Lithium-ion rechargeable battery

Abstract

To provide a positive electrode active material that is used for a lithium ion secondary battery to suppress the decrease in capacity in a charging and discharging cycle.SOLUTION: In a surface layer part of a positive electrode active material, a coating layer is formed by segregation. The positive electrode active material includes a first region and a second region. The first region exists internally. The second region exists in a part of the surface layer part and the inside. The first region contains lithium, transition metal, and oxygen. The second region contains magnesium, fluorine, and oxygen.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to a product, a method, or a method of manufacture. Alternatively, the present invention relates to a process. This relates to machines, manufacturers, or compositions of matter. One aspect of the present invention relates to semiconductor devices, display devices, light-emitting devices, energy storage devices, lighting devices, or electronic devices. This relates to a method for manufacturing a device. In particular, to a positive electrode active material that can be used in a secondary battery, a secondary battery, and This relates to electronic devices that have a secondary battery.

[0002] In this specification, the term "energy storage device" refers to all elements and devices that have an energy storage function. For example, lithium-ion secondary batteries and other rechargeable batteries (also called secondary batteries) This includes muon capacitors and electric double-layer capacitors.

[0003] Furthermore, in this specification, "electronic equipment" refers to all devices that have an energy storage device, and the energy storage device is All electronic devices, including electro-optical devices and information terminal devices with energy storage systems, are considered electronic equipment. [Background technology]

[0004] In recent years, various energy storage devices such as lithium-ion secondary batteries, lithium-ion capacitors, and air batteries have been developed. Development of new devices is actively underway. In particular, high-power, high-capacity lithium-ion secondary batteries are being developed. Mobile phones, smartphones, or other portable information devices such as laptop computers, and portable music players. Players, digital cameras, medical equipment, or hybrid electric vehicles (HEVs), electric vehicles ( Next-generation clean energy such as EVs or plug-in hybrid vehicles (PHEVs) The demand for rechargeable energy is rapidly expanding, along with the development of the semiconductor industry, including the automotive sector. It has become an essential part of the modern information society as a source.

[0005] The characteristics currently required for lithium-ion secondary batteries include further increased capacity, improved cycle characteristics, improved safety in various operating environments, and improved long-term reliability.

[0006] One method of increasing the capacity of a lithium-ion secondary battery is known to be to increase the charging voltage. For example, the capacity of lithium cobaltate, which is often used as the positive electrode active material of a lithium-ion secondary battery, is generally 155 mAh / g when the charging voltage is 4.3 V, but when the charging voltage is increased to 4.6 V, it becomes 220 mAh / g (see Fig. 21(A)).

[0007] However, it is also known that increasing the charging voltage deteriorates the cycle characteristics. For example, general lithium cobaltate has a capacity retention rate of 95% or more after 30 cycles when the charging voltage is 4.4 V, but when the charging voltage is increased to 4.6 V, the capacity retention rate after 30 cycles drops to 50% or less (see Fig. 21(B)).

[0008] Therefore, in order to improve the cycle characteristics and increase the capacity of lithium-ion secondary batteries, improvement of the positive electrode active material has been studied (Patent Documents 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0009] <00,00095>

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] Thus, lithium-ion secondary batteries and the positive electrode active materials used therein have different capacities and sizes. There is still room for improvement in various aspects such as coolant characteristics, charge / discharge characteristics, reliability, safety, and cost. It is being done.

[0011] One aspect of the present invention, when used in a lithium-ion secondary battery, allows for a high capacity in charge-discharge cycles. One of the objectives of this invention is to provide a positive electrode active material in which the decrease in quantity is suppressed. One aspect of this invention aims to provide a high-capacity secondary battery. Alternatively, one aspect of this invention is One of the objectives is to provide a secondary battery with excellent charge and discharge characteristics. Or, an embodiment of the present invention. One of the objectives of this project is to provide safe and reliable secondary batteries.

[0012] Alternatively, one aspect of the present invention provides novel materials, active materials, energy storage devices, or methods for producing them. One of the objectives is to provide it.

[0013] Furthermore, the description of these problems does not preclude the existence of other problems. The embodiments do not need to solve all of these problems. It is possible to extract other issues from the description of the requested terms. [Means for solving the problem]

[0014] To achieve the above objective, one aspect of the present invention involves the surface layer of the positive electrode active material being subjected to segregation. It is characterized by forming a covering layer.

[0015] One aspect of the present invention is a positive electrode active material, wherein the positive electrode active material comprises a first region and a second region. The first region is located inside the positive electrode active material, and the second region is located on the surface of the positive electrode active material. And present in part of the interior, the first region has lithium, a transition metal, and oxygen, and the second The region in question is a positive electrode active material containing magnesium, fluorine, and oxygen.

[0016] Furthermore, one aspect of the present invention is a positive electrode active material, wherein the positive electrode active material comprises lithium and a transition metal. It contains oxygen, magnesium, and fluorine, and is present on the surface of the positive electrode active material, and X-ray photoelectrons Atoms including lithium, transition metals, oxygen, fluorine, and magnesium, measured by spectroscopy. Assuming a total amount of 100 atomic%, it is present on the surface of the positive electrode active material and measured by X-ray photoelectron spectroscopy. The magnesium concentration is between 1 atomic% and 16 atomic%, and fluorine This is a positive electrode active material with a concentration of 0.2 atomic% or more and 4 atomic% or less.

[0017] Furthermore, one aspect of the present invention is a positive electrode active material, wherein the positive electrode active material comprises lithium and a transition metal. A positive electrode active material having oxygen, magnesium, and fluorine, which is measured by X-ray photoelectron spectroscopy. The ratio of magnesium concentration to fluorine concentration on the surface is Mg:F=y:1 (3≦y≦5). It is the positive electrode active material.

[0018] Furthermore, one aspect of the present invention is a positive electrode active material, wherein the positive electrode active material comprises lithium and a transition metal. A positive electrode active material having oxygen, magnesium, and fluorine, which is measured by X-ray photoelectron spectroscopy. The peak position of the fluorine bond energy on the surface is between 682 eV and 685 eV. It is the positive electrode active material.

[0019] Furthermore, in the above, the transition metal preferably contains cobalt. Or, in the above, The transition metals preferably include manganese, cobalt, and nickel.

[0020] Furthermore, one aspect of the present invention is a positive electrode active material, wherein the positive electrode active material comprises a first region and a second region It has a region, the first region is located inside, and contains lithium, a transition metal, and oxygen. It has a layered rock salt type crystalline structure, and the second region is present in the surface and part of the interior, and magnesium It contains cium, fluorine, and oxygen, has a rock salt-type crystal structure, and has a first region and a second region The crystal orientation in the region is consistent, and the magnesium on the surface of the cathode active material is measured by X-ray photoelectron spectroscopy. The ratio of the concentration to the fluorine concentration is Mg:F=y:1 (3≦y≦5) for the positive electrode active material.

[0021] Furthermore, the above describes the fluorine bonding energy on the surface of the positive electrode active material as measured by X-ray photoelectron spectroscopy. The peak position is preferably 682 eV or higher and less than 685 eV.

[0022] Furthermore, in one aspect of the present invention, a lithium source, a transition metal source, a magnesium source, and a fluorine source are mixed. The process involves combining the ingredients and heating them at a temperature of 800°C to 1100°C for 2 to 20 hours. Heating in an oxygen-containing atmosphere at a temperature between 500°C and 1200°C for a holding time of 50 hours or less. A method for producing a positive electrode active material having a certain degree, wherein fluorine contained in a fluorine source and magnesium The atomic ratio of magnesium contained in the source is Mg:F = 1:x (1.5 ≤ x ≤ 4). This is a method for producing the positive electrode active material.

[0023] Alternatively, one aspect of the present invention is a positive electrode active material, wherein the positive electrode active material comprises a first region and a second region It has a region and a second region, the first region being located inside the positive electrode active material and the second region being located inside the positive electrode active material It is present in the surface layer and part of the interior, and the first region contains lithium, cobalt, and oxygen. The second region contains cobalt, magnesium, fluorine, and oxygen, and is the positive electrode active material. When analyzed by electron energy loss spectroscopy, the L3 / L of cobalt in the first region was found to be 2 is less than 3.8, and the cobalt in the second region is L3 / L2 is 3.8 or higher. It is the positive electrode active material. [Effects of the Invention]

[0024] According to one aspect of the present invention, by using it in a lithium-ion secondary battery, during the charge-discharge cycle This can provide a positive electrode active material that suppresses the decrease in capacity. Furthermore, it can be used in high-capacity secondary batteries. We can provide this. Furthermore, we can provide a secondary battery with excellent charge and discharge characteristics. Furthermore, it is possible to provide safe and reliable secondary batteries. In addition, novel materials and active We can provide materials, energy storage devices, or methods for manufacturing them. [Brief explanation of the drawing]

[0025] [Figure 1] A diagram illustrating an example of a positive electrode active material. [Figure 2] A diagram illustrating an example of a method for preparing positive electrode active material. [Figure 3] Cross-sectional view of the active material layer when a graphene compound is used as a conductive additive. [Figure 4] A diagram illustrating a coin-type rechargeable battery. [Figure 5] A diagram illustrating a cylindrical rechargeable battery. [Figure 6] A diagram illustrating an example of a secondary battery. [Figure 7] A diagram illustrating an example of a secondary battery. [Figure 8] A diagram illustrating an example of a secondary battery. [Figure 9] A diagram illustrating an example of a secondary battery. [Figure 10] A diagram illustrating a laminated rechargeable battery. [Figure 11] A diagram illustrating a laminated rechargeable battery. [Figure 12] A diagram showing the external appearance of a secondary battery. [Figure 13] A diagram showing the external appearance of a secondary battery. [Figure 14] A diagram illustrating the method for manufacturing a secondary battery. [Figure 15] A diagram illustrating a rechargeable battery that can be bent. [Figure 16] A diagram illustrating a rechargeable battery that can be bent. [Figure 17] A diagram illustrating an example of an electronic device. [Figure 18] A diagram illustrating an example of an electronic device. [Figure 19] A diagram illustrating an example of an electronic device. [Figure 20] A diagram illustrating an example of an electronic device. [Figure 21] A diagram illustrating the characteristics of a conventional secondary battery. [Figure 22] STEM image and EDX mapping of the cathode active material of Example 1. [Figure 23] STEM image and EDX mapping of the cathode active material of Example 1. [Figure 24] A graph showing the amount of magnesium near the surface of the positive electrode active material in Example 1. [Figure 25] A graph showing the cycle characteristics of the secondary battery in Example 1. [Figure 26] A graph showing the cycle characteristics of the secondary battery in Example 1. [Figure 27] A graph showing the cycle characteristics of the secondary battery in Example 1. [Figure 28] A graph showing the cycle characteristics of the secondary battery in Example 1. [Figure 29] STEM image of the positive electrode active material in Example 2. [Figure 30] STEM image of the positive electrode active material in Example 2. [Figure 31] A graph showing the charge and discharge characteristics of the secondary battery in Example 2. [Figure 32] A graph showing the cycle characteristics of the secondary battery in Example 2. [Figure 33] STEM and FFT images of the cathode active material of Example 3. [Figure 34] STEM and FFT images of the cathode active material of Example 3. [Figure 35] STEM image and EDX mapping of the cathode active material in Example 3. [Figure 36] TEM image of the positive electrode active material of Example 3. [Figure 37] STEM image and EDX mapping of the cathode active material in Example 3. [Figure 38] ToF-SIMS depth analysis of the positive electrode active material in Example 3. [Figure 39] XPS spectrum of the positive electrode active material of Example 3. [Figure 40] A graph showing the cycle characteristics of the secondary battery in Example 4. [Figure 41] A graph showing the cycle characteristics of the secondary battery in Example 4. [Figure 42] A graph showing the cycle characteristics of the secondary battery in Example 4. [Figure 43] A graph showing the cycle characteristics of the secondary battery in Example 6. [Figure 44] STEM image of the positive electrode active material of Example 6. [Figure 45] STEM image of the positive electrode active material of Example 6. [Figure 46] STEM and FFT images of the cathode active material of Example 6. [Figure 47] STEM image and estimated crystal structure model of the cathode active material in Example 6. [Figure 48] STEM image and EDX mapping of the cathode active material of Example 6. [Figure 49] STEM image and EDX mapping of the cathode active material of Example 6. [Figure 50] A graph showing the EELS analysis results of the positive electrode active material in Example 7. [Figure 51] A graph showing the EELS analysis results of the positive electrode active material in Example 7. [Modes for carrying out the invention]

[0026] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is... Not limited to the following description, the form and details can be modified in various ways, as any person skilled in the art would know. This is easily understood. Furthermore, the present invention shall be interpreted as being limited to the contents of the embodiments described below. It's not something that can be done.

[0027] In the figures described herein, the positive electrode, negative electrode, active material layer, separator, and outer casing are shown separately. The size, thickness, etc., of each individual component may be exaggerated for the sake of clarity in the explanation. Yes. Therefore, each component is not necessarily limited to its size, nor is the relationship between each component limited. It is not limited to relative size.

[0028] Furthermore, in the configuration of the present invention as described herein, parts that are the same or have similar functions The same symbols are used consistently across different drawings, and explanations of their repetition are omitted. When referring to parts with similar functions, the hatch pattern is the same, and no special designation is given. There are cases where this is not the case.

[0029] Furthermore, Miller indices are used to express crystal planes and directions. In Miller index notation, crystallography Above, a superscript bar is placed over the number, but in this specification, due to the restrictions on application notation, a -(ma) is placed before the number. The IN sign will be used. In addition, individual orientations indicating directions within the crystal are indicated by [ ], and the equivalent is The collective orientation that shows all directions is < >, the individual planes that show crystal planes are ( ), and equivalent symmetries are The sets and surfaces that a set possesses are denoted by {}.

[0030] In this specification, segregation refers to the process of a solid composed of multiple elements (e.g., A, B, C) This refers to the phenomenon where a certain element (for example, B) is distributed unevenly.

[0031] In this specification, etc., the layered rock salt type crystal structure of a composite oxide containing lithium and a transition metal This structure has a rock salt-type ionic arrangement in which cations and anions are arranged alternately, and it contains transition metals and Because lithium is arranged in a regular pattern to form a two-dimensional plane, two-dimensional diffusion of lithium is possible. This refers to the crystal structure. It may contain defects such as vacancies in cations or anions. Also, layers... Strictly speaking, the rock salt crystal structure is a structure in which the lattice of the rock salt crystal is distorted. be.

[0032] A rock salt crystal structure refers to a structure in which cations and anions are arranged alternately. There may be deficiencies in either the ON or N ion.

[0033] Layered rock salt crystals and the anions of rock salt crystals form a cubic close-packed structure (face-centered cubic lattice structure). When layered rock salt crystals and rock salt crystals come into contact, cubic close-packed formation is created by anions. There are crystal planes with matching filling structures. However, the space group of the layered rock salt crystal is R-3m. Since it is different from the Fm-3m space group of rock salt, the indices of crystal planes that satisfy the above conditions are for layered rock. Salt-type crystals and rock salt-type crystals are different. In this specification, layered rock salt-type crystals and rock salt-type crystals are used. When the orientation of the cubic close-packed structure composed of anions is aligned, the orientation of the crystal is approximately one It is possible to say "to do."

[0034] For example, lithium cobalt oxide having a layered rock salt-type crystal structure and having a rock salt-type crystal structure When magnesium oxide comes into contact with lithium cobalt oxide, the crystal orientation is approximately the same as that of lithium cobalt oxide. When the (1-1-4) surface of the magnesium oxide is in contact with the {001} surface of the magnesium oxide, When the (104) surface of the magnesium oxide is in contact with the {001} surface of the magnesium oxide, lithium cobalt oxide When the (0-14) surface of the lithium cobalt oxide is in contact with the {001} surface of the magnesium oxide, When the (001) surface of the lithium cobalt oxide is in contact with the {111} surface of the magnesium oxide, Examples include cases where the (012) plane and the {111} plane of magnesium oxide are in contact.

[0035] The approximate agreement of the crystal orientation in the two regions can be seen in TEM (transmission electron microscope) images and STEM images. (Scanning transmission electron microscope) image, HAADF-STEM (High-angle scattering annular dark-field scanning transmission electron microscope) This can be determined from images such as microscopic images and ABF-STEM (annular bright-field scanning transmission electron microscope) images. Yes, it is possible. X-ray diffraction, electron diffraction, neutron diffraction, etc., can also be used as criteria for judgment. In M-images, the arrangement of cations and anions can be observed as a repetition of bright and dark lines. When the orientation of the cubic close-packed structure is aligned in rock salt crystals, bright lines and It can be observed that the angle formed by the repetition of the dark lines is 5 degrees or less, more preferably 2.5 degrees or less. It is possible. However, light elements such as oxygen and fluorine cannot be clearly observed in TEM images, etc. In some cases, the alignment of the metal elements can be determined by the arrangement of the metal elements.

[0036] In this specification, the similarity in the structure of a two-dimensional interface is referred to as epitaxy. Crystal growth that has similarities to the structure of a two-dimensional interface is called epitaxial growth. Topotaxis refers to having fundamental structural similarities or having the same crystallographic orientation. Therefore, if it is topotaxis, when you observe a part of the cross-section, you will see two regions (even The orientation of the crystals in the underlying region and the region formed by growth is roughly consistent.

[0037] (Embodiment 1) [Structure of the positive electrode active material] First, using Figure 1, we will explain a positive electrode active material 100, which is one embodiment of the present invention. Figure 1(A As shown in the diagram, the positive electrode active material 100 has a first region 101 and a second region 102. It can also be said that the second region 102 is located on the first region 101, or the second region 102 It can be said that this covers at least a portion of the first region 101.

[0038] The first region 101 and the second region 102 are regions having different compositions. However, the second region Region 102 is preferably a region where a specific element is segregated, as will be described later. The boundaries between the two regions may not be clear. In Figure 1(A), the first region 101 and the second region Region 102 is divided by a dotted line, and the gradient of elemental concentrations across the dotted line is shown in gray density. Indicated in light. For convenience, in Figure 1(B) and subsequent figures, the boundary between the first region 101 and the second region 102 is shown. The boundary will be shown only by a dotted line. Details of the boundary between the first region 101 and the second region 102. This will be explained later.

[0039] Furthermore, as shown in Figure 1(B), a second region 102 may exist inside the positive electrode active material. For example, when the first region 101 is polycrystalline, specific elements segregate at the grain boundaries and in their vicinity. Furthermore, a portion of the positive electrode active material with crystal defects may be formed. In and near there, specific elements may be segregated, forming a second region 102. In specifications and other documents, a crystal defect refers to a defect observable by TEM imaging, etc., or the inclusion of other elements in the crystal. This refers to a complex structure, etc.

[0040] Furthermore, as shown in Figure 1(B), the second region 102 covers the entirety of the first region 101. It's not necessary.

[0041] In other words, the first region 101 is located inside the positive electrode active material 100, and the second region 10 Region 2 is located on the surface of the positive electrode active material 100. Furthermore, the second region 102 is located on the positive electrode active material 1 It may exist inside 00.

[0042] The first region 101 may also be called, for example, solid phase A. The second region 102 is For example, it could be called solid phase B.

[0043] The particle size of the positive electrode active material 100 is important; if it is too large, lithium diffusion becomes difficult, and it is coated onto the current collector. When this happens, there are problems such as the surface of the active material layer becoming too rough. On the other hand, if it is too small, current collection... Problems include difficulty in supporting the active material layer during coating onto the body, and excessive reaction with the electrolyte. This occurs. Therefore, the D50 (also called the median diameter) is between 0.1 μm and 100 μm. It is preferable that the particle size be between 1 μm and 40 μm, and more preferably between 1 μm and 40 μm.

[0044] <First Domain 101> The first region 101 has lithium, a transition metal, and oxygen. The first region 101 is It can be said that it contains a composite oxide comprising lithium and a transition metal.

[0045] The transition metal present in the first region 101 is a layered rock salt type composite oxide, along with lithium. It is preferable to use a metal that can form a cellulose molecule. For example, manganese, cobalt, nickel, etc. One or more can be used. That is, the transition metal that the first region 101 has and You may use only cobalt, or you may use two types, cobalt and manganese, or cobalt Three types of metals may be used: thut, manganese, and nickel. Furthermore, the first region 101 is added to the transition metal. Furthermore, it may contain metals other than transition metals, such as aluminum.

[0046] In other words, the first region 101 consists of lithium cobaltate, lithium nickelate, and a portion of cobalt. Lithium cobaltate substituted with manganese, nickel-manganese-lithium cobaltate Composites containing lithium and transition metals, such as lithium nickel-cobalt-aluminate. It may contain oxides.

[0047] The first region 101 is a region within the positive electrode active material 100 that particularly contributes to the charge-discharge reaction. It is possible. In order to increase the capacity when the positive electrode active material 100 is used in a secondary battery, the first region It is preferable that region 101 has a larger volume than the second region 102.

[0048] In the layered rock salt crystal structure, lithium diffuses easily in two dimensions, so the first region 101 is defined as follows. This is preferable. Also, if the first region 101 has a layered rock salt type crystal structure, unexpectedly, As will be discussed later, magnesium is prone to segregation. However, the entirety of the first region 101 is layered rock. It does not have to be a salt-type crystal structure. For example, even if there are crystal defects in part of the first region 101. Alternatively, a portion of the first region 101 may be amorphous, or it may have other crystalline structures. It's okay to be there.

[0049] <Second Domain 102> The second region 102 has magnesium, fluorine, and oxygen. For example, the second region Region 102 contains magnesium oxide, and it can be said that some of the oxygen is replaced by fluorine. stomach.

[0050] The second region 102 covers at least a portion of the first region 101. The magnesium oxide contained in O2 is an electrochemically stable material, so it can withstand repeated charging and discharging. Even if it deteriorates easily, it is suitable as a coating layer.

[0051] The second region 102, if too thin, will have reduced functionality as a coating layer, but if it is too thick, it will also have reduced functionality. This leads to a decrease in quantity. Therefore, the thickness of the second region is preferably 0.5 nm to 50 nm. A more preferable size is between 0.5 nm and 3 nm.

[0052] If the second region 102 has a rock salt-type crystal structure, then the crystal orientation is the same as that of the first region 101. It is preferable because it is easy to implement and functions well as a stable coating layer. However, the second region 10 Not all of region 2 has to be a rock salt type crystal structure. For example, part of the second region 102 is amorphous. It may be of any quality, or it may have other crystalline structures.

[0053] Generally, as the positive electrode active material undergoes repeated charging and discharging, transition metals such as cobalt and manganese are released. Side reactions occur, such as dissolution into the electrolyte, oxygen release, and instability of the crystal structure. Degradation progresses. However, the positive electrode active material 100 in one aspect of the present invention has a second surface layer Because it has region 102, the first region 101 has a composite oxide containing lithium and a transition metal. It is possible to make the crystalline structure of materials more stable.

[0054] Furthermore, the second region 102 has magnesium, fluorine, and oxygen, but furthermore, the first It is preferable that the first region 101 and the second region have the same transition metal. If region 102 has the same transition metal, the valence of the transition metal will be different in these two regions. It is preferable that the transition metal in the first region 101 is a trivalent atom. Preferably, there are more of these than atoms of other valencies, and the transition metal in the second region 102 is divalent. It is preferable that there are more atoms with other valencies than atoms with other valencies.

[0055] If there are many divalent transition metals in the second region 102, then CoO(II), MnO(II), Ni( II) shows that there are many metal oxides with a transition metal:oxygen ratio of 1:1 (atomic ratio). This metal oxide forms a stable solid solution with magnesium oxide, which is also a divalent metal oxide. It is easy to form a second region 102. Therefore, the second region 102 can become a more stable and better coating layer.

[0056] The valency of transition metals can be determined by EELS (Electron Energy Loss Spectroscopy) and XAFS (X-ray Absorption Fine Structure Spectroscopy). Analysis, XPS (X-ray photoelectron spectroscopy), ESR (electron spin resonance), Mössbauer spectroscopy, etc. This allows for analysis. In particular, EELS has high spatial resolution, so the second region 102 This method is preferable because it allows for analysis even of thin layers of a few nanometers.

[0057] When analyzing the valence of transition metals using EELS, the valence can be determined by the L3 / L2 ratio. The larger the L3 / L2 ratio, the higher the proportion of divalent transition metals. For example, in EELS, When the transition metals of region 101 and region 202 were analyzed, the first region 101 possesses The L3 / L2 ratio of the transition metal is less than 3.8, and the transition metal in the second region 102 is L3 / L2 is preferably 3.8 or higher.

[0058] Furthermore, the second region 102 may also contain lithium in addition to the above.

[0059] Furthermore, as shown in Figure 1(B), if a second region 102 also exists inside the first region 101, Furthermore, the crystal structure of the lithium and transition metal composite oxide in the first region 101 is further stabilized. It is sometimes possible to standardize the process, which is preferable.

[0060] Furthermore, the fluorine present in the second region 102 exists in bonding states other than MgF2 and LiF. It is preferable that... Specifically, when the surface of the positive electrode active material 100 is analyzed by XPS, fluorine The peak position of the bond energy with other elements must be between 682 eV and 685 eV. This is preferable, and more preferably about 684.3 eV. This is due to MgF2 and LiF This is a bond energy that does not match any of the others.

[0061] In this specification, the peak position of the binding energy of a certain element when analyzed by XPS. This refers to the range in which the intensity of the energy spectrum is maximum, corresponding to the bond energy of that element. This refers to the value of the bond energy that results in [the specified value].

[0062] <Boundary between the first region 101 and the second region 102> The first region 101 and the second region 102 are TEM images, STEM images, and FFT (Fast Fourier Transform). Conversion) Analysis, EDX (Energy Dispersive X-ray Spectroscopy), ToF-SIMS (Time-of-Flight Secondary X-ray Spectroscopy) Depth analysis by ion mass spectrometry, XPS (X-ray photoelectron spectroscopy), Auger electron analysis Different compositions can be confirmed using optical methods, TDS (thermal desorption gas analysis), etc. For example, in the cross-sectional TEM and STEM images of the positive electrode active material 100, differences in constituent elements are reflected in the image. Because it is observed as a difference in brightness, the constituent elements of the first region 101 and the second region 102 It can be observed that they are different. Also, in the EDX elemental distribution image, the first region 101 and the second region It can be observed that 102 has different elements. However, various analyses do not necessarily reveal the first A clear boundary between region 101 and the second region 102 does not need to be observable.

[0063] In this specification, the range of the second region 102 present on the surface of the positive electrode active material 100 is: The magnesium concentration detected by depth profiling from the outermost surface of the positive electrode active material 100 is P This refers to the period until it reaches 1 / 5 of the original length. For depth directional analysis, the EDX line analysis described above is used. Magnesium The peak concentration of the substance is located within a depth of 2 nm from the surface to the center of the positive electrode active material 100. It is preferable that it exists to a depth of 1 nm, and more preferably to a depth of 0.5 nm. It is even more preferable that it be present at a depth where the magnesium concentration is 1 / 5 of the peak. In other words, the range of the second region 102 varies depending on the manufacturing method, but in the case of the manufacturing method described later... This generally extends from the surface of the positive electrode active material to a depth of approximately 2 nm to 5 nm.

[0064] The second region 102, which is located inside the first region 101, was also detected by depth profiling. This refers to the region where the magnesium concentration is 1 / 5 or more of the peak.

[0065] The distribution of fluorine in the positive electrode active material 100 is preferably superimposed on the distribution of magnesium. Therefore, the peak of fluorine concentration is in the depth from the surface to the center of the positive electrode active material 100. It is preferable that they are present up to 2 nm, and more preferably up to a depth of 1 nm. It is even more preferable that they exist up to a depth of 0.5 nm.

[0066] Thus, the second region 102 is formed by magnets extending from the surface of the positive electrode active material 100 towards the interior. This can also be described as a concentration gradient region where the concentrations of um and fluorine decrease.

[0067] Magnesium and fluorine concentrations were determined by ToF-SIMS, XPS, Auger electron spectroscopy, This can be analyzed using TDS, etc.

[0068] Note that XPS has a measurement range of approximately 5 nm from the surface of the positive electrode active material 100. It is possible to quantitatively analyze the elemental concentration present in the region up to approximately 5 nm. Therefore, the second region 10 If the thickness of region 2 is less than 5 nm, combine a portion of the second region 102 and the first region 101. If the thickness of the second region 102 is 5 nm or more from the surface, then the original The elementary concentration can be quantitatively analyzed. The surface of the positive electrode active material 100 was analyzed using XPS, and the lithium Um, atoms including transition metals, oxygen, fluorine, and magnesium, which are present in the first region 101. When the total amount is set to 100 atomic%, the magnesium concentration is 1 atomic% or greater. 16 atomic% or less, and fluorine concentration of 0.2 atomic% or more, 4 atomic It is preferable that the concentration be % or less. Furthermore, the ratio of magnesium to fluorine concentrations should be Mg:F=y: It is preferable that the ratio of atoms is 1 (3 ≤ y ≤ 5), and that Mg:F = approximately 4:1. This is even more preferable. When the magnesium and fluorine concentrations are within these ranges, the secondary battery This allows for the creation of a positive electrode active material 100 that exhibits extremely good cycle characteristics when used.

[0069] As mentioned above, the concentrations of magnesium and fluorine gradually decrease from the surface towards the interior. Therefore, the first region 101 contains elements such as magnesium that are present in the second region 102. It may also be the case that the second region 102 has the elements that the first region 101 has. It may also be the first region 101, which contains carbon, sulfur, silicon, sodium, calcium, and salt. It may also contain other elements such as carbon, sulfur, and zirconium. The second region 102 is carbon, sulfur It contains yellow, silicon, sodium, calcium, chlorine, zirconium, and other elements. That's fine.

[0070] [Segregation] The second area 102 includes sputtering, solid-phase methods, liquid-phase methods such as sol-gel methods, etc. It can also be formed by the method described above. However, the inventors have found that by using a magnesium source and a fluorine source... After mixing with the generating material, heating causes magnesium to segregate, forming a second region 102. It was made clear what is possible. Furthermore, having the second region 102 formed in this way We have revealed that the positive electrode active material possesses extremely excellent properties.

[0071] For example, in Example 4 of Patent Document 2 (Japanese Patent Publication No. 2016-076454), magnesium A complex oxide containing the compound oxide is synthesized, and then the powder of the complex oxide is mixed with lithium fluoride. By heating, a fluorinated and lithium-ionized surface oxide is formed on the surface of the composite oxide. The method states that no magnesium was detected in the surface oxides.

[0072] However, the inventors of this invention simultaneously mix a magnesium source and a fluorine source as starting materials. By doing so, magnesium oxide could be segregated to the surface layer of the positive electrode active material 100. Furthermore, it has been found that the fluorine added to the starting material has the effect of segregating magnesium. The inventors revealed this.

[0073] In order to form the second region 102 by magnesium segregation, the surface layer of the positive electrode active material 100 Furthermore, magnesium can segregate not only at grain boundaries and their vicinity, but also at crystal defects and their vicinity. The second region 102 formed at the grain boundary and its vicinity, and at crystal defects and their vicinity, is Further stabilization of the crystal structure of the lithium and transition metal composite oxide in region 101 of 1. It can contribute to transformation.

[0074] To effectively perform segregation in the second region 102, the concentrations of magnesium and fluorine in the raw materials should be Mg Preferably, F = 1:x (1.5 ≤ x ≤ 4) (atomic ratio), and Mg:F = 1:2 It is even more preferable that the ratio be approximately (atomic ratio).

[0075] On the other hand, the concentrations of magnesium and fluorine in the second region 102, which was formed as a result of segregation, are M It is preferable that g:F=y:1 (3≦y≦5) (atomic ratio), and Mg:F=4:1. It is even more preferable that it be a degree.

[0076] The second region 102, formed by segregation, was formed by epitaxial growth. Therefore, the crystal orientations of the first region 101 and the second region 102 are partially identical. Therefore, the first region 101 and the second region 102 can become topotaxi. If the crystal orientations of region 101 and the second region 102 are roughly the same, then the second region 102 is It can function as a better coating layer.

[0077] <Third Domain 103> In addition, there have been examples in which the positive electrode active material 100 has a first region 101 and a second region 102. As explained above, the present invention is not limited to these embodiments. For example, as shown in Figure 1(C) The positive electrode active material 100 may have a third region 103. The third region 103 may be, for example For example, it can be set up so as to be adjacent to at least a part of the second region 102. Region 103 may be a carbon-containing film including a graphene compound, or lithium The coating may have um or decomposition products of the electrolyte. The third region 103 is carbon In the case of a coating, the conduction between the positive electrode active materials 100 and between the positive electrode active materials 100 and the current collector is impaired. The electrical properties can be enhanced. Also, the third region 103 contains lithium or electrolyte decomposition products. If the coating has this property, it suppresses excessive reaction with the electrolyte, and when used in a secondary battery, it prevents excessive cycling. This can improve performance characteristics.

[0078] Furthermore, a buffer area may be provided between the first area 101 and the second area 102. The buffer region includes, for example, lithium, transition metals, oxygen, as well as titanium, aluminum, It is preferable that it contains metals such as zirconium and vanadium. The buffer region is the first region Region 101 and the second region 102 may overlap. Positive electrode active material having a buffer region Assuming a quality of 100, the crystal structure of the first region 101 and the second region 102 is further stabilized. This allows for the creation of a positive electrode active material with excellent cycle characteristics, which is preferable.

[0079] [Manufacturing method] It has a first region 101 and a second region 102, the second region 102 being formed by segregation. The method for producing the positive electrode active material 100 in this case will be explained using Figure 2. In this embodiment, If the transition metal in the first region 101 is cobalt, that is, if the first region 101 is co The case where lithium baltate is present will be explained. Furthermore, segregation occurs with magnesium oxide. The case of forming a second region 102 containing fluorine will be described.

[0080] First, prepare the starting materials (S11). Specifically, lithium source, cobalt source, magnesium Weigh the um source and fluorine source separately. For example, lithium carbonate can be used as the lithium source. Lithium fluoride, lithium hydroxide, etc. can be used. For example, as a cobalt source, Cobalt oxide, cobalt hydroxide, cobalt oxyhydroxide, cobalt carbonate, cobalt oxalate For example, cobalt sulfate can be used as a magnesium source. Magnesium, magnesium fluoride, etc. can be used as a fluorine source. For example, lithium fluoride, magnesium fluoride, etc. can be used. Tium can be used as both a lithium source and a fluorine source, and magnesium fluoride M can be used as both a magnesium source and a fluorine source.

[0081] In this embodiment, lithium carbonate (Li2CO3) is used as the lithium source, and as the cobalt source Cobalt oxide (Co3O4), magnesium oxide (MgO) as a magnesium source, lithium Lithium fluoride (LiF) will be used as the um source and fluorine source.

[0082] The atomic ratio of magnesium and fluorine in the raw materials is Mg:F=1:x(1.5≦x≦4)(atomic A numerical ratio is preferred, and it is more preferable that Mg:F = 1:2 (atomic ratio), The ratio of magnesium oxide to lithium fluoride is MgO:LiF = 1:x (1.5 ≤ x ≤ 4) It is preferable that the molar ratio be approximately MgO:LiF = 1:2. It is preferable.

[0083] The molar ratio of each raw material can be, for example, as follows: 1 / 2·Li2CO3+((1-z) / 3)·Co3O4+z·MgO+2z·LiF (z=0.01)

[0084] Next, the weighed starting materials are mixed (S12). For mixing, a ball mill or bead mill can be used. The following can be used.

[0085] Next, the materials mixed in S12 are heated (S13). This step is distinguished from the subsequent heating step. For this reason, there is a first heating or baking process. The first heating is 800°C or higher and 1050°C It is preferable to carry out the process at temperatures below ℃, and more preferably at temperatures between 900℃ and 1000℃. The heating time is preferably between 2 hours and 20 hours. The first heating is done using dry air, etc. It is preferable to carry out the process in a dry atmosphere. A dry atmosphere is one in which the dew point is -50°C or lower. Preferably, the temperature is -100°C or lower. In this embodiment, 1000°C The heating will be carried out for 10 hours, with a temperature increase of 200°C / h, and dry air with a dew point of -109°C being used for 10 hours. The flow rate will be L / min.

[0086] The first heating in S13 causes the first region 101 to have a composite containing lithium and a transition metal. Oxides can be synthesized. In addition, this first heating process removes the magnesium contained in the starting material. Some of the sium and fluorine segregates on the surface of the composite oxide containing lithium and transition metals. At this point, much of the magnesium and fluorine are in complex oxides containing lithium and transition metals. It is in a state of solid solution.

[0087] Next, the material heated in S13 is cooled to room temperature (S14). The cooling process is the same as or different from the heating process. It is preferable to carry it out over the above-mentioned period. For example, it should be carried out over a period of 10 to 15 hours. This can be done. After cooling, it is preferable to sift the synthesized material. In this method, the material will be sieved using a 53 μm mesh.

[0088] Furthermore, lithium, cobalt, fluorine, and magnesium were pre-synthesized as starting materials. Particles of a composite oxide containing the above may be used. In this case, steps S12 to S14 This can be omitted.

[0089] Next, the material cooled in S14 is subjected to a second heating (S15). This step is the same as the previous heating step. To distinguish between the two, this is sometimes referred to as a second heating or annealing process. Optimal conditions for the second heating process. This relates to the particle size and composition of a composite oxide containing lithium, cobalt, fluorine, and magnesium. Although it varies, it is preferable to hold the temperature at the specified temperature for 50 hours or less, and for at least 2 hours. It is preferable to perform the process for 10 hours or less. The specified temperature is between 500°C and 1200°C. A temperature of 700°C or higher and 1000°C or lower is preferred, and a temperature of around 800°C is even more preferred. Furthermore, heating in an oxygen-containing atmosphere is preferable. In this embodiment, at 800°C The heating will be performed for 2 hours, with a temperature increase of 200°C / h, and 10 L / of dry air with a dew point of -109°C. We will run it in min mode.

[0090] By performing the second heating in S15, the magnesium and fluorine contained in the starting material are converted into lithium This can promote segregation to the surface layer of composite oxides containing mu and transition metals.

[0091] Finally, the material heated in S15 is cooled to room temperature. The cooling process should be equal to or greater than the heating process. It is preferable to do this over time. Then the cooled material is collected (S16), and the first region A positive electrode active material 100 having region 101 and a second region 102 can be obtained.

[0092] By using the positive electrode active material described in this embodiment, a secondary electrode with high capacity and good cycle characteristics can be obtained. It can be used as a battery. This embodiment can be used in appropriate combination with other embodiments. It is possible.

[0093] (Embodiment 2) In this embodiment, it is used in a secondary battery having the positive electrode active material 100 described in the previous embodiment. Examples of other materials that can be used will be described. In this embodiment, the positive electrode, negative electrode and electric Let's take a secondary battery, in which the dissolution solution is enclosed in an outer casing, as an example.

[0094] [Positive electrode] The positive electrode comprises a positive electrode active material layer and a positive electrode current collector.

[0095] <Cathode active material layer> The positive electrode active material layer contains a positive electrode active material. Furthermore, the positive electrode active material layer contains a conductive additive and a binder. It may have.

[0096] As the positive electrode active material, the positive electrode active material 100 described in the previous embodiment can be used. By using the positive electrode active material 100 described in the previous embodiment, high capacity and cycle characteristics can be achieved. It can be used to create an excellent rechargeable battery.

[0097] As conductive additives, carbon materials, metal materials, or conductive ceramic materials can be used. Yes, it is possible. Additionally, fibrous materials may be used as conductive additives. The conductivity relative to the total amount of the active material layer... The content of the electrolytic agent is preferably 1 wt% to 10 wt%, and preferably 1 wt% to 5 wt%. This is preferable.

[0098] Conductive additives can form an electrical conduction network within the electrode. This allows for the maintenance of electrical conduction pathways between positive electrode active materials. Conductive aids are present in the active material layer. By adding the agent, an active material layer with high electrical conductivity can be realized.

[0099] Examples of conductive additives include natural graphite, artificial graphite such as mesocarbon microbeads, and carbon fibers. Fibers can be used. For example, mesophase pitch carbon fibers can be used. Carbon fibers such as isotropic pitch carbon fibers can be used. Carbon nanofibers and carbon nanotubes can be used. The tubes can be fabricated, for example, by vapor phase growth. Also, as a conductive additive, for example... Examples include carbon black (acetylene black (AB), etc.) and graphite particles. Carbon materials such as graphene and fullerene can be used. Also, for example, copper, nickel Metal powders such as oxal, aluminum, silver, and gold, as well as metal fibers and conductive ceramic materials. It can be used.

[0100] Furthermore, graphene compounds may be used as conductive additives.

[0101] Graphene compounds possess excellent electrical properties, including high conductivity, as well as high flexibility and high It possesses excellent physical properties, such as high mechanical strength, and may also have other properties. The compound has a planar shape. Graphene compounds enable surface contact with low contact resistance. Furthermore, even thin materials can have very high conductivity, allowing for efficient conduction within the active material layer with only a small amount. An electric current can be formed. Therefore, graphene compounds can be used as conductive additives. This is preferable because it increases the contact area between the active material and the conductive additive. This is preferable because it can reduce electrical resistance. Here, graphene compounds are used as an example. For example, graphene or multigraphene or reduced graphene O It is particularly preferable to use xide (hereinafter referred to as RGO). Here, RGO is, for example, oxidation This refers to compounds obtained by reducing graphene (graphene oxide: GO).

[0102] When using active materials with small particle sizes, for example, active materials with a particle size of 1 μm or less, the specific surface area of ​​the active material is Larger materials require more conductive paths to connect the active materials. Therefore, a larger amount of conductive additive is needed. This tends to happen, and relatively, the amount of active material carried decreases. When this decreases, the capacity of the secondary battery decreases. In such cases, a conductive additive is used. When graphene compounds are used, even small amounts of graphene compounds efficiently form conductive paths. This is particularly preferable because it does not require reducing the amount of active material supported.

[0103] In the following example, a graphene compound is used as a conductive additive in the active material layer 200. An example of the cross-sectional configuration will be explained.

[0104] Figure 3(A) shows a longitudinal cross-sectional view of the active material layer 200. The active material layer 200 consists of granular positive electrode active material. It contains 100, a graphene compound 201 as a conductive additive, and a binder (not shown). Hmm. Here, as graphene compound 201, for example, graphene or multigraphene It is fine to use it. Here, it is preferable that the graphene compound 201 has a sheet-like shape. Furthermore, graphene compound 201 is a multigraphene, or (and) multiple graphenes. The graphene may be partially overlapping and form a sheet.

[0105] In the longitudinal section of the active material layer 200, as shown in Figure 3(A), the interior of the active material layer 200 In Figure 3(A), the graphene compound 201 is dispersed in a generally uniform sheet-like manner. Graphene compound 201 is schematically represented by a thick line, but in reality it is a single or multiple layer of carbon molecules. It is a thin film with a layer thickness. Multiple graphene compounds 201 are multiple granular cathode active materials The material 100 is surrounded, covered, or placed on the surface of multiple granular positive electrode active materials 100. Because they are formed to stick together, they are in surface contact with each other.

[0106] Here, multiple graphene compounds bond together to form a network of graphene compounds. Forming a sheet (hereinafter referred to as graphene compound net or graphene net) Yes, it is possible. When the active material is covered with a graphene net, the graphene net connects the active materials to each other. It can also function as a binder. Therefore, it reduces the amount of binder needed. Because it is possible to do so or not to use it, the ratio of active material to electrode volume or electrode weight The efficiency can be improved. In other words, the capacity of the energy storage device can be increased.

[0107] Here, graphene oxide is used as graphene compound 201 and mixed with the active material to form the active material It is preferable to reduce the layer after forming the layer that will become layer 200. By using graphene oxide, which has extremely high dispersibility in polar solvents, graphene formation can be achieved. The compound 201 can be dispersed approximately uniformly within the active material layer 200. The solvent is volatilized and removed from the dispersion medium containing dispersed graphene oxide, and the graphene oxide is reduced. Therefore, the graphene compound 201 remaining in the active material layer 200 partially overlaps, and By being dispersed to the extent that they are in surface contact, a three-dimensional conductive path can be formed. The reduction of graphene oxide may be carried out, for example, by heat treatment or by using a reducing agent. That's fine.

[0108] Therefore, unlike granular conductive additives such as acetylene black that make point contact with the active material, graph Compound 201 enables surface contact with low contact resistance, unlike conventional conductive additives. It improves the electrical conductivity between the granular positive electrode active material 100 and the graphene compound 201 using only a small amount. Therefore, the ratio of positive electrode active material 100 in the active material layer 200 can be increased. This allows for an increase in the discharge capacity of the energy storage device.

[0109] Examples of binders include styrene-butadiene rubber (SBR) and styrene-isoprene rubber. N-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene- It is preferable to use a rubber material such as a propylene-diene copolymer. Fluororubber can be used.

[0110] Furthermore, it is preferable to use a water-soluble polymer as the binder. Examples of the base material include polysaccharides. Examples of the polysaccharides include cellulose derivatives such as carboxymethyl cellulose (CMC), methylcellulose, ethylcellulose, hydroxypropylcellulose, diacetylcellulose, regenerated cellulose, and starch etc. Further, it is more preferable to use these water-soluble polymers in combination with the rubber material described above .

[0111] Alternatively, examples of the binder include polystyrene, polymethyl acrylate, polymethyl methacrylate (polymethyl methacrylate (PMMA)), sodium polyacrylate, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene, isobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride ( PVdF), polyacrylonitrile (PAN), ethylene propylene diene polymer, polyvinyl acetate, nitrocellulose and other materials are preferably used .

[0112] A plurality of the above binders may be used in combination

[0113] For example, a material having a particularly excellent viscosity adjustment effect may be used in combination with other materials. For example, although rubber materials and the like are excellent in adhesive force and elastic force, it may be difficult to adjust the viscosity when mixed with a solvent . In such a case, for example, it is preferable to mix with a material having a particularly excellent viscosity adjustment effect . As the material having a particularly excellent viscosity adjustment effect, for example, a water-soluble polymer may be used . Further, as the water-soluble polymer having a particularly excellent viscosity adjustment effect, the above-mentioned polysaccharides, for example, car boxymethylcellulose ​​Carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxy propyl cellulose and cellulose derivatives such as diacetyl cellulose, regenerated cellulose, etc., or starch can be used.

[0114] In addition, cellulose derivatives such as carboxymethyl cellulose, for example, by using salts such as sodium salts or ammonium salts of carboxymethyl cellulose, the solubility is increased, and it becomes easier to exhibit the effect as a viscosity modifier. By increasing the solubility, the dispersion of the active material and other components can be improved when preparing the electrode slurry. In this specification, the cellulose and cellulose derivatives used as the electrode binder shall include those salts.

[0115] Water-soluble polymers stabilize the viscosity by dissolving in water, and also stably disperse the active material and other materials combined as a binder, for example, styrene-butadiene rubber, etc. in an aqueous solution. Also, due to having functional groups, it is expected to be easily adsorbed stably on the surface of the active material. In addition, cellulose derivatives such as carboxymethyl cellulose, for example, have many functional groups such as hydroxyl groups and carboxyl groups. Due to having functional groups, it is expected that the polymers interact with each other and widely cover the surface of the active material. When the binder covering or contacting the surface of the active material forms a film, it is also expected to play a role as a passive film and suppress the decomposition of the electrolyte. Here, the passive film is a film having no electron conductivity or having extremely low electric conductivity, for example,

[0116] on the surface of the active material ​​​​​​​When a dynamic film is formed, the decomposition of the electrolyte can be suppressed at the battery reaction potential. It can. Furthermore, the passivation film suppresses electrical conductivity, while lithium ions can conduct electricity. And even better.

[0117] <Positive electrode current collector> As the positive electrode current collector, metals such as stainless steel, gold, platinum, aluminum, and titanium, and this Highly conductive materials such as alloys can be used. Also, materials used for the positive electrode current collector It is preferable that the material does not dissolve at the positive electrode potential. Also, silicon, titanium, neodymium, sucrose Aluminum alloys with added elements that improve heat resistance, such as valdium and molybdenum, are used. It can be formed by metal elements that react with silicon to form silicides. This is also good. Examples of metallic elements that react with silicon to form silicides include zirconium and thi. Tan, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten These include cobalt, nickel, etc. Current collectors come in foil, plate (sheet), mesh, and perforated forms. Shapes such as metallic or expanded metal can be used as appropriate. The thickness of the current collector is It is best to use particles between 5 μm and 30 μm in size.

[0118] [Negative electrode] The negative electrode has a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer also contains a conductive additive and It may have a binder.

[0119] <Negative electrode active material> For example, alloy materials or carbon-based materials can be used as the negative electrode active material.

[0120] As a negative electrode active material, it is possible to perform charge and discharge reactions through alloying and dealloying reactions with lithium. Capable elements can be used. For example, at least one of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. can be included in the material used. Such elements have a larger capacity compared to carbon. In particular, silicon has a high theoretical capacity of 4200 mAh / g. Therefore, it is preferable to use silicon as the negative electrode active material. Also, compounds containing these elements may be used. For example, there are SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, SbSn, etc. Here, elements capable of performing charge-discharge reactions through alloying and de-alloying reactions with lithium, and compounds containing such elements, etc. may be referred to as alloy-based materials in some cases. Among them, at least one can be used. Such elements have a larger capacity compared to carbon. Especially, silicon has a high theoretical capacity of 4200 mAh / g. Therefore, it is preferable to use silicon as the negative electrode active material. Also, compounds containing these elements may be used. For example, there are SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, SbSn, etc. Here, elements capable of performing charge-discharge reactions through alloying and de-alloying reactions with lithium, and compounds containing such elements, etc. may be referred to as alloy-based materials in some cases.

[0121] In this specification, etc., SiO refers to, for example, silicon monoxide. Alternatively, SiO can also be represented as SiO•x. Here, x preferably has a value near 1. For example, x is preferably 0.2 or more and 1.5 or less, more preferably 0.3 or more and 1.2 or less. x

[0122] As the carbon-based material, graphite, graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon nanotubes, graphene, carbon black, etc. can be used.

[0123] Examples of graphite include artificial graphite and natural graphite. Examples of artificial graphite include mesocarbon microbeads (MCMB), coke-based artificial graphite, pitch-based artificial graphite, etc. It is possible to use spherical graphite having a spherical shape as artificial graphite. For example MCMB may have a spherical shape, which is preferable. In addition, it is relatively easy to reduce the surface area of MCMB, which may be preferable. Examples of natural graphite include scaly graphite, spheroidized natural graphite, and the like.

[0124] Graphite exhibits a potential as low as that of metallic lithium when lithium ions are inserted into graphite (when a lithium-graphite intercalation compound is formed) (0.05 V or more and 0.3 V or less vs. Li / L i + ). As a result, the lithium-ion secondary battery can exhibit a high operating voltage. Furthermore graphite has advantages such as a relatively high capacity per unit volume, a relatively small volume expansion, low cost , and high safety compared to metallic lithium, and thus is preferable.

[0125] In addition, oxides such as titanium dioxide (TiO2), lithium titanate (Li4T i5O 12 ), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5) , tungsten oxide (WO2), molybdenum oxide (MoO2), etc. can be used as the negative electrode active material .

[0126] In addition, Li3N-type structured Li Li 3-x M[[ID=4):

[0127] ​​​​​​​​​​​​ When a lithium-transition metal binitride is used, lithium ions are included in the negative electrode active material, Combined with lithium-ion-free materials such as V2O5 and Cr3O8 as positive electrode active materials. This is preferable. By pre-desorbing the lithium ions contained in the positive electrode active material, the negative electrode active material is used. A lithium-transition metal composite can be used.

[0128] Furthermore, materials that undergo a conversion reaction can also be used as the negative electrode active material. For example, Lithium oxide, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO). Transition metal oxides that do not form alloys with the negative electrode active material may be used. The resulting materials include Fe2O3, CuO, Cu2O, RuO2, Cr2O3, etc. CoS oxides 0.89 , sulfides such as NiS and CuS, Zn3N2, Cu3N, Ge3 Nitrides such as N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3, etc. It can also occur with fluoride.

[0129] The conductive additives and binders that the negative electrode active material layer may have include the positive electrode active material layer Materials similar to conductive additives and binders can be used.

[0130] <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 thium.

[0131] [Electrolyte] An electrolyte solution contains a solvent and an electrolyte. A non-protic organic solvent is preferred as the solvent for the electrolyte solution. For example, ethylene carbonate (EC), propylene carbonate (PC), and buty Lenyl carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolane Chtone, 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 Hoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetra One of the following: lahydrofuran, sulfolane, sultone, or two or more of these. It can be used in combinations and ratios.

[0132] Furthermore, by using a polymer material that gels as the solvent for the electrolyte, the risk of leakage is reduced. The integrity is enhanced. Furthermore, it enables the secondary battery to be made thinner and lighter. The polymer is gelled. Typical examples of materials include silicone gel, acrylic gel, acrylonitrile gel, and polyethylene. Teylene oxide gels, polypropylene oxide gels, fluorine polymer gels, etc. There is.

[0133] Furthermore, as the solvent for the electrolyte, an ionic liquid (a room-temperature molten salt) that is flame-retardant and non-volatile is used. By using one or more of these, the internal temperature of the energy storage device will rise due to internal short circuits or overcharging. This can also prevent the rupture or ignition of energy storage devices. Ionic liquids contain cations and anions. It consists of organic cations and anions. As organic cations used in the electrolyte, quaternary cations are used. Ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, etc. aliphatic onium cations, imidazolium cations, pyridinium cations, etc. Aromatic cations are one example. Also, monovalent amide-based anions are used as anions in the electrolyte. Nions, monovalent methide anions, fluorosulfonate anions, perfluoroalkyl Sulfonate anions, tetrafluoroborate anions, perfluoroalkyl borates Anions, hexafluorophosphate anions, or perfluoroalkyl phosphates Examples include anions.

[0134] Furthermore, examples of electrolytes to be dissolved in the above solvent include LiPF6, LiClO4, and Li AsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4 Li2B 10 Cl 10 Li2B 12 Cl 12 LiCF3SO3, LiC4F9SO 3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2) 2. Lithium compounds such as LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, etc. Using one type of um salt, or two or more of these salts in any combination and ratio. It is possible.

[0135] The electrolyte used in the energy storage device may contain particulate matter and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as "non-contaminated"). It is preferable to use a highly purified electrolyte with a low content of (also called "pure substance"). Specifically, the weight ratio of impurities to the electrolyte should be 1% or less, preferably 0.1% or less, more preferably It is preferable that the amount be 0.01% or less.

[0136] Furthermore, the electrolyte contains vinylene carbonate, propanesultone (PS), and tert-butylbe. TBB, fluoroethylene carbonate (FEC), LiBOB, and also succinyl Dinitrile compounds such as notrile and adiponitrile may be added. The concentration should be, for example, between 0.1 wt% and 5 wt% relative to the total solvent.

[0137] Alternatively, a polymer gel electrolyte, obtained by swelling a polymer with an electrolyte solution, may be used. Using an electrolyte increases safety against leakage, etc. Furthermore, it allows for the miniaturization of secondary batteries. It can be made lighter.

[0138] Examples of polymers that can be gelled include silicone gel, acrylic gel, and acrylonitrile gel. Polyethylene oxide gels, polypropylene oxide gels, fluorine polymers Gels or similar materials can be used.

[0139] Examples of polymers include polyalkylene oxides such as polyethylene oxide (PEO). Polymers having a denture structure, PVDF, polyacrylonitrile, etc., and those Copolymers containing PVDF and hexafluoropropylene (H) can be used. For example, PVDF and hexafluoropropylene (H) PVDF-HFP, a copolymer of FP, can be used. The material may have a porous structure.

[0140] In addition, instead of an electrolyte, a solid electrolyte containing inorganic materials such as sulfide-based or oxide-based materials, or P Solid electrolytes containing polymer materials such as EO (polyethylene oxide) can be used. When using a solid electrolyte, the installation of separators and spacers becomes unnecessary. Because the entire pond can be solidified, the risk of leakage is eliminated, dramatically improving safety.

[0141] [Separator] Furthermore, it is preferable that the secondary battery has a separator. The separator can be, for example, paper. Fibers containing cellulose, nonwoven fabrics, glass fibers, ceramics, or other materials. Iron (polyamide), Vinylon (polyvinyl alcohol-based fiber), polyester, acrylic Made from synthetic fibers such as lyl, polyolefin, and polyurethane. This can be done. The separator is processed into a bag shape and positioned to enclose either the positive or negative electrode. It is preferable to do so.

[0142] The separator may have a multilayer structure. For example, an organic material such as polypropylene or polyethylene. The material film contains ceramic-based materials, fluorine-based materials, polyamide-based materials, or a combination thereof. It can be used to coat mixtures and other materials. Examples of ceramic materials include aluminium oxide. Aluminum particles, silicon oxide particles, etc. can be used. As for fluorine-based materials, For example, PVDF, polytetrafluoroethylene, etc. can be used. Polyamide materials Materials used include, for example, nylon and aramid (meta-aramid, para-aramid). It is possible.

[0143] Coating with ceramic materials improves oxidation resistance, thus preventing separation during high-voltage charging and discharging. This can suppress degradation of the battery and improve the reliability of secondary batteries. Furthermore, by using fluorine-based materials... This allows the separator and electrodes to adhere more closely, improving the output characteristics. Coating with polyamide materials, especially aramid, improves heat resistance, thus increasing the safety of secondary batteries. It can improve overall health.

[0144] For example, a mixture of aluminum oxide and aramid material is applied to both sides of a polypropylene film. It may also be done by applying aluminum oxide to the surface of the polypropylene film that is in contact with the positive electrode. A mixed material of um and aramid may be coated, and a fluorine-based material may be coated on the surface in contact with the negative electrode. .

[0145] Using a multilayer separator ensures the safety of the secondary battery even if the overall thickness of the separator is thin. Because it can maintain this state, the capacity per unit volume of a secondary battery can be increased.

[0146] (Embodiment 3) In this embodiment, the shape of the secondary battery having the positive electrode active material 100 described in the previous embodiment is Let's explain an example. The material used in the secondary battery described in this embodiment is the same as in the previous embodiment. The description of the state can be taken into consideration.

[0147] [Coin-type rechargeable battery] First, let's explain an example of a coin-type rechargeable battery. Figure 4(A) shows a coin-type (single-layer flattened type). This is an external view of the secondary battery, and Figure 4(B) is a cross-sectional view thereof.

[0148] The coin-type rechargeable battery 300 consists of a positive electrode casing 301, which also serves as the positive terminal, and a negative electrode casing, which also serves as the negative terminal. 302 is insulated and sealed by a gasket 303 made of polypropylene or the like. The positive electrode 304 consists of a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with it. It is formed by the following. The negative electrode 307 is provided in contact with the negative electrode current collector 308. It is formed by a negative electrode active material layer 309.

[0149] Furthermore, the positive electrode 304 and negative electrode 307 used in the coin-type secondary battery 300 are each made of live metal The layers only need to be formed on one side.

[0150] The positive electrode container 301 and the negative electrode container 302 are made of nickel and aluminum, which are corrosion-resistant to the electrolyte. , metals such as titanium, or alloys thereof, or alloys of these with other metals (e.g., stainless steel) (etc.) can be used. In addition, nickel and aluminum can be used to prevent corrosion by the electrolyte. It is preferable to cover it with a material such as a nut. The positive electrode can 301 is the positive electrode 304, and the negative electrode can 302 is the negative electrode 30 Connect each of the 7s electrically.

[0151] These negative electrode 307, positive electrode 304, and separator 310 are impregnated with the electrolyte, as shown in Figure 4(B). As shown, with the positive electrode can 301 at the bottom, the positive electrode 304, separator 310, negative electrode 307, and negative The electrode cans 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are connected via a gasket 303. The coin-shaped rechargeable battery 300 is manufactured by crimping the parts together.

[0152] By using the positive electrode active material described in the previous embodiment for the positive electrode 304, high capacity cycle This allows for the creation of a coin-type secondary battery 300 with superior characteristics.

[0153] [Cylindrical rechargeable battery] Next, an example of a cylindrical secondary battery will be explained with reference to Figure 5. Cylindrical secondary battery 600 As shown in Figure 5(A), it has a positive electrode cap (battery cover) 601 on the top surface, and the sides and The bottom has a battery case (outer case) 602. These positive electrode cap and battery case (outer case) 6 02 is insulated by gasket (insulating packing) 610.

[0154] Figure 5(B) is a schematic diagram showing a cross-section of a cylindrical secondary battery. Inside 602, a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 in between. A wound battery element is provided. Although not shown in the diagram, the battery element is wound around a center pin. It is being rotated. Battery can 602 is closed at one end and open at the other end. , metals such as nickel, aluminum, and titanium that are corrosion-resistant to the electrolyte, or these Alloys of these metals or alloys of these metals with other metals (for example, stainless steel) can be used. Furthermore, to prevent corrosion from the electrolyte, it is preferable to coat it with nickel, aluminum, etc. i. Inside the battery can 602, the battery element in which the positive electrode, negative electrode and separator are wound is It is sandwiched between a pair of opposing insulating plates 608 and 609. A battery element is also provided. The inside of the battery can 602 is filled with a non-aqueous electrolyte (not shown). The non-aqueous electrolyte is A battery similar to that of the IN type rechargeable battery can be used.

[0155] Since the positive and negative electrodes used in cylindrical secondary batteries are wound, active material is formed on both sides of the current collector. It is preferable to do so. The positive electrode 604 is connected to the positive electrode terminal (positive electrode current collector lead) 603, and the negative The negative terminal (negative current collector lead) 607 is connected to pole 606. The positive terminal 603 and the negative Both electrode terminals 607 can be made of metal materials such as aluminum. Positive electrode terminal 6 Terminal 03 is resistance-welded to the safety valve mechanism 612, and the negative terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 uses a PTC element (Positive Temperature C It is electrically connected to the positive electrode cap 601 via the efficient)611. The safety valve mechanism 612 activates the positive electrode cap 601 when the internal pressure of the battery rises above a predetermined threshold. This disconnects the electrical connection between the positive electrode 604 and the positive electrode 611. Also, the PTC element 611 is at a certain temperature. This is a thermal resistance element whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current. This prevents abnormal heat generation. The PTC element uses barium titanate (BaTiO3) Semiconductor ceramics and the like can be used.

[0156] Furthermore, as shown in Figure 5(C), multiple secondary batteries 600 are connected to conductive plates 613 and 614. Module 615 may be configured by inserting it in between. Multiple secondary batteries 600 are connected in parallel. They may be connected in series, or they may be connected in parallel and then further connected in series. It may be. By configuring a module 615 having multiple secondary batteries 600, It can extract a large amount of electricity.

[0157] Figure 5(D) is a top view of module 615. To make the diagram clearer, the conductive plate 613 is pointed. As shown by the lines, module 615 powers multiple secondary batteries 600. It may have a conductor 616 that connects to the target. A conductive plate 613 is superimposed on the conductor 616. It is possible to do so. Also, even if there is a temperature control device 617 between multiple secondary batteries 600 Good. When the secondary battery 600 overheats, the temperature control device 617 cools it down, and the secondary battery When 600 is too cold, it can be heated by the temperature control device 617. The performance of module 615 will be less affected by outside temperature.

[0158] By using the positive electrode active material 100 described in the previous embodiment for the positive electrode 604, high capacity and This allows for the creation of a cylindrical secondary battery 600 with excellent operating characteristics.

[0159] [Example of a secondary battery structure] Another example of a secondary battery structure will be explained using Figures 6 to 9.

[0160] Figures 6(A) and 6(B) show the external view of the battery pack. The battery pack is a circuit It has a circuit board 900 and a secondary battery 913. The secondary battery 913 has terminal 951 and terminal 9 It has 52 and is covered with label 910. The battery pack also has antenna 914. That's good too.

[0161] The circuit board 900 is secured with a seal 915. The circuit board 900 has a circuit 912. Terminal 911 is connected to terminal 951 and terminal 913 of the secondary battery 913 via the circuit board 900. It is electrically connected to terminal 952. Also, terminal 911 is connected to the antenna via circuit board 900. It is electrically connected to terminal 914 and circuit 912. Note that multiple terminals 911 are provided, and multiple Each of the terminals 911 may be used as a control signal input terminal, a power supply terminal, etc.

[0162] Circuit 912 protects the secondary battery 913 from overcharging, over-discharging, and overcurrent, for example. It functions as a protective circuit. Circuit 912 is provided on the back surface of circuit board 900. That's good. Note that the antenna 914 is not limited to a coil shape; it may also be linear, plate-shaped, etc. Also, planar antennas, aperture antennas, traveling wave antennas, EH antennas, magnetic field antennas Antennas such as dielectric antennas may also be used. Antenna 914 may be, for example, an external device It has the function to communicate data with the battery pack via antenna 914. Communication methods with other devices include NFC, which is used between the battery pack and other devices. A response method that allows for this can be applied.

[0163] The battery pack has a layer 916 between the antenna 914 and the secondary battery 913. For example, layer 916 has the function of shielding electromagnetic fields caused by secondary batteries 913. For example, magnetic materials can be used.

[0164] Note that the structure of the battery pack is not limited to that shown in Figure 6.

[0165] For example, as shown in Figures 7(A-1) and 7(A-2), Figures 6(A) and 6(B) An antenna 918 may be provided on the other pair of opposing faces of the secondary battery 913 shown in the figure. Figure 7(A-1) is an external view of the pair of surfaces as seen from one side, and Figure 7(A-2) is This is an external view of the pair of surfaces shown above, seen from the other side. For parts that are the same as the battery pack, see the battery pack description shown in Figures 6(A) and 6(B). This can be used as appropriate.

[0166] As shown in Figure 7(A-1), a layer 916 is sandwiched between one of the pair of surfaces of the secondary battery 913. An antenna 914 is provided, and as shown in Figure 7(A-2), the other side of the pair of surfaces of the secondary battery 913 An antenna 918 is provided with layer 917 in between. Layer 917 is, for example, connected to a secondary battery 913. It has the function of shielding electromagnetic fields. For layer 917, for example, a magnetic material is used. It is possible to be there.

[0167] By adopting the above structure, the battery pack is provided with two antennas, and antenna 914 and Both sizes of the 918 antenna can be increased.

[0168] Antenna 918 can be fitted with an antenna of a shape applicable to antenna 914. Furthermore, the antenna 918 may be a flat conductor. This flat conductor is a conductor for electric field coupling. It can function as one of the components. That is, one of the two conductors that a capacitor has. Antenna 914 may function as a single conductor. This allows only electromagnetic and magnetic fields to be generated. Alternatively, power can be exchanged using an electric field.

[0169] Alternatively, as shown in Figure 7(B-1), the battery pack shown in Figures 6(A) and 6(B) may have an indicator. A device 920 may be provided. The display device 920 is electrically connected to terminal 911. For the same parts as the battery pack shown in Figures 6(A) and 6(B), see Figures 6(A) and 6(B). The explanation of the battery pack shown in 6(B) can be used as appropriate.

[0170] The display device 920 displays, for example, an image indicating whether or not it is charging, an image indicating the amount of stored power, etc. It may be shown. The display device 920 may be, for example, electronic paper, liquid crystal display device, or electronic A luminescent (also known as EL) display device can be used. For example, an electronic paper By using this method, the power consumption of the display device 920 can be reduced.

[0171] Alternatively, as shown in Figure 7(B-2), the secondary battery 913 shown in Figures 6(A) and 6(B) can be connected to A sensor 921 may be provided. The sensor 921 is connected via terminal 922 and circuit board 900. It is electrically connected to terminal 911. Note that the energy storage device shown in Figures 6(A) and 6(B) For the same parts, the explanation of the energy storage device shown in Figures 6(A) and 6(B) can be appropriately referenced. .

[0172] Examples of sensors 921 include displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, and light. Liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, electric current, voltage, power, radiation, flow It should have the ability to measure quantity, humidity, gradient, vibration, odor, or infrared radiation. By providing the sensor 921, for example, data indicating the environment in which the energy storage device is located can be collected. It can also detect (temperature, etc.) and store it in the memory within circuit 912.

[0173] Furthermore, an example of the structure of the secondary battery 913 will be explained using Figures 8 and 9.

[0174] The secondary battery 913 shown in Figure 8(A) has terminals 951 and 952 inside the housing 930. It has a wound body 950. The wound body 950 is impregnated with an electrolyte inside the housing 930. Terminal 952 is in contact with the housing 930, and terminal 951 is in contact with the housing by using an insulating material or the like. It is not in contact with 930. Note that in Figure 8(A), for convenience, the housing 930 is shown separately. However, in reality, the wound body 950 is covered by the housing 930, and terminals 951 and 952 are It extends outside the casing 930. The casing 930 is made of a metal material (for example, aluminum). (or) or resin materials can be used.

[0175] Furthermore, as shown in Figure 8(B), the housing 930 shown in Figure 8(A) is formed from multiple materials. This is also possible. For example, the secondary battery 913 shown in Figure 8(B) consists of a housing 930a and a housing 930b The two are bonded together, and the winding body 950 is in the area enclosed by the housing 930a and housing 930b. It is provided.

[0176] For the casing 930a, insulating materials such as organic resin can be used. In particular, the antenna By using a material such as organic resin on the surface where the electric field of the secondary battery 913 is formed, Shielding can be suppressed. Furthermore, if the shielding of the electric field by the housing 930a is small, the housing 930a Antennas such as antenna 914 and antenna 918 may be installed inside. For example, metal materials can be used.

[0177] Furthermore, the structure of the wound body 950 is shown in Figure 9. The wound body 950 consists of a negative electrode 931 and a positive electrode It has 932 and a separator 933. The wound body 950 is sandwiched between the separator 933 The negative electrode 931 and the positive electrode 932 are stacked on top of each other, and the stacked sheet is wound up to form a wound body. Yes. Furthermore, multiple stacks of the negative electrode 931, positive electrode 932, and separator 933 are possible. They can be stacked.

[0178] The negative electrode 931 is connected to terminal 911 shown in Figure 6 via either terminal 951 or terminal 952. The positive terminal 932 is connected to terminal 911 shown in Figure 6 via terminal 951 and the other terminal of terminal 952. Connected.

[0179] By using the positive electrode active material described in the previous embodiment for the positive electrode 932, high capacity cycle This allows for the creation of a secondary battery 913 with superior characteristics.

[0180] [Laminated rechargeable battery] Next, an example of a laminate-type secondary battery will be explained with reference to Figures 10 to 15. If a laminate-type secondary battery has a flexible structure, the number of flexible parts can be reduced. If implemented in electronic devices that also possess some of these features, the secondary battery can also be bent in accordance with the deformation of the electronic device. can.

[0181] Using Figure 10, we will explain the laminated secondary battery 980. The battery 980 has a wound body 993 as shown in Figure 10(A). The wound body 993 has a negative electrode 994 It has a positive electrode 995 and a separator 996. The winding body 993 is a winding as explained in Figure 9 Similar to the rotating body 950, the negative electrode 994 and the positive electrode 995 overlap with the separator 996 in between. These are laminated sheets, and the laminated sheets are then rolled up.

[0182] The number of layers in the stack consisting of the negative electrode 994, positive electrode 995, and separator 996 is the required number of layers. The design should be appropriate depending on the capacitance and element volume. The negative electrode 994 is connected to the lead electrode 997 and the lead One side of the electrode 998 is connected to the negative electrode current collector (not shown), and the positive electrode 995 is connected to the lead electrode It is connected to a positive electrode current collector (not shown) via pole 997 and the other of lead electrode 998.

[0183] As shown in Figure 10(B), there is a film 981 which will be the outer casing and a film 98 which has a recess. The aforementioned coiled body 993 is housed in the space formed by bonding 2 together by heat pressing or the like. As a result, a secondary battery 980 can be manufactured as shown in Figure 10(C). (Winding body 99) 3 has lead electrodes 997 and 998, a film 981 and a recess The film 982 is impregnated with an electrolyte solution inside it.

[0184] Film 981 and film 982 having a recess are made of a metal material such as aluminum. or resin materials can be used. Film 981 and film 982 having recesses If a resin material is used as the material, when an external force is applied, the film 981 and the recess will To create a rechargeable battery in which the film 982 can be deformed and is flexible. It is possible.

[0185] Furthermore, Figures 10(B) and 10(C) show examples using two films, A space is formed by folding a single film, and the aforementioned wound body 99 is placed in that space. You may store 3.

[0186] By using the positive electrode active material described in the previous embodiment for the positive electrode 995, high capacity cycle This allows for the creation of a secondary battery 980 with superior characteristics.

[0187] Figure 10 also shows a secondary battery 9 having a wound body in a space formed by a film that serves as the outer casing. I have explained 80 examples, but for example, as shown in Figure 11, the shape is formed by the film that forms the outer casing. In the resulting space, it can also be used as a secondary battery having multiple strip-shaped positive electrodes, separators, and negative electrodes. good.

[0188] The laminated secondary battery 500 shown in Figure 11(A) consists of a positive electrode current collector 501 and a positive electrode active material The positive electrode 503 has a solid layer 502, and the negative electrode has a current collector 504 and a negative electrode active material layer 505. It has a negative electrode 506, a separator 507, an electrolyte 508, and an outer casing 509. A separator 507 is installed between the positive electrode 503 and the negative electrode 506 located within the body 509. It is. Also, the inside of the outer casing 509 is filled with electrolyte 508. The electrolyte 508 contains actual The electrolyte shown in Form 2 of the application can be used.

[0189] In the laminate-type secondary battery 500 shown in Figure 11(A), the positive electrode current collector 501 and the negative electrode current collector are... The polar current collector 504 also serves as a terminal for obtaining electrical contact with the outside. Therefore, it is the positive electrode. Parts of the current collector 501 and the negative electrode current collector 504 are exposed to the outside from the outer casing 509. They may also be arranged in this manner. Furthermore, the positive electrode current collector 501 and the negative electrode current collector 504 may be separated from the outer casing 509. Without exposing it to the outside, lead electrodes are used to connect the lead electrodes to the positive electrode current collector 501, or to the negative electrode. The lead electrodes may be exposed to the outside by ultrasonic bonding with the current collector 504.

[0190] In the laminated secondary battery 500, the outer casing 509 is made of, for example, polyethylene, poly On a film made of materials such as propylene, polycarbonate, ionomer, and polyamide, A highly flexible metal thin film such as aluminum, stainless steel, copper, or nickel is provided, and further, the gold An insulating synthetic resin such as polyamide resin or polyester resin is used as the outer surface of the outer casing on a thin film. A three-layer laminate film with a lipid film can be used.

[0191] Furthermore, an example of the cross-sectional structure of the laminate-type secondary battery 500 is shown in Figure 11(B). In A), for simplicity, an example consisting of two current collectors is shown, but in reality, multiple electrode layers are used. It consists of:

[0192] In Figure 11(B), the number of electrode layers is set to 16 as an example. However, the secondary battery 500 is flexible. In Figure 11(B), the negative electrode current collector 504 has 8 layers, The positive electrode current collector 501 has a structure of 8 layers, for a total of 16 layers. Figure 11(B) shows the negative electrode This shows a cross-section of the extraction section, where eight layers of negative electrode current collectors 504 are ultrasonically bonded. The number of electrode layers is not limited to 16; it can be more or fewer. This allows for the creation of a secondary battery with a larger capacity. Also, in cases where the number of electrode layers is small... In combination, it is possible to create a rechargeable battery that is thin and highly flexible.

[0193] Here, an example of the external view of the laminate-type secondary battery 500 is shown in Figures 12 and 13. Figure 1 Figures 2 and 13 show the positive electrode 503, negative electrode 506, separator 507, casing 509, and positive electrode lead. It has a lead electrode 510 and a negative lead electrode 511.

[0194] Figure 14(A) shows the external view of the positive electrode 503 and the negative electrode 506. The positive electrode 503 is the positive electrode current collector 50 The positive electrode has a positive electrode active material layer 502 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). Negative electrode 506 has a negative electrode current collector 504, and the negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. Furthermore, the negative electrode 506 is the region where the negative electrode current collector 504 is partially exposed, i.e., the tab region. It has a tab region. The area and shape of the tab regions of the positive and negative electrodes are not limited to the example shown in Figure 14(A). I can't.

[0195] [Method for manufacturing laminated rechargeable batteries] Here, an example of a method for manufacturing a laminate-type secondary battery, as shown in Figure 12, is presented in Figure 14. We will explain using (B) and (C).

[0196] First, the negative electrode 506, separator 507, and positive electrode 503 are stacked. (See Figure 14(B) for details.) The negative electrode 506, separator 507, and positive electrode 503 are shown. Here, there are 5 sets of negative electrodes and 5 sets of positive electrodes. An example of using four sets is shown. Next, the joining of the tab regions of the positive electrode 503 and the tab of the outermost positive electrode. The positive lead electrode 510 is joined to the region. For joining, for example, ultrasonic welding can be used. Good. Similarly, the bonding of the tab regions of the negative electrode 506 and the negative electrode connection to the tab region of the outermost negative electrode The electrode 511 is joined.

[0197] Next, the negative electrode 506, separator 507, and positive electrode 503 are placed on the outer casing 509.

[0198] Next, as shown in Figure 14(C), the outer casing 509 is folded at the part indicated by the dashed line. Next, the outer perimeter of the exterior body 509 is joined. For joining, for example, heat compression bonding may be used. In order to allow the electrolyte 508 to be added later, a part (or one side) of the outer casing 509 A region that is not connected (hereinafter referred to as the inlet) is provided.

[0199] Next, the electrolyte 508 is introduced into the inside of the outer casing 509 through the inlet provided in the outer casing 509. The introduction of electrolyte 508 is preferably carried out under a reduced pressure atmosphere or an inert gas atmosphere. And finally, the inlet is joined. In this way, the laminated secondary battery A certain secondary battery 500 can be manufactured.

[0200] By using the positive electrode active material described in the previous embodiment for the positive electrode 503, high capacity cycle This allows for the creation of a secondary battery 500 with superior characteristics.

[0201] [Bendable rechargeable battery] Next, an example of a bendable secondary battery will be described with reference to Figures 15 and 16. .

[0202] Figure 15(A) shows a schematic top view of the bendable battery 250. Figure 15(B1), (B2) and (C) correspond to the cutting lines C1-C2 and C3-C4 in Figure 15(A), respectively. This is a schematic cross-sectional view at the cutting line A1-A2. The battery 250 consists of an outer casing 251 and an outer casing It has a positive electrode 211a and a negative electrode 211b housed inside 251. The positive electrode 211a and the negative electrode Lead 212a is electrically connected to the negative electrode 211b, and lead 21 is electrically connected to the negative electrode 211b. 2b extends to the outside of the outer casing 251. Also, within the area enclosed by the outer casing 251, In addition to electrode 211a and negative electrode 211b, an electrolyte (not shown) is sealed inside.

[0203] The positive electrode 211a and negative electrode 211b of the battery 250 will be explained using Figure 16. Figure 16(A) illustrates the stacking order of the positive electrode 211a, the negative electrode 211b, and the separator 214. This is a perspective view. Figure 16(B) shows the positive electrode 211a and the negative electrode 211b, in addition to lead 2 This is a perspective view showing lead 12a and lead 212b.

[0204] As shown in Figure 16(A), the battery 250 has multiple strip-shaped positive electrodes 211a, multiple strip-shaped It has a negative electrode 211b and a plurality of separators 214. Positive electrode 211a and negative electrode 211 Each of b has a protruding tab portion and a portion other than the tab. One side of the positive electrode 211a A positive electrode active material layer is formed in the portion other than the tab, and in the portion other than the tab on one side of the negative electrode 211b A negative electrode active material layer is formed.

[0205] The sides of the positive electrode 211a where the positive electrode active material layer is not formed, and the negative electrode active material of the negative electrode 211b The positive electrode 211a and the negative electrode 211b are stacked so that surfaces without a formed surface are in contact with each other. It can be done.

[0206] Furthermore, the surface on which the positive electrode active material of the positive electrode 211a is formed and the surface on which the negative electrode active material of the negative electrode 211b is formed A separator 214 is provided between the surfaces. In Figure 16(A), the separator is shown for clarity. Reference numeral 214 is shown as a dotted line.

[0207] Also, as shown in Figure 16(B), the multiple positive electrodes 211a and leads 212a are connected at the joint 215 They are electrically connected at a. The multiple negative electrodes 211b and leads 212b are connected at joint 2 Electrically connected at 15b.

[0208] Next, the exterior body 251 will be explained using Figures 15(B1), (B2), (C), and (D). ru.

[0209] The outer casing 251 has a film-like shape and sandwiches the positive electrode 211a and the negative electrode 211b. It is folded in two. The outer casing 251 has a folded portion 261 and a pair of sealing portions 2 It has 62 and a sealing portion 263. The pair of sealing portions 262 are positive electrode 211a and negative electrode It is provided on either side of pole 211b and can also be called a side seal. Also, seal portion 26 3 has a portion that overlaps with leads 212a and 212b, and is also called the top seal. It is possible.

[0210] The outer casing 251 has a ridge line 271 and a valley line 2 in the portion that overlaps with the positive electrode 211a and the negative electrode 211b. It is preferable that the 72 have a wave shape arranged alternately. Also, the sealing portion 26 of the outer casing 251 2 and the sealing portion 263 are preferably flat.

[0211] Figure 15(B1) shows a cross-section cut at the point where it overlaps with ridge line 271, and Figure 15(B2) shows... This is a cross-section taken at the point where it overlaps with valley line 272. Figures 15(B1) and (B2) both show the battery. This corresponds to the cross-section in the width direction of 250 and the positive electrode 211a and the negative electrode 211b.

[0212] Here, the distance La is defined as the distance between the end of the negative electrode 211b in the width direction and the seal portion 262. When the battery 250 is deformed, such as by bending, the positive electrode 211a and the negative electrode will be affected, as will be described later. 211b deforms so that it is shifted relative to itself in the longitudinal direction. In this case, if the distance La is too short, the outer The housing 251 rubbed strongly against the positive electrode 211a and the negative electrode 211b, causing damage to the outer casing 251. In some cases, this can occur. In particular, if the metal film of the outer casing 251 is exposed, the metal film may become electrical. There is a risk of corrosion due to the dissolution solution. Therefore, set the distance La as long as possible. It is preferable to do so. On the other hand, if the distance La is made too large, the volume of the battery 250 will increase. Put it away.

[0213] Furthermore, the thicker the combined thickness of the stacked positive electrode 211a and negative electrode 211b, the greater the negative electrode 211 It is preferable to increase the distance La between b and the seal portion 262.

[0214] More specifically, stacked positive electrode 211a and negative electrode 211b and separate (not shown) When the total thickness of -214 is denoted as thickness t, the distance La is 0.8 times the thickness t or greater than 3.0. Two times or less, preferably 0.9 times or more and 2.5 times or less, more preferably 1.0 times or more and 2.0 times or less It is preferable that it be lower. By setting the distance La to this range, it becomes compact and easy to bend. This enables the creation of highly reliable batteries.

[0215] Furthermore, when the distance between the pair of sealing portions 262 is denoted as distance Lb, distance Lb is set to the negative electrode 211b It is preferable to make it sufficiently larger than the width Wb. This prevents repeated bending of the battery 250. When deformation such as is applied, the positive electrode 211a and the negative electrode 211b come into contact with the outer casing 251. Even if this is done, a portion of the positive electrode 211a and the negative electrode 211b can be shifted in the width direction, To effectively prevent friction between the electrode 211a and the negative electrode 211b and the outer casing 251. It is possible.

[0216] For example, the difference between the distance Lb between the pair of sealing portions 262 and the width Wb of the negative electrode 211b is the positive electrode The thickness t of 211a and the negative electrode 211b is 1.6 times or more and 6.0 times or less, preferably 1.8 times. It is preferable that the ratio is 5.0 times or less, and more preferably 2.0 times or more and 4.0 times or less. .

[0217] In other words, it is preferable that the distance Lb, width Wb, and thickness t satisfy the relationship shown in Equation 1 below. It's nice.

[0218]

number

[0219] Here, a is 0.8 or more and 3.0 or less, preferably 0.9 or more and 2.5 or less, more preferably It satisfies the condition of being between 1.0 and 2.0.

[0220] Furthermore, Figure 15(C) shows a cross-section including lead 212a, battery 250, positive electrode 211a and This corresponds to the longitudinal cross-section of the negative electrode 211b. As shown in Figure 15(C), the bent portion 2 In 61, the longitudinal ends of the positive electrode 211a and the negative electrode 211b and the outer casing 251 It is preferable to have a space 273 in between.

[0221] Figure 15(D) shows a schematic cross-sectional view of the battery 250 when bent. Figure 15(D) is This corresponds to the cross-section at the cutting line B1-B2 in Figure 15(A).

[0222] When the battery 250 is bent, a portion of the outer casing 251 located on the outside of the bend stretches, while the portion located on the inside stretches. Other parts deform by shrinking. More specifically, the parts located on the outside of the outer casing 251. It deforms so that the amplitude of the wave is small and the period of the wave is large. On the other hand, the outer casing 251 The part located inside the curve deforms such that the wave amplitude is large and the wave period is small. In this way, as the outer casing 251 deforms, the force acting on the outer casing 251 due to bending Because the stress is relieved, the material that makes up the exterior 251 does not need to expand or contract. As a result, the outer casing 251 can be bent with minimal force without damaging the battery 250.

[0223] Also, as shown in Figure 15(D), when the battery 250 is bent, the positive electrode 211a and the negative electrode 21 1b and the other are relatively shifted. At this time, multiple stacked positive electrodes 211a and negative electrodes Since one end of 211b on the sealing portion 263 side is fixed by the fixing member 217, it can be bent. Each part shifts in such a way that the amount of shift increases the closer it is to part 261. As a result, the positive electrode 21 The stress on 1a and the negative electrode 211b is relieved, and the positive electrode 211a and the negative electrode 211b themselves There is no need for expansion or contraction. As a result, the positive electrode 211a and the negative electrode 211b are not damaged. The 250 battery can be bent.

[0224] Furthermore, there is a space 273 between the ends of the positive electrode 211a and the negative electrode 211b and the outer casing 251. As a result, when bent, the ends of the positive electrode 211a and negative electrode 211b located on the inside However, it can shift relative to the outer casing 251 without coming into contact with it.

[0225] The battery 250 illustrated in Figures 15 and 16 can withstand repeated bending and straightening, and the outer casing remains intact. Damage, such as breakage of the positive electrode 211a and negative electrode 211b, is less likely to occur, and the battery characteristics are less likely to deteriorate. This is a battery. The positive electrode 211a of the battery 250 is the positive electrode active material described in the previous embodiment. By using higher quality materials, it is possible to create batteries with even higher capacity and superior cycle characteristics.

[0226] (Embodiment 4) This embodiment describes an example in which a secondary battery, which is one aspect of the present invention, is mounted in an electronic device. do.

[0227] First, as described in part of Embodiment 3, a bendable secondary battery is mounted in an electronic device. An example is shown in Figure 17. An example of an electronic device using a bendable secondary battery is, for instance, a te Revision devices (also called televisions or television receivers), computers, etc. Nita, digital cameras, digital video cameras, digital photo frames, mobile phones ( Mobile phones (also called mobile phone devices), portable game consoles, personal information terminals, sound playback devices, Examples include large game machines such as penis-shaped machines.

[0228] Furthermore, rechargeable batteries with flexible shapes can be installed in the interior or exterior walls of houses and buildings, or in automobiles. It can also be incorporated along the curved surfaces of the interior or exterior.

[0229] Figure 17(A) shows an example of a mobile phone. Mobile phone 7400 has a housing 7401 In addition to the display unit 7402 incorporated into it, there are operation buttons 7403, an external connection port 7404, and It is equipped with a speaker 7405, a microphone 7406, etc. Note that the mobile phone 7400 is secondary. It has a battery 7407. The secondary battery 7407 of the present invention is used This allows us to provide lightweight and long-lasting mobile phones.

[0230] Figure 17(B) shows the mobile phone 7400 in a curved state. Mobile phone 740 When the 0 is deformed by an external force and the whole thing is bent, the secondary battery located inside is revealed. The 7407 is also bent. Figure 17(C) shows the state of the bent secondary battery 7407 at that time. As shown in the diagram, the 7407 secondary battery is a thin rechargeable battery. The 7407 secondary battery is in a bent state. It is fixed in place. Furthermore, the secondary battery 7407 is electrically connected to the current collector 7409. It has an electrode 7408.

[0231] Figure 17(D) shows an example of a bangle-type display device. The portable display device 7100 is The device comprises a housing 7101, a display unit 7102, operation buttons 7103, and a secondary battery 7104. Figure 17(E) also shows the state of the bent secondary battery 7104. The secondary battery 7104 is bent. When worn on the user's arm in a distorted state, the casing deforms, causing part of the secondary battery 7104 or All curvatures change. Note that the degree of curvature at any point in the curve is equal to the radius of the corresponding circle. The value expressed as such is the radius of curvature, and the reciprocal of the radius of curvature is called the curvature. Specifically, the radius of curvature Within a range of 40mm to 150mm, a portion of the main surface of the housing or secondary battery 7104 The whole thing changes. The radius of curvature on the main surface of secondary battery 7104 is 40 mm or more and 150 High reliability can be maintained within a range of mm or less. The present invention applies to the secondary battery 7104 described above. By using one embodiment of a secondary battery, a lightweight and long-lasting portable display device can be provided.

[0232] Figure 17(F) shows an example of a wristwatch-type personal information terminal. The personal information terminal 7200 is , housing 7201, display unit 7202, band 7203, buckle 7204, operation button 72 05. It is equipped with input / output terminals 7206, etc.

[0233] The 7200 mobile information terminal offers mobile phone, email, document viewing and creation, music playback, and internet connectivity. - It can run various applications such as network communication and computer games. ru.

[0234] The display unit 7202 has a curved display surface, and displays are made along the curved display surface. It can do this. In addition, the display unit 7202 is equipped with a touch sensor, allowing you to touch the screen with your finger or stylus. It can be operated by touching it. For example, the icon 72 displayed on the display unit 7202 Touching 07 will launch the application.

[0235] The 7205 control button is used for setting the time, turning the power on and off, and turning wireless communication on and off. It has various functions such as operation, silent mode activation and deactivation, and power saving mode activation and deactivation. This can be done. For example, the operating system built into the mobile information terminal 7200 The stem also allows you to freely configure the function of the control button 7205.

[0236] Furthermore, the 7200 portable information terminal is capable of performing standardized short-range wireless communication. Yes, for example, by communicating with a wireless headset, hands-free operation is possible. You can also make phone calls.

[0237] Furthermore, the portable information terminal 7200 is equipped with an input / output terminal 7206, and connects to other information terminals via a connector. It can directly exchange data via this. It can also be charged via input / output terminal 7206. It is also possible to perform this operation. Note that charging is performed wirelessly without using input / output terminal 7206. That's fine.

[0238] The display unit 7202 of the portable information terminal 7200 has a secondary battery according to one embodiment of the present invention. By using a secondary battery according to one aspect of the present invention, a lightweight and long-lasting portable information terminal can be provided. For example, the secondary battery 7104 shown in Figure 17(E) is placed inside the housing 7201 in a curved state. Alternatively, it can be incorporated into the band 7203 in a flexible state.

[0239] The personal information terminal 7200 preferably has a sensor. For example, a fingerprint sensor. Human body sensors such as pulse sensors and body temperature sensors, as well as touch sensors, pressure sensors, and acceleration sensors. It is preferable that the following are installed:

[0240] Figure 17(G) shows an example of an armband-type display device. The display device 7300 consists of a display unit 7 The present invention has a secondary battery having 304. The display device 7300 is a table The display unit 7304 can also be equipped with a touch sensor, and it can also function as a portable information terminal. It is also possible.

[0241] The display unit 7304 has a curved display surface, and displays are made along the curved display surface. Yes, it is possible. Furthermore, the display device 7300 can communicate via standardized short-range wireless communication, etc. The situation can be changed.

[0242] Furthermore, the display device 7300 is equipped with input / output terminals and can be directly connected to other information terminals via connectors. It can exchange data. It can also be charged via input / output terminals. Furthermore, charging may be performed wirelessly without using input / output terminals.

[0243] By using a secondary battery according to one aspect of the present invention as the secondary battery of the display device 7300, We can provide display devices with a long lifespan in large quantities.

[0244] Next, Figures 18(A) and 18(B) show an example of a foldable tablet device. The tablet terminal 9600 shown in Figures 18(A) and 18(B) has a housing 9630. a, housing 9630b, movable part 9640 connecting housing 9630a and housing 9630b, display Section 9631, display mode switching switch 9626, power switch 9627, power saving mode It has a toggle switch 9625, a fastener 9629, and an operating switch 9628. Section 9631 uses a flexible panel, allowing for a tablet with a wider display area. It can be used as a tablet terminal. Figure 18(A) shows the tablet terminal 9600 in an open state. Figure 18(B) shows the tablet terminal 9600 in a closed state.

[0245] Furthermore, the tablet terminal 9600 stores energy inside the housings 9630a and 9630b. It has a body 9635. The energy storage body 9635 passes through the movable part 9640 and the housing 9630a and housing It is located across 9630b.

[0246] The display unit 9631 can be partially designated as a touch panel area, and the displayed operation keys can be accessed. Data can be entered by touching the screen. Additionally, the touchscreen keyboard display can be turned off. By touching the location where the replacement button is displayed with your finger or stylus, the display unit 9631 will activate. Keyboard buttons can be displayed.

[0247] Additionally, the display mode switch 9626 switches the display orientation, such as portrait or landscape. You can switch between black and white and color displays. Power saving mode switch. The 9625 is detected by the light sensor built into the tablet terminal 9600 when in use. The display brightness can be optimized according to the amount of ambient light. In addition to optical sensors, other detection sensors such as gyroscopes and accelerometers that detect tilt are also used. The device may be built-in.

[0248] Figure 18(B) shows the closed state, and the tablet terminal consists of a housing 9630 and a solar cell 96 33. It has a charge / discharge control circuit 9634 including a DC-DC converter 9636. Also, an energy storage unit As 9635, a secondary battery according to one aspect of the present invention is used.

[0249] Furthermore, since the tablet device 9600 is foldable, when not in use, the casing 9630a and The casing 9630b can be folded so that it overlaps with the other casing. By folding it, Since the display unit 9631 can be protected, the durability of the tablet terminal 9600 can be increased. It can. Furthermore, the energy storage unit 9635 using a secondary battery according to one embodiment of the present invention has high capacity and good cycle Because it possesses certain characteristics, we can provide a tablet device that can be used for extended periods of time over a long period of time. ru.

[0250] In addition, the tablet devices shown in Figures 18(A) and 18(B) are also available in various forms. Functions to display information (still images, videos, text images, etc.), calendar, date or time, etc. A function that displays information on the display unit, and a touch input operation or editing of the information displayed on the display unit. It has input capabilities, and functions to control processing through various software (programs), etc. It is possible.

[0251] The solar cell 9633 mounted on the surface of the tablet device powers the touch panel. It can be supplied to the display unit or the video signal processing unit, etc. Note that the solar cell 9633 is housed in a casing. A structure that can be provided on one or both sides of the body 9630 and efficiently charges the energy storage body 9635. It can be considered a success.

[0252] Furthermore, the configuration and operation of the charge / discharge control circuit 9634 shown in Figure 18(B) are shown in Figure 18( A block diagram is shown and explained in C). Figure 18(C) shows the solar cell 9633 and the energy storage unit 963. 5. DC-DC converter 9636, converter 9637, switch SW1 to SW3, table The diagram shows the section 9631, and includes the energy storage unit 9635, the DC-DC converter 9636, and the capacitor. The converter 9637 and switches SW1 to SW3 are connected to the charge / discharge control circuit 96 shown in Figure 18(B). This corresponds to section 34.

[0253] First, let's explain an example of operation when electricity is generated by the solar cell 9633 using ambient light. The electricity generated by the solar panel is converted to a DC-DC converter to provide the voltage needed to charge the 9635 energy storage unit. The converter 9636 performs voltage boosting or de-voltage adjustment. Then, the solar cell controls the operation of the display unit 9631. When power from 9633 is used, switch SW1 is turned ON, and converter 9637 The voltage is then boosted or lowered to the voltage required for the display unit 9631. If you do not want the display to work, turn SW1 off and SW2 on to charge the battery 9635. The configuration should be designed to handle electricity.

[0254] The solar cell 9633 is shown as an example of a power generation method, but it is not particularly limited to this method. Energy storage using other power generation methods such as electrical elements (piezo elements) and thermoelectric conversion elements (Peltier elements) The configuration may also involve charging the body 9635. For example, power may be transmitted and received wirelessly (contactlessly). This configuration uses a contactless power transmission module for charging, or a combination of other charging methods. That's fine.

[0255] Figure 19 shows an example of another electronic device. In Figure 19, the display device 8000 is part of the present invention. This is an example of an electronic device using a secondary battery 8004 according to the embodiment. Specifically, the display device 800 0 corresponds to a display device for receiving TV broadcasts, and consists of a housing 8001, a display unit 8002, and a speaker unit. The invention includes 8003, a secondary battery 8004, etc. A secondary battery 8004 according to one aspect of the present invention has a housing It is located inside the body 8001. The display device 8000 receives power from the commercial power supply. It can be used to power the device, or it can use the power stored in the secondary battery 8004. Even when power cannot be supplied from the commercial power source due to a power outage, etc., according to one aspect of the present invention By using the secondary battery 8004 as an uninterruptible power supply, the display device 8000 can be used. ru.

[0256] The display unit 8002 has light-emitting elements such as liquid crystal display devices and organic EL elements in each pixel. Equipment, electrophoresis display device, DMD (Digital Micromirror Display) ce), PDP (Plasma Display Panel), FED (Field Semiconductor display devices such as Emission Displays can be used.

[0257] In addition to being used for receiving TV broadcasts, display devices are also used for personal computers, advertising displays, and more. This includes all information display devices.

[0258] In Figure 19, the fixed lighting device 8100 is a secondary battery 81 according to one aspect of the present invention. This is an example of an electronic device using 03. Specifically, the lighting device 8100 has a housing 8101 and light It has a power source 8102, a secondary battery 8103, etc. In Figure 19, the secondary battery 8103 is located in the housing 81 An example is provided where 01 and the light source 8102 are installed inside the ceiling 8104. However, the secondary battery 8103 may also be located inside the housing 8101. The 8100 can receive power from the commercial power supply, or it can store power in the secondary battery 8103. It is also possible to use the accumulated power. Therefore, if power is not supplied from the commercial power source due to a power outage, etc. Even when it is not possible to receive a power supply, the secondary battery 8103 according to one aspect of the present invention can be used as an uninterruptible power supply. This makes it possible to use the lighting device 8100.

[0259] Note that Figure 19 illustrates a fixed lighting device 8100 installed on the ceiling 8104. However, in one aspect of the present invention, the secondary battery is located in a location other than the ceiling 8104, for example, the side wall 8105, the floor 8 106, It can also be used in fixed lighting devices installed in windows 8107, etc., and on a tabletop It can also be used in lighting fixtures and other similar devices.

[0260] Furthermore, the light source 8102 can be an artificial light source that uses electricity to artificially produce light. Specifically, this includes incandescent light bulbs, discharge lamps such as fluorescent lamps, and light-emitting elements such as LEDs and organic EL elements. The element is an example of the artificial light source mentioned above.

[0261] In Figure 19, an air conditioner having an indoor unit 8200 and an outdoor unit 8204, This is an example of an electronic device using a secondary battery 8203 according to one aspect of the present invention. Specifically, indoor The unit 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, etc. (Figure 19) This example illustrates the case where the secondary battery 8203 is provided in the indoor unit 8200, but Battery 8203 may be located in the outdoor unit 8204. Alternatively, it may be located in the indoor unit 8200 and the outdoor unit. The secondary battery 8203 may be provided on both sides of the unit 8204. (Air conditioner) It can receive power from the commercial power supply, or from the electricity stored in the secondary battery 8203. It can also use force. In particular, both the indoor unit 8200 and the outdoor unit 8204 can use secondary batteries 82 If 03 is provided, when power cannot be supplied from the commercial power source due to a power outage, etc. Furthermore, by using the secondary battery 8203 according to one aspect of the present invention as an uninterruptible power supply, an air conditioner can be used. Conditioner can be used.

[0262] Note that Figure 19 shows a separate-type air conditioner consisting of an indoor unit and an outdoor unit. As an example, an integrated air conditioner has both the indoor and outdoor unit functions in a single housing. A secondary battery according to one aspect of the present invention can also be used in the conditioner.

[0263] In Figure 19, the electric refrigerator 8300 is powered by a secondary battery 8304 according to one aspect of the present invention. This is an example of the electronic equipment used. Specifically, the electric refrigerator 8300 consists of a casing 8301 and a refrigerator. It has a storage room door 8302, a freezer room door 8303, a secondary battery 8304, etc. In Figure 19, two The next battery 8304 is located inside the casing 8301. The electric refrigerator 8300 is, It can receive power from the commercial power supply, or it can use the power stored in the secondary battery 8304. It can also be used. Therefore, when power cannot be supplied from the commercial power source due to a power outage, etc. However, by using the secondary battery 8304 according to one aspect of the present invention as an uninterruptible power supply, electric cooling The 8300 freezer / refrigerator will become available for use.

[0264] Furthermore, during periods when electronic devices are not in use, especially the total amount of electricity that can be supplied by the commercial power source... Of these, during periods when the proportion of electricity actually used (called the electricity usage rate) is low, secondary By storing power in the battery, the rate of power consumption outside of the above-mentioned time period is suppressed. It is possible. For example, in the case of the electric refrigerator 8300, when the temperature is low, the refrigerator door 830 2. At night when the freezer door 8303 is not opened or closed, power is stored in the secondary battery 8304. And as the temperature rises, the refrigerator door 8302 and the freezer door 8303 are opened and closed. During the daytime, by using the secondary battery 8304 as an auxiliary power source, the daytime power usage rate It can be kept low.

[0265] In addition to the electronic devices described above, a secondary battery according to one aspect of the present invention can be mounted in any electronic device. According to one aspect of the present invention, the cycle characteristics of the secondary battery are improved. Depending on the embodiment, a high-capacity secondary battery can be made, and thus the secondary battery itself can be made smaller and lighter. Therefore, a secondary battery, which is one aspect of the present invention, is described in this embodiment. By incorporating this into electronic devices, it is possible to create electronic devices that have a longer lifespan and are lighter in weight. This embodiment can be implemented in appropriate combination with other embodiments.

[0266] (Embodiment 5) This embodiment shows an example in which a secondary battery according to one aspect of the present invention is mounted on a vehicle.

[0267] When a secondary battery is installed in a vehicle, it becomes a hybrid electric vehicle (HEV), an electric vehicle (EV), or a hybrid electric vehicle. This will enable the realization of next-generation clean energy vehicles such as plug-in hybrid electric vehicles (PHEVs). .

[0268] Figure 20 illustrates a vehicle using a secondary battery, which is one embodiment of the present invention. Figure 20(A) The automobile 8400 shown is an electric vehicle that uses an electric motor as a power source for driving. Yes. Alternatively, an electric motor and an engine can be appropriately selected and used as the power source for propulsion. This is a hybrid vehicle that can achieve the following: By using one aspect of the present invention, the driving range can be extended. This makes it possible to realize a vehicle. In addition, the 8400 automobile has a secondary battery. The secondary battery is The secondary battery modules shown in Figures 12(C) and 12(D) are positioned on the floor portion of the vehicle. You can use them by arranging them side by side. Also, a battery pack made by combining multiple secondary batteries as shown in Figure 17. It may be installed on the floor inside the vehicle. The secondary battery drives the electric motor 8406. In addition, it supplies power to light-emitting devices such as headlights 8401 and interior lights (not shown). They can provide it.

[0269] Furthermore, the secondary battery is used for the speedometer, tachometer, and other displays in the 8400 automobile. It can supply power to the device. In addition, the secondary battery is the navigation system of the 8400 automobile. It can supply power to semiconductor devices such as ignition systems.

[0270] The automobile 8500 shown in Figure 20(B) is a plug-in type of secondary battery that the automobile 8500 has. It can be charged by receiving power from an external charging facility using methods such as contactless power supply. Figure 20(B) shows the two devices mounted on the automobile 8500, connected to the ground-mounted charging device 8021. The next diagram shows the state in which the battery 8024 is being charged via cable 8022. Therefore, charging methods and connector specifications are subject to the standards of CHAdeMO (registered trademark) and Combo, etc. The method can be carried out as appropriate. The charging device 8021 is installed at a charging station in a commercial facility. It is also fine to use a household power supply. For example, plug-in technology allows for external power supply. The power supply can charge the secondary battery 8024 installed in the 8500 vehicle. Charging is performed by converting AC power to DC power via a conversion device such as an AC / DC converter. It is possible.

[0271] Although not shown in the diagram, a power receiving device is mounted on the vehicle, and power is supplied wirelessly from a ground-based power transmission device. It can also be charged by doing so. In this contactless power supply method, power transmission equipment is installed in roads or exterior walls. By incorporating this, charging can be performed not only when the vehicle is stopped but also while it is in motion. Furthermore, this contactless power supply... This method may be used to transmit and receive power between vehicles. Furthermore, the exterior of the vehicle Solar panels may be installed to charge the secondary battery when the vehicle is stopped or in motion. Electromagnetic induction or magnetic resonance methods can be used to supply power to it.

[0272] Furthermore, Figure 20(C) shows an example of a two-wheeled vehicle using a secondary battery according to one embodiment of the present invention. Figure 20 The scooter 8600 shown in (C) includes a secondary battery 8602, side mirrors 8601, and turn signals. It is equipped with a light 8603. The secondary battery 8602 supplies electricity to the turn signal light 8603. can.

[0273] Furthermore, the scooter 8600 shown in Figure 20(C) has a secondary battery 860 in the under-seat storage 8604. It can store 2. The secondary battery 8602 can be stored even if the under-seat storage 8604 is small. It can be stored in the under-seat storage compartment 8604. The secondary battery 8602 is removable. It is preferable that the secondary battery 8602 is carried indoors for charging, and then driven. It is preferable to store them before use.

[0274] According to one aspect of the present invention, the cycle characteristics of the secondary battery are improved, and the capacity of the secondary battery is increased. This makes it possible to make the secondary battery itself smaller and lighter. Making the body smaller and lighter contributes to reducing the vehicle's weight, which in turn improves its driving range. It is possible. Furthermore, the secondary battery installed in the vehicle can also be used as a power source for purposes other than the vehicle itself. In this case, for example, it is possible to avoid using commercial power during peak electricity demand. Therefore, if we can avoid using commercial power during peak electricity demand, we can save energy and It can contribute to reducing carbon dioxide emissions. Also, if the cycle characteristics are good, two Because the next battery can be used for a long period of time, the amount of rare metals used, including cobalt, can be reduced. It is possible.

[0275] This embodiment can be implemented in appropriate combination with other embodiments. [Examples]

[0276] In this embodiment, cobalt was used as the transition metal in the first region of the positive electrode active material. And a positive electrode active material prepared by adding magnesium and fluorine to the starting material, and comparative examples. We prepared a positive electrode active material without adding magnesium and fluorine, and analyzed its characteristics. Furthermore, the cycle characteristics were altered by changing the concentrations of magnesium and fluorine added to the starting material. I evaluated it.

[0277] <Preparation of positive electrode active materials for Samples 1 to 6> Cathode activity of samples 1 to 6 with varying concentrations of magnesium and fluorine sources. The material was fabricated. Lithium carbonate and cobalt oxide were used as common starting materials. Magnesium oxide and lithium fluoride were used as different additive starting materials for each batch.

[0278] Sample 1 contains 0.5 atomic% magnesium relative to the cobalt present in the common starting material. Magnesium oxide and fluorine are used to create a mixture containing fluorine and 1 atomic% fluorine. Lithium oxide was used as the additive starting material. Below, Sample 1 uses 0.5 ml as the additive starting material. This is expressed as using ol% MgO and 1 mol% LiF.

[0279] As described above, in this specification, the amount of additive starting material is determined by the transition metal contained in the common starting material. The percentage should be expressed in atomic% or mol%. The same applies to Sample 2 and subsequent samples. It will be written as follows.

[0280] Sample 2 uses 0.5 mol% MgO and 0.5 m³ of cobalt as additive starting materials. ol% LiF was used. Sample 3 used 0.5 mol% MgO as the starting material. 2 mol% LiF was used. Sample 4 was used as a comparative example, with 1 mol of added starting material. % LiF was used, and magnesium was not added. Sample 5 was used as a comparative example. 0.5 mol% MgO was used as the generating material, and no fluorine was added. Sample 6 was proportional For comparison, neither magnesium nor fluorine was added. Common output of each sample The starting materials and additives are shown in Table 1.

[0281] [Table 1]

[0282] For each of the six samples described above, the starting material was prepared in the same manner as described in Embodiment 1. Mix the ingredients, perform the first heating, cool, sift, perform the second heating, cool, The material was recovered to obtain the positive electrode active material. The particles were obtained during these processes, and also after these processes were completed. The following analysis was performed on the positive electrode active material.

[0283] <stem-edx> For Sample 1 and Sample 5 (comparative example), the cross-section near the surface of the particles before the second heating was analyzed using STEM-EDX. Figures 22 and 23 show the STEM-EDX images of Sample 1 and Sample 5 (comparative example) before the second heating, respectively. Figure 22(A) and Figure 23(A) are STEM images, Figure 22(B) and Figure 23(B) are magnesium mappings, and Figure 22(C) and Figure 23(C) are fluorine mappings.

[0284] As shown in Figure 22(B), in Sample 1 containing magnesium and fluorine in the starting material, it was observed that magnesium was segregated to some extent near the surface of the particles even before the second heating. The segregated region was about 1 nm to 2 nm from the surface of the particles.

[0285] On the other hand, as shown in the EDX mapping of Figure 23(B), in Sample 5 containing magnesium but not fluorine in the starting material, segregation of magnesium to the vicinity of the surface was not observed.

[0286] As shown in Figures 22(C) and 23(C), almost no fluorine was observed inside the positive electrode active material in both Sample 1 and Sample 5. This was considered to be because fluorine, which is a light element, is difficult to detect by EDX.

[0287] <X-ray Photoelectron Spectroscopy (XPS)> Next, for Sample 1 and Sample 5 (comparative example), the amount of magnesium near the surface of the positive electrode active material before and after the second heating was analyzed.

[0288] The conditions for XPS analysis were as follows. Measuring device: QuanteraII manufactured by PHI ​​​​​​X-ray source: Monochromatic Al (1486.6 eV) Detection area: 100 μmφ Detection depth: Approximately 4-5 nm (extraction angle 45°) Measurement spectrum: Wide, Li1s, Co2p, Ti2p, O1s, C1s, F1s, S 2p, Ca2p, Mg1s, Na1s, Zr3d

[0289] Table 2 shows the results of quantifying the concentration of each element using XPS. The quantitative accuracy is ±1ato. The detection limit is around 1 atomic%, although this varies depending on the element. Also, for Ca, the waveform is... Because the separated Mg Auger peak has been removed, the quantitative error is larger than usual.

[0290] Furthermore, Table 3 shows the results of calculating the abundance ratio of each element when cobalt is set to 1.

[0291] [Table 2]

[0292] [Table 3]

[0293] Furthermore, Figure 2 shows a graph of the elemental abundance ratios for magnesium, as shown in Table 3. This is shown in 4.

[0294] As shown in Tables 2, 3 and Figure 24, the additive starting material contains magnesium and fluorine. In sample 1, even before the second heating, magnets were observed near the surface of the positive electrode active material that could be measured by XPS. Magnesium was present. After the second heating, the amount of magnesium near the surface of the positive electrode active material further increased. It increased.

[0295] In other words, it is thought that the second heating process promoted the segregation of magnesium onto the surface of the positive electrode active material. Thus, the positive electrode active material of Sample 1 has a first region in the interior and a second region on the surface. It has a first region containing lithium cobaltate and a second region containing magnesium. It was confirmed to be an extremely active material.

[0296] On the other hand, in Sample 5, which contains only magnesium and no fluorine as an additive starting material, Before and after the second heating, the magnesium levels near the surface of the positive electrode active material were below the detection limit. Surprisingly, the fluorine contained in the starting material segregates magnesium to the surface layer of the positive electrode active material. It has been revealed that it has the effect of causing this.

[0297] <Cycle Characteristics> Next, we examine Sample 1 before and after the second heating, Sample 5 before and after the first heating, and Sample 2. Using the positive electrode active materials of Sample 3, Sample 4, and Sample 6, a CR2032 type (diameter 2 A coin-type secondary battery with dimensions of 0 mm (0 mm) and 3.2 mm (3 mm) was fabricated, and its cycle characteristics were evaluated.

[0298] The positive electrode contains the positive electrode active material prepared above, acetylene black (AB), and polyfluoride. Nylidene (PVDF) as the positive electrode active material: AB:PVDF = 95:2.5:2.5 (by weight) A slurry mixed with the other materials was used as a coating for the current collector.

[0299] Lithium metal was used for the counter electrode.

[0300] The electrolyte in the electrolyte solution is 1 mol / L lithium hexafluoride phosphate (LiPF6). The electrolyte contains ethylene carbonate (EC) and diethyl carbonate (DEC). C:DEC = 3:7 (volume ratio), with vinylene carbonate (VC) mixed at 2% by weight. They used something.

[0301] The positive electrode and negative electrode cans were made of stainless steel (SUS).

[0302] The measurement temperature for the cycle characteristics test was set to 25°C. The charging current density was 68 per unit weight of active material. The test is performed with a constant current of 0.5 mA / g and an upper voltage limit of 4.6 V, after which the current density becomes 1.4 mA / g. Constant voltage charging was performed until [a certain value was reached]. Discharge was performed using a constant voltage with a current density of 68.5 mA / g per unit weight of active material. The tests were conducted with a minimum voltage of 2.5V. Each battery underwent 30 charge-discharge cycles.

[0303] Figures 25(A) and 25(B) show the second heating of Sample 1 and the second heating of Sample 5. Figure 25(A) shows a graph of the cycle characteristics of a secondary battery using the positive electrode active material before and after heating. ) is the energy density when charging at 4.6V, and Figure 25(B) is the energy density when charging at 4.6V. This is a graph of the maintenance rate. Note that energy density is the product of the discharge capacity and the average discharge voltage.

[0304] As shown in Figure 25, in Sample 1, which has magnesium and fluorine in the additive starting material, By performing heating step 2, the cycle characteristics were significantly improved. Furthermore, the energy density was also good. Ta.

[0305] As was evident from the XPS results mentioned above, by performing a second heating, the correct This is thought to be due to an increase in the amount of magnesium present near the surface of the highly active material.

[0306] On the other hand, in sample 5, which had only magnesium as the additive starting material, before and after the second heating: No significant differences were observed in the cycle characteristics.

[0307] Next, Figures 26 and 27 show the positive electrode active materials of samples 1 to 6 after the second heating. The graph shows the cycle characteristics of the secondary battery. Figure 26 shows the energy density when charged at 4.6V. The graph in Figure 27 shows the energy density maintenance rate when charging at 4.6V.

[0308] As shown in Figures 26 and 27, Sample 4 (Comparative Example) had only fluorine added to the starting material. ), Sample 5 (comparative example), in which only magnesium was added, contained magnesium and fluorine. It showed inferior cycle characteristics compared to Sample 6 (comparative example), which did not contain the additive.

[0309] On the other hand, samples 1 to 3, in which magnesium and fluorine were added to the starting material, performed well. It showed excellent cycling characteristics. The best cycling characteristics were observed in magnesium and fluorine. Sample 1 had an atomic ratio of 1:2. Next, the ratio of magnesium to fluorine content. Sample 2, with a ratio of 1:4, showed good cycle characteristics. Also, as is clear from Figure 26... Furthermore, it exhibited not only good cycle characteristics but also excellent energy density.

[0310] In this way, by adding magnesium and fluorine to the starting material, good cycle characteristics can be achieved. It was revealed that the positive electrode active material shown can be obtained. Furthermore, the magnesium contained in the starting material The atomic ratio of Mg to fluorine is preferably Mg:F=1:x (1.5≦x≦4), and Mg:F= It was found that a ratio of approximately 1:2 is the most preferable.

[0311] <Preparation of positive electrode active materials for samples 7 and 8> Next, the amount of magnesium added was changed while keeping the ratio of magnesium to fluorine constant (Mg:F=1:2). The positive electrode active materials for Sample 7 and Sample 8 were then prepared.

[0312] Sample 7 used 1 mol% MgO and 2 mol% LiF as additive starting materials. Sample 8 used 2 mol% MgO and 4 mol% LiF as additive starting materials. For Sample 7 and Sample 8, the same manufacturing method as described in Embodiment 1 was used. The starting materials are mixed, heated for the first time, cooled, sieved, and then heated for the second time. The material was then cooled, recovered, and used to create a positive electrode active material, which in turn led to the construction of a secondary battery.

[0313] Sample 1, sample Sample 7, Sample 8, and a comparative example of a sample without added magnesium and fluorine. Table 4 shows the common starting materials and additive starting materials for all six types.

[0314] [Table 4]

[0315] <Cycle Characteristics> Figures 28(A) and 28(B) show Sample 1, Sample 7, Sample 8 and Sample Figure 28 shows a graph of the cycle characteristics of a secondary battery using the positive electrode active material of (Comparative Example) 6. A) is a graph of energy density when charging at 4.6V, and Figure 28(B) is the energy when charging at 4.6V. This is a graph of energy density maintenance rate.

[0316] As shown in Figures 28(A) and 28(B), the atomic ratio of magnesium to fluorine in the raw materials. All samples with a Mg:F ratio of 1:2 showed good cycle characteristics. In particular, Sample 7, which used 1 mol% MgO and 2 mol% LiF as starting materials, was the best. It exhibited favorable cycle characteristics, with an energy density retention rate of 93% after 30 cycles. As is clear from Figure 28(A), not only the cycle characteristics but also the energy density is good. there were. [Examples]

[0317] In this embodiment, a positive electrode active material having a second region formed by magnesium segregation, The results of comparing positive electrode active materials having a magnesium oxide layer formed by external coating This will be shown.

[0318] <Positive electrode active material having a second region formed by segregation> As a positive electrode active material having a second region formed by magnesium segregation, Sample 7 of Example 1, using 1 mol% MgO and 2 mol% LiF as materials. Used.

[0319] <Positive electrode active material with externally coated MgO> As a positive electrode active material having a magnesium oxide layer formed by external coating, Sample 9: Lithium lutein oxide coated with magnesium oxide using multi-angle barrel sputtering. The positive electrode active material of (Comparative Example) and Sample 10 (Comparative Example) was used. Sample 9 (Comparative Example) The method for preparing Sample 10 (comparative example) is described below.

[0320] Lithium cobalt oxide manufactured by Nippon Chemical Industrial Co., Ltd. (product name: C-10N) was used. Multi-angled barrel Sputtering uses magnesium oxide as the target, with a power of 450W and sputtering gas The film was deposited using Ar and O2. The partial pressures of Ar and O2 were 0.6 Pa and 0 Pa, respectively. The pressure was set to 0.5 Pa. The processing time was 36 minutes for sample 9 and 180 minutes for sample 10. .

[0321] STEM observation after multi-angle barrel sputtering revealed that in sample 9, the positive electrode active material A magnesium oxide layer of approximately 1 nm to 3 nm was attached to the surface. Also, in sample 10... A magnesium oxide layer of approximately 6 nm to 8 nm was attached to the surface of the positive electrode active material.

[0322] Subsequently, samples 9 and 10 were heated in the same manner as described in the second heating procedure in Embodiment 1. It was heated at 800°C for 2 hours. The heating rate was 200°C / h, and dry air with a dew point of -109°C was used for 10 minutes. It was run at L / min.

[0323] Samples 7, 9 (comparative example), and 10 (comparative example) are used for comparison in this embodiment. The conditions are shown in Table 5.

[0324] [Table 5]

[0325] <stem> Cross-sections of the positive electrode active material of Sample 7 and Sample 10 (comparative example) were observed using STEM. Figures 29(A) and 29(B) show a second region formed by segregation. STEM images of Sample 7 are shown. Figures 30(A) and 30(B) show the external covering. The image shows a STEM image of sample 10 (comparative example) having a magnesium oxide layer formed thereon.

[0326] In Sample 7, the difference in image brightness is due to the fact that the first and second regions are different regions. This could be observed from the following. As shown in Figure 29, the second region formed by segregation In sample 7, a second region of approximately 1 nm to 2 nm was observed.

[0327] Furthermore, in Sample 10 (Comparative Example), as shown in Figure 30, lithium cobalt oxide was also present on The formation of a magnesium oxide layer could be observed from differences in image brightness, etc. In Sample 10 (comparative example), a magnesium oxide layer of approximately 8 nm was observed.

[0328] Both Sample 7 and Sample 10 (comparative example) showed interlayer cations and anions. The arrangement is at least partially aligned, and the crystal orientation of the first and second regions is consistent. The following behavior was observed.

[0329] <Charge / discharge characteristics> Using the positive electrode active materials of Sample 7, Sample 9 (comparative example), and Sample 10 (comparative example) A secondary battery was fabricated in the same manner as in Example 1, and its charge-discharge characteristics were evaluated. Figure 31(A) shows Sample 7. Figure 31(B) shows the positive electrode of Sample 9 (comparative example), and Figure 31(C) shows the positive electrode of Sample 10 (comparative example). This graph shows the charge and discharge characteristics of a secondary battery using an active material.

[0330] As shown in Figure 31, a sample having a second region formed by magnesium segregation. Sample 9 has a magnesium oxide layer formed by polygonal barrel sputtering, as shown in 7. Furthermore, it had a larger capacity than sample 10 and exhibited good charge-discharge characteristics.

[0331] <Cycle Characteristics> Next, the positive electrode active materials of Sample 7, Sample 9 (Comparative Example), and Sample 10 (Comparative Example) The results of evaluating the cycle characteristics of the secondary battery used are shown in Figures 32(A) and 32(B). The cycle characteristics test was performed in the same manner as in Example 1.

[0332] Figure 32(A) shows the energy density when charging at 4.6V, and Figure 32(B) shows the energy when charging at 4.6V. This is a graph of energy density retention rate. As shown in Figure 32(B), the number formed by segregation Sample 7, which has region 2, has magnesium oxide formed by polygonal barrel sputtering. It exhibited significantly better cycle characteristics than samples 9 and 10, which had a um layer. Furthermore, as shown in Figure 32(A), the energy density was also better in sample 7.

[0333] Thus, the second region formed by magnesium segregation is subjected to polygonal barrel sputtering. A more formed magnesium oxide layer contributes to better charge-discharge and cycle characteristics. It became clear that this was the case.

[0334] These results suggest that the magnesium oxide layer coating the outside of the lithium cobalt oxide particles is Furthermore, it was formed as a result of magnesium, which was already present in the starting material, segregating to the surface. The magnesium-containing region contributes to the stabilization of the lithium cobalt oxide crystal structure. This was speculated. [Examples]

[0335] In this embodiment, the positive electrode active material having a second region formed by magnesium segregation is described. The characteristics were revealed through various analyses.

[0336] <Analyzed positive electrode active material> Example 1 uses 1 mol% MgO and 2 mol% LiF as additive starting materials. Pull 7 was used as the analysis sample for this embodiment.

[0337] <STEM、FFT> S of the cross-section near the surface of the positive electrode active material of sample 7 having a second region formed by segregation. TEM-FFT images are shown in Figures 33 and 34. Figure 33(A) shows the vicinity of the surface of the positive electrode active material. This is a STEM image, and the FFT (Fast Fourier Transform) of the region shown in FFT1 in Figure 33(A) is shown. The image is shown in Figure 33(B). Some of the bright spots in the FFT image of Figure 33(B) are shown in Figure 33(C). We decided to call them A, B, C, and O.

[0338] For the bright spots in the FFT image of the region shown in FFT1, the measured values ​​are as follows: OA = d = 0.2 0nm, OB was d=0.24nm, and OC was d=0.25nm. Also, ∠AOB=5 The angles were 3°, ∠BOC=74°, and ∠AOC=127°.

[0339] This is ICDD (International Centre for Diffraction) Data on magnesium oxide (MgO) in the ction Data database (I From CDD45-0945), d=0.21nm of OA(200) and OB(1 d=0.24nm at -11), d=0.24nm at OC(-1-11), ∠AOB=55 °, ∠BOC=70°, ∠AOC=125° are close. Therefore, the region shown in FFT1 is It was revealed that the region has a rock salt-type crystalline structure and is an incident image. .

[0340] Figure 34(A) is a STEM image of the vicinity of the surface of the same positive electrode active material as Figure 33(A), and Figure 34( Figure 34(B) shows the FFT image of the region shown in FFT2 in A). FFT of Figure 34(B) As shown in Figure 34(C), some of the bright spots in the image are designated as A, B, C, and O.

[0341] For the bright spots in the FFT image of the region shown in FFT2, the measured values ​​are as follows: OA = d = 0.2 The wavelengths were 4nm, OB was d=0.20nm, and OC was d=0.45nm. Also, ∠AOB=2 The angles were 5°, ∠BOC=53°, and ∠AOC=78°.

[0342] This is data on lithium cobalt oxide (LiCoO2) in the ICDD database. From ICDD50-0653), d=0.24nm of OA(101), OB( d=0.20nm for 104), d=0.47nm for OC(003), ∠AOB=25°, ∠BOC=55° and ∠AOC=80° are close. Therefore, the region shown in FFT2 is Koba It was revealed that this region contains lithium luteate and is an image of the incident

[0010] .

[0343] Furthermore, the STEM images in Figures 33(A) and 34(A) show that in the first and second regions... The brightness of the images differed, and furthermore, the crystal orientations matched between the first and second regions. It was observed that they were doing so.

[0344] <stem-edx> Next, the surface vicinity and the vicinity of crystal defects of sample 7 were analyzed using STEM-EDX. The results are shown in Figures 35 to 37.

[0345] Figure 35 shows the STEM-EDX analysis results of the vicinity of the surface of the positive electrode active material of sample 7. (A) is a STEM image, Figure 35(B) is a magnesium mapping, and Figure 35(C) is a fluorine mapping. This is a mapping.

[0346] In Example 1, 0.5 mol% MgO and 1 mol% LiF were used as the starting material. Compared to Sample 1 (Figure 22), the starting material was modified by adding 1 mol% MgO and 2 mol% LiF. Sample 7 (Figure 35), used as the basis for this analysis, clearly shows the magnesium near the surface of the positive electrode active material. This was observed. The greater the amount of magnesium near the surface of the positive electrode active material, the more the cycle characteristics This supports the results of Example 1, which indicate good performance.

[0347] Figure 36 is a cross-sectional TEM image of the vicinity of a crystal defect in the positive electrode active material of sample 7. At point 1001, a region of different brightness, believed to be a crystal defect, was observed.

[0348] Figure 37 shows the results of analyzing the crystal defect 1001 in Figure 36 using STEM-EDX. show.

[0349] Figure 37(A-1) is a STEM image of the crystal defect 1001, and Figure 37(A-2) is a magnesium Figure 37(B-1) shows the mapping of fluorine, and Figure 37(B-2) shows the mapping of zirconium. This is a mapping of Um.

[0350] As shown in Figure 37(A-2), the crystal defects in the positive electrode active material of sample 7 and their vicinity are Magnesium segregation was observed. Therefore, sample 7 showed segregation not only near the surface but also in the interior. It was also shown to be a positive electrode active material having a second region. Furthermore, as shown in Figure 37(B-2) As shown above, a large amount of zirconium segregation was observed in the second region inside. The process is carried out using a ball mill, and zirconium is used as the material for the ball mill. Therefore, there is a possibility that zirconium was mixed into sample 7. Also, Figure 37 (B-1 As shown in the second region inside, almost no fluorine was detected, but this is EDX This was thought to be because fluorine, being a light element, is difficult to detect.

[0351] <tof-sims> Next, regarding the positive electrode active material of sample 7 having a second region formed by segregation, To investigate the depth distribution of nesium and fluorine, we performed an analysis using ToF-SIMS. The results are shown in Figure 38.

[0352] Multiple cathode active material particles were used as samples, and ToF-SIMS analysis and sputtering were performed alternately. The analysis was repeated, starting from the surface of the positive electrode active material and moving in the depth direction. The measuring instrument used was TOF.S. Using the IMS5-300 (manufactured by ION-TOF), C was used as the ion source for sputtering. We used s. The analysis was performed within an area of ​​approximately 50 μm square.

[0353] Magnesium oxide ion ([MgO2] 2- ) and fluoride ions (F - Regarding the strength of ), Figure 38 shows a graph with the number of measurements (cycles) on the horizontal axis. In this measurement, negative Since we are performing an analysis on ions, the distribution of magnesium is [MgO2] 2- With strength The evaluation was conducted. Note that each intensity level has been normalized with a maximum value of 1.

[0354] As shown in Figure 38, a sample having a second region formed by magnesium segregation. In step 7, it was revealed that the depth distributions and peaks of magnesium and fluorine overlapped. Ta.

[0355] <xps> Next, the positive electrode active material of sample 7 was analyzed using XPS before and after the second heating process. The results are shown in Table 6 and Figure 39. XPS analysis was performed in the same manner as in Example 1.

[0356] Table 6 shows the results of quantifying the concentrations of each element in sample 7 using XPS. Note the quantitative accuracy. The detection limit is approximately ±1 atomic%, and although it varies depending on the element, it is also approximately 1 atomic. In Ca, the waveform-separated Mg Auger peak is removed, so the quantitative error is higher than usual. big.

[0357] [Table 6]

[0358] The quantitative values ​​in Table 6 are XPS-analyzable values ​​obtained from the cathode active material at a depth of 4 nm from the surface toward the center. These exist in the range up to 5 nm and include lithium, cobalt, titanium, oxygen, carbon, fluorine, and sulfur. The total amount of calcium, magnesium, sodium, and zirconium is 100 atmospheres. This is the value when set to c%.

[0359] As shown in Table 6, the sample having a second region formed by segregation after the second heating. In 7, in the range from 4 nm to 5 nm in depth from the surface toward the center, lithium, co Balt, titanium, oxygen, carbon, fluorine, sulfur, calcium, magnesium, sodium When the total amount of zirconium is taken as 100%, the magnesium concentration is 5.5 atomic The fluorine concentration was 1.4 atomic%.

[0360] Furthermore, when the total amount of lithium, cobalt, oxygen, fluorine, and magnesium is taken as 100% The magnesium concentration was calculated to be 6.7%, and the fluorine concentration was calculated to be 1.7%. .

[0361] Furthermore, the ratio of magnesium to fluorine concentrations is within the range Mg:F=y:1 (3≦y≦5). More precisely, the ratio of Mg:F was approximately 3.9:1.

[0362] Next, surface XPS analysis was performed to analyze the fluorine bonding state of sample 7 after the second heating. The results are shown in Figure 39. As a comparative example, 10 mol% LiF was used as the starting material. The results of a sample prepared in the same manner as Sample 7, except that magnesium was not added. This is shown. The XPS spectra of standard samples of MgF2 and LiF are also shown.

[0363] As shown in Figure 39, 10 mol% LiF was used as the starting material, and magnesium was added. In the sample without fluorine addition, the peak of the fluorine bond energy coincided with that of LiF.68 The voltage is approximately 5 eV, and the fluorine present in the surface layer of the positive electrode active material is mainly bonded to LiF. It was thought to be in that state. On the other hand, 1 mol% MgO and 2 mol% LiF were added to the starting material. In sample 7, which is used as a second region, fluorine present on the surface of the positive electrode active material is found. The peak of the binding energy is between 682 eV and 685 eV, more precisely 684.3 eV. It was V, and did not match either MgF2 or LiF. In other words, the second positive electrode active material It is inferred that the fluorine present in the region exists in bonding states other than MgF2 and LiF. Ta. [Examples]

[0364] In this embodiment, when preparing a positive electrode active material having a second region formed by segregation, This section explains the results of our investigation into the heating temperature and the atmosphere during the second heating process. .

[0365] ≪Second heating temperature≫ <Preparation of positive electrode active materials from Sample 11 to Sample 13> The cathode active materials for samples 11 to 13 were prepared by changing the temperature of the second heating process. All starting materials are lithium carbonate and cobalt oxide as common starting materials, and additive starting materials Then, 1 mol% MgO and 2 mol% LiF were used.

[0366] The second heating temperature was 700°C for sample 11, 900°C for sample 12, and 13 was The positive electrode active material was prepared in the same manner as Sample 7 in Example 1, except that the temperature was set to 1000°C. The second heating temperature for pull 7 is 800°C. The second heating temperatures for each sample are shown in Table 7. vinegar.

[0367] [Table 7]

[0368] Using the positive electrode active materials of Sample 7 and Samples 11 to 13, the same procedure as in Example 1 was followed. Next, we fabricated batteries and evaluated their cycle characteristics. Samples 7, 11 through 13. The cycle characteristics are shown in Figure 40. The charge and discharge conditions were the same as in Example 1.

[0369] Figure 40(A) is a graph of energy density when charging at 4.6V, and Figure 40(B) is a graph of energy density when charging at 4.6V. This is a graph of the energy density maintenance rate over time. As shown in Figure 40(B), the second heating temperature Sample 7, heated to 800°C, showed the best cycle characteristics. The second heating temperature was 70°C. Sample 11, set to 0°C, and Sample 12, set to 900°C, showed the next best cycles. This was a characteristic. Even in sample 13, where the second heating temperature was 1000°C, after 20 cycles... The energy density maintenance rate was 76%. This is the same as shown in Figure 26 for the sample without additive starting material. In Sample 6, the energy density maintenance rate after 20 cycles was 63%, compared to this. Therefore, it can be said that it exhibited good cycle characteristics.

[0370] Therefore, the second heating temperature is preferably 700°C to 1000°C, and 700°C to 9 It was found that temperatures below 00°C are more preferable, and temperatures around 800°C are even more preferable.

[0371] ≪Second heating atmosphere≫ <Preparation of positive electrode active materials from Sample 14 to Sample 16> The second heating atmosphere was changed from dry air to 100% oxygen, from Sample 14 to Sample 1. We fabricated cathode active materials up to 6. All starting materials were lithium carbonate as a common starting material. Cobalt oxide is used, along with 1 mol% MgO and 2 mol% LiF as additive starting materials. The second heating process was changed to an oxygen atmosphere, and the same procedure was used for samples 7, 12, and 13. A positive electrode active material was prepared in the same manner.

[0372] A secondary battery was fabricated using the positive electrode active materials from Samples 14 to 16, in the same manner as in Example 1. The cycle characteristics were then evaluated along with those of samples 7, 12, and 13.

[0373] Energy density and cycle characteristics of Sample 7, Sample 12 through Sample 16 The graphs are shown in Figures 41 and 42. Figure 41 shows the energy density, and Figure 42 shows the cycle characteristics. This is a graph. Figures 41(A) and 42(A) show the results when the second heating temperature was 800°C. Samples 14 and 7, Figures 41(B) and 42(B) were measured at 900°C. Pull 15 and Sample 12, Figures 41(C) and 42(C) are sunflowers heated to 1000°C. The cycle characteristics of pull 16 and sample 13 are shown. Also, the respective characteristics shown in Figures 41 and 42. Table 8 shows the atmosphere and temperature for the second heating of the sample.

[0374] [Table 8]

[0375] As shown in Figure 41, when a second heating is performed at 800°C, 900°C, and 1000°C, The second heating process, when performed in an oxygen atmosphere, showed better cycle characteristics than when performed in dry air. Ta. [Examples]

[0376] In this example, we show the case where magnesium and fluorine are used as additive starting materials, and the case where magnesium and fluorine are used. We compared the cycle characteristics when using elements other than bisulfite.

[0377] Comparison of fluorine and chlorine First, we'll consider the case where magnesium and fluorine are used as additive starting materials, and the case where chlorine is used instead of fluorine. The cycle characteristics were compared under different conditions.

[0378] <Preparation of positive electrode active materials for samples 17 and 18> Sample 7 contains 1 mol% MgO and 2 mol% cobalt as additive starting materials. LiF was used. Sample 17 consisted of 1 mol% MgO, 1 mol% LiF, and 1 mol% LiCl was used. Sample 18 was used as a comparative example, with 1 mol% MgO and 2 mol% LiCl was used. Sample 6 was used as a comparative example, and all of magnesium, fluorine, and chlorine were used. It was not added.

[0379] Samples 7, 17, 18, and 6 are the same as in Example 2. We fabricated positive electrode active materials and used them to create secondary batteries, and then evaluated their cycle characteristics. The cycle characteristics test was performed in the same manner as in Example 1.

[0380] <Cycle Characteristics> Table 9 shows the starting materials added to each sample and the energy density maintenance after 20 cycles for each sample. Shows the rate.

[0381] [Table 9]

[0382] As shown in Table 9, when chlorine is added instead of fluorine, the cycle characteristics tend to decrease. However, sample 17, which contained 1% each of fluorine and chlorine, showed the same results after 20 cycles. The energy density maintenance rate was over 80%. This is due to the presence of magnesium, fluorine, and chlorine. Compared to sample 6, which had no deviations, it exhibited good cycle characteristics.

[0383] Comparison of magnesium with other metals Next, we will consider the case where magnesium and fluorine are used as additive starting materials, and the case where magnesium is replaced with other materials. The cycle characteristics were compared when using metals.

[0384] <Preparation of positive electrode active material for sample 29 from sample 19> Sample 7 of Example 1 is an example of a sample using magnesium and fluorine as additive starting materials. Sample 19 was used as a comparative example, with 1 mol% MgO and 1 mol% MgO as added starting materials. mol% TiO2 and 2mol% LiF were used. Sample 20 was used as a comparative example, 1 m ol% ZrO2 and 2mol% LiF were used. Sample 21 was used as a comparative example, 1 mo 1% TiO2 and 2mol% LiF were used. Sample 22 was used as a comparative example, with 1 mol % V2O5 and 2 mol% LiF were used. Sample 23 was used as a comparative example, with 1 mol% ZnO and 2 mol% LiF were used. Sample 24 was used as a comparative example, with 1 mol% C aO and 2 mol% LiF were used. Sample 25 was used as a comparative example, with 1 mol% Al2 O3 and 2 mol% LiF were used. Sample 26 was used as a comparative example, with 1 mol% MoO 2.2 mol% LiF was used. Sample 27 was used as a comparative example, with 1 mol% SrO. 2 mol% LiF was used. Sample 28 was used as a comparative example, with 1 mol% NaF and 1 m ol% LiF was used. Sample 29 was used as a comparative example, with 1 mol% BaO and 2 mol % LiF was used. Furthermore, as a comparative example where neither fluorine nor any metal is added, see Example. Sample 6 of 1 was used.

[0385] Examples for Sample 6, Sample 7, and Samples 19 through 29 Similar to step 1, a positive electrode active material was fabricated, a secondary battery was constructed using it, and its cycle characteristics were evaluated. did.

[0386] <Cycle Characteristics> Table 10 shows the starting materials added to each sample and the energy density of each sample after 20 cycles. This indicates the percentage of ownership.

[0387] [Table 10]

[0388] As shown in Table 10, replacing magnesium with other metals degrades the cycle properties. A tendency to do so was observed.

[0389] Based on these results, magnesium and fluorine are used in combination as additive starting materials. It became clear that this was extremely effective.

[0390] From the previous example, by adding magnesium and fluorine as starting materials for the positive electrode active material, It was revealed that magnesium segregates on the surface of the positive electrode active material. Because it has a well-formed coating layer, it becomes a positive electrode active material with high capacity and excellent cycle characteristics. This became clear.

[0391] Because secondary batteries with such positive electrode active materials have high capacity and long lifespan, they are favored for portable electronic devices. It is suitable. Furthermore, if applied to vehicles, including automobiles, it would allow for the use of commercial power during peak electricity demand. It is also possible to avoid using the source, resulting in energy conservation and reduction of carbon dioxide emissions. It can also contribute to reduction. [Examples]

[0392] In this embodiment, nickel, manganese, and cobalt are used as the transition metals in the first region. We will now describe the results of fabricating and evaluating the applied positive electrode active material.

[0393] <Sample 31, Sample 32> Sample 31 containing magnesium and fluorine, and a comparative example containing magnesium and fluorine. Sample 32, which does not contain tx, was prepared.

[0394] Sample 31 is a combination of nickel, manganese, and cobalt in the starting materials, with magnesium added to the sum of the materials. A sample was prepared by adding 1 atomic percent of [the substance] and 2 atomic percent of fluorine. Also, the starting material... The atomic ratio of nickel, manganese, and cobalt was set to Ni:Mn:Co=1:1:1.

[0395] First, lithium carbonate (Li2CO3) was used as the lithium source for the common starting material. Nickel oxide (NiO) was used as the nickel source. Manganese oxide was used as the manganese source. MnO2 was used. Cobalt oxide (Co3O4) was used as the cobalt source. Magnesium oxide (MgO) was used as the magnesium source for the additive starting material. Lithium fluoride (LiF) was used as the power source.

[0396] Each starting material is LiCo 0.323 Mn 0.333 Ni 0.333 O2 + MgO 0.01 LiF 0.02 The weights were measured to achieve the given atomic ratio.

[0397] Next, the weighed starting materials were mixed using a ball mill.

[0398] Next, the mixed starting materials were fired. The firing was carried out at 950°C for 10 hours, with a heating rate of 200°C / h. The flow rate of the dry atmosphere was set to 10 L / min.

[0399] The above process involves lithium, nickel, manganese, cobalt, magnesium, and fluorine. We synthesized composite oxide particles.

[0400] The synthesized composite oxide particles were cooled to room temperature.

[0401] Next, the composite oxide particles were heated. The heating was at 800°C (200°C / hour), and the holding time was... The experiment was conducted under dry air conditions for two hours.

[0402] The heated powder was cooled to room temperature and then crushed. The crushing process involved sieving. The process was carried out using a sieve with a mesh size of 53 μm.

[0403] The particles that had undergone the crushing process were used as the positive electrode active material for sample 31.

[0404] Sample 32 uses LiCo 0.333 Mn 0.333 Ni 0.333 O2 The samples were weighed to achieve an atomic ratio. The firing process was carried out at 1000°C. Other details are for Sample 31. It was made in the same way as [another product].

[0405] The preparation conditions for Sample 31 and Sample 32 are shown in Table 11.

[0406] [Table 11]

[0407] <Cycle Characteristics> Next, using the positive electrode active materials of sample 31 and sample 32 prepared as described above, We manufactured a coin-type rechargeable battery of the CR2032 type (20mm diameter, 3.2mm height), and We evaluated the characteristics of the Ikuru.

[0408] The positive electrode contains the positive electrode active materials of Sample 31 and Sample 32, and acetylene black (AB). ) and polyvinylidene fluoride (PVDF) as the positive electrode active material: AB:PVDF = 95:2.5 A slurry mixed at a ratio of 2:5 (by weight) was applied to an aluminum foil current collector. Furthermore, N-methyl-2-pyrrolidone (NMP) was used as the solvent.

[0409] Lithium metal was used for the counter electrode.

[0410] The electrolyte in the electrolyte solution is 1 mol / L lithium hexafluoride phosphate (LiPF6). The electrolyte contains ethylene carbonate (EC) and diethyl carbonate (DEC). A mixture of C:DEC = 3:7 (volume ratio) is combined with vinylene carbonate (VC) at a ratio of 2 A mixture containing a weight percentage of the additive was used.

[0411] The positive electrode and negative electrode cans were made of stainless steel (SUS).

[0412] The measurement temperature for the cycle characteristics test was set to 25°C. The charging current density was 68 per unit weight of active material. The test is performed with a constant current of 0.5 mA / g and an upper voltage limit of 4.6 V, after which the current density becomes 1.4 mA / g. Constant voltage charging was performed until [a certain value was reached]. Discharge was performed using a constant voltage with a current density of 68.5 mA / g per unit weight of active material. The test was conducted with a minimum voltage of 2.5V.

[0413] Discharge rate during 4.6V charging of secondary batteries using the positive electrode active materials of Sample 31 and Sample 32 The capacitance is shown in Figure 43(A), and the discharge capacity maintenance rate is shown in Figure 43(B).

[0414] Compared to sample 32, which did not contain magnesium and fluorine, magnesium and fluorine were added. Sample 31, to which fluorine was added, showed extremely good cycling characteristics.

[0415] Next, the results of various analyses performed on sample 31 are shown below.

[0416] <stem-fft> Figures 44 and 45 show STEM images of the cross-section near the surface of the positive electrode active material of sample 31. Figure 44(B) is a magnified STEM image of a portion of Figure 44(A). Figures 45(A) and Figure Figure 45(B) is a magnified HAADF-STEM image of a portion of Figure 44(A).

[0417] As is clear from Figure 45, the region of about 0.5 nm from the surface of the positive electrode active material is different from the other regions. A difference in brightness was observed. This is magnesium, an element lighter than transition metals. This was thought to be because there were many of them.

[0418] Furthermore, the region from approximately 0.5 nm to 5 nm from the surface of the positive electrode active material is the same as the internal region. A difference in regularity was observed. This was observed from approximately 0.5 nm to 5 nm from the surface. This was thought to be because the crystal orientation differed between that region and the area inside it.

[0419] Figure 46(A) is a bright-field STEM image of the same area as Figure 45(B). Figure 46(B) shows the Fast Fourier Transform (FFT) image of the region shown in FFT1. As shown in Figure 46(B), some of the bright spots in the image were designated as A, B, C, and O.

[0420] For the bright spots in the FFT image of the region shown in FFT1, the measured values ​​are as follows: OA = d = 0.2 The wavelengths were 2nm, OB was d=0.25nm, and OC was d=0.23nm. Also, ∠AOB=5 The angles were 8°, ∠BOC=69°, and ∠AOC=127°.

[0421] This is ICDD (International Centre for Diffraction) Data on magnesium oxide (MgO) in the ction Data database (I From CDD45-0945), d=0.21nm of OA(200) and OB(1 d=0.24nm at -11), d=0.24nm at OC(-1-11), ∠AOB=55 °, ∠BOC=70°, ∠AOC=125° are close. Therefore, the region shown in FFT1 is It was determined that the region had a rock salt-type crystalline structure and was therefore an image of the incident

[0011] .

[0422] Furthermore, Figure 46(C) shows the FFT image of the region indicated by FFT2 in Figure 46(A). As shown in Figure 46(C), some of the bright spots in the two images were designated A, B, C, and O.

[0423] For the bright spots in the FFT image of the region shown in FFT2, the measured values ​​are as follows: OA = d = 0.2 The wavelengths were 5nm, OB was d=0.21nm, and OC was d=0.49nm. Also, ∠AOB=2 The angles were 6°, ∠BOC=57°, and ∠AOC=83°.

[0424] This is data on lithium cobalt oxide (LiCoO2) in the ICDD database. From ICDD50-0653), d=0.24nm for OA(10-11), O d=0.20nm for B(10-14), d=0.47nm for OC(0003), ∠AOB =25°, ∠BOC=55°, ∠AOC=80°, which are close. Therefore, the region shown in FFT2 The region has a layered rock salt type crystalline structure, and the image is of [-12-10] incidence. It was speculated.

[0425] Furthermore, Figure 46(D) shows the FFT image of the region indicated by FFT3 in Figure 46(A). As shown in Figure 46(D), some of the bright spots in the FFT3 image were designated as A, B, C, and O. .

[0426] For the bright spots in the FFT image of the region shown in FFT3, the measured values ​​are as follows: OA = d = 0.2 The values ​​were 1 nm, OB was d=0.26 nm, and OC was d=0.24 nm. Also, ∠AOB = 5 The angles were 6°, ∠BOC=72°, and ∠AOC=128°.

[0427] This is data on lithium cobalt oxide (LiCoO2) in the ICDD database. From ICDD50-0653), d=0.20nm of OA(01-14), O d=0.23nm for B(10-1-2), d=0.23nm for OC(1-102), ∠A OB=55°, ∠BOC=70°, and ∠AOC=125° are close. Therefore, we will show it using FFT2. The region shown is a region with a layered rock salt type crystal structure, and is an image of the [02-21] incident. It was speculated that this was the case.

[0428] In other words, the regions shown in FFT2 and FFT3 have the same layered rock salt crystal structure, It became clear that these were regions with different orientations of the crystal axes.

[0429] Furthermore, in the range observable in Figures 45(A), 45(B), and 46(A), the brightness is Even though they differed, the orientation of the crystals appeared to be roughly consistent.

[0430] Figure 47 shows the structure near the surface of the positive electrode active material, as inferred from the STEM-FFT results. This is shown along with the EM image. In Figure 47, M represents either nickel, manganese, or cobalt.

[0431] The FFT3 region within the positive electrode active material has a layered rock salt-type crystalline structure. This is an incident image in which the atoms of mu and M are observed to overlap.[02-21]

[0432] Furthermore, FFT2, the surface region of the positive electrode active material, has a layered rock salt-type crystalline structure. A layer of oxygen atoms, a layer of M (one of nickel, manganese, or cobalt) atoms, and lithium This is an image of [-12-10] incidence, where the repeating layers of mu atoms can be observed. Brightfield S The alternating dark and bright layers in the TEM image are due to the M layer and oxygen and This is thought to be because the lithium layers are repeated. In other words, FFT3 and FFT2 are the same It has a layered rock salt-type crystalline structure, but the orientation of the crystal axes differs.

[0433] Furthermore, in the surface region of the positive electrode active material, FFT1 is a region closer to the surface than FFT2. It has a rock salt-type crystalline structure, and

[0011] this is an incident image.

[0434] <edx> Next, the results of analyzing the cross-section near the surface of the positive electrode active material of sample 31 using EDX are shown in the figure. This is shown in 48 and Figure 49.

[0435] Figure 48(A-1) shows the HAADF-STEM image, Figure 48(A-2) shows the oxygen mapping, Figure Figure 48(B-1) shows the mapping of magnesium, and Figure 48(B-2) shows the mapping of fluorine. Yes. Also, Figure 49(A-1) is the same HAADF-STEM image as Figure 48(A-1), Figure 49 (A-2) shows the manganese mapping, Figure 49 (B-1) shows the nickel mapping, Figure 49 (B-2) is a cobalt mapping.

[0436] First, from Figure 48 (B-1), magnesium is concentrated in a region of about 3 nm from the surface of the positive electrode active material. The analytical process was observed. Also, see Figures 49(A-2), 49(B-1), and 49(B -2) Comparison shows that the surface layer of the positive electrode active material has less manganese than the interior, and more nickel. A region with a high concentration of cobalt was observed. This region extends approximately 5 nm from the surface. Furthermore, the region where a different regularity from the interior was observed in the STEM image almost perfectly overlapped with the surrounding area.

[0437] Therefore, sample 31 has a positive electrode active material that has a region containing magnesium in its surface layer, and inside It was confirmed that the positive electrode active material has a region with a low manganese content in a part of its structure. .

[0438] In summary, based on the above results, the molar ratio of the starting materials is LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2 Sample prepared by heating +1mol%MgO+2mol%LiF at 800°C. The 31 positive electrode active materials were found to have the following characteristics.

[0439] First, the positive electrode active material of sample 31 has a second region containing magnesium oxide in its surface layer. It contains LiNi, which has a layered rock salt-type crystalline structure in the part closer to the center. x Mn y Co z It has a region containing O2(x+y+z=1), and near the surface, layered rock salt formations are present. LiNi having a crystalline structure a Mn b Co c A region having O2(a+b+c=1) and ru.

[0440] Internal Li limit x Mn y Co z O2 and LiNi a Mn b Co c O2 is the same layered rock salt type It has a crystalline structure, but the orientation of the crystal axes may differ.

[0441] Furthermore, regarding the content of each element, y > b, and the sum of nickel, manganese, and cobalt is In contrast, the manganese content may be low in areas close to the surface.

[0442] The positive electrode active material of Sample 31, which has the characteristics described above, performs extremely well when used in secondary batteries. It exhibits cyclical characteristics. [Examples]

[0443] In this example, cobalt is used as the transition metal, and magnesium and fluorine are used as the starting materials. This section describes the results of analyzing the positive electrode active material prepared by adding [the specified ingredient] using EELS. .

[0444] Example 1 uses 1 mol% MgO and 2 mol% LiF as additive starting materials. Pull 7 was used as the analysis sample for this embodiment.

[0445] Regarding the state of cobalt at six analysis points *1 to *6 within the cross-section of sample 7, EELS The analysis was performed using [a specific method]. Figure 50 shows the vicinity of the surface of the positive electrode active material of sample 7 used for EELS analysis. This is a STEM image of a cross-section, with *1 (depth from the surface of approximately 1 nm) and *2 (depth from the surface of approximately 2.5 nm) shown in the figure. Analysis points are shown at nm) and *3 (approximately 5 nm). *4 is approximately 10 nm from the surface of the positive electrode active material. m, *5 is approximately 100 nm from the surface of the positive electrode active material, and *6 is near the center of the particles of the positive electrode active material. .

[0446] Table 1 shows the EELS spectral intensity ratio of the L2 and L3 levels of cobalt at each analysis point. This is shown in Figure 2 and Figure 51. Note that the higher the L3 / L2 ratio, the lower the valence of cobalt.

[0447] [Table 12]

[0448] As is clear from Table 12 and Figure 51, the L3 of the analysis point*1 closest to the surface of the positive electrode active material The highest value for / L2 was 4.6. Also, L3 / L2 from analysis point *2 to analysis point *6 is analysis point *1 was lower and within the range of 2.9 to 3.2, so no significant difference was observed.

[0449] These results indicate that at the analysis point*1, cobalt oxide (CoO) exists in a divalent state. It was inferred that there was a high amount of cobalt. Also, from analysis point *2 to analysis point *6, lithium cobaltate was found. It was inferred that a large amount of cobalt exists in the trivalent state as um (LiCoO2). [Explanation of Symbols]

[0450] 100 Cathode active material 101 First Domain 102 Second Domain 103 The Third Domain 200 Active material layer 201 Graphene Compounds 211a positive electrode 211b negative electrode 212a Lead 212b Reed 214 Separator 215a Joint 215b Joint 217 Fixing member 250 batteries 251 Exterior 261 Folded section 262 Seal part 263 Seal part 271 Ridge 272 Valley Line 273 Space 300 Secondary battery 301 Positive electrode can 302 Negative electrode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode 308 Negative electrode current collector 309 Negative electrode active material layer 310 Separator 500 secondary battery 501 Positive electrode current collector 502 Positive electrode active material layer 503 Positive electrode 504 Negative electrode current collector 505 Negative electrode active material layer 506 negative electrode 507 Separator 508 Electrolyte 509 Exterior 510 Positive lead electrode 511 Negative lead electrode 600 Secondary battery 601 Positive Cap 602 Battery Can 603 Positive terminal 604 Positive electrode 605 Separator 606 negative electrode 607 Negative terminal 608 Insulating board 609 Insulating board 611 PTC element 612 Safety valve mechanism 900 Circuit Boards 910 Labels 911 terminal 912 Circuit 913 Secondary battery 914 Antenna 915 Seal 916 layers 917 layers 918 Antenna 920 Display device 921 Sensor 922 terminals 930 cabinets 930a enclosure 930b enclosure 931 negative electrode 932 Positive electrode 933 Separator 950 Wound body 951 terminal 952 terminals 980 Secondary battery 993 Wound body 994 negative electrode 995 positive electrode 996 Separator 997 Lead Electrode 998 Lead Electrode 1001 Crystal Defect 7100 Portable Display Device 7101 enclosure 7102 Display section 7103 Operation Buttons 7104 Secondary battery 7200 Mobile Information Terminal 7201 enclosure 7202 Display section 7203 Band 7204 Buckle 7205 Operation Buttons 7206 Input / output terminal 7207 Icons 7300 display device 7304 Display section 7400 mobile phones 7401 enclosure 7402 Display section 7403 Operation Buttons 7404 External connection port 7405 Speaker 7406 Microphone 7407 Secondary battery 7408 Lead Electrode 7409 Current collector 8000 display device 8001 enclosure 8002 Display section 8003 Speaker section 8004 Secondary battery 8021 Charging device 8022 Cable 8024 Secondary battery 8100 Lighting device 8101 enclosure 8102 Light source 8103 Secondary battery 8104 Ceiling 8105 Side wall 8106 floor 8107 Window 8200 indoor unit 8201 enclosure 8202 Air vent 8203 Secondary battery 8204 Outdoor unit 8300 Electric Refrigerator / Freezer 8301 enclosure 8302 Refrigerator door 8303 Freezer door 8304 Secondary battery 8400 automobiles 8401 Headlight 8406 Electric motor 8500 automobiles 8600 Scooter 8601 Side Mirror 8602 Secondary battery 8603 Turn signal light 8604 Under-seat storage 9600 Tablet devices 9625 Switch 9626 Switch 9627 Power switch 9628 Operation switch 9629 Fastener 9630 cabinet 9630a enclosure 9630b enclosure 9631 Display section 9633 Solar Cell 9634 Charge / Discharge Control Circuit 9635 Energy Storage Unit 9636 DC-DC converter 9637 Converter 9640 Moving parts< / edx> < / xps> < / stem>

Claims

1. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing lithium cobalt oxide, The positive electrode active material has a first region having a layered rock salt type crystal structure and a second region having a rock salt type crystal structure. The first region comprises lithium, cobalt, aluminum, and oxygen. The second region contains cobalt, magnesium, fluorine, and oxygen. When the positive electrode active material is analyzed by electron energy loss spectroscopy, the first region has a first analysis point, the second region has a second analysis point, the first analysis point has more trivalent cobalt atoms than cobalt atoms of other valencies, and the second analysis point has more divalent cobalt atoms than cobalt atoms of other valencies. Lithium-ion rechargeable battery.

2. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing lithium cobalt oxide, The positive electrode active material has a first region having a layered rock salt type crystal structure and a second region having a rock salt type crystal structure. The first region comprises lithium, cobalt, aluminum, and oxygen. The second region contains cobalt, magnesium, fluorine, and oxygen. When the positive electrode active material is analyzed by electron energy loss spectroscopy, the first region has a first analysis point, the second region has a second analysis point, and with L2 representing the L2 level of cobalt and L3 representing the L3 level of cobalt, the spectral intensity ratio L3 / L2 of cobalt at the first analysis point is less than 3.8, and the spectral intensity ratio L3 / L2 of cobalt at the second analysis point is 3.8 or greater. Lithium-ion rechargeable battery.

3. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing lithium cobalt oxide, The positive electrode active material has a first region having a layered rock salt type crystal structure and a second region having a rock salt type crystal structure. The crystal orientations of the first region and the second region are roughly coincide. The first region comprises lithium, cobalt, aluminum, and oxygen. The second region contains cobalt, magnesium, fluorine, and oxygen. When the positive electrode active material is analyzed by electron energy loss spectroscopy, the first region has a first analysis point, the second region has a second analysis point, the first analysis point has more trivalent cobalt atoms than cobalt atoms of other valencies, and the second analysis point has more divalent cobalt atoms than cobalt atoms of other valencies. Lithium-ion rechargeable battery.

4. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing lithium cobalt oxide, The positive electrode active material has a first region having a layered rock salt type crystal structure and a second region having a rock salt type crystal structure. The crystal orientations of the first region and the second region are roughly coincide. The first region comprises lithium, cobalt, aluminum, and oxygen. The second region contains cobalt, magnesium, fluorine, and oxygen. When the positive electrode active material is analyzed by electron energy loss spectroscopy, the first region has a first analysis point, the second region has a second analysis point, and with L2 representing the L2 level of cobalt and L3 representing the L3 level of cobalt, the spectral intensity ratio L3 / L2 of cobalt at the first analysis point is less than 3.8, and the spectral intensity ratio L3 / L2 of cobalt at the second analysis point is 3.8 or greater. Lithium-ion rechargeable battery.

5. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing lithium cobalt oxide, The positive electrode active material has a first region having a layered rock salt type crystal structure and a second region having a rock salt type crystal structure. The first region comprises lithium, cobalt, aluminum, and oxygen. The second region contains cobalt, magnesium, fluorine, and oxygen. The second region contains magnesium oxide in which some of the oxygen is replaced by fluorine. When the positive electrode active material is analyzed by electron energy loss spectroscopy, the first region has a first analysis point, the second region has a second analysis point, the first analysis point has more trivalent cobalt atoms than cobalt atoms of other valencies, and the second analysis point has more divalent cobalt atoms than cobalt atoms of other valencies. Lithium-ion rechargeable battery.

6. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing lithium cobalt oxide, The positive electrode active material has a first region having a layered rock salt type crystal structure and a second region having a rock salt type crystal structure. The first region comprises lithium, cobalt, aluminum, and oxygen. The second region contains cobalt, magnesium, fluorine, and oxygen. The second region contains magnesium oxide in which some of the oxygen is replaced by fluorine. When the positive electrode active material is analyzed by electron energy loss spectroscopy, the first region has a first analysis point, the second region has a second analysis point, and with L2 representing the L2 level of cobalt and L3 representing the L3 level of cobalt, the spectral intensity ratio L3 / L2 of cobalt at the first analysis point is less than 3.8, and the spectral intensity ratio L3 / L2 of cobalt at the second analysis point is 3.8 or greater. Lithium-ion rechargeable battery.

7. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing lithium cobalt oxide, The positive electrode active material has a first region having a layered rock salt type crystal structure and a second region having a rock salt type crystal structure. The first region comprises lithium, cobalt, aluminum, and oxygen. The second region contains cobalt, magnesium, fluorine, and oxygen. In the second region, a portion of the magnesium combines with oxygen and fluorine, When the positive electrode active material is analyzed by electron energy loss spectroscopy, the first region has a first analysis point, the second region has a second analysis point, the first analysis point has more trivalent cobalt atoms than cobalt atoms of other valencies, and the second analysis point has more divalent cobalt atoms than cobalt atoms of other valencies. Lithium-ion rechargeable battery.

8. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing lithium cobalt oxide, The positive electrode active material has a first region having a layered rock salt type crystal structure and a second region having a rock salt type crystal structure. The first region comprises lithium, cobalt, aluminum, and oxygen. The second region contains cobalt, magnesium, fluorine, and oxygen. In the second region, a portion of the magnesium combines with oxygen and fluorine, When the positive electrode active material is analyzed by electron energy loss spectroscopy, the first region has a first analysis point, the second region has a second analysis point, and with L2 representing the L2 level of cobalt and L3 representing the L3 level of cobalt, the spectral intensity ratio L3 / L2 of cobalt at the first analysis point is less than 3.8, and the spectral intensity ratio L3 / L2 of cobalt at the second analysis point is 3.8 or greater. Lithium-ion rechargeable battery.

9. In any one of claims 5 to 8, The crystal orientations of the first region and the second region are roughly consistent. Lithium-ion rechargeable battery.

10. In any one of claims 1, 2, and 5 to 8, In the STEM image of the positive electrode active material, the angle between the repetition of bright and dark lines observed between the first region and the second region is 5 degrees or less. Lithium-ion rechargeable battery.

11. In any one of claims 1 to 10, The second region covers at least a portion of the first region. Lithium-ion rechargeable battery.

12. In any one of claims 1 to 11, The positive electrode active material has a magnesium concentration of 1 atom or more and 16 atoms or less, with the total amount of atoms containing lithium, cobalt, oxygen, fluorine, and magnesium, as measured by X-ray photoelectron spectroscopy, set to 100 atomic%, Lithium-ion rechargeable battery.

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