Positive electrode active material particle

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, or an electronic device. Or electronic equipment and its operating system. Regarding the system.

[0002] In this specification, the term "electricity storage device" refers to any element or device having an electricity storage function. For example, lithium-ion secondary batteries and other storage batteries (also called secondary batteries) These include lithium ion capacitors and electric double layer capacitors.

[0003] In addition, in this specification, the term "electronic device" refers to any device having a power storage device. An electro-optical device having a power storage device, an information terminal device having a power storage device, and the like are all electronic devices. [Background technology]

[0004] In recent years, various types of energy storage devices, such as lithium-ion secondary batteries, lithium-ion capacitors, and air batteries, have become available. The development of lithium-ion secondary batteries, which have high output and capacity, is particularly popular. , mobile phones, smartphones, notebook computers and other portable information terminals, portable 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 increasing along with the development of the semiconductor industry, such as automobiles. They have become indispensable in today's information society as a source of information.

[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] In order 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] JP 2012-018914 A [Patent Document 2] JP 2016-076454 A Summary of the Invention [Problem to be solved by the invention]

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

[0009] One embodiment of the present invention is a lithium-ion secondary battery that can reduce the charge-discharge cycle time. It is an object of the present invention to provide a positive electrode active material particle 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 and discharge characteristics. An object of one embodiment is to provide a secondary battery that is safe or highly reliable.

[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. Problems other than these can be extracted from the claims. [Means for solving the problem]

[0012] 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 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 elements 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 to element M measured by X-ray photoelectron spectroscopy is 0.85 or less. The molecular weight ratio (Mg / M) of the positive electrode active material particles is 0.2 to 0.5. The light is used, for example, to analyze 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 in contact with the outside of the first region, and the first region is a lithium , an element M, and oxygen, the element M being selected from cobalt, manganese, and nickel. The second region is one or more elements selected from the group consisting of the elements 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 contained 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-mentioned configuration, 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-mentioned configuration, 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 structure, one of the plurality of raw materials is a compound having an element M, Another of the raw materials is a compound having lithium, and another of the raw materials is a compound having 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. Effect of the Invention

[0023] According to one embodiment of the present invention, by using the lithium ion secondary battery, It is possible to provide a positive electrode active material in which the capacity decrease caused by the charging is suppressed. It is also possible to provide a secondary battery having excellent charge / discharge characteristics. In addition, a secondary battery having 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 description of the drawings]

[0024] [Figure 1] 4A to 4C are diagrams illustrating an example of a positive electrode active material particle. [Diagram 2] 4A to 4C are diagrams illustrating an example of a method for manufacturing positive electrode active material particles. [Diagram 3] FIG. 13 is a cross-sectional view of an active material layer in the case where a graphene compound is used as a conductive assistant. [Figure 4] FIG. 2 is a diagram illustrating a coin-type secondary battery. [Diagram 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 are diagrams illustrating examples of electronic devices. [Figure 19] 1A to 1C are diagrams illustrating examples of electronic devices. [Figure 20] 1A to 1C are diagrams illustrating examples of electronic devices. [Figure 21] 1A to 1C are diagrams illustrating examples of electronic devices. [Figure 22] SEM observation results. [Diagram 23] SEM observation results. [Figure 24] SEM observation results. [Diagram 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. [Diagram 30] Figure showing HAADF-STEM image. [Diagram 31] FIG. 4 is a graph showing the maintenance rate of the energy density of a secondary battery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following description, and it is understood by those skilled in the art that various changes can be made in form and detail. The present invention is not limited to the description of the following embodiments. It is not something that is done.

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

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

[0028] In the present specification and the like, a layered rock-salt type crystal of a 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 is Since lithium is regularly arranged to form a two-dimensional plane, two-dimensional diffusion of lithium is possible. 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 similarity to the structure of a two-dimensional interface is referred to as epitaxy. Crystal growth that resembles the structure of a two-dimensional interface is called epitaxial growth. Topotachian: to have dimensional structural similarity or to have the same crystallographic orientation Therefore, in the case of topotaxis, when a part of the cross section is observed, two regions (for example For example, the crystal orientation of the underlying region and the grown region is the same.

[0030] The rock salt crystal structure is a structure in which cations and anions are arranged alternately. There may be ion or anion 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, the cubic close-packed structure is formed by anions. 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 type crystals and rock salt type 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. It can be said 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 comes into contact with the {001} plane of lithium cobalt oxide, When the (104) plane of lithium cobalt oxide contacts the {001} plane of magnesium oxide, When the (0-14) plane of lithium cobalt oxide contacts the {001} plane of magnesium oxide, When the (001) plane of magnesium oxide comes into contact with the {111} plane of lithium cobalt oxide, 012) plane comes into contact with the {111} plane of magnesium oxide, etc.

[0033] The alignment of the crystal orientations in the two regions is confirmed by TEM (transmission electron microscope) and STEM ( Scanning transmission electron microscope (HAADF-STEM) image, High-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image This can be judged from the images obtained by ABF-STEM (annular bright-field scanning transmission electron microscope), 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, TEM images, etc. The difference in the 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 less than 2.5 degrees. In addition, the 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, but in such cases, the alignment of the metal elements is considered to be consistent. It is possible to determine the following.

[0034] Space groups are used, for example, in X-ray diffraction, electron diffraction, STEM images, and TEM images. For example, the structure can be analyzed and obtained by FFT of the 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 NMR (NMR) Reaction 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 may be said that at least a portion of the film 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 some cases, the boundary between the two regions is not clear. In FIG. 1(A), the first region 101 and the second region The region 102 is divided by a dotted line, and the concentration gradient of an element across the dotted line is shown in gray. In FIG. 1B and subsequent figures, 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 will be shown only by a dotted line. More details will be provided later.

[0039] As shown in FIG. 1B, the positive electrode active material particle 100 has a second region 102 therein. For example, when the first region 101 is polycrystalline, the second region 102 may exist at the grain boundary. In addition, the second region may be present in the portion of the positive electrode active material particle 100 having the crystal defect. In this specification, the crystal defect is a defect observed by TEM. This refers to possible defects in the crystal, 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 first 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, for example, solid phase A. The second region 102 may be, for example, For example, it may be called solid phase B.

[0043] <First Region 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, one or more of manganese, cobalt, and nickel are preferably used. In other words, the first region 101 can use only cobalt as a transition metal. Alternatively, two types of metals, cobalt and manganese, may be used. Alternatively, cobalt, manganese, nickel, For example, aluminum may be used in addition to the transition metal as element M. Metals other than transition metals may also be used.

[0045] That is, the first region 101 is made of one of lithium cobalt oxide, lithium nickel oxide, and cobalt oxide. Lithium cobalt oxide with manganese substituted in the middle, lithium nickel-manganese-cobalt oxide Lithium-cobalt-lithium aluminate, lithium-cobalt-lithium aluminate, and other composites containing lithium and transition metals 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 Moreover, when the first region 101 has a layered rock salt type crystal structure, it is unexpectedly preferable. However, if the entire first region 101 is The crystal structure may not be a layered rock salt type. For example, the first region 101 may have a crystal defect in part. A part of the first region 101 may be amorphous or may have another crystal structure. It may have.

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

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

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

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

[0051] The magnesium oxide is partially replaced by fluorine, which improves 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 less soluble in hydrofluoric acid.

[0052] If the second region 102 is too thin, its function as a covering layer is reduced. This leads to a decrease in capacitance. Therefore, the thickness of the second region 102 is set to be 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, the cross section can be exposed and then observed using a TEM.

[0054] If the second region 102 has a rock salt type crystal structure, the crystal orientation of the second region 102 and the first region 101 will be the same. 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] In general, the positive electrode active material particles 100 lose cobalt, manganese, etc. as they are repeatedly charged and discharged. Side effects include 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 on the surface, 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 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 By reducing the Li / M ratio, 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 are 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 becomes larger. As the average particle size increases, the specific surface area decreases. In such a case, the active material particles may cause side reactions such as decomposition of the electrolyte. 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, for example, an irreversible reaction during charging and discharging of a secondary battery. .

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

[0061] The fluorine contained in the second region 102 is MgF 2 , LiF, CoF 2 Bonding state other than Specifically, the surface of the positive electrode active material particle 100 is examined by XPS ( When analyzed by 1-d FT-IR photoelectron spectroscopy, the fluorine binding energy peak was 682 eV. It is preferable that the energy is 685 eV or less, and more preferably about 684.3 eV. This is MgF 2 , LiF.

[0062] In this specification, the peak position of the bond 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 bond energy at which the bond is 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) images. Energy dispersive X-ray analysis (EDX), time-of-flight SIMS (ToF-SIMS) Depth analysis by secondary ion mass spectrometry, XPS, Auger electron spectroscopy, TDS ( It can be confirmed that the composition is different by thermal desorption spectroscopy etc. For example, TEM images In the STEM images, differences in the constituent elements are observed as differences in the brightness of the images. It can be seen that the constituent elements of the first region 101 and the second region 102 are different. It can also be seen 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 performed by Auger electron spectroscopy, TDS, or the like.

[0065] XPS is capable of quantitatively analyzing about 5 nm from the surface of the positive electrode active material particle 100 . 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 first 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 ratio measured by XPS in the positive electrode active material particles 100 is, for example, 0.5 or more. It is less than 0.85.

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

[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, for example, by electron diffraction patterns or T It can be evaluated by analyzing the inverse fast Fourier transform image of the EM image.

[0070] <Third Area 103> In the above, 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 may be provided, for example, so as to be in contact with at least a portion of the second region 102. The third region 103 may be a coating containing carbon, such as a graphene compound. Alternatively, it may be a coating having a decomposition product of lithium or the electrolyte. When the positive electrode active material particles 100 are a coating containing carbon, the positive electrode active material particles 100 and the positive electrode active material particles 1 In addition, the third region 103 can increase the electrical conductivity between the lithium ion battery 100 and the current collector. In the case of a coating containing a decomposition product 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 can 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 (Li 2 CO 3 ), as a source of cobalt Cobalt oxide (Co 3 O 4), magnesium oxide (MgO) as a magnesium source, 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 mixed together as starting materials. In this way, the second region 102 having magnesium and fluorine is formed in the positive electrode active material particle 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). The first heating is performed at a temperature of 800° C. or more. It is preferable to carry out the treatment at a temperature of 1050°C or lower, and more preferable to carry out the treatment 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 a first region 101. Here, (Li / M)_R By reducing the amount of the element M, the element M becomes excessive. The excessive element M causes the first region 101 For example, a layer mainly composed of the element M is likely to be formed on the outside of the first region 10. The Li / M of the entire positive electrode active material particle 100 is 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 comprises lithium cobalt oxide, The Li / M value of lithium cobalt oxide is close to 1. The L By making i / M smaller than 1, the element M and oxygen are distributed 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 of the first region 101, 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 be the case.

[0084] It is preferable that the second region 102 is stable even during the charge and discharge process of the secondary battery. Metals other than transition metals, such as magnesium, hardly change valence, so their compounds are transition metals. Compared to metal compounds, in secondary batteries that use redox reactions such as lithium ion batteries, It can be said that the second region 102 is more stable because it contains magnesium. The side reaction on the surface of the substance particle 100 is suppressed. Therefore, the second region 102 is made of magnesium. It is preferable to have a .mu.m.

[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 the 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 reduce the discharge capacity or deteriorate the cycle characteristics. do.

[0087] The inventors have made the first region 101 a cobalt oxide film by making the cobalt surplus. 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 having magnesium and 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. Magnesium, for example, partially substitutes for cobalt contained in the second region 102. In addition, fluorine may be used to partially substitute for oxygen in the second region 102. However, at this point, other parts of magnesium and fluorine may undergo transition with lithium. It is in a state of being solid-dissolved in a complex oxide containing a metal.

[0089] In addition, by adding fluorine to the positive electrode active material of one embodiment of the present invention, the second region 102 Magnesium may be easily segregated in the steel.

[0090] The oxygen that bonds with magnesium is replaced with fluorine, and the surroundings of the replaced fluorine Magnesium may become more mobile in

[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, magnesium oxide Even in stable compounds, the addition of fluorine causes charge imbalance, resulting in magnesium This can weaken the bond between oxygen and oxygen.

[0093] For these reasons, by adding fluorine to the positive electrode active material of one embodiment of the present invention, This may lead to magnesium segregation 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 to 10 hours. 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] The second heating step of S15 converts magnesium and fluorine contained in the starting material into lithium. 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 is The concentrations of cation and fluorine can be increased.

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

[0098] By using the positive electrode active material particles described in this embodiment, it is possible to obtain a high capacity and good cycle characteristics. This embodiment may be used in appropriate combination with other embodiment modes. There can be.

[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 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 includes positive electrode active material particles. The positive electrode active material layer also includes a conductive additive and a barrier layer. It may also have an indium.

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

[0103] As the conductive assistant, a carbon material, a metal material, a conductive ceramic material, or the like is used. In addition, a fibrous material may be used as the conductive assistant. 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. Below is more preferable.

[0104] The conductive assistant 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 assistant, it is possible to realize an active material layer having high electrical conductivity. do.

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

[0106] In addition, a graphene compound may be used as the conductive assistant.

[0107] Graphene compounds have excellent electrical properties, including high electrical conductivity, as well as high flexibility and In addition, the graphene may have 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. A conductive path can be formed. 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 assistant. In addition, it is preferable because it may be possible to reduce electrical resistance. For example, graphene or multi-graphene or reduced graphene It is particularly preferable to use RGO, which is, for example, an acid This refers to a compound obtained by reducing graphene oxide (GO). .

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

[0109] In the following, as an example, a graphene compound is used as a conductive assistant 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 conductive particles 100, the graphene compound 201 as a conductive assistant, and a binder (not shown) are Here, the graphene compound 201 may be, for example, graphene or multi-graph 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. 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 or covered with the positive electrode active material particles 100. Since they are formed to adhere to the surfaces of the electrodes, 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. The graphene compound is then bonded to a graphene sheet (hereinafter referred to as a graphene compound net or a graphene net). When the active material is covered with a graphene net, the graphene net can Therefore, the amount of binder can be reduced. Since it is possible to use or not use the active material, the proportion of the active material in the electrode volume and weight can be reduced. The ratio can be improved, that is, the capacity of the power storage device can be increased.

[0113] Here, graphene oxide is used as the graphene compound 201, and is mixed with an active material to form an active material. After the layer that becomes the graphene layer 200 is formed, it is preferable to reduce the layer. In addition, 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 removed by evaporation 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 performed, for example, by 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 granular positive electrode active material particles 100 and the graphene compound 201 is smaller than that of the graphene compound 201. Therefore, the ratio of the positive electrode active material particles 100 in the active material layer 200 can be increased. This makes it possible to increase the discharge capacity of the power storage device.

[0115] Examples of binders include styrene-butadiene rubber (SBR) and styrene-isopropanol. Acrylonitrile-butadiene rubber, butadiene rubber, ethylene-styrene rubber 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. The molecule may be, for example, a polysaccharide. Chilled cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl Cellulose, diacetyl cellulose, regenerated cellulose and other cellulose derivatives, starch, etc. In addition, these water-soluble polymers can be used in combination with the above-mentioned rubber materials. It is more preferable to use it.

[0117] Alternatively, the binder may be polystyrene, polymethyl acrylate, or polymethacrylate. Methyl (Polymethylmethacrylate (PMMA)), Sodium polyacrylate, Polyvinyl chloride 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 of two or more of the above.

[0119] For example, a material having a particularly excellent viscosity adjusting effect may be used in combination with another material. 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, it is possible to mix the material with a particularly excellent viscosity adjusting effect. As a material having a particularly excellent viscosity adjusting effect, for example, a water-soluble polymer is preferably used. In addition, examples of water-soluble polymers that are particularly effective in adjusting viscosity include the above-mentioned polysaccharides, such as cellulose, polysaccharides, and polysaccharides such as cellulose. Carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxy Cellulose derivatives such as dipropyl cellulose, diacetyl cellulose, and regenerated cellulose Conductive materials and starch can be used.

[0120] In addition, cellulose derivatives such as carboxymethyl cellulose are, for example, The solubility of cellulose is increased by converting it into a salt such as sodium salt or ammonium salt. The higher the solubility, the easier it becomes to exert the effect of a viscosity adjuster. It is also possible to improve the dispersibility of the active material and other components when preparing a battery. In the present invention, the cellulose and cellulose derivatives used as the binder of the electrode include: This also includes salts thereof.

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

[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 act as a barrier against the decomposition of the electrolyte. A film with no electrical conductivity or with very 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. In addition, the material used for the positive electrode current collector can be made of highly conductive materials such as these alloys. 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 a silicide. Metal elements that react with silicon to form silicide include zirconium, Titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten 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 recommended to use one with a diameter 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. The negative electrode active material layer contains a conductive additive and 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 and discharge reactions by alloying and dealloying reactions with lithium. Any possible element can be used, for example silicon, tin, gallium, aluminum, Germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. Materials containing at least one of these elements can be used. These elements have a low capacity compared to carbon. Silicon has a high theoretical capacity of 4200mAh / g. It is preferable to use silicon, and compounds containing these elements may also be used. For example, SiO, Mg 2 Si, Mg 2 Ge, SnO, SnO 2 , Mg 2 Sn, SnS 2 , V 2 Sn 3 , FeSn 2 , CoSn 2 , Ni 3 Sn 2 , Cu 6 Sn 5 , Ag 3 Sn, Ag 3 Sb, Ni 2 MnSb, CeSb 3 , LaSn 3 , La 3 Co 2 Sn 7 , CoSb 3 , InSb, SbSn, etc. Here, charging and discharging are performed by alloying and dealloying reactions with lithium. Elements capable of undergoing 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-based materials include graphite, 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 of artificial graphite include meso graphite. Examples include carbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite. Here, as the artificial graphite, spherical graphite having a spherical shape can be used. For example, the MCMB may have a spherical shape, which is preferred. It is relatively easy to reduce the product, which may be preferable. , flake graphite, and spherical natural graphite.

[0130] Graphite is formed when lithium ions are inserted into graphite (lithium-graphite intercalation compound is 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. In addition, graphite has a relatively high capacity per unit volume, a relatively small volume expansion, and is inexpensive. It is preferable because it has the advantage of being safer than metallic lithium.

[0131] Titanium dioxide (TiO 2 ), lithium titanium oxide (Li 4 Ti 5 O 12 ), lithium-graphite intercalation compound (Li x C 6), niobium pentoxide (Nb 2 O 5 ), tungsten oxide (WO 2 ), molybdenum oxide (MoO 2 ) and other oxides. can be done.

[0132] In addition, the negative electrode active material is a complex nitride of lithium and transition metals, Li 3 N-type structure Li 3-x M x N (M=Co, Ni, Cu) can be used. For example, Li 2. 6 Co 0.4 N 3 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, the negative electrode active material contains lithium ions, , V that does not contain lithium ions as the positive electrode active material 2 O 5 , Cr 3 O 8 Combined with materials such as 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 be used as the negative electrode active material. For example, lithium oxide such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO) A transition metal oxide that does not form an alloy with the metal may be used as the negative electrode active material. Further examples of materials in which this occurs include Fe 2 O 3 ,CuO,Cu2 O, RuO 2 , Cr 2 O 3 Oxides such as CoS 0.89 , NiS, CuS and other sulfides, Zn 3 N 2 , Cu 3 N, Ge 3 N 4 Nitrides such as NiP 2 , FeP 2 , CoP 3 Phosphides such as FeF 3 , BiF 3 etc. This also occurs with fluoride.

[0135] The conductive assistant 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. Preferable examples include 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 ethyl, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethylsulfate phthalocyanine, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, One of tetrahydrofuran, sulfolane, sultone, etc., or two or more of these can be used in any combination and ratio.

[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 increased due to an internal short circuit or overcharging. Even if the battery is heated, it can prevent the battery from bursting or catching fire. The electrolyte solution is made of cations and anions. Ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations Aliphatic onium cations such as imidazolium cations and pyridinium cations The aromatic cations are also used as anions in the electrolyte. Anions, monovalent methide anions, fluorosulfonate anions, perfluoroalkyl sulfonic acid anion, tetrafluoroborate anion, perfluoroalkyl borate anion phosphate anion, hexafluorophosphate anion, or perfluoroalkyl phosphat ate anion, etc.

[0139] The electrolyte to be dissolved in the above-mentioned solvent is, for example, LiPF 6 , LiClO 4 , L iAsF 6 , LiBF 4 , LiAlCl 4 , LiSCN, LiBr, LiI, Li 2 SO 4 , Li2 B 10 Cl 10 , Li 2 B 12 Cl 12 , LiCF 3 SO 3 , LiC 4 F 9 S O 3 , LiC(CF 3 SO 2 ) 3 , LiC(C 2 F 5 SO 2 ) 3 , LiN(CF 3 SO 2 ) 2 , LiN(C 4 F 9 SO 2 )(CF 3 SO 2 ), LiN(C 2 F 5 SO 2 ) 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 of 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 having 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 fluorine compounds may be added. The concentration of the additives is, for example, 0. It may be set to 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] By using a polymer gel electrolyte, safety against leakage etc. is improved. The pond can be made thinner and lighter.

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

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

[0146] [Separator] The secondary battery preferably has a separator. Examples of the separator include Cellulose-containing fibers, including paper, nonwoven fabrics, glass fibers, ceramics, or Nylon (polyamide), Vinylon (polyvinyl alcohol fiber), polyester, a 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, fluorine, polyamide, or other materials. The ceramic material can be, for example, an oxide. Aluminum particles, silicon oxide particles, etc. can be used. Fluorine-based materials include: For example, PVDF, polytetrafluoroethylene, etc. can be used. Polyamide Materials used include nylon, aramid (meta-aramid, para-aramid), etc. There can be.

[0148] Coating with ceramic materials improves oxidation resistance, making it ideal for use as a separator during high-voltage charging and discharging. This suppresses the deterioration of the data and improves the reliability of the secondary battery. Coating the separator and electrodes makes them more easily adhered to each other, improving output characteristics. Coating polyamide materials, especially aramid, improves heat resistance, making them ideal 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 multi-layered separator, the safety of the secondary battery can be maintained even if the overall thickness of the separator is thin. Since the above-mentioned condition can be maintained, 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 of the above-mentioned embodiment. Please refer to the description of the embodiments.

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

[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. The negative electrode 307 is formed by a negative electrode current collector 308 and a negative electrode current collector 308 are provided so as to be in contact with the negative electrode current collector 308. The negative electrode active material layer 309 is formed by applying a negative electrode active material layer 309 to the negative electrode.

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

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

[0156] The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated with an electrolyte, and then the negative electrode 307, the positive electrode 304, and the separator 310 are impregnated with an electrolyte. As shown in FIG. 1, the positive electrode can 301 is placed downward, and the positive electrode 304, the separator 310, the 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 manufacture 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 low power consumption. 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. As shown in FIG. 5(A), the battery has a positive electrode cap (battery cover) 601 on the top surface and The battery can (external can) 602 is disposed on the bottom surface. It is insulated from 02 by a gasket (insulating packing) 610.

[0159] Fig. 5(B) is a schematic diagram showing a cross section of a cylindrical secondary battery. Inside the can 602, a strip-shaped positive electrode 604 and a negative electrode 606 are sandwiched between a separator 605. A wound battery element is provided. Although not shown, the battery element is wound around a center pin. 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. These and their alloys with other metals (e.g., stainless steel, etc.) can be used. In addition, in order to prevent corrosion by the electrolyte, it is preferable to coat the electrode with nickel, aluminum, or the like. 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. A non-aqueous electrolyte (not shown) is poured into the battery can 602. 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 The safety valve mechanism 612 closes the positive electrode cap 60 when the internal pressure of the battery rises above a predetermined threshold. The PTC element 611 cuts off the electrical connection between the positive electrode 604 and the positive electrode 604. It is a thermal resistor element whose resistance increases when the temperature rises, and the amount of current is limited by the increase in resistance. The PTC element is made of barium titanate (BaTiO 3 ) Semiconductor ceramics based on such a material 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 low power consumption. This results in a cylindrical secondary battery 600 with excellent cycling characteristics.

[0162] [Structural 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 external appearance of the power storage device. The battery 913 has a plate 900 and a secondary battery 913. A label 910 is attached to the secondary battery 913. As shown in FIG. 6B, the power storage device includes a terminal 951 and a terminal 952. 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 may 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. Alternatively, antenna 914 or antenna 915 may be used. The flat conductor may be a flat conductor. The flat conductor functions as one of the conductors for electric field coupling. In other words, the anode can be used as one of the two conductors of the capacitor. The antenna 914 or antenna 915 may be activated. In addition, it is also possible to exchange power 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 secondary battery 913 and between the antenna 915 and the secondary battery 913. The layer 916 has a function of blocking 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 electricity 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 faces, and FIG. 7(A-2) is 6(A) and 6(B) are external views seen from the other side of the pair of surfaces. Regarding the same parts as those of the power storage device shown in FIG. It can be used as appropriate.

[0170] As shown in FIG. 7(A-1), a layer 916 is sandwiched between one of a pair of 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 an electromagnetic field caused by the electromagnetic field. For example, a magnetic material may be used for the layer 917. 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 faces, and FIG. 7(B-2) is an external view seen from one side of the pair of faces. 6(A) and 6(B) are external views seen from the other side of the pair of surfaces. The same parts as those of the power storage device shown in FIG. 6(A) and FIG. 6(B) will be described. can be used as appropriate.

[0173] As shown in FIG. 7(B-1), a layer 916 is sandwiched between one of the pair of surfaces of a secondary battery 913. As shown in FIG. 7B-2, an antenna 914 and an antenna 915 are provided. An antenna 918 is provided on the other of the pair of surfaces of the substrate 13 with a layer 917 interposed 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 antenna 914 and antenna 915 is applied. As a method for communication 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 storage device and other devices, such as C. can.

[0174] Alternatively, as shown in FIG. 8A, the secondary battery 913 shown in FIG. 6A and FIG. 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. The label 910 does not need to be provided on the portion where the display device 920 is provided. Note that the same parts as those in the power storage device shown in FIG. 6(A) and FIG. 6(B) are ) and the power storage device in FIG. 6B can be referred to as appropriate.

[0175] The display device 920 displays, for example, an image indicating whether charging is in progress, an image indicating the amount of stored power, etc. The display device 920 may be, for example, an electronic paper, a liquid crystal display device, an electronic For example, electroluminescence (EL) display devices 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 FIG. 6A and FIG. 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 FIG. 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 detecting displacement, position, velocity, acceleration, angular velocity, number of rotations, distance, Light, liquid, magnetism, temperature, chemicals, 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] Further, a structural example of the secondary battery 913 will be described with reference to FIGS.

[0179] A 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. In FIG. 9A, the housing 930 is not in contact with the housing 930 for convenience. 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 is 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. The wound body 950 is placed in the area surrounded by the housing 930a and the housing 930b. 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 nanotube is formed, the electric field generated by the secondary battery 913 If the electric field shielding 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.

[0182] The structure of the wound body 950 is shown in FIG. The winding body 950 has a positive electrode 932 and a separator 933. Then, the negative electrode 931 and the positive electrode 932 are stacked on top of each other, and the laminated sheet is wound. The negative electrode 931, the positive electrode 932, and the separator 933 are 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 Therefore, the secondary battery 913 can have 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 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. Similarly to the wound body 950, a negative electrode 994 and a positive electrode 995 are stacked with a separator 966 interposed therebetween. The laminated sheet is then wound.

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

[0188] As shown in FIG. 11B, 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 the space formed by bonding the above-mentioned wound body 993 and the above-mentioned wound body 993 together by thermocompression bonding or the like. By this, a secondary battery 980 can be manufactured as shown in FIG. 93 has a lead electrode 997 and a lead electrode 998, a film 981, and a recess. 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 981, when an external force is applied, the recess 981 and the film 982 are The film 982 having the above structure can be deformed to produce a secondary battery having flexibility. This can be done.

[0190] In addition, although an example using two films is shown in FIG. 11(B) and FIG. 11(C), A space is formed by folding one sheet of 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 capacity This makes it possible to obtain a secondary battery 980 having excellent cycle characteristics even in a small amount.

[0192] FIG. 11 shows a secondary battery having a wound body in a space formed by a film that serves as an exterior body. 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, a negative electrode current collector 504 and a negative electrode active material layer 505 The battery includes a negative electrode 506, a separator 507, an electrolyte 508, and an exterior body 509. A separator 507 is provided between a positive electrode 503 and a negative electrode 506 provided in a housing 509. The exterior body 509 is filled with an electrolyte 508. The electrolyte 508 contains The electrolyte solution shown in the second embodiment 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 obtaining 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 exterior body 509. 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 a 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, On a membrane made of a material such as polypropylene, polycarbonate, ionomer, polyamide, etc. 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 applied 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 of a structure with two current collectors. In reality, however, it is a structure with multiple electrodes. It consists of layers.

[0197] In FIG. 12B, as an example, the number of electrode layers is 16. In FIG. 12(B), the negative electrode current collector 504 is made up of eight layers. 12B shows a structure of 16 layers in total, with the positive electrode current collector 501 being 8 layers. 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 has excellent flexibility.

[0198] An example of the external appearance of a laminated secondary battery 500 is shown in FIGS. 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 connected to each other.

[0199] FIG. 15(A) shows an external view of a positive electrode 503 and a negative electrode 506. The positive electrode 503 is connected to a 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 a 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, that is, a tab. The area and shape of the tab regions of the positive electrode and the negative electrode are as shown in the example of FIG. Not limited.

[0200] [Method of manufacturing laminated secondary battery] Here, an example of a method for producing a laminated secondary battery, the external view of which is shown in FIG. This will be explained using 5(B) and (C).

[0201] First, the negative electrode 506, the separator 507, and the positive electrode 503 are laminated. The negative electrode 506, the separator 507, and the 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 substrate region. For example, ultrasonic welding or the like is used for the bonding. Similarly, the tab regions of the negative electrodes 506 are joined to each other, and the negative electrode is attached to the tab region of the outermost negative electrode. The lead electrode 511 is joined.

[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. In order to fill the electrolyte 508 later, a part (or one side) of the exterior body 509 is In this case, a region that is not joined to the substrate (hereinafter referred to as an inlet) 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 electrolyte 508 can be introduced under a reduced pressure or inert gas atmosphere. Finally, the inlet is joined. In this manner, a laminated secondary battery is obtained. It is possible to manufacture 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 having excellent cycle characteristics even in a small 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] FIG. 16(A) shows a schematic top view of a bendable battery 250. , (B2), and (C) are cut along the lines C1-C2 and C3-C4 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. A lead 212a electrically connected to the negative electrode 211b and a lead 212 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 lead in addition to the positive electrode 211a and the negative electrode 211b. 2 is a perspective view showing the lead 212a and the lead 212b.

[0209] As shown in FIG. 17A, 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 the material layer is not 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 regulator 214 is shown in dotted line.

[0212] As shown in FIG. 17B, 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 to each other 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 arranged 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 includes the positive electrode 211a and the sealing portion 263. The seal portion 2 is provided on both sides 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 272 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 corrugated shape in which the sealing portions 272 are arranged alternately. 62 and seal portion 263 are preferably flat.

[0216] FIG. 16(B1) is a cross section cut at the portion 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 pond 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, In this manner, the positive electrode 211a and the negative electrode 211b are deformed so as to be shifted 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 are strongly connected to each other. In particular, if the metal film of the exterior body 251 is exposed, If the metal film is removed, it may be corroded by the electrolyte. It is preferable to set the distance La as long as possible. On the other hand, setting the distance La too large This increases the volume of the battery 250.

[0218] In addition, the greater the total thickness of the laminated 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 laminated positive electrode 211a and negative electrode 211b is defined as thickness t. When the thickness t is 0.8 to 3.0 times, the distance La is preferably 0.9 to 2.0 times 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 range, a compact battery with high reliability against bending can be realized. do.

[0220] In addition, 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 it is 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 t of the electrode 211a and the negative electrode 211b is 1.6 times or more and 6.0 times or less, preferably 1.8 times or less. 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 Most of the time, the ratio is between 1.0 and 2.0.

[0225] FIG. 16C is a cross section including the lead 212a, showing the battery 250, the positive electrode 211a, and As shown in FIG. 16(C), the bent portion corresponds to a 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 exterior body 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 it is bent. , which corresponds to the cross section taken along 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 outer casing 25 is deformed so that the amplitude of the wave becomes smaller and the period of the wave becomes larger. The part inside 1 deforms so that the wave amplitude is large and the wave period is small. In this way, the exterior body 251 is deformed, and the load on the exterior body 251 increases with bending. Since the stress caused by the expansion and contraction is relieved, 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 2 At this time, the plurality of stacked positive electrodes 211a and negative electrodes 211b are shifted relative to each other. Since the end of the pole 211b on the side of the seal portion 263 is fixed by the fixing member 217, the pole 211b is bent. The amount of deviation increases toward the recess 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. As a result, when the battery is bent, the positive electrode 211a and the negative electrode 211b located on the inside are bent in the exterior body 2. 51 can be displaced relative to each other without contacting them.

[0230] The battery 250 illustrated in FIG. 16 and FIG. 17 can be repeatedly bent and stretched without losing its exterior. 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 produce a battery with higher capacity and better cycle characteristics. can.

[0231] (Embodiment 4) In this embodiment, an example in which a secondary battery according to one embodiment of the present invention is mounted on an electronic device will be described. Reveal.

[0232] First, as described 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). For example, a television device (also called a television or television receiver), monitors for computers, digital cameras, digital video cameras, digital photo frames, etc. mobile phones (also called mobile phones or mobile phone devices), portable game machines, and portable information terminals , audio playback devices, and large game machines such as pachinko machines.

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

[0234] FIG. 18A shows an example of a mobile phone. A mobile phone 7400 includes a housing 740. In addition to the display unit 7402 incorporated in the 1, the operation buttons 7403, the 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 according to one embodiment of the present invention. This makes it possible to provide a lightweight mobile phone with a long life.

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

[0236] FIG. 18D shows an example of a bangle-type display device. The portable display device 7100 is 7101, a display unit 7102, an operation button 7103, and a secondary battery 7104. FIG. 18(E) shows the bent state of the secondary battery 7104. When the device is bent and worn on the user's arm, the case may deform and cause damage to part of the secondary battery 7104 or The total curvature changes. The degree of curvature at any point on the curve is expressed as the radius of the corresponding circle. The value expressed 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 case or secondary battery 7104 within the range of 40 mm to 150 mm in diameter Or the entire surface of the secondary battery 7104 changes. 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 portable display device with a long life can be provided.

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

[0238] The portable information terminal 7200 is capable of carrying out mobile phone calls, e-mails, viewing and creating documents, playing music, and internet connections. It can run various applications such as internet communication and computer games. Cut.

[0239] The display unit 7202 has a curved display surface, and displays information along the curved display surface. The display unit 7202 is equipped with a touch sensor, and the screen can be operated by touching it with a finger or a stylus. For example, the icon 7 displayed on the display unit 7202 can be operated by touching the By touching 207, the application can be launched.

[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 supports various functions such as auto-start, silent mode and power saving mode. For example, an operating system built into the portable information terminal 7200 can be Depending on the system, the functions of the operation buttons 7205 can be freely set.

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

[0242] The portable information terminal 7200 also includes an input / output terminal 7206 and is 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. 18E is curved and inserted into the housing 7201. The flexible support 7204 may be incorporated in a flexible state or inside the band 7203 in a bendable state.

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

[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 of 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.

[0246] The display surface of the display unit 7304 is curved, and the display is performed along the curved display surface. In addition, the display device 7300 can display the image by short-distance wireless communication according to a communication standard. You can change the situation.

[0247] The display device 7300 also has an input / output terminal, and can directly connect to other information terminals via a connector. It is possible to exchange data. It is also possible to charge the device via the input / output terminal. The charging operation may be performed by wireless power supply without going through 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, It is possible to provide a light-weight display device with a long life.

[0249] In addition, an example in which the secondary battery with excellent cycle characteristics shown in the above embodiment is mounted on an electronic device will be described. This will be explained with reference to 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, the battery can be lightweight and have a long life. We can provide products that are useful for daily use. For example, electric toothbrushes, electric shavers, Examples of such products include electric beauty devices. The secondary batteries used in these products are 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 that includes a heating element and an 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 for increased safety. A protection circuit for preventing overcharging and overdischarging 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 the weight is small. 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 FIG. 19(A) and FIG. 19(B) includes a housing 963. 0a, a housing 9630b, a movable part 9640 connecting the housings 9630a and 9630b, A display unit 9631, a display mode changeover switch 9626, a power switch 9627, a power saving mode The mode changeover switch 9625, the fastener 9629, and the operation switch 9628 are provided. By using a flexible panel for the display unit 9631, a tab with a wider display area can be made. FIG. 19(A) shows a tablet terminal 9600 in an open state. 19(A) shows a tablet terminal 9600 in a closed state, and FIG. 19(B) shows a 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 the movable portion 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 enter data by touching the screen. You can also switch the keyboard display on the touch panel. By touching the area where the switch button is displayed with your finger or a stylus, the display On the keyboard buttons can be displayed.

[0255] A display mode changeover switch 9626 is used to change the display orientation, such as vertical or horizontal. You can choose between black and white and color display. The switch 9625 detects the usage of the light detected by the 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. The tablet terminal includes a housing 9630 and a solar cell 9 633, a charge / discharge control circuit 9634 including a DCDC converter 9636. The battery 9635 is a secondary battery according to one embodiment of the present invention.

[0257] In addition, since the tablet terminal 9600 can be folded in two, when not in use, The housing 9630b can be folded so that the housing 9630b and the housing 9630b overlap each other. Since the display portion 9631 can be protected, durability of the tablet terminal 9600 can be improved. In addition, the power storage unit 9635 using the secondary battery of one embodiment of the present invention has a high capacity and a good cycle. The tablet terminal 9600 has a long lifespan due to its excellent durability. can be provided.

[0258] In addition, the tablet terminals shown in Fig. 19(A) and Fig. 19(B) are used in various Functions that display useful information (still images, videos, text images, etc.), calendars, dates, or times A 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, and the ability to control processing using various software (programs) , etc.

[0259] The solar cell 9633 attached to the surface of the tablet device supplies power to the touch panel. The solar cell 9633 can supply the solar cell 9633 with the following components: The battery 9635 can be efficiently charged by providing the battery 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. A block diagram is shown in FIG. 19C. A solar cell 9633 and 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 storage battery 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 This corresponds to 634.

[0261] First, an example of operation in which power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell is converted to a voltage to charge the storage battery 9635. The converter 9636 increases or decreases the voltage. When power from the battery 9633 is used, the switch SW1 is turned on, and the converter 963 7, the voltage is increased or decreased to a 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 limited thereto. Storage by other power generation means such as piezoelectric elements and thermoelectric conversion elements For example, the power may be transmitted and received wirelessly (contactlessly). The configuration is a non-contact power transmission module that charges the battery by connecting the battery to the battery, or by combining it with other charging means. You may do so.

[0263] FIG. 20 shows another example of electronic equipment. In FIG. 20, a display device 8000 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, 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 according to one aspect of the present invention can be used. The display device 8000 can be used by using the secondary battery 8004 as an uninterruptible power source. 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 3D Emission Display can be used.

[0265] In addition, display devices are used for TV broadcast reception, personal computers, advertising displays, etc. 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. 8101 is an example of an electronic device using the lighting device 8100. The device includes a light source 8102, a secondary battery 8103, and the like. In FIG. For example, the light source 101 and the 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 supply of power from the commercial power source is not possible. 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 source. This enables the lighting device 8100 to be used.

[0267] In addition, FIG. 20 illustrates a lighting device 8100 that is installed on a ceiling 8104. However, in the secondary battery according to one embodiment of the present invention, other than the ceiling 8104, for example, the side wall 8105, the floor The present invention can be applied to a lighting device installed in a fixed position such as a desk 8106 or a window 8107. It can also be used in upper lighting devices.

[0268] In addition, 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 diodes and organic electroluminescence (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 according to 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. The secondary battery 8203 may be provided in both the outdoor units 8204. The battery can be supplied with power from a commercial power source or can be charged by the power stored in the 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 according to one embodiment of the present invention as an uninterruptible power supply, The use of conditioners will be possible.

[0270] In addition, Figure 20 shows a separate type air conditioner consisting of an indoor unit and an outdoor unit. However, an integrated air conditioner that has both the indoor and outdoor functions in a single housing is also shown. 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, The refrigerator door 8302, the freezer door 8303, the secondary battery 8304, and the like are included. A secondary battery 8304 is provided inside the housing 8301. The power can be supplied from a commercial power source, or the power stored in the secondary battery 8304 can be used. Therefore, when power cannot be supplied from commercial power sources due to a power outage, etc. Even in such a case, the secondary battery 8304 according to one embodiment of the present invention can be used as an uninterruptible power supply. It will be possible to use 8300 refrigerators / freezers.

[0272] In addition, during periods 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 the power usage rate 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 turned on, the secondary battery 8304 is used as an auxiliary power source, so that the daytime power consumption is reduced. 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 on 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 which is one embodiment of the present invention will be described in this embodiment. By incorporating the above-mentioned in electronic devices, the electronic devices can be made lighter and have a longer life span. 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 appropriately selected and used as the power source for driving. The present invention relates to a hybrid vehicle that can use a 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 A light emitting device such as a room light (not shown) can be powered.

[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 device of the automobile 8400. The present invention can provide power to semiconductor devices such as gating systems.

[0278] The automobile 8500 shown in FIG. 21B has a secondary battery 8024. The vehicle is charged by receiving power from an external charging facility using a plug-in method or a wireless power supply method. FIG. 21(B) shows a charging device 8021 mounted on a ground and a charging station 8500 mounted on a vehicle. 8, a secondary battery 8024 mounted thereon 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. For example, plug-in technology can be used to Charging a secondary battery 8024 mounted on the automobile 8500 using external power supply Charging is done by converting AC power to DC power through 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 receives power from a ground power transmitting device in a non-contact manner. 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. In addition, the vehicle exterior may be provided with a power supply. 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 resonance method can be used.

[0280] FIG. 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, a side mirror 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 space under the seat 8604. The secondary battery 8602 can be stored in the under-seat storage 8604. can also be stored in the under-seat storage space 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 vehicle itself can be made smaller and lighter, it will contribute to reducing the vehicle's weight, improving the vehicle's 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 is possible to do so.

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

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

[0285] <Preparation of Positive Electrode Active Material Particles> Sample 1 to Sample 1 with different concentrations of lithium and cobalt sources The positive electrode active material particles were produced using lithium carbonate (Li 2 CO 3 ), Tricobalt tetroxide (Co 3 O 4 ), magnesium oxide (MgO) and lithium fluoride ( LiF) was used.

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

[0287] [Table 1]

[0288] From Table 1, the number of cobalt atoms 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 In the case of Sample 1, it is 1.040 times, in the case of Sample 7, it is 1.051 times, and in the case of Sample 8, it is 1.06 times, in the case of Sample 9, it is 1.081 times, and in the case of Sample 10, it is 1.131 times . Also, from Table 1, with respect to the number of cobalt atoms contained in cobalt tetroxide, the number of magnesium atoms contained in magnesium oxide is 0.010 times. Also, from Table 1, with respect to the number of cobalt atoms contained in cobalt tetroxide, the number of fluorine atoms contained in lithium fluoride is 0.020 times .

[0289] Regarding the above 10 samples, in the same manner as the production method described in Embodiment 1, starting materials were mixed, first heating was performed, after cooling, crushing treatment was performed, second heating was performed, and then cooling was carried out to obtain positive electrode 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 carried out 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 / C o increases, it can be seen that the particles become larger. In Sample 4, they are 5 μm ​In Sample 8, most particles were around 20 μm in diameter. Many particles were observed, and in Sample 10, particles with a diameter exceeding 50 μm were observed.

[0291] <Particle size distribution> Next, of the samples obtained, Sample 1 to Sample 4 were The particle size distribution was measured for Sample 6 to Sample 10. The measurements were performed using a laser diffraction particle size distribution analyzer (SALD-2200, manufactured by Shimadzu Corporation). ) was used. Samples 1 to 4 and Sample 6 The measurement results up to Sample 10 are shown in Figure 25. Figure 25(A) shows the results from Sample 1 to Sample 10. Figure 25(B) shows the results for Samples 4 and 6, and Figure 25(B) shows the results for Samples 7 to 6. The results for up to le 10 are shown. In Fig. 25, the vertical axis represents relative intensity and the horizontal axis represents particle size. be.

[0292] In addition, in Figure 26, the horizontal axis shows the lithium content of lithium carbonate and lithium fluoride. The sum of the number of atoms of cobalt in tricobalt tetroxide divided by the number of cobalt atoms in tricobalt tetroxide ((Li / C The vertical axis shows the peak value of the relative intensity, and here the particle size at which the relative intensity reaches its maximum value. Shows.

[0293] As (Li / Co)_R increased, the peak value of the grain size tended to increase. In addition, the peak value tends to increase sharply when the (Li / Co)_R value is around 1.05. It was. EXAMPLES

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

[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. FIG. 27 shows the ratio of lithium to cobalt (Li / Co), FIG. 28 shows the ratio of magnesium to cobalt (Mg / Co), and FIG. 29 shows the ratio of fluorine to cobalt (F / C o). In FIGS. 28 and 29, the analysis results before the second heating (white in the figure) and after the completion of production, that is, after the second heating (black in the figure) in the production process of the positive electrode active material particles are shown.

[0298] From FIG. 27, in each sample, the Li / Co obtained by XPS was greater than 0.5 and less than 0.85. Also, after Sample 8, the value of Li / Co tended to increase. From the results of FIG. 28 described later, it is possible that the second region 102 is thin or hardly formed after Sample 8. The ratio of the first region 101 occupying the region measured by XPS becomes high, and it is considered that the value of Li / Co approaches 1, which is the value of the ratio of lithium to cobalt in lithium cobalt oxide.

[0299] Also, from FIG. 28, Mg / Co tended to increase after the second heating. Therefore, it is suggested that the segregation of magnesium further progresses due to the second heating.

[0300] From Figure 28, for Sample 1, Sample 2, and Sample 3, Mg / Co obtained by XPS was greater than 0.25 and less than 0.3. Also, for Samp le 4, Sample 5, and Sample 6, Mg / C o obtained by XPS was greater than 0.3 and less than 0.4. Also, for Sample 8 and Sampl e 9, Mg / Co obtained by XPS was 0.1 or less. Also, for Sample 10, Mg was below the detection limit in XPS and was not detected. For samples starting from Sample 8 where the ratio of starting materials ([Li / Co)_R is 1.061, the concentration of magnesium is low and in the surface of the positive electrode active material particles, the second region 102 may be thin or hardly formed.

[0301] From Figure 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. For samples starting from Sample 8 where the ratio of starting materials (Li / Co)_R is 1.061, the concentration of fluorine tended 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> ​​​​FIB (Focused Ion Beam System: Focused Ion Beam Processing After each sample was cut into a thin section using a microscope (observation device), the HAADF-STEM images were observed. The JEM-ARM200F manufactured by JEOL was used for the observation. The observation results are shown in FIG. 30(B) and Sample 9 in FIG.

[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 is formed of a crystal structure or a crystal structure of the first region 101 located inside. On the other hand, in Figure 30(B), the surface of the particle has a layered region. has not been significantly observed.

[0305] In Sample 4, a layered region was formed on the surface, and the XPS results showed that this region contained mag. On the other hand, in Sample 9, the cesium is distributed at a relatively high concentration on the surface of the particles. The magnesium concentration was low and no significant layered regions were observed. EXAMPLES

[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. Polyvinylidene fluoride (PVDF) is used as the positive electrode active material particles: AB:PVDF=95:2.5:2.5 The slurry mixed in the ratio (by weight) 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 lithium hexafluorophosphate (LiPF 6 )of 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 8.5 mA / g (equivalent to approximately 0.3 C) and an upper limit voltage of 4.6 V. Then, the current density The battery was charged at a constant voltage until the current reached 1.37mA / g (equivalent to approximately 0.005C). 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 performed at 1000 V. Each battery was subjected to 30 charge / discharge cycles.

[0312] FIG. 31(A) shows the results of the measurement using the positive electrode active material particles from 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. An enlarged view is shown in FIG.

[0313] Compared to Sample 1, Sample 2 and Sample 3, Sample The capacity retention rate was improved in Sample 4, and further improved in Sample 5 and Sample 6. The capacity retention rate improved as the ratio of the starting materials (Li / Co)_R increased. The efficiency was improved, and excellent characteristics were obtained when (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 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 making it greater than 1.02, the capacity retention rate could be further increased. [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 plate 610 Gasket 611 PTC element 612 Safety valve mechanism 900 Circuit Board 910 Label 911 Terminal 912 Circuit 913 Secondary battery 914 Antenna 915 Antenna 916 layers 917 layers 918 Antenna 919 Terminal 920 Display device 921 Sensor 922 Terminal 930 Case 930a Case 930b Case 931 negative electrode 932 Positive electrode 933 Separator 950 Wound body 951 Terminal 952 Terminal 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 Case 7102 Display section 7103 Operation button 7104 Secondary battery 7200 Portable Information Terminal 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 Case 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Mike 7407 Secondary battery 7409 Current collector 7500 Electronic 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 Case 8102 Light source 8103 Secondary battery 8104 Ceiling 8105 Side wall 8106 Bed 8107 Window 8200 indoor unit 8201 Case 8202 Ventilator 8203 Secondary battery 8204 Outdoor unit 8300 Electric refrigerator-freezer 8301 Case 8302 Refrigerator door 8303 Freezer door 8304 Secondary battery 8400 Automobiles 8401 Headlight 8406 Electric Motor 8500 Automobiles 8600 Scooter 8601 Side mirror 8602 Secondary battery 8603 Turn signal light 8604 Under-seat storage 9600 Tablet PC 9625 Switch 9626 Switch 9627 Power Switch 9628 Operation Switch 9629 Fastener 9630 Case 9630a Case 9630b Case 9631 Display section 9633 Solar Cells 9634 Charge / discharge control circuit 9635 Electric 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 in contact with the outside of the first region, the first region comprises lithium, an element M, and oxygen; The element M is one or more elements selected from cobalt, manganese, and nickel; the second region has the element M, oxygen, magnesium, and fluorine, an atomic ratio (Li / M) of the lithium to the element M measured by X-ray photoelectron spectroscopy is 0.5 or more and 0.85 or less; The positive electrode active material particles have an atomic ratio (Mg / M) of the magnesium to the element M of 0.2 or more and 0.5 or less, as measured by X-ray photoelectron spectroscopy.

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 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 a space group R-3m; The crystal structure of the second region is represented by the space group Fm-3m.

5. In any one of claims 1 to 4, The positive electrode active material particles have an atomic ratio (F / M) of the fluorine to the element M of 0.02 or more and 0.15 or less, as measured by X-ray photoelectron spectroscopy.

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