Method for preparing positive electrode active material

Abstract

To provide a novel manufacturing method of a cathode active material.SOLUTION: A manufacturing method of a cathode active material includes: creating an acid solution by mixing a water solution containing nickel, cobalt, and manganese and a water solution containing a first additive element; forming a composite hydroxide having nickel, cobalt, manganese, and the first additive element by reacting the acid solution and an alkaline solution; forming a complex oxide by mixing the composite hydroxide and a lithium source, and performing first heating; and mixing the complex oxide and a second additive element source, and performing second heating. In the manufacturing method of the cathode active material, the first additive element is at least one selected from gallium, boron, aluminum, indium, magnesium, and fluorine, further the second additive element is at least one selected from calcium, gallium, boron, aluminum, indium, magnesium, and fluorine.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] One aspect of the present invention relates to an object, a method, or a manufacturing method. One aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. One aspect of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, or an electronic device, or a manufacturing method thereof. In particular, one aspect of the present invention relates to a positive electrode active material for a lithium ion secondary battery and a manufacturing method thereof.

Background Art

[0002] <{ In recent years, lithium ion secondary batteries with high output and high capacity have rapidly increased in demand and have become indispensable in modern society as an energy source that can be repeatedly used.

[0003] Among them, lithium ion secondary batteries for portable electronic devices are required to have a large discharge capacity per unit weight and excellent charge and discharge characteristics. To meet these requirements, improvements to the positive electrode active materials of lithium ion secondary batteries are actively underway. For example, Patent Document 1 discloses a positive electrode active material with excellent charge and discharge characteristics. [[ID=1&]]

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Improvements are desired in various aspects such as capacity, cycle characteristics, charge and discharge characteristics, reliability, safety, or cost of lithium ion secondary batteries and the positive electrode active materials used therein.

[0006] In view of the above, one aspect of the present invention aims to provide a positive electrode active material with low degradation and a method for producing the same. Alternatively, one aspect of the present invention aims to provide a positive electrode active material with low cost and a method for producing the same. Alternatively, one aspect of the present invention aims to provide a positive electrode active material with a high proportion of nickel as a transition metal and a method for producing the same. Alternatively, one aspect of the present invention aims to provide a positive electrode active material with good charge-discharge characteristics and a method for producing the same. Alternatively, one aspect of the present invention aims to provide a highly safe secondary battery and a method for producing the same. Alternatively, one aspect of the present invention aims to provide a novel method for producing a positive electrode active material.

[0007] Furthermore, the description of the above problems does not preclude the existence of other problems. It is also possible to extract problems other than those described above from the description, drawings, and claims. Moreover, one aspect of the present invention does not need to solve all of the above problems, but solves at least one of them. [Means for solving the problem]

[0008] To solve the above problems, in one aspect of the present invention, a positive electrode active material having an additive element is prepared. The additive element may be added when preparing a composite hydroxide that serves as a precursor for the positive electrode active material. It may also be added when mixing the precursor with a lithium source. Alternatively, the additive element may be added after preparing a composite oxide containing lithium and a transition metal. Furthermore, the additive element may be added at multiple of these steps.

[0009] One aspect of the present invention is a method for producing a positive electrode active material, comprising reacting an aqueous solution containing nickel, cobalt, and manganese with an alkaline solution to form a composite hydroxide containing nickel, cobalt, and manganese, mixing the composite hydroxide with a lithium source and a first additive element source, and heating the mixture, wherein the first additive element is at least one selected from gallium, boron, aluminum, indium, magnesium, or fluorine.

[0010] In the above, the first additive element is preferably gallium, and the first additive element source is preferably gallium hydroxide, gallium oxyhydroxide, or an organic salt of gallium.

[0011] Another aspect of the present invention is a method for producing a positive electrode active material, comprising: reacting an aqueous solution containing nickel, cobalt, and manganese with an alkaline solution to form a composite hydroxide containing nickel, cobalt, and manganese; mixing the composite hydroxide with a lithium source and performing a first heating to form a composite oxide; mixing the composite oxide with a first additive element source and performing a second heating, wherein the first additive element is at least one selected from calcium, gallium, boron, aluminum, indium, magnesium, or fluorine.

[0012] In the above, it is preferable that the second heating is performed at a temperature above 750°C and below 850°C.

[0013] Furthermore, in the above, the first additive element is preferably gallium, and the compound having the first additive element is preferably gallium hydroxide, gallium oxyhydroxide, or an organic salt of gallium.

[0014] Another aspect of the present invention is a method for producing a positive electrode active material, comprising: mixing an aqueous solution containing nickel, cobalt, and manganese with an aqueous solution containing a first additive element to prepare an acid solution; reacting the acid solution with an alkaline solution to form a composite hydroxide containing nickel, cobalt, manganese, and the first additive element; mixing the composite hydroxide with a lithium source and performing a first heating to form a composite oxide; mixing the composite oxide with a second additive element source and performing a second heating, wherein the first additive element is at least one selected from gallium, boron, aluminum, indium, magnesium, or fluorine, and the second additive element is at least one selected from calcium, gallium, boron, aluminum, indium, magnesium, or fluorine.

[0015] In the above, it is preferable that the second heating is performed at a temperature above 750°C and below 850°C.

[0016] Furthermore, in the above, it is preferable that the first additive element is gallium, the source of the first additive element is gallium hydroxide, gallium oxyhydroxide, or an organic acid salt of gallium, and the second additive element is calcium, the source of the second additive element is preferably calcium carbonate or calcium fluoride.

[0017] Another aspect of the present invention is a secondary battery having a positive electrode active material prepared by the method described above.

[0018] Another aspect of the present invention is a vehicle having a secondary battery having a positive electrode active material prepared by the above method, and at least one of a motor, a brake, and a control circuit. [Effects of the Invention]

[0019] According to one aspect of the present invention, a positive electrode active material with low degradation and a method for producing the same can be provided. Alternatively, according to one aspect of the present invention, a positive electrode active material with low cost and a method for producing the same can be provided. Alternatively, according to one aspect of the present invention, a positive electrode active material with a high proportion of nickel as a transition metal and a method for producing the same can be provided. Alternatively, according to one aspect of the present invention, a positive electrode active material with good charge-discharge characteristics and a method for producing the same can be provided. Alternatively, according to one aspect of the present invention, a highly safe secondary battery and a method for producing the same can be provided. Alternatively, according to one aspect of the present invention, a novel method for producing a positive electrode active material can be provided.

[0020] Furthermore, the description of these effects does not preclude the existence of other effects. Moreover, one aspect of the present invention does not necessarily have to possess all of these effects. Other effects will naturally become apparent from the description in the specification, drawings, and claims, and it is possible to extract other effects from the description in the specification, drawings, and claims. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 is a flowchart illustrating the method for preparing the positive electrode active material. [Figure 2] Figure 2 is a flowchart illustrating the method for preparing the positive electrode active material. [Figure 3] Figure 3 is a flowchart illustrating the method for preparing the positive electrode active material. [Figure 4] Figure 4 is a flowchart illustrating the method for preparing the positive electrode active material. [Figure 5] Figure 5 is a flowchart illustrating the method for preparing the positive electrode active material. [Figure 6] Figure 6 is a flowchart illustrating the method for preparing the positive electrode active material. [Figure 7] Figure 7 is a flowchart illustrating the method for preparing the positive electrode active material. [Figure 8] Figure 8 is a flowchart illustrating the method for preparing the positive electrode active material. [Figure 9] Figure 9 illustrates the coprecipitation synthesis apparatus. [Figure 10] Figure 10 is a diagram illustrating the coprecipitation synthesis apparatus. [Figure 11] Figure 11 is a diagram illustrating the model used in the calculations. [Figure 12] Figure 12 is a graph showing the calculation results. [Figure 13] Figures 13(A) through 13(D) illustrate the model used in the calculations. [Figure 14] Figures 14(A) and 14(B) illustrate the calculation results. [Figure 15] Figure 15(A) is an exploded perspective view of a coin-type rechargeable battery, Figure 15(B) is a perspective view of a coin-type rechargeable battery, and Figure 15(C) is a cross-sectional perspective view thereof. [Figure 16] Figures 16(A) and 16(B) show examples of cylindrical secondary batteries, Figure 16(C) shows examples of multiple cylindrical secondary batteries, and Figure 16(D) shows examples of energy storage systems with multiple cylindrical secondary batteries. [Figure 17]Figures 17(A) and 17(B) illustrate examples of secondary batteries, while Figure 17(C) shows the inside of a secondary battery. [Figure 18] Figures 18(A) through 18(C) illustrate examples of secondary batteries. [Figure 19] Figures 19(A) and 19(B) show the external appearance of a secondary battery. [Figure 20] Figures 20(A) to 20(C) illustrate the method for manufacturing a secondary battery. [Figure 21] Figures 21(A) to 21(C) show examples of battery pack configurations. [Figure 22] Figures 22(A) and 22(B) illustrate examples of secondary batteries. [Figure 23] Figures 23(A) through 23(C) illustrate examples of secondary batteries. [Figure 24] Figures 24(A) and 24(B) illustrate examples of secondary batteries. [Figure 25] Figure 25(A) is a perspective view of the battery pack, Figure 25(B) is a block diagram of the battery pack, and Figure 25(C) is a block diagram of a vehicle having the battery pack and motor. [Figure 26] Figures 26(A) to 26(D) illustrate an example of a transport vehicle. [Figure 27] Figures 27(A) and 27(B) illustrate the energy storage device. [Figure 28] Figure 28(A) shows an electric bicycle, Figure 28(B) shows a secondary battery for an electric bicycle, and Figure 28(C) illustrates an electric motorcycle. [Figure 29] Figures 29(A) to 29(D) illustrate an example of an electronic device. [Figure 30] Figure 30(A) shows an example of a wearable device, Figure 30(B) is a perspective view of a wristwatch-type device, Figure 30(C) is a side view of a wristwatch-type device, and Figure 30(D) is a diagram illustrating an example of wireless earphones. [Figure 31]Figures 31(A) and 31(B) are SEM images of the positive electrode active material. [Figure 32] Figures 32(A) and 32(B) are SEM images of the positive electrode active material. [Figure 33] Figure 33(A) is a graph of charge-discharge cycles and discharge capacity, and Figure 33(B) is a graph of charge-discharge cycles and discharge capacity retention rate. [Figure 34] Figure 34(A) is a graph of charge-discharge cycles and discharge capacity, and Figure 34(B) is a graph of charge-discharge cycles and discharge capacity retention rate. [Modes for carrying out the invention]

[0022] Embodiments of the present invention will be described in detail below with reference to the drawings. However, it will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and its form and details can be modified in various ways. Furthermore, the present invention is not to be interpreted as being limited to the embodiments described below.

[0023] A secondary battery has, for example, a positive electrode and a negative electrode. The positive electrode is made up of a positive electrode active material. The positive electrode active material is, for example, a substance that performs a reaction that contributes to the charge and discharge capacity. However, the positive electrode active material may also contain a portion of substances that do not contribute to the charge and discharge capacity.

[0024] In this specification, the positive electrode active material of one aspect of the present invention may be expressed as a positive electrode material, a positive electrode material for secondary batteries, a composite oxide, etc. In this specification, it is preferable that the positive electrode active material of one aspect of the present invention has a compound. In this specification, it is preferable that the positive electrode active material of one aspect of the present invention has a composition. In this specification, it is preferable that the positive electrode active material of one aspect of the present invention has a composite.

[0025] In this specification, the term "crack" is defined not only as a crack generated during the manufacturing process of the positive electrode active material, but also as a crack generated by subsequent pressurization and charging / discharging.

[0026] In this specification, the surface layer of particles such as active material refers to, for example, the region extending from the surface inward within 50 nm, more preferably within 35 nm, even more preferably within 20 nm, and most preferably within 10 nm. Surfaces formed by cracks (which may also be called fissures) may also be considered the surface. The region deeper than the surface layer is referred to as the interior. In this case, particles such as active material refer to both primary and secondary particles.

[0027] In this specification, the term "particle" is not limited to spherical shapes (circular cross-sections), but may also refer to individual particles with elliptical, rectangular, trapezoidal, triangular, rounded quadrilateral, or asymmetrical cross-sections, and individual particles may also have irregular shapes.

[0028] In this specification, a value in the vicinity of a given numerical value A refers to a value between 0.9 × A and 1.1 × A.

[0029] (Embodiment 1) In this embodiment, an example of a method for producing a positive electrode active material 100, which is one aspect of the present invention, will be described using Figures 1 to 8.

[0030] Note that the flowcharts shown in Figures 1 to 8 indicate the order of elements connected by lines. They do not indicate the timing of elements that are not directly connected by lines. For example, steps S11 and S21 in Figure 1 are shown at the same height in the diagram, but they do not necessarily have to be performed simultaneously.

[0031] [Manufacturing Method 1] First, using Figures 1 and 2, we will explain the method of adding the additive element X1 when preparing the composite hydroxide 98, which serves as a precursor to the positive electrode active material 100.

[0032] <Step S11> In step S11 of Figures 1 and 2, a transition metal M source is first prepared.

[0033] As the transition metal M, at least one of nickel, cobalt, and manganese can be used. For example, as the transition metal M, nickel alone may be used, cobalt and manganese may be used, nickel and cobalt may be used, or nickel, cobalt, and manganese may be used.

[0034] When using at least one of nickel, cobalt, and manganese, it is preferable to use a mixing ratio of nickel, cobalt, and manganese that allows for a layered rock salt-type crystal structure.

[0035] In particular, it is preferable for the positive electrode active material 100 to contain a large amount of nickel as the transition metal M, as this may result in lower raw material costs and an increased charge / discharge capacity per unit weight compared to cases where cobalt is the main component. For example, it is preferable that the nickel content of the transition metal M exceeds 25 atomic percent, more preferably 60 atomic percent or more, and even more preferably 80 atomic percent or more. However, if the proportion of nickel is too high, the chemical stability and heat resistance may decrease. Therefore, it is preferable that the nickel content of the transition metal M be 95 atomic percent or less.

[0036] Having cobalt as the transition metal M is preferable because it results in a high average discharge voltage and contributes to the stabilization of the layered rock salt structure, thus enabling a highly reliable secondary battery. However, since cobalt is more expensive and less stable than nickel and manganese, if the proportion of cobalt is too high, the cost of manufacturing the secondary battery may increase. Therefore, it is preferable that the amount of cobalt in the transition metal M be between 2.5 atomic% and 34 atomic%.

[0037] Note that the transition metal M does not necessarily have to include cobalt.

[0038] The presence of manganese as the transition metal M is preferable because it improves heat resistance and chemical stability. However, if the proportion of manganese is too high, the discharge voltage and discharge capacity tend to decrease. Therefore, it is preferable that the amount of manganese in the transition metal M is between 2.5 atomic% and 34 atomic%.

[0039] Note that the transition metal M does not necessarily have to include manganese.

[0040] The transition metal M source is prepared as an aqueous solution containing the transition metal M. As the nickel source, an aqueous solution of a nickel salt can be used. Examples of nickel salts include nickel sulfate, nickel chloride, nickel nitrate, or their hydrates. Alternatively, nickel organic acid salts, such as nickel acetate, or their hydrates can be used. Furthermore, an aqueous solution of nickel alkoxide or an organic nickel complex can be used as the nickel source. In this specification, an organic acid salt refers to a compound of a metal with an organic acid such as acetic acid, citric acid, oxalic acid, formic acid, or butyric acid.

[0041] Similarly, aqueous solutions of cobalt salts can be used as a cobalt source. Examples of cobalt salts include cobalt sulfate, cobalt chloride, cobalt nitrate, or their hydrates. Organic cobalt salts, such as cobalt acetate, or their hydrates can also be used. Furthermore, aqueous solutions of cobalt alkoxides and organic cobalt complexes can be used as cobalt sources.

[0042] Similarly, aqueous solutions of manganese salts can be used as a manganese source. Examples of manganese salts include manganese sulfate, manganese chloride, manganese nitrate, or their hydrates. Organic manganese salts, including manganese acetate, or their hydrates can also be used. Furthermore, aqueous solutions of manganese alkoxides or organic manganese complexes can be used as a manganese source.

[0043] In this embodiment, an aqueous solution is prepared by dissolving nickel sulfate, cobalt sulfate, and manganese sulfate in pure water as the transition metal M source. The atomic ratio of nickel, cobalt, and manganese is Ni:Co:Mn = 8:1:1 or close to this. The aqueous solution exhibits acidity.

[0044] <Step S12> Furthermore, in step S12 of Figures 1 and 2, a source of additive element X1 is prepared.

[0045] As the additive element X1, at least one can be selected from, for example, gallium, boron, aluminum, indium, fluorine, magnesium, titanium, yttrium, zirconium, niobium, lanthanum, and hafnium. For example, as the additive element X1, only gallium may be used, two types of elements (gallium and aluminum) may be used, or three types of elements (gallium, boron, and aluminum) may be used.

[0046] The source of additive element X1 is also prepared as an aqueous solution containing additive element X1. As a gallium source, for example, an aqueous solution of gallium hydroxide or a gallium salt can be used. Examples of gallium salts include gallium sulfate, gallium acetate, or gallium nitrate.

[0047] As a boron source, for example, an aqueous solution of boric acid or a borate salt can be used.

[0048] As an aluminum source, for example, an aqueous solution of aluminum hydroxide or an aluminum salt can be used. Examples of aluminum salts include aluminum sulfate, aluminum acetate, or aluminum nitrate.

[0049] As an indium source, for example, an aqueous solution of indium hydroxide or an indium salt can be used. Examples of indium salts include indium sulfate, indium acetate, or indium nitrate.

[0050] As a fluorine source, for example, aqueous solutions of gallium fluoride, boron fluoride, aluminum fluoride, or magnesium fluoride can be used.

[0051] As a magnesium source, for example, aqueous solutions of magnesium hydroxide, magnesium carbonate, or magnesium fluoride can be used.

[0052] In this embodiment, gallium is used as the additive element X1, and an aqueous solution of gallium sulfate dissolved in pure water is prepared as the source of the additive element X1.

[0053] <Step S13> As shown in step S13 of Figure 2, a chelating agent may also be prepared. Examples of chelating agents include glycine, oxine, 1-nitroso-2-naphthol, 2-mercaptobenzothiazole, or EDTA (ethylenediaminetetraacetic acid). Multiple agents selected from glycine, oxine, 1-nitroso-2-naphthol, 2-mercaptobenzothiazole, or EDTA may also be used. At least one of these is dissolved in pure water to form a chelating aqueous solution. The chelating agent is a complexing agent that forms a chelating compound and is preferred over general complexing agents. Of course, a complexing agent may be used instead of a chelating agent, and ammonia water can be used as the complexing agent.

[0054] Using a chelate aqueous solution is preferable because it suppresses the unwanted generation of crystal nuclei and promotes crystal growth. Since the generation of unwanted nuclei is suppressed, the formation of fine particles is suppressed, and a composite hydroxide with a good particle size distribution can be obtained. In addition, using a chelate aqueous solution can slow down the acid-base reaction, and by allowing the reaction to proceed gradually, nearly spherical secondary particles can be obtained. Glycine has the effect of maintaining a constant pH value at or near 9.0 to 10.0, and using a glycine aqueous solution as the chelate aqueous solution is preferable because it makes it easier to control the pH of the reaction vessel when obtaining the composite hydroxide 98. Furthermore, the glycine concentration of the glycine aqueous solution is preferably 0.05 mol / L to 0.5 mol / L, and more preferably 0.1 mol / L to 0.2 mol / L.

[0055] <Step S14> Next, in step S14 of Figure 1, the transition metal M source and the additive element X1 source are mixed to prepare an acid solution. A chelating agent may be further added as shown in Figure 2.

[0056] If the ratio of additive element X1 to the transition metal M is too low, the effect of suppressing the degradation of the positive electrode active material 100 or improving the charge-discharge characteristics cannot be sufficiently obtained. On the other hand, if the ratio of additive element X1 is too high, disadvantages such as a decrease in the charge-discharge capacity of the positive electrode active material 100 and an increase in cost may occur. For this reason, it is preferable to mix the additive elements such that the sum of the additive elements X1 is 10 atomic percent or less relative to the sum of all the transition metals M and additive elements X1. It is even more preferable to mix them so that the sum is between 1 atomic percent and 4 atomic percent. That is, when the atomic ratio is (M+X1):X1=1:A, it is preferable that A≦0.1, and more preferably that 0.01≦A≦0.04.

[0057] In this embodiment, nickel, cobalt, manganese, and gallium are mixed in such a way that when the atomic ratio Ni:Co:Mn:Ga = 80:10:(10-x):x, 1 ≤ x ≤ 4.

[0058] <Step S21> Next, in step S21 of Figures 1 and 2, an alkaline solution is prepared. As the alkaline solution, an aqueous solution containing, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia can be used. An aqueous solution obtained by dissolving these in pure water can be used. Alternatively, an aqueous solution obtained by dissolving multiple substances selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia in pure water may also be used.

[0059] The pure water preferred for use in the above transition metal M source, additive element X1 source, and alkaline solution is water with a resistivity of 1 MΩ·cm or more, more preferably water with a resistivity of 10 MΩ·cm or more, and even more preferably water with a resistivity of 15 MΩ·cm or more. Water that satisfies this resistivity is highly pure and contains very few impurities.

[0060] <Step S22> Furthermore, as shown in step S22 of Figure 2, it is preferable to prepare water in the reaction vessel. This water may be pure water, but it is more preferable to have an aqueous solution of the chelating agent. Therefore, this water can be called a chelating aqueous solution, a reaction vessel filling solution, or a preparation solution. When using a chelating aqueous solution, the description in step S13 can be taken into consideration.

[0061] <Step S31> Next, in step S31 of Figures 1 and 2, the acid solution and the alkaline solution are mixed and reacted. This reaction can be called a coprecipitation reaction, a neutralization reaction, or an acid-base reaction.

[0062] During the coprecipitation reaction in step S31, it is preferable to maintain the pH of the reaction system at 9.0 to 11.0, preferably 9.8 to 10.3.

[0063] For example, when adding an alkaline solution to a reaction vessel and then adding an acidic solution dropwise, it is preferable to maintain the pH of the aqueous solution in the reaction vessel within the above-mentioned range. The same applies when adding an acidic solution to the reaction vessel first and then adding an alkaline solution dropwise. When the volume of solution in the reaction vessel is between 200 mL and 350 mL, it is preferable to set the dropping rate of the acidic or alkaline solution to between 0.01 mL / min and 1 mL / min, preferably between 0.1 mL / min and 0.8 mL / min, as this makes it easier to control the pH conditions. The reaction vessel includes a reaction vessel, etc.

[0064] It is advisable to stir the aqueous solution in the reaction vessel using a stirring device. The stirring device may include a stirrer or impeller. The impeller can have two to six blades; for example, if four blades are used, they should be arranged in a cross shape when viewed from above. The rotation speed of the stirring device should be between 800 rpm and 1200 rpm.

[0065] It is preferable to adjust the temperature of the reaction vessel to be between 50°C and 90°C. The addition of the alkaline or acidic solution should be started after the temperature reaches this level.

[0066] Furthermore, it is preferable to maintain an inert atmosphere inside the reaction vessel. In this case, nitrogen or argon can be used as the inert atmosphere. If a nitrogen atmosphere is used, nitrogen gas should be introduced at a flow rate of 0.5 L / min to 2 L / min.

[0067] It is also advisable to install a reflux condenser in the reaction vessel. The reflux condenser allows nitrogen gas to be released from the reaction vessel and water to be returned to the reaction vessel.

[0068] The above coprecipitation reaction precipitates a complex hydroxide 98 containing the transition metal M and the additive element X1.

[0069] <Step S32> To recover the complex hydroxide 98, it is preferable to perform filtration as shown in step S32 of Figure 2. Suction filtration is preferred. When filtration, it is preferable to wash the reaction product precipitated in the reaction vessel with pure water, then add an organic solvent with a low boiling point (e.g., acetone) before performing the filtration.

[0070] <Step S33> As shown in step S33 of Figure 2, the filtered composite hydroxide 98 should be dried. For example, it can be dried under vacuum at a temperature between 60°C and 90°C for 0.5 hours to 3 hours. In this way, the composite hydroxide 98 can be obtained.

[0071] In this way, a composite hydroxide 98 having a transition metal M and an additive element X1 can be obtained. In this specification, the term "composite hydroxide 98" refers to a hydroxide of multiple metals. The composite hydroxide 98 can be considered a precursor of the positive electrode active material 100.

[0072] The composite hydroxide 98 is obtained as secondary particles formed by the aggregation of primary particles. In this specification, primary particles refer to the smallest unit of particles (clumps) that do not have grain boundaries when observed, for example, at 5000x magnification using an SEM (scanning electron microscope). In other words, primary particles refer to the smallest unit of particles surrounded by the grain boundaries of secondary particles. Secondary particles refer to particles that are aggregated from the primary particles so as to share a part of the grain boundary (such as the outer circumference of the primary particles) and do not easily separate (particles independent of others). That is, secondary particles may have grain boundaries.

[0073] <Step S41> Next, in step S41 of Figures 1 and 2, a lithium source is prepared. For example, lithium hydroxide, lithium carbonate, or lithium nitrate can be used as the lithium source. It is particularly preferable to use a lithium compound with a low melting point, such as lithium hydroxide (melting point 462°C). Since positive electrode active materials with a high nickel content are more prone to cation mixing compared to lithium cobalt oxide, etc., heating in step S54, etc., must be performed at a low temperature. For this reason, it is preferable to use a material with a low melting point.

[0074] The lithium source described above preferably uses high-purity materials. Specifically, the purity of the material should be 4N (99.99%) or higher, preferably 4N5 (99.995%) or higher, and even more preferably 5N (99.999%) or higher. Using high-purity materials can improve the battery characteristics of the secondary battery.

[0075] <Step S51> Next, in step S51 of Figures 1 and 2, the composite hydroxide 98 and the lithium source are mixed. Mixing can be done dry or wet. For example, a ball mill or bead mill can be used for mixing. When using a ball mill, it is preferable to use zirconia balls as the media. Also, when using a ball mill or bead mill, it is preferable to set the peripheral speed to 100 mm / sec or more and 2000 mm / sec or less in order to suppress contamination from the media or material. The cobalt compound and lithium compound may be pulverized at the same time as mixing.

[0076] <Steps S52 to S55> Next, the mixture of composite hydroxide 98 and lithium source is heated. Heating may be performed once, as shown in step S54 of Figure 1, but it is more preferable to perform it twice, as shown in steps S52 and S54 of Figure 2. Although not shown, it may be heated three or more times.

[0077] To distinguish it from other heating processes, step S52 is sometimes referred to as the first heating step and step S54 as the second heating step in Figure 2.

[0078] For the heating process, an electric furnace or a rotary kiln can be used as the firing apparatus. Containers such as crucibles, pods, and setters used during heating are preferably made of materials that do not easily release impurities. For example, a crucible made of 99.9% pure aluminum oxide is suitable. For mass production, pods made of mullite cordierite (Al2O3·SiO2·MgO) are suitable. Furthermore, it is preferable to heat these containers with lids on.

[0079] When heating in step S52 as shown in Figure 2, the heating temperature is preferably between 400°C and 700°C. Furthermore, the heating time in step S52 is preferably between 1 hour and 10 hours. It is preferable that the heating in step S52 is performed at a lower temperature and / or for a shorter time than the heating in step S54, which is performed later.

[0080] The heating atmosphere is preferably an oxygen-containing atmosphere, or a so-called dry air atmosphere with low water content (for example, a dew point of -50°C or lower, more preferably a dew point of -80°C or lower).

[0081] For example, when heating at 850°C for 2 hours, the heating rate should be between 150°C / hour and 250°C / hour. Furthermore, the flow rate of dry air that can form a dry atmosphere should preferably be between 8 L / min and 15 L / min. Regarding the cooling time, it is preferable that it be between 10 hours and 50 hours from the specified temperature to room temperature, and the cooling rate can be calculated from the cooling time, etc.

[0082] The heating in step S52 is expected to release the gaseous components in the composite hydroxide 98 and lithium source, and by using this composite hydroxide 98 and lithium source, a composite oxide with fewer impurities can be obtained.

[0083] Furthermore, as shown in steps S53 and S55 of Figure 2, it is preferable to have a crushing step after heating. Crushing can be done, for example, in a mortar. Classification may also be done using a sieve. By having a crushing step, the particle size and / or shape of the positive electrode active material 100 can be made more uniform.

[0084] The heating in step S54 shown in Figures 1 and 2 is preferably carried out at a temperature above 700°C and below 1050°C, more preferably between 800°C and 1000°C, and even more preferably between 800°C and 950°C. In producing the positive electrode active material 100 through this heat treatment, it is important to heat at least to the temperature at which each raw material melts.

[0085] The heating time can be, for example, between 1 hour and 100 hours, and is preferably between 2 hours and 20 hours.

[0086] The heating atmosphere, heating rate, cooling time, etc., can be determined by referring to the description in step S52.

[0087] Furthermore, when collecting the heated material, it is preferable to transfer it from the crucible to a mortar before collection, as this prevents impurities from contaminating the material. The mortar itself should also be made of a material that does not easily release impurities; specifically, a mortar made of aluminum oxide with a purity of 90% or higher, preferably 99% or higher, is recommended.

[0088] The positive electrode active material 100 can be produced through the above process.

[0089] The positive electrode active material 100 is preferred because it contains few impurities. However, if a sulfide is used as the starting material, such as a transition metal M source, sulfur may be detected in the positive electrode active material 100. The sulfur concentration can be measured by performing elemental analysis of the entire particle of the positive electrode active material 100 using GD-MS (glow discharge mass spectrometry), ICP-MS (inductively coupled plasma mass spectrometry), etc.

[0090] [Preparation Method 2] Next, using Figures 3 and 4, we will explain the method for adding element X2 when mixing the composite hydroxide 98 with the lithium source. We will mainly describe the steps that differ from those in Figures 1 and 2, while other steps can be referenced from Figures 1 and 2.

[0091] <Steps S11 to S41> A composite hydroxide 98 containing a transition metal M is obtained by the same process as steps S11 to S31 in Figures 1 and 2, except that the additive element X1 is not used. A lithium source is also prepared in the same manner as in step S41 in Figures 1 and 2.

[0092] <Step S42> Next, in step S42 of Figures 3 and 4, a source of additive element X2 is prepared.

[0093] As the additive element X2, at least one can be selected from, for example, gallium, boron, aluminum, indium, fluorine, magnesium, titanium, yttrium, zirconium, niobium, lanthanum, and hafnium. For example, when using only gallium as the additive element X2, two types of elements such as gallium and aluminum can be used, or three types of elements such as gallium, boron, and aluminum can be used. The source of the additive element X2 does not necessarily have to be an aqueous solution.

[0094] As a gallium source, for example, gallium oxide, gallium oxyhydroxide, gallium hydroxide, or gallium salts can be used. Examples of gallium sources include gallium sulfate, gallium acetate, or gallium nitrate. Gallium alkoxides may also be used.

[0095] As a boron source, for example, boric acid or borate salts can be used.

[0096] As an aluminum source, for example, aluminum oxide, aluminum hydroxide, or aluminum salts can be used. Examples of aluminum salts include aluminum sulfate, aluminum acetate, or aluminum nitrate. Aluminum alkoxides may also be used.

[0097] As an indium source, for example, indium oxide, indium sulfate, indium acetate, or indium nitrate can be used. Indium alkoxides may also be used.

[0098] As fluorine sources, for example, gallium fluoride, boron fluoride, aluminum fluoride, and magnesium fluoride can be used.

[0099] For example, magnesium oxide, magnesium hydroxide, magnesium carbonate, and magnesium fluoride can be used as magnesium sources. Magnesium alkoxides may also be used.

[0100] In this embodiment, gallium is used as the additive element X2, and gallium oxyhydroxide is prepared as the source of the additive element X2.

[0101] <Steps S51 through S55> Subsequently, heating and other processes can be performed in the same manner as in steps S51 to S55 of Figures 1 and 2 to produce the positive electrode active material 100.

[0102] [Method 3 of preparation] Next, using Figures 5 and 6, a method for preparing a composite oxide 99 containing lithium and a transition metal M, followed by the addition of the additive element X3, will be described. The process described will mainly differ from that described in Figures 1 to 4; other steps can be considered in relation to Figures 1 to 4.

[0103] <Steps S11 through Step S55> A composite hydroxide 98 having a transition metal M is obtained by the same process as in steps S11 to S33 in Figures 3 and 4. Then, the composite hydroxide 98 and the lithium source are heated or otherwise subjected to the same process as in steps S41 to S54 in Figures 1 and 2. It is more preferable to crush the material after heating, as shown in step S55 in Figure 2.

[0104] The material produced through the above process is referred to as composite oxide 99 in this manufacturing method, as shown in Figures 5 and 6.

[0105] <Step S61> Next, in step S61 of Figures 5 and 6, a source of additive element X3 is prepared.

[0106] As the additive element X3, at least one can be selected from, for example, calcium, gallium, boron, aluminum, indium, fluorine, magnesium, titanium, yttrium, zirconium, niobium, lanthanum, and hafnium. For example, as the additive element X3, only calcium may be used, only gallium may be used, only aluminum may be used, two types of elements, calcium and gallium, two types of elements, calcium and aluminum, or three types, calcium, gallium, and aluminum, may be used.

[0107] It is preferable to use a material that does not contain water, or contains less water than the additive element X1 source, for the additive element X3 source. This is to avoid the reaction between the composite oxide 99 and water.

[0108] For example, calcium oxide, calcium hydroxide, or calcium salts can be used as calcium sources. Examples of calcium salts include calcium carbonate and calcium fluoride.

[0109] For example, titanium oxide or titanium salts can be used as the titanium source. Examples of titanium salts include titanium fluoride, titanium sulfate, titanium acetate, or titanium nitrate. Titanium alkoxides may also be used.

[0110] For example, zirconium oxide or zirconium salts can be used as zirconium sources. Examples of zirconium salts include zirconium fluoride, zirconium sulfate, zirconium acetate, or zirconium nitrate. Zirconium alkoxides may also be used.

[0111] For the gallium, boron, aluminum, indium, fluorine, and magnesium sources, the same materials as those used for additive element X2 can be used.

[0112] <Step S71> Next, in step S71 of Figures 5 and 6, the composite oxide 99 and the additive element X3 source are mixed. This mixing can be carried out in the same manner as in step S51.

[0113] <Step S72> Next, as step S72 in Figures 5 and 6, the mixture of the composite oxide 99 and the additive element X3 source is heated.

[0114] The heating in step S72 is preferably carried out at a temperature of 700°C or higher and less than 1050°C, and more preferably at a temperature of 750°C or higher and 850°C or lower. The heating time can be, for example, 1 hour or more and 100 hours or less, and is preferably 2 hours or more and 10 hours or less. The heating in step S72 is preferably carried out at a lower temperature and / or for a shorter heating time than the heating in step S54.

[0115] Other conditions such as heating atmosphere, heating rate, and cooling time can be considered in reference to the description in step S54.

[0116] <Step S73> As shown in step S73 of Figure 6, it is preferable to have a crushing step after heating. Crushing can be carried out in the same manner as in steps S53 and S55.

[0117] The positive electrode active material 100 can be produced through the above process.

[0118] As shown in the fabrication methods in Figures 5 and 6, by fabricating the composite oxide 99 and then mixing it with the additive element X3 source and heating it, it may be possible to change the depth-direction concentration profile of the elements in the positive electrode active material 100. For example, the concentration of additive element X3 in the surface layer can be increased compared to the interior of the positive electrode active material 100. Therefore, the effect of the additive element that contributes to the stabilization of the surface layer can be enhanced.

[0119] [Manufacturing Method 4] Figures 1 to 6 illustrate a method of adding additive elements in one step, but the present invention is not limited to this, and the steps in Figures 1 to 6 can be combined as appropriate. A method of adding additive elements in two steps will be explained using Figure 7, and a method of adding additive elements in three steps will be explained using Figure 8.

[0120] In the manufacturing method shown in Figure 7, first, a composite hydroxide 98 having a transition metal M and an additive element X1 is obtained by following the same steps as in steps S11 to S33 in Figure 1. Next, the additive element X3 source is mixed and heated by following the same steps as in steps S41 to S73 in Figure 5 to obtain a positive electrode active material 100.

[0121] In the manufacturing method shown in Figure 8, first, a composite hydroxide 98 having a transition metal M and an additive element X1 is obtained by following the same steps as in steps S11 to S33 in Figure 2. Next, an additive element X2 source is added by following the same steps as in steps S41 to S55 in Figure 4 to obtain a composite oxide 99 having a transition metal M, an additive element X1, and an additive element X2 source. Furthermore, a positive electrode active material 100 is obtained by following the same steps as in steps S61 to S73 in Figure 6.

[0122] Although not shown in the diagram, the additive elements may be added in two stages: from additive element X1 source and additive element X2 source, or from additive element X2 source and additive element X3 source. Furthermore, the additive elements may be added in processes other than those described above.

[0123] In this way, by separating the process of introducing multiple additive elements, it is sometimes possible to change the depth profile of each element. For example, the concentration of a particular additive element can be increased in the surface layer compared to the interior of the positive electrode active material 100. Also, using the number of atoms of the transition metal M as a reference, the ratio of the number of atoms of a particular additive element to this reference can be made higher in the surface layer than in the interior.

[0124] This embodiment can be used in combination with other embodiments.

[0125] (Embodiment 2) In this embodiment, a coprecipitation synthesis apparatus that can be used to produce the positive electrode active material described in Embodiment 1 will be explained with reference to Figures 9 and 10.

[0126] The coprecipitation synthesis apparatus 170 shown in Figure 9 has a reaction vessel 171, which has a reaction container. A separable flask may be used at the bottom of the reaction container, and a separable cover may be used at the top. The separable flask may be cylindrical or round. In the case of a cylindrical shape, the separable flask has a flat bottom. The atmosphere inside the reaction vessel 171 can be controlled using at least one inlet of the separable cover. For example, the atmosphere is preferably an inert atmosphere, and preferably contains nitrogen. In that case, it is preferable to perform nitrogen flow. It is also preferable to bubble nitrogen in the water 192 inside the reaction vessel 171. The coprecipitation synthesis apparatus 170 may also be equipped with a reflux condenser 191 connected to at least one inlet of the separable cover, as shown in Figure 10. This reflux condenser 191 can discharge atmospheric gas, such as nitrogen, from inside the reaction vessel 171 and return water to the reaction vessel 171. The atmosphere inside the reaction vessel 171 only needs to have an airflow sufficient to discharge the gas generated by the thermal decomposition reaction caused by the heat treatment.

[0127] First, water 192 is placed in reaction vessel 171, and then the acid solution and alkaline solution are added dropwise to reaction vessel 171. The water 192 prepared in reaction vessel 171 is sometimes referred to as the starting solution. The starting solution may also be referred to as the preparation solution, and may refer to the aqueous solution before the reaction, i.e., the initial aqueous solution.

[0128] The following describes the other components of the coprecipitation synthesis apparatus 170 shown in Figures 9 and 10. The coprecipitation synthesis apparatus 170 includes a stirring unit 172, a stirring motor 173, a thermometer 174, a tank 175, a pipe 176, a pump 177, a tank 180, a pipe 181, a pump 182, a tank 186, a pipe 187, a pump 188, and a control device 190, etc.

[0129] The stirring unit 172 is capable of stirring the water 192 in the reaction vessel 171, and further has a stirring motor 173 as a power source for rotating the stirring unit 172. The stirring unit 172 has paddle-shaped stirring blades (referred to as paddle blades), and the paddle blades have two to six blades, and the blades may have an inclination of 40 degrees to 70 degrees.

[0130] The thermometer 174 can measure the temperature of the water 192. The temperature of the reaction vessel 171 can be controlled using a heater and a cooling thermoelectric element to maintain a constant temperature of the water 192. An example of a cooling thermoelectric element is a Peltier element. Although not shown, a pH meter can also be placed in the reaction vessel 171 to measure the pH of the water 192.

[0131] Each tank can store different raw material aqueous solutions. For example, each tank can be filled with a transition metal M source or an acid solution, and an alkaline solution. A tank filled with water to function as a loading liquid may also be provided. Each tank is equipped with a pump, which can be used to drip the raw material aqueous solution into the reaction vessel 171 through a pipe. Each pump can control the dripping rate, i.e., the flow rate, of the raw material aqueous solution. Instead of a pump, a valve may be provided in the pipe 176 to control the dripping rate, i.e., the flow rate, of the raw material aqueous solution.

[0132] The control device 190 is electrically connected to the stirring motor 173, thermometer 174, pump 177, pump 182, and pump 188, and can control the rotation speed of the stirring unit 172, the temperature of the water 192, the amount of each raw material aqueous solution dispensed, and so on.

[0133] The rotation speed of the stirring unit 172, specifically the rotation speed of the paddle blades, should be, for example, 800 rpm to 1200 rpm. It is also preferable to perform the stirring while maintaining the water 192 at 50°C to 90°C. At that time, it is preferable to dropwise add the acid solution, etc., into the reaction vessel 171 at a constant rate. Of course, the rotation speed of the paddle blades is not limited to a constant rate and can be adjusted as appropriate. For example, it is possible to change the rotation speed according to the amount of liquid in the reaction vessel 171. Furthermore, the dropping rate of the acid solution, etc., can also be adjusted. It is preferable to adjust the dropping rate to maintain a constant pH in the reaction vessel 171. Alternatively, the dropping rate may be controlled so that when the pH of the acid solution, etc., deviates from the desired pH value, an alkaline solution is added. The above pH value should be between 9.0 and 11.0, preferably within the range of 9.8 to 10.3.

[0134] After the above steps, the reaction product precipitates in the reaction vessel 171. The reaction product contains a complex hydroxide 98. This reaction can be described as coprecipitation or co-precipitation, and this step may be described as the co-precipitation step.

[0135] This embodiment can be used in combination with other embodiments.

[0136] (Embodiment 3) In this embodiment, a positive electrode active material 100, which is one aspect of the present invention, will be described with reference to Figures 11 to 14.

[0137] The positive electrode active material 100 has secondary particles formed by the aggregation of primary particles. The positive electrode active material 100 may also have voids inside.

[0138] <Contained elements> The positive electrode active material 100 comprises lithium, a transition metal M, oxygen, and at least one of the additive element X. In this specification, additive element X refers to the sum of additive element X1, additive element X2, and additive element X3.

[0139] The positive electrode active material 100 can be described as a composite oxide represented by LiMO2 to which an additive element X is added. However, the positive electrode active material in one embodiment of the present invention only needs to have the crystal structure of a lithium composite oxide represented by LiMO2, and its composition is not strictly limited to Li:M:O=1:1:2.

[0140] The transition metal M and additive element X contained in the positive electrode active material 100, and their preferred proportions, can be referenced to the description in Embodiment 1.

[0141] <Elemental distribution> It is preferable that the additive element X in the positive electrode active material 100 has a concentration gradient. In particular, since the additive element X3 is added after the composite oxide 99 is prepared, it is easy for it to have a concentration gradient. For example, it is preferable that the positive electrode active material 100 has a surface layer and an interior, and that the concentration of the additive element X3 is higher in the surface layer than in the interior.

[0142] Unlike the interior of the crystal, the particle surface is in a state where the bonds are broken, and lithium is released from the surface during charging, making it a region where the lithium concentration tends to be lower than in the interior. Therefore, the surface layer is prone to instability and the crystal structure is easily disrupted. Thus, if an additive element X or compound (for example, an oxide of additive element X) that is chemically and structurally more stable than the lithium composite oxide represented by LiMO2 is present in the surface layer, changes in the crystal structure can be suppressed more effectively. Furthermore, if the concentration of additive element X3 in the surface layer is high, it can be expected that the corrosion resistance to hydrofluoric acid produced by the decomposition of the electrolyte will improve.

[0143] However, if the surface layer consists only of additive element X and oxygen, there is a risk that the lithium insertion and removal pathways will be blocked. Therefore, the surface layer must contain at least a transition metal M, and in the discharge state, it must also contain lithium and have pathways for lithium insertion and removal. Furthermore, it is preferable that the concentration of the transition metal M in the surface layer is higher than that of each additive element X.

[0144] The distribution of additive element X as described above reduces the degradation of the positive electrode active material 100 even after charging and discharging. In other words, it suppresses the degradation of the secondary battery. Furthermore, it makes for a highly safe secondary battery.

[0145] Furthermore, it is preferable that the transition metal M, particularly cobalt and nickel, is uniformly dissolved in the entire positive electrode active material 100.

[0146] Furthermore, in one embodiment of the present invention, the positive electrode active material 100 may be a positive electrode active material composite having a coating layer covering at least a portion of the positive electrode active material 100. For example, one or more of glass, oxide, and LiM2PO4 (where M2 is one or more selected from Fe, Ni, Co, and Mn) can be used as the coating layer.

[0147] As the glass coating layer of the positive electrode active material composite, a material having an amorphous portion can be used. Examples of materials having an amorphous portion include materials having one or more selected from SiO2, SiO, Al2O3, TiO2, Li4SiO4, Li3PO4, Li2S, SiS2, B2S3, GeS4, AgI, Ag2O, Li2O, P2O5, B2O3, and V2O5, and Li7P3S. 11 , or Li 1+x+y Al x Ti 2-x Si y P 3-y O 12For example, (0 < x < 2, 0 < y < 3) etc. can be used. The material having an amorphous part can be used in an entirely amorphous state or in a state of crystallized glass (also referred to as glass ceramics) where a part is crystallized. It is desirable for the glass to have lithium ion conductivity. Having lithium ion conductivity can also be said to have lithium ion diffusivity and lithium ion penetrability. Further, the glass preferably has a melting point of 800 °C or lower, more preferably 500 °C or lower. Also, it is preferable for the glass to have electronic conductivity. Further, the glass preferably has a softening point of 800 °C or lower, and for example, a Li2O - B2O3 - SiO2 - based glass can be used.

[0148] Examples of the oxide that the coating layer of the positive electrode active material composite has include aluminum oxide, zirconium oxide, hafnium oxide, niobium oxide, etc. Also, examples of LiM2PO4 (M2 is one or more selected from Fe, Ni, Co, Mn) that the coating layer of the positive electrode active material composite has include LiFePO4, LiNiPO4, LiCoPO4, LiMnPO4, LiFe a Ni b PO4, LiFe a Co b PO4, LiFe a Mn b PO4, LiNi a Co b PO4, LiNi a Mn b PO4 (a + b is 1 or less, 0 < a < 1, 0 < b < 1), LiFe c Ni d Co e PO4, LiFe c Ni d Mn e PO4, LiNi c Co d Mn e PO4 (c + d + e is 1 or less, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g Co h Mn i PO4 (f + g + h + i is 1 or less, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), etc.

[0149] A composite treatment can be used to fabricate the coating layer of the positive electrode active material composite. Examples of composite treatments include mechanical energy composite treatments such as mechanochemical methods, mechanofusion methods, and ball milling methods; liquid phase reaction composite treatments such as coprecipitation, hydrothermal methods, and sol-gel methods; and gas phase reaction composite treatments such as barrel sputtering, ALD (Atomic Layer Deposition), vapor deposition, and CVD (Chemical Vapor Deposition). For example, Picobond manufactured by Hosokawa Micron can be used as a mechanical energy composite treatment. Furthermore, it is preferable to perform one or more heat treatments during the composite treatment.

[0150] <Ease of each additive element X to enter nickel sites> The following describes the results of calculations regarding whether the additive elements X—boron, magnesium, aluminum, calcium, titanium, gallium, yttrium, zirconium, niobium, lanthanum, and hafnium—can stably exist at the nickel sites of layered rock salt-type lithium composite oxides represented by LiMO2. For comparison, the results for cobalt and manganese are also shown.

[0151] In this embodiment, the transition metal M includes nickel, cobalt, and manganese, and LiMO2, in which nickel accounts for the largest proportion, was used as a model for evaluation from the stabilization energy of the entire system.

[0152] Figure 11 shows the model used for the calculations. The energy change when nickel at substitution site 110, shown in the center of the model, is substituted with another metal element was calculated. The more stable the element, the more likely it is to exist at the nickel site.

[0153] The calculation conditions are shown in Table 1.

[0154] [Table 1]

[0155] The calculation results are shown in Figure 12. LS in the figure indicates low spin. Substitution with any of the following elements—boron, aluminum, titanium, gallium, yttrium, zirconium, niobium, lanthanum, and hafnium—resulted in greater stability than the unsubstituted or substituted with cobalt or manganese.

[0156] <Effect of adding element X on suppressing surface structure changes> Next, we will explain the results of calculations regarding the effect of using gallium, aluminum, magnesium, and calcium among the additive elements X on suppressing structural changes.

[0157] LiMO2, which has a high nickel content, is prone to cation mixing during repeated charging and discharging, where nickel moves to the lithium sites, and it is thought that the surface undergoes a structural change to NiO (nickel oxide). Nickel oxide is inert to battery reactions. Therefore, suppressing the structural change to NiO on the LiMO2 surface is important to inhibit degradation.

[0158] In this embodiment, the calculation was started with the pre-substitution model, where nickel moves to lithium sites. Additionally, assuming a high nickel content in LiMO2, the LiNiO2 model was used as the initial state. This is shown in Figure 13(A). Here, all lithium and nickel occupy the octahedral sites 108.

[0159] Following the initial state, the intermediate state was defined as a structure in which nickel migrated to tetrahedral site 104 in the lithium layer. This is shown in Figure 13(B).

[0160] The final state was a structure in which the nickel occupied the octahedral site 108. This is shown in Figure 13(C).

[0161] The tetrahedral site 104 is a site that is ionically bonded with four oxygen atoms, while the octahedral site 108 is a site that is ionically bonded with six oxygen atoms.

[0162] In this embodiment, we investigated whether substituting the additive element X with nickel sites would make structural changes from the initial state to the intermediate state less likely to occur. Figure 13(D) shows an example in which gallium is substituted with nickel sites, indicated by dashed lines.

[0163] The calculation conditions are shown in Table 2. The structures of the initial and intermediate states obtained as calculation results, when the additive element X is gallium, are shown in Figures 14(A) and 14(B).

[0164] [Table 2]

[0165] In the initial state shown in Figure 14(A) and the intermediate state shown in Figure 14(B), no significant strain occurred around the substituted gallium, clearly indicating that the gallium stably enters the nickel site.

[0166] Next, Table 3 shows the results of comparing the energy difference between the initial state and the intermediate state with and without the addition of element X.

[0167] [Table 3]

[0168] As is clear from Table 3, nickel-lithium exchange is less likely to occur when additive element X, such as calcium, gallium, aluminum, and magnesium, is present compared to the unsubstituted case. This effect was more pronounced with gallium, aluminum, and magnesium.

[0169] From the above, it was suggested that by having gallium, aluminum, or magnesium as the additive element X, cation mixing can be suppressed, degradation of the positive electrode active material 100 can be suppressed, and the capacity retention rate can be improved.

[0170] This embodiment can be used in combination with other embodiments.

[0171] (Embodiment 4) This embodiment describes examples of multiple shapes of secondary batteries having a positive electrode active material manufactured by the manufacturing method described in the previous embodiment.

[0172] [Coin-type rechargeable battery] An example of a coin-type rechargeable battery is described below. Figure 15(A) is an exploded perspective view of a coin-type (single-layer flat type) rechargeable battery, Figure 15(B) is an external view, and Figure 15(C) is a cross-sectional view thereof. Coin-type rechargeable batteries are mainly used in small electronic devices. In this specification, the term "coin-type battery" includes button-type batteries.

[0173] Figure 15(A) is a schematic diagram to show the overlapping of components (up / down relationship and positional relationship) for clarity. Therefore, Figure 15(A) and Figure 15(B) are not perfectly identical corresponding diagrams.

[0174] In Figure 15(A), the positive electrode 304, separator 310, negative electrode 307, spacer 322, and washer 312 are stacked. These are sealed with the negative electrode can 302 and the positive electrode can 301. Note that the gasket for sealing is not shown in Figure 15(A). The spacer 322 and washer 312 are used to protect the inside or to fix the position within the can when the positive electrode can 301 and the negative electrode can 302 are crimped together. The spacer 322 and washer 312 are made of stainless steel or insulating material.

[0175] The positive electrode 304 is a laminated structure in which a positive electrode active material layer 306 is formed on a positive electrode current collector 305.

[0176] To prevent a short circuit between the positive and negative electrodes, a separator 310 and a ring-shaped insulator 313 are arranged to cover the sides and top surfaces of the positive electrode 304, respectively. The separator 310 has a larger planar area than the positive electrode 304.

[0177] Figure 15(B) is a perspective view of the completed coin-type rechargeable battery.

[0178] The coin-type secondary battery 300 has a positive electrode casing 301, which also serves as the positive electrode terminal, and a negative electrode casing 302, which also serves as the negative electrode terminal, insulated and sealed by a gasket 303 made of polypropylene or the like. The positive electrode 304 is formed by a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with it. The negative electrode 307 is formed by a negative electrode current collector 308 and a negative electrode active material layer 309 provided in contact with it. Furthermore, the negative electrode 307 is not limited to a laminated structure, and lithium metal foil or a lithium-aluminum alloy foil may be used.

[0179] Furthermore, for the positive electrode 304 and negative electrode 307 used in the coin-type secondary battery 300, the active material layer only needs to be formed on one side.

[0180] The positive electrode can 301 and the negative electrode can 302 can be made of metals such as nickel, aluminum, or titanium, or alloys thereof, or alloys of these with other metals (e.g., stainless steel), which are corrosion-resistant to the electrolyte. Furthermore, it is preferable to coat them with nickel and aluminum, etc., to prevent corrosion caused by the electrolyte. The positive electrode can 301 is electrically connected to the positive electrode 304, and the negative electrode can 302 is electrically connected to the negative electrode 307.

[0181] The negative electrode 307, positive electrode 304, and separator 310 are immersed in an electrolyte solution, and as shown in Figure 15(C), the positive electrode can 301 is placed at the bottom, and the positive electrode 304, separator 310, negative electrode 307, and negative electrode can 302 are stacked in this order. The positive electrode can 301 and negative electrode can 302 are then crimped together via a gasket 303 to manufacture a coin-type secondary battery 300.

[0182] The above configuration makes it possible to create a coin-type secondary battery 300 with high capacity, high charge / discharge capacity, and excellent cycle characteristics. Furthermore, if the secondary battery has a solid electrolyte layer between the negative electrode 307 and the positive electrode 304, the separator 310 can be omitted.

[0183] [Cylindrical rechargeable battery] An example of a cylindrical secondary battery will be explained with reference to Figure 16(A). As shown in Figure 16(A), the cylindrical secondary battery 616 has a positive electrode cap (battery cover) 601 on the top surface and a battery casing (outer casing) 602 on the sides and bottom. The positive electrode cap 601 and the battery casing (outer casing) 602 are insulated from each other by a gasket (insulating packing) 610.

[0184] Figure 16(B) is a schematic diagram showing a cross-section of a cylindrical secondary battery. The cylindrical secondary battery shown in Figure 16(B) has a positive electrode cap (battery cover) 601 on the top surface and a battery casing (outer casing) 602 on the sides and bottom. The positive electrode cap 601 and the battery casing (outer casing) 602 are insulated from each other by a gasket (insulating packing) 610.

[0185] Inside the hollow cylindrical battery casing 602, a battery element is provided, in which a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 in between. Although not shown, the battery element is wound around a central axis. The battery casing 602 is closed at one end and open at the other. The battery casing 602 can be made of metals such as nickel, aluminum, and titanium, or alloys thereof, or alloys of these with other metals (e.g., stainless steel), which are corrosion-resistant to the electrolyte. Furthermore, it is preferable to coat the battery casing 602 with nickel and aluminum to prevent corrosion by the electrolyte. Inside the battery casing 602, the battery element, in which the positive electrode, negative electrode, and separator are wound, is sandwiched between a pair of opposing insulating plates 608 and 609. In addition, a non-aqueous electrolyte (not shown) is injected into the inside of the battery casing 602 in which the battery element is provided. The non-aqueous electrolyte can be the same as that used in coin-type secondary batteries.

[0186] Since the positive and negative electrodes used in cylindrical storage batteries are wound, it is preferable to form the active material on both sides of the current collector. Figures 16(A) to 16(D) illustrate a secondary battery 616 in which the height of the cylinder is greater than the diameter of the cylinder, but the battery is not limited to this configuration. A secondary battery in which the diameter of the cylinder is greater than the height of the cylinder is also possible. Such a configuration allows for, for example, miniaturization of the secondary battery.

[0187] By using the positive electrode active material 100 obtained in the above-described embodiment as the positive electrode 604, a cylindrical secondary battery 616 with high capacity, high charge / discharge capacity, and excellent cycle characteristics can be obtained.

[0188] A positive electrode terminal (positive electrode current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collector lead) 607 is connected to the negative electrode 606. Both the positive electrode terminal 603 and the negative electrode terminal 607 can be made of metal materials such as aluminum. The positive electrode terminal 603 is resistance-welded to the safety valve mechanism 613, and the negative electrode terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 613 is electrically connected to the positive electrode cap 601 via a PTC (Positive Temperature Coefficient) element 611. The safety valve mechanism 613 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the internal pressure of the battery rises above a predetermined threshold. The PTC element 611 is a thermal resistance element whose resistance increases when the temperature rises, and it prevents abnormal heat generation by limiting the amount of current through the increase in resistance. Barium titanate (BaTiO3) based semiconductor ceramics can be used for the PTC element.

[0189] Figure 16(C) shows an example of an energy storage system 615. The energy storage system 615 has multiple secondary batteries 616. The positive electrode of each secondary battery is in contact with a conductor 624 separated by an insulator 625 and is electrically connected. The conductor 624 is electrically connected to a control circuit 620 via wiring 623. The negative electrode of each secondary battery is also electrically connected to the control circuit 620 via wiring 626. The control circuit 620 can be a protective circuit to prevent overcharging or over-discharging, etc.

[0190] Figure 16(D) shows an example of an energy storage system 615. The energy storage system 615 has multiple secondary batteries 616, which are sandwiched between conductive plates 628 and 614. The multiple secondary batteries 616 are electrically connected to conductive plates 628 and 614 by wiring 627. The multiple secondary batteries 616 may be connected in parallel, in series, or connected in parallel and then in series. By configuring an energy storage system 615 with multiple secondary batteries 616, a large amount of power can be extracted.

[0191] Multiple secondary batteries 616 may be connected in parallel and then further connected in series.

[0192] A temperature control device may be provided between the multiple secondary batteries 616. When a secondary battery 616 overheats, it can be cooled by the temperature control device, and when a secondary battery 616 becomes too cold, it can be heated by the temperature control device. This makes the performance of the energy storage system 615 less susceptible to the influence of ambient temperature.

[0193] Furthermore, in Figure 16(D), the energy storage system 615 is electrically connected to the control circuit 620 via wiring 621 and wiring 622. Wiring 621 is electrically connected to the positive terminals of the multiple secondary batteries 616 via conductive plate 628, and wiring 622 is electrically connected to the negative terminals of the multiple secondary batteries 616 via conductive plate 614.

[0194] [Other structural examples of secondary batteries] Examples of secondary battery structures will be explained using Figures 17 and 18.

[0195] The secondary battery 913 shown in Figure 17(A) has a wound body 950 with terminals 951 and 952 inside a housing 930. The wound body 950 is immersed in an electrolyte inside the housing 930. Terminal 952 is in contact with the housing 930, while terminal 951 is not in contact with the housing 930 due to the use of an insulating material or the like. In Figure 17(A), the housing 930 is shown separated for convenience, but in reality, the wound body 950 is covered by the housing 930, and terminals 951 and 952 extend outside the housing 930. The housing 930 can be made of a metal material (e.g., aluminum) or a resin material.

[0196] Furthermore, as shown in Figure 17(B), the housing 930 shown in Figure 17(A) may be formed from multiple materials. For example, in the secondary battery 913 shown in Figure 17(B), housing 930a and housing 930b are bonded together, and the winding body 950 is provided in the area surrounded by housing 930a and housing 930b.

[0197] For the housing 930a, an insulating material such as organic resin can be used. In particular, by using a material such as organic resin on the surface where the antenna is formed, shielding of the electric field by the secondary battery 913 can be suppressed. If the shielding of the electric field by housing 930a is small, the antenna may be placed inside housing 930a. For housing 930b, for example, a metal material can be used.

[0198] Furthermore, the structure of the wound body 950 is shown in Figure 17(C). The wound body 950 has a negative electrode 931, a positive electrode 932, and a separator 933. The wound body 950 is a wound body in which the negative electrode 931 and the positive electrode 932 are stacked on top of each other with the separator 933 in between, and the stacked sheets are wound up. Note that multiple stacks of the negative electrode 931, positive electrode 932, and separator 933 may be stacked.

[0199] Alternatively, the secondary battery 913 may have a wound body 950a as shown in Figures 18(A) to 18(C). The wound body 950a shown in Figure 18(A) has 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 932a.

[0200] By using the positive electrode active material 100 obtained in the above-described embodiment as the positive electrode 932, a secondary battery 913 with high capacity, high charge / discharge capacity, and excellent cycle characteristics can be obtained.

[0201] The separator 933 has a wider width than the negative electrode active material layer 931a and the positive electrode active material layer 932a, and is wound so as to overlap with the negative electrode active material layer 931a and the positive electrode active material layer 932a. Furthermore, it is preferable from a safety standpoint that the negative electrode active material layer 931a is wider than the positive electrode active material layer 932a. A wound body 950a of this shape is also preferable due to its good safety and productivity.

[0202] As shown in Figure 18(B), the negative terminal 931 is electrically connected to terminal 951. Terminal 951 is electrically connected to terminal 911a. The positive terminal 932 is electrically connected to terminal 952. Terminal 952 is electrically connected to terminal 911b.

[0203] As shown in Figure 18(C), the coiled body 950a and electrolyte are covered by the housing 930, forming a secondary battery 913. 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 the inside of the housing 930 at a predetermined internal pressure to prevent the battery from rupturing.

[0204] As shown in Figure 18(B), the secondary battery 913 may have multiple windings 950a. By using multiple windings 950a, a secondary battery 913 with a larger charge and discharge capacity can be made. Other elements of the secondary battery 913 shown in Figures 18(A) and (B) can be considered in reference to the description of the secondary battery 913 shown in Figures 17(A) to (C).

[0205] <Laminated rechargeable battery> Next, an example of the external view of a laminate-type secondary battery is shown in Figures 19(A) and 19(B). Figures 19(A) and 19(B) show a positive electrode 503, a negative electrode 506, a separator 507, an outer casing 509, a positive electrode lead electrode 510, and a negative electrode lead electrode 511.

[0206] Figure 20(A) shows the external view of the positive electrode 503 and the negative electrode 506. The positive electrode 503 has a positive electrode current collector 501, and the positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501. The positive electrode 503 also has a region where the positive electrode current collector 501 is partially exposed (hereinafter referred to as the tab region). The negative electrode 506 has a negative electrode current collector 504, and the negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. The negative electrode 506 also has a region where the negative electrode current collector 504 is partially exposed, i.e., the tab region. The area and shape of the tab regions of the positive and negative electrodes are not limited to the example shown in Figure 20(A).

[0207] <Method for manufacturing laminated rechargeable batteries> Here, an example of a method for manufacturing a laminate-type secondary battery, whose external view is shown in Figure 19(A), will be explained using Figures 20(B) and 20(C).

[0208] First, the negative electrode 506, separator 507, and positive electrode 503 are stacked. Figure 20(B) shows the stacked negative electrode 506, separator 507, and positive electrode 503. Here, an example using 5 sets of negative electrodes and 4 sets of positive electrodes is shown. This can also be called a laminate consisting of negative electrodes, separators, and positive electrodes. Next, the tab regions of the positive electrode 503 are joined together, and the positive electrode lead electrode 510 is joined to the tab region of the outermost positive electrode. For joining, ultrasonic welding, for example, can be used. Similarly, the tab regions of the negative electrode 506 are joined together, and the negative electrode lead electrode 511 is joined to the tab region of the outermost negative electrode.

[0209] Next, the negative electrode 506, separator 507, and positive electrode 503 are placed on the outer casing 509.

[0210] Next, as shown in Figure 20(C), the outer casing 509 is bent at the portion indicated by the dashed line. Then, the outer periphery of the outer casing 509 is joined. For joining, for example, heat sealing may be used. At this time, a region that is not joined (hereinafter referred to as the inlet) is provided on a part (or one side) of the outer casing 509 so that the electrolyte 508 can be added later.

[0211] Next, the electrolyte 508 (not shown) is introduced into the inside of the outer casing 509 through an inlet provided in the outer casing 509. It is preferable to introduce the electrolyte 508 under a reduced pressure atmosphere or an inert atmosphere. Finally, the inlet is sealed. In this way, a laminate-type secondary battery 500 can be manufactured.

[0212] By using the positive electrode active material 100 obtained in the above-described embodiment as the positive electrode 503, a secondary battery 500 can be made that has high capacity, high charge / discharge capacity, and excellent cycle characteristics.

[0213] [Example of a battery pack] An example of a secondary battery pack according to one embodiment of the present invention, which is capable of wireless charging using an antenna, will be explained with reference to Figures 21(A) to 21(C).

[0214] Figure 21(A) shows the external 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 21(B) is a diagram illustrating the configuration of the secondary battery pack 531. The secondary battery pack 531 has a circuit board 540 and a secondary battery 513. A label 529 is attached to the secondary battery 513. The circuit board 540 is fixed by a seal 515. The secondary battery pack 531 also has an antenna 517.

[0215] The internal structure of the secondary battery 513 may have a wound structure or a laminated structure.

[0216] In the secondary battery pack 531, for example, as shown in Figure 21(B), a control circuit 590 is located on the circuit board 540. The circuit board 540 is electrically connected to terminal 514. The circuit board 540 is also electrically connected to the antenna 517, one of the positive and negative leads 551 of the secondary battery 513, and the other of the positive and negative leads 552.

[0217] Alternatively, as shown in Figure 21(C), the system may have a circuit system 590a provided on the circuit board 540 and a circuit system 590b electrically connected to the circuit board 540 via terminals 514.

[0218] The antenna 517 is not limited to a coil shape; for example, it may be linear or plate-shaped. Alternatively, antennas such as planar antennas, aperture antennas, traveling wave antennas, EH antennas, magnetic field antennas, and dielectric antennas may be used. Alternatively, the antenna 517 may be a flat conductor. This flat conductor can function as one of the conductors for electric field coupling. In other words, the antenna 517 may function as one of the two conductors of the capacitor. This allows for power exchange not only through electromagnetic and magnetic fields, but also through electric fields.

[0219] The secondary battery pack 531 has a layer 519 between the antenna 517 and the secondary battery 513. The layer 519 has the function of shielding, for example, the electromagnetic field from the secondary battery 513. For the layer 519, a magnetic material can be used, for example.

[0220] [Positive electrode] The positive electrode comprises a positive electrode active material layer and a positive electrode current collector. The positive electrode active material layer contains a positive electrode active material and may also contain a conductive material and a binder. The positive electrode active material used is a positive electrode active material manufactured using the manufacturing method described in the previous embodiment.

[0221] Alternatively, the positive electrode active material described in the previous embodiment may be used in combination with other positive electrode active materials.

[0222] Examples of other cathode 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, MnO2 can be mentioned.

[0223] In addition, as another cathode active material, a lithium-containing material having a spinel-type crystal structure containing manganese such as LiMn2O4 is preferably mixed with lithium nickelate (LiNiO2 or LiNi 1-x M x O2 (0 < x < 1) (M = Co, Al, etc.). By adopting such a configuration, the characteristics of the secondary battery can be improved.

[0224] In addition, as another cathode active material, a lithium manganese composite oxide represented by the composition formula Li a Mn b M c O d can be used. Here, the element M is preferably a metal element selected from elements other than lithium and manganese, or silicon or phosphorus, and more preferably nickel. Further, when measuring the entire particles of the lithium manganese composite oxide, it is preferable to satisfy 0 < a / (b + c) < 2, c > 0, and 0.26 ≤ (b + c) / d < 0.5 during discharge. The composition of metals, silicon, phosphorus, etc. of the entire particles of the lithium manganese composite oxide can be measured using, for example, ICP-MS (inductively coupled plasma mass spectrometer). Also, the oxygen composition of the entire particles of the lithium manganese composite oxide can be measured using, for example, EDX (energy dispersive X-ray analysis method). Further, it can be obtained by using valence evaluation of melting gas analysis and XAFS (X-ray absorption fine structure) analysis in combination with ICP-MS analysis. The lithium manganese composite oxide refers to an oxide containing at least lithium and manganese, and may contain at least one element selected from the group consisting of chromium, cobalt, aluminum, nickel, iron, magnesium, molybdenum, zinc, indium, gallium, copper, titanium, niobium, silicon, and phosphorus.

[0225] <Conductive material> The conductive material, also called a conductive aid or a conductivity-imparting agent, is a carbon material. By attaching a conductive aid between a plurality of active materials, the plurality of active materials are electrically connected to each other, enhancing conductivity. Note that the term "attachment" does not only refer to the physical adhesion of the active material and the conductive aid. It includes cases where a covalent bond occurs, cases where bonding occurs by van der Waals forces, cases where a part of the surface of the active material is covered by the conductive aid, cases where the conductive aid fits into the surface irregularities of the active material, and cases where they are electrically connected even if they do not touch each other.

[0226] Typical carbon materials used as the conductive material include carbon black (such as furnace black, acetylene black, graphite, etc.).

[0227] It is more preferable to use graphene or a graphene compound as the conductive material.

[0228] In this specification, etc., the graphene compound includes multi-layer graphene, multi-graphene, graphene oxide, multi-layer graphene oxide, multi-oxidized graphene, reduced graphene oxide, reduced multi-layer graphene oxide, reduced multi-oxidized graphene, graphene quantum dots, etc. The graphene compound refers to a material that has carbon, has a flat or sheet-like shape, and has a two-dimensional structure formed by carbon six-member rings. The two-dimensional structure formed by the carbon six-member rings may also be referred to as a carbon sheet. The graphene compound may have a functional group. Also, the graphene compound preferably has a bent shape. Also, the graphene compound may be rounded like a carbon nanofiber.

[0229] In this specification, etc., graphene oxide refers to a material that has carbon and oxygen, has a sheet-like shape, and has a functional group, particularly an epoxy group, a carboxy group, or a hydroxy group.

[0230] In this specification, reduced graphene oxide refers to a material having carbon and oxygen, having a sheet-like shape, and possessing a two-dimensional structure formed by a six-membered carbon ring. It may also be called a carbon sheet. Reduced graphene oxide can function as a single sheet, but multiple sheets may be laminated together. It is preferable that reduced graphene oxide has a portion in which the carbon concentration is greater than 80 atomic percent and the oxygen concentration is between 2 atomic percent and 15 atomic percent. By having such carbon and oxygen concentrations, it can function as a highly conductive material even in small quantities. Furthermore, it is preferable that reduced graphene oxide has a G / D intensity ratio of 1 or more in the Raman spectrum. Reduced graphene oxide with such an intensity ratio can function as a highly conductive material even in small quantities.

[0231] Graphene and graphene compounds may possess excellent electrical properties, such as high conductivity, and excellent physical properties, such as high flexibility and high mechanical strength. Furthermore, graphene and graphene compounds may have a sheet-like shape. Graphene and graphene compounds may have curved surfaces, enabling surface contact with low contact resistance. They may also exhibit very high conductivity even when thin, allowing for the efficient formation of conductive paths within the active material layer with a small amount. Therefore, using graphene or graphene compounds as a conductive material can increase the contact area between the active material and the conductive material. It is preferable that the graphene or graphene compound covers 80% or more of the active material's surface area. It is also preferable that the graphene or graphene compound adheres to at least a portion of the active material particles. Furthermore, it is preferable that the graphene or graphene compound overlaps at least a portion of the active material particles. It is also preferable that the shape of the graphene or graphene compound matches at least a portion of the shape of the active material particles. The shape of the active material particles refers, for example, to the irregularities of a single active material particle or the irregularities formed by multiple active material particles. Furthermore, it is preferable that graphene or a graphene compound surrounds at least a portion of the active material particles. The graphene or graphene compound may also have pores.

[0232] When using active material particles with a small particle size, such as 1 μm or less, the specific surface area of ​​the active material particles is large, and more conductive paths are required to connect the active material particles. In such cases, it is preferable to use graphene or graphene compounds that can efficiently form conductive paths even in small amounts.

[0233] Due to the properties described above, graphene compounds are particularly effective as conductive materials in secondary batteries that require rapid charging and rapid discharging. For example, secondary batteries for two-wheeled or four-wheeled vehicles, and secondary batteries for drones, may require rapid charging and rapid discharging characteristics. Mobile electronic devices may also require rapid charging characteristics. Rapid charging and rapid discharging can also be described as high-rate charging and high-rate discharging. For example, this refers to charging and discharging at 1C, 2C, or 5C or higher.

[0234] Alternatively, graphene or a graphene compound may be mixed with materials used to form graphene or a graphene compound and used in the active material layer 200. For example, particles used as a catalyst when forming graphene or a graphene compound may be mixed together with graphene or a graphene compound. Examples of catalysts used when forming graphene or a graphene compound include silicon dioxide (SiO2, SiO2). x Examples of particles include those having (x<2), aluminum oxide, iron, nickel, ruthenium, iridium, platinum, copper, germanium, etc. The median diameter (D50) of the particles is preferably 1 μm or less, and more preferably 100 nm or less.

[0235] <Binder> As a binder, it is preferable to use rubber materials such as styrene-butadiene rubber (SBR), styrene-isoprene-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, or ethylene-propylene-diene copolymer. Fluororubber can also be used as a binder.

[0236] Furthermore, it is preferable to use a water-soluble polymer as the binder. Examples of water-soluble polymers include polysaccharides. Examples of polysaccharides include cellulose derivatives such as carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxypropylcellulose, diacetylcellulose, and regenerated cellulose, as well as starch. It is even more preferable to use these water-soluble polymers in combination with the aforementioned rubber material.

[0237] Alternatively, it is preferable to use materials such as polystyrene, methyl polyacrylate, 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, polyvinyl acetate, or nitrocellulose as the binder.

[0238] You may use a combination of several of the binders mentioned above.

[0239] For example, a material with particularly excellent viscosity-modifying properties may be used in combination with other materials. For instance, rubber materials have excellent adhesive and elastic properties, but their viscosity can be difficult to adjust when mixed with a solvent. In such cases, it is preferable to mix them with a material with particularly excellent viscosity-modifying properties. As a material with particularly excellent viscosity-modifying properties, for example, a water-soluble polymer can be used. As a water-soluble polymer with particularly excellent viscosity-modifying properties, the aforementioned polysaccharides, such as carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxypropylcellulose, and diacetylcellulose, as well as cellulose derivatives such as regenerated cellulose and starch, can be used.

[0240] Furthermore, cellulose derivatives such as carboxymethylcellulose can be made more effective as viscosity modifiers by increasing their solubility, for example, by using salts such as sodium salts and ammonium salts of carboxymethylcellulose. Increased solubility also improves the dispersibility of the active material and other components when preparing electrode slurries. In this specification, cellulose and cellulose derivatives used as electrode binders include their salts.

[0241] Water-soluble polymers stabilize viscosity by dissolving in water and can stably disperse active materials and other materials used as binders, such as styrene-butadiene rubber, in aqueous solutions. Furthermore, because they possess functional groups, they are expected to be easily and stably adsorbed onto the surface of the active material. Additionally, cellulose derivatives such as carboxymethylcellulose often contain functional groups such as hydroxyl and carboxyl groups, and because of these functional groups, the polymers interact with each other, allowing them to broadly cover the surface of the active material.

[0242] When a binder covers or is in contact with the surface of the active material, it is expected to act as a passivation film, suppressing the decomposition of the electrolyte. Here, a passivation film is a film that does not conduct electricity, or has extremely low electrical conductivity. For example, when a passivation film is formed on the surface of the active material, the decomposition of the electrolyte can be suppressed at the battery reaction potential. Furthermore, it is even more desirable for the passivation film to suppress electrical conductivity while still allowing lithium ions to conduct.

[0243] <Positive electrode current collector> As the positive electrode current collector, highly conductive materials such as stainless steel, gold, platinum, aluminum, titanium, and alloys thereof can be used. Furthermore, it is preferable that the material used for the positive electrode current collector does not dissolve at the positive electrode potential. Aluminum alloys with added elements that improve heat resistance, such as silicon, titanium, neodymium, scandium, and molybdenum, can also be used. Alternatively, it may be formed from a metallic element that reacts with silicon to form a silicide. Examples of metallic elements that react with silicon to form a silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, and nickel. The positive electrode current collector can be in various shapes, such as foil, plate, sheet, mesh, perforated metal, or expanded metal. The positive electrode current collector should preferably have a thickness of 5 μm to 30 μm.

[0244] [Negative electrode] The negative electrode comprises a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer may also contain a conductive material and a binder.

[0245] As the negative electrode active material, for example, alloy-based materials, carbon-based materials, and mixtures thereof can be used.

[0246] As the negative electrode active material, an element capable of performing a charge-discharge reaction by an alloying / de-alloying reaction with lithium can be used. For example, a material containing at least one of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. can be used. Such elements have a larger capacity compared to carbon, and particularly silicon has a high theoretical capacity of 4200 mAh / g. Therefore, it is preferable to use silicon as the negative electrode active material. Further, compounds containing these elements may also be used. For example, there are SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, SbSn, etc. Here, an element capable of performing a charge-discharge reaction by an alloying / de-alloying reaction with lithium, and a compound containing the element, etc. may be referred to as an alloy-based material.

[0247] In this specification, etc., SiO refers to, for example, silicon monoxide. Alternatively, SiO can also be expressed as SiO x Here, x preferably has a value of 1 or near 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] As the carbon-based material, graphite, graphitizable carbon (soft carbon), 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 of artificial graphite include mesocarbon microbeads (MCMB), coke-based artificial graphite, pitch-based artificial graphite, etc. Here, spherical graphite having a spherical shape can be used as the artificial graphite. For example, MCMB may have a spherical shape, which is preferable. Also, MCMB can relatively easily reduce its surface area, which may be preferable. Examples of natural graphite include flaky graphite, spheroidized natural graphite, etc.

[0250] When lithium ions are inserted into graphite (during the formation of lithium-graphite intercalation compounds), graphite exhibits a potential as low as that of lithium metal (0.05V to 0.3V vs. Li / Li). + This allows lithium-ion secondary batteries using graphite to exhibit a high operating voltage. Furthermore, graphite is preferable because it has advantages such as a relatively high capacity per unit volume, relatively small volume expansion, low cost, and higher safety compared to lithium metal.

[0251] Furthermore, titanium dioxide (TiO2) and lithium titanium oxide (Li4Ti5O2) are used as negative electrode active materials. 12 ), lithium-graphite intercalation compound (Li x Oxides such as C6, niobium pentoxide (Nb2O5), tungsten oxide (WO2), and molybdenum oxide (MoO2) can be used.

[0252] Furthermore, as the negative electrode active material, a Li3N type structure is used, which is a lithium and transition metal binitride. 3-x M x N (M = Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 The N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm²). 3 ) indicates a preference.

[0253] Using a lithium-transition metal complex nitride is preferable because it contains lithium ions in the negative electrode active material, allowing it to be combined with lithium-ion-free materials such as V2O5 and Cr3O8 as the positive electrode active material. Even when using a lithium-ion-containing material as the positive electrode active material, the lithium-transition metal complex nitride can be used as the negative electrode active material by pre-desorbing the lithium ions contained in the positive electrode active material.

[0254] Furthermore, materials that undergo a conversion reaction can also be used as the negative electrode active material. For example, transition metal oxides that do not form alloys with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO), may be used as the negative electrode active material. Other materials that undergo a conversion reaction include oxides such as Fe2O3, CuO, Cu2O, RuO2, Cr2O3, and CoS 0.89 This can also occur with sulfides such as NiS and CuS, nitrides such as Zn3N2, Cu3N, and Ge3N4, phosphides such as NiP2, FeP2, and CoP3, and fluorides such as FeF3 and BiF3.

[0255] The conductive material and binder that the negative electrode active material layer can have can be the same materials as those used for the positive electrode active material layer.

[0256] Furthermore, in addition to the same materials as the positive electrode current collector, copper and other materials can also be used as the negative electrode current collector. It is preferable to use a material for the negative electrode current collector that does not alloy with carrier ions such as lithium.

[0257] [Electrolyte] One form of electrolyte can be used: an electrolyte solution comprising a solvent and an electrolyte dissolved in the solvent. As the solvent for the electrolyte, an aprotic organic solvent is preferred. Examples include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolactone, 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 sulfoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolane, sultone, and one of these, or two or more of these, can be used in any combination and ratio.

[0258] Furthermore, by using one or more flame-retardant and non-volatile ionic liquids (room-temperature molten salts) as the solvent for the electrolyte, it is possible to prevent the energy storage device from rupturing or catching fire even if the internal temperature rises due to an internal short circuit or overcharging. Ionic liquids consist of cations and anions, and include organic cations and anions. Examples of organic cations used in the electrolyte include aliphatic onium cations such as quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, as well as aromatic cations such as imidazolium cations and pyridinium cations. Examples of anions used in the electrolyte include monovalent amide anions, monovalent methide anions, fluorosulfonic acid anions, perfluoroalkyl sulfonate anions, tetrafluoroborate anions, perfluoroalkyl borate anions, hexafluorophosphate anions, or perfluoroalkyl phosphate anions.

[0259] Furthermore, examples of electrolytes to be dissolved in the above solvent include LiPF6, LiClO4, LiAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4, and Li2B. 10 Cl 10 Li2B 12 Cl 12 Lithium salts such as LiCF3SO3, LiC4F9SO3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2)2, LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, lithium bis(oxalate) borate (Li(C2O4)2, LiBOB) can be used individually or in any combination and ratio of two or more of these salts.

[0260] It is preferable to use a highly purified electrolyte in which particulate matter or elements other than the constituent elements of the electrolyte (hereinafter simply referred to as "impurities") are present in small amounts. Specifically, it is preferable that the weight ratio of impurities to the electrolyte be 1% or less, preferably 0.1% or less, and more preferably 0.01% or less.

[0261] Furthermore, additives such as vinylene carbonate, propanesultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), lithium bis(oxalate)borate (LiBOB), and dinitrile compounds such as succinonitrile and adiponitrile may be added to the electrolyte. The concentration of the additive should be, for example, 0.1 wt% to 5 wt% relative to the solvent in which the electrolyte is dissolved.

[0262] Alternatively, a polymer gel electrolyte, obtained by swelling a polymer with an electrolyte solution, may be used.

[0263] Using polymer gel electrolytes enhances safety against leakage and other issues. Furthermore, it enables the secondary battery to be made thinner and lighter.

[0264] As the polymer to be gelled, silicone gels, acrylic gels, acrylonitrile gels, polyethylene oxide gels, polypropylene oxide gels, fluorine-based polymer gels, etc., can be used. For example, polymers having a polyalkylene oxide structure such as polyethylene oxide (PEO), PVDF, polyacrylonitrile, and copolymers containing them can be used. For example, PVDF-HFP, a copolymer of PVDF and hexafluoropropylene (HFP), can be used. Furthermore, the formed polymer may have a porous structure.

[0265] [Separator] As separators, for example, those made from cellulose-containing fibers such as paper, nonwoven fabrics, glass fibers, ceramics, or synthetic fibers using nylon (polyamide), vinylon (polyvinyl alcohol-based fiber), polyester, acrylic, polyolefin, or polyurethane can be used.

[0266] The separator may have a multilayer structure. For example, an organic material film such as polypropylene or polyethylene can be coated with a ceramic material, a fluorine material, a polyamide material, or a mixture thereof. As ceramic materials, for example, aluminum oxide particles or silicon oxide particles can be used. It is also possible to use a glass-like material as a ceramic material, but unlike the glass used in electrodes, it is preferable that it has low electronic conductivity. As fluorine materials, for example, PVDF or polytetrafluoroethylene can be used. As polyamide materials, for example, nylon or aramid (meta-aramid, para-aramid) can be used.

[0267] Coating with ceramic materials improves oxidation resistance, suppressing separator degradation during high-voltage charging and improving the reliability of secondary batteries. Coating with fluorine-based materials facilitates better adhesion between the separator and electrodes, improving output characteristics. Coating with polyamide materials, particularly aramid, improves heat resistance, thereby enhancing the safety of secondary batteries.

[0268] For example, a polypropylene film may be coated on both sides with a mixture of aluminum oxide and aramid. Alternatively, the side of the polypropylene film in contact with the positive electrode may be coated with a mixture of aluminum oxide and aramid, and the side in contact with the negative electrode may be coated with a fluorine-based material.

[0269] The contents of this embodiment can be freely combined with the contents of other embodiments.

[0270] (Embodiment 5) This embodiment shows an example of fabricating an all-solid-state battery using the positive electrode active material 100 obtained in the above-described embodiment.

[0271] As shown in Figure 22(A), a secondary battery 400 according to one embodiment of the present invention has a positive electrode 410, a solid electrolyte layer 420, and a negative electrode 430.

[0272] The positive electrode 410 has a positive electrode current collector 413 and a positive electrode active material layer 414. The positive electrode active material layer 414 has a positive electrode active material 411 and a solid electrolyte 421. The positive electrode active material 411 is the positive electrode active material 100 obtained in the above embodiment. The positive electrode active material layer 414 may also have a conductive material and a binder.

[0273] The solid electrolyte layer 420 has a solid electrolyte 421. The solid electrolyte layer 420 is located between the positive electrode 410 and the negative electrode 430 and is a region that does not contain either the positive electrode active material 411 or the negative electrode active material 431.

[0274] The negative electrode 430 has 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 active material layer 434 may also have a conductive material and a binder. When metallic lithium is used as the negative electrode active material 431, it is not necessary to form it into particles, so the negative electrode 430 can be made without the solid electrolyte 421, as shown in Figure 22(B). Using metallic lithium in the negative electrode 430 is preferable because it can improve the energy density of the secondary battery 400.

[0275] As the solid electrolyte 421 in the solid electrolyte layer 420, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halogen-based solid electrolyte, etc., can be used.

[0276] Sulfide-based solid electrolytes include thiolysicone-based (Li 10 GeP2S 12 Li 3.25 Ge 0.25 P 0.75 S4, etc.), sulfide glass (70Li2S·30P2S5, 30Li2S·26B2S3·44LiI, 63Li2S·36SiS2·1Li3PO4, 57Li2S·38SiS2·5Li4SiO4, 50Li2S·50GeS2, etc.), sulfide crystallized glass (Li7P3S 11 Li 3.25 P 0.95It contains S4, etc. Sulfide-based solid electrolytes have advantages such as the availability of materials with high conductivity, the ability to be synthesized at low temperatures, and their relatively soft nature which helps maintain conductive paths even after charging and discharging.

[0277] Oxide-based solid electrolytes include materials having a perovskite-type crystal structure (La 2 / 3-x Li 3x Materials having a NASICON-type crystal structure (Li 1-Y Al Y Ti 2-Y (PO4)3 etc.) Materials having a garnet-type crystal structure (Li7La3Zr2O 12 Materials having a LISICON-type crystal structure (Li 14 ZnGe4O 16 etc.), LLZO(Li7La3Zr2O 12 ), oxide glass (Li3PO4-Li4SiO4, 50Li4SiO4·50Li3BO3, 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. are included. Oxide-based solid electrolytes have the advantage of being stable in the atmosphere.

[0278] Halide-based solid electrolytes include LiAlCl4, Li3InBr6, LiF, LiCl, LiBr, and LiI. Furthermore, composite materials in which these halide-based solid electrolytes are packed into the pores of porous aluminum oxide or porous silica can also be used as solid electrolytes.

[0279] Alternatively, different solid electrolytes may be mixed and used.

[0280] In particular, Li has a NASICON-type crystal structure. 1+x Al x Ti 2-x(PO4)3(0 < x < 1) (hereinafter referred to as LATP) contains elements such as aluminum and titanium, which may be included in the positive electrode active material used in the secondary battery 400 of one aspect of the present invention. Therefore, a synergistic effect can be expected for improving the cycle characteristics, which is preferable. Also, an improvement in productivity due to the reduction of processes can be expected. In this specification and the like, the NASICON-type crystal structure refers to a compound represented by M2(XO4)3 (M: transition metal, X: S, P, As, Mo, W, etc.), which has a structure in which MO6 octahedra and XO4 tetrahedra share vertices and are three-dimensionally arranged.

[0281] <Shape of the exterior body and the secondary battery> For the exterior body of the secondary battery 400 of one aspect of the present invention, various materials and shapes can be used, but it is preferable to have a function of pressing the positive electrode, the solid electrolyte layer, and the negative electrode.

[0282] For example, FIG. 23 shows an example of a cell for evaluating the materials of an all-solid-state battery.

[0283] FIG. 23(A) is a schematic cross-sectional view of the evaluation cell. The evaluation cell has a lower member 761, an upper member 762, and a fixing screw or wing nut 764 for fixing them. By rotating the pressing screw 763, the electrode plate 753 is pressed to fix the evaluation material. An insulator 766 is provided between the lower member 761 and the upper member 762 made of a stainless steel material. Also, an O-ring 765 for sealing is provided between the upper member 762 and the pressing screw 763.

[0284] The evaluation material is placed on the electrode plate 751, surrounded by an insulating tube 752 around it, and is in a state of being pressed by the electrode plate 753 from above. A perspective view of the periphery of this evaluation material is shown in FIG. 23(B).

[0285] 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, and a cross-sectional view is shown in FIG. 23(C). In FIGS. 23(A) to (C), the same reference numerals are used for the same parts.

[0286] The electrode plate 751 and lower member 761, which are electrically connected to the positive electrode 750a, can be considered to correspond to the positive electrode terminal. The electrode plate 753 and upper member 762, which are electrically connected to the negative electrode 750c, can be considered to correspond to the negative electrode terminal. Electrical resistance and other parameters can be measured while applying pressure to the evaluation material via the electrode plates 751 and 753.

[0287] Furthermore, it is preferable to use a package with excellent airtightness for the outer casing of a secondary battery according to one embodiment of the present invention. For example, a ceramic package or a resin package can be used. Also, when sealing the outer casing, it is preferable to block out the outside air and perform the sealing in a sealed atmosphere, for example, inside a glove box.

[0288] Figure 24(A) shows a perspective view of a secondary battery according to one embodiment of the present invention, having a different exterior and shape from that shown in Figure 23. The secondary battery in Figure 24(A) has external electrodes 771 and 772 and is sealed with an exterior having a plurality of package members.

[0289] Figure 24(B) shows an example of a cross-section cut along the dashed line in Figure 24(A). The laminate having a positive electrode 750a, a solid electrolyte layer 750b, and a negative electrode 750c is enclosed and sealed by a package member 770a having an electrode layer 773a on a flat plate, a frame-shaped package member 770b, and a package member 770c having an electrode layer 773b on a flat plate. Insulating materials, such as resin materials and ceramics, can be used for the package members 770a, 770b, and 770c.

[0290] The external electrode 771 is electrically connected to the positive electrode 750a via the electrode layer 773a and functions as a positive electrode terminal. The external electrode 772 is electrically connected to the negative electrode 750c via the electrode layer 773b and functions as a negative electrode terminal.

[0291] By using the positive electrode active material 100 obtained in the above-described embodiment, an all-solid-state secondary battery with high energy density and good output characteristics can be realized.

[0292] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0293] (Embodiment 6) This embodiment is an example of a secondary battery different from the cylindrical secondary battery shown in Figure 16(D). Figure 25(C) shows an example of applying the secondary battery to an electric vehicle (EV).

[0294] Electric vehicles are equipped with a first battery 1301a and 1301b as the main secondary battery for propulsion, and a second battery 1311 that supplies power to the inverter 1312 that starts the motor 1304. The second battery 1311 is also called the cranking battery (or starter battery). The second battery 1311 only needs to be able to output power, and does not require a large capacity, so its capacity is smaller than that of the first batteries 1301a and 1301b.

[0295] The internal structure of the first battery 1301a may be a wound type as shown in Figure 17(A) or Figure 18(C), or a stacked type as shown in Figure 19(A) or Figure 19(B). Furthermore, the first battery 1301a may use the all-solid-state battery of Embodiment 4. Using the all-solid-state battery of Embodiment 4 for the first battery 1301a allows for higher capacity, improved safety, and miniaturization and weight reduction.

[0296] In this embodiment, an example is shown in which two first batteries 1301a and 1301b are connected in parallel, but three or more may be connected in parallel. Also, if the first battery 1301a can store sufficient power, the first battery 1301b may not be necessary. By configuring a battery pack with multiple secondary batteries, a large amount of power can be extracted. Multiple secondary batteries may be connected in parallel, in series, or connected in parallel and then in series. Multiple secondary batteries are also called a battery pack.

[0297] Furthermore, in the vehicle-mounted secondary battery, a service plug or circuit breaker that can cut off high voltage without using tools is provided in order to interrupt the power from multiple secondary batteries, and this is installed in the first battery 1301a.

[0298] Furthermore, the power from the first batteries 1301a and 1301b is mainly used to rotate the motor 1304, but also supplies power to 42V onboard components (electric power steering 1307, heater 1308, defogger 1309, etc.) via the DC-DC circuit 1306. If a rear motor 1317 is located on the rear wheels, the first battery 1301a is also used to rotate the rear motor 1317.

[0299] Furthermore, the second battery 1311 supplies power to 14V automotive components (audio 1313, power windows 1314, lights 1315, etc.) via the DC-DC circuit 1310.

[0300] Furthermore, the first battery 1301a will be explained using Figure 25(A).

[0301] Figure 25(A) shows an example where nine rectangular secondary batteries 1300 are arranged in a single battery pack 1415. In this example, nine rectangular secondary batteries 1300 are connected in series, with one electrode fixed by an insulating fixing part 1413 and the other electrode fixed by an insulating fixing part 1414. While this embodiment shows an example of fixing with fixing parts 1413 and 1414, the batteries may also be housed in a battery housing box (also called a casing). Since vehicles are expected to be subjected to vibrations or shaking from external sources (such as the road surface), it is preferable to fix multiple secondary batteries using fixing parts 1413, 1414 and a battery housing box. Furthermore, one electrode is electrically connected to the control circuit unit 1320 by wiring 1421, and the other electrode is electrically connected to the control circuit unit 1320 by wiring 1422.

[0302] Furthermore, the control circuit unit 1320 may also use a memory circuit that includes a transistor made of an oxide semiconductor. A charging control circuit or battery control system having a memory circuit that includes a transistor made of an oxide semiconductor may be referred to as a BTOS (Battery operating system or Battery oxide semiconductor).

[0303] It is preferable to use a metal oxide that functions as an oxide semiconductor. For example, as the oxide, a metal oxide such as In-M-Zn oxide (where element M is one or more selected from aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium) is preferable. In particular, the In-M-Zn oxide that can be applied as the oxide is preferably CAAC-OS (C-Axis Aligned Crystal Oxide Semiconductor) or CAC-OS (Cloud-Aligned Composite Oxide Semiconductor). Alternatively, In-Ga oxide or In-Zn oxide may be used as the oxide. CAAC-OS is an oxide semiconductor having multiple crystalline regions, the c-axis of which is oriented in a specific direction. The specific direction is the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. Furthermore, a crystalline region is a region in which the atomic arrangement has periodicity. If the atomic arrangement is considered as a lattice arrangement, then a crystalline region is also a region in which the lattice arrangement is aligned. In addition, CAAC-OS has regions in which multiple crystalline regions are connected in the ab-plane direction, and these regions may have distortion. Distortion refers to a point in a region in which multiple crystalline regions are connected where the orientation of the lattice arrangement changes between a region in which the lattice arrangement is aligned and another region in which the lattice arrangement is aligned. In other words, CAAC-OS is an oxide semiconductor that is c-axis oriented and does not have a clear orientation in the ab-plane direction. Furthermore, CAC-OS is a material composition in which, for example, elements constituting a metal oxide are unevenly distributed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size. In the following, in a metal oxide, a state in which one or more metal elements are unevenly distributed, and regions containing these metal elements are mixed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size, is also referred to as a mosaic or patchy state.

[0304] Furthermore, CAC-OS is a composite metal oxide having a mosaic-like structure formed by the separation of the material into a first region and a second region, with the first region distributed within the film (hereinafter also referred to as a cloud-like structure). In other words, CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0305] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in In-Ga-Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS of In-Ga-Zn oxide, the first region is the region where [In] is greater than the [In] in the composition of the CAC-OS film. The second region is the region where [Ga] is greater than the [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is the region where [In] is greater than the [In] in the second region, and [Ga] is smaller than the [Ga] in the second region. The second region is the region where [Ga] is greater than the [Ga] in the first region, and [In] is smaller than the [In] in the first region.

[0306] Specifically, the first region described above is a region whose main components are indium oxide, indium zinc oxide, etc. The second region described above is a region whose main components are gallium oxide, gallium zinc oxide, etc. In other words, the first region can be rephrased as a region whose main component is In. Similarly, the second region can be rephrased as a region whose main component is Ga.

[0307] Furthermore, a clear boundary may not be observed between the first region and the second region described above.

[0308] For example, in the case of CAC-OS in In-Ga-Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) confirms that it has a structure in which regions mainly composed of In (first region) and regions mainly composed of Ga (second region) are unevenly distributed and mixed.

[0309] When CAC-OS is used in a transistor, the conductivity due to the first region and the insulation due to the second region work complementaryly to give CAC-OS a switching function (on / off function). In other words, CAC-OS has conductive function in part of the material, insulating function in part of the material, and semiconductor function as a whole. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I) can be achieved. on This enables high field-effect mobility (μ) and good switching operation.

[0310] Oxide semiconductors can take on diverse structures, each possessing different properties. One embodiment of the present invention may include two or more of the following: amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, CAC-OS, nc-OS, and CAAC-OS.

[0311] Furthermore, since it can be used in high-temperature environments, it is preferable that the control circuit section 1320 uses a transistor made of an oxide semiconductor. To simplify the process, the control circuit section 1320 may be formed using a unipolar transistor. Transistors using an oxide semiconductor in the semiconductor layer have an operating ambient temperature range of -40°C to 150°C, which is wider than that of single-crystal Si, and the change in characteristics is smaller than that of a single-crystal Si transistor even when the secondary battery is heated. The off-current of a transistor using an oxide semiconductor is below the lower limit of measurement even at 150°C, but the off-current characteristics of a single-crystal Si transistor are highly temperature-dependent. For example, at 150°C, the off-current of a single-crystal Si transistor increases, and the current on / off ratio does not become sufficiently large. The control circuit section 1320 can improve safety. In addition, a synergistic effect on safety can be obtained by combining it with a secondary battery that uses the positive electrode active material 100 obtained in the above embodiment as the positive electrode.

[0312] The control circuit unit 1320, which uses a memory circuit including an oxide semiconductor transistor, can also function as an automatic control device for secondary batteries to address causes of instability such as micro-shorts. Functions to eliminate causes of instability include overcharging prevention, overcurrent prevention, overheating control during charging, cell balancing in the battery pack, over-discharge prevention, remaining charge indicator, automatic control of charging voltage and current according to temperature, control of charging current according to the degree of degradation, detection of abnormal behavior of micro-shorts, and prediction of abnormalities related to micro-shorts. The control circuit unit 1320 has at least one of these functions. Furthermore, it is possible to miniaturize the automatic control device for secondary batteries.

[0313] Furthermore, a micro-short refers to a tiny short circuit inside a secondary battery. It does not mean that the positive and negative electrodes of the secondary battery are short-circuited, making charging and discharging impossible. Rather, it refers to a phenomenon where a small short-circuit current flows through a tiny short circuit. Because even a relatively short-circuit in a small area can cause a large voltage change, this abnormal voltage value may affect the estimation of the subsequent charging and discharging state of the secondary battery.

[0314] One of the causes of micro-short circuits is said to be that multiple charge-discharge cycles result in an uneven distribution of the positive electrode active material, causing localized current concentration in parts of the positive and negative electrodes, leading to areas where the separator malfunctions, or causing micro-short circuits due to the generation of by-reactants from side reactions.

[0315] Furthermore, in addition to detecting micro-shorts, the control circuit unit 1320 also detects the terminal voltage of the secondary battery and manages the charging and discharging state of the secondary battery. For example, to prevent overcharging, both the output transistor and the cutoff switch of the charging circuit can be turned off almost simultaneously.

[0316] Furthermore, an example of a block diagram of the battery pack 1415 shown in Figure 25(A) is shown in Figure 25(B).

[0317] The control circuit unit 1320 includes at least a switch to prevent overcharging, a switch unit 1324 including a switch to prevent over-discharging, a control circuit 1322 that controls the switch unit 1324, and a voltage measurement unit for the first battery 1301a. The control circuit unit 1320 has upper and lower voltage limits set for the secondary battery used, and limits the upper limit of external current and the upper limit of output current to the outside. Within the range between the lower voltage limit and the upper voltage limit of the secondary battery, it is within the voltage range for which use is recommended, and if it goes outside this range, the switch unit 1324 activates and functions as a protection circuit. The control circuit unit 1320 can also be called a protection circuit because it controls the switch unit 1324 to prevent over-discharge and overcharge. For example, if the control circuit 1322 detects a voltage that is likely to cause overcharging, it cuts off the current by turning off the switch in the switch unit 1324. Furthermore, a PTC element may be provided in the charge / discharge path to provide a function to cut off the current in response to the rise in temperature. Furthermore, the control circuit unit 1320 has an external terminal 1325 (+IN) and an external terminal 1326 (-IN).

[0318] The switch section 1324 can be constructed by combining an n-channel transistor and a p-channel transistor. The switch section 1324 is not limited to a switch having a Si transistor using single-crystal silicon, but can also 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), GaO x The switch section 1324 may be formed using a power transistor having a gallium oxide (where x is a real number greater than 0) or the like. Furthermore, since memory elements using OS transistors can be freely arranged by stacking them on circuits using Si transistors, integration can be easily achieved. Also, since OS transistors can be manufactured using the same manufacturing equipment as Si transistors, they can be manufactured at low cost. That is, by stacking a control circuit section 1320 using OS transistors on the switch section 1324 and integrating them, it is possible to create a single chip. Since the volume occupied by the control circuit section 1320 can be reduced, miniaturization becomes possible.

[0319] The first batteries 1301a and 1301b primarily supply power to 42V (high-voltage) in-vehicle equipment, while the second battery 1311 supplies power to 14V (low-voltage) in-vehicle equipment.

[0320] This embodiment shows an example in which lithium-ion secondary batteries are used for both the first battery 1301a and the second battery 1311. The second battery 1311 may be a lead-acid battery, an all-solid-state battery, or an electric double-layer capacitor. For example, the all-solid-state battery of Embodiment 4 may be used. By using the all-solid-state battery of Embodiment 4 for the second battery 1311, high capacity can be achieved, and the device can be made smaller and lighter.

[0321] Furthermore, the regenerative energy generated by the rotation of the tire 1316 is sent to the motor 1304 via the gear 1305 and charged the second battery 1311 via the control circuit unit 1321 from the motor controller 1303 and battery controller 1302. Alternatively, it is charged the first battery 1301a via the control circuit unit 1320 from the battery controller 1302. Alternatively, it is charged the first battery 1301b via the control circuit unit 1320 from the battery controller 1302. In order to efficiently charge the regenerative energy, it is desirable that the first batteries 1301a and 1301b are capable of rapid charging.

[0322] The battery controller 1302 can set the charging voltage and charging current of the first batteries 1301a and 1301b. The battery controller 1302 can set the charging conditions according to the charging characteristics of the secondary battery being used and enable rapid charging.

[0323] Although not shown in the diagram, when an electric vehicle is connected to an external charger, the charger's outlet or connection cable is electrically connected to the battery controller 1302. Power supplied from the external charger charges the first batteries 1301a and 1301b via the battery controller 1302. In some cases, the charger has a control circuit and does not use the functions of the battery controller 1302, but it is preferable to charge the first batteries 1301a and 1301b via the control circuit unit 1320 to prevent overcharging. In some cases, the charger's outlet or connection cable may also have a control circuit. The control circuit unit 1320 is sometimes called an ECU (Electronic Control Unit). The ECU is connected to a CAN (Controller Area Network) installed in the electric vehicle. CAN is one of the serial communication standards used as an in-vehicle LAN. The ECU also includes a microcomputer. The ECU also uses a CPU or GPU.

[0324] External chargers installed at charging stations and other locations include 100V outlets, 200V outlets, and 3-phase 200V with 50kW output. Additionally, it is possible to charge by receiving power from external charging equipment using contactless power supply methods.

[0325] For rapid charging, a rechargeable battery capable of withstanding high-voltage charging is desired to achieve short charging times.

[0326] Furthermore, the secondary battery of this embodiment described above uses the positive electrode active material 100 obtained in the previously described embodiment. In addition, by using graphene as a conductive material, even if the electrode layer is thickened and the load is increased, the decrease in capacity is suppressed and high capacity is maintained, resulting in a secondary battery with significantly improved electrical characteristics as a synergistic effect. This is particularly effective for secondary batteries used in vehicles, and it is possible to provide a vehicle with a long driving range, specifically a driving range of 500 km or more on a single charge, without increasing the ratio of the weight of the secondary battery to the total weight of the vehicle.

[0327] In particular, the secondary battery of this embodiment described above can achieve a higher operating voltage by using the positive electrode active material 100 described in the previous embodiment, and the usable capacity can be increased with increasing charging voltage. Furthermore, by using the positive electrode active material 100 described in the previous embodiment as the positive electrode, a secondary battery for vehicles with excellent cycle characteristics can be provided.

[0328] Next, we will describe an example in which a secondary battery, which is one aspect of the present invention, is implemented in a vehicle, typically a transport vehicle.

[0329] Furthermore, by mounting a secondary battery shown in any one of Figures 16(D), 18(C), or 25(A) onto a vehicle, next-generation clean energy vehicles such as hybrid vehicles (HV), electric vehicles (EV), or plug-in hybrid vehicles (PHV) can be realized. Secondary batteries can also be mounted on agricultural machinery, motorized bicycles including electric-assist bicycles, motorcycles, electric wheelchairs, electric carts, small or large vessels, submarines, aircraft such as fixed-wing and rotary-wing aircraft, rockets, satellites, space probes, planetary probes, and spacecraft. A secondary battery according to one embodiment of the present invention can be a high-capacity secondary battery. Therefore, a secondary battery according to one embodiment of the present invention is suitable for miniaturization and weight reduction, and can be suitably used in transport vehicles.

[0330] In Figures 26(A) to (D), a transport vehicle is shown as an example of a mobile body using one embodiment of the present invention. The automobile 2001 shown in Figure 26(A) is an electric vehicle that uses an electric motor as a power source for driving. Alternatively, it is a hybrid vehicle that can appropriately select and use an electric motor and an engine as power sources for driving. When a secondary battery is mounted on the vehicle, one or more examples of the secondary battery shown in Embodiment 3 are installed in one location. The automobile 2001 shown in Figure 26(A) has a battery pack 2200, and the battery pack has a secondary battery module in which multiple secondary batteries are connected. Furthermore, it is preferable to have a charging control device electrically connected to the secondary battery module.

[0331] Furthermore, the automobile 2001 can be charged by receiving power from an external charging facility via a plug-in method or a contactless power supply method to the secondary battery it possesses. When charging, the charging method and connector specifications may be carried out as appropriate using a prescribed method such as CHAdeMO® or Combo. The charging facility may be a charging station installed in a commercial facility or a household power supply. For example, the battery storage device mounted on the automobile 2001 can be charged by supplying power from an external source using plug-in technology. Charging can be performed by converting AC power to DC power via a conversion device such as an AC / DC converter.

[0332] Although not shown in the diagram, the vehicle can also be charged by mounting a power receiving device on the vehicle and receiving power wirelessly from a ground-based power transmission device. In this wireless power supply method, charging can be performed not only when the vehicle is stopped but also while it is in motion by incorporating the power transmission device into the road or exterior wall. Furthermore, this wireless power supply method can be used to transmit and receive power between two vehicles. In addition, solar panels can be installed on the exterior of the vehicle to charge the secondary battery when the vehicle is stopped and when it is in motion. For such wireless power supply, electromagnetic induction or magnetic resonance methods can be used.

[0333] Figure 26(B) shows a large transport vehicle 2002 equipped with an electrically controlled motor as an example of a transport vehicle. The secondary battery module of the transport vehicle 2002 has a maximum voltage of 170V, achieved by connecting 48 cells in series, each consisting of four secondary batteries with a nominal voltage of 3.0V to 5.0V. The secondary battery module of the battery pack 2201 has the same functions as Figure 26(A), except for differences in the number of secondary batteries that make up the module, so the explanation is omitted.

[0334] Figure 26(C) shows, as an example, a large transport vehicle 2003 equipped with an electrically controlled motor. The secondary battery module of the transport vehicle 2003 has a maximum voltage of 600V, achieved by connecting more than 100 secondary batteries with a nominal voltage of 3.0V to 5.0V in series. By using secondary batteries with the positive electrode active material 100 described in the above embodiment as the positive electrode, it is possible to manufacture secondary batteries with good rate characteristics and charge / discharge cycle characteristics, which can contribute to the high performance and long lifespan of the transport vehicle 2003. Furthermore, since it has the same functions as Figure 26(A) except for differences in the number of secondary batteries constituting the secondary battery module of the battery pack 2202, the explanation is omitted.

[0335] Figure 26(D) shows an example of an aircraft 2004 having a fuel-burning engine. The aircraft 2004 shown in Figure 26(D) has wheels for takeoff and landing, and can therefore be considered part of a transport vehicle. It has a battery pack 2203 which includes a secondary battery module formed by connecting multiple secondary batteries and a charging control device.

[0336] The secondary battery module of aircraft 2004 has a maximum voltage of 32V, for example, by connecting eight 4V secondary batteries in series. The secondary battery module of battery pack 2203 has the same functions as Figure 26(A), except for the number of secondary batteries that make up the module, so the explanation is omitted.

[0337] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0338] (Embodiment 7) In this embodiment, an example of mounting a secondary battery, which is one aspect of the present invention, in a building will be explained using Figures 27(A) and 27(B).

[0339] The house shown in Figure 27(A) has a power storage device 2612 having a secondary battery, which is one embodiment of the present invention, and a solar panel 2610. The power storage device 2612 is electrically connected to the solar panel 2610 via wiring 2611, etc. The power storage device 2612 may also be electrically connected to a ground-mounted charging device 2604. The electricity obtained from the solar panel 2610 can be used to charge the power storage device 2612. The electricity stored in the power storage device 2612 can be used to charge the secondary battery of the vehicle 2603 via the charging device 2604. The power storage device 2612 is preferably installed in the underfloor space. By installing it in the underfloor space, the space above the floor can be used effectively. Alternatively, the power storage device 2612 may be installed on the floor.

[0340] The electricity stored in the energy storage device 2612 can also supply power to other electronic devices in the house. Therefore, even when power cannot be supplied from the commercial power source due to a power outage or the like, electronic devices can be used by using the energy storage device 2612 according to one aspect of the present invention as an uninterruptible power supply.

[0341] Figure 27(B) shows an example of an energy storage device according to one aspect of the present invention. As shown in Figure 27(B), an energy storage device 791 according to one aspect of the present invention is installed in the underfloor space 796 of the building 799. Furthermore, the energy storage device 791 may be equipped with the control circuit described in Embodiment 5, and by using a secondary battery with the positive electrode active material 100 obtained in the above embodiment as the positive electrode in the energy storage device 791, a long-life energy storage device 791 can be made.

[0342] The energy storage device 791 is equipped with a control device 790, which is electrically connected by wiring to the distribution board 703, the energy storage controller 705 (also called the control device), the display unit 706, and the router 709.

[0343] Power is supplied from the commercial power supply 701 to the distribution panel 703 via the service drop connection section 710. Power is also supplied to the distribution panel 703 from the energy storage device 791 and the commercial power supply 701, and the distribution panel 703 supplies the supplied power to the general load 707 and the energy storage system load 708 via outlets (not shown).

[0344] General loads 707 are electrical equipment such as televisions and personal computers, while energy storage loads 708 are electrical equipment such as microwave ovens, refrigerators, and air conditioners.

[0345] The energy storage controller 705 includes a measurement unit 711, a prediction unit 712, and a planning unit 713. The measurement unit 711 has the function of measuring the amount of electricity consumed by the general load 707 and the energy storage system load 708 during a day (for example, from 0:00 to 24:00). The measurement unit 711 may also have the function of measuring the amount of electricity consumed by the energy storage device 791 and the amount of electricity supplied from the commercial power supply 701. The prediction unit 712 has the function of predicting the amount of electricity demanded by the general load 707 and the energy storage system load 708 during the next day, based on the amount of electricity consumed by the general load 707 and the energy storage system load 708 during the day. The planning unit 713 has the function of planning the charging and discharging of the energy storage device 791 based on the amount of electricity demand predicted by the prediction unit 712.

[0346] The amount of electricity consumed by the general load 707 and the energy storage system load 708, as measured by the measurement unit 711, can be checked on the display unit 706. It can also be checked on electrical equipment such as televisions and personal computers via the router 709. Furthermore, it can be checked on mobile electronic devices such as smartphones and tablets via the router 709. Additionally, the amount of electricity demand for each time period (or hourly) predicted by the prediction unit 712 can be checked on the display unit 706, electrical equipment, and mobile electronic devices.

[0347] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0348] (Embodiment 8) This embodiment shows an example of mounting an energy storage device according to one aspect of the present invention on a motorcycle or bicycle.

[0349] Furthermore, Figure 28(A) shows an example of an electric bicycle using a power storage device according to one embodiment of the present invention. The power storage device according to one embodiment of the present invention can be applied to the electric bicycle 8700 shown in Figure 28(A). The power storage device according to one embodiment of the present invention includes, for example, a plurality of storage batteries and a protection circuit.

[0350] The electric bicycle 8700 is equipped with a power storage device 8702. The power storage device 8702 can supply electricity to a motor that assists the rider. The power storage device 8702 is also portable, and Figure 28(B) shows it detached from the bicycle. The power storage device 8702 also has multiple storage batteries 8701, which are part of a power storage device according to one embodiment of the present invention, and the remaining battery level and other information can be displayed on a display unit 8703. The power storage device 8702 also has a control circuit 8704 capable of controlling the charging of a secondary battery or detecting abnormalities, as exemplified in Embodiment 5. The control circuit 8704 is electrically connected to the positive and negative electrodes of the storage battery 8701. A small solid-state secondary battery, as shown in Figures 24(A) and 24(B), may also be provided in the control circuit 8704. By providing the small solid-state secondary battery shown in Figures 24(A) and 24(B) to the control circuit 8704, power can be supplied to the memory circuit of the control circuit 8704 to retain data for extended periods. Furthermore, a synergistic effect on safety can be obtained by combining it with a secondary battery that uses the positive electrode active material 100 obtained in the above embodiment as the positive electrode. The secondary battery and control circuit 8704 that use the positive electrode active material 100 obtained in the above embodiment as the positive electrode can greatly contribute to eliminating accidents such as fires caused by secondary batteries.

[0351] Furthermore, Figure 28(C) shows an example of a motorcycle using a power storage device according to one embodiment of the present invention. The electric motorcycle 8600 shown in Figure 28(C) is equipped with a power storage device 8602, side mirrors 8601, and turn signals 8603. The power storage device 8602 can supply electricity to the turn signals 8603. In addition, the power storage device 8602, which houses multiple secondary batteries using the positive electrode active material 100 obtained in the above embodiment as the positive electrode, can have a high capacity and contribute to miniaturization.

[0352] Furthermore, the electric motorcycle 8600 shown in Figure 28(C) can accommodate the power storage device 8602 in the under-seat storage compartment 8604. The power storage device 8602 can be stored in the under-seat storage compartment 8604 even if the under-seat storage compartment 8604 is small.

[0353] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0354] (Embodiment 9) This embodiment describes an example of mounting a secondary battery, which is one aspect of the present invention, in an electronic device. Examples of electronic devices on which a secondary battery is mounted include television equipment (also called televisions or television receivers), monitors for computers, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game consoles, personal information terminals, sound playback devices, and large game machines such as pachinko machines. Personal information terminals include notebook personal computers, tablet terminals, e-book readers, and mobile phones.

[0355] Figure 29(A) shows an example of a mobile phone. The mobile phone 2100 includes a display unit 2102 built into the housing 2101, as well as operation buttons 2103, an external connection port 2104, a speaker 2105, a microphone 2106, and the like. The mobile phone 2100 also has a secondary battery 2107. By providing a secondary battery 2107 that uses the positive electrode active material 100 described in the above embodiment as the positive electrode, a high capacity can be achieved, and a configuration that can accommodate space saving due to the miniaturization of the housing can be realized.

[0356] The mobile phone 2100 can run various applications such as making phone calls, sending emails, reading and creating documents, playing music, communicating on the internet, and playing computer games.

[0357] The operation button 2103 can be assigned various functions, including time setting, power on / off operation, wireless communication on / off operation, silent mode activation / deactivation, and power saving mode activation / deactivation. For example, the function of the operation button 2103 can be freely configured by the operating system built into the mobile phone 2100.

[0358] Furthermore, the 2100 mobile phone is capable of performing standardized short-range wireless communication. For example, it can communicate with a wireless headset to enable hands-free calling.

[0359] Furthermore, the mobile phone 2100 is equipped with an external connection port 2104, which allows for direct data exchange with other information terminals via a connector. It can also be charged via the external connection port 2104. Note that charging may also be performed wirelessly without using the external connection port 2104.

[0360] The mobile phone 2100 preferably has sensors. For example, it is preferable that the sensor includes a human body sensor such as a fingerprint sensor, pulse sensor, or body temperature sensor, as well as a touch sensor, pressure sensor, acceleration sensor, etc.

[0361] Figure 29(B) shows an unmanned aerial vehicle 2300 having multiple rotors 2302. The unmanned aerial vehicle 2300 is sometimes called a drone. The unmanned aerial vehicle 2300 has a secondary battery 2301, a camera 2303, and an antenna (not shown), which are embodiments of the present invention. The unmanned aerial vehicle 2300 can be remotely controlled via the antenna. The secondary battery using the positive electrode active material 100 obtained in the above embodiment as the positive electrode has a high energy density and high safety, so it can be used safely for a long period of time over a long period of time and is suitable as a secondary battery to be mounted on the unmanned aerial vehicle 2300.

[0362] Figure 29(C) shows an example of a robot. The robot 6400 shown in Figure 29(C) is equipped with a secondary battery 6409, an illuminance sensor 6401, a microphone 6402, an upper camera 6403, a speaker 6404, a display unit 6405, a lower camera 6406 and an obstacle sensor 6407, a movement mechanism 6408, a computing device, and the like.

[0363] Microphone 6402 has the function of detecting the user's voice and ambient sounds. Speaker 6404 has the function of emitting sound. Robot 6400 can communicate with the user using microphone 6402 and speaker 6404.

[0364] The display unit 6405 has the function of displaying various types of information. The robot 6400 can display the information desired by the user on the display unit 6405. The display unit 6405 may be equipped with a touch panel. The display unit 6405 may also be a detachable information terminal, and by installing it in a fixed position on the robot 6400, charging and data transfer can be made possible.

[0365] The upper camera 6403 and lower camera 6406 have the function of imaging the area around the robot 6400. In addition, the obstacle sensor 6407 can detect the presence or absence of obstacles in the direction of travel when the robot 6400 moves forward using the movement mechanism 6408. The robot 6400 can recognize its surrounding environment and move safely using the upper camera 6403, lower camera 6406 and obstacle sensor 6407.

[0366] The robot 6400 is equipped with a secondary battery 6409 according to one aspect of the present invention and a semiconductor device or electronic components in its internal region. The secondary battery using the positive electrode active material 100 obtained in the above-described embodiment as the positive electrode has a high energy density and high safety, so it can be used safely for a long period of time over a long period of time and is suitable as a secondary battery 6409 to be mounted on the robot 6400.

[0367] Figure 29(D) shows an example of a cleaning robot. The cleaning robot 6300 has a display unit 6302 located on the top surface of the housing 6301, multiple cameras 6303 located on the sides, a brush 6304, operation buttons 6305, a secondary battery 6306, and various sensors. Although not shown, the cleaning robot 6300 is equipped with wheels, a suction port, etc. The cleaning robot 6300 is self-propelled, can detect dirt 6310, and can suck up the dirt from a suction port located on the bottom surface.

[0368] For example, the cleaning robot 6300 can analyze images captured by the camera 6303 to determine the presence or absence of obstacles such as walls, furniture, or steps. Furthermore, if the image analysis detects an object that might become entangled in the brush 6304, such as wiring, the rotation of the brush 6304 can be stopped. The cleaning robot 6300 is equipped with a secondary battery 6306 according to one embodiment of the present invention and a semiconductor device or electronic component within its internal region. The secondary battery using the positive electrode active material 100 obtained in the above-described embodiment as the positive electrode has high energy density and high safety, allowing for safe use over long periods, making it suitable as a secondary battery 6306 for the cleaning robot 6300.

[0369] Figure 30(A) shows an example of a wearable device. Wearable devices use rechargeable batteries as a power source. Furthermore, in order to enhance splash resistance, water resistance, or dust resistance when used by users in daily life or outdoors, there is a demand for wearable devices that can be charged wirelessly in addition to wired charging with exposed connectors.

[0370] For example, a secondary battery according to one embodiment of the present invention can be mounted in a spectacle-type device 4000 as shown in Figure 30(A). The spectacle-type device 4000 has a frame 4000a and a display unit 4000b. By mounting the secondary battery in the temple portion of the curved frame 4000a, a lightweight spectacle-type device 4000 with good weight balance and a long continuous usage time can be made. The secondary battery using the positive electrode active material 100 obtained in the above embodiment as the positive electrode has a high energy density and can realize a configuration that can accommodate space saving due to the miniaturization of the housing.

[0371] Furthermore, a secondary battery according to one aspect of the present invention can be mounted in the headset-type device 4001. The headset-type device 4001 has at least a microphone section 4001a, a flexible pipe 4001b, and an earphone section 4001c. The secondary battery can be provided in the flexible pipe 4001b or in the earphone section 4001c. The secondary battery using the positive electrode active material 100 obtained in the above embodiment as the positive electrode has a high energy density and can realize a configuration that can accommodate space saving due to the miniaturization of the housing.

[0372] Furthermore, a secondary battery according to one embodiment of the present invention can be mounted on a device 4002 that can be directly attached to the body. The secondary battery 4002b can be provided inside the thin housing 4002a of the device 4002. The secondary battery using the positive electrode active material 100 obtained in the above embodiment as the positive electrode has a high energy density and can realize a configuration that can accommodate space saving due to the miniaturization of the housing.

[0373] Furthermore, a secondary battery according to one embodiment of the present invention can be mounted on a device 4003 that can be attached to clothing. The secondary battery 4003b can be provided inside the thin housing 4003a of the device 4003. The secondary battery using the positive electrode active material 100 obtained in the above embodiment as the positive electrode has a high energy density and can realize a configuration that can accommodate space saving due to the miniaturization of the housing.

[0374] Furthermore, a secondary battery according to one embodiment of the present invention can be mounted on the belt-type device 4006. The belt-type device 4006 has a belt portion 4006a and a wireless power supply and receiving portion 4006b, and a secondary battery can be mounted in the internal region of the belt portion 4006a. A secondary battery using the positive electrode active material 100 obtained in the above embodiment as the positive electrode has a high energy density and can realize a configuration that can accommodate space saving due to the miniaturization of the housing.

[0375] Furthermore, a secondary battery according to one aspect of the present invention can be mounted in the wristwatch-type device 4005. The wristwatch-type device 4005 has a display unit 4005a and a belt unit 4005b, and the secondary battery can be provided in either the display unit 4005a or the belt unit 4005b. The secondary battery using the positive electrode active material 100 obtained in the above embodiment as the positive electrode has a high energy density and can realize a configuration that can accommodate space saving due to the miniaturization of the housing.

[0376] The display unit 4005a can display not only the time, but also various other information such as incoming emails and phone calls.

[0377] Furthermore, since the wristwatch-type device 4005 is a wearable device that is worn directly on the wrist, it may be equipped with sensors to measure the user's pulse, blood pressure, etc. It can accumulate data on the user's exercise level and health, and manage their health.

[0378] Figure 30(B) shows a perspective view of the wristwatch-type device 4005 after it has been removed from the arm.

[0379] A side view is also shown in Figure 30(C). Figure 30(C) shows how the secondary battery 913 is built into the internal region. The secondary battery 913 is the secondary battery shown in Embodiment 3. The secondary battery 913 is located in a position that overlaps with the display unit 4005a, allowing for high density and high capacity, as well as being small and lightweight.

[0380] Since the wristwatch-type device 4005 is required to be small and lightweight, using the positive electrode active material 100 obtained in the above embodiment as the positive electrode of the secondary battery 913 makes it possible to create a secondary battery 913 that is both high in energy density and compact.

[0381] Figure 30(D) shows an example of wireless earphones. Here, wireless earphones with a pair of main units 4100a and 4100b are illustrated, but they do not necessarily have to be a pair.

[0382] The main units 4100a and 4100b include a driver unit 4101, an antenna 4102, and a secondary battery 4103. They may also have a display unit 4104. Preferably, they also have a circuit board with a wireless IC or the like, charging terminals, etc. They may also have a microphone.

[0383] The case 4110 contains a secondary battery 4111. Preferably, it also has a circuit board on which circuits such as a wireless IC and a charging control IC are mounted, and charging terminals. It may also have a display unit, buttons, etc.

[0384] The main units 4100a and 4100b can communicate wirelessly with other electronic devices such as smartphones. This allows them to play audio data sent from other electronic devices. Furthermore, if the main units 4100a and 4100b have microphones, they can send sound acquired by the microphones to other electronic devices, process the audio data, and then send it back to the main units 4100a and 4100b for playback. This allows them to be used, for example, as a translation device.

[0385] Furthermore, the secondary battery 4103 in the main unit 4100a can be charged from the secondary battery 4111 in the case 4110. As the secondary battery 4111 and the secondary battery 4103, coin-type secondary batteries, cylindrical secondary batteries, etc., as in the previous embodiment can be used. The secondary battery using the positive electrode active material 100 obtained in the above embodiment as the positive electrode has a high energy density, and by using it in the secondary battery 4103 and the secondary battery 4111, a configuration that can accommodate space saving due to the miniaturization of wireless earphones can be realized.

[0386] This embodiment can be implemented in appropriate combination with other embodiments. [Examples]

[0387] In this example, a positive electrode active material according to one embodiment of the present invention was prepared, and its cycle characteristics were evaluated.

[0388] First, the method for preparing the positive electrode active material will be explained with reference to Figures 1 through 8.

[0389] <Sample 1> Nickel(II) sulfate was used as the nickel source, cobalt(II) sulfate as the cobalt source, and manganese(II) sulfate as the manganese source. The amounts were weighed to achieve a molar ratio of Ni:Co:Mn = 8:1:1, and dissolved in water to a 2M solution. 0.075M glycine was added as a chelating agent to prepare an acid solution.

[0390] A 5M sodium hydroxide aqueous solution was used as the alkaline solution.

[0391] A 0.075 M glycine aqueous solution was used as the loading solution. Nitrogen was bubbled into the loading solution at a nitrogen flow rate of 1 L / min.

[0392] The acid solution was added dropwise while stirring the substrate at 1000 rpm. The dropwise addition rate was increased from 0.40 mL / min to 0.93 mL / min. The alkaline solution was added dropwise as needed to maintain the pH of the substrate at 10.3. The temperature of the substrate was also maintained at 70°C. OptiMax (Mettler-Toledo) was used for these coprecipitation reactions.

[0393] The precipitate formed by the above coprecipitation reaction was filtered with pure water and acetone, dried, and a complex hydroxide was obtained.

[0394] Lithium hydroxide monohydrate was used as the lithium source and mixed with the composite hydroxide obtained above. The mixing ratio was set so that lithium was 1.01 (molar ratio) when the sum of nickel, cobalt, and manganese was 1.

[0395] The above mixture was heated in an aluminum oxide crucible in a muffle furnace at 500°C for 10 hours in an oxygen atmosphere. The oxygen flow rate was 5 L / min. After cooling to room temperature, it was crushed to obtain a composite oxide.

[0396] The composite oxide obtained above was similarly heated at 800°C for 10 hours. This comparative example, prepared without the use of additive elements, was designated as Sample 1.

[0397] <Sample 2> In Sample 2, gallium was added in step S12. Specifically, gallium(III) sulfate was used as the gallium source, weighed to a molar ratio of Ni:Co:Mn:Ga = 80:10:9:1, dissolved in water to a 2M solution, and glycine was added to prepare an acid solution. The mixing rate of the acid solution was increased from 0.20 mL / min to 0.47 mL / min. The rest of the preparation was the same as for Sample 1. That is, a lithium source was added and the mixture was heated at 500°C for 10 hours, followed by heating at 800°C for 10 hours.

[0398] <Sample 3> In Sample 3, the same composite hydroxide as in Sample 1 was used, with gallium added in step S41. Specifically, gallium oxyhydroxide was used as the gallium source and mixed with the lithium source and the composite hydroxide prepared in the same manner as in Sample 1. The mixing ratio was 0.01 (molar ratio) of gallium when the sum of nickel, cobalt, and manganese was 1. The rest of the preparation was the same as in Sample 1. That is, the lithium source and gallium source were added and heated at 500°C for 10 hours, followed by heating at 800°C for 10 hours.

[0399] <Sample 4> In Sample 4, the same composite hydroxide as in Sample 1 was used, and gallium was added in step S61. Specifically, gallium oxyhydroxide was used as the gallium source and mixed with the composite oxide prepared in the same manner as in Sample 1. The mixing ratio was 0.01 (molar ratio) of gallium when the sum of nickel, cobalt, and manganese was considered to be 1. Specifically, a lithium source was added and the mixture was heated at 500°C for 10 hours, followed by heating at 800°C for 10 hours. A gallium source was then added and the mixture was heated at 800°C for 2 hours. The rest of the preparation was the same as in Sample 1.

[0400] <Sample 11> Sample 11 was prepared in the same manner as Sample 1.

[0401] <Sample 12> In Sample 12, aluminum was added in step S12. Specifically, aluminum sulfate was used as the aluminum source, weighed to a molar ratio of Ni:Co:Mn:Al = 79:10:10:1, dissolved in water to a 2M solution, and glycine was added to prepare an acid solution. The acid solution was added dropwise at a rate of 0.8 L / min. The rest of the preparation was the same as for Sample 2.

[0402] <Sample 13> In Sample 13, the same composite hydroxide as in Sample 11 was used, with aluminum added in step S41. Specifically, aluminum hydroxide was used as the aluminum source and mixed with the lithium source along with the composite hydroxide prepared in the same manner as in Sample 1. The mixing ratio was set to 0.01 (molar ratio) of aluminum when the sum of nickel, cobalt, and manganese was considered to be 1. The rest of the preparation was the same as in Sample 3.

[0403] <Sample 14> In Sample 14, the same composite hydroxide as in Sample 11 was used, with aluminum added in step S61. Specifically, aluminum hydroxide was used as the aluminum source and mixed with the composite oxide prepared in the same manner as in Sample 1. The mixing ratio was set to 0.01 (molar ratio) of aluminum when the sum of nickel, cobalt, and manganese was considered to be 1. The rest of the preparation was the same as in Sample 4.

[0404] Table 4 shows the preparation conditions for Samples 1 through 4 and Samples 11 through 14.

[0405] [Table 4]

[0406] <sem> SEM images of Sample 1 are shown in Figure 31(A), Sample 2 in Figure 31(B), Sample 3 in Figure 32(A), and Sample 4 in Figure 32(B). The positive electrode active material in all samples consisted of secondary particles.

[0407] <Cycle Characteristics> Using the positive electrode active material prepared above, a half-cell was assembled as follows.

[0408] Acetylene black (AB) was prepared as the conductive material, and polyvinylidene fluoride (PVDF) was prepared as the binder. A slurry was prepared by mixing the positive electrode active material, AB, and PVDF in a weight ratio of 95:3:2, and this slurry was coated onto an aluminum current collector. NMP (N-methyl-2-pyrrolidone) was used as the solvent for the slurry.

[0409] After coating the current collector with slurry, the solvent was evaporated and the material was pressed. The positive electrode was obtained through these steps. The active material content of the positive electrode was approximately 7 mg / cm³. 2 That's what I decided.

[0410] The electrolyte consisted of a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7, with 2 wt% vinylene carbonate (VC) added as an additive. The electrolyte in the electrolyte solution was 1 mol / L lithium hexafluoride phosphate (LiPF6). Polypropylene was used as the separator.

[0411] A lithium metal was used as the counter electrode, and a coin-shaped half-cell equipped with the above-mentioned positive electrode was formed, and the charge-discharge cycle characteristics were measured.

[0412] Charging was performed using CC / CV (100mA / g, 4.5V, 10mA / g cut), and discharging was performed using CC (100mA / g, 2.7V cut). A 10-minute pause was taken between charging and discharging. The measurement temperature was 45°C for both tests.

[0413] The discharge capacities of Samples 1 to 4 are shown in Figure 33(A), and the discharge capacity retention rates are shown in Figure 33(B). Similarly, the discharge capacities of Samples 11 to 14 are shown in Figure 34(A), and the discharge capacity retention rates are shown in Figure 34(B). The maximum discharge capacities are also shown in Table 4.

[0414] As shown in Figures 33 and 34, despite the relatively high measurement temperature of 45°C, samples 2 through 4 and samples 12 through 14 showed good cycle characteristics. In particular, the samples in which the additive elements were mixed in step S61 showed the best discharge capacity retention rate. After 50 cycles, the discharge capacity retention rate was 94.6% for sample 4 and 94.0% for sample 14. [Explanation of symbols]

[0415] 98. Complex Hydroxides 99. Composite Oxides 100 Cathode active material 104 Tetrahedron Site 108 Octahedron Site 110 Replacement locations 170 Co-precipitation method synthesis equipment 171 Reaction vessel 172 Stirring section 173 Stirring motor 174 Thermometer 175 tank 176 tube 177 Pump 180 tanks 181 tube 182 pump 186 Tank 187 tube 188 Pump 190 Control device 191 Reflux condenser 192 Water< / sem>

Claims

1. A composite hydroxide containing nickel, cobalt, and manganese is formed by reacting an aqueous solution containing nickel, cobalt, and manganese with an alkaline solution. The composite hydroxide, the lithium source, and the first additive element source are mixed together. Heat, A method for producing a positive electrode active material, The first additive element source has a first additive element, A method for producing a cathode active material, wherein the first additive element is gallium.

2. In claim 1, A method for producing a cathode active material, wherein the first additive element source is gallium hydroxide, gallium oxyhydroxide, or an organic acid salt of gallium.

3. A composite hydroxide containing nickel, cobalt, and manganese is formed by reacting an aqueous solution containing nickel, cobalt, and manganese with an alkaline solution. The composite hydroxide is mixed with a lithium source, and a first heating is performed to form a composite oxide. The composite oxide is mixed with the first additive element source. A method for producing a positive electrode active material, comprising a second heating process, The first additive element source has a first additive element, A method for producing a cathode active material, wherein the first additive element is gallium.

4. In claim 3, A method for producing a positive electrode active material, wherein the second heating is performed at a temperature above 750°C and below 850°C.

5. In claim 3 or claim 4, A method for producing a cathode active material, wherein the first additive element source is gallium hydroxide, gallium oxyhydroxide, or an organic acid salt of gallium.

6. An acid solution is prepared by mixing an aqueous solution containing nickel, cobalt, and manganese with an aqueous solution containing a first additive element. The acid solution is reacted with an alkaline solution to form a composite hydroxide having nickel, cobalt, manganese, and the first additive element. The composite hydroxide is mixed with a lithium source, and a first heating is performed to form a composite oxide. The composite oxide is mixed with a second additive element source. A method for producing a positive electrode active material, comprising a second heating process, The first additive element is at least one selected from gallium, boron, aluminum, indium, magnesium, and fluorine. The second additive element source has a second additive element, A method for producing a positive electrode active material, wherein the second additive element is at least one selected from calcium, gallium, boron, aluminum, indium, magnesium, and fluorine.

7. In claim 6, A method for producing a positive electrode active material, wherein the second heating is performed at a temperature above 750°C and below 850°C.

8. In claim 6 or claim 7, The first additive element is gallium, The first source of additive elements is gallium hydroxide, gallium oxyhydroxide, or an organic salt of gallium. The second additive element is calcium. A method for producing a positive electrode active material, wherein the second additive element source is calcium carbonate or calcium fluoride.

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