Preparation method for positive electrode active material

Abstract

Provided is a positive electrode active material having a large charge / discharge capacity. Also provided is a novel positive electrode active material. According to the present invention, a positive electrode active material is prepared by: obtaining a compound (also referred to as a precursor) that contains nickel, cobalt, manganese, and aluminum by the use of a coprecipitation method; subsequently heating a mixture, which is obtained by mixing a lithium compound and the compound containing nickel, cobalt, manganese, and aluminum, at a first heating temperature; pulverizing or crushing the mixture; subsequently heating the mixture at a second heating temperature; mixing in an additive; and then subjecting the resulting mixture to a third heating treatment.

Description

Method for producing positive electrode active material

[0001] The present invention relates to a positive electrode active material, a secondary battery, and a method for manufacturing the same, or to a mobile information terminal and a vehicle having a secondary battery.

[0002] One embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, an electronic device, or a manufacturing method thereof.

[0003] In this specification, the term "semiconductor device" refers to any device that can function by utilizing semiconductor characteristics, and electro-optical devices, semiconductor circuits, and electronic devices are all included in the category of semiconductor devices.

[0004] In this specification, the term "power storage device" refers to elements and devices in general that have a power storage function, including, for example, power storage devices such as lithium ion secondary batteries (also called secondary batteries), lithium ion capacitors, and electric double layer capacitors.

[0005] In recent years, the development of various power storage devices, such as lithium-ion secondary batteries, lithium-ion capacitors, and air batteries, has been actively pursued. Demand for high-power, high-energy-density lithium-ion secondary batteries, in particular, has rapidly expanded along with the development of the semiconductor industry, and they are now essential to the modern information society as a rechargeable energy source, as they are used in portable information terminals such as mobile phones, smartphones, and notebook computers, portable music players, digital cameras, medical devices, and next-generation clean-energy vehicles such as hybrid vehicles (HVs), electric vehicles (EVs), and plug-in hybrid vehicles (PHVs).

[0006] Patent Document 1 discloses a positive electrode active material for a lithium ion secondary battery that has a high capacity and is excellent in charge / discharge cycle performance.

[0007] International Publication No. 2020 / 099978

[0008] An object of one embodiment of the present invention is to provide a positive electrode active material having a large charge / discharge capacity. Another object is to provide a positive electrode active material having a high charge / discharge voltage. Another object is to provide a positive electrode active material that is not easily deteriorated. Another object is to provide a novel positive electrode active material. Another object is to provide a secondary battery having a large charge / discharge capacity. Another object is to provide a secondary battery having a high charge / discharge voltage. Another object is to provide a secondary battery that is safe or highly reliable. Another object is to provide a secondary battery that is not easily deteriorated. Another object is to provide a secondary battery with a long life. Another object is to provide a novel secondary battery.

[0009] Another object of one embodiment of the present invention is to provide a novel substance, an active material, a power storage device, or a manufacturing method thereof.

[0010] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these can be extracted from the description in the specification, drawings, and claims.

[0011] Conventionally, lithium cobalt oxide (LiCoO), also known as LCO, has been used as a positive electrode active material for lithium ion secondary batteries with high energy density. ２ However, since LCO contains a large amount of expensive cobalt, a positive electrode active material with a low cobalt content is desired. For example, a positive electrode active material called NCM is known as a positive electrode active material with a low cobalt content. NCM is a LiNi ｘ Co ｙ Mn ｚ O ２ (x>0, y>0, z>0), and as an example, x, y, and z satisfy x:y:z=5:2:3 or a value close to that.

[0012] The positive electrode active material disclosed in this specification is a material in which aluminum is added as a first additive element and calcium is added as a second additive element to a material having a low cobalt content, where x, y, and z satisfy the relationship x:y:z=8:1:1 or values ​​close to the above.

[0013] By reducing the cobalt content, manufacturing costs can be reduced. Furthermore, a higher nickel ratio increases the change in the valence of the transition metal that contributes to charge and discharge, thereby increasing capacity. The positive electrode active material disclosed herein is configured to improve reliability by sequentially adding a first additive element and a second additive element.

[0014] The timing at which the first additive element and the second additive element are added in sequence is also characteristic, and the manufacturing method thereof will be disclosed below.

[0015] The method for producing a positive electrode active material disclosed in this specification includes supplying an aqueous solution containing a water-soluble salt of nickel, a water-soluble salt of cobalt, a water-soluble salt of manganese, and a water-soluble salt of aluminum, and an alkaline solution to a reaction vessel, mixing them inside the reaction vessel to precipitate a compound containing at least nickel, cobalt, and manganese, heating a first mixture obtained by mixing the compound containing at least nickel, cobalt, and manganese with a lithium compound at a first heating temperature, crushing or pulverizing the first mixture, and then further heating it at a second heating temperature, and mixing the first mixture with a calcium compound to obtain a second mixture, and heating it at a third heating temperature.

[0016] The pH inside the reaction vessel is preferably 9.0 or more and 12.0 or less, and more preferably 10.5 or more and 11.5 or less.

[0017] A chelating agent is added when an aqueous solution and an alkaline solution are mixed to precipitate a compound containing at least nickel, cobalt, and manganese. Precipitation refers to the generation of new particles or substances through a reaction in the reaction liquid, or the formation of a substance that grows around the generated particles or substances. The substance precipitated by the coprecipitation method is called a precursor. Examples of chelating agents include glycine, oxine, 1-nitroso-2-naphthol, 2-mercaptobenzothiazole, and EDTA (ethylenediaminetetraacetic acid). Multiple agents selected from glycine, oxine, 1-nitroso-2-naphthol, and 2-mercaptobenzothiazole may also be used. The chelating agent is dissolved in pure water to form a chelating aqueous solution. The chelating agent is a complexing agent that forms a chelate compound and is preferable to conventional complexing agents. Of course, complexing agents other than chelating agents may also be used; conventional complexing agents, such as aqueous ammonia, can be used.

[0018] The use of a chelate aqueous solution is preferable because it can suppress the generation of unnecessary crystal nuclei and promote growth. Suppressing the generation of unnecessary nuclei suppresses the generation of fine particles, thereby enabling the production of hydroxides with a good particle size distribution. Furthermore, the use of a chelate aqueous solution can delay the acid-base reaction, allowing the reaction to proceed gradually, resulting in the production of secondary particles that are nearly spherical. When a glycine aqueous solution is used as the chelate aqueous solution, the glycine concentration of the glycine aqueous solution is preferably 0.075 mol / L or more and 0.4 mol / L or less in the aqueous solution in which the transition metal salt is dissolved.

[0019] The positive electrode active material obtained by the above method has crystals with a hexagonal layer structure. The crystals are not limited to single crystals (also called crystallites). In the case of polycrystals, several crystallites aggregate to form primary particles. Primary particles refer to particles that are recognized as grains with a single smooth surface when observed under an SEM. Secondary particles refer to clumps of aggregated primary particles. In SEM observation, different primary particles have visible boundaries or different colors due to differences in crystallinity, crystal orientation, or composition. For this reason, they are often visible as distinct regions. The aggregation of primary particles does not depend on the bonding force acting between multiple primary particles. It may be a covalent bond, ionic bond, hydrophobic interaction, van der Waals force, or other intermolecular interaction, or multiple bonding forces may be acting.

[0020] When coprecipitation is used, secondary particles may be formed, with the size of the secondary particles being between 5 μm and 30 μm, and the size of the primary particles being between 50 nm and 100 nm.

[0021] A secondary battery using the above-described positive electrode active material is also one of the configurations disclosed in this specification. The secondary battery has a positive electrode having a positive electrode active material and a negative electrode having a negative electrode active material. A separator is also provided between the positive electrode and the negative electrode. The separator is used to prevent short circuits, and a safe and highly reliable secondary battery can be provided.

[0022] According to one embodiment of the present invention, two heat treatments improve the mixing state of the mixture, thereby reducing voids in the secondary particles when a secondary battery is fabricated. Furthermore, three heat treatments, two before the addition of calcium and one after the addition, can improve crystallinity. Therefore, a high-capacity positive electrode active material can be provided. Alternatively, a positive electrode active material that is relatively stable even after repeated charge and discharge can be provided. Alternatively, a secondary battery with high safety or reliability can be provided.

[0023] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will 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.

[0024] FIG. 1 illustrates an example of a production flow of a positive electrode active material according to one embodiment of the present invention. FIG. 2 illustrates a cross-sectional view of a reaction vessel used in one embodiment of the present invention. FIG. 3A illustrates an exploded perspective view of a coin-type secondary battery, FIG. 3B illustrates a perspective view of the coin-type secondary battery, and FIG. 3C illustrates a cross-sectional perspective view thereof. FIG. 4A illustrates an example of a cylindrical secondary battery. FIG. 4B illustrates an example of a cylindrical secondary battery. FIG. 4C illustrates an example of a plurality of cylindrical secondary batteries. FIG. 4D illustrates an example of a power storage system including a plurality of cylindrical secondary batteries. FIGS. 5A and 5B illustrate an example of a secondary battery, and FIG. 5C illustrates the internal structure of the secondary battery. FIGS. 6A to 6C illustrate an example of a secondary battery. FIGS. 7A and 7B illustrate the external appearance of a secondary battery. FIGS. 8A to 8C illustrate a method for manufacturing a secondary battery. FIGS. 9A to 9C illustrate an example of a battery pack. FIGS. 10A and 10B illustrate an example of a secondary battery. FIGS. 11A to 11C illustrate an example of a secondary battery. FIGS. 12A and 12B are diagrams illustrating an example of a secondary battery. FIG. 13A is a perspective view of a battery pack illustrating one embodiment of the present invention, FIG. 13B is a block diagram of the battery pack, and FIG. 13C is a block diagram of a vehicle having a motor. FIGS. 14A to 14D are diagrams illustrating an example of a transportation vehicle. FIGS. 15A and 15B are diagrams illustrating a power storage device according to one embodiment of the present invention. FIG. 16A is a diagram illustrating an electric bicycle, FIG. 16B is a diagram illustrating a secondary battery for the electric bicycle, and FIG. 16C is a diagram illustrating an electric motorcycle. FIGS. 17A to 17D are diagrams illustrating an example of an electronic device. FIGS. 18A and 18B are diagrams illustrating charge-discharge cycle characteristics of a secondary battery at 25° C., and FIGS. 19A and 19B are diagrams illustrating charge-discharge cycle characteristics of a secondary battery at 45° C.

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various modifications can be made to the embodiments and details. Furthermore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0026] (Embodiment 1) In this embodiment, an example of a method for producing a positive electrode active material 200A in which an additive element is added to a compound containing at least nickel, cobalt, and manganese obtained by a coprecipitation method is described with reference to Fig. 1. Note that the flow diagram shown in Fig. 1 shows the order of elements connected by lines, but does not show the time timing between elements that are not directly connected by lines.

[0027] In this embodiment, a process is used in which a coprecipitated precursor having Co, Ni, Mn, or Al present in one particle is prepared by a coprecipitation method, the coprecipitated precursor is mixed with a Li salt, and then heated twice, and a calcium compound is then added.

[0028] As shown in FIG. 1 , a cobalt source 801, a nickel source 802, a manganese source 803, and an aluminum source 804 are prepared; an alkaline solution is prepared as aqueous solution 893; and chelating agents are prepared as aqueous solutions 892 and 894. The cobalt source 801, the nickel source 802, the manganese source 803, and the aluminum source 804 are mixed to prepare an aqueous solution 890. The aqueous solution 890 and the aqueous solution 892 are mixed to prepare a mixed solution 901. The mixed solution 901, the aqueous solution 893, and the aqueous solution 894 are reacted to produce a compound containing at least nickel, cobalt, manganese, and aluminum. This reaction may be referred to as a neutralization reaction, an acid-base reaction, or a coprecipitation reaction, and the compound containing at least nickel, cobalt, manganese, and aluminum (nickel compound 805 in FIG. 1 ) may be referred to as a precursor of a nickel-cobalt-manganese-aluminum compound. The reaction occurring by performing the process surrounded by the dashed line in FIG. 1 may also be referred to as a coprecipitation reaction.

[0029] <Cobalt aqueous solution> As the cobalt aqueous solution used in the cobalt source 801, cobalt sulfate (for example, CoSO ４ ), cobalt chloride (e.g., CoCl２ ) or cobalt nitrate (e.g., Co(NO ３ ) ２ ), cobalt acetate (e.g., C ４ H ６ CoO ４ ), cobalt alkoxide, or organic cobalt complex, or an aqueous solution containing a hydrate thereof. Alternatively, an organic acid of cobalt, such as cobalt acetate, or a hydrate thereof, may be used instead of the aqueous cobalt solution. In this specification, the organic acid includes citric acid, oxalic acid, formic acid, and butyric acid in addition to acetic acid.

[0030] For example, an aqueous solution of these compounds in pure water can be used. Because the cobalt aqueous solution is acidic, it can be referred to as an acid aqueous solution. The cobalt aqueous solution can also be referred to as a cobalt source in the manufacturing process of the positive electrode active material.

[0031] <Aqueous Nickel Solution> The aqueous nickel solution used in the nickel source 802 may be an aqueous solution of nickel sulfate, nickel chloride, nickel nitrate, or a hydrate thereof. Alternatively, an aqueous solution of an organic acid salt of nickel, such as nickel acetate, or a hydrate thereof may be used. Alternatively, an aqueous solution of nickel alkoxide or an organic nickel complex may be used.

[0032] <Manganese Aqueous Solution> The manganese aqueous solution used in the manganese source 803 may be an aqueous solution of a manganese salt, such as manganese sulfate, manganese chloride, manganese nitrate, or a hydrate thereof. Alternatively, an aqueous solution of an organic acid salt of manganese, such as manganese acetate, or a hydrate thereof may be used. Alternatively, an aqueous solution of a manganese alkoxide or an organic manganese complex may be used.

[0034] <Aluminum aqueous solution> The aluminum aqueous solution used for the aluminum source 804 can be an aqueous solution of aluminum sulfate, aluminum chloride, aluminum nitrate, or a hydrate thereof. Alternatively, an aqueous solution of an organic salt of aluminum, such as aluminum acetate, or a hydrate thereof can be used. Alternatively, an aqueous solution of aluminum alkoxide or an organic aluminum complex can be used.

[0033] The aqueous solution 890 can be prepared by preparing and then mixing the above-mentioned cobalt aqueous solution, nickel aqueous solution, manganese aqueous solution, and aluminum aqueous solution. Alternatively, for example, nickel sulfate, cobalt sulfate, manganese sulfate, and aluminum sulfate can be mixed and then mixed with water to prepare the aqueous solution 890.

[0035] In this embodiment, nickel sulfate, cobalt sulfate, manganese sulfate, and aluminum sulfate are weighed out in desired amounts and mixed together. Aqueous solution 890, which is a mixture of nickel sulfate, cobalt sulfate, manganese sulfate, and aluminum sulfate, is mixed with aqueous solution 892 to prepare mixed solution 901. Aqueous solutions 892 and 894 are used that function as chelating agents, but are not particularly limited thereto and may be pure water.

[0036] <Alkaline Solution> Examples of alkaline solutions used in the aqueous solution 893 include aqueous solutions containing sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia. For example, aqueous solutions in which these are dissolved in pure water can be used. An aqueous solution in which multiple types selected from sodium hydroxide, potassium hydroxide, and lithium hydroxide are dissolved in pure water may also be used.

[0037] <Reaction Conditions> When reacting the mixed solution 901 and the aqueous solution 893 according to the coprecipitation method, the pH of the reaction system is adjusted to 9.0 or more and 12.0 or less, preferably 10.5 or more and 11.5 or less. For example, when the aqueous solution 894 is placed in a reaction tank and the mixed solution 901 and the aqueous solution 893 are added dropwise to the reaction tank, the pH of the aqueous solution in the reaction tank should be maintained within the above-mentioned range. The same applies when the aqueous solution 893 is placed in a reaction tank and the aqueous solution 894 and the mixed solution 901 are added dropwise. The same applies when the mixed solution 901 is placed in a reaction tank and the aqueous solution 894 and the aqueous solution 893 are added dropwise to the reaction tank. The drop rate of the aqueous solution 893, the aqueous solution 894, or the mixed solution 901 should be adjusted to 0.1 mL / min or more and 0.8 mL / min or less, which is preferable for easy control of the pH conditions. The reaction tank has at least a reaction vessel.

[0038] The aqueous solution in the reaction vessel is preferably stirred using a stirring means. The stirring means has a stirrer or stirring blades. Two to six stirring blades can be provided. For example, when four stirring blades are used, they are preferably arranged in a cross shape when viewed from above. The rotation speed of the stirring means is preferably 800 rpm to 1200 rpm.

[0039] The temperature of the reaction vessel is adjusted to be 50° C. or higher and 90° C. or lower. The dropping of the aqueous solution 893, the aqueous solution 894, or the mixed solution 901 may be started after the temperature has reached the appropriate temperature.

[0040] The inside of the reaction vessel is preferably an inert atmosphere. For example, when a nitrogen atmosphere is used, nitrogen gas is preferably introduced at a flow rate of 0.5 L / min to 2 L / min.

[0041] The reactor may also be equipped with a reflux condenser, which allows nitrogen gas to escape from the reactor and water to return to the reactor.

[0042] After the above reaction, a compound containing at least nickel, cobalt, manganese, and aluminum is precipitated in the reaction vessel. Filtration is performed to recover the compound containing at least nickel, cobalt, manganese, and aluminum. During filtration, it is preferable to wash the reaction product precipitated in the reaction vessel with pure water, and then add an organic solvent with a low boiling point (e.g., acetone) before performing the filtration.

[0043] The filtered compound containing at least nickel, cobalt, manganese, and aluminum may be further dried, for example, at a temperature of 60° C. to 120° C. in vacuum for 0.5 to 12 hours. In this manner, a compound containing at least nickel, cobalt, manganese, and aluminum can be obtained.

[0044] The compound containing at least nickel, cobalt, manganese, and aluminum obtained by the above reaction is obtained as secondary particles formed by aggregation of primary particles. In this specification, the term "primary particle" refers to the smallest particle (clump) without grain boundaries when observed, for example, at 5000x magnification using a scanning electron microscope (SEM). In other words, the term "primary particle" refers to the smallest particle surrounded by grain boundaries. The term "secondary particle" refers to particles (particles independent from others) formed by aggregation of the primary particles so as to share part of the grain boundaries (peripheries of the primary particles) and which are not easily separated. In other words, the secondary particles may have grain boundaries.

[0045] In this embodiment, in the compound containing at least nickel, cobalt, manganese, and aluminum obtained by the coprecipitation method, the atomic ratio of nickel, cobalt, manganese, and aluminum is appropriately adjusted to be Ni:Co:Mn:Al=8:1:0.9:0.1 or approximately therein.

[0046] Next, a lithium compound is prepared.

[0047] <Lithium Compound 806> As the lithium compound 806, Li salts such as lithium hydroxide (e.g., LiOH), lithium carbonate (e.g., Li ２ CO ３ ), or lithium nitrate (e.g., LiNO ３ ) are listed. In particular, among lithium compounds, it is preferable to use a material with a low melting point, such as lithium hydroxide (melting point 462°C). A positive electrode active material with a high proportion of nickel is more susceptible to cation mixing than lithium cobalt oxide, so the first heating 807 must be performed at a low temperature. Therefore, it is preferable to use a material with a low melting point. The lithium concentration of the positive electrode active material 200A described below can be adjusted appropriately at this stage.

[0048] In this embodiment, desired amounts of each component are weighed and mixed with a compound containing at least nickel, cobalt, manganese, and aluminum and a lithium compound to obtain a mixture 904. The mixing is performed using a mortar or a stirring mixer.

[0049] Next, the first heating 807 is performed. As a firing device for performing the first heating 807, an electric furnace or a rotary kiln furnace can be used.

[0050] The first heating temperature is preferably higher than 400° C. and equal to or lower than 1050° C. The first heating time is preferably 1 hour or more and 20 hours or less.

[0051] Next, the secondary particles are crushed or pulverized in a mortar to break up any clumps of particles, and then recovered. Furthermore, classification may be performed using a sieve. In this embodiment, a crucible made of aluminum oxide (also called alumina) with a purity of 99.9% is used. Furthermore, when recovering the material after heating, it is preferable to transfer the material from the crucible to a mortar and then recover it, since this prevents impurities from being mixed into the material. Furthermore, it is preferable that the mortar be made of a material that does not easily release impurities. Specifically, it is preferable to use a mortar made of alumina with a purity of 90% or more, preferably 99% or more.

[0052] Next, the second heating 808 is performed. As a firing device for performing the second heating 808, an electric furnace or a rotary kiln furnace can be used.

[0053] The second heating temperature is preferably higher than 400°C and equal to or lower than 1050°C. The second heating time is preferably 1 hour or more and 20 hours or less. The second heating is preferably performed in an oxygen atmosphere, and it is particularly preferable to perform the second heating while supplying oxygen. For example, the flow rate is 10 L / min per 1 L of the furnace volume. Specifically, the mixture 904 is preferably heated with the container containing the mixture 904 covered.

[0054] The secondary particles are then crushed or pulverized in a mortar to break up any agglomerated particles, and then recovered.Furthermore, the particles may be classified using a sieve.

[0055] Then, the obtained mixture 905 is mixed with a compound 910 as a second additional element. In this embodiment, calcium is used as the second additional element, and a calcium compound is used as the compound 910.

[0056] <Calcium Compound> Examples of the compound 910 include calcium oxide, calcium carbonate, and calcium hydroxide. In this embodiment, calcium carbonate (CaCO ３ ) is used. The amount of compound 910 is determined by the practitioner, taking into consideration the composition of the lithium compound and the compound containing at least nickel, cobalt, manganese, and aluminum, and the calcium is preferably added in a desired amount. Calcium is preferably added by weighing in a range of 0.5 atomic % to 3 atomic % relative to the compound containing nickel, cobalt, manganese, and aluminum.

[0057] Thereafter, a third heating 809 is performed. The third heating temperature is at least higher than the first heating temperature, and is preferably higher than 700°C and not higher than 1050°C. The third heating time is shorter than that of the second heating, and is preferably 0.5 hours or more and not higher than 20 hours. The third heating is preferably performed in an oxygen atmosphere, and it is particularly preferable to perform the third heating while supplying oxygen. For example, the flow rate is 10 L / min per 1 L of the furnace volume. Specifically, the heating is preferably performed with the container containing the mixture 905 covered.

[0058] Next, the secondary particles are crushed or pulverized in a mortar to loosen the particles, and then collected. The particles may be further classified using a sieve. The crushing step can further uniformize the particle size and / or shape of the positive electrode active material 200A.

[0059] The above steps can produce the positive electrode active material 200A. The positive electrode active material 200A obtained by the above steps is an NCM to which Al and Ca are added, and is therefore sometimes called NCMACa.

[0060] This embodiment mode can be freely combined with other embodiment modes.

[0061] Embodiment Mode 2 In this embodiment mode, a coprecipitation apparatus for performing the coprecipitation method in the manufacturing method of Embodiment Mode 1 will be described below.

[0062] The coprecipitation synthesis apparatus 170 shown in FIG. 2 includes a reaction tank 171, which includes a reaction vessel. A separable flask is preferably used at the bottom of the reaction vessel, and a separable cover is preferably used at the top. The separable flask may be cylindrical or round. In the case of a cylindrical flask, the separable flask has a flat bottom. The atmosphere in the reaction tank 171 can be controlled using at least one inlet of the separable cover. For example, the atmosphere preferably contains nitrogen. In this case, it is preferable to flow nitrogen into the reaction tank 171. It is also preferable to bubble nitrogen through the aqueous solution 192 in the reaction tank 171. The coprecipitation synthesis apparatus 170 may include a reflux condenser connected to at least one inlet of the separable cover. This reflux condenser can discharge atmospheric gas, such as nitrogen, from the reaction tank 171 and return water to the reaction tank 171. The atmosphere in the reaction tank 171 only needs to have an airflow of a sufficient amount to discharge gases generated by the thermal decomposition reaction resulting from the heat treatment.

[0063] 1 and 2, the procedure of the coprecipitation method enclosed by the chain line in FIG. 1 will be described.

[0064] First, an aqueous solution 894 (chelating agent) is placed in the reaction tank 171, and then the mixed solution 901 and the aqueous solution 893 (alkaline solution) are added dropwise to the reaction tank 171. The aqueous solution 192 in Fig. 2 shows the state when the addition has started. The aqueous solution 894 may be referred to as a "charged solution." The charged solution may also be referred to as an "adjusted solution," and may refer to the aqueous solution before the reaction, i.e., the aqueous solution in its initial state.

[0065] Other components of the coprecipitation synthesis apparatus 170 shown in Fig. 2 will be described. 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.

[0066] The stirring unit 172 can stir the aqueous solution 192 in the reaction tank 171, and further has a stirring motor 173 as a power source for rotating the stirring unit 172. The stirring unit 172 has paddle-type stirring blades (referred to as paddle blades), and the paddle blades may have two to six blades, and the blades may have an inclination of 40 degrees to 70 degrees.

[0067] The thermometer 174 can measure the temperature of the aqueous solution 192. The temperature of the reaction tank 171 can be controlled using a thermoelectric element so that the temperature of the aqueous solution 192 is constant. An example of a thermoelectric element is a Peltier element. Although not shown, a pH meter is also placed in the reaction tank 171, and can measure the pH of the aqueous solution 192.

[0068] Each tank can store a different aqueous raw material solution. For example, each tank can be filled with a mixed solution 901 and an aqueous solution 893. A tank filled with an aqueous solution 894, which functions as a fill-up liquid, may also be prepared. Each tank is provided with a pump, and the aqueous raw material solution can be dripped into the reaction tank 171 through the pipes by using the pump. The amount of aqueous raw material solution dripped, i.e., the amount of solution sent, can be controlled by each pump. In addition to the pump, a valve may be provided in the pipe 176 to control the amount of aqueous raw material solution dripped, i.e., the amount of solution sent.

[0069] The control device 190 is electrically connected to the stirring motor 173, the thermometer 174, the pump 177, the pump 182, and the pump 188, and can control the rotation speed of the stirring unit 172, the temperature of the aqueous solution 192, and the amount of each raw aqueous solution dropped.

[0070] The rotation speed of the stirring unit 172, specifically the rotation speed of the paddle blades, is preferably, for example, 800 rpm to 1200 rpm. The stirring is preferably performed while heating the aqueous solution 192 to 50°C to 90°C. During this process, the mixed solution 901 is preferably dripped into the reaction tank 171 at a constant rate. Of course, the rotation speed of the paddle blades is not limited to a constant value and can be adjusted as appropriate. For example, the rotation speed can be changed depending on the amount of liquid in the reaction tank 171. The dripping speed of the mixed solution 901 can also be adjusted. The dripping speed can be adjusted to maintain a constant pH in the reaction tank 171. Alternatively, the dripping speed can be controlled so that the mixed solution 901 is dripped first, and then the aqueous solution 892 is dripped when the pH value deviates from the desired value. The pH value is preferably set to 9.0 to 11.0, preferably 10.0 to 10.5.

[0071] After the above steps, a reaction product precipitates in the reaction tank 171. The reaction product has compounds containing at least nickel, cobalt, manganese, and aluminum. This reaction can be referred to as coprecipitation, and this step may be referred to as a coprecipitation step.

[0072] This embodiment mode can be freely combined with other embodiment modes.

[0073] (Embodiment 3) An example of a coin-type secondary battery will be described. Fig. 3A is an exploded perspective view of a coin-type (single-layer flat) secondary battery, Fig. 3B is an external view, and Fig. 3C is a cross-sectional view thereof. Coin-type secondary batteries are mainly used in small electronic devices. In this specification, coin-type batteries include button-type batteries.

[0074] 3A is a schematic diagram that shows the overlapping of components (upper and lower relationships and positional relationships) for ease of understanding, and therefore, FIGS. 3A and 3B are not completely corresponding views.

[0075] In Fig. 3A, a positive electrode 304, a separator 310, a negative electrode 307, a spacer 322, and a washer 312 are stacked. These are sealed by a negative electrode can 302 and a positive electrode can 301. Note that a gasket for sealing is not shown in Fig. 3A. The spacer 322 and the washer 312 are used to protect the inside or to fix the position inside the can when the positive electrode can 301 and the negative electrode can 302 are crimped together. The spacer 322 and the washer 312 are made of stainless steel or an insulating material.

[0076] A positive electrode 304 has a laminated structure in which a positive electrode active material layer 306 is formed on a positive electrode current collector 305 .

[0077] To prevent short-circuiting between the positive electrode and the negative electrode, a separator 310 and a ring-shaped insulator 313 are arranged so as to cover the side and top surfaces of the positive electrode 304. The separator 310 has a larger planar area than the positive electrode 304.

[0078] FIG. 3B is a perspective view of the completed coin-type secondary battery.

[0079] In the coin-type secondary battery 300, a positive electrode can 301, which also serves as a positive electrode terminal, and a negative electrode can 302, which also serves as a negative electrode terminal, are insulated and sealed by a gasket 303 made of polypropylene. 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 the positive electrode current collector. 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 the negative electrode current collector. The negative electrode 307 is not limited to a laminated structure, and may be made of lithium metal foil or a lithium-aluminum alloy foil.

[0080] It is to be noted that the positive electrode 304 and the negative electrode 307 used in the coin-type secondary battery 300 each only need to have an active material layer formed on one side.

[0081] The positive electrode can 301 and the negative electrode can 302 can be made of metals resistant to corrosion by liquid electrolytes, such as nickel, aluminum, and titanium, or alloys of these metals and other metals (e.g., stainless steel). Furthermore, to prevent corrosion by the liquid electrolyte, nickel and aluminum coatings are preferred. 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.

[0082] These negative electrode 307, positive electrode 304, and separator 310 are immersed in a liquid electrolyte, and as shown in FIG. 3C , the positive electrode 304, separator 310, negative electrode 307, and negative electrode can 302 are stacked in this order with the positive electrode can 301 facing downwards, and the positive electrode can 301 and the negative electrode can 302 are crimped together via a gasket 303, thereby producing a coin-shaped secondary battery 300.

[0083] The above-described configuration allows the coin-type secondary battery 300 to have a high capacity, a high charge / discharge capacity, and excellent cycle characteristics. Note that, when a secondary battery having a solid electrolyte layer between the negative electrode 307 and the positive electrode 304 is used, the separator 310 may be unnecessary.

[0084] [Cylindrical Secondary Battery] An example of a cylindrical secondary battery will be described with reference to Fig. 4A. As shown in Fig. 4A, a cylindrical secondary battery 616 has a positive electrode cap (battery lid) 601 on the top surface and a battery can (external can) 602 on the side and bottom surfaces. The positive electrode cap 601 and the battery can (external can) 602 are insulated by a gasket (insulating packing) 610.

[0085] 4B is a schematic diagram showing a cross section of a cylindrical secondary battery. The cylindrical secondary battery shown in FIG. 4B has a positive electrode cap (battery lid) 601 on the top surface and a battery can (external can) 602 on the side and bottom surfaces. The positive electrode cap and battery can (external can) 602 are insulated by a gasket (insulating packing) 610.

[0086] A battery element is provided inside a hollow cylindrical battery can 602, which includes a strip-shaped positive electrode 604 and a negative electrode 606 wound with a separator 605 sandwiched between them. Although not shown, the battery element is wound around a central axis. One end of the battery can 602 is closed and the other end is open. The battery can 602 can be made of nickel, aluminum, titanium, or alloys thereof, or alloys of these with other metals (e.g., stainless steel), which are corrosion-resistant to liquid electrolytes. Furthermore, to prevent corrosion by the liquid electrolyte, the battery can 602 is preferably coated with nickel or aluminum. Inside the battery can 602, the wound battery element, which includes the positive electrode, negative electrode, and separator, is sandwiched between a pair of opposing insulating plates 608 and 609. A nonaqueous electrolyte (not shown) is poured into the battery can 602, which contains the battery element. The nonaqueous electrolyte may be the same as that used in coin-type secondary batteries.

[0087] Since the positive and negative electrodes used in a cylindrical storage battery are wound, it is preferable to form active materials on both sides of the current collector. While the secondary battery 616 shown in Figures 4A to 4D has a cylinder whose height is greater than its diameter, this is not limiting. A secondary battery whose diameter is greater than its height may also be used. This configuration, for example, can reduce the size of the secondary battery.

[0088] By using the positive electrode active material 200A described in Embodiment 1 for the positive electrode 604, the cylindrical secondary battery 616 can have a large capacity, a large charge / discharge capacity, and excellent cycle characteristics.

[0089] 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 aluminum. The positive electrode terminal 603 is resistance-welded to a 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 cuts off the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the increase in internal pressure of the battery exceeds a predetermined threshold. The PTC element 611 is a thermosensitive resistor whose resistance increases as the temperature increases, and the increased resistance limits the amount of current to prevent abnormal heat generation. The PTC element is made of barium titanate (BaTiO ３ )-based semiconductor ceramics can be used.

[0090] 4C shows an example of a power storage system 615. The power storage system 615 has a plurality of secondary batteries 616. The positive electrodes of each secondary battery are in contact with and electrically connected to conductors 624 separated by insulators 625. The conductors 624 are electrically connected to a control circuit 620 via wiring 623. The negative electrodes of each secondary battery are electrically connected to the control circuit 620 via wiring 626. A protection circuit that prevents overcharging or overdischarging can be used as the control circuit 620.

[0091] 4D shows an example of a power storage system 615. The power storage system 615 has a plurality of secondary batteries 616, which are sandwiched between a conductive plate 628 and a conductive plate 614. The plurality of secondary batteries 616 are electrically connected to the conductive plate 628 and the conductive plate 614 by wiring 627. The plurality of secondary batteries 616 may be connected in parallel, in series, or in series after being connected in parallel. By configuring the power storage system 615 to have a plurality of secondary batteries 616, it is possible to extract a large amount of power.

[0092] A plurality of secondary batteries 616 may be connected in parallel and then further connected in series.

[0093] A temperature control device may be provided between the multiple secondary batteries 616. When the secondary batteries 616 are overheated, they can be cooled by the temperature control device, and when the secondary batteries 616 are too cold, they can be heated by the temperature control device. This makes it difficult for the performance of the power storage system 615 to be affected by the outside air temperature.

[0094] 4D , the power storage system 615 is electrically connected to a control circuit 620 via wiring 621 and wiring 622. The wiring 621 is electrically connected to the positive electrodes of the plurality of secondary batteries 616 via a conductive plate 628, and the wiring 622 is electrically connected to the negative electrodes of the plurality of secondary batteries 616 via a conductive plate 614.

[0095] [Another Example of Secondary Battery Structure] An example of the structure of a secondary battery will be described with reference to FIGS. 5 and 6. FIG.

[0096] The secondary battery 913 shown in FIG. 5A has a wound body 950 provided with terminals 951 and 952 inside a housing 930. The wound body 950 is immersed in a liquid electrolyte inside the housing 930. The terminal 952 contacts the housing 930, and the terminal 951 is not in contact with the housing 930 due to the use of an insulating material. Note that in FIG. 5A, the housing 930 is shown separated for convenience, but in reality, the wound body 950 is covered by the housing 930, and the 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.

[0097] 5B, the housing 930 shown in Fig. 5A may be formed of a plurality of materials. For example, the secondary battery 913 shown in Fig. 5B has a housing 930a and a housing 930b bonded together, and a wound body 950 is provided in the area surrounded by the housing 930a and the housing 930b.

[0098] The housing 930a can be made of an insulating material such as organic resin. In particular, using organic resin on the surface on which the antenna is formed can prevent the secondary battery 913 from blocking the electric field. Note that if the housing 930a does not block the electric field much, the antenna may be provided inside the housing 930a. The housing 930b can be made of, for example, a metal material.

[0099] 5C shows the structure of the wound body 950. 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 sandwiched therebetween, and the laminated sheet is wound. Note that multiple layers of the negative electrode 931, the positive electrode 932, and the separator 933 may be stacked.

[0100] 6A to 6C may be used as a secondary battery 913 having a wound body 950a. The wound body 950a shown in Fig. 6A includes a negative electrode 931, a positive electrode 932, and a separator 933. The negative electrode 931 includes a negative electrode active material layer 931a. The positive electrode 932 includes a positive electrode active material layer 932a.

[0101] By using the positive electrode active material 200A described in Embodiment 1 for the positive electrode 932, the secondary battery 913 can have high capacity, high charge / discharge capacity, and excellent cycle characteristics.

[0102] The separator 933 has a width wider than the negative electrode active material layer 931 a and the positive electrode active material layer 932 a, and is wound so as to overlap the negative electrode active material layer 931 a and the positive electrode active material layer 932 a. From the standpoint of safety, it is preferable that the negative electrode active material layer 931 a be wider than the positive electrode active material layer 932 a. A wound body 950 a having such a shape is preferable due to its high safety and productivity.

[0103] 6B, the negative electrode 931 is electrically connected to a terminal 951. The terminal 951 is electrically connected to a terminal 911a. The positive electrode 932 is electrically connected to a terminal 952. The terminal 952 is electrically connected to a terminal 911b.

[0104] 6C , the wound body 950 a and the liquid electrolyte are covered by the housing 930 to form the secondary battery 913. It is preferable to provide a safety valve and an overcurrent protection element in the housing 930. The safety valve is a valve that opens when the inside of the housing 930 reaches a predetermined internal pressure to prevent the battery from exploding.

[0105] As shown in Fig. 6B, the secondary battery 913 may have multiple wound bodies 950a. Using multiple wound bodies 950a can result in a secondary battery 913 with a larger charge / discharge capacity. For other elements of the secondary battery 913 shown in Figs. 6A and 6B, the descriptions of the secondary battery 913 shown in Figs. 5A to 5C can be referred to.

[0106] 7A and 7B show examples of external views of a laminated secondary battery, which includes 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.

[0107] 8A shows an external view of a positive electrode 503 and a negative electrode 506. The positive electrode 503 has a positive electrode current collector 501, and a 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 a tab region). The negative electrode 506 has a negative electrode current collector 504, and a negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. The negative electrode 506 also has a region where the negative electrode current collector 504 is partially exposed, i.e., a tab region. The area and shape of the tab regions of the positive electrode and negative electrode are not limited to the example shown in FIG. 8A .

[0108] <Method of Manufacturing Laminated Secondary Battery> Here, an example of a method of manufacturing the laminated secondary battery whose external view is shown in FIG. 7A will be described with reference to FIGS. 8B and 8C.

[0109] First, the negative electrode 506, separator 507, and positive electrode 503 are stacked. FIG. 8B shows the stacked negative electrode 506, separator 507, and positive electrode 503. Here, an example is shown in which five pairs of negative electrodes and four pairs of positive electrodes are used. This can also be called a laminate consisting of a negative electrode, a separator, and a positive electrode. 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 example, ultrasonic welding may be used for joining. 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.

[0110] Next, the negative electrode 506 , the separator 507 and the positive electrode 503 are arranged on the outer casing 509 .

[0111] Next, as shown in Fig. 8C, the exterior body 509 is folded at the portion indicated by the dashed line. Thereafter, the outer periphery of the exterior body 509 is joined. For example, thermocompression bonding may be used for joining. At this time, an area (hereinafter referred to as an inlet) that is not joined is provided in a part (or one side) of the exterior body 509 so that a liquid electrolyte can be introduced later.

[0112] Next, a liquid electrolyte (not shown) is introduced into the inside of the exterior body 509 through an inlet provided in the exterior body 509. The introduction of the liquid electrolyte is preferably carried out under a reduced pressure atmosphere or an inert atmosphere. Finally, the inlet is joined. In this manner, the laminated secondary battery 500 can be fabricated.

[0113] By using the positive electrode active material 200A described in Embodiment 1 for the positive electrode 503, the secondary battery 500 can have a high capacity, a high charge / discharge capacity, and excellent cycle characteristics.

[0114] [Example of Battery Pack] An example of a secondary battery pack according to one embodiment of the present invention that can be wirelessly charged using an antenna will be described with reference to FIGS. 9A to 9C. FIG.

[0115] Fig. 9A is a diagram showing the appearance of secondary battery pack 531, which has a thin rectangular parallelepiped shape (also called a thick flat plate shape). Fig. 9B is a diagram illustrating the configuration of secondary battery pack 531. Secondary battery pack 531 has circuit board 540 and secondary battery 513. Label 529 is affixed to secondary battery 513. Circuit board 540 is fixed with sticker 515. Secondary battery pack 531 also has antenna 517.

[0116] The interior of the secondary battery 513 may have a structure including a wound body or a laminated body.

[0117] 9B , the secondary battery pack 531 has a control circuit 590 on a circuit board 540. The circuit board 540 is electrically connected to the terminals 514. The circuit board 540 is also electrically connected to the antenna 517, one 551 of the positive and negative leads of the secondary battery 513, and the other 552 of the positive and negative leads.

[0118] Alternatively, as shown in FIG. 9C, the device may have a circuit system 590 a provided on the circuit board 540 and a circuit system 590 b electrically connected to the circuit board 540 via the terminals 514 .

[0119] The antenna 517 is not limited to a coil shape, and may be, for example, a wire or plate shape. Furthermore, a planar antenna, an aperture antenna, a traveling wave antenna, an EH antenna, a magnetic field antenna, or a dielectric antenna may also 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 a capacitor. This allows power to be exchanged not only by electromagnetic fields and magnetic fields, but also by electric fields.

[0120] The secondary battery pack 531 includes a layer 519 between the antenna 517 and the secondary battery 513. The layer 519 has a function of, for example, shielding an electromagnetic field generated by the secondary battery 513. The layer 519 can be formed using, for example, a magnetic material.

[0121] The content of this embodiment can be freely combined with the content of other embodiment modes.

[0122] Embodiment 4 In this embodiment, an example of manufacturing an all-solid-state battery using the positive electrode active material 200A shown in Embodiment 1 will be described.

[0123] As shown in FIG. 10A , a secondary battery 400 of one embodiment of the present invention includes a positive electrode 410 , a solid electrolyte layer 420 , and a negative electrode 430 .

[0124] The positive electrode 410 includes a positive electrode current collector 413 and a positive electrode active material layer 414. The positive electrode active material layer 414 includes a positive electrode active material 411 and a solid electrolyte 421. The positive electrode active material 200A described in Embodiment 1 is used as the positive electrode active material 411. The positive electrode active material layer 414 may include a conductive additive and a binder.

[0125] Solid electrolyte layer 420 has solid electrolyte 421. Solid electrolyte layer 420 is located between positive electrode 410 and negative electrode 430, and is a region that has neither positive electrode active material 411 nor negative electrode active material 431.

[0126] The negative electrode 430 includes a negative electrode current collector 433 and a negative electrode active material layer 434. The negative electrode active material layer 434 includes a negative electrode active material 431 and a solid electrolyte 421. The negative electrode active material layer 434 may also include a conductive additive and a binder. When metallic lithium is used as the negative electrode active material 431, it is not necessary to form the material into particles. Therefore, as shown in FIG. 10B , the negative electrode 430 can be formed without the solid electrolyte 421. FIG. 10B also illustrates an example in which the negative electrode active material 431 is formed as a film using a sputtering method. Using metallic lithium for the negative electrode 430 is preferable because it can improve the energy density of the secondary battery 400.

[0127] The solid electrolyte 421 of the solid electrolyte layer 420 may be, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte.

[0128] The sulfide-based solid electrolytes include thiolithium-based (Li １０ GeP ２ S １２ , Li ３．２５ Ge ０．２５ P ０．７５ S ４ ), sulfide glass (70Li ２ S・30P ２ S ５ , 30Li ２ S・26B ２ S ３ ・44LiI, 63Li ２ S・36SiS ２ ・1Li ３ P.O. ４ , 57Li ２ S・38SiS ２ ・5Li ４ SiO ４ , 50Li ２ S・50GeS ２ ), sulfide crystallized glass (Li ７ P ３ S １１ , Li ３．２５ P０．９５ S ４ Sulfide-based solid electrolytes have the advantages of being highly conductive, being able to be synthesized at low temperatures, and being relatively soft, making it easy to maintain conductive paths even after charging and discharging.

[0129] The oxide-based solid electrolyte includes a material having a perovskite crystal structure (La ２／３−ｘ Li ３ｘ TiO ３ ), a material having a NASICON type crystal structure (Li １−Ｙ Al Ｙ Ti ２−Ｙ (P.O. ４ ) ３ ), materials having a garnet-type crystal structure (Li ７ La ３ Zr ２ O １２ ), a material having a LISICON type crystal structure (Li １４ ZnGe ４ O １６ ), LLZO(Li ７ La ３ Zr ２ O １２ ), oxide glass (Li ３ P.O. ４ -Li ４ SiO ４ , 50Li ４ SiO ４ ・50Li ３ BO ３ ), oxide crystallized glass (Li １．０７ Al ０．６９ Ti １．４６ (P.O. ４ ) ３ , Li １．５ Al ０．５ Ge １．５ (P.O. ４ ) ３ Oxide-based solid electrolytes have the advantage of being stable in the atmosphere.

[0130] Halide-based solid electrolytes include LiAlCl ４ , Li ３ InBr ６, LiF, LiCl, LiBr, and LiI. Furthermore, composite materials in which these halide-based solid electrolytes are filled into the pores of porous aluminum oxide or porous silica can also be used as solid electrolytes.

[0131] Also, different solid electrolytes may be mixed and used.

[0132] Among them, Li having a NASICON type crystal structure １＋ｘ Al ｘ Ti ２−ｘ (P.O. ４ ) ３ Since (0[x[1) (hereinafter referred to as LATP) contains aluminum and titanium, which are elements that may be contained in the positive electrode active material used in the secondary battery 400 of one embodiment of the present invention, a synergistic effect can be expected in improving cycle characteristics, which is preferable. In addition, productivity can be improved by reducing the number of steps. Note that in this specification, the NASICON-type crystal structure refers to a structure in which M ２ (XO ４ ) ３ (M: transition metal, X: S, P, As, Mo, or W), ６ Octahedron and XO ４ It refers to a structure in which tetrahedrons are arranged three-dimensionally with their vertices shared.

[0133] [Exterior Body and Shape of Secondary Battery] Various materials and shapes can be used for the exterior body of the secondary battery 400 of one embodiment of the present invention, but it is preferable that the exterior body has a function of applying pressure to the positive electrode, the solid electrolyte layer, and the negative electrode.

[0134] For example, FIG. 11 shows an example of a cell for evaluating materials for an all-solid-state battery.

[0135] 11A is a schematic cross-sectional view of the evaluation cell, which has a lower member 761, an upper member 762, and a fixing screw or wing nut 764 that fixes them together, and electrode plate 753 is pressed to fix the evaluation material by rotating a holding screw 763. An insulator 766 is provided between lower member 761 and upper member 762, both made of stainless steel. An O-ring 765 is also provided between upper member 762 and holding screw 763 to provide a tight seal.

[0136] The evaluation material is placed on electrode plate 751, surrounded by insulating tube 752, and pressed from above by electrode plate 753. An enlarged perspective view of the evaluation material and its surroundings is shown in Figure 11B.

[0137] The evaluation material is an example of a laminate of a positive electrode 750a, a solid electrolyte layer 750b, and a negative electrode 750c, and its cross-sectional view is shown in Fig. 11C. Note that the same reference numerals are used for the same parts in Figs. 11A to 11C.

[0138] The electrode plate 751 and the lower member 761, which are electrically connected to the positive electrode 750a, can be said to correspond to a positive electrode terminal. The electrode plate 753 and the upper member 762, which are electrically connected to the negative electrode 750c, can be said to correspond to a negative electrode terminal. The electrical resistance can be measured by applying pressure to the evaluation material via the electrode plate 751 and the electrode plate 753.

[0139] The secondary battery of one embodiment of the present invention preferably uses an airtight package for its exterior. For example, a ceramic package or a resin package can be used. Furthermore, the exterior is preferably sealed in a sealed atmosphere, such as in a glove box, while blocking external air.

[0140] Fig. 12A is a perspective view of a secondary battery of one embodiment of the present invention, which has an exterior body and a shape different from those in Fig. 11. The secondary battery in Fig. 12A has external electrodes 771 and 772 and is sealed in an exterior body having a plurality of package members.

[0141] 12B shows an example of a cross section taken along the dashed line in FIG. 12A. A stack including a positive electrode 750a, a solid electrolyte layer 750b, and a negative electrode 750c is enclosed and sealed within a package member 770a having a flat plate with an electrode layer 773a, a frame-shaped package member 770b, and a flat plate with an electrode layer 773b. The package members 770a, 770b, and 770c can be made of insulating materials, such as resin materials and ceramics.

[0142] The external electrode 771 is electrically connected to the positive electrode 750a via the electrode layer 773a and functions as a positive electrode terminal, while the external electrode 772 is electrically connected to the negative electrode 750c via the electrode layer 773b and functions as a negative electrode terminal.

[0143] By using the positive electrode active material 200A described in the first embodiment, an all-solid-state secondary battery having high energy density and good output characteristics can be realized.

[0144] The content of this embodiment mode can be combined with the content of other embodiment modes as appropriate.

[0145] Embodiment 5 This embodiment is an example different from the cylindrical secondary battery shown in Fig. 4D. Fig. 13C shows an example of application to an electric vehicle (EV).

[0146] The electric vehicle is equipped with first batteries 1301a and 1301b as main driving secondary batteries, and a second battery 1311 that supplies power to an inverter 1312 that starts a motor 1304. The second battery 1311 is also called a cranking battery (also called a starter battery). The second battery 1311 only needs to have high output, and does not need to have a large capacity, and the capacity of the second battery 1311 is smaller than that of the first batteries 1301a and 1301b.

[0147] The internal structure of the first battery 1301a may be a wound type shown in Fig. 5A or 6C or a stacked type shown in Fig. 7A or 7B. The first battery 1301a may use the all-solid-state battery of Embodiment 4. By using the all-solid-state battery of Embodiment 4 for the first battery 1301a, a high capacity can be achieved, safety can be improved, and the battery can be made smaller and lighter.

[0148] In this embodiment, an example is shown in which two first batteries 1301a and 1301b are connected in parallel, but three or more batteries may be connected in parallel. Furthermore, if the first battery 1301a can store sufficient power, the first battery 1301b may be omitted. By configuring a battery pack having multiple secondary batteries, it is possible to extract large amounts of power. The multiple secondary batteries may be connected in parallel, in series, or in series after being connected in parallel. A plurality of secondary batteries is also called a battery pack.

[0149] In addition, in a secondary battery for vehicle use, a service plug or circuit breaker that can cut off high voltage without using tools is provided in the first battery 1301a in order to cut off power from multiple secondary batteries.

[0150] The power of the first batteries 1301a and 1301b is mainly used to rotate the motor 1304, but also supplies power to 42V in-vehicle components (electric power steering 1307, heater 1308, defogger 1309) via the DCDC circuit 1306. When a rear motor 1317 is provided for the rear wheels, the first battery 1301a is also used to rotate the rear motor 1317.

[0151] In addition, the second battery 1311 supplies power to 14V in-vehicle components (audio 1313, power windows 1314, lamps 1315) via the DCDC circuit 1310.

[0152] The first battery 1301a will be described with reference to FIG. 13A.

[0153] FIG. 13A shows an example in which nine prismatic secondary batteries 1300 are combined into one battery pack 1415. Furthermore, nine prismatic secondary batteries 1300 are connected in series, with one electrode fixed by a fixing portion 1413 made of an insulator and the other electrode fixed by a fixing portion 1414 made of an insulator. While this embodiment shows an example in which the batteries are fixed by the fixing portions 1413 and 1414, they may also be housed in a battery housing box (also called a casing). Because it is expected that a vehicle will be subjected to external vibrations or shaking (from the road surface), it is preferable to fix multiple secondary batteries using the fixing portions 1413 and 1414 and the battery housing box. Furthermore, one electrode is electrically connected to the control circuit unit 1320 by wiring 1421. The other electrode is electrically connected to the control circuit unit 1320 by wiring 1422.

[0154] FIG. 13B shows an example of a block diagram of the battery pack 1415 shown in FIG. 13A.

[0155] The control circuit 1320 includes a switch unit 1324 including at least a switch for preventing overcharging and a switch for preventing overdischarging, a control circuit 1322 for controlling the switch unit 1324, and a voltage measurement unit for the first battery 1301a. The control circuit 1320 sets upper and lower voltage limits for the secondary battery used and limits the upper limit of the external current and the upper limit of the output current. The range between the lower and upper voltage limits of the secondary battery is within the recommended voltage range, and when the secondary battery is outside this range, the switch unit 1324 activates and functions as a protection circuit. The control circuit 1320 can also be called a protection circuit because it controls the switch unit 1324 to prevent overcharging and overdischarging. For example, if the control circuit 1322 detects a voltage that could cause overcharging, it turns off the switch unit 1324 to cut off the current. Furthermore, a PTC element may be provided in the charge / discharge path to provide a function for cutting off the current in response to an increase in temperature. The control circuit section 1320 also has an external terminal 1325 (+IN) and an external terminal 1326 (-IN).

[0156] The switch unit 1324 can be configured by combining n-channel transistors and p-channel transistors. The switch unit 1324 is not limited to a switch having a Si transistor using single crystal silicon, and may be, 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 of a power transistor having gallium oxide (x is a real number greater than 0).

[0157] The first batteries 1301a and 1301b mainly supply power to in-vehicle devices of the 42V system (high voltage system), and the second battery 1311 supplies power to in-vehicle devices of the 14V system (low voltage system). A lead-acid battery is often used as the second battery 1311 because of its cost advantage.

[0158] In this embodiment, an example in which lithium ion secondary batteries are used for both the first battery 1301a and the second battery 1311 is shown. A lead-acid battery, an all-solid-state battery, or an electric double layer capacitor may be used for the second battery 1311. 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 reductions in size and weight can be achieved.

[0159] Furthermore, regenerative energy generated by the rotation of the tire 1316 is sent to the motor 1304 via the gear 1305, and is then charged into the second battery 1311 from the motor controller 1303 and the battery controller 1302 via the control circuit unit 1321. Alternatively, the first battery 1301a is charged from the battery controller 1302 via the control circuit unit 1320. Alternatively, the first battery 1301b is charged from the battery controller 1302 via the control circuit unit 1320. In order to efficiently charge the regenerative energy, it is desirable that the first batteries 1301a and 1301b be capable of rapid charging.

[0160] 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 charging conditions in accordance with the charging characteristics of the secondary battery used, and can perform rapid charging.

[0161] Although not shown, when an external charger is connected, the charger's outlet or the charger's connection cable is electrically connected to the battery controller 1302. Power supplied from the external charger is charged to the first batteries 1301a and 1301b via the battery controller 1302. Some chargers are provided with a control circuit, and although the functions of the battery controller 1302 may not be used, it is preferable to charge the first batteries 1301a and 1301b via the control circuit unit 1320 to prevent overcharging. The control circuit unit 1320 may also be provided in the connection cable or the charger's connection cable. The control circuit unit 1320 is sometimes called an ECU (Electronic Control Unit). The ECU is connected to a CAN (Controller Area Network) provided in the electric vehicle. CAN is one of the serial communication standards used as an in-vehicle LAN. The ECU includes a microcomputer. The ECU uses a CPU or a GPU.

[0162] The external chargers installed at the charging stations are available with 100V outlets, 200V outlets, and three-phase 200V, 50kW outlets. It is also possible to charge using a contactless power supply system that receives power from external charging equipment.

[0163] When rapid charging is performed, a secondary battery that can withstand high voltage charging is desired in order to charge in a short time.

[0164] The secondary battery of this embodiment uses the positive electrode active material 200A described in Embodiment 1. Furthermore, by using graphene as a conductive additive, a secondary battery with significantly improved electrical characteristics can be realized, which suppresses capacity reduction and maintains high capacity even when the electrode layer is thickened and the amount of graphene supported is increased. This is particularly effective for secondary batteries used in vehicles, and a vehicle with a long cruising range, specifically, a cruising distance of 500 km or more per charge, can be provided without increasing the ratio of the weight of the secondary battery to the total weight of the vehicle.

[0165] In particular, the secondary battery of the present embodiment described above can increase the operating voltage of the secondary battery by using the positive electrode active material 200A shown in embodiment 1, and can increase the usable capacity as the charging voltage increases. Furthermore, by using the positive electrode active material 200A shown in embodiment 1 for the positive electrode, a secondary battery for a vehicle having excellent cycle characteristics can be provided.

[0166] Next, an example in which a secondary battery according to one embodiment of the present invention is mounted on a vehicle, typically a transportation vehicle, will be described.

[0167] Furthermore, when the secondary battery shown in any one of FIGS. 4D, 6C, and 13A is installed in a vehicle, a next-generation clean energy vehicle such as a hybrid vehicle (HV), an electric vehicle (EV), or a plug-in hybrid vehicle (PHV) can be realized. Furthermore, the secondary battery can also be installed in agricultural machinery, mopeds including electrically assisted bicycles, motorcycles, electric wheelchairs, electric carts, small or large ships, submarines, fixed-wing and rotary-wing aircraft, rockets, artificial satellites, space probes, planetary probes, and transportation vehicles such as spacecraft. The secondary battery of one embodiment of the present invention can be a high-capacity secondary battery. Therefore, the secondary battery of one embodiment of the present invention is suitable for miniaturization and weight reduction and can be suitably used in transportation vehicles.

[0168] 14A to 14D illustrate examples of transportation vehicles using one embodiment of the present invention. The automobile 2001 shown in FIG. 14A is an electric automobile using an electric motor as a power source for traveling. Alternatively, it is a hybrid automobile that can appropriately select and use an electric motor or an engine as a power source for traveling. When a secondary battery is installed in a vehicle, an example of the secondary battery described in Embodiment 3 is installed in one or more locations. The automobile 2001 shown in FIG. 14A includes a battery pack 2200, which includes a secondary battery module to which multiple secondary batteries are connected. It is preferable that the automobile further include a charge control device electrically connected to the secondary battery module.

[0169] Furthermore, the automobile 2001 can charge its secondary battery by receiving power from an external charging facility using a plug-in method or a contactless power supply method. The charging method and connector standard may be a predetermined method, such as CHAdeMO (registered trademark) or Combo. The secondary battery may be charged from a charging station installed in a commercial facility or from a household power source. For example, plug-in technology can be used to charge an electric storage device installed in the automobile 2001 using an external power supply. Charging can be performed by converting AC power to DC power via an AC-DC converter.

[0170] Although not shown, a power receiving device can be mounted on a vehicle and power can be supplied contactlessly from a ground-based power transmitting device to charge the vehicle. In the case of this contactless power supply method, by incorporating a power transmitting device into a road or an exterior wall, charging can be performed not only while the vehicle is stopped but also while the vehicle is moving. This contactless power supply method can also be used to transmit and receive power between two vehicles. Furthermore, solar cells can be installed on the exterior of the vehicle to charge the secondary battery while the vehicle is stopped and while moving. For such contactless power supply, an electromagnetic induction method or a magnetic field resonance method can be used.

[0171] 14B shows a large transport vehicle 2002 having an electrically controlled motor as an example of a transport vehicle. The secondary battery module of the transport vehicle 2002 is, for example, a four-cell unit of secondary batteries with a nominal voltage of 3.0 V to 5.0 V, with 48 cells connected in series for a maximum voltage of 170 V. Apart from the number of secondary batteries constituting the secondary battery module of the battery pack 2201, the transport vehicle 2002 has the same functions as those shown in FIG. 14A , and therefore a description thereof will be omitted.

[0172] FIG. 14C shows, as an example, a large transport vehicle 2003 having an electrically controlled motor. The secondary battery module of the transport vehicle 2003 has, for example, one hundred or more secondary batteries with a nominal voltage of 3.0 V or more and 5.0 V or less connected in series, with a maximum voltage of 600 V. By using a secondary battery whose positive electrode active material 200A described in embodiment 1 is used, a secondary battery with excellent rate characteristics and charge / discharge cycle characteristics can be manufactured, contributing to improved performance and a longer life of the transport vehicle 2003. Furthermore, except for the number of secondary batteries constituting the secondary battery module of the battery pack 2202, the same functions as those of FIG. 14A are provided, and therefore a description thereof will be omitted.

[0173] Fig. 14D shows, as an example, an aircraft 2004 having an engine that burns fuel. The aircraft 2004 shown in Fig. 14D has wheels for takeoff and landing, and can therefore be considered part of a transport vehicle, and has a battery pack 2203 that includes a secondary battery module formed by connecting multiple secondary batteries and the secondary battery module and a charge control device.

[0174] The secondary battery module of the aircraft 2004 is, for example, eight 4 V secondary batteries connected in series to produce a maximum voltage of 32 V. Apart from the number of secondary batteries constituting the secondary battery module of the battery pack 2203, it has the same functions as those in Fig. 14A, and therefore a description thereof will be omitted.

[0175] The content of this embodiment mode can be combined with the content of other embodiment modes as appropriate.

[0176] Embodiment 6 In this embodiment, an example in which a secondary battery according to one embodiment of the present invention is mounted in a building will be described with reference to FIGS. 15A and 15B.

[0177] The house illustrated in FIG. 15A includes a power storage device 2612 including a secondary battery of one embodiment of the present invention, and a solar panel 2610. The power storage device 2612 is electrically connected to the solar panel 2610 through a wiring 2611. The power storage device 2612 may also be electrically connected to a ground-mounted charging device 2604. The power obtained by the solar panel 2610 can be charged to the power storage device 2612. The power stored in the power storage device 2612 can be charged to a secondary battery included in the vehicle 2603 via the charging device 2604. The power storage device 2612 is preferably installed in an underfloor space. By installing the power storage device 2612 in the underfloor space, the space above the floor can be effectively utilized. Alternatively, the power storage device 2612 may be installed on the floor.

[0178] The power stored in the power storage device 2612 can also be supplied to other electronic devices in the house. Therefore, even when power cannot be supplied from a commercial power source due to a power outage, the power storage device 2612 of one embodiment of the present invention can be used as an uninterruptible power supply, enabling the use of electronic devices.

[0179] 15B illustrates an example of a power storage device according to one embodiment of the present invention. As illustrated in FIG. 15B , a power storage device 791 according to one embodiment of the present invention is installed in an underfloor space 796 of a building 799. The control circuit described in Embodiment 5 may be provided in the power storage device 791. The power storage device 791 can have a long lifetime by using a secondary battery in which the positive electrode active material 200A described in Embodiment 1 is used for its positive electrode.

[0180] A control device 790 is installed in the power storage device 791, and the control device 790 is electrically connected to the distribution board 703, the power storage controller 705 (also called the control device), the display 706, and the router 709 by wiring.

[0181] Electric power is sent from commercial power source 701 to distribution board 703 via service line attachment portion 710. Electric power is also sent to distribution board 703 from power storage device 791 and commercial power source 701, and distribution board 703 supplies the sent electric power to general load 707 and power storage load 708 via outlets (not shown).

[0182] The general load 707 is, for example, an electrical appliance such as a television or a personal computer, and the power storage load 708 is, for example, an electrical appliance such as a microwave oven, a refrigerator, or an air conditioner.

[0183] The power storage controller 705 includes a measurement unit 711, a prediction unit 712, and a planning unit 713. The measurement unit 711 has a function of measuring the amount of power consumed by the general load 707 and the power storage load 708 during a day (e.g., from midnight to midnight). The measurement unit 711 may also have a function of measuring the amount of power of the power storage device 791 and the amount of power supplied from the commercial power source 701. The prediction unit 712 has a function of predicting the amount of power demand to be consumed by the general load 707 and the power storage load 708 during the next day based on the amount of power consumed by the general load 707 and the power storage load 708 during the previous day. The planning unit 713 has a function of creating a plan for charging and discharging the power storage device 791 based on the amount of power demand predicted by the prediction unit 712.

[0184] The amount of power consumed by the general load 707 and the power storage load 708 measured by the measurement unit 711 can be confirmed on the display 706. It can also be confirmed on electrical appliances such as televisions and personal computers via the router 709. It can also be confirmed on portable electronic devices such as smartphones and tablets via the router 709. The amount of power demand for each time period (or each hour) predicted by the prediction unit 712 can also be confirmed on the display 706, the electrical appliances, and the portable electronic devices.

[0185] The content of this embodiment mode can be combined with the content of other embodiment modes as appropriate.

[0186] Embodiment 7 In this embodiment, an example in which a power storage device according to one embodiment of the present invention is mounted on a motorcycle or a bicycle will be described.

[0187] 16A illustrates an example of an electric bicycle using the power storage device of one embodiment of the present invention. The power storage device of one embodiment of the present invention can be applied to an electric bicycle 8700 illustrated in FIG. 16A. The power storage device of one embodiment of the present invention includes, for example, a plurality of storage batteries and a protection circuit.

[0188] The electric bicycle 8700 includes a power storage device 8702. The power storage device 8702 can supply electricity to a motor that assists a rider. The power storage device 8702 is portable and is shown in a state detached from the bicycle in FIG. 16B . The power storage device 8702 includes a plurality of built-in storage batteries 8701, which are included in the power storage device of one embodiment of the present invention, and the remaining battery charge can be displayed on a display unit 8703. The power storage device 8702 also includes a control circuit 8704 that can control charging or detect an abnormality of the secondary battery, as shown as an example in Embodiment 5. The control circuit 8704 is electrically connected to the positive and negative electrodes of the storage battery 8701. The control circuit 8704 may be provided with the small-sized solid-state secondary battery shown in FIGS. 12A and 12B. By providing the small-sized solid-state secondary battery shown in FIGS. 12A and 12B in the control circuit 8704, power can be supplied to retain data in a memory circuit included in the control circuit 8704 for a long period of time. Furthermore, by combining the positive electrode active material 200A shown in the first embodiment with a secondary battery using the positive electrode, a synergistic effect on safety can be obtained.

[0189] 16C is an example of a two-wheeled vehicle using the power storage device of one embodiment of the present invention. A scooter 8600 shown in FIG. 16C includes a power storage device 8602, a side mirror 8601, and a turn signal light 8603. The power storage device 8602 can supply electricity to the turn signal light 8603. The power storage device 8602, which includes a plurality of secondary batteries each using the positive electrode active material 200A described in Embodiment 1 for its positive electrode, can have a high capacity, which can contribute to miniaturization.

[0190] 16C can store a power storage device 8602 in an 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.

[0191] The content of this embodiment mode can be combined with the content of other embodiment modes as appropriate.

[0192] Embodiment 8 In this embodiment, an example of mounting a secondary battery according to one embodiment of the present invention in an electronic device will be described. Examples of electronic devices mounting a secondary battery include television sets (also referred to as televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also referred to as mobile phones or mobile phone devices), portable game consoles, personal digital assistants, sound players, and large game consoles typified by pachinko machines. Examples of personal digital assistants include notebook personal computers, tablet terminals, e-book readers, and mobile phones.

[0193] 17A shows an example of a mobile phone. The mobile phone 2100 includes a display portion 2102 built into a housing 2101, an operation button 2103, an external connection port 2104, a speaker 2105, and a microphone 2106. Note that the mobile phone 2100 includes a secondary battery 2107. By including the secondary battery 2107 using the positive electrode active material 200A described in Embodiment 1 for its positive electrode, a high capacity can be achieved, and a configuration that can accommodate space saving due to miniaturization of the housing can be realized.

[0194] The mobile phone 2100 can execute various application software such as mobile phone, e-mail, text browsing and creation, music playback, internet communication, and computer games.

[0195] The operation button 2103 can be provided with various functions such as time setting, power on / off operation, wireless communication on / off operation, silent mode activation / deactivation, and power saving mode activation / deactivation. For example, the functions of the operation button 2103 can be freely set by an operating system incorporated in the mobile phone 2100.

[0196] The mobile phone 2100 is also capable of performing standardized short-range wireless communication, and can also make hands-free calls by communicating with a wirelessly enabled headset, for example.

[0197] The mobile phone 2100 also includes an external connection port 2104, which allows direct data exchange with other information terminals via a connector. Charging can also be performed via the external connection port 2104. Note that charging may be performed by wireless power supply without using the external connection port 2104.

[0198] The mobile phone 2100 preferably has a sensor, such as a fingerprint sensor, a pulse sensor, a human body sensor represented by a body temperature sensor, a touch sensor, a pressure sensor, or an acceleration sensor.

[0199] FIG. 17B illustrates an unmanned aerial vehicle 2300 having a plurality of rotors 2302. The unmanned aerial vehicle 2300 is sometimes called a drone. The unmanned aerial vehicle 2300 includes a secondary battery 2301 which is one embodiment of the present invention, a camera 2303, and an antenna (not shown). The unmanned aerial vehicle 2300 can be remotely controlled via the antenna. A secondary battery using the positive electrode active material 200A described in Embodiment 1 for its positive electrode has high energy density and high safety; therefore, it can be used safely for a long period of time and is suitable as a secondary battery to be installed in the unmanned aerial vehicle 2300.

[0200] Fig. 17C shows an example of a robot. A robot 6400 shown in Fig. 17C includes 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, an obstacle sensor 6407, a movement mechanism 6408, and a computing unit.

[0201] The microphone 6402 has a function of detecting the user's voice and environmental sounds, and the speaker 6404 has a function of emitting sound. The robot 6400 can communicate with the user using the microphone 6402 and the speaker 6404.

[0202] The display unit 6405 has a function of displaying various information. The robot 6400 can display 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, which can be installed in a fixed position on the robot 6400 to enable charging and data transfer.

[0203] The upper camera 6403 and the lower camera 6406 have the function of capturing images of the surroundings of the robot 6400. Furthermore, 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 the surrounding environment and move safely using the upper camera 6403, the lower camera 6406, and the obstacle sensor 6407.

[0204] The robot 6400 includes a secondary battery 6409 according to one embodiment of the present invention and a semiconductor device or an electronic component in an internal region thereof. The secondary battery using the positive electrode active material 200A described in Embodiment 1 for its positive electrode has high energy density and high safety, and therefore can be used safely for a long period of time. Therefore, the secondary battery is suitable as the secondary battery 6409 to be mounted on the robot 6400.

[0205] 17D shows an example of a cleaning robot. The cleaning robot 6300 includes a display unit 6302 arranged on the top surface of a housing 6301, a plurality of cameras 6303 arranged on the side surface, a brush 6304, an operation button 6305, a secondary battery 6306, and various sensors. Although not shown, the cleaning robot 6300 is provided with tires and a suction port. The cleaning robot 6300 can move by itself, detect dust 6310, and suck up the dust from a suction port arranged on the bottom surface.

[0206] For example, the cleaning robot 6300 can analyze an image captured by the camera 6303 and determine the presence or absence of an obstacle, such as a wall, furniture, or a step. Furthermore, when an object, such as a wire, that may become entangled in the brush 6304 is detected through image analysis, the cleaning robot 6300 can stop the rotation of the brush 6304. The cleaning robot 6300 includes a secondary battery 6306 according to one embodiment of the present invention and a semiconductor device or an electronic component in its internal region. The secondary battery using the positive electrode active material 200A described in Embodiment 1 for its positive electrode has high energy density and high safety, and therefore can be used safely for a long period of time. Therefore, the secondary battery 6306 is suitable for use in the cleaning robot 6300.

[0207] The content of this embodiment mode can be combined with the content of other embodiment modes as appropriate.

[0208] In this example, a secondary battery including a positive electrode active material of one embodiment of the present invention was fabricated, and its characteristics were evaluated.

[0209] In this example, nickel sulfate (94.626 g), cobalt sulfate (12.650 g), manganese sulfate (9.764 g), aluminum sulfate (1.094 g), and glycine (1.689 g) were dissolved in purified water to prepare a 250 mL solution with a Ni:Co:Mn:Al ratio of 8:1:0.9:0.1 using the coprecipitation method according to Example 1. The resulting mixture and sodium hydroxide solution were then added dropwise to 300 mL of aqueous glycine solution to obtain slurry A containing a metal composite hydroxide with a pH of 10.3. Slurry A was then filtered and dried to obtain chemical mixture B of the metal composite hydroxide. Note that the chemical mixture is not simply a physical mixture of powders, but rather the result of coprecipitation from solutions containing different metals. The resulting chemical mixture B (2.05438 g) was mixed with lithium hydroxide (0.94562 g) using a planetary mixer to obtain powder mixture C. Powder mixture C contains Li １．０１ Ni ０．８ Co ０．１ Mn ０．０９ Al ０．０１ O ２ However, the amount of lithium hydroxide is ０．８ Co ０．１ Mn０．０９ Al ０．０１ (OH) ２ ) to adjust. The obtained powder mixture C was subjected to a first heat treatment at 500 ° C for 10 hours, after which it was returned to room temperature and crushed. Thereafter, a second heat treatment was performed at 800 ° C for 10 hours, after which it was returned to room temperature and crushed. Calcium carbonate (0.01314 g) was then added to the heat-treated powder C (1.28686 g), and a third heat treatment was performed at 800 ° C for 2 hours, after which it was returned to room temperature and crushed. A positive electrode active material (this example) represented by NCMACa was obtained, in which 1 atomic % of Ca was added to the total of nickel, manganese, cobalt, oxygen, and Al.

[0210] The calcium concentration in the positive electrode active material (secondary particles) obtained by the above manufacturing method is 0.1 atomic % or more and 5 atomic % or less. Note that the calcium concentration here is a value based on the amount added during the manufacturing of the secondary particles, i.e., the calcium concentration relative to the nickel compound (containing cobalt, manganese, and aluminum) that is the precursor, and may not match the actual analytical concentration. In addition, the composition of the primary particles that make up the secondary particles is Li Ｗ Ni Ｘ Co Ｙ Mn Ｚ Al Ｒ O ２ (wherein 0.89<W<1.07, X+Y+Z+R=1, and X>0, Y>0, Z>0, R>0, preferably 0.7<X<0.9, 0.05≦Y<0.2, 0.05≦Z<0.2, 0.001≦R≦0.05).

[0211] As a comparative example, nickel sulfate (94.626 g), cobalt sulfate (12.650 g), manganese sulfate (9.764 g), aluminum sulfate (1.094 g), and glycine (1.689 g) were dissolved in purified water using the coprecipitation method according to Example 1 to prepare a 250 mL solution with a Ni:Co:Mn:Al ratio of 8:1:0.9:0.1. The resulting mixture and aqueous sodium hydroxide solution were then added dropwise to 300 mL of aqueous glycine solution to obtain slurry A containing a metal composite hydroxide with a pH of 10.3. Slurry A was then filtered and dried to obtain chemical mixture B of the metal composite hydroxide. Note that the chemical mixture is not simply a physical mixture of powders, but rather the result of coprecipitation from solutions containing different metals. The resulting chemical mixture B (2.05438 g) was mixed with lithium hydroxide (0.94562 g) using a planetary mixer to obtain powder mixture C. The obtained powder mixture C was subjected to a first heat treatment at 500°C for 10 hours, and then returned to room temperature and crushed. Thereafter, the obtained powder mixture C was subjected to a second heat treatment at 800°C for 10 hours, and then returned to room temperature and crushed, to obtain a positive electrode active material (comparative example) represented by NCMA.

[0212] The particle distribution of the obtained particles was measured. The D50 (median diameter) can be measured by observation using an SEM (scanning electron microscope) or TEM, or by a particle size distribution analyzer using a laser diffraction / scattering method. In this example, a laser diffraction particle size distribution analyzer SALD-2200 manufactured by Shimadzu Corporation was used. The D50 of this example (NCMACa) measured by a particle size distribution analyzer using the laser diffraction / scattering method was 10.1 μm. On the other hand, the D50 of the comparative example (NCMA) measured by a particle size distribution analyzer using the laser diffraction / scattering method was 9.8 μm.

[0213] A plurality of coin-type battery cells were fabricated using the positive electrode active material (NCMACa) of this example, and their cycle characteristics were evaluated.

[0214] The positive electrode active material used for each sample was the positive electrode active material obtained by the method shown in embodiment 1. Acetylene black was used as the conductive additive, and they were mixed to prepare a slurry, which was then applied to an aluminum current collector.

[0215] After the slurry was applied to the current collector, the solvent was evaporated. Then, a roll press was used to apply pressure at 210 kN / m, and then a further pressure of 1467 kN / m. Heating may be performed during pressing. A positive electrode was obtained through the above process. The loading amount of the positive electrode was approximately 7 mg / cm. ２ It was decided.

[0216] The prepared positive electrode was used to prepare a coin-type battery cell of CR2032 type (diameter 20 mm, height 3.2 mm).

[0217] Lithium metal was used as the counter electrode.

[0218] The sample electrolyte was 1 mol / L lithium hexafluorophosphate (LiPF ６ Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a volume ratio of EC:DEC = 3:7 using a solvent such as PEG-1000. Vinylene carbonate (VC) was added as an additive in an amount of 2 wt % based on the total volume of the mixed solvent.

[0219] The separator was made of polypropylene having a thickness of 25 μm.

[0220] The positive electrode can and the negative electrode can were made of stainless steel (SUS).

[0221] In the evaluation of cycle characteristics, the charging voltage was 4.5 V. Measurement temperatures were 25°C and 45°C. Charging was CC / CV (0.5 C, 0.05 C cut), discharging was CC (0.5 C, 2.7 V cut), and a 10-minute rest period was provided before the next charging. In this example, 1 C was 200 mA / g.

[0222] 18A and 18B show the respective cycle characteristics when the measurement temperature is 25° C. In FIG. 18A, the vertical axis represents the discharge capacity, and in FIG. 18B, the vertical axis represents the discharge capacity retention rate.

[0223] 19A and 19B show the cycle characteristics when the measurement temperature is 45° C. In FIG. 19A, the vertical axis represents the discharge capacity, and in FIG. 19B, the vertical axis represents the discharge capacity retention rate.

[0224] In addition, in FIGS. 19A and 19B, the comparative example is NCMA.

[0225] From the results of FIG. 18B, it was confirmed that NCMACa had a higher capacity retention rate during charge cycles than NCMA of the comparative example.

[0226] 170: coprecipitation synthesis apparatus, 171: reaction tank, 172: stirring unit, 173: stirring motor, 174: thermometer, 175: tank, 176: pipe, 177: pump, 180: tank, 181: pipe, 182: pump, 186: tank, 187: pipe, 188: pump, 190: control device, 192: aqueous solution, 200A: positive electrode active material, 300: secondary battery, 301: positive electrode can, 302: negative electrode can, 303: gasket, 304: positive electrode, 305: positive electrode current collector, 306: positive electrode active material layer, 307: negative electrode, 308: negative electrode current collector, 309: negative electrode active material layer, 310: separator, 312: washer , 313: ring-shaped insulator, 322: spacer, 400: secondary battery, 410: positive electrode, 411: positive electrode active material, 413: positive electrode current collector, 414: positive electrode active material layer, 420: solid electrolyte layer, 421: solid electrolyte, 430: negative electrode, 431: negative electrode active material, 433: negative electrode current collector, 434: negative electrode active material layer, 500: secondary battery, 501: positive electrode current collector, 502: positive electrode active material layer, 503: positive electrode, 504: negative electrode current collector, 505: negative electrode active material layer, 506: negative electrode, 507: separator, 509: exterior body, 510: positive electrode lead electrode, 511: negative electrode lead electrode, 513: secondary battery, 514: terminal child, 515: sticker, 517: antenna, 519: layer, 529: label, 531: secondary battery pack, 540: circuit board, 551: one side, 552: other side, 590: control circuit, 590a: circuit system, 590b: circuit system, 601: positive electrode cap, 602: battery can, 603: positive electrode terminal, 604: positive electrode, 605: separator, 606: negative electrode, 607: negative electrode terminal, 608: insulating plate, 609: insulating plate, 611: PTC element, 613: safety valve mechanism, 614: conductive plate, 615: power storage system, 616: secondary battery, 620: control circuit, 621: wiring, 622: wiring, 6 23: Wiring, 624: Conductor, 625: Insulator, 626: Wiring, 627: Wiring, 628: Conductive plate, 700: Energy storage device, 701: Commercial power source, 703: Distribution board, 705: Energy storage controller, 706: Display, 707: General load, 708: Energy storage load, 709: Router, 710: Drop line attachment part, 711: Measurement part, 712: Prediction part, 713: Planning part, 750a: Positive electrode, 750b: Solid electrolyte layer, 750c: Negative electrode, 751: Electrode plate, 752: Insulating tube, 753: Electrode plate, 761: Lower member, 762: Upper member, 764: Wing nut, 765: O-ring,766: insulator, 770a: packaging member, 770b: packaging member, 770c: packaging member, 771: external electrode, 772: external electrode, 773a: electrode layer, 773b: electrode layer, 790: control device, 791: power storage device, 796: underfloor space, 799: building, 801: cobalt source, 802: nickel source, 803: manganese source, 804: aluminum source, 805: nickel compound, 806: lithium compound, 807: first heating, 808: second heating, 809: third heating, 890: aqueous solution, 892: aqueous solution, 893: aqueous solution, 894: aqueous solution, 901: Mixture, 904: mixture, 905: mixture, 910: compound, 911a: terminal, 911b: terminal, 913: secondary battery, 930: housing, 930a: housing, 930b: housing, 931: negative electrode, 931a: negative electrode active material layer, 932: positive electrode, 932a: positive electrode active material layer, 933: separator, 950: wound body, 950a: wound body, 951: terminal, 952: terminal, 1300: prismatic secondary battery, 1301a: battery, 1301b: battery, 1302: battery controller, 1303: motor controller, 1304: motor, 1305: gear, 1306: DCDC circuit, 1307: electric power steering, 1308: heater, 1309: defogger, 1310: DCDC circuit, 1311: battery, 1312: inverter, 1313: audio, 1314: power window, 1315: lamps, 1316: tires, 1317: rear motor, 1320: control circuit section, 1321: control circuit section, 1322: control circuit, 1324: switch section, 1325: external terminal, 1326: external terminal, 1413: fixing section, 1414: fixing section, 1415: battery pack, 1421: wiring, 1422: wiring, 2001: automobile, 2002: transport vehicle, 200 3: transport vehicle, 2004: aircraft, 2100: mobile phone, 2101: housing, 2102: display unit, 2103: operation button, 2104: external connection port, 2105: speaker, 2106: microphone, 2107: secondary battery, 2200: battery pack, 2201: battery pack, 2202: battery pack, 2203: battery pack, 2300: unmanned aerial vehicle, 2301: secondary battery, 2302: rotor, 2303: camera, 2603: vehicle, 2604: charging device, 2610: solar panel, 2611: wiring, 2612: power storage device, 6300: cleaning robot, 6301: housing,6302: Display unit, 6303: Camera, 6304: Brush, 6305: Operation button, 6306: Secondary battery, 6310: Dust, 6400: Robot, 6401: Illuminance sensor, 6402: Microphone, 6403: Upper camera, 6404: Speaker, 6405: Display unit, 6406: Lower camera, 6407: Obstacle sensor, 6408: Moving mechanism, 6409: Secondary battery, 8600: Scooter, 8601: Side mirror, 8602: Power storage device, 8603: Turn signal light, 8604: Under-seat storage, 8700: Electric bicycle, 8701: Storage battery, 8702: Power storage device, 8703: Display unit, 8704: Control circuit,

Claims

1. A method for producing a positive electrode active material, wherein an aqueous solution containing a water-soluble salt of nickel, a water-soluble salt of cobalt, a water-soluble salt of manganese, and a water-soluble salt of aluminum, and an alkaline solution are supplied to a reaction vessel, mixed inside the reaction vessel to precipitate a compound containing at least nickel, cobalt, manganese, and aluminum, heating a first mixture obtained by mixing the compound and a lithium compound at a first heating temperature, followed by disintegration or pulverization, further heating at a second heating temperature, A method for producing a positive electrode active material, comprising heating a second mixture obtained by mixing the disintegrated or pulverized first mixture and a calcium compound at a third heating temperature.

2. The method for producing a positive electrode active material according to Claim 1, wherein the third heating temperature is higher than the first heating temperature.

3. The method for producing a positive electrode active material according to Claim 1, wherein the alkaline solution is an aqueous solution containing sodium hydroxide.

4. The method for producing a positive electrode active material according to Claim 1, wherein the pH of the mixed solution obtained by mixing the aqueous solution and the alkaline solution is 9 or more and 11 or less.

5. The method for producing a positive electrode active material according to Claim 1, wherein an aqueous solution containing glycine is added when precipitating the compound by mixing the aqueous solution, the alkaline solution, and the aqueous solution containing the water-soluble salt of aluminum.

6. The method for producing a positive electrode active material according to Claim 1, wherein the composition of the first mixture is represented by Li W Ni x Co y Mn Z Al R O 2 (where 0.89 < W < 1.07, X + Y + Z + R = 1, and 0.7 < X < 0.9, 0.05 ≦ Y < 0.1, 0.05 ≦ Z < 0.1, 0.001 ≦ R < 0.05).