Positive active material particles

Abstract

To provide a positive electrode active material particle in which the decrease in capacity in a charge-discharge cycle is suppressed, a high-capacity secondary battery, a secondary battery with excellent charge-discharge characteristics, a secondary battery with high safety or reliability, or a novel material, an active material particle, or a power storage device.SOLUTION: A positive electrode active material particle has a first region and a second region. The second region has a region in contact with the outside of the first region. The first region has lithium, one or more elements M selected from cobalt, manganese, and nickel, and oxygen. The second region has the element M, oxygen, magnesium, and fluorine. An atomic number ratio (Li / M) of lithium to the element M measured by X-ray photoelectron spectroscopy is 0.5 or more and 0.85 or less. An atomic number ratio (Mg / M) of magnesium to the element M measured by X-ray photoelectron spectroscopy is 0.2 or more and 0.5 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to an article, a method, or a manufacturing method. , machine, manufacture, or composition of matter One embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, an electronic device, or the like. or their manufacturing methods. Or electronic equipment and its operating system Regarding the system.

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

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

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

[0005] The characteristics required for lithium-ion secondary batteries are higher capacity, cycle life, and These include improved characteristics, safety in various operating environments, and improved long-term reliability.

[0006] To improve the cycle characteristics and capacity of lithium-ion secondary batteries, Improvements are being considered (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

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

[0008] As described above, lithium ion secondary batteries and the positive electrode active materials used therein have the following characteristics: capacity, size, There is room for improvement in various aspects, such as cycle characteristics, charge / discharge characteristics, reliability, safety, and cost. It is left behind.

[0009] One embodiment of the present invention is to use the same in a lithium ion secondary battery, thereby improving the charging and discharging cycle. It is an object of the present invention to provide positive electrode active material particles in which a decrease in capacity is suppressed. An object of one embodiment of the present invention is to provide a high-capacity secondary battery. An object of the present invention is to provide a secondary battery having excellent charge-discharge characteristics. An object of one embodiment is to provide a secondary battery with high safety or reliability.

[0010] Another embodiment of the present invention is a novel substance, active material particles, a power storage device, or a manufacturing method thereof. One of our goals is to provide a method for

[0011] The description of these problems does not preclude the existence of other problems. It is not necessary for one embodiment to solve all of these problems. It is possible to extract other problems from the claims. [Means for solving the problem]

[0012] One aspect of the present invention is a positive electrode active material particle having a first region and a second region, The second region has a region in contact with the outside of the first region, and the first region is composed of lithium and an element M and oxygen, and the element M is one or more selected from cobalt, manganese, and nickel. the second region has the element M, oxygen, magnesium, and fluorine; The atomic ratio of lithium to element M (Li / M) measured by X-ray photoelectron spectroscopy is 0.5 The ratio of magnesium element to element M measured by X-ray photoelectron spectroscopy is 0.85 or more. The molecular weight ratio (Mg / M) of the positive electrode active material particles is 0.2 or more and 0.5 or less. The light is used to analyze, for example, the surface of the positive electrode active material particles.

[0013] In the above configuration, the thickness of the second region is 0.5 nm or more and 50 nm or less. is preferred.

[0014] In the above configuration, the first region has a layered rock salt type crystal structure, and the second region has a layered rock salt type crystal structure. It is preferred that the compound has a salt-type crystal structure.

[0015] In the above configuration, the crystal structure of the first region is expressed by the space group R-3m, and the crystal structure of the second region is expressed by the space group R-3m. The crystal structure of the region is preferably represented by the space group Fm-3m.

[0016] In the above configuration, the number of fluorine atoms relative to the element M measured by X-ray photoelectron spectroscopy The ratio (F / M) is preferably 0.02 or more and 0.15 or less.

[0017] In the above structure, the element M is preferably cobalt.

[0018] Alternatively, one embodiment of the present invention is a positive electrode active material particle having a first region and a second region. The second region has an area contacting the outside of the first region, and the first region is , an element M, and oxygen, wherein the element M is selected from cobalt, manganese, and nickel. The second region is one or more elements selected from the group consisting of element M, oxygen, magnesium, and fluorine. The particles are formed using a plurality of raw materials, and the number of atoms of element M contained in the plurality of raw materials is The ratio of the total number of lithium atoms in the multiple raw materials to the total (Li / M) is 1.02 The positive electrode active material particles are larger than 1.05 and smaller than 1.05.

[0019] In the above structure, the ratio of the number of atoms of the element M contained in the plurality of materials to the total number of atoms of the element M contained in the plurality of materials is The number of magnesium atoms contained in the raw material is preferably 0.005 or more and 0.05 or less. .

[0020] In the above structure, the ratio of the number of atoms of the element M contained in the plurality of materials to the total number of atoms of the element M contained in the plurality of materials is The number of fluorine atoms contained in the raw material is preferably 0.01 or more and 0.1 or less.

[0021] In the above-mentioned configuration, one of the plurality of raw materials is a compound containing element M, Another one of the raw materials is a compound containing lithium, and another one of the raw materials is a compound containing magnesium. It is preferably a compound.

[0022] In the above configuration, the thickness of the second region is 0.5 nm or more and 50 nm or less. is preferred. [Effects of the Invention]

[0023] According to one embodiment of the present invention, when used in a lithium ion secondary battery, It is also possible to provide a positive electrode active material that suppresses the decrease in capacity during charging. Furthermore, a secondary battery having excellent charge / discharge characteristics can be provided. In addition, a secondary battery with high safety and reliability can be provided. It is possible to provide active material particles, a power storage device, or a manufacturing method thereof. [Brief explanation of the drawings]

[0024] [Figure 1] 3A to 3C are diagrams illustrating an example of positive electrode active material particles. [Figure 2] 5A to 5C are diagrams illustrating an example of a method for manufacturing positive electrode active material particles. [Figure 3] FIG. 10 is a cross-sectional view of an active material layer in the case where a graphene compound is used as a conductive additive. [Figure 4] FIG. 2 is a diagram illustrating a coin-type secondary battery. [Figure 5] FIG. 2 is a diagram illustrating a cylindrical secondary battery. [Figure 6] 1A and 1B illustrate examples of power storage devices. [Figure 7] 1A and 1B illustrate examples of power storage devices. [Figure 8] 1A and 1B illustrate examples of power storage devices. [Figure 9] 1A and 1B illustrate examples of power storage devices. [Figure 10] 1A and 1B illustrate examples of power storage devices. [Figure 11] FIG. 1 is a diagram illustrating a laminated secondary battery. [Figure 12] FIG. 1 is a diagram illustrating a laminated secondary battery. [Figure 13] FIG. 2 is a diagram showing the appearance of a secondary battery. [Figure 14] FIG. 2 is a diagram showing the appearance of a secondary battery. [Figure 15] 1A to 1C are diagrams illustrating a method for manufacturing a secondary battery. [Figure 16] 1A and 1B are diagrams illustrating a bendable secondary battery. [Figure 17] 1A and 1B are diagrams illustrating a bendable secondary battery. [Figure 18] 1A to 1C illustrate examples of electronic devices. [Figure 19] 1A to 1C illustrate examples of electronic devices. [Figure 20] 1A to 1C illustrate examples of electronic devices. [Figure 21] 1A to 1C illustrate examples of electronic devices. [Figure 22] SEM observation results. [Figure 23] SEM observation results. [Figure 24] SEM observation results. [Figure 25] Particle size distribution measurement results. [Figure 26] Particle size distribution measurement results. [Figure 27] XPS measurement results. [Figure 28] XPS measurement results. [Figure 29] XPS measurement results. [Figure 30] Figure showing HAADF-STEM image. [Figure 31] FIG. 10 is a graph showing the energy density maintenance rate of a secondary battery. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and it is understood by those skilled in the art that various modifications may be made to the modes and details thereof. The present invention will be easily understood by reading the following description of the embodiments. It is not something that is done.

[0026] In addition, crystal planes and directions are indicated by superscript bars in the crystallographical notation. Due to limitations on the application notation, crystal planes and directions are indicated by a bar above the numbers. The numbers are expressed by adding a minus sign (-) before the numbers. The orientation is [ ], the collective orientation showing all equivalent directions is < >, and the individual faces showing crystal faces are ( ) and sets of surfaces with equivalent symmetry are represented by {}.

[0027] In this specification, segregation refers to a phenomenon in a solid consisting of multiple elements (for example, A, B, and C). This refers to the phenomenon in which a certain element (such as B) is distributed unevenly.

[0028] In the present specification and the like, the layered rock salt type crystals of the composite oxide containing lithium and a transition metal The structure is a rock salt type ion arrangement in which cations and anions are arranged alternately, and The lithium atoms are regularly arranged to form a two-dimensional plane, allowing two-dimensional diffusion of lithium. The term "crystal structure" refers to a crystal structure in which cations or anions may be missing.

[0029] In this specification and the like, the term "epitaxy" refers to the similarity of the structure of a two-dimensional interface. Crystal growth that resembles the structure of a two-dimensional interface is called epitaxial growth. Topotachianism is the practice of having dimensional structural similarity or having the same crystallographic orientation. Therefore, when a part of a cross section is observed, two regions (for example, For example, the crystal orientation of the underlying region and the region that is grown is the same.

[0030] The rock salt crystal structure is a structure in which cations and anions are arranged alternately. There may be ionic or anionic deficiencies.

[0031] Layered rock salt crystals and anions in rock salt crystals have a cubic close-packed structure (face-centered cubic lattice structure) When layered rock salt crystals come into contact with each other, a cubic close-packed structure consisting of anions is formed. There are crystal planes with matching packing structures. However, the space group of layered rock salt crystals is R-3. m, which is different from the space group Fm-3m of rock salt crystals. The index is different for layered rock salt crystals and rock salt crystals. In a type crystal, when the directions of the crystal planes that satisfy the above conditions are the same, the crystal orientation is the same. We can say that.

[0032] For example, lithium cobalt oxide with a layered rock salt crystal structure and lithium cobalt oxide with a rock salt crystal structure When magnesium oxide comes into contact with lithium cobalt oxide, the crystal orientation is the same. When the (1-1-4) plane of magnesium oxide contacts the {001} plane of lithium cobalt oxide, When the (104) plane of the lithium cobalt oxide contacts the {001} plane of the magnesium oxide, When the (0-14) plane of the lithium cobalt oxide contacts the {001} plane of the magnesium oxide, When the (001) plane of the magnesium oxide contacts the {111} plane of the lithium cobalt oxide, 012) plane and the {111} plane of magnesium oxide come into contact.

[0033] The alignment of the crystal orientations in the two regions can be confirmed by TEM (transmission electron microscope) and STEM ( Scanning transmission electron microscope (HAADF-STEM) image, High Angle Scattering Annular Dark Field Scanning Transmission Electron Microscope (HAADF-STEM) image This can be determined from the ABF-STEM (annular bright-field scanning transmission electron microscope) image, etc. X-ray diffraction (XRD), electron diffraction, neutron X-ray diffraction and other methods can also be used to make a judgment. If the crystal orientation is consistent, the TEM image etc. The difference in direction of the rows of cations and anions alternately arranged on a straight line is 5 degrees or less, and more preferably It can be seen that the temperature is below 2.5 degrees. In addition, TEM images show that oxygen, fluorine, and other In some cases, the light elements that correspond to the metal elements may not be clearly observed. It is possible to determine the following.

[0034] Space groups are used in, for example, X-ray diffraction, electron diffraction, STEM images, and TEM images using FFT (fast Fourier transform). For example, the structure can be analyzed and obtained from the FFT of a STEM image. The image was analyzed and the ICDD (International Centre for Diff The crystal structure is identified by comparing it with databases such as the Fraction Data Database. do.

[0035] (Embodiment 1) In this embodiment, a positive electrode active material particle according to one embodiment of the present invention will be described.

[0036] [Positive electrode active material structure] First, a positive electrode active material particle 100 according to one embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1(A), the positive electrode active material particle 100 has a first region 101 and a second region 102. The second region 102 is in contact with the outside of the first region 101. It can be said that at least a part of the surface is covered.

[0037] The second region 102 is preferably a layered region.

[0038] The first region 101 and the second region 102 are regions having different compositions. In FIG. 1A, the boundary between the first region 101 and the second region 102 may not be clear. The region 102 is divided by a dotted line, and the concentration gradient of an element across the dotted line is shown in gray. 1B and onward, for convenience, the boundary between the first region 101 and the second region 102 is shown. The boundary between the first region 101 and the second region 102 is shown only by a dotted line. More details will be provided later.

[0039] As shown in FIG. 1B, a second region 102 is present inside the positive electrode active material particle 100. For example, when the first region 101 is polycrystalline, the second region 102 may be present at the grain boundary. In addition, the second region may be formed in the portion of the positive electrode active material particle 100 where the crystal defect is present. In this specification, the crystal defect is a defect observed by TEM. This refers to possible defects in the crystal structure, or structures in which other elements have entered the crystal.

[0040] Furthermore, the second region 102 does not have to cover the entire first region 101.

[0041] In other words, the first region 101 exists inside the positive electrode active material particle 100, and the second region The second region 102 is present in the surface layer of the positive electrode active material particle 100. It may be present inside the electrode active material particle 100 .

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

[0043] <First Area 101> The first region 101 contains lithium, an element M, and oxygen. The element M is a mixture of a plurality of elements. The element M may be, for example, one or more elements selected from transition metals. The first region 101 has a composite oxide containing lithium and a transition metal.

[0044] The element M is a transition metal that can form a layered rock salt type composite oxide together with lithium. For example, it is preferable to use one or more of manganese, cobalt, and nickel. In other words, only cobalt can be used as the transition metal in the first region 101. Alternatively, two types of cobalt and manganese may be used, or a combination of cobalt, manganese, and nickel may be used. For example, aluminum may be used in addition to the transition metal as the element M. Metals other than transition metals, including Cr, may also be used.

[0045] That is, the first region 101 is made of one of lithium cobalt oxide, lithium nickel oxide, and cobalt. Lithium cobalt oxide with manganese substituted in some parts, lithium nickel-manganese-cobalt oxide Lithium and transition metal composites such as lithium aluminum and nickel-cobalt-lithium aluminum oxide It may have an oxide.

[0046] In the layered rock salt type crystal structure, lithium is easily diffused two-dimensionally, so the first region 101 and Furthermore, when the first region 101 has a layered rock salt type crystal structure, it is surprisingly However, if the entire first region 101 is The layered rock salt type crystal structure is not required. For example, the first region 101 may have a crystal defect in part. The first region 101 may have a crystal structure other than that of the first region 101. It may have.

[0047] The first region 101 may be represented by the space group R-3m.

[0048] <Second Area 102> The second region includes the element M and oxygen. For example, the second region includes an oxide of the element M. Has.

[0049] The second region preferably contains magnesium in addition to the element M and oxygen. The second region preferably contains fluorine. By having Here, the high stability of the secondary battery means that, for example, the change in the crystal structure of the positive electrode active material particles 100 It means that the change in capacity is small. It also means that the second region This means that the change in the valence of the transition metal, for example, cobalt, contained in the region 102 is suppressed.

[0050] The second region 102 has, for example, magnesium oxide, with some of the oxygen substituted with fluorine. Magnesium oxide is a chemically stable material, so it can be used even after repeated charging and discharging. It is resistant to deterioration and is suitable as a coating layer.

[0051] Magnesium oxide is partially substituted with fluorine, which allows for the diffusion of lithium, for example. The surface layer of the positive electrode active material, for example, the second The presence of fluorine near the region 102 may make it difficult to dissolve in hydrofluoric acid.

[0052] If the second region 102 is too thin, its function as a covering layer is reduced, but if it is too thick, Therefore, the thickness of the second region 102 is set to 0.5 nm or more and 50 nm or less. It is preferable that the thickness is 0.5 nm or more and 3 nm or less.

[0053] The thickness of the second region 102 can be measured by TEM. After processing the sample to expose the cross section, observation can be performed using a TEM.

[0054] If the second region 102 has a rock salt type crystal structure, the crystal orientation will be the same as that of the first region 101. This is preferable because it is easy to match and function as a stable coating layer. The entire second region 102 does not have to have a rock salt crystal structure. It may be crystalline or have another crystal structure.

[0055] The second region 102 may be represented by the space group Fm-3m.

[0056] Generally, the positive electrode active material particles 100 lose cobalt, manganese, etc. as they are repeatedly charged and discharged. side effects such as the dissolution of transition metals into the electrolyte, the release of oxygen, and the instability of the crystal structure. However, the positive electrode active material particles 100 according to one embodiment of the present invention Since the second region 102 is located in the surface layer, the lithium and transition metal contained in the first region 101 are It is possible to make the crystal structure of the composite oxide containing the metal more stable.

[0057] The number of lithium atoms relative to the element M in the process for producing the positive electrode active material according to one embodiment of the present invention The relationship between the ratio and the second region formed will be explained. The element M is distributed in large amounts on the surface, forming the second region. The atomic ratio of lithium to element M is By reducing the ratio Li / M, an excess of element M is generated, forming the second region. It can be achieved.

[0058] The ratio of element M to lithium is higher in the second region than in the first region ( (i.e., Li / M is small). Alternatively, in the second region, lithium is not detected. There may be cases where this is the case.

[0059] On the other hand, by increasing Li / M, the average particle size of the positive electrode active material particles 100 increases. As the average particle size increases, the specific surface area decreases. In such cases, side reactions such as decomposition of the electrolyte may occur. By reducing the specific surface area, the area in contact with the electrolyte is reduced, reducing the amount of side reactions. Here, the side reaction refers to an irreversible reaction during the charge and discharge of a secondary battery, for example. .

[0060] As shown in FIG. 1B, the second region 102 exists inside the first region 101. The crystalline structure of the composite oxide containing lithium and a transition metal in the first region 101 is further This is preferable because it can be stabilized.

[0061] The fluorine contained in the second region 102 is in a bonding state other than MgF2, LiF, and CoF2. Specifically, the surface of the positive electrode active material particle 100 is analyzed by XPS (X When analyzed by FT-IR photoelectron spectroscopy, the peak position of the fluorine binding energy was 682 eV. It is preferable that the energy is 685 eV or less, and more preferably about 684.3 eV. This is a binding energy that does not match either MgF2 or LiF.

[0062] In this specification, the peak position of the binding energy of a certain element when analyzed by XPS The position is the position where the intensity of the energy spectrum is extremely high in the range corresponding to the binding energy of the element. This refers to the value of binding energy at which the bond becomes largest.

[0063] <First area 101 and second area 102> The first area 101 and the second area 102 are used for TEM images, STEM images, and FFT (Fast Fourier Transform) analysis. Energy dispersive X-ray analysis (EDX), time-of-flight simultaneous electron microscopy (ToF-SIMS), Depth analysis by secondary ion mass spectrometry, XPS, Auger electron spectroscopy, TDS ( It can be confirmed that the different compositions are obtained by thermal desorption spectroscopy (TEM). In the STEM image, differences in the constituent elements are observed as differences in the brightness of the image. It can be seen that the constituent elements of the first region 101 and the second region 102 are different. It can also be observed from the element distribution image that the first region 101 and the second region 102 contain different elements. However, it is not always possible to clearly distinguish the first region 101 and the second region 102 through various analyses. The boundary does not have to be observable.

[0064] The concentrations of lithium, element M, magnesium and fluorine were determined by ToF-SIMS, XPS, The analysis can be carried out by Auger electron spectroscopy, TDS, or the like.

[0065] XPS is capable of quantitatively analyzing the area from the surface of the positive electrode active material particle 100 to about 5 nm. Therefore, when the thickness of the second region 102 is less than 5 nm, the second region 102 and the first region When the thickness of the second region 102 is 5 nm or more from the surface, The element concentrations in the second region 102 can be quantitatively analyzed.

[0066] The Li / M measured by XPS in the positive electrode active material particles 100 is, for example, 0.5 or more. It is below 0.85.

[0067] In addition, the ratio of magnesium to element M measured using XPS in the positive electrode active material particles 100 The atomic ratio of magnesium to magnesium (hereinafter referred to as Mg / M) is preferably greater than 0.15, and is preferably less than 0.2 It is preferably 0.3 or more and 0.4 or less, and more preferably 0.3 or more and 0.4 or less.

[0068] In addition, the ratio of fluorine to element M measured in the positive electrode active material particles 100 using XPS was The atomic ratio (hereinafter referred to as F / M) is preferably 0.02 or more and 0.15 or less.

[0069] The crystal structures of the first region 101 and the second region 102 can be determined by, for example, an electron diffraction pattern or T It can be evaluated by analyzing the inverse fast Fourier transform image of the EM image.

[0070] <Third Area 103> It has been assumed so far that the positive electrode active material particle 100 has the first region 101 and the second region 102. However, one embodiment of the present invention is not limited to this. Thus, the positive electrode active material particle 100 may have a third region 103. 3 can be provided so as to be in contact with at least a part of the second region 102, for example. The third region 103 may be a coating containing carbon, such as a graphene compound. Alternatively, it may be a coating containing a decomposition product of lithium or the electrolyte. When the positive electrode active material particles 100 are coated with carbon, the positive electrode active material particles 100 may be coated with each other or with the positive electrode active material particles 100. The third region 103 can enhance the electrical conductivity between the 00 and the current collector. In the case of a coating containing decomposition products of the electrolyte, excessive reaction with the electrolyte is suppressed, and the secondary battery When used in the above, the cycle characteristics can be improved.

[0071] [Production method] The first region 101 and the second region 102 are formed by segregation. A method for producing the positive electrode active material particles 100 in this case will be described with reference to FIG.

[0072] First, starting materials are prepared (S11). Specifically, a lithium source, an element M source, magnesium The lithium source is, for example, lithium carbonate, Lithium fluoride, lithium hydroxide, etc. can be used. When element M is cobalt, For example, cobalt sources include cobalt oxide, cobalt hydroxide, cobalt oxyhydroxide, and carbonate. Cobalt, cobalt oxalate, cobalt sulfate, etc. can be used. Magnesium The source may be, for example, magnesium oxide, magnesium fluoride, or the like. As the fluorine source, for example, lithium fluoride, magnesium fluoride, etc. can be used. In other words, lithium fluoride can be used as both a lithium source and a fluorine source. Magnesium fluoride can be used as both a magnesium source and a fluorine source. Cut.

[0073] In this embodiment, lithium carbonate (Li2CO3) is used as the lithium source, and cobalt is used as the cobalt source. Cobalt oxide (Co3O4) as a source of magnesium, magnesium oxide (MgO) as a source of Lithium fluoride (LiF) is used as the lithium source and the fluorine source.

[0074] In one embodiment of the present invention, a magnesium source and a fluorine source are simultaneously mixed as starting materials. By this, the second region 102 containing magnesium and fluorine is formed on the positive electrode active material particles 10. It was possible to form it on the surface of 0.

[0075] Here, the total number of lithium atoms in the starting material is divided by the total number of atoms of element M. Let the value be (Li / M)_R.

[0076] Next, the weighed starting materials are mixed (S12). etc. can be used.

[0077] Next, the material mixed in S12 is subjected to a first heating (S13). It is preferable to carry out the heating at a temperature of 900°C or higher and 1000°C or lower. The heating time is preferably 2 hours or more and 20 hours or less. In this embodiment, the heat treatment is preferably performed at 1000° C. for 10 hours. The temperature is increased by 200°C / h and the flow rate of dry air is 10 L / min.

[0078] The first heating in S13 forms the first region 101. Here, (Li / M)_R By reducing the value of element M, the element M becomes surplus. The surplus element M causes the first region 101 Therefore, a layer mainly composed of the excess element M is likely to be formed outside the first region 10. The Li / M of the entire positive electrode active material particle 100 is made smaller than the Li / M of the composite oxide of In other words, by making the element M in a surplus state, the element A second region 102 is formed having M and oxygen.

[0079] In addition, some of the lithium is released outside the system (outside the particles produced) by the first heating in S13. In other words, some of the lithium is lost. The ratio of lithium to element M in the positive electrode active material particles after S16 is Li / M may become smaller.

[0080] The formation of the first region 101 and the second region 102 will be described in more detail below. do.

[0081] For example, when the element M is cobalt and the first region 101 has lithium cobalt oxide, The Li / M of lithium cobalt oxide is close to 1. The L of the entire positive electrode active material particle By making i / M smaller than 1, the element M and oxygen are introduced outside the first region 101. A second region 102 having the structure is formed.

[0082] Considering the loss of some lithium, (Li / M)_R should be set to, for example, less than 1.05. By reducing the thickness, a second region 102 having cobalt is formed outside the first region 101. will be done.

[0083] In addition, by increasing (Li / M)_R, the specific surface area of ​​the positive electrode active material particles becomes smaller. This may occur.

[0084] It is preferable that the second region 102 is stable during the charge and discharge process of the secondary battery. Metals other than transition metals, such as magnesium, hardly change their valence, so their compounds are transition metals. Compared to metal compounds, in secondary batteries that use oxidation-reduction reactions, such as lithium-ion batteries, The second region 102 contains magnesium, which improves the positive electrode activity. The side reaction on the surface of the substance particle 100 is suppressed. It is preferable to have ammonium.

[0085] However, according to the inventors' experiments, (Li / M)R (where element M is cobalt) As the atomic ratio of cobalt to the total of raw materials becomes smaller, the second In some cases, the first region 102 becomes thin, or the second region 102 is difficult to form.

[0086] In addition, when the second region 102 is difficult to form, the magnesium concentration of the first region 101 is The magnesium present in the first region 101 inhibits charging and discharging. For example, it may decrease the discharge capacity or deteriorate the cycle characteristics. do.

[0087] The inventors have found that by making the cobalt surplus, the first region 101 is made of cobalt oxide. A region having lithium is formed, and a region having a cobalt skeleton is formed as the second region 102. After or simultaneously with the formation of the second region 102, magnesium is segregated into the second region 102. As a result, a second region 102 containing magnesium and having a rock salt structure is formed. We discovered that this can be done.

[0088] The magnesium and fluorine are partially transported to the second region 102 by the first heating of S13. For example, magnesium is partially substituted for cobalt contained in the second region 102. In addition, fluorine may be used to partially substitute for oxygen contained in the second region 102. However, at this point, other parts of magnesium and fluorine may be transferred to lithium. It is in a state of being solid-dissolved in a complex oxide containing a metal.

[0089] Furthermore, by adding fluorine to the positive electrode active material of one embodiment of the present invention, the second region 102 Magnesium may be more likely to segregate in the alloy.

[0090] The oxygen bonded to magnesium is replaced by fluorine, and the surroundings of the replaced fluorine This may make magnesium more mobile.

[0091] Furthermore, adding magnesium fluoride to magnesium oxide may lower the melting point. The lowering of the melting point makes it easier for atoms to move during heat treatment.

[0092] Also, fluorine has a higher electronegativity than oxygen. Therefore, Even in stable compounds, the addition of fluorine causes a charge imbalance, resulting in the formation of magnesium This may weaken the bond between oxygen and the

[0093] For these reasons, by adding fluorine to the positive electrode active material of one embodiment of the present invention, This may make it easier for magnesium to move and for magnesium to segregate in the second region. do.

[0094] Next, the material heated in S13 is cooled to room temperature (S14).

[0095] Next, the material cooled in S14 is subjected to a second heating (S15). The second heating is performed at a specified temperature. The retention time is preferably 50 hours or less, and more preferably 2 hours or more and 10 hours or less. The specified temperature is preferably 500°C or higher and 1200°C or lower, and more preferably 700°C or higher. The temperature is preferably 1000°C or lower, and more preferably about 800°C. In this embodiment, the heating is performed at 800°C for 2 hours. The temperature rise rate is 200°C / h and the flow rate of dry air is 10 L / min.

[0096] By carrying out the second heating in S15, the magnesium and fluorine contained in the starting material are converted into lithium. The segregation of the composite oxide containing magnesium and a transition metal in the surface layer portion is promoted, and the magnesium in the second region 102 The concentrations of nesium and fluorine can be increased.

[0097] Finally, the material heated in S15 is cooled to room temperature and collected (S16) to form positive electrode active material particles. You can get 100 children.

[0098] By using the positive electrode active material particles described in this embodiment, high capacity and good cycle characteristics can be achieved. This embodiment mode may be used in appropriate combination with other embodiment modes. You can be there.

[0099] (Embodiment 2) In this embodiment, a secondary battery having the positive electrode active material particles 100 described in the previous embodiment is In this embodiment, examples of materials that can be used for the positive electrode, the negative electrode, and the A secondary battery in which an electrolyte solution is enclosed in an exterior body will be taken as an example for explanation.

[0100] [Positive electrode] The positive electrode has a positive electrode active material layer and a positive electrode current collector.

[0101] <Cathode active material layer> The positive electrode active material layer contains positive electrode active material particles. The positive electrode active material layer also contains a conductive additive and a barrier layer. It may also have an indium.

[0102] The positive electrode active material particles 100 described in the previous embodiment are used as the positive electrode active material particles. By using the positive electrode active material particles 100 described in the previous embodiment, it is possible to achieve a high capacity. A secondary battery with excellent cycle characteristics can be obtained.

[0103] As the conductive additive, a carbon material, a metal material, a conductive ceramic material, or the like may be used. Furthermore, a fibrous material may be used as the conductive additive. The content of the conductive additive is preferably 1 wt% or more and 10 wt% or less, and more preferably 1 wt% or more and 5 wt% or less. Bottom is more preferable.

[0104] The conductive additive can form an electrically conductive network in the active material layer. The auxiliary agent can maintain the electrical conduction path between the positive electrode active materials. By adding a conductive additive, it is possible to realize an active material layer with high electrical conductivity. do.

[0105] Examples of the conductive additive include natural graphite, artificial graphite such as mesocarbon microbeads, and carbon. Examples of carbon fibers include mesophase pitch carbon fibers. Carbon fibers such as carbon fibers, isotropic pitch-based carbon fibers, etc. can be used. Carbon nanofibers, carbon nanotubes, etc. can be used. The nanotubes can be produced by, for example, a vapor phase growth method. For example, carbon black (acetylene black (AB) etc.), graphite particles Carbon materials such as silicon, graphene, and fullerene can be used. Metal powders and fibers such as nickel, aluminum, silver, and gold, as well as conductive ceramic materials can be used.

[0106] A graphene compound may also be used as the conductive additive.

[0107] Graphene compounds have excellent electrical properties, such as high conductivity, as well as high flexibility and In some cases, the graphene has excellent physical properties, such as high mechanical strength. Graphene compounds have a planar shape. Graphene compounds enable surface contact with low contact resistance. In addition, even if the material is thin, it can have very high conductivity, and a small amount can be used efficiently in the active material layer. Therefore, graphene compounds are used as conductive additives. This is preferable because it is possible to increase the contact area between the active material and the conductive additive. In addition, it is preferable because it may be possible to reduce electrical resistance. For example, graphene or multigraphene or reduced graphene It is particularly preferable to use RGO. It refers to a compound obtained by reducing graphene oxide (GO). .

[0108] When using active material particles with a small particle size, for example, active material particles with a particle size of 1 μm or less, The specific surface area of ​​the active material particles is large, and therefore more conductive paths are required to connect the active material particles together. In such cases, graphene compounds that can efficiently form conductive paths even in small amounts are used. It is particularly preferred to use

[0109] In the following, as an example, a graphene compound is used as a conductive additive in the active material layer 200. An example of the cross-sectional configuration in this case will be described.

[0110] 3A shows a vertical cross-sectional view of the active material layer 200. The active material layer 200 is made of granular positive electrode active material. The graphene compound 201 is a conductive additive, and the binder (not shown) is a conductive particle 100. Here, the graphene compound 201 may be, for example, graphene or multigraph Here, the graphene compound 201 may have a sheet shape. In addition, the graphene compound 201 is preferably a multi-graphene or (and ) A plurality of graphenes may be partially overlapped to form a sheet.

[0111] In the vertical cross section of the active material layer 200, as shown in FIG. 3(A), the inside of the active material layer 200 In FIG. 3(A), the sheet-like graphene compound 201 is dispersed almost uniformly. The graphene compound 201 is shown in bold in the figure, but in reality it is a single layer of carbon molecules or The graphene compounds 201 are thin films having a thickness of multiple layers. The positive electrode active material particles 100 are wrapped around or covered with the positive electrode active material particles 100. Since they are formed to adhere to the surface of the substrate, they are in surface contact with each other.

[0112] Here, a plurality of graphene compounds are bonded to each other to form a mesh-like graphene compound. forming a graphene compound net or graphene net. When the active material is covered with a graphene net, the graphene net can Therefore, the amount of binder can be reduced. This allows for the active material to be used in a smaller amount or not in a larger amount, reducing the proportion of the active material in the electrode volume or weight. This makes it possible to improve the ratio, i.e., to increase the capacity of the power storage device.

[0113] Here, graphene oxide is used as the graphene compound 201, and is mixed with an active material to form an active material. After forming the layer that will become the graphene compound layer 200, it is preferable to reduce the layer. By using graphene oxide, which has extremely high dispersibility in polar solvents, The compound 201 can be dispersed approximately uniformly inside the active material layer 200. The solvent is evaporated from the dispersion medium containing the graphene oxide dispersed in the solution, and the graphene oxide is reduced. Therefore, the graphene compound 201 remaining in the active material layer 200 partially overlaps with each other. By dispersing the particles so that they come into surface contact with each other, a three-dimensional conductive path can be formed. The reduction of graphene oxide may be carried out by, for example, heat treatment or by using a reducing agent. You may go.

[0114] Therefore, unlike granular conductive additives such as acetylene black, which come into point contact with the active material, Since the phenyl compound 201 enables surface contact with low contact resistance, it is not necessary to use a conventional conductive additive. The amount of the positive electrode active material particles 100 is smaller than that of the graphene compound 201, and the electrical conductivity between the positive electrode active material particles 100 and the graphene compound 201 is improved. Therefore, the ratio of the positive electrode active material particles 100 in the active material layer 200 can be increased. This allows the discharge capacity of the power storage device to be increased.

[0115] Examples of binders include styrene-butadiene rubber (SBR), styrene-isopropyl Acrylonitrile-butadiene rubber, ethylene-styrene rubber, butadiene rubber, ethylene- It is preferable to use a rubber material such as a propylene-diene copolymer. For this purpose, fluororubber can be used.

[0116] As the binder, it is preferable to use, for example, a water-soluble polymer. As the molecule, for example, polysaccharides can be used. cellulose (CMC), methylcellulose, ethylcellulose, hydroxypropyl Cellulose, diacetyl cellulose, regenerated cellulose and other cellulose derivatives, as well as starch In addition, these water-soluble polymers can be used in combination with the above-mentioned rubber materials. It is more preferable to use

[0117] Alternatively, the binder may be polystyrene, polymethyl acrylate, or polymethacrylic acid. Methyl (Polymethyl methacrylate (PMMA)), Sodium polyacrylate, Polyvinyl Polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide , polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene Pyrene, polyisobutylene, polyethylene terephthalate, nylon, polyvinyl fluoride Polyvinyl chloride (PVDF), polyacrylonitrile (PAN), ethylene propylene diene polymer It is preferable to use materials such as polyvinyl acetate and nitrocellulose.

[0118] The binder may be used in combination with two or more of the above.

[0119] For example, a material having a particularly excellent viscosity adjusting effect may be used in combination with other materials. For example, rubber materials have excellent adhesive strength and elasticity, but it is difficult to adjust the viscosity when mixed with a solvent. In such cases, for example, mixing with a material that has a particularly excellent viscosity adjusting effect can be As a material having a particularly excellent viscosity adjusting effect, for example, a water-soluble polymer is preferably used. Furthermore, examples of water-soluble polymers that are particularly effective in adjusting viscosity include the aforementioned polysaccharides, such as cellulose, cellulose acetate, and the like. Carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxymethylcellulose Cellulose derivatives such as hydroxypropyl cellulose, diacetyl cellulose, and regenerated cellulose Conductive materials and starch can be used.

[0120] The cellulose derivatives such as carboxymethyl cellulose are, for example, The solubility increases when cellulose is converted into salts such as sodium salts or ammonium salts. The increased solubility of the solubility of the electrode makes it easier to achieve the desired viscosity. It is also possible to improve the dispersibility of the active material and other components when preparing the battery. In the present invention, the cellulose and cellulose derivatives used as binders for the electrodes include: The salts thereof are also included.

[0121] Water-soluble polymers stabilize viscosity by dissolving in water, and also work well with active materials and binders. Other materials to be combined, such as styrene butadiene rubber, are stable in aqueous solution. In addition, since it has functional groups, it is easily and stably adsorbed onto the surface of the active material. It is expected that cellulose derivatives such as carboxymethyl cellulose can be Many materials have functional groups such as hydroxyl groups and carboxyl groups. It is expected that the polymers will interact with each other and widely cover the surface of the active material.

[0122] When the binder that covers or contacts the surface of the active material forms a film, it is called a passive film. It is expected that the passive film will also act as a barrier to prevent the decomposition of the electrolyte. A film with no electrical conductivity or extremely low electrical conductivity, for example, on the surface of an active material When a passive film is formed, it is possible to suppress the decomposition of the electrolyte at the battery reaction potential. In addition, the passive film suppresses electrical conductivity and does not allow lithium ions to be conducted. It is even more desirable to

[0123] <Positive electrode current collector> The positive electrode current collector may be made of metals such as stainless steel, gold, platinum, aluminum, titanium, etc. Highly conductive materials such as these alloys can be used. It is preferable that the material does not dissolve at the potential of the positive electrode. Aluminum alloys with added elements such as candium and molybdenum that improve heat resistance It can also be formed from a metal element that reacts with silicon to form silicide. Metal elements that react with silicon to form silicide include zirconium, Titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungste The current collectors are available in foil, plate (sheet), mesh, punched, etc. The current collector may be in the form of a metal, an expanded metal, or the like. It is preferable to use one with a thickness of 5 μm or more and 30 μm or less.

[0124] [Negative electrode] The negative electrode has a negative electrode active material layer and a negative electrode current collector. and a binder.

[0125] <Negative electrode active material> As the negative electrode active material, for example, an alloy-based material or a carbon-based material can be used.

[0126] As a negative electrode active material, it can carry out charge-discharge reactions by alloying and dealloying reactions with lithium. Any element can be used, such as silicon, tin, gallium, aluminum, Germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. Materials containing at least one of these elements can be used. These elements have a higher capacity than carbon. Silicon has a particularly high theoretical capacity of 4200mAh / g. Silicon is preferably used, and compounds containing these elements may also be used. For example, SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag 3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, Examples include InSb and SbSn. Here, charging and discharging occurs through alloying and dealloying reactions with lithium. Elements that can undergo a reaction and compounds containing such elements are sometimes called alloy materials. be.

[0127] In this specification, SiO refers to, for example, silicon monoxide. Alternatively, SiO refers to Si O x Here, it is preferable that x has a value close to 1. For example, x can be expressed as The ratio is preferably 0.2 or more and 1.5 or less, and more preferably 0.3 or more and 1.2 or less.

[0128] Carbon materials include graphite, easily graphitizable carbon (soft carbon), and non-graphitizable carbon (hard carbon). carbon nanotubes, graphene, carbon black, etc. stomach.

[0129] Examples of graphite include artificial graphite and natural graphite. Examples include carbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite. Here, spherical graphite having a spherical shape can be used as the artificial graphite. For example, the MCMB may have a spherical shape, which is preferable. It is relatively easy to reduce the product, which is sometimes preferable. , flake graphite, and spherical natural graphite.

[0130] Graphite is formed when lithium ions are inserted into graphite (when lithium-graphite intercalation compounds are formed) It shows a low potential similar to that of lithium metal (0.05V to 0.3V vs. Li / Li + This allows the lithium-ion secondary battery to exhibit a high operating voltage. Furthermore, graphite has a relatively high capacity per unit volume, a relatively small volume expansion, and is inexpensive. It is preferable because it has advantages such as higher safety compared to metallic lithium.

[0131] In addition, titanium dioxide (TiO2) and lithium titanium oxide (Li4 Ti5O 12 ), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5 ), tungsten oxide (WO2), molybdenum oxide (MoO2), etc. can be done.

[0132] In addition, the negative electrode active material is a composite nitride of lithium and transition metals, which has a Li3N structure. つLi 3-x M x N (M=Co, Ni, Cu) can be used. For example, Li 2. 6Co 0.4 N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3)of This is preferable.

[0133] When a composite nitride of lithium and transition metals is used, lithium ions are included in the negative electrode active material, As a positive electrode active material, materials that do not contain lithium ions, such as V2O5 and Cr3O8, are used. In addition, when a material containing lithium ions is used as the positive electrode active material, However, by first removing the lithium ions contained in the positive electrode active material, As the lithium-transition metal nitride, a complex nitride of lithium and a transition metal can be used.

[0134] In addition, a material that undergoes a conversion reaction can also be used as the negative electrode active material. For example, lithium oxides such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO) A transition metal oxide that does not form an alloy with aluminum may be used as the negative electrode active material. Further materials that produce this include Fe2O3, CuO, Cu2O, RuO2, and Cr2O3 oxides such as CoS 0.89 , NiS, CuS and other sulfides, Zn3N2, Cu3N, Ge Nitrides such as 3N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3, etc. This also occurs with fluoride.

[0135] The conductive additive and binder that the negative electrode active material layer can have are: The same materials as the conductive additive and binder that can be used can be used.

[0136] <Negative electrode current collector> The negative electrode current collector can be made of the same material as the positive electrode current collector. It is preferable to use a material that does not alloy with carrier ions such as lithium.

[0137] [Electrolyte] The electrolytic solution contains a solvent and an electrolyte. The solvent for the electrolytic solution is preferably an aprotic organic solvent. Preferably, for example, ethylene carbonate (EC), propylene carbonate (PC), Ethylene carbonate, chloroethylene carbonate, vinylene carbonate, gamma-butyro Lactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfone oxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran One of tetrahydrofuran, sulfolane, sultone, etc., or two or more of these can be used in combinations and ratios of:

[0138] In addition, a flame-retardant and non-volatile ionic liquid (room-temperature molten salt) is used as the solvent for the electrolyte. By using one or more, the internal temperature of the storage device can be prevented from rising due to an internal short circuit or overcharging. Even if the battery is damaged, it can prevent the battery from exploding or catching fire. The electrolyte solution is made of tetravalent cations and anions. ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations Aliphatic onium cations such as imidazolium cations and pyridinium cations The following aromatic cations are also used as anions in electrolytes: monovalent amide-based Anions, monovalent methide anions, fluorosulfonate anions, perfluoroalkanes perfluoroalkyl borate anion, tetrafluoroborate anion, perfluoroalkyl bo ... phosphate anion, hexafluorophosphate anion, or perfluoroalkyl phosphate hydrate anions, etc.

[0139] The electrolyte to be dissolved in the solvent is, for example, LiPF6, LiClO4, L iAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO 4. Li2B 10 Cl 10 , Li2B 12 Cl 12 , LiCF3SO3, LiC4F9S O3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2 )2, LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, etc. One or more of these titanium salts may be used in any combination and ratio. This can be done.

[0140] The electrolyte used in the electricity storage device is free from granular waste and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as " It is preferable to use a highly purified electrolyte solution with a low content of impurities. Specifically, the weight ratio of impurities to the electrolyte is 1% or less, preferably 0.1% or less, more preferably 1% or less. It is preferably 0.01% or less.

[0141] In addition, the electrolyte contains vinylene carbonate, propane sultone (PS), and tert-butyl Benzene (TBB), Fluoroethylene carbonate (FEC), Lithium bis(oxa) Lithium borate (LiBOB), as well as dinitriles such as succinonitrile and adiponitrile Additives such as methyl methyl acrylate compounds may be added. The concentration of the additives may be, for example, 0. It may be 1 weight % or more and 5 weight % or less.

[0142] Alternatively, a polymer gel electrolyte may be used in which a polymer is swollen with an electrolytic solution.

[0143] The use of polymer gel electrolyte increases safety against leakage etc. The pond can be made thinner and lighter.

[0144] Gelled polymers include silicone gel, acrylic gel, and acrylonitrile gel. , polyethylene oxide gel, polypropylene oxide gel, fluorine-based polymer For example, a gel of a polyalcohol such as polyethylene oxide (PEO) can be used. Polymers with an alkylene oxide structure, PVDF, polyacrylonitrile, etc. For example, PVDF and hexafluoropropylene copolymers containing PVDF can be used. PVDF-HFP, a copolymer of propylene and propylene (HFP), can be used. The resulting polymer may have a porous shape.

[0145] In addition, instead of the electrolytic solution, a solid electrolyte containing an inorganic material such as a sulfide or oxide, It is possible to use a solid electrolyte containing a polymer material such as polyethylene oxide (PEO). When a solid electrolyte is used, there is no need to install a separator or spacer. Since the entire battery can be solidified, there is no risk of leakage, dramatically improving safety.

[0146] [Separator] The secondary battery preferably has a separator. Examples of the separator include: Cellulose-containing fibers such as paper, nonwoven fabrics, glass fibers, ceramics, or Nylon (polyamide), Vinylon (polyvinyl alcohol fiber), polyester, It is recommended to use synthetic fibers such as acrylic, polyolefin, and polyurethane. The separator is processed into a bag shape and arranged to encase either the positive electrode or the negative electrode. It is preferable to place

[0147] The separator may have a multi-layer structure. For example, the separator may be made of a material such as polypropylene or polyethylene. The material film is made of ceramic material, fluorine material, polyamide material, or any of these. The ceramic material can be coated with a mixture of oxides, etc. Aluminum particles, silicon oxide particles, etc. can be used. For example, PVDF, polytetrafluoroethylene, etc. can be used. Polyamide Materials used include nylon, aramid (meta-aramid, para-aramid), etc. You can be there.

[0148] Coating with ceramic materials improves oxidation resistance, making it possible to use separators during high-voltage charging and discharging. This suppresses the deterioration of the battery and improves the reliability of the secondary battery. Coating the separator and electrodes makes them adhere more easily, improving output characteristics. Coating polyamide materials, especially aramid, improves heat resistance, making it suitable for secondary batteries. Safety can be improved.

[0149] For example, a mixture of aluminum oxide and aramid is applied to both sides of a polypropylene film. Alternatively, the surface of the polypropylene film that comes into contact with the positive electrode may be coated with aluminum oxide. The surface that comes into contact with the negative electrode may be coated with a mixed material of aluminum and aramid, and a fluorine-based material may be coated on the surface. stomach.

[0150] By using a multilayer separator, the safety of the secondary battery can be maintained even if the overall thickness of the separator is thin. Since the capacity per unit volume of the secondary battery can be increased,

[0151] (Embodiment 3) In this embodiment, a secondary battery having the positive electrode active material particles 100 described in the previous embodiment is The material used in the secondary battery described in this embodiment is the same as that used in the previous embodiment. The description of the embodiments may be taken into consideration.

[0152] [Coin-type secondary battery] First, an example of a coin-type secondary battery will be described. Figure 4(A) shows a coin-type (single-layer flat type) 4(B) is a cross-sectional view of the secondary battery shown in FIG.

[0153] The coin-type secondary battery 300 has a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal. The can 302 is insulated and sealed with a gasket 303 made of polypropylene or the like. The positive electrode 304 is composed of a positive electrode current collector 305 and a positive electrode active material layer 30 provided in contact with the positive electrode current collector 305. The negative electrode 307 is formed by a negative electrode current collector 308 and a negative electrode current collector 308 which is set in contact with the negative electrode current collector 308. The negative electrode active material layer 309 is formed by the bonding.

[0154] The positive electrode 304 and the negative electrode 307 used in the coin-type secondary battery 300 are active The material layer only needs to be formed on one side.

[0155] The positive electrode can 301 and the negative electrode can 302 are made of nickel and aluminum, which are corrosion-resistant to the electrolyte. Metals such as aluminum and titanium, or alloys of these and other metals (e.g., stainless steel) In addition, nickel or aluminum can be used to prevent corrosion by the electrolyte. The positive electrode can 301 is preferably coated with a positive electrode 304, and the negative electrode can 302 is preferably coated with a negative electrode 305. 07 and electrically connect to each other.

[0156] The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated with an electrolyte, and the resulting structure is shown in FIG. ) the positive electrode can 301 is placed downward, and the positive electrode 304, separator 310, negative electrode 307, The positive electrode can 301 and the negative electrode can 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are secured together with a gasket 303 interposed therebetween. Then, the laminate is pressed to form a coin-type secondary battery 300.

[0157] By using the positive electrode active material particles described in the previous embodiment for the positive electrode 304, it is possible to achieve high capacity and small capacity. The coin-type secondary battery 300 can have excellent cycle characteristics.

[0158] [Cylindrical secondary battery] Next, an example of a cylindrical secondary battery will be described with reference to FIG. 5. Cylindrical secondary battery 600 As shown in FIG. 5(A), the battery has a positive electrode cap (battery lid) 601 on the top surface, and The battery can (external can) 602 is provided on the bottom surface. It is insulated from O2 by a gasket (insulating packing) 610.

[0159] Fig. 5(B) is a schematic diagram showing the cross section of a cylindrical secondary battery. Inside the can 602, a strip-shaped positive electrode 604 and a negative electrode 606 are placed with a separator 605 sandwiched between them. The battery element is wound around a center pin (not shown). The battery can 602 is closed at one end and open at the other end. The material is nickel, aluminum, titanium, or other metals that are resistant to corrosion by the electrolyte. Alloys of these and other metals (e.g., stainless steel) can be used. In addition, it is preferable to coat the electrode with nickel, aluminum, etc. to prevent corrosion by the electrolyte. A battery element in which a positive electrode, a negative electrode, and a separator are wound inside a battery can 602. The battery element is sandwiched between a pair of opposing insulating plates 608 and 609. The inside of the battery can 602 is filled with a non-aqueous electrolyte (not shown). A coin-type secondary battery can be used.

[0160] The positive and negative electrodes used in cylindrical secondary batteries are wound, so active materials are formed on both sides of the current collector. A positive electrode terminal (positive electrode current collecting lead) 603 is connected to the positive electrode 604. A negative electrode terminal (negative electrode current collecting lead) 607 is connected to the negative electrode 606. The negative electrode terminal 607 can be made of a metal material such as aluminum. 603 is resistance-welded to a safety valve mechanism 612, and a negative terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 is a PTC (Positive Temperature Coefficient) element. The positive electrode cap 601 is electrically connected to the positive electrode cap 601 via a coefficient 611. The safety valve mechanism 612 closes the positive electrode cap 60 when the internal pressure of the battery exceeds a predetermined threshold. The PTC element 611 cuts off the electrical connection between the positive electrode 604 and the PTC element 611. It is a thermal resistor whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current. The PTC element is made of barium titanate (BaTiO3). Semiconductor ceramics based on silicon can be used.

[0161] By using the positive electrode active material particles described in the previous embodiment for the positive electrode 604, it is possible to achieve high capacity and small capacity. The cylindrical secondary battery 600 can be made to have excellent cycle characteristics.

[0162] [Structure example of power storage device] Another structural example of the power storage device will be described with reference to FIGS.

[0163] 6(A) and 6(B) are diagrams showing the appearance of the power storage device. The device includes a plate 900 and a secondary battery 913. A label 910 is attached to the secondary battery 913. Furthermore, as shown in FIG. 6B, the power storage device has a terminal 951, a terminal 952, and It has an antenna 914 and an antenna 915.

[0164] The circuit board 900 has a terminal 911 and a circuit 912. The terminal 911 is connected to the terminal 95. 1, terminal 952, antenna 914, antenna 915, and circuit 912. A plurality of terminals 911 are provided, and each of the plurality of terminals 911 is used as a control signal input terminal, a power supply terminal, It can also be a child.

[0165] The circuit 912 may be provided on the back surface of the circuit board 900. The antenna 915 is not limited to a coil shape, but may be, for example, a wire shape or a plate shape. , Planar antenna, Aperture antenna, Traveling wave antenna, EH antenna, Magnetic field antenna, Dielectric Alternatively, an antenna such as a body antenna may be used. The flat conductor may be a flat conductor. This flat conductor functions as one of the conductors for electric field coupling. In other words, the capacitor has two conductors, one of which is an anode. The antenna 914 or the antenna 915 may be activated. Furthermore, electric power can be exchanged using an electric field.

[0166] The line width of antenna 914 is preferably larger than the line width of antenna 915. This allows the amount of power received by the antenna 914 to be increased.

[0167] The power storage device is a layer 916 between the antenna 914 and the antenna 915 and the secondary battery 913. The layer 916 has a function of shielding an electromagnetic field generated by the secondary battery 913, for example. For example, a magnetic material can be used as 916 .

[0168] The structure of the power storage device is not limited to that shown in FIG.

[0169] For example, as shown in FIGS. 7(A-1) and 7(A-2), FIGS. 6(A) and 6(B) In the secondary battery 913 shown in FIG. 1, an antenna may be provided on each of a pair of opposing surfaces. FIG. 7(A-1) is an external view seen from one side of the pair of surfaces, and FIG. 7(A-2) is 6(A) and 6(B) are external views seen from the other side of the pair of surfaces. 6A and 6B. It can be used as appropriate.

[0170] As shown in FIG. 7(A-1), a layer 916 is sandwiched between one of the two surfaces of a secondary battery 913. As shown in FIG. 7(A-2), an antenna 914 is provided on both sides of the secondary battery 913. An antenna 915 is provided on the opposite side with a layer 917 sandwiched therebetween. The layer 917 is, for example, a secondary battery 913. The layer 917 has a function of shielding the electromagnetic field generated by the magnetic field. can.

[0171] By adopting the above structure, the size of both the antenna 914 and the antenna 915 can be increased. It can be made easier.

[0172] Or, as shown in Figs. 7(B-1) and 7(B-2), In the secondary battery 913 shown in FIG. 1, a separate antenna may be provided on each of a pair of opposing surfaces. FIG. 7(B-1) is an external view seen from one side of the pair of surfaces, and FIG. 7(B-2) 6(A) and 6(B) are external views seen from the other side of the pair of surfaces. 6A and 6B. can be used as appropriate.

[0173] As shown in FIG. 7(B-1), a layer 916 is sandwiched between one of the two surfaces of the secondary battery 913. 7B-2, an antenna 914 and an antenna 915 are provided. An antenna 918 is provided on the other of the two surfaces of the substrate 13, sandwiching a layer 917 therebetween. For example, the antenna 918 has a function of performing data communication with an external device. For example, an antenna having a shape applicable to the antenna 914 and the antenna 915 is applied. As a communication method between the power storage device and other devices via the antenna 918, NF It is possible to apply a response method that can be used between the power storage device and other devices, such as can.

[0174] Alternatively, as shown in FIG. 8A, the secondary battery 913 shown in FIGS. 6A and 6B may be A display device 920 may be provided. The display device 920 is electrically connected to the terminal 911 via the terminal 919. It should be noted that the label 910 does not need to be provided in the area where the display device 920 is provided. 6(A) and 6(B) are the same as those in the power storage device shown in FIG. 6B can be used as appropriate.

[0175] The display device 920 displays, for example, an image indicating whether charging is in progress or not, an image indicating the amount of stored power, etc. The display device 920 may be, for example, an electronic paper, a liquid crystal display, an electronic For example, an electroluminescence (EL) display device can be used. By using the polarizer, the power consumption of the display device 920 can be reduced.

[0176] Alternatively, as shown in FIG. 8B, the secondary battery 913 shown in FIGS. 6A and 6B may be used. The sensor 921 may be electrically connected to the terminal 911 via a terminal 922. Note that the same parts as those in the power storage device shown in FIGS. 6A and 6B are shown in The description of the power storage device shown in FIGS. 6(A) and 6(B) can be used as appropriate.

[0177] The sensor 921 may be, for example, a sensor for measuring displacement, position, velocity, acceleration, angular velocity, number of rotations, distance, Light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, It is sufficient if it has the function of measuring flow rate, humidity, gradient, vibration, odor, or infrared. By providing the sensor 921, for example, data indicating the environment in which the power storage device is placed can be acquired. It is also possible to detect data (such as temperature) and store it in memory within the circuit 912.

[0178] Furthermore, an example of the structure of the secondary battery 913 will be described with reference to FIGS.

[0179] The secondary battery 913 shown in FIG. 9A has a terminal 951 and a terminal 952 provided inside a housing 930. The winding body 950 is impregnated with an electrolyte inside the housing 930. The terminal 952 is in contact with the housing 930, and the terminal 951 is in contact with the housing by using an insulating material or the like. It should be noted that in FIG. 9A, for convenience, the housing 930 is shown separated. However, in reality, the winding body 950 is covered by the housing 930, and the terminals 951 and 952 are extends outside the housing 930. The housing 930 may be made of a metal material (e.g., aluminum). etc.) or a resin material can be used.

[0180] As shown in FIG. 9B, the housing 930 shown in FIG. 9A may be formed from a plurality of materials. For example, the secondary battery 913 shown in FIG. 9B may be formed by a housing 930a and a housing 930b. The area surrounded by the housing 930a and the housing 930b is covered with the wound body 950. is provided.

[0181] The housing 930a can be made of an insulating material such as organic resin. By using a material such as organic resin on the surface on which the capacitor is formed, the electric field generated by the secondary battery 913 If the shielding of the electric field by the housing 930a is small, the housing 930a Antennas such as antenna 914 and antenna 915 may be provided inside the housing 930b. For example, a metal material can be used as the material.

[0182] Furthermore, the structure of the wound body 950 is shown in FIG. 10. The wound body 950 includes a negative electrode 931 and The wound body 950 has a positive electrode 932 and a separator 933. The wound body 950 has the separator 933 sandwiched therebetween. Then, the negative electrode 931 and the positive electrode 932 are stacked one on top of the other, and the laminated sheet is wound. The negative electrode 931, the positive electrode 932, and the separator 933 may be further laminated. Multiple layers may be stacked.

[0183] The negative electrode 931 is connected to the terminal 911 shown in FIG. 6 via one of the terminals 951 and 952. The positive electrode 932 is connected to the terminal 911 shown in FIG. 6 via the other of the terminals 951 and 952. is connected to.

[0184] By using the positive electrode active material particles 100 described in the previous embodiment for the positive electrode 932, a high volume This makes it possible to obtain a secondary battery 913 with excellent cycle characteristics even in a small amount.

[0185] [Laminated secondary battery] Next, an example of a laminated secondary battery will be described with reference to FIGS. If the laminated secondary battery is made flexible, it can be made with fewer flexible parts. If the secondary battery is mounted in an electronic device that has some of the same characteristics, the secondary battery can be bent in accordance with the deformation of the electronic device. It is also possible.

[0186] A laminated secondary battery 980 will be described with reference to FIG. The secondary battery 980 has a wound body 993 shown in FIG. 4, a positive electrode 995, and a separator 966. The wound body 993 is the same as that described in FIG. Similar to the wound body 950, the negative electrode 994 and the positive electrode 995 are stacked with the separator 966 sandwiched therebetween. The laminated sheet is then wound up.

[0187] The number of layers of the negative electrode 994, the positive electrode 995, and the separator 966 may be as many as necessary. The negative electrode 994 is connected to the lead electrode 997 and the lead electrode 998. The positive electrode 995 is connected to a negative electrode current collector (not shown) via one of the lead electrodes 998. The positive electrode 997 is connected to a positive electrode current collector (not shown) via the other of the electrode 997 and the lead electrode 998. .

[0188] As shown in FIG. 11(B), a film 981 that serves as an exterior body and a film 982 having a recess are The above-mentioned wound body 993 is housed in a space formed by bonding the above-mentioned wound body 993 and the above-mentioned wound body 82 together by thermocompression bonding or the like. By doing so, a secondary battery 980 can be fabricated as shown in FIG. 93 has a lead electrode 997 and a lead electrode 998, and a film 981 and a recessed portion. The inside of the film 982 is impregnated with an electrolyte.

[0189] The film 981 and the film 982 having the recesses are made of a metal material such as aluminum. The film 981 and the film 982 having the recesses can be made of a metal or resin material. If a resin material is used as the material for the recess, when an external force is applied, the film 981 and the recess The film 982 having the above structure can be deformed to produce a flexible secondary battery. This can be done.

[0190] In addition, although Fig. 11(B) and Fig. 11(C) show examples using two films, A space is formed by folding one film, and the above-mentioned wound body 9 is inserted into the space. 93 may also be accommodated.

[0191] By using the positive electrode active material particles 100 described in the previous embodiment for the positive electrode 995, a high volume This makes it possible to obtain a secondary battery 980 with excellent cycle characteristics even in a small amount.

[0192] In addition, in FIG. 11, a secondary battery having a wound body in a space formed by a film that serves as an exterior body is shown. We have explained the example of 980, but as shown in Figure 12, A secondary battery having a plurality of rectangular positive electrodes, separators, and negative electrodes in the formed space. Good too.

[0193] The laminated secondary battery 500 shown in FIG. 12(A) includes a positive electrode current collector 501 and a positive electrode active material. A positive electrode 503 having a material layer 502 and a negative electrode current collector 504 and a negative electrode active material layer 505 are provided. The battery includes a negative electrode 506, a separator 507, an electrolyte 508, and an exterior body 509. A separator 507 is provided between a positive electrode 503 and a negative electrode 506 provided in a housing 509. The exterior body 509 is filled with an electrolyte 508. The electrolyte 508 contains The electrolyte solution shown in Embodiment Mode 2 can be used.

[0194] In the laminated secondary battery 500 shown in FIG. 12(A), a positive electrode current collector 501 and The negative electrode current collector 504 also serves as a terminal for electrical contact with the outside. A part of the electrode current collector 501 and the negative electrode current collector 504 is exposed to the outside from the outer casing 509. In addition, the positive electrode current collector 501 and the negative electrode current collector 504 may be disposed in the outer casing 509. The lead electrode is connected to the positive electrode current collector 501 or the negative electrode current collector 502 by using the lead electrode. The lead electrode may be exposed to the outside by ultrasonic bonding to the electrode current collector 504 .

[0195] In the laminated secondary battery 500, the exterior body 509 is made of, for example, polyethylene, polypropylene, or the like. On a membrane made of a material such as polypropylene, polycarbonate, ionomer, or polyamide, A thin metal film with excellent flexibility, such as aluminum, stainless steel, copper, or nickel, is applied. On the metal thin film, an insulating composite such as polyamide resin or polyester resin is used as the outer surface of the exterior body. A laminate film having a three-layer structure provided with a resin film can be used.

[0196] An example of the cross-sectional structure of a laminated secondary battery 500 is shown in FIG. For simplicity, (A) shows an example consisting of two current collectors, but in reality, it is composed of multiple electrodes. It consists of layers.

[0197] In FIG. 12(B), as an example, the number of electrode layers is set to 16. In FIG. 12(B), the negative electrode current collector 504 is made up of eight layers. 12(B) shows a structure of 16 layers in total, with 8 layers of the positive electrode current collector 501. The cross section of the extraction part is shown, and eight layers of negative electrode current collector 504 are ultrasonically bonded. Of course, the number of electrode layers is not limited to 16, and may be more or less. In this case, a secondary battery having a larger capacity can be obtained. In this case, a secondary battery can be made thin and highly flexible.

[0198] An example of an external view of a laminated secondary battery 500 is shown in FIGS. 13 and 14. 13 and 14 show a positive electrode 503, a negative electrode 506, a separator 507, an outer casing 509, a positive electrode lead The positive electrode 510 and the negative electrode 511 are provided.

[0199] 15(A) shows an external view of the positive electrode 503 and the negative electrode 506. The positive electrode 503 is connected to the positive electrode current collector 5 01, and the positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501. The electrode 503 has a region where the positive electrode current collector 501 is partially exposed (hereinafter referred to as a tab region). The electrode 506 has a negative electrode current collector 504, and the negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. The negative electrode 506 is formed in a region where the negative electrode current collector 504 is partially exposed, i.e., a tab. The area and shape of the tab regions of the positive electrode and negative electrode are the same as those in the example shown in FIG. Not limited to.

[0200] [Method for manufacturing laminated secondary batteries] Here, an example of a method for manufacturing a laminated secondary battery, the external view of which is shown in FIG. 13, will be described with reference to FIG. 5(B) and (C) will be used to explain.

[0201] First, the negative electrode 506, the separator 507, and the positive electrode 503 are stacked. The negative electrode 506, separator 507, and positive electrode 503 are shown. Next, the bonding of the tab regions of the positive electrode 503 and the bonding of the tabs of the positive electrode on the outermost surface are shown. The positive electrode lead electrode 510 is bonded to the bonding region. For example, ultrasonic welding or the like is used for bonding. Similarly, the tab regions of the negative electrodes 506 are bonded to each other, and the negative electrode is bonded to the tab region of the negative electrode on the outermost surface. The lead electrode 511 is bonded.

[0202] Next, the negative electrode 506 , the separator 507 and the positive electrode 503 are placed on the exterior body 509 .

[0203] Next, as shown in FIG. 15(C), the exterior body 509 is folded at the portions indicated by the dashed lines. After that, the outer periphery of the exterior body 509 is bonded. For example, thermocompression bonding may be used for bonding. At this time, a part (or one side) of the outer casing 509 is provided so that the electrolyte 508 can be poured therein later. A region (hereinafter referred to as an inlet) that is not joined to the substrate is provided.

[0204] Next, the electrolyte 508 is introduced into the inside of the exterior body 509 through an inlet provided in the exterior body 509. The introduction of the electrolyte 508 can be carried out under a reduced pressure atmosphere or an inert gas atmosphere. Finally, the inlet is joined. In this way, a laminated secondary battery is obtained. It is possible to fabricate a secondary battery 500 having the above structure.

[0205] By using the positive electrode active material particles 100 described in the previous embodiment for the positive electrode 503, a high volume This makes it possible to obtain a secondary battery 500 with excellent cycle characteristics at a low amount.

[0206] [Bendable secondary battery] Next, an example of a bendable secondary battery will be described with reference to FIGS. 16 and 17. do.

[0207] Figure 16(A) shows a schematic top view of a bendable battery 250. , (B2), and (C) are cut along the cutting lines C1-C2 and C3-C in FIG. 16(A), respectively. 4 is a schematic cross-sectional view taken along the line A1-A2. The battery 250 includes an exterior body 251 and an exterior The positive electrode 211a and the negative electrode 211b are housed inside the body 251. The lead 212a electrically connected to the negative electrode 211b and the lead 212b electrically connected to the negative electrode 211b 12b extends outside the exterior body 251. In addition, in the area surrounded by the exterior body 251, In addition to the positive electrode 211a and the negative electrode 211b, an electrolyte (not shown) is enclosed.

[0208] The positive electrode 211a and the negative electrode 211b of the battery 250 will be described with reference to FIG. FIG. 17(A) illustrates the stacking order of the positive electrode 211a, the negative electrode 211b, and the separator 214. FIG. 17(B) shows a perspective view of the positive electrode 211a and the negative electrode 211b, as well as a lead. 212a and lead 212b.

[0209] As shown in FIG. 17(A), the battery 250 includes a plurality of rectangular positive electrodes 211a, a plurality of rectangular The positive electrode 211a and the negative electrode 211b have a rectangular shape and a plurality of separators 214. 1b each have a protruding tab portion and a portion other than the tab. A positive electrode active material layer is formed on the portion other than the tab of the negative electrode 211b. A negative electrode active material layer is formed on the negative electrode.

[0210] The surfaces of the positive electrodes 211a on which the positive electrode active material layer is not formed and the surfaces of the negative electrodes 211b on which the negative electrode active material layer is not formed are The positive electrode 211a and the negative electrode 211b are stacked so that the surfaces on which no material layer is formed are in contact with each other. It is layered.

[0211] In addition, the surface of the positive electrode 211a on which the positive electrode active material layer is formed and the surface of the negative electrode 211b on which the negative electrode active material layer is formed are A separator 214 is provided between the formed surfaces. The resistor 214 is shown in dotted lines.

[0212] As shown in FIG. 17(B), the positive electrodes 211a and the leads 212a are connected to each other at the joints 21. The negative electrodes 211b and the leads 212b are electrically connected at the joints 5a. Electrical connection is made at 215b.

[0213] Next, the exterior body 251 will be described with reference to FIGS. 16(B1), (B2), (C), and (D). do.

[0214] The exterior body 251 has a film-like shape and is configured to sandwich the positive electrode 211a and the negative electrode 211b. The exterior body 251 is folded in two as shown in FIG. The pair of sealing portions 262 are connected to the positive electrode 211a and the sealing portion 263. The seal portion 2 is provided on either side of the negative electrode 211b and can also be called a side seal. 63 has a portion overlapping with the lead 212a and the lead 212b, and is also called a top seal. It is possible.

[0215] The exterior body 251 has ridge lines 271 and valley lines at the portions overlapping the positive electrode 211a and the negative electrode 211b. It is preferable that the sealing portion 272 of the exterior body 251 has a wave shape in which the sealing portions 272 are arranged alternately. 62 and the seal portion 263 are preferably flat.

[0216] FIG. 16(B1) is a cross section cut at the part overlapping with the ridge line 271, and FIG. 16(B2) is 16(B1) and (B2) are cross sections cut at the part where the electric current flows. It corresponds to a cross section in the width direction of the reservoir 250, the positive electrode 211a and the negative electrode 211b.

[0217] Here, the end of the negative electrode 211b in the width direction, i.e., the end of the negative electrode 211b and the seal portion 26 The distance between the battery 250 and the electrode 2 is defined as La. When the battery 250 is deformed by bending or the like, As a result, the positive electrode 211a and the negative electrode 211b are deformed so as to be displaced from each other in the length direction. At this time, if the distance La is too short, the exterior body 251 and the positive electrode 211a and the negative electrode 211b may be strongly connected to each other. In particular, if the metal film of the exterior body 251 is exposed, If the metal film is exposed to the electrolyte, it may be corroded by the electrolyte. It is preferable to set the distance La as long as possible. On the other hand, if the distance La is set too long, This increases the volume of the battery 250.

[0218] In addition, the greater the total thickness of the stacked positive electrode 211a and negative electrode 211b, the greater the It is preferable to increase the distance La between 1b and the seal portion 262.

[0219] More specifically, the total thickness of the stacked positive electrode 211a and negative electrode 211b is defined as thickness t. When the distance La is 0.8 times or more and 3.0 times or less, preferably 0.9 times or more and 2.0 times or less, of the thickness t, The distance La is preferably 0.5 times or less, and more preferably 1.0 times or more and 2.0 times or less. By setting the value in this range, a compact battery with high reliability against bending can be realized. do.

[0220] Furthermore, when the distance between the pair of seal portions 262 is a distance Lb, the distance Lb is a and the width of the negative electrode 211b (here, the width Wb of the negative electrode 211b). This is preferable because it prevents the battery 250 from being damaged when repeatedly bent or deformed. Even if the positive electrode 211a and the negative electrode 211b come into contact with the exterior body 251, Since a part of 211b can be shifted in the width direction, the positive electrode 211a and the negative electrode 211b This effectively prevents the exterior body 251 from rubbing against each other.

[0221] For example, the difference between the distance La between the pair of seal portions 262 and the width Wb of the negative electrode 211b is The thickness is 1.6 times or more and 6.0 times or less, preferably 1.8 times or more, the thickness t of the positive electrode 211a and the negative electrode 211b. It is preferable that the ratio is 2.0 times or more and 5.0 times or less, and more preferably 2.0 times or more and 4.0 times or less. stomach.

[0222] In other words, it is preferable that the distance Lb, the width Wb, and the thickness t satisfy the relationship of the following formula 1: I wish.

[0223]

number

[0224] Here, a is 0.8 or more and 3.0 or less, preferably 0.9 or more and 2.5 or less, and more preferably The value must be between 1.0 and 2.0.

[0225] FIG. 16(C) is a cross section including the lead 212a, and shows the battery 250, the positive electrode 211a, and 16(C), the bent portion corresponds to the cross section of the negative electrode 211b in the longitudinal direction. In 261, the ends of the positive electrode 211a and the negative electrode 211b in the length direction and the outer casing 251 It is preferable to have a space 273 between them.

[0226] FIG. 16(D) shows a schematic cross-sectional view of the battery 250 when bent. , which corresponds to the cross section taken along the cutting line B1-B2 in FIG. 16(A).

[0227] When the battery 250 is bent, the part of the exterior body 251 located on the outside of the bend stretches, and the part located on the inside More specifically, the part located on the outside of the exterior body 251 is deformed so as to shrink. The component deforms so that the amplitude of the wave becomes smaller and the period of the wave becomes larger. The part located inside 1 deforms so that the wave amplitude is large and the wave period is small. In this way, the deformation of the exterior body 251 causes the load on the exterior body 251 to increase as the exterior body 251 is bent. Since the stress caused by the expansion and contraction is alleviated, the material that constitutes the exterior body 251 does not need to expand and contract. As a result, the battery 250 can be bent with a small force without damaging the exterior body 251.

[0228] Furthermore, as shown in FIG. 16(D), when the battery 250 is bent, the positive electrode 211a and the negative electrode 211b are bent. At this time, the plurality of stacked positive electrodes 211a and negative electrodes 11b are displaced relative to each other. The pole 211b is fixed at one end on the seal portion 263 side by the fixing member 217, so that the pole 211b is not bent. The amount of deviation increases as the distance approaches the edge 261. The stress applied to the positive electrode 211a and the negative electrode 211b is relieved, and the positive electrode 211a and the negative electrode 211b themselves As a result, the positive electrode 211a and the negative electrode 211b are not damaged. The battery 250 can be easily bent.

[0229] In addition, a space 273 is provided between the positive electrode 211a and the negative electrode 211b and the exterior body 251. By doing so, when the battery is bent, the positive electrode 211a and the negative electrode 211b located on the inside are bent by the exterior body 2. 51 can be displaced relative to each other without contacting them.

[0230] The battery 250 illustrated in FIGS. 16 and 17 retains its exterior even after repeated bending and stretching. The damage to the positive electrode 211a and the negative electrode 211b is unlikely to occur, and the battery characteristics are unlikely to deteriorate. The positive electrode 211a of the battery 250 is provided with the positive electrode active material described in the previous embodiment. By using the material particles 100, it is possible to create a battery with higher capacity and better cycle characteristics. can.

[0231] (Fourth embodiment) In this embodiment, an example in which a secondary battery according to one embodiment of the present invention is mounted in an electronic device will be described. Reveal.

[0232] First, as explained in part of the third embodiment, a bendable secondary battery is mounted on an electronic device. Examples of such a device are shown in Figures 18(A) to 18(G). Examples of such devices include television sets (also called televisions or television receivers), computers, and monitors for computers, digital cameras, digital video cameras, digital photo frames, etc. games, mobile phones (also called mobile phones or mobile phone devices), portable game consoles, and personal digital assistants , audio playback devices, large game machines such as pachinko machines, etc.

[0233] In addition, the flexible secondary battery can be attached to the inner or outer wall of a house or building, or to an automobile. It can also be incorporated into curved surfaces of the interior or exterior of a vehicle.

[0234] FIG. 18A shows an example of a mobile phone. The mobile phone 7400 includes a housing 740 1, in addition to a display unit 7402, operation buttons 7403, an external connection port 7404, The mobile phone 7400 is equipped with a speaker 7405, a microphone 7406, and the like. The secondary battery 7407 is a secondary battery of one embodiment of the present invention. This allows us to provide lightweight, long-lasting mobile phones.

[0235] FIG. 18B shows the mobile phone 7400 in a bent state. When the entire 00 is deformed by an external force and curved, the secondary battery installed inside The secondary battery 7407 is also bent. At this time, the state of the bent secondary battery 7407 is as shown in FIG. C). The secondary battery 7407 is a thin secondary battery. The secondary battery 7407 is bent. The secondary battery 7407 is fixed in a state where it is electrically connected to the current collector 7409. It has a lead electrode.

[0236] FIG. 18(D) shows an example of a bangle-type display device. The portable display device 7100 is , a housing 7101, a display unit 7102, operation buttons 7103, and a secondary battery 7104. FIG. 18(E) shows the state of the bent secondary battery 7104. The secondary battery 7104 When the device is bent and worn on the user's arm, the housing may deform and damage part of the secondary battery 7104 or The total curvature changes. The degree of curvature at any point on the curve is expressed as the radius of the corresponding circle. The value expressed as the radius of curvature is called the curvature, and the reciprocal of the radius of curvature is called the curvature. A part of the main surface of the housing or secondary battery 7104 within the range of 40 mm to 150 mm in diameter The radius of curvature of the main surface of the secondary battery 7104 is 40 mm or more. If the thickness is within the range of 0 mm or less, high reliability can be maintained. By using the secondary battery of one embodiment of the present invention, a lightweight and long-life portable display device can be provided.

[0237] FIG. 18(F) shows an example of a wristwatch-type portable information terminal. The watch includes a housing 7201, a display unit 7202, a band 7203, a buckle 7204, and an operation button 7 205, an input / output terminal 7206, etc.

[0238] The portable information terminal 7200 is capable of performing functions such as mobile phone calls, e-mails, document browsing and creation, music playback, internet connection, and so on. It can run various applications such as internet communication and computer games. Cut.

[0239] The display surface of the display unit 7202 is curved, and the display is performed along the curved display surface. The display portion 7202 is provided with a touch sensor, and the screen can be touched with a finger or a stylus. For example, the icon 7 displayed on the display unit 7202 can be operated by touching the You can launch the application by touching 207.

[0240] The operation button 7205 is used to set the time, turn the power on and off, and turn wireless communication on and off. It has various functions such as auto-start, silent mode activation and deactivation, power saving mode activation and deactivation, etc. For example, an operating system built into the mobile information terminal 7200 can be The system also allows the functions of the operation buttons 7205 to be freely set.

[0241] In addition, the mobile information terminal 7200 is capable of performing standardized short-range wireless communication. For example, by communicating with a wireless headset, hands-free You can also make calls.

[0242] The portable information terminal 7200 also has an input / output terminal 7206, and can be connected to other information terminals via a connector. Data can be exchanged directly through the input / output terminal 7206. The charging operation can be performed by wireless power supply without going through the input / output terminal 7206. You may go.

[0243] The display portion 7202 of the portable information terminal 7200 includes the secondary battery of one embodiment of the present invention. By using the secondary battery of one embodiment of the present invention, a lightweight and long-life portable information terminal can be provided. For example, the secondary battery 7104 shown in FIG. 18(E) may be curved and inserted into the housing 7201. The flexible support 7204 may be incorporated into the band 7203 in a flexible state or may be incorporated into the band 7203 in a flexible state.

[0244] The mobile information terminal 7200 preferably has a sensor. For example, a fingerprint sensor may be used as the sensor. Human body sensors such as sensors, pulse sensors, and body temperature sensors, as well as touch sensors, pressure sensors, and acceleration sensors It is preferable that a sensor, etc. be installed.

[0245] FIG. 18G shows an example of a wristband-type display device. The display device 7300 has a display unit The display device 7300 includes a secondary battery 7304 according to one embodiment of the present invention. The display portion 7304 may be provided with a touch sensor, and may function as a portable information terminal. It is also possible to do so.

[0246] The display surface of the display unit 7304 is curved, and images are displayed along the curved display surface. The display device 7300 can also communicate with the display device 7300 by short-distance wireless communication according to a communication standard. You can change the situation.

[0247] The display device 7300 is also equipped with an input / output terminal, and can be directly connected to other information terminals via a connector. It is possible to exchange data and also charge via the input / output terminal. The charging operation may be performed by wireless power supply without using the input / output terminals.

[0248] When the secondary battery of one embodiment of the present invention is used as the secondary battery included in the display device 7300, A lightweight, long-life display device can be provided.

[0249] In addition, an example in which the secondary battery with good cycle characteristics shown in the above embodiment is mounted on an electronic device will be described. This will be explained using FIG. 18(H), FIG. 19 and FIG.

[0250] By using the secondary battery of one embodiment of the present invention as a secondary battery in everyday electronic devices, it is possible to achieve lighter weight and a longer life. For example, we can provide daily electronic products such as electric toothbrushes, electric shavers, Examples include electric beauty devices, and the secondary batteries for these products are designed to be easy for users to hold. Therefore, there is a demand for a secondary battery that is stick-shaped, small, lightweight, and has a large capacity.

[0251] FIG. 18(H) is a perspective view of a device also called a tobacco-containing smoking device (electronic cigarette). In FIG. 18(H), an electronic cigarette 7500 includes an atomizer 7501 including a heating element and an atomizer 7502. The secondary battery 7504 supplies power to the tomizer 7501, and the liquid supply bottle, sensor, etc. The cartridge 7502 contains a secondary battery 7504. A protection circuit for preventing overcharging and over-discharging may be electrically connected to the secondary battery 7504. The secondary battery 7504 shown in H) has an external terminal so that it can be connected to a charging device. The secondary battery 7504 is at the tip when held, so the total length is short and it is lightweight. The secondary battery according to one embodiment of the present invention has a high capacity and good cycle characteristics. Therefore, it is a small and lightweight electronic cigarette that can be used for a long period of time. We can provide 500.

[0252] Next, Fig. 19(A) and Fig. 19(B) show an example of a foldable tablet terminal. The tablet terminal 9600 shown in FIGS. 19(A) and 19(B) includes a housing 963 0a, a housing 9630b, a movable part 9640 connecting the housings 9630a and 9630b, a table display unit 9631, display mode changeover switch 9626, power switch 9627, power saving mode It has a mode changeover switch 9625, a fastener 9629, and an operation switch 9628. The display unit 9631 is made of a flexible panel, which allows a tab with a wider display area to be displayed. FIG. 19A shows a tablet terminal 9600 in an open state. 19(B) shows the tablet terminal 9600 in a closed state.

[0253] The tablet terminal 9600 also includes a housing 9630a and a housing 9630b. The power storage unit 9635 is connected to the housing 9630a through a movable part 9640. It is provided across the body 9630b.

[0254] A part of the display unit 9631 can be used as a touch panel area, and the displayed operation keys You can input data by touching the screen. By touching the area where the change button is displayed with your finger or a stylus, the display 9631 The keyboard buttons can be displayed.

[0255] A display mode changeover switch 9626 changes the display orientation, such as portrait or landscape. You can switch between black and white and color display. The switch 9625 is a device that detects the use of a light sensor built into the tablet terminal 9600. The display brightness can be optimized according to the amount of external light at the time. In addition to optical sensors, other sensors such as gyros and acceleration sensors that detect tilt are also used. An ejection device may be built in.

[0256] FIG. 19(B) shows the tablet terminal in a closed state, and the tablet terminal includes a housing 9630, a solar cell 9631, and a battery 9632. 633, and a charge / discharge control circuit 9634 including a DC / DC converter 9636. The battery 9635 is a secondary battery according to one embodiment of the present invention.

[0257] In addition, the tablet terminal 9600 can be folded in half, so when not in use, the case 9630a and The housing 9630b can be folded so that the housing 9630b overlaps the housing 9630a. Since the display portion 9631 can be protected, durability of the tablet terminal 9600 can be improved. Furthermore, the power storage unit 9635 using the secondary battery of one embodiment of the present invention has a high capacity and a good size. The tablet terminal 9600 has a long-term usability due to its durability. can provide.

[0258] In addition, the tablet terminals shown in Figures 19(A) and 19(B) are also available in various Functions that display important information (still images, videos, text images, etc.), calendars, dates, or times The function to display the above on the display unit, and to operate or edit the information displayed on the display unit by touch input. Touch input function, function to control processing by various software (programs) , etc.

[0259] The solar cell 9633 attached to the surface of the tablet terminal supplies power to the touch panel. The solar cell 9633 can be supplied to a display unit, a video signal processor, or the like. The power storage unit 9635 can be efficiently charged by providing the power storage unit 9635 on one or both sides of the housing 9630. It can be configured as follows.

[0260] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 19B are A block diagram is shown in FIG. 19(C). In FIG. 19(C), a solar cell 9633, a power storage unit 96 35, DC-DC converter 9636, converter 9637, switches SW1 to SW3, The display unit 9631 is shown, along with a power storage unit 9635, a DC-DC converter 9636, and a The inverter 9637 and the switches SW1 to SW3 are connected to the charge / discharge control circuit 9 shown in FIG. This corresponds to 634.

[0261] First, an example of operation when power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell is converted into a voltage to charge the storage battery 9635. The converter 9636 increases or decreases the voltage. When power is used from the battery 9633, the switch SW1 is turned on, and the converter 963 7, the voltage is increased or decreased to the voltage required for the display unit 9631. When not displaying in 1, turn switch SW1 off and switch SW2 on. The power storage unit 9635 may be charged.

[0262] The solar cell 9633 is shown as an example of a power generating means, but is not particularly limited thereto. Storage by other power generation means such as piezoelectric elements and thermoelectric conversion elements (Peltier elements) For example, the power supply 9635 may be configured to transmit and receive power wirelessly (contactlessly). It is also possible to combine it with a contactless power transmission module that charges the battery, or other charging means. You may do so.

[0263] Another example of electronic equipment is shown in FIG. 20. In FIG. 20, a display device 8000 is a display device according to the present invention. 8 is an example of an electronic device using a secondary battery 8004 according to one embodiment. 8000 corresponds to a display device for receiving TV broadcasts, and includes a housing 8001, a display unit 8002, a speaker, and The secondary battery 8004 according to one embodiment of the present invention includes: The display device 8000 is provided inside a housing 8001. The display device 8000 is supplied with power from a commercial power source. It is also possible to use the power stored in the secondary battery 8004. Therefore, even when power cannot be supplied from a commercial power source due to a power outage or the like, the present invention can be used. The display device 8000 can be used by using the secondary battery 8004 as an uninterruptible power supply. become.

[0264] The display unit 8002 is a display device having a light emitting element such as a liquid crystal display device or an organic EL element in each pixel. Optical devices, electrophoretic displays, DMD (Digital Micromirror Devices) ice), PDP (Plasma Display Panel), FED (Field A semiconductor display device such as a reflective LED (emission display) can be used.

[0265] In addition to TV broadcast reception, display devices are also used for personal computers and advertising displays. This includes all display devices for displaying information, such as:

[0266] In FIG. 20, a stationary lighting device 8100 includes a secondary battery 8 according to one embodiment of the present invention. 8103. Specifically, the lighting device 8100 includes a housing 8101, 20, the secondary battery 8103 is disposed in the housing 8. 101 and a light source 8102 are installed inside a ceiling 8104. 8, the secondary battery 8103 may be provided inside the housing 8101. The device 8100 can be supplied with power from a commercial power source or can be powered by a secondary battery 8103. The stored power can also be used. Therefore, in the event of a power outage, the power supply from the commercial power source can be reduced. Even when power is not available, the secondary battery 8103 according to one embodiment of the present invention can be used as an uninterruptible power supply. This allows the lighting device 8100 to be used.

[0267] In addition, FIG. 20 illustrates a lighting device 8100 of a fixed type provided on a ceiling 8104. However, in the secondary battery according to one embodiment of the present invention, the side wall 8105, the floor 8106, and the like are not included in the ceiling 8104. It can be used for a fixed lighting device provided in a window 8107 or a desk. It can also be used in upper lighting devices.

[0268] The light source 8102 can be an artificial light source that artificially obtains light using electricity. Specifically, this applies to incandescent lamps, discharge lamps such as fluorescent lamps, and light-emitting devices such as LEDs and organic EL elements. An example of the artificial light source is a light element.

[0269] In FIG. 20, an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is 8 is an example of an electronic device using a secondary battery 8203 of one embodiment of the present invention. The indoor unit 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, and the like. In the example shown, the secondary battery 8203 is provided in the indoor unit 8200. The secondary battery 8203 may be provided in the outdoor unit 8204. Both the outdoor units 8204 may be provided with a secondary battery 8203. The battery can be supplied with power from a commercial power source or stored in a secondary battery 8203. In particular, both the indoor unit 8200 and the outdoor unit 8204 are equipped with secondary batteries 8 If 203 is installed, when power cannot be supplied from the commercial power source due to a power outage, etc. However, by using the secondary battery 8203 of one embodiment of the present invention as an uninterruptible power supply, Conditioner can be used.

[0270] In addition, Figure 20 shows a separate type air conditioner consisting of an indoor unit and an outdoor unit. However, it is an integrated air conditioner that has the functions of both an indoor unit and an outdoor unit in a single housing. The secondary battery according to one embodiment of the present invention can also be used for the conditioner.

[0271] In FIG. 20, an electric refrigerator-freezer 8300 includes a secondary battery 8304 according to one embodiment of the present invention. Specifically, an electric refrigerator-freezer 8300 includes a housing 8301, It has a refrigerator door 8302, a freezer door 8303, a secondary battery 8304, etc. A secondary battery 8304 is provided inside the housing 8301. The power can be supplied from a commercial power source or can be stored in a secondary battery 8304. Therefore, when power cannot be supplied from the commercial power source due to a power outage, etc. Even in this case, by using the secondary battery 8304 of one embodiment of the present invention as an uninterruptible power supply, 8300 refrigerators and freezers will be available for use.

[0272] In addition, during times when electronic devices are not in use, the total amount of power that can be supplied by commercial power suppliers is also During the time period when the ratio of the amount of electricity actually used (called the electricity usage rate) is low, By storing power in the secondary battery, it is possible to prevent power usage rates from increasing outside the above time periods. For example, in the case of the electric refrigerator-freezer 8300, when the temperature is low, the refrigerator compartment door 83 02, during the night when the freezer door 8303 is not opened or closed, power is supplied to the secondary battery 8304. Then, as the temperature rises, the refrigerator door 8302 and the freezer door 8303 open and close. During the daytime, when the vehicle is in operation, the secondary battery 8304 is used as an auxiliary power source, thereby reducing the power consumption during the daytime. The rate can be kept low.

[0273] In addition to the electronic devices described above, the secondary battery of one embodiment of the present invention can be mounted in various electronic devices. According to one embodiment of the present invention, the cycle characteristics of the secondary battery can be improved. According to one embodiment, a high-capacity secondary battery can be obtained, and therefore the secondary battery itself can be made small and lightweight. Therefore, a secondary battery according to one embodiment of the present invention will be described in this embodiment. By incorporating the above-mentioned technology into electronic devices, it is possible to make the electronic devices lighter and with a longer lifespan. This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0274] (Embodiment 5) In this embodiment, an example in which a secondary battery according to one embodiment of the present invention is mounted on a vehicle will be described.

[0275] When a secondary battery is installed in a vehicle, it becomes a hybrid vehicle (HEV), an electric vehicle (EV), or It will be possible to realize next-generation clean energy vehicles such as plug-in hybrid vehicles (PHEVs). do.

[0276] FIG. 21 illustrates an example of a vehicle using a secondary battery according to one embodiment of the present invention. The automobile 8400 shown in FIG. 1 is an electric automobile that uses an electric motor as a power source for driving. Alternatively, an electric motor and an engine can be selected as the power source for driving. The hybrid vehicle is capable of using the secondary battery according to one embodiment of the present invention. This allows for a vehicle with a long driving range. The secondary battery not only drives the electric motor 8406 but also powers the headlights 8401 and Power can be supplied to a light emitting device such as a room light (not shown).

[0277] In addition, the secondary battery is used for the displays of the car 8400, such as the speedometer and tachometer. The secondary battery can supply power to the navigation system of the automobile 8400. The power supply can be used to power semiconductor devices such as gating systems.

[0278] The automobile 8500 shown in FIG. 21(B) has a secondary battery 8024. Charging is performed by receiving power from an external charging facility using a plug-in method or a wireless power supply method. FIG. 21(B) shows a case where a charging device 8021 is installed on a ground and a charging station 8022 is installed on a vehicle 8500. The secondary battery 8024 mounted on the device is being charged via a cable 8022. When charging, please refer to CHAdeMO (registered trademark) or Combo for charging method and connector specifications. The charging device 8021 may be a charging station installed in a commercial facility. It can be a power station or a home power source. For example, plug-in technology can Charging the secondary battery 8024 mounted on the automobile 8500 by supplying power from an external source Charging is performed by converting AC power to DC power via a converter such as an AC-DC converter. This can be done in exchange.

[0279] Although not shown, a power receiving device is mounted on the vehicle, and power is supplied contactlessly from a power transmitting device on the ground. In this case, the power transmission device is installed on the road or on the exterior wall. By incorporating this, charging can be done not only when the vehicle is stopped but also while the vehicle is moving. The vehicle may transmit and receive power between them using the same method. A solar cell may be provided in the vehicle so that the secondary battery can be charged when the vehicle is stopped or running. To supply power in the above, an electromagnetic induction method or a magnetic field resonance method can be used.

[0280] 21C shows an example of a two-wheeled vehicle using the secondary battery of one embodiment of the present invention. The scooter 8600 shown in FIG. 1(C) includes a secondary battery 8602, side mirrors 8601, and a directional indicator. The secondary battery 8602 supplies electricity to the direction indicator light 8603. can be done.

[0281] In addition, the scooter 8600 shown in FIG. 21(C) has a secondary battery 86 in the storage under the seat 8604. The secondary battery 8602 can be stored in the under-seat storage 8604, which is small. can also be stored in the under-seat storage compartment 8604.

[0282] 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. Therefore, the secondary battery itself can be made smaller and lighter. If the battery itself can be made smaller and lighter, it will contribute to reducing the vehicle's weight, which will improve the cruising range. In addition, the secondary battery installed in the vehicle can also be used as a power supply source for other purposes. In this case, for example, it is possible to avoid using commercial power sources during peak power demand periods. If we can avoid using commercial power sources during peak power demand periods, we can save energy and This can contribute to reducing carbon dioxide emissions. Since secondary batteries can be used for a long period of time, the amount of rare metals used, including cobalt, can be reduced. It can be done.

[0283] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Example]

[0284] In this example, positive electrode active material particles using cobalt as the element M were produced and evaluated. .

[0285] <Preparation of Positive Electrode Active Material Particles> Sample 1 to Sample 1 with varying concentrations of lithium and cobalt sources The positive electrode active material particles were prepared using lithium carbonate (Li2CO3), Tricobalt tetroxide (Co3O4), magnesium oxide (MgO) and lithium fluoride ( LiF) was used.

[0286] For each sample, the starting materials lithium carbonate, tricobalt tetroxide, and magnesium oxide were Nesium and lithium fluoride were weighed out so that the molar ratios were as shown in Table 1.

[0287] [Table 1]

[0288] From Table 1, the number of cobalt atoms contained in tricobalt tetroxide is The sum of the number of lithium atoms in each lithium chloride is 1.0 in Sample 1. 00 times, Sample 2 is 1.010 times, Sample 3 is 1.020 times, Sa Sample 4 is 1.030 times, Sample 5 is 1.035 times, Sample 6 is 1.035 times 1.040 times in Sample 1, 1.051 times in Sample 2, and 1.06 times in Sample 3. 1x in Sample 9, 1.081x in Sample 10, and 1.131x in Sample 11. Also, from Table 1, the number of cobalt atoms contained in tricobalt tetroxide is The number of magnesium atoms contained in aluminum is 0.010 times. The number of fluorine atoms contained in lithium fluoride is 0.020 times the number of cobalt atoms contained in cobalt. It is 0.020 times.

[0289] For each of the above 10 samples, in the same manner as the production method described in Embodiment 1, the starting materials were mixed, first heating was performed, after cooling, crushing treatment was performed, second heating was performed, and after cooling, they were recovered to obtain cathode active material particles from Sample 1 to Sample 10. As the first heating condition, treatment was performed at 1000 °C for 10 hours in a dry air atmosphere. As the second heating condition, treatment was performed at 800 °C for 2 hours in a dry air atmosphere.

[0290] <SEM Observation> For each of the obtained samples, observation was performed using a scanning electron microscope (SEM: Scanning Electron Microscope). The observation results of Sample 1 and Sample 4 are shown in FIGS. 22(A) and (B), the observation results of Sample 7 and Sample 8 are shown in FIGS. 23(A) and (B), and the observation results of Sample 9 and Sample 10 are shown in FIGS. 24(A) and (B), respectively. As Li / Co increases, it can be seen that the particles become larger. In Sample 4, many particles with a particle size of about 5 μm are observed, while in Sample 8, many particles with a particle size of about 20 μm are observed, and in Sample 10, particles with a particle size exceeding 50 μm are observed.

[0291] <Particle Size Distribution> Next, among each of the obtained samples, for Sample 1 to Sample 4 and for Sample 6 to Sample 10, measurement of the particle size distribution was performed. ​It was carried out. For the measurement, a laser diffraction particle size distribution analyzer (SALD-2200 type, manufactured by Shimadzu Corporation ) was used. The measurement results from Sample 1 to Sample 4, and from Sample 6 to Sample 10 are shown in Fig. 25. Fig. 25(A) shows the results of Sample 1 to 4 and Sample 6, and Fig. 25(B) shows the results from Sample 7 to Samp le 10, respectively. In Fig. 25, the vertical axis represents the relative intensity and the horizontal axis represents the particle size .

[0292] Also, in Fig. 26, on the horizontal axis, the value obtained by dividing the sum of the number of lithium atoms contained in each of lithium carbonate and lithium fluoride by the number of cobalt atoms contained in cobalt tetroxide ((Li / C o)_R) is shown, and on the vertical axis, the peak value of the relative intensity, here the particle size at which the relative intensity becomes the maximum value, is shown.

[0293] As (Li / Co)_R increased, the peak value of the particle size tended to increase. Also, a tendency was observed that the increase in the peak value became steep when the value of (Li / Co)_R was near 1.05 .

Example

[0294] In this example, XPS analysis was performed on Samples 1 to 10 obtained in Example 1 .

[0295] <XPS analysis> The composition obtained by XPS analysis is shown in Table 2.

[0296]

Table 2

[0297] The atomic ratios obtained by XPS for each sample are shown in FIGS. 27, 28, and 29. Figure 27 shows the ratio of lithium to cobalt (Li / Co), and Figure 28 shows the ratio of lithium to cobalt. Figure 29 shows the ratio of magnesium to cobalt (Mg / Co) and Figure 30 shows the ratio of fluorine to cobalt (F / C 28 and 29 show the steps of producing the positive electrode active material particles. The figure shows the state before the second heating (white in the figure) and the state after the completion of the preparation, i.e., after the second heating (black in the figure). The analysis results for (color) and (color).

[0298] As can be seen from Figure 27, the Li / Co ratio obtained by XPS was greater than 0.5 for each sample. The Li / Co ratio was smaller than 0.85. After Sample 8, the Li / Co ratio increased. From the results of FIG. 28 described later, the second region 102 It may be thin or barely formed. It occupies the area measured by XPS. The ratio of the first region 101 containing the lithium cobalt oxide becomes higher, and the Li / Co value becomes higher than that of the lithium cobalt oxide. It is thought that the lithium to cobalt ratio approached 1.

[0299] Also, from Figure 28, it was observed that the Mg / Co ratio tended to increase after the second heating. This suggests that the second heating further promotes segregation of magnesium.

[0300] As shown in Figure 28, Sample 1, Sample 2, and Sample 3 are XPS The Mg / Co ratio obtained by Samp was greater than 0.25 and smaller than 0.3. Sample 4, Sample 5 and Sample 6 show the Mg / C obtained by XPS. o was greater than 0.3 and smaller than 0.4. In e9, Mg / Co obtained by XPS was 0.1 or less. Also, in Sample 10, Mg was below the detection limit by XPS and was not detected. After Sample 8 where the ratio of starting materials ([Li / Co])_R is 1.061, the concentration of magnesium is low and it is possible that the second region 102 is thin or hardly formed on the surface of the positive electrode active material particles.

[0301] From FIG. 29, for Samples 1 to 6, F / Co obtained by XPS was greater than 0.05 and less than 0.15. Also, for Samples 8 to Samp le 10, F / Co obtained by XPS was greater than 0.2 and less than 0.3. After Sample 8 where the ratio of starting materials ([Li / Co])_R is 1.061 there was a tendency for the fluorine concentration to be significantly higher. This may be considered to have increased relatively as the magnesium concentration decreased.

Example

[0302] In this example, cross-sectional TEM observations were performed on Sample 4 and Sample 9 obtained in Example 1.

[0303] <TEM Observation> Each sample was thinned by FIB (Focused Ion Beam System: focused ion beam processing observation device), and then HAADF-STEM images were observed. A JEM-ARM200F manufactured by JEOL Ltd. was used for the observation. The observation results of Sample 4 are shown in FIG. 30(A), and the observation results of Sample 9 are shown in FIG. 30(B).

[0304] In FIG. 30(A), a second region 102 having a thickness of about 1.5 nm is formed on the particle surface. The region 102 and the first region 101 located inside have a crystalline structure or a crystalline structure. On the other hand, in Figure 30(B), the surface of the particle has a layered region. is not significantly observed.

[0305] In Sample 4, a layered region was formed on the surface, and the XPS results showed that this region contained magnesium. On the other hand, in Sample 9, the surface of the particles is covered with cadmium. The magnesium concentration was low and no significant layered regions were observed. [Example]

[0306] In this example, Samples 1 to 8 obtained in Example 1 were used. A coin-type secondary battery of the CR2032 type (diameter 20 mm, height 3.2 mm) was fabricated. The cycle characteristics were evaluated.

[0307] The positive electrode was made of the positive electrode active material particles prepared above, acetylene black (AB), and polypropylene. Positive electrode active material particles: AB:PVDF = 95:2.5:2.5 The slurry mixed at (weight ratio) was applied to the current collector. The positive electrodes using Samples 11 to 10 were subjected to a pressing treatment.

[0308] Lithium metal was used as the counter electrode.

[0309] The electrolyte contained 1 mol / L of lithium hexafluorophosphate (LiPF6). The electrolyte used was ethylene carbonate (EC) and diethyl carbonate (DEC). EC:DEC = 3:7 (volume ratio), vinylene carbonate (VC) was mixed at 2 wt%. The following was used.

[0310] The positive electrode can and the negative electrode can were made of stainless steel (SUS).

[0311] The measurement temperature for the cycle characteristic test was 25°C. Charging was performed at a current density of 6 The measurement was performed at a constant current of 8.5mA / g (equivalent to approximately 0.3C) and an upper voltage limit of 4.6V. The battery was charged at a constant voltage until the current reached 1.37 mA / g (equivalent to approximately 0.005 C). Constant current with a current density of 68.5mA / g (equivalent to approximately 0.3C) per unit mass, and a lower limit voltage of 2.5 The test was carried out at 1000 V. Each battery was subjected to 30 charge / discharge cycles.

[0312] FIG. 31(A) shows the results of the positive electrode active material particles Sample 1 to Sample 8. The graph shows the cycle characteristics of the secondary battery. The horizontal axis shows the number of cycles, and the vertical axis shows the energy density. The energy density is the product of the discharge capacity and the average discharge voltage. The energy density retention rate is calculated by taking the initial discharge capacity or the maximum discharge capacity as 100%. The vertical axis is expanded to make the results from Sample 1 to Sample 6 easier to see. The enlarged view is shown in FIG. 31(B).

[0313] Compared to Sample 1, Sample 2, and Sample 3, Sample The capacity retention rate improved in Sample 4, and further improved in Sample 5 and Sample 6. As the ratio of the starting materials (Li / Co)_R increases, the capacity retention rate improves. The efficiency improved, and excellent properties were obtained when the (Li / Co)_R was 1.035 or more. In Sample 7, where i / Co)_R exceeds 1.05, the capacity retention rate decreases. The capacity retention rate was even lower than that of Sample 1 to Sample 3. At 8, the capacity retention rate further decreased.

[0314] By making (Li / Co)_R smaller than 1.05, the capacity retention rate can be increased. Furthermore, by increasing the ratio to more than 1.02, the capacity retention rate could be further improved. [Explanation of symbols]

[0315] 100 Positive electrode active material particles 101 First Area 102 Second Area 103 The Third Region 200 Active material layer 201 Graphene Compounds 211a positive electrode 211b negative electrode 212a Lead 212b Lead 214 Separator 215a Joint 215b Joint 217 Fixing member 250 batteries 251 Exterior body 261 Bending part 262 Seal part 263 Seal part 271 Ridgeline 272 Valley Line 273 Space 300 Secondary battery 301 Positive electrode can 302 Anode 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 body 510 Positive lead electrode 511 Negative lead electrode 600 Secondary battery 601 Positive electrode cap 602 Battery can 603 Positive terminal 604 Positive electrode 605 Separator 606 negative electrode 607 Negative terminal 608 Insulating plate 609 Insulating board 610 Gasket 611 PTC element 612 Safety valve mechanism 900 Circuit Board 910 Label 911 terminal 912 circuits 913 Secondary battery 914 Antenna 915 Antenna 916 layers 917 layers 918 Antenna 919 terminal 920 Display device 921 Sensor 922 terminal 930 chassis 930a housing 930b housing 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 966 Separator 997 Lead Electrode 998 Lead electrode 7100 Portable display devices 7101 Housing 7102 Display section 7103 Operation button 7104 Secondary battery 7200 Personal Digital Assistant 7201 Case 7202 Display section 7203 Band 7204 Buckle 7205 Operation button 7206 Input / output terminal 7207 Icon 7300 display device 7304 Display section 7400 mobile phone 7401 Housing 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 7407 Secondary battery 7409 Current collector 7500 e-cigarettes 7501 Atomizer 7502 Cartridge 7504 Secondary battery 8000 display device 8001 Case 8002 Display section 8003 Speaker section 8004 Secondary battery 8021 Charging device 8022 cable 8024 Secondary battery 8100 Lighting equipment 8101 Housing 8102 Light source 8103 Secondary battery 8104 Ceiling 8105 Side wall 8106 beds 8107 Window 8200 indoor unit 8201 Housing 8202 Ventilation outlet 8203 Secondary battery 8204 Outdoor unit 8300 Electric refrigerator-freezer 8301 Housing 8302 Refrigerator door 8303 Freezer door 8304 Secondary battery 8400 Automobiles 8401 Headlight 8406 Electric motor 8500 cars 8600 Scooter 8601 Side mirror 8602 Secondary battery 8603 Turn signal light 8604 Under-seat storage 9600 tablet device 9625 Switch 9626 Switch 9627 Power Switch 9628 Operation Switch 9629 Fasteners 9630 chassis 9630a housing 9630b housing 9631 Display section 9633 Solar Cells 9634 Charge / Discharge Control Circuit 9635 Electricity storage unit 9636 DC / DC Converter 9637 Converter 9640 Moving parts

Claims

1. a positive electrode active material particle having a first region and a second region, the second region has a region that contacts the outside of the first region, the first region comprises lithium, cobalt, and oxygen; the second region comprises cobalt, oxygen, magnesium, and fluorine; the atomic ratio of lithium to cobalt (Li / Co) measured by X-ray photoelectron spectroscopy is 0.5 or more and 0.85 or less; Positive electrode active material particles, in which the atomic ratio of magnesium to cobalt (Mg / Co) measured by X-ray photoelectron spectroscopy is 0.2 or more and 0.5 or less.

2. In claim 1, The thickness of the second region is 0.5 nm or more and 50 nm or less.

3. In claim 1 or claim 2, the first region has a layered rock salt type crystal structure, The second region is a positive electrode active material particle having a rock salt type crystal structure.

4. In any one of claims 1 to 3, the crystal structure of the first region is represented by space group R-3m, The crystal structure of the second region is expressed by the space group Fm-3m.

5. In any one of claims 1 to 4, Positive electrode active material particles having an atomic ratio of fluorine to cobalt (F / Co) of 0.02 or more and 0.15 or less as measured by X-ray photoelectron spectroscopy.

Images