Method for manufacturing positive electrode active material

Abstract

To provide a positive electrode active material having a large charge-discharge capacity, or to provide a positive electrode active material having a high charge-discharge voltage, or to provide a positive electrode active material exhibiting less degradation, or to provide a novel positive electrode active material.SOLUTION: To suppress the occurrence of defects, the surface of positive electrode active material particles is modified or coated by adding zirconium (Zr), titanium (Ti), hafnium (Hf), yttrium (Y), to the positive electrode active material particles. Ideally, a barrier film containing at least one of Zr, Ti, Hf, and Y is provided around the positive electrode active material particles, and it is preferable that the barrier film be a functional film capable of allowing lithium ions to pass through while suppressing the elution of metals such as cobalt from the inside of the positive electrode active material particles.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a secondary battery using a positive electrode active material and a method for manufacturing the same. Regarding information terminals, vehicles, etc.

[0002] 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, an electronic device, Or it relates to a method for producing them.

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

[0004] In this specification, the term "power storage device" refers to elements and devices in general that have a power storage function. For example, a storage battery (also called a secondary battery) such as a lithium-ion secondary battery, This includes lithium ion capacitors and electric double layer capacitors. [Background technology]

[0005] In recent years, lithium-ion secondary batteries, lithium-ion capacitors, air batteries, all-solid-state batteries, etc. The development of various types of energy storage devices is actively underway, especially lithium-ion batteries, which have high output and capacity. Demand for secondary batteries has rapidly expanded along with the development of the semiconductor industry, and the number of rechargeable energy sources has increased. As a source of supply, it has become an indispensable part of the modern information society.

[0006] It is also a positive electrode active material for lithium-ion secondary batteries, which has high capacity and excellent charge-discharge cycle characteristics. As a method for producing the lithium cobalt oxide, lithium fluoride and chromium fluoride are synthesized. Research is being conducted into a technology in which magnesium is added, mixed, and heated (Patent Document 1).

[0007] Furthermore, research into the crystal structure of positive electrode active materials is also being conducted (Non-Patent Documents 1 and 2). Reference 3) In addition, the physical properties of fluorides such as fluorite (calcium fluoride) have been studied for a long time. In addition, the ICSD (Inorganic Semiconductor Device) introduced in Non-Patent Document 5 is By using the Crystal Structure Database, Research is being conducted to analyze the crystal structure of positive electrode active materials using X-ray diffraction (XRD). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2019-179758 [Non-patent literature]

[0009] [Non-Patent Document 1] Toyoki Okumura et al, “Correlation of lithium ion distribution and X-ray absorption near-edge structure in O3-and O2-lithium cobalt oxides from first-principle calculation”, Journal of Materials Chemistry, 2012, 22, p.17340-17348 [Non-patent document 2] Motohashi, T. et al, “Electronic phase diagram of the layered cobalt oxide system LixCoO2(0.0≦x≦1.0)”, Physical Review B, 80(16) ,2009, 165114 [Non-patent document 3] Zhaohui Chen et al, “Staging Phase Transitions in LixCoO2”, Journal of The Electrochemical Society, 2002, 149(12) A1604-A1609 [Non-patent document 4] WE Counts et al, Journal of the American Ceramic Society, 1953, 36[1] 12-17. Fig.01471 [Non-Patent Document 5] Belsky, A. et al., “New developments in the Inorganic Crystal Structure Database (ICSD): accessibility in support of materials research and design”, Acta Cryst., 2002, B58 364-369. Summary of the Invention [Problem to be solved by the invention]

[0010] The characteristics required for energy storage devices include safety in various operating environments and improved long-term reliability. etc.

[0011] Secondary batteries used in electric and hybrid vehicles are designed to be used for a long period of time. Therefore, it is desirable for the battery to have sufficient reliability. The secondary battery used is required to have high voltage and heat resistance.

[0012] Furthermore, it is also desirable to be able to charge the secondary battery quickly in order to shorten the charging time. do.

[0013] An object of one embodiment of the present invention is to provide a positive electrode active material with high charge / discharge capacity.

[0014] Another object is to provide a positive electrode active material having a high charge / discharge voltage. The object of the present invention is to provide a positive electrode active material with less oxidative stress. Alternatively, the object of the present invention is to provide a novel positive electrode active material. The following are the challenges.

[0015] Another object is to provide a secondary battery with a large charge / discharge capacity. One of the objectives is to provide a secondary battery with high voltage. Another object of the present invention is to provide a secondary battery with low deterioration. Another object is to provide a secondary battery with a long life. Another object is to provide a novel secondary battery.

[0016] Alternatively, one aspect of the present invention is a secondary battery that can be used in a wide temperature range and is not easily affected by the environmental temperature. One of the challenges is to provide a battery.

[0017] Another embodiment of the present invention is to provide a novel substance, an active material, a power storage device, or a manufacturing method thereof. One of the challenges is to

[0018] 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]

[0019] Charging and discharging at high voltages of 4.5V or higher or at high temperatures (45°C or higher) can cause In some cases, defects (also called pits) may occur in the positive electrode active material particles. The expansion and contraction of the positive electrode active material particles can cause defects such as cracks. In some cases, this may be the case.

[0020] To prevent such defects, the positive electrode active material particles contain zirconium (Zr) and titanium. (Ti), hafnium (Hf), yttrium (Y), etc. are added to the positive electrode active material particles. The surface of the positive electrode active material particles is modified or coated. Ideally, a barrier film (Z The barrier film contains one of r, Ti, Hf, and Y, and the barrier film does not allow lithium ions to pass through. This allows the film to function as a functional film that suppresses the elution of metals such as cobalt from inside the positive electrode active material particles. It is not limited to forming a coating film on the entire surface of the particles, but it is also preferable to form a coating film on the entire surface of the particles so that the metal element does not dissolve. A barrier film may be provided on a part of the region that is susceptible to the influence of the ultraviolet rays so as to block the region.

[0021] Such a barrier film is preferably strong enough to withstand high charge / discharge voltages. The heating temperature can be increased stepwise or gradually to obtain crystalline It is preferable to have a high film thickness.

[0022] In addition, after adding fluorine or a metal element (magnesium) to the positive electrode active material particles, A barrier layer may be formed on the surface of the positive electrode active material particles by heat treatment. The shell is the barrier layer, and the core is the positive electrode. If we consider it as an active material particle, it can be said to have a core-shell structure. It allows cobalt ions to pass through, preventing the elution of metals such as cobalt from inside the positive electrode active material particles. In this specification, when the positive electrode active material is formed on the outermost surface of the positive electrode active material particle, is called a barrier film, and when it is formed below the outermost surface of the positive electrode active material particles, that is, in the depth direction, it is called a barrier film. It will be called a layer.

[0023] Barrier film or layer prevents various defects (such as pits or cracks) from occurring This improves the safety and reliability of the secondary battery.

[0024] The positive electrode active material of lithium-ion secondary batteries is typically LCO or NCM, which are made up of multiple metals. It can also be said to be an alloy containing elements (cobalt, nickel, etc.). At least one of the positive electrodes has a defect, and the defect may change before and after charging and discharging. When the material particles are used in a secondary battery, they are absorbed by the environmental material (electrolyte solution) surrounding the positive electrode active material particles. The phenomenon of material deterioration or chemical or electrochemical corrosion caused by This deterioration does not occur uniformly on the particle surface, but is concentrated locally. Repeated charging and discharging of a secondary battery can cause defects to form deep inside the battery, for example. Jiru.

[0025] Pitting corrosion is a phenomenon in which defects progress in the particles of positive electrode active material, forming holes. The holes that occur due to this phenomenon are also called pits in this specification. Call.

[0026] In this specification, cracks and pits are different. Cracks are formed immediately after the production of the positive electrode active material particles. Even if it exists, there is no pit. A pit can be said to be a hole where several layers of cobalt and oxygen have escaped, or a place where cobalt has eluted, when charging and discharging under high voltage conditions of 4.5 V or higher or high temperature (45 °C or higher). Cracks refer to new surfaces generated by the application of physical pressure, or cracks caused by grain boundaries. Cracks may also occur due to the expansion and contraction of particles during charging and discharging. In addition, pits may occur from cracks or cavities within particles. Figure 35(C) shows an example of a pit. Figure 35(A) is a top view of the FIB-SEM image of the positive electrode active material particles after disassembling the secondary battery cell after 50 cycles of a cycle test at a charging voltage of 4.7 V. The cross-sectional view of the broken line part in Figure 35(A) is Figure 35(B), and the enlarged view of the part surrounded by the square frame in Figure 3 5(B) is Figure 35(C). The pits 90a, 90b, and 90c indicated by the arrows in Figure 35(C) are shown. By adding Zr, Ti, Hf, Y, etc. to the positive electrode active material particles, the generation of pits during charging and discharging under high voltage conditions or high temperature can be suppressed.

[0027] [[ID=***18]] 5(B) is Figure 35(C). The pits 90a, 90b, and 90c indicated by the arrows in Figure 35(C) are shown.

[0028] By adding Zr, Ti, Hf, Y, etc. to the positive electrode active material particles, the generation of pits during charging and discharging under high voltage conditions or high temperature can be suppressed.

[0029] <Observation using SEM> By repeating cross-section processing with FIB and SEM observation, three-dimensional information on the structure can be obtained. Such an observation method is sometimes called Slice and View. [[ID=***39]]

[0030] The configuration of the invention related to the method for manufacturing a secondary battery disclosed in this specification includes a first step of producing a first mixture in which a first material, a second material and a third material are mixed, and the first mixture It seems there is a duplicate or incorrect tag in the original text which might cause some confusion in the translation. The text with the tag ` ` and the repeated ` ` and the incorrect ` ` might need to be double-checked in the original source for accuracy. The translation is done based on the best understanding of the text as presented.a second step of heating the mixture to form a second mixture, and a fourth material being mixed with the second mixture; a third step of preparing a third mixture containing the fifth material and the sixth material; a fourth step of preparing a fourth mixture in which the above materials are mixed; and a fifth step of heating the mixture at a temperature of 100°C to prepare a fifth mixture, and then crushing the fifth mixture. The crushed fifth mixture is heated under a temperature condition higher than the first temperature condition, and the sixth mixture is and a sixth step of fabricating the second step, the fifth step, and the sixth step. In the first step, the heating is carried out in an atmosphere with oxygen, and in the second step, the heating is carried out in an atmosphere with oxygen. The temperature range is 00°C to 950°C, and the time is 1 hour to 100 hours. The temperature condition of 1 is a temperature range of 350°C or more and less than 600°C, and for 1 hour or more and 100 hours or less. The second temperature condition is a temperature range of 600°C to 900°C for 1 hour. The method for producing a positive electrode active material is carried out for a period of not less than 100 hours.

[0031] In the above structure, the first material is a halogen compound containing an alkali metal, and the second material is a halogen compound containing an alkali metal. The material comprises magnesium, and the third material comprises an alkali metal and cobalt. The fourth material is an oxide, the fifth material is nickel, and the fifth material is aluminum.

[0032] In the above configuration, the sixth material is zirconium (Zr), titanium (Ti), or hafnium. It is preferable that the alloy contains one or more of hafnium (Hf), yttrium (Y), In particular, it is more desirable to have zirconium.

[0033] The above-mentioned manufacturing method is a method for manufacturing a positive electrode active material by heating under a first temperature condition. The second temperature condition causes crystal growth, and the second temperature condition causes the surface, near-surface, or A method for producing a secondary battery in which a barrier film containing crystals is provided on all or part of the surface layer. It can also be said that. [Effects of the Invention]

[0034] According to one aspect of the present invention, the occurrence of defects (such as pits or cracks) can be suppressed. According to one aspect of the present invention, a positive electrode active material having a high energy density and a large charge / discharge capacity is provided. Alternatively, a material having high energy density and high charge / discharge voltage can be provided. Alternatively, it is possible to provide a positive electrode active material that is less likely to deteriorate. Alternatively, a new positive electrode active material can be provided. Alternatively, a large charge / discharge capacity can be achieved. Alternatively, it is possible to provide a secondary battery with a high charge / discharge voltage. It is also possible to provide a secondary battery with high safety and reliability. This makes it possible to provide a secondary battery with little deterioration, or to provide a secondary battery with a long life. Alternatively, a novel secondary battery can be provided.

[0035] According to one embodiment of the present invention, a novel substance, an active material, a power storage device, or a manufacturing method thereof is provided. It can be provided.

[0036] The description of these effects does not preclude the existence of other effects. The embodiment does not necessarily have to have all of these effects. , the specification, drawings, claims, etc., and It is possible to extract other effects from the claims and other descriptions. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 1 is a diagram illustrating a method for producing a positive electrode active material. [Figure 2] FIG. 2 is a diagram illustrating a method for producing a positive electrode active material. [Figure 3] FIG. 3 is a diagram illustrating a method for producing a positive electrode active material. [Figure 4] FIG. 4 shows an example of an SEM image of the positive electrode active material. [Figure 5] FIG. 5 is an example of an SEM image of the positive electrode active material. [Figure 6] FIG. 6 is an example of an SEM image of the positive electrode active material. [Figure 7] FIG. 7 is an example of an SEM image of the positive electrode active material. [Figure 8] FIG. 8 is a diagram illustrating the depth of charge and the crystal structure of a positive electrode active material according to one embodiment of the present invention. [Figure 9] FIG. 9 shows the XRD pattern calculated from the crystal structure. [Figure 10] FIG. 10 is a diagram illustrating the state of charge and the crystal structure of the positive electrode active material of the comparative example. [Figure 11] FIG. 11 shows the XRD pattern calculated from the crystal structure. [Figure 12] 12A to 12D are cross-sectional views illustrating examples of the positive electrode of a secondary battery. [Figure 13] FIG. 13(A) is an exploded perspective view of a coin-type secondary battery, FIG. 13(B) is a perspective view of the coin-type secondary battery, and FIG. 13(C) is a cross-sectional perspective view thereof. [Figure 14] Fig. 14(A) shows an example of a cylindrical secondary battery. Fig. 14(B) shows an example of a cylindrical secondary battery. Fig. 14(C) shows an example of multiple cylindrical secondary batteries. Fig. 14(D) shows an example of a power storage system having multiple cylindrical secondary batteries. [Figure 15] 15(A) and 15(B) are diagrams for explaining an example of a secondary battery, and FIG. 15(C) is a diagram showing the inside of the secondary battery. [Figure 16]16A to 16C are diagrams illustrating examples of secondary batteries. [Figure 17] 17(A), 17(B), and 17(C) are diagrams showing the external appearance of the secondary battery. [Figure 18] 18A to 18C are diagrams illustrating a method for manufacturing a secondary battery. [Figure 19] FIG. 19 is a top view showing an example of a secondary battery manufacturing apparatus. [Figure 20] FIG. 20 is a cross-sectional view showing an example of a method for producing a secondary battery. [Figure 21] 21(A) to 21(C) are perspective views showing an example of a method for manufacturing a secondary battery, and Fig. 21(D) is a cross-sectional view corresponding to Fig. 21(C). [Figure 22] 22A to 22F are perspective views showing an example of a method for manufacturing a secondary battery. [Figure 23] FIG. 23(A) shows an example of the configuration of a battery pack, FIG. 23(B) shows an example of the configuration of a battery pack, and FIG. 23(C) shows an example of the configuration of a battery pack. [Figure 24] 24(A) and (B) are diagrams illustrating an example of a secondary battery. [Figure 25] 25(A) to 25(C) are diagrams illustrating examples of secondary batteries. [Figure 26] 26(A) and (B) are diagrams illustrating an example of a secondary battery. [Figure 27] FIG. 27(A) is a perspective view of a battery pack showing one embodiment of the present invention, FIG. 27(B) is a block diagram of the battery pack, and FIG. 27(C) is a block diagram of a vehicle having a motor. [Figure 28] 28(A) to 28(D) are diagrams illustrating an example of a transportation vehicle. [Figure 29] 29A and 29B illustrate a power storage device according to one embodiment of the present invention. [Figure 30] FIG. 30(A) is a diagram showing an electric bicycle, FIG. 30(B) is a diagram showing a secondary battery for the electric bicycle, and FIG. 30(C) is a diagram explaining an electric motorcycle. [Figure 31] 31A to 31D are diagrams illustrating examples of electronic devices. [Figure 32] FIG. 32(A) shows an example of a wearable device, FIG. 32(B) shows a perspective view of a wristwatch-type device, and FIG. 32(C) is a diagram illustrating a side view of the wristwatch-type device. [Figure 33] FIG. 33 shows the cycle characteristics of the secondary battery. [Figure 34] 34(A) and (B) are SEM images of the positive electrode. [Figure 35] 35(A) to (C) are SEM images of the positive electrode. [Figure 36] 36(A) to (C) are SEM images of the positive electrode. [Figure 37] 37(A) to (C) are SEM images of the positive electrode. [Figure 38] 38(A) to (C) are SEM images of the positive electrode. [Figure 39] Figures 39(A) to (C) are STEM images of the positive electrode. [Figure 40] Figures 40(A) and (B) are STEM images of the positive electrode. [Figure 41] 41(A) to 41(C) show the results of EDX analysis of the positive electrode. DETAILED DESCRIPTION OF THE INVENTION

[0038] 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.

[0039] A secondary battery has, for example, a positive electrode and a negative electrode. The material that constitutes the positive electrode is a positive electrode active material. The positive electrode active material is, for example, a material that undergoes a reaction that contributes to the charge / discharge capacity. The substance may partially contain a substance that does not contribute to the charge / discharge capacity.

[0040] In this specification and the like, the positive electrode active material of one embodiment of the present invention is a positive electrode material or a positive electrode material for a secondary battery. In this specification and the like, the term "electrode material" refers to an embodiment of the present invention. It is preferable that the positive electrode active material of the present invention has a compound. The positive electrode active material of one embodiment preferably has a composition. The positive electrode active material of one embodiment preferably includes a composite.

[0041] In this specification, segregation refers to the phenomenon in a solid consisting of multiple elements (e.g., A, B, C). This refers to the phenomenon in which a certain element (e.g., B) is distributed spatially non-uniformly.

[0042] In this specification, the surface layer of a particle of an active material or the like refers to, for example, a layer extending from the surface to the inside by 50 nm or less, more preferably 35 nm or less, even more preferably 20 nm or less, and most preferably The area is within 10 nm. Surfaces that are created by cracks or fractures can also be considered surfaces. The region deeper than the surface layer is called the interior. There are areas where the grains are stuck together, areas where the crystal orientation changes inside the grain (including the center), and areas with many defects. The grain boundary is a type of planar defect. The vicinity of the grain boundary refers to the region within 10 nm from the grain boundary. In this case, particles are not limited to spherical shapes (cross-sectional shapes are circular), and the cross-sectional shapes of individual particles are also included. Shapes include ovals, rectangles, trapezoids, cones, squares with rounded corners, and asymmetric shapes. Additionally, the individual particles may be of irregular shape.

[0043] In this specification and the like, Miller indices are used to indicate crystal planes and directions. Individual faces are represented in ( ). Crystal faces, directions and space groups are represented by the crystallographic notation of numbers with superscripts. However, in this specification, due to limitations on the application notation, instead of adding a bar above the number, It may be expressed by adding a minus sign (-) before it.

[0044] (Embodiment 1) In this embodiment, a method for manufacturing a positive electrode active material of one embodiment of the present invention will be described with reference to FIGS. An example of the law will be explained.

[0045] <Step S11> In step S11 of FIG. 1, a composite oxide containing lithium, a transition metal M, and oxygen is first As the material for (LiMO2), a lithium source and a transition metal M source are prepared.

[0046] Examples of the lithium source include lithium carbonate, lithium hydroxide, lithium nitrate, and lithium fluoride. Um etc. can be used.

[0047] The transition metal M is a layered rocksalt complex oxide that belongs to the space group R-3m together with lithium. It is preferable to use a metal that can form a crystalline silicon film. For example, manganese, cobalt, or nickel may be used. In other words, only cobalt may be used as a source of the transition metal M. Alternatively, nickel alone may be used, or two types of cobalt and manganese, or cobalt and nickel Two types of metals, ie, cobalt and nickel, may be used, or three types of metals, ie, cobalt, manganese, and nickel, may be used.

[0048] When a metal capable of forming a layered rock salt type composite oxide is used, a layered rock salt type crystal structure can be formed. It is preferable to mix cobalt, manganese, and nickel in the range of the ratio. Aluminum may be added to these transition metals as long as the crystal structure of this type can be obtained.

[0049] As the source of the transition metal M, oxides, hydroxides, etc. of the metals exemplified as the transition metal M are used. As the cobalt source, for example, cobalt oxide, cobalt hydroxide, etc. can be used. As the manganese source, manganese oxide, manganese hydroxide, etc. can be used. Nickel oxide, nickel hydroxide, etc. can be used as the nickel source. The aluminum source may be aluminum oxide, aluminum hydroxide, or the like. do.

[0050] <Step S12> Next, in step S12, the lithium source and the transition metal M source are mixed. The mixing can be carried out by a wet method or a cold method. For example, a ball mill, a bead mill, etc. can be used for the mixing. When using a ball mill, for example, zirconia balls can be used as grinding media. It is preferable to use

[0051] <Step S13> Next, in step S13, the mixed material is heated. This step is similar to the subsequent heating step. To distinguish between the two, it is sometimes called firing or first heating. Heating is performed at temperatures between 800°C and 1100°C. It is preferable to carry out the heating at a temperature of less than 1000°C, and more preferable to carry out the heating at a temperature of 900°C or more and 1000°C or less. A temperature of about 950°C is more preferable, or a temperature of 800°C or higher and 1000°C or lower is preferable. The temperature is preferably 900°C or higher and 1100°C or lower. If the temperature is too low, the lithium source and the transition metal On the other hand, if the temperature is too high, the decomposition and melting of the transition metal M When the metal involved in the redox reaction is excessively reduced, lithium evaporates, etc. For example, if cobalt is used as the transition metal M, defects may occur. This can result in defects where the valence of the ions becomes divalent.

[0052] The heating time can be, for example, 1 hour to 100 hours, and can be 2 hours to 20 hours. It is preferable to set the time to 1 hour or more and 20 hours or less. It is also preferable to set the time to 2 hours or more and 1 The firing is preferably carried out in an atmosphere with little water, such as dry air (for example, a dew point of -50°C). It is preferable to carry out the heating at a temperature of 1000°C or lower, more preferably -100°C or lower. The heating time is set to 200°C / h, and the flow rate of the drying atmosphere is set to 10 L / min. The heated material can then be cooled to room temperature (25°C). For example, it is preferable that the time required for the temperature to drop from a specified temperature to room temperature is 10 hours or more and 50 hours or less.

[0053] However, cooling to room temperature in step S13 is not essential. If there is no problem in carrying out the steps S1 to S44, the cooling is continued to a temperature higher than room temperature. You may do so.

[0054] <Step S14> Next, in step S14, the material sintered as described above is recovered, and lithium, a transition metal M, and A composite oxide containing oxygen (LiMO2) is obtained. Specifically, lithium cobalt oxide, manganese Lithium nickel oxide, lithium nickel oxide, cobalt with some of the cobalt replaced by manganese lithium cobalt oxide, lithium cobalt oxide in which some of the cobalt is replaced by nickel, or nickel Lithium manganese cobalt oxide, etc. can be obtained.

[0055] In step S14, the previously synthesized lithium, transition metal M, and oxygen are mixed together. In this case, steps S11 to S13 may be omitted. It is possible.

[0056] For example, a pre-synthesized composite oxide is cobalt oxide manufactured by Nippon Chemical Industry Co., Ltd. Lithium particles (product name: Cellseed C-10N) can be used. This is an average particle The diameter (D50) was approximately 12 μm, and impurity analysis was performed using glow discharge mass spectrometry (GD-MS). In the precipitation, the magnesium concentration and fluorine concentration are 50 ppm wt or less, and the calcium concentration is The aluminum and silicon concentrations are 100 ppm wt or less, and the nickel concentration is 1 50 ppm wt or less, sulfur concentration 500 ppm wt or less, arsenic concentration 1100 ppm wt or less, and the concentration of elements other than lithium, cobalt and oxygen is 150 ppm wt or less t or less, and lithium cobalt oxide.

[0057] Alternatively, lithium cobalt oxide particles (product name: Cellseed C-5) manufactured by Nippon Chemical Industry Co., Ltd. H) can also be used. This has an average particle size (D50) of about 6.5 μm, and GD- In the MS impurity analysis, the concentration of elements other than lithium, cobalt, and oxygen was C-1 It is lithium cobalt oxide, which is the same as or lower than 0N.

[0058] In this embodiment, cobalt is used as the metal M, and pre-synthesized lithium cobalt oxide is used. The particles used were cellulose nanoparticles (Cellseed C-10N manufactured by Nippon Chemical Industry Co., Ltd.).

[0059] <Step S21> Next, in step S21, a halogen source such as a fluorine source or a chlorine source is used as a material for the mixture 902. A source of silicon and a source of magnesium are provided, and preferably a source of lithium is also provided.

[0060] Fluorine sources include, for example, lithium fluoride (LiF) and magnesium fluoride (MgF2). , aluminum fluoride (AlF3), titanium fluoride (TiF4, TiF3), koba fluoride CoF2, CoF3, Nickel Fluoride (NiF2), Zirconium Fluoride (Zr F4), vanadium fluoride (VF5), manganese fluoride (MnF2, MnF3), fluoride Iron (FeF2, FeF3), chromium fluoride (CrF2, CrF3), niobium fluoride (Nb F5), zinc fluoride (ZnF2), calcium fluoride (CaF2), sodium fluoride ( NaF), potassium fluoride (KF), barium fluoride (BaF2), cerium fluoride (C eF2), lanthanum fluoride (LaF3), sodium aluminum hexafluoride (Na3Al F6) and the like can be used. Also, a mixture of multiple fluorine sources can be used. However, lithium fluoride has a relatively low melting point of 848°C, making it easy to melt during the annealing process described below. Therefore, it is preferable.

[0061] As the chlorine source, for example, lithium chloride, magnesium chloride, etc. can be used.

[0062] Examples of magnesium sources include magnesium fluoride, magnesium oxide, and magnesium hydroxide. Sodium carbonate, magnesium carbonate, etc. can be used.

[0063] As the lithium source, for example, lithium fluoride or lithium carbonate can be used. Therefore, lithium fluoride can be used as both a lithium source and a fluorine source. Magnesium fluoride can be used as both a fluorine source and a magnesium source.

[0064] In this embodiment, lithium fluoride (LiF) is prepared as a fluorine source. Magnesium fluoride (MgF2) will be prepared as the source of neodymium. Lithium fluoride (L) LiF and magnesium fluoride MgF2 are mixed in a molar ratio of about LiF:MgF2=65:35. Mixing them together has the greatest effect in lowering the melting point. On the other hand, the more lithium fluoride there is, the more lithium There is a concern that excessive lithium fluoride may cause deterioration of cycle characteristics. The molar ratio of LiF to magnesium fluoride MgF2 is LiF:MgF2=x:1 (0≦x≦1 .9), and LiF:MgF2=x:1 (0.1≦x≦0.5) is more preferable. LiF:MgF2=x:1 (x=approximately 0.33) is more preferable. In the specification, "near" means a value greater than 0.9 times and less than 1.1 times that value.

[0065] If the subsequent mixing and grinding steps are to be carried out wet, a solvent is prepared. ketones such as ethanol and isopropanol, alcohols such as ethanol and isopropanol, diethyl ether ethers, dioxane, acetonitrile, N-methyl-2-pyrrolidone (NMP), etc. Use an aprotic solvent that does not react easily with lithium. In this embodiment, acetone is used.

[0066] <Step S22> Next, in step S22, the materials of the mixture 902 are crushed and mixed. The process can be carried out by either a dry method or a wet method, but the wet method is preferred because it allows for finer pulverization. For mixing, a ball mill, a bead mill, etc. can be used. When used, it is preferable to use, for example, zirconia balls as the grinding media. It is preferable to carry out the above mixing and grinding steps sufficiently to pulverize the mixture 902 into fine powder.

[0067] <Step S23> Next, in step S23, the mixed and crushed materials are collected and mixed into a mixture 90 You get 2.

[0068] The mixture 902 has, for example, a D50 (median diameter) of 600 nm or more and 20 μm or less. It is preferable that the thickness is 1 μm or more and 10 μm or less, and more preferable that the thickness is 600 nm or less. The size of the fine powder is preferably 1 μm or more and 10 μm or less, or 1 μm or more and 20 μm or less. If the resulting mixture 902 is a compound having lithium, a transition metal M, and oxygen, the compound can be produced in a later step. When mixed with the oxide, the mixture 902 is easily distributed uniformly on the surface of the composite oxide particles. stomach.

[0069] <Step S41> Next, in step S41, LiMO2 obtained in step S14 and the mixture 902 are The number of transition metal atoms in the composite oxide containing lithium, transition metal, and oxygen is The ratio of M to the number of magnesium atoms Mg contained in the mixture 902 is M:Mg=100:y (0.1≦y≦6), and M:Mg=100:y (0.3≦y≦3). It is more preferable to have one.

[0070] The mixing in step S41 is performed more slowly than the mixing in step S12 in order to prevent the composite oxide particles from being destroyed. For example, it is preferable to set the rotation speed to be milder than that of the mixing in step S12. It is preferable to use conditions where the amount of particles is small or the time is short. It can be said that these conditions are less likely to destroy the particles. For mixing, a ball mill, a bead mill, etc. When a ball mill is used, for example, zirconia balls are used as grinding media. It is preferable to use

[0071] <Step S42> Next, in step S42, the mixed materials are collected to obtain a mixture 903.

[0072] In this embodiment, the mixture of lithium fluoride and magnesium fluoride is Although the present invention has been described as a method of adding a small amount of lithium cobalt oxide to the Instead of the mixture 903 in step S42, a starting material of lithium cobalt oxide may be used. A magnesium source, a fluorine source, etc. may be added to the raw material and then fired. The process includes steps S11 to S14 and steps S21 to S23. Since there is no need to separate the processes, it is simple and highly productive.

[0073] Alternatively, lithium cobalt oxide pre-doped with magnesium and fluorine can be used. Magnesium and fluorine doped lithium cobalt oxide can be used to This is simpler and allows the steps up to step S42 to be omitted.

[0074] In addition, magnesium and fluorine were added to lithium cobalt oxide, and magnesium was further added to the lithium cobalt oxide. A magnesium source and a fluorine source may also be added.

[0075] <Step S43> Next, in step S43, the mixture 903 is heated in an atmosphere containing oxygen. This step is sometimes called the first annealing step to distinguish it from other heating steps. It is more preferable to use heating that has the effect of preventing adhesion so that the particles of 03 do not stick together.

[0076] Examples of heating that has the effect of suppressing adhesion include heating while stirring the mixture 903, Examples of the method include heating the container containing 903 while vibrating it.

[0077] The heating temperature in step S43 is equal to or higher than the temperature at which the reaction between LiMO2 and the mixture 902 proceeds. The temperature at which the reaction proceeds is the temperature at which the elements contained in LiMO2 and the mixture 902 Therefore, it is acceptable that the temperature is lower than the melting point of these materials. For example, salts and oxides have a melting temperature T m 0.757 times (Tanman temperature T d )mosquito Solid-state diffusion occurs.

[0078] However, if the temperature is higher than the temperature at which at least a part of the mixture 903 melts, the reaction will proceed more easily. Therefore, the annealing temperature is preferably equal to or higher than the eutectic point of the mixture 902. When the compound 902 contains LiF and MgF2, the temperature in step S43 is set to 700°C, which is the eutectic point. A temperature of 42°C or higher is preferable.

[0079] In addition, the molar ratio of LiCoO2:LiF:MgF2 was 100:0.33:1. The mixed mixture 903 shows an endothermic temperature around 830°C in differential scanning calorimetry (DSC). Therefore, the annealing temperature is preferably 830°C or higher. The substance 903 contains at least fluorine, lithium, cobalt, and magnesium. , the mixture 903 has a crystal structure of O3' type.

[0080] The higher the annealing temperature, the easier the reaction will proceed, shortening the annealing time and increasing productivity. Therefore, it is preferable.

[0081] However, the annealing temperature must be above the decomposition temperature of LiMO2 (1130°C for LiCoO2). Also, at temperatures close to the decomposition temperature, a small amount of LiMO2 decomposes. Therefore, the annealing temperature is preferably 1130°C or less. It is more preferable that the temperature is 1000°C or lower, and even more preferable that the temperature is 950°C or lower. It is more preferable that the temperature is 0.4°C or lower.

[0082] Therefore, the annealing temperature is preferably 500°C or higher and 1130°C or lower. 1000°C or less is more preferable, 500°C or more and 950°C or less is even more preferable, and 500°C or more and 950°C or less is even more preferable. The temperature is more preferably 742°C or higher and 1130°C or lower, and more preferably 742°C or higher and 1130°C or lower. More preferably, the temperature is 42°C or higher and 1000°C or lower, and even more preferably, 742°C or higher and 950°C or lower. More preferably, the temperature is 742°C or higher and 900°C or lower. Also, the temperature is preferably 830°C or higher and 1130°C or lower. Preferably, the temperature is 830°C or higher and 1000°C or lower, more preferably 830°C or higher and 950°C or lower. The temperature is preferably 830°C or higher and more preferably 900°C or lower.

[0083] Furthermore, when the mixture 903 is heated, the partial pressure of fluorine or fluoride in the atmosphere is set within an appropriate range. It is preferable to control the temperature to

[0084] In the manufacturing method described in this embodiment, some materials, for example, LiF, which is a fluorine source, are used as a flux. This function allows the annealing temperature to be set below the decomposition temperature of LiMO2, for example, 7 The temperature can be lowered to between 42°C and 950°C, and the surface layer contains more magnesium than the center. This allows the additives to be highly distributed, resulting in a positive electrode active material with excellent properties.

[0085] However, because LiF is lighter than oxygen molecules, it can volatilize and dissipate when heated. In this case, the amount of LiF in the mixture 903 decreases, and the function as a flux is weakened. It is necessary to heat the material while suppressing the evaporation of LiF. Even if this is the case, there is a possibility that Li and F on the surface of LiMO2 will react to produce LiF, which may then volatilize. Therefore, even if a fluoride with a higher melting point than LiF is used, the volatilization is suppressed in the same way. Regulation is necessary.

[0086] Therefore, the mixture 903 is heated in an atmosphere containing LiF, that is, the Li It is preferable to heat the mixture 903 under a condition where the partial pressure of F is high. The volatilization of LiF in the compound 903 can be suppressed.

[0087] The annealing is preferably performed for an appropriate time. The appropriate annealing time depends on the annealing temperature, It changes depending on the conditions such as the size and composition of the LiMO2 particles in step S14. If it is small, a lower temperature or shorter time may be more preferable than if it is large.

[0088] For example, if the average particle diameter (D50) of the particles in step S14 is about 12 μm, the annealing temperature The annealing temperature is preferably, for example, 600° C. or higher and 950° C. or lower. The annealing time is preferably, for example, 3 hours or longer. Preferably, 10 hours or more is more preferable, and 60 hours or more is even more preferable.

[0089] On the other hand, when the average particle diameter (D50) of the particles in step S24 is about 5 μm, the annealing temperature The annealing temperature is preferably, for example, 600° C. or higher and 950° C. or lower. The annealing time is, for example, 1 hour to 10 hours. Preferably, it is less than 1 hour, and more preferably about 2 hours.

[0090] The temperature drop time after annealing is preferably, for example, 10 hours or more and 50 hours or less.

[0091] <Step S31> Next, in step S31, an additive source is prepared. The additive source may contain, for example, , Zirconium, Aluminum, Nickel, Manganese, Titanium, Vanadium, Iron, Chromium , niobium, cobalt, arsenic, zinc, silicon, sulfur, phosphorus, and boron. In FIG. 1, a nickel source and an aluminum source are used as additive sources. We will explain about this.

[0092] The source of each additive is preferably an oxide, hydroxide, fluoride, alkoxide, or the like.

[0093] <Step S61> Next, in step S61, the annealed mixture 903 is mixed with an additive source. It can be said that the additive is contained in the surface of the mixture 903 after the mixing.

[0094] Examples of the mixing method include a solid phase method, a sol-gel method, a sputtering method, and a mechanochemical method. The solid phase method and the sol-gel method can be easily performed at atmospheric pressure and room temperature. In addition, it is preferable that an additive can be contained in the surface of the mixture 903 after annealing.

[0095] In this specification, the sol-gel method is a method of forming a metal-containing organic compound solution into a solution. The solution is converted into metal oxide or hydroxide particles by hydrolysis and polymerization of the compounds in the solution. The solution is dissolved into a sol, and the reaction is allowed to proceed further to gel the material, resulting in an amorphous porous gel. This refers to a method of forming a film or crystal by heating.

[0096] When using the sol-gel method, first, the additive source alkoxide is dissolved in alcohol and then the alkoxide is mixed with the alcohol. The mixture 903 after nealing is mixed with the above.

[0097] For example, when zirconium is used as the additive source, zirconium(IV) tetrapropionate is used. The alcohol may be, for example, isopropanol (2 -propanol) can be used.

[0098] Next, a solution of zirconium(IV) tetrapropoxide in isopropanol and the annealed The mixture with the mixture 903 is stirred. 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 the amount of zirconium (IV) tetrapropoxide that is hydrated. The time may be long enough to cause decomposition and polycondensation reactions, for example, 60 hours at room temperature. This can be done under the following conditions.

[0099] After the above treatment, the precipitate is collected from the mixture. The collection method can be filtration, centrifugation, etc. In this embodiment, the recovery is carried out by evaporation to dryness. In this embodiment, the drying is carried out by ventilation at 95°C.

[0100] <Step S62> Next, in step S62, the dried material is collected to obtain a mixture 904.

[0101] <Step S63> Next, the mixture 904 synthesized in step S62 is heated (S43 is the first annealing In this case, the heating of S63 can be called the second annealing.) The heating conditions are 350°C or higher. The heating is carried out at a temperature of 600°C or less for 1 hour or more and 100 hours or less.

[0102] It is also preferable to heat in an atmosphere containing oxygen.

[0103] In this embodiment, heating is performed at 400° C. for 2 hours.

[0104] <Step S64> In step S64, crushing is carried out, and mixing is carried out if necessary.

[0105] <Step S67> Next, in step S64, the recovered mixture is heated (S63 is called the second annealing). In this case, the heating of S63 can be called the third annealing. The heating time is the time when the specified temperature is maintained. The time is preferably 50 hours or less, and more preferably 2 hours or more and 10 hours or less. It is more preferable to carry out the treatment for 1 hour or more and 3 hours or less.

[0106] The specified temperature is preferably 600°C or higher and 1200°C or lower, and more preferably 800°C or higher and 1000°C or lower. is more preferred.

[0107] It is also preferable to heat in an atmosphere containing oxygen.

[0108] In this embodiment, the specified temperature is set to 850°C and is maintained for 2 hours, and the temperature is increased by 200°C. / h, and the flow rate of the dry atmosphere is 10 L / min.

[0109] In this embodiment, the heating is performed twice under different heating conditions in steps S63 and S67. The heat treatment is performed in separate steps, but this is not particularly limited. In step S63, the heat treatment is performed once. The temperature range is 830°C or higher and 1130°C or lower, and the heating time is preferably, for example, 1 hour or longer. It is more preferable that the heating time be 10 hours or more, and even more preferable that the heating time be 60 hours or more. If this is done, it is not necessary to perform the heat treatment twice, and in this case, the number of steps can be reduced. .

[0110] <Step S68> In step S68, crushing is carried out, and mixing is carried out if necessary.

[0111] <Step S66> Next, in step S66, the crushed material is collected to prepare the positive electrode active material 100. At this time, it is preferable to further sieve the collected particles. By filtering, if the positive electrode active material particles are stuck together, this can be resolved. Cut.

[0112] An example of an SEM image of the positive electrode active material 100 obtained according to the flow of FIG. 1 is shown in FIG. The manufacturing process of the positive electrode active material 100 shown in FIG. 4 differs between step S63 and step S67. In step S63, the heating conditions are not divided into two steps, but are set to one step, and the heating condition is 830°C or more for 11 minutes. The temperature range was 30°C or less, and the heating time was 850°C for 10 hours in an oxygen atmosphere. The additive sources used were nickel and aluminum. The surface of the positive electrode active material 100 shown in FIG. It has a smooth surface with few irregularities. The smoothness and small irregularities can be seen, for example, in the cross-sectional SEM image of the positive electrode active material 100 shown in FIG. can be determined from a cross-sectional TEM image, the specific surface area of ​​the positive electrode active material 100, etc. The particle shape of 100 is rarely spherical and is irregular, so it is difficult to calculate the radius of curvature. It is difficult to define the radius of curvature because the radius of curvature changes as the particle size changes. Although it is difficult to obtain a cross-sectional shape of the positive electrode active material 100 cut at an arbitrary position, the shape The edges of the container can be rounded and have almost no sharp edges. Fluorine is important for making the surface smooth and shiny. Fluorine improves the wettability of the positive electrode active material surface, making it homogenous and flat. For example, in step S43, lithium oxide and fluoride are mixed together. It is important to prepare positive electrode active material particles by heating the positive electrode active material in the manner shown in Figure 4. In the example 100, a region containing fluorine is formed as a barrier layer in the surface layer portion.

[0113] Next, a manufacturing method different from that shown in FIG. 1 will be described with reference to FIG. 2. Note that the parts common to FIG. 1 Since there are many differences, we will mainly explain the differences. The explanation can be taken into consideration. In addition, the positive electrode active material is finally obtained in the manufacturing flow of FIG. 1, FIG. 2, and FIG. Although it is stated that a quality of 100 can be obtained, it does not indicate that the same structure and ingredients will be obtained. However, if the manufacturing process is different, at least some of the particles will be different, for example, the particle size, the convex portion, the concentration distribution, etc. The fabric, particle appearance, etc. will be different.

[0114] In FIG. 1, the mixture 903 after annealing in step S61 and nickel as an additive source are The preparation method of mixing both the source and the aluminum source has been described. As shown in steps S32 and S33 of FIGS. The mixing in steps S32 and S33 in FIGS. Before that, crushing may be carried out.

[0115] Examples of additives in the additive source include nickel, aluminum, manganese, titanium, and zinc. Iron, chromium, niobium, cobalt, arsenic, zinc, silicon, sulfur, lithium One or more elements selected from the group consisting of fluorine, fluorine, and boron can be used.

[0116] In FIG. 2, a zirconium source is used in step S31. In step S31, an aluminum source is used as an additive, and in step S32, a nickel source is used as an additive. show.

[0117] The methods for mixing these additives include, for example, the solid phase method, the sol-gel method, the sputtering method, Mechanochemical methods, CVD methods, etc. can be used. It's fine.

[0118] As shown in FIG. 2, in step S61-1, the nickel source is mixed, and then in step S61- The zirconium source and the aluminum source can be mixed in 2. The mixing can be dry or wet. In this case, for example, step S61-2 can be performed by a sol-gel method. When the sol-gel method is used, the aluminum source is aluminum alkoxide. The zirconium source is zirconium alkoxide. If steps S62, S63, S64, S67, and S68 are carried out in the same manner, the positive electrode active material 100 can be obtained. can be.

[0119] In addition, the positive electrode immediately after heat treatment of S63 at 400°C for 2 hours in an oxygen atmosphere An example of an SEM image of the active material is shown in Figure 5. As shown in Figure 5, after heat treatment at 400°C, It can be seen that many zirconium oxide particles are attached. An example of an SEM image of the positive electrode active material immediately after heat treatment at 850°C for 2 hours in an oxidizing atmosphere. As shown in Figure 6, small crystal nuclei (zirconium oxide) were observed after the heat treatment at 400°C. The crystals of the crystalline silicon (SiC) are grown by heat treatment at 850°C, forming large lumps (scattered like islands). In the positive electrode active material shown in Figure 6, zirconium oxide scattered in islands functions as a barrier film. There are.

[0120] Also, the heating conditions in steps S63 and S67 are different from each other, and the heating conditions are not divided into two steps. The heating conditions were as follows: 63, one time, 850°C, 2 hours, oxygen atmosphere, An example of an SEM image of the electrode active material is shown in Figure 7. The zirconium oxide scattered like islands functions as a barrier film for the positive electrode active material.

[0121] Also, as shown in FIG. 3, in step S41, LiMO2 and a mixture 902 are mixed and annealed. Then, various additive sources may be mixed in step S61. Mixing may be performed by dry or wet methods. The annealing conditions can be seen in the description of step S43. If steps S62, S63, S64, S67, and S68 are performed in the same manner, the positive electrode active material 100 is obtained.

[0122] In this way, by separating the process of introducing the transition metal M and the additive, It may be possible to change the depth profile. For example, In addition, the number of atoms of the transition metal M is determined as follows: The ratio of the number of atoms of the additive element to the reference is made higher in the surface layer than in the central portion. It is possible.

[0123] This embodiment can be used in combination with other embodiments.

[0124] (Embodiment 2) In this embodiment, the positive electrode active material particles obtained by the manufacturing method described in Embodiment 1 will be described below. The positive electrode active material particles obtained by the manufacturing method shown in Embodiment 1 are composed of lithium and a transition metal. It has a layered rock-salt type crystal structure that is common to composite oxides containing metals.

[0125] 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.

[0126] 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.

[0127] Materials with a layered rock-salt crystal structure, such as lithium cobalt oxide (LiCoO2), are It has a high capacitance and is known to be an excellent positive electrode active material for secondary batteries. An example of a material having a crystal structure is a composite oxide represented by LiMO2.

[0128] The Jahn-Teller effect in transition metal compounds depends on the number of electrons in the d orbital of the transition metal: The strength of the effect is known to vary.

[0129] In compounds containing nickel, distortion is likely to occur due to the Jahn-Teller effect. Therefore, when LiNiO2 is charged and discharged at high voltage, In LiCoO2, the Jahn-Teller effect is This suggests that the effect of the ion implantation is small, and the resistance to charging and discharging at high voltages may be superior, which is preferable. It's nice.

[0130] The positive electrode active material will be described with reference to Figs. 8 to 11. The case where cobalt is used as the transition metal in the substance will be described.

[0131] <Conventional positive electrode active materials> The positive electrode active material shown in FIG. 10 is prepared by the method described below, to which halogen and magnesium are added. The lithium cobalt oxide shown in Figure 10 is lithium cobalt oxide (LiCoO2). As described in Non-Patent Documents 1 and 2, the crystal structure changes depending on the charge depth. changes.

[0132] As shown in FIG. 10, lithium cobalt oxide at a charge depth of 0 (discharged state) is in the space group R It has a region with a -3m crystal structure, and there are three CoO2 layers in the unit cell. Therefore, this crystal structure is sometimes called an O3 type crystal structure. The term "octahedral structure" refers to a structure in which an octahedral structure in which oxygen atoms are six-coordinated to each other is connected on a plane in an edge-sharing state. do.

[0133] At a charge depth of 1, the crystal structure has the space group P-3m1, and there is Co in the unit cell. There is one O2 layer, so this crystal structure is sometimes called an O1-type crystal structure.

[0134] In addition, when the charge depth is about 0.88, lithium cobalt oxide has a crystal structure of the space group R-3m. This structure is similar to the structure of CoO2, such as P-3m1(O1), and R-3m(O 3) and the structure of LiCoO2, and the structure of The crystal structure is sometimes called the H1-3 type crystal structure. has twice the number of cobalt atoms per unit cell of the other structures. In this specification, the c-axis of the H1-3 type crystal structure is expressed as 0 for ease of comparison with other structures. It will be shown as a diagram of half of a unit cell.

[0135] As an example, the H1-3 type crystal structure has a unit cell as described in Non-Patent Document 2. The coordinates of cobalt and oxygen in 1(0, 0, 0.27671±0.00045), O2(0, 0, 0.11535±0. 00045), where O1 and O2 are oxygen atoms. The H1-3 crystal structure is represented by a unit cell with one cobalt and two oxygen atoms. On the other hand, as will be described later, the O3'-type crystal structure of one aspect of the present invention preferably has one It is represented by a unit cell using cobalt and one oxygen atom. This is the O3' type crystal structure. The symmetry between cobalt and oxygen differs between the H1-3 structure and the O3' structure. This shows that the crystal structure is less different from the O3 structure than the H1-3 type structure. Selection of which unit cell is more preferable to represent the crystal structure of the active material. For example, the selection is based on the GOF (good of fit) in the Rietveld analysis of XRD. ss) should be selected to be smaller.

[0136] High-voltage charging where the charging voltage is 4.6V or higher based on the oxidation-reduction potential of lithium metal When the battery is repeatedly charged or discharged to a deep depth of charge of 0.8 or more, Lithium cobalt oxide has a H1-3 type crystal structure and a R-3m(O3) structure in the discharged state. The crystal structure changes (i.e., non-equilibrium phase changes) between these two states.

[0137] However, these two crystal structures have a large misalignment of the CoO2 layers. As shown by the arrows, in the H1-3 type crystal structure, the CoO2 layer is larger than the R-3m(O3). Such dynamic structural changes have a negative effect on the stability of the crystal structure. Yes.

[0138] Furthermore, the difference in volume is large. When comparing the same number of cobalt atoms, the H1-3 type crystal The difference in volume between the structure and the O3-type crystal structure in the discharged state is more than 3.0%.

[0139] In addition, the H1-3 type crystal structure has continuous CoO2 layers such as P-3m1(O1). The resulting structure is likely to be unstable.

[0140] Therefore, repeated high-voltage charging and discharging causes the crystal structure of lithium cobalt oxide to collapse. The breakdown of the crystal structure causes a deterioration in cycle characteristics. , the number of sites where lithium can exist stably decreases, and lithium insertion and desorption becomes difficult. This is thought to be the reason.

[0141] <Cathode active material> In the positive electrode active material of one embodiment of the present invention, the CoO2 layer is displaced during repeated high-voltage charge and discharge. Furthermore, the change in volume can be reduced. The positive electrode active material of one embodiment of the present invention can achieve excellent cycle characteristics. The positive electrode active material according to one embodiment of the present invention can have a stable crystal structure in a charged state at a high voltage. Therefore, the positive electrode active material of one embodiment of the present invention has a short circuit resistance when maintained in a charged state at a high voltage. In such cases, safety is improved, making it preferable. .

[0142] The positive electrode active material of one embodiment of the present invention has a sufficient discharge state and a high voltage charged state. The change in the crystal structure and the difference in volume when compared per the same number of transition metal atoms in small.

[0143] The crystal structure of the positive electrode active material before and after charging and discharging is shown in Figure 8. The positive electrode active material is composed of lithium and transition metals. It is a composite oxide containing cobalt as group M and oxygen. It is preferable to have magnesium, aluminum, nickel, titanium, and zirconium. It is also preferable to have a halogen such as fluorine, chlorine or bromine as an additive.

[0144] The crystal structure at a charge depth of 0 (discharged state) in FIG. 8 is R-3m(O3), the same as in FIG. On the other hand, when the positive electrode active material is fully charged, it has a different crystal structure from the H1-3 type. This structure is in the space group R-3m, and is not a spinel-type crystal structure. The cobalt, magnesium, and other ions occupy the oxygen hexacoordinated positions, and the arrangement of cations is smooth. It has a symmetry similar to that of the Pinel type. The periodicity of the CoO2 layers in this structure is the same as that of the O3 type. Therefore, in this specification and the like, this structure is referred to as an O3'-type crystal structure or a pseudospinel-type crystal structure. Therefore, the O3' type crystal structure can be rephrased as a pseudospinel type crystal structure. In the crystal structure diagram of the O3' type crystal structure shown in Figure 8, the cobalt atoms In order to explain the symmetry of the oxygen atom, the lithium atom is omitted. In reality, for example, 20 atomic % or less of lithium is present relative to cobalt between the CoO2 layers. In addition, in both the O3 type and O3' type crystal structures, the CoO2 layer It is preferable that magnesium is present in a dilute state between the two, i.e., at the lithium site. It is preferable that halogen such as fluorine is present randomly and dilutely at the oxygen sites.

[0145] In the O3' type crystal structure, light elements such as lithium may occupy the oxygen tetracoordination position. In this case too, the ion arrangement has a symmetry similar to that of the spinel type.

[0146] The O3' type crystal structure has random Li between layers, but the CdCl2 type crystal structure It can be said that this crystal structure is similar to the CdCl2 type. The structure is that when lithium nickel oxide is charged to a charge depth of 0.94 (Li 0.06 NiO2 ) crystal structure, but pure lithium cobaltate or cobalt-rich layered rock salt It is known that positive electrode active materials of this type do not usually have this crystal structure.

[0147] In the positive electrode active material of one embodiment of the present invention, when a large amount of lithium is released by charging at a high voltage, The change in the crystal structure is more suppressed than in conventional positive electrode active materials. As can be seen, there is almost no misalignment of the CoO2 layers in these crystal structures.

[0148] More specifically, the positive electrode active material of one embodiment of the present invention has a structure that can be maintained even when the charging voltage is high. For example, conventional positive electrode active materials have a H1-3 type crystal structure. For example, even at a voltage of about 4.6 V based on the potential of lithium metal, R-3m(O 3) There exists a region of charging voltage where the crystal structure of For example, even at a voltage of 4.65V to 4.7V based on the potential of lithium metal, O3 Furthermore, when the charging voltage is increased, the H1-3 In secondary batteries, for example, when graphite is used as the negative electrode active material, When using R-3m, for example, even when the voltage of the secondary battery is 4.3V or more and 4.5V or less There is a region of charging voltage where the crystal structure of (O3) can be maintained, and there is a region where the charging voltage is further increased. For example, even when the potential of lithium metal is between 4.35V and 4.55V, O3 There is a region where a '-type crystal structure can be formed.

[0149] Therefore, in the positive electrode active material of one embodiment of the present invention, no result is obtained even after repeated charge and discharge at a high voltage. The crystal structure is not easily broken.

[0150] In addition, the positive electrode active material has an O3 type crystal structure at a charge depth of 0 and an O3' type crystal structure at a charge depth of 0.88. The difference in volume per unit cell of the crystal structure is 2.5% or less, more specifically 2.2% or less. do.

[0151] In the O3' type crystal structure, the coordinates of cobalt and oxygen in the unit cell are expressed as Co(0, 0,0.5), O(0,0,x), and can be shown within the range of 0.20≦x≦0.25. .

[0152] Additives, such as matrices, exist randomly and dilutely between the CoO2 layers, i.e., at the lithium sites. Magnesium has the effect of suppressing the displacement of the CoO2 layers. When magnesium is present, it tends to form the O3' type crystal structure. It is preferable that magnesium is distributed throughout the particles of the positive electrode active material of one embodiment. In order to distribute the cations throughout the cathode active material, a heat treatment is performed in a manufacturing process of the cathode active material according to one embodiment of the present invention. It is preferable to do so.

[0153] However, if the heat treatment temperature is too high, cation mixing occurs, and additives, e.g. For example, the possibility of magnesium entering the cobalt site increases. Magnesium does not have the effect of maintaining the structure of R-3m during high voltage charging. If the temperature of the process is too high, cobalt will be reduced to divalent and lithium will evaporate. There are also concerns about other adverse effects.

[0154] Therefore, before the heat treatment to distribute magnesium throughout the particles, cobalt oxide It is preferable to add a halogen compound such as a fluorine compound to lithium. Adding substances to lithium cobalt oxide lowers its melting point. At a temperature where on-mixing is unlikely to occur, it is easy to distribute magnesium throughout the particles. Furthermore, if a fluorine compound is present, the electrolyte will have corrosion resistance to the hydrofluoric acid produced by decomposition. can be expected to improve.

[0155] If the magnesium concentration is increased above a desired value, the effect on stabilizing the crystal structure is reduced. In addition to the lithium site, magnesium may also be present at the cobalt site. This is thought to be because the magnesium contained in the positive electrode active material of one embodiment of the present invention also enters the matrix. The number of atoms of ammonium is preferably 0.001 times or more and 0.1 times or less the number of atoms of the transition metal M, and is preferably 0. It is more preferable that the ratio is greater than 0.01 and less than 0.04, and more preferably about 0.02. The magnesium concentration can be measured by, for example, measuring the elemental composition of the entire particle of the positive electrode active material using ICP-MS or the like. It may be a value obtained by performing an analysis, or may be a value based on the blending of raw materials in the process of producing the positive electrode active material. It's fine.

[0156] Lithium cobalt oxide is added with metals other than cobalt (hereinafter referred to as metal Z), such as nickel, One or more metals selected from aluminum, manganese, titanium, vanadium and chromium They may be added, and it is particularly preferred to add one or more of nickel and aluminum. Manganese, titanium, vanadium, and chromium may easily take on a stable tetravalent state. The addition of the metal Z may contribute significantly to the stability of the positive electrode active material of one embodiment of the present invention. For example, in some materials, the crystalline structure may become more stable when charged at a high voltage. In the positive electrode active material of one embodiment of the present invention, the metal Z improves the crystallinity of the lithium cobalt oxide. It is preferable to add it at a concentration that does not change significantly. It is preferable that the amount is such that the desired effect is not exhibited.

[0157] As shown in the legend in Figure 8, transition metals such as nickel and manganese, as well as aluminum The nium is preferably present at the cobalt site, but some of it is present at the lithium site. It is also preferable that magnesium is present at the lithium site. The moiety may be substituted with fluorine.

[0158] As the magnesium concentration of the positive electrode active material of one embodiment of the present invention increases, the volume of the positive electrode active material increases. The amount of magnesium may decrease. For example, this can occur when magnesium enters the lithium site. This may reduce the amount of lithium that contributes to charging and discharging. In some cases, magnesium may produce magnesium compounds that do not contribute to charging and discharging. The positive electrode active material of one embodiment contains nickel as the metal Z in addition to magnesium. This may increase the capacity per weight and per volume. In one embodiment, the positive electrode active material contains aluminum as the metal Z in addition to magnesium. This may increase the capacity per weight and per volume. The positive electrode active material of one embodiment of the present invention contains nickel and aluminum in addition to magnesium. This may allow for higher capacity per weight and volume.

[0159] The concentrations of elements such as magnesium and metal Z contained in the positive electrode active material of one embodiment of the present invention are as follows: is expressed using the number of atoms.

[0160] The number of nickel atoms in the positive electrode active material of one embodiment of the present invention is 10% of the number of cobalt atoms. Preferably, it is 7.5% or less, more preferably 7.5% or less, and even more preferably 0.05% or more and 4% or less. The nickel concentration shown here is preferably 0.1% or more and 2% or less. The value may be a value obtained by performing elemental analysis of the entire particle of the positive electrode active material using MS or the like, or may be a value obtained by performing elemental analysis of the entire particle of the positive electrode active material using MS or the like. It may be based on the value of the blend of raw materials in the process of making the material.

[0161] If the battery is charged at a high voltage for a long period of time, transition metals will leach out of the positive electrode active material into the electrolyte. However, by having nickel in the above ratio, the positive electrode activity It may be possible to suppress the elution of transition metals from materials.

[0162] The number of aluminum atoms in the positive electrode active material of one embodiment of the present invention is 0.01 to the number of cobalt atoms. The range is preferably 0.05% or more and 4% or less, and more preferably 0.1% or more and 2% or less. The aluminum concentration can be determined by, for example, performing elemental analysis of the entire particle of the positive electrode active material using ICP-MS. It may be a value obtained by the calculation, or it may be a value based on the composition of raw materials in the process of producing the positive electrode active material. Good too.

[0163] If the electrolyte contains LiPF6, hydrogen fluoride may be generated due to hydrolysis. In addition, hydrogen fluoride is produced by the reaction of PVDF, which is used as a component of the positive electrode, with alkali. The decrease in hydrogen fluoride concentration in the charging solution may cause corrosion of the current collector. In addition, gelation of PVDF and / or peeling of the coating can be suppressed. This may prevent a decrease in adhesiveness due to insolubilization.

[0164] When the positive electrode active material according to one embodiment of the present invention contains magnesium in addition to the element X, high voltage charging When element X is phosphorus, the number of phosphorus atoms is equal to that of cobalt. The ratio of the number of atoms of 1 to 20% is preferable, the ratio of 2 to 10% is more preferable, and the ratio of 3% is even more preferable. More preferably, the number of magnesium atoms is 0.01 to 8.0%. 0.1% or more and 10% or less is preferable, 0.5% or more and 5% or less is more preferable, 0.7% or more The phosphorus and magnesium concentrations shown here are, for example, those obtained by ICP- The value may be a value obtained by performing elemental analysis of the entire particle of the positive electrode active material using MS or the like, or may be a value obtained by performing elemental analysis of the entire particle of the positive electrode active material using MS or the like. It may also be based on the value of the raw material composition in the process of making the quality.

[0165] When the positive electrode active material has cracks, phosphorus, more specifically, for example, phosphorus and acid, is present inside the cracks. The presence of a compound containing an element may inhibit the progression of cracks.

[0166] <Surface Layer> Magnesium is distributed throughout the particles of the positive electrode active material of one embodiment of the present invention. In addition, the magnesium concentration in the surface layer a is preferably higher than the average of the whole particle. For example, it is preferable that the magnesium concentration in the surface layer measured by XPS or the like is It is preferable that the magnesium concentration is higher than the average magnesium concentration of the whole particle measured by S or the like.

[0167] In addition, the positive electrode active material of one embodiment of the present invention does not contain an element other than cobalt, such as nickel, aluminum, or the like. In the case where the alloy contains one or more metals selected from aluminum, manganese, iron and chromium, It is preferred that the concentration of the metal in the vicinity of the particle surface is higher than the average concentration throughout the particle. For example, The concentrations of elements other than cobalt in the surface layer measured by XPS, etc., are measured by ICP-MS, etc. It is preferable that the concentration of the element is higher than the average concentration of the element in the whole particle.

[0168] The particle surface is essentially a crystal defect, and lithium is released from the surface during charging. As the lithium concentration in the outer layer increases, it is more likely to become lower than in the inner layer. If the magnesium concentration in the surface layer is high, the crystal structure will be easily broken. This allows for more effective suppression of structural changes. It is also expected that the corrosion resistance against hydrofluoric acid produced by decomposition of the electrolyte will be improved.

[0169] Furthermore, the concentration of halogen such as fluorine in the surface layer portion of the positive electrode active material of one embodiment of the present invention is higher than that of the entire particle. It is preferable that the average value is higher than the average value of the surface layer. By doing so, the corrosion resistance to hydrofluoric acid can be effectively improved.

[0170] As described above, the surface layer of the positive electrode active material according to one embodiment of the present invention contains more additives, such as magnesium, than the inside. It is preferable that the composition of the inner layer is different from that of the inner layer, and that the concentration of sodium and fluorine is high. It is preferable that the surface layer has a stable crystal structure at room temperature. For example, at least the surface layer portion a of the positive electrode active material of one embodiment of the present invention may have a crystalline structure. In addition, a part of the surface layer and the inside may have a rock salt type crystal structure. In this case, it is preferable that the crystal orientation of the surface layer and the crystal orientation of the interior are approximately the same.

[0171] Layered rock salt crystals and the anions of rock salt crystals are in a cubic close-packed structure (face-centered cubic lattice structure) ) It is estimated that the anions in the O3' type crystal also have a cubic close-packed structure. When they contact, there are crystal planes where the cubic close-packed structure formed by the anions is aligned. However, the space group of the layered rock salt crystal and O3' crystal is R-3m, and the space group of the rock salt crystal is The space groups Fm-3m (the common rock salt crystal space group) and Fd-3m (the simplest symmetry Since this is different from the space group of rock salt crystals, the Miller indices of the crystal planes that satisfy the above conditions are is different between layered rock salt crystals and O3'-type crystals and rock salt crystals. In salt-type crystals, O3'-type crystals, and rock salt-type crystals, the cubic maxima composed of anions When the orientation of the close-packed structure is aligned, it is sometimes said that the crystal orientation is roughly the same.

[0172] The crystal orientation of the two regions roughly coincides with each other, as can be seen from TEM (transmission electron microscope) images and STE M (scanning transmission electron microscope) image, HAADF-STEM (high angle annular dark field scanning transmission electron microscope) image This should be judged from images such as annular bright-field scanning transmission electron microscope (ABF-STEM) images. X-ray diffraction (XRD), electron diffraction, neutron diffraction, etc. can also be used as a basis for judgment. If the crystal orientation is roughly the same, cations and anions will appear linearly in a TEM image. The difference in the direction of the alternating rows is less than 5 degrees, and preferably less than 2.5 degrees. It can be seen that light elements such as oxygen and fluorine cannot be clearly observed in TEM images. In such cases, the alignment of the orientation can be determined by the arrangement of the metal elements.

[0173] However, if the surface layer is only MgO or only a solid solution structure of MgO and CoO(II), Therefore, the surface layer must contain at least cobalt. In the discharged state, it must also have lithium and have a path for lithium insertion and desorption. It is also preferable that the concentration of cobalt is higher than that of magnesium.

[0174] <Particle size> If the particle size of the positive electrode active material of one embodiment of the present invention is too large, it becomes difficult for lithium to diffuse. When the active material layer is applied to the current collector, the surface of the active material layer becomes too rough. If the particle size is too small, it will be difficult to support the active material layer when applying it to the current collector, and excessive reaction with the electrolyte will occur. Therefore, the average particle size (D50: also called the median diameter) However, it is preferably 1 μm or more and 100 μm or less, and more preferably 2 μm or more and 40 μm or less. Preferably, it is 5 μm or more and 30 μm or less.

[0175] <Analysis method> In one embodiment of the present invention, a positive electrode active material exhibits an O3'-type crystal structure when charged at a high voltage. Whether or not it is a positive electrode active material can be determined by examining the positive electrode charged at high voltage using XRD, electron diffraction, and neutron beam Determined by analysis using diffraction, electron spin resonance (ESR), nuclear magnetic resonance (NMR), etc. In particular, XRD can detect the symmetry of transition metals such as cobalt in the positive electrode active material with high resolution. It is possible to analyze the crystallinity and the orientation of the crystals, and to compare the periodic distortion of the lattice and the The crystallite size can be analyzed, and sufficient accuracy can be obtained by measuring the positive electrode obtained by disassembling the secondary battery. This is preferable in that it allows you to obtain a high degree of

[0176] As described above, the positive electrode active material of one embodiment of the present invention has a high voltage charging state and a high voltage discharging state. The crystal structure changes little when the battery is charged at high voltage and when it is discharged. Materials with a crystal structure that exhibits large changes in the crystal structure occupying 50 wt% or more cannot withstand high-voltage charging and discharging. In addition, there are cases where the desired crystal structure cannot be obtained by simply adding an additive element. It should be noted that there are cases where the cobalt oxide with magnesium and fluorine is Although they share the same property of being lithium, when charged at high voltage, the O3'-type crystal structure is In some cases, the H1-3 type crystal structure accounts for 50 wt% or more, and in other cases, the H1-3 type crystal structure accounts for 50 wt% or more. At a certain voltage, the O3' type crystal structure becomes almost 100 wt %. Increasing the voltage may result in the formation of an H1-3 type crystal structure. To determine whether or not a material is a positive electrode active material, analysis of the crystal structure, including XRD, is required. is necessary.

[0177] However, when the positive electrode active material is in a high-voltage charged or discharged state, its crystalline structure changes when it comes into contact with the air. For example, the O3' crystal structure may change to the H1-3 crystal structure. Therefore, all samples should be handled in an inert atmosphere such as argon. It is preferable to perform this step.

[0178] <Charging Method> In order to determine whether a certain composite oxide is a positive electrode active material of one embodiment of the present invention, For example, a coin cell (CR2032 type, 20mm diameter) with lithium as the counter electrode is used for high-voltage charging. It is possible to create a battery with a height of 3.2 mm and charge it.

[0179] More specifically, the positive electrode is formed by mixing a positive electrode active material, a conductive additive, and a binder in a slurry. The above may be applied to a positive electrode current collector made of aluminum foil and used.

[0180] Lithium metal can be used for the counter electrode. When the secondary battery is in a charged state, the potential of the secondary battery is different from the potential of the positive electrode. is the potential of the positive electrode unless otherwise specified.

[0181] The electrolyte contained 1 mol / L of lithium hexafluorophosphate (LiPF6). The electrolyte used was ethylene carbonate (EC) and diethyl carbonate (DEC). EC:DEC = 3:7 (volume ratio), vinylene carbonate (VC) was mixed at 2 wt%. The above can be used.

[0182] The separator can be made of polypropylene with a thickness of 25 μm.

[0183] The positive and negative electrode cans can be made of stainless steel (SUS). Cut.

[0184] The coin cell prepared under the above conditions was charged at a constant current of 4.6 V and 0.5 C, and then the current value The battery is charged at a constant voltage until the temperature reaches 0.01C. Here, 1C is 137mA / g. After charging in this way, place the coin cell in a glow By disassembling it in the box and removing the positive electrode, the positive electrode active material charged at high voltage can be obtained. When various analyses are carried out after this, the container is sealed in an argon atmosphere to prevent reactions with external components. For example, XRD can be performed in a sealed container in an argon atmosphere. can.

[0185] <XRD> CuKα calculated from the O3' type crystal structure and H1-3 type crystal structure model The ideal powder XRD patterns by the 1-line are shown in Figures 9 and 11. Calculated from the crystal structure of LiCoO2(O3) at charge depth 0 and CoO2(O1) at charge depth 1. The ideal XRD patterns of LiCoO2(O3) and CoO2(O1) are also shown. ) pattern is ICSD (Inorganic Crystal Structure The crystal structure information obtained from the Material Database (see Non-Patent Document 5) Reflex Pow, one of the modules of ls Studio (BIOVIA) The 2θ range was 15° to 75°. , Step size=0.01, wavelength λ1=1.540562×10 -10 m, λ2 are No setting, Monochromator was set to single. The turn was similarly created from the crystal structure information described in Non-Patent Document 3. The crystal structure pattern was estimated from the XRD pattern of the positive electrode active material of one embodiment of the present invention. TOPAS ver.3 (crystal structure analysis software manufactured by Bruker) was used to filter the The XRD patterns were generated as well as the others.

[0186] As shown in Figure 9, in the O3' type crystal structure, 2θ = 19.30 ± 0.20° (19.1 0° or more and 19.50° or less), and 2θ=45.55±0.10° (45.45° or more) Diffraction peaks appear at 2θ=19.30±45.65°. 0.10° (19.20° to 19.40°), and 2θ = 45.55 ± 0.05 However, a sharp diffraction peak appears at 45.50° or more and 45.60° or less. As shown, in the H1-3 type crystal structure and CoO2 (P-3m1, O1), peaks are formed at these positions. Therefore, when charged at high voltage, 2θ=19.30±0.20° The appearance of peaks at 2θ=45.55±0.10° is a positive example of one embodiment of the present invention. This can be said to be a characteristic of the electrode active material.

[0187] This shows the crystal structure at charge depth 0 and the crystal structure when charged at high voltage, and the diffraction peaks of the XRD More specifically, the positions where the main diffraction peaks of both are close to each other. The difference in the positions at which peaks appear is 2θ = 0.7 or less, and more preferably 2θ = 0.5 or less.

[0188] The positive electrode active material of one embodiment of the present invention has an O3'-type crystal structure when charged at a high voltage. However, not all particles need to have the O3' type crystal structure. Other crystal structures may be included. However, some of the crystals may be amorphous. However, if Rietveld analysis is performed on the XRD pattern, When the above process is carried out, it is preferable that the O3' type crystal structure is 50 wt% or more, and 60 wt% or more. It is more preferable that the content of the O3'-type crystal is 66 wt % or more, and it is further preferable that the content of the O3'-type crystal is 66 wt % or more. The structure is 50 wt% or more, more preferably 60 wt% or more, and even more preferably 66 wt% or more. If the positive electrode active material has the above-mentioned properties, it can have sufficiently excellent cycle characteristics.

[0189] In addition, even after more than 100 charge / discharge cycles from the start of measurement, Rietveld analysis was performed. In this case, the O3' type crystal structure is preferably 35 wt% or more, and more preferably 40 wt% or more. It is more preferable that the content is 43 wt % or more, and even more preferable that the content is 43 wt % or more.

[0190] In addition, the crystallite size of the O3'-type crystal structure of the positive electrode active material particles is The charge / discharge ratio is only about 1 / 10 of that of CoO2(O3). Even under the XRD measurement conditions, a clear peak of the O3' type crystal structure was observed after high-voltage charging. On the other hand, in simple LiCoO2, some of the structure may be similar to the O3' type crystal structure. Even if the crystallite size is increased, the crystallite size becomes smaller and the peak becomes broader and smaller. It can be determined from the half-width of the RD peak.

[0191] In this specification, the theoretical capacity of the positive electrode active material is the capacity of the positive electrode active material that can be inserted and removed. The theoretical capacity of LiCoO2 is 274 mAh / g, the theoretical capacity of LiNiO2 is 274mAh / g, and the theoretical capacity of LiMn2O4 is It is 148mAh / g.

[0192] In this specification, the depth of charge when all intercalable and detachable lithium is intercalated is The depth of charge when all the intercalable lithium in the positive electrode active material is deintercalated is defined as 0, and the depth of charge when all the intercalable lithium in the positive electrode active material is deintercalated is defined as 1. In addition, the positive electrode active material with a charge depth of 0.7 or more and 0.9 or less is charged at a high voltage. In addition, a positive electrode active material with a charge depth of 0.06 or less, or a high The positive electrode active material is discharged to 90% or more of its charge capacity from the charged state. This is referred to as the discharged positive electrode active material.

[0193] Discharge rate is the relative ratio of the discharge current to the battery capacity, and is expressed in units of C. For a battery with a rated capacity of X (Ah), the current equivalent to 1C is X (A). 2X (A ) is said to be discharged at 2C, and when discharged at a current of X / 5(A), In this case, the battery was discharged at 0.2C. The charging rate was also the same, 2X(A). When charging with a current of X / 5(A), it is said to be charging at 2C. In this case, the battery was charged at 0.2C.

[0194] Constant current charging refers to a method of charging at a constant charge rate. For example, when the charging reaches the upper voltage limit, the voltage is kept constant and charging is continued. For example, discharge refers to a method of discharging at a constant discharge rate.

[0195] In this specification, a value in the vicinity of a certain value A means a value between 0.9 A and 1.1 A. That is what I will say.

[0196] In this specification and the like, a secondary battery using the positive electrode and the positive electrode active material of one embodiment of the present invention In some cases, lithium metal is used as the counter electrode, but the secondary battery of one embodiment of the present invention does not use this. The negative electrode may be made of other materials, such as graphite or lithium titanate. The positive electrode and the positive electrode active material according to one embodiment of the present invention have a crystalline structure that is resistant to breakdown even after repeated charge and discharge, and are excellent in The properties of the negative electrode, such as the ability to obtain satisfactory cycle characteristics, are not affected by the material of the negative electrode. For secondary batteries, the charging voltage is higher than the general charging voltage of about 4.7V with lithium as the counter electrode. Although examples of charging and discharging at a low voltage are shown, charging and discharging at a lower voltage may also be performed. When charging and discharging at a low voltage, the cycle characteristics may be even better than those shown in this specification. It is expected.

[0197] (Embodiment 3) In this embodiment, a lithium-ion secondary battery including a positive electrode active material of one embodiment of the present invention will be described. A secondary battery consists of an outer casing, a current collector, an active material (positive electrode active material or negative electrode active material), a conductor, and a The electrolyte contains at least an electrolytic auxiliary agent and a binder. In the case of a secondary battery using an electrolyte, there is a positive electrode, a negative electrode, and a separator between the positive and negative electrodes. A parameter is provided.

[0198] [Positive electrode] The positive electrode includes a positive electrode active material layer and a positive electrode current collector. It is preferable that the positive electrode active material 100 is contained, and it may further contain a binder, a conductive additive, etc. good.

[0199] FIG. 12(A) shows an example of a schematic cross-sectional view of a positive electrode.

[0200] The current collector 550 is a metal foil, and a positive electrode is formed by applying a slurry onto the metal foil and drying it. After drying, further pressing may be performed. The positive electrode is formed by attaching an active material to the current collector 550. A material layer is formed.

[0201] The slurry is a material liquid used to form an active material layer on the current collector 550. Both contain at least an active material, a binder, and a solvent, and preferably further contain a conductive additive. The slurry is also called electrode slurry or active material slurry. When forming a positive electrode active material layer, a positive electrode slurry is used, and when forming a negative electrode active material layer, It is sometimes called a negative electrode slurry.

[0202] The conductive additive is also called a conductive agent or conductive material, and is made of a carbon material. By attaching a conductive additive to the active material, the active materials are electrically connected to each other, thereby increasing the conductivity. Note that "adhesion" only refers to the physical adhesion between the active material and the conductive additive. When covalent bonds occur, or when bonds are formed by van der Waals forces, the active material When the conductive additive covers part of the surface, or when the conductive additive is embedded in the surface irregularities of the active material, This concept also includes cases where the device is electrically connected even if it is not in contact with the device.

[0203] Carbon black (furnace) is a typical example of a carbon material used as a conductive additive. black, acetylene black, graphite, etc.

[0204] In FIG. 12(A), acetylene black 553 is shown as the conductive additive. In the case of 12(A), a second active material having a particle size smaller than that of the positive electrode active material 100 shown in the first embodiment is used. This shows an example of mixing particles of different sizes. This can be used as a positive electrode active material layer, and the charge / discharge capacity of the secondary battery can be increased. Positive electrode active material 100 described in Embodiment 1 corresponds to active material 561 in FIG.

[0205] In order to bond a current collector 550 such as a metal foil to an active material as a positive electrode of a secondary battery, It contains a binder (resin). Binders are also called binding agents. Binders are polymeric materials. If the binder is added in large amounts, the ratio of the active material in the positive electrode decreases, Therefore, the amount of binder is kept to a minimum. In the above, the active material 561, the second active material 562, and the acetylene black 553 are filled. The dark areas refer to voids or binder.

[0206] Although FIG. 12A shows an example in which the active material 561 is spherical, there is no particular limitation. The cross-sectional shape of the active material 561 may be an ellipse, a rectangle, a trapezoid, It may be a cone, a rectangle with rounded corners, or an asymmetrical shape.

[0207] FIG. 12B shows examples in which the active material 561 has various shapes. 2(B) shows an example different from that shown in FIG. 12(A).

[0208] In addition, in the positive electrode of FIG. 12(B), graphene is used as a carbon material used as a conductive additive. 554 is used.

[0209] Graphene has amazing electrical, mechanical and chemical properties, It is a carbon material that is expected to be applied in various fields, such as field effect transistors and solar cells. be.

[0210] FIG. 12(B) shows an active material 561, graphene 554, and acetylene black on a current collector 550. 553 is formed as a positive electrode active material layer.

[0211] In addition, the process of mixing graphene 554 and acetylene black 553 to obtain electrode slurry In this case, the weight of the carbon black to be mixed is preferably 1.5 times or more and 20 times or less than that of the graphene. The weight is preferably 2 times or more and 9.5 times or less.

[0212] In addition, when the mixture of graphene 554 and acetylene black 553 is within the above range, the slurry - During preparation, the dispersion stability of Acetylene Black 553 is excellent, and agglomerations are unlikely to occur. When the mixture of graphene 554 and acetylene black 553 is within the above range, This allows for a higher electrode density than a positive electrode that uses only Black 553 as a conductive additive. By increasing the pole density, it is possible to increase the capacity per unit of weight. The gravimetric density of the positive electrode active material layer can be higher than 3.5 g / cc. In addition, the positive electrode active material 100 described in Embodiment 1 is used for the positive electrode, and the graphene 554 and the By mixing Cetylene Black 553 in the above range, the secondary battery will have a higher capacity. This is desirable as it is expected to have a synergistic effect.

[0213] In addition, although the electrode density is lower than that of a positive electrode that uses only graphene as a conductive additive, The mixture of the first carbon material (graphene) and the second carbon material (acetylene black) is within the above range. This allows for rapid charging. is used as the positive electrode, and the mixture of graphene 554 and acetylene black 553 is within the above range. This will result in a synergistic effect in that the secondary battery will become more stable and be able to handle even faster charging. The effect is promising and desirable.

[0214] These features are effective for use as a secondary battery for vehicles.

[0215] Increasing the number of secondary batteries increases the vehicle's weight, which increases the amount of energy required to move. By using high-density secondary batteries, it is possible to install secondary batteries of the same weight. The range can be maintained with almost no change in the vehicle's total weight.

[0216] In addition, as the capacity of the vehicle's secondary battery increases, more power is required to charge it, so it is necessary to charge it in a short time. It is also desirable to temporarily generate electricity when braking the vehicle. When charging it, so-called regenerative charging is done under high-rate charging conditions, Good rate characteristics are required for secondary batteries for vehicles.

[0217] The positive electrode active material 100 shown in the first embodiment is used for the positive electrode, and acetylene black and graphite are mixed. By optimizing the mixture ratio of phene, it is possible to achieve high electrode density and the appropriate gap required for ion conduction. This makes it possible to create a space between the battery and the battery, and to develop an in-vehicle battery with high energy density and good output characteristics. A secondary battery for use can be obtained.

[0218] This configuration is also effective in mobile information terminals, and the positive electrode active material 1 shown in the first embodiment 00 is used for the positive electrode, and the mixture ratio of acetylene black and graphene is set in the optimal range. This allows the secondary battery to be made smaller and have a higher capacity. By adjusting the mixture ratio of phenate to the optimum range, it is also possible to rapidly charge portable information terminals.

[0219] In FIG. 12B, the active material 561, the graphene 554, and the acetylene black 5 The unfilled areas at 53 represent voids or binder. The voids are the electrolyte penetration areas. Too much is necessary, but if there is too little, the electrode density will decrease, and if there is too little, the electrolyte will not penetrate If voids remain after the battery is fabricated, the energy density will decrease.

[0220] The positive electrode active material 100 obtained in the first embodiment is used for the positive electrode, and acetylene black and By optimizing the mixing ratio of lathane, it is possible to achieve high density electrodes and the appropriate gap required for ion conduction. This makes it possible to create a secondary battery with high energy density and good output characteristics. You can get a battery.

[0221] FIG. 12(C) shows an example of a positive electrode using carbon nanotubes 555 instead of graphene. FIG. 12(C) shows an example different from FIG. 12(B). Using Tube 555 prevents the aggregation of carbon black such as Acetylene Black 553. , the dispersibility can be improved.

[0222] In FIG. 12(C), the active material 561, the carbon nanotube 555, the acetylene The areas not filled with black 553 refer to voids or binder.

[0223] Another example of the positive electrode is shown in FIG. 12(D). In FIG. 12(C), graphene In this example, carbon nanotubes 555 are used in addition to graphene 554. 4 and carbon nanotubes 555, such as acetylene black 553. This prevents the carbon black from agglomerating and improves its dispersibility.

[0224] In FIG. 12(D), the active material 561, the carbon nanotube 555, the graphene 554, the area not filled with acetylene black 553 refers to voids or binder. are.

[0225] Using any one of the positive electrodes shown in FIGS. 12(A) to 12(D), a separator is placed on the positive electrode. The stack of the negative electrode on the separator is placed in a container (such as an outer packaging or metal can) that contains the stack. A secondary battery can be produced by filling the container with an electrolyte.

[0226] Although the above configuration shows an example of a secondary battery using an electrolytic solution, the present invention is not particularly limited.

[0227] For example, a semi-solid battery or an all-solid battery can be manufactured using the positive electrode active material 100 shown in the first embodiment. You can also do this.

[0228] In this specification, a semi-solid battery is a battery in which at least one of the electrolyte layer, the positive electrode, and the negative electrode is made of a semi-solid material. In this context, semi-solid does not mean that the ratio of solid material is 50%. A semi-solid is a substance that has the properties of a solid, such as small volume change, but is also flexible. This means that the liquid has some of the properties similar to a liquid, such as being easily absorbed. It can be a single material or multiple materials. For example, a liquid material can be mixed with a porous solid material. It may be a wetted material.

[0229] In this specification and the like, a polymer electrolyte secondary battery refers to a secondary battery having a polymer in the electrolyte layer between the positive electrode and the negative electrode. The polymer electrolyte secondary battery includes a dry (or solid) polymer electrolyte battery and a polymer gel electrolyte battery. The polymer electrolyte secondary battery may also be called a semi-solid battery. When a semi-solid battery is fabricated using the positive electrode active material 100 shown in Embodiment 1, the semi-solid battery becomes a secondary battery with a large charge-discharge capacity. Also, a semi-solid battery with a high charge-discharge voltage can be obtained. Or, a semi-solid battery with high safety or reliability can be realized. Moreover, the positive electrode active material described in Embodiment 1 may be mixed with other positive electrode active materials and used. Examples of other positive electrode active materials include composite oxides having an olivine-type crystal structure, a layered rock salt-type crystal structure, or a spinel-type crystal structure. For example, compounds such as LiFePO4, LiFeO2, LiNiO2, LiMn2O4, V2O5, Cr2O5, and MnO2 can be cited.

[0230] When fabricating a semi-solid battery using the positive electrode active material 100 shown in Embodiment 1, the semi-solid battery becomes a secondary battery with a large charge-discharge capacity. Also, a semi-solid battery with a high charge-discharge voltage can be obtained. Or, a semi-solid battery with high safety or reliability can be realized. Moreover, the positive electrode active material described in Embodiment 1 may be mixed with other positive electrode active materials and used. Examples of other positive electrode active materials include composite oxides having an olivine-type crystal structure, a layered rock salt-type crystal structure, or a spinel-type crystal structure. For example, compounds such as LiFePO4, LiFeO2, LiNiO2, LiMnZ04, V2O5, Cr2O5, and MnO2 can be cited.

[0231] Moreover, as another positive electrode active material, it is preferable to mix a lithium-containing material having a spinel-type crystal structure containing manganese such as LiMn2O4 with lithium nickelate (LiNiO2 or LiNiMO2 (0 < x < 1), M = Co, Al, etc.). By adopting this configuration, the characteristics of the secondary battery can be improved.

[0232] Examples of other positive electrode active materials include composite oxides having an olivine-type crystal structure, a layered rock salt-type crystal structure, or a spinel-type crystal structure. For example, compounds such as LiFePO4, LiFeO2, LiNiO2, LiMn2O4, V2O5, Cr2O5, and MnO2 can be cited. Moreover, as another positive electrode active material, it is preferable to mix a lithium-containing material having a spinel-type crystal structure containing manganese such as LiMn2O4 with lithium nickelate (LiNiO2 or LiNiMO2 (0 < x < 1), M = Co, Al, etc.). By adopting this configuration, the characteristics of the secondary battery can be improved. Moreover, as another positive electrode active material, a composition formula of Li It may be cited.

[0233] Moreover, as another positive electrode active material, a composition formula of Li Moreover, as another positive electrode active material, it is preferable to mix a lithium-containing material having a spinel-type crystal structure containing manganese such as LiMn2O4 with lithium nickelate (LiNiO2 or LiNiMO2 (0 < x < 1), M = Co, Al, etc.). By adopting this configuration, the characteristics of the secondary battery can be improved. 1-x M x O 2(0 < x < 1) (M = Co, Al, etc.)) is preferably mixed. By adopting this configuration, the characteristics of the secondary battery can be improved. Moreover, as another positive electrode active material, a composition formula of Li

[0234] Moreover, as another positive electrode active material, a composition formula of Li aMn b M c O d Lithium can be expressed as A manganese composite oxide can be used. Here, the element M is an element other than lithium and manganese. It is preferable to use a metal element selected from the group consisting of silicon and phosphorus, and nickel is preferable. Furthermore, when measuring the entire particle of the lithium manganese composite oxide, 0 <a / (b+c)<2、かつc>0 during discharge, and 0.26≦(b+c) / d<0.5 It is preferable that the metal and silicon of the entire lithium manganese composite oxide particle be The composition of carbon, phosphorus, etc. is measured using, for example, an ICP-MS (inductively coupled plasma mass spectrometer). The oxygen composition of the entire lithium manganese composite oxide particle can be, for example, It can be measured using EDX (energy dispersive X-ray analysis). Combined with PMS analysis, molten gas analysis and XAFS (X-ray absorption fine structure) analysis can be used to evaluate the valence of The lithium manganese composite oxide can be determined by using at least It refers to an oxide containing lithium and manganese, and also contains chromium, cobalt, aluminum, and nickel. , iron, magnesium, molybdenum, zinc, indium, gallium, copper, titanium, niobium, It may contain at least one element selected from the group consisting of silicon, phosphorus, etc. good.

[0235] <Binder> 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.​

[0236] 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.

[0237] Alternatively, the binder may be polystyrene, polymethyl acrylate, or polymethyl methacrylate. (Polymethyl methacrylate, PMMA), Sodium polyacrylate, Polyvinyl Alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, Polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene Polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), ethylene propylene diene polymer, It is preferable to use materials such as polyvinyl acetate and nitrocellulose.

[0238] The binder may be used in combination with two or more of the above.

[0239] For example, a material having a particularly excellent viscosity adjusting effect may be used in combination with other materials. For example, rubber materials have excellent adhesive strength and elasticity, but it is difficult to adjust the viscosity when mixed with a solvent. In such cases, for example, mixing with a material that has a particularly excellent viscosity adjusting effect can be As a material having a particularly excellent viscosity adjusting effect, for example, a water-soluble polymer is preferably used. Furthermore, examples of water-soluble polymers that are particularly effective in adjusting viscosity include the aforementioned polysaccharides, such as cellulose, cellulose acetate, and the like. Carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxymethylcellulose Cellulose derivatives such as hydroxypropyl cellulose, diacetyl cellulose, and regenerated cellulose Conductive materials and starch can be used.

[0240] 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.

[0241] 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.

[0242] When the binder that covers or contacts the surface of the active material forms a film, it is called a passive film. It is expected that the passive film will also play a role in suppressing the decomposition of the electrolyte. It is a film with no electrical conductivity or extremely low electrical conductivity, and is When a dynamic membrane is formed, it is possible to suppress the decomposition of the electrolyte at the battery reaction potential. In addition, the passive film suppresses electrical conductivity while allowing lithium ions to conduct. And even more desirable.

[0243] <Positive electrode current collector> The current collector may be made of metals such as stainless steel, gold, platinum, aluminum, titanium, or any of these metals. Highly conductive materials such as alloys can be used. The materials used for the positive electrode current collector are: It is preferable that the material does not dissolve at the potential of the positive electrode. Uses aluminum alloys containing elements such as tungsten and molybdenum that improve heat resistance. It may 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 and titanium. , hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, There are ballast, nickel, etc. Current collectors are available in foil, plate, sheet, mesh, and punched metal. The current collector may be in the form of a metal foil, an expanded metal foil, or the like. It is recommended to use one with a thickness of 30 μm or more.

[0244] [Negative electrode] The negative electrode has a negative electrode active material layer and a negative electrode current collector. The conductive layer may further contain a conductive additive and a binder.

[0245] <Negative electrode active material> As the negative electrode active material, for example, an alloy-based material or a carbon-based material can be used.

[0246] 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.

[0247] In this specification, SiO refers to, for example, silicon monoxide. Alternatively, SiO refers to SiO x Here, x preferably has a value of 1 or close to 1. For example, x is preferably 0.2 or more and 1.5 or less, and more preferably 0.3 or more and 1.2 or less.

[0248] Carbon materials include graphite, easily graphitizable carbon (soft carbon), and non-graphitizable carbon (hard carbon). carbon nanotubes, graphene, carbon black, etc. may be used. .

[0249] 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.

[0250] 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 lithium-ion secondary batteries using graphite to exhibit high operating voltages. Furthermore, graphite has a relatively high capacity per unit volume and a relatively small volume expansion. It is preferable because it has advantages such as being inexpensive and being safer than metallic lithium.

[0251] 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.

[0252] 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, Li2.6 Co 0.4 N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3 ) And preferable.

[0253] 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.

[0254] 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.

[0255] 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.

[0256] <Negative electrode current collector> The negative electrode current collector may be made of the same material as the positive electrode current collector, or may be made of copper. The electrode current collector is preferably made of a material that does not alloy with carrier ions such as lithium.

[0257] [Separator] A separator is placed between the positive and negative electrodes. The separator can be made of paper or other materials. Cellulose-containing fibers, nonwoven fabrics, glass fibers, ceramics, or nylon (polyethylene glycol) amide), vinylon (polyvinyl alcohol fiber), polyester, acrylic, polyvinyl alcohol It is possible to use a material made of synthetic fibers using olefin or polyurethane. The separator is preferably processed into a bag shape and placed so as to encase either the positive electrode or the negative electrode. I wish.

[0258] The separator may have a multi-layer structure. For example, the separator may be made of an organic material such as polypropylene or polyethylene. The material film is made of ceramic material, fluorine material, polyamide material, or a mixture of these. As a ceramic material, for example, aluminum oxide can be used. Examples of the fluorine-based material include fluorine particles, silicon oxide particles, etc. PVDF, polytetrafluoroethylene, etc. can be used. For example, nylon, aramid (meta-aramid, para-aramid), etc. can be used. can.

[0259] 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.

[0260] For example, a polypropylene film is coated on both sides with a mixture of aluminum oxide and aramid. Alternatively, aluminum oxide may be applied to the surface of the polypropylene film that comes into contact with the positive electrode. Alternatively, the surface of the negative electrode that comes into contact with the carbon black may be coated with a mixed material of carbon black and aramid, and then coated with a fluorine-based material.

[0261] 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.

[0262] [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.

[0263] 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.

[0264] 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, LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, Lithium Lithium salts such as mubis(oxalate)borate (Li(C2O4)2, LiBOB) One or more of these may be used in any combination and ratio. .

[0265] 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.

[0266] In addition, the electrolyte contains vinylene carbonate, propane sultone (PS), and tert-butyl ether. Benzene (TBB), Fluoroethylene carbonate (FEC), Lithium bis(oxalate) Lithium borate (LiBOB), as well as dinitriles such as succinonitrile and adiponitrile Additives such as compounds may be added. The concentration of the additives is, for example, 0.1 to the total solvent. It is sufficient to set the content to between 5 wt% and 5 wt%.

[0267] Alternatively, a polymer gel electrolyte may be used in which a polymer is swollen with an electrolytic solution.

[0268] The use of polymer gel electrolytes increases safety against leakage, etc. It is possible to make the device thinner and lighter.

[0269] The polymers that can be gelled include silicone gel, acrylic gel, acrylonitrile gel, Polyethylene oxide gel, polypropylene oxide gel, fluorine polymer For example, a polyalkoxysilane such as polyethylene oxide (PEO) can be used. Polymers with polyethylene oxide structure, PVDF, polyacrylonitrile, etc. For example, PVDF and hexafluoropropylene copolymers containing PVDF and hexafluoropropylene copolymers can be used. PVDF-HFP, a copolymer of PVDF and HFP, can be used. The polymer to be applied may have a porous shape.

[0270] 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.

[0271] Therefore, the positive electrode active material 100 obtained in the first embodiment can be applied to all-solid-state batteries. By applying the cathode slurry or electrode to an all-solid-state battery, high safety and excellent characteristics are achieved. A good all-solid-state battery can be obtained.

[0272] [Exterior body] The exterior of the secondary battery is made of a metal material such as aluminum or a resin material. Also, a film-like outer casing can be used. , such as polyethylene, polypropylene, polycarbonate, ionomer, polyamide On the film made of such material, a highly flexible material such as aluminum, stainless steel, copper, or nickel is applied. A metal thin film is provided, and a polyamide resin or polyester is further provided on the metal thin film as the outer surface of the exterior body. A film having a three-layer structure provided with an insulating synthetic resin film such as a terephthalate resin can be used.

[0273] This embodiment can be used in combination with other embodiments.

[0274] (Fourth embodiment) In this embodiment, a positive electrode or a negative electrode manufactured by the manufacturing method described in the previous embodiment is used. Examples of various shapes of secondary batteries having electrodes will be described.

[0275] [Coin-type secondary battery] An example of a coin-type secondary battery will be described. FIG. 13(A) shows a coin-type (single-layer flat type) 13(B) is an external view of the secondary battery, and FIG. 13(C) is a cross-sectional view of the same. Coin-type secondary batteries are mainly used in small electronic devices.

[0276] In Figure 13(A), the overlapping of the components (vertical and positional relationships) is shown for ease of understanding. Therefore, Fig. 13(A) and Fig. 13(B) are completely identical pairs. It is not a diagram.

[0277] In FIG. 13(A), a positive electrode 304, a separator 310, a negative electrode 307, a spacer 322, a wafer The shears 312 are stacked on top of each other and sealed with a negative electrode can 302 and a positive electrode can 301. In FIG. 16(A), the gasket for sealing is not shown. The washer 312 is used to protect the inside of the positive electrode can 301 and the negative electrode can 302 when they are crimped together. The spacer 322 and washer 312 are used to fix the position inside the Use a non-insulating material.

[0278] The positive electrode 304 has a laminated structure in which a positive electrode active material layer 306 is formed on a positive electrode current collector 305. .

[0279] To prevent short circuit between the positive and negative electrodes, a separator 310 and a ring-shaped insulator 313 are attached to the positive electrode 304. The separator 310 is disposed so as to cover the side and top surfaces of the positive electrode 304. It has a large planar area.

[0280] FIG. 13(B) is a perspective view of the completed coin-type secondary battery.

[0281] 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 307 is formed by a negative electrode active material layer 309 formed by stacking the negative electrode active material layer 309. Alternatively, a lithium metal foil or a lithium-aluminum alloy foil may be used.

[0282] 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.

[0283] 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 caused by electrolytes. The positive electrode can 301 is the positive electrode 304, and the negative electrode can 302 is the negative electrode. 307 and electrically connected to each other.

[0284] The negative electrode 307, the positive electrode 304 and the separator 310 are immersed in an electrolyte solution, and as shown in FIG. As shown, the positive electrode can 301 is placed downwards, and the positive electrode 304, separator 310, negative electrode 307, and negative electrode The cans 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are secured together with a gasket 303 interposed therebetween. The coin-type secondary battery 300 is manufactured by crimping.

[0285] By using it as a secondary battery, it has a high capacity, a high charge / discharge capacity, and excellent cycle characteristics. The coin-type secondary battery 300 can be formed. In the case of a secondary battery, the separator 310 may be unnecessary.

[0286] [Cylindrical secondary battery] An example of a cylindrical secondary battery will be described with reference to FIG. 14(A). As shown in FIG. 14(A), the battery 6 has a positive electrode cap (battery lid) 601 on the top surface, and The positive electrode cap 601 and the battery can (external can) 602 are disposed on the bottom surface of the battery. The container 602 is insulated from the container 602 by a gasket (insulating packing) 610.

[0287] FIG. 14(B) is a schematic diagram showing a cross section of a cylindrical secondary battery. The cylindrical secondary battery has a positive electrode cap (battery lid) 601 on the top surface and The positive electrode cap and the battery can (external can) 602 are are insulated by a gasket (insulating packing) 610.

[0288] Inside a hollow cylindrical battery can 602, a strip-shaped positive electrode 604 and a negative electrode 606 are placed between a separator 6 The battery element is wound around the center of the battery. The battery can 602 is wound around an axis. One end is closed and the other end is open. The can 602 is made of a metal such as nickel, aluminum, or titanium that is resistant to corrosion by the electrolyte. or alloys of these and other metals (e.g., stainless steel, etc.) In addition, to prevent corrosion by the electrolyte, nickel, aluminum, etc. are used in the battery can 6. It is preferable to coat the positive electrode, the negative electrode and the separator inside the battery can 602. The battery element with the coil wound around it is sandwiched between a pair of opposing insulating plates 608 and 609. The battery can 602 in which the battery element is provided is filled with a non-aqueous electrolyte (not shown). The non-aqueous electrolyte may be the same as that used in coin-type secondary batteries.

[0289] The positive and negative electrodes used in cylindrical storage batteries are wound, so active materials are formed on both sides of the current collector. It is preferable that

[0290] By using the positive electrode active material 100 obtained in the first embodiment for the positive electrode 604, it is possible to obtain a high capacity and It is possible to obtain a cylindrical secondary battery 616 having a high charge / discharge capacity and excellent cycle characteristics. Cut.

[0291] A positive electrode terminal (positive electrode current collecting lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collecting lead) 607 is connected. The positive terminal 603 is connected to a safety valve mechanism 61. 3, the negative electrode terminals 607 are resistance welded to the bottom of the battery can 602. is a PTC element (Positive Temperature Coefficient The safety valve mechanism 613 is electrically connected to the positive electrode cap 601 via the safety valve mechanism 611. When the internal pressure of the reservoir increases beyond a predetermined threshold, the positive electrode cap 601 and the positive electrode 604 are electrically connected. The PTC element 611 cuts off the electrical connection when the resistance of the PTC element 611 increases. It is a thermal resistor element that increases in resistance and limits the amount of current to prevent abnormal heat generation. PTC elements are made of semiconducting ceramics such as barium titanate (BaTiO3). can be used.

[0292] 14C shows an example of a power storage system 615. The power storage system 615 includes a plurality of secondary batteries. The positive electrode of each secondary battery has a conductor 624 separated by an insulator 625. The conductor 624 is in contact with and electrically connected to the control circuit 62 via the wiring 623. 0. The negative electrodes of the secondary batteries are electrically connected to the The control circuit 620 is electrically connected to a charger that performs charging and discharging. A discharge control circuit and a protection circuit for preventing overcharging or overdischarging can be applied.

[0293] FIG. 14D shows an example of a power storage system 615. The power storage system 615 includes a plurality of secondary batteries. The plurality of secondary batteries 616 are sandwiched between the conductive plate 628 and the conductive plate 614. The plurality of secondary batteries 616 are electrically connected to the conductive plate 628 and the conductive plate 614 by wiring 627. The plurality of secondary batteries 616 may be connected in parallel or in series. They may be connected in parallel and then in series. By configuring a power storage system 615 having a battery 616, it is possible to extract a large amount of power. can.

[0294] A plurality of secondary batteries 616 may be connected in parallel and then further connected in series.

[0295] A temperature control device may be provided between the plurality of secondary batteries 616. When the secondary battery 616 is too cold, the temperature control device cools it down. Therefore, the performance of the power storage system 615 is affected by the outside temperature. It will be less likely to happen.

[0296] 14D, the power storage system 615 is connected to a control circuit 620 via a wiring 621 and a wiring The wiring 621 is electrically connected to the plurality of two electrodes via a conductive plate 628. The wiring 622 is connected to the positive electrode of the secondary battery 616 via the conductive plate 614. are electrically connected to the respective

[0297] [Other examples of secondary battery structures] An example of the structure of the secondary battery will be described with reference to FIGS.

[0298] The secondary battery 913 shown in FIG. 15(A) has a terminal 951 and a terminal 952 provided inside a housing 930. The winding 950 is immersed in an electrolyte solution 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. 15A, the housing 930 is not in contact with the housing 930. For convenience, the housing 930 is shown separated. Although the figure shows the winding body 950, in reality, the winding body 950 is covered by the housing 930, and the terminals 951 and 955 are 2 extends outside the housing 930. The housing 930 is made of a metal material (e.g., aluminum Rubber or resin materials can be used.

[0299] As shown in FIG. 15(B), the housing 930 shown in FIG. 15(A) is made of a plurality of materials. For example, the secondary battery 913 shown in FIG. 15B may be formed by a housing 930a and a housing 930b. The wound body 930 is located in the area surrounded by the housing 930a and the housing 930b. 50 are provided.

[0300] 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. An antenna may be provided inside the housing 930b. For example, a metal material may be used for the housing 930b. can.

[0301] 15(C) shows the structure of the wound body 950. The wound body 950 is made up of a negative electrode 931 The wound body 950 includes a positive electrode 932 and a separator 933. The negative electrode 931 and the positive electrode 932 are stacked on top of each other with the negative electrode 931 and the positive electrode 932 sandwiched therebetween, and the laminated sheet is wound up. The negative electrode 931, the positive electrode 932, and the separator 933 are stacked together to form a wound body. Furthermore, multiple layers may be stacked.

[0302] Further, a secondary battery 913 having a wound body 950a as shown in FIG. The wound body 950a shown in (A) includes a negative electrode 931, a positive electrode 932, and a separator 933. The negative electrode 931 has a negative electrode active material layer 931a. The positive electrode 932 has a positive electrode active material layer 932b. It has a.

[0303] By using the positive electrode active material 100 obtained in the first embodiment for the positive electrode 932, it is possible to obtain a high capacity and The secondary battery 913 can have a high charge / discharge capacity and excellent cycle characteristics.

[0304] The separator 933 has a width greater than that of the negative electrode active material layer 931a and the positive electrode active material layer 932a. The negative electrode active material layer 931a and the positive electrode active material layer 932a are wound so as to overlap each other. In addition, from the viewpoint of safety, the width of the negative electrode active material layer 931a is wider than that of the positive electrode active material layer 932a. Furthermore, the wound body 950a having such a shape is preferable because it is safe and productive. .

[0305] As shown in FIG. 16(B), the negative electrode 931 is ultrasonically bonded, welded, or crimped to a terminal 951. The terminal 951 is electrically connected to the terminal 911a. 932 is electrically connected to a terminal 952 by ultrasonic bonding, welding, or crimping. 952 is electrically connected to terminal 911b.

[0306] As shown in FIG. 16(C), the wound body 950a and the electrolyte are covered by the housing 930. It is preferable to provide a safety valve, an overcurrent protection element, etc. in the housing 930. The safety valve is a valve that opens when the inside of the housing 930 reaches a predetermined internal pressure to prevent the battery from exploding. do.

[0307] As shown in FIG. 16(B), the secondary battery 913 may have a plurality of wound bodies 950a. By using a plurality of wound bodies 950a, the secondary battery 913 can have a larger charge / discharge capacity. The other elements of the secondary battery 913 shown in FIGS. 16(A) and (B) can be The description of the secondary battery 913 shown in (1) to (C) can be taken into consideration.

[0308] <Laminated secondary battery> Next, an example of an external view of a laminated secondary battery is shown in FIG. 17(A) and FIG. 17(B). 17(A) and 17(B) show a positive electrode 503, a negative electrode 506, a separator 507, and a 07, an outer casing 509, a positive electrode lead electrode 510, and a negative electrode lead electrode 511.

[0309] 18(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.

[0310] <Method 1 for producing laminated secondary battery> Here, regarding an example of a method for manufacturing a laminated secondary battery shown in FIG. 17(A), This will be explained with reference to FIG. 18(B) and FIG. 18(C).

[0311] 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. An example of using four sets is shown below. It can also be called a laminate consisting of a negative electrode, a separator, and a positive electrode. The tab regions of 503 are joined together, and the positive electrode lead electrode 510 is joined to the tab region of the positive electrode on the outermost surface. For example, ultrasonic welding may be used for the joining. The regions are joined together, and the negative electrode lead electrode 511 is joined to the tab region of the negative electrode on the outermost surface.

[0312] Next, the negative electrode 506 , the separator 507 and the positive electrode 503 are placed on the exterior body 509 .

[0313] Next, as shown in FIG. 18(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.

[0314] Next, electrolyte 508 (not shown) is introduced into exterior body 509 through an inlet provided in exterior body 509. The electrolyte 508 is introduced into the inside of the electrode 509 under a reduced pressure atmosphere or an inert atmosphere. Finally, the inlet is joined. In this way, the structure shown in FIG. 17(A) is obtained. Alternatively, a laminate type secondary battery 600 as shown in FIG. 17(B) can be fabricated.

[0315] By using the positive electrode active material 100 obtained in the first embodiment for the positive electrode 503, it is possible to obtain a high capacity and The secondary battery 600 can have a high charge / discharge capacity and excellent cycle characteristics.

[0316] <Method 2 for producing laminated secondary batteries> Next, an example of a method for manufacturing the laminated secondary battery 600 shown in FIG. 17(C) will be described with reference to FIG. 19, 20, 21(A) to 21(D), and 22(A) to 22(F) are used. The secondary battery 600 shown in FIG. 17(C) includes a positive electrode 503, a negative electrode 506, a separator The battery 501 includes a motor 507, an exterior body 509, a positive lead electrode 510, and a negative lead electrode 511. The exterior body 509 is sealed with a seal 516 .

[0317] The laminated secondary battery 600 can be manufactured using, for example, a manufacturing apparatus shown in FIG. The manufacturing apparatus 800 shown in FIG. 19 includes a material input chamber 801, a transfer chamber 802, a processing chamber 803, and a Each chamber has various exhaust mechanisms depending on the purpose of use. In addition, each chamber can be connected to various gas supply mechanisms depending on the purpose of use. In order to prevent impurities from entering the manufacturing apparatus 800, a configuration in which the It is preferable that an inert gas is supplied into the manufacturing apparatus 800. The gas supplied to the inside of the manufacturing equipment 800 is purified to a high purity by a gas purifier before being introduced into the manufacturing equipment 800. The material input chamber 801 is for inserting the positive electrode, the separator, the negative electrode, , and the like into the manufacturing apparatus 800. The transfer chamber 802 is a room for transferring the outer packaging body and the like into the manufacturing apparatus 800. The processing chamber 803 has a stage and an electrolyte dropping mechanism.

[0318] The laminated secondary battery 600 is fabricated as follows. This is a room for taking out the fabricated secondary battery to the outside of the manufacturing apparatus 800.

[0319] First, the exterior body 509b is placed on the stage 831 of the processing chamber 803, and then the exterior body 50 The positive electrode 503 is placed on the substrate 9b (FIGS. 21(A) and 21(B)). Electrolyte 525a is dropped onto the positive electrode 503 from the electrode 4 (FIGS. 21(C) and 21(D)). FIG. 21(D) is a cross section corresponding to the dashed line AB in FIG. 21(C). To avoid clutter, the description of stage 831 may be omitted. For example, any one of the following methods may be used: dispense method, spray method, inkjet method, etc. In addition, the ODF (One Drop Fill) method is used to drip the electrolyte. It is possible.

[0320] The nozzle 834 is moved to drip the electrolyte 525a onto the entire surface of the positive electrode 503. Alternatively, by moving the stage 831, the entire surface of the positive electrode 503 can be covered with the liquid. The electrolyte 525a may be dripped in this manner.

[0321] The electrolyte is dropped from a position that is greater than 0 mm and less than 1 mm from the surface to be dropped. It is preferable that this be done.

[0322] It is also preferable to appropriately adjust the viscosity of the electrolyte dropped from the nozzle or the like. Viscosity ranges from 0.3 mPa·s to 1000 mPa·s at room temperature (25°C) It can be dripped from the nozzle as long as it is within the specified range.

[0323] In addition, the viscosity of the electrolyte changes depending on the temperature of the electrolyte, so the temperature of the electrolyte to be dropped must also be adjusted appropriately. The temperature of the electrolyte is preferably adjusted to a temperature above the melting point and below the boiling point of the electrolyte. Below the ignition point is preferred.

[0324] Next, a separator 507 is placed on the positive electrode 503 so as to overlap the entire surface of the positive electrode 503. Next, the electrolyte 52 is sprayed onto the separator 507 using a nozzle 834 (FIG. 22(A)). 5b is dropped onto the separator 507 (FIG. 22(B)). (FIG. 22(C)). The negative electrode 506 does not protrude from the separator 507 when viewed from above. Then, the electrolyte 525 is sprayed onto the negative electrode 506 using a nozzle 834. Then, the positive electrode 503, the separator 507, and the negative electrode 508 are By further stacking the stacks of 06, the stack 512 shown in FIG. 20 can be produced. Next, the positive electrode 503 and the separator 509 are sealed with the exterior body 509a and the exterior body 509b. 07, and the negative electrode 506 is sealed (FIGS. 22(E) and 22(F)).

[0325] By arranging a plurality of laminates 512 on the exterior body 509b, multiple panels can be obtained. After sealing the laminate 512 one by one in the sealing area surrounding the laminate 512, By dividing the battery pack at the outside, the plurality of secondary batteries can be separated into individual batteries.

[0326] When sealing, first, a frame-shaped resin layer is formed on the exterior body 509b. At least a part of the resin layer is cured by irradiating at least a part of the resin layer with light. After the light irradiation, sealing is performed by thermocompression or welding. Alternatively, the sealing by thermocompression or welding may be performed without performing the sealing by light irradiation. It is also possible.

[0327] Although FIG. 17(C) shows an example in which the exterior body 509 is sealed on all four sides, FIG. 17(A) and It may be sealed on three sides as shown in FIG. 17(B).

[0328] [Example of a battery pack] FIG. 2 shows an example of a secondary battery pack according to one embodiment of the present invention that can be wirelessly charged using an antenna. 3 will be used to explain.

[0329] FIG. 23(A) is a diagram showing the appearance of the secondary battery pack 531, which has a thin rectangular parallelepiped shape ( (It can also be called a thick flat plate shape.) Figure 23(B) shows the configuration of the secondary battery pack 531. The secondary battery pack 531 includes a circuit board 540 and a secondary battery 513. A label 529 is attached to the secondary battery 513. The circuit board 540 has a sticker The secondary battery pack 531 is fixed by a .

[0330] The inside of the secondary battery 513 may have a structure having a wound body or a structure having a laminated body. That's fine.

[0331] In the secondary battery pack 531, for example, as shown in FIG. 23(B), The circuit board 540 has a control circuit 590. The circuit board 540 is electrically connected to the terminal 514. The circuit board 540 also includes an antenna 517, a positive lead and a negative lead of the secondary battery 513. One of the leads 551 is electrically connected to the other of the positive and negative leads 552 .

[0332] Alternatively, as shown in FIG. 23(C), a circuit system 59 provided on a circuit board 540 0a, and a circuit system 590b electrically connected to the circuit board 540 via the terminal 514. and

[0333] The antenna 517 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, the antenna 517 may be a flat conductor. This flat conductor can function as one of the conductors for electric field coupling. The antenna 517 functions as one of the two conductors of the capacitor. This allows power to be exchanged not only in electromagnetic fields and magnetic fields but also in electric fields. Cut.

[0334] The secondary battery pack 531 has a layer 519 between the antenna 517 and the secondary battery 513. The layer 519 has a function of shielding the electromagnetic field generated by the secondary battery 513, for example. The layer 519 may be made of, for example, a magnetic material.

[0335] This embodiment mode can be freely combined with other embodiment modes.

[0336] (Embodiment 5) In this embodiment, an all-solid-state battery is manufactured using the positive electrode active material 100 obtained in the first embodiment. Here is an example:

[0337] As shown in FIG. 24A, a secondary battery 400 of one embodiment of the present invention includes a positive electrode 410, a solid electrolyte The battery has a porous layer 420 and a negative electrode 430 .

[0338] The positive electrode 410 includes a positive electrode current collector 413 and a positive electrode active material layer 414. The positive electrode active material 411 includes a positive electrode active material 411 and a solid electrolyte 421. The positive electrode active material layer 414 is made of the positive electrode active material 100 obtained in the first embodiment. and a binder.

[0339] The solid electrolyte layer 420 includes a solid electrolyte 421. The solid electrolyte layer 420 is connected to the positive electrode 410. The negative electrode 430 is located between the positive electrode active material 411 and the negative electrode active material 431. It is an area.

[0340] The negative electrode 430 includes a negative electrode current collector 433 and a negative electrode active material layer 434. The negative electrode active material layer 434 has a negative electrode active material 431 and a solid electrolyte 421. The negative electrode 430 may contain an auxiliary agent and a binder. As shown in FIG. 24(B), the negative electrode 430 does not have a solid electrolyte 421. The use of metallic lithium in the negative electrode 430 improves the energy density of the secondary battery 400. This is preferable.

[0341] The solid electrolyte 421 of the solid electrolyte layer 420 may be, for example, a sulfide-based solid electrolyte, an acid A carbide-based solid electrolyte, a halide-based solid electrolyte, or the like can be used.

[0342] Sulfide-based solid electrolytes include thiosilicon-based (Li 10 GeP2S 12 , Li 3.25 Ge 0.25 P 0.75 S4, etc.), sulfide glass (70Li2S・30P2S5, 30Li2 S·26B2S3·44LiI, 63Li2S·38SiS2·1Li3PO4, 57L i2S・38SiS2・5Li4SiO4, 50Li2S・50GeS2, etc.), sulfide crystals Crystallized glass (Li7P3S 11 , Li 3.25 P 0.95 S4, etc.) are included. Solid electrolytes have high conductivity, can be synthesized at low temperatures, and are relatively soft. This has the advantage that the conductive path is easily maintained even after charging and discharging.

[0343] Oxide-based solid electrolytes include materials with a perovskite crystal structure (La 2 / 3-x Li 3x TiO3, etc.), materials with NASICON-type crystal structure (Li 1-Y Al Y Ti 2- Y (PO4)3, etc.), materials with garnet-type crystal structure (Li7La3Zr2O 12 etc. ), materials with LISICON-type crystal structure (Li 14 ZnGeO 16 etc.), LLZO (Li7La3Zr2O 12 ), oxide glass (Li3PO4-Li4SiO4, 50L i4SiO4·50Li3BO3, etc.), oxide crystallized glass (Li 1.07 Al 0.69 Ti 1.46 (PO4)3, Li 1.5 Al 0.5 Ge 1.5(PO4)3, etc. Oxide-based solid electrolytes have the advantage of being stable in the atmosphere.

[0344] Halide solid electrolytes include LiAlCl4, Li3InBr6, LiF, and LiCl These halide-based solid electrolytes are also used as porous Composite materials filled into the pores of aluminum oxide and porous silica can also be used as solid electrolytes. It can be used as such.

[0345] Also, different solid electrolytes may be mixed and used.

[0346] Among them, Li with NASICON type crystal structure 1+x Al x Ti 2-x (PO4)3( 0[x[1] (hereinafter referred to as LATP) is a combination of aluminum and titanium, which is one aspect of the present invention. Since the positive electrode active material used in the secondary battery 400 contains elements that may be contained, the cycle characteristics can be improved. This is desirable as it is expected to have a synergistic effect. In addition, productivity can be improved by reducing the number of processes. In this specification, the NASICON type crystal structure is M2(XO4)3 (M: transition X is a transition metal, and is a compound represented by the formula (X: S, P, As, Mo, W, etc.), and is an MO6 octahedron and XO It refers to a structure in which four tetrahedrons are arranged three-dimensionally with their vertices shared.

[0347] [Shapes of exterior body and secondary battery] The exterior body of the secondary battery 400 according to one embodiment of the present invention can be made of various materials and in various shapes. However, it is preferable that the positive electrode, the solid electrolyte layer, and the negative electrode have a function of applying pressure thereto.

[0348] For example, Figure 25 shows an example of a cell for evaluating materials for all-solid-state batteries.

[0349] FIG. 25(A) is a cross-sectional view of the evaluation cell. The evaluation cell is composed of a lower member 761 and an upper member 762, and a fixing screw and a wing nut 764 that fix them. By rotating it, the electrode plate 753 is pressed and the evaluation material is fixed. An insulator 766 is provided between the lower member 761 and the upper member 762, both of which are made of a material. An O-ring 762 is provided between the upper member 762 and the holding screw 763 for sealing. 65 is provided.

[0350] The material to be evaluated is placed on an electrode plate 751, surrounded by an insulating tube 752, and an electric It is pressed by the electrode plate 753. The figure is shown in Figure 25(B).

[0351] As an example of the evaluation material, a stack of a positive electrode 750a, a solid electrolyte layer 750b, and a negative electrode 750c is shown. The cross-sectional view is shown in FIG. 25(C). The same symbols are used wherever possible.

[0352] The electrode plate 751 and the lower member 761 electrically connected to the positive electrode 750a are It can be said that this corresponds to a terminal. The electrode plate 753 and the upper member 762 can be said to correspond to the negative terminal. The evaluation material is subjected to pressure via the electrode plate 751 and the electrode plate 753, and the electrical resistance is measured. can be measured.

[0353] In addition, a package with excellent airtightness may be used for the exterior body of the secondary battery according to one embodiment of the present invention. For example, a ceramic package or a resin package can be used. In addition, when sealing the exterior body, it is necessary to shut out the outside air and seal it in a sealed atmosphere, for example, in a glove box. It is preferable to carry out the treatment in a gas chamber.

[0354] FIG. 26(A) shows a secondary battery of one embodiment of the present invention having an exterior body and a shape different from those in FIG. 25. The secondary battery in FIG. 26(A) has external electrodes 771 and 772 and a plurality of packs. It is sealed with an exterior body having a cage member.

[0355] An example of a cross section taken along the dashed line in FIG. 26(A) is shown in FIG. 26(B). The laminate having the solid electrolyte layer 750b and the negative electrode 750c is formed by providing an electrode layer 773a on a flat plate. The package member 770a is a frame-shaped package member 770b, and the electrode layer 7 The package member 770c on which the semiconductor device 73b is provided is enclosed and sealed. The package members 770a, 770b, and 770c are made of an insulating material, such as a resin material or ceramic. Mix can be used.

[0356] The external electrode 771 is electrically connected to the positive electrode 750a via the electrode layer 773a, The external electrode 772 functions as a positive terminal. It is electrically connected to electrode 750c and functions as the negative terminal.

[0357] By using the positive electrode active material 100 obtained in the first embodiment, high energy density and good It is possible to realize an all-solid-state secondary battery with high output characteristics.

[0358] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0359] (Sixth embodiment) This embodiment is an example different from the cylindrical secondary battery shown in FIG. 14(D). C) is used to show an example of applying it to an electric vehicle (EV).

[0360] The electric vehicle includes first batteries 1301a and 1301b as main driving secondary batteries. b and a second battery that powers an inverter 1312 that starts the motor 1304. The second battery 1311 is a cranking battery (starter battery). The second battery 1311 is also called a super battery. If it has high output, Often, a large capacity is not required and the capacity of the second battery 1311 is less than that of the first battery. Smaller than 1301a and 1301b.

[0361] The internal structure of the first battery 1301a is the same as that of the wound battery shown in FIG. 15(A) or FIG. 16(C). It may be a type or a laminated type shown in FIG. 17(A) or FIG. 17(B). The first battery 1301a may be the all-solid-state battery of the fifth embodiment. By using the all-solid-state battery of Embodiment 5 for the battery 1301a, a high capacity can be achieved. , safety is improved and it is possible to make the device smaller and lighter.

[0362] In this embodiment, two first batteries 1301a and 1301b are connected in parallel. Although an example is shown, three or more batteries may be connected in parallel. If sufficient power can be stored, the first battery 1301b may be omitted. By configuring a battery pack with a secondary battery, it is possible to extract a large amount of power. The number of secondary batteries may be connected in parallel, in series, or in parallel. A plurality of secondary batteries may be connected in series after being connected to each other.

[0363] In addition, in the case of secondary batteries for vehicles, tools are used to cut off power from multiple secondary batteries. It has a service plug or circuit breaker that can cut off high voltage without The battery 1301a is provided with the

[0364] The power of the first batteries 1301a and 1301b is mainly used to rotate the motor 1304. It is used to power 42V automotive components (electric power supplies) via the DCDC circuit 1306. 1307, heater 1308, defogger 1309, etc.) to supply power to the rear wheels. Even when the rear motor 1317 is provided, the first battery 1301a is connected to the rear motor 131 Used to rotate the number 7.

[0365] The second battery 1311 also supplies power to 14V-based in-vehicle components ( Powers the audio 1313, power windows 1314, lamps 1315, etc. do.

[0366] The first battery 1301a will be described with reference to FIG. 27(A).

[0367] FIG. 27(A) shows an example in which nine rectangular secondary batteries 1300 are used as one battery pack 1415. Also, nine square secondary batteries 1300 are connected in series, and one electrode is connected to the insulator. The other electrode is fixed by a fixing part 1414 made of an insulating material. In this embodiment, an example in which the battery is fixed by the fixing parts 1413 and 1414 is shown. The vehicle may be configured to be housed in a housing box (also called a housing). Since it is assumed that vibration or shaking is applied from the fixed parts 1413 and 1414 It is preferable to fix multiple secondary batteries in a battery housing box or similar. The other electrode is electrically connected to the control circuit section 1320 by a wiring 1421. The electrodes are electrically connected to the control circuit section 1320 by wiring 1422 .

[0368] The control circuit 1320 uses a memory circuit including a transistor using an oxide semiconductor. A charge control circuit having a memory circuit including a transistor using an oxide semiconductor may be provided. , or the battery control system is called BTOS (Battery operating system) When referred to as "em" or "Battery oxide semiconductor" There is.

[0369] It is preferable to use a metal oxide that functions as an oxide semiconductor. For example, oxide 530 In-M-Zn oxide (where element M is aluminum, gallium, yttrium, copper) , vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium Aluminum, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten It is preferable to use a metal oxide such as one or more selected from the group consisting of titanium dioxide, magnesium, and the like. In particular, the In-M-Zn oxide that can be used as the oxide 530 is CAAC-OS (CA xls Aligned Crystal Oxide Semiconductor) ,CAC-OS(Cloud-Aligned Composite Oxide Se The oxide 530 is preferably In-G In-Zn oxide and In-Zn oxide may also be used. CAAC-OS has multiple crystalline regions. The plurality of crystalline regions are oxide semiconductors whose c-axes are oriented in a particular direction. The specific directions are the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, The crystalline region is a region where the atomic arrangement is periodic. If the atomic arrangement is considered as a lattice arrangement, the crystalline region is a region that has the lattice arrangement Furthermore, the CAAC-OS has multiple crystalline domains in the ab-plane direction. The region may have a region where the regions are connected, and the region may have distortion. In the area where the crystalline regions are connected, there are areas with a uniform lattice arrangement and areas with a different uniform lattice arrangement. This refers to the point where the lattice orientation changes between the c-axis and the The CAC is an oxide semiconductor that is oriented in the ab plane direction and does not have a clear orientation in the ab plane direction. -OS means that, for example, the elements constituting the metal oxide are preferably 0.5 nm or more and 10 nm or less. Or, it is a composition of materials unevenly distributed in sizes of 1 nm to 3 nm or in the vicinity thereof. In the following, it is assumed that one or more metal elements are unevenly distributed in a metal oxide, and the metal elements The region having the element has a size of 0.5 nm or more and 10 nm or less, preferably 1 nm or more and 3 nm or less, Or a state where they are mixed in a size close to that size is also called a mosaic or patch state.

[0370] Furthermore, CAC-OS is a mosaic structure in which the material is separated into a first region and a second region. The first region is in a cloud-like shape, and the first region is distributed throughout the film (hereinafter also referred to as a cloud-like shape). In other words, the CAC-OS is a mixture of the first and second regions. It is a composite metal oxide having the following structure.

[0371] Here, the ratio of In to the metal elements constituting the CAC-OS in the In-Ga-Zn oxide is The atomic ratios of In, Ga, and Zn are expressed as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS of In-Ga-Zn oxide, the first region is In this region, [In] is larger than [In] in the composition of the CAC-OS film. The second region is where [Ga] is larger than [Ga] in the composition of the CAC-OS film. Or, for example, the first region has [In] higher than the [In] in the second region. The first region is larger than the second region, and [Ga] is smaller than [Ga] in the first region. In the second region, [Ga] is larger than [Ga] in the first region, and [In ] is a region smaller than [In] in the first region.

[0372] Specifically, the first region is mainly composed of indium oxide, indium zinc oxide, etc. The second region is a region in which the gallium oxide, gallium zinc oxide, etc. In other words, the first region is called a region where In is the main component. The second region can be rephrased as a region containing Ga as the main component. This can be done.

[0373] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0374] For example, in the case of CAC-OS, an In-Ga-Zn oxide, energy dispersive X-ray spectroscopy (EDX:Energy Dispersive X-ray spectrosco The EDX mapping obtained using the py) identified the region containing In as the main component (first region ) and a region (second region) mainly composed of Ga are unevenly distributed and mixed. It can be confirmed that:

[0375] When CAC-OS is used in a transistor, the conductivity due to the first region and the conductivity due to the second region are The insulating properties caused by the above work complementary to each other, resulting in a switching function (On / Off). In other words, CAC-OS is , a part of the material has a conductive function and a part of the material has an insulating function, and the whole of the material has a The material functions as a semiconductor. By separating the conductive function from the insulating function, Therefore, when using CAC-OS in transistors, This allows for a high on-state current (I on ), high field-effect mobility (μ), and good switching This allows for realizing a locking operation.

[0376] Oxide semiconductors have a variety of structures, each of which has different characteristics. Oxide semiconductors include amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, and CA Two or more of C-OS, nc-OS, and CAAC-OS may be included.

[0377] In addition, since the control circuit section 1320 can be used in a high temperature environment, it is made of a transistor using an oxide semiconductor. It is preferable to use a transistor. In order to simplify the process, the control circuit section 13 The transistor 20 may be formed using a unipolar transistor. The operating ambient temperature range of transistors is wider than that of single-crystal Si, from -40°C to 150°C. Even if the secondary battery is heated, the change in characteristics is smaller than that of a single crystal. The off-state current of the transistor is below the lower limit of measurement regardless of the temperature, even at 150°C. The off-current characteristics of the i-transistor are highly temperature dependent. For example, at 150°C, In Si transistors, the off-state current increases and the current on / off ratio does not become large enough. The circuit section 1320 can improve safety. By combining the active material 100 with a secondary battery that uses the active material 100 in the positive electrode, a synergistic effect on safety is achieved. A secondary battery and a control circuit using the positive electrode active material 100 obtained in the first embodiment as a positive electrode are obtained. The path portion 1320 can greatly contribute to eliminating accidents such as fires caused by secondary batteries.

[0378] The control circuit unit 1320 using a memory circuit including a transistor using an oxide semiconductor is It functions as an automatic control device for secondary batteries to address 10 causes of instability, such as micro-shorts. The functions to eliminate the causes of instability in the 10 items include overcharging prevention. Stop, overcurrent prevention, overheat control during charging, cell balancing in battery packs, over-discharge prevention, remaining capacity meter, Automatic control of charging voltage and current according to temperature, control of charging current according to deterioration, micro These include abnormal short-circuit behavior detection and abnormal prediction of micro-shorts. At least one of the functions is provided in the control circuit section 1320. It can be made smaller.

[0379] Also, a micro-short refers to a minute short circuit inside a secondary battery, The positive and negative electrodes of the battery are not short-circuited to the point that charging and discharging becomes impossible, but rather there is a small short circuit. This refers to the phenomenon where a small amount of short-circuit current flows in a relatively short time and at a small point. Even in the vicinity of the power source, large voltage changes occur, and the abnormal voltage value affects subsequent estimations. There is a risk that this may occur.

[0380] One of the causes of micro-short circuits is the breakdown of the positive electrode active material due to repeated charge and discharge. The uneven distribution causes localized current concentration in parts of the positive electrode and negative electrode, causing the separator Some parts of the material may stop functioning, or side reactions may occur, resulting in microscopic damage. It is said that a short circuit has occurred.

[0381] In addition to detecting a micro-short circuit, the control circuit unit 1320 also detects the terminal voltage of the secondary battery. It can also be said that the system detects the charge and discharge status of the secondary battery and manages the charge and discharge status of the secondary battery. Both the output transistor of the power circuit and the cutoff switch can be turned off almost simultaneously. Cut.

[0382] An example of a block diagram of the battery pack 1415 shown in FIG. 27(A) is shown in FIG. 27(B). .

[0383] The control circuit section 1320 includes at least a switch for preventing overcharging and a switch for preventing overdischarging. a switch unit 1324 including a switch, and a control circuit 1322 for controlling the switch unit 1324; The control circuit 1320 includes a voltage measuring unit for the first battery 1301a. The upper and lower voltage limits of the secondary battery are set, and the upper limit of the external current and the output to the outside are also set. The upper limit of the current is limited. The range between the lower limit voltage and the upper limit voltage of the secondary battery is is within the recommended voltage range, and if it goes outside that range, the switch unit 1324 operates, The control circuit 1320 also controls the switch 1324 to It can also be called a protection circuit because it prevents overcharging and overdischarging. When the control circuit 1322 detects this, the switch of the switch unit 1324 is turned off. Furthermore, a PTC element is installed in the charge / discharge path to cut off the current according to the rise in temperature. The control circuit 1320 may be provided with a function to cut off the external terminal 1325 (+I N) and an external terminal 1326 (-IN).

[0384] The switch section 1324 is a combination of n-channel transistors and p-channel transistors. The switch section 1324 is made of Si, which uses single crystal silicon. The switch is not limited to a transistor, but may be made of, for example, Ge (germanium), SiGe (Silicon Germanium), GaAs (Gallium Arsenide), GaAlAs (Gallium Aluminum arsenide), InP (indium phosphide), SiC (silicon carbide), ZnSe (zinc selenide), GaN (gallium nitride), GaOx (gallium oxide; x is greater than 0) The switch section 1324 may be formed by a power transistor having a low real number. A memory element using an OS transistor is stacked on a circuit using a Si transistor. This allows for free placement, making integration easy. Since silicon transistors can be manufactured using the same manufacturing equipment as silicon transistors, That is, the control circuit using an OS transistor on the switch section 1324 can be manufactured at low cost. The control circuit section 1320 can be stacked and integrated into a single chip. The volume occupied by 1320 can be reduced, making it possible to make it smaller.

[0385] The first batteries 1301a and 1301b mainly supply power to 42V (high voltage) in-vehicle devices. The second battery 1311 supplies power to the 14V system (low voltage system) in-vehicle equipment. The second battery 1311 is often a lead-acid battery because of its cost advantage. Compared to lithium-ion secondary batteries, the battery has a higher self-discharge rate, which is called sulfation. The second battery 1311 is a lithium ion secondary battery. This has the advantage of being maintenance-free, but for long-term use, for example, for more than 3 years, If the temperature rises above this level, there is a risk of abnormalities occurring that cannot be detected during manufacturing. If the second battery 1311 becomes inoperable, the first battery 1301a, 1301b, To prevent the motor from being unable to start even if there is remaining capacity in 1b, If the battery 1311 is a lead-acid battery, power is supplied from the first battery to the second battery. The battery is charged to keep it fully charged at all times.

[0386] In this embodiment, both the first battery 1301a and the second battery 1311 are lithium. The second battery 1311 is a lead-acid battery or an all-solid-state battery. For example, the all-solid-state battery of the fifth embodiment may be used. By using the all-solid-state battery according to the fifth embodiment as the second battery 1311, a high capacity can be achieved. This allows for a reduction in size and weight.

[0387] The regenerative energy generated by the rotation of the tire 1316 is transmitted to the motor 13 via the gear 1305. 04 and controlled by the motor controller 1303 and battery controller 1302. The second battery 1311 is charged via the circuit unit 1321. The first battery 1301a is charged by the roller 1302 via the control circuit unit 1320. Alternatively, the first battery is supplied from the battery controller 1302 via the control circuit unit 1320. In order to efficiently charge the regenerative energy, the first battery It is desirable that the batteries 1301a and 1301b are capable of rapid charging.

[0388] The battery controller 1302 controls the charging voltage and The battery controller 1302 can set the battery voltage, charging current, etc. Charging conditions can be set according to the charging characteristics of the battery, allowing for rapid charging.

[0389] Although not shown, when connecting to an external charger, the charger's outlet or charging The electrical connection cable is electrically connected to the battery controller 1302. The power supplied from the charger is supplied to the first battery 1 via the battery controller 1302. 301a, 1301b. In addition, some chargers are equipped with a control circuit. In some cases, the function of the battery controller 1302 is not used, but it is restricted to prevent overcharging. It is preferable to charge the first batteries 1301a and 1301b via the control circuit unit 1320. In addition, the connection cable or charger connection cable may have a control circuit. The control circuit section 1320 is an ECU (Electronic Control Unit The ECU is also called a CAN (Controller CAN is used as an in-vehicle LAN. It is one of the serial communication standards. The ECU includes a microcomputer. The ECU uses a CPU and GPU.

[0390] External chargers installed at charging stations, etc., are powered by 100V or 200V outlets. There are also other types, such as a 3-phase 200V and 50kW outlet. It can also be charged by receiving power from charging equipment.

[0391] When performing rapid charging, a secondary battery that can withstand high voltage charging is required in order to charge in a short time. A pond is desired.

[0392] The secondary battery of the present embodiment described above is also made by using the positive electrode active material 100 obtained in the first embodiment. Furthermore, graphene is used as a conductive additive, and the positive electrode has a high density. Even if the electrode layer is made thicker and the amount of support is increased, the capacity decrease is suppressed and high capacity is maintained, which is a synergistic effect. This makes it possible to realize a secondary battery with significantly improved electrical characteristics. This is particularly useful for secondary batteries used in vehicles. It is efficient and the driving range can be increased without increasing the weight ratio of the secondary battery to the total vehicle weight. It is possible to provide vehicles with a long range, specifically a range of over 500 km on a single charge.

[0393] In particular, the secondary battery of this embodiment uses the positive electrode active material 100 described in the first embodiment. This allows the operating voltage of the secondary battery to be increased, and as the charging voltage increases, the battery becomes unusable. In addition, the positive electrode active material 100 described in the first embodiment can be used to increase the capacity. By using the electrode, a secondary battery for vehicles having excellent cycle characteristics can be provided.

[0394] Next, an example in which a secondary battery according to one embodiment of the present invention is mounted on a vehicle, typically a transportation vehicle, will be described. I will explain.

[0395] In addition, the secondary battery shown in any one of FIG. 14(D), FIG. 16(C), and FIG. 27(A) may be installed in a vehicle. When installed in a hybrid vehicle (HV), electric vehicle (EV), or plug-in hybrid vehicle (PHY), This will enable the realization of next-generation clean energy vehicles such as plug-in hybrid vehicles (PHVs). Motorized bicycles including electrically assisted bicycles, motorcycles, electric wheelchairs, electric carts, small vehicles Or large ships, submarines, fixed-wing aircraft, rotary-wing aircraft, rockets, satellites, space exploration The secondary battery can also be mounted on transportation vehicles such as aircraft, planetary probes, and spacecraft. The secondary battery of one embodiment can be a high-capacity secondary battery. The secondary battery is suitable for miniaturization and light weight, and can be suitably used in transportation vehicles.

[0396] 28(A) to 28(D) show examples of transportation vehicles using one embodiment of the present invention. The automobile 2001 shown in FIG. 8(A) is an electric automobile that uses an electric motor as a power source for running. Alternatively, an electric motor and an engine can be selected as the power source for running. When a secondary battery is installed in a vehicle, the implementation An example of the secondary battery shown in Mode 4 is installed at one or more locations. The vehicle 2001 has a battery pack 2200, which is a battery pack having a plurality of secondary batteries connected thereto. The secondary battery module further includes a charging control It is preferable to have a device.

[0397] In addition, the car 2001 is equipped with a plug-in type or a contactless charging system for the secondary battery that the car 2001 has. The vehicle can be charged by receiving power from an external charging facility using a charging method, etc. The charging method and connector specifications are specified by CHAdeMO (registered trademark) and Combo. The secondary battery may be a charging station installed in a commercial facility, It can also be a household power source. For example, plug-in technology allows for external power supply. The power storage device mounted on the automobile 2001 can be charged by the AC / DC converter. This can be achieved by converting AC power into DC power via a conversion device such as a converter.

[0398] 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 two vehicles. A solar cell may be provided in the storage unit to charge the secondary battery when the vehicle is stopped or running. The supply of power through contact can be achieved by electromagnetic induction or magnetic resonance.

[0399] FIG. 28(B) shows a large transport vehicle having an electrically controlled motor as an example of a transport vehicle. The figure shows a vehicle 2002. The secondary battery module of the transportation vehicle 2002 has a nominal voltage of, for example, 3. A 48-cell unit consisting of 4 secondary batteries with a voltage between 0V and 5.0V is connected in series. The maximum voltage is 70 V. The secondary battery that constitutes the secondary battery module of the battery pack 2201 Other than the difference in the number of items, the functions are the same as those in FIG. 28(A), so the explanation will be omitted.

[0400] FIG. 28(C) shows an example of a large transport vehicle 2003 having an electrically controlled motor. The secondary battery module of the transport vehicle 2003 has a nominal voltage of, for example, 3.0 V or more. The maximum voltage is 600V when more than 100 secondary batteries of 5.0V or less are connected in series. A secondary battery with small variations in characteristics is desired. By using a secondary battery that uses the positive electrode, a secondary battery with stable battery characteristics is manufactured. This allows for mass production at low cost in terms of yield. The number of secondary batteries constituting the secondary battery module 202 is different from that of FIG. 28(A). Since they have similar functions, their explanations will be omitted.

[0401] FIG. 28(D) shows an aircraft 2004 having a fuel-burning engine as an example. The aircraft 2004 shown in FIG. 28(D) has wheels for takeoff and landing, so it is not a transport vehicle. It can be said that this is a part of the secondary battery module, and multiple secondary batteries are connected to form a secondary battery module. The battery pack 2203 includes a module and a charge controller.

[0402] The secondary battery module of the 2004 aircraft is, for example, a 3V battery consisting of eight 4V secondary batteries connected in series. The maximum voltage of the secondary battery that constitutes the secondary battery module of the battery pack 2203 is 2V. Other than the difference in number, etc., it has the same functions as FIG. 28(A), so the explanation will be omitted.

[0403] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0404] (Embodiment 7) In this embodiment, an example in which a secondary battery according to one embodiment of the present invention is mounted in a building is described with reference to FIG. This will be explained using Figure 29(A) and Figure 29(B).

[0405] The house in FIG. 29A includes a power storage device 2612 including a secondary battery of one embodiment of the present invention. The solar panel 2610 is connected to the power storage device 2612. The power storage device 2612 and the ground-mounted charging device 2613 are electrically connected via a wire 2611. The power generated by the solar panel 2610 can be The power stored in the power storage device 2612 can be The secondary battery of the vehicle 2603 can be charged via the charging device 2604. The electrical device 2612 is preferably installed in the underfloor space. This allows for effective use of the space above the floor. It may be placed on top.

[0406] The power stored in the power storage device 2612 can also be used to power other electronic devices in the home. Therefore, even when power cannot be supplied from the commercial power source due to a power outage or the like, the present invention The power storage device 2612 of one embodiment can be used as an uninterruptible power supply, thereby enabling the use of electronic devices. It becomes Noh.

[0407] FIG. 29B illustrates an example of a power storage device 700 according to one embodiment of the present invention. As shown in the figure, a power storage device 791 according to one embodiment of the present invention is installed in an underfloor space 796 of a building 799. The power storage device 791 may be provided with the control circuit described in Embodiment 6. In addition, a secondary battery using the positive electrode active material 100 obtained in the first embodiment as a positive electrode is used as the power storage device 791. By using the control circuit described in the sixth embodiment, a synergistic effect on safety can be obtained. The secondary battery using the positive electrode active material 100 described in the first embodiment as a positive electrode has a secondary battery. This can greatly contribute to the elimination of accidents such as fires caused by the power storage device 791.

[0408] The storage device 791 is provided with a control device 790, which is connected to the A distribution board 703, a power storage controller 705 (also called a control device), and a display 706 , and the router 709 are electrically connected to.

[0409] Electric power is sent from a commercial power source 701 to a distribution board 703 via a drop line attachment portion 710 . In addition, power is sent to the distribution board 703 from the power storage device 791 and the commercial power source 701, The distribution board 703 distributes the received power to the general loads 707 and and supplies it to the storage load 708.

[0410] The general load 707 is, for example, an electrical appliance such as a television or a personal computer. The electrical load 708 is, for example, an electrical appliance such as a microwave oven, a refrigerator, or an air conditioner.

[0411] The power storage controller 705 includes a measurement unit 711, a prediction unit 712, and a planning unit 713. The measurement unit 711 measures the general load 707, the power storage system 708, and the power consumption of the power storage system 709 during a day (for example, from 0:00 to 24:00). The measuring unit 711 has a function of measuring the amount of power consumed by the load 708. The power consumption of the device 791 and the power consumption supplied from the commercial power source 701 are measured. The prediction unit 712 may also predict the general load 707 and the power storage load 708 during a day. Based on the amount of power consumed by the general load 707 and the storage load 708 during the next day, The planning unit 713 has a function of predicting the amount of power demand to be consumed. The power storage device 791 has a function of making a plan for charging and discharging the power storage device 791 based on the predicted amount of power demand.

[0412] The power consumed by the general load 707 and the power storage load 708 measured by the measurement unit 711 The amount can be confirmed on the display 706. Also, the amount can be confirmed on the television via the router 709. It can also be checked in electrical equipment such as TVs and personal computers. It can also be checked by a mobile electronic device such as a smartphone or tablet via the router 709. In addition, the display 706, the electric device, and the portable electronic terminal can predict the time. 2. You can also check the predicted power demand for each time period (or hourly). .

[0413] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0414] (Embodiment 8) In this embodiment, an example in which a power storage device according to one embodiment of the present invention is mounted on a motorcycle or a bicycle will be described. .

[0415] FIG. 30A illustrates an example of an electric bicycle using the power storage device of one embodiment of the present invention. The power storage device of one embodiment of the present invention can be applied to an electric bicycle 8700 illustrated in FIG. A power storage device of one embodiment of the present invention includes, for example, a plurality of storage batteries and a protection circuit.

[0416] The electric bicycle 8700 includes a power storage device 8702. The power storage device 8702 serves as an assistant for the rider. The power storage device 8702 can supply electricity to a motor that runs on the power FIG. 30(B) shows the state where the power storage device 8702 is removed from the bicycle. The power storage device of one embodiment of the present invention includes a plurality of built-in storage batteries 8701. The remaining battery charge and the like can be displayed on the display unit 8703. The control circuit 870 capable of controlling charging or detecting abnormality of the secondary battery, an example of which is shown in the sixth embodiment, The control circuit 8704 is electrically connected to the positive and negative electrodes of the storage battery 8701. In addition, the control circuit 8704 is provided with a small solid-state secondary A battery may be provided. The small solid secondary battery shown in FIG. 26(A) and FIG. 26(B) may be controlled. By providing it in the circuit 8704, data in the memory circuit of the control circuit 8704 can be held for a long time. In addition, the positive electrode active material 10 obtained in the first embodiment can be supplied with electric power. Combining it with a secondary battery that uses 0 as the positive electrode will provide a synergistic effect in terms of safety. A secondary battery using the positive electrode active material 100 obtained in embodiment 1 as a positive electrode and a control circuit 8704 This can make a significant contribution to eliminating accidents such as fires caused by secondary batteries.

[0417] FIG. 30C illustrates an example of a two-wheeled vehicle including a power storage device of one embodiment of the present invention. The scooter 8600 shown in (C) has a power storage device 8602, side mirrors 8601, and a turn signal. The power storage device 8602 can supply electricity to the direction indicator light 8603. In addition, a plurality of secondary batteries using the positive electrode active material 100 obtained in the first embodiment as a positive electrode can be produced. The stored power storage device 8602 can have a high capacity, which can contribute to miniaturization. .

[0418] In addition, the scooter 8600 shown in FIG. 30(C) has a storage unit 8604 under the seat. The power storage device 8602 can be stored in the under-seat storage 8604 even if it is small. , and can be stored in the under-seat storage compartment 8604.

[0419] (Embodiment 9) 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. As an electronic device that incorporates a secondary battery, for example, a television device (television or television) (also called revision receivers), monitors for computers, digital cameras, digital Video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices) ), portable game machines, personal digital assistants, audio playback devices, large game machines such as pachinko machines, etc. Examples of portable information terminals include notebook personal computers and tablet terminals. These include e-book readers and mobile phones.

[0420] 31A shows an example of a mobile phone. The mobile phone 2100 has a housing 2101. In addition to the display unit 2102 incorporated in the The mobile phone 2100 is equipped with a speaker 2105, a microphone 2106, etc. The battery 2107 includes the positive electrode active material 100 described in the first embodiment. By providing a secondary battery 2107, high capacity can be achieved, and space can be saved by making the housing smaller. It is possible to realize a configuration that can respond to changes.

[0421] The mobile phone 2100 is a device that can be used for mobile phone calls, e-mails, viewing and creating documents, playing music, and internet. It can run various applications such as internet communication and computer games. .

[0422] The operation button 2103 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, the operating system installed in the mobile phone 2100 can The system also allows the functions of the operation buttons 2103 to be freely set.

[0423] The mobile phone 2100 is also capable of performing standardized short-range wireless communication. For example, by communicating with a wireless headset, hands-free communication is possible. You can also talk.

[0424] The mobile phone 2100 also has an external connection port 2104, allowing it to be connected to other information terminals via a connector. Data can be exchanged directly via the external connection port 2104. Charging can also be performed. Note that charging is performed by wireless power supply without going through the external connection port 2104. It may also be carried out by

[0425] The mobile phone 2100 preferably has a sensor, such as a fingerprint sensor. , pulse sensors, body temperature sensors, and other human body sensors, as well as touch sensors, pressure sensors, and acceleration sensors , etc. are preferably installed.

[0426] Figure 31(B) shows an unmanned aerial vehicle 2300 having multiple rotors 2302. The unmanned aerial vehicle 2300 is sometimes referred to as a drone. The unmanned aerial vehicle 2300 is an embodiment of the present invention. The unmanned aerial vehicle includes a secondary battery 2301, a camera 2303, and an antenna (not shown). The device 2300 can be remotely controlled via an antenna. A secondary battery using the active material 100 in the positive electrode has a high energy density and is highly safe, and therefore can be used for a long time. It can be used safely for a long period of time and is used as a secondary battery for the unmanned aerial vehicle 2300. It is suitable.

[0427] Figure 31(C) shows an example of a robot. The robot 6400 shown in Figure 31(C) is , secondary battery 6409, illuminance sensor 6401, microphone 6402, upper camera 640 3, a speaker 6404, a display unit 6405, a lower camera 6406, and an obstacle sensor 640 7, equipped with a moving mechanism 6408, a computing device, etc.

[0428] The microphone 6402 has a function of detecting the user's voice and environmental sounds. The speaker 6404 has a function of emitting sound. The device can communicate with the user using the microphone 6402 and the speaker 6404. It is possible.

[0429] The display unit 6405 has a function of displaying various information. The display unit 6405 can display desired information. The display unit 6405 may be a detachable information terminal. By placing it in a fixed position on the Robot 6400, charging and data transfer can be performed. It is possible.

[0430] The upper camera 6403 and the lower camera 6406 are used to capture images of the surroundings of the robot 6400. The obstacle sensor 6407 also detects the obstacles in the robot 640 by using the movement mechanism 6408. Robot 64 can sense whether there are any obstacles in its path as it moves forward. 00 uses an upper camera 6403, a lower camera 6406, and an obstacle sensor 6407 It is possible to recognize the surrounding environment and move safely.

[0431] The robot 6400 has a secondary battery 6409 according to one embodiment of the present invention and a semiconductor The positive electrode active material 100 obtained in the first embodiment is used for the positive electrode. Secondary batteries have a high energy density and are highly safe, so they can be safely used for a long period of time. It can be used as a secondary battery 6409 to be mounted on the robot 6400.

[0432] FIG. 31(D) shows an example of a cleaning robot. The cleaning robot 6300 is a housing 63 01 A display unit 6302 arranged on the top surface, multiple cameras 6303 arranged on the side, and a brush 6304, operation buttons 6305, a secondary battery 6306, various sensors, etc. Although not shown, the cleaning robot 6300 is equipped with tires, a suction nozzle, etc. The robot 6300 moves by itself, detects the debris 6310, and ejects it from the suction port on the bottom. It can suck mi.

[0433] For example, the cleaning robot 6300 analyzes the image captured by the camera 6303 and detects the walls, furniture, etc. It can also determine whether there are obstacles such as steps or wiring by image analysis. If an object that may become entangled in the brush 6304 is detected, the rotation of the brush 6304 is stopped. The cleaning robot 6300 has a secondary battery 6 according to one aspect of the present invention in its internal area. 306, and a semiconductor device or electronic component. Secondary batteries using 0 as the positive electrode have a high energy density and are highly safe, so they can be used for a long period of time. It can be used safely for a long time and is used as a secondary battery 6306 mounted on the cleaning robot 6300. It is suitable.

[0434] FIG. 32(A) shows an example of a wearable device. It uses a secondary battery as a power source. In addition, the user must ensure that the device is water-resistant for daily use or outdoor use. To improve water resistance, not only wired charging with exposed connectors is also supported. There is a demand for wearable devices that can also be charged wirelessly.

[0435] For example, a secondary lens according to one aspect of the present invention may be applied to a glasses-type device 4000 as shown in FIG. 32(A). The eyeglass-type device 4000 includes a frame 4000a and a display. The secondary battery is mounted on the temple of the curved frame 4000a. This allows for a lightweight, well-balanced eyeglass-type device that can be used continuously for a long time. 4000. When the positive electrode active material 100 obtained in the first embodiment is used for the positive electrode, The secondary battery has a high energy density and is designed to accommodate space-saving requirements associated with smaller housings. This can be achieved.

[0436] In addition, the headset device 4001 may be equipped with a secondary battery according to one embodiment of the present invention. The headset type device 4001 includes at least a microphone unit 4001a and a frame. The flexible pipe 4001b and the earphone part 4001c are included. A secondary battery can be provided in the earphone unit 4001b or the earphone unit 4001c. The secondary battery using the positive electrode active material 100 obtained in the above as the positive electrode has a high energy density and It is possible to realize a configuration that can accommodate space saving associated with miniaturization.

[0437] In addition, a device 4002 that can be directly attached to the body is equipped with a secondary battery according to one embodiment of the present invention. The device 4002 can be mounted with a secondary battery 400 in a thin housing 4002a. The positive electrode active material 100 obtained in the first embodiment can be used for the positive electrode. The secondary battery has a high energy density and is designed to be space-saving due to the miniaturization of the housing. It can be realized.

[0438] In addition, a device 4003 that can be attached to clothing is equipped with a secondary battery according to one embodiment of the present invention. The device 4003 has a thin housing 4003a and a secondary battery 4003b. A secondary battery using the positive electrode active material 100 obtained in the first embodiment as a positive electrode can be provided. The battery has a high energy density, and the structure allows for space saving due to the miniaturization of the housing. It is possible.

[0439] In addition, the belt-type device 4006 can be equipped with a secondary battery according to one embodiment of the present invention. The belt-type device 4006 includes a belt part 4006a and a wireless power receiving part 4006b. 4006b, and a secondary battery can be mounted in the internal area of ​​the belt portion 4006a. A secondary battery using the positive electrode active material 100 obtained in the first embodiment as a positive electrode has a high energy density. This makes it possible to realize a configuration that can accommodate space-saving measures that accompany the miniaturization of the housing.

[0440] In addition, the secondary battery of one embodiment of the present invention can be mounted on the wristwatch device 4005. The wristwatch type device 4005 has a display part 4005a and a belt part 4005b. A secondary battery can be provided in the display unit 4005a or the belt unit 4005b. The secondary battery using the positive electrode active material 100 obtained in Embodiment 1 as the positive electrode has a high energy density and can be easily stored in a case. It is possible to realize a configuration that can accommodate space saving that accompanies the miniaturization of the body.

[0441] The display unit 4005a displays not only the time but also various information such as incoming emails and phone calls. It is possible.

[0442] The wristwatch type device 4005 is a wearable device that can be worn directly on the wrist. Therefore, sensors for measuring the user's pulse, blood pressure, etc. may be installed. It is also possible to accumulate health-related data and manage health.

[0443] FIG. 32(B) shows a perspective view of the wristwatch type device 4005 removed from the wrist.

[0444] 32(C) shows a side view. In FIG. 32(C), a secondary battery 913 is installed in the internal area. The secondary battery 913 is the secondary battery shown in the fourth embodiment. The secondary battery 913 is provided at a position overlapping the display unit 4005a, and has high density and large capacity. It can be small, compact and lightweight.

[0445] The wristwatch type device 4005 is required to be small and lightweight. By using the positive electrode active material 100 obtained in the first embodiment for the positive electrode of the secondary battery 913, high energy The secondary battery 913 can be made small and have high energy density.

[0446] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Example]

[0447] In this example, the results of electron microscope observation of a positive electrode of one embodiment of the present invention are shown.

[0448] First, a positive electrode active material according to one embodiment of the present invention was produced by the production method shown in FIG.

[0449] <Preparation of positive electrode active material> Pre-synthesized composite oxides containing lithium, transition metal M, and oxygen are available in Japan. Lithium cobalt oxide particles (product name: Cellseed C-10N) manufactured by Chemical Industry Co., Ltd. were prepared. (Step S14).

[0450] Next, lithium fluoride was used as the fluorine source, magnesium fluoride was used as the magnesium source, The molecular weight ratio of lithium fluoride to magnesium fluoride was 1:3 (step The mixture was crushed and mixed (step S21), and a mixture 902 was obtained (step S twenty three).

[0451] Next, the lithium cobalt oxide and the mixture 902 were mixed to remove the cobalt contained in the lithium cobalt oxide. When the number of atoms of fluoride is 100, the number of molecules of magnesium fluoride contained in mixture 902 is 1 were prepared and mixed (step S41), and a mixture 903 was obtained (step S4 2).

[0452] Next, the mixture 903 was placed in an alumina container, which was then covered with a lid and placed in a muffle furnace. The mixture 903 was heated (step S43). The heating conditions were 900° C., 20 hours, and an oxygen atmosphere. I felt that way.

[0453] Next, the heated second mixture, nickel hydroxide, and aluminum hydroxide are mixed with cobalt hydroxide. When the number of cobalt atoms in lithium hydroxide is 100, the number of nickel hydroxide molecules is The molecular weight of aluminum hydroxide was 0.5 (step P S31). Next, the nickel hydroxide and aluminum hydroxide prepared in step S31 are mixed with the heated mixture. The mixture 903 was mixed (step S61) to obtain a mixture 904 (step S62).

[0454] Next, the mixture 904 was placed in an alumina container, which was then covered with a lid and placed in a muffle furnace. The mixture 904 was heated (Step S63) to prepare a positive electrode active material of one embodiment of the present invention. Here, the heat treatment is not performed in two separate heating steps, step S63 and step S67. The heating conditions were 850°C, 10 hours, and an oxygen atmosphere. Ta.

[0455] <Preparation of positive electrode> Next, a positive electrode was fabricated using the prepared positive electrode active material. The positive electrode active material, AB, and PVDF were mixed in a ratio of 95:3:2 (weight ratio) to prepare a slurry. The slurry was applied to an aluminum current collector having a thickness of 20 μm. MP was used.

[0456] After the slurry was applied to the current collector, the solvent was evaporated and then a pressure of 210 kN / m was applied. After that, a pressure of 1467 kN / m was applied. Through the above steps, a positive electrode was obtained. The amount of the positive electrode supported was approximately 6 mg / cm 2 The density of the positive electrode active material layer was approximately 3 It was .9g / cc.

[0457] <Preparation of secondary battery> Next, using the prepared positive electrode, a CR2032 type (diameter 20 mm, height 3.2 mm) A battery cell was fabricated.

[0458] Lithium metal was used as the counter electrode.

[0459] 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), and vinylene carbonate (VC) was added to the mixture. The material containing 100% by weight of Zn was used.

[0460] The separator was made of polypropylene with a thickness of 25 μm.

[0461] The positive electrode can and the negative electrode can were made of stainless steel (SUS).

[0462] <Cycle characteristics> Next, the cycle characteristics of the secondary battery were evaluated. Charging was performed at a 0.5C rate with a maximum of 4. After constant current charging up to 7V, constant voltage charging was performed at 4.7V up to a rate of 0.05C. Discharge was performed at a constant current of 200mA / g at a rate of 0.5C down to a lower limit of 2.5V. The measurement was carried out at 45°C.

[0463] The cycle characteristics are shown in Figure 33. The horizontal axis shows the number of cycles, and the vertical axis shows the discharge capacity. After the cycle, the discharge capacity decreased to less than 40% of that of the first cycle.

[0464] <Battery Disassembly> The secondary battery was disassembled after 50 charge / discharge cycles, and the positive electrode was removed. Disassembly was carried out under an argon atmosphere. After disassembly, the specimen was washed with DMC, and the solvent was evaporated. In addition, observations were also made at the stage after the positive electrode was fabricated, before it was incorporated into a secondary battery.

[0465] <SEM Observation> Next, regarding the positive electrode taken out by disassembling the secondary battery, it was observed with a scanning electron microscope (SEM). Fig. 34(A) shows the SEM image of the positive electrode of the secondary battery after 50 cycles. Fig. 34 (B) shows the SEM image of the positive electrode before being incorporated into the secondary battery. For the SEM observation, a scanning electron microscope device SU8030 manufactured by Hitachi High-Tech Corporation was used for the observation. was observed using the scanning electron microscope device SU8030 manufactured by Hitachi High-Tech Corporation.

[0466] Next, the positive electrode was cross-sectioned with FIB (Focused Ion Beam), and the cross-section of the positive electrode was observed with SEM. By repeating the cross-sectioning with FIB and the SEM observation, three-dimensional information on the structure can be obtained. For the FIB processing and SEM observation, XVision2 10B manufactured by Hitachi High-Tech was used.

[0467] Fig. 35(A) shows the SEM image of the upper surface of the positive electrode of the secondary battery after 50 cycles. Fig. 35(B) is the cross-sectional view of the dashed line part in Fig. 35(A). Also, Fig. 3( C) is an enlarged view of the part surrounded by the square frame in Fig. 35(B). In Fig. 35(C), pits 90a, 90b, 90 c are shown. are shown.

[0468] Fig. 36(A) is the same SEM image as Fig. 35(A), but the dashed line part is different. Fig. 36(B) is the cross-sectional view of the dashed line part in Fig. 36(A). That is, Fig, 36(B) is an image with the cross-sectional position shifted from Fig. 35 (B). Also, Fig. 36(C) is an enlarged view of the part surrounded by the square frame in Fig. 36(B). In Fig. 36(C), pits 90d, 90e, and crack 91[[ID=:38]] a are shown. are shown.

[0469] Fig. 37(A) is the same SEM image as Fig. 35(A) and Fig. 36(A), but the dashed line part is different This is the case. Figure 37(B) is a cross-sectional view of the dashed-line portion in Figure 37(A). That is, Figure 37 (B) is an image with the cross-sectional position shifted from Figures 35(B) and 36(B). Also, Figure 3 7(C) is an enlarged view of the portion surrounded by the square frame in Figure 37(B). Figure 37(C) shows pins 90f, 90g, and cavity 92a.

[0470] Figure 38(A) shows a SEM image of the upper surface of the positive electrode before being incorporated into the secondary battery. Figure 38(B) is a cross-sectional view of the dashed-line portion in Figure 38(A). Also, Figures 38(C) and (D) are enlarged views of two portions each surrounded by the square frame in Figure 38(B). Figure 38(D) shows crack 91b.

[0471] As described above, when the positive electrode after 50 cycles was observed, pits, cracks, and voids were observed.

[0472] <STEM Observation> Next, the cross-section of the positive electrode of the secondary battery after 50 cycles was observed using a scanning transmission electron microscope (STEM). We performed sample processing for cross-section observation using FIB. Figure 39(A ) shows a transmission electron image (TE image), and Figure 39(B) shows a secondary battery image (SE image) of the same location respectively. Figure 39(C) is an enlarged view of the portion surrounded by the square frame in Figure 39(B). For STEM observation, a scanning transmission electron microscope HD-2700 manufactured by Hitachi High-Tech Corporation was used.

[0473] At the location indicated by the arrow in Figure 39(C), the width of the pit was observed. The results are shown in Table 1 .

[0474]

Table 1

[0475] The width of the pits was in the range of approximately 10 nm to 25 nm.

[0476] <EDX analysis> Next, for the positive electrode of the secondary battery after 50 cycles, energy dispersive X-ray spectroscopy (EDX :Energy Dispersive X-ray spectroscopy) was used for evaluation.

[0477] Fig. 40(A) shows the cross-sectional STEM image of the positive electrode shown in Fig. 39(B). Fig. 40(B) is an enlarged view of the portion surrounded by the square frame in Fig. 40(A).

[0478] The EDX mapping in the region shown in Fig. 40(B) is shown in Figs. 41(A) to (C). Fig. 41(A) shows the EDX mapping of magnesium, Fig. 41(B) shows that of aluminum, and Fig. 41(C) shows that of cobalt . HD-2700 manufactured by Hitachi High-Tech was used for the EDX analysis . The acceleration voltage was 200 kV. The EDX mapping suggested that magnesium and aluminum were present in at least a part of the surface layer of the positive electrode active material particles .

Explanation of symbols

[0479] 100 Positive electrode active material 300 Secondary battery 301 Positive electrode can 302 Negative electrode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode [[ID=,57]]308 Negative electrode current collector 309 Negative electrode active material layer 310 Separator 312 Washer 313 Ring-shaped insulator 322 Spacer 400 Secondary battery 410 Positive electrode 411 Cathode active material 413 Positive electrode current collector 414 Cathode active material layer 420 Solid electrolyte layer 421 Solid electrolyte 430 negative electrode 431 Negative electrode active material 433 Negative electrode current collector 434 Negative electrode active material layer 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 509a Exterior body 509b exterior body 510 Positive lead electrode 511 Negative lead electrode 513 Secondary battery 514 terminals 515 Seal 516 Stickers 517 Antenna 519 layers 529 Label 530 Oxides 531 Secondary battery pack 540 Circuit Board 550 current collector 551 On the other hand 552 On the other hand 553 Acetylene Black 554 Graphene 555 Carbon nanotubes 561 Active material 562 Active material 590 Control Circuit 590a Circuit System 590b Circuit System 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 613 Safety valve mechanism 614 Conductive Plate 615 Energy Storage System 616 Secondary battery 620 Control Circuit 621 Wiring 622 Wiring 623 Wiring 624 Conductors 625 Insulator 626 Wiring 627 Wiring 628 Conductive Plate 700 Electricity storage device 701 Commercial power supply 703 Distribution board 705 Energy Storage Controller 706 Display 707 General load 708 Storage Load 709 Router 710 Drop line attachment part 711 Measurement Department 712 Prediction Department 713 Planning Department 750a positive electrode 750b solid electrolyte layer 750c negative pole 751 Electrode Plate 752 Insulating tube 753 Electrode Plate 761 Lower member 762 Upper member 764 Wing Nut 765 O-ring 766 Insulator 770a Packaging material 770b Packaging material 770c packaging material 771 External electrode 772 External electrode 773a Electrode layer 773b Electrode layer 790 Control Device 791 Power storage device 796 Underfloor space 799 Building 902 mixture 903 mixture 904 Mixture 911a terminal 911b terminal 913 Secondary battery 930 chassis 930a housing 930b housing 931 negative electrode 931a Negative electrode active material layer 932 Positive electrode 932a Cathode active material layer 933 Separator 950 Wound body 950a Wound body 951 terminal 952 terminals 1300 Prismatic secondary battery 1301a battery 1301b battery 1302 Battery Controller 1303 Motor Controller 1304 Motor 1305 Gear 1306 DC / DC circuit 1307 Electric power steering 1308 Heater 1309 Defogger 1310 DC / DC circuit 1311 Battery 1312 inverter 1313 Audio 1314 Power window 1315 Lamps 1316 Tires 1317 Rear motor 1320 Control circuit section 1321 Control circuit section 1322 control circuit 1324 Switch section 1325 External terminal 1326 External terminal 1413 Fixed part 1414 Fixed part 1415 Battery Pack 1421 Wiring 1422 Wiring 2001 Automobile 2002 Transport Vehicle 2003 Transport Vehicle 2004 aircraft 2100 mobile phone 2101 Housing 2102 Display section 2103 Operation button 2104 External connection port 2105 Speaker 2106 Mike 2107 Secondary battery 2200 battery pack 2201 Battery pack 2202 Battery Pack 2203 Battery Pack 2300 Unmanned Aircraft 2301 Secondary battery 2302 rotor 2303 Camera 2603 vehicles 2604 Charging device 2610 solar panel 2611 Wiring 2612 Energy storage device 4000 Eyeglasses-type Device 4000a frame 4000b Display section 4001 Headset type device 4001a microphone section 4001b Flexible Pipe 4001c Earphones 4002 devices 4002a housing 4002b secondary battery 4003 Devices 4003a housing 4003b secondary battery 4005 Wristwatch-type device 4005a Display section 4005b Belt section 4006 Belt-type device 4006a Belt section 4006b Wireless power receiving unit 6300 Cleaning Robot 6301 Housing 6302 Display section 6303 Camera 6304 Brush 6305 Operation button 6306 Secondary battery 6310 Garbage 6400 Robot 6401 Illuminance Sensor 6402 Microphone 6403 Upper Camera 6404 Speaker 6405 Display section 6406 Lower Camera 6407 Obstacle Sensor 6408 Moving mechanism 6409 Secondary battery 8600 Scooter 8601 Side mirror 8602 Energy storage devices 8603 Turn signal light 8604 Under-seat storage 8700 Electric Bicycle 8701 Storage battery 8702 Energy storage devices 8703 Display section 8704 Control circuit

Claims

[Claim 1] a first step of mixing lithium fluoride, a second material having magnesium, and a third material being a metal oxide having lithium and cobalt to form a first mixture; a second step of putting the first mixture into a first container, placing a lid on the first container, and performing first heating in a temperature range of 742°C to 950°C for 1 hour to 100 hours to prepare a second mixture; a third step of mixing the second mixture with a fourth material containing nickel, and then further mixing a fifth material containing aluminum and a sixth material containing zirconium to prepare a third mixture; a fourth step of subjecting the third mixture to a second heating at a temperature of 350° C. or higher and lower than 600° C. for a time period of 1 hour or higher and 100 hours or lower to prepare a fourth mixture; a fifth step of putting the fourth mixture into a second container, placing a lid on the second container, and performing third heating in a temperature range of 830°C to 1130°C for 1 hour to 100 hours to prepare a fifth mixture; in the third step, aluminum alkoxide is used as the fifth material containing aluminum, and zirconium alkoxide is used as the sixth material containing zirconium; In the second step, the fourth step, and the fifth step, the first to third heating steps are each performed in an atmosphere containing oxygen.

Images