Method for producing positive electrode active material

Abstract

To provide a positive electrode active material for a lithium ion secondary battery having excellent cycle characteristics and high capacity.SOLUTION: A coating layer containing aluminum and a coating layer containing magnesium are provided on a surface layer portion of a positive electrode active material. The coating layer containing magnesium is present in a region closer to the surface of the particle than the coating layer containing aluminum. The coating layer containing aluminum can be formed by a sol-gel method using aluminum alkoxide. The coating layer containing magnesium can be formed by mixing magnesium and fluorine in a starting material and heating the mixture after a sol-gel method to segregate magnesium.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, Pertaining to a 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. In particular, the present invention relates to an electronic device and its operating system.

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

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

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

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

[0006] Therefore, we aimed to improve the cycle characteristics and capacity of lithium-ion secondary batteries by developing a positive electrode Improvements in active materials have been investigated (Patent Documents 1, 2 and 3). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 8-236114 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-124262 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-358953 Summary of the Invention [Problem to be solved by the invention]

[0008] However, lithium ion secondary batteries and the positive electrode active materials used therein have There are still many aspects to be improved, such as characteristics, capacity, charge / discharge characteristics, reliability, safety, and cost. There is still room for improvement.

[0009] One embodiment of the present invention is to improve the efficiency of charge / discharge cycles by using the present invention in a lithium ion secondary battery. Another object of the present invention is to provide a positive electrode active material in which the decrease in the amount of the positive electrode active material is suppressed. Another object of the present invention is to provide a high-capacity secondary battery. Another object of the present invention is to provide a secondary battery having excellent charge-discharge characteristics. One of the objects of the present invention is to provide a secondary battery with high safety and reliability.

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

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

[0012] In order to achieve the above object, one aspect of the present invention is to provide a cathode active material having a surface layer containing aluminum. The present invention is characterized in that a coating layer containing tantalum and a coating layer containing magnesium are provided.

[0013] One aspect of the present invention is a positive electrode active material, the positive electrode active material including a first region, a second region, and and a third region, the first region being present inside the positive electrode active material, and the second region being present inside the first a third region covering at least a portion of the second region; and a third region covering at least a portion of the second region. The first region has lithium, a transition metal, and oxygen, and the second region has lithium and aluminum. the third region comprises magnesium, a transition metal, and oxygen; It is a positive electrode active material having the above structure.

[0014] In the above, the third region may contain fluorine.

[0015] In the above, the third region may contain a transition metal.

[0016] In the above, the first region and the second region have a layered rock salt type crystal structure, and the third region has a layered rock salt type crystal structure. The region may have a rock salt type crystal structure.

[0017] In the above, the transition metal may be cobalt.

[0018] Another embodiment of the present invention is a positive electrode active material. The positive electrode active material includes lithium and aluminum. a surface layer of the positive electrode active material, the surface layer of the positive electrode active material containing fluorine, a transition metal, magnesium, oxygen, and fluorine; Lithium, aluminum, transition metals, magnesium present and measured by X-ray photoelectron spectroscopy The total amount of oxygen and fluorine is 100 atomic %, and it exists in the surface layer of the positive electrode active material, and X-ray The aluminum concentration measured by photoelectron spectroscopy is 0.1 atomic % or more and 10 atomic % or less, The magnesium concentration is 5 atomic % or more and 20 atomic % or less, and the fluorine concentration is 3.5 atomic % or more. The positive electrode active material has a Cr content of 14 atomic % or less.

[0019] Another embodiment of the present invention is a battery including a positive electrode having the above-described positive electrode active material, a negative electrode, an electrolyte solution, and an outer casing. and a secondary battery having the above.

[0020] Further, one aspect of the present invention is a method for producing a sol-gel composite material comprising the steps of dissolving aluminum alkoxide in alcohol; Aluminum alkoxide is dissolved in alcohol. Particles having lithium, a transition metal, magnesium, oxygen, and fluorine in a solution and mixing an alcohol solution of aluminum alkoxide, lithium, and a transition metal. A mixture of particles containing metal, magnesium, oxygen, and fluorine is added to water. A step of stirring in an atmosphere containing steam, a step of recovering a precipitate from the mixed liquid, and a step of recovering the recovered precipitate. The precipitate is heated in an oxygen-containing atmosphere at 500°C to 1200°C for 50 hours or more. and heating the cathode active material under a low temperature. [Effects of the Invention]

[0021] According to one embodiment of the present invention, by using the compound in a lithium ion secondary battery, It is possible to provide a positive electrode active material in which the capacity decrease due to the addition of the positive electrode active material is suppressed. Furthermore, a secondary battery having excellent charge / discharge characteristics can be provided. Furthermore, a secondary battery having high safety and reliability can be provided. A substance, a power storage device, or a manufacturing method thereof can be provided. [Brief explanation of the drawings]

[0022] [Figure 1] 1A to 1C illustrate an example of a positive electrode active material. [Figure 2] 1A to 1C illustrate an example of a method for manufacturing a positive electrode active material. [Figure 3] FIG. 10 is a cross-sectional view of an active material layer in the case where a graphene compound is used as a conductive additive. [Figure 4] FIG. 2 is a diagram illustrating a coin-type secondary battery. [Figure 5] FIG. 2 is a diagram illustrating a cylindrical secondary battery. [Figure 6] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 7] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 8] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 9] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 10] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 11] FIG. 1 is a diagram illustrating a laminated secondary battery. [Figure 12] FIG. 1 is a diagram illustrating a laminated secondary battery. [Figure 13]FIG. 2 is a diagram showing the appearance of a secondary battery. [Figure 14] FIG. 2 is a diagram showing the appearance of a secondary battery. [Figure 15] 1A to 1C are diagrams illustrating a method for manufacturing a secondary battery. [Figure 16] 1A and 1B are diagrams illustrating a bendable secondary battery. [Figure 17] 1A and 1B are diagrams illustrating a bendable secondary battery. [Figure 18] 1A to 1C illustrate examples of electronic devices. [Figure 19] 1A to 1C illustrate examples of electronic devices. [Figure 20] 1A to 1C illustrate examples of electronic devices. [Figure 21] 1A to 1C illustrate examples of electronic devices. [Figure 22] 2 is a graph showing the cycle characteristics of a secondary battery using the positive electrode active material of Example 1. [Figure 23] 1 is a STEM image of the positive electrode active material of Example 2. [Figure 24] 1 is a STEM-FFT image of the positive electrode active material of Example 2. [Figure 25] 1 shows a STEM image and EDX elemental mapping of the positive electrode active material of Example 2. [Figure 26] 1 shows a STEM image and EDX analysis of the positive electrode active material of Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and various modifications in form and details are possible by those skilled in the art. Furthermore, the present invention should not be construed as being limited to the description of the following embodiments. It is not something that can be done.

[0024] In this specification, crystal planes and directions are indicated by Miller indices. In the above, numbers are marked with a superscript bar in crystallography, but the crystal planes and directions in this specification are Due to limitations in the application notation, instead of placing a bar above the numbers, a minus sign (-) is placed before the numbers. Also, individual directions that indicate directions within a crystal are expressed in [ ], and all equivalent directions are expressed in [ ]. The aggregate orientation is indicated by < >, the individual crystal plane is indicated by ( ), and the aggregates with equivalent symmetry are indicated by ( ). Each joint is represented by {}.

[0025] 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.

[0026] In the present specification and the like, the layered rock salt type crystal structure of a composite oxide containing lithium and a transition metal is The structure has a rock salt type ion arrangement in which cations and anions are arranged alternately, and the transition metal and lithium The lithium atoms are regularly arranged to form a two-dimensional plane, allowing two-dimensional diffusion of lithium. It refers to a crystalline structure. It may have defects such as cation or anion deficiencies. Strictly speaking, the rock salt crystal structure is a distorted structure of the rock salt crystal. be.

[0027] In this specification and the like, the rock salt type crystal structure refers to a structure in which cations and anions are arranged alternately. It is possible for there to be a deficiency of cations or anions.

[0028] The anions of layered rock salt crystals and rock salt crystals form a cubic close-packed structure (face-centered cubic lattice structure). When layered rock salt crystals come into contact with each other, the cubic closest packing composed of anions However, the space group of the layered rock salt crystal is R-3m. The rock salt crystal space group Fm-3m (the general rock salt crystal space group) and Fd-3m ( Since the space group is different from that of rock salt crystals, which have the simplest symmetry, the results satisfying the above conditions The Miller indices of the crystal planes are different between layered rock salt crystals and rock salt crystals. In crystals and rock salt crystals, the cubic close-packed structure composed of anions is aligned When this occurs, the crystal orientation is said to be roughly the same.

[0029] The alignment of the crystal orientations in the two regions is confirmed by TEM (transmission electron microscope) and STEM (scanning electron microscope) images. High-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image, ) images, ABF-STEM (annular bright-field scanning transmission electron microscope) images, etc. X-ray diffraction, electron diffraction, neutron diffraction, etc. can also be used as materials for judgment. TEM image In layers such as these, the arrangement of cations and anions can be observed as repeated bright and dark lines. When the orientation of the cubic close-packed structure of salt-type crystals and rock salt-type crystals is aligned, bright and dark lines appear between the crystals. It can be observed that the angle formed by the repetition of the above is 5 degrees or less, and more preferably 2.5 degrees or less. However, in TEM images, light elements such as oxygen and fluorine may not be clearly observed. In this case, the alignment of the orientation can be determined by the arrangement of the metal elements.

[0030] (Embodiment 1) [Positive electrode active material structure] First, a positive electrode active material 100 according to one embodiment of the present invention will be described with reference to FIG. 1(B), the positive electrode active material 100 is composed of a first region 101 and a second region 102. The first region 101 is located inside the positive electrode active material 100. The second region 102 covers at least a portion of the first region 101. The region 103 covers at least a portion of the second region 102 .

[0031] Furthermore, as shown in FIG. 1(B), even if a third region 103 exists inside the positive electrode active material 100, For example, when the first region 101 is polycrystalline, the third region 103 exists near the grain boundary. In addition, the third region 1 may be present near the portion of the positive electrode active material 100 where the crystal defects are present. In FIG. 1, a part of the grain boundary is shown by a dotted line. Crystal defects are defects that can be observed in TEM images, i.e., structures in which other elements have entered the crystal. , cavities, etc.

[0032] Although not shown, a second region 102 may be present inside the positive electrode active material 100. For example, when the first region 101 is polycrystalline, the second region 102 exists near the grain boundary. In addition, the second region 102 may be present in the vicinity of the portion of the positive electrode active material 100 where the crystal defect is present. It may be possible.

[0033] Also, the second region 102 does not have to cover the entire first region 101. The third region 103 does not necessarily cover the entire second region 102. Adjacent to region 101, a third region 103 may be present.

[0034] In other words, the first region 101 exists inside the positive electrode active material 100, and the second region 10 The second and third regions 103 are present in the surface layer portion of the positive electrode active material 100. The region 102 and the third region 103 function as a coating layer for the positive electrode active material. The region 103 and the second region 102 may exist inside the particle of the positive electrode active material 100. good.

[0035] If the particle size of the positive electrode active material 100 is too large, it becomes difficult for lithium to diffuse. On the other hand, if the particle size is too small, the surface of the active material layer becomes too rough. This can cause problems such as difficulty in coating onto the surface and excessive reaction with the electrolyte. 50 (also called median diameter) is preferably 0.1 μm or more and 100 μm or less, and 1 μm or less It is more preferable that the thickness is at most 40 μm.

[0036] In order to increase the density of the positive electrode active material layer, large particles (approximately 20 μm or more, approximately 40 μm or more) are required. Mixing large particles (less than 1 μm) with small particles (about 1 μm) and filling the gaps between the large particles with the small particles. Therefore, the particle size distribution may have two or more peaks.

[0037] <First Area 101> The first region 101 contains lithium, a transition metal, and oxygen. It can be said that the composite oxide contains lithium and a transition metal.

[0038] The transition metal contained in the first region 101 is a layered rock salt type composite oxide together with lithium. It is preferable to use a metal that can form a sphere. For example, manganese, cobalt, nickel In other words, the transition metal contained in the first region 101 and the transition metal contained in the second region 102 can be used alone or in combination. Cobalt alone may be used, or both cobalt and manganese may be used. Alternatively, the first region 101 may be formed of a transition metal. Additionally, metals other than transition metals, such as aluminum, may be contained.

[0039] That is, the first region 101 is made of lithium cobalt oxide, lithium nickel oxide, and a part of cobalt. Lithium cobalt oxide with manganese substitution, lithium nickel-manganese-cobalt oxide , lithium-cobalt-lithium aluminum oxide, and other composite acids containing lithium and transition metals. The compound may have a structure similar to that of the compound of the present invention.

[0040] The first region 101 is a region of the positive electrode active material 100 that particularly contributes to the charge / discharge reaction. In order to increase the capacity when the positive electrode active material 100 is used in a secondary battery, the first region 101 , preferably has a larger volume than the second region 102 and the third region 103 .

[0041] The first region 101 may be either single crystal or polycrystalline. The powder 1 may be polycrystalline with an average crystallite size of 280 nm or more and 630 nm or less. In the case of crystals, the grain boundaries can sometimes be observed using a TEM. The average grain size is It can be calculated from the half-width of XRD.

[0042] Since polycrystals have a clear crystal structure, there are sufficient paths for two-dimensional diffusion of lithium ions. In addition, it is easier to produce than a single crystal, so it is preferable for the first region 101. stomach.

[0043] The layered rock salt type crystal structure allows lithium to easily diffuse two-dimensionally, and therefore is used as the first region 101. Furthermore, when the first region 101 has a layered rock salt type crystal structure, the subsequent However, if the first region 101 is entirely made of layered rock salt, the segregation of magnesium described above is likely to occur. For example, the first region 101 may have a crystal defect in part. Alternatively, a part of the first region 101 may be amorphous, or the first region 101 may be amorphous. It may have a crystalline structure.

[0044] <Second Area 102> The second region 102 comprises lithium, aluminum, a transition metal, and oxygen. In a composite oxide containing aluminum and a transition metal, some of the transition metal sites are replaced by aluminum. The transition metal contained in the second region 102 is different from the transition metal contained in the first region 101. In this specification, the term "site" refers to a site that is the same element as the transition metal that binds the bond. This refers to the position that a certain element should occupy in a crystal.

[0045] The second region 102 may also contain fluorine.

[0046] The second region 102 contains aluminum, which improves the cycle characteristics of the positive electrode active material 100. The aluminum contained in the second region 102 has a concentration gradient. Aluminum may also be a part of a composite oxide containing lithium and a transition metal. It is preferable that it exists at the transition metal site, but it may exist in other states. For example, it may exist as aluminum oxide (Al2O3).

[0047] Generally, the positive electrode active material loses transition metals such as cobalt and manganese as it is repeatedly charged and discharged. Side reactions such as dissolution into the electrolyte, oxygen release, and instability of the crystal structure occur. However, the positive electrode active material 100 according to one embodiment of the present invention has an aluminum surface layer. The second region 102 has lithium, and therefore the first region 101 has lithium. It is possible to make the crystal structure of the composite oxide containing the transition metal more stable. The cycle characteristics of a secondary battery containing the material 100 can be improved.

[0048] The second region 102 preferably has a layered rock salt type crystal structure. has a layered rock salt type crystal structure, and is bonded to the first region 101 and the third region 103. The first region 101, the second region 102, and the third region 103 are easily aligned. When the crystal orientations of the second and third regions 102 and 103 are roughly aligned, the second and third regions 102 and 103 are more stable. It can function as a fixed coating layer.

[0049] If the second region 102 is too thin, its function as a covering layer is reduced, but if it is too thick, it is not easy to Therefore, the second region 102 is formed by separating the surface of the positive electrode active material 100 from the surface of the positive electrode active material 100. It is preferable that the thickness of the pores is within 30 nm, more preferably 15 nm, in the depth direction from the surface of the pores.

[0050] <Third Area 103> The third region 103 contains magnesium and oxygen. It can be said that it contains nesium.

[0051] The third region 103 contains the same transition metal as the first region 101 and the second region 102. Furthermore, the third region 103 may contain fluorine. When 103 has fluorine, some of the oxygen in magnesium oxide is replaced by fluorine. Good too.

[0052] The magnesium oxide contained in the third region 103 is an electrochemically stable material, and therefore, charging and discharging The positive electrode active material 100 is suitable as a coating layer because it is resistant to deterioration even after repeated charging. By having the third region 103 in addition to the second region 102 in the surface layer portion, It is possible to make the crystal structure of the composite oxide containing lithium and transition metals more stable. Therefore, the cycle characteristics of a secondary battery having the positive electrode active material 100 can be improved. Also, 4.3V (vs. Li / Li + ), especially voltages exceeding 4.5V (v s. Li / Li + When charging and discharging are performed at a high voltage of 100 V or more, the structure of one embodiment of the present invention is particularly It has a significant effect.

[0053] If the third region 103 has a rock salt type crystal structure, the crystal orientation will be the same as that of the second region 102. This is preferable because it is easy to adhere to the surface and functions as a stable coating layer. The third region 103 does not necessarily have to have a rock salt type crystal structure. The third region 103 may have any other crystal structure.

[0054] If the third region 103 is too thin, its function as a covering layer is reduced, but if it is too thick, it is not easy to Therefore, the third region 103 is formed in the positive electrode active material 100 from the surface thereof in the depth direction. It is preferable that the thickness is 0.5 nm or more and 50 nm or less, and it is preferable that the thickness is 0.5 nm or more and 5 nm or less. It is more preferable that the

[0055] It is important that the third region 103 contains an electrochemically stable material. The element to be used does not necessarily have to be magnesium. For example, instead of magnesium, Alternatively, magnesium may contain other typical elements such as calcium and beryllium. Furthermore, instead of or together with fluorine, chlorine may be contained.

[0056] <Boundaries between each area> The first region 101, the second region 102, and the third region 103 are regions having different compositions. However, the elements in each region may have a concentration gradient. For example, The aluminum in the second region 102 may have a concentration gradient. As will be described later, 103 is preferably a region where magnesium is segregated. There may be a gradient of nesium concentration, so the boundaries between the regions are not clear. There are cases where this happens.

[0057] The first region 101, the second region 102, and the third region 103 are used for TEM images, STEM images, and , FFT (Fast Fourier Transform) analysis, EDX (Energy Dispersive X-ray Analysis), ToF-S Depth analysis by IMS (time-of-flight secondary ion mass spectrometry), XPS (X-ray photoelectron Spectroscopy), Auger electron spectroscopy, TDS (thermal desorption spectroscopy), etc. It can be confirmed that the EDX measurement is performed while scanning the area. Two-dimensional evaluation is sometimes called EDX area analysis. The data in this region was extracted and the distribution of atomic concentrations within the positive electrode active material particles was evaluated. This is sometimes called analysis.

[0058] For example, in TEM and STEM images, differences in constituent elements appear as differences in image brightness. Therefore, the constituent elements of the first region 101, the second region 102, and the third region 103 In addition, area analysis by EDX (e.g., elemental mapping) also reveals that the first It is observed that the first region 101, the second region 102 and the third region 103 have different elements. I can understand.

[0059] In addition, EDX line analysis and depth direction analysis using ToF-SIMS revealed that the first region 101, the second region 102, and the third region 103 detect the peaks of the concentrations of the elements. It is possible.

[0060] However, it is not necessarily the case that the first region 101, the second region 102, and the third region are identified by various analyses. It is not necessary that a clear boundary of the region 103 is observable.

[0061] In this specification and the like, the range of the third region 103 present in the surface layer portion of the positive electrode active material 100 is This refers to the time from the surface of the positive electrode active material 100 until the magnesium concentration reaches 1 / 5 of its peak. The analytical methods used were the above-mentioned EDX line analysis and ToF-SIMS. Depth analysis and the like can be applied.

[0062] The peak of magnesium concentration is at a depth of 3 mm from the surface of the positive electrode active material 100 toward the center. Preferably, the ions are present in the range of 1 nm to a depth of 200 nm, more preferably in the range of 1 nm to a depth of 200 nm, and It is more preferable that the thickness is up to 0.5 nm.

[0063] The depth at which the magnesium concentration reaches 1 / 5 of its peak varies depending on the manufacturing method, but will be described later. In the case of the manufacturing method, the depth is generally about 2 nm to 5 nm from the surface of the positive electrode active material.

[0064] The third region 103 present inside the first region 101 was also detected by depth direction analysis. This refers to the region where the concentration of the typical element is 1 / 5 or more of the peak.

[0065] The distribution of fluorine in the positive electrode active material 100 preferably overlaps with the distribution of magnesium. Therefore, fluorine also has a concentration gradient, and the peak of the fluorine concentration is It is preferable that the particles exist within a depth of 3 nm from the surface toward the center, and preferably within a depth of 1 nm. It is more preferable that the pores are present at a depth of up to 0.5 nm, and it is even more preferable that the pores are present at a depth of up to 0.5 nm.

[0066] In this specification, the second region 102 present in the surface layer portion of the positive electrode active material 100 is This refers to the area where the aluminum concentration detected by depth analysis is more than half of the peak. The second region 101 exists inside the first region 101, such as near the grain boundary or near the crystal defect. For 02, the aluminum concentration detected by depth direction analysis is more than half of the peak. The analytical methods used are the EDX line analysis and ToF -SIMS-based depth analysis can be applied.

[0067] Therefore, the third region 103 and the second region 102 may overlap. The region 103 is located closer to the surface of the particle of the positive electrode active material than the second region 102. In addition, the peak of the magnesium concentration is preferably more positive than the peak of the aluminum concentration. It is preferable that the metal oxide is present in a region close to the surface of the particles of the electrode active material.

[0068] The peak of the aluminum concentration is at a depth of 0.5n from the surface to the center of the positive electrode active material 100. Preferably, the nanoparticles are present at a depth of 1 nm to 5 nm. is more preferable.

[0069] The concentrations of aluminum, magnesium, and fluorine were measured by ToF-SIMS and EDX as described above. In addition to area and line analysis, analysis can be performed using XPS, Auger electron spectroscopy, TDS, etc. This can be done.

[0070] The measurement range of XPS is about 5 nm from the surface of the positive electrode active material 100. Therefore, the third region 10 If the thickness of the third region 103 is less than 5 nm from the surface, the third region 103 and a part of the second region 102 When the thickness of the third region 103 is 5 nm or more from the surface, the thickness of the third region 10 3. The element concentration can be quantitatively analyzed.

[0071] Lithium, aluminum, and the first region measured by XPS from the surface of the positive electrode active material 100 The total amount of transition metals, magnesium, oxygen, and fluorine contained in 101 is taken as 100 atomic %. When the aluminum concentration is 0.1 atomic % or more and 10 atomic % or less, It is more preferable that the magnesium concentration is 0.1 atomic % or more and 2 atomic % or less. The fluorine concentration is preferably 3.5 atomic % or more and 14 atomic % or less. It is preferable that the content is not more than 1 atomic %.

[0072] As described above, the first region 101, the second region 102, and the third region 103 have Since elements may have a concentration gradient, the first region 101 may be divided into the second region 102 and The third region 103 may have the same element as the first region 103. The first region 101 and the second region 102 may contain the same elements. 101, the second region 102 and the third region 103 are composed of carbon, sodium, calcium, It may also contain other elements such as chlorine and zirconium.

[0073] [Covering the second area] The second region 102 is made of particles of a composite oxide containing lithium and a transition metal, and aluminum. The insulating layer can be formed by coating a material having the above properties.

[0074] As a method for coating a material containing aluminum, liquid phase methods such as the sol-gel method, Solid phase method, sputtering method, evaporation method, CVD (chemical vapor deposition) method, PLD (pulsed laser In this embodiment, a uniform coating is desired. The sol-gel method will be applied, which allows processing at atmospheric pressure and allows for a long time.

[0075] When the sol-gel method is applied, aluminum alkoxide is first dissolved in alcohol, and the solution is Particles of a composite oxide containing lithium and a transition metal are mixed into the liquid and stirred in an atmosphere containing water vapor. By placing it in an atmosphere containing H2O, composite oxide particles containing lithium and transition metals are formed. On the particle surface, hydrolysis and polycondensation reactions between water and aluminum alkoxide occur, and the particles A gel-like layer containing aluminum is formed on the surface of the particles, which are then collected and dried. The manufacturing method will be described in detail later.

[0076] In this embodiment, particles of a composite oxide containing lithium and a transition metal are coated on a positive electrode current collector. Before proceeding, an example of coating an aluminum-containing material was described. The method is not limited to this. After forming a positive electrode active material layer containing aluminum alkoxide, the positive electrode current collector and the positive electrode active material layer are It may also be soaked in a solution containing cid.

[0077] [Segregation in the third region] The third area 103 is a method using a liquid phase method such as a sputtering method, a solid phase method, or a sol-gel method. However, the present inventors have found that the magnesium source and the fluorine source can be used as the first After mixing with the material in region 101 of FIG. 1, heating is performed to cause magnesium to be mixed with the material in region 101 of FIG. 1. It was revealed that the third region 103 was formed by segregating the first region on the outermost surface. The presence of the third region 103 results in a positive electrode active material 100 with excellent cycle characteristics. It was revealed that

[0078] By heating as described above, magnesium is segregated on the outermost surface of the positive electrode active material particles, and the third When forming region 103, heating causes lithium, transition metals, magnesium, and fluorine to It is preferable to coat the composite oxide particles with a material containing aluminum. Surprisingly, even after coating with a material containing aluminum, magnesium remained in the positive electrode active material particles. This is because the segregation occurs on the outermost surface of the film. The details of the manufacturing method will be described later.

[0079] When magnesium is segregated, the complex containing lithium and a transition metal contained in the first region 101 is When the oxide is polycrystalline or has crystal defects, the lithium and Magnesium can also segregate near the grain boundaries and crystal defects of composite oxides containing transition metals. The magnesium segregated near the boundary and the crystal defect interacts with the lithium contained in the first region 101. This can contribute to further stabilizing the crystal structure of the composite oxide containing a transition metal.

[0080] The ratio of magnesium to fluorine in the raw material is Mg:F=1:x (1.5≦x≦4) (atomic ratio). In the range of Mg:F=1:, magnesium segregation occurs effectively. It is more preferable that the ratio is about 2 (atomic number ratio).

[0081] The third region 103 formed by segregation is formed by epitaxial growth. Therefore, the crystal orientations of the second region 102 and the third region 103 may partially coincide with each other. That is, the second region 102 and the third region 103 may be topotaxis. If the crystal orientations of the region 102 and the third region 103 are roughly the same, they will have better It can function as a covering layer.

[0082] In this specification and the like, the term "having three-dimensional structural similarity" or "being crystallographically identical" refers to a compound that has a similar three-dimensional structure. The same orientation is called topotaxis. In other words, the crystals in two regions (for example, the base region and the grown region) The orientations are roughly the same.

[0083] <Fourth Area 104> It should be noted that the positive electrode active material 100 has been divided into the first region 101, the second region 102, and the third region 103. Although an example having the 103 has been described, one embodiment of the present invention is not limited to this. As shown in (C), the positive electrode active material 100 may have a fourth region 104. The region 104 may be provided so as to be in contact with at least a part of the third region 103. The fourth region 104 is a film containing carbon such as a graphene compound. Alternatively, the coating may be a film containing decomposition products of lithium or the electrolyte. When the region 104 is a coating containing carbon, the positive electrode active material 100 and the positive electrode active material 100 The fourth region 104 can increase the electrical conductivity between the 00 and the current collector. In the case of a coating containing decomposition products of the electrolyte, excessive reaction with the electrolyte is suppressed, and the secondary battery When used in the above, the cycle characteristics can be improved.

[0084] [Production method] Positive electrode active material having a first region 101, a second region 102, and a third region 103 An example of a method for producing the substrate 100 will be described with reference to FIG. 2. In this example of the production method, a first One region has cobalt as the transition metal and the second region uses aluminum alkoxide. It is formed through the sol-gel method, and then heated to segregate magnesium on the surface. The third region 103 is formed by combining the first and second electrodes.

[0085] First, starting materials are prepared (S11). The starting materials include lithium, cobalt, and fluorine. The present invention uses particles of a composite oxide containing magnesium.

[0086] When synthesizing composite oxide particles containing lithium, cobalt, fluorine, and magnesium, First, the lithium source, the cobalt source, the magnesium source, and the fluorine source are weighed out. The lithium source may be, for example, lithium carbonate, lithium fluoride, or lithium hydroxide. The cobalt source can be, for example, cobalt oxide, cobalt hydroxide, cobalt oxyhydroxide, etc. Baltic, cobalt carbonate, cobalt oxalate, cobalt sulfate, etc. can be used. As the magnesium source, for example, magnesium oxide, magnesium fluoride, etc. may be used. As the fluorine source, for example, lithium fluoride, magnesium fluoride, etc. 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. You can be there.

[0087] The atomic ratio of magnesium to fluorine in the raw materials is preferably Mg:F=1:x (1.5≦x≦4). It is more preferable that the atomic ratio is about Mg:F=1:2. If there is any, magnesium segregation is likely to occur when heating is performed in a later process.

[0088] Next, the weighed starting materials are mixed. For example, a ball mill, a bead mill, etc. is used for mixing. It is possible.

[0089] Next, the mixed starting materials are fired. The firing is preferably carried out at a temperature of 800°C or higher and 1050°C or lower. The firing temperature is preferably 900°C or higher and 1000°C or lower. The firing time is 2 hours or longer. It is preferable to bake for 20 hours or less. Baking should be done in a dry atmosphere such as dry air. A dry atmosphere is preferably one in which the dew point is -50°C or less, and more preferably -10 An atmosphere of 0°C or less is more preferable. In this embodiment, heating is performed at 1000°C for 10 hours. The temperature rise rate is 200℃ / h, and dry air with a dew point of -109℃ is flowed at 10L / min. The heated material is then cooled to room temperature.

[0090] In the above process, particles of composite oxide containing lithium, cobalt, fluorine, and magnesium are mixed. It can be achieved.

[0091] The starting material is a composite oxide of lithium and cobalt that has been synthesized in advance. For example, lithium cobalt oxide particles (trade name: ) manufactured by Nippon Chemical Industry Co., Ltd. may be used. :C-20F) can be used as the starting material. It has a particle size of about 20 μm, Fluorine, magnesium, calcium, sodium, and silicon are detected in the area that can be analyzed by XPS from the surface. The starting material is lithium cobalt oxide particles containing silicon, sulfur, and phosphorus. The lithium cobalt oxide particles (product name: C-20F) manufactured by Nippon Chemical Industry Co., Ltd. were used as the It will be used.

[0092] Next, aluminum alkoxide is dissolved in alcohol, and the starting material particles are mixed with the solution. (S12).

[0093] Aluminum alkoxides include trimethoxyaluminum and triethoxyaluminum. aluminum, tri-n-propoxyaluminum, tri-i-propoxyaluminum, tri- n-Butoxyaluminum, Tri-i-butoxyaluminum, Tri-sec-butoxy Aluminum, tri-t-butoxyaluminum, etc. can be used. Aluminum The solvents that dissolve alkoxides include methanol, ethanol, propanol, 2- Propanol, butanol, 2-butanol, etc. can be used.

[0094] The alkoxide group of the aluminum alkoxide and the alcohol used as the solvent are different. Although different types may be combined, it is particularly preferred that they are of the same type.

[0095] Next, the mixture is stirred in an atmosphere containing water vapor (S13). H2O in the atmosphere and aluminum isopropoxide undergo hydrolysis and polycondensation reactions. Then, a gel-like aluminum oxide was formed on the surface of lithium cobalt oxide particles containing magnesium and fluorine. A layer containing ammonium is formed.

[0096] The stirring can be performed using, for example, a magnetic stirrer. The stirring time is determined by the amount of water in the atmosphere. and aluminum isopropoxide for a time sufficient to undergo hydrolysis and polycondensation reactions. For example, 4 hours, 25°C, 90% RH (Relative Humidity) This can be done under conditions of (relative humidity, ty).

[0097] As described above, by reacting aluminum alkoxide with water at room temperature, for example, a solvent When heating to a temperature exceeding the boiling point of alcohol (for example, 100°C or higher), Therefore, a coating layer containing aluminum that is more uniform and of higher quality can be formed.

[0098] The precipitate is recovered from the mixed solution after the above treatment (S14). In this embodiment, the particles are collected by filtration. A paper filter is used for filtration, and the residue is filtered with a solution of aluminum alkoxide. Wash with the same alcohol as the medium.

[0099] Next, the collected residue is dried (S15). In this embodiment, the residue is dried in a vacuum at 70° C. for 1 hour. It will be dried.

[0100] Next, the dried powder is heated (S16). By this heating, the magnesium contained in the starting material is Sium and fluorine segregate to the surface, forming third region 103 .

[0101] It is preferable to hold the heating at the specified temperature for 50 hours or less, and the holding time should be between 1 hour and 10 hours. It is more preferable to maintain the temperature at the specified temperature. The temperature is preferably 500°C or higher and 1200°C or lower, and more preferably 700°C or higher and 1000°C or lower. Preferably, the temperature is about 800° C., and more preferably about 800° C. Furthermore, it is preferable to heat the material in an atmosphere containing oxygen. In this embodiment, the specified temperature is set to 800° C. and is maintained for 2 hours. The temperature is 200℃ / h, and the flow rate of dry air is 10L / min. The cooling time is the same as the heating time or less. This will take the above amount of time.

[0102] Next, it is preferable to cool the heated powder and then perform a crushing process (S17). This can be done, for example, by sieving.

[0103] Through the above steps, the positive electrode active material 100 of one embodiment of the present invention can be manufactured.

[0104] (Embodiment 2) In this embodiment, a secondary battery having the positive electrode active material 100 described in the previous embodiment is used. In this embodiment, the positive electrode, the negative electrode, and the electrolyte solution However, the following description will be given taking as an example a secondary battery enclosed in an exterior body.

[0105] [Positive electrode] The positive electrode has a positive electrode active material layer and a positive electrode current collector.

[0106] <Cathode active material layer> The positive electrode active material layer includes a positive electrode active material. The positive electrode active material layer also includes a conductive additive and a binder. may have

[0107] The positive electrode active material 100 described in the previous embodiment can be used as the positive electrode active material. By using the positive electrode active material 100 described in the previous embodiment, it is possible to achieve high capacity and good cycle characteristics. An excellent secondary battery can be obtained.

[0108] As the conductive additive, a carbon material, a metal material, a conductive ceramic material, or the like can be used. A fibrous material may also be used as the conductive additive. The content of the electrical auxiliary agent is preferably 1 wt% or more and 10 wt% or less, and more preferably 1 wt% or more and 5 wt% or less. is more preferred.

[0109] The conductive additive can form an electrically conductive network in the electrode. This allows the electrical conduction path between the positive electrode active materials to be maintained. By adding the agent, an active material layer having high electrical conductivity can be realized.

[0110] Examples of the conductive additive include natural graphite, artificial graphite such as mesocarbon microbeads, and carbon fiber. Examples of carbon fibers that can be used include mesophase pitch carbon fibers. Carbon fibers such as isotropic pitch-based carbon fibers can be used. Carbon nanofibers and carbon nanotubes can be used. The tube can be produced by, for example, vapor phase growth method. For example, carbon black (acetylene black (AB) etc.), graphite particles Carbon materials such as graphene and fullerene can be used. Metal powders and fibers such as nickel, aluminum, silver, and gold, as well as conductive ceramic materials, etc. It can be used.

[0111] A graphene compound may also be used as the conductive additive.

[0112] Graphene compounds have excellent electrical properties, such as high conductivity, as well as high flexibility and high In addition, graphene may have excellent physical properties such as high mechanical strength. The graphene compound has a planar shape, which allows for surface contact with low contact resistance. In addition, even if they are thin, they can have very high conductivity, and even a small amount can be used to efficiently conduct electricity within the active material layer. Therefore, the graphene compound can be used as a conductive additive. This is preferable because it is possible to increase the contact area between the active material and the conductive additive. This is preferable because it may be possible to reduce the electrical resistance. For example, graphene or multigraphene or reduced graphene O It is particularly preferred to use RGO oxide. This refers to a compound obtained by reducing graphene oxide (GO).

[0113] When using an active material with a small particle size, for example, an active material with a particle size of 1 μm or less, the specific surface area of ​​the active material is Therefore, a large amount of conductive additive is required. This tends to result in a relative decrease in the amount of active material carried. If the amount of the conductive additive decreases, the capacity of the secondary battery will decrease. When graphene compounds are used, they efficiently form conductive paths even in small amounts. This is particularly preferable because it is possible to avoid reducing the amount of the active material carried.

[0114] As an example, in the case where a graphene compound is used as a conductive additive in the active material layer 200, An example of the cross-sectional structure will be described.

[0115] 3(A) shows a vertical cross-sectional view of the active material layer 200. The active material layer 200 is made of granular positive electrode active material. 100, a graphene compound 201 as a conductive additive, and a binder (not shown). Here, the graphene compound 201 may be, for example, graphene or multi-graphene. Here, the graphene compound 201 preferably has a sheet shape. In addition, the graphene compound 201 may be a multi-graphene or (and) a multi-graphene. The graphene may be partially overlapped to form a sheet.

[0116] In the vertical cross section of the active material layer 200, as shown in FIG. 3(A), In FIG. 3(A), the sheet-like graphene compound 201 is dispersed almost uniformly. The graphene compound 201 is shown schematically in bold, but in reality it is a single layer or multiple layers of carbon molecules. The graphene compounds 201 are thin films having a thickness of 1000 nm. The positive electrode active material 100 is wrapped around or covered by the positive electrode active material 100, or on the surface of the positive electrode active material 100. Since they are formed to stick together, they are in surface contact with each other.

[0117] Here, a plurality of graphene compounds are bonded to each other to form a mesh-like graphene compound. It is possible to form a graphene sheet (hereinafter referred to as a graphene compound net or graphene net). When the active material is covered with a graphene net, the graphene net can connect the active material to each other. It can also function as a binder to bind the particles together. Therefore, the ratio of the active material to the electrode volume or weight can be reduced. In other words, the capacity of the power storage device can be increased.

[0118] Here, graphene oxide is used as the graphene compound 201, and is mixed with an active material to form an active material. After forming the layer that will become the layer 200, it is preferable to reduce it. By using graphene oxide, which has extremely high dispersibility in polar solvents, The mixture 201 can be dispersed approximately uniformly inside the active material layer 200. The solvent is evaporated from the dispersion medium containing the dispersed graphene oxide, and the graphene oxide is reduced. Therefore, the graphene compound 201 remaining in the active material layer 200 partially overlaps with each other. By dispersing the particles so that they are in surface contact with each other, a three-dimensional conductive path can be formed. The reduction of graphene oxide may be performed by, for example, heat treatment or by using a reducing agent. It is also possible.

[0119] Therefore, unlike granular conductive additives such as acetylene black, which come into point contact with the active material, graphite Since the compound 201 enables surface contact with low contact resistance, it is more effective than ordinary conductive additives. The amount of the positive electrode active material 100 is smaller than that of the graphene compound 201, and the electrical conductivity between the positive electrode active material 100 and the graphene compound 201 is improved. Therefore, the ratio of the granular positive electrode active material 100 in the active material layer 200 can be increased. This makes it possible to increase the discharge capacity of the power storage device.

[0120] Examples of binders include styrene-butadiene rubber (SBR) and styrene-isoprene. Acrylonitrile-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene-propylene It is preferable to use a rubber material such as a propylene-diene copolymer. Fluorine rubber can be used.

[0121] As the binder, it is preferable to use, for example, a water-soluble polymer. As the molecule, for example, polysaccharides can be used. cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose Cellulose derivatives such as cellulose, diacetyl cellulose, and regenerated cellulose, as well as starch These water-soluble polymers can be used in combination with the rubber materials described above. It is even better if there is one.

[0122] Alternatively, the binder may be polystyrene, polymethyl acrylate, or polymethyl methacrylate. Polymethyl methacrylate (PMMA), sodium polyacrylate, polyvinyl Polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, Polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene Polyethylene, polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride Polyvinyl fluoride (PVdF), polyacrylonitrile (PAN), ethylene propylene diene polymer It is preferable to use materials such as polyvinyl acetate and nitrocellulose.

[0123] The binder may be used in combination with two or more of the above.

[0124] For example, a material having a particularly excellent viscosity adjusting effect may be used in combination with other materials. For example, rubber materials have excellent adhesive strength and elasticity, but it is difficult to adjust the viscosity when mixed with a solvent. In such cases, for example, mixing with a material that has a particularly excellent viscosity adjusting effect can As a material having a particularly excellent viscosity adjusting effect, for example, a water-soluble polymer is preferably used. Furthermore, examples of water-soluble polymers that are particularly effective in adjusting viscosity include the aforementioned polysaccharides, such as carbohydrates. Carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxy Cellulose derivatives such as propyl cellulose, diacetyl cellulose, and regenerated cellulose Carbohydrates and starches can be used.

[0125] The cellulose derivatives such as carboxymethyl cellulose are, for example, By converting cellulose into salts such as sodium salts or ammonium salts, the solubility increases, It is easier to exert its effect as a viscosity adjuster. The increased solubility makes it easier to make electrode slurry. When preparing a substrate, it is also possible to improve the dispersibility of the active material and other components. In this case, the cellulose and cellulose derivatives used as binders for electrodes include These salts are also included.

[0126] Water-soluble polymers stabilize viscosity by dissolving in water, and also act as active materials and binders. Other materials to be combined, such as styrene butadiene rubber, are stably dispersed in aqueous solution. In addition, since it has functional groups, it can be easily and stably adsorbed onto the surface of the active material. It is expected that cellulose derivatives such as carboxymethyl cellulose will For example, many materials have functional groups such as hydroxyl groups and carboxyl groups. It is expected that the polymers will interact with each other and widely cover the surface of the active material.

[0127] When the binder that covers or contacts the surface of the active material forms a film, it is called a passive film. It is expected that the passive film will also play a role in suppressing the decomposition of the electrolyte. It is a film with no or very low electrical conductivity, and for example, it is When a dynamic membrane is formed, it is possible to suppress the decomposition of the electrolyte at the battery reaction potential. In addition, the passive film suppresses electrical conductivity while allowing lithium ions to conduct. And even more desirable.

[0128] <Positive electrode current collector> The positive electrode current collector may be made of metals such as stainless steel, gold, platinum, aluminum, titanium, or the like. Highly conductive materials such as alloys of these can be used. It is preferable that silicon, titanium, neodymium, scavenger, etc. are not eluted at the potential of the positive electrode. Aluminum alloys containing elements such as indium and molybdenum that improve heat resistance are used. It can also be formed from a metal element that reacts with silicon to form silicide. Metal elements that react with silicon to form silicide include zirconium, titanium, and Tantalum, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten , cobalt, nickel, etc. Current collectors are available in foil, plate (sheet), mesh, and punched shapes. The current collector may be in the form of a metal, an expanded metal, or the like. It is recommended to use a thickness of 5 μm or more and 30 μm or less.

[0129] [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.

[0130] <Negative electrode active material> As the negative electrode active material, for example, an alloy-based material or a carbon-based material can be used.

[0131] As a negative electrode active material, it is possible to carry out charge-discharge reactions by alloying and dealloying reactions with lithium. Any suitable element can be used, such as silicon, tin, gallium, aluminum, Rumanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. Materials containing at least one of these elements can be used. These elements have a large capacity compared to carbon. Silicon has a particularly high theoretical capacity of 4200mAh / g. It is preferable to use silicon. Alternatively, compounds containing these elements may be used. For example, SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V 2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3 Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, I nSb, SbSn, etc. Here, the charge / discharge reaction occurs due to alloying and dealloying reactions with lithium. Elements capable of undergoing a reaction and compounds containing such elements are sometimes called alloy materials. do.

[0132] In this specification and the like, SiO refers to, for example, silicon monoxide. Alternatively, SiO refers to SiO x Here, it is preferable that x has a value close to 1. For example, x is 0 A value between 0.2 and 1.5 is preferred, and a value between 0.3 and 1.2 is more preferred.

[0133] Carbon materials include graphite, easily graphitizable carbon (soft carbon), and non-graphitizable carbon (hard carbon). carbon nanotubes, graphene, carbon black, etc. may be used. .

[0134] Examples of graphite include artificial graphite and natural graphite. Examples include carbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite. Here, as the artificial graphite, spherical graphite having a spherical shape can be used. For example, the MCMB may have a spherical shape, which is preferable. It is relatively easy to reduce the particle size, which is sometimes preferable. Examples include flake graphite and spherical natural graphite.

[0135] When lithium ions are inserted into graphite (when lithium-graphite intercalation compounds are formed), It exhibits a low potential similar to that of lithium metal (0.05V to 0.3V vs. Li / L i + This allows the lithium-ion secondary battery to exhibit a high operating voltage. In addition, graphite has a relatively high capacity per unit volume, a relatively small volume expansion, and is inexpensive. It is preferable because it has advantages such as higher safety compared to lithium metal.

[0136] In addition, titanium dioxide (TiO2) and lithium titanium oxide (Li4T i5O 12 ), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5) Oxides such as tungsten oxide (WO2) and molybdenum oxide (MoO2) can be used. can.

[0137] In addition, the negative electrode active material is a composite nitride of lithium and transition metals, which has a Li3N structure. Li 3-x M x N (M=Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3 ) And preferable.

[0138] When a composite nitride of lithium and a transition metal is used, the negative electrode active material contains lithium ions, The positive electrode active material is a combination of materials such as V2O5 and Cr3O8 that do not contain lithium ions. It is preferable that a material containing lithium ions is used as the positive electrode active material. By first removing the lithium ions contained in the positive electrode active material, A complex nitride of lithium and a transition metal can be used.

[0139] In addition, a material that undergoes a conversion reaction can also be used as the negative electrode active material. , cobalt oxide (CoO), nickel oxide (NiO), iron oxide (FeO), etc. A transition metal oxide that does not form an alloy with the metal may be used as the negative electrode active material. Further materials that can be produced include Fe2O3, CuO, Cu2O, RuO2, Cr2O3, etc. oxide, CoS 0.89 , NiS, CuS and other sulfides, Zn3N2, Cu3N, Ge3 Nitrides such as N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3, etc. It also occurs with fluoride.

[0140] The conductive additive and binder that can be contained in the negative electrode active material layer are the same as those that can be contained in the positive electrode active material layer. The same materials as the conductive additive and binder can be used.

[0141] <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.

[0142] [Electrolyte] The electrolytic solution contains a solvent and an electrolyte. The solvent for the electrolytic solution is preferably an aprotic organic solvent. For example, ethylene carbonate (EC), propylene carbonate (PC), ethylene carbonate, chloroethylene carbonate, vinylene carbonate, gamma-butyrolactone lactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1 ,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfone oxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran One of tetrahydrofuran, sulfolane, sultone, etc., or two or more of these Combinations and ratios may be used.

[0143] In addition, by using a polymer material that gels as a solvent for the electrolyte, safety against leakage etc. is improved. The safety of the secondary battery is improved. In addition, it is possible to make the secondary battery thinner and lighter. Typical examples of materials are silicone gel, acrylic gel, acrylonitrile gel, and polyethylene gel. Styrene oxide gel, polypropylene oxide gel, fluorine polymer gel, etc. There is.

[0144] 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 batteries, it is possible to prevent the internal temperature from rising due to an internal short circuit or overcharging of the storage battery. Even if the battery is damaged, it can prevent the battery from exploding or catching fire. Ionic liquids are made of cations and anions. The organic cations used in the electrolyte include quaternary cations. Ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, etc. aliphatic onium cations such as imidazolium cations and pyridinium cations Aromatic cations are also used as anions in electrolytes. Anions, monovalent methide anions, fluorosulfonate anions, perfluoroalkyl Sulfonate anion, tetrafluoroborate anion, perfluoroalkylborate anion, hexafluorophosphate anion, or perfluoroalkylphosphate anions, etc.

[0145] The electrolyte to be dissolved in the solvent is, for example, LiPF6, LiClO4, Li AsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4 , Li2B 10 Cl 10 , Li2B 12 Cl 12 , LiCF3SO3, LiC4F9SO 3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2) 2. Lithium such as LiN(C4F9SO2)(CF3SO2) and LiN(C2F5SO2)2 Use one or more of these ammonium salts in any combination and ratio. can be done.

[0146] The electrolyte used in the energy storage device is free from granular waste and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as "impurities"). It is preferable to use a highly purified electrolyte solution with a low content of ammonium hydroxide. Specifically, the weight ratio of impurities to the electrolyte is 1% or less, preferably 0.1% or less, more preferably It is preferably 0.01% or less.

[0147] In addition, the electrolyte contains vinylene carbonate, propane sultone (PS), and tert-butyl ether. Benzene (TBB), Fluoroethylene Carbonate (FEC), LiBOB, and Squishi Additives such as dinitrile compounds such as dibenzonitrile and adiponitrile may also be added. The concentration of the agent may be, for example, 0.1 wt % to 5 wt % relative to the total solvent.

[0148] Alternatively, a polymer gel electrolyte may be used in which a polymer is swollen with an electrolytic solution.

[0149] Examples of the polymer include polyalkylene oxides such as polyethylene oxide (PEO). Polymers with a hexagonal structure, PVDF, polyacrylonitrile, etc., and their For example, a copolymer containing PVDF and hexafluoropropylene (H PVDF-HFP, a copolymer of PVDF and PVDF, can be used. The mer may have a porous shape.

[0150] In addition, instead of the electrolyte solution, solid electrolytes containing inorganic materials such as sulfides and oxides, and P A solid electrolyte containing a polymer material such as EO (polyethylene oxide) can be used. When a solid electrolyte is used, there is no need to install a separator or spacer. Since the entire pond can be solidified, there is no risk of leakage, dramatically improving safety.

[0151] [Separator] The secondary battery preferably has a separator. The separator may be made of, for example, paper. Cellulose-containing fibers, nonwoven fabrics, glass fibers, ceramics, or nanofibers, including Ilon (polyamide), Vinylon (polyvinyl alcohol fiber), polyester, acrylic Use synthetic fibers such as styrene, polyolefin, and polyurethane. The separator is made into an envelope and encases either the positive or negative electrode. It is preferable to arrange it as follows.

[0152] The separator may have a multi-layer structure. For example, the separator may be made of an organic material such as polypropylene or polyethylene. The material film is made of ceramic material, fluorine material, polyamide material, or a combination of these. The ceramic material can be, for example, aluminum oxide. Aluminum particles, silicon oxide particles, etc. can be used. For example, PVDF, polytetrafluoroethylene, etc. can be used. Polyamide-based materials Materials used include nylon, aramid (meta-aramid, para-aramid), etc. It is possible.

[0153] Coating with ceramic materials improves oxidation resistance, making it suitable for separators during high-voltage charging and discharging. This can suppress the deterioration of the battery and improve the reliability of the secondary battery. By coating, the separator and electrodes can be more easily attached to each other, improving output characteristics. Coating polyamide materials, especially aramid, improves heat resistance, which contributes to the safety of secondary batteries. Safety can be improved.

[0154] For example, a mixture of aluminum oxide and aramid is coated on both sides of a polypropylene film. Alternatively, aluminum oxide may be applied to the surface of the polypropylene film that comes into contact with the positive electrode. The surface that comes into contact with the negative electrode may be coated with a mixed material of rubber and aramid, and a fluorine-based material may be coated on the surface that comes into contact with the negative electrode. .

[0155] By using a multilayer separator, the safety of the secondary battery can be maintained even if the overall thickness of the separator is thin. Since the temperature can be maintained, the capacity per volume of the secondary battery can be increased.

[0156] (Embodiment 3) In this embodiment, the shape of the secondary battery having the positive electrode active material 100 described in the previous embodiment is The material used in the secondary battery described in this embodiment is the same as that in the previous embodiment. The description of the state can be taken into consideration.

[0157] [Coin-type secondary battery] First, an example of a coin-type secondary battery will be described. Figure 4(A) shows a coin-type (single-layer flat type) 4(A) and 4(B) are external views of the secondary battery, and FIG. 4(B) is a cross-sectional view thereof.

[0158] The coin-type secondary battery 300 has a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal. 302 is insulated and sealed by a gasket 303 made of polypropylene or the like. The positive electrode 304 is composed of a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with the positive electrode current collector 305. The negative electrode 307 is formed by a negative electrode current collector 308 and a The negative electrode active material layer 309 is formed by bonding the negative electrode active material layer 309 to the negative electrode active material layer 309 .

[0159] The positive electrode 304 and the negative electrode 307 used in the coin-type secondary battery 300 are each an active material. The barrier layer need only be formed on one side.

[0160] The positive electrode can 301 and the negative electrode can 302 are made of nickel and aluminum, which are corrosion-resistant to the electrolyte. , titanium, or alloys thereof or alloys of these with other metals (e.g. stainless steel) In addition, nickel or aluminum can be used to prevent corrosion by the electrolyte. The positive electrode can 301 is preferably coated with a positive electrode 304, and the negative electrode can 302 is preferably coated with a negative electrode 304. 7 and electrically connect to each other.

[0161] The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated with an electrolyte, and the resultant structure shown in FIG. As shown in FIG. 1, the positive electrode can 301 is placed downward, and the positive electrode 304, separator 310, negative electrode 307, and negative electrode 308 are connected to the positive electrode can 301. The positive electrode can 301 and the negative electrode can 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are connected with a gasket 303 interposed therebetween. Then, the laminate is pressed to form a coin-type secondary battery 300.

[0162] By using the positive electrode active material described in the previous embodiment for the positive electrode 304, it is possible to achieve high capacity cycling. The coin-type secondary battery 300 can be made to have excellent characteristics.

[0163] [Cylindrical secondary battery] Next, an example of a cylindrical secondary battery will be described with reference to FIG. 5. A cylindrical secondary battery 600 is As shown in FIG. 5(A), the positive electrode cap (battery lid) 601 is provided on the top surface, and the side and bottom surfaces are provided. The positive electrode cap 601 and the battery can (external can) 602 are disposed on the surface. ) 602 is insulated by a gasket (insulating packing) 610.

[0164] 5(B) is a schematic diagram showing the cross section of a cylindrical secondary battery. Inside 602, a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 sandwiched between them. 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. Metals such as nickel, aluminum, titanium, etc. that are corrosion-resistant to the electrolyte, or Alloys of these and other metals (for example, stainless steel) can be used. In addition, it is preferable to coat the electrode with nickel, aluminum, or the like to prevent corrosion by the electrolyte. The battery element, in which the positive electrode, negative electrode, and separator are wound inside the battery can 602, is The battery is sandwiched between a pair of opposing insulating plates 608 and 609. The battery can 602 is filled with a non-aqueous electrolyte (not shown). The same as the in-type secondary battery can be used.

[0165] The positive and negative electrodes used in cylindrical secondary batteries are wound, so active material is formed on both sides of the current collector. A positive electrode terminal (positive electrode current collecting lead) 603 is connected to the positive electrode 604, and a negative A negative electrode terminal (negative electrode current collecting lead) 607 is connected to the positive electrode 603. The positive electrode terminal 607 can be made of a metal material such as aluminum. 603 is resistance-welded to the safety valve mechanism 612, and the negative terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 is a PTC (Positive Temperature Coefficient) element. The positive electrode cap 601 is electrically connected to the positive electrode cap 601 via a positive electrode coefficient 611. The safety valve mechanism 612 releases the positive electrode cap 601 when the internal pressure of the battery exceeds a predetermined threshold. The PTC element 611 cuts off the electrical connection between the positive electrode 604 and the positive electrode 604. It is a thermal resistor whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current. It prevents abnormal heat generation. The PTC element is made of barium titanate (BaTiO3) Semiconductor ceramics and the like can be used.

[0166] By using the positive electrode active material described in the above embodiment for the positive electrode 604, it is possible to achieve high capacity cycling. The cylindrical secondary battery 600 can be made to have excellent characteristics.

[0167] [Structure example of power storage device] Another structural example of the power storage device will be described with reference to FIGS.

[0168] 6(A) and 6(B) are diagrams showing the appearance of the power storage device. 900 and a secondary battery 913. A label 910 is attached to the secondary battery 913. Furthermore, as shown in FIG. 6B, the power storage device has a terminal 951, a terminal 952, and an The antenna 914 and the antenna 915 are included.

[0169] The circuit board 900 has a terminal 911 and a circuit 912. The terminal 911 is connected to a terminal 951. , terminal 952, antenna 914, antenna 915, and circuit 912. A plurality of terminals 911 are provided, and each of the plurality of terminals 911 is used as a control signal input terminal, a power supply terminal, etc. may also be used.

[0170] The circuit 912 may be provided on the back surface of the circuit board 900. The antenna 915 is not limited to a coil shape, but may be, for example, a wire shape or a plate shape. Planar antenna, aperture antenna, traveling wave antenna, EH antenna, magnetic field antenna, dielectric Alternatively, antenna 914 or antenna 915 may be used. The flat conductor may function as one of the conductors for electric field coupling. In other words, the capacitor has two conductors, one of which is an annulus. The antenna 914 or the antenna 915 may be activated. Instead, power can be exchanged using an electric field.

[0171] 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.

[0172] The power storage device has a layer 916 between the antenna 914 and the secondary battery 913 and an antenna 915. The layer 916 has a function of shielding an electromagnetic field generated by the secondary battery 913, for example. The layer 916 may be made of, for example, a magnetic material.

[0173] The structure of the power storage device is not limited to that shown in FIG.

[0174] For example, as shown in Figs. 7(A-1) and 7(A-2), In the secondary battery 913 shown in FIG. 7(A-1) is an external view seen from one side of the pair of surfaces, and FIG. 7(A-2) is a 6(A) and 6(B) are external views seen from the other side of the pair of surfaces. For the same parts as those of the power storage device shown in FIG. 6(A) and FIG. 6(B), the description of the power storage device shown in FIG. 6(A) and FIG. 6(B) applies. It can be used as needed.

[0175] As shown in FIG. 7(A-1), a layer 916 is sandwiched between one of the two surfaces of a secondary battery 913. 7(A-2), a retainer 914 is provided, and the other of the pair of surfaces of the secondary battery 913 is The antenna 915 is provided on the second electrode 913 with a layer 917 sandwiched therebetween. The layer 917 has a function of preventing the influence of the electromagnetic field caused by the magnetic field. Sexual bodies can be used.

[0176] By adopting the above structure, the size of both the antenna 914 and the antenna 915 can be increased. It is possible.

[0177] Alternatively, as shown in Figs. 7(B-1) and 7(B-2), A separate antenna may be provided on each of a pair of opposing surfaces of secondary battery 913. FIG. 7(B-1) is an external view seen from one side of the pair of surfaces, and FIG. 7(B-2) is 6(A) and 6(B) are external views seen from the other side of the pair of surfaces. 6A and 6B. It can be used as appropriate.

[0178] As shown in FIG. 7(B-1), a layer 916 is sandwiched between one of the two surfaces of a secondary battery 913. 7B-2, a secondary battery 91 An antenna 918 is provided on the other of the pair of surfaces of the substrate 3, sandwiching a layer 917 therebetween. For example, the antenna 918 has a function of performing data communication with an external device. For example, antennas having shapes applicable to the antennas 914 and 915 can be applied. As a communication method between the power storage device and other devices via antenna 918, NFC is available. It is possible to apply a response method that can be used between the power storage device and other devices, such as Cut.

[0179] Alternatively, as shown in FIG. 8A, the secondary battery 913 shown in FIGS. 6A and 6B may be A display device 920 may be provided. The display device 920 is electrically connected to the terminal 911 via the terminal 919. It is not necessary to provide the label 910 in the area where the display device 920 is provided. Note that the same parts as those of the power storage device shown in FIGS. 6(A) and 6(B) are shown in FIG. The description of the power storage device in FIG. 6B can be used as appropriate.

[0180] The display device 920 displays, for example, an image indicating whether charging is in progress or not, an image indicating the amount of stored power, etc. The display device 920 may be, for example, an electronic paper, a liquid crystal display, an electrophotographic display, or the like. For example, an electroluminescence (EL) display device can be used. By using the par, the power consumption of the display device 920 can be reduced.

[0181] Alternatively, as shown in FIG. 8B, the secondary battery 913 shown in FIGS. 6A and 6B may be connected to the sensor. The sensor 921 may be electrically connected to the terminal 911 via a terminal 922. 6A and 6B. The description of the power storage device in FIGS. 6A and 6B can be used as appropriate.

[0182] The sensor 921 may be, for example, a sensor for detecting displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, etc. , liquid, magnetic, temperature, chemical, sound, time, hardness, electric field, current, voltage, power, radiation, flow It is sufficient if it has the function of measuring volume, humidity, gradient, vibration, odor, or infrared. By providing the sensor 921, for example, data indicating the environment in which the power storage device is placed can be acquired. It is also possible to detect a signal (such as temperature) and store it in memory within the circuit 912.

[0183] Furthermore, an example of the structure of the secondary battery 913 will be described with reference to FIGS.

[0184] The secondary battery 913 shown in FIG. 9A has a terminal 951 and a terminal 952 provided inside a housing 930. The winding 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. 930. For convenience, the housing 930 is shown in FIG. 9(A). However, in reality, the winding body 950 is covered by the housing 930, and the terminals 951 and 952 are The housing 930 is made of a metal material (for example, aluminum). etc.) or resin materials can be used.

[0185] As shown in FIG. 9B, the housing 930 shown in FIG. 9A is made of a plurality of materials. For example, the secondary battery 913 shown in FIG. 9B may be a battery having a housing 930a and a housing 930b. The wound body 950 is located in the area surrounded by the housing 930a and the housing 930b. It is provided.

[0186] The housing 930a can be made of an insulating material such as organic resin. By using a material such as organic resin on the surface on which the secondary battery 913 is formed, If the shielding of the electric field by the housing 930a is small, the shielding of the electric field by the housing 930a can be suppressed. Antennas such as antenna 914 and antenna 915 may be provided inside the housing 930b. For example, a metal material can be used.

[0187] Furthermore, the structure of the wound body 950 is shown in Fig. 10. The wound body 950 is made up of a negative electrode 931 and a positive electrode 932. The winding body 950 has a pole 932 and a separator 933. The negative electrode 931 and the positive electrode 932 are stacked one on top of the other, and the laminated sheet is wound to form a wound body. The negative electrode 931, the positive electrode 932, and the separator 933 may be further laminated. You can stack several of them.

[0188] 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. Connected.

[0189] By using the positive electrode active material described in the above embodiment for the positive electrode 932, it is possible to achieve high capacity cycling. The secondary battery 913 can have excellent characteristics.

[0190] [Laminated secondary battery] Next, an example of a laminated secondary battery will be described with reference to FIGS. If the laminated secondary battery is made flexible, it will have at least one flexible portion. If the secondary battery is mounted in an electronic device that also has a battery, it can be bent according to the deformation of the electronic device. can.

[0191] A laminated secondary battery 980 will be described with reference to FIG. The battery 980 has a wound body 993 shown in FIG. 10, a positive electrode 995, and a separator 996. Similar to the wound body 950, a negative electrode 994 and a positive electrode 995 are stacked with a separator 996 sandwiched therebetween. The laminated sheet is then wound up.

[0192] The number of layers of the negative electrode 994, the positive electrode 995, and the separator 996 is determined as required. The negative electrode 994 is connected to the lead electrode 997 and the lead The positive electrode 995 is connected to a negative electrode current collector (not shown) via one of the lead electrodes 998. The positive electrode 997 and the lead electrode 998 are connected to a positive electrode current collector (not shown).

[0193] As shown in FIG. 11(B), a film 981 that serves as an exterior body and a film 98 having a recess are 2 are bonded together by thermocompression or the like, and the above-mentioned wound body 993 is housed in the space formed. In this way, a secondary battery 980 can be fabricated as shown in FIG. 3 has lead electrodes 997 and 998, and is connected to a film 981 and a recessed portion. The inside of the film 982 is impregnated with an electrolyte.

[0194] The film 981 and the film 982 having the recesses are made of a metal material such as aluminum. The film 981 and the film 982 having the recesses can be made of a material such as a resin. If a resin material is used as the material, when external force is applied, the film 981 and the recessed portion The film 982 can be deformed to produce a flexible secondary battery. can be done.

[0195] In addition, although Fig. 11(B) and Fig. 11(C) show examples using two films, A space is formed by folding one sheet of film, and the above-mentioned wound body 99 is inserted into the space. It may also accommodate 3.

[0196] By using the positive electrode active material described in the previous embodiment for the positive electrode 995, it is possible to achieve high capacity cycling. The secondary battery 980 can have excellent characteristics.

[0197] 11 shows a secondary battery 9 having a wound body in a space formed by a film that serves as an exterior body. We have explained the example of 80, but as shown in Figure 12, for example, the shape is determined by the film that forms the exterior body. It can also be used as a secondary battery having a plurality of rectangular positive electrodes, separators, and negative electrodes in the space formed. good.

[0198] 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 positive electrode active material layer 502, a negative electrode current collector 504 and a negative electrode active material layer 505 The battery includes a negative electrode 506, a separator 507, an electrolyte 508, and an exterior body 509. A separator 507 is provided between a positive electrode 503 and a negative electrode 506 provided in a body 509. The exterior body 509 is filled with an electrolyte 508. The electrolyte solution shown in the second embodiment can be used.

[0199] In the laminated secondary battery 500 shown in FIG. 12(A), a positive electrode current collector 501 and a negative electrode current collector 502 are The electrode current collector 504 also serves as a terminal for electrical contact with the outside. A part of the current collector 501 and the negative electrode current collector 504 is exposed to the outside from the outer casing 509. In addition, the positive electrode current collector 501 and the negative electrode current collector 504 may be disposed in the outer casing 509. The lead electrode is not exposed to the outside, and the lead electrode is connected to the positive electrode current collector 501 or the negative electrode The lead electrode may be exposed to the outside by ultrasonic bonding to the current collector 504 .

[0200] In the laminated secondary battery 500, the exterior body 509 is made of, for example, polyethylene, poly A film made of propylene, polycarbonate, ionomer, polyamide, etc. is coated with an A thin metal film with excellent flexibility, such as aluminum, stainless steel, copper, or nickel, is applied, and the metal is further On the metallic thin film, an insulating synthetic resin such as polyamide resin or polyester resin is applied as the outer surface of the exterior body. A three-layer laminate film provided with an oil film can be used.

[0201] An example of the cross-sectional structure of a laminated secondary battery 500 is shown in FIG. A) shows an example of a structure consisting of two current collectors for simplicity, but in reality, it is composed of multiple electrode layers. It consists of:

[0202] In FIG. 12(B), as an example, the number of electrode layers is set to 16. However, the secondary battery 500 has flexibility. In FIG. 12(B), the negative electrode current collector 504 has eight layers. The positive electrode current collector 501 has eight layers, making a total of 16 layers. The cross section of the extraction part is shown, and eight layers of negative electrode current collector 504 are ultrasonically bonded. The number of electrode layers is not limited to 16, and may be more or less. In this case, a secondary battery having a larger capacity can be obtained. In this case, a secondary battery can be made thin and highly flexible.

[0203] An example of the external appearance of a laminated secondary battery 500 is shown in FIGS. 13 and 14. 3 and 14 show a positive electrode 503, a negative electrode 506, a separator 507, an outer casing 509, a positive electrode lead The positive electrode 510 and the negative electrode 511 are provided.

[0204] 15(A) shows an external view of the positive electrode 503 and the negative electrode 506. The positive electrode 503 is connected to the positive electrode current collector 50 1, and the positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501. 503 has a region where the positive electrode current collector 501 is partially exposed (hereinafter referred to as the tab region). 506 has a negative electrode current collector 504, and a negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. In addition, the negative electrode 506 has a region where the negative electrode current collector 504 is partially exposed, that is, a tab region. The area and shape of the tab regions of the positive electrode and negative electrode are not limited to the example shown in FIG. I can't.

[0205] [Method for manufacturing laminated secondary batteries] Here, an example of a method for manufacturing the laminated secondary battery shown in FIG. 13 will be described with reference to FIG. This will be explained using (B) and (C).

[0206] First, the negative electrode 506, the separator 507, and the positive electrode 503 are stacked. The figure shows five pairs of negative electrodes 506, separators 507, and positive electrodes 503. Next, the bonding of the tab regions of the positive electrode 503 and the bonding of the tabs of the positive electrode on the outermost surface are shown. The positive electrode lead electrode 510 is bonded to the region. For example, ultrasonic welding or the like can be used for bonding. Similarly, the bonding of the tab regions of the negative electrodes 506 to each other and the bonding of the negative electrode leads to the tab region of the negative electrode on the outermost surface are also preferable. Then, the bonded electrode 511 is formed.

[0207] Next, the negative electrode 506 , the separator 507 and the positive electrode 503 are placed on the exterior body 509 .

[0208] Next, as shown in FIG. 15(C), the exterior body 509 is folded at the portion indicated by the broken line. After that, the outer periphery of the exterior body 509 is bonded. For example, thermocompression bonding may be used for bonding. , so that the electrolyte 508 can be poured later, An area that is not bonded (hereinafter referred to as an inlet) is provided.

[0209] Next, the electrolyte 508 is introduced into the inside of the exterior body 509 through an inlet provided in the exterior body 509. The introduction of the electrolytic solution 508 is preferably carried out under a reduced pressure atmosphere or an inert gas atmosphere. Finally, the inlet is joined. In this way, a laminated secondary battery is completed. A secondary battery 500 can be fabricated.

[0210] By using the positive electrode active material described in the above embodiment for the positive electrode 503, it is possible to achieve high capacity cycling. The secondary battery 500 can have excellent characteristics.

[0211] [Bendable secondary battery] Next, an example of a bendable secondary battery will be described with reference to FIGS. 16 and 17. .

[0212] Figure 16(A) shows a schematic top view of a bendable battery 250. (B2) and (C) are cut along the cutting lines C1-C2 and C3-C4 in FIG. 16(A), respectively. 2 is a schematic cross-sectional view taken along the line A1-A2. The positive electrode 211a and the negative electrode 211b are housed inside the battery 251. lead 212a electrically connected to the negative electrode 211b, and lead 211b electrically connected to the negative electrode 211c. 2b extends outside the exterior body 251. In addition, in the area surrounded by the exterior body 251, In addition to the electrode 211a and the negative electrode 211b, an electrolyte (not shown) is enclosed.

[0213] The positive electrode 211a and the negative electrode 211b of the battery 250 will be described with reference to FIG. 17. FIG. 17(A) illustrates the stacking order of the positive electrode 211a, the negative electrode 211b, and the separator 214. FIG. 17(B) shows a perspective view of the positive electrode 211a and the negative electrode 211b, as well as a lead 2. 12a and a lead 212b.

[0214] As shown in FIG. 17(A), the battery 250 includes a plurality of rectangular positive electrodes 211a, a plurality of rectangular positive electrodes 211b, and a plurality of rectangular positive electrodes 211c. The positive electrode 211a and the negative electrode 211b are connected to each other, and a plurality of separators 214 are connected to each other. Each of the positive electrode 211a and the positive electrode 211b has a protruding tab portion and a portion other than the tab. A positive electrode active material layer is formed on the portion other than the tab, and a negative electrode 211b is formed on the portion other than the tab on one surface of the negative electrode 211b. A negative electrode active material layer is formed.

[0215] The surfaces of the positive electrode 211a on which the positive electrode active material layer is not formed and the surfaces of the negative electrode 211b on which the negative electrode active material layer is not formed are The positive electrode 211a and the negative electrode 211b are stacked so that the surfaces on which the porous layer is not formed are in contact with each other. will be done.

[0216] In addition, the surface on which the positive electrode active material layer of the positive electrode 211a is formed and the surface on which the negative electrode active material layer of the negative electrode 211b is formed are A separator 214 is provided between the formed surfaces. The separator 214 is shown in dotted lines.

[0217] As shown in FIG. 17(B), the positive electrodes 211a and the leads 212a are connected to each other at the joints 215. The negative electrodes 211b and the leads 212b are electrically connected at the joints 211a and 212b. Electrical connection is made at 15b.

[0218] Next, the exterior body 251 will be described with reference to FIGS. 16(B1), (B2), (C), and (D). do.

[0219] The exterior body 251 has a film-like shape and is configured to sandwich the positive electrode 211a and the negative electrode 211b. The exterior body 251 is folded in two at the folded portion 261 and a pair of sealing portions 2 The pair of sealing portions 262 are connected to the positive electrode 211a and the negative electrode 211b. The seal portion 26 is provided on either side of the pole 211b and can also be called a side seal. 3 has a portion overlapping with the lead 212a and the lead 212b, and is also called a top seal. This can be done.

[0220] The exterior body 251 has a ridge line 271 and a valley line 272 at the portion overlapping the positive electrode 211a and the negative electrode 211b. It is preferable that the sealing portion 26 of the exterior body 251 has a wave shape in which the grooves 72 are arranged alternately. 2 and the seal portion 263 are preferably flat.

[0221] FIG. 16(B1) is a cross section cut at the part overlapping with the ridge line 271, and FIG. 16(B2) is a cross section cut at the part overlapping with the ridge line 271. The cross section is taken at the part overlapping with the valley line 272. 250 and corresponds to the cross section in the width direction of the positive electrode 211a and the negative electrode 211b.

[0222] Here, the distance between the end of the negative electrode 211b in the width direction and the seal portion 262 is defined as La. When the battery 250 is deformed by bending or the like, the positive electrode 211a and the negative electrode 211b are 211b deform so as to be displaced from each other in the length direction. The exterior body 251 rubs strongly against the positive electrode 211a and the negative electrode 211b, causing the exterior body 251 to be damaged. In particular, if the metal film of the exterior body 251 is exposed, the metal film may become electrically Therefore, it is recommended to set the distance La as long as possible. On the other hand, if the distance La is too large, the volume of the battery 250 increases. Put away.

[0223] In addition, the greater the total thickness of the stacked positive electrode 211a and negative electrode 211b, the greater the It is preferable to increase the distance La between the end of b and the seal portion 262.

[0224] More specifically, a stack of positive electrode 211a, negative electrode 211b, and a separator (not shown) are When the total thickness of 214 is thickness t, the distance La is between 0.8 and 3.0 times the thickness t. Preferably, the ratio is 0.9 to 2.5 times, more preferably 1.0 to 2.0 times. By setting the distance La in this range, it is possible to make the device compact and resistant to bending. This makes it possible to realize a highly reliable battery.

[0225] In addition, when the distance between the pair of seal portions 262 is a distance Lb, the distance Lb is It is preferable that the width Wb of the battery 250 is sufficiently larger than the width Wb of the battery 250. When deformation such as bending occurs, the positive electrode 211a and the negative electrode 211b come into contact with the exterior body 251. Even if the positive electrode 211a and the negative electrode 211b are separated, a part of the positive electrode 211a and the negative electrode 211b can be shifted in the width direction. To effectively prevent the electrode 211a and the negative electrode 211b from rubbing against the exterior body 251. can be done.

[0226] For example, the difference between the distance Lb between the pair of seal portions 262 and the width Wb of the negative electrode 211b is 1.6 times or more and 6.0 times or less, preferably 1.8 times, the thickness t of 211a and the negative electrode 211b It is 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. .

[0227] 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: It's nice.

[0228]

number

[0229] Here, a is 0.8 or more and 3.0 or less, preferably 0.9 or more and 2.5 or less, and more preferably is between 1.0 and 2.0.

[0230] FIG. 16(C) is a cross section including the lead 212a, and shows the battery 250, the positive electrode 211a, and As shown in FIG. 16(C), the bent portion 2 corresponds to a cross section of the negative electrode 211b in the longitudinal direction. 61, the ends of the positive electrode 211a and the negative electrode 211b in the length direction and the outer casing 251 It is preferable to have a space 273 therebetween.

[0231] FIG. 16(D) shows a schematic cross-sectional view of the battery 250 when bent. This corresponds to the cross section taken along the line B1-B2 in FIG. 16(A).

[0232] When the battery 250 is bent, the part of the exterior body 251 located on the outside of the bend stretches, and the part located on the inside More specifically, the part located on the outside of the exterior body 251 is deformed so as to shrink. On the other hand, the outer casing 251 is deformed so that the amplitude of the wave becomes smaller and the period of the wave becomes larger. The part located inside the In this way, the deformation of the exterior body 251 causes the load acting on the exterior body 251 due to bending. Since the stress is relieved, the material that constitutes the exterior body 251 itself does not need to expand or contract. As a result, the battery 250 can be bent with a small force without damaging the exterior body 251.

[0233] Furthermore, as shown in FIG. 16(D), when the battery 250 is bent, the positive electrode 211a and the negative electrode 21 At this time, the plurality of stacked positive electrodes 211a and negative electrodes 1b are displaced relative to each other. Since one end of 211b on the sealing portion 263 side is fixed by the fixing member 217, The amount of deviation increases as the electrode is closer to the positive electrode 21. The stress applied to the positive electrode 211a and the negative electrode 211b is relieved, and the positive electrode 211a and the negative electrode 211b themselves As a result, the positive electrode 211a and the negative electrode 211b do not need to be stretched or contracted. The battery 250 can be bent.

[0234] In addition, a space 273 is provided between the ends of the positive electrode 211a and the negative electrode 211b and the exterior body 251. By doing so, when the electrode is bent, the ends of the positive electrode 211a and the negative electrode 211b located on the inside are However, the outer casing 251 can be displaced relative to the outer casing 251 without coming into contact with the outer casing 251.

[0235] The battery 250 illustrated in FIGS. 16 and 17 retains its exterior even after repeated bending and stretching. The positive electrode 211a and the negative electrode 211b are less likely to be damaged, and the battery characteristics are less likely to deteriorate. The positive electrode 211a of the battery 250 has the positive electrode active material described in the previous embodiment. By using this material, it is possible to produce a battery with even higher capacity and better cycle characteristics.

[0236] (Fourth embodiment) In this embodiment, an example in which a secondary battery according to one embodiment of the present invention is mounted on an electronic device will be described. do.

[0237] First, as explained in part of the third embodiment, a bendable secondary battery is mounted on an electronic device. Examples are shown in Figures 18(A) to 18(G). For example, television equipment (also called television or television receiver), computers, Computer monitors, digital cameras, digital video cameras, digital photo frames systems, mobile phones (also called mobile phones or mobile phone devices), portable game machines, personal digital assistants, Examples include audio playback devices and large game machines such as pachinko machines.

[0238] In addition, the flexible secondary battery can be mounted on the inner or outer wall of a house or building, or on the inside or outside of a car. It is also possible to incorporate it along the curved surface of the interior or exterior of the vehicle.

[0239] FIG. 18A shows an example of a mobile phone. The mobile phone 7400 has a housing 7401. In addition to the display unit 7402 incorporated in the The mobile phone 7400 is equipped with a speaker 7405, a microphone 7406, etc. The secondary battery 7407 is a secondary battery of one embodiment of the present invention. This makes it possible to provide a lightweight, long-lasting mobile phone.

[0240] FIG. 18B shows the mobile phone 7400 in a bent state. When the entire device is deformed by an external force and curved, the secondary battery inside 7407 is also bent. At this time, the state of the bent secondary battery 7407 is shown in FIG. The secondary battery 7407 is a thin storage battery. The secondary battery 7407 is shown in the bent state. The secondary battery 7407 is fixed in place by a lead wire electrically connected to the current collector 7409. It has a gate electrode.

[0241] FIG. 18(D) shows an example of a bangle-type display device. The portable display device 7100 includes: The device includes a housing 7101, a display unit 7102, operation buttons 7103, and a secondary battery 7104. 18(E) shows the state of the bent secondary battery 7104. The secondary battery 7104 is bent. When the device is worn on the user's arm with the device attached, the housing may deform and cause damage to part of the secondary battery 7104 or The total curvature changes. The degree of curvature at any point on the curve is expressed as the radius of the corresponding circle. The value expressed is the radius of curvature, and the reciprocal of the radius of curvature is called the curvature. Specifically, the radius of curvature is The area is within the range of 40 mm to 150 mm, and the area is part of the main surface of the casing or the secondary battery 7104. The radius of curvature of the main surface of the secondary battery 7104 is 40 mm or more and 150 mm or less. If the thickness is within the range of 1 mm or less, high reliability can be maintained. By using the secondary battery of one embodiment, a lightweight, long-life portable display device can be provided.

[0242] FIG. 18(F) shows an example of a wristwatch-type portable information terminal. The portable information terminal 7200 is , a housing 7201, a display unit 7202, a band 7203, a buckle 7204, and an operation button 72 05, input / output terminal 7206, etc.

[0243] The portable information terminal 7200 is capable of carrying out mobile phone calls, e-mails, viewing and creating documents, playing music, and internet access. - It can run various applications such as internet communication and computer games. do.

[0244] The display surface of the display unit 7202 is curved, and the display is performed along the curved display surface. The display portion 7202 is provided with a touch sensor, and can be touched with a finger or a stylus. For example, the icon 72 displayed on the display unit 7202 can be operated by touching it. You can launch the application by touching 07.

[0245] The operation button 7205 is used to set the time, turn the power on and off, and turn wireless communication on and off. It has various functions such as operation, silent mode activation and deactivation, power saving mode activation and deactivation, etc. For example, an operating system installed in the portable information terminal 7200 can The function of the operation button 7205 can also be freely set using the stem.

[0246] In addition, the mobile information terminal 7200 is capable of performing standardized short-range wireless communication. For example, by communicating with a wireless headset, hands-free operation is possible. You can also make calls.

[0247] The portable information terminal 7200 also has an input / output terminal 7206, and a connector for connecting to other information terminals. Data can be exchanged directly via the input / output terminal 7206. The charging operation can be performed by wireless power supply without going through the input / output terminal 7206. It is also possible.

[0248] 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 inside the housing 7201. Alternatively, it can be incorporated in the band 7203 in a bendable state.

[0249] The mobile information terminal 7200 preferably has a sensor. For example, a fingerprint sensor may be used as the sensor. Human body sensors such as pulse sensors and body temperature sensors, as well as touch sensors, pressure sensors, and acceleration sensors It is preferable that a sensor, etc. be installed.

[0250] FIG. 18G shows an example of a wristband-type display device. The display device 7300 includes a display unit 7 304 and includes the secondary battery of one embodiment of the present invention. The display unit 7304 may be provided with a touch sensor, and may function as a portable information terminal. It is also possible.

[0251] The display surface of the display unit 7304 is curved, and images can be displayed along the curved display surface. The display device 7300 can also communicate with the display device 7300 by short-distance wireless communication according to a communication standard. The situation can be changed.

[0252] The display device 7300 is also equipped with an input / output terminal, and can be directly connected to other information terminals via a connector. It is also possible to charge the device via the input / output terminals. The charging operation may be performed by wireless power supply without using the input / output terminals.

[0253] By using the secondary battery of one embodiment of the present invention as the secondary battery included in the display device 7300, This makes it possible to provide a display device with a long life at a low cost.

[0254] In addition, an example in which the secondary battery with good cycle characteristics shown in the above embodiment is mounted on an electronic device is shown in FIG. 18(H), 19 and 20.

[0255] By using the secondary battery of one embodiment of the present invention as a secondary battery in everyday electronic devices, the battery is lightweight and has a long life. For example, we can provide various products such as electric toothbrushes, electric shavers, and These include mobile beauty devices, and the secondary batteries for these products are designed to be easy for users to hold. Therefore, there is a demand for a small, lightweight, stick-shaped secondary battery with a large capacity.

[0256] FIG. 18(H) is a perspective view of a device also called a tobacco-containing smoking device (electronic cigarette). In 18(H), the electronic cigarette 7500 is an atomizer 7501 containing a heating element and an atomizer A secondary battery 7504 that supplies power to the MYZA, and a cart containing a liquid supply bottle, sensors, etc. To enhance safety, the secondary battery 7504 is protected from overcharging and overcharging. A protection circuit for preventing discharge may be electrically connected to the secondary battery 7504. The secondary battery 7504 has an external terminal so that it can be connected to a charging device. The 504 is the tip when held, so the total length is short and the weight is light. Since the secondary battery of one embodiment of the present invention has a high capacity and good cycle characteristics, We offer a compact and lightweight e-cigarette 7500 that can be used for long periods of time. Can be provided.

[0257] 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 9630 a, a housing 9630b, a movable part 9640 connecting the housings 9630a and 9630b, and a display Part 9631, display mode switch 9626, power switch 9627, power saving mode The display includes a mode changeover switch 9625, a fastener 9629, and an operation switch 9628. By using a flexible panel for the part 9631, a tablet with a wider display area can be manufactured. FIG. 19(A) shows a state in which the tablet terminal 9600 is opened. 19(B) shows the tablet terminal 9600 in a closed state.

[0258] The tablet terminal 9600 also includes a battery storage device inside the housing 9630a and the housing 9630b. The power storage unit 9635 is connected to the housing 9630a through the movable portion 9640. It is located across 9630b.

[0259] A part of the display unit 9631 can be used as a touch panel area, and the user can operate the displayed operation keys. You can input data by touching the screen. You can also switch the keyboard display on the touch panel. By touching the area where the replacement button is displayed with your finger or a stylus, the display 9631 Keyboard buttons can be displayed.

[0260] A display mode changeover switch 9626 changes the display orientation between portrait and landscape. You can select between black and white and color display. The touch 9625 detects when in use by the light sensor built into the tablet terminal 9600. The display brightness can be optimized according to the amount of external light. In addition to optical sensors, other sensors such as gyros and acceleration sensors that detect tilt are also available. The device may be built-in.

[0261] FIG. 19(B) shows the tablet terminal in a closed state, and the tablet terminal includes a housing 9630 and a solar cell 96 33, a charge / discharge control circuit 9634 including a DC / DC converter 9636. The body 9635 is a secondary battery according to one embodiment of the present invention.

[0262] In addition, since the tablet terminal 9600 can be folded in half, when not in use, the housing 9630a and The housing 9630b can be folded so that the housing 9630a and the housing 9630b overlap each other. Since the display portion 9631 can be protected, the durability of the tablet terminal 9600 can be improved. Furthermore, the power storage unit 9635 using the secondary battery of one embodiment of the present invention has a high capacity and a good cycle life. The tablet terminal 9600 has excellent thermal properties, allowing it to be used for extended periods of time. We can provide it.

[0263] In addition, the tablet terminals shown in Figures 19(A) and 19(B) can be used in various Functions that display information (still images, videos, text images, etc.), calendars, dates, or times The function to display information on the display unit, and the function to input or edit the information displayed on the display unit. It has input functions, functions to control processing using various software (programs), etc. It is possible.

[0264] The solar cell 9633 attached to the surface of the tablet terminal supplies power to the touch panel, The solar cell 9633 can be supplied to a display unit, a video signal processor, or the like. The structure can be provided on one or both sides of the power storage unit 9630, and can efficiently charge the power storage unit 9635. It can be concluded that

[0265] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 19(B) are shown in FIG. A block diagram is shown in FIG. 19(C) and will be explained. In FIG. 19(C), a solar cell 9633, a power storage unit 963 5, DC-DC converter 9636, converter 9637, switches SW1 to SW3, table The display unit 9631 is shown, and the storage battery 9635, the DC-DC converter 9636, 19B. This corresponds to 34.

[0266] First, an example of operation when power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell is converted into a voltage for charging the storage battery 9635. The voltage is increased or decreased by a inverter 9636. When power is used from the 9633, switch SW1 is turned on and the converter 9637 The voltage is increased or decreased to the voltage required for the display unit 9631. When not displaying the display, turn SW1 off and SW2 on to charge the power storage unit 9635. The configuration may be such that electricity is supplied.

[0267] The solar cell 9633 is shown as an example of a power generating means, but is not particularly limited thereto. Power storage using other power generation methods such as piezoelectric elements and thermoelectric conversion elements For example, the power may be transmitted and received wirelessly (contactlessly). It is also possible to combine it with a contactless power transmission module that charges the battery, or other charging means. That's fine.

[0268] Another example of electronic equipment is shown in FIG. 20. In FIG. 20, a display device 8000 is a display device according to one embodiment of the present invention. 8 is an example of an electronic device using a secondary battery 8004 according to an embodiment. 8000 corresponds to a display device for receiving TV broadcasts, and includes a housing 8001, a display unit 8002, and a speaker unit. The secondary battery 8004 according to one embodiment of the present invention includes a housing 8003 and a secondary battery 8004. The display device 8000 is provided inside a body 8001. The display device 8000 receives power from a commercial power source. Alternatively, the power stored in the secondary battery 8004 can be used. Even when power cannot be supplied from a commercial power source due to a power outage or the like, the present invention The display device 8000 can be used by using the secondary battery 8004 as an uninterruptible power supply. do.

[0269] The display unit 8002 includes a liquid crystal display device, an emitting device having a light emitting element such as an organic EL element in each pixel, and Device, electrophoretic display device, DMD (Digital Micromirror Device) ce), PDP (Plasma Display Panel), FED (Field A semiconductor display device such as a reflective LED (emission display) can be used.

[0270] In addition to TV broadcast reception, display devices are also used for personal computers and advertising displays. , including all display devices for displaying information.

[0271] In FIG. 20, a stationary lighting device 8100 includes a secondary battery 81 according to one embodiment of the present invention. 8101, a housing 8102, a light source 8103, and a light source 8104. 20, the secondary battery 8103 is mounted in the housing 81. 8101 and a light source 8102 are installed inside a ceiling 8104. However, the secondary battery 8103 may be provided inside the housing 8101. The device 8100 can receive power from a commercial power source or can store power in a secondary battery 8103. Therefore, if the power supply from the commercial power source is interrupted due to a power outage, etc., Even when the power is not available, the secondary battery 8103 according to one embodiment of the present invention can be used as an uninterruptible power supply. This allows the lighting device 8100 to be used.

[0272] 20 illustrates a lighting device 8100 that is a fixed type provided on a ceiling 8104. However, the secondary battery according to one embodiment of the present invention is not limited to the ceiling 8104, but may be installed on other parts such as the side wall 8105 and the floor 8106. 106, it can be used for a fixed lighting device provided in a window 8107, etc., or it can be used for a tabletop lighting device. It can also be used in lighting devices of this type.

[0273] The light source 8102 may be an artificial light source that artificially obtains light using electricity. Specifically, incandescent lamps, fluorescent lamps and other discharge lamps, and light-emitting devices such as LEDs and organic EL elements The element is an example of the artificial light source.

[0274] 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 device 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, and the like. 8 illustrates an example in which the secondary battery 8203 is provided in the indoor unit 8200. The battery 8203 may be provided in the outdoor unit 8204. Both the power supply 8201 and the power supply 8204 may be provided with a secondary battery 8203. The power supply can be supplied from a commercial power source, or the power stored in the secondary battery 8203 can be used. In particular, both the indoor unit 8200 and the outdoor unit 8204 may be equipped with secondary batteries 82 If 03 is installed, when power cannot be supplied from the commercial power source due to a power outage, etc. In addition, by using the secondary battery 8203 of one embodiment of the present invention as an uninterruptible power supply, The conditioner can be used.

[0275] In Figure 20, a separate type air conditioner consisting of an indoor unit and an outdoor unit is shown. As an example, it is an all-in-one air conditioner that has the functions of both the indoor unit and the outdoor unit in a single housing. The secondary battery according to one embodiment of the present invention can also be used in the conditioner.

[0276] 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, a refrigerator It has a storage compartment door 8302, a freezer compartment door 8303, a secondary battery 8304, etc. A secondary battery 8304 is provided inside the housing 8301. The electric refrigerator-freezer 8300 is It can receive power from a commercial power source, or use the power stored in the secondary battery 8304. Therefore, when power cannot be supplied from the commercial power source due to a power outage, etc. However, by using the secondary battery 8304 of one embodiment of the present invention as an uninterruptible power supply, It will be possible to use the 8300-capacity refrigerator.

[0277] In addition, during times when electronic devices are not in use, especially when the total amount of power that can be supplied by the commercial power supplier is low, During the time period when the ratio of the amount of electricity actually used (called the electricity usage rate) is low, By storing power in the battery, it is possible to prevent power usage rates from increasing outside of the above time periods. For example, in the case of the electric refrigerator-freezer 8300, when the temperature is low and the refrigerator compartment door 830 2. During the night when the freezer door 8303 is not opened or closed, the secondary battery 8304 stores power. Then, as the temperature rises, the refrigerator door 8302 and the freezer door 8303 are opened and closed. By using the secondary battery 8304 as an auxiliary power source during the daytime, the daytime power usage rate can be kept low.

[0278] In addition to the electronic devices described above, the secondary battery according to one embodiment of the present invention can be mounted in various electronic devices. According to one embodiment of the present invention, the cycle characteristics of the secondary battery can be improved. According to this aspect, a high-capacity secondary battery can be obtained, and therefore the secondary battery itself can be made small and lightweight. Therefore, the secondary battery according to one embodiment of the present invention can be By incorporating this technology into electronic devices, the electronic devices can be made lighter and have a longer lifespan. The embodiment can be implemented in appropriate combination with other embodiments.

[0279] (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.

[0280] When a secondary battery is installed in a vehicle, it becomes a hybrid vehicle (HEV), an electric vehicle (EV), or a powertrain. This will enable the realization of next-generation clean energy vehicles such as plug-in hybrid vehicles (PHEVs). .

[0281] 21A and 21B illustrate an example of a vehicle using a secondary battery according to one embodiment of the present invention. The automobile 8400 shown in FIG. 1 is an electric automobile that uses an electric motor as a power source for driving. Alternatively, an electric motor and an engine can be selected as the power source for driving. By using one aspect of the present invention, it is possible to extend the driving range. Furthermore, the automobile 8400 has a secondary battery. If many small cylindrical secondary batteries as shown in Figure 5 are lined up on the floor of the car, In addition, a battery pack made up of a combination of multiple secondary batteries as shown in FIG. 14 can be attached to the floor of the vehicle. The secondary battery not only drives the electric motor 8406 but also It can supply power to a light emitting device such as a lamp 8401 or a room light (not shown).

[0282] In addition, the secondary battery is used to power the speedometer, tachometer, and other displays of the automobile 8400. The secondary battery can supply power to the navigation device of the automobile 8400. The present invention can provide power to semiconductor devices such as mobile terminals.

[0283] The automobile 8500 shown in FIG. 21(B) has a secondary battery that is plugged in. It can be charged by receiving power from an external charging facility using a contactless power supply system or other methods. FIG. 21(B) shows a diagram of a charging device 8021 mounted on a ground and a charging station 8022 mounted on a vehicle 8500. The secondary battery 8024 is shown being charged via a cable 8022. For charging methods and connector specifications, please refer to the specified CHAdeMO (registered trademark) or Combo. The charging device 8021 is a charging station installed in a commercial facility. For example, plug-in technology can be used to The secondary battery 8024 installed in the automobile 8500 can be charged by the power supply. Charging is performed by converting AC power to DC power via a converter such as an AC-DC converter. It is possible.

[0284] Although not shown, a power receiving device is mounted on the vehicle and power is supplied contactlessly from a power transmitting device on the ground. In this case, a power transmission device is installed on the road or exterior wall. By incorporating this technology, charging can be carried out not only when the vehicle is stopped but also while the vehicle is moving. This method may be used to transmit and receive power between vehicles. A solar cell may be provided to charge the secondary battery when the vehicle is stopped or running. The power can be supplied by an electromagnetic induction method or a magnetic resonance method.

[0285] 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 (C) has a secondary battery 8602, side mirrors 8601, and a turn signal. The secondary battery 8602 can supply electricity to the direction indicator light 8603. can.

[0286] In addition, the scooter 8600 shown in FIG. 21(C) has a secondary battery 860 in the storage space under the seat 8604. 2 can be stored. The secondary battery 8602 can be stored even if the under-seat storage 8604 is small. The secondary battery 8602 can be stored in the under-seat storage 8604. When charging, the secondary battery 8602 is brought indoors, charged, and stored before driving. Just do that.

[0287] 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 body can be made smaller and lighter, it will contribute to reducing the weight of the vehicle, which will improve the driving range. In addition, the secondary battery installed in the vehicle can also be used as a power supply source for other purposes besides the vehicle. 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 the secondary battery can be used for a long period of time, the amount of rare metals used, including cobalt, can be reduced. It is possible.

[0288] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Example]

[0289] In this example, secondary batteries using positive electrode active materials with different coating layers were fabricated and their characteristics were compared. The results are shown below.

[0290] <Preparation of positive electrode active material> Positive electrode active materials Samples 1 to 5 were prepared. Each sample was prepared by the following method. I passed.

[0291] <Sample 1> Sample 1 has lithium cobalt oxide inside and aluminum and magnesium on the surface. In order to obtain a positive electrode active material having a coating layer containing magnesium and fluorine, The lithium particles are coated with an aluminum layer using the sol-gel method, and then heated. Made.

[0292] Lithium cobalt oxide particles containing magnesium and fluorine, manufactured by Nippon Chemical Industry Co., Ltd. (product name ;C-20F) was used.

[0293] Add 0.0348g of tri-i-propoxyaluminum to 20ml of 2-propanol. The tri-i-propoxyaluminum was dissolved in 2-propanol. 5 g of lithium cobalt oxide particles containing magnesium and fluorine was added.

[0294] This mixture was stirred with a magnetic stirrer for 4 hours at 25°C and 90% RH. This treatment resulted in the hydration of the H2O and tri-i-propoxyaluminum in the atmosphere. Decomposition and polycondensation reactions are carried out to form lithium cobalt oxide particles containing magnesium and fluorine. An aluminum-containing layer was formed on the surface of the substrate.

[0295] The mixed solution after the above treatment was filtered and the residue was collected. (No.4) was used.

[0296] The collected residue was dried under vacuum at 70°C for 1 hour.

[0297] The dried powder was heated to 800°C (heating rate: 200°C / hour) for 2 hours. The reaction was carried out under a dry air atmosphere.

[0298] The heated powder was cooled and crushed by sieving. The sieve used had an opening of 53 μm.

[0299] The particles after the crushing treatment were used as the positive electrode active material of Sample 1.

[0300] <Sample 2> Sample 2 is a comparative example, and has lithium cobalt oxide inside and magnesium on the surface. In order to obtain a positive electrode active material having a coating layer containing magnesium and fluorine, It was produced by heating lithium particles.

[0301] Lithium cobalt oxide particles containing magnesium and fluorine were manufactured by Nippon Chemical Industry Co., Ltd. (product name: C -20F) was used.

[0302] The lithium cobalt oxide particles containing magnesium and fluorine were heated. The heating was carried out at 200°C (heating rate: 200°C / hour), for a holding time of 2 hours, in an oxygen atmosphere.

[0303] The heated powder was cooled and sieved through a 53 μm mesh sieve. The quality was high.

[0304] <Sample 3> Sample 3 is a comparative example of lithium cobalt oxide containing magnesium and fluorine. In order to obtain a positive electrode active material in which magnesium is not sufficiently segregated in the surface layer, The lithium cobalt oxide particles containing fluorine were used as they were without heating.

[0305] Lithium cobalt oxide particles containing magnesium and fluorine were manufactured by Nippon Chemical Industry Co., Ltd. (product name: C -20F) was used.

[0306] <Sample 4> Sample 4 is a comparative example, and has lithium cobalt oxide inside and aluminum on the surface. In order to obtain a positive electrode active material having a coating layer containing magnesium, lithium cobalt oxide containing no magnesium is used. The aluminum particles were coated with an aluminum-containing coating layer by the sol-gel method and then heated. .

[0307] As magnesium-free lithium cobalt oxide particles, Nippon Chemical Industry Co., Ltd. (product name: C- This is because magnesium was not detected by XPS and fluorine was detected at about 1 atomic %. The lithium cobalt oxide particles are produced.

[0308] The lithium cobalt oxide particles were treated with aluminum by the sol-gel method in the same way as Sample 1. A coating layer containing cellulose was formed, heated, dried, and sieved. It was made into a substance.

[0309] <Sample 5> Sample 5 is a comparative example in which magnesium is used as a positive electrode active material without a coating layer. Lithium cobalt oxide particles without the coating were used as they were without heating.

[0310] As magnesium-free lithium cobalt oxide particles, Nippon Chemical Industry Co., Ltd. (product name: C- 10N) was used.

[0311] The conditions for Samples 1 to 5 are shown in Table 1.

[0312] [Table 1]

[0313] <Cycle characteristics> Using the positive electrode active materials of Samples 1 to 5 prepared above, CR2032 type ( A coin-type secondary battery (20 mm diameter, 3.2 mm height) was fabricated and its cycle characteristics were evaluated. .

[0314] The positive electrode consisted of the positive electrode active material (LiCoO2) of Samples 1 to 5 and acetylene black. LiCoO2 (AB) and polyvinylidene fluoride (PVDF) were mixed in a ratio of LiCoO2:AB:PVDF=9. The slurry mixed at a weight ratio of 5:2.5:2.5 was applied to an aluminum foil current collector. We used the following.

[0315] The counter electrode was made of lithium metal.

[0316] The electrolyte used in the electrolytic solution is 1 mol / L lithium hexafluorophosphate (LiPF6). The electrolyte contains ethylene carbonate (EC) and diethyl carbonate (DEC). C:DEC = 3:7 (volume ratio) mixed, and vinylene carbonate (VC) was added. The material used was one containing 100% by weight of cellulose acetate.

[0317] The positive electrode can and the negative electrode can were made of stainless steel (SUS).

[0318] The measurement temperature for the cycle characteristic test was 25°C. Charging was performed at a current density of 68 per unit weight of active material. The current density is then increased to 1.4mA / g at a constant current of 0.5mA / g and an upper voltage limit of 4.6V. The battery was charged at a constant voltage up to 1000 kJ / g. The current was measured at a lower limit voltage of 2.5V.

[0319] 22(A) and 22(B) show secondary battery samples using the positive electrode active materials of Samples 1 to 5. The graphs of the battery cycle characteristics are shown in Figure 22(A) and (B). FIG. 22(B) is a graph showing the energy density maintenance rate when charged to 4.6V. The energy density is the product of the discharge capacity and the average discharge voltage. The density was calculated assuming the peak top as 100%.

[0320] As is clear from Fig. 22(A) and Fig. 22(B), the lithium cobalt oxide without a coating layer Compared with Sample 5, which is made of aluminum, Sample 6 is made of a positive electrode active material having a coating layer containing aluminum. Sample 4 exhibited slightly better cycle characteristics.

[0321] In addition, sample 2, which is lithium cobalt oxide particles containing magnesium and fluorine, and sample In the comparison of sample 3, sample 2, which was heated, showed a higher solubility than sample 3, which was not heated. The cycle characteristics were also significantly improved. This is because magnesium is converted into lithium cobalt oxide by heating. This is thought to be the effect of segregation at the surface of the aluminum particles.

[0322] In addition, lithium cobalt oxide particles containing magnesium and fluorine are coated with a coating containing aluminum. Sample 1, which is a positive electrode active material having a coating layer formed thereon, exhibited extremely good cycle characteristics. These are sample 2, in which magnesium is segregated in the surface layer, and sample 3, in which the coating layer contains aluminum. The properties were superior to those of Sample 4, which was formed by aluminum and magnesium. By providing a coating layer containing aluminum, it is possible to form a coating layer containing only aluminum or magnesium. It is clear that better cycle characteristics can be obtained than when only the coating layer is provided. It was. [Example]

[0323] In this example, lithium cobalt oxide particles having a coating layer containing aluminum and magnesium were used. The characteristics of the children were revealed through various analyses.

[0324] <xps> Samples 1, 2, and 3 of Example 1 were subjected to XPS analysis from the surface. In addition, the particles of Sample 1 in Example 1 were subjected to the sol-gel treatment and drying, but before heating. The results are shown in Table 2. Some points have been rounded to the nearest second, so the total may not add up to 100%.

[0325] [Table 2]

[0326] In addition, using the results in Table 2, lithium, aluminum, cobalt, magnesium, oxygen, Table 3 shows the atomic ratio calculated assuming the total amount of fluorine is 100 atomic %.

[0327] [Table 3]

[0328] XPS analysis can quantitatively analyze the area from the surface of the positive electrode active material to about 5 nm. As shown in the figure, in the samples 1 and 2, which are the positive electrode active materials that were heated, The atomic ratio of magnesium was significantly increased compared to Sample 6 and Sample 3, which were not subjected to annealing. In other words, it was clear that heating caused magnesium to segregate in the region about 5 nm from the surface. It became clear.

[0329] In addition, Sample 1 and Sample 6 were prepared by forming a coating layer containing aluminum by the sol-gel method. In this case, sample 1, which was heated, has more aluminum than sample 6, which was not heated. Therefore, by heating, the atomic ratio of the surface to the silicon was small. It was presumed that aluminum had diffused.

[0330] Therefore, in the case of Sample 1, which has a coating layer containing aluminum and magnesium, There is a lot of magnesium in the area, and aluminum is present in a deeper region than magnesium. It was inferred that this was the case.

[0331] <stem-fft> Next, the results of STEM observation and FFT analysis of Sample 1 are shown in Figure 23. and shown in FIG.

[0332] 23(A) to 23(C) are bright-field ST images of a cross section near the surface of the positive electrode active material of Sample 1. In Fig. 23(C), the surface layer of the positive electrode active material particle is covered with what is presumed to be magnesium. It can be seen that there are elements that are observed to be brighter than others. As far as could be observed, it was also observed that the crystal orientation was roughly consistent from the interior to the surface. .

[0333] FIG. 24(A-1) is a HAADF-STEM image of a cross section near the surface of the positive electrode active material of Sample 1. The FFT (Fast Fourier Transform) image of the area indicated by FFT1 in FIG. 24(A-1) is shown. 24(A-2). Some of the bright spots in the FFT image of Fig. 24(A-2) are shown in Fig. 24(A-3). We have decided to call them A, B, C, and O as shown.

[0334] For the bright spots in the FFT image of the area shown in FFT1, the actual measured values ​​are OA and d=0.2 5nm, OB d=0.16nm, OC d=0.26nm. Also, ∠AOB=3 7°, ∠BOC=36°, ∠AOC=73°.

[0335] This is the ICDD (International Centre for Diffraction Magnesium oxide (MgO) data in the I CDD45-0945), and data for cobalt oxide (CoO) (ICDD48-17 19) is close to the distance and angle obtained from

[0336] In the case of magnesium oxide, OA(1-11) has d = 0.24 nm, and OB(0-22) has d =0.15nm, OC(-1-11) is d=0.24nm, ∠AOB=35°, ∠BOC =35°, ∠AOC=71°.

[0337] In the case of cobalt oxide, OA(1-11) has d = 0.25 nm, and OB(0-22) has d =0.15nm, OC(-1-11) is d=0.25nm, ∠AOB=35°, ∠BOC =35°, ∠AOC=71°.

[0338] Therefore, the region of about 2 nm from the surface of the positive electrode active material particle shown in FFT1 is composed of rock salt type crystals. It was found that the FF region has a crystal structure and is an image of the

[0011] incident light. The area marked T1 has magnesium oxide or cobalt oxide, or It was inferred that the material contained both cobalt and cobalt oxide.

[0339] FIG. 24(B-1) shows the HAADF- of the cross section near the surface of the same positive electrode active material as FIG. 24(A-1). The FFT image of the region indicated by FFT2 in Figure 24(B-1) is shown in Figure 24(B Some of the bright spots in the FFT image of Figure 24(B-2) are shown in Figure 24(B-3). We decided to call them A, B, C, and O.

[0340] For the bright spots in the FFT image of the area shown in FFT2, the actual measured values ​​are OA and d=0.5 1 nm, OB was d=0.21 nm, and OC was d=0.25 nm. Also, ∠AOB=5 5°, ∠BOC=24°, ∠AOC=79°.

[0341] This is the data for lithium cobalt oxide (LiCoO2) in the ICDD database ( ICDD50-0653), and LiAl 0.2 Co 0.8 data of O2 (ICDD8 9-0912) are close to the distances and angles obtained therefrom.

[0342] In the case of lithium cobalt oxide (LiCoO2), OA(003) has d = 0.47 nm, OB (104) has d = 0.20 nm, OC(101) has d = 0.24 nm, ∠AOB = 55° , ∠BOC = 25°, ∠AOC = 80°.

[0343] LiAl 0.2 Co 0.8 In the case of O2, OA(003) has d = 0.47 nm, OB(10 4) has d = 0.20 nm, OC(101) has d = 0.24 nm, ∠AOB = 55°, ∠B OC = 25°, ∠AOC = 80°.

[0344] Therefore, the region from 3 nm deeper to about 6 nm from the surface of the cathode active material shown by FFT2 is a region having the same layered rock salt-type crystal structure as that of lithium cobalt oxide and LiAl 0.2 Co 0.8 O2, and it was revealed that it is an image of [0-10] incidence.

[0345] <STEM-EDX (Element Mapping, Line Analysis)> Next, regarding the results of EDX analysis of Sample 1, they are shown in FIGS. 25 and 26 .

[0346] FIG. 25 is the STEM-EDX analysis result of a cross section near the surface of the cathode active material of Sample 1. FIG. 25(A-1) is a HAADF-STEM image, FIG. 25(A-2) is the element mapping of cobalt , FIG. 25(B-1) is the element mapping of aluminum, FIG. 25(B-... Figure 25(C) shows the elemental mapping of fluorine.

[0347] As shown in FIG. 25(B-1), aluminum is present in a region of about 10 nm from the surface of the positive electrode active material. As shown in Figure 25(B-2), magnesium It was observed that the particles were segregated in a region about 3 nm from the surface of the positive electrode active material. As shown in Fig. 5(C), almost no fluorine was detected near the surface, which is due to the EDX analysis. This is thought to be because fluorine, a light element, is difficult to detect.

[0348] Figure 26 shows the results of STEM-EDX analysis of a cross section near the surface of the positive electrode active material of Sample 1. Figure 26(A) is a HAADF-STEM image. The area surrounded by the white line in Figure 26(A) The graph showing the results of EDX analysis in the direction of the white arrow is shown in Figure 26(B). FIG. 26(C) is a graph showing a part of FIG. 26(B) enlarged. However, almost no fluorine was detected.

[0349] As shown in FIG. 26(C), magnesium and aluminum were present near the surface of the positive electrode active material of Sample 1. The distribution of magnesium is closer to the surface than the distribution of aluminum. It was also revealed that the magnesium peak was more prominent than the aluminum peak. It was also revealed that cobalt and oxygen exist from the outermost surface of the positive electrode active material particles. It was assumed to exist.

[0350] From the results of the XPS and EDX analyses described above, it can be seen that Sample 1 is a first embodiment of the present invention. The first region is made of lithium cobalt oxide, and the second region is made of lithium and aluminum. , cobalt, and oxygen as a third region, and a positive region having magnesium and oxygen as a third region. It was confirmed that the electrode active material was a part of the second region and the third region in Sample 1. It was revealed that some of the

[0351] In addition, in the graph of FIG. 26(B), the amount of oxygen detected is stable at a distance of 11 nm or more. The average amount of oxygen detected in this stable region is O ave Calculate the average value O ave 50% of The value of 0.5O ave The distance x of the measurement point that showed the closest measurement value to the particle of the positive electrode active material is It was assumed to be the outermost surface.

[0352] In this example, the average O detected amount of oxygen in the distance range of 11 nm to 40 nm is ave The measurement point that showed the closest measurement value to 388.5, which is 50% of 777, was 777. The x-axis is the distance 9.5 nm. It was estimated that the distance of 9.5 nm was the outermost surface of the particles of the positive electrode active material.

[0353] If the distance to the outermost surface of the positive electrode active material particle is 9.5 nm, the magnesium peak is The aluminum peak was 2.3 nm from the outermost surface.

[0354] From the results of the above-mentioned Examples 1 and 2, it is clear that the first region 101 and the second region 102 are one aspect of the present invention. The second region 102 includes lithium and aluminum. The third region 103 includes cobalt and oxygen, and the third region 104 includes magnesium and oxygen. It has been revealed that the positive electrode active material obtained by this method has excellent cycle characteristics when used in secondary batteries. It became like this. [Explanation of symbols]

[0355] 100 Cathode active material 101 First Area 102 Second Area 103 The Third Region 104 The Fourth Realm 200 Active material layer 201 Graphene Compounds 211a positive electrode 211b negative electrode 212a Lead 212b Lead 214 Separator 215a Joint 215b Joint 217 Fixing member 250 batteries 251 Exterior body 261 Bending part 262 Seal part 263 Seal part 271 Ridgeline 272 Valley Line 273 Space 300 Secondary battery 301 Positive electrode can 302 Anode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode 308 Negative electrode current collector 309 Negative electrode active material layer 310 Separator 500 secondary battery 501 Positive electrode current collector 502 Positive electrode active material layer 503 Positive electrode 504 Negative electrode current collector 505 Negative electrode active material layer 506 negative electrode 507 Separator 508 Electrolyte 509 Exterior body 510 Positive lead electrode 511 Negative lead electrode 600 Secondary battery 601 Positive electrode cap 602 Battery can 603 Positive terminal 604 Positive electrode 605 Separator 606 negative electrode 607 Negative terminal 608 Insulating plate 609 Insulating board 611 PTC element 612 Safety valve mechanism 900 Circuit Board 910 Label 911 terminal 912 circuits 913 Secondary battery 914 Antenna 915 Antenna 916 layers 917 layers 918 Antenna 919 terminal 920 Display device 921 Sensor 922 terminal 930 chassis 930a housing 930b housing 931 negative electrode 932 Positive electrode 933 Separator 950 Wound body 951 terminal 952 terminals 980 Secondary battery 981 Film 982 Film 993 Wound body 994 negative electrode 995 positive electrode 996 Separator 997 Lead Electrode 998 Lead electrode 7100 Portable display devices 7101 Housing 7102 Display section 7103 Operation button 7104 Secondary battery 7200 Personal Digital Assistant 7201 Case 7202 Display section 7203 Band 7204 Buckle 7205 Operation button 7206 Input / output terminal 7207 Icon 7300 display device 7304 Display section 7400 mobile phone 7401 Housing 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 7407 Secondary battery 7409 Current collector 7500 e-cigarettes 7501 Atomizer 7502 Cartridge 7504 Secondary battery 8000 display device 8001 Case 8002 Display section 8003 Speaker section 8004 Secondary battery 8021 Charging device 8022 cable 8024 Secondary battery 8100 Lighting equipment 8101 Housing 8102 Light source 8103 Secondary battery 8104 Ceiling 8105 Side wall 8106 beds 8107 Window 8200 indoor unit 8201 Housing 8202 Ventilation outlet 8203 Secondary battery 8204 Outdoor unit 8300 Electric refrigerator-freezer 8301 Housing 8302 Refrigerator door 8303 Freezer door 8304 Secondary battery 8400 Automobiles 8401 Headlight 8406 Electric motor 8500 cars 8600 Scooter 8601 Side mirror 8602 Secondary battery 8603 Turn signal light 8604 Under-seat storage 9600 tablet device 9625 Switch 9626 Switch 9627 Power Switch 9628 Operation Switch 9629 Fasteners 9630 chassis 9630a housing 9630b housing 9631 Display section 9633 Solar Cells 9634 Charge / Discharge Control Circuit 9635 Electricity storage unit 9636 DC / DC Converter 9637 Converter 9640 Moving parts < / xps>

Claims

1. dissolving an aluminum alkoxide in an alcohol; a step of mixing composite oxide particles containing lithium, a transition metal, magnesium, oxygen, and fluorine with an alcohol solution of aluminum alkoxide in which the aluminum alkoxide is dissolved in the alcohol to obtain a mixed solution; a step of stirring the mixture in an atmosphere containing water vapor; recovering a precipitate from the mixture; a step of heating the recovered precipitate in an oxygen-containing atmosphere at 700°C or higher and 1000°C or lower for a holding time of 50 hours or shorter to obtain a powder; cooling the powder and subjecting it to a crushing treatment; The method for producing a positive electrode active material includes the steps of:

2. In claim 1, The heating causes magnesium and fluorine to segregate on the surfaces of the powders. A method for producing a positive electrode active material.

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