(A), the horizontal axis represents distance (nm). The vertical axis shows the ratio of the atomic concentration of magnesium to the atomic concentration of transition metals in the grains ( Mg / Tr-Metal).

[0423] The atomic concentration of the transition metal in the grain (Tr-Metal) is The average value of the atomic concentration of the metal was used. The area of ​​the crystal grain used to calculate the average value is shown in Figure 53(D). is indicated by an arrow.

[0424] As shown in FIG. 54(A), the grain boundaries and their vicinity are characterized by the atomic concentration of the transition metal in the grains. The ratio of the atomic concentration of magnesium to the concentration of Tr (Mg / Tr-Metal) is 0.030 or more. It was found that there are regions where magnesium is segregated at and near the grain boundaries. It was found that the grain boundaries and their vicinity are thought to contain magnesium oxide. Sample B, which is one embodiment of the present invention, has magnesium oxide at and near the grain boundaries. The positive electrode active material particles become chemically and structurally stable, and the transition metals dissolve into the electrolyte. This can suppress the deterioration of the positive electrode active material, such as detachment and instability of the crystal structure. It is possible to prevent cracking of the active material particles and also to prevent oxygen from being released from the positive electrode active material particles. By using such positive electrode active material particles, deterioration of the electricity storage device can be suppressed. When the charging voltage is increased, the positive electrode active material particles Since the crystal structure of the positive electrode active material particles is easily transformed, sample B is particularly preferable. .

[0425] The atomic concentration of fluorine relative to the atomic concentration of transition metals (Tr-Metal) in the crystal grains The ratio is shown in Figure 54(B). In Figure 54(B), the horizontal axis is distance [n m], and the vertical axis represents the ratio of the atomic concentration of fluorine to the atomic concentration of transition metals in the crystal grains ( F / Tr-Metal).

[0426] As shown in Figures 52(C) and 54(B), in sample B, the grains and grain boundaries The fluorine concentration was below the detection limit. Fluorine is a light element and is difficult to detect with EDX. It is thought that

[0427] The atomic concentration of magnesium (Mg) relative to the atomic concentration of cobalt (Co) at each EDX measurement point The ratio of the molecular concentrations is shown in Figure 54(C). In Figure 54(C), the horizontal axis is distance (Distance e) [nm], and the vertical axis shows the ratio of the atomic concentration of cobalt to the atomic concentration of magnetite at each EDX measurement point. The ratio of the atomic concentrations of Mg and Co is shown.

[0428] As shown in Figure 54(C), the grain boundaries and their vicinity are characterized by the cobalt atomic concentration in the grains. The ratio of the atomic concentration of magnesium to the concentration of Co (Mg / Co) is 0.030 or more. It was found that magnesium was segregated at and near the grain boundaries. It was.

[0429] The ratio of the atomic concentration of fluorine to the atomic concentration of cobalt (Co) at each EDX measurement point is shown. In Fig. 54(D), the horizontal axis represents distance (nm). The vertical axis shows the ratio of the atomic concentration of fluorine to the atomic concentration of cobalt at each EDX measurement point. In sample B, the fluorine concentration in the grains and grain boundaries was below the detection limit. It was below. [Explanation of symbols]

[0430] 100: Positive electrode active material particle, 101: Crystal grain, 103: Crystal grain boundary, 105: Crystal defect, 10 7: region, 200: active material layer, 201: graphene compound, 211a: positive electrode, 211b: Negative electrode, 212a: lead, 212b: lead, 214: separator, 215a: joint, 215b: Joint, 217: Fixing member, 250: Battery, 251: Exterior body, 261: Bending ridge, 262: seal, 263: seal, 271: ridge, 272: valley, 273: sky Between the battery 300 and the cathode can 301, the anode can 302, the gasket 303, and the cathode can 304. : positive electrode, 305: positive electrode current collector, 306: positive electrode active material layer, 307: negative electrode, 308: negative electrode current collector body, 309: negative electrode active material layer, 310: separator, 500: secondary battery, 501: positive electrode current collector body, 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: exterior body, 510: positive electrode Lead electrode, 511: negative electrode lead electrode, 600: secondary battery, 601: positive electrode cap, 60 2: Battery can, 603: Positive electrode terminal, 604: Positive electrode, 605: Separator, 606: Negative electrode, 6 07: Negative terminal, 608: Insulating plate, 609: Insulating plate, 611: PTC element, 612: Safety Valve mechanism, 900: circuit board, 910: label, 911: terminal, 912: circuit, 913: Next battery, 914: antenna, 915: antenna, 916: layer, 917: layer, 918: Tena, 919: terminal, 920: display device, 921: sensor, 922: terminal, 930: housing , 930a: housing, 930b: housing, 931: negative electrode, 932: positive electrode, 933: separator , 950: Winding body, 951: Terminal, 952: Terminal, 980: Secondary battery, 993: Winding body, 994: negative electrode, 995: positive electrode, 996: separator, 997: lead electrode, 998: lead electrode, 1101: crystal grain, 1103: crystal grain boundary, 1201: crystal grain, 1203: crystal grain World, 7100: Portable display device, 7101: Housing, 7102: Display unit, 7103: Operation button 7104: Secondary battery, 7200: Portable information terminal, 7201: Housing, 7202: Display unit , 7203: Band, 7204: Buckle, 7205: Operation button, 7206: Input / output terminal Child, 7207: Icon, 7300: Display device, 7304: Display unit, 7400: Mobile phone 7401: Housing, 7402: Display, 7403: Operation buttons, 7404: External connection port 7405: Speaker, 7406: Microphone, 7407: Secondary battery, 8000: Display 8001: housing, 8002: display unit, 8003: speaker unit, 8004: secondary battery, 8021: charging device, 8022: cable, 8024: secondary battery, 8100: lighting device, 8101: Housing, 8102: Light source, 8103: Secondary battery, 8104: Ceiling, 8105: Side Wall, 8106: Floor, 8107: Window, 8200: Indoor unit, 8201: Housing, 8202: Ventilation Mouth, 8203: Secondary battery, 8204: Outdoor unit, 8300: Electric refrigerator-freezer, 8301: Case Body, 8302: Refrigerator door, 8303: Freezer door, 8304: Secondary battery, 8400: Electric vehicles, 8401: Headlights, 8406: Electric motors, 8500: Automobiles, 8600 : Scooter, 8601: Side mirror, 8602: Secondary battery, 8603: Turn signal light, 8 604: Under-seat storage, 9600: Tablet terminal, 9625: Switch, 9626: Switch, 9627: Power switch, 9628: Operation switch, 9629: Fastener, 963 0: Housing, 9630a: Housing, 9630b: Housing, 9631: Display, 9633: Solar cell 9634: Charge and discharge control circuit, 9635: Power storage body, 9636: DC-DC converter, 9 637: Converter, 9640: Moving part

Claims

1. A lithium ion secondary battery including positive electrode active material particles, a region containing carbon, a positive electrode current collector, and an electrolyte solution, the positive electrode active material particles contain lithium cobalt oxide, The lithium cobalt oxide has a layered rock salt crystal structure, the positive electrode active material particles have a plurality of crystal grains and crystal defects, the positive electrode active material particles have a region containing aluminum in at least one crystal grain among the plurality of crystal grains, When a cross section of the positive electrode active material particle is subjected to EDX measurement and a grain boundary between any two adjacent crystal grains among the plurality of crystal grains and a region in the vicinity of the grain boundary are evaluated by line analysis, The grain boundary and the region near the grain boundary are the crystal grains have a region containing magnesium and oxygen, the region having a higher atomic concentration of magnesium than the interior of the two crystal grains, and the ratio of the atomic concentration of magnesium to the atomic concentration of cobalt at each EDX measurement point is 0.030 or more; the crystal defect and a region in the vicinity of the crystal defect have a region having a higher magnesium atomic concentration than an inside of at least one crystal grain among the plurality of crystal grains, a portion of the positive electrode active material particles is in contact with the region containing the carbon, The region containing carbon has a function of increasing the electrical conductivity between the positive electrode active material particles and the positive electrode current collector.

2. A lithium ion secondary battery including positive electrode active material particles, a region containing carbon, a positive electrode current collector, and an electrolyte solution, the positive electrode active material particles contain lithium cobalt oxide, The lithium cobalt oxide has a layered rock salt crystal structure, the positive electrode active material particles have a plurality of crystal grains, a surface layer portion of the positive electrode active material particle contains magnesium and fluorine, the positive electrode active material particles have a region containing aluminum in at least one crystal grain among the plurality of crystal grains, When a cross section of the positive electrode active material particle is subjected to EDX measurement and a grain boundary between any two adjacent crystal grains among the plurality of crystal grains and a region in the vicinity of the grain boundary are evaluated by line analysis, The grain boundary and the region near the grain boundary are the crystal grains have a region containing magnesium and oxygen, the region having a higher atomic concentration of magnesium than the interior of the two crystal grains, and the ratio of the atomic concentration of magnesium to the atomic concentration of cobalt at each EDX measurement point is 0.030 or more; a portion of the positive electrode active material particles is in contact with the region containing the carbon, The region containing carbon has a function of increasing the electrical conductivity between the positive electrode active material particles and the positive electrode current collector.

3. A lithium ion secondary battery including positive electrode active material particles, a positive electrode current collector, and an electrolyte solution, the positive electrode active material particles contain lithium cobalt oxide, The lithium cobalt oxide has a layered rock salt crystal structure, the positive electrode active material particles have a plurality of crystal grains and crystal defects, the positive electrode active material particles have a region containing aluminum in at least one crystal grain among the plurality of crystal grains, When a cross section of the positive electrode active material particle is subjected to EDX measurement and a grain boundary between any two adjacent crystal grains among the plurality of crystal grains and a region in the vicinity of the grain boundary are evaluated by line analysis, The grain boundary and the region near the grain boundary are the crystal grains have a region containing magnesium and oxygen, the region having a higher atomic concentration of magnesium than the interior of the two crystal grains, and the ratio of the atomic concentration of magnesium to the atomic concentration of cobalt at each EDX measurement point is 0.030 or more; The lithium ion secondary battery, wherein the crystal defect and a region in the vicinity of the crystal defect have a region having a higher magnesium atomic concentration than an interior of at least one of the plurality of crystal grains.

4. A lithium ion secondary battery including positive electrode active material particles, a positive electrode current collector, and an electrolyte solution, the positive electrode active material particles contain lithium cobalt oxide, The lithium cobalt oxide has a layered rock salt crystal structure, the positive electrode active material particles have a plurality of crystal grains, a surface layer portion of the positive electrode active material particle contains magnesium and fluorine, the positive electrode active material particles have a region containing aluminum in at least one crystal grain among the plurality of crystal grains, When a cross section of the positive electrode active material particle is subjected to EDX measurement and a grain boundary between any two adjacent crystal grains among the plurality of crystal grains and a region in the vicinity of the grain boundary are evaluated by line analysis, The grain boundary and the region near the grain boundary are A lithium ion secondary battery comprising magnesium and oxygen, the atomic concentration of magnesium being higher than that inside the two crystal grains, and having a region in which the ratio of the atomic concentration of magnesium to the atomic concentration of cobalt at each EDX measurement point is 0.030 or more.

5. A lithium ion secondary battery including positive electrode active material particles, a positive electrode current collector, and an electrolyte solution, the positive electrode active material particles contain lithium cobalt oxide, The lithium cobalt oxide has a layered rock salt crystal structure, the positive electrode active material particles have a plurality of crystal grains and crystal defects, a surface layer portion of the positive electrode active material particle contains magnesium and fluorine, the positive electrode active material particles have a region containing aluminum in at least one crystal grain among the plurality of crystal grains, When a cross section of the positive electrode active material particle is subjected to EDX measurement and a grain boundary between any two adjacent crystal grains among the plurality of crystal grains and a region in the vicinity of the grain boundary are evaluated by line analysis, The grain boundary and the region near the grain boundary are the crystal grains have a region containing magnesium and oxygen, the region having a higher atomic concentration of magnesium than the interior of the two crystal grains, and the ratio of the atomic concentration of magnesium to the atomic concentration of cobalt at each EDX measurement point is 0.030 or more; the crystal defect and a region in the vicinity of the crystal defect have a region having a higher magnesium atomic concentration than an inside of at least one crystal grain among the plurality of crystal grains, a portion of the positive electrode active material particles is in contact with a coating having a decomposition product of the electrolyte solution; The coating has a function of suppressing excessive reaction with the electrolyte solution.

6. In any one of claims 1 to 5, When a cross section of the positive electrode active material particle is subjected to EDX measurement and a grain boundary between any two adjacent crystal grains among the plurality of crystal grains and a region in the vicinity of the grain boundary are evaluated by line analysis, The grain boundary and the region near the grain boundary are a lithium ion secondary battery having a region in which the ratio of the atomic concentration of fluorine to the atomic concentration of cobalt within the two crystal grains is 0.020 or more and 1.00 or less;

7. In claim 1 or 3, The lithium ion secondary battery comprises a surface layer portion of the positive electrode active material particles containing magnesium and fluorine.

8. In claim 1 or 2, The lithium ion secondary battery includes a graphene compound carbon.

9. In any one of claims 5, The coating is a lithium ion secondary battery containing lithium.

10. In any one of claims 1 to 9, The lithium ion secondary battery contains vinylene carbonate as an electrolyte.

11. In any one of claims 1 to 10, In the lithium ion secondary battery, the grain boundary and the region in the vicinity of the grain boundary are regions of 1 nm to 10 nm across the grain boundary.

12. In any one of claims 1 to 11, When a cross section of the positive electrode active material particle is subjected to EDX measurement and a grain boundary between any two adjacent crystal grains among the plurality of crystal grains and a region in the vicinity of the grain boundary are evaluated by line analysis, The grain boundary and the region near the grain boundary are A lithium ion secondary battery having a region in which one or more elements selected from silicon and calcium are detected above the lower detection limit.

13. In any one of claims 1 to 12, When a cross section of the positive electrode active material particle is subjected to EDX measurement and a grain boundary between any two adjacent crystal grains among the plurality of crystal grains and a region in the vicinity of the grain boundary are evaluated by line analysis, The grain boundary and the region near the grain boundary are A lithium ion secondary battery having a region where the atomic concentration of silicon is higher than that inside the two crystal grains.

14. In any one of claims 1 to 13, When a cross section of the positive electrode active material particle is subjected to EDX measurement and a grain boundary between any two adjacent crystal grains among the plurality of crystal grains and a region in the vicinity of the grain boundary are evaluated by line analysis, The grain boundary and the region near the grain boundary are A lithium ion secondary battery having a region where the atomic concentration of calcium is higher than that inside the two crystal grains.

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